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131.
Ilana Abayev Arie Zaban Vladimir G. Kytin Alexey A. Danilin Germà Garcia-Belmonte Juan Bisquert 《Journal of Solid State Electrochemistry》2007,11(5):647-653
Results on the density of sates of nanostructured TiO2 as a function of particle size and temperature are reported. In TiO2 nanoparticles with a mean diameter 10 nm, the density of states (DOS) is strongly temperature-dependent, indicating a rearrangement
of the bandgap states in which the exponential energy parameter (width of the distribution) increases from 0.080 to 50 °C.
For nanoparticles with mean diameters of 20 and 30 nm the DOS is much closer to an exponential distribution, and is much less
sensitive to temperature variations. It is suggested that nanometer confinement has a significant influence on the density
of electronic states for 10-nm particles, while band tailing is similar to that occurring in bulk semiconductors for the larger
particles.
相似文献
Juan BisquertEmail: |
132.
The approach of studying structural and dynamical properties of flexible molecules is of substantial interest, as it allows decoding the shapes and intrinsic properties of isolated molecular constituents, which have an influence on the selectivity and functionality in biological processes. Combining quantum computation methods with double resonance or infrared hole burning techniques, mainly covering hydride stretch vibrations, recently led to great progress in understanding the structure of a variety of biological building blocks. Measurements of spectra in the lower frequency range, with relatively compact and convenient laser sources, still pose major challenges. For this reason, the method of ionization-loss stimulated Raman spectroscopy (ILSRS) has been developed and applied for monitoring the spectral features of the 2-phenylethanol prototype. The bands observed in the Raman spectra of its two conformers uniquely identify their structures and are in accord with anharmonic results obtained by density functional theory calculations. These findings point to future opportunities for ILSRS as a powerful conformational probe and set new standards for detailed interrogation of structure and intra- and inter-molecular interactions. 相似文献
133.
Laser-based spectroscopies coupled with molecular beam techniques facilitated the monitoring of H fragments released in ultraviolet photodissociation of pre-excited isoenergetic vibrational levels of pyrrole. Most noticeably, there was an order of magnitude larger reactivity for an eigenstate primarily consisting of two quanta of ring deformation than for another with one quantum of symmetric C-H stretch. The dynamics, the intramolecular interactions controlling the energy flow, and the mode-selectivity within a medium-sized, ten atom molecule, is discussed. 相似文献
134.
A mixture of Fe(AcAc)(2) and Co(AcAC)(2) was thermolyzed in a closed cell under the autogenic pressure of the reactants. The nature of the products was temperature dependent. The reaction is a one-stage, simple, efficient, and solvent-free method to prepare FeCo alloy nanoparticles protected by a carbon shell. Particle sizes of 60-150 were obtained covered by a carbon layer of 3-4 nm. The air stability of these particles is also demonstrated. 相似文献
135.
Ilya Kuselman Ilana Schumacher Francesca Pennecchi Cathy Burns Aleš Fajgelj Paolo de Zorzi 《Accreditation and quality assurance》2011,16(12):615-622
A metrological approach for investigating out-of-specification (OOS) test results in long-term stability study of drug products
was used. It is shown that OOS test results can indicate an actual change in a measured property of a product or be metrologically
related with a certain confidence probability, i.e., be caused by the measurement problems, while the product still meets
the quality requirements at the time of testing. As examples, results of testing sodium chloride injections in 500-mL plastic
containers and of epinephrine (l-adrenaline) injections in 1-mL ampoules were discussed. Regression analysis of the data was performed, as well as warning
and action lines for shelf life of the products calculated for relevant measurement uncertainties and confidence probabilities.
Producer’s and consumer’s risks of the established shelf life values were also estimated. 相似文献
136.
Perelshtein I Applerot G Perkas N Grinblat J Gedanken A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(15):4575-4582
Titanium oxide (TiO(2)) nanoparticles (NPs) in their two forms, anatase and rutile, were synthesized and deposited onto the surface of cotton fabrics by using ultrasonic irradiation. The structure and morphology of the nanoparticles were analyzed by using characterization methods such as XRD, TEM, STEM, and EDS. The antimicrobial activities of the TiO(2)-cotton composites were tested against Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) strains, as well as against Candida albicans. Significant antimicrobial effect was observed, mainly against Staphylococcus aureus. In addition, the combination of visible light and TiO(2) NPs showed enhanced antimicrobial activity. 相似文献
137.
Asymmetric synthesis of (-)-[9]helicene, as well as preparation of its lower homologues, completes the series of carbon-sulfur [5]-, [7]-, [9]-, and [11]helicenes. Spectroscopic and electrochemical studies of this series provide an absorption onset-based band gap, E(g) = 3.40 eV, for a cross-conjugated (C(2)S)(n) helix; this value may be compared to E(g) = 3.59 eV obtained from TD-DFT computed excitation energies for a series of dimethyl-substituted [n]helicenes (n ≤ 31). 相似文献
138.
Alexandra Chapsky Osnat Melamed Dalia Galron Hava M. Golan Ilana Bar 《Journal of Raman spectroscopy : JRS》2012,43(8):1083-1088
A novel approach using micro‐Raman spectroscopy for the detection of alteration of global DNA methylation levels in human individuals with polymorphism in the methlyenetetrahydrofolate reductase (MTHFR) gene was tested. Comparison of measured Raman spectra from samples with wild type genotype to those with polymorphism (homozygous and heterozygous ) in the MTHFR gene revealed that the intensity of the ~ 2945 cm–1 peak, representing C–H stretches in the DNA constituents and in the methyl group is sample dependent. The intensity ratios between the area of these peaks in the different samples and the peaks at 1667 cm–1 were used to assess the extent of methylation, allowing classification of the DNA samples for the common MTHFR polymorphism, MTHFR 677 C > T. These results suggest that improvement of the identification capabilities of Raman spectroscopy for DNA methylation can contribute to disease diagnosis and to a better understanding of the physical and biomolecular processes related to epigenetic regulation of the genome. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
139.
Arijit Basu Ilana Veprinsky‐Zuzulia Mira Levinman Yoav Barkan Jacob Golenser Abraham J. Domb 《Macromolecular rapid communications》2016,37(3):251-256
PEG400 (polyethylene glycol, MW 400) biscyanoacrylate is synthesized and copolymerized with 2‐octyl cyanoacrylate for potential use as bioadhesive. PEG400 biscyanoacrylate is synthesized from the esterification of anthracenyl cyanoacrylic acid where the anthracene unit serves as vinyl‐protecting group. Copolymerization increases the plasticity, mechanical strength, and resilience of the resulted polymer as determined by dynamic mechanical analysis. Peeling test confirms its superior bioadhesive properties. Surface morphology is characterized by SEM imaging. The formulations are cytocompatible and safe. This cyanoacrylate composition may provide improved bioadhesive cyanoacrylates.