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  • 1
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    EDP SCIENCES
    Publikationsdatum: 2024-04-05
    Beschreibung: Chemistry
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Sprache: Französisch
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  • 2
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    EDP SCIENCES
    Publikationsdatum: 2024-04-05
    Beschreibung: Chemistry
    Schlagwort(e): 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
    Sprache: Französisch
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  • 3
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    EDP SCIENCES
    Publikationsdatum: 2024-04-07
    Beschreibung: Chemistry
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Sprache: Französisch
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  • 4
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    EDP SCIENCES
    Publikationsdatum: 2024-04-05
    Beschreibung: Chemistry
    Schlagwort(e): 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
    Sprache: Französisch
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  • 5
    Publikationsdatum: 2024-04-05
    Beschreibung: Chemistry
    Schlagwort(e): 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
    Sprache: Französisch
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  • 6
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    EDP SCIENCES
    Publikationsdatum: 2024-04-08
    Beschreibung: Chemistry
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Sprache: Französisch
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  • 7
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    EDP SCIENCES
    Publikationsdatum: 2024-04-05
    Beschreibung: Chemistry;Materials science
    Schlagwort(e): 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
    Sprache: Französisch
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  • 8
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    EDP SCIENCES
    Publikationsdatum: 2024-04-05
    Beschreibung: Chemistry
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Sprache: Französisch
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  • 9
    Publikationsdatum: 2024-03-05
    Beschreibung: Con sus 220 km2 la región geográfica de Bahía de Nipe es el mayor acuatorio en su tipo en Cuba, donde se encuentran representaciones de diversos ecosistemas a lo largo de sus costas. Los asentamientos humanos y sus múltiples actividades productivas de importancia y magnitud, le dan a esta bahía relevancia como recurso natural que sustenta usos estratégicos para el país.
    Beschreibung: Other
    Schlagwort(e): Contaminación ; Metales pesados ; Fuentes contaminantes ; Pesquerías ; Pollution ; Heavy metals ; Plaguicides ; Fisheries ; Plaguicidas ; Sources pollution
    Repository-Name: AquaDocs
    Materialart: Thesis/Dissertation
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2024-01-11
    Beschreibung: The 60–80s of the last century were the period of the most rapid development of commercial oceanology in the Azov and Black Sea Scientific Research Institute of Marine Fisheries and Oceanography (AzCherNIRO, further renamed YugNIRO). In addition to the monitoring of oceanographic processes, it was involved in the areas of general marine ecology, monitoring of marine pollution, and space oceanology. Oceanographic information is used in forecasting the state of aquatic ecosystems at various timescales and is crucial for fishing forecasts. In 1981, a satellite data reception center was established in AzCherNIRO. In the 80–90s, in YugNIRO, an optimal procedure was created for multidimensional predictive monitoring of the state of the Black Sea ecosystem. In September 1986, within the Laboratory of Commercial Oceanology of the Black Sea, a group for the conservation of marine ecosystems was created, which turned into a sector in January 1989, and into a separate laboratory in December 1996. Its reasearchers carried out multidisciplinary environmental studies, investigating the ecological status of the aquatic areas affected by the facilities of the marine industry during their operation, monitoring the level of soil contamination, and excercising the toxicological control of fish and fish products. YugNIRO oceanological studies conducted in the World Ocean from the early 1970s to the early 1990s made it possible to link the productivity and catches of exploitable species to the atmospheric circulation, changes in the climatic fields of currents, as well as to the geo- and heliophysical factors, which enabled the fishing predictions with a one-year lead time or more for the fishing areas of the Central, Southeastern and Southwestern Indian Ocean, the Patagonian Shelf, and the Indian Ocean sector of Antarctica. In the 70–90s and early 2000s, YugNIRO conducted marine geological studies facilitating fishing operations and environmental protection in the Gulf of Aden, on the bottom elevations of the tropical and subtropical parts of the Indian Ocean, in the Antarctic Shelf area, and in the Black and Azov Seas. This article lays down the current major goals and prospects of commercial oceanology.
    Beschreibung: 60–80-е годы прошедшего столетия были в АзЧерНИРО (ЮгНИРО) периодом наиболее активного развития промысловой океанологии. Кроме мониторинга океанографических процессов она начала внедряться в сферы общей экологии моря, мониторинга загрязнения моря, космической океанологии. Океанографическая информация используется при разработке прогнозов состояния водных экосистем различной заблаговременности и является неотъемлемой составляющей рыбопромысловых прогнозов. В 1981 г. в АзЧерНИРО был создан центр приема спутниковой информации. В 1980–1990-х гг. в ЮгНИРО была создана оптимальная для Черного моря схема комплексного прогностического мониторинга состояния его экосистемы. В сентябре 1986 г. в составе лаборатории промысловой океанологии Черного моря была создана группа, в январе 1989 г. — сектор, в декабре 1996 г. — лаборатория охраны морских экосистем. Сотрудниками лаборатории проводились комплексные экологические исследования состояния акваторий предприятий морехозяйственого комплекса в условиях их производственной деятельности, контроль уровня загрязненности почв, токсикологический контроль рыбы и рыбопродукции. Океанологические исследования ЮгНИРО, проводимые в Мировом океане с начала 1970-х до начала 1990-х гг., позволили получить систему связей урожайности и вылова промысловых объектов с особенностями атмосферной циркуляции, изменениями макромасштабных полей течений, гео- и гелиофизическими факторам для прогноза промысловых характеристик с заблаговременностью год и более в промысловых районах центральной, юго-восточной и юго-западной частей Индийского океана, в районе Патагонского шельфа, в индоокеанском секторе Антарктики. Выполнение морских геологических работ в рыбопромысловых и природоохранных целях проводилось ЮгНИРО в 1970–1990-х и в начале 2000-х гг. в Аденском заливе, на поднятиях тропической и субтропической частей Индийского океана, на шельфе Антарктиды, в Черном и Азовском морях. В статье формулируются основные современные цели и пути развития промысловой океанологии.
    Beschreibung: Published
    Beschreibung: Non Refereed
    Schlagwort(e): Commercial oceanography ; Marine geology ; Ecosystems ; Fisheries ; Промысловая океанография ; Морская геология ; Экосистемы ; АзЧерНИРО ; ЮгНИРО ; Промысловые прогнозы ; Океанографическая информация ; Океанологические исследования ; YugNIRO ; AzCherNIRO ; ASFA_2015::F::Fishery oceanography ; ASFA_2015::F::Forecasting ; ASFA_2015::F::Fishery institutions ; ASFA_2015::M::Monitoring
    Repository-Name: AquaDocs
    Materialart: Journal Contribution
    Format: pp.159-169
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  • 11
    Publikationsdatum: 2024-01-25
    Beschreibung: La producción de ostión en Cuba aumenta hacia el este, y los máximos de abundancia y captura se presentan en la zona costera cercana a la cuenca del río Cauto, en la región correspondiente al municipio Manzanillo, provincia de Granma. En esta región habitan el ostión de mangle antillano (Crassostrea rhizophorae Guilding, 1828), y el ostión americano (Crassostrea virginica Gmelin, 1791). Aunque la tendencia histórica ha sido al incremento, posterior a 2013 (853 t) la producción promedio anual disminuye a 307 t. El objetivo de esta investigación fue evaluar el estado actual del recurso ostión y su aprovechamiento industrial en la región del golfo de Guacanayabo, en relación a la situación ambiental de sus hábitats. Se realizó un diagnóstico de la pesquería de ostión y de la gestión ambiental de la pesca extractiva para determinar impactos ecosistémicos. Se identificaron como principales factores de impacto negativo, que inciden sobre las poblaciones de ostión y sus hábitats, el incumplimiento del periodo de veda, el manejo inadecuado de la pesca extractiva, y eventos de contaminación, que afectan los bienes y servicios ecosistémicos del manglar y reducen las poblaciones de ostión. Se propone la ostricultura artesanal como alternativa pesquera sostenible y se proyectó un plan de producción de ostión para 2023-2030. Se estimó que a calidad ambiental de la región donde se desarrollan las especies de interés es adecuada para su desarrollo.
    Beschreibung: Oyster production in Cuba increases to the east, and the maximum abundance and catch occur in the coastal zone near the Cauto river basin, in the region corresponding to the Manzanillo municipality, Granma province. The West Indian mangrove oyster (Crassostrea rhizophorae Guilding, 1828), and the American oyster (Crassostrea virginica Gmelin, 1791) inhabit this region. Although the historical trend has been to increase, after 2013 (853 t) the average annual production decreases to 307 t. The objective of this research was to evaluate the current state of the oyster resource and its industrial use in the region of the Guacanayabo Gulf, in relation to the environmental situation of its habitats. A diagnosis of the oyster fishery and the environmental management of extractive fishing was carried out to determine ecosystem impacts. The main factors of negative impact, which affect oyster populations and their habitats, were identified as non-compliance with the closed season, inadequate management of extractive fishing, and pollution events, which affect the goods and ecosystem services of the mangrove and reduce oyster populations. Artisanal oyster farming is proposed as a sustainable fishing alternative and an oyster production plan was projected for 2023-2030. It is estimated that the environmental quality of the region where the species of interest develop is adequate for their development.
