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Manmohan Kumar 《Radiation Physics and Chemistry》2001,62(5-6):387-392
The spectral characteristics of the bimetallic sols produced by gamma and electron irradiation of mixed solutions of Tl+–Cu2+ ions in different ratios have been studied in aqueous medium. The intermediate transient species have also been characterized by the technique of pulse radiolysis. The rate constant for the reaction of Cu2+ion with the Tl+ ion reduction species was founded by 4×109 dm3 mol−1s−1. Developmental absorption spectra in gamma radiolytic reduction of the mixed ions indicated reduction of Tl+ ion on the surface of small copper particles, resulting in bimetallic-sol with core of copper. The presence of a small concentration of Cu2+ ion was found to restrict the agglomeration process of thallium particles at near neutral pH conditions. The reducing capability of the bimetallic sols was found to be proportional to the thallium content in the sol. The observed UV–Vis spectra of the mixed Tl/Cu sols produced on electron irradiation showed much lower absorption in the higher wavelength region and were more close to that of the pure sol of the ion, present in higher concentration in the feed solution. Thus, the high dose rate-assisted stabilization of smaller thallium particles. Size of all these bimetallic sol particles was much less than 50 nm. 相似文献
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Jianghua Feng Jing Zhao Fuhua Hao Chang Chen Kishore Bhakoo Huiru Tang 《Journal of nanoparticle research》2011,13(5):2049-2062
The metabonomic changes in murine RAW264.7 macrophage-like cell line induced by ultrasmall superparamagnetic particles of
iron oxides (USPIO) have been investigated, by analyzing both the cells and culture media, using high-resolution NMR in conjunction
with multivariate statistical methods. Upon treatment with USPIO, macrophage cells showed a significant decrease in the levels
of triglycerides, essential amino acids such as valine, isoleucine, and choline metabolites together with an increase of glycerophospholipids,
tyrosine, phenylalanine, lysine, glycine, and glutamate. Such cellular responses to USPIO were also detectable in compositional
changes of cell media, showing an obvious depletion of the primary nutrition molecules, such as glucose and amino acids and
the production of end-products of glycolysis, such as pyruvate, acetate, and lactate and intermediates of TCA cycle such as
succinate and citrate. At 48 h treatment, there was a differential response to incubation with USPIO in both cell metabonome
and medium components, indicating that USPIO are phagocytosed and released by macrophages. Furthermore, information on cell
membrane modification can be derived from the changes in choline-like metabolites. These results not only suggest that NMR-based
metabonomic methods have sufficient sensitivity to identify the metabolic consequences of murine RAW264.7 macrophage-like
cell line response to USPIO in vitro, but also provide useful information on the effects of USPIO on cellular metabolism. 相似文献
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Sandeep K. Vaishanav Jyoti Korram Rekha Nagwanshi Kallol K. Ghosh Manmohan L. Satnami 《Journal of fluorescence》2016,26(3):855-865
Protein Quantum dots interaction is crucial to investigate for better understanding of the biological interactions of QDs. Here in, the model protein Bovine serum albumin (BSA) was used to evaluate the process of protein QDs interaction and adsorption on QDs surface. The modified Stern-Volmer quenching constant (Ka), number of binding sites (n) at different temperatures (298 308 and 318 K?±?1) and corresponding thermodynamic parameters (ΔG?<?0, ΔH?<?0, and ΔS?>?0) were calculated. The quenching constant (Ks) and number of binding sites (n) is found to be inversely proportional to temperature. It signified that static quenching mechanism is dominant over dynamic quenching. The standard free energy change (ΔG?<?0) implies that the binding process is spontaneous, while the enthalpy change (ΔH?<?0) suggest that the binding of QDs to BSA is an enthalpy-driven process. The standard entropy change (ΔS?>?0) suggest that hydrophobic force played a pivotal role in the interaction process. The adsorption process were assessed and evaluated by pseudofirst-order, pseudosecond-order kinetic model, and intraparticle diffusion model. 相似文献
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The gamma-ray shielding behaviour of a material can be investigated by determining its various interaction and energy-absorption parameters (such as mass attenuation coefficients, mass energy absorption coefficients, and corresponding effective atomic numbers and electron densities). Literature review indicates that the effective atomic number (Zeff) has been used as extensive parameters for evaluating the effects and defect in the chosen materials caused by ionising radiations (X-rays and gamma-rays). A computer program (Zeff-toolkit) has been designed for obtaining the mean value of effective atomic number calculated by three different methods. A good agreement between the results obtained with Zeff-toolkit, Auto_Zeff software and experimentally measured values of Zeff has been observed. Although the Zeff-toolkit is capable of computing effective atomic numbers for both photon interaction (Zeff,PI) and energy absorption (Zeff,En) using three methods in each. No similar computer program is available in the literature which simultaneously computes these parameters simultaneously. The computed parameters have been compared and correlated in the wide energy range (0.001–20?MeV) for 10 commonly used building materials. The prominent variations in these parameters with gamma-ray photon energy have been observed due to the dominance of various absorption and scattering phenomena. The mean values of two effective atomic numbers (Zeff,PI and Zeff,En) are equivalent at energies below 0.002?MeV and above 0.3?MeV, indicating the dominance of gamma-ray absorption (photoelectric and pair production) over scattering (Compton) at these energies. Conversely in the energy range 0.002–0.3?MeV, the Compton scattering of gamma-rays dominates the absorption. From the 10 chosen samples of building materials, 2 soils showed better shielding behaviour than did other 8 materials. 相似文献
