Determination of Lambda-Cyhalothrin and Malathion Residues in Locust by Gas Chromatography with Electron Capture Detection

Journal of Analytical Chemistry - A reliable, easy, and reproducible method was developed for the quantification of λ-cyhalothrin and malathion residues in desert locust. For the extraction, a...     

Benchmark approach to search of cost-effective and accurate density functional for homolytic cleavage of C─Mg bond of Grignard reagent

Grignard reactions are of importance in organic chemistry for the synthesis β-keto esters and diethyl malonate, alcohols, aldehydes or ketones, monocarboxylic acids, and other organometallic compounds. Generally, the heterolytic dissociation of C─Mg bond in Grignard reagent is the key step in these reactions. Recently, homolytic cleavage of the C─Mg bond in Grignard reagents has been reported in the preparation of stable radicals. These reactive species react with other compounds, which result in the formation of hydrocarbons and their derivatives. Therefore, the study of homolytic cleavage of C─Mg bonds is quite vital to better understand the kinetics and thermodynamics of these reactions. In the current study, a benchmark approach is adopted to find a cost-effective and accurate density functional (DF) for bond dissociation energies measurement of the C─Mg bond of Grignard reagents. Twenty-nine DFs from 13 density functional theory (DFT) classes with three types of basis sets (Pople' 6-31G(d) and 6-311G(d), Dunning's aug-cc-pVDZ, and Karlsruhe' def2-SVP basis sets) are implemented for the measurement of dissociation energies of the C─Mg bond. Theoretical dissociation energy values are compared with experimental reported values of the C─Mg bond of selected Grignard reagents. TPSSTPSS of the meta-GGA class with 6-31G (d) basis set gave accurate results, and its Pearson's correlation is 0.95. SD, root mean square deviation, and mean unsigned error of this method are 2.36 kcal mol⁻¹, 2.33 kcal mol⁻¹, and −0.46 kcal mol⁻¹, respectively. TPSSTPSS of the meta-GGA class is a one-electron, self-interaction, error-free Tao-Perdew-Staroverov-Scuseria functional that performed better with the 6-31G(d) basis set.     

Polyphenolics with Strong Antioxidant Activity from Acacia nilotica Ameliorate Some Biochemical Signs of Arsenic-Induced Neurotoxicity and Oxidative Stress in Mice

Neurotoxicity is a serious health problem of patients chronically exposed to arsenic. There is no specific treatment of this problem. Oxidative stress has been implicated in the pathological process of neurotoxicity. Polyphenolics have proven antioxidant activity, thereby offering protection against oxidative stress. In this study, we have isolated the polyphenolics from Acacia nilotica and investigated its effect against arsenic-induced neurotoxicity and oxidative stress in mice. Acacia nilotica polyphenolics prepared from column chromatography of the crude methanol extract using diaion resin contained a phenolic content of 452.185 ± 7.879 mg gallic acid equivalent/gm of sample and flavonoid content of 200.075 ± 0.755 mg catechin equivalent/gm of sample. The polyphenolics exhibited potent antioxidant activity with respect to free radical scavenging ability, total antioxidant activity and inhibition of lipid peroxidation. Administration of arsenic in mice showed a reduction of acetylcholinesterase activity in the brain which was counteracted by Acacia nilotica polyphenolics. Similarly, elevation of lipid peroxidation and depletion of glutathione in the brain of mice was effectively restored to normal level by Acacia nilotica polyphenolics. Gallic acid methyl ester, catechin and catechin-7-gallate were identified in the polyphenolics as the major active compounds. These results suggest that Acacia nilotica polyphenolics due to its strong antioxidant potential might be effective in the management of arsenic induced neurotoxicity.     

Radiobiokinetic evaluation of domestic cold kits

Domestically produced diagnostic cold kits, viz. glucoheptonate (GH), diisopropyliminodiacetic acid (DISIDA), dimercaptosuccinic acid (DMSA), diethylenetriamine-pentaacetic acid (DTPA), methylenediphosphonate (MDP) and Sn-colloid were labeled with^99mTc and their in-vivo distribution in experimental animals (rats) was evaluated prior to use in humans for diagnostic scanning. The biodistribution pattern was found in accordance with the latest guidelines of the International Atomic Energy Agency (IAEA), which serve as a standard for small scale producers.     