    Beschreibung: Published
    Beschreibung: Refereed
    Schlagwort(e): Golfo de Guacanayabo ; Gestión ambiental ; Pesquería ; Ostricultura ; Gulf of Guacanayabo ; Environmental management ; Fisheries ; Ostrich farming
    Repository-Name: AquaDocs
    Materialart: Journal Contribution
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  • 12
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNV Chemistry of minerals, crystals and gems
    Sprache: Englisch
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  • 13
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Sprache: Englisch
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  • 14
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Sprache: Englisch
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  • 15
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Sprache: Englisch
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  • 16
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry
    Sprache: Englisch
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  • 17
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRH Electrochemistry and magnetochemistry
    Sprache: Englisch
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  • 18
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry
    Sprache: Englisch
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  • 19
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Sprache: Englisch
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  • 20
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNK Inorganic chemistry
    Sprache: Englisch
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  • 21
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Sprache: Englisch
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  • 22
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRL Nuclear chemistry, photochemistry and radiation
    Sprache: Englisch
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  • 23
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Sprache: Englisch
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  • 24
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): 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
    Sprache: Englisch
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  • 25
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Sprache: Englisch
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  • 26
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRH Electrochemistry and magnetochemistry
    Sprache: Englisch
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  • 27
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRC Colloid chemistry
    Sprache: Englisch
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  • 28
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Sprache: Englisch
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  • 29
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Sprache: Englisch
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  • 30
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Sprache: Englisch
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  • 31
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRX Surface chemistry and adsorption
    Sprache: Englisch
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  • 32
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Sprache: Englisch
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  • 33
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    IntechOpen | IntechOpen
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry::PNFS Spectrum analysis, spectrochemistry, mass spectrometry
    Sprache: Englisch
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  • 34
    Publikationsdatum: 2023-03-08
    Beschreibung: © 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.
    Beschreibung: 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.
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; Chemical engineering ; Catalysis
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 35
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): Science ; Chemistry ; Education ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::J Society and Social Sciences::JN Education
    Sprache: Deutsch
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  • 36
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    Logos Verlag Berlin | Logos Verlag Berlin
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): 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
    Sprache: Englisch
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  • 37
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    Logos Verlag Berlin | Logos Verlag Berlin
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): 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
    Sprache: Deutsch
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  • 38
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    Logos Verlag Berlin | Logos Verlag Berlin
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): 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
    Sprache: Deutsch
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  • 39
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    The MIT Press | The MIT Press
    Publikationsdatum: 2024-03-27
    Beschreibung: 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
    Schlagwort(e): 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
    Sprache: Englisch
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  • 40
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    Logos Verlag Berlin | Logos Verlag Berlin
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): 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
    Sprache: Englisch
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  • 41
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): 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
    Sprache: Deutsch
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  • 42
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    Taylor & Francis | CRC Press
    Publikationsdatum: 2024-03-31
    Beschreibung: 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.
    Schlagwort(e): 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
    Sprache: Englisch
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  • 43
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    Unbekannt
    Frontiers Media SA
    Publikationsdatum: 2024-04-04
    Beschreibung: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact
    Schlagwort(e): living marine resources ; Forecasting ; prediction ; fish ; Fisheries ; Seasonal to Decadal Prediction ; Climate services ; thema EDItEUR::P Mathematics and Science::PD Science: general issues ; thema EDItEUR::R Earth Sciences, Geography, Environment, Planning::RB Earth sciences::RBK Hydrology and the hydrosphere::RBKC Oceanography (seas and oceans)
    Sprache: Englisch
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  • 44
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    Unbekannt
    MDPI - Multidisciplinary Digital Publishing Institute
    Publikationsdatum: 2024-04-05
    Beschreibung: 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.
    Schlagwort(e): QD1-999 ; Toxicology ; Chemistry ; Biology ; Material Science ; Nanofibers ; Nanotechnology ; thema EDItEUR::P Mathematics and Science::PN Chemistry
    Sprache: Englisch
    Format: application/octet-stream
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  • 45
    Publikationsdatum: 2024-04-04
    Beschreibung: 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.
    Schlagwort(e): Chemistry ; Chemistry ; Fritz Haber Institute ; thema EDItEUR::P Mathematics and Science::PD Science: general issues::PDX History of science
    Sprache: Englisch
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  • 46
    facet.materialart.
    Unbekannt
    transcript Verlag | transcript Verlag
    Publikationsdatum: 2024-04-04
    Beschreibung: 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.
    Schlagwort(e): 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
    Sprache: Deutsch
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  • 47
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    Unbekannt
    De Gruyter | De Gruyter
    Publikationsdatum: 2024-04-11
    Beschreibung: 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.
    Schlagwort(e): 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
    Sprache: Englisch
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  • 48
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    De Gruyter | De Gruyter
    Publikationsdatum: 2024-04-05
    Beschreibung: 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
    Schlagwort(e): 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
    Sprache: Englisch
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  • 49
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    Unbekannt
    Springer Nature | Palgrave Macmillan
    Publikationsdatum: 2024-03-29
    Beschreibung: This open access book explores fishing livelihoods in the context of the wider contexts in which they are embedded. Drawing on case studies from across the Asia-Pacific region, the book highlights how fishing livelihoods are shaped by globalisation, social relationships and governance. The book concludes by showing how better understanding these relationships can contribute to governance for healthier ecosystems and social wellbeing. This is an open access book. This is an open access book.
    Schlagwort(e): Fisheries ; marine social science ; fishing livelihoods in the Asia-Pacific ; sustainable fishing ; environmental sustainability ; food security ; coastal conservation ; fish stocks ; fisheries governance ; Fishing livelihoods and social diversity ; Fishing livelihoods and wellbeing ; Open Access ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPQ Central / national / federal government::JPQB Central / national / federal government policies ; thema EDItEUR::J Society and Social Sciences::JH Sociology and anthropology::JHB Sociology ; thema EDItEUR::R Earth Sciences, Geography, Environment, Planning::RN The environment ; thema EDItEUR::R Earth Sciences, Geography, Environment, Planning::RG Geography::RGB Physical geography and topography ; thema EDItEUR::R Earth Sciences, Geography, Environment, Planning::RN The environment::RNF Environmental management ; thema EDItEUR::R Earth Sciences, Geography, Environment, Planning::RG Geography::RGC Human geography
    Sprache: Englisch
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  • 50
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    Unbekannt
    Coimbra University Press
    Publikationsdatum: 2022-01-31
    Beschreibung: 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.
    Schlagwort(e): Geography ; Chemistry ; Literature ; Geology ; Light ; Optics ; Biology ; History ; Physics
    Sprache: Portugiesisch
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  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Aquatic sciences 51 (1989), S. 108-128 
    ISSN: 1420-9055
    Schlagwort(e): Chemistry ; mountain lakes ; silica ; acidity ; sediment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Alpine lakes in siliceous catchments of Tyrol and Carinthia (Austria) show signs of acidification. About 9% of the studied lakes have no alkalinity, more than 20% are below pH 6. About two thirds of all lakes have acid neutralizing capacities below 100 μeq 1−1. In spite of moderate precipitation acidity, some lakes show considerable concentrations of dissolved reactive aluminum during or shortly after snowmelt. High altitude lakes of the Alps are definitely more acidic than high mountain lakes in remote areas. Large differences in water and soil chemistry of nearby situated lakes were attributed to heterogeneities of bedrock geology. Paleolimnological investigations on former pH values of five lakes, based on diatom assemblages in the sediment, showed different developments: recent and past acidification, stable conditions, and alkalinization.
    Materialart: Digitale Medien
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  • 52
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: In this part properties and efficiency of the developed model1,2 are discussed. A variation of the parameters shows that vigorous effects are caused by the effective aggregation. All calculations show that at low conversion there are little temporal steps between the sequential aggregation steps. In the range of 5% to 20% conversion the velocity of aggregation decreases and the aggregative stability agrees with experiences given in the literature. It is shown that the calculated results are in agreement with the experimental results and therefore the presented model is a suitable possibility to describe the formation of some PVC-morphology properties.
    Notizen: In der vorliegenden Arbeit werden die Eigenschaften des früher1,2 entwickelten Modells untersucht und diskutiert. Die Variation der Modellparameter zeigt einen großen Einfluß der Aggregationsprozesse auf die Subkornmorphologie. Bei niedrigen Monomerumsätzen ist das Zeitintervall zwischen zwei aufeinanderfolgenden Aggregationsschritten sehr klein, so daß für das Teilchenwachstum die Geschwindigkeit der Aggregation der Unterstrukturen entscheidend ist. Im Bereich zwischen 5% und 20% Monomerumsatz sinkt die Aggregationsgeschwindigkeit sehr stark, so daß für das Teilchenwachstum zunehmend die Polymerisationsreaktion an Bedeutung gewinnt. Aggregative Stabilität wird nach dem Modell für einen Teilchengrößenbereich erhalten, der sich in Übereinstimmung mit experimentellen Daten aus der Fachliteratur befindet. Die berechneten Teilchengrößen entsprechen ebenfalls den in der Literatur publizierten experimentellen Werten, so daß das Modell eine gute Grundlage für die Beschreibung einiger morphologisch bestimmter Polymereigenschaften bildet.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 53
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 165 (1989), S. 21-34 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Es wurden unidirektionale Verbundwerkstoffe aus Novolakharz mit Kohlenstoff-Fasern gemäß der Prepreg-Methode verarbeitet. Das Novolakharz wurde durch Polymerisation von Phenol mit Formaldehyd (Mol-Verhältnis 1 : 0,82) und Oxalsäure als Katalysator (1,5 Gew.-% von Phenol) hergestellt. Die Härtung des Novolakharzes wurde mit Hexamethylentetramin (Hexa) durchgeführt, während das geeignete Verhältnis durch die IR-Spektroskopie bestimmt wurde.Es wurden Proben aus Novolak/Hexa (Gew.-Verhältnis 14: 1), verstärkt mit kommerziellen Kohlenstoff-Fasern, unter verschiedenen Bedingungen (z. B. verschiedene thermische Programme und verschiedene Verhältnisse von Novolakharz : Kohlenstoff-Fasern) hergestellt. Die mechanischen Eigenschaften der hergestellten Proben (wie Biegefestigkeit, Zugfestigkeit, usw.) wurden bestimmt, und ihre Struktur wurde mit Hilfe der Elektronenmikroskopie untersucht.Mit zunehmendem Volumenverhältnis der Kohlenstoff-Fasern werden nicht nur alle mechanischen Eigenschaften des verstärkten Materials verbessert, sondern auch sein Nutzungsgrad nimmt zu, und die Herstellungsbedingungen üben einen größeren Einfluß aus. Die mit dem gleichen Verhältnis von Kohlenstoff-Fasern (z. B. 15 Vol.-%) hergestellten Proben weisen mit zunehmendem Härtungsgrad des Novolaks verbesserte mechanische Eigenschaften auf. Der Häirtungsgrad des Novolaks während der Anfangsphase (Gel-Zeit) als auch während der Endphase (Nachhärtung) kann mit Hilfe der IR-Spektren des härtenden Novolaks verfolgt werden, während der Härtungsgrad der Zwischenphase nur indirekt aus den Werten der mechanischen Eigenschaften der entsprechenden Proben bestimmt werden kann.Aus der Korrelation zwischen den Herstellungsparametern und den mechanischen Eigenschaften der Proben ergeben sich optimale Bedingungen für die Verarbeitung in der Wärmepresse zur Herstellung von mit Kohlenstoff-Fasern verstärkten Novolakharzen (1. Phase: T1 = 125-145°C, t1 = 20 min - 1 h, ohne Druck; 2. Phase: T2 = 180-195°C, t2 = 40 min, P2 ≃ 1,5 kN /cm2).
