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1.
Nonlinear Dynamics - Nonlinear flutter of variable stiffness composite plates—using a reduced-order model benefiting from a large-enough number of modes or degrees of freedom—is the... 相似文献
2.
This study analyzes the economics of transshipping biomass from truck to train in a North American setting. Transshipment
will only be economic when the cost per unit distance of a second transportation mode is less than the original mode. There
is an optimum number of transshipment terminals which is related to biomass yield. Transshipment incurs incremental fixed
costs, and hence there is a minimum shipping distance for rail transport above which lower costs/km offset the incremental
fixed costs. For transport by dedicated unit train with an optimum number of terminals, the minimum economic rail shipping
distance for straw is 170 km, and for boreal forest harvest residue wood chips is 145 km. The minimum economic shipping distance
for straw exceeds the biomass draw distance for economically sized centrally located power plants, and hence the prospects
for rail transport are limited to cases in which traffic congestion from truck transport would otherwise preclude project
development. Ideally, wood chip transport costs would be lowered by rail transshipment for an economically sized centrally
located power plant, but in a specific case in Alberta, Canada, the layout of existing rail lines precludes a centrally located
plant supplied by rail, whereas a more versatile road system enables it by truck. Hence for wood chips as well as straw the
economic incentive for rail transport to centrally located processing plants is limited. Rail transshipment may still be preferred
in cases in which road congestion precludes truck delivery, for example as result of community objections. 相似文献
3.
Jiyun Hu Hamed Mehrabi Yin-Shan Meng Maddison Taylor Jin-Hui Zhan Qigeng Yan Mourad Benamara Robert H. Coridan Hudson Beyzavi 《Chemical science》2021,12(22):7930
Metalation of covalent organic frameworks (COFs) is a critical strategy to functionalize COFs for advanced applications yet largely relies on the pre-installed specific metal docking sites in the network, such as porphyrin, salen, 2,2′-bipyridine, etc. We show in this study that the imine linkage of simple imine-based COFs, one of the most popular COFs, readily chelate transition metal (Ir in this work) via cyclometalation, which has not been explored before. The iridacycle decorated COF exhibited more than 10-fold efficiency enhancement in (photo)catalytic hydrogen evolution from aqueous formate solution than its molecular counterpart under mild conditions. This work will inspire more functional cyclometallated COFs to be explored beyond catalysis considering the large imine COF library and the rich metallacycle chemistry.This study describes cyclometallation as a new metal binding mode for imine-based COFs. The iridacycle decorated COF could be used for catalytic hydrogen evolution from aqueous formate solution with high stability and high efficacy. 相似文献
4.
R. Abu-Eittah Maher M. Hamed A. A. Mohamed 《International journal of quantum chemistry》1991,39(2):211-226
The electronic absorption spectra of 2-, 3-, and 4-vinylpyridines and 1,2-(2,3-dipyridyl), 1,2-(2,4-dipyridyl), 1,2-(3,4-dipyridyl), and 1,2-(4,4-dipyridyl) ethylenes have been investigated in polar and nonpolar solvents. A correlation has been made between the geometry of the molecule and the observed spectrum. Molecular orbital calculations have been carried out using the INDO/S? CI procedure and a limited geometry optimization. The solvent effect at the MO level has been calculated. MO calculations predicted the existence of nπ* transitions that were not observed experimentally. The wave functions of the different CI states were calculated. The experimental transition energy as well as oscillator strength corresponded satisfactorily with the calculated ones. The observed transitions were assigned according to the results of MO calculations. 相似文献
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7.
S. Abboudy A. E. Hamed M. E. Kassem L. I. Abou-El-Nasr 《Journal of Thermal Analysis and Calorimetry》1993,39(3):301-308
The influence of stoichiometric ratio on the phase transition of sodium potassium sulphate (NaxK1–x)2SO4 crystals is investigated in the temperature range 300–500 K. The stoichiometric ratiox is chosen to bex=0.2, 0.3, 0.4, 0.8 and 0.9. The study has been carried out by using differential scanning calorimetry, DSC technique. The value of the specific heat,C
p, at the transition temperature,T
c
, increases asx is increased up tox=0.4 and then decreases for higher values ofx. The change in the specific heat, C
p, is following a relation of the form C
p C
p (T–T
c
/T
c
)– with = 0.12 which is in a fair agreement with the 3d Ising model. Insertion of Cu2+ ions into the lattice of (NaxK1–x)2SO4 crystals leads to a multiple peak in the temperature dependence ofC
p. The results are discussed from thermodynamical point of view.We would like to thank Prof. E. F. El-Wahidy, Prof. of Solid State Physics and Head of Physics Department, Faculty of Science, Alexandria University, for his interest and support of this work. 相似文献
8.
Hamed M. Abu El-Nader 《Transition Metal Chemistry》1995,20(3):316-319
Summary The kinetics of the thermal decomposition of thetris-oxalactocobaltate(III) complex has been investigated in the presence of EtOH and (CH2OH)2 spectrophotometrically in the 50–70 ± 0.1 ° C range. The rate of the reaction decreases upon the addition of either of the alcohols to the reaction medium, whereas the activation energy increases. The thermodynamic parameters were calculated and are discussed in terms of the solvation effects. The influence of the dielectric constants of the solvent mixtures on the rate has been studied. A free radical mechanism is proposed and discussed. 相似文献
9.
10.
Green synthesis of silver nanoparticles (Ag NPs) has been achieved using oak fruit bark extract as a reducing, capping and stabilizing agent. The biosynthesized Ag NPs were characterized using various techniques. UV–visible spectrum of prepared silver colloidal solution showed absorption maximum at 433 nm. X‐ray diffraction and transmission electron microscopy analysis revealed that Ag NPs have a face‐centred cubic structure being spherical in shape with an average particle size of 20–25 nm. The toxicity of the Ag NPs was tested on bacterial species such as Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli by comparison based on diameter of inhibition zone in disc diffusion tests and minimum inhibitory concentration and minimum bactericidal concentration of NPs dispersed in liquid cultures. The antimicrobial activity of Ag NPs was greater towards Gram‐positive bacteria (S. aureus and B. subtilis) compared to Gram‐negative bacteria as determined using standard Kirby–Bauer disc diffusion assay and serial dilution. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献