419 research outputs found
Dynamic covalent chemistry on surfaces employing highly reactive cyclopentadienyl moieties
No full textSilicon substrates coated with a bromide-terminated silane are transformed into highly reactive, cyclopentadiene covered analogues. These surfaces undergo rapid cycloaddition reactions with various dienophile-capped polymers. Mild heating of the substrates causes the retro-Diels-Alder reaction to occur, thus reforming the reactive cyclopentadiene surface, generating an efficiently switchable surface
Fritz Schumacher & Heinrich Tessenow: Architecture, an Art or a Craft?
No full textThis booklet contains the inaugural lectures of Fritz Schumacher and Heinrich Tessenow given on the occasion of their appointment respectively as professors at the Technical University in Dresden and The Art Academy in Dresden.The lectures provide novel insights into their understanding of architecture and into their proposals for reform of architectural education. they are proceeded by an introductory essay of the guest editor architectural historian Hartmut Frank.History, Form & Aesthetic
Sociedades modernas, sociedades de obsolescência: a sociologia temporal de Hartmut Rosa / Modern societies, obsolescence societies: Hartmut Rosa's temporal sociology
No full textResenha de: ROSA, Hartmut. Aceleração: a transformação das estruturas temporais na modernidade. São Paulo: Editora Unesp, 2019. Centrado na revisitação da modernidade a partir de uma perspectiva temporal, Hartmut Rosa sustenta o conceito de aceleração social como aspecto fundante do projeto moderno. Explorando diferentes variáveis causais para o conceito da aceleração social, a resenha examina as transformações das instituições morais, valorativas e políticas ocorridas ao longo do desenvolvimento histórico da modernidade como episódios induzidos pela obsolescência. Sendo esta um produto de campos de ação crescentemente cambiantes e acelerados, o autor mobiliza esse conceito para fundamentar inédita proposta de diferenciação entre a modernidade e a modernidade tardia como momentos históricos calcados em diferentes níveis de compressão espaço-temporal, estabilidade institucional e temporalização de projetos individuais e coletivos de futuro.***AbstractCentered on revisiting modernity from a temporal perspective, Hartmut Rosa supports the concept of social acceleration as a fundamental aspect of the modern project. Exploring different causal variables for the concept of social acceleration, the review examines the transformations of moral, valuative and political institutions that occurred during the historical development of modernity as episodes induced by obsolescence. As this is a product of increasingly changing and accelerated fields of action, the author mobilizes this concept to substantiate an unprecedented proposal for differentiation between modernity and late modernity as historical moments based on different levels of space-time compression, institutional stability and temporalization of individual and collective future projects
Surveying silk fibre degradation by crystallinity determination: a study on the Tang-Dynasty silk treasure from Famen Temple, China
No full textWhen Chinese archaeologists opened an unknown vault under the collapsed pagoda of Famen Temple near Xian (Shaanxi Province, NW China) in 1987, they found a vast amount of valuable silk textiles. The degraded textiles were part of a treasure comprising hundreds of artifacts deposited by Tang dynasty (ad 618–907) emperors as a gift to the temple. Run as a bilateral German-Chinese project, the Roemisch-Germanisches Zentralmuseum Mainz established a textile conservation laboratory in Shaanxi´s provincial capital Xian in 2001, joining numerous other laboratories that have existed there since the early 1990s.This preliminary study represents part of an ongoing investigation programme that accompanies the conservation work. The Tang dynasty silk is generally in a very poor state of preservation as a result of its long burial period. Large sections have only survived as an amorphous brown mass of fibre debris. Some parts are better preserved, however, offering the unique opportunity to study the whole range of degradation stages on ancient silks.This preliminary scientific investigation focuses on the determination of the silk fibres’ crystallinity and its relation to the ageing process. As we know from modern material, silk is mainly crystalline, albeit in a somewhat amorphous state. The methods of investigation used were X-ray diffraction (XRD) using synchrotron radiation, which is a new way to determine crystallinity of ancient silk fibres; and polarized Fourier transform infrared spectroscopy (FTIR) for the determination of crystallite orientation. Both methods were specifically devised to gain information on small single fibres
Selbstorganisierende, hochkristalline Dünnschichten als innovative Materialplattform mit hohem Anwendungspotential
No full textClusters /
No full textIncludes bibliographies and index.Metal-metal multiple bonds in dinuclear clusters / F. A. Cotton, R. A. Walton -- Developments in transition metal cluster chemistry / G. Schmid -- Spectroscopic properties of the quasi one-dimensional tetracyanoplatinate (II) compounds / G. Gliemann, H. Yersin
Spektroskopisches Verhalten kristalliner Tetracyanoplatinate mit quasi eindimensionaler Struktur
No full textThe emission behavior of some tetracyano-platinates is discussed. The emission and the absorption energies follow an 1/R³ law (R is the Pt-Pt-distance). A correlation between the energy levels of the complex ions in solution and the solid state bands is pointed out
Polarisations-spektralphotometrische Untersuchungen in Emission und Absorption an [Cr urea₆] J₃-Einkristallen
No full textEs wurden Polarisationsspektren von {Cr[OC(NH₂)₂]₆} J₃-Mikrokristallen in Emission und Absorption bis herab zu 7 K im Bereich der im Roten liegenden scharfen Interkombinationsübergänge vermessen. Diese stellen elektrische Dipolübergänge dar. Die beiden auf der kurzwelligen Seite der Emission auftretenden Hauptübergänge bei 6995 Å und bei 7029 Å sind Null-Null-Übergänge. Sie können den ²Eg-Folgetermen Γ₅, Γ₆ und Γ₄ (in D'₃) zugeordnet werden. Es zeigen sich deutliche Hinweise auf eine Mischung zwischen dem oberen ²Eg-Folgeterm Γ₄ und einem ⁴A₁ (⁴T₂g)-Folgeterm. Es werden qualitative Aussagen über Deaktivierungsmechanismen beim [Cr urea₆] J₃ gemacht
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