    Notizen: Unidirectional composite materials of novolac resin with carbon fibers were fabricated according to the prepreg method. Novolac resin was prepared by polymerization of phenol with formaldehyde (mole ratio 1 : 0.82) in the presence of oxalic acid as catalyst (1.5 wt.-% to phenol). The curing of novolac resin was performed with hexamethylenetetramine (hexa), while the appropriate proportion was determined by using the IR-spectroscopy.Specimens of novolac/hexa (weight ratio 14:1) reinforced with carbon fibers commercially available were fabricated under different conditions (e.g. different thermal programs and different proportions of novolac/carbon fibers). The mechanical properties of the fabricated specimens (like flexural strength, tensile strength, etc.) were determined and their structure was examined by scanning electron microscopy.By increasing the volume proportion of carbon fibers, not only all mechanical properties of the composite material were increased, but also their degree of utilization was increased and also the production conditions had greater influence. Concerning the specimens produced by the same proportion of carbon fibers (e.g. 15 vol.-%) their mechanical properties were improved by increasing the curing of novolac. The degree of curing of novolac during the initial phase (gel time) and during the ultimate phase (post-curing) can be followed with the aid of IR-spectra of the cured resin, while the degree of curing for the intermediate phase can be obtained only indirectly from the values of the mechanical properties of the corresponding specimens.From the correlation between the production parameters and the mechanical properties of the samples the optimal conditions for processing of the thermopress for the manufacture of carbon fiber reinforced novolac were concluded (1. phase: T1 = 125-145°C, t1 = 20 min - 1 h, without pressure; 2. phase: T2 = 180-195°C, t2 = 40 min, P2 ≃ 1,5 kN/cm2).
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 54
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 165 (1989), S. 69-78 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: In dieser Arbeit interessieren wir uns für den Einfluß von Konzentration und Temperatur auf den elektrischen Widerstand eines Butyl-Kautschuks (IIR), der mit zwei Typen von Ruß (Hoch-Abrasion-Schmelzofen-Ruß (HAF) und Schnell-Extrusion-Hochofen-Ruß (FEF)) versetzt ist. Ergebnis war, daß die Leitfähigkeit bei niedrigem Rußgehalt hauptsächlich durch thermische Aktivierung der Ladungsträger erreicht wird. Bei mittleren Konzentrationen überwiegt der Tunnel-Mechanismus bei niedriger Temperatur, gefolgt von der thermischen Aktivierung bei relativ hoher Temperatur. Dies gilt für beide Rußarten. Das metallartige Verhalten bei Gemischen mit hoher Rußkonzentration kann sowohl der thermischen Ausdehnung der Tunnelwege zwischen Kohlenstoff-Agglomeraten als auch dem Zusammenbruch der Kohlenstoff-Agglomerate bei steigender Temperatur zugeschrieben werden.
    Notizen: In this study we are interested in the effect of concentration and temperature on the electrical resistivity of butyl rubber (IIR) loaded with two types of carbon black, (namely, high abrasion furnace black (HAF), and fast extrusion furnace black (FEF)). It was found that the conductivity at low carbon black concentrations is mainly achieved by thermal activation of carriers. Tunneling mechanism at low termperature followed by thermal activation at relatively high temperature is found to be predominant for moderate concentrations for both carbon blacks. The metal-like behaviour which was observed in highly loaded compounds was attributed to both, the thermal expansion of the tunneling paths between carbon-carbon agglomerates and the breakdown of carbon agglomerates with temperature.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 55
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 165 (1989), S. 79-87 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die Arbeit beschreibt die Synthese von Halogenderivaten des Phenylglycidylethers und die Möglichkeiten der Verwendung von diesen Komponenten als Flammverzögerer und reaktive Verdünnungsmittel für Epoxidharze.Mit Hilfe der Nelder-Mead-Simplexmethode wurden die besten Reaktionsbedingungen gefunden. Die so hergestellten Produkte zeichnen sich durch eine hohe Qualität aus und wurden mit einem niedermolekularen Epoxidharz gemischt und mit Diaminodiphenylmethan gehärtet.Die Viskosität von Harzgemischen und die Brennbarkeit der gehärteten Systeme wurden untersucht. Mit dem erhöhten Gehalt an Halogen (Chlor oder Brom) steigt die Viskosität, und die Brennbarkeit der Epoxide wird reduziert.
    Notizen: This study deals with the synthesis of halogenated derivatives of phenyl glycidyl ether and with possibilities of their use as flame retardants and reactive diluents of epoxy resin.The best reaction conditions optimized by Nelder-Mead simplex method were found. The products of very high quality were prepared. They were mixed with a lowmolecular epoxy resin and cured by diamino diphenyl methane.The viscosity of the resin mixtures and limiting oxygen index of cured systems were determined. It was found that a higher content of halogen, both chlorine and bromine, causes increasing viscosity and reduced flammability of the epoxides.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 56
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 165 (1989), S. 89-95 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Durch Messungen von Tg, Tm und Tc (Trübungspunkt) wurden Phasendiagramme der vier verträglichen Polymermischungen von chlorierten isotaktischen Polypropylenen (Chlorgehalt 39,2 (CPP-40) und 49,8 Gew.-% (CPP-50)) mit Poly(ethylen-co-vinylacetat)en (Vinylacetatgehalt 40 (EVA-40) und 45 Gew.-% (EVA-45)) untersucht. Von den vier Mischungspaaren war die Mischung von CPP-50 mit EVA-40 am besten verträglich.
    Notizen: By measuring Tg, Tm and Tc (cloud point) phase diagrams for the four miscible blends of chlorinated isotactic polypropylenes (chlorine content 39.2 (CPP-40) and 49.8 wt.-% (CP-50)) with Poly(ethylene-co-vinyl acetate)s (vinyl acetate contents 40 (EVA-40) and 45 wt.-% (EVA-45)) were investigated. The blend of CPP-50 with EVA-40 was the most compatible of the four blend pairs.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 57
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die Synthese und Charakterisierung von Kationenaustauschmembranen aus PE-PS-DVB-Interpolymeren für die Elektrolyse von Borax-Lösung zur Erzeugung von Borsäure und Natronlauge wurden durchgeführt und mit den Eigenschaften von im Handel erhältlichen Membranen („Nafion 324“ und „Permaplex C-20“) verglichen.
    Notizen: The synthesis and the characterization of the PE-PS-DVB interpolymer cationexchange membranes in the electrolysis of borax solutions to produce boric acid and sodium hydroxide simultaneously was carried out. The characterization of the teflon based “Nafion 324” and polystyrene-DVB based “Permaplex C-20” membranes was also performed in the same system for comparison.The DVB contents were varied between 3 - 12% (by wt. in total monomers) and the increase of the cross-links resulted in the decrease of the water contents and ionexchange capacities of the membranes. The PE present in the membrane acted as a barrier for electroosmotic water transport. The membranes with high DVB contents showed better electrolysis performance due to their low water contents and low electroosmotic water transport properties. The use of the interpolymer membrane containing 11.6% DVB resulted in high current efficiency and high sodium cation dynamic transport number and worked satisfactorily at the process conditions of borax electrolysis.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 58
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 165 (1989), S. 125-131 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Aus Rizinusöl und difunktionellen Säuren, wie Oxal-, Malon-, Bernstein-, Glutar-, Adipin-, Suberin- und Sebacinsäure, wurden Prepolyester hergestellt. Diese Prepolyester (PPE) wurden anschließend mit Methylmethacrylat und 1% Ethylenglykoldimethacrylat als Vernetzer interpenetriert. Die Polymerisation wurde radikalisch mit Benzoylperoxid gestartet. Die neuen PPE/Polymethylmethacrylat (PMMA)-interpenetrierenden Netzwerke wurden als Pulver erhalten. Sie wurden durch ihr Löseverhalten, IR-Spektroskopie und ihr thermisches Verhalten charakterisiert.
    Notizen: Prepolyesters were obtained from castor oil and dibasic acids, viz oxalic, malonic, succinic, glutaric, adipic, suberic and sebacic acid. These prepolyesters (PPE) were subsequently interpenetrated with methyl methacrylate containing 1% ethylene glycol dimethacrylate as crosslinker by radical polymerization initiated with benzoyl peroxide. The novel PPE poly(methyl methacrylate) PPE/PMMA interpenetrating polymer networks (IPNs) were obtained as powder. They were characterized by solubility behaviour, IR spectral study and thermal behaviour.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 59
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: 2,4-Ionen, ein polymeres quartäres Ammoniumsalz, wurde auf einem makroporösen chlormethylierten Poly(Styrol-co-Divinylbenzol)-Harz (XAD-2) immobilisiert. Der Ionen-Gehalt des Harzes, der durch CHN-Elementaranalyse bestimmt wurde, betrug 50,2 g/kg Harz. Der wichtigste Nebeneffekt des modifizierten Harzes, das Ausbluten des Katalysators 2,4-Ionen, kann durch eine spektrophotometrische Methode, die extrem geringe Konzentraionen an freiem Ionen an der Oberfläche des Harzes messen kann, ermittelt werden.Die Aktivität der immobilisierten 2,4-Ionen/Kobalt(II)-phthalocyanin-tetranatriumsulfonat-Komplexe in bezug auf die oxidative Kupplung von Thiolen ist viel niedriger als im homogenen Fall, aber noch beträchtlich höher als im polymerfreien System. Die beobachtete Abnahme der Reaktionsgeschwindigkeit resultiert nicht aus Behinderungen des Massentransports, sondern vorzugsweise aus den Katalysatoreigenschaften wie z. B. einem sehr niedrigen N+/Co-VerhtUtnis. Die aktiven Zentren scheinen nur in der äußeren Hiille der Harzpartikel vorhanden zu sein.
