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  • Chemistry  (64,815)
  • Inorganic Chemistry  (6,872)
  • Industrial Chemistry
  • Seismology
  • 2020-2024  (60)
  • 1990-1994  (51,541)
  • 1950-1954  (9,272)
  • 1940-1944  (4,724)
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  • 1
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    EDP SCIENCES
    Publication Date: 2024-04-05
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 2
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    EDP SCIENCES
    Publication Date: 2024-04-05
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 3
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    EDP SCIENCES
    Publication Date: 2024-04-07
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 4
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    EDP SCIENCES
    Publication Date: 2024-04-05
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 5
    Publication Date: 2024-04-05
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 6
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    EDP SCIENCES
    Publication Date: 2024-04-08
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 7
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    EDP SCIENCES
    Publication Date: 2024-04-05
    Description: Chemistry;Materials science
    Keywords: Chemistry ; Materials science ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 8
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    EDP SCIENCES
    Publication Date: 2024-04-05
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 9
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    transcript Verlag | transcript Verlag
    Publication Date: 2024-05-13
    Description: Die Novemberrevolution von 1918/19 erschütterte die Tiefenschichten der politischen und gesellschaftlichen Ordnung der Metropole Hamburg. Diese vielschichtige Transformation wird anhand ausgewählter Akteur*innen, Institutionen und Ereignisse mit Beiträgen aus der neueren Revolutions-, Konflikt- und Kriegsforschung sowie aus der Kulturwissenschaft, der Geschichts- und Sozialwissenschaft nachgezeichnet. Die Beiträger*innen des Bandes durchleuchten die Dynamiken des revolutionären Wandels im umfassenden Dispositiv der urbanen Machtverhältnisse in ihren diskursiven Formationen: im Geschlechterverhältnis, in den Klassenverhältnissen, in der Wirtschaft, im Bildungswesen, im Film, in den Utopien und Vorstellungen der Menschen der Zeit. Die Beschreibung der dynamischen Umbrüche schließt die Nachbarstadt Altona und die Region ein und verbindet somit Lokales mit Nationalem und Globalem.
    Keywords: Revolution 1918/19 ; Hamburg ; Politik ; Gesellschaft ; Norddeutschland ; Wahlen 1919 ; Film ; Weimarer Republik ; Globalgeschichte ; Deutsche Geschichte ; Bismarck ; Metropole ; Seismologie ; Kulturgeschichte ; Geschlecht ; Stadt ; Sozialgeschichte ; Europäische Geschichte ; Geschichte des 20. Jahrhunderts ; Geschichtswissenschaft ; Politics ; Society ; North Germany ; Elections 1919 ; Weimar Republic ; Global History ; German History ; Seismology ; Cultural History ; Gender ; City ; Social History ; European History ; History of the 20th Century ; History ; thema EDItEUR::N History and Archaeology::NH History::NHD European history ; thema EDItEUR::N History and Archaeology::NH History::NHT History: specific events and topics::NHTB Social and cultural history
    Language: German
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  • 10
    Publication Date: 2024-04-05
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: We implemented an automatic procedure to download the hypocentral data of the online Bulletin of the International Seismological Centre (ISC) in order to produce in near real-time a homogeneous catalogue of the Global and EuroMediterranean instrumental seismicity to be used for forecasting experiments and other statistical analyses. For the interval covered by the reviewed ISC Bulletin, we adopt the ISC locations and convert the surface wave magnitude (Ms) and short-period body-wave magnitude (mb) as computed by the ISC to moment magnitude (Mw), using empirical relations. We merge the so obtained proxies with real Mw provided by global and EuroMediterranean moment tensor catalogues. For the most recent time interval (about 2 yr) for which the reviewed ISC Bulletin is not available, we do the same but using the preferred (prime) location provided by the ISC Bulletin and converting to Mw the Ms and mb provided by some authoritative agencies. For computing magnitude conversion equations, we use curvilinear relations defined in a previous work and the chi-square regression method that accounts for the uncertainties of both x and y variables.
    Description: H2020 EU project RISE contract n. 821115
    Description: Published
    Description: 1771-1785
    Description: OST2 Deformazione e Hazard sismico e da maremoto
    Description: JCR Journal
    Keywords: Statistical methods ; Statistical seismology ; Earthquake source observations ; Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 11
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Mineralogy includes thirteen chapters that discuss the methodology of specific mineralogical methods, the composition of minerals from different igneous rocks, and the composition of minerals from different sedimentary rocks.It contains detailed mineralogical studies from Africa, Asia, and Europe. Chapters present different scientific mineralogical methods and detailed descriptions of minerals from different magmatic and sedimentary rocks.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNV Chemistry of minerals, crystals and gems
    Language: English
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  • 12
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Benzimidazole is a comprehensive survey of the known and new methods of benzimidazole synthesis, the spectral and theoretical aspects of existing benzimidazole derivatives, and the anticancer properties of a new class of benzimidazole derivatives. This book examines aspects and newer mechanisms of benzimidazoles containing heterocyclic moiety. Chapters report on anticancer properties of benzimidazole derivatives, novel methods of synthesis of benzimidazoles, versatile nature of the benzimidazoles, spectral and theoretical studies of benzimidazole derivatives, and medicinal importance and pharmacological aspects of benzimidazole derivatives.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Language: English
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  • 13
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Green Chemistry - New Perspectives is at the frontiers of this continuously evolving interdisciplinary science, and publishes research that attempts to reduce the environmental impact of the chemical enterprise by developing a technology base that is inherently non-toxic to living things and the environment. The book covers all aspects of green chemistry, including chemical synthesis, nano synthesis, eco-friendly processes, biomass, extraction techniques, environmental remediation, and energy, making it a unique reference resource. This will continue to encourage scientists around the world to develop novel synthetic methods or improve the existing ones to circumvent some of the problems and favours all aspects of green chemistry. This book is intended for academia, professionals, scientists, as well as graduate and undergraduate students without any geographical limitations.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Language: English
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  • 14
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: This book consists of several selected chapters on important subjects in modern high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC). The content addresses aspects related to both improvements in the mainstream HPLC/UPLC technology and utilization, as well as developments of exploratory new materials and equipment. The book presents useful details about the presented subjects as well as describes new applications and/or relevant case studies for each subject. It is addressed to a large audience of analytical chemists involved in separation science. Each chapter is authored by scientists with considerable field and academic experience.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Language: English
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  • 15
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Recent Advances in Chemical Kinetics provides a comprehensive overview of several types of chemical reactions. It includes six chapters that discuss solvent catalysis, customized flow reactors, p-conjugation in kinetics, kinetics of autoxidation, molecular chameleon for cations and anions, and internal clocks of atoms.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry
    Language: English
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  • 16
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Redox reactions are involved in biochemistry, energy, corrosion, and much more. In both biology and electrochemistry, the redox reaction is complex and varied. For example, redox shuttles in supercapacitors show aspects of molecular electrochemistry applied to electrode porosity. In pseudocapacitors, the formalism associated with their electrochemical response requires investigation and formalism. Similarly, the simple definition of redox potential opens fundamental questions about its measurement in solutions without supporting salts. This book illustrates the variety of redox reactions in its examination of the importance of redox molecules in the development of new electrical energy storage devices.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRH Electrochemistry and magnetochemistry
    Language: English
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  • 17
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: We are living in a critical time, both for humanity and the planet, which has led us to look for more sustainable formulas to interact with the environment. One of the important changes in the design and operation of chemical processes is the search for environmentally friendly technologies. Supercritical carbon dioxide has been revealed as a promising environmentally friendly solvent that is energy efficient, selective and capable of reducing waste, making it a promising alternative to conventional organic solvents. However, reliable and versatile mathematical models of phase equilibrium thermodynamics are needed for the use of supercritical carbon dioxide in process design and viability studies. This book reviews experimental procedures for obtaining high-pressure phase equilibria data and describes the phase diagrams of binary mixtures and some thermodynamic models capable of determining the conditions of phase equilibria at high pressures. These concepts are applied to the components of the transesterification reaction of rac-2-pentanol with a vinyl ester, which is important in the pharmaceutical industry because (S)-2-pentanol can be obtained as a reaction product. This product is a key intermediate in the synthesis of drugs against Alzheimer’s disease.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry
    Language: English
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  • 18
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: In recent decades, artificial porous structures have attracted increasing enthusiasm from researchers inspired by the fascinating molecular pores in nature and their unique biological functions. Although substantial achievements in porous materials have been realized, the construction of topologically designed pores is still challenging. Recently, the emergence of covalent organic frameworks (COFs), which are constructed based on organic and polymer chemistry, has made it possible to design artificial pores with controlled pore size, topology and interface properties. COFs are crystalline porous materials constructed by the precise reticulation of organic building blocks via dynamic covalent bonds. Distinct from non-covalent interactions which tend to produce isostructures, covalent bonds enable accurate pore design owing to their predetermined reaction pathways. In addition, the appropriate polycondensation of organic building units enables the formation of extended two-dimensional (2D) and three-dimensional (3D) polymer architectures with periodically ordered skeletons and well-defined pores. With their large surface area, tailorable structures, and tunable chemistry, COFs are regarded as potentially superior candidates for various applications including catalysis, energy storage and conversion, mass transport and biotechnology. This book examines the historic achievement of COFs, providing clear and comprehensive guidance for researchers on their structural design, synthetic protocols and functional exploration.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Language: English
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  • 19
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Fluoride covers a continuum of topics that are frequently studied in the broad area of fluoride (F) research. It provides an overview of the primary sources of environmental fluoride in typical high-fluoride environments and demonstrates the transitions and transformations that emerge and culminate in hydro-geochemical interactions that result in fluoride-fouling of large portions of the world’s water and agricultural resources. This way, the book pinpoints the connection between F enrichment of water sources and the prevalence of endemic fluorosis in certain areas of the world. In order to contribute to a better understanding of the global fluoride problem, new fluoride detection and quantification technologies are proposed with an in-depth analysis of emerging trends in the use of portable user-friendly devices in point-of-use measurements of water fluoride. This has been presented against the backdrop of a robust overview of traditional fluoride quantification methodologies that are still in wide application among the scientific communities. In addressing fluoride toxicities, which are not limited to dental and skeletal dilapidations, the authors have explored the role of natural antioxidants in ameliorating physiological fluoride-induced noxious effects in mammalian systems. Nonetheless, since community dependence on high-fluoride water due to a lack of alternative clean water sources remains to be the principal pathway of human fluoride over-exposure, a review chapter on F mitigation techniques applied all over the world is incorporated aiming at providing a succinct overview of water defluoridation techniques and strategies being used to combat the impacts of human F overexposure around the globe. Since every cloud has a silvery lining, the possibility of using ammonium fluorides as a novel reagent in mineral processing has been considered convenient industrial fluorinating agents, which present the possibility of complete regeneration that is not afforded by the reagents presently used in decomposing silicon component of the ores.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNK Inorganic chemistry
    Language: English
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  • 20
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: This book discusses the chemistry and applications of pyridine derivatives. The library of pyridine derivatives is growing steadily with numerous synthetic analogues already described and the identification of new, naturally occurring pyridine-based compounds. The book includes ten chapters organized into two parts. The first part focuses on the numerous types of reactions that arise from pyridine derivatives. The second part examines the pharmaceutical applications of pyridine derivatives as well as their usefulness as sensors for metal cations and extracting agents for platinum group metals.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Language: English
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  • 21
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: The book discusses multiple issues associated with modern dosimetry in physics and treatment planning and how investigators from diverse world centers and institutions approach problem-solving in these important areas. It examines topics including pretreatment validation and factors affecting reference dosimetry. It also addresses unique issues affecting pediatric populations as well as the modern role of thermoluminescence validation. Several chapters discuss intensity modulation, including defining modern problems associated with both treatment planning and the definition of tumor and normal tissue contours. Furthermore, the book examines the role of imaging as both a vehicle to define tumor targets and normal tissue as well as a tool for dose validation.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRL Nuclear chemistry, photochemistry and radiation
    Language: English
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  • 22
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: The book comprises 14 chapters covering all the issues related to water desalination. These chapters emphasize the relationship between problems encountered with the use of feed water, the processes developed to address them, the operation of the required plants and solutions actually implemented. This compendium will assist designers, engineers and investigators to select the process and plant configuration that are most appropriate for the particular feed water to be used, for the geographic region considered, as well as for the characteristics required of the treated water produced. This survey offers a comprehensive, hierarchical and logical assessment of the entire desalination industry. It starts with the worldwide scarcity of water and energy, continues with the thermal - and membrane-based processes and, finally, presents the design and operation of large and small desalination plants. As such, it covers all the scientific, technological and economical aspects of this critical industry, not disregarding its environmental and social points of view. One of InTech's books has received widespread praise across a number of key publications. Desalination, Trends and Technologies (Ed. Schorr, M. 2011) has been reviewed in Corrosion Engineering, Science & Technology – the official magazine for the Institute of Materials, Minerals & Mining, and Taylor & Francis's Desalination Publications. Praised for its “multi-faceted content [which] contributes to enrich it,” and described as “an essential companion...[that] enables the reader to gain a deeper understanding of the desalination industry,” this book is testament to the quality improvements we have been striving towards over the last twelve months.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Language: English
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  • 23
    Publication Date: 2024-04-05
    Description: The Global Methane Initiative (GMI) is a voluntary international partnership that promotes methane recovery and reuse activities in developing and transition economies. The U.S. Department of State requested an evaluation of the activities and outcomes supported in whole or in part by its contributions to GMI to gauge its value added to the program.
