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111.
Flow through a channel whose walls are lined with non-erodible porous material is investigated using Beavers and Joseph slip boundary condition. It is shown that the effect of porous lining is to increase the mass flow rate and to decrease the friction factor. 相似文献
112.
113.
Adsorbed Intermediates in Oxygen Reduction on Platinum Nanoparticles Observed by In Situ IR Spectroscopy 下载免费PDF全文
Dr. Simantini Nayak Dr. Ian J. McPherson Prof. Kylie A. Vincent 《Angewandte Chemie (International ed. in English)》2018,57(39):12855-12858
The sluggish kinetics of oxygen reduction to water remains a significant limitation in the viability of proton‐exchange‐membrane fuel cells, yet details of the four‐electron oxygen reduction reaction remain elusive. Herein, we apply in situ infrared spectroscopy to probe the surface chemistry of a commercial carbon‐supported Pt nanoparticle catalyst during oxygen reduction. The IR spectra show potential‐dependent appearance of adsorbed superoxide and hydroperoxide intermediates on Pt. This strongly supports an associative pathway for oxygen reduction. Analysis of the adsorbates alongside the catalytic current suggests that another pathway must also be in operation, consistent with a parallel dissociative pathway. 相似文献
114.
Laser isotope separation (LIS) by infrared laser chemistry of polyatomic molecules has come a long way since its discovery.
The last decade has seen considerable efforts in scaling up of the process for light elements like carbon, oxygen and silicon.
These efforts aim at ways to improve both the enrichment factor and the throughput. The achievement is quite significant especially
for carbon isotope separation wherein macroscopic operating scales have been realized. We report our studies on the IR laser
chemistry of two promising systems, viz. neat CF2HCl and CF3Br/Cl2. We have investigated conditions for optimizing the dissociation yield and selectivity using natural samples containing l.l%C-13.Wealso
highlight our current efforts for scaling up the process. These include the design aspects of a photochemical reactor with
multipass refocusing Herriott optics for efficient photon utilization, development of a cryogenic distillation set up and
a preparative gas chromatograph for large scale separation/collection of the isotopically enriched photoproduct in the post-irradiation
stage. 相似文献
115.
116.
It is shown that it is sufficient to solve a single first order differential equation to determine exact Bianchi type V imperfect fluid solutions of Einstein's field equations. Two exact solutions are presented in this paper. One of these two solutions corresponds to the case when the anisotropic pressure tensor is proportional to the shear tensor. This proportionality, it is shown, is a necessary but not a sufficient condition for the absence of heat flow in a Bianchi type V universe. It is also observed that the presence of heat flow necessarily introduces anisotropy in a Bianchi type V universe. 相似文献
117.
A simple spectrophotometric method for the determination of nylidrin hydrochloride, isoxsuprine hydrochloride and salbutamol sulphate is described, based on measurement of the orangeyellow species produced when the drugs are coupled with diazotized benzocaine (p-aminoethyl benzoate) in trimethylamine medium. The method is applicable over the range 1-12 mug ml for isoxsuprine hydrochloride and nylidrin hydrochloride and 1-8 mug ml for salbutamol sulphate. The method is a modification of the Bratton-Marshall reaction and is simple, reproducible, accurate and more sensitive than those cited in the literature. 相似文献
118.
A simple extractive photometric method for the determination of tetramisole hydrochloride in pharmaceutical preparations is described. The method uses the formation of coloured complexes of the drug with reagents such as Solochrome Dark Blue, Solochrome Black T, Bromocresol Purple, Bromothymol Blue, Bromophenol Blue and Bromocresol Green in an acidic buffer. The ion-pair complexes formed are quantitatively extracted into chloroform under the experimental conditions. 相似文献
119.
120.
The rates of peroxydisulphate oxidation of aromatic ketones have been found to be first order with respect to peroxydisulphate as well as of silver (I), but independent of the aromatic ketone. The effect of substituents on the rate of oxidation has been evaluated. The logk values have been plotted against the σ+ values, with ρ+=? 0.14. The reactivities of 1- and 2-acetyl naphthalene have been discussed. A mechanism of the oxidation of aromatic ketones based on reactive Ag+2 species has been suggested. 相似文献