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1.
2.
Auguet C. Martorell F. Moll F. Torra V: 《Journal of Thermal Analysis and Calorimetry》2002,70(1):277-290
The miniaturized calorimetric devices furnish a reduced working flat surface and permits measurements with extremely low-mass
quantities. The experimental sensitivity shows relevant position dependence with x-y surface coordinates and with z-distance. The device identification is realized via a 2-D model based in Fourier general equation.
Using the Marquardt method the experimental flat surface device can be identified and the fitted parameters used to simulate
the behavior of the experimental system. From the model, the effects of several dissipation configurations can be evaluated.
Also, via the RC-analogy, a way to 3-D experimental devices is roughly described.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
Cornelia Bohne Adelaide Faljoni-Alario Giuseppe Cilento 《Photochemistry and photobiology》1988,48(3):341-347
Abstract— The interaction of serum albumin-bound acceptors with enzyme-generated and protected triplet species was studied in two types of systems. Chlorophyll-a bound to bovine and human serum albumins is efficiently excited by enzymatically generated triplet acetone and acetaldehyde. When the Chl-a concentration is much lower than that of the albumin the interaction occurs with chlorophyll in an aggregate in which one Chl-a is surrounded by several protein molecules. When the Chl-a concentration is higher than that of the protein, the aggregate contains the proteins and fluorescent chlorophylls in a 1:1 ratio. The excess chlorophylls, although able to interact with the donors, are not fluorescent.
In another study, probes bound to various specific sites of serum albumins were used as quenchers of the enzymatically generated triplet acetone. The efficiency of quenching by all the bound probes is equal and in one case even stronger than for the free probes.
A model for the interaction of the excited species contained in the enzyme with the acceptor(s) located in the protein is proposed.
The present results provide further evidence that enzyme-generated and protected triplet carbonyl species can interact through a collisional process with acceptors bound to or constituents of macromolecules. 相似文献
In another study, probes bound to various specific sites of serum albumins were used as quenchers of the enzymatically generated triplet acetone. The efficiency of quenching by all the bound probes is equal and in one case even stronger than for the free probes.
A model for the interaction of the excited species contained in the enzyme with the acceptor(s) located in the protein is proposed.
The present results provide further evidence that enzyme-generated and protected triplet carbonyl species can interact through a collisional process with acceptors bound to or constituents of macromolecules. 相似文献
4.
5.
Computer applications in chemical industry are outlined and the CARSA system (computer-assisted research in synthesis and application) is described. This modular system consists of the three main parts: WIFODATA (data base; substance and finding documentation), QSAR (programs for quantitative structure/activity relationships) and RDSS (reaction design by synthon substitution; program package for planning of syntheses). The vital RDSS component is discussed in more detail; the underlying philosophy is explained, and examples are given from practical work. Some future steps towards a real molecular-design system are outlined. 相似文献
6.
C. Auguet J. L. Seguin F. Martorell F. Moll V. Torra J. Lerchner 《Journal of Thermal Analysis and Calorimetry》2006,86(2):521-529
Micro-calorimetric
devices using Si-based sensors are very useful for the study of gas–solid
reactions, in which very low mass of reactants are necessary. But in fact
the consequence of using flat detectors is an increase of the uncertainty
in the measured energy. In this work a calorimetric gas sensor based on Xensor
chip is analysed studying the local x–y
contributions of dissipation to the sensitivity related to the value in the
centre. We study also the effects of the gas-flow on the sensitivity, comparing
the results obtained with two Xensor type chips. Finally we carry out a deeper
analysis of the x–y effects on the
calorimetric detector for dissipations in the reactant shell extremely close
to the detector surface to visualize the link between the power density distribution
and the output signal. 相似文献
7.
