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  • General Chemistry  (10,801)
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  • 1
    Publication Date: 2021-05-19
    Description: Aleksey Sergeevich Vinnov (25.05.1958 – 04.06.2019) was a Candidate of Sciences (Engineering), an Associate Professor, a talented lecturer, a rector of the Kerch Maritime Technological Institute (KMTI) in 2000–2005, a Senior Researcher in the FSBSI “Southern Scientific Research Institute of Marine Fisheries and Oceanography” (YugNIRO), and a Deputy Head for Operation and Quality of the Limited Liability Company under the Laws of Russian Federation “Aquamarine”. A.S. Vinnov made a great contribution into the development of education and science in the field of fisheries. Aleksey Sergeevich began his professional life as a Junior Researcher in the Astrakhan Technical Institute of Fishing Industry and Economy and defended his Candidate's Thesis in 1988. He dedicated the major part of his working career to the Kerch State Maritime Technological University, where he had been employed for 21 years, taking positions from a senior lecturer of the Department of Fish Processing Technology, an Associate Professor, the Dean of the Technological Faculty, the vice-rector for academic affairs, to the rector of the University. A.S. Vinnov was known for his rational thinking and professional integrity; he was diplomatic and considerate, and proved to be a competent leader. Vinnov's research works were dedicated to the issues of development of production technology for canned fish and fish protein mass, of kinetics of enzymatic hydrolysis, and many other subjects. A.S. Vinnov was honored with several badges of distinction due to his high professional expertise and personal contribution to the development of fisheries field, particularly education.
    Description: Алексей Сергеевич Виннов (25.05.1958 – 04.06.2019 гг.) — кандидат технических наук, доцент, талантливый преподаватель, ректор Керченского морского технологического института с 2000 по 2005 г. (КМТИ), старший научный сотрудник ФГБНУ «Южный научно-исследовательский институт рыбного хозяйства и океанографии» (ЮгНИРО), заместитель директора по производству и качеству ООО «Аквамарин». А.С. Виннов внес огромный вклад в развитие образования и науки рыбной отрасли. Свою трудовую деятельность Алексей Сергеевич начал в должности младшего научного сотрудника Астраханского технического института рыбной промышленности и хозяйства, успешно защитив в 1988 г. кандидатскую диссертацию. Большую часть своей трудовой деятельности он посвятил Керченскому государственному морскому технологическому университету, проработав здесь 21 год в должностях от старшего преподавателя кафедры технологии рыбных продуктов, доцента, декана технологического факультета, проректора по учебной работе до ректора университета. А.С. Виннов обладал рациональным мышлением, был очень грамотным, тактичным человеком, умелым руководителем. Научная деятельность Алексея Сергеевича была посвящена изучению вопросов усовершенствования технологии рыбных консервов, рыбных белковых масс, кинетики ферментативного гидролиза, а также многим другим. За личный вклад в развитие образования и рыбной отрасли, за высокий профессионализм А.С. Виннов был удостоен ряда почетных знаков отличия.
    Description: Published
    Keywords: Researchers ; Engineering ; Fish processing ; Canned food ; Rector ; Proteins ; Hydrolysis
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.91-95
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  • 2
    Publication Date: 2021-05-19
    Description: Наряду с исследованиями по определению сырьевой базы Азово-Черноморского бассейна, при создании института АзЧерНИРО в 1933 г. была сразу организована научно-исследовательская лаборатория техники лова рыбы. За все время функционирования этого подразделения такие специалисты, как С.С. Виннов, О.И. Саковец, С.Я. Наместников, Е.Е. Шапунов, В.М. Кириллов, В.Г. Герасимов, В.С. Долбиш, Н.Г. Думин, В.Г. Васильев, А.А. Яковлев, Е.С. Деньгин, В.И. Абакаров, В.Н. Миронов, В.В. Стрельцов, А.С. Вайнерман, В.К. Яшкин, Ю.В. Шишов, А.М. Стафикопуло в течение многих лет вносили огромный вклад в развитие рыболовства в Азово-Черноморском бассейне и Мировом океане. До 1950 г. траловый промысел в Черном море отсутствовал, хотя были известны попытки внедрить этот вид лова в черноморское рыболовство. Так, в начале 1909 г. в северо-западной части Черного моря работал траулер «Федя». К концу 1911 г. количество траулеров, которые работали в данном регионе моря, увеличилось до 9 судов. Уловы состояли на 98-99 % из осетровых и на 1-2 % из камбалы. Ввиду очень большого вылова молоди осетровых рыб траловый промысел вскоре был запрещен. В 1932 г. из Мурманска для выяснения эффективности тралового лова в Черном море был послан рыболовный траулер «Абрек». Почти у всего черноморского побережья пробовали ловить отечественным промысловым тралом, применяемым в Баренцевом море для добычи трески. При этом отмечалось, что уловы камбалы были очень низкими. Очевидно, одной из причин была неприспособленность самой конструкции трала для лова этого вида рыб. В конце 1933 г. траулер вернулся в Мурманск. В 1949 г. Черноморская научно-промысловая экспедиция возобновила работы по освоению тралового лова в Черном море. Перед экспедицией стояла задача всесторонне изучить ихтиофауну моря и выяснить возможности применения ряда поисковых орудий лова, в том числе донного трала. С этой целью было разработано и испытано несколько типов донных тралов. С конца 1949 г. были начаты исследования по разработке конструкции разноглубинного трала для Черного моря. К тому времени инженерами М.К. Кокоревым, В.Ф. Шушпановым и А.Н. Потехиным была разработана специальная подъемно-распорная система. В соответствии с ее техническими данными в дальнейшем проектировались сетные части трала. Первый проект опытного рыболовного разноглубинного морского трала разрабатывался для лова мелких черноморских пелагических рыб в толще воды, на глубинах от 0 до 100 м, с одного судна. Большой вклад в развитие тралового промысла в Черном море внес А.Н. Самарянов.
    Description: Published
    Keywords: Engineering ; Fishing gear ; Fishing fleet ; Fishing vessels ; Trawlers ; Anchovy fisheries ; Sprat fisheries ; Purse fishing ; Commercial species ; Mullets
    Repository Name: AquaDocs
    Type: Conference Material , Non Refereed
    Format: pp.247-254
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  • 3
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-17
    Keywords: Engineering
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-08-17
    Description: Polyamide thickness and roughness have been identified as critical properties that affect thin-film composite membrane performance for reverse osmosis. Conventional formation methodologies lack the ability to control these properties independently with high resolution or precision. An additive approach is presented that uses electrospraying to deposit monomers directly onto a substrate, where they react to form polyamide. The small droplet size coupled with low monomer concentrations result in polyamide films that are smoother and thinner than conventional polyamides, while the additive nature of the approach allows for control of thickness and roughness. Polyamide films are formed with a thickness that is controllable down to 4-nanometer increments and a roughness as low as 2 nanometers while still exhibiting good permselectivity relative to a commercial benchmarking membrane.
    Keywords: Engineering
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2018-09-07
    Description: Zeolitic imidazolate framework (ZIF) membranes are emerging as a promising energy-efficient separation technology. However, their reliable and scalable manufacturing remains a challenge. We demonstrate the fabrication of ZIF nanocomposite membranes by means of an all-vapor-phase processing method based on atomic layer deposition (ALD) of ZnO in a porous support followed by ligand-vapor treatment. After ALD, the obtained nanocomposite exhibits low flux and is not selective, whereas after ligand-vapor (2-methylimidazole) treatment, it is partially transformed to ZIF and shows stable performance with high mixture separation factor for propylene over propane (an energy-intensive high-volume separation) and high propylene flux. Membrane synthesis through ligand-induced permselectivation of a nonselective and impermeable deposit is shown to be simple and highly reproducible and holds promise for scalability.
    Keywords: Engineering
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-09-14
    Keywords: Engineering
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2018-09-14
    Description: Insects are among the most agile natural flyers. Hypotheses on their flight control cannot always be validated by experiments with animals or tethered robots. To this end, we developed a programmable and agile autonomous free-flying robot controlled through bio-inspired motion changes of its flapping wings. Despite being 55 times the size of a fruit fly, the robot can accurately mimic the rapid escape maneuvers of flies, including a correcting yaw rotation toward the escape heading. Because the robot’s yaw control was turned off, we showed that these yaw rotations result from passive, translation-induced aerodynamic coupling between the yaw torque and the roll and pitch torques produced throughout the maneuver. The robot enables new methods for studying animal flight, and its flight characteristics allow for real-world flight missions.
    Keywords: Engineering
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 8
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-04-27
    Keywords: Engineering
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 9
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-09-14
    Keywords: Engineering
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 10
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-03-09
    Keywords: Engineering
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    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 11
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2018-01-19
    Keywords: Engineering
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 12
    Unknown
    Berlin, Heidelberg : Springer Vieweg
    Keywords: Engineering ; Robotics ; Automation ; Industrial engineering ; Production engineering ; Economic sociology ; Engineering ; Industrial and Production Engineering ; Organizational Studies, Economic Sociology ; Robotics and Automation
    Description / Table of Contents: Einleitung --- Prognostizierte Veränderungen der gestaltbaren Arbeitssystemdimensionen --- Systeme zur Assistenz und Effizienzsteigerung in manuellen Produktionsprozessen der Industrie auf Basis von Projektion und Tiefendatenerkennung --- Betriebliche Auswirkungen industrieller Servicerobotik am Beispiel der Kleinteilemontage --- Erweiterte Horizonte – Ein technischer Blick in die Zukunft der Arbeit --- Soziotechnische Assistenzsysteme für die Produktionsarbeit in der Textilbranche --- Lernförderliche Arbeitssysteme für die Arbeitswelt von morgen --- Assistenz und Wissensvermittlung am Beispiel von Montage- und Instandhaltungstätigkeiten --- Der Mensch in Interaktion mit autonomen Planungs- und Steuerungssystemen für Cyber-Physische Produktionssysteme --- ReApp – Wiederverwendbare Roboterapplikationen für flexible Roboteranlagen - Auswirkungen der Ergebnisse aus ReApp auf betriebliche Funktionen am Beispiel eines Anwendungsfalls in der Elektroindustrie --- Modellierungsansatz für ein arbeitsplatznahes Beschreibungsmodell der »Arbeitswelt Industrie 4.0 --- Die Zukunft der Arbeit im demografischen Wandel --- “Social Manufacturing and Logistics“ – Arbeit in der digitalisierten Produktion --- Lernförderliche Arbeitsorganisation in der Industrie 4.0 --- Decision Support Pipelines – Durchgängige Datenverarbeitungsinfrastrukturen für die Entscheidungen von morgen --- Gerechtigkeit in flexiblen Arbeits- und Managementprozessen --- Technologie, Organisation, Qualifikation
    Pages: Online-Ressource (XI, 246 Seiten) , 62 Abbildungen, 56 Abbildungen in Farbe
    ISBN: 9783662492666
    Language: German
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  • 13
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-06-23
    Keywords: Engineering
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 14
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-06-23
    Keywords: Engineering
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 15
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-06-16
    Keywords: Engineering
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 16
    Publication Date: 2017-06-23
    Description: Exoskeletons and active prostheses promise to enhance human mobility, but few have succeeded. Optimizing device characteristics on the basis of measured human performance could lead to improved designs. We have developed a method for identifying the exoskeleton assistance that minimizes human energy cost during walking. Optimized torque patterns from an exoskeleton worn on one ankle reduced metabolic energy consumption by 24.2 ± 7.4% compared to no torque. The approach was effective with exoskeletons worn on one or both ankles, during a variety of walking conditions, during running, and when optimizing muscle activity. Finding a good generic assistance pattern, customizing it to individual needs, and helping users learn to take advantage of the device all contributed to improved economy. Optimization methods with these features can substantially improve performance.
