662 research outputs found
Undulators and free-electron lasers
No full textThis book is a reference text for all those working in free-electron laser research as well as being a learning aid for physicists and graduate students who wish an introduction to this field. Only a basic understanding of relativistic mechanics and electromagnetism is presupposed. After an overview of early developments and general principles of operation, the different models that can be used to describe free-electron lasers are presented, organized according to their range of applicability. The relevent conceptual and mathematical constructs are built up from first principles with attention to obtaining the practically important results in a simple but rigorous way. Interaction of the undulator with the driving electron accelerator and the laser cavity and design of undulator magnets are treated and an overview is given of some typical experiments
Rezension: Motz, Markus: Englisch oder Deutsch in Internationalen Studiengängen?
No full textBrandl H. Rezension: Motz, Markus: Englisch oder Deutsch in Internationalen Studiengängen? Info DaF. 2006;(2-3):230-235
Modified finite-difference approximations near the singularitiy in the problem of motz
No full textA simple, modified finite-difference method is described for solving Laplace's equation with boundary singularities of the infinite derivative type. Modified approximations for the derivatives of the Laplacian equation are employed near the singularity. These are developed from a truncated series form of the local analytical solution. The method is applied to the problem of Motz. The numerical results compare favourably with those obtained by other techniques
First Row Transition Metal Aminopyridinates – the Missing Complexes
No full textLithiated 4-methyl-2-[(trimethylsilyl)amino]pyridine (Ap(TMS)H) undergoes a salt metathesis reaction with [SCCl(3)(thf)(3)] and FeCl(3), at low temperature in thf, to yield the homoleptic complexes [Sc(Ap(TMS))(3)] (1) and [Fe(Ap(TMS))(3)] (2). An analogous reaction with MnCl(2), CoCl(2) and FeCl(2) using two equivalents of 4-tert-butylpyridine (tBuPy) as additional donor ligand affords the structurally analogous cis complexes [Mn(Ap(TMS))(2)(tBuPy)(2)] (3), [Co(Ap(TMS))(2)(tBuPy)(2)] (4) and [Fe(Ap(TMS))(2)(tBuPy)(2)] (5). If FeCl(3), is used without tBuPy, the highly symmetric trinuclear complex [Fe(3)(Ap(TMS))((6)Li(2)O] (6) is obtained. Furthermore, the use of ZnCl(2) in a reaction with lithiated Ap(TMS)H yields the dimeric complex [Zn(Ap(TMS))(4)] (7) in which two Ap(TMS) ligands bridge the two metals. All complexes have been characterised by X-ray crystal structure analysis. To the best of our knowledge, complexes 1 and 2 and 5 are the first scandium and iron aminopyridinates, respectively, and complex 3 is the first manganese aminopyridinate complex which contains no additional anionic ligand. Complexes 4 and 7 are rare examples of cobalt and zinc aminopyridinates. This study proves that aminopyridinato ligands are highly universal ligands since they are able to stabilize early and late transition metals. Aminopyridinates of every first row transition metal are now available. The magnetic properties of all paramagnetic complexes were investigated. All complexes are high-spin complexes and the trinuclear iron complex 6 exhibits a weak antiferromagnetic coupling. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)Deutsche Forschungsgerneinschaft (DFG
Is heart rate variability an objective parameter with which to manage treatment of infants with heart failure due to left-to-right shunting?
