Kinetics of hydrogen peroxide decomposition in aqueous sulfuric acid over palladium/carbon: effcet of acid concentration

Decomposition of H₂O₂ over Pd (5%)/carbon in an aqueous sulfuric acid solution at different acid concentrations (0-10 mol/L) and temperatures (281-313 K) in a magnetically stirred glass reactor has been investigated. The catalytic activity, activation energy and frequency factor for the decomposition decrease with increasing acid concentration; the decrease in the activation energy is, however, very small. This revised version was published online in June 2006 with corrections to the Cover Date.     

Drastic increase of selectivity for H2O2 formation in direct oxidation of H2 to H2O2 over supported Pd catalysts due to their bromination

Incorporation of bromide anions (1.0 wt%) in supported Pd catalysts (viz. Pd supported on Al2O3, ZrO2, SiO2, H-beta or Ga2O3) leads to a drastic increase in their selectivity for H2O2 formation in the direct oxidation of H2 to H2O2 by O2(at room temperature) in an aqueous acidic (0.03 M H3PO4) reaction medium; the selectivity increase is accompanied by a large decrease in the H2O2 decomposition activity of the catalysts.     

Effects of gamma irradiation on some chemicals using an NaI (Tl) detector

The present work was carried out to find out the gamma ray shielding properties and to study the effects using an NaI (Tl) detector using radioactive sources ⁵⁷Co, ¹³³Ba, ¹³⁷Cs, ⁵⁴Mn, ⁶⁰Co and ²²Na at energies 122, 356, 511, 662, 840, 1170, 1275 and 1330?keV, for some chemicals, namely, sodium thiosulfate (Na₂S₂O₃), benzoic acid (C₇H₆O₂), sodium hydroxide (NaOH), poly vinyl alcohol (PVA) (C₂H₄O), potassium nitrate (KNO3), naphthalene (C₁₀H₈). Mass attenuation coefficient (µ_m) values obtained from the experiment were used to determine the effective atomic numbers (Z_eff) and effective electron densities (N_eff), atomic cross-sections (σ_t) and electronic cross-sections (σ_e); it will be observed from the present work that the variation in the obtained values is only due to the increase or decrease in the gamma ray energy and the chemical composition of the sample. It was seen that the calculated and obtained values showed good agreement. The investigated data are useful in the electronic industry, plastic industry, building materials and agriculture fields. From the present work it was found that the PVA could be used as a better gamma shielding material.     

Matter of age: growing anisotropic gold nanocrystals in organic media

We investigated the influence of the reduction state of gold ions on the growth of gold nanocrystals in N,N-dimethyl formamide (DMF). While freshly prepared solutions of AuCl3 produce spherical nanocrystals, aged precursor solutions containing mainly Au+ ions and Au(0) atoms lead to various branched nanoparticles. Furthermore, we show that also the amount of the reducing and stabilisation agent tetra-n-octylammonium formate (TOAF) plays a decisive role on the shape of the nanocrystals, allowing us to grow triangular and cubic nanoparticles.     

The present and future of e-waste plastics recycling

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Identification of molecular fingerprints of phenylindole derivatives as cytotoxic agents: a multi-QSAR approach

Phenylindole is reported to be an interesting scaffold having promising cytotoxic activities and can overcome the cancer drug resistance possibly via binding to the colchicine binding site of tubulin. In order to find out the molecular fingerprints for the better cytotoxic activity of phenylindole derivatives, multiple validated chemometric modeling approaches namely hologram QSAR (HQSAR), Bayesian classification model, and pharmacophore mapping analyses were applied into a dataset of 102 phenylindole derivatives. The final HQSAR model shows good statistical significance (Q²?=?0.760; R²_Train?=?0.868; R²_Test?=?0.660), and the best pharmacophore hypothesis has the highest regression coefficient value (r?=?0.975) and the lowest RMS value of 0.679. Moreover, the Bayesian model is also statistically validated and robust to discriminate the cytotoxic and non-cytotoxic phenylindoles. These studies suggest that the amine group should be unsubstituted for retaining higher cytotoxicity. The pharmacophore mapping and Bayesian classification study suggest the importance of 2-phenyl group as a ring aromatic feature conducive to cytotoxicity. The steric and hydrophobic effect of long chain linear alkyl group has a positive influence on cytotoxicity as evidenced by the multi-QSAR study. Therefore, this multi-QSAR modeling reported here is beneficial in designing potential phenylindole cytotoxic agents in future.     

A rapid and green method for expedient multicomponent synthesis of N-substituted decahydroacridine-1,8-diones as potential antimicrobial agents

Research on Chemical Intermediates - An efficient, green, high yielding, and quick method for the synthesis of N-substituted decahydroacridine-1,8-diones was achieved by multicomponent reaction...