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71.
R. Verma J. Arunachalam S. Gangadharan 《Journal of Radioanalytical and Nuclear Chemistry》1992,164(5):327-335
A radiochemical neutron activation analysis procedure for the determination of Ta, W, Ir, Pt, Au, Cu, Cr, Co and Zn in lithium niobate has been developed. The method involves a one-step removal of radioactive nuclides of Nb, Ta and W representing the dominating radioactivity of the irradiated sample. After irradiation, the sample is fused with inactive carriers and Na2O2 in a nickel crucible. The fused cake is dissolved in HCl–H2O2 and Nb, Ta and W are homogeneously precipitated. The impurities are separated by combinations of precipitation and ion-exchange separations for precise -ray measurements with an overall chemical yield of 70% to 90%. The results are discussed. 相似文献
72.
An optimization procedure for the gallic acid-persulphate method for the ultratrace determination of vanadium is reported. The optimization step has improved the sensitivity by a factor of three. The linearity range of the calibration graph is also extended. 相似文献
73.
Saidkhodzha Nematulloev Dr. Arunachalam Sagadevan Badriah Alamer Dr. Aleksander Shkurenko Dr. Renwu Huang Dr. Jun Yin Dr. Chunwei Dong Dr. Peng Yuan Dr. Khursand E. Yorov Azimet A. Karluk Dr. Wasim J. Mir Bashir E. Hasanov Dr. Mohamed Nejib Hedhili Dr. Naveen M. Halappa Prof. Dr. Mohamed Eddaoudi Prof. Dr. Omar F. Mohammed Prof. Dr. Magnus Rueping Prof. Dr. Osman M. Bakr 《Angewandte Chemie (International ed. in English)》2023,62(26):e202303572
Point defects in nanoparticles have long been hypothesized to play an important role in governing the particle's electronic structure and physicochemical properties. However, single point defects in material systems usually exist with other heterogeneities, obscuring the chemical role of the effects. Herein, we report the synthesis of novel atomically precise, copper hydride nanoclusters (NCs), [Cu28H10(C7H7S)18(TPP)3] ( Cu28 ; TPP: triphenylphosphine; C7H7S: o-thiocresol) with a defined defect in the gram scale via a one-pot reduction method. The Cu28 acts as a highly selective catalyst for C−C cross-couplings. The work highlights the potential of defective NCs as model systems for investigating individual defects, correlating defects with physiochemical properties, and rationally designing new nanoparticle catalysts. 相似文献
74.
K. Santhakumar N. Kumaraguru S. Arunachalam M. N. Arumugham 《Transition Metal Chemistry》2006,31(1):62-70
The kinetics and mechanism of reduction of the surfactant complex ions, cis-chloro/bromo(dodecylamine)(triethylenetetramine)cobalt(III) by iron(II) in aqueous solution were studied at 303, 308 and
313 K by spectrophotometry under pseudo-first-order conditions using an excess of the reductant. The second-order rate constant
increases with cobalt(III) concentration and the presence of aggregation of the complex itself alters the reaction rate. The
reductions are acid-independent in the range [H+] = 0.05–0.25 mol dm−3. Variation of ionic strength (μ) influences the reaction rate. Activation and thermodynamic parameters have been computed. It is suggested that the reaction
of Fe2+(aq) with the cobalt(III) complex proceeds by an inner-sphere mechanism. The critical micelle concentration (CMC) values of
these surfactant metal complexes in aqueous solution were obtained from conductance measurements. Specific conductivity data
(at 303, 308 and 313 K) served for the evaluation of the temperature-dependent CMC and the standard Gibbs energy of micellization
(ΔGm0). 相似文献
75.
Magnetic field induced exciton binding energy is investigated in a strained InAs/GaAs quantum wire within the framework of single band effective mass approximation. The strain contribution to the potential is determined through deformation potentials. The interband emission energy of strained InAs/GaAs wire is investigated in the influence of magnetic field with the various structural parameters. Magnetic field induced photoionization cross section of the exciton is studied. The total optical absorption and the refractive index changes as a function of normalized photon energy between the ground and the first excited state in the presence of magnetic field are analyzed. The optical absorption coefficients and the refractive index changes strongly depend on the incident optical intensity and the magnetic field. The occurred blueshift of the resonant peak due to the magnetic field will give the information about the variation of two energy levels in the quantum well wire. The optical absorption coefficients and the refractive index changes are strongly dependent on the incident optical intensity and the magnetic field. 相似文献
76.