    Keywords: Physics ; Environmental Science ; Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TQ Environmental science, engineering and technology ; thema EDItEUR::R Earth Sciences, Geography, Environment, Planning::RB Earth sciences::RBP Meteorology and climatology
    Language: English
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  • 24
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Progress in agricultural, biomedical and industrial applications' is a compilation of recent advances and developments in gas chromatography and its applications. The chapters cover various aspects of applications ranging from basic biological, biomedical applications to industrial applications. Book chapters analyze new developments in chromatographic columns, microextraction techniques, derivatisation techniques and pyrolysis techniques. The book also includes several aspects of basic chromatography techniques and is suitable for both young and advanced chromatographers. It includes some new developments in chromatography such as multidimensional chromatography, inverse chromatography and some discussions on two-dimensional chromatography. The topics covered include analysis of volatiles, toxicants, indoor air, petroleum hydrocarbons, organometallic compounds and natural products. The chapters were written by experts from various fields and clearly assisted by simple diagrams and tables. This book is highly recommended for chemists as well as non-chemists working in gas chromatography.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Language: English
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  • 25
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: This book discusses electrocatalysis and electrocatalysts for energy, water electrolysis, water treatment, CO2 conversion, and green chemistry. It reviews various electrocatalysts and their properties and electrochemical performances. The first section of the book covers topics in direct alcohol fuel cells including Pt-based electrocatalysts as non-carbon electrode support materials and the development of electrocatalysts for direct methanol fuel cells. The second section of the book covers various topics in electrocatalysis and electrocatalysts for a cleaner environment, including electrocatalysts for the conversion of CO2 to valuable products and SYNGAS, electrocatalysts for water electrolysis, and much more.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRH Electrochemistry and magnetochemistry
    Language: English
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  • 26
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Surfactants are ubiquitous and have applications in diverse areas, including food, cosmetics, detergents, lubricants, enhanced oil recovery (EOR), and targeted drug delivery systems. Their wide diversity of applications owes to their unique structure, namely, a hydrophilic and a hydrophobic group present in the same molecule. Although most surfactants used industrially are synthetic, there is a growing need for natural surfactants, as the latter is obtainable from renewable sources and are less toxic and highly biodegradable in contrast to their synthetic counterparts. This book is a compilation of interesting articles by various experts that cover various applications of both synthetic and natural surfactants.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRC Colloid chemistry
    Language: English
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  • 27
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: The chemical sensor plays an essential role in the fields of environmental conservation and monitoring, disaster and disease prevention, and industrial analysis. A typical chemical sensor is a device that transforms chemical information in a selective and reversible way, ranging from the concentration of a specific sample component to total composition analysis, into an analytically useful signal. Much research work has been performed to achieve a chemical sensor with such excellent qualities as quick response, low cost, small size, superior sensitivity, good reversibility and selectivity, and excellent detection limit. This book introduces the latest advances on chemical sensors. It consists of 15 chapters composed by the researchers active in the field of chemical sensors, and is divided into 5 sections according to the classification following the principles of signal transducer. This collection of up-to-date information and the latest research progress on chemical sensor will provide valuable references and learning materials for all those working in the field of chemical sensors.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Language: English
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  • 28
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Distillation is an important separation technique that has been used for many centuries to exploit the volatility differences between components in a mixture. The distillation process has many variations and applications. This book includes two sections on desalination and reactive distillation. It discusses desalination in the processes of solar and membrane distillation, with a focus on the reduction of energy costs to obtain potable water. It also discusses reactive distillation, which can be used in some cases to reduce the power duty in the separation process by using the reaction heat directly in the separation. The book includes cases of mathematical modeling, simulation, and optimization of the distillation process.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Language: English
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  • 29
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Cyclodextrins (CDs) have attracted great interest from the research community as well as industries in an array of sectors because of their unique structural features. This book provides a comprehensive overview of CDs, beginning with their historical background. Chapters address such topics as the structure and physiochemical properties of CDs, advancements in the field, and potential applications of these materials in fields such as drug delivery and sensing. This book reveals new frontiers in the CD world and is a useful resource for organic, analytical, and supramolecular chemists as well as scientists engaged in biological and material sciences.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: English
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  • 30
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: The book presents a comprehensive overview of sorption, which is a multi-parametric separation process. It is extensively used in the removal of various pollutants from the tertiary stage of wastewater treatment, from leachates, etc. It discusses fundamental points of the technique as well as kinetic theories and isotherms. It also examines the synthesis and characterizations of all studied adsorbent materials to find their paths of sorption. Finally, it highlights the importance of having a cost-estimation plan for the synthesis of sorbent materials as well as predictions for their reusability.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRX Surface chemistry and adsorption
    Language: English
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  • 31
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Carotenoids are natural and versatile secondary metabolites, most of them showing colours that vary from yellow to red. They are widespread among living beings where they are involved in many biological roles reporting beneficial actions. To date, more than 750 carotenoids have been described in nature. Humans cannot synthesize carotenoids de novo, thus they are mainly obtained through diet. In fact, carotenoids are consistently found in tissues or biological fluids where they play a beneficial decreasing the risk of developing some diseases.During the last half-century, significant advances in carotenoids research have been made. This book highlights new perspectives and applications of carotenoids including characterization and isolation of new compounds (including rare carotenoids), their production at a mid-large scale (involving new innovative approaches), and uses of carotenoids in different biotechnological fields like food science, biomedicine, and cosmetics.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Language: English
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  • 32
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Infrared Spectroscopy - Perspectives and Applications is a compendium of contributions from experts in the field of infrared (IR) spectroscopy. This assembly of investigations and reviews provides a comprehensive overview of the fundamentals as well as the groundbreaking applications in the field. Chapters discuss IR spectroscopy applications in the food and biomedicine sectors and for measuring transport through polymer membranes, characterizing lignocellulosic biomasses, detecting adulterants, and characterizing enamel surface advancements. This book is an invaluable resource and reference for students, researchers, and other interested readers.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry::PNFS Spectrum analysis, spectrochemistry, mass spectrometry
    Language: English
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  • 33
    Publication Date: 2023-02-20
    Description: Several regions around the globe are characterized by a seismically active lower crust, at depths where litho­logical and thermal conditions suggest stress release by ductile flow. The Gargano Promontory (GP, southern Italy) is an example where a recently installed seismic network has recorded an intense seismic activity at depths between 20 and 30 km, i.e. in the lower crust. The GP is located in proximity of the Gargano-Dubrovnik line­ament, a seismogenic zone separating the central and southern Adriatic basins. These two basins constitute sites of sediments accumulation since Tertiary times. Another important basin in the region is represented by the Apennine foredeep, that includes the Candelaro area. We analyze the possible mechanisms controlling the dis­tribution of seismicity in the GP to identify the factors that make the lower crust seismically active. To this aim, we construct a thermo-rheological model of a layered continental crust, calibrated on the basis of geometrical, lithological and thermal constraints. The model takes into account various crustal lithologies, the presence of fluids in the crystalline basement, lateral variations of geotherm and stress field. The numerical simulations show that the presence of fluids is a key factor controlling the cluster of seismicity in the lower crust. Moreover, the presence of water in the upper crystalline basement and sedimentary cover provides a plausible explanation for upper crustal seismicity in a zone of very high heat flow SW of the GP. The distribution of the seismicity is probably affected by the composition of the crystalline basement, with mafic bodies injected into the crust during the Paleocene magmatic phase that affected the Mediterranean region. In addition, fluid accumulation and overpressure may occur along detachment levels in the lower crust, leading to clustering of the earthquakes. Based on our findings, we hypothesize that the presence of hydrous diapiric upwelling(s) in the upper mantle can feed a deep fluid circulation system, inducing lower crustal seismicity.
    Description: Published
    Description: 103929
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: Lower crust ; Rheology ; Seismology ; Geotherm ; Numerical modeling ; Gargano Promontory (southern Italy)
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 34
    Publication Date: 2023-03-08
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in LeClerc, H., Tompsett, G., Paulsen, A., McKenna, A., Niles, S., Reddy, C., Nelson, R., Cheng, F., Teixeira, A., & Timko, M. Hydroxyapatite catalyzed hydrothermal liquefaction transforms food waste from an environmental liability to renewable fuel. IScience, 25(9), (2022): 104916, https://doi.org/10.1016/j.isci.2022.104916.
    Description: Food waste is an abundant and inexpensive resource for the production of renewable fuels. Biocrude yields obtained from hydrothermal liquefaction (HTL) of food waste can be boosted using hydroxyapatite (HAP) as an inexpensive and abundant catalyst. Combining HAP with an inexpensive homogeneous base increased biocrude yield from 14 ± 1 to 37 ± 3%, resulting in the recovery of 49 ± 2% of the energy contained in the food waste feed. Detailed product analysis revealed the importance of fatty-acid oligomerization during biocrude formation, highlighting the role of acid-base catalysts in promoting condensation reactions. Economic and environmental analysis found that the new technology has the potential to reduce US greenhouse gas emissions by 2.6% while producing renewable diesel with a minimum fuel selling price of $1.06/GGE. HAP can play a role in transforming food waste from a liability to a renewable fuel.
    Description: This work was funded by the DOE Bioenergy Technology Office (DE-EE0008513), a DOE DBIR (DE-SC0015784) and the MassCEC. The authors thank WenWen Yao, Department of Environmental Science at WPI, for TOC analysis, Mainstream Engineering for heating value characterization of the oil and solid samples, Wei Fan for assistance in obtaining SEM images and, Julia Martin and Ronald Grimm for their assistance in collecting XPS data, and Jeffrey R. Page for his assistance with oil upgrading and analysis. HOL was partially funded for this work by NSF Graduate Research Fellowship award number 2038257. A portion of this work was performed at the National High Magnetic Field Laboratory Ion Cyclotron Resonance user facility, which is supported by the NSF Division of Materials Research and Division of Chemistry through DMR 16-44779 and the State of Florida.
    Keywords: Chemistry ; Chemical engineering ; Catalysis
    Repository Name: Woods Hole Open Access Server
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  • 35
    Publication Date: 2024-04-23
    Description: The National Institute of Geophysics and Volcanology (INGV, Istituto Nazionale di Geofisica e Vulcanologia), is an italian public research institute established in 1999. Since its inception, the mission of INGV included seismic surveillance and earthquake monitoring in Italy. INGV is part of the Civil Defence system (Margheriti et al., 2021). INGV has offices in different parts of Italy and operates the Italian National Seismic Network (Rete Sismica Nazionale—RSN; INGV Seismological Data Centre, 2006) and other networks at national scale (Michelini et al., 2017). INGV also operates a temporary seismic network infrastructure, a pool of instruments used to densify seismic networks for scientific experiments or in response to damaging earthquakes and to increase monitoring capabilities during seismic sequences. SISMIKO is the operational task force of INGV whose core purpose is to rapidly deploy temporary seismic stations in response to moderate—large magnitude earthquakes or in areas where a seismic sequence is causing concerns and/or scientific interest (Moretti et al., 2016). By reducing the spatial distance between the seismic stations, temporary deployments can improve the RSN detection capability and the accuracy of the earthquake locations. SISMIKO was established in 2015 by Lucia Margheriti and Milena Moretti, so they became responsible for INGV emergency deployments of the temporary networks. SISMIKO involves INGV technicians and researchers from all over Italy, from Milano to Catania (see acknowledgments), grouped together by common interest technical and scientific issues. SISMIKO coordinates all INGV groups working on seismic emergencies (Figure 1). The data acquired by the SISMIKO temporary networks, are made available to the scientific community, without any restrictions, via italian node of the European Integrated Data Archive portal (EIDA1; Danecek et al., 2021). Datasets are archived in near real-time in the “Standard for the Exchange of Earthquake Data (SEED)” format and have an associated Digital Object Identifier (DOI). The data are used for monitoring, surveillance and for scientific research. Since its establishment, SISMIKO has installed seven temporary seismic networks, including the one used to monitor the 2016–2018 seismic sequence in central Italy (Moretti et al., 2016). The most recent activations of SISMIKO were in May and November 2022: Chianti-Fiorentino (Piccinini et al., 2022; 2023) and North Marche coast (D’Alema et al., 2022b), respectively. The following section briefly describes the history of the INGV emergency mobile network.
    Description: Published
    Description: 1146579
    Description: OST5 Verso un nuovo Monitoraggio
    Description: JCR Journal
    Keywords: SISMIKO ; Seismic emergency ; Temporary seismic network ; Real time transmission ; Seismology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 36
    Publication Date: 2023-09-01
    Description: Abstract
    Description: We present a new, consistently processed seismicity catalogue for the Eastern and Southern Alps, based on the temporary dense Swath-D monitoring network. The final catalogue includes 6,053 earthquakes for the time period 2017-2019 and has a magnitude of completeness of −1.0ML. The smallest detected and located events have a magnitude of −1.7ML. Aimed at the low to moderate seismicity in the study region, we generated a multi-level, mostly automatic workflow which combines a priori information from local catalogues and waveform-based event detection, subsequent efficient GPU-based event search by template matching, P & S arrival time pick refinement and location in a regional 3-D velocity model. The resulting seismicity distribution generally confirms the previously identified main seismically active domains, but provides increased resolution of the fault activity at depth. In particular, the high number of small events additionally detected by the template search contributes to a more dense catalogue, providing an important basis for future geological and tectonic studies in this complex part of the Alpine orogen.
    Description: TableOfContents
    Description: Seismicity catalogue Python codes & metadata Seismicity cross-sections
    Keywords: Seismology ; Seismic Waveform Analysis ; Eastern Alps ; Earthquake ; Geophysics ; Template matching ; 4DMB ; 4D Mountain Building ; EARTH SCIENCE ; EARTH SCIENCE 〉 SOLID EARTH ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 EARTHQUAKES ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 EARTHQUAKES 〉 EARTHQUAKE MAGNITUDE/INTENSITY ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 EARTHQUAKES 〉 EARTHQUAKE OCCURRENCES ; geophysics ; seismology ; surface processes ; tectonics
    Type: Dataset , Dataset
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  • 37
    Publication Date: 2023-10-18
    Description: Abstract
    Description: This data publication contains (i) a slab model of the Cascadia subduction zone, derived from receiver functions, parameterized as depth to the three interfaces: t (top), c (central) and m (Moho), in NetCDF format; (ii) the station measurements of all parameters in the model in tabular and Raysum model file format; (iii) the raw receiver functions in SAC format; and (iv) auxiliary scripts for loading and plotting the data. A total of 45,601 individual receiver functions recorded at 298 seismic stations distributed across the Cascadia forearc contributed to the slab model. For each station, 100 s recordings symmetric about the P -wave arrival (i.e. 50 s noise and 50 s signal) of earthquakes with magnitudes between 5.5 and 8, in the distance range between 30 and 100 degree, were downloaded from the Incorporated Research Institutions for Seismology (IRIS) data center, the Northern California Earthquake Data Center (NCEDC), and the Natural Resources Canada Data Center (NRCAN). After quality control, radial and transverse receiver functions were computed through frequency-domain simultaneous deconvolution, with an optimal damping factor found through generalized cross validation. The continental forearc and subducting slab were parameterized as three layers over a mantle half-space, with the subduction stratigraphy bounding interfaces labeled as t (top), c (central) and m (Moho). Synthetic receiver functions were calculated through ray-theoretical modeling of plane-wave scattering at the model interfaces. The thickness, S -wave velocity (VS) and P - to S -wave velocity ratio (VP/VS) of each layer, as well as the common strike and dip of the bottom two layers and the top of the half space (in total 11 parameters) were optimized simultaneously through a simulated annealing global parameter search scheme. The misfit was defined as the anti-correlation (1 minus the cross-correlation coefficient) between the observed and predicted receiver functions, bandpass filtered between 2 and 20 s period duration. In total, 171, 143 and 137 quality A nodes were determined to constrain the t, c and m interfaces, respectively. At the trench, 105 nodes at 3 km below the local bathymetry were inserted to constrain the t and c interfaces, and at 6.5 km deeper to constrain the m interface, representing typical sediment and igneous crustal thicknesses. A spline surface was fitted to these nodes to yield margin-wide depth models. The spline coefficients were found using singular value decomposition, with the nominal depth uncertainties supplied as weights. The solution was damped by retaining the 116, 117, and 116 largest singular values for the t, c and m interfaces, respectively, based on analysis of L-curves and the Akaike information criterion. The data set is the supplemental material to Bloch, W., Bostock, M. G., Audet, P. (2023) A Cascadia Slab Model from Receiver Functions. Geochemistry, Geophysics, Geosystems.