    Keywords: Engineering
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  • 17
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-11-24
    Keywords: Engineering
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 18
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-12-01
    Description: Kim et al . (Reports, 28 April 2017, p. 430) presented results for the solar-driven harvesting of water from air via metal-organic frameworks as a prodigious potential advance toward remedying global water shortages. Basic thermodynamics and a survey of multiple off-the-shelf technologies show that their approach is vastly inferior in efficiency (and thereby in feasibility) to available alternatives.
    Keywords: Engineering
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  • 19
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-12-01
    Keywords: Engineering
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 20
    Publication Date: 2017-12-01
    Description: In their comment, Bui et al . argue that the approach we described in our report is vastly inferior in efficiency to alternative off-the-shelf technologies. Their conclusion is invalid, as they compare efficiencies in completely different operating conditions. Here, using heat transfer and thermodynamics principles, we show how Bui et al .’s conclusions about the efficiencies of off-the-shelf technologies are fundamentally flawed and inaccurate for the operating conditions described in our study.
    Keywords: Engineering
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  • 21
    Publication Date: 2017-05-12
    Description: Bacteria within communities can interact to organize their behavior. It has been unclear whether such interactions can extend beyond a single community to coordinate the behavior of distant populations. We discovered that two Bacillus subtilis biofilm communities undergoing metabolic oscillations can become coupled through electrical signaling and synchronize their growth dynamics. Coupling increases competition by also synchronizing demand for limited nutrients. As predicted by mathematical modeling, we confirm that biofilms resolve this conflict by switching from in-phase to antiphase oscillations. This results in time-sharing behavior, where each community takes turns consuming nutrients. Time-sharing enables biofilms to counterintuitively increase growth under reduced nutrient supply. Distant biofilms can thus coordinate their behavior to resolve nutrient competition through time-sharing, a strategy used in engineered systems to allocate limited resources.
    Keywords: Engineering
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  • 22
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-05-12
    Keywords: Engineering
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 23
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-02-10
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
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  • 24
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-01-27
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 25
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-02-17
    Description: Engineering has an image problem. The phrase "engineering disaster" rolls off the tongue, while great technical achievements are more often heralded as "scientific miracles." Enter Dream Big. Sponsored by the American Society of Civil Engineers with support from Bechtel Corporation, the film sets out to reframe engineering as a force for good and a profession in service to people and the planet. Author: Donna Riley
    Keywords: Engineering
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  • 26
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-07-21
    Keywords: Engineering
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  • 27
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-07-21
    Keywords: Engineering
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  • 28
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-05-26
    Keywords: Engineering
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  • 29
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-11-10
    Keywords: Engineering
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  • 30
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-01-27
    Description: Polynitrogens have the potential for ultrahigh-performing explosives or propellants because singly or doubly bonded polynitrogens can decompose to triply bonded dinitrogen (N2) with an extraordinarily large energy release. The large energy content and relatively low activation energy toward decomposition makes the synthesis of a stable polynitrogen allotrope an extraordinary challenge. Many elements exist in different forms (allotropes)—for example, carbon can exist as graphite, diamond, buckyballs, or graphene. However, no stable neutral allotropes are known for nitrogen, and only two stable homonuclear polynitrogen ions had been isolated until now—namely, the N3− anion (1) and the N5+ cation (2). On page 374 of this issue, Zhang et al. (3) report the synthesis and characterization of the first stable salt of the cyclo-N5− anion, only the third stable homonuclear polynitrogen ion ever isolated. Author: Karl O. Christe
    Keywords: Inorganic Chemistry
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  • 31
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    Berlin, Heidelberg : Springer Vieweg
    Keywords: Engineering ; Humanities ; Digital libraries ; Computers ; Educational technology ; Electrical engineering ; Engineering ; Communications Engineering, Networks ; Information Systems and Communication Service ; Digital Humanities ; Technology and Digital Education
    Description / Table of Contents: Seit Jahren wird unser Alltag geprägt von zunehmender Automation und Vernetzung, die Digitalisierung genannt wird. Sensoren erfassen immer mehr unterschiedliche Daten und werden von intelligenten Algorithmen zunehmend präzisier analysiert. Dies führt nicht nur zu einem anderen Verhältnis im Umgang und bei der Nutzung von Daten durch Menschen und Maschinen, sondern wird auch dramatisch Aufgaben und Prozesse verändern. Die damit verbundenen Arbeitsanforderungen werden zum massiven Wandel von Berufsbildern führen, in dem einfache Tätigkeiten automatisiert und komplexe Tätigkeiten vereinfacht werden. Nicht nur das Arbeiten sondern auch das Lernen, Lehren und Forschen verändert sich durch die Digitalisierung. Die technischen Möglichkeiten wandeln die Lebenswelten mit ihren urbanen Versorgungs- und Infrastrukturen und eröffnen den Wirtschaftsräumen neue Geschäftsmodelle. Diese parallel einsetzenden Entwicklungen führen zu radikalen Umbrüchen, die in den kommenden Jahren sämtliche Aspekte der Gesellschaft verändern werden
    Pages: Online-Ressource (IX, 199 Seiten)
    ISBN: 9783662528549
    Language: German
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  • 32
    Keywords: Earth sciences ; Natural disasters ; Engineering geology ; Engineering ; Geology ; Foundations ; Hydraulics ; Sustainable development ; Earth Sciences ; Natural Hazards ; Geoengineering, Foundations, Hydraulics ; Sustainable Development
    Description / Table of Contents: ISDR-ICL Sendai Partnerships 2015-2025 --- The ISDR-ICL Sendai Partnerships 2015-2025: Background and Content --- Forum lectures --- Rupestrian world heritage sites: Instability investigation and sustainable mitigation --- Subaerial landslide-generated waves: Numerical and laboratory simulations --- Rockfall occurrence and fragmentation --- Contribution from signatory organizations of the Sendai Partnerships --- International Consortium on Landslides (ICL) --- International Consortium on Landslides (ICL) - The proposing organization of the ISDR-ICL Sendai partnerships 2015-2025 --- United Nations Office for Disaster Risk Reduction (UNISDR) --- UNISDR‘s Contribution to Science and Technology for Disaster Risk Reduction and the Role of the International Consortium on Landslides (ICL) --- United Nations Educational, Scientific and Cultural Organization (UNESCO) --- UNESCO’s Contribution to the Implementation of UNISDR’s Global Initiative and ICL --- United Nations University (UNU) --- The United Nations University: Research and Policy Support for Environmental Risk Reduction --- World Meteorological Organization (WMO) --- Concerted International Efforts for Advancing Multi-Hazard Early Warning Systems --- International Council for Science (ICSU) --- On Future Challenges for the Integration of Science into International Policy Development for Landslide Disaster Risk Reduction --- World Federation of Engineering Organizations (WFEO) --- World Federation of Engineering Organizations Activities in Disaster Risk Reduction --- Disaster Prevention Research Institute (DPRI), Kyoto University --- National Civil Protection Department, Italian Presidency of the Council of Ministers, Government of Italy --- Understanding and Reducing Landslide Disaster Risk: Challenges and Opportunities for Italian Civil Protection --- Landslide Dynamics: ISDR-ICL Landslide Interactive Teaching Tools (LITT) --- Progress of the World Report on Landslides --- International Programme on Landslides (IPL): Objectives, History and List of World Centres of Excellence and IPL Projects --- UNESCO-KU-ICL UNITWIN Cooperation Programme for Landslides and Water-Related Disaster Risk Management. Landslides: Journal of the International Consortium on Landslides --- IPL Activities --- Advanced Technologies for Landslides (WCoE 2014-2017, IPL-196, IPL-198) --- Mechanisms of Landslides and Creep in Over-Consolidated Clays and Flysch (WCoE 2014-2017 --- Research on Heavy-Rainfall-Induced and Hydraulic-Driven Geological Hazards in China (WCoE 2014-2017). Landslide Risk Reduction in Croatia: Scientific research in the framework of the WCoE 2014-2017, IPL-173, IPL-184, ICL ABN --- Shapes and Mechanisms of Large-scale Landslides in Japan: Forecasting Analysis from an Inventory (WCoE 2014–2017 --- Retrospective and Prospects for Cold Regions Landslide Research (2012-2016) (WCoE 2014-2017, IPL-132, IPL-167, IPL-203, CRLN --- Large-scale Rockslide Inventories: from the Kokomeren River Basin to the Entire Central Asia Region (WCoE 2014-2017, IPL-106-2) --- Interventions for Promoting Knowledge, Innovations and Landslide Risk Management Practices within South and Southeast Asia (WCoE 2014-2017) --- Promoting a Global Standard for Community-based Landslide Early Warning Systems (WCoE 2014-2017, IPL-158, IPL-165) --- Model Policy Frameworks, Standards and Guidelines on Landslide Disaster Reduction (WCoE 2014-2017) --- Landslide Hazard and Risk Management (WCoE 2014-2017) --- Mitigation of Landslide Hazards in Ukraine under the Guidance of ICL: 2009–2016 (IPL-153, IPL-191) --- Development of a Hazard Evaluation Technique for Earthquake-Induced Landslides Based on an Analytic Hierarchy Process (AHP) (IPL-154) --- The Croatian-Japanese SATREPS Joint Research Project on Landslides (IPL-161)
    Pages: Online-Ressource (XXVI, 586 pages) , 372 illustrations, 350 illustrations in color
    ISBN: 9783319594699
    Language: English
