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1.
The purpose of the paper is to present the variation of total ozone concentration over Dumdum at Kolkata, India during different
seasons. It is concluded that the trend of ozone concentration during different seasons are different. A critical analysis
is done and following important results are obtained.
(i) |
The total ozone concentration increases during the pre-monsoon and winter periods. During pre-monsoon period rate of formation
of ozone increases sharply with the rise of surface temperature. 相似文献
2.
The paper presents the nature of variations of clouds and total ozone over Kolkata (22°34′N, 88°24′E), India. The low-level
cloud over Kolkata has been noticed to occur for many days and nights, particularly in the months from June to September.
The low level cloud occurrences were minimum in winter months. The effect of cloud occurrence on ozone concentration has been
critically analyzed and explained. It has been observed that the concentration of ozone increased with the increase of cloud
occurrence. The related possible chemical explanation for ozone production processes has been offered. 相似文献
3.
4.
The kinetics of the oxidative degradation of d -fructose by nanoparticles of MnO2 has been studied in dilute sulfuric acid medium and also in the presence of surfactants of cetyl trimethyl ammonium bromide (CTAB), Triton X-100 (TX-100), and Tween 20. Amorphous nanoparticles of MnO2 in the form of spherical particulates of size 50–200 nm, as detected by a transmission electron microscope, have been found to exist, supported on two-dimensional gum acacia sheets. The reaction is first order in MnO2 but complex order with respect to fructose and H+. The reaction is inhibited due to adsorption of reaction products on the surface of MnO2 nanoparticles. The reaction takes place through an intermediate complex formation between β-d -fructopyranose and protonated MnO2. A one-step two-electron transfer reaction ultimately leads to the formation of an aldonic acid and formic acid. The entropy of activation plays the key role for the reaction in the absence of surfactants. In the surfactant-mediated reaction, partitioning of both the reactants takes place between the aqueous and micellar pseudophases and reaction occurs following Berezin's model. Binding of fructose with the surfactants in the Stern/palisade layer takes place through the ion–dipole interaction and H-bonding while protonated MnO2 remains at the outer side of the Stern/palisade layer within the micelle. Both the enthalpy and entropy changes associated with the fructose–water interaction, fructose–micelle interaction, and micelle–water interaction finally control the fructose–micelle binding. 相似文献
5.
The sharp depletion of attenuation of 22.235 GHz signal before the onset of Nor’wester over Kolkata, India is observed and
possible explanation of such type of variation is presented. It is concluded that this may be taken as one possible method
of forecasting severe thunderstorm associated with Nor’wester. Physical explanations based on the formation and dissipation
mechanisms of thunderstorm are also presented. 相似文献
6.
Noncollinear difference frequency mixing of dye laser and Nd:YAG second harmonic (fundamental) radiation from a commercial
laser system is employed for the generation of 2.7–5.3 μm (1.6–1.7 μm) radiations in a flux-grown KTiOAsO1 crystal. The generated radiation is used to scan the methane absorption in the fundamental (v
3) and its first overtone (2v
3) band at pressure 90 torr in a laboratory made single pass gas cell of length 33 cm. 相似文献
7.
The effect of nonionic micelles of Triton X‐100 on the oxidative decarboxylation of l ‐glutamic acid by chloroaurate(III) complexes has been investigated in acetate buffer medium. The reaction is first order with respect to Au(III), but a complex order with respect to glutamate. H+ ion has both accelerating and retarding effects in the pH range 3.72–4.80, whereas a Cl? ion has an inhibiting effect in the range 0.02–0.56 mol dm?3. Under the experimental conditions, AuCl?4 and AuCl3(OH)? are the predominant and effective oxidizing species, whereas the zwitterion (H2A) and mononegative anion (HA?) are the predominant reducing species of the amino acid. The reaction involves a one‐step two‐electron transfer process and passes through the intermediate formation of iminic cation. In the presence of surfactant, the reaction passes through a maximum and it appears to follow Berezin's model, where both the oxidant and the substrate are partitioned between the aqueous and the micellar phase and then react. The binding constants between the reactants and the surfactant have been evaluated at different temperatures. Compensation between substrate–water interaction and substrate–micelle interaction plays an important role in such redox reactions in the presence of a surfactant. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 482–493, 2012 相似文献
8.
A critical analysis of Total Column Ozone (TCO) over Dum Dum, West Bengal, India is done during different seasons for the
period of 1997 to 2005. It is confirmed that pre-monsoon rate of change of TCO over Dum Dum is highly correlated with Gangetic
West Bengal, India monsoon rainfall of same year and that of TCO during other seasons are independent of monsoon rainfall
over Gangetic West Bengal. It is also concluded that pre-monsoon rate of change of TCO may play an important role to forecast
monsoon rainfall of a particular year over Gangetic West Bengal. It is also showed that other parameters affecting monsoon
rainfall are insignificant w.r.t. TCO variations. A possible explanation based on chemical kinetics of O3 are also presented. 相似文献
9.
The paper presents the covariation of seasonal intensity values of 5893 Å and 5577 Å lines of night airglow emissions and seasonal values of ozone concentration at Calcutta (Kolkata) with relative sunspot number, solar ultraviolet flux and solar 10.7 cm wavelength radio flux during the years 1984, 1985 and 1987. Various statistical parameters including coefficients of correlation between the atmospheric and solar quantities are computed. Possible explanation for the covariation of the quantities is provided invoking the excitation mechanisms and chemical reactions underlying them. 相似文献
10.
Pratik K. Sen Nasimul Gani Jayanta K. Midya Biswajit Pal 《Transition Metal Chemistry》2008,33(2):229-236
The kinetics of reduction of tetrachloroaurate(III) by glycine has been spectrophotometrically studied in NaOAc–AcOH buffer
in the pH range 3.73–4.77. The reaction is first order with respect to both Au(III) and glycine. Both H+ and Cl− ions have inhibiting effects on the reaction rate. The rate decreases with a decrease in the dielectric constant of the medium.
AuCl4− and AuCl3(OH)− are presumed to be the predominant oxidizing species under the conditions of the experiment. The reaction of gold(III) and
zwitterionic species of glycine proceeds with the intermediate formation of gold(I) and iminic cation and the latter subsequently
hydrolyses in a fast step to produce formaldehyde and ammonium ion. Formaldehyde was identified as the only organic product
by 1H NMR spectroscopy. 相似文献
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