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The basic reproduction number and the point of endemic equilibrium are two very important factors in any deterministic compartmental epidemic model as the basic reproduction number and the point of endemic equilibrium represent the nature of disease transmission and disease prevalence respectively. In this article the sensitivity analysis based on mathematical as well as statistical techniques has been performed to determine the importance of the epidemic model parameters. It is observed that 6 out of the 11 input parameters play a prominent role in determining the magnitude of the basic reproduction number. It is shown that the basic reproduction number is the most sensitive to the transmission rate of disease. It is also shown that control of transmission rate and recovery rate of the clinically ill are crucial to stop the spreading of influenza epidemics. 相似文献
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Shail Patel Ian P. Stott Manmohan Bhakoo Peter Elliott 《Journal of computer-aided molecular design》1998,12(6):543-556
The problem of designing new peptides that possess specific properties, such as bactericidal activity, is of wide interest. Recently, attention has focused on the use of Computer-Aided Molecular Design techniques in parallel with more traditional 'synthesise and test' methods. These techniques may typically use Genetic Algorithms to optimise molecules based on Neural Network models that predict activity. In this paper we describe a successful application of this Molecular Design methodology that has resulted in novel bactericidal peptides of real value. A key issue for commercial utilisation of such results is the ability to protect the intellectual property rights associated with the discovery of new molecules. Typically peptide patents use structural templates of amino acid hydrophobicity-hydrophilicity that define highly regular peptide patent spaces. In an extension of established patenting practice we describe a patent application that uses a Neural Net predictive model to define the regions of peptide space that we claim within the patent. This formalism makes no a priori assumptions about the regularity of the patent space. A preliminary comparative investigation of the shape and size of this and other bactericidal peptide patent spaces is conducted. 相似文献
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Dr. Govind Goroba Pawar Dr. Ajit Prabhakar Kale Pooja Sah Prof. Manmohan Kapur 《European journal of organic chemistry》2023,26(3):e202201277
The total synthesis of the 14-membered resorcylic acid lactone neocosmosin A is described. The key step in the synthesis is the palladium-catalyzed α-arylation of TES-enol ethers of enones. The employment of the α-arylation approach to this class of resorcylic acid lactones is a new approach, which has the scope of being generalized into a unified approach for the synthesis of this class of natural products. 相似文献
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Bairavarasu SR Edwards ME Sastry MD Kochary F Kommidi P Reddy BR Lianos D Aggarwal MD 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(4):1581-1587
We present electron paramagnetic resonance (EPR)--evidence of photomagnetism under the conditions of in situ green laser illumination (photo-EPR) in lead magnesium niobate-lead titanate, Pb(Mg,Nb)O3-PbTiO3 (PMN-PT), containing nanoparticles/wires of orthorhombic beta-PbO as identified by Raman spectroscopy. Photo-EPR studies of the sample containing beta-PbO, brownish red in color, have shown intense line at g=2.00, and its yield increased when produced in the presence of 7.5 kG external magnetic field suggesting the formation of magnetic polaron. This was identified as due to interaction between Fe3+, photoinduced Pb3+ and unpaired electron trapped at oxygen vacancies. The photoinduced growth and decay of magnetic polaron has shown a non-exponential behavior. Photoluminescence (PL) studies were conducted with excitation at 308 nm (XeCl laser) and also at 454.5, 488 and 514.5 nm using Ar+ laser. The excitation with 308 nm gave broad PL centered at 500 and 710 nm the latter being quite prominent in beta-PbO containing crystals, along with cooperative luminescence at 350 nm involving two emitting centers. The excitation with Ar+ laser lines, close to the electronic absorption in samples containing beta-PbO gave richer and sharp PL emission in red region from the constituents of the magnetic polaron and also intense anti-Stokes emission on excitation with 514.5 nm radiation. This appears to be due to phototransfer optically stimulated luminescence (PT-OSL) involving electron-hole recombination at photoinduced magnetic polaron site. 相似文献