No full textTreatment in heart failure could be guided by additional non-clinical measures, such as neurohumoral levels. Variability in heart rate is known to reflect neurohumoral stimulation. With this in mind, we sought to assess retrospectively the variability in heart rate to guide the treatment of infants in heart failure. We analysed retrospectively the data from 20 infants with a significant left-to-right shunt. All were unsuitable for cardiac surgery or interventional therapy at the time the treatment had commenced. None of the infants improved while receiving diuretics, spironolactone, and digoxin alone, but improved after the addition of propanolol or metoprolol. None of the infants had problems during or after the subsequent operation. Parasympathetic activity reflected by parameters of variability in heart rate, such as the square root of adjacent RR-intervals, and the amount of adjacent RR-Intervals greater than 50 milliseconds, improved in nearly all infants during beta blockade. On the other hand, parameters of variability in heart rate reflecting sympathetic activity did not change. Parasympathetic activity reflected the clinical state of nearly all the infants. These parameters, therefore, seem to be a good non-clinical parameter, showing the optimal treatment for heart failure in an ambulatory setting
Synthesis of hybrid organic-inorganic polymer
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Química, Florianópolis, 2014.O desenvolvimento de novas tecnologias e equipamentos na área de engenharia exige a adaptação dos materiais hoje empregados ou criação de novas matérias primas capazes de suportar os mais diversos ambientes e condições. Durante anos a engenharia química e de materiais vem estudando os materiais inorgânicos como moléculas precursoras com o intuito de obter, após tratamento térmico, fibras ou cerâmicas de alta performance, dotadas de características químicas e térmicas inalcançáveis com outros materiais. Materiais cerâmicos são destinados à aplicações bastante nobres na área aeroespacial e automotiva devido ao elevado custo dos compostos empregados em sua obtenção.Com o objetivo de produzir materiais com características melhoradas, aumentando assim o leque de aplicações e ao mesmo tempo reduzir os custos de produção, buscou-se introduzir moléculas orgânicas ao processo de síntese. A inserção de compostos orgânicos permite a inclusão de funções orgânicas, melhora as propriedades químicas, permite o uso de menores quantidades de material inorgânico e diversifica a área de aplicações. Até o presente momento, diversos autores sintetizaram novos compostos híbridos orgânico-inorgânicos através de rotas sintéticas variadas. Neste trabalho foram utilizados precursores inorgânicos comerciais e o monômero orgânico estireno através de duas grandes rotas sintéticas, polimerização em solução via radicais livres e hidrossililação assistida por catalisador metálico com adição de iniciador radicalar.Produtos com diferentes características foram sintetizados por ambas as técnicas. Ambas as técnica utilizadas mostraram-se adequadas para a obtenção de um polímero híbrido com as características desejadas. O híbrido orgânico-inorgânico sintetizado apresentou elevada estabilidade térmica resultando em um alto grau de ceramização, caracterizando-o assim como um bom material precursor para cerâmicas.Abstract : The development of new technologies and equipment in engineering area forces the improvement of materials used nowadays or the conception of new with capability to be applied in different environments and conditions. Along years chemical and material engineers have been studying inorganic materials as precursor molecules intending to obtain, after thermal treatment, high performance fibers and ceramics, with singular chemical and thermic characteristics obtained only by these materials. Ceramic materials are applied in noble applications like aerospace and automotive due to the high aggregate value of raw material.A promising material with improved characteristics, to increase the range of applications and decrease production costs, is the combination of organic molecules and preceramic compounds in a synthesis process. The addition of organic compounds allows the inclusion of organic functions, improves chemical properties, reduces the amount of inorganic material and diversifies the application area. Nowadays several authors have synthesized new hybrid organic - inorganic compounds by numerous synthetic routes. In this work commercial inorganic precursors and organic styrene monomer were reacted by two synthetic routes, solution polymerization with free radical initiator and hydrosilylation assisted by metal catalyst with the subsequent addition of free radical initiator.Products with different characteristics were synthesized using polymerization by free radical initiator and hydrosilylation followed by radical initiator addition. Both techniques revealed to be satisfactory to obtain a hybrid polymer with improved characteristics. The new organic-inorganic hybrid materials synthesized showed high thermal stability resulting in a high ceramic yield, characterizing it as a good precursor material for ceramics
Intermittent high glucose enhances apoptosis related to oxidative stress in human umbilical vein endothelial cells: the role of protein kinase C and NAD(P)H-oxidase activation
No full textClippings from The newsweekly. (1995 June 6)
No full textHeadline: USA's Achenbach is state champ! Area Rotarians raise funds for Oklahoma City. Obituaries: Mera (Neuman) Johnson, Clara E. Gettel, Carl Fiebig, Mabel M. Tobias, Elton H. Motz, Janet Roberts, Evelyn V. Richard
Thinking the unthinkable: Facing maternal abuse.