    Keywords: Seismology ; Cascadia ; North America ; Reveiver Functions ; Subduction ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 PLATE TECTONICS ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 PLATE TECTONICS 〉 PLATE BOUNDARIES ; lithosphere ; The Present
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  • 38
    Publication Date: 2024-04-05
    Description: Chemiebezogene Kompetenzen werden bereits im Sachunterricht der Grundschule entwickelt und sollen im Chemieunterricht der Sekundarstufe I aufgegriffen und weiterentwickelt werden. Ziel dieser Studie war es, die chemiebezogenen Kompetenzen der Schülerinnen und Schüler in der Übergangsphase zwischen Sachunterricht und Chemieunterricht zu analysieren. In einer Ergänzungsstudie wurden zusätzlich sowohl die Auswirkungen der Schulschließungen aufgrund der SARS-CoV-II Pandemie auf die Kompetenzen der Schülerinnen und Schüler als auch der Einfluss einer veränderten Testadministration untersucht. Insgesamt wurden die Kompetenzen von 2262 Lernenden der Jahrgangsstufen 5 bis 9 zu drei Messzeitpunkten analysiert. Die Ergebnisse zeigen, dass die chemiebezogenen Kompetenzen sowohl zum Ende der Grundschulzeit als auch zu Beginn des Chemieunterrichts über alle Kompetenzbereiche hinweg sehr heterogen ausfallen. Dennoch sind sie zu Beginn des Chemieunterrichts in einigen Kompetenzbereichen höher ausgeprägt als zum Ende der Grundschulzeit. Nach den pandemiebedingten Schulschließungen waren die Kompetenzen ähnlich ausgeprägt wie in den gleichen Jahrgangsstufen vor den Schulschließungen. Eine während der Schulschließungen notwendige Bearbeitung der Testhefte von zu Hause aus führte vor allem bei den jüngeren Schülerinnen und Schülern zu besseren Testergebnissen als die Bearbeitung in der Schule. Um die Entwicklung chemiebezogener Kompetenzen in der Übergangsphase zu optimieren, sollte der Erwerb dieser Kompetenzen bereits im Sachunterricht einheitlicher gestaltet werden.
    Keywords: Science ; Chemistry ; Education ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::J Society and Social Sciences::JN Education
    Language: German
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  • 39
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    Logos Verlag Berlin | Logos Verlag Berlin
    Publication Date: 2024-04-05
    Description: In 2005, the hybrid model was published by Prof. H.-D. Alber and Prof. P. Zhu as an alternative to the Allen-Cahn model for the description of phase field transformations. With low interfacial energy, it is more efficient, since the resolution of the diffuse interface is numerically broader for the same solution accuracy and allows coarser meshing. The solutions of both models are associated with energy minimisation and in this work the error terms introduced in the earlier publications are discussed and documented using one and two dimensional numerical simulations. In the last part of this book, phase field problems, initially not coupled with material equations, are combined with linear elasticity and, after simple introductory examples, a growing martensitic inclusion is simulated and compared with literature data. In addition to the confirmed numerical advantage, another phenomenon not previously described in the literature is found: with the hybrid model, in contrast to the examples calculated with the Allen-Cahn model, an inclusion driven mainly by curvature energy does not disappear completely. The opposite problem prevents inclusions from growing from very small initial configurations, but this fact can be remedied by a very finely chosen diffuse interface width and by analysing and adjusting the terms that generate the modelling errors. The last example shows that the hybrid model can be used with numerical advantages despite the above mentioned peculiarities.
    Keywords: Science ; Chemistry ; Mathematics ; Science ; Physics ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PB Mathematics ; thema EDItEUR::P Mathematics and Science::PH Physics
    Language: English
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  • 40
    Publication Date: 2024-04-05
    Description: Das selbstgesteuerte Experimentieren ist laut den nationalen Bildungsstandards sowie den Lehrplänen im Fach Chemie ein wichtiger Bestandteil der naturwissenschaftlichen Schulbildung. Offene Experimentierformen sind jedoch wenig etabliert. Um das selbstgesteuerte Experimentieren in die Unterrichtspraxis zu implementieren, wurde im Rahmen dieses Forschungsprojekts eine eintägige Lehrkräftefortbildung zur Konzeption von selbstgesteuerten Experimenten im Chemieunterricht durchgeführt. Dazu wurde ein literaturbasiertes Strukturierungskonzept entwickelt, mit dem die Lehrkräfte kochbuchartige Schulversuche zu selbstgesteuerten und kompetenzorientierten Experimenten mit beliebigen Öffnungsgraden modifizieren können. Begleitend zur Fortbildung wurde im Prä-Post-Follow-Up-Design das fachdidaktische Wissen der Teilnehmenden hinsichtlich der Planung von selbstgesteuerten Experimenten empirisch überprüft. Zur Erfassung dieses Konstrukts wurde ein neues Messinstrument literaturbasiert entwickelt und die Güte des Messinstruments evaluiert. Die Auswertungen zeigen, dass die Fortbildung hinsichtlich des fachdidaktischen Wissens der Lehrkräfte kurz- sowie langfristig lernförderlich ist und die Fortbildung von den Teilnehmenden positiv bewertet wird. Die Reliabilitätsanalyse sowie die Validierungsstudie zeigen, dass der Test sowohl reliabel als auch valide ist. In Folgestudien könnte die langfristige Verhaltensänderung der Lehrkräfte bezüglich der Implementierung des selbstgesteuerten Experimentierens in den Unterricht untersucht werden.
    Keywords: Science ; Chemistry ; Science ; Education ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PD Science: general issues ; thema EDItEUR::J Society and Social Sciences::JN Education
    Language: German
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  • 41
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    Logos Verlag Berlin | Logos Verlag Berlin
    Publication Date: 2024-04-05
    Description: Konsumgüter werden beispielsweise mit Slogans wie "Gut in Bio. Schlecht in Chemie." beworben. Dabei wird intendiert, sich gezielt von "Chemie" abzugrenzen und sich das positive Bild von "Natur" zu Nutze zu machen. Dies prägt die öffentliche Meinung und trägt zu einer antagonistisch-wertenden Sicht von "Chemie" und "Natur" bei. Dass Chemie als Naturwissenschaft der Beschreibung der Natur dient, um deren Stoffe und Stoffumwandlungen zu erklären, ist dem Laien selten bewusst. Chemie findet überall statt, insbesondere in der Natur! Genau an diesem Punkt setzt das Unterrichtskonzept "Chemie Pur - Unterrichten in der Naturglqq an. Ziel ist es, im Freiland, mit direkt vor Ort gewonnenen Naturstoffen, Umweltprozesse experimentell zu erarbeiten. Die projektbegleitende Evaluationsstudie stellte sich der Forschungsfrage, wie sich das Unterrichtskonzept auf das Fach- und Sachinteresse, auf die Naturverbundenheit sowie auf die Einstellung zu Chemie und Natur von Schülerinnen und Schülern der Sekundarstufe II auswirkt. Die Auswertung der Fragebogenergebnisse mit latenten Veränderungsmodellen haben gezeigt, dass die Intervention im Freiland das inhaltsbezogene Sachinteresse steigert und die Einstellung zu Chemie und Natur positiv beeinflusst sowie ein erhöhten Fachwissenszuwachs ermöglicht. Die gewonnenen Erkenntnisse können die Grundlage für die Entwicklung und Evaluation von good-practice-Ansätzen naturwissenschaftlicher Lernsituationen bilden. Das Unterrichtskonzept Chemie Pur leistet zudem einen Beitrag im Bereich Outdoor Education, um den Antagonismus von Chemie und Natur zu verringern.
    Keywords: Science ; Chemistry ; Science ; Education ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PD Science: general issues ; thema EDItEUR::J Society and Social Sciences::JN Education
    Language: German
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  • 42
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    The MIT Press | The MIT Press
    Publication Date: 2024-03-27
    Description: The original 1818 text of Mary Shelley's classic novel, with annotations and essays highlighting its scientific, ethical, and cautionary aspects. Mary Shelley's Frankenstein has endured in the popular imagination for two hundred years. Begun as a ghost story by an intellectually and socially precocious eighteen-year-old author during a cold and rainy summer on the shores of Lake Geneva, the dramatic tale of Victor Frankenstein and his stitched-together creature can be read as the ultimate parable of scientific hubris. Victor, “the modern Prometheus,” tried to do what he perhaps should have left to Nature: create life. Although the novel is most often discussed in literary-historical terms—as a seminal example of romanticism or as a groundbreaking early work of science fiction—Mary Shelley was keenly aware of contemporary scientific developments and incorporated them into her story. In our era of synthetic biology, artificial intelligence, robotics, and climate engineering, this edition of Frankenstein will resonate forcefully for readers with a background or interest in science and engineering, and anyone intrigued by the fundamental questions of creativity and responsibility. This edition of Frankenstein pairs the original 1818 version of the manuscript—meticulously line-edited and amended by Charles E. Robinson, one of the world's preeminent authorities on the text—with annotations and essays by leading scholars exploring the social and ethical aspects of scientific creativity raised by this remarkable story. The result is a unique and accessible edition of one of the most thought-provoking and influential novels ever written. Essays by Elizabeth Bear, Cory Doctorow, Heather E. Douglas, Josephine Johnston, Kate MacCord, Jane Maienschein, Anne K. Mellor, Alfred Nordmann
    Keywords: science fiction ; gothic ; horror ; European ; British ; literature ; fiction ; cautionary tale ; STEM ; science ; bioethics ; classic ; bicentennial ; Josephine Johnston ; Cory Doctorow ; Jane Maienschein ; Kate MacCord ; Alfred Nordmann ; Elizabeth Bear ; Anne K. Mellor ; Heather E. Douglas ; Frankenstein ; Creature ; Monster ; Mary Shelley ; Makers ; women in science ; science and anti-science ; values in science ; responsible innovation ; Industrial Revolution ; Mary Wollstonecraft ; William Godwin ; Percy Bysshe Shelley ; Galvanism ; Mount Tambora ; Myths ; Two Cultures ; epistolary novel ; Victor Frankenstein ; Geneva ; Prometheus ; Arctic ; Lord Byron ; John Polidori ; ghost stories ; Revisions ; Electricity ; Lightning ; Vitalism ; Chemistry ; Extinction ; Magnetism ; Moral responsibility ; Legal responsibility ; Social responsibility ; Consequences ; Obligations ; Ethics ; Maker Culture ; DIY ; Technology Adjacent Possible ; Facebook ; Surveillance ; Aristotle ; Fetal development ; Epigenesis ; Embryo ; Person ; Technoscience ; Alchemy ; uncanny valley ; animation ; complexity ; Morality ; Monstrosity ; Christianity ; Otherness ; Gender ; Nature ; Domestic Affections ; Women ; Sexuality ; Technical Sweetness ; Los Alamos ; Trinity Test ; Scientific Responsibility ; Nuclear Weapons ; adjacent possible ; synthetic biology ; robotics ; thema EDItEUR::F Fiction and Related items::FB Fiction: general and literary::FBC Classic fiction: general and literary ; thema EDItEUR::F Fiction and Related items::FL Science fiction::FLC Classic science fiction
    Language: English
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  • 43
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    Logos Verlag Berlin | Logos Verlag Berlin
    Publication Date: 2024-04-05
    Description: When auralizing moving sound sources in Virtual Reality (VR) environments, the two main input parameters are the location and radiated signal of the source. An array measurement-based model is developed to characterize moving sound sources regarding the two parameters in this thesis. This model utilizes beamforming, i.e. delay and sum beamforming (DSB) and compressive beamforming (CB) to obtain the locations and signals of moving sound sources. A spiral and a pseudorandom microphone array are designed for DSB and CB, respectively, to yield good localization ability and meet the requirement of CB. The de-Dopplerization technique is incorporated in the time-domain DSB to address moving source problems. Time-domain transfer functions (TDTFs) are calculated in terms of the spatial locations within the steering window of the moving source. TDTFs then form the sensing matrix of CB, thus allowing CB to solve moving source problem. DSB and CB are further extended to localize moving sound sources, and the reconstructed signals from the beamforming outputs are investigated to obtain the source signals. Moreover, localization and signal reconstruction are evaluated through varying parameters in the beamforming procedures, i.e. steering position, steering window length and source speed for a moving periodic signal using DSB, and regularization parameter, signal to noise ratio (SNR), steering window length, source speed, array to source motion trajectory and mismatch for a moving engine signal using CB. The parameter studies show guidelines of parameter selection based on the given situations in this thesis for modeling moving source using beamforming. Both algorithms are able to reconstruct the moving signals in the given scenarios. Although CB outperforms DSB in terms of signal reconstruction under particular conditions, the localization abilities of the two algorithms are quite similar. The practicability of the model has been applied on pass-by measurements of a moving loudspeaker using the designed arrays, and the results can match the conclusions drawn above from simulations. Finally, a framework on how to apply the model for moving source auralization is proposed.
    Keywords: Science ; Chemistry ; Technology & Engineering ; Construction ; Technology & Engineering ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TN Civil engineering, surveying and building::TNK Building construction and materials ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TB Technology: general issues
    Language: English
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  • 44
    Publication Date: 2024-04-05
    Description: Neuere Erkenntnisse zum Umsatzverhalten an Dieseloxidationskatalysatoren (DOCs) zeigen, dass das Umsatzverhalten von Schadstoffen vom Oxidationsgrad der verwendeten Edelmetallkatalysatoren abhängen kann. Dabei wird deutlich, dass sich der Oxidationsgrad bei typischen Abgaszusammensetzungen langsam und reversibel mit der Katalysatortemperatur ändert. Das kann bei periodischen Katalysatortemperaturänderungen zu einem ausgeprägten Hystereseverhalten führen. Bisherige Ergebnisse liegen insbesondere zum Verhalten der NO-Oxidation an Platin-Katalysatoren vor. Ziel der vorliegenden Arbeit ist es daher, die Untersuchungen auf seriennahe Pd- und PtPd-Mischkatalysatoren sowie auf andere abgastypische Schadstoffe, wie CO und Kohlenwasserstoffe, zu erweitern und dabei auch den Einfluss der Katalysatoralterung zu erfassen. Es wurde ein globalkinetisches Modell entwickelt und an die experimentellen Befunde angepasst. Dabei zeigte sich, dass es in der Regel möglich ist, das Umsatzverhalten bei reinen Pt- und Pd-Katalysatoren mit diesem örtlich eindimensionalen, makrokinetischen Zweiphasenmodell zutreffend zu beschreiben, wohingegen das Verhalten auf Pt/Pd-Mischkatalysatoren weniger gut simuliert werden kann. Dies ist vermutlich auf die heterogene Struktur der Pt/Pd-legierten Partikel zurückzuführen.
    Keywords: Science ; Chemistry ; Technology & Engineering ; Chemical & Biochemical ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TD Industrial chemistry and manufacturing technologies::TDC Industrial chemistry and chemical engineering
    Language: German
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  • 45
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    Frontiers Media SA
    Publication Date: 2024-04-04
    Description: The Frontiers in Chemistry Editorial Office team are delighted to present the inaugural “Frontiers in Chemistry: Rising Stars” article collection, showcasing the high-quality work of internationally recognized researchers in the early stages of their independent careers. All Rising Star researchers featured within this collection were individually nominated by the Journal’s Chief Editors in recognition of their potential to influence the future directions in their respective fields. The work presented here highlights the diversity of research performed across the entire breadth of the chemical sciences, and presents advances in theory, experiment and methodology with applications to compelling problems. This Editorial features the corresponding author(s) of each paper published within this important collection, ordered by section alphabetically, highlighting them as the great researchers of the future. The Frontiers in Chemistry Editorial Office team would like to thank each researcher who contributed their work to this collection. We would also like to personally thank our Chief Editors for their exemplary leadership of this article collection; their strong support and passion for this important, community-driven collection has ensured its success and global impact.