Design of donor–acceptor–donor (D–A–D) type small molecule donor materials with efficient photovoltaic parameters

Four Donor–Acceptor–Donor (D–A–D) type of donor molecules (M1‐M4) with triphenylamine (TPA) as donor moiety, thiophene as bridge, and thiazolothiazole as acceptor unit were designed and its photovoltaic parameters were equated with reference molecule “R.” DFT functional CAM‐B3LYP/6‐31G (d,p) was found best for geometry optimization and TD‐CAM‐B3LYP/6‐31G (d,p) was found suitable for excited state calculations. Among designed donor molecules, M4 manifests suitable lowest band gap of 4.73 eV, frontier molecular orbital energy levels as well as distinctive broad absorption of 455.3 nm due to the stronger electron withdrawing group. The electron‐withdrawing substituents contribute to red shifts of absorption spectra and better stabilities for designed molecules. The theoretically determined reorganization energies of designed donor molecules suggested excellent charge mobility property. The lower λ_e values in comparison with λ_h illustrated that these four donor materials would be ideal for electron transfer and M4 would be best amongst the investigated molecules with lowest λ_e of 0.0177. Furthermore, the calculated Voc of M4 is 2.04 V with respect to PC₆₀BM (phenyl‐C61‐butyric acid methyl ester). This study revealed that the designed donor materials are suitable and recommended for high performance organic solar cell devices.     

Effect of surface morphology on measurement and interpretation of boundary slip on superhydrophobic surfaces

Highly liquid repellent surfaces have been obtained by the combination of roughness and hydrophobicity. Studies have reported that the flow over such surfaces exhibits larger boundary slip as compared to the smooth hydrophobic surfaces. However, the surface roughness can also lead to apparent slip. Thus, the effect of the two factors, that is, wettability and roughness, needs to be segregated. In this study, we have measured the slippage of water on rough hydrophilic and hydrophobic surfaces using colloidal probe atomic force microscopy technique (CP‐AFM). Results showed that the effect of surface roughness on the measured slip is dominant over that of wettability. It was also found that slip on surfaces with sparsely distributed asperities is highly local and measurements on various locations give dissimilar results. The results suggested that the main reason of the larger slip, on rough hydrophobic surfaces, is likely to be the roughness and not the hydrophobicity. Moreover, it was also found that the slip does not vary considerably with the increase or decrease in the shear rate. Most likely, this kind of slip phenomena is caused by the apparent decrease of the drag force, because the nanoasperities on the surface restrict the probe from reaching the surface properly. Copyright © 2016 John Wiley & Sons, Ltd.     

The effect of fast neutrons on the electrophysical properties of nuclear-doped <Emphasis Type="Italic">p</Emphasis>-silicon

The influence of the defects induced by fast-neutron irradiation on the rate of charge-carrier removal in nuclear-doped silicon (p-Si < B, P>) and a test p-Si < B > sample is studied by measuring the Hall coefficient and resistivity at room temperature. It is shown that the rate of removal of charge carriers in p-Si < B, P > is higher than that in p-Si < B>. A barrier model is developed to explain the observed effect.     

Hypoglycemic and Anti-Inflammatory Effects of Triterpene Glycoside Fractions from Aeculus hippocastanum Seeds

Horse chestnut (Aesculus hippocastanum L.)-derived drugs have shown their potential in biomedical applications. The seed of A. hippocastanum contains various kinds of chemical compounds including phenolics, flavonoids, coumarins, and triterpene saponins. Here, we investigated the chemical components in A. hippocastanum L. grown in Uzbekistan, which has not yet been studied in detail. We identified 30 kinds of triterpene saponins in an extract of A. hippocastanum L. Classifying extracted saponins into eight fractions, we next studied the hypoglycemic and the anti-inflammatory activities of escin and its derivatives through in vivo experiments. We came by data indicating the highest (SF-1 and SF-2) and the lowest (SF-5 and SF-8) antidiabetic and anti-inflammatory effects of those eight fractions. These results imply the prospective use of A. hippocastanum L. grown in Uzbekistan in the production of pharmaceutical drugs to treat diabetes and inflammation.     

Investigation of the electrophysical properties and structures of impurity-defective complexes in silicon doped with palladium

Electric and structural methods are used to investigate formation of impurity-defective complexes in silicon doped with palladium. It is demonstrated that acceptor levels E _C – 0.18 and E _v + 0.34 eV detected in silicon during incorporation of palladium are caused by singly and doubly negatively charged states of [Pd–V] complexes, and the donor level E _v + 0.32 eV is a product of chemical compound of palladium with hydrogen forming the [Pd–H] complex. It is assumed that the palladium impurity in the doped silicon samples causes the elastic crystal energy to change and impurity clouds to be formed around microdefects. An increase in the temperature of palladium diffusion in silicon causes the impurity clouds to decay and the microdefect core sizes to decrease with their subsequent chaining into a needle.     

Dinuclear nickel(II) complexes with ONO-pincer and coordinated aquo ligands as a robust homogeneous water oxidation catalyst

Russian Chemical Bulletin - A nickel(II) complex with the newly synthesized dicarboxamide ligand [H2LBZ][(CF3SO3)Cl] was explored as a water oxidation catalysis. All the synthesized compounds were...