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91.
It has been shown recently that the analysis records in capillary electrophoresis may involve regions with extremely strong electromigration dispersion of peaks. Such a fundamental effect is due to the existence of more centers of symmetry in a given electrolyte system. This paper shows that even such a simple and frequently used electrolyte system as phosphate buffer may exhibit more than one center of symmetry. By using the peak shape diagram approach we have revealed that neutral and alkaline phosphate buffers have two centers of symmetry and one center of extreme dispersion. Model experiments confirmed this new important discovery. 相似文献
92.
Intensity and lifetime data indicate that the self-quenching of Sm3+ fluorescence in barium borate glass matrix is by direct dipole-quadrupole interactions. The quenching of Tb3+ fluorescence by Sm3+ has been found due to direct dipole-dipole interactions. However, at relatively low Sm3+ concentrations, energy transfer through migration among Tb3+ ions also occurs. Further at low Sm3+ concentrations, there is an enhancement of Sm3+ emission due to energy transfer to an Sm3+ that is not coupled to a second Tb3+ or Sm3+ ion. At high Sm3+ concentrations, no enhancement of Sm3+ emission occurs and is attributed to transfer to Sm3+Sm3+ or Sm3+Tb3+ couples that take up the energy by simultaneous transitions that lie well below the manifold of Sm3+. 相似文献
93.
R. P. Pant S. B. Halligudi R. S. Shukla D. K. Suri R. V. Mehta 《Reaction Kinetics and Catalysis Letters》1998,64(1):109-112
A ferrofluid consisting of colloidally dispersed magnetite particles in water was found to be an efficient selective catalyst
for water gas shift reaction at 15–25 atmosphere of CO pressure in the temperature range of 423–553 K where the products obtained
were only CO2 and H2. The reaction was studied as a function of variation of the concentration of catalyst, pressure of CO gas and temperature.
Kinetic parameters suggested a mechanism involving first order dependence in CO and catalyst concentrations. 相似文献
94.
Excimer emission in concentrated aqueous solutions of 9-aminoacridine hydrochloride has been observed at 555 nm. A study of monomer, dimer and excimer emission, absorption and excitation spectra shows that the excited dimer emission is transformed into excimer emission at higher temperatures. Unusually large hypochromism is observed on dimer formation. 相似文献
95.
Bhuvan C. Pant 《Journal of organometallic chemistry》1974,65(1):51-56
Diaryltellurium diacetates have been prepared in excellent yields by the oxidation of diaryltellurides with lead tetraacetate and also by the reaction of diaryltellurium dichlorides with silver acetate. Hydrolysis, reduction and exchange reactions of these derivatives and their spectral data are described. 相似文献
96.
The performance of PSO algorithm depends greatly on the appropriate parameter selection strategies for fine tuning its parameters. This paper proposes three new nonlinear strategies for selecting inertia weight which plays a significant role in particle’s foraging behaviour. The PSO variants implying these strategies are named as: fine grained inertia weight PSO (FGIWPSO); Double Exponential Self Adaptive IWPSO (DESIWPSO) and Double Exponential Dynamic IWPSO (DEDIWPSO). In FGIWPSO, inertia weight is obtained adaptively, depending on particle’s iteration wise performance and decreases exponentially. DESIWPSO and DEDIWPSO employ Gompertz function, a double exponential function for selecting inertia weight. In DESIWPSO the particles’ iteration wise performance is fed as input to the Gompertz function. On the other hand DEDIWPSO evaluates the inertia weight for whole swarm iteratively using Gompertz function where relative iteration is fed as input. The efficacy and efficiency of proposed approaches is validated on a suite of benchmark functions. The proposed variants are compared with non linear inertia weight and exponential inertia weight strategies. Experimental results assert that the proposed modifications help in improving PSO performance in terms of solution quality as well as convergence rate. 相似文献
97.
Vijay Pant 《偏微分方程通讯》2013,38(9-10):1609-1641
98.
V. Seena Anukool Rajorya Prita Pant Soumyo Mukherji V. Ramgopal Rao 《Solid State Sciences》2009,11(9):1606-1611
Micro fabricated sensors based on nanomechanical motion with piezoresistive electrical readout have become a promising biochemical sensing tool. The conventional microcantilever materials are mostly silicon-based. The sensitivity of the sensor depends on Young's modulus of the structural material, thickness of the cantilever as well as on the gauge factor of the piezoresistor. UV patternable polymers such as SU-8 have a very low Young's modulus compared to the silicon-based materials. Polymer cantilevers with a piezoresistive material having a large gauge factor and a lower Young's modulus are therefore highly suited for sensing applications. In this work, a spin coatable and photopatternable mixture of carbon black (CB) and SU-8, with proper dispersion characteristics, has been demonstrated as a piezoresistive thin film for polymer microcantilevers. Results on percolation experiments of SU-8/CB composite and fabrication of piezoresistive SU-8 microcantilevers using this composite are presented. With our controlled dispersion experiments, we could get a uniform piezoresistive thin film of thickness less than 1.2 μm and resistivity of 2.7 Ω cm using 10 wt% of CB in SU-8. The overall thickness of the SU-8/composite/SU-8 is approximately 3 μm. We further present results on the electromechanical characterization and biofunctionalization of the cantilever structures for biochemical sensing applications. These cantilevers show a deflection sensitivity of 0.55 ppm/nm. Since the surface stress sensitivity is 4.1 × 10−3 [N/m]−1, these cantilevers can well be used for detection of protein markers for pathological applications. 相似文献
99.
Using optical microscopy, we investigated the crystallization of aqueous ammonium sulfate droplets containing soot and kaolinite, as well as the crystallization of aqueous ammonium sulfate droplets free of solid material. Our results show that soot did not influence the crystallization RH of aqueous ammonium sulfate particles under our experimental conditions. In contrast, kaolinite increased the crystallization RH of the aqueous ammonium sulfate droplets by approximately 10%. In addition, our results show that the crystallization RH of aqueous ammonium sulfate droplets free of solid material does not depend strongly on particle size. This is consistent with conclusions made previously in the literature, based on comparisons of results from different laboratories. From the crystallization results we determined the homogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate droplets and the heterogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate particles containing kaolinite. Using classical nucleation theory and our experimental data, we determined that the interfacial tension between an ammonium sulfate critical nucleus and an aqueous ammonium sulfate solution is 0.064 +/- 0.003 J m(-2) (in agreement with our previous measurements), and the contact angle between an ammonium sulfate critical nucleus and a kaolinite surface is 59 +/- 2 degrees. On the basis of our results, we argue that soot will not influence the crystallization RH of aqueous ammonium sulfate droplets in the atmosphere, but kaolinite can significantly modify the crystallization RH of atmospheric ammonium sulfate droplets. As an example, the CRH50 (the relative humidity at which 50% of the droplets crystallize) ranges from about 41 to 51% RH when the diameter of the kaolinite inclusion ranges from 0.1 to 5 microm. For comparison, the CRH50 of aqueous ammonium sulfate droplets (0.5 microm diameter) free of solid material is approximately 34.3% RH under atmospheric conditions. 相似文献
100.
Bhattacharyya Sibes Chandra Pant Chandra Shekhar Mehra Anurag Bhattacharya Bikash Malik Ranjan Kumar 《Journal of solution chemistry》2014,43(8):1466-1475
Journal of Solution Chemistry - The solubility of ammonia in toluene has been measured at 398 K and at pressures up to 340 kPa using a static, synthetic and isochoric technique.... 相似文献