Materials and Environmental Chemistry
Attempts on the preparation of elastic sorbents from waste rubber tyres, for removal of biobutanol from ferment liquor extracts, using low-distribution apolar solvent like n-heptane have been discussed. The main factors in preparation of useful sorbents are the type of the waste tyre, the type of the sulphonating agent, and the reaction conditions. The waste tyres containing large amount of styrene proved to be useful base material for preparation of elastic sorbent with concentrated sulphuric acid as sulphonation agent. The common mixed waste tyres resulted in elastic sorbents with lower absorbing capacities. Therefore, the styrene containing ones were studied over a wide range of the sulphonation conditions.
Keywords: Biobutanol, extractive fermentation, superabsorbent, solid sponge, sulphonated rubber, tyre wastes
New selective sensors based on potentiometric transduction for iodide assessment are described. The sensors based on the use of a newly synthesized copper (II) [N,N-bis-(1-carboxy-2-(p-hydroxybenzyl))–2,6-di(aminocarbonyl)pyridine] complex (CuL) as neutral ionophore in plasticized poly(vinyl chloride) (PVC) membranes. The influence of lipophilic cationic and anionic additives on the response properties of the sensors was evaluated. The fabricated sensors exhibited enhanced response towards iodide ions over the concentration range 6.3×10-6 to1.0 ×10-2 mol L-1 with a detection limit of 0.33μg mL−1 and a slope of -63.6±0.2 mV per decade. These sensors showed a fast and stable response, good reproducibility, and long-term stability. The sensors showed a stable potential over a wide pH range (4.5–9) and exhibited high selectivity for I− ion in the presence of many common anions. The sensors were applied for direct potentiometric measurements of iodide ions over the concentration range 0.8–1270 μg mL−1 and also for the titration of some metal ions (e.g. Ag+, Hg2+) and MnO4 – through sequential monitoring. The sequential binding of these ions with I− ensured share stepwise titration curves with consecutive end point breaks at the equivalent points.
Keywords: iodide; copper (II) [dipeptide derivative] complex; anion recognition; PVC membrane sensors; potentiometry
Minimization of impurities content in Si, necessary for its application as semiconductor material, was performed by using directional crystallization of metallurgical grade Si (n-MG-Si) with 98 wt. % Si purity without intermediate stages. After pulling from melt, n-MG-Si goes into p-type Si with current carriers concentration (p) ~ 1016 cm–3 and Si has been purified practically from most of the impurities. The possibility of uncontrolled impurities removal from Si depends on impurities effective coefficient of segregation in Si. Therefore we have investigated the effective coefficient of segregation of unwanted impurities in Si crystals, obtained by pulling directly from MG-Si melt. In the presented article the effective segregation coefficient of major impurities in Si has been calculated and analysed in the dependence on the crystallization conditions. Effective coefficient of segregation makes possible estimate the capacity and efficiency of Si purification from impurities during crystallization from melt.
Keywords: Silicon, segregation, impurity, crystallization, purification
The effect of nanometer size disordered regions in SixGe1–x and InPxAs1–x semiconductor alloys on the mobility ofcharge carriers has been investigated. The investigation has shown, that the composition dependence of the mobility appears as a result of contribution of main processes of current carriers scattering on phonons, ionized impurities and “alloy” disorders in SixGe1–x and InPxAs1–x alloys. We have calculated the contribution of these scattering processes towards total scattering. Share of contribution of “alloy” disorders into the total mobility is different for SixGe1–x and InPxAs1–x solid solutions. Unlike SixGe1–x alloys, the “alloy” disorders in InPxAs1–x practically do not disturb the crystal lattice in a tangible way at temperatures in the range of 4.2 – 300 K because of sublattices of InP and InAs retain certain individuality in InPxAs1–x alloys.