    Keywords: Green and Sustainable Chemistry ; Analytical Chemistry ; Theoretical and Computational Chemistry ; Polymer Chemistry ; Medicinal and Pharmaceutical Chemistry ; Organic Chemistry ; Nanoscience ; Catalysis and Photocatalysis ; Supramolecular Chemistry ; Electrochemistry ; Inorganic Chemistry ; Chemical Biology ; thema EDItEUR::P Mathematics and Science::PD Science: general issues
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  • 46
    Publication Date: 2023-12-20
    Description: Giulia Parola’s Environmental Democracy at the Global Level: Rights and Duties for a New Citizenship can be seen as a manifesto that is both traditional and revolutionary at the same time. It calls for the construction of a new civilisation centred on the environment, while drawing on the traditional notions of democratic government. It adopts an approach that is focused on the power of individuals rather than governments, as ways to protect and improve the environment. It proposes that environmental rights and ecological duties are self-evident and inalienable, and should be treated as the cornerstones of a new democracy. Parola’s book is a thought provoking and intriguing work that will be of interest to scholars of environmental studies as well as to legal practitioners and non-specialists. Giulia Parola has studied Environmental Law at the University of Torino, at the University of René Descartes in Paris, (where she obtained PhD in Public Law) and at the University of Iceland ( LLM in Natural Resources Law and International Environmental Law). In 2011, she was appointed by the University of Laval (Canada, Quebec) as a researcher and a lecturer in Environmental Law.
    Keywords: GE1-350 ; K ; International Law ; Materials Science ; Industrial Chemistry ; Law ; Comparative Law ; Foreign Law ; Environment ; Natural Sciences ; German Civil Code ; Pollution Control ; bic Book Industry Communication::K Economics, finance, business & management::KC Economics::KCN Environmental economics
    Language: English
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  • 47
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    Taylor & Francis | CRC Press
    Publication Date: 2024-03-31
    Description: Hydroxyapatite coatings are of great importance in the biological and biomedical coatings fields, especially in the current era of nanotechnology and bioapplications. With a bonelike structure that promotes osseointegration, hydroxyapatite coating can be applied to otherwise bioinactive implants to make their surface bioactive, thus achieving faster healing and recovery. In addition to applications in orthopedic and dental implants, this coating can also be used in drug delivery. Hydroxyapatite Coatings for Biomedical Applications explores developments in the processing and property characterization and applications of hydroxyapatite to provide timely information for active researchers and newcomers alike. In eight carefully reviewed chapters, hydroxyapatite experts from the United States, Japan, Singapore, and China present the latest on topics ranging from deposition processes to biomedical applications in implants and drug delivery. This book discusses: Magnetron sputtering and electrochemical deposition The modification of hydroxyapatite properties by sol–gel deposition to incorporate other elements found in natural bones, such as zinc, magnesium, and fluorine The use of pure hydroxyapatite in drug delivery applications The growth or self-assembly of hydroxyapatite on shape memory alloy Hydroxyapatite composite coatings—with carbon nanotubes, titanium dioxide (TiO2), and others—on the titanium alloy Offering valuable insights and a wealth of data, including numerous tables and figures, this is a rich source of information for research on hydroxyapatite coatings. Each chapter also covers material that provides an accessible stepping stone for those who are new to the field.
    Keywords: Pre-clinical medicine: basic sciences ; Chemistry ; Materials science ; thema EDItEUR::M Medicine and Nursing::MF Pre-clinical medicine: basic sciences ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
    Language: English
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  • 48
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    MDPI - Multidisciplinary Digital Publishing Institute
    Publication Date: 2024-04-05
    Description: Nanofibers, particularly those of a carbonaceous content, have received increased interest in the past two decades due to their outstanding physico-chemical characteristics and their possibility to form and contribute towards a plethora of potentially advantageous materials for consumer, industrial and medical applications. Despite this, and together with the numerous research studies and published articles that have sought to investigate these aspects, the potential impact of CNTs is still not understood. Whether or not nanofibers may be able to provide a sophisticated alternative to conventional materials is still debatable, whilst their effects upon both environmental and human health are highly equivocal. How nanofibers are conceived can determine how they may interact with different environments, such as the human body. Understanding each key step of the synthesis and production of nanofibers to their use within potential applications is therefore essential in gaining an insight into how they may be perceived by any biological system and environment. Thus, obtaining such information will enable all scientific communities to begin to realize the potential advantages posed by nanofibers. The aim of this Special Issue therefore, was to provide a collective overview of nanofibers; ‘from synthesis to application’. The Issue particularly focuses upon carbon-based nanofibers, but also highlights alternative nanofiber types. Emphasis is given holistically, with articles discussing the production routes of nanofibers, their plight during their life-cycle (origin to applied form and effects over time), as well as how nanofibers could either incite conflict, or provide aid to human and environmental health.
    Keywords: QD1-999 ; Toxicology ; Chemistry ; Biology ; Material Science ; Nanofibers ; Nanotechnology ; thema EDItEUR::P Mathematics and Science::PN Chemistry
    Language: English
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  • 49
    Publication Date: 2024-04-04
    Description: This volume, occasioned by the centenary of the Fritz Haber Institute, formerly the Institute for Physical Chemistry and Electrochemistry, covers the institute's scientific and institutional history from its founding until the present. The institute was among the earliest established by the Kaiser Wilhelm Society, and its inauguration was one of the first steps in the development of Berlin-Dahlem into a center for scientific research. Its establishment was made possible by an endowment from Leopold Koppel, granted on the condition that Fritz Haber, well-known for his discovery of a method to synthesize ammonia from its elements, be made its director. The history of the institute has largely paralleled that of 20th-century Germany. It undertook controversial weapons research during World War I, followed by a "Golden Era" during the 1920s, in spite of financial hardships.
    Keywords: Chemistry ; Chemistry ; Fritz Haber Institute ; thema EDItEUR::P Mathematics and Science::PD Science: general issues::PDX History of science
    Language: English
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  • 50
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    transcript Verlag | transcript Verlag
    Publication Date: 2024-04-04
    Description: Die Chemie büßt zugunsten physikalischer und lebenswissenschaftlicher Konzeptionen zunehmend an Deutungsmacht über die molekulare Welt ein. Sandra Lang untersucht, inwiefern die Ausdifferenzierung der chemischen Wissenschaften mit sich ebenfalls ausdifferenzierenden Zugriffen auf das Molekulare zusammenhängt. Anhand der vier exemplarischen Grenzfelder Materialwissenschaften, Biomedizin, Pharmazie und Quantenchemie und deren Narrative zur molekularen Eigenschaft der Chiralität veranschaulicht sie die transformative Phase der Chemie angesichts sich wandelnder Innovationsdispositive.
    Keywords: Chemie ; Chiralität ; Molekülkonzept ; Naturwissenschaften ; Grenzarbeit ; Interdisziplinarität ; Hybridität ; Wissenschaft ; Technik ; Wissenschaftssoziologie ; Techniksoziologie ; Wissenssoziologie ; Wissenschaftsgeschichte ; Soziologie ; Chemistry ; Chirality ; Molecule Concept ; Natural Sciences ; Border Work ; Interdisciplinarity ; Hybridity ; Science ; Technology ; Sociology of Science ; Sociology of Technology ; Sociology of Knowledge ; History of Science ; Sociology ; thema EDItEUR::P Mathematics and Science::PD Science: general issues::PDR Impact of science and technology on society ; thema EDItEUR::J Society and Social Sciences::JH Sociology and anthropology::JHB Sociology
    Language: German
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  • 51
    facet.materialart.
    Unknown
    Taylor & Francis | CRC Press
    Publication Date: 2024-03-31
    Description: Because of many misconceptions, the biological drug manufacturing industry does not fully utilize disposable components, despite their wide availability. These misconceptions include concerns for the quality of materials, running costs, scalability, the level of automation possible, and the training of staff needed to include these components in existing bioprocessing systems. Not fully realizing the long-term benefits, many manufacturers are unwilling to discard investments made in fixed equipment and traditional stainless steel systems. Regulatory and environmental concerns, however, will eventually compel manufacturers to adopt disposable systems. Making a strong case for disposables, Disposable Bioprocessing Systems demonstrates the true potential of these systems. Written by a researcher and professor with hands-on experience in designing, establishing, and validating biological manufacturing facilities worldwide, and creating model facilities using maximum disposable technology, this book is the first comprehensive introduction to understanding disposable systems. It gives an overview of the current state of the disposable bioprocessing industry, resolves all controversial issues, and guides readers in choosing disposable components that meet their needs. An important chapter on safety addresses facts and myths about the use of plastics and elastomers—including the issue of leaching—and how to ensure regulatory compliance. Helping readers understand their choices, the book describes the equipment and systems available to prepare the starting materials for the manufacturing of biological drugs—from disposable containers to filters. The author also discusses costs, regulations, and concerns about waste disposal, and shares his predictions for the future of the disposable bioprocessing industry. A practical manual for those interested in the transition to disposable systems, this book will also interest students of bioprocessing. It offers a timely view of disposable bioprocessing technology as a "game changer" that will facilitate developing new drugs and conducting research in the emerging field of stem cells and gene therapy.
    Keywords: Biotechnology ; Pharmaceutical Science ; Industrial Chemistry ; PHARMACEUTICAL ; BIOSCIENCE ; CHEMLIB ; SCI-TECH ; BIOMEDICALSCIENCE ; CHEMICALENGINEERING ; STM ; bags ; bioreactors ; cleaning ; disposal ; downstream ; single ; stainless ; steel ; use ; validation ; thema EDItEUR::M Medicine and Nursing::MF Pre-clinical medicine: basic sciences ; thema EDItEUR::M Medicine and Nursing::MK Medical specialties, branches of medicine::MKG Pharmacology ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TD Industrial chemistry and manufacturing technologies::TDC Industrial chemistry and chemical engineering ; thema EDItEUR::M Medicine and Nursing::MQ Nursing and ancillary services::MQW Biomedical engineering
    Language: English
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  • 52
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    De Gruyter | De Gruyter
    Publication Date: 2024-04-11
    Description: Presents technologies and key concepts to produce suitable smart materials and intelligent structures for sensing, information and communication technology, biomedical applications (drug delivery, hyperthermia therapy), self-healing, flexible memories and construction technologies. Novel developments of environmental friendly, cost-effective and scalable production processes are discussed by experts in the field.
    Keywords: Science ; Chemistry ; Industrial & Technical ; Technology & Engineering ; Textiles & Polymers ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TD Industrial chemistry and manufacturing technologies::TDC Industrial chemistry and chemical engineering ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
    Language: English
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  • 53
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    De Gruyter | De Gruyter
    Publication Date: 2024-04-05
    Description: Comprise definition of 1500 terms. Innovation from A to Z presents a glossary, including: Terms, older terms whose meanings have changed, acronyms, synonyms, famous names, selected abbreviations, and cross-references. A highly interdisciplinary approach incorporating strategy and entrepreneurship with technology and engineering sciences, economics, marketing, organizational behavior and theory. Ideal for engineers, managers, sales people and economists. Innovation Technology from A to Z Glossary of terms, including acronyms, synonyms, abbreviations, cross-references 1500 terms supplemented by figures and tables that clearly demonstrate the state-of-the-art in Innovation Technology
    Keywords: Science ; Chemistry ; Technology & Engineering ; Agriculture ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TV Agriculture and farming
    Language: English
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  • 54
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    Unknown
    Coimbra University Press
    Publication Date: 2022-01-31
    Description: This work brings together various contributions from experts in very diverse areas of knowledge, to discuss the theme ‘Light’ from various points of view. The subjects gathered in this work come from the areas of Physics, Philosophy, Transcendence, Chemistry, Optics, Literature, History of Sciences, History, Geography, International Relations, Biology, Psychology, Art, Cinema and Photography, Medicine and Museology. The texts partially reflect the contents presented at the interdisciplinary colloquium ‘Visões da Luz’ held in October 2015, on the occasion of the International Year of Light 2015, under the aegis of III-UC and open to academia and society, to teachers of the Basic and Secondary Education.
    Keywords: Geography ; Chemistry ; Literature ; Geology ; Light ; Optics ; Biology ; History ; Physics
    Language: Portuguese
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  • 55
    facet.materialart.
    Unknown
    Taylor & Francis | CRC Press
    Publication Date: 2024-04-11
    Description: Suitable for practicing engineers and engineers in training, this book covers the most important operations involving particulate solids. Through clear explanations of theoretical principles and practical laboratory exercises, the text provides an understanding of the behavior of powders and pulverized systems. It also helps readers develop skills for operating, optimizing, and innovating particle processing technologies and machinery in order to carry out industrial operations. The author explores common bulk solids processing operations, including milling, agglomeration, fluidization, mixing, and solid-fluid separation.
    Keywords: Industrial Chemistry ; Food Chemistry ; FOOD ; CHEMLIB ; SCI-TECH ; CHEMICALENGINEERING ; CHEMISTRY ; STM ; bed ; distribution ; fluidized ; industry ; mass ; material ; particle-size ; processing ; technology ; transfer ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TD Industrial chemistry and manufacturing technologies::TDC Industrial chemistry and chemical engineering ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TD Industrial chemistry and manufacturing technologies::TDC Industrial chemistry and chemical engineering::TDCT Food and beverage technology ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
    Language: English
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  • 56
    Publication Date: 2024-04-04
    Description: The Earth is an heterogeneous complex media from the mineral composition scale (10−6m) to the global scale ( 106m). The reconstruction of its structure is a quite challenging problem because sampling methodologies are mainly indirect as potential methods (Günther et al., 2006; Rücker et al., 2006), diffusive methods (Cognon, 1971; Druskin & Knizhnerman, 1988; Goldman & Stover, 1983; Hohmann, 1988; Kuo & Cho, 1980; Oristaglio & Hohmann, 1984) or propagation methods (Alterman & Karal, 1968; Bolt & Smith, 1976; Dablain, 1986; Kelly et al., 1976; Levander, 1988; Marfurt, 1984; Virieux, 1986). Seismic waves belong to the last category. We shall concentrate in this chapter on the forward problem which will be at the heart of any inverse problem for imaging the Earth. The forward problem is dedicated to the estimation of seismic wavefields when one knows the medium properties while the inverse problem is devoted to the estimation of medium properties from recorded seismic wavefields.
    Keywords: seismic wave ; geophysical imaging ; seismic wave ; geophysical imaging ; Boundary value problem ; Finite element method ; Free surface ; Frequency domain ; Seismology ; Time domain ; Velocity ; thema EDItEUR::P Mathematics and Science::PD Science: general issues
    Language: English
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  • 57
    Publication Date: 2023-06-12
    Description: Seismic events produced by block rotations about vertical axis occur in many geodynamic contexts. In this study, we show that these rotations can be accounted for using the proper theory, namely micropolar theory, and a new asymmetric moment tensor can be derived. We then apply this new theory to the Kaikōura earthquake (2016/11/14), Mw 7.8, one of the most complex earthquakes ever recorded with modern instrumental techniques. Using advanced numerical techniques, we compute synthetic seismograms including a full asymmetric moment tensor and we show that it induces measurable differences in the waveforms proving that seismic data can record the effects of the block rotations observed in the field. Therefore, the theory developed in this work provides a full framework for future dynamic source inversions of asymmetric moment tensors.
