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  • Author or Editor: Ajay Singh x
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Abstract

Thirty-micrometer thick polyvinylidenefluoride (PVDF)–zinc oxide (ZnO) nanocomposite samples in the mass ratio of ZnO (1–6% (w/w)) have been prepared by solution mixing method. The nano- and microstructures of PVDF–ZnO nanocomposite of different mass ratios were characterized by using high-resolution techniques such as atomic force microscopy (AFM) and scanning electron microscopy (SEM). The SEM and AFM images show the presence of different components such as nanoparticles, amorphous and crystalline phases in nanocomposite samples. Dielectric properties of polymer nanocomposite based on PVDF and ZnO of different mass/% compositions have been studied to understand the molecular motion at different frequencies in the temperature range from 300 to 500 K. The permittivity of the nanocomposites decreases with frequency, while increases with the increasing temperature and ZnO content. The loss peak that disappeared at higher frequency is the remarkable result of this study.

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Abstract  

A new inorganic ion-exchanger, zirconium tugnstoarsenate, has been synthesized which has been characterized by chemical analysis, thermogravimetry, X-ray and infrared spectroscopy. The ion exchanger has been found to be stable in acids and neutral salt solutions. The Kd values for 30 metal ions have been determined at pH 3–4 which show that the exchanger has high affinity for UO 2 2+ , ZrO2+, Cs+ and Tl+ ions. The variation of Kd for a number of metal ions as a function of concentration of nitric acid and ammonium nitrate has been investigated to elucidate the probable exchange mechanism and to work out conditions for elution. Some binary separations, viz. Sr2+−Cs+, Sr2+−Rb+, Sr2+−Y3+, Fe3+−Al3+, Fe3+−Zn2+ and Zn2+−Hg2+ in trace amounts have been carried out on the column of the exchanger which demonstrate the utility of the exchanger in radionalytical and analytical chemistry.

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Ion-exchange behaviour of copper ferricyanide

Application of ion-exchange column to the separation of Cs

Journal of Radioanalytical and Nuclear Chemistry
Authors: Ajay Jain, Raj Singh and Chand Bala

Abstract  

A new inorganic ion exchanger, copper ferricyanide prepared by adding copper nitrate to a potassium ferricyanide solution at 80°C has been found to be stable in acids and salt solutions. It has been characterized by chemical analysis, thermogravimetry. X-ray and infrared spectroscopy. Distribution coefficients determined for various metal ions show that the exchanger has a high affinity for heavy univalent cations. The variation of Kd for a number of metal ions as a function of nitric acid concentration and ammonium nitrate has been investigated to elucidate the probable exchange mechanism and to work out conditions for elution. Binary separations of Cs from a number of other metal ions were achieved on the column of exchanger. The exchanger is useful for the separation of137Cs.

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Ficus carica L. (Moraceae), the ‘fig tree’, is reported to help in the prevention of vein blockage. Its rich fiber content has a laxative effect and fig latex inhibits the growth of carcinoma cells. Despite the wide use in the Indian traditional system of medicine of, especially, the fruit as an antidiabetic drug, and pharmacological investigation of the leaves, very little investigation has been conducted on phytochemical properties of the plant. An HPTLC method has therefore been established for simultaneous quantification of four biomarkers — bergapten, psoralen, rutin, and chlorogenic acid — in different tissues of the plant. Levels of bergapten and psoralen were highest in the leaves and bark whereas amounts in the fruit were negligible. Levels of chlorogenic acid were highest in the fruit and the maximum concentrations of rutin were found in the leaves. It is therefore apparent that the part of the plant to be used as a drug should be decided on the basis of the activity desired.This HPTLC method can also be used for quality control and standardization of different parts of F. carica .

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Abstract

Short circuit thermally stimulated discharge current (TSDC) has been recorded in corona-charged ethyl cellulose foil samples at different annealing time. An analysis of the data reveals significant changes in the TSDC curves of the samples as a function of annealing time. The possible relaxation processes accounting for the changes are discussed, not only a shift of peak temperature of the observed peak to higher temperatures, but also a lowering in its height has been observed with increase in annealing time. Peak temperature higher than 343 K did not arise even for the annealing time of 240 h. The activation energy (A) has been found to increase, while the trapped charge carrier n t decrease with increase in annealing time. Linear relationship between ln A and n t indicated an exponential distribution of traps.

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Terminalia species are widely used as important timber-yielding plants and are rich source of tannins and dyes. The stem bark of these species (waste from the timber industry) is used in Ayurveda as a cardiac tonic and diuretic and is also of ethnobotanical importance. It can be exploited as a source of important polyphenols, for example ellagic and gallic acids, which are potent antioxidants. In this context, a TLC method has been established for quantification of ellagic and gallic acids in seven Terminalia species ( T. arjuna (Roxb.) Wight & Arn, T. bellirica Roxb., T. bialata Steud., T. catappa Linn., T. chebula Retz., T. manii King, and T. tomentosa W. & A. Prodr.), and TLC markers of the species have been identified. The study concluded that common and distinguishing bands were observed for all seven Terminalia species in UV light at 254 and 366 nm and after derivatization with anisaldehyde sulfuric acid reagent. T. bialata and T. chebula have a similar TLC profile under UV light at 254 nm and T. chebula has two characteristic yellow bands at R F 0.22 and 0.39 under UV light at 366 nm. T. manii could be identified by blue bands at R F 0.57 and 0.66 under UV light at 366 nm and by a purple band at R F 0.37 after derivatization. T. arjuna can easily be differentiated by a fluorescent blue band at R F 0.39 under UV light at 366 nm and a blue band at the same R F after derivatization. T. bellirica, T. manii , and T. tomentosa furnished faint blue, fluorescent blue, and greenish blue bands, respectively, at R F 0.66 under UV light at 366 nm. Only a single faint blue band is visible for T. catappa at R F 0.57 under UV light at 366 nm. The amounts of ellagic and gallic acids vary from species to species. The maximum concentrations of ellagic and gallic acids, 2.69% and 1.04%, respectively, were found in T. chebula and T. catappa , respectively.

