Electroreduction of Derivatives of N,N'-Dioxides of Phenazine and Quinoxaline in Nonaqueous Media and in the Presence of Proton Donors of Medium Strength

Russian Journal of Electrochemistry - The electroreduction (ER) of benzo[a]phenazine-7,12-dioxide (1) and 2-ethoxycarbonyl-3-methyl-quinoxaline-1,4-dioxide (2) in DMF on a glassy carbon electrode...     

A switchable ionic liquid with polarity swing-assisted regeneration properties used for the preconcentration of cadmium in biological samples

In the present study the cadmium (Cd) was determined in serum samples of psoriatic patients. The severity of psoriasis was evaluated according to criteria based on standard clinical diagnosis using Psoriasis Area Severity Index (PASI) score. In present study, an innovative tunable green solvent system based microextraction (TSS-ME) was applied for the enrichment of Cd in acid digested serum samples prior to determination with flame atomic absorption spectrometry. The hydrophobic complex of Cd-ammonium pyrrolidine thiocarbamate was extracted in a tunable solvent system which was prepared from a polybasic amine (N, N, N′, N′-tetramethyl-1, 4-diaminobutane), decanol and water system. The tunable green solvent system (TSS) which has zero ionic strength was converted to homogeneous monophasic polar hydrophilic phase via exposure to CO₂ at different pressure and time duration. Then hydrophobic enriched Cd- ammonium pyrrolidine thiocarbamate was back extracted, using HNO₃ (0.1 to 0.5 mol L⁻¹) then the second round of TSS-ME was applied. The acidic aqueous phase enrich with analyte was separated from tunable solvent. The separated TSS was easily reused for up to 10 time for preconcentration purposes without loss of its enrichment character. The smoker and nonsmoker psoriatic patients at PASI >10, have two to three folds higher Cd levels in serum samples than healthy persons.     

Small Ubiquitin-Like Modifier Protein 3 Enhances the Solubilization of Human Bone Morphogenetic Protein 2 in <Emphasis Type="Italic">E. coli</Emphasis>

Small ubiquitin-like modifier (SUMO) fusion technology is widely used in the production of heterologous proteins from prokaryotic system to aid in protein solubilization and refolding. Due to an extensive clinical application of human bone morphogenetic protein 2 (hBMP2) in bone augmentation, total RNA was isolated from human gingival tissue and mature gene was amplified through RT-PCR, cloned (pET21a), sequence analyzed, and submitted to GenBank (Accession no. KF250425). To obtain soluble expression, SUMO3 was tagged at the N-terminus of hBMP2 gene (pET21a/SUMO3-hBMP2), transferred in BL21 codon+, and ~?40% soluble expression was obtained on induction with IPTG. The dimerized hBMP2 was confirmed with Western blot, native PAGE analysis, and purified by fast protein liquid chromatography with 0.5 M NaCl elution. The cleavage of SUMO3 tag from hBMP2 converted it to an insoluble form. Computational 3D structural analysis of the SUMO3-hBMP2 was performed and optimized by molecular dynamic simulation. Protein-protein interaction of SUMO3-hBMP2 with BMP2 receptor was carried out using HADDOCK and inferred stable interaction. The alkaline phosphatase assay of SUMO3-hBMP2 on C2C12 cells showed maximum 200-ng/ml dose-dependent activity. We conclude that SUMO3-tagged hBMP2 is more suited for generation of soluble form of the protein and addition of SUMO3 tag does not affect the functional activity of hBMP2.     

Biological entities as chemical reactors for synthesis of nanomaterials: Progress,challenges and future perspective

Synthesis of nanomaterials is being gained extensive attention in the fields of chemistry, applied physics, catalysis, drug delivery and the most important in diagnosis and therapeutic applications. Recently, many reports have been published on physical and chemical synthesis of magnetic as well as metallic nanoparticles (NPs) with viable surface functionalization, but still there is a dire need of such strategies that can combine synthetic methodology with stable surface modification found in nature. Synthesis of NPs via biological methods is the possible way to solve these barriers. However, systematized summary and outlooks of NPs synthesis via biological entities with various influencing factors e.g. temperature, pH, concentration of reactants and reaction time has rarely been reported. This review will present the distinct advantages of biological synthesis of NPs over physical and chemical methods. It will also highlight the recent progress on synthesis of NPs via various biological systems i.e. plant, fungus, bacteria, and yeast. Furthermore, it will explain various factors that control the size, shape, and morphology of these NPs. Finally, it would present the future perspectives of green chemistry for the development of nano-science and -biotechnology.     