    Notizen: A poly(quaternary ammonium) salt, 2,4-ionene, has been immobilized on a macroporous chloromethylated poly(styrene-divinylbenzene) resin (XAD-2). The ionene content of the resin, determined by CHN elemental analysis, was 50.2 g/kg resin. The most important side effect of the modified resin, catalyst (2,4-ionene) bleeding, can be detected by a spectrophotometric method capable of determining extremely low concentrations of free ionene in the supernatant of the resin.The activity of these immobilized 2,4-ionene/cobalt(II)phthalocyanine-tetrasodiumsulfonate (CoTSPc) complexes towards the oxidative coupling of thiols is much lower than in the homogeneous case, but still considerably higher than for the polymer free system. The observed decrease in reaction rate does not originate from the considerable mass transfer resistances but predominantly from catalyst properties like a very low local N+/Co ratio. The active sites appear to be present in the outer shell of the resin particles only.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 60
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 173 (1989), S. 163-181 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Röntgendiffraktometrische Untersuchungen und DSC-Messungen an Blend-Filmen, die aus Lösungen von PEEK und PES hergestellt wurden, zeigen eine Phasenseparation bei den Filmen, die bei 340°C hergestellt wurden. Das Kristallisationsverhalten von Filmen, die bei 340°C hergestellt, anschließend abgeschreckt und bei 180°C getempert wurden, ist identisch mit dem von PEEK. Filme, die bei 300°C hergestellt wurden, kristallisierten erst durch Tempern bei 250°C. Blockcopolymere, die aus Oligomeren von PEEK und PES erhalten wurden, unterscheiden sich in dieser Hinsicht von Blends der gleichen Zusammensetzung. Die Glastemperatur von Copolymeren mit einem PEEK-Gehalt von mehr als 50% liegt höher als die von PEEK selbst, während der Schmelzpunkt dieser Copolymeren niedriger als der von PEEK ist.
    Notizen: Polymer blends of PEEK with PES were prepared by the solution blending method. Copolymers composed of PEEK and PES components were synthesized from these oligomers. The formation conditions exerted an influence over the molecular aggregation and the crystallization behaviors of the blend films and block copolymers which were examined by X-ray diffractometry and DSC analysis. As a result, phase-separation in the blend films was found when the formation temperature was high. The blend films formed at 340°C, quenched and annealed at 180°C, exhibited the same crystallization behavior as those of PEEK. In the case of the blend films formed at 300°C, the annealing of the films at 250°C was required to crystallize the blend films. The Tg of a copolymer with a PEEK component content of more than 50% tends to shift toward a higher temperature than the Tg of PEEK itself, and the Tm of the copolymer toward a lower temperature than that of PEEK ist.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 61
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 168 (1989), S. 129-134 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Das Reaktionsprodukt eines Cyclohexanon-Formaldehyd-Harzes mit dem Säurechlorid des Radikalinitiators 4,4′-Azo-bis(4-cyanopentansäure) wurde als Initiator für die Styrolpolymerisation eingesetzt, um ein Cyclohexanon-Formaldehyd-Harz/Polystyrol-Copolymeres zu bilden. Das Copolymere zeigte ähnliche Löslichkeit wie Polystyrol.
    Notizen: The reaction product of cyclohexanone-formaldehyde resin with an acid chloride of a radical initiator, 4,4′-azo-bis(4-cyano pentanoic acid) was used as initiator for styrene polymerization to form a cyclohexanone-formaldehyde resin/polystyrene copolymer. The copolymer showed similar solubility as polystyrene.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 62
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 168 (1989), S. 145-155 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Entgegengesetzte Ladungen wurden durch tertiäre Amin- und Carboxylgruppen in Polyurethan (PU) und Polystyrol (PS) eingeführt, um durch gemeinsame Massepolymerisation ein interpenetrierendes PU/PS Polymernetzwerk (IPN) zu erhalten. Vier IPNs wurden hergestellt: ein Voll-IPN, zwei Semi-IPNs und ein lineares Blend. Die Wirkung der geladenen Gruppen auf die mechanischen Eigenschaften und die Morphologie der vier Polymermischungen wurde untersucht.Es wurde gefunden, daß PU/PS IPNs mit geladenen Gruppen keine Phasenseparation und somit homogene Verteilung aufweisen, was durch elektronenmikroskopische (SEM) Aufnahmen nachgewiesen wurde. Dynamisch-mechanische Messungen zeigen, daß die Übergangspeaks des Verlust-Moduls E″ in die Mitte zwischen den beiden Übergangspeaks der beiden Komponenten ohne geladene Gruppen liegen. Dies ist von der Zunahme des Gehaltes an geladenen Gruppen abhängig. Gleichzeitig nimmt der Speichermodul E′ in einer Stufe ab, was im Gegensatz zu der zweistufigen Abnahme bei Proben ohne Ladungsträger steht.Die Zugfestigkeit nimmt in allen vier Polymermischungen mit der Zunahme an Acrylsäure (AA) in Poly(Styrol-Acrylsäue) PSAA zu, was in dem PU/PSAA Voll-IPN besonders deutlich wird.
    Notizen: Opposite charges, namely tertiary amine and carboxyl groups, were introduced into polyurethane (PU) and polystyrene (PS), respectively, to prepare PU/PS interpenetrating polymer networks (IPNs) by means of simultaneous bulk polymerization. Four IPNs were synthesized: a full-IPN, two semi-IPNs and a linear blend. The effect of charge groups on the mechanical properties and morphology of the four polymer alloys was investigated.It is found that the PU/PS IPN which was incorporated with charge groups is free of any phase-separation, and sufficiently uniformly distributed, as can be seen from the corresponding scanning electron microscopy (SEM) photographs. Dynamic mechanical analysis indicates that the transition peak of the loss modulus E″ will move towards the centre between the two transition peaks of both components in the absence of charge groups, as a function of an increase in the contents of the opposite charge groups. Meanwhile the storage modulus E′ will decrease in a single-stage way from the previous two-stage mode.The tensile strength in all the four polymer alloys increased markedly along with an increase in the contents of acrylic acid (AA) in the poly(styrene-acrylic acid) (PSAA), which clearly can be seen for the PU/PSAA full-IPN.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 63
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 168 (1989), S. 157-168 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Pyrolysis behaviour and coke characteristics of different precursors for carbon processing: thermosetting resins (resol, novolak), hydrolytic lignin, pitch, tar as well as their blends were studied using differential thermal analysis (DTA) and X-ray diffraction techniques. The blends novolak-pitch, resol-tar and resol-hydrolytic lignin show a higher coke yield after carbonisation up to 1000°C compared to the corresponding individual substances. A good correlation between the integral procedural decomposition temperature T*A of the investigated precursors and their coke yield is found.
    Notizen: Mittels Thermo- und Röntgenstrukturanalyse wird eine vergleichende Untersuchung des Pyrolysevorganges und der Mikrostruktur des aus zwei Gruppen organischer Bindemittel und deren Mischungen gewonnenen Koksrückstandes durchgeführt. Gruppe I umfaßt reine und mit Hydrolyselignin gefüllte Resol- und Novolak-Phenol-Formaldehydharze und Gruppe II Steinkohlenpech und -teer. Es wird festgestellt, daß sich die Mischungen Novolakharz-Pech, Resolharz-Teer und Resolharz-Hydrolyselignin beim Erhitzen nicht wie mechanische Gemische verhalten und eine erhöhte Ausbeute an Koksrückstand liefern. Weiterhin wird gefunden, daß die integrale Endtemperatur der Pyrolyse (T*A) dieser Substanzen als quantitatives Maß für die Ausbeute an Koksrückstand im Anschluß an die Carbonisierung der Proben dienen kann.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 64
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 168 (1989), S. 217-223 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The paper describes the successful synthesis of silicon containing bismaleimide resin 4,4′-carbo(4,4′-bismaleimido phenoxy)diphenyl silane. The char yield of the bismaleimide resin in N2 atmosphere was found to be 55% at 800°C. Chain extension of bismaleimide with 4,4′-diamino diphenyl sulfone reduced the char yield and thermal stability.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 65
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: As hard blocks in polyether block amides, polyamides are used whose length is intensively regulated by dicarboxylic acids. Since, with regard to melting and crystallization behaviour, this acid constitutes an interfering structural unit in the chain, and in the case of a completely converted product each chain contains one acid molecule, it is essential to know where in the chain incorporation will occur. As opposed to monofunctional chain regulators which always form a chain end, a bifunctional chain regulator can a priori also be randomly incorporated into the inner part of the chain. This leads to a far greater interference than occurs if the chain regulator molecule and the chain end, which acts as an interfering unit in any case, coincide with each other.By means of adipic acid-regulated oligoamides based on lauryl lactam, the incorporation of the chain regulator was examined by NMR spectroscopy and compared with model calculations. This resulted in a close match only if it was presupposed that the incorporation was carried out randomly with the same degree of probability at any point whatsoever between two lauryl lactam structural units or at the chain end.Further calculations illustrate the effects of the incorporation of the chain regulator on the size of the amorphous portion.