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  • 33
    Unknown
    Berlin, Heidelberg : Springer Vieweg
    Keywords: Engineering ; Humanities ; Digital libraries ; Educational technology ; Electrical engineering ; Engineering ; Communications Engineering, Networks ; Digital Humanities ; Technology and Digital Education
    Description / Table of Contents: Vorwort --- Einleitung --- Bürger --- Wenn Bots sich unter Leute mischen: Social Bots in den Sozialen Medien --- Digitale Partizipation in Wissenschaft und Wirtschaft --- Entwicklung einer soziodigitalen Souveränität --- Unternehmen --- Digitale Souveränität – ein mehrdimensionales Handlungskonzept für die deutsche Wirtschaft --- Privatheit und digitale Souveränität in der Arbeitswelt 4.0 --- Staat --- Mehr Daten, weniger Vertrauen in Statistik – freie Fahrt für ‚alternative Fakten‘? --- Internationale Perspektiven auf digitale Souveränität --- Digitalisierung der Bildung als staatliche Aufgabe --- Ausblick
    Pages: Online-Ressource (IX, 187 Seiten) , 40 Abbildungen in Farbe
    ISBN: 9783662557969
    Language: German
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  • 34
    Keywords: Engineering ; Project management ; Engineering design ; Automotive Engineering ; Project Management ; Engineering Design
    Description / Table of Contents: A - Die Entwicklung: Drei Erfolgsstories --- Die StreetScooter-Gründer-Story --- Die StreetScooter-Meilensteine 2008-2017 --- Die StreetScooter-Entwicklungsstory --- Die StreetScooter-Protagonisten-Story --- B - Die Lösung: Return on Engineering: Die StreetScooter-Lösungsbausteine. C - Die Perspektive: Die StreetScooter-Netzwerk-Story --- Die StreetScooter-Produktions-Story --- Die StreetScooter-Post-Story --- Die StreetScooter-Mobilitätslösung --- Die StreetScooter-Vision. A - The Development: Three Stories of Success --- The StreetScooter Founder Story --- The StreetScooter Milestones 2008-2017 --- The StreetScooter Development Story --- The StreetScooter Protagonists Story --- B - The Solution: Return on Engineering: The StreetScooter Building Blocks --- C - The Perspective: The StreetScooter Network Story --- The StreetScooter Production Story --- The StreetScooter Post Story --- The StreetScooter Mobility Solution --- The StreetScooter Vision
    Pages: Online-Ressource (VII, 213 Seiten)
    ISBN: 9783662549971
    Language: German
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  • 35
    Unknown
    Berlin, Heidelberg : Springer Vieweg
    Keywords: Engineering ; Humanities ; Digital libraries ; Computers ; Educational technology ; Electrical engineering ; Engineering ; Communications Engineering, Networks ; Information Systems and Communication Service ; Digital Humanities ; Technology and Digital Education
    Description / Table of Contents: Seit Jahren wird unser Alltag geprägt von zunehmender Automation und Vernetzung, die Digitalisierung genannt wird. Sensoren erfassen immer mehr unterschiedliche Daten und werden von intelligenten Algorithmen zunehmend präzisier analysiert. Dies führt nicht nur zu einem anderen Verhältnis im Umgang und bei der Nutzung von Daten durch Menschen und Maschinen, sondern wird auch dramatisch Aufgaben und Prozesse verändern. Die damit verbundenen Arbeitsanforderungen werden zum massiven Wandel von Berufsbildern führen, in dem einfache Tätigkeiten automatisiert und komplexe Tätigkeiten vereinfacht werden. Nicht nur das Arbeiten sondern auch das Lernen, Lehren und Forschen verändert sich durch die Digitalisierung. Die technischen Möglichkeiten wandeln die Lebenswelten mit ihren urbanen Versorgungs- und Infrastrukturen und eröffnen den Wirtschaftsräumen neue Geschäftsmodelle. Diese parallel einsetzenden Entwicklungen führen zu radikalen Umbrüchen, die in den kommenden Jahren sämtliche Aspekte der Gesellschaft verändern werden
    Pages: Online-Ressource (IX, 199 Seiten)
    ISBN: 9783662528549
    Language: German
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  • 36
    Unknown
    Berlin, Heidelberg : Springer Vieweg
    Keywords: Engineering ; Humanities ; Digital libraries ; Educational technology ; Electrical engineering ; Engineering ; Communications Engineering, Networks ; Digital Humanities ; Technology and Digital Education
    Description / Table of Contents: Vorwort --- Einleitung --- Bürger --- Wenn Bots sich unter Leute mischen: Social Bots in den Sozialen Medien --- Digitale Partizipation in Wissenschaft und Wirtschaft --- Entwicklung einer soziodigitalen Souveränität --- Unternehmen --- Digitale Souveränität – ein mehrdimensionales Handlungskonzept für die deutsche Wirtschaft --- Privatheit und digitale Souveränität in der Arbeitswelt 4.0 --- Staat --- Mehr Daten, weniger Vertrauen in Statistik – freie Fahrt für ‚alternative Fakten‘? --- Internationale Perspektiven auf digitale Souveränität --- Digitalisierung der Bildung als staatliche Aufgabe --- Ausblick
    Pages: Online-Ressource (IX, 187 Seiten) , 40 Abbildungen in Farbe
    ISBN: 9783662557969
    Language: German
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  • 37
    Keywords: Earth sciences ; Natural disasters ; Engineering geology ; Engineering ; Geology ; Foundations ; Hydraulics ; Sustainable development ; Earth Sciences ; Natural Hazards ; Geoengineering, Foundations, Hydraulics ; Sustainable Development
    Description / Table of Contents: ISDR-ICL Sendai Partnerships 2015-2025 --- The ISDR-ICL Sendai Partnerships 2015-2025: Background and Content --- Forum lectures --- Rupestrian world heritage sites: Instability investigation and sustainable mitigation --- Subaerial landslide-generated waves: Numerical and laboratory simulations --- Rockfall occurrence and fragmentation --- Contribution from signatory organizations of the Sendai Partnerships --- International Consortium on Landslides (ICL) --- International Consortium on Landslides (ICL) - The proposing organization of the ISDR-ICL Sendai partnerships 2015-2025 --- United Nations Office for Disaster Risk Reduction (UNISDR) --- UNISDR‘s Contribution to Science and Technology for Disaster Risk Reduction and the Role of the International Consortium on Landslides (ICL) --- United Nations Educational, Scientific and Cultural Organization (UNESCO) --- UNESCO’s Contribution to the Implementation of UNISDR’s Global Initiative and ICL --- United Nations University (UNU) --- The United Nations University: Research and Policy Support for Environmental Risk Reduction --- World Meteorological Organization (WMO) --- Concerted International Efforts for Advancing Multi-Hazard Early Warning Systems --- International Council for Science (ICSU) --- On Future Challenges for the Integration of Science into International Policy Development for Landslide Disaster Risk Reduction --- World Federation of Engineering Organizations (WFEO) --- World Federation of Engineering Organizations Activities in Disaster Risk Reduction --- Disaster Prevention Research Institute (DPRI), Kyoto University --- National Civil Protection Department, Italian Presidency of the Council of Ministers, Government of Italy --- Understanding and Reducing Landslide Disaster Risk: Challenges and Opportunities for Italian Civil Protection --- Landslide Dynamics: ISDR-ICL Landslide Interactive Teaching Tools (LITT) --- Progress of the World Report on Landslides --- International Programme on Landslides (IPL): Objectives, History and List of World Centres of Excellence and IPL Projects --- UNESCO-KU-ICL UNITWIN Cooperation Programme for Landslides and Water-Related Disaster Risk Management. Landslides: Journal of the International Consortium on Landslides --- IPL Activities --- Advanced Technologies for Landslides (WCoE 2014-2017, IPL-196, IPL-198) --- Mechanisms of Landslides and Creep in Over-Consolidated Clays and Flysch (WCoE 2014-2017 --- Research on Heavy-Rainfall-Induced and Hydraulic-Driven Geological Hazards in China (WCoE 2014-2017). Landslide Risk Reduction in Croatia: Scientific research in the framework of the WCoE 2014-2017, IPL-173, IPL-184, ICL ABN --- Shapes and Mechanisms of Large-scale Landslides in Japan: Forecasting Analysis from an Inventory (WCoE 2014–2017 --- Retrospective and Prospects for Cold Regions Landslide Research (2012-2016) (WCoE 2014-2017, IPL-132, IPL-167, IPL-203, CRLN --- Large-scale Rockslide Inventories: from the Kokomeren River Basin to the Entire Central Asia Region (WCoE 2014-2017, IPL-106-2) --- Interventions for Promoting Knowledge, Innovations and Landslide Risk Management Practices within South and Southeast Asia (WCoE 2014-2017) --- Promoting a Global Standard for Community-based Landslide Early Warning Systems (WCoE 2014-2017, IPL-158, IPL-165) --- Model Policy Frameworks, Standards and Guidelines on Landslide Disaster Reduction (WCoE 2014-2017) --- Landslide Hazard and Risk Management (WCoE 2014-2017) --- Mitigation of Landslide Hazards in Ukraine under the Guidance of ICL: 2009–2016 (IPL-153, IPL-191) --- Development of a Hazard Evaluation Technique for Earthquake-Induced Landslides Based on an Analytic Hierarchy Process (AHP) (IPL-154) --- The Croatian-Japanese SATREPS Joint Research Project on Landslides (IPL-161)
    Pages: Online-Ressource (XXVI, 586 pages) , 372 illustrations, 350 illustrations in color
    ISBN: 9783319594699
    Language: English
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  • 38
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    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-07-08
    Description: The Internet connects billions of computational platforms of various sizes, from supercomputers to smart phones. However, the same types of data transmission can connect computational resources to much simpler sensors “at the edge of the net” that collect, analyze, and transmit data, as well as controllers that receive instructions. Devices deployed in the environment, homes and offices, and even our bodies would expand the number of connected devices to the trillions. This “Internet of Things” (IoT) underlies the vision of smart homes and buildings that could sense and transmit their status and respond appropriately (1), or track and report on the state of objects (vehicles, goods, or even animals) in the environment. However, the practical implementation of the IoT has been relatively slow, in part because all of these edge devices must draw electrical power from their local environment. We analyze the use of photovoltaics (PV) to power devices and help bring the IoT to fruition. Authors: Richard Haight, Wilfried Haensch, Daniel Friedman
    Keywords: Engineering
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 39
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    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-04-22
    Description: So prized by the ancient Romans were Egyptian obelisks that, at one time, more of them stood in Rome than in Egypt. In the 19th century, France, Britain, and the United States—inspired by Napoleon Bonaparte's expedition to Egypt in 1798— acquired their own major obelisks from Alexandria and Luxor. Cleopatra's Needles, by Egyptologist Bob Brier, explores the engineering challenges associated with building and erecting these massive monuments. Author: Andrew Robinson
