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61.
Tauber MJ Kelley RF Giaimo JM Rybtchinski B Wasielewski MR 《Journal of the American Chemical Society》2006,128(6):1782-1783
We have carried out room-temperature, solution-phase electron paramagnetic resonance and electron-nuclear double resonance studies on a series of radical anions based upon perylene-3,4:9,10-bis(dicarboximide) (PDI). The following systems were studied: two PDI monomers, a covalent, cofacial dimer, and two covalent trefoil-PDI3 molecules, one of which self-assembles into pi-stacked dimers. Full sharing of the unpaired electron in the covalent and self-assembled dimers is revealed by a halving of the hyperfine coupling constants in these species, relative to those of the monomers. These results and the electronic absorption spectra show that electron hopping on a >107 Hz time scale occurs between a reduced and neutral chromophoric pair. 相似文献
62.
K.V. Jovan Jose 《Molecular physics》2015,113(19-20):3057-3066
We present the first implementation of the evaluation Raman spectra of large molecules using the molecules-in-molecules (MIM) fragment-based method (MIM-Raman). Molecular fragments and associated overlapping subsystems are constructed by cutting the C–C bonds in the large molecule based on the connectivity information and a number-based fragmentation scheme. After saturating the dangling bonds with hydrogen link-atoms, independent energy and Raman frequency calculations are performed on each subsystem. Subsequently, link-atom-related forces, Hessian and polarisability derivative matrix elements are projected back onto the corresponding host and supporting atoms through the Jacobian projection method. In the two-layer model (MIM2), the long-range interactions, absent in the single layer model (MIM1), are taken into account through a second layer at a lower level of theory. The MIM-Raman method is benchmarked on a set of large linear and cage molecules. The MIM extrapolated energy and Raman spectra are compared with the full calculations at B3LYP/6-311G(d,p) or B3LYP/6-311+G(d,p) levels of theory. The benchmark analysis of 21 molecules at MIM2 show an accuracy improvement of 85% in energies, 74% in Raman frequencies and 66% in intensities over MIM1. The implementation and benchmark analysis validates the MIM-Raman model for exploring Raman spectra of large molecules in the future. 相似文献
63.
Dušan Teodorović Vijay Varadarajan Jovan Popović Mohan Raj Chinnaswamy Sharath Ramaraj 《Annals of Operations Research》2006,143(1):123-131
In this paper, an “intelligent” isolated intersection control system was developed. The developed “intelligent” system makes
“real time” decisions as to whether to extend (and how much) current green time. The model developed is based on the combination
of the dynamic programming and neural networks. Many tests show that the outcome (the extension of the green time) of the
proposed neural network is nearly equal to the best solution. Practically negligible CPU times were achieved, and were thus
absolutely acceptable for the “real time” application of the developed algorithm. 相似文献
64.
Dejan M. Gvozdi Jovan B. Radunovi 《International Journal of Infrared and Millimeter Waves》1996,17(6):1001-1009
This paper analyses the influence of nonstationary effects on response pulswidth of Metal-Semiconductor-Metal Photodetector (MSM-PD) made of a two-valley semiconductor. A phenomenological model is used for 2D numerical simulation of carrier transport and intervalley transfer. The analysis of the pulsewidth response of the MSM-PD has been made for various micron and submicron structures, bias voltages and incident light wavelengths. 相似文献
65.
66.