    Description: Westfälische Wilhelms-Universität Münster (1056)
    Keywords: ddc:551.22 ; Seismology ; asymmetric moment tensor ; micropolar theory ; Kaikōura earthquake
    Language: English
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  • 58
    Publication Date: 2024-02-28
    Description: The AlpArray experiment and the deployment of Swath-D together with the dense permanent network in Italy allow for detailed imaging of the spatio-temporal imaging complexity of seismic wave-fields within the greater Alpine region. The distance of any point within the area to the nearest station is less than 30 km, resulting in an average inter-station distance of about 45 km. With a much denser deployment in a smaller region of the Alps (320 km in length and 140 km wide), the Swath-D network possesses an average inter-station distance of about 15 km. We show that seismogram sections with a spatial sampling of less than 5 km can be obtained using recordings of these regional arrays for just a single event. Multiply reflected body waves can be observed for up to 2 h after source time. In addition, we provide and describe animations of long-period seismic wave-fields using recordings of about 1300–1600 broadband stations for six representative earthquakes. These illustrate the considerable spatio-temporal variability of the wave-field’s properties at a high lateral resolution. Within denser station distributions like those provided by Swath-D, even shorter period body and surface wave features can be recovered. The decrease of the horizontal wavelength from P to S to surface waves, deviations from spherically symmetric wavefronts, and the capability to detect multi-orbit arrivals are demonstrated qualitatively by the presented wave-field animations, which are a valuable tool for educational, quality control, and research purposes. We note that the information content of the acquired datasets can only be adequately explored by application of appropriate quantitative methods accounting for the considerable complexity of the seismic wave-fields as revealed by the now available station configuration.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Christian-Albrechts-Universität zu Kiel (3094)
    Keywords: ddc:551.22 ; Seismology ; Wave-fields ; Animations ; Alps ; AlpArray ; Swath-D
    Language: English
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  • 59
    Publication Date: 2024-02-23
    Description: Abstract
    Description: The main aim of this project is to investigate the crustal and mantle structure beneath the Longmenshan fault zone in China, based on a very dense passive seismology profile. The Longmenshan fault zone hosted the Wenchuan earthquake of May 2008 with a magnitude (Mw) of 7.9 and the Lushan earthquake of June 2013 with a magnitude (Mw) of 6.6. It is planned to mainly use the receiver-function method, to investigate the crustal and mantle structure beneath the Longmenshan fault zone. Waveform data are available from the GEOFON data center, under network code 4O, and are embargoed until February 2024.
    Keywords: Broadband seismic waveforms ; Seismology ; temporary local seismic experiment ; Earthquake ; Receiver functions ; Crustal and mantle structure ; China ; Monitoring system ; EARTH SCIENCE 〉 SOLID EARTH ; In Situ/Laboratory Instruments 〉 Magnetic/Motion Sensors 〉 Seismometers ; In Situ Land-based Platforms 〉 GEOPHYSICAL STATIONS/NETWORKS ; In Situ Land-based Platforms 〉 GEOPHYSICAL STATIONS/NETWORKS 〉 SEISMOLOGICAL STATIONS
    Type: Dataset , Seismic Network
    Format: ~1T
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  • 60
    Publication Date: 2024-05-21
    Description: Abstract
    Description: Continuous passive seismic monitoring is carried out between September 2017 and December 2021 around the Theistareykir geothermal area located at the intersection between the active Northern Rift Zone and the active Tjörnes Fracture Zone in NE Iceland. This experiment, in addition to an extensive gravimetric monitoring survey, was conducted in the framework of the MicroGraviMoTiS project for a better understanding of the structures and behavior of the local geothermal system under exploitation and for further development of local and regional geothermal resources. 14 broadband stations (Trillium C-120s) recording at 200 Hz comprise the temporary network, that is installed to complement stations of the national seismological network of IMO and stations of Landsvirkjun, the National Power Company of Iceland. The stations were placed in and around the producing zone to primarily retrieve local natural and/or induced seismicity associated to the injection and production operations. The retrieved seismic data is also used for obtaining a representative 1D velocity model of the region, for computing a seismic ambient noise tomography, and for monitoring the system using coda wave interferometry techniques. Funding for this project is provided by the German Federal Ministry for Education and Research (MicroGraviMoTiS , BMBF, grant: 03G0858A), the Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences and Landsvirkjun. Waveform data are available from the GEOFON data center, under network code 3P, and are embargoed until December 2025.
    Keywords: Broadband seismic waveforms ; Seismology ; temporary local seismic experiment ; Monitoring system ; EARTH SCIENCE 〉 SOLID EARTH ; In Situ/Laboratory Instruments 〉 Magnetic/Motion Sensors 〉 Seismometers ; In Situ Land-based Platforms 〉 GEOPHYSICAL STATIONS/NETWORKS ; In Situ Land-based Platforms 〉 GEOPHYSICAL STATIONS/NETWORKS 〉 SEISMOLOGICAL STATIONS ; Passive seismic ; Seismometers ; Velocity ; MiniSEED ; GIPP ; MESI ; Volcano
    Type: Dataset , Seismic Network
    Format: 783GB
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  • 61
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 216 (1994), S. 153-154 
    ISSN: 1572-946X
    Keywords: Chemistry ; Molecular Hydrogen ; Cloud Models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations of the CO J=1-0 line are commonly used as a tracer for molecular material in clouds. The ratio of the H2 column density to the integrated intensity of this line,X, is often taken to be constant, despite theoretical and observational uncertainty. We have tried to identify how this ratio depends on cloud parameters, testing a simple theoretical argument suggesting its invariance with respect to density. The apparent constancy can be understood if clouds are clumpy on scales of Av ≈ 1-2 mag.
    Type of Medium: Electronic Resource
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  • 62
    ISSN: 1573-739X
    Keywords: Antimalarials ; Artemisia annua L ; Artemisinin ; Biosynthesis ; Chemistry ; Clinical trials ; Pharmacology ; Phytochemistry ; Sesquiterpenes ; Toxicology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Artemisinin, a sesquiterpene lactone endoperoxide isolated fromArtemisia annua L., and a number of its semisynthetic derivatives have shown to possess antimalarial properties. They are all eflective againstPlasmodium parasites that are resistant to the newest and commonly used antimalarial drugs. This article gives a survey of the literature dealing with artemisinin-relaled antimalarial issues that have appeared from the end of 1989 up to the beginning of 1994. A broad range of medical and pharmaceutical disciplines is covered, including phytochemical aspects like the selection of high-producing plants, analytical procedures, and plant biotechnology. Furthermore, the organic synthesis of artemisinin derivatives is discussed, as well as their mechanism of action and antimalarial activity, metabolism and pharmacokinetics, clinical studies, sideeffects and toxicology, and biological activities other than antimalarial activity.
    Type of Medium: Electronic Resource
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  • 63
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 76 (1994), S. 703-723 
    ISSN: 1572-9613
    Keywords: Seismology ; migration ; scalar wave equation ; parallel computing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Prospecting for oil and gas resources poses the problem of determining the geological structure of the earth's crust from indirect measurements. Seismic migration is an acoustic image reconstruction technique based on the inversion of the scalar wave equation. Extensive computation is necessary before reliable information can be extracted from large sets of recorded data. In this paper a collection of “industrial” migration techniques, each giving rise to a data parallel algorithm, is outlined. Computer simulations on synthetic seismic data illustrate the problem and the approach.
    Type of Medium: Electronic Resource
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  • 64
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 214 (1994), S. 57-65 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Positive und negative Photostrukturen wurden in einem Polyimid (PI) aus 4,4′-Biphthalsäureanhydrid (BPA) und 4,4′-Diamino-3,3′-dimethyldiphenylmethan (DADMDPM), PI(BPA/DADMDPM) erzeugt, nachdem dieses mit Michlers Keton (MK) bzw. Benzophenon (BP) dotiert und einer ultravioletten Strahlung von 400 ± 50 nm ausgesetzt und naß entwickelt wurde. Das Prinzip der positiven Abbildung basiert auf dem Photokupplungseffekt von MK mit PI, der die Löslichkeit des Polyimids erhöht und so die Entwicklung eines Positivmusters ermöglicht. Die Erzeugung negativer Muster wird durch intermakromolekulare Wasserstoffbrücken zwischen der Carbonylgruppe des Imid-Rings und der Hydroxygruppe, die bei der photoinduzierten Kupplung von Benzophenon mit dem Polyimid gebildet wird, bewirkt. Die lithographische Auswertung zeigt, daß der mit MK dotierte, positive Polyimidfilm nicht in der Lage ist, brauchbare Muster zu erzeugen, da die UV-Wellenlängen von MK absorbiert werden, wodurch die Photokupplung in den tieferen Schichten des Films verhindert wird. Andererseits können in dem 0,6 μm dicken, mit Benzophenon dotierten Polyimidfilm sogar 2 μm schmale Linien aufgelöst werden.
    Notes: Positive and negative photostructures are formed after the polyimide (PI) of 4,4′-biphthalic anhydride (BPA) and 4,4′-diamino-3,3′-dimethyldiphenylmethane (DADMDPM), PI(BPA/DADMDPM) is doped with Michler′s ketone (MK) and benzophenone (BP), respectively, and is subjected to UV light (400 ± 50 nm) irradiation and solvent development. The principle of positive feature formation is based on the photocoupling of MK with PI, which increases PI solubility and thus enables a positive pattern to be developed. The phenomenon of negative photopatterning results from intermacromolecular H-bonding between the carbonyl group of the imide ring and the hydroxy group which is formed in the photoinduced coupling reaction between BP and PI. Lithographic evaluation shows that the MK-doped positive-acting PI film cannot form useful patterns because UV wavelengths are strongly absorbed by MK, which limits the depth of photocoupling in the film. On the other hand, 2-μm-wide lines can be resolved in the BP-doped negative-acting 0.6-μm-thick PI film.
    Additional Material: 5 Ill.
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  • 65
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 214 (1994), S. 101-113 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyhydrazid/Polyamid-Blends (PEHZ12/PA6) wurden durch Niedrigtemperatur-Polykondensation von 4,4′-Dichlorformyl-α,ω-diphenoxydodecan und Terephthaloyldihydrazid (TDH) zu Poly(etheraroylhydrazid) in Gegenwart von Polyamid 6 synthetisiert. Die DSC-Analysen lassen vermuten, daß die zwei Polymerkomponenten nicht wechselwirken. Bei der Extraktion des PA6-Anteils der Blends mit Ameisensäure zeigt die Charakterisierung des PEHZ12-Extraktionsrückstands aber, daß zumindest bei bestimmten Zusammensetzungen Wechselwirkungen zwischen den Komponenten auftreten. Modellreaktionen erlauben die Annahme, daß die PEHZ12-Polymerisation zwischen den Amino-Endgruppen des PA6 und den wachsenden PEHZ12-Polymerketten abläuft.
    Notes: Poly(etheraroylhydrazide) is synthesized in the presence of PA6 by means of low-temperature condensation polymerization of 4,4′-dichloroformyl-α,ω-diphenoxydodecane with terephthaloyl dihydrazide (TDH) in order to prepare polyhydrazide/poly-amide 6 (PEHZ12/PA6) blends. The thermal analysis of the blends by DSC seems to indicate that the two polymers are not interacting. Nevertheless, when the blends are subjected to an extraction process with formic acid in order to remove the PA6, the characterization of the residual PEHZ12 reveales that some interactions do occur between the constituent polymers, at least for selected compositions. Model experiments permit to hypothesize that the polymerization of PEHZ12 proceeds with a chemical interaction between amino end groups of PA6 and growing PEHZ12 chains.
    Additional Material: 7 Ill.
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  • 66
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 214 (1994), S. 179-196 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The crystallization behavior of PBT as well as PC is changed in the controlled-processed blend due to intermolecular interactions between the different macromolecules in molten state.If the kinetics of the crystallization process prevents a crystallization-induced separation, the partial miscibility of the amorphous phases, measured by the glass transition temperatures, will lead to a decrease of the crystallinity of PBT. The crystallinity, normalized to the concentration of PBT in the blend, is independent from the concentration of PC at low coolling rates.At high cooling rates, PBT is crystallizing stepwise in the blend PBT/PC 40/60 wt.-%. The crystallization temperature in the anisothermic crystallization process is increased at low contents of PC due to a changed nucleation mechanism. The half-time of crystallization is increasing in blends with an increasing PC-content in isothermic crystallization experiments.The normally amorphous PC crystallizes considerably fast in presence of PBT in PC-rich blends. The crystallization or change in the state of order of PC was measured in situ by X-ray diffraction. Calorimetric experiments confirm this result and allow a quantitative estimation of the PC-crystallinity, which amounts to some 20% in the blend PBT/PC 5/95 wt.-%.
    Notes: Das Kristallisationsverhalten sowohl von PBT als auch von PC ist im definiert verarbeiteten Blend infolge intermolekularer Wechselwirkungen zwischen den unterschiedlichen Molekülen in der Schmelze verändert.Die über die Glasübergangstemperaturen gemessene teilweise Mischbarkeit der amorphen Phasen führt bei PBT zu einer Erniedrigung des Kristallinitätsgrades, wenn die kinetischen Bedingungen des Kristallisationsprozesses keine kristallisationsbedingte Entmischung zulassen. Der auf den PBT-Anteil normierte Kristallinitätsgrad ist bei kleinen Abkühlgeschwindigkeiten vom PC-Anteil unabhängüg.In der Mischung PBT/PC 40/60 Gew.-% kommt es bei hohen Kühlraten zu einer fraktionierten Kristallisation. Die Kristallisationstemperatur bei anisothermer Kristallisation ist bei geringen PC-Gehalten durch Änderung des Keimbildungsmechanismus erhöht. Bei isothermer Kristallisation steigt mit zunehmendem PC-Anteil die Kristallisationshalbwertszeit des PBT an.Das normalerweise amorphe PC kann in Gegenwart von PBT in den PC-reichen Mischungen besonders schnell kristallisieren, wobei der Kristallisations- bzw. Ordnungsprozeß des PC in situ mittels der Röntgenbeugung gemessen wurde. Kalorimetrische Untersuchungen bestätigen dieses Ergebnis und erlauben eine quantitative Abschätzung des PC-Kristallinitätsgrades zu ca. 20% im Blend PBT/PC 5/95 Gew.-%.
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  • 67
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    Angewandte Makromolekulare Chemie 214 (1994), S. 197-210 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Elementaranalytische sowie NMR-, IR- und UV-spektroskopische Untersuchungen zeigen, daß die Photolyse von Halogenphenolnovolaken zur Substitution der Halogenatome durch Wasserstoff, der Bildung chinoider Gruppen und intermolekularen Vernetzung führt. Die Geschwindigkeit der Halogeneliminierung hängt von der Art des Halogens ab. Sie steigt in der Reihenfolge F 〈 Cl 〈 Br 〈 I. Die Chloreliminierung aus der 4-Position ist gegenüber der aus der 2- und 3-Position begünstigt. Außerdem verläuft die Abspaltung para-ständiger Chloratome aus Dimeren schneller als aus Trioder Tetrameren. ESR-Messungen bei 77 K sowie die Laserblitzphotolyse bei 296 K deuten auf die intermediäre Bildung von Phenoxyl- und Arylradikalen. Lithographische Tests belegen die hohe UV-Empfindlichkeit von Resisten auf der Basis von Halogenphenolnovolaken. Im Vergleich zu nichthalogenhaltigen Novolakresisten wird eine 6 - 10fache (System: 4-Chlorphenolnovolak/4,4′-Bisazidobiphenyl (5%)) bzw. eine ca. 25fache (System: 4-Chlorphenol-/m-Cresolnovolak/Hexamethoxymethylmelamin (5%)) Steigerung der Empfindlichkeit erreicht. Zur Interpretation wird ein Mechanismus postuliert, demzufolge die durch Halogenabspaltung hervorgerufene Sekundärradikalbildung zu einer zusätzlichen Vernetzung beiträgt. In den melaminhaltigen Resisten katalysiert der gebildete Halogenwasserstoff (Hal· + RH → H-Hal + R·) außerdem die Reaktion der Melaminverbindung mit der Novolakmatrix.