    Keywords: Engineering
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 40
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    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-10-21
    Description: A physicist reveals the engineering marvels that underlie the modern metropolis Author: Sybil Derrible
    Keywords: Engineering
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 41
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    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-09-09
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 42
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    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-11-11
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 43
    Keywords: Engineering ; Commercial law ; Automotive engineering ; Robotics ; Automation ; Community psychology ; Environmental psychology ; Engineering ; Automotive Engineering ; Robotics and Automation ; Community and Environmental Psychology ; Commercial Law
    Description / Table of Contents: Teil I Human and Machine --- Teil II Mobilität --- Teil III Verkehr --- Teil IV Sicherheit --- Teil V Recht und Haftung --- Teil VI Akzeptanz
    Pages: Online-Ressource (XIV, 732 Seiten)
    ISBN: 9783662458549
    Language: German
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  • 44
    Unknown
    Berlin, Heidelberg : Springer Vieweg
    Keywords: Engineering ; Robotics ; Automation ; Industrial engineering ; Production engineering ; Engineering economics ; Engineering economy ; Manufacturing industries ; Machines ; Tools ; Engineering ; Industrial and Production Engineering ; Robotics and Automation ; Engineering Economics, Organization, Logistics, Marketing ; Manufacturing, Machines, Tools ; Information Systems Applications (incl. Internet)
    Description / Table of Contents: Einordnung und Hintergründe --- Positionen der Sozialpartner --- Erfahrungen und Herausforderungen in der Industrie --- Forschungsfragen und Entwicklungsstrategien --- Ausblick
    Pages: Online-Ressource (VIII, 167 Seiten) , 38 Abbildungen
    ISBN: 9783662459157
    Language: German
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  • 45
    Keywords: Engineering ; Computer simulation ; Economic theory ; Data-driven Science, Modeling and Theory Building ; Complexity ; Simulation and Modeling ; Applications of Graph Theory and Complex Networks ; Economic Theory/Quantitative Economics/Mathematical Methods
    Description / Table of Contents: Chapter 1 Financial Market --- Influence Networks in the Foreign Exchange Market --- Entropy and Transfer Entropy: The Dow Jones and the build up to the 1997 Asian Crisis --- Execution and Cancellation Lifetimes in Foreign Currency Market --- Signs of market orders and human dynamics --- Damped oscillatory behaviors in the ratios of stock market indices --- Exploring Market Making Strategy for High Frequency Trading: an Agent-based Approach --- Effect of Cancel Order on Simple Stochastic Order-Book Model --- Chapter 2 Robustness and Fragility --- Cascading failures in interdependent economic networks --- Do connections make systems robust?: a new scenario for the complexity-stability relation --- Simulation of Gross Domestic Product in International Trade Networks: Linear Gravity Transportation Model --- Analysis of Network Robustness for a Japanese Business Relation Network by Percolation Simulation.- Detectability threshold of the spectral method for graph partitioning.- Spread of Infectious Diseases with a Latent Period.-Chapter 3 Interaction and Distribution --- Geographic Dependency of Population Distribution- Spatiotemporal Analysis of Influenza Epidemics in Japan --- A Universal Lifetime Distribution for Multi-Species Systems --- Firm Age Distributions and the Decay Rate of Firm Activities --- Empirical Analysis of Firm-Dynamics on Japanese Inter-firm trade Network --- Direct participants’ behavior through the lens of transactional analysis: the case of SPEI --- Chapter 4 Traffic and Pedestrian --- Pedestrian Dynamics in Jamology --- Qualitative Methods of Validating Evacuation Behaviors --- Collective dynamics of pedestrians with no fixed destination --- Traffic Simulation of Kobe-city --- MOSAIIC: city-level agent-based traffic simulation adapted to emergency situations --- GUI for Agent Based Modeling --- Chapter 5 Social Media --- Emotional Changes in Japanese Blog Space Resulting from the 3.11 Earthquake --- Modeling of ENJYO via process of consensus formation on SNS --- A network structure of emotional interactions in an electronic bulletin board --- Scale-free network topologies with clustering similar to online social networks --- Identifying Colors of Products and Associated Personalized Recommendation Engine in e-Fashion Business
    Pages: Online-Ressource (IX, 346 pages)
    ISBN: 9783319205915
    Language: English
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  • 46
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-09-27
    Description: This viewpoint comments on recent advances in understanding the design principles of biological networks. It highlights the surprising discovery of "good-engineering" principles in biochemical circuitry that evolved by random tinkering.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Alon, U -- New York, N.Y. -- Science. 2003 Sep 26;301(5641):1866-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel 76100. urialon@weizmann.ac.il〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14512615" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biochemical Phenomena ; Biochemistry ; *Biological Evolution ; *Biology ; DNA/metabolism ; Engineering ; *Models, Biological ; Proteins/metabolism ; Signal Transduction ; Systems Theory
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 47
    Publication Date: 2003-04-26
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bhattacharjee, Yudhijit -- New York, N.Y. -- Science. 2003 Apr 25;300(5619):565.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12714717" target="_blank"〉PubMed〈/a〉
    Keywords: *Academies and Institutes ; Engineering ; *Foundations ; Institute of Medicine (U.S.) ; *National Academy of Sciences (U.S.) ; *Research Support as Topic ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 48
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-05-11
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kerr, Richard A -- New York, N.Y. -- Science. 2002 May 10;296(5570):1006-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12004100" target="_blank"〉PubMed〈/a〉
    Keywords: Engineering ; Extraterrestrial Environment ; Geological Phenomena ; Geology ; *Mars ; *Safety ; Space Flight ; *Spacecraft ; United States ; United States National Aeronautics and Space Administration ; Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 49
    ISSN: 1434-193X
    Keywords: Triplet recombination ; Electron transfer ; Radical ions ; Photochemistry ; Terpenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The triphenypyrylium tetrafluoroborate (TPT)-sensitized reactions of several terpene donor molecules, including sabinene (1), α-phellandrene (4), α-terpinene (5) and γ-terpinene (6) give rise to significantly different products than reactions induced by other electron-transfer sensitizers, such as 1,4-dicyanobenzene (DCB). The divergent reactions require decidedly different key intermediates; the products obtained with TPT can be explained by dissociative recombination of the intermediate radical-radical cation pair in the triplet state, generating donor-derived biradicals.
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  • 50
    ISSN: 1434-193X
    Keywords: Azides ; Cleavage reactions ; Cycloadditions ; Nitrogen heterocycles ; Polycycles ; Ring expansion ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---2-Alkyl-1-methylquinazolinium hexafluorophosphates 9 are deprotonated by sodium or potassium hydride to afford solutions of 2-alkylidenedihydroquinazolines 10, which were investigated by NMR spectroscopy. Trapping with methanesulfonyl azide (5a) of 10 in situ or subsequent treatment with trifluoromethanesulfonyl azide (5b) gives mixtures of colourless (15) and intensely yellow N-sulfonylimino-1,4-benzodiazepines 16 along with products due to cleavage of the exocyclic double bond of 10, viz. 11 and 13. The ethylidene compound 10b yields the bicyclic products 18 and 19, apparently by complex sequences of reactions that are triggered by removal of the acidic proton at C-2 of 16b and 16f. The structures of the products are based on spectroscopic evidence and X-ray diffraction analyses performed on 15b, 16d, 16e, and 19.
    Additional Material: 6 Ill.
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  • 51
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1589-1593 
    ISSN: 1434-193X
    Keywords: Azaallenium ions ; Azaallylium ions ; Iminium ion ; Kinetics ; Linear Free Energy Relationships ; Ab initio calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The rate constants for the reactions of the 2-azaallenium ion 1b+, the 2-azaallylium ion 2a+ and the iminium ion 3+ with different nucleophiles were determined by 1H NMR spectroscopy. By correlation with the Linear Free Enthalpy Relationship (LFER) lg k20°C = s (E + N), developed by Mayr and Patz, the electrophilicity parameters E(1b+) = -3.7, E(2a+) ≍ -16 and E(3+) = -10.43 were obtained. They show that the relative reactivities of these ions are approximately 1012:1:106. Quantum chemical calculations (ab initio, DFT) of the methyl anion affinities for the ions 1b+,2a+ and3+ are in agreement with the experimental E values. The X-ray structure of 3+·CF3SO3- is reported for the first time; it shows no strong interaction between the cation and the anion.
    Additional Material: 2 Ill.
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  • 52
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1595-1601 
    ISSN: 1434-193X
    Keywords: Oxazoline N-oxide ; Cycloadditions ; Cycloadditions ; Lactams ; Thienamycin ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---[3+2] Cycloaddition between a camphor-derived oxazoline N-oxide 9 and the γ,δ-unsaturated enamino ester 11 afforded the single adduct 6. A stereoselective reduction of the enamino ester side chain allowed the control of the absolute configuration of the two additional asymmetric centres. Nitrogen protection and oxidative hydrolysis of the resulting product 13, followed by further functional group manipulations, led to the β-lactam derivative 1, a known precursor of the β-methylthienamycin derivative2a.
    Additional Material: 1 Ill.
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  • 53
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1603-1607 
    ISSN: 1434-193X
    Keywords: Boron ; Cyclotrimerizations ; Nitrogen heterocycles ; Macrocycles ; Subphthalocyanines ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The regioselective preparation of ortho-substituted subphthalocyanides was achieved employing 3-substituted phthalonitrile derivatives as starting materials. A mechanistic proposal has been outlined.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/2000/99525_s.pdf or from the author.
