Elucidation of cell killing mechanism by comparative analysis of photoreactions on different types of bacteria

The mechanism of biocidal action of nano titania on Escherichia coli and Staphylococcus aureus has been evaluated by various biochemical techniques like lipid peroxidation, hydrolysis of orthonitrophenol β-D-galactopyranoside, estimation of protein-amino acid and bacterial nucleic acids leakage into solution, in addition to morphology studies by electron microscopy (TEM and SEM) and K(+) ion leakage by inductively coupled plasma optical emission spectrometry. The active anatase phase of nano titania has been synthesized by sol-gel and pulverization techniques to obtain particle sizes averaging around 11 nm. The nano semiconductor with a bandgap of 3.2 eV responds well to the UV source to liberate reactive oxygen species (ROS). Gram negative bacteria easily succumb to the ROS at a faster rate than gram-positive bacteria with an observable difference in the mode of attack. The use of analytical techniques revealed the release of peroxidized lipid (26 nmol mL(-1) ) and protein content (370 μg mL(-1)) with a K(+) ion concentration of 22 000 ppb on complete destruction of E. coli.     

Quantification of glycopeptides by multiple reaction monitoring liquid chromatography/tandem mass spectrometry

Protein glycosylation has a major influence on functions of proteins. Studies have shown that aberrations in glycosylation are indicative of disease conditions. This has prompted major research activities for comparative studies of glycoproteins in biological samples. Multiple reaction monitoring (MRM) is a highly sensitive technique which has been recently explored for quantitative proteomics. In this work, MRM was adopted for quantification of glycopeptides derived from both model glycoproteins and depleted human blood serum using glycan oxonium ions as transitions. The utilization of oxonium ions aids in identifying the different types of glycans bound to peptide backbones. MRM experiments were optimized by evaluating different parameters that have a major influence on quantification of glycopeptides, which include MRM time segments, number of transitions, and normalized collision energies. The results indicate that oxonium ions could be adopted for the characterization and quantification of glycopeptides in general, eliminating the need to select specific transitions for individual precursor ions. Also, the specificity increased with the number of transitions and a more sensitive analysis can be obtained by providing specific time segments. This approach can be applied to comparative and quantitative studies of glycopeptides in biological samples as illustrated for the case of depleted blood serum sample. Copyright ? 2012 John Wiley & Sons, Ltd.     

13X分子筛负载Fe催化剂上1,4-二氧六环在空气中完全氧化(英文)

采用浸渍法制备了不同Fe含量的13X分子筛负载的Fe催化剂(Fe/X13),运用N_2吸附-脱附法测得其BET比表面积和BJH孔径分布,采用X射线衍射、扫描电镜、程序升温还原和NH_3程序升温脱附法表征了该催化剂的织构性质.在固定床流动反应器中,以空气为氧化剂、在100-400℃范围内考察了Fe/X13催化剂上1,4-二氧六环的完全氧化反应性能,研究了反应温度、金属担载量和气体空速(GHSV)等条件对催化氧化降解二氧六环反应性能的影响,并在400℃测定了该催化剂反应50h的稳定性,结果表明,6 wt%Fe/13X催化剂表现出最高的催化性能,在400℃,GHSV=24000 h~(-1)的条件下,二氧六环转化率为97%,生成CO和CO_2的选择性达95%,降解产物还包括少量的乙醛、乙二醇-甲酸酯、乙二醇二甲酸、1,4-二氧六环-2醇、1,4-二氧六环-2酮及2-甲氧基1,3二氧戊环.基于这些经色谱-质谱联用仪检测出的产物,提出了可能的1,4-二氧六环降解机理。     

A facile method for the preparation of hexafluoroisopropanol functionalized derivatives using hexafluoroacetone trihydrate via a carbonyl-ene reaction

Hexafluoroacetone trihydrate was shown to undergo an efficient carbonyl-ene reaction with a variety of alkenes in the presence of molecular sieves under microwave heating and conventional heating producing hexafluoroisopropanol functionalized derivatives in high yields.     

An efficient chiral-pool synthesis of botryolide-E

An efficient stereoselective total synthesis of botryolide-E by a chiral-pool approach is described.     