    Notes: The photolysis of halogenophenol novolacs is determined by the substitution of halogens by hydrogen and the formation of quinoid groups and intermolecular crosslinks. This is concluded from elemental analysis, NMR, IR and optical absorption measurements. The rate of halogen release depends on the chemical nature of the halogen. It increases in the order F 〈 Cl 〈 Br 〈 I. Chlorine elimination from 4-position is favored over that from 2- and 3-position. Moreover, dimers release chlorine from 4-position much more readily than trimers and tetramers. ESR measurements at 77 K and flash photolysis studies at 296 K yielded evidence for the intermediate existence of phenoxyl and aryl radicals. Lithographic tests demonstrated the high UV-sensitivity of resist formulations based on halogen-containing novolacs. The increase in sensitivity relative to that of formulations based on nonhalogenated novolacs is 6 to 10fold system: 4-chlorophenol novolac/4,4′-bisazidobiphenyl (5%) and ca. 25fold system: 4-chlorophenol/m-cresol novolac/hexamethoxymethylmelamine (5%). A postulated reactions mechanism concerning the sensitivity increase takes into account that halogen elimination results in the formation of additional radicals that accelerate the rate of crosslinking. Moreover, hydrogen halide generated by hydrogen abstraction of halogen radicals (Hal· + RH → H-Hal + R·) provides for the acid required to catalyze the reaction of the melamine compound with the novolac matrix.
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  • 68
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    Angewandte Makromolekulare Chemie 215 (1994), S. 11-24 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Calciumcarbonate unterschiedlicher Teilchenform (sphäarisch, kubisch und nadelfäormig) wurden mit Polypropylen (PP) in einer Zwei-Walzen-Mäuhle gemischt und anschließend zu Platten gepreßt. Der Einflußder Teilchenform auf das Kristallisationsverhalten der PP/CaCO3-Composite, d.h. Kristallisationspeaktemperatur (Tmax), Kristallisationsverlauf usw., wurde mittels Differentialkalorimetrie untersucht. Der Wert von Tmax häangt von der Größe der Gesamtoberfläache der CaCO3-Teilchen ab; Tmax ist bei nadelfäormigen Teilchen gräoßer als bei kubischen oder sphäarischen und hauangt in allen Fäallen der nicht-isothermen Kristallisation von der Abkäuhlgeschwindigkeit und der vorher erreichten maximalen Temperatur ab.
    Notes: Calcium carbonate of various particle shape (spheric, cubic, needle-shaped type) and polypropylene (PP) were mixed on a two roll mill and the mixture was pressed into plates. The effect of particle shape on the crystallization behavior of PP/CaCO3 composites, such as crystallization peak temperature (TMAX), crystallized pattern, etc., was investigated with differential scanning calorimetry measurements. The value of TMAX is explained by the total surface area of added CaCO3 particles; TMAX of needle-shaped series is larger than that of cubic or spheric ones. TMAX of various shaped CaCO3-filled PP totally depends on the cooling rate and maximum temperature in the non-isothermal crystallization, respectively.
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  • 69
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    Angewandte Makromolekulare Chemie 215 (1994), S. 107-119 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Polyaddition von Polyethylenglykol (PEG) Oligoglycidylethern (Mn (PEG): 396,587, 1437 und 3554) mit asymmetrischen Diaminen, wie N,N-Dimethylund N,N-Diethyl-1,3-diaminopropan, wurden wasserläosliche kationische Polymere erhalten. Die Eigenschaften der kationischen Polymeren sind vom urspräunglichen PEG-Molekulargewicht und der Diaminreaktivitäat abhäangig. PEG mit Mn = 396 zeigt das beste Verhalten. In verdäunnten wäassrigen Läosungen und in wäassrigen 2M NaCl-Läosungen der Polymeren wurde das Polyelektrolytverhalten veranschaulicht. Die Gegenwart der PEG Kette bestimmt das Polyelektrolytverhalten in den 2M NaCl Läosungen.
    Notes: Water-soluble cationic polymers were obtained by polyaddition of poly(ethylene glycol) (PEG) diglycidylethers (M̄n of PEG were 396, 587, 1437 and 3554, resp.) with asymmetrical diamines such as N,N-dimethyl-1,3-diaminopropane and N,N-diethyl-1,3-diaminopropane. The cationic polymer properties depend on the PEG initial molecular weight and on the diamine reactivity too. PEG with M̄n = 396 had the best behaviour in these reactions. The polyelectrolyte feature of cationic polymers was emphasized both in dilute aqueous solutions and in 2M aqueous NaCl solutions. The polyelectrolyte behaviour in 2M aqueous NaCl solution is determined by the PEG chain presence.
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    Angewandte Makromolekulare Chemie 215 (1994), S. 139-145 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Reaktion von o-Kresol mit Formaldehyd wurde unter Verwendung verschiedener tertiäarer Amine als Katalysatoren untersucht. Der Einfluß der Reaktionsparameter Basizitäat, Temperatur, Reaktionszeit und Formaldehydkonzentration wird diskutiert. Für die bevorzugte Bildung von 2,4-Bis(hydroxymethyl)-6-methylphenol wurden optimierte Synthesebedingungen erarbeitet. Die Bildung von Zwei-bzw. Mehrkernprodukten konnte nicht ausgeschlossen werden.
    Notes: The reaction between o-cresol and formaldehyde was investigated using various tertiary amines as catalysts. The influence of the reaction parameters basicity, temperature, reaction time and concentration of formaldehyde was discussed. To yield preferentially 2,4-bis(hydroxymethyl)-6-methylphenol the conditions of synthesis were optimized. The formation of bi- and polynuclear products cannot be avoided.
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    Angewandte Makromolekulare Chemie 215 (1994), S. 189-200 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Scherviskositäat fläussigkristalliner Ethylcellulose, die mit Cellulosepulver unterschiedlicher Partikelgräoße gefäullt war, wurde bei konstantem Schergefäalle mit einem Kegel-Platte-Viskosimeter bestimmt. Der Einfluß des Cellulosepulvergehalts, des Läange/Breite-Verhäaltnisses der Pulverteilchen und der Temperatur auf das viskose Verhalten und die Phasenäubergäange wird diskutiert. Der Zusatz von Cellulosepulver erhäoht die Viskositäat und verringert die Aktivierungsenergie des Fließens(Ea), ohne jedoch die Phasenäubergäange zu beeinflussen. Die Viskositäat und die Aktivierungsenergie sind abhäangig vom Läange/Breite-Verhäaltnis der Pulverteilchen; mit zunehmender Gräoße dieses Verhäaltnisses wird die Viskositäatszunahme beschleunigt und die Aktivierungsenergie des Fließens erhäoht, wäahrend die Aktivierungsenergie mit steigendem Pulvergehalt abnimmt. Die Phasenumwandlungen sind unabhäangig von der Partikelform. Der Einfluß des Pulvergehalts auf Viskositäat und Aktivierungsenergie ist abhäangig von der Art der fläussigen Phase; in der anisotropen Phase ist der Einfluß geringer als in der isotropen Phase. Dies scheint von der Ausrichtung der Pulverteilchen und der stäabchenfäormigen Molekäule herzuräuhren.
    Notes: Steady-state shear viscosity for the liquid crystalline ethyl cellulose solution filled with cellulose powders was determined using a cone-plate-type viscometer and the effects of cellulose powder content, powder aspect ratio and temperature on the viscometric behavior and phase transformation were discussed. The addition of powder increased the viscosity and decreased the activation energy (Ea) for flow, but did not affect the phase transformation. The viscosity and Ea depended on the aspect ratio; with greater aspect ratio, the viscosity enhancement was accelerated and Ea as well as the decrease in Ea with powder content increased. The phase transformation did not depend on the aspect ratio, the dependences of viscosity and of Ea on powder content depended on the solution phase; the dependences for the anisotropic phase were smaller than those for the isotropic one. The findings appeared to originate from the alignments of powders and rod-like molecules.
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The UV-degradation of an unstabilized and two HALS stabilized polyethylene (PE) films is described. The degradations are characterized by measuring the oxygen uptake, the formation of CO and CO2, the FT-IR spectra, the mechanical properties, the stabilizer concentration and the oxygen content of the film.The oxygen uptake of the unstabilized PE film led to the expected changes in the IR spectra and embrittlement of the film, while the oxygen uptake by the HALS stabilized films caused only minor changes. The differences between the results for the unstabilized and the HALS stabilized polymers are explained assuming that the initiation of the photodegradation of PE is due to charge transfer complexes.
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Principal chemical pathways characteristic of active participation of radical scavenging polymer stabilizers (phenols, aromatic, hydroaromatic and hindered aliphatic amines) are outlined. Pathways resulting in a partial depletion or distortion of activity of stabilizers, in formation of polymer discolouring products, or in interactions in bifunctional stabilizers are involved.
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  • 74
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Irradiations (λ≥300 nm) of poly(butyleneterphtalate) films were carried out in both vacum and air. Photoproducts were investigated by FTIR spectroscopy, chemical derivatization reactions and physical treatments. The repartition of photoproducts in the polymer was shown to be heterogeneous. A scheme accounting for the main routes of PBT photolysis was found on the basis of photoproducts identification. Most of oxidation products were analogous to vacum photolysis species; the mechanism of photooxidation proposed implied both pure photolytical processes and a photo-induced oxidation route.
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  • 75
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of polymer density, processing conditions (quenching of annealing), degree of crystallinity, size of crystallite and mobility of polymer chains on the photo-and radiation-induced degradation and the polymer stability have been studied by UV, FTIR spectroscopic, viscosity and mechanical property measurements. Four kinds of annealed or quenched polyethylene (PE) films varying densities were used to the studies. Polystyrene (PSt) films were used to investigate the effect of chain mobility on polymer degradation. The following results were obtained. 1.In linear low density (LLD) PE, greater amounts of crosslinking (irradiated in vacuum) and chain scission (irradiated in air) were noticed than in mediun density (MD) PE and high density (HD) PE samples.2.Polyene formation is favored in the case of the irradiation in vacuum for LLDPE.3.Polymer stability evaluated by mechanical property such as elongation at break (%) is superior in LLDPE to MDPE and HDPE for annealed and quenched samples.4.Segmental motion of polymer chain also affects the polymer stability
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    Angewandte Makromolekulare Chemie 217 (1994), S. 43-49 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The study is on two component blends of high density polyethylenes, having normal and ultra-high molecular weight. The polyethylenes were homogenized by two routes: in powder state or by rolling in melt, then pressed at temperatures in the range from 140°C to 220°C. Comparative studies showed that the way of homogenizing of the components does practically not affect the main mechanical properties of the blends when pressed at temperatures ≥ 160°C. Of special interest are the characteristics of those systems where ultra-high molecular weight polyethylene is the matrix component.
    Notes: Untersucht wurden binäre Mischungen von Polyethylenen hoher Dichte rnit normaler und ultrahochmolekularer Molmasse, die auf zweierlei Weise - in Pulverform oder durch Walzen im Schmelzezustand - homogenisiert und bei Temperaturen zwischen 140 und 220°C gepreßt waren.Es wurde festgestellt, daß die Art der Homogenisierung der Komponenten praktisch keinen Einfluß auf die Eigenschaften bei Preßtemperaturen ≥ 160°C hat. Von besonderem Interesse sind die Eigenschaften der Systeme, in welchen das ultrahochmolekulare Polyethylen die Rolle der Matrixkomponente spielt.
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    Angewandte Makromolekulare Chemie 218 (1994), S. 81-109 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das Verhalten eines neuartigen photoinitiierenden Systems, das die Polymerisation von pigmenthaltigen Schichten großer Dicke in einem Reaktionsschritt gestattet, wird dargestellt. Die verschiedenen Wechselwirkungen, die in einem pigmenthaltigen System auftreten, werden qualitativ beschrieben, und der Anteil der von einem Photoinitiator absorbierten Lichtintensität wird berechnet. Neben dem Absorptions- und Reflexionsverhalten von verschiedenen Pigmentklassen werden die optischen Eigenschaften verschiedener Strahlungsquellen untersucht, um die Strahlungsbereiche zu finden, die am besten mit den optischen Parametern der Pigmente korrespondieren. Weiterhin wird die Beschleunigung von Polymerisationen durch die photokatalytische Wirkung einiger Pigmente behandelt.
    Notes: Ce travail sur le rôe des pigments définit le comportement d'un nouveau systeme photosensible qui permet de polymériser des milieux épais et pigmentés selon un procédé en une seule étape. Les différentes interactions présentes en milieu pigmenté sont décrites de façon qualitative, et la part de l'intensité lumineuse absorbée par un photo-amorceur dans un systéme pigmenté est evaluée. Les propriétés optiques telles que l'absorption et la réflectance des différentes familles chimiques de pigments sont déterminées, et, en paralléle, les propriétés optiques des différentes sources d'irradiation sont étudiées de manière à répondre au mieux aux fenêtres de transmission des pigments. L'effet photocatalytique de certains pigments est mentionné, ceci afin d'amkliorer la réaction de polymérisation.
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    Angewandte Makromolekulare Chemie 218 (1994), S. 153-162 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Herstellung von cis-1,4-Polybutadien erfolgte mittels Polymerisation von 1,3-Butadien mit einem Katalysatorsystem, das in einer zweistufigen Reaktion gebildet wird: (1) BF3 · O(C2H5)2 und Al(C2H5)3, (2) Ni(OOC8H15)2 und Al(C2H5)3, genannt in-situ-Katalysatorsystem.Die Molmassenverteilungen (MMD) der erhaltenen Polymeren sind mit der Größenausschlußchromatographie (SEC) untersucht worden. Sie lassen sich mit Summen aus Schulz-Flory-Funktionen (SFF) beschreiben. Veränderte Katalysatorformierungs- und Polymerisationsbedingungen beeinflussen die Parameter der SFF. Veränderte Peakflächen und Molmassenmittelwerte der Einzelpeaks zeigen, daß die Polymerisation über mehrere Arten aktiver Zentren verläuft.
    Notes: Cis-1,4-polybutadiene was produced by polymerization of 1,3-butadiene using a catalyst system formed by a two-step formation, Namely (1) BF3 . O(C2H5)2 and Al(C2H5)3, (2) Ni(OOC8H15)2 and Al(C2H5)3 named in-situ-catalyst.The molar mass distributions (MMD) of the polybutadienes are investigated by means of size exclusion chromatography (SEC). The MMD's were fitted by a sum of Schulz-Flory-Functions (SFF). Changed catalyst formation and polymerization conditions influenced the parameters of the SFF. Changed areas and changed molar mass averages indicate a polymerization with more than one peak maximum and kind of active species and lead to a better understanding of the polymerization.