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  • 54
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1609-1615 
    ISSN: 1434-193X
    Keywords: Terpenoids ; Natural products ; Total synthesis ; Cyclizations ; Rearrangements ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A new route for the synthesis of 2,7- and 7-functionalized labdanes starts from (R)-carvone (1). 11-Nordrim-7-en-9-one (15) is an appropriate starting material for the total synthesis of hispanone (21), a biologically active furolabdane isolated from the Mediterranean medicinal plant Ballota saxatilis.
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  • 55
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    Liebigs Annalen 2000 (2000), S. 1623-1626 
    ISSN: 1434-193X
    Keywords: Iridoid glucoside ; (8S)-Kingiside ; (8S)-Loganin ; (8S)-7-Ketologanin ; Asymmetric synthesis ; Natural products ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The tetraacetyl derivative 8 of the naturally occurring kingiside (8a) was prepared from aucubin (1). Intermediates in the synthesis were (8S)-tetraacetyl loganin (6) and (8S)-tetraacetyl-7-ketologanin (7), whose free (8R)-epimers occur in many different plants (Caprifoliaceae, Loganiaceae). The 13C NMR spectrum allows the structure to be unequivocally identified.
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  • 56
    ISSN: 1434-193X
    Keywords: Tetrakis(dimethylamino)naphthalenes ; Basicity ; Hydrogen bonds ; Cyclicvoltammetry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---For comparison to the recently described 2,3,6,7-tetrakis(dimethylamino)naphthalene (1) the three isomers 2,3, and 4 were synthesized. The basicities of this group of isomers are strongly dependent upon the different mutual orientations of the pairs of dimethylamino substituents: only the isomers 3 and, partially, 4, both with dimethylamino groups in adjacent peri-positions of the naphthalene, are strong “proton sponges”. For the isomers 1 and 2 with the same number and kind of twofold dimethylamino substituents in neighbouring ortho-positions, however, no significant basicity increase is observed. To explain this difference between the two groups of isomers it is suggested that in the ortho-pairs of 1 and 2 the C-N bonds diverge considerably, leading to an increased N···N distance and consequently to less stable [N···H···N]+ hydrogen bonds in contrast to the parallel C-N bonds in the peri-substituted isomers 3 and 4. X-ray crystal structure analyses of the bases and of some of the salts derived therefrom were solved and are discussed. Cyclic voltammetry indicates that 1 to 4 are strong electron donors, reacting easily to radical cations or dications which with suitable acids have been obtained as salts.
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  • 57
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    Liebigs Annalen 2000 (2000), S. 1677-1683 
    ISSN: 1434-193X
    Keywords: Radicals ; Cyclizations ; Pyridinethione ; Tetrahydrofurans ; Asymmetric synthesis ; Thiazolethione ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The trisubstituted functionalized tetrahydrofurans 10, 11, 16, 18, and 19 were photochemically prepared from 2,3-syn- and 2,3-anti-configuredN-(3-benzoyloxy-5-hexen-2-oxy)thiazole-2(3H)-thione anti-6, pyridinethiones 7, anti-8, and BrCCl3. The formation of tetrahydrofurans was achieved by an efficient and highly regioselective alkoxyl radical cyclization (5-exo-trig). The 2,3-anti substituted intermediates 9 and 12 cyclize stereoselectively whereas a 2,3-syn-configured O-radical affords both possible diastereomeric addition products in equal amounts. The cyclized tetrahydrofuryl methyl radicals were trapped with the bromine atom donor BrCCl3 to afford the bromomethyl-substituted cyclic ethers 10, 11, 18, and 19 in excellent yields. The utility of this reaction was stressed by conversion of one of the newly prepared tetrahydrofurans in a two-step synthesis into (+)-allo-muscarine (+)-20.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/2000/99590_s.pdf or from the author.
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  • 58
    ISSN: 1434-193X
    Keywords: Thioketones ; Thiocarbonyl ylides ; Cycloadditions ; Cycloreversions ; Sulfur heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Reactions of diaryl thioketones with diazomethane at room temperature afford 4,4,5,5-tetraaryl-1,3-dithiolanes; the scope of this surprising 2:1 interaction has been studied for decades (Schönberg Reaction). The clue to the mechanism was our observation that the stoichiometry is 1:1 at -78 °C, and 2,5-dihydro-2,2-diaryl-1,3,4-thiadiazoles are formed as primary [2+3] cycloadducts. They lose N2 at -45 °C in first-order reactions generating diaryl thioketone S-methylides which can be intercepted by thioketones (→1,3-dithiolanes), multiple CC bonds, or acids HX. In the absence of trapping reagents, the elusive intermediates either dimerize furnishing 2,2,3,3-tetraaryl-1,4-dithianes or give rise to 2,2-diarylthiiranes by electrocyclization. Beyond thiobenzophenone and diazomethane, our main model reaction, the studies involve fluorene-9-thione, 4,4-dimethoxy- and 4,4-dichlorothiobenzophenone. The ring of 2,5-dihydro-2,2-diphenyl-1,3,4-thiadiazole (8) is opened by LDA at -78 °C and derivatives of anion 12 are obtained. - In summa: The Schönberg reaction consists of two 1,3-dipolar cycloadditions, linked by a 1,3-dipolar cycloreversion.
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  • 59
    ISSN: 1434-193X
    Keywords: Conjugation ; Boron ; Sensors ; Cyclic voltammetry ; Polymers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---New electropolymerizable aromatic compounds (i.e. pyrrole, thiophene, aniline) bearing boronic acid and ester substituents have been synthesized and their electrochemical behavior has been investigated. Functionalized polythiophene and polypyrrole films could be anodically generated in acetonitrile, whereas the polyaniline derivative was electroformed in an acidic aqueous solution. The electrochemical responses of some of these materials were changed when fluoride ions were added to the electrolytic solutions. The strongest modifications, caused by binding of fluoride by the immobilized boron, were observed for the polypyrrole derivative in hydroorganic media.
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  • 60
    ISSN: 1434-193X
    Keywords: Heterocycles ; Zinc ; Palladium ; Catalysts ; Sulfur ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Organozinc halides derived from Grignard reagents behave differently in their reaction with ethyl (±±)-(2RS,3SR)-tetrahydro-4-methylene-2-phenyl-3-(phenylsulfonyl)furan-3-carboxylate (3) according to the hybridisation of the carbon ligand. During the development of short multi-component reactions for the synthesis of diverse functionalized ethyl 2,5-dihydrofuran-3-carboxylates it was discovered that aryl and vinyl zinc halides undergo clean reaction with 3 in the presence of Pd(PPh3)4. In contrast, when alkyl zinc halides are reacted with 3 in the presence of Pd(PPh3)4, reductive desulfonation of 3 is observed. Remarkably, in the absence of a transition metal catalyst, the allylic substitution of 3 with alkyl zinc halides proceeds cleanly and in moderate to good yield.
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  • 61
    ISSN: 1434-193X
    Keywords: Self-assembly ; Vapor-pressure osmometry ; Resorcin[4]arenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Resorcin[4]arene tetracarboxylic acids 5,6 (A) and resorcin[4]arene tetrapyridines 2,3 (P) self-assemble in chloroform solution to form stable heterotopic AP dimers. Data from NMR titration and dilution experiments, as well as from vapor-pressure osmometry (VPO), indicate that the AP dimer is formed with an association constant greater than 107 M-1. Solid-solution extraction experiments are indicative of the formation of a 2:1 trimer (A2P), while self-associated homotopic species (A2 and A3) can be detected by NMR and VPO. Analysis of the heterotopic noncovalent assembly process over a range of compositions shows that these other species are much less stable than the AP heterodimer, which is the exclusive species at an A/P concentration ratio of 1:1 (〉 99.7% of the total at 10 mM).
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  • 62
    ISSN: 1434-193X
    Keywords: Sulfoxides ; β-Amino sulfones ; Mannich type reaction ; Lithium perchlorate ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The LiClO4-mediated one-pot reaction of aldehydes with (trimethylsilyl)dialkyl amines and the lithium salt of sulfoxides or sulfones, affords the corresponding β-(dialkylamino) sulfoxides and β-(dialkylamino) sulfones in high yields. The aminosulfoxidation reaction of aliphatic or aromatic aldehydes lacks diastereoselectivity, but the diastereomeric sulfoxides can be separated by HPLC or column chromatography for further use.
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  • 63
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    Liebigs Annalen 2000 (2000), S. 1741-1744 
    ISSN: 1434-193X
    Keywords: Bridged pyranose derivatives ; Ring enlargement ; Carbenes ; Glycosides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Addition of dichlorocarbene to the glycal (±±)-2 followed by cyclopropyl-allyl rearrangement leads to the chloro-2H-pyran (±±)-4. Oxidation of (±±)-4 and reduction of the obtained hydroxypyranone (±±)-5 gave the methyl pyranoside (±±)-6. The relative configuration of (±±)-6 was established by X-ray structural analysis of the corresponding acetate (±±)-7. The synthesis of the optically active starting materials (+)-2 and (-)-2 is also reported.
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  • 64
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    Liebigs Annalen 2000 (2000), S. 1745-1758 
    ISSN: 1434-193X
    Keywords: CMP-Neu5Ac analogues ; Enzyme inhibitors ; Substrate analogues ; Transition state analogues ; Transferases ; Carbohydrates ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Quinic acid was transformed into phosphitamides 16, 25, and 36, which could be readily linked to 5′-O-unprotected cytidine derivative 17. Ensuing oxidation of the obtained phosphite triesters with tBuO2H and hydrogenolytic de-O-benzylation furnished the corresponding phosphate diesters 18, 26, and 38. Base catalyzed removal of acetyl protecting groups, and methyl ester hydrolysis furnished CMP-Neu5Ac analogues 1d, 1e, and 2. Quinic acid was also transformed into 1,2-unsaturated diallyl α-hydroxymethyl-phosphate derivatives (R)- and (S)-46, which on reaction with cytidine phosphitamide 47 afforded the phosphite triesters. Subsequent oxidation with tBuO2H and then treatment with NEt3 gave phosphate diester derivatives (R)- and (S)-48. Deallylation, acetyl group removal, and methyl ester hydrolysis furnished (R)- and (S)-3, respectively. Treatment of (R)- and (S)-48 with DBU as a base led to acetic acid elimination, thus yielding, after de-O-allylation, acetyl group cleavage, and ester hydrolysis, diene derivative (E)-4. Donor substrate analogues 1d and 1e exhibited good α(2-6)-sialyltransferase inhibition (Ki: 2.0·10-4 and 2.0·10-5 M). However, transition state analogues (R)-, and particularly (S)-3 showed excellent inhibition properties (Ki: 1.6·10-6 and 2.7·10-7 M).