D. Mihailovi? Z. ?aponji? M. Radoi?i? S. Lazovi? C. J. Baily P. Jovan?i? J. Nedeljkovi? M. Radeti? 《Cellulose (London, England)》2011,18(3):811-825
This study discusses the possibility of using a corona discharge at atmospheric pressure and air RF plasma at low pressure
for the cotton fibre activation prior to deposition of colloidal TiO2 nanoparticles in order to enhance antibacterial, UV protective and self-cleaning properties. X-ray photoelectron spectroscopy
(XPS) analysis confirmed the presence of TiO2 nanoparticles on the surface of cotton fibres. XPS elemental mapping indicated that TiO2 nanoparticles were more evenly distributed across the surface of untreated and corona pre-treated cotton fabrics in comparison
with RF plasma pre-treated fabric. Atomic absorption spectroscopy measurements revealed that the equivalent total content
of TiO2 in the cotton fabrics pre-treated by corona and RF plasma was 31% higher than in the fabric that did not undergo any treatment
prior to loading of TiO2 nanoparticles. In order to achieve maximum bacteria (Gram-negative bacteria Escherichia coli) reduction, untreated cotton fabric had to be loaded with colloidal TiO2 nanoparticles twice, but only once following corona or RF plasma pre-treatment. Deposition of TiO2 nanoparticles onto cotton fabrics provided maximum UV protective rating of 50+. Extraordinary photocatalytic activity of
TiO2 nanoparticles deposited onto cotton fabrics was proved by self-cleaning of blueberry juice stains and photodegradation of
methylene blue in aqueous solution under UV illumination. 相似文献
67.
Darka Mihailović Zoran Šaponjić Marija Radoičić Ricardo Molina Tamara Radetić Petar Jovančić Jovan Nedeljković Maja Radetić 《先进技术聚合物》2011,22(5):703-709
The objective of this study was to highlight the potential application of the corona discharge at atmospheric pressure for the surface activation of polyester (PES) fabrics in order to improve the binding efficiency of colloidal TiO2 nanoparticles. The obtained nanocomposite textile materials provide desirable level of UV protection, self‐cleaning properties, and photodegradation activity. The measured UV protection factor (UPF) of fabrics corresponds to UPF rating of 50+, designating the maximum UV protection. Additionally, the total photodegradation of methylene blue in aqueous solution was achieved after 24 hr of UV illumination and this capability was preserved and even improved after four repeated cycles. The results showed that the corona treated PES fabrics loaded with TiO2 nanoparticles had considerably enhanced the overall efficiency compared to PES fabrics loaded only with TiO2 nanoparticles. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
68.
Dejan M. Gvozdi Jovan B. Radunovic J. M. Elazar 《International Journal of Infrared and Millimeter Waves》1993,14(7):1485-1493
In this work the conformal mapping is used to determine an analytical expression for the electric field in MSM structures. The expression simplifies the analysis of optically generated carriers transport, i.e. the determination of the response of the MSN photodetectors. It can also be useful in the analysis of MSM electrooptical modulators operation. 相似文献
69.
The stereochemistry of β-fragmentation products formed in the oxidation of cis-and trans-4-t-butylcyclohexaanemethanol with lead tetraacetate and with lead tetraacetate-metal chloride combinations, under various reaction conditions, has been investigated, and the results compared with those obtained, under similar conditions, in the oxidative decarboxylation of cis-and trans-4-t-butylcyclohexanecarboxylic acid with the same reagents. It was found that all four substrates afford, under comparable conditions, identical cis-trans proportions of the respective fragmentation products, and that, therefore, so far as steric course is concerned, both the initial homolytic and subsequent heterolytic processes involved in the lead tetraacetate fragmentation reaction are independent of the nature and configuration of the starting material. 相似文献
70.
Surface modified TiO2 nanoparticles dissolved in toluene were encapsulated in PMMA by in situ radical polymerization of methyl methacrylate initiated by 2,2′-azobisisobutyronitrile. The surface modification of the TiO2 nanoparticles (average diameter of 4.5 nm) was achieved by the formation of a charge transfer complex between TiO2 nanoparticles and 6-palmitate ascorbic acid. The surface modified TiO2/nanoparticles were characterized using UV−Vis and FTIR spectroscopy, while the obtained polymer nanocomposites were characterized using reflection and 1H NMR spectroscopy, as well as gel permeation chromatography. The influence of the TiO2 nanoparticles on the thermal properties of the PMMA matrix was investigated using thermo-gravimetric analysis and differential scanning calorimetry. The glass transition temperature of the polymer was not influenced by the presence of the nanoparticles while the thermal stability was significantly improved. 相似文献