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    Angewandte Makromolekulare Chemie 219 (1994), S. 1-10 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Umsetzung von Chromacrylat mit Bisphenol A und einem Überschuß Epichlorhydrin wurden neuartige Epoxid-Harze hergestellt. Epoxy-Äquivalentgewicht, Gehalt an Hydroxygruppen und hydrolysierbarem Chlor sowie die Viskosität wurden bestimmt, und die Harze wurden mittels IR- und 1H-NMR-Spektroskopie charakterisiert. Die thermischen Eigenschaften der bei 30°C für 24 h mit Ciba Geigy HY 850 (aliphatisches Amin) gehärteten Harze wurden gemessen. Die Harze besitzen eine gute thermische und chemische Stabilität und eine gute elektrische Leitfähigkeit. Die Reaktion verläuft nach erster Ordnung; die Aktivierungsenergie beträgt 47 kJ mol-1 bzw. 34 kJ mol-1 mit bzw. ohne Chromacrylat. Aus spektroskopischen Untersuchungen wird geschlossen, daß das Chrom mit Bisphenol A einen Komplex bildet, der die Epoxidierung beschleunigt.
    Notes: Novel epoxy resins containing chromium acrylate have been synthesized by reacting chromium acrylate with bisphenol-A and excess epichlorohydrin. The quantities such as epoxy equivalent weight, hydroxy content, hydrolyzable chlorine content and viscosity have been determined. The resins have been characterized by IR and 1H NMR spectroscopy. The cured resins were evaluated for thermal properties. The curing of resins was carried out with Ciba Geigy HY 850 (aliphatic amine adduct) at 30°C for 24 h. The cured resins have excellent thermal and chemical resistance, in addition to an excellent electrical conductivity. The reaction follows first order kinetics with an activation energy of 47 kJ mol-1 and 34 kJ mol-1 in the presence and absence of chromium acrylate, respectively. The chromium forms a complex with bisphenol-A, as indicated by spectroscopic studies, which increases epoxidation.
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    Angewandte Makromolekulare Chemie 219 (1994), S. 67-76 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Interpenetrierende Polymernetzwerke (IPNs) aus Polystyrol und Polyurethan auf der Basis von hydroxyterminiertem Naturkautschuk mit unterschiedlichen NCO/OH-Verhältnissen wurden unter verschiedenen Reaktionsbedingungen hergestellt und zu widerstandsfähigen Filmen verarbeitet. Die IPNs wurden durch ihre physikalischen, mechanischen und morphologischen Eigenschaften wie Dichte, Shore-A-Härte, Vernetzungsdichte, Zugfestigkeit und Reißdehnung charakterisiert. Mit steigendem Polystyrolgehalt erhöhen sich auch Dichte, Shore-A-Härte und Zugfestigkeit, während die Reißdehnung abnimmt. Die Untersuchungen der Vernetzungsdichte lassen eine Phasenumkehr vermuten.
    Notes: Interpenetrating polymer networks (IPNs) of polyurethane based on hydroxyterminated natural rubber with varying NCO/OH ratios and polystyrene were synthesized under different experimental conditions. These IPNs were found to make tough films. The IPNs were characterized by their physical, mechanical and morphological properties like density, Shore-A hardness, crosslink density, tensile strength and elongation at break. The IPNs exhibited an increasing trend in density, Shore-A hardness and tensile strength with increasing polystyrene content, while elongation at break decreased with similar variation in polystyrene content. The crosslink density measurements indicated a possible phase inversion process.
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    Angewandte Makromolekulare Chemie 219 (1994), S. 117-124 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß einer Plasmabehandlung von Ultrafiltrationsmembranen aus Polyethylen auf die Fouling- und Reinigungseigenschaften bei der Filtration von Rinderserumalbumin werden diskutiert. Bei 2,45 GHz erzeugtes Luft-Plasma steigert die Hydrophilie der Membranoberfläche von 0 auf 60%. Der Durchfluß bleibt bei 90 bis 99%. Mit Plasma behandelte Membranen sind leichter zu reinigen als unbehandelte; dennoch sind sie anfälliger für die Ablagerung von Rinderserumalbumin.
    Notes: The effect of plasma treatment of polyethylene ultrafiltration membranes on fouling and cleaning phenomena during filtration of bovine serum albumin solutions is discussed. Air-plasma of 2.45 GHz raises the membrane surface hydrophilicity from 0 up to 60%. The flux is maintained at 90-99%. Plasma-treated membranes are easier to clean than untreated polyethylene membranes. Despite that, the plasma-modified membranes are susceptible to more intensive deposition of albumin.
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    Angewandte Makromolekulare Chemie 219 (1994), S. 101-115 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Immobilisierung von Glucose-Oxidase in einer Poly(vinylalkohol) (PVAL)-Membran in Gegenwart von UV-Photoinitiatoren wurde untersucht. Enzym-Membranen wurden aus PVAL-Diazoharz- und PVAL-Photoinitiator-Systemen durch Vernetzung mit UV-Licht hergestellt. Mit diesen immobilisierten Glucose-Oxidase-Membranen wurde eine wirkungsvolle Enzymelektrode entwickelt, deren Eigenschaften untersucht wurden. Der Einfluß der Photoinitiatorkonzentration in Poly(vinylalkohol) und der UV-Bestrahlungsdauer auf den Grad der Unlöslichkeit sowie die Aktivitätsausbeute der Membran wurden mit Glucose als Substrat untersucht. Temperatur- und pH-Abhängigkeit der relativen Aktivität, Stabilität bei mehrmaligem Gebrauch, Lagerstabilität und Kalibrierungsdiagramme der Enzym-Membranen wurden ermittelt. Eine beim Erstgebrauch auftretende Instabilitätserscheinung der Membranen wurde ebenfalls untersucht.
    Notes: A study of the immobilization of glucose oxidase on a poly(vinyl alcohol) (PVAL) membrane in the presence of UV sensitizers was carried out. Enzyme membranes were prepared from PVAL-diazoresin and PVAL-sensitizer systems, crosslinked by means of UV irradiation. An effective enzyme electrode was developed by using the immobilized glucose oxidase membrane, and its characteristics were investigated. The effects of the concentration of sensitizers in poly(vinyl alcohol) and UV irradiation time on the degree of insolubility as well as the activity yield of the membrane were examined for the immobilized glucose oxidase using glucose as a substrate. Temperature and pH dependences of the relative activity, stability in repeated use, storage stability and calibration plots of the enzyme membranes were evaluated. The unstability phenomenon, found in the initial use of the immobilized glucose oxidase membrane, which was prepared from PVAL-sensitizer system, was also investigated.
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  • 83
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    Angewandte Makromolekulare Chemie 219 (1994), S. 11-26 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Biopol, Biocellat and Mater-Bi, three biologically decomposable plastics have been tested for their use in medical industries. Biopol did not loose its stress and stiffness under sterilisation, and was also resistant against temperature and alcohol. Mater-Bi and Biocellat, the two other materials, did not satisfy the test applications. Water vapor sterilisation, temperature up to 60°C, at higher temperatures this material will embrittle.
    Notes: Für den Einsatz biologisch abbaubarer Kunststoffe in der pharmazeutischen Industrie und Medizintechnik wurden Produkte verschiedener Hersteller, wie Biopol, Biocellat und Mater-Bi untersucht. Dabei zeigte vor allem Biopol das notwendige Anforderungsprofil, d.h. die Anwendbarkeit aller Sterilisationsverfahren ohne Festigkeitsbzw. Steifigkeitsverluste sowie Temperatur- und Alkoholbeständigkeit. Dagegen wiesen die Werkstoffe Mater-Bi und Biocellat einige Schwachstellen auf. Bei Mater-Bi lagen diese bei der Wasserdampfsterilisation sowie bei der geringen thermischen und Medienbeständigkeit. Biocellat versprödet dagegen durch die erhöhte Temperatur bei der Dampfsterilisation, d.h. daß ein Einsatz über 60°C nicht möglich wäre.
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  • 84
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Alkylierung von Poly(5-vinyltetrazol) mit Dimethylsulfat und tert-Butylalkohol sowie Alkylhalogeniden RHal (R=CH3, C2H5, CH2—CH=CH2, n-C4H9 und t-C4H9) und die Kinetik dieser Reaktion wurden untersucht, um eine neue Herstellungsmethode für tetrazolhaltige Polymere mit wertvollen Eigenschaften zu entwickeln. Die vergleichenden Untersuchungen über die isomere Zusammensetzung und die spektroskopischen Daten von Poly(N-alkyl-5-vinyltetrazol)en, die durch die Alkylierung von Poly(5-vinyltetrazol) sowie durch die Copolymerisation der entsprechenden Monomeren hergestellt wurden, wurden mit IR-, 1H-NMR- und 13C-NMR-Spektroskopie durchgeführt. Der Alkylierungsumsatz beträgt bis zu 99,8%; dadurch können polymere Produkte erhalten werden, deren Zusammensetzung, Struktur und Eigenschaften denen der Homo- und Copolymeren sehr ähnlich sind.
    Notes: Alkylation of poly(5-vinyl tetrazole) with dimethyl sulfate and tert-butyl alcohol as well as with alkyl halides RHal (R=CH3, C2H5, CH2—CH=CH2, n-C4H9, t-C4H9) has been studied under various conditions in order to develop a new method of synthesis of tetrazole-containing polymers having a complex of valuable properties. The kinetic study of the process and comparison of isomeric compositions and spectroscopic characteristics (IR, 1H NMR and 13C NMR) of poly(N-alkyl-5-vinyl tetrazole)s synthesized by alkylation of poly(5-vinyl tetrazole) and of those prepared by (co)polymerization of the corresponding vinyl tetrazoles have been carried out. The alkylation is found to proceed to high conversion extents (up to 99.8%) and enables to obtain a wide variety of polymeric products having the composition, structure and properties very similar to those of homo- and copolymers.
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  • 85
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Farbstoffe mit nichtlinearen optischen Eigenschaften wurden in einer zweistufigen Synthese aus 2-Hydroxyethylmethacrylat (HEMA), 4-Carboxybenzaldehyd und verschiedenen Anilinderivaten hergestellt. Die Farbstoffe (aromatische Iminester von HEMA) wurden mit Styrol copolymerisiert, die erhaltenen Copolymere wurden mit DSC sowie IR-, 1H NMR- und UV-VIS-Spektroskopie charakterisiert, und ihre nichtlinearen Eigenschaften wurden untersucht. Es zeigte sich, daß die nichtlinearen Koeffizienten d31 und d33 vom Farbstoffgehalt der Copolymeren und der Art der elektronenspendenden Gruppen abhängig sind.
    Notes: Dyes for nonlinear optics have been synthesized in two steps from 2-hydroxyethyl methacrylate (HEMA), 4-carboxybenzaldehyde and various substituted anilines. The obtained dyes (aromatic imine esters of HEMA) have been copolymerized with styrene, the copolymers characterized by DSC as well as IR, 1H NMR and UV-VIS spectroscopy, and studied for their nonlinear properties. The d31 and d33 nonlinear coefficients proved to be dependent on the dye content of the copolymers and on the nature of electrondonating groups.
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  • 86
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    Angewandte Makromolekulare Chemie 220 (1994), S. 123-132 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß von Ca2+-bzw. Al3+-Ionen auf das Viskositätsverhalten (Salzverträglichkeit) wäßriger Lösungen von Natriumcarboxymethylcellulose (CMC) sowohl mit unterschiedlichem Polymerisationsgrad (DP) als auch mit unterschiedlichem Substitutionsgrad (DS) und verschiedenartiger Substitutentenverteilung wurde untersucht. Aus Viskositätsmessungen mit einem Rotationsviskosimeter bei einer Scherrate von 500 s-1 geht hervor, daß die relative Abnahme der Viskosität im Ergebnis des Zusatzes der mehrwertigen Metallkationen unabhängig vom DP (im Bereich von 160 bis 900) der CMC ist. Homogen hergestellte CMC-Proben 2 mit einem größeren Gehalt an 2,3,6-Tri-O-carboxymethylglucose-Einheiten in der Polymerkette weisen im Vergleich zu heterogen hergestellten CMCs 1 bei gleichem Gesamt-DS eine höhere Salzverträglichkeit auf.
    Notes: The influence of Ca2+-and Al3+-ions, respectively, upon the viscosity behaviour (so-called salt tolerance) of aqueous solutions of sodium carboxymethyl cellulose (CMC) with different degree of polymerization (DP) and, on the other hand, with both different degree of substitution (DS) and distribution of substituents, was investigated. Viscosimetry by means of a rotational rheometer at a shear rate of 500 s-1 shows that the relative drop in viscosity as a result of addition of the multivalent metal cations is independent of DP (ranging from 160 to 900) of the CMC samples. Homogeneously synthesized CMCs (2) with a higher content of 2,3,6-tri-O-carboxymethyl glucose units in the polymer chain possess a significantly higher salt tolerance than those (1) prepared under heterogeneous reaction conditions at comparable total DS values.
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  • 87
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    Angewandte Makromolekulare Chemie 222 (1994), S. 61-87 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Melamin-Formaldehyd-Harz-Formmassen (MF) wurden durch mechanisches Mischen mit Ethylen-Vinylacetat-Copolymeren (EVA) und teilverseiftem EVA modifiziert, wobei Etherbindungen zwischen dem hydrolysierten EVA und dem MF-Harz nachgewiesen werden konnten, die die mechanischen Eigenschaften von spritzgepreßten Formteilen im Vergleich zur Modifizierung mit EVA verbessern. Der Zusatz solcher Modifikatoren erhöht die Duktilität und verringert im Falle von EVA die Nachschwindung der überaus steifen MF-Matrix, solange der Modifikatoranteil gering bleibt. Dagegen werden die Steifigkeit und die Wärmeformbeständigkeit verschlechtert. Die durch solche unvernetzten Polymeren erreichbare Steigerung der Schlagzähigkeit bleibt allerdings unzureichend.
    Notes: Melamine-formaldehyde moulding compounds (MF) were modified by mechanical mixing with ethylene/vinyl acetate copolymers (EVA) and with partially hydrolysed EVA. Ether linkages between the hydrolysed material and the MF resin improve the mechanical properties of the transfer moulded parts containing the hydrolysed material compared to those made with EVA. The use of both modifying polymers improves the ductility and, in case of the partially hydrolysed material, the postshrinkage of the extremely rigid MF matrix, as long as the modification polymer content is kept low. On the contrary, Young's modulus and the heat deflection temperature are deteriorated. The improvement in impact strength by use of those uncrosslinked polymers is still insufficient.
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  • 88
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    Angewandte Makromolekulare Chemie 222 (1994), S. 111-123 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe von Copolyesteramiden mit Molekulargewichten zwischen 1000 und 7000 (GPC, NMR) wurden aus Adipinsäure/1,6-Hexandiamin/∊-Caprolacton bzw. Nylon 6,6-Salz/∊-Caprolacton hergestellt. Die thermischen Eigenschaften der synthetisierten Polymeren (Glasübergangs-, Schmelz-, und Zersetzungstemperaturen, Schmelzenthalpien) wurden durch DSC- und TGA-Messungen bestimmt und in Bezug auf das Comonomerverhältnis in der Ausgangsmischung diskutiert. Die Übereinstimmung der Copolymerzusammensetzung mit dem Ausgangscomonomerverhältnis wurde mit FT-IR- und NMR-Spektroskopie untersucht. Die Bioabbaubarkeit der Copolyesteramide wurde durch enzymatische Hydrolyse geprüft.