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  • 65
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    Liebigs Annalen 2000 (2000), S. 1759-1765 
    ISSN: 1434-193X
    Keywords: Cyclitols ; Aminocyclitols ; Glycosidase inhibitors ; α-Mannosidase inhibitors ; Deoxygenation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Three deoxy derivatives 2-4 of the α-mannosidase inhibitor mannostatin A (1) were synthesized, and their inhibition of Jack bean α-mannosidase was evaluated in order to elucidate the roles of each of the three hydroxyl groups of the inhibitor. The 1- and 2-deoxy derivatives 2 and 3 retained some inhibitory activity, although reduced by a factor of about 100 relative to the parent, whereas it was completely lost with the 3-deoxy derivative 4. Structure and activity relationships are discussed in the light of these findings.
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  • 66
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    Liebigs Annalen 2000 (2000), S. 1767-1772 
    ISSN: 1434-193X
    Keywords: Circular dichroism ; Conformation analysis ; s-Triazines ; Chiral auxiliaries ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---CD data of the optically pure 2-[(R)-1-(9-anthryl)ethylamino]-4-chloro-6-[(R)-1-(1-naphthyl)ethylamino]-1,3,5-triazine, 2[(R)-1-(9-anthryl)ethylamino]-4,6-bis[(R)-1-(1-naphthyl)ethylamino]-1,3,5-triazine, 2,4-bis[(R)-1-(9-anthryl)ethylamino]-6-chloro-1,3,5-triazine are presented. The analysis of the CD spectra by means of the nonempirical DeVoe approach has afforded the complete conformational characterisation of the three s-triazine derivatives, allowing us to establish how the conformation of these derivatives depends on the nature of the substituent 1-arylethylamino groups.
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  • 67
    ISSN: 1434-193X
    Keywords: Cycloadditions ; Carbenes ; Nitrones ; Nitrilimines ; Pyrazolines ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The reaction of tert-butylalkynyl chromium Fischer carbene complex 1 with nitrones 2 affords β-enamino-ketoaldehydes 4 by the light-promoted rearrangement of the corresponding [3+2] cycloadduct carbene complexes 3. On the other hand, [3+2] cycloaddition of chiral nonracemic Fischer alkenyl carbene complexes 19 with nitrilimines 10 yields enantiomerically pure Δ2-pyrazolines with high regio- and diastereoselectivity.
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  • 68
    ISSN: 1434-193X
    Keywords: Asymmetric synthesis ; Zinc ; Transition structures ; QM/MM computations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Trimethylsilyl substitutions of the fenchyl alcohols [(1R,2R,4S)-exo-(2-Ar)-1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol, Ar = 2-methoxyphenyl (1) and Ar = 2-(dimethylaminomethyl)phenyl (2)] yield the chiral ligands 3 [Ar = 2-methoxy-3-(trimethylsilyl)phenyl] and 4 [Ar = 2-(dimethylaminomethyl)3-(trimethylsilyl)phenyl]. Increased reactivities and enantioselectivities in diethylzinc additions to benzaldehyde are obtained from 3 (63% ee R) and 4 (93% ee S), relative to 1 (26% ee S) and 2 (73% ee S). X-ray crystal structures of 3 and of its methylzinc complex 3-Zn reveal out-of-plane bending of the methoxy groups as major geometrical consequences of the trimethylsilyl substitutions. Analyses of QM/MM ONIOM μ-O transition-structure models for 1, 2, 3, and 4 show that trimethylsilyl-induced distortions of methoxy and of dimethylaminomethyl groups explain the observed increased enantioselectivities.
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  • 69
    ISSN: 1434-193X
    Keywords: Palladium ; exo-π-Allylpalladium complexes ; Allylic alkylation ; Spiro compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The palladium(0)-catalyzed alkylation of 2,3-bis(acetoxymethyl)bicyclo[2.2.1]hepta-2,5-diene 1 with malonate-type enolates as nucleophiles is investigated. A monoalkylated product is formed first, and undergoes (depending on the nucleophile used) a second intramolecular reaction leading to spirocyclopropane-annulated bicyclo[2.2.1]heptene derivatives 5. The formation of endo spirobicyclic cyclopropanes adducts as major isomer is rationalized by assuming formation of an intermediate exo-(π-allyl)palladium complex.
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  • 70
    ISSN: 1434-193X
    Keywords: Ketones ; Reductions ; Micelles ; Cobalt ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Operationally simple and environmentally benign procedures have been developed to selectively reduce different α,β-unsaturated ketones, 4,4-dimethylcyclohex-2-ene-1-one (1), isophorone (2), benzylideneacetone (3), chalcone (4) by NaBH4 or by the system NaBH4 + CoCl2. Alternative reaction media to the extensively used MeOH have been explored, and new procedures take advantage of the acceleration and chemoselectivity induced by water or by aqueous micellar solutions. It was possible to selectively and quantitatively afford pure products of 1,2 and of 1,4 reduction as well as the totally reduced compounds (yield and selectivity 〉 90%) by simple changes in the experimental conditions.
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  • 71
    ISSN: 1434-193X
    Keywords: C-Glycosides ; Conformation analysis ; Molecular dynamics ; Selectins ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The conformational behavior of the C-glycosyl analogue of sialyl-α-(2→3)-galactose, synthesized as a glycosidase inhibitor, has been studied using a combination of NMR spectroscopy (J and NOE data) and molecular dynamics calculations. The obtained results show that the population distribution of conformers with respect to the orientation about the pseudo-glycosidic linkages is mainly controlled by steric interactions. This is in contrast to findings made for O-glycosides. In these natural compounds, the conformational behavior about the glycosidic linkage Φ is mainly governed by the exo-anomeric effect.
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  • 72
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    Liebigs Annalen 2000 (2000), S. 1815-1820 
    ISSN: 1434-193X
    Keywords: Asymmetric synthesis ; Palladium-catalysed couplings ; Palladacycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Chiral C2-symmetric N-benzylazetidines have been conveniently prepared from optically pure anti-1,3-diols without loss of enantiomeric purity. N-Debenzylation led to the corresponding N-unsubstituted azetidines, which were then subjected to palladium-catalysed coupling reactions with aryl bromides to afford chiral N-arylazetidines. (R,R)-N-Benzyl-2,4-dimethylazetidine has been employed in the synthesis of a new cyclopalladated complex, which can be used, for instance, as a chiral recognition agent for phosphorus ligands.
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  • 73
    ISSN: 1434-193X
    Keywords: Cyclizations ; Spiro compounds ; Nucleosides ; Isomerizations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Syntheses of the spiro nucleosides 2′-deoxyhydantocidin 3a and its 1′-epimer 3b are described. The newly developed route involves a Horner-Wadsworth-Emmons condensation of the phosphonate 16 with the erythrose derivative 15 affording a mixture of six isomers which was fully assigned by NMR spectroscopy. The mixture was directly converted into the final compounds in an efficient base-catalyzed cyclization reaction. A base-catalyzed interconversion between the two isomers was observed.
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  • 74
    ISSN: 1434-193X
    Keywords: Benzodiazepines ; Heterocycles ; Azeto[1,2-a]-1,5-benzodiazepines ; Cyclizations ; Cycloadditions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The reaction of o-phenylenediamine (4) with one, two or three equivalents of p-substituted 3-dimethylaminopropiophenone hydrochlorides 5a-e was studied. 4-Aryl-2,3-dihydro-1H-1,5-benzodiazepine derivatives 6a-e were obtained in good yields, along with the 1:2-adducts 7c-e and the unexpected 1:3-adducts rac-8c-e. The type of adduct formed is determined by the molar ratio of the reactants 4 and 5 and by the nature of the substituent in the para position of the propiophenone 5.
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  • 75
    ISSN: 1434-193X
    Keywords: Cup-shaped PAHs ; Host-guest compounds ; Host-guest chemistry ; Cyclizations ; Semiempirical calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Cyclotrimerisation of benzo-polycyclic bromostannylalkenes 8a-d with Cu(NO3)2·3H2O in THF affords benzotri(benzonorbornadienes) 3a-d as a mixture of the syn and anti isomers. The ratio of syn to anti is close to the 1:3 statistical value in most cases (i.e. in cyclotrimers 3a,b,d), but highly in favour of the anti isomer in 3c, where steric hindrance by the methoxy groups plays an important role in the stereochemistry of the cyclotrimerisation. The substrates for the cyclotrimerisation, i.e. the bromostannyl alkenes 8a-d, were prepared from bromoalkenes 7a-d by treatment with base (LDA) and quenching with trimethyltin chloride. In turn, bromoalkenes 7a-d were prepared from alkenes 5a-d by radical bromination-elimination. The reaction conditions used were designed to minimise Wagner-Meerwein rearrangements that would lead to unwanted bromo isomers. The cup-shaped syn cyclotrimers 3a-d exhibit high electron density within the cavity as determined by AM1 semiempirical calculations of their electrostatic potential surfaces and are valuable substrates for supramolecular chemistry. As an example, it is shown that fullerene C60 is drawn into solution in acetonitrile by complexation with both the syn and anti trimer of benzonorbornadiene 3a.