    Notizen: Als Hartblöcke in Polyetherblockamiden werden durch Dicarbonsäuren stark geregelte Polyamide eingesetzt. Da die Säure in Hinblick auf das Schmelz- und Kristallisationsverhalten einen Störbaustein in der Kette darstellt und bei einem ausgeregelten Produkt jede Kette ein Säuremolekül enthält, ist es von Bedeutung zu wissen, wo in der Kette der Einbau erfolgt. Anders als bei monofunktionellen Reglern, wo der Regler stets ein Kettenende bildet, kann ein bifunktioneller Regler a priori auch statistisch im Inneren der Kette eingebaut werden. Dies führt zu einer viel stärkeren Störung, als wenn das Reglermolekül und das sowieso als Störstelle wirkende Kettenende zusammenfallen. Anhand adipinsäuregeregelter Oligoamide auf Basis von Laurinlactam wird kernresonanzspektroskopisch der Einbau des Reglers untersucht und mit Rechnungen verglichen. Es ergibt sich nur dann gute Übereinstimmung, wenn vorausgesetzt wird, daß der Einbau statistisch erfolgt und dabei mit gleicher Wahrscheinlichkeit für jede beliebige Stelle zwischen zwei Laurinlactambausteinen oder am Kettenende abläuft. Weitere Rechnungen verdeutlichen den Einfluß des Reglereinbaus auf die Größe des amorphen Anteils.
    Zusätzliches Material: 6 Tab.
    Materialart: Digitale Medien
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  • 66
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Auf Grund von mikroskopischen Beobachtungen wurde festgestellt, daß unter dem Einfluß von UV-Strahlung die Oberfläche von PVC-Filmen einer Formveränderung unterliegt. Auf der Oberfläche erscheinen Bläschen und Löcher. Die sich absondernden Gasprodukte der Polymerfotodestruktion verursachen die Bildung dieser Bläschen und Löcher. Größere Oberflächenänderungen wurden in Filmen mit einem Zusatz von 1-5% eines MMA/MA-Copolymeren beobachtet. Das weist auf eine in diesem Modifikator stattfindende Photoabbaureaktion hin, deren Ergiebigkeit größer ist als in reinem PVC. Dieser Modifikator wird in PVC eingeführt, um die Filmoberfläche zu verbessern, beschleunigt allerdings ihre Zerstörung unter dem Einfluß von UV-Strahlung. Es wurde festgestellt, daß Cyclohexanonspuren in den Proben den Photoabbau von MMA/MA retardieren, diesen Prozeß in PVC aber beschleunigen.
    Notizen: By means of microscopic observation, the deformation of the surface of PVC films caused by 253.7 nm UV radiation was investigated. Numerous blisters and holes were formed by the gaseous photodecomposition products of the polymer.More apparent deformation of the films containing MMA/MA suggests that the photodecomposition of this modifier occurs with higher efficiency than that of PVC.MMA/MA copolymer is introduced into PVC films to improve the smoothness of their surface, but this modifier accelerates the deformation of this surface under UV irradiation. It was also found that traces of cyclohexanone in samples retard the photodecomposition of MMA/MA and accelerate this process in PVC.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 67
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 170 (1989), S. 29-41 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Eine Anzahl von Harzen wurde durch gemeinsame Kondensation von p-Aminoacetophenon (p-AAph), substituierten Benzoesäuren wie m-Tolylsäure (m-TA), o-Tolylsäure (o-TA), Phthalsäure (PhA), p-Nitrobenzoesäure (p-NBA), p-Chlorbenzoesäure (p-CIBA) und Formaldehyd (F) in Gegenwart von verschiedenen Säuren und Basen als Katalysatoren hergestellt. Die Harze wurden IR-spektroskopisch charakterisiert. Die Löslichkeitsparameter wurden gemäß Small's Gruppenbeteiligung berechnet; sie stimmen gut mit den experimentellen Werten überein. Das thermische Verhalten und die bakteriologischen Eigenschaften der Harze wurden auch untersucht.
    Notizen: A number of resins has been prepared by condensing p-amino-acetophenone (p-AAph) with substituted benzoic acid such as m-toluic acid (m-TA), o-toluic acid (o-TA), phthalic acid (PhA), p-nitrobenzoic acid (p-NBA), p-chlorobenzoic acid (p-CIBA) and formaldehyde (F) in presence of some acids and bases as catalysts. The resins were characterized by infrared spectra of the characteristic groups. The solubility parameters were calculated from Small's group contribution which agreed well with the experimental values. The thermal behaviour and the bacteriological properties of the resins have also been investigated.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 68
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Notwithstanding their more common beginnings, liquid crystals and molecular biology developed mainly parallel and independently during the last one hundred years.Molecule-phase relationships on the one and complex static-dynamic treatments on the other hand seem to forward mutually integrative views in our days.Biomesogen approaches will deepen our insights into the spatio-temporal coherences of biological systems. They might contribute significantly to the understanding of life processes.
    Zusätzliches Material: 23 Ill.
    Materialart: Digitale Medien
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  • 69
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Recent studies on ionic distribution in solutions and in suspensions were reviewed. Suspensions of latex particles, which were large enough to be seen under an ultramicroscope, were investigated by the 2-D Fourier transformation. The micrograph showing ordered structures gave discrete scattering spots, whereas those of disordered arrangements displayed no spots or halos. The two-state structure gave a limited number of halo, confirming our previous conclusion that the very frequently observed single, broad scattering peak was reminiscent of some kind of ordering of solute species. By using an image data analyser, the crystallization process was shown to follow the Ostwald ripening mechanism. The concurrent study by the quasi elastic light scattering method and by the Fourier analysis gave consistent scattering profiles, which indicated that the ordering phenomena took place in the entire volume of suspensions. The scattering intensity (correctly the lattice factor) was calculated for cubic systems with paracrystalline distortion. The peak intensity was lowered by enhanced distortion, while the peak position itself was not affected. This justifies our previous treatment of the single, broad peak in terms of the Bragg equation. The experimentally found scattering curve was compared with this theoretical calculation; the degree of distortion was evaluated.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 70
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Lyotropic liquid crystalline phases of cellulose derivatives were explored as an analytical tool. Molar mass dependent measurements of the helicoidal cholesteric pitch of a cellulose tricarbanilate/solvent system may be used to determine the molar mass of this derivative by optical means. The compatibility of a ternary liquid crystalline system can be adequately investigated by a study of the supermolecular structure with spectroscopic measurements.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 71
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The application of carotenoids as natural additives in various water-based or water-compatible formulations for the pigmentation of foods and feeds is seriously hampered by their insolubility in aqueous systems.Therefore, in order to develop the full potential of colour strength and to achieve a high degree of bioavailability during gastro intestinal passage, the coarse crystalline material has to be transformed into a microdisperse state.Exemplified with β-carotene, a novel non-mechanical process is described that transforms the carotenoids into a colloidal hydrosol characterized by an average particle size of about 0.1 μm.The process is based on the preparation of a transient high temperature solute state of the carotenoid in a water-miscible solvent, coupled with succeeding rapid aqueous precipitation in the presence of a stabilizing polymer colloid. The obtained hydrosols are characterized by photon-correlation-spectroscopy(size), and microelectrophoresis(colloidal stabilization).The bioavailability was tested by monitoring plasma levels of β-carotene in veal calves.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 72
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Polymer science is mature enough to allow one to think about tailor-making macromolecular compounds aimed at interacting purposely with living systems. Reasons for developing bioresorbable polymers for temporary therapeutic applications are discussed with respect to property adjustments and economical factors. The field of the applications is first described and guidelines for tailor-making multimeric macromolecules with desired properties are presented. The approach led to focuss investigations on poly(α-hydroxy acids) and functional poly(β-hydroxy acids) derived from natural hydroxy acids, namely lactic, glycolic and malic acids. Physical, mechanical and biological properties of some corresponding polymers and copolymers are presented. Last but not least, examples of applications currently investigated are recalled.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 73
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: When blood comes into contact with an artificial surface, a number of events occur which include protein adsorption, platelet activation and the activation of the intrinsic pathway of blood coagulation. With the increased application of blood containing artificial devices, there is a great demand to develop new biomaterials which retard thrombus formation. Our new approach to solving this problem is to mimic the non-thrombogenic surface of natural biological membranes at least in a simple form. We have developed a polymerisable phospholipid and polyesters based on the major phospholipid polar head group present on the erythrocyte outer membrane surface. The coagulation of blood exposed to these polymers was examined by the technique of Material Thrombelastography, a relatively simple test for the in vitro screening of polymer thrombogenicity. We present results which indicate that the polymerised phospholipid and polyesters show reduced thrombogenicity, and may therefore have potential for future biomaterials.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 74
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: After implantation a stable bond between the implant and the surrounding tissue is required. Therefore a high cell adhesion of the polymer surface of the implant must be achieved. Depending on the treatment time of a polydimethylsiloxane foil with oxygen plasma, the cell adhesion can be improved. FT-IR spectroscopy and ESCA analysis were used to characterize the surface modification. The cell spreading and cell adhesion increase with increasing hydrophilic character of the polymer surface after plasma treatment. A pronounced correlation was found between the efficiency of DNA and protein content, characterizing cell growth, and the spreading of the cells.Polydimethylsiloxane, Glow-Discharge, Surface Modification, Cell Adhesion, Cell Proliferation.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 75
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: We have used synthetic polymers as tools to probe endocytosis and lysosome function. Their particular value lies in their well-defined chemical constitution and in the possibility to custom-synthesize molecules with desired characteristics. Polyvinylpyrrolidone, Percoll and polystyrene beads have been 125I-labelled and used to explore the borderland of pinocytosis and phagocytosis. Derivatized poly(aspartamide), poly(hydroxypropylmethacrylamide) and a polylysine-poly(ethylene oxide) block copolymer have been used to investigate the effects of hydrophobic moieties and sugar residues on substrate-selection in pinocytosis. The effect of cationic moieties has been studied using vinylpyrrolidone-vinylamine copolymers.Poly(hydroxypropylmethacrylamide) with certain oligopeptide side---chains have been shown to be susceptible to lysosomal peptidases. Ethylene glycol oligomers are being used to study the basal permeability of the lysosome membrane.Soluble macromolecules have considerable potential in targeted drug-delivery. Drugs attached to appropriate polymers by covalent links that are susceptible to lysosomal enzymes can deliver drug to target cells and avoid unwanted sideeffects. Synthetic macromolecules have several advantages over their natural counterparts: they are chemically more robust, less immunogenic, and easier and cheaper to prepare in bulk.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 76
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Diagnostics are e. g. reagents or combinations of reagents or measure bloodcomponents down to concentrations of 10-15 mol/1 in reproducable form. To achieve this target diagnostics have to fullfill special requirements in purity, uniformity, producibility and reproducibility. These requirements are also valid for integrated polymers and plastics. Examples of the application of polymers and plastics in diagnostics are e. g. materials for the blood-plasma-separation, the stabilization of proteins, solid phases in immunoassays as reagent tubes, microtiterplates and latexparticles.Reciprocal actions between polymers, plastics, polymer additives, blood and bloodsubstances like proteins in diagnostic tests can be seen as indications to similar effects by the intracorporeal applications of plastics in surgery and in general for contacts of natural materials with plastics, as usual in the foodpacking.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
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  • 77
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Using Eupergit, a synthetic resin, as an example, the necessary characteristics of a support for high performance affinity chromatography (HPAC) are demonstrated. To such a support different ligands can be immobilized and used for the separation of biopolymers.From the range of possible applications a few examples are chosen. Immunoglobulins are isolated in one step by protein A-HPAC, the purified antibodies are immobilized and applied to immunoaffinity-HPLC for the isolation of corresponding antigens. Concanavalin A-HPAC of membrane proteins was chosen to represent chromatography with immobilized lectins. Antithrombin could be isolated from human plasma by the use of immobilized heparin. HPAC has the advantage of affinity chromatography, which is above all highly specific. As the support is resistant to high pressure and has well defined microparticles with a particular pore size, it provides a much higher yield at considerable flow rates. The handling of materials like this is simpler, the separation of the sample is quicker and can be reproduced more easily.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 78
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 166 (1989), S. 257-272 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Controlled polyelectrolyte adsorption can be used to render phospholipid bilayer membranes sensitive to physical and chemical signals. We describe in this paper the design and construction of macromolecular switches for bilayer membranes, which can be used to create lipid vesicles that release their contents rapidly and quantitatively in response to changes in pH, temperature, light intensity or glucose concentration. The kinetics and mechanisms of the molecular switching processes observed in such systems are also discussed.