No full textThis paper describes how the radical concept of maternal perversion first presented by Estela Welldon (1988) informs the psychotherapeutic assessment and treatment of female inpatients within forensic services and of women in the community who commit acts of violence. It presents a model of the psychology of female violence that the author describes as 'crimes against the body'. The paper offers clinical evidence for Welldon's model of female perversion in forensic settings and provides an extended clinical illustration of psychotherapeutic work, when the therapist was pregnant, with a woman who killed her child
Synthesis of fluorine-modified polysilazanes via Si-H bonds activation and their application as protective hydrophobic coatings
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Química, Florianópolis, 2017Uma nova rota para a síntese de polissilazanos fluoro-modificados para aplicações de revestimentos protetores com hidrofobicidade aumentada e excelente resistência química foi desenvolvida pela reação do oligossilazano liquido Durazane® 1800, disponível comercialmente, e o álcool fluorado 2,2,2-trifluoroetanol (TFE), utilizando fluoreto de tetrabutilamônio (TBAF) como catalisador seletivo na ativação dos grupos Si-H e sua posterior reação simultânea com grupos N-H e O-H. Borohidreto de Cálcio (Ca(BH4)2· 2THF) foi utilizado como inibidor da reação, a fim de se obter um polissilazano fluorado em estado sólido e solúvel, ideal para aplicação como revestimento em substratos metálicos pela técnica de revestimento por imersão. O mecanismo de reação proposto assim como a estrutura polimérica resultante foram investigadas pelas analises de espectroscopia de RMN (1H e13C), espectroscopia por transformada de Fourier (FTIR), GPC, GC, XPS e análise elementar. Os grupos Si-H e Si-N não reagidos do polímero reagem posteriormente com a superfície do substrato, resultando em uma excelente adesão, enquanto os grupos CF3 provenientes do material fluorado diminuem os valores de energia livre superficial, aumentando o Angulo de contato para gotas de agua em aprox. 15 % e para hexadecano em até 40 %, em comparação com revestimentos baseados em polissilazanos sem modificações. Além disso, a resistência química dos revestimentos fluorados em contato com soluções ácidas e básicas (HCl e KOH) foi consideravelmente aumentada, oferecendo um grande potencial para proteção contra corrosão, especialmente em metais.Abstract: A new route to synthesize fluorine-modified polysilazanes for coating applications with improved hydrophobicity and excellent chemical resistance was developed by the reaction of the commercially available liquid oligosilazane Durazane® 1800 and the fluorinated alcohol 2,2,2- trifluoroethanol (TFE) using tetra-n-butylammoniumfluoride (TBAF) as selective catalyst to activate Si-H groups for simultaneous selective reactions with both N-H and O-H groups. Calcium borohydride (Ca(BH4)2·2THF) was used as reaction inhibitor, to terminate the reaction to receive a solid, soluble fluorinated polysilazane, which is suitable to coat metal substrates via simple dip-coating technique. The proposed reaction mechanisms and the resulting polymer structures confirm the attachment of the fluorinated groups on the polysilazane backbone, were investigated with 1H, 13C NMR, FTIR, XPS spectroscopy, GPC, GC and elemental analysis. It was also demonstrated that the absence of catalyst leads only to the expected decomposition of the silazane by the alcohol. Whereas the remaining silazane Si-H and Si-N bonds provide for an excellent adhesion of the coatings to the substrate, the CF3 groups decrease the surface energy leading to an increased contact angle of up to 15 % and 40 % to water and hexadecane, respectively, in comparison to fluorine-free polysilazane coatings. When tested as mold release coatings, the F- modified silazanes reduced the adhesion of a phenolic resin with an aluminum substrate from 12.7 to 2.8 MPa. Moreover, the chemical resistance of the fluorine-modified polysilazanes based coatings in contact with acids and bases (HCl and KOH) is remarkably improved, offering a great potential to protect especially metals from corrosion
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