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Bark of Myrica esculenta Buch.-Ham., commonly known as ‘Kaphal’ in indigenous systems of medicine, is used for treatment of a variety of ailments. Three samples were collected from the Nainital, Ranikhet, and Shimla regions of India for qualitative and quantitative standardization by HPTLC on silica gel plates. The profiles obtained by use of two mobile phases revealed the presence of almost similar components. Amethod was established for identification of the biomarkers gallic acid, lupeol, oleanolic acid, and stigmasterol in extracts of the plant, because of the therapeutic importance of these compounds. The characteristic band of gallic acid occurred at R F 0.56 when toluene-ethyl acetate-formic acid 5:5:1 was used as mobile phase. Bands of oleanolic acid, stigmasterol, and lupeol occurred at R F 0.38, 0.49, and 0.62, respectively, when toluene-ethyl acetate 8:2 was used. These biomarkers were also estimated quantitatively. The amounts of the biomarkers varies from sample to sample - stigmasterol from 0.2229–0.4489%, oleanolic acid from 0.0079–0.0384%, lupeol from 0.0233–0.0783%, and gallic acid from 0.0795–0.0918%. The amounts were highest in the Nainital sample and lowest in the Shimla sample.

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Emodin–phospholipid complex

A potential of herbal drug in the novel drug delivery system

Journal of Thermal Analysis and Calorimetry
Authors: Devendra Singh, M. S. M. Rawat, Ajay Semalty and Mona Semalty

Abstract

Developing the drugs as amphiphilic lipid complexes is a potential approach for improving therapeutic efficacy of the drugs by increasing solubility, reducing drug crystallinity, modifying dissolution behavior (sustained or controlled release), and improving bioavailability. Emodin (1,3,8-trihydroxy-6-methylanthraquinone), an anthranoid derivative, shows several biological effects like antimicrobial, antidiuretic, anti-cancerous, and potent antioxidant but due to poor solubility, the dissolution restrains its valuable importance. To overcome this limitation, the emodin–phospholipid complex was developed and investigated by thermal analysis (differential scanning calorimetry), crystallographic (X-ray diffractography), surface morphology (scanning electron microscopy), spectroscopic methods (FT-IR, 1H-NMR), solubility, and the dissolution (in vitro drug release) study. The phospholipid complex of emodin was found, fluffy and porous with rough surface morphology in the SEM. FT-IR, 1H-NMR, DSC, and X-RPD data confirmed the formation of the complex. The water and n-octanol solubility of emodin was improved from 2.25 to 9.97 and 53.45 to 77.62 μg/ml, respectively, in the prepared complex. The improved dissolution was shown by the phospholipid complex. Based on the results of the study, it can be concluded that the phospholipid complex may be considered as promising drug delivery system for improving the overall absorption and bioavailability of the emodin molecule.

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Abstract  

Ion-exchange papers were prepared by impregnating chromatographic Whatman No. 3 paper with pyridinium tungstoarsenate exchanger. The composition of the material loaded on the paper shows that the compound has the formula (C5H5NH)3 W1 2AsO4 0·Rf values of 30 metal ions were determined on these ion-exchange papers by developing with ascending technique in solvents containing mixtures of n-propanol and hydrochloric or nitric acid. Several binary, ternary and some quaternary separations were also achieved on these papers. Studies were also made on plain papers for comparison.

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Abstract

The kinetics of the periodate oxidation of p-toluidine (TOL) in acetone–water medium has been followed by monitoring the increase in the absorbance of the reaction intermediate, C4, and the main reaction product is 4-methyl-1,2-benzoquinone. Results under pseudo first order conditions, [IO4 ] > [TOL], are in agreement with the rate law d[C]/dt = kK 3 K 4 K w[MnII] [S] [IO4 ]0 [H+]/{K 2 K w + (K w + K b K 2)[H+] + K b [H+]2} where kK 3 K 4 is the empirical composite rate constant, K w is ionic product of water, K 2 is acid dissociation constant of H4IO6 , K b is base dissociation constant of TOL i.e. substrate [S] and [IO4 ]0 represents the concentration of periodate that has been taken in excess in most of the kinetic runs. In agreement with the rate law, the 1/k cat versus pH profile passes through a minimum. Free radical scavengers do not affect the reaction rate. The rate is found to decrease with an increase in ionic strength and decrease in dielectric constant of the medium. Activation parameters evaluated are: ∆E = 12.2 ± 1.1 kJ mol−1, A = (1.57 ± 0.005) × 107 dm3 mol−1 s−1; ∆S # = −115.9 ± 0.2 J mol−1 K−1, ∆G # = 46.2 ± 0.9 kJ mol−1 and ∆H # = 9.60 ± 0.06 kJ mol−1.

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