Accurate quantification of deoxyribonucleic acid (DNA) is critical for many analyses in molecular biology and genetic tests. We present a method in which the stoichiometrically existing phosphorus content in purified genomic DNA is quantitatively converted into orthophosphate ions by microwave assisted-UV digestion in the presence of microlitre quantities of dilute reagents (HCl, HNO(3), H(2)O(2)). The tandem use of microwave energy and ultraviolet photons for DNA digestion in pressurized quartz vessels enables a maximum reaction temperature of 240 °C resulting in efficient and fast mineralization of high molecular weight DNA within 30 minutes. Compared to hotplate digestion, the digestion time is reduced by a factor of 32. The MW-UV sample preparation approach coupled with the ion chromatographic measurement of phosphate using a high performance (HP) methodology provides an accurate quantitation of phosphorus mass fractions as low as 0.3 μg g(-1), corresponding to a DNA mass of 25 μg. The relative expanded uncertainties (% U) expressed at 95% confidence for these analyses range from 0.2 to 0.6%. Critically, the matrix of the calibrant solution is also matched with respect to the digested matrix anions (chloride, nitrate), without which significant bias in IC performance is observed. The phosphorus content of the calf thymus DNA was also measured using high-performance inductively coupled plasma optical emission spectroscopy (HP-ICP-OES), which provided independent data for comparison with the MW-UV digestion-IC based approach. Ion chromatography requires smaller volume of materials to perform the analysis and could be useful for characterizing primary calibration standards and certified reference materials with low uncertainties. 相似文献
77.
Ponnusamy Sami Natarajan Mariselvi Kandasamy Venkateshwari Murugesan Vairalakshmi Arunachalam Sarathi Kasi Rajasekaran 《Transition Metal Chemistry》2010,35(5):563-570
The kinetics of reduction of heteropoly 11-tungstovanadophosphate, [PVVW11O40]4−, (HPA1) and heteropoly 10-tungstodivanadophosphate, [PVVVVW10O40]5−, (HPA2) by thiourea has been investigated in HClO4/phthalate/acetate buffer solutions spectrophotometrically at 25 °C in aqueous medium. The stoichiometry of the reaction is
1:1 in both cases. The HPAs are converted into the corresponding one-electron reduced heteropoly blues, namely, [PVIVW11O40]5− and [PVIVVVW10O40]6−, and thiourea is oxidised to formamidine disulphide. The reaction shows first-order dependence in both [HPA] and [thiourea]
at constant pH. The rate–pH profile shows the participation of both the neutral and deprotonated forms of thiourea in the
reaction. The reaction proceeds through an outer sphere electron transfer mechanism in which activation-controlled electron
transfer is the rate-determining step. Self-exchange rate constants for the couples [PVVW11O40]4−/[PVIVW11O40]5−, [PVVVVW10O40]5−/[PVIVVVW10O40]6− and H2NCSNH2/H2NCS·+NH2 have been evaluated by Marcus theory. 相似文献
78.
Applicability of polyaniline (PANI) has been investigated for the preconcentration and speciation of inorganic mercury (Hg2+) and methyl mercury (CH3Hg+) in various waters (ground, lake and sea waters). Preliminary experiments (batch) with powdered PANI for the quantitative removal of both Hg2+ and CH3Hg+ showed that the retention of Hg2+ was almost independent of pH while a pH dependent trend from pH 1 to 12 was seen for CH3Hg+ with maximum retention at pH > 5. Time dependence batch studies showed that a contact time of 10 min was sufficient to reach equilibrium. The Kd values were found to be ∼8 × 104 and ∼7 × 103 for Hg2+ and CH3Hg+, respectively.Subsequently column experiments were carried out with PANI and the separation of the species was carried out by selective and sequential elution with 0.3% HCl for CH3Hg+ and 0.3% HCl-0.02% thiourea for Hg2+. This was then followed by further pre-concentration of mercury on a gold trap and its determination by CVAAS. The uptake efficiency studies showed that the PANI column was able to accumulate up to 100 mg Hg2+/g and 2.5 mg CH3Hg+/g. This method allows both preconcentration and speciation of mercury with preconcentration factors around 120 and 60 for Hg2+ and CH3Hg+, respectively. The interfering effects of various foreign substances on the retention of mercury were investigated. 相似文献
79.
Subramanian Sundarrajan Arunachalam Venkatesan Seeram Ramakrishna 《Macromolecular rapid communications》2009,30(20):1769-1774
Military soldiers, medicinal doctors, and ordinary people require protection against chemical and biological warfare (C&B) agents. Activated charcoal impregnated with metal ions is currently used in protective clothing applications, which has some disadvantages. Electrospinning is emerging as one of the cheapest technologies to produce continuous nanofibers with a high surface area‐to‐volume ratio. In the present study, electrospinning of a poly(ethylene imine) (PEI)/nylon blend has been carried out in which PEI acts as a support material as well as a catalytic media. The membrane is combined with non‐selective metal oxide nanoparticles to degrade C&B agents into non‐toxic products. In addition, these membranes possess hydrophilic properties, hence they are suitable candidates for protective clothing applications.
80.
MK Hossain-Ibrahim K Rezajooi JK MacNally MRJ Mason AR Lieberman PN Anderson 《BMC neuroscience》2006,7(1):8-21