Wolfgang A. Herrmann Cornelia Weber Manfred L. Ziegler Orhan Serhadli 《Journal of organometallic chemistry》1985,297(2):245-254
The diazoolefines of composition N2CCR2 (R/R = CH3/CH3 and(-CH2-)5) are suitable precursors of the corresponding vinylidene ligands CCR2. Thus, treatment of the RhRh complex [(η5-C5Me5)Rh(μ-CO)]2 (1) with the N-nitrosourethanes 2a and 2b, resp., in the presence of lithium t-butoxide yields the otherwise inaccessible μ-vinylidene complexes (μ-CCR2)[(η5-C5Me5)Rh(CO)]2 (R = CH3 (3a), R,R = (-CH2-)5 (3b)). The analogous cobalt compound (μ-CCMe2)[(η5-C5Me5)Co(CO)]2 (5a) is obtained similarly. This procedure extends the well-documented diazoalkane method for the synthesis of μ-alkylidene complexes to the less stable diazoalkenes. A single-crystal X-ray diffraction study of the dimethylvinylidene derivative 3a shows the CMe2 ligand to adopt an almost symmetrically metal-bridging position (d(RhC) 197.8(1) and 204.3(1) pm), with a rhodium-rhodium single bond completing a three-membered Rh2C-metallacycle (d(RhRh) 268.4(0) pm) analogous with cyclopropane. 相似文献
8.
The parallel between orbital first and second electric moments and statistical first and second central moments is noted. Three measures of orbital spatial distribution in terms of their moments are proposed, and applied to the LMO's in a series of ten-electron hydrides. Consistent differences between bond and lone pair distributions are found. Using the statistical interpretation, for each LMO an effective solid angle around the central atom is postulated. 相似文献
9.
Torsten Meyer Thomas Hellweg Stefan Spange Stephanie Hesse Christian Jger Cornelia Bellmann 《Journal of polymer science. Part A, Polymer chemistry》2002,40(18):3144-3152
Polyvinylamine hydrogels with silica particles encapsulated (PVAm/silica) were produced by a two‐step synthesis. In the first step, polyvinylformamide/silica (PVFA/silica) hybrids were synthesized from vinylformamide (VFA) and 1,3‐divinylimidazolidin‐2‐one (1,3‐bisvinylethyleneurea, BVU), as the crosslinker, by radical copolymerization in silica/water suspensions using different compositions of VFA/BVU. The target product PVAm/silica was obtained by acidic hydrolysis of the PVFA/silica hydrogels in a second step. The chemical structures of both hydrogels, PVFA/silica and PVAm/silica, respectively, were revealed by solid‐state 13C(1H) cross‐polarity/magic‐angle spinning NMR spectroscopy. Both hydrogels swelled significantly in water. The swelling capacity of the two systems was characterized by the correlation length ξ (or hydrodynamic blob size) of the network meshes with small‐angle neutron scattering experiments. ξ is significantly larger for PVAm/silica than for PVFA/silica, which corresponds to the observed higher swelling capacity of this polyelectrolyte material. Furthermore, the swelling behavior of the hybrid hydrogels was quantitatively described in terms of free swell capacity, centrifuge‐retention capacity, adsorption against pressure, and free swell rate as compared with values of the corresponding copolymer hydrogels. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3144–3152, 2002 相似文献
10.
Kristin fischer Stefan Spange Steffen Fischer Cornelia Bellmann Jörg Adams 《Cellulose (London, England)》2002,9(1):31-40
The surface polarity of native celluloses has been investigated by the following solvatochromic dyes: dicyano-bis (1,10)-phenanthroline iron (II) Fe(phen)2 (CN)2 (1), bis(4-N,N-dimethylamino)-benzophenone (2), and cou-marine 153 (3). Linear Solvation Energy (LSE) relationships and the UV/Vis data have been used to characterize the surface polarity of different native cellulose batches in terms of the empirical Kamlet–Taft polarity parameters (hydrogen bond acidity), (hydrogen bond basicity), and * (dipolarity/polarizability). , , *and calculated Reichardt's E T (30) values are reported for various native and regenerated cellulose samples with different degrees of crystallinity. The degree of crystallinity of the cellulose samples has been determined by X-ray. The microcrystalline environment of cellulose can be exactly parameterized in terms of the , and *values. It shows a fairly strong acidity and a low dipolarity/polarizability. For the amorphous sections smaller and larger * values are observed. The correspondence of the empirical polarity parameters determined has been discussed in relation to results from pyrene fluorescence and zetapotential measurements. 相似文献