Keywords: Semiconductor Alloys, disorders, charge carriers mobility
Chemical and Biological Aspects of Life
Indoneesiella echioides (or) Andrographis echioides (L) Nees is an important herb widely distributed in south India. This is commonly known as False water willow. Indoneesiella echioides (L) Nees is used as in traditional Indian medicine. The leaf juice of this plant is used to cure fever. Different pharmacological properties of Indoneesiella echioides have already been reported. Thus, the present study was performed to investigate the preliminary phytochemical screening, separation, identification of compounds and compare the phytochemical composition of various fraction of Indoneesiella echioides using gas chromatography-mass spectrometry. The plant was extracted for various solvents in increasing order of polarity from using n-hexane, chloroform, ethyl acetate, acetone, ethanol, butanol and methanol. The result obtained after GC-MS studies were confirmed by spectral analysis.
Keywords: Indoneesiella echioides (L) Nees, phytochemical screening, separation and identification of compounds, GC-MS studies, spectral analysis
Novel Hg(II) complexes of d10 configuration have been synthesized and characterized by elemental analysis, IR, UV-VIS spectra and thermal analysis. The analytical and spectral data reveal that the ligands (H2L1- HL3) behave as neutral or mono basic bidentate in nature, coordinating via C=O or C-O and NH or C=N. The harmful effect of Hg-polluted drinking water on male sex hormones, kidney function as well as oxidative status biomarkers of male rats was investigated. Meanwhile, the potential protective effects of synthesized complexes and their ligands were studied. Results showed that orally administration of HgCl2 for 30 days caused a significant disruption of male sex hormones and kidney function. Further, the level of lipid peroxidation was elevated and activities of antioxidant enzymes were markedly declined in kidney and testes homogenates. The co-administration of HgCl2 with antipyrine and thiosemicarbazone as well as their complexes for four weeks led to amelioration in the kidney and testes functions as the levels of male sex hormones and kidney function tests were recovered. Meanwhile, these compounds showed ameliorative effects on the oxidative status of rats. It can be concluded that drinking of Hg-polluted water induces oxidative stress pathways that may lead to deterioration in kidney and testes function. The findings also suggest the curative action of antipyrine and thiosemicarbazone as well as their complexes since they exhibited the ability to resist the harmful action of mercury and to protect the organs from the action of free radicals.
Keywords: DTA; Hg(II) complexes; IR; male hormones; oxidative status; TGA
Thiophene, a five membered heterocycle is considered as biologically important dynamic scaffold that holds wide range of biological activities. The fruitful application of Cephoxitin as antimicrobial, Thenaldine as anti inflammatory, Ralitrexed as anticancer and Erdosteine as antioxidant proved the potential of thiophene moiety. Diverse biological response profile has pulled in consideration of many researchers to investigate this heterocycle to its multiple potential against several activities. This review is complementary to previous reviews and focuses to review the work reported on antimicrobial activities of thiophene derivatives.
Keywords: Thiophene, thienopyrimidine, antibacterial, antifungal, antitubercular, minimum inhibitory concentration
Industrial and Engineering Chemistry, Biotechnology
Generally, during drug discovery programs, after identification of new antibiotic metabolite, its high quantity production is obtained by various approaches, including production or extraction improvement or even strain genetic manipulation. To provide enough amounts of two novel non-toxic anti-MRSA pentapeptides named persipeptides (A and B) required for drug discovery programs, seven different fermentation broths examined. CM1 medium considerably enhanced the biosynthesis of persipeptides up to 219.63 ± 2.48, compared with ISP2 medium (36.31 ± 1.37), showing a six-fold increase. Additionally, at the extraction level, results of experimental design indicated that liquid-liquid extraction (LLE) of persipeptides by 34 % BuOH at 228 rpm (Stirrer speed), temperature 28 ˚C, and pH 9-9.5 for 78 min (stirring time) was equal to 264 ± 9.85 μg mL-1, which was the most favorable combination for their extraction. Compared with un-optimized extraction process (219.63 ± 2.48 μg mL-1), the optimized conditions improved the yield of the extraction by 20.20 %, while saving both time and solvent usage up to 67 % (162 min) and 16 %, respectively. The total sum of persipeptides enhancements resulted from the replacement of fermentation broth and subsequent optimization of their extraction by LLE reached almost seven-time, compared to conventional method (36.31 ± 1.37 μg mL-1). Therefore, relatively large amounts of persipeptides can be economically produced and extracted for various future experiments.
Keywords: Anti-MRSA; drug discovery; enhanced-production; experimental design; HPLC; liquid-liquid extraction; pentapeptide