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  • 76
    ISSN: 1434-193X
    Keywords: Carbene complexes ; Enamines ; Metallatrienes ; Cyclopentadienes ; Dihydropyrroles ; spiro-Tetrahydropyrroles ; Iminium carbonylmetalates ; Dimetallapolyenes ; Tungsten ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Reactions of the [(1-alkynyl)carbene]tungsten complex (CO)5W=C(OEt)C≡CPh (1) with 1-aminocyclohexenes 2a-c and 7a-c afford different types of products depending on the amino substituents and the reaction conditions. (4-Aminocyclobutenyl)carbene complexes B have been shown to be generated in the first reaction step through a [2+2] cycloaddition. These are key intermediates and afford cross-conjugated tungstatrienes E, (conjugated) 1-tungsta-1,3,5-hexatrienes G, or (non-conjugated) 1-tungsta-1,3,6-heptatrienes F by following competing reaction pathways. Cross-conjugated 1-tungstatrienes 3 have been isolated in 52-74% yield by performing the reactions of 1-aminobenzocyclohexenes 2a-c with compound 1 in pentane. In dichloromethane instead of pentane, (conjugated) 1-tungsta-1,3,5-hexatrienes 4 are obtained, which subse-quently undergo fragmentation to give cyclopentadienes 6 (by π-cyclization) and dihydropyrroles (by α-cyclization) in a molar ratio dependent on the nature of the amino substituents. (Non-conjugated) 1-tungsta-1,3,6-heptatrienes 10 are generated upon reaction of 1-aminocyclohexenes 7a-c with compounds 1, which are transformed into cyclopentadienes 12 via conjugated 1-tungsta-1,3,5-hexatrienes 9 as intermediates. Reactions of 1-tungsta-1,3,6-heptatrienes 10 with the (1-alkynyl)carbene complex 1 afford dinuclear compounds 14, which subsequently yield indenes 15 (by two successive π-cyclization steps) and spiro-tetrahydropyrroles 16 (by both a π-cyclization and an α-cyclization step), depending on the steric bulk of the amino substituent.
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  • 77
    ISSN: 1434-193X
    Keywords: Allyl alcohols ; Organocerium reagents ; Alkenes ; Addition reactions ; Cerium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Alkylcerium reagents add to the multiple bonds of allyl and propargyl alcohols in good yields and under mild conditions. The double bond can be reduced with lithium aluminum hydride in the presence of cerium trichloride. The regiochemistry of the attack depends on electronic factors.
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  • 78
    ISSN: 1434-193X
    Keywords: Amidines ; Chiral bases ; N-Acyliminium ions ; Enantioselective catalysis ; Chiral pool ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The synthesis of four enantiopure hydroxyamidines is described. One amidine was obtained from (S)-pyroglutamic acid. Its key step involved the addition of phenylmagnesium bromide to the corresponding ester, affording the tertiary alcohol without detectable racemization. The second amidine was obtained by coupling of an (S)-malic acid derived N-acyliminium ion with β-naphthol. The other amidines were obtained from an (S)-serine-derived imide which was reduced to two diastereomeric lactams that were eventually transformed into the corresponding amidines.
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  • 79
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 155-163 
    ISSN: 1434-193X
    Keywords: Macrocycles ; Cyclizations ; Strained compounds ; Ketophosphonate ; Iodoalkyne ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Two strategies have been explored to build the highly strained eleven-membered ring 2, a potential precursor for the biosynthetic key intermediate of the protoilludane family: an intramolecular Horner-Wadsworth-Emmons olefination and an intramolecular Nozaki-Hiyama-Kishi type-ring closure.
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  • 80
    ISSN: 1434-193X
    Keywords: Neutral anion receptor ; Hydrogen bonds ; Urea moieties ; Donor-acceptor systems ; Macrocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The synthesis of macrocyclic and acyclic cleft-like anion receptors in which four hydrogen bond donating urea moieties are present in a preorganized fashion is described. NMR spectroscopy shows the complex formation with H2PO4- and Cl -. Cleft-like receptors bind H2PO4- in a 2:1 guest-host stoichiometry (Ka = 107M-2) in DMSO, whereas Cl - is bound in a 1:1 stoichiometry (Ka = 103M-1). The macrocyclic receptors form a 1:1 complex with H2PO4- (Ka = 103M-1 in DMSO) with a 100-fold selectivity for H2PO4- over Cl -.
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  • 81
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 193-198 
    ISSN: 1434-193X
    Keywords: Nucleophilic substitutions ; Azulenes ; Hydroxylation ; Amination ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Hydroxylation of azulenes with tert-butylhydroperoxide proceeds efficiently at the 6-position when the former contain electron-withdrawing substituents in the five-membered ring. Similarly, VNS amination of azulenes proceeds with 4-amino-1,2,4-triazole; its anion, being an active nucleophile, also reacts with unsubstituted azulene. A variety of transformations of 6-hydroxyazulenes, such as substitution of the corresponding sulfonates with nitrogen, oxygen, sulfur, carbon nucleophiles and halogens, and the Claisen rearrangement of allylic ethers, is reported.
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  • 82
    ISSN: 1434-193X
    Keywords: Heterocycles ; Carbohydrates ; Imidazolidines ; Oxazolidines ; Spiro compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Prochiral 1,3-dihydroxyacetone forms racemic oxazolidine- and oxazoline-type spiro[4.4]nonanes upon reactions with potassium (thio)cyanate and cyanamide. In contrast, 1,3-diaminoacetone yields only the corresponding spiro-bisimidazolidinethione under similar conditions together with monocyclic by-products, but the spiro-bisimidazolidinone is accessible by reaction of 1,3-dichloroacetone with urea. The resolution of the racemic spiro-bisoxazolidinethione 2a was achieved by using brucine as the resolving agent.
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  • 83
    ISSN: 1434-193X
    Keywords: Homogeneous catalysis ; Palladium ; Acetoxylation ; Acryloxylation ; Addition reactions ; Cyclooctadiene ; Cyclooct-4-enone ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Palladium-catalyzed acryloxylation of several cycloalkenes in the presence of the Pd(OAc)2/p-benzoquinone/MnO2 catalytic system is reported. This oxidation reaction yields allylic acrylates as the sole products through the intermediacy of an η3-allyl complex. However, with 1,5-cyclooctadiene (3), cyclooct-4-enone (4) is the major reaction product. Its formation results from oxidation, which is also observed in the palladium-catalyzed acetoxylation of 3. It has been shown that this is the result of a 1,2-trans addition (acryloxy-palladation), followed by a β-hydride elimination, which yields an enol acrylate or acetate. A second Markovnikov-oriented 1,2-trans-acryloxy-palladation on the latter yields a palladium complex, rearrangement of which gives 4.
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  • 84
    ISSN: 1434-193X
    Keywords: Amino acids ; coupling ; N-Substituted amide ; Cyclizations ; Cyclic dipeptides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A short synthesis of new, functionalized seven-membered ring cyclic dipeptides is described. After the coupling of N-protected β-amino acids to N-substituted α-amino tert-butyl esters, the protective groups of the terminal functions were removed and the cyclization took place diastereoselectively in the presence of the coupling agent BOP. Amide substitution was found to be effective in promoting the cyclization of linear dipeptides.
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  • 85
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 275-280 
    ISSN: 1434-193X
    Keywords: Radical reactions ; Substituent effects ; Nitrogen heterocycles ; Dihydropyridines ; Pyrrolines ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A set of allene-tethered benzoyloximes (5) has been treated with nBu3SnH. Depending on their substitution pattern, a wide range of compounds has been obtained. If the stannyl radical adds on the allene, the C-centred radical thus formed undergoes either a 5-exo ring closure to give the cyclopentene derivatives 7 or a 6-endo ring closure onto the N atom to give the dihydropyridines 8. If the stannyl radical adds on the benzoyl moiety, an iminyl radical is formed which leads to the 3H-pyrroles 9 and the alkylidene-pyrrolines 10. Steric effects as well as polar effects are the factors governing the reaction course.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/2000/99373_s.pdf or from the author.
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  • 86
    ISSN: 1434-193X
    Keywords: Antibiotics ; Configuration determination ; Heterocycles ; Hongoquercin A ; Terpenoids ; Total synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---(±)-Hongoquercin A (1), the racemate of an antibacterial fungal metabolite, has been synthesized starting from geranylacetone (2) and ethyl orsellinate (ethyl 2,4-dihydroxy-6-methylbenzoate, 5). The structure (±)-1 has been confirmed by X-ray analysis of its ethyl ester (±)-10. Synthesis of the naturally occurring (+)-hongoquercin A from (-)-sclareol (11) established its configuration as depicted in 1.
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  • 87
    ISSN: 1434-193X
    Keywords: Carbohydrates ; Amino sugars ; Protecting groups ; Glycosylations ; Trichloroacetimidates ; Oligosaccharides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The N-DMM-Protected lactosamine derivative 2 was readily transformed into the corresponding glycosyl donor 4 and into acceptor 5. A TMSOTf-catalyzed glycosidation afforded the derived tetrasaccharide 6 which led to glycosyl donor 9. Reaction of 9 with lactose derivative 10 as acceptor gave the desired hexasaccharide 11. Cleavage of all protective groups and N-acetylation afforded the target molecule 1b (lacto-N-neohexaose). Glycosylation of acceptor 10 with donor 4 furnished tetrasaccharide 16 which, employing standard procedures, gave acceptor 18. Glycosylation of 18 with donor 9 furnished, under standard conditions, octasaccharide 19. Cleavage of all protective groups and N-acetylation afforded the target molecule 1c (lacto-N-neooctaose). Both 1b and 1c were obtained in good overall yields.
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  • 88
    ISSN: 1434-193X
    Keywords: Sharpless asymmetric dihydroxylation ; Asimilobin ; Tetrahydrofuran ring ; Wittig reactions ; Annonaceous acetogenins ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The most efficient method for the synthesis of the trans/threo/trans-bis(tetrahydrofuran) (THF) ring unit was established, and the first total synthesis of (-)-asimilobin and its diastereomer was then accomplished in twelve and fourteen steps, respectively, from trans-1,5,9-decatriene, by a convergent route with a Wittig reaction as the key step. By virtue of these synthetic results, the absolute configuration of the bis(THF) unit in naturally occurring asimilobin should be corrected.
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  • 89
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 381-385 
    ISSN: 1434-193X
    Keywords: Enynes ; Macrocycles ; Coordination chemistry ; Crown compounds ; Radicals ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The complex molecular structure and interesting activation mechanisms of naturally occurring enediynes have inspired the synthesis of a variety of simpler model systems to mimic their properties. While in most model compounds nucleophilic attack, isomerization or bioreduction are used to activate the unsaturated system for diradical cyclization, some attempts have been made to employ metal-ion coordination for this purpose. Significant enhancement of the thermal reactivity has been achieved by metal-ion induced conformational and electronic changes of suitably substituted enediynes, such as 1, 5, 6, 17 and 18. Enediyne activation by stoichiometric or catalytic formation of vinylidene complexes, such as 22, from terminal alkynes has also been investigated. This paper summarizes recent results pursuing the activation of enediyne diradical cyclization by metal ions.