Preparation and characterization of graphite nano-platelet (GNP)/epoxy nano-composite: Mechanical,electrical and thermal properties

Epoxy based polymer nano-composite was prepared by dispersing graphite nano-platelets (GNPs) using two different techniques: three-roll mill (3RM) and sonication combined with high speed shear mixing (Soni_hsm). The influence of addition of GNPs on the electrical and thermal conductivity, fracture toughness and storage modulus of the nano-composite was investigated. The GNP/epoxy prepared by 3RM technique showed a maximum electrical conductivity of 1.8 × 10⁻⁰³ S/m for 1.0 wt% which is 3 orders of magnitude higher than those prepared by Soni_hsm. The percentage of increase in thermal conductivity was only 11% for 1.0 wt% and 14% for 2.0 wt% filler loading. Dynamic mechanical analysis results showed 16% increase in storage modulus for 0.5 wt%, although the Tg did not show any significant increase. Single edge notch bending (SENB) fracture toughens (K_IC) measurements were carried out for different weight percentage of the filler content. The toughening effect of GNP was most significant at 1.0 wt% loading, where a 43% increase in K_IC was observed. Among the two different dispersion techniques, 3RM process gives the optimum dispersion where both electrical and mechanical properties are better.     

An efficient and simple method for the preparation of symmetrical disiloxanes from hydrosilanes by Lewis acid-catalyzed air oxidation

Symmetrical disiloxanes were prepared in high yields by air oxidation of mono, di, and trihydrosilanes under Lewis acid catalysis.     

Impact of A–D–A-Structured Dithienosilole- and Phenoxazine-Based Small Molecular Material for Bulk Heterojunction and Dopant-Free Perovskite Solar Cells

Herein, the synthesis of the novel acceptor–donor–acceptor (A–D–A)-structured small molecule Si-PO-2CN based on dithienosilole (DTS) as building block flanked by electron-rich phenoxazine (POZ) units, which are terminated with dicyanovinylene, is presented. Si-PO-2CN showed unique electrochemical and photophysical properties and has been successfully employed in perovskite solar cells (PSCs) as well as in bulk heterojunction organic solar cells (OSCs). The PSCs fabricated with dopant-free Si-PO-2CN as hole-transport material (HTM) exhibited a power conversion efficiency (PCE) of 14.1 % (active area=1.02 cm²). Additionally, a PCE of 5.6 % has been achieved for OSCs, which employed Si-PO-2CN as p-type donor material when blended with a [6,6]-phenyl C71 butyric acid methyl ester (PC₇₁BM) acceptor. The versatile application of Si-PO-2CN provides a pathway for further implementation of DTS-based building blocks in solar cells for designing new molecules.     

Efficient microwave-assisted synthesis of oximes from acetohydroxamic acid and carbonyl compounds using BF3·OEt2 as the catalyst

An efficient synthesis of oximes by reaction of carbonyls with acetohydroxamic acid using BF₃·OEt₂ as a catalyst is described.     

Insulin immobilized PCL‐cellulose acetate micro‐nanostructured fibrous scaffolds for tendon tissue engineering

Use of growth factors as biochemical molecules to elicit cellular differentiation is a common strategy in tissue engineering. However, limitations associated with growth factors, such as short half‐life, high effective physiological doses, and high costs, have prompted the search for growth factor alternatives, such as growth factor mimics and other proteins. This work explores the use of insulin protein as a biochemical factor to aid in tendon healing and differentiation of cells on a biomimetic electrospun micro‐nanostructured scaffold. Dose response studies were conducted using human mesenchymal stem cells (MSCs) in basal media supplemented with varied insulin concentrations. A dose of 100‐ng/mL insulin showed increased expression of tendon markers. Synthetic‐natural blends of various ratios of polycaprolactone (PCL) and cellulose acetate (CA) were used to fabricate micro‐nanofibers to balance physicochemical properties of the scaffolds in terms of mechanical strength, hydrophilicity, and insulin delivery. A 75:25 ratio of PCL:CA was found to be optimal in promoting cellular attachment and insulin immobilization. Insulin immobilized fiber matrices also showed increased expression of tendon phenotypic markers by MSCs similar to findings with insulin supplemented media, indicating preservation of insulin bioactivity. Insulin functionalized scaffolds may have potential applications in tendon healing and regeneration.