Rapid bioenabled formation of ferroelectric BaTiO3 at room temperature from an aqueous salt solution at near neutral pH

A 12-mer peptide, identified through phage display biopanning, has been used for the first time to induce the rapid formation of ferroelectric (tetragonal) nanocrystalline BaTiO3 at room temperature from an aqueous salt precursor solution at near neutral pH. BaTiO3 is widely used in capacitors, thermistors, displays, and sensors owing to its attractive dielectric, ferroelectric, pyroelectric, optical, and electrochemical properties. Two 12-mer peptides (BT1 and BT2) were selected from a phage-displayed peptide library via binding to tetragonal BaTiO3 powder. While these peptides possessed various types of amino acids, 8 of the 12 amino acids were common to both peptides. Each of these peptides induced the formation of faceted nanoparticles (50-100 nm diameter) from an aqueous precursor solution. X-ray diffraction and selected area electron diffraction patterns obtained from these faceted nanoparticles were consistent with the BaTiO3 compound. Rietveld analyses of the X-ray diffraction patterns yielded good fits to tetragonal crystal structures, with the BaTiO3 formed in the presence of the BT2 peptide exhibiting the most tetragonal character. A coating of the latter BaTiO3 nanoparticles exhibited polarization hysteresis (a well-known characteristic of ferroelectric materials) at room temperature and a relative permittivity of 2200. Such rapid, peptide-induced precipitation at room temperature provides new opportunities for direct BaTiO3 formation on low-melting or reactive materials (e.g., plastics, cloths, bio-organics) and the low temperature integration of BaTiO3 into electronic devices (e.g., on silicon or flexible polymer substrates).     

Enhancing dielectric and mechanical behaviors of hybrid polymer nanocomposites based on polystyrene,polyaniline and carbon nanotubes coated with polyaniline

The dielectric and mechanical properties of hybrid polymer nanocomposites of polystyrene/polyaniline/carbon nanotubes coated with polyaniline(PCNTs) have been investigated using impedance analyzer and extensometer. The blends of PS/PANI formed the heterogeneous phase separated morphology in which PCNTs are dispersed uniformly. The incorporation of a small amount of PCNTs into the blend of PS/PANI has remarkably increased the dielectric properties. Similarly, the AC conductivity of PS/PANI is also increased five orders of magnitude from 1.6 × 10~(-10) to 2.0 × 10~(-5) S·cm~(-1) in the hybrid nanocomposites. Such behavior of hybrid nanocomposites is owing to the interfacial polarization occurring due to the presence of multicomponent domains with varying conductivity character of the phases from insulative PS to poor conductor PANI to highly conductive CNTs. Meanwhile, the tensile modulus and tensile strength are also enhanced significantly up to 55% and 160%, respectively, without much loss of ductility for three phase hybrid nanocomposites as compared to the neat PS. Thereby, the hybrid nanocomposites of PS/PANI/_P CNTs become stiffer, stronger and tougher as compared to the neat systems.     

Influence of chitosan and epoxy cross-linking on physical properties of binary blends

In this study, blends of chitosan (Cs) and bisphenol-F-diglycidyl ether (3.80 × 10^?3 to 3.80 × 10^?2 mol) were cast by the solution route. FT-IR results suggested that chitosan was cross-linked at terminal amino groups through diepoxide linkage. The chitosan films became less flexible and stiffer upon reaction with epoxy. Blending improved percentage elongation (31%) and toughness (10 MPa), whereas Young’s modulus (145 MPa) and tensile strength (45 MPa) were decreased. Extent of weight loss in Cs/BPFDGE was lower (15%) than that of original precursors (chitosan 33%). Moreover, blending of chitosan with BPFDGE increased water absorption properties due to generation of hydrophilic ?OH groups.     

Determination of cadmium and lead in biological samples by three ultrasonic-based samples treatment procedures followed by electrothermal atomic absorption spectrometry

The development of 3 different ultrasonic-based sample treatment methods, ultrasonic probe-assisted acid extraction, ultrasonic-assisted acid slurry, and ultrasonic-assisted acid pseudodigestion is presented. These methods were compared for the determination of Cd and Pb by electrothermal atomic absorption spectrometry in biological samples (blood and scalp hair) and validated by using certified materials BCR 397 human hair and BCR 185R bovine liver. The sample amounts chosen to perform the analysis were 100 mg and 0.5 mL for solids (human hair and bovine liver) and blood samples, respectively. An acid digestion induced by microwave energy was used to obtain the total metal concentrations and for comparative purposes. The best results were obtained with the ultrasonic-assisted acid pseudodigestion, with which it was possible to perform accurate and precise determination of the Cd and Pb contents in 2 certified reference materials and biological samples of 50 normal males of ages 25-40 years. The precision of the methods, together with their efficiency, rapidity, low cost, and environmental acceptability, make them good alternatives for the determination of trace metals from biological samples. The precision of the methods for accuracy evaluation, resulting in good agreement according to the t-test for a 95% confidence level, and the relative standard deviations were lower than 10% (n=10) for all determinations.     

A new 14-membered cyclopeptide alkaloid from Zizyphus oxyphylla

One new 14-membered frangulanine-type cyclopeptide alkaloid, oxyphyl line-A (1) has been isolated from the stem bark of Zizyphus oxyphylla together with the known 13-membered cyclopeptide, nummularine R (2). The structure was established on the basis of spectral studies particularly 2D NMR.     

用光学频谱仪测量几种典型图像的频谱

利用空间频谱分析仪对不同光学图像进行频谱分析。