    Notizen: Kontrollierte Adsorption von Polyelektrolyten kann ein wirksames Werkzeug im Design von dünnen molekularen Filmen sein. Man kann erwarten, daß die Adsorption von Polyelektrolytketten das empfindliche Kräftegleichgewicht erheblich beeinflußt, das die strukturellen und funktionellen Eigenschaften von geordneten Strukturen wie Einzel-, Doppel- und Mehrfachschichten bestimmt. Andererseits ist die Adsorption von Polyelektrolyten außerordentlich sensitiv auf Umgebungsparameter, z.B. pH, Temperatur oder lonenstärke. Kontrollierte Adsorption kann daher zu Sensitivität auf bestimmte chemische oder physikalische Stimuli führen, sodaß auf diese Weise ein molekularer Schaltmechanismus entworfen werden kann. Durch Umsetzen dieser ldee in reale Systeme gelang es uns, molekulares Schalten in Mischungen von Poly(2-ethylacrylsäre) mit natürlichen oder synthetischen Phosphatidylcholinen zu bewirken. Insbesondere haben wir Phosphatidylcholinvesikel hergestellt, die ihren lnhalt nach einer Änderung von pH, Temperatur, Glukosekonzentration oder nach Bestrahlung mit Licht schnell und quantitativ freisetzen. Die Entwicklung und die Herstellung von Doppelschichtmembranen, die auf solche Änderungen reagieren, sowie die Kinetik und der Mechanismus des damit verbundenen molekularen Schaltprozesses werden im vorliegenden Artikel diskutiert.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 79
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Enzymes can be immobilized by gel entrapment, by microencapsulation, by physical or ionic adsorption, by covalent binding to inorganic or organic carriers, or by whole cell immobilization. Of particular interest is the large number of chemical reactions developed for the covalent binding of enzymes via their nonessential functional groups to inorganic carriers such as glass, ceramics and iron, to natural polymers such as cellulose and Sepharose, and to synthetic polymers such as nylon, polyacrylamide, and other vinyl polymers and copolymers possessing reactive chemical groups. The stability of certain enzymes is markedly increased on their immobilization. It was thus possible to transform the biologically active polymer derivatives into active enzyme beads, enzyme capsules, enzyme columns and enzyme membranes and these enabled the construction of enzyme reactors such as the batch-stirred tank reactors, the continuous packed bed reactors, and fluidized bed reactors. So far mainly immobilized hydralases and isomerases are being used in industry on a large scale. It seems likely, however, that once adequate techniques become available for cofactor recycling, the use of immobilized enzymes will be extended to other organic reactions, particularly those involving stereospecific synthesis of simple or complex organic molecules. Among the industrial processes in which immobilized enzymes are being used, it is worth mentioning the industrial-scale continuous production of fructose enriched syrup from glucose by immobilized glucose-isomerase, the batch process for the production of 6-aminopenicillanic acid (6-APA) from penicillin G with the aid of immobilized penicillin amidase; the production of aspartame from aspartic acid and phenylalanine by immobilized thermoase; the large scale production of optically active amino acids with immobilized amino acid acylase; and the large scale production and application of immobilized lactase for the hydrolysis of lactose. The recently developed process for acrylamide production using immobilized nitrilase containing microbial cells should also be referred to. The successful use of an NAD-polyethylene glycol conjugate (NAD-PEG) as a nondialyzable water-soluble coenzyme derivative in the enzymic synthesis of leucine from α-ketoisocaproic acid and ammonia, in a membrane-enclosed reactor containing L-leucine dehydrogenase, NAD-PEG, formate and formate dehydrogenase, illustrates the new possibilities opened up by making use of cofactor-polymer conjugates. The use of enzyme-polymer conjugates in analytical and clinical is also illustrated.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 80
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The genetic make-up of living systems especially of isolated cells can be altered by a variety of methods including chemical or light-induced mutation. More modern procedures are the in vitro recombination of nucleic acids and the cell-cell fusion.The new methods are especially useful to reprogram microorganisms to produce valuable proteins or other natural products in excess quantties. In the following we will elucidate the importance of the new techniques by describing the bacterial production of glucose dehydrogenase, of the proteinase inhibitor stefin A and by outlining the methods and promisses of substractive cloning. Although the economic value of genetic engineering techniques still awaits justification, the importance of the methodology for basic biological research is well documented.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 81
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Immobilization of whole cells has become an efficient tool for biosynthesis, biotransformation and analysis. High cell density, high operational stability, easy handling, propably in continuous systems, and multiple reuse are important advantages of immobilized cells. In comparison to other methods like adsorption, crosslinking and encapsulation, the entrapment within a polymeric network is the most widely applied technique in heterogeneous biocatalysis. For immobilizing mammalian cells nearly exclusively the adsorption onto micorcarriers is used. Requirements for the polymers to be used in such immobilized cell systems are discussed in detail.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 82
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 168 (1989), S. 1-8 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Vier Pyridazinderivate wurden synthetisiert und als Beschleuniger für Naturkautschukmischungen entwickelt. Die rheologischen Eigenschaften wurden mit Hilfe eines Monsanto Rheometers 100 bestimmt. Die rheometrischen Daten wurden für die Berechnung der kinetischen Konstanten der Vulkanisationsreaktion in Anwesenheit der synthetisierten Verbindungen benutzt. Verglichen mit Mercaptobenzthiazol (MBT), einem Beschleuniger der häufig in der Kautschukindustrie eingesetzt wird, zeigten diese Verbindungen eine gute Beschleunigerwirksamkeit.
    Notizen: Four pyridazine derivatives were synthesized and evaluated as accelerators in natural rubber (NR) mixes. The rheological characteristics were determined by a Monsanto Rheometer 100. The kinetic constants for the vulcanization reaction in the presence of the synthetic compounds were calculated using the rheometric data. The compounds showed a good accelerating efficiency compared with mercaptobenzothiazole (MBT), which is widely used in rubber industry.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 83
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 170 (1989), S. 173-182 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die Ansammlung von als inaktiv angenommenen „Dimeren“ und „Trimeren“ sowie der Verbrauch von aktiven Spezies mit der Reaktionszeit im säurekatalysierten Furfurylalkohol (FA)/Formaldehyd (F) System wurde durch GPC-Technik unter Anwendung eines Doppeldetektors bewiesen.Ein Reaktionsmechanismus wurde für den Kondensationsprozeß vorgeschlagen, der einige Widersprüche der bisherigen Untersuchungen erklären kann.
    Notizen: Accumulation of “dimers” and “trimers” considered to be inactive and consumption of active ones with reaction time in furfuryl-alcohol (FA)/formaldehyde (F) acid catalyzed condensation system was proved by GPC technique using double detector.A reaction mechanism was proposed for the condensation process explaining some contradictions of investigations collected so far.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 84
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Dieser Artikel befaßt sich mit silylierten bzw. maleinisierten Polybutadienölen und ihren Effekten in Kieselsäure und Silicate bzw. Kreide enthaltenden Kautschukmischungen. Sie erweisen sich als wirksame Hilfsstoffe für die Substitution von Ruß durch mineralische Füllstoffe.