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  • 90
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 419-423 
    ISSN: 1434-193X
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The first enantioselective synthesis of enantiomerically pure (-)-wine lactone, (-)-1a, a fragrance constituent of various white wines, and its epimer (+)-1b, was carried out. The key steps are allylic substitution of (±)-2-cyclohexen-1-yl acetate (2) with dimethylmalonate using palladium complexes of phosphanyldihydrooxazol L1 or of the phosphanylcarboxylic acid L2 as catalyst, subsequent decarboxylation, iodolactonization and elimination, furnishing enantiomerically pure bicyclic lactone (+)-7 in 47% overall yield. The diastereoselective introduction of methyl groups by SN2′-type substitution with an organocopper compound and by enolate alkylation gave lactone (-)-1a in 43% overall yield from (+)-7.
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  • 91
    ISSN: 1434-193X
    Keywords: Aplykurodins ; Marine steroids ; C-C coupling ; Cyclic peroxides ; Lactonization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---An approach to the synthesis of aplykurodins, ichthyotoxic marine lactones, is presented. The carbon framework was derived from vitamin D3 by conversion of the readily accessible allyl alcohol 13 to the protected Grundmann's hydroxy ketone 22 and subsequent introduction of the C2 side chain through a Pd0-promoted coupling. Highly stereoselective hetero Diels-Alder reaction with O21 produced the key intermediate peroxide 25. Functional group transformations, coupled with a series of chemo- and stereoselective reactions, finally resulted in the synthesis of the unnatural analogue 17,18-dihydro-3,9-di-epi-aplykurodinone B (6).
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  • 92
    ISSN: 1434-193X
    Keywords: Zeolites ; Radical ions ; Ring opening ; Electron transfer ; Oxidations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Incorporation of trans-1,2-diphenylcyclopropane (1) and its 3,3-D2-isotopomer into the channels of a redox-active pentasil zeolite (Na-ZSM-5) resulted in the formation of exo,exo-1,3-diphenylallyl radical (2•) and its 2-D1 isotopomer, respectively. This conversion requires oxidation, ring opening, and deprotonation, in an unspecified sequence. The allyl radical 2• is also formed upon incorporation of trans-1,3-diphenylpropene (3). A comparison with the solution photochemistry, in the presence or absence of added base, shows the conversion of 1 into 2• to be a zeolite-specific reaction. Incorporation of arylcyclopropanes 9 (R = H, OCH3) into ZSM-5 generated trans-propenylbenzene radical cations 10•+ (R = H, OCH3); the 2,2-D2 isotopomer of 9 (R = OCH3) gave rise to three different isotopomers of 10•+ (R = OCH3).
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  • 93
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 485-490 
    ISSN: 1434-193X
    Keywords: Calixarenes ; Tripodal cryptand ; Extraction abilities ; Cations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The tripodal calixcryptands have been one of the scarcely explored fields in calixarene chemistry due to the difficulties in their preparation. The strategy presented in this paper shows that novel tripodal calixcryptands can be conveniently prepared by directly treacing p-tert-butylcalix[n]arenes (n = 4, 6) with a multi-functional polypode reagent, e.g. 1,1,1-tris(tosyloxyethoxyethoxymethyl)propane or tetrakis(tosyloxyethoxyethoxymethyl)methane, under selected conditions. The first example of 1,2,4-tripodal calix[6]cryptands has been prepared. Novel calix[6]crown and doublecalix[4]arenes were co-prepared. The extraction abilities of these novel calixcryptands toward several alkali metal ions, ammonium and alkylammonium ions are presented.
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  • 94
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 521-525 
    ISSN: 1434-193X
    Keywords: Allyl aryl sulfones ; Nitroarenes ; Condensation reaction ; Lewis acids ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Allyl aryl sulfones 2 react with aryl nitrocompounds 1 in a DBU/MgCl2 system giving the 4-arylsulfonyl quinolines 3. Some mechanistic aspects of the reaction are discussed. Application of this reaction to the formal total synthesis of the natural product (-)Eupolauramine is described.
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  • 95
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    Liebigs Annalen 2000 (2000), S. 527-538 
    ISSN: 1434-193X
    Keywords: Furans ; Pyrans ; Dihydropyran-2-ylidenes ; Ring closure ; Addition reaction ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---On treatment with base the pentynones 8a-f undergo anionic addition reactions of the resulting enolate species to the alkyne moiety and afford the 2,5-disubstituted furans 10a-f in yields ranging from 10-91%. The proposed mechanism involves the 2-methylene-dihydrofurans 11 as intermediates which tautomerize to yield the observed products. In the case of the α-picolyl derivative 8g both possible enolates 12 and 13 are formed which are subsequently transformed to the products 10g and 14g, respectively. Starting with the hexynones 9a-e an analogous reaction takes place with the formation of the pyran derivatives 15 and 16 in comparable yields. Under the same reaction conditions the n-butyl ketone 9f gives rise to two isomeric compounds, namely the 4H-pyran 16f and the cyclohexenone 17. This result is explained by assuming initial formation of two isomeric enolates which react either by O- or C-attack on the carbon-carbon triple bond.
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  • 96
    ISSN: 1434-193X
    Keywords: Alkylations ; Deaminated AdoHcy ; Decarboxylated AdoHcy ; Mitsunobu reaction ; Nucleosides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---5′-Acetylthio-5′-deoxy-2′,3′-O-isopropylideneadenosine (8) was directly prepared from commercially available 2′,3′-O-isopropylideneadenosine (7) and thioacetic acid under Mitsunobu conditions in almost quantitative yield. In situ cleavage of the acetylthio function of 8 followed by coupling with different alkyl bromides proceeded with high yields. Deprotection of the obtained 5′-thionucleosides yielded the S-adenosyl-L-homocysteine analogues decarboxylated AdoHcy (11), deaminated AdoHcy (14) and 5′-[3-(cyano)propylthio]-5′-deoxyadenosine (16) in good overall yields. Direct deprotection of the thionucleoside 8 delivered 5′-thio-5′-deoxyadenosine (18) in excellent yield. In addition, binding constants of these AdoHcy analogues and the DNA methyltransferase M·HhaI were determined in a fluorescence assay.
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  • 97
    ISSN: 1434-193X
    Keywords: Amino ketones ; Homogeneous catalysis ; Aziridination ; Copper ; Enols ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A series of acyclic and cyclic enol derivatives 1 has been transformed into the corresponding α-amino-functionalized ketones 2 by means of enantioselective catalytic aziridination with chiral Cu complexes, prepared in situ from [Cu(MeCN)4]PF6 and the optically active ligands 3, by using (N-tosylimino)iodobenzene (PhINTs) as a nitrogen source. The best enantioselectivities (ee values of up to 52%) have been achieved for the electronically deactivated enol acetate 1aδ, but the incorporation of steric bulk and the substitution pattern at the enol double bond do not improve the ee values. The cyclic substrates react considerably less readily (only up to 45% conversion) compared to their acyclic counterparts (complete consumption). A transition structure is suggested for the asymmetric Cu-catalyzed aziridination of the enol acetate 1aδ in the presence of the chiral ligand 3b that could account for the sense of the (R)-configured product 2a.
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  • 98
    ISSN: 1434-193X
    Keywords: Porphyrins ; Chiral auxiliaries ; Macrocycles ; Pyrethroids ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Esters, N,N-disubstituted amides, and a N-acylurea derived from the enantiopure industrial intermediate (1R)-cis-hemicaronaldehydic acid (or biocartol) are convenient synthons for the preparation of a series of chiroporphyrins by condensation with pyrrole. These chiral meso-tetracyclopropylporphyrins are obtained exclusively as the D2-symmetric α,β,α,β atropisomer, generally in low to moderate yields (2-20%), and in the urea case in excellent yield (60%). Hydrolysis of the urea substituents affords a chiroporphyrin with mono-N-substituted amide groups. 1H-NMR spectroscopy indicates that the ester, amide, and urea stereogenic groups sit on the porphyrin close to the metal binding site and restrict substrate or ligand access along a C2-symmetric groove. This structural feature of chiroporphyrins and of their metal complexes is of high potential interest in asymmetric catalysis and chiral recognition.
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  • 99
    ISSN: 1434-193X
    Keywords: Cyclophanes ; Molecular recognition ; Molecular shuttles ; Rotaxanes ; Template-directed synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Two dumbbell-shaped compounds (8 and 11), each composed of two polyether chains intercepted by a 1,4-dioxybenzene recognition site, terminated by tetraarylmethane-based stoppers, and emanating from a central 9,10- or a 2,6-dioxyanthracene unit, have been synthesized. Two [2]rotaxanes (9 · 4 PF6 and 12 · 4 PF6) have been prepared by interlocking these dumbbell-shaped compounds (8 and 11) with a bipyridinium-based tetracationic cyclophane (15 · 4 PF6) - namely, cyclobis(paraquat-p-phenylene). A [3]rotaxane (10 · 8 PF6) incorporating two cyclophane components (15 · 4 PF6) was also obtained when the 9,10-dioxyanthracene-containing dumbbell-shaped compound (8) incorporating two 1,4-dioxybenzene recognition sites was employed. The 1H-NMR spectroscopic investigation of the [2]rotaxanes (9 · 4 PF6 and 12 · 4PF6) revealed that the cyclophane component encircles one of the two 1,4-dioxybenzene recognition sites in the 9,10-dioxyanthracene-containing [2]rotaxane (9 · 4 PF6) and the 2,6-dioxyanthracene unit in the other [2]rotaxane (12 · 4 PF6). These structures have been confirmed by UV/Vis and electrochemical experiments. Comparison with the spectroscopic properties of simple model compounds shows the presence of electronic interactions which lead to (i) the occurrence of very efficient energy transfer processes in the dumbbell-shaped components and (ii) perturbations in the absorption spectra with appearance of two charge-transfer absorption bands and complete luminescence quenching in the [2]rotaxanes. For the 2,6-dioxyanthracene-containing [2]rotaxane (12 · 4 PF6), it has been demonstrated that the cyclophane can be displaced from the dioxyanthracene to the 1,4-dioxybenzene station upon electrochemical oxidation.
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  • 100
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 627-631 
    ISSN: 1434-193X
    Keywords: Complex nucleoside ; Antibiotics ; Radicals ; Zn-Cu couple ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Homosinefungin 5, which can be considered as an analogue of S-adenosylmethionine (SAM) and of S-adenosylhomocysteine (SAH), has been synthesized by means of a sequence in which the key step was the addition of a radical, produced by the simple treatment of an iodide precursor with a zinc-copper couple, to suitably activated olefins.
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