    Notes: A series of copolyesteramides based on adipic acid/1,6-hexane diamine/∊-caprolactone and Nylon 6,6 salt/∊-caprolactone were synthesized. Their molecular weights, determined by gel permeation chromatography and NMR spectroscopy, were found to lie within the range from 1000 up to 7000. Their thermal properties (glass transitions, melting points and heats of melting, and decomposition temperatures) were recorded with diferential scanning calorimetry and thermogravimetry, respectively, and correlated to the comonomer feed composition. The FT-IR and NMR spectra were also recorded in order to confirm the composition of the copolyesteramides and to compare them with that of the comonomer feed. The biodegradability of the synthesized copolymers was tested by enzymatic hydrolysis.
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  • 89
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    Angewandte Makromolekulare Chemie 222 (1994), S. 165-174 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch sulfonsäurekatalysierte Umsetzung von Abietinsäure und Paraformaldehyd bei hohen Temperaturen wurden neuartige Kondensationsprodukte erhalten. Als Nebenprodukte der Polykondensation werden eine Ketoverbindung sowie Wasser und Kohlendioxid gebildet. Die Carboxygruppen der Abietinsäure sind an der Kondensationsreaktion beteiligt. In Abwesenheit von Paraformaldehyd wurde das Abietinsäure/Sulfonsäurekatalysator-System untersucht, um zusätzliche Informationen über die Reaktion zu erhalten. Der Reaktionsverlauf hängt von der Temperatur und der chemischen Struktur des Katalysators ab. Ein möglicher Reaktionsmechanismus der Kondensation wird diskutiert.
    Notes: New condensation products have been synthesized by heating abietic acid and formaldehyde at high temperatures in the presence of sulfonic-type acid catalysts. The main polycondensation reaction is associated with a secondary one which leads to a ketonic compound, carbon dioxide and water. The carboxylic groups of abietic acid participate in this condensation reaction. The behaviour of the abietic acid-sulfonic acid catalyst system was studied in absence of formaldehyde to acquire additional information about the reaction. The process is defined by the reaction temperature and chemical nature of the catalyst. A possible mechanism of the condensation reaction is discussed on the basis of the obtained results.
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  • 90
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    Angewandte Makromolekulare Chemie 223 (1994), S. 1-11 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: After a general classification of the cationic ring-opening polymerizations (CROP's) according to their polymerization mechanism, a number of examples of tailored polymers based on CROP are presented. The monomers used for the synthesis of these tailored structures are tetrahydrofuran (THF), N-tert-butyl aziridine (TBA), 2-methyl-1,3-oxazoline (MeOX) and 1,3-dioxolane (DXL).The polymer structures include different block and graft copolymers, macromonomers, star-shaped polymers, polymer networks and interpenetrating polymer networks (IPNs).
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  • 91
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In diesem Beitrag wird ein überblick über neuere Entwicklungen auf dem Gebiet der Synthese von Telechelen, Makromonomeren, Block- und Pfropfcopolymeren gegeben. Synthesestrategien aus den Bereichen der Polykondensation, der radikalischen, anionischen und kationischen Polymerisation, der Kettenspaltung sowie der Criss-Cross-Cycloaddition werden diskutiert.
    Notes: New developments in the synthesis of telechelics, macromonomers, block- and graftcopolymers are presented. Synthetic strategies for them are demonstrated with examples from different fields such as polycondensation, radical, anionic, and cationic polymerization, chain cleavage and criss-cross-cycloaddition.
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  • 92
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    Angewandte Makromolekulare Chemie 223 (1994), S. 69-79 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Alkanes with highly substituted carbon-carbon bonds can be cleaved in free radicals by homolytic dissociation under the influence of thermal energy. The energy of dissociation is mainly determined by the type and size of the respective substituents. For tetraarylbutane dinitriles the temperatures of decomposition are in the range of other technically used initiators. But nevertheless, these compounds are up to now rather seldom used to initiate free radical polymerizations. This is connected with the special mechanism of initiation: the formed highly substituted alkyl radicals are relatively stable and show only a rather low reactivity against the usually used monomers. Therefore, in the beginning of the polymerization the radical concentration is rather high which leads not only to addition to monomers but also to a pronounced primary radical termination. In some cases this termination process is reversible which results in an unusual polymerization kinetics. Depending on the type of monomer and the degree of reversibility of the primary radical termination, either a period of “dead-end” polymerization follows or the cleavage of the oligomers at the chain end results in a re-initiation process with a “normal” polymerization with increased rate. The reaction mechanism, kinetics and some possible applications of such initiating alkanes are reported.
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  • 93
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    Angewandte Makromolekulare Chemie 223 (1994), S. 121-133 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Untersuchungen wesentlicher Aspekte der Polymerisation und der Eigenschaftsmodifikation auf Metallocen-Katalyse basierender Cycloolefin-Copolymere (COC) zeigen, daß mit dieser Monomer-Katalysator-Kombination eine neue Klasse transparenter Thermoplasten zugänglich gemacht wird. COC können mit Metallocenen in beliebiger zusammensetzung und mit kontrollierter Mikrostruktur hergestellt werden. Die somit erreichte und durch zusätzliche Modifikationen noch erweiterbare Breite des Eigenschaftsspektrums ermöglicht vielfältige Anwendungen dieser neuen Polymerklasse. Die wichtigsten Schlüsselfaktoren im rohstofflich-technologischen Bereich, die diese Struktur- und Eigenschaftsvielfalt ergeben, werden beispielhaft beschrieben.
    Notes: Investigation of the polymerization process and property modification of metallocene-based cycloolefin copolymers (COC) shows that this monomer-catalyst combination enables synthesis of a new class of transparent thermoplastic polymers. Metallocene catalysis offers much opportunity to vary the composition and microstructure of the copolymers. The breadth of the polymer spectrum which can be further widened by polymer modification enables many applications for this new class of thermoplastics. The key parameters that control structure and properties in the COC family are discussed in this paper.
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  • 94
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    Angewandte Makromolekulare Chemie 223 (1994), S. 165-175 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The present paper deals with the synthesis and modification of functionalized polymers characterized by a special molecular architecture. The reactivity of a functionalized polymer with comb-like structure can be controlled in a significant manner by the crystalline order of the side chains. In contrast, photocrosslinking of comblike polymers containing cinnamic components in the side chains influences the crystallization process. The air drying process of a modified polybutadiene system with comb-like structure was shown to depend sensitively on the side chain order. Enzymatic synthesis of new monomers and polymers is briefly reviewed. The complexing capability of cyclodextrines were used to synthesize polyrotaxanes. Finally, the synthesis of a chiral polymerizable dendrimer containing eight estergroups in the monomer unit is presented.
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  • 95
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    Angewandte Makromolekulare Chemie 223 (1994), S. 203-216 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Intramolecularly crosslinked poly(organosiloxane) particles are prepared by means of emulsion polycondensation or emulsion polymerization of alkoxysilanes or cyclic organic siloxanes. Starting from these intramolecularly crosslinked poly(organosiloxane) particles, graft copolymers are obtained by free-radical emulsion polymerization of unsaturated olefinic monomers (e.g. acrylates, styrene) in the presence of (functionalized) organosiloxanes. Intramolecularly crosslinked poly(siloxane) particles and their graft copolymers are characterized by means of light scattering (in dispersion), electron microscopy and thermal analyses (DSC, DMTA).
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  • 96
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    Angewandte Makromolekulare Chemie 214 (1994), S. 153-167 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Zusammenhang zwischen der Mischbarkeit und den physikalischen Eigenschaften von Polymerblends aus Poly(2,6-dimethyl-1,4-phenylenoxid) (PPO), die in unterschiedlichen Zusammensetzungen in einem Doppelschneckenextruder mit Polystyrol, schlagzähem Polystyrol oder Styrol-Butadien-Copolymeren hergestellt wurden, wird diskutiert. Die Verträglichkeit der Komponenten wurde mittels DSC und DMA, die Morphologie der Blends mittels SEM untersucht. Mit abnehmendem Polystyrolanteil wurde eine schlechtere Mischbarkeit bei den Blends beobachtet, deren Kerbschlagempfindlichkeit sich erhöhte. Die Untersuchungsergebnisse werden mit dem Micellmodell interpretiert.
    Notes: The relationship between the miscibility and the physical properties of polymer blends of poly(2,6-dimethyl-1,4-phenylene oxide) and polystyrene (PS), high-impact polystyrene (IPS) and poly(styrene-block-butadiene-block-styrene) (SBS), which are blended in different compositions by a twin-screw extruder is discussed. The three types of SBS that were used are SBS1, SBS2 and SBS3 having different styrene/butadiene ratios. Dynamic mechanical analysis and differential scanning calorimetry were used to study the miscibility. The morphology was examined by SEM. The miscibility of the blends decreases with decreasing PS content. The notch sensitivity is improved by blending. Finally, the micelle model was used to explain the testing phenomena.
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  • 97
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aliphatische Polyamide mit Poly(ethylenoxid)-Kettensegmenten unterschiedlicher Länge wurden durch Grenzflächenpolymerisation aus Succinylchlorid und Jeffamine ED-900 (O,O'-Bis(2-aminopropyl)poly(ethylenglykol) 800) bzw. Jeffamine ED-2001 (O,O'-Bis(2-aminopropyl)poly(ethylenglykol) 1900) zur Verwendung als Trägersubstanzen für Medikamente synthetisiert. Copolyamide mit kurzkettigen Diamin- und Jeffamine-Segmenten sowie Polyamide aus Cystin und Diamineinheiten wurden auf die gleiche Weise hergestellt. Die Polymerisationen wurden im zweiphasigen System Dichlormethan/Wasser bei Temperaturen um 0°C durchgeführt. Die Polymerprodukte wurden durch stufenweise Dialyse in wäßriger Phase bis zu einem Molekulargewicht von 25000 fraktioniert, nach Gefriertrocknung als wasserlösliche Harze oder Feststoffe erhalten und durch Mikroanalyse sowie 1H NMR-Spektroskopie charakterisiert. Die inhärenten Viskositäten liegen im Bereich von 10-20 ml/g. Die Eignung eines repräsentativen Zielmoleküls zur Bindung von Medikamenten wurde durch eine kovalente Verankerung einer als Medikamentmodell fungierenden Ferrocen-Verbindung untersucht. Dabei wurde ein wasserlösliches Polymer-Ferrocen-Konjugat erhalten.
    Notes: Aliphatic polyamides comprising poly(ethylene oxide) chain segments of various lengths, designed for use as drug carriers, are synthesized by interfacial polymerization of succinyl chloride with the two Jeffamine types ED-900 and ED-2001, formally described by the supplier as O,O'-bis(2-aminopropyl)poly(ethylene glycol) 800 and O,O'-bis(2-aminopropyl)poly(ethylene glycol) 1900. Copolyamides comprising both short-chain diamine and Jeffamine segments are similarly prepared, as are polyamides made up of cystine and diamine segments. The polymerizations are performed in a two-phase methylene chloride-water system at temperatures near or below 0°C. The product polymers, crudely fractionated by staged aqueous-phase dialysis at an ultimate molecular-mass cut-off of 25000, are collected after freeze-drying as water-soluble resins or solids and are characterized microanalytically and by 1H NMR spectroscopy. Inherent viscosities are in the range of 10-20 ml g-1. The drug-binding potential of a representative target polymer is probed by the covalent anchoring of a ferrocene compound used as a drug model, giving a water-soluble polymer-ferrocene conjugate.
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  • 98
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    Angewandte Makromolekulare Chemie 214 (1994), S. 211-216 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Über die Anwendung von Vinylesterharzen aus dem Diglycidylether von Bisphenol A sowie dessen Urethanderivat als Beschichtungsmaterial wird berichtet. Die mit den Harzen beschichteten Flußstahlplatten wurden auf Oberflächenglanz, Kratzfestigkeit und Chemikalienbeständigkeit untersucht. Harze mit Styrolanteil zeigen deutlich verbesserte Beschichtungseigenschaften.
    Notes: The present paper is concerned with the coating applications of a vinyl ester resin derived from diglycidyl ether of bisphenol-A and its urethane derivative. The mild steel panels coated with the synthesized resins were evaluated for their gloss on the surface, scratch hardness and chemical resistance. The incorporation of styrene in the resin systems improves the properties of coatings remarkably.
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  • 99
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das Katalysatorsystem Zirkonocendichlorid/Methylalumoxan wurde auf Siliciumdioxid aufgebracht, um Katalysatoren fur die Suspensions- order Gasphasenpolymerisation von Ethylen herzustellen. Die häochste Aktivitäat wurde für eine sandwichartige, dreilagige Verankerung von Zirkonzentren auf der Träageroberfläache gefunden. Dieneuen Katalysatorsysteme besitzen eine im Vergleich zu den entsprechenden homogenen Katalysatoren geringere Aktivitäat. Die Immobilisierung der aktiven Katalysatorzentren führt zu einer deutlichen Erhäohung der Polymermolmassen. Dabei bleibt die enge Molekulargewichtsverteilung der Polymerprodukte nahezu erhalten. Solche auf Träager aufgebrachte Metallocen-Katalysatoren käonnten für die Herstellung von Polyethylenen mit kontrollierter Rheologie Anwendung finden.
    Notes: The system zirconocene dichloride/methylalumoxane was supported on silica in order to provide ethylene polymerization catalysts for suspension or gas phase processes. Highest activity was found for a sandwich-like, three layer anchoring of the zirconium centers on the support surface. The new catalyst systems show a decrease of activity compared to polymerization experiments in homogeneous phase. However, the molecular weights are increased and the weight distributions remain narrow by immobilization of the active catalyst sites. Those supported metallocene catalysts could find application for the synthesis of polyethylene materials with controlled rheology.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 215 (1994), S. 129-138 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Vernetzte Copolmere aus Butylacrylat (BA) und Ethylenglycol-dimethacrylat (EGDMA) wurden auf ihre Eignung als stationäare Phase für die Chromatographie untersucht. Es wurde festgestellt, daß gering vernetzte Copolymere (〈 30 Gew.-% EGDMA) nicht poräos sind, wäahrend Matrices mit mehr als 40 Gew.-% EGDMA eine konstante Porositäat aufweisen. Eine Erhäohung des Vernetzergehaltes beeinflußt hauptsäachlich die Hydrophobie der Oberfläache. Zwei Meßmethoden für diese Eigenschaft werden diskutiert: Die Absorption von Alkylalkoholen und von Aminosäauren. Für letztere wurde aus der Steigung der Beziehung zwischen der Sälenkapazitäat und dem Hydrophobie-Parameter der Aminosäauren ein Matrix-Hydrophobie-Index berechnet und dieser mit den bekannten Energien der Wechselwirkung von Alkylalkohol—CH2 Gruppen mit der Polymermatrix verglichen. Die Vorteile der Verwendung des Hydrophobie-Indexes bei der Bewertung von polymeren Sorbentien werden aufgezeigt.
    Notes: Copolymers of butyl acrylate (BA) crosslinked with ethylene glycol dimethacrylate (EGDMA) were evaluated as potential chromatographic packings. It was found that slightly crosslinked copolymers (up to 30 wt.-% EGDMA) did not provide porous material, while for matrices which exceeded 40 wt.-% of EGDMA the porous structure remained unchangeable. The increase of crosslinker content mostly affected the surface hydrophobicity. Two methods of measurement of this property were discussed: Sorption of alkyl alcohols and amino acids. Taking the latter for testing, a polymer matrix hydrophobicity index was calculated as the slope of dependence of column capacity vs. amino acid hydrophobicity parameter. The indices were verified against well-established interaction energies of —CH2— groups of alkyl alcohols and polymer surfaces. Some benefits of the use of the hydrophobicity index in evaluation of polymer sorbents were demonstrated.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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