    Notizen: This paper deals with silylated and maleated polybutadiene oils and their effects in rubber compounds containing silica(tes) resp. chalk as fillers. They are shown to be efficient aids in the substitution of oil-dependent carbon black by mineral fillers.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 85
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 171 (1989), S. 79-89 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die isotherme und nichtisotherme Kristallisation von isotaktischem Polypropylen, das mit ausgewählten organischen Pigmenten gefärbt war, wurde mittels DSC untersucht. Es wurde gefunden, daß die Nukleierungsfähigkeit der Pigmente mit deren chemischem Aufbau und mit der Erniedrigung der freien Energie für den Keimbildungsprozeß verbunden ist. Die experimentellen Daten wurden mit Hilfe der bekannten Avrami-Gleichung analysiert.Blau-Pigment und Rot-Lack beschleunigen die Kristallisation von isotaktischem Polypropylen, während Orange-Pigment die Kristallisationsgeschwindigkeit etwas herabsetzt.
    Notizen: The isothermal and non-isothermal crystallization of isotactic polypropylene coloured with selected organic pigments was examined by differential scanning calorimetry. It was found that the nucleating ability of pigments is connected with their chemical nature and with the reduction of the free energy for critical nucleus formation. The experimental data were analysed in terms of the well known Avrami equation.Blue pigment and Red lake are substances which accelerate the crystallization of isotactic polypropylene, while Orange pigment decreases the crystallization rate slightly.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 86
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Um bei Kationen-Austauschmembranen eine dauerhafte Selektivität für die Durchlässigkeit von einwertigen Kationen zu erzielen, wurde eine Polyethylenimin-Schicht auf der Membranoberfläche durch Säureamidbindung zwischen Polyethylenimin und den —SO2Cl-Gruppen einer Styrol-co-Divinylbenzol-Membran erzeugt. Nach der Reaktion wurden die im Inneren der Membran verbleibenden —SO2Cl-Gruppen durch Tauchen in wäßrige Natronlauge hydrolysiert.Die so gewonnenen Kationen-Austauschmembranen wurden mittels Elektrodialyse von Seewasser hinsichtlich ihrer Selektivität für die Durchlässigkeit von einwertigen Kationen, ihres elektrischen Widerstandes, ihrer Stromleistung und ihrer überfüh-rungszahlen für Natrium-Ionen untersucht. ATR-IR-Messungen auf der Membran-oberfläche belegen, daß die Shäureamidbindung gegenüber starker Hydrolyseeinwirkung stabil war.
    Notizen: In order to give the monovalent cation permselectivity to the cation exchange membrane permanently, polyethyleneimine layer was formed on the membrane surface by acid-amide bond between polyethyleneimine and the —SO2Cl groups of a styrene-divinylbenzene copolymer membrane. After the reaction, the —SO2Cl groups remaining in the inner part of the membrane were hydrolyzed by immersing the membrane into an aqueous sodium hydroxide solution.The resultant cation exchange membranes were evaluated by electrodialysis of sea water from the point of view of the monovalent cation permselectivity, electric resistance of the membrane, current efficiency, and transport number of sodium ions calculated by membrane potential in connection with reduced viscosity of the various commercial polyethyleneimines, ATR-IR measurements on the membrane surface suggested that the acid-amide bond was stable for severe hydrolysis reaction.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 87
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 171 (1989), S. 141-152 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die Epoxidgruppen eines Copolymeren, das man durch Pfropfung von 2,3-Epoxypropylmethacrylat auf isotaktisches Polypropylen erhält, wurden mit niedermolekularen Carbonsäuren umgesetzt. Die Reaktion verläuft in Gegenwart von organischen Lösungsmitteln heterogen und kann durch tertiäre Amine beschleunigt werden. Die Geschwindigkeitskonstanten der Reaktion werden mit der Dissoziationskonstanten der gebundenen Säure und mit der Art des verwendeten Beschleunigers korreliert. Die Reaktivität der polymergebundenen Epoxidgruppen ändert sich im Vergleich mit Reaktionen unter homogenen Bedingungen nicht.
    Notizen: Epoxy groups on isotactic polypropylene, to which 2,3-epoxypropylmethacrylate was grafted, were reacted with low molecular carboxylic acids. The reaction proceeds under heterogeneous conditions in the presence of organic solvents and it may be catalysed by tertiary amines. The rate constants of this reaction are correlated with the dissociation constant of the bonded acid and with the character of the used catalyst. The reactivity of polymer-bonded epoxy groups is not changed when comparing with reactions performed under homogeneous conditions.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 88
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Es wird eine neue Methode zur Einführung von hydrophilen Polyetherseitenketten in segmentierte Polyurethane unter Verwendung eines Polypropylenoxid-Macromeren mit 1,3-Diol-Gruppen an einem Kettenende, die als Kettenverlängerer fungieren, beschrieben. In diesem Prozeß wird eine Seitenkette quantitativ und direkt in medizinische Polyurethanelastomere eingebaut. Diese Entwicklung ist auch für Biowerkstoffe in künstlichen Organen von Interesse.
    Notizen: A new method of introducing a hydrophilic polyether side chain into segmented polyurethane using a polypropylene oxide macromer with 1,3-diol at one chain-end, which behaves as chain extender, is described. In this procedure, a molecular-designed side-chain is incorporated quantitatively and directly into polyurethane biomedical elastomer. The design is also of interest to biomaterials in artificial organs.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 89
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 172 (1989), S. 233-233 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 90
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 173 (1989), S. 85-100 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Der Orientierungsmechanismus von kaltverstrecktem, teilkristallinem Polyoxymethylen wurde durch Messung der Intensität der Weitwinkel-Röntgenstreuung (WAXS) untersucht. Die Anisotropie der Proben wurde im einachsigen Zugversuch bei etwa 130°C im Temperaturbereich zwischen Glasübergangstemperatur und Schmelzpunkt erzeugt. Der Prozess der plastischen Deformation wurde für verschiedene Stadien der Verstreckung diskutiert. Die Orientierungsverteilung der Kristalllamellen wurde qualitativ charakterisiert durch die Berechnung von Polfiguren aus den WAXS Streuintensitätsdaten. Der Grad der Orientierung wurde durch die Berechnung des Orientierungsfaktors für den [100] Flächennormalenvektor der Einheitszelle beschrieben. Die Textur der eingeschnürten Proben mit hoher Orientierung wurde als Mischung von axialer und uniplanar-axialer Textur erkannt. Als mögliche Erklärung für diesen Orientierungstyp wird ein Einfluß der Probengeometrie angenommen.
    Notizen: The orientation mechanism of cold-drawn, partially crystalline polyoxymethylene (ULTRAFORM) samples was studied by performing wide angle X-ray scattering (WAXS) measurements. The anisotropic samples were prepared in uniaxial tensile tests around 130°C, in a temperature range between the glass transition and the melting point. The process of the plastic deformation is discussed for different degrees of anisotropy. The orientation distribution of the crystalline lamellae was qualitatively characterized by performing pole figure intensity calculations from the measured WAXS intensities. The degree of orientation was quantitatively described by calculating the orientation factors for the [100] normal vector of the unit cell. The texture of the necked samples with high orientation degrees was a mixture of axial and uniplanar-axial textures. An explanation for the formation of this kind of orientation is proposed assuming an influence of the sample geometry on the orientation process.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 91
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 173 (1989), S. 205-212 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Herkömmliches Vernetzen von Polyethylen niedriger Dichte (LDPE) wurde mit Dicumylperoxid (DCP) als Vernetzer durchgeführt. DCP wurde in verschiedenen Konzentrationen mit LDPE-Schnitzeln in einem Extruder bei 135 - 145°C gemischt. Monofilamentfäden wurden bei 110°C auf einer Laborziehmaschine gezogen. Die Zugdehnungseigenschaften, der prozentuale Schrumpf und die Dichte wurden mit Zunahme der DCP-Konzentration und der Heizdauer verbessert, während jedoch die prozentuale Quellung abnahm.
    Notizen: Conventional crosslinking of low density polyethylene (LDPE) was carried out using dicumyl peroxide (DCP) as crosslinking agent. DCP in various concentrations was mixed with LDPE chips in an extruder at 135 - 145°C. Monofilaments were drawn on a laboratory drawing machine at 110°C. It was found that tensile properties, percent shrinkage and density were improved with the increase in the concentration of DCP and in the heating period, whereas, however, the percent swelling decreased.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die Resultate von Untersuchungen über die chemische Wechselwirkung zwischen einigen monofunktionellen Modellverbindungen, die die Struktur und Reaktivität von wärmehärtbaren Phenol- und Harnstoff-Formaldehyd-Harzen simulieren, mit Holzkomponenten (Hemicellulosen, Cellulose und Lignin) werden dargelegt. Während Hemicellulosen deutlich dazu neigen, Kondensationsprodukte mit diesen Modellverbindungen zu ergeben, reagieren Lignine in manchen Fällen weniger leicht und abhängig davon, durch welchen Prozeß sie gewonnen worden sind, und abhängig von der Art der Modellverbindung. Cellulose reagierte wegen ihrer Kristallinität nicht unter den gegebenen Bedingungen.
