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101.
In similarity with the strongly electrophilic BPSEs and despite its more electron-rich character, 1-phenylsulfinyl-2-phenylsulfanylethylene (SOSE) reacts with nucleophiles with displacement of the phenylthio moiety. Specifically it reacts with diols under basic conditions to produce β-cycloacetalic sulfoxides. The reaction has been amply developed in carbohydrate chemistry. 相似文献
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103.
Júlio C. Fabris 《General Relativity and Gravitation》1994,26(2):135-147
We study some consequences of the generalized Maxwell-Einstein system in higher dimensions. This generalization is such that the Maxwell-type field constructed in an evenn-dimensional space-time preserves the conformal invariance. After dimensional reduction to four dimensions, it gives rise to scalar, electromagnetic and Kalb-Ramond fields. Specifically, we analyse here some compactification processes, including the stability of the final configuration (forn=8), and anisotropic cosmological solutions (forn=6).On leave of absence from: Departamento de Física e Química, Universidade Federal do Espírito Santo, Goiabeiras, Vitória CEP 29000, Espírito Santo, Brazil 相似文献
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105.
Giovanni Candiano Gian Marco Ghiggeri Gerolamo Delfino Carlo Queirolo Fabrizio Ginevri 《Analytica chimica acta》1986
A typical product (glycosyl lysine) formed by reaction of lysine with glyceraldehyde is measured at 490 nm after coupling with diazotized sulfanilic acid. Reaction with 4-dimethylaminobenzaldehyde was less satisfactory. 相似文献
106.
The equations governing the response of hysteretic systems to sinusoidal forces, which are memory dependent in the classical phase space, can be given as a vector field over a suitable phase space with increased dimension. Hence, the stationary response can be studied with the aids of classical tools of nonlinear dynamics, as for example the Poincaré map. The particular system studied in the paper, based on hysteretic Masing rules, allows the reduction of the dimension of the phase space and the implementation of efficient algorithms. The paper summarises results on one degree of freedom systems and concentrates on a two degree of freedom system as the prototype of many degree of freedom systems. This system has been chosen to be in 1:3 internal resonance situation. Depending on the energy dissipation of the elements restoring force, the response may be more or less complex. The periodic response, described by frequency response curves for various levels of excitation intensity, is highly complex. The coupling produces a strong modification of the response around the first mode resonance, whereas it is negligible around the second mode. Quasi-periodic motion starts bifurcating for sufficiently high values of the excitation intensity; windows of periodic motions are embedded in the dominion of the quasi-periodic motion, as consequence of a locking frequency phenomenon. 相似文献
107.
Electrodes/Electrolyte Interfaces in the Presence of a Surface‐Modified Photopolymer Electrolyte: Application in Dye‐Sensitized Solar Cells 下载免费PDF全文
Dr. Adriano Sacco Federico Bella Stefano De La Pierre Dr. Micaela Castellino Dr. Stefano Bianco Prof. Roberta Bongiovanni Prof. Candido Fabrizio Pirri 《Chemphyschem》2015,16(5):960-969
Since hundreds of studies on photoanodes and cathodes show that the electrode/electrolyte interfaces represent a key aspect at the base of dye‐sensitized solar cell (DSSC) performances, it is reported here that these interfaces can be managed by a smart design of the spatial composition of quasi‐solid electrolytes. By means of a cheap, rapid, and green process of photoinduced polymerization, composition‐tailored polymer electrolyte membranes (PEMs) with siloxane‐enriched surfaces are prepared, and their properties are thoroughly described. When assembled in DSSCs, the interfacial action promoted by the composition‐tailored PEMs enhances the photocurrent and fill factor values, thus increasing the global photovoltaic conversion efficiency with respect to the non‐modified PEMs. Moreover, the presence of the siloxane‐chain‐enriched surface increases the hydrophobicity and reduces the water vapor permeation into the device, thus enhancing the cell′s durability. 相似文献
108.
Abstract. Active control of oscillations of a suspended cable under transversal wind, described by a constant term and a fluctuating turbulent component, is dealt with. Control of transversal in-plane and out-of-plane oscillations is performed by imposing a longitudinal motion to one support; the control law depends, linearly or quadratically, on measures of displacement and velocity of a selected point. First, the steady-state oscillations around the planar static configuration, determined by the wind constant component, under sinusoidal in-plane and out-of-plane loading are studied, showing the nonlinear behaviour in the regions of primary and parametric resonance and the effects of the control action. Afterwards, attention is focused on the response of the cable to transversal wind turbulence, whose fluctuating component is described by a random process with an assigned spectral density. The effectiveness of longitudinal control is analysed by means of numerical investigations.Sommario. Si analizza il controllo attivo delle oscillazioni di un cavo sospeso, sottoposto all'azione di un vento agente in direzione ortogonale al piano del cavo e descritto mediante un termine di carico costante ed una componente variabile di turbolenza. Il controllo delle oscillazioni piane e spaziali viene realizzato mediante spostamento longitudinale di uno degli appoggi; la legge di controllo dipende linearmente o quadraticamente da misure di spostamento e velocità di un punto prescelto. In una prima fase, vengono studiate le oscillazioni stazionarie sotto carichi sinusoidali agenti rispettivamente nel piano e fuori del piano del cavo, intorno alla configurazione di equilibrio statico determinata dalla presenza della componente costante del vento, mostrando il comportamento nonlineare nelle regioni di risonanza primaria e parametrica e gli effetti dell'azione di controllo. Successivamente, si focalizza l'attenzione sulla risposta del cavo alla componente trasversale di turbolenza del vento, la quale è descritta da un processo stocastico a media nulla con densità spettrale assegnata. L'efficacia del controllo viene analizzata attraverso un'indagine numerica. 相似文献
109.
Analytical and experimental investigations are performed in order to characterize the dynamic behaviour of a non-smooth rotational oscillator, which exhibits multiple discontinuity boundaries in the phase space. The physical system consists of a rotating body subjected to an elastic restoring force and in contact with one or two rough discs rotating with constant driving velocities. The presence of multiple discontinuity boundaries caused by frictional contacts leads to non-standard bifurcations that are studied by means of a simple mechanical model.A test set-up has then been built to investigate the correctness of modelling of the friction force and the validity of the proposed model for technical applications: the experimental measurements qualitatively and quantitatively capture the basic scenarios anticipated by the model while a strong robustness of the phenomena pointed out by the theoretical analyses has been revealed in the experiments. 相似文献
110.