    Notizen: Results are presented on the chemical interactions occurring when some monofunctional model compounds simulating the structure and reactivity of thermosetting phenol- and urea-formaldehyde resins are mixed with wood components (hemicelluloses, cellulose, and lignins). Whereas hemicelluloses clearly show a propensity to give condensation products with these model compounds, lignins can react less readily in some instances depending on the delignification procedure used to isolate them and on the type of model compound. Cellulose did not react under the conditions chosen, mostly because of its crystalline character.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 93
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 173 (1989), S. 183-193 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: XPS-, SSIMS- und Wasserkontaktwinkelmessungen wurden verwendet, um den chemischen Einfluß von CF4/O2-Entladungen auf Polycarbonat (PC) aus Bisphenol A zu charakterisieren. Die durch Plasmabehandlung erzeugte Oberflächenmodifizierung kann auf der Basis der im Plasma vorhandenen aktiven Spezies, deren Konzentration durch Actinometrie bestimmt worden ist, erklärt werden.Bei kleinen Gehalten an O2 im Gas (1%) tritt eine umfassende Fluorierung der Oberfläche bedingt durch die Pfropfung von Fluorkohlenstoff-Radikalen ein. Es werden perfluorierte Inseln gebildet, wie der hohe Wert des zunehmenden Kontaktwinkels zeigt. Bei 20-80% O2 reagieren Fluoratome mit der Oberfläche und ätzen sie teilweise. Kleine Gehalte an Fluor, aber keine perfluorierten Inseln werden beobachtet. Sauerstoff trägt zum Ätzen bei und oxidiert die PC-Oberfläche. Die Sauerstoffkonzentration auf der Oberfläche nimmt mit Zunahme des O2-Gehalts im Gas zu, ebenso die Bildung von stark oxidierten Inselchen auf der Probenoberfläche, wie die dramatische Abnahme der Kontaktwinkel zeigt. Eine Verminderung der Aromatizität der Oberfläche, die mit Hilfe von XPS und SSIMS beobachtet wird, ist die Folge dieser Reaktionen.
    Notizen: XPS, SSIMS and water contact angle measurements have been used to characterize the chemical effect of CF4/O2 discharges on polycarbonate (PC) made from bisphenol A. We found that the surface modification induced by plasma treatment can be clearly explained on the basis of the acitve species present in the plasma, whose concentration has been studied by actinometry.With very low amounts of O2 in the gas feed (1%) extensive fluorination of the surface occurs, due to grafting of the fluorocarbon radicals. Perfluorinated islands are formed, as shown by the high value of advancing contact angles. In the 20-80% O2 range, fluorine atoms react with the surface, partially inducing etching. Low amounts of fluorine are observed on the sample and no perfluorinated islands. Oxygen participates in etching and oxidizes the PC surface. We observed an increase of the surface concentration of oxygen with increasing the O2 amount in the gas feed and also the formation of strongly oxidized islets on the sample surface, as shown by the dramatic reduction of receding contact angles. A reduction of surface aromaticity, observed by XPS and SSIMS, is the consequence of these reactions.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 173 (1989), S. 213-218 
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: An attempt was made to obtain cationic cellulose derivatives of highest possible degrees of substitution by treating dissolving grade pulps under homogeneous conditions with glycidyltrimethylammonium chloride in the solvent system dimethylacetamide/lithiumchloride. The influence of temperature, reaction time and molar ratio of the reagents was examined. A reaction time of 8 h and a temperature of 70°C have been found to be optimal. The cellulose content in solution and the molar ratio of the reagents have to be adapted to the used pulp.
    Notizen: Es wurde der Versuch unternommen, durch Umsetzung von Zellstoffen mit Glycidyltrimethylammoniumchlorid im Lösungsmittelsystem Dimethylacetamid/Lithiumchlorid kationische Cellulosederivate mit möglichst hohen Substitutionsgraden zu erhalten. Hierzu wurden Temperaturabhängigkeit, Reaktionsdauer und Molverhältnis der Reaktanden untersucht. Als optimal erwies sich eine Reaktionsdauer von 8 h bei einer Reaktionstemperatur von 70°C. Der Cellulosegehalt in Lösung und das Molverhältnis der Reaktanden müssen dem verwendeten Zellstoff angepaßt werden.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 773-781 
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A second example of insertion of a water molecule into the helical backbone of an apolar peptide is presented here and compared to a similar occurrence in a longer peptide with the same type of sequence of residues, i.e., Boc-Aib-(Ala-Leu-Aib)3-OMe. The backbone of the title compound assumes an approximate 310-helical form with three 4 → 1 hydrogen bonds. In the place of a fourth 4 → 1 hydrogen bond, a water molecule is inserted between O(1) and N(4), and acts as a bridge by forming hydrogen bonds N(4) … W(1) (2.95 Å) and W(1) … O(1) (2.81 Å). The water molecule participates in a third hydrogen bond with a neighboring peptide molecule, W(1) … O(4) (2.91 Å). The insertion of the water molecule causes the apolar peptide to mimic an amphiphilic helix. Crystals grown from ethyl acetate/petroleum ether (reported here) or from methanol/water solution are in space group P212121 with a = 12.024(4) Å, b = 15.714(6) Å, c = 21.411(7) Å, Z = 4 and dcalc = 1.124 g/cm3 for C32H58N6O9 · H2O. The overall agreement factor R is 6.3% for 2707 reflections observed with intensities 〉 3σ(F) and the resolution is 0.90 Å.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Chemical shifts of base and H1′ protons of the single-stranded hexamers d(ATTACC) and d(GGTAAT), of the 1 : 1 mixtures of these complementary hexamers, and of the self-complementary dodecamer d(ATTACCGGTAAT) were measured at various temperatures in aqueous solution. Four different sample concentrations were used in the case of the dodecamer and of the mixture of the complementary hexamers; the individual hexamers were measured at two different DNA concentrations. Absorbance temperature profiles at five different NaCl concentrations were measured for the dodecamer in order to quantify the effect of the ionic strength on the duplex formation.Under suitable conditions of nucleotide concentration, temperature, and ionic strength, the dodecamer adopts either a B-DNA duplex or a hairpin-loop structure. Chemical shift vs temperature profiles, constructed for all samples, were used to obtain thermodynamic parameters either for the various stacking interactions in the single strands or for the duplex or the hairpin-loop formation. In the analysis of the duplex formation of the hexamers, a two-state approach appeared too simple, because systematic deviations were revealed. Therefore, a new three-state model (DUPSTAK) was developed. In order to investigate the magnitude of error arising from the use of the two-state approach in cases where the DUPSTAK model appears more appropriate, a series of test calculations was made. The magnitude of error in the enthalpy and in the entropy of duplex melting is found to depend linearly upon the actual melting temperature and not upon the individual ΔHOd and ΔSOd values.Thermodynamic analysis of the chemical shift vs temperature profiles in D2O solution (no added salt) yields an average Tmd value of 341 K (1M DNA) and ΔHOd of -121 kJ · mol-1 for the dimer/random-coil transition of the hexamer duplex d(ATTACC) · d(GGTAAT). For the duplex ⇄ random-coil transition of the 12-mer d(ATTACCGGTAAT) an average Tmd value of 336 K (1M DNA) and ΔHOd of -372 kJ · mol-1 are found. The hairpin/random-coil transition of d(ATTACCGGTAAT) is characterized by a rather large ΔHOh value, -130 kJ · mol-1, and an average Tmh value of 304 K.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A computational method is elaborated for studying the water environment around regular polynucleotide duplexes; it allows rigorous structural information on the hydration shell of DNA to be obtained. The crucial aspect of this Monte Carlo simulation is the use of periodical boundary conditions. The output data consists of local maxima of water density in the space near the DNA molecule and the properties of one- and two-membered water bridges as function of pairs of polar groups of DNA.In the present paper the results for poly(dG) · poly(dC) and poly(dG-dC) · poly(dG-dC) are presented. The differences in their hydration shells are of a purely structural nature and are caused by the symmetry of the polar groups of the polymers under study, the symmetry being reflected by the hydration shell.The homopolymer duplex hydration shell mirrors the mononucleotide repeat. The water molecules contacting the polynucleotide in the minor groove are located nearly in the plane midway between the planes of successive base pairs. One water molecule per base pair forms a water bridge facing two polar groups of bases from adjacent base pairs and on different strands making a “spine”-like structure. In contrast, the major groove hydration is stabilized exclusively by two-membered water bridges; the water molecules deepest in the groove are concentrated near the plane of the corresponding base pair.The alternating polymer is characterized by a marked dyad symmetry of the hydration shell corresponding to the axis between two successive base pairs. The minor groove hydration of the dCpdG step resembles the characteristic features of the homopolymer, but the bridge between the O2 oxygens of the other base-stacking type is formed by two water molecules. The major groove hydration is characterized by high probability of one-membered water bridges and by localization of a water molecule on the dyad axis of the dGpdC step.The found structural elements are discussed as reasonable invariants of a dynamic hydration shell.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Biopolymers 28 (1989) 
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We report dynamic light scattering measurements over a wide range of scattering vectors for fractionated samples of porcine submaxillary mucin (PSM) glycoproteins in two different solvents: 0.1M NaCl, and 6M GdnHCl. The relaxation spectrum has been successfully resolved into a slow mode corresponding to pure translational diffusion and a fast mode containing information on the relaxation times for intramolecular motion. Analysis of the slow mode permits a light scattering evaluation of the polydispersity of these high molecular weight mucin glycoprotein fractions. Determination of the longest intramolecular relaxation times τ1 shows that these are much longer for the PSM fractions in 0.1M NaCl compared to 6M GdnHCl. These data are consistent with earlier studies showing that the chain conformation is the same in both solvents, but that in 0.1M NaCl, the PSM glycoprotein undergoes a self-association process that is end-to-end in nature. Since the τ1 value is intimately related to the viscoelastic behavior of PSM solutions and gels, it is interesting to speculate that the end-to-end association process may be physiologically important.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 835-849 
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Theoretical computations are performed of the intercalative binding to a model d(CpG)2 minihelix of 7-H pyrido[4.3C]carbazole, the precursor of the antitumor bisintercalating drug ditercalinium. The conformations of the intercalation site are generated by the AGNAS procedure (algorithm to generate nucleic acid structures) of Miller and co-workers. The ligand-nucleotide interactions and the nucleotide conformational energies are computed with the SIBFA procedures (sum of interactions between fragments ab intio computed), which use formulas of empirical origin that reproduce ab initio SCF (self-consistent field) computations. Among the candidate intercalation sites most favored energetically, one has a pattern of conformational angles related to the one determined crystallographically by Sobell et al. in a series of x-ray structural studies of small intercalator-dinucleotide monophosphate complexes. Optimal values of the unwinding angle, found in the range of -12° to -14°, are consistent with available experimental data on DNA.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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