Bis‐benzimidazolium‐palladium system catalyzed Suzuki‐Miyaura coupling reaction of aryl bromides under mild conditions

Bis‐benzimidazolium salts were prepared successfully from commercially available and inexpensive o‐phenylenediamine through a series of simple reactions. The bis‐NHC‐Pd complexes prepared in situ can catalyze Suzuki‐Miyaura cross‐coupling reaction under very mild conditions in aqueous media with excellent yields. The efficiency of this reaction is demonstrated by its compatibility with a range of functional groups. Di‐ortho‐substituted biaryls could be accomplished in 89–99% yields. Moreover, the rigorous exclusion of air or moisture is not required in these transformations.     

Simple Method in Diagnosing Cancer Cells by a Novel Fluorescence Probe BMVC

Different cellular accumulations with distinct fluorescence properties of BMVC in cancer cells from normal cells allow us to establish a simple and economic method for the diagnosis of cancer cells. With using a light emitting diode to excite the BMVC molecule, microarray fluorescence analysis of a cell‐based glass chip provides an easy method towards the detection of a limited number of cancer cells.     

Meromorphic solutions of equations over non-Archimedean fields

In this paper, we give some conditions to assure that the equation P(X)=Q(Y) has no meromorphic solutions in all K, where P and Q are polynomials over an algebraically closed field K of characteristic zero, complete with respect to a non-Archimedean valuation. In particular, if P and Q satisfy the hypothesis (F) introduced by H. Fujimoto, a necessary and sufficient condition is obtained when deg P=deg Q. The results are presented in terms of parametrization of a projective curve by three entire functions. In this way we also obtain similar results for unbounded analytic functions inside an open disk.      

Electrical and interface state density properties of polyaniline–poly-3-methyl thiophene blend/p-Si Schottky barrier diode

We have formed conjugated polymeric aniline–thiophene organic material on p-Si substrate by adding polyaniline–poly-3-methyl thiophene blend solution in acetonitrile on top of a p-Si substrate and then evaporating the solvent. It has been seen that the forward bias current–voltage (I–V) characteristics of polyaniline–poly-3-methyl thiophene blend/p-Si/Al with a barrier height value of 0.60 eV and an ideality factor value of 3.37 showed rectifying behaviour at room temperature. The polyaniline–poly-3-methyl thiophene blend/p-Si/Al Schottky barrier diode showed non-ideal I–V behaviour with the value of ideality factor greater than unity that could be ascribed to the interfacial layer, interface states and series resistance. Furthermore, Cheung's functions and modified Norde's function were used to extract the diode parameters including ideality factor, barrier height and series resistance. It has been seen that there is a good agreement between the barrier height values from all methods. However, the values of series resistance obtained from Cheung's functions is higher than the values obtained from Norde's functions. The energy distribution of interface states density, determined from forward bias current–voltage (I–V) characteristic technique at room temperature, increases exponentially with bias from 2.81 × 10¹⁶ cm^?2 eV^?1 in (0.73–E_v) eV to 1.14 × 10¹⁷ cm^?2 eV^?1 in (0.48–E_v) eV.     

Swelling assisted photografting of itaconic acid onto sodium alginate membranes

Grafting of itaconic acid (IA) was achieved onto sodium alginate (NaAlg) membranes by using UV-radiation. Process was performed under nitrogen atmosphere and benzophenone (BP) was used as a photoinitiator. Membranes were preswelled before the polymerization process and ethanol was determined as the best swelling agent among the studied solvents. The effect of polymerization time, initiator and monomer concentrations on the grafting efficiency were investigated. The best conditions for optimum grafting were obtained with IA concentration of 1.0 M, a BP concentration of 0.1 M and a reaction time of 4 h at 25 °C. Under these conditions grafting efficiency for NaAlg-g-IA membranes was found to be 14% (w/w). To obtain further increase in grafting efficiency membranes were also preswelled in IA and BP solutions and polymerization was carried out at different temperatures after UV polymerization. Grafted membranes were characterized by using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Effect of grafting on membrane properties such as intrinsic viscosity and swelling percentage were also determined.     

A Note on Large Rainbow Matchings in Edge-coloured Graphs

A rainbow subgraph in an edge-coloured graph is a subgraph such that its edges have distinct colours. The minimum colour degree of a graph is the smallest number of distinct colours on the edges incident with a vertex over all vertices. Kostochka, Pfender, and Yancey showed that every edge-coloured graph on n vertices with minimum colour degree at least k contains a rainbow matching of size at least k, provided ${n\geq \frac{17}{4}k^2}$ . In this paper, we show that n ≥ 4k ? 4 is sufficient for k ≥ 4.     

Three hydrophobic amino acids in <Emphasis Type="Italic">Escherichia coli</Emphasis> HscB make the greatest contribution to the stability of the HscB-IscU complex

Background  

General iron-sulfur cluster biosynthesis proceeds through assembly of a transient cluster on IscU followed by its transfer to a recipient apo-protein. The efficiency of the second step is increased by the presence of HscA and HscB, but the reason behind this is poorly understood. To shed light on the function of HscB, we began a study on the nature of its interaction with IscU. Our work suggested that the binding site of IscU is in the C-terminal domain of HscB, and two different triple alanine substitutions ([L92A, M93A, F153A] and [E97A, E100A, E104A]) involving predicted binding site residues had detrimental effects on this interaction. However, the individual contribution of each substitution to the observed effect remains to be determined as well as the possible involvement of other residues in the proposed binding site.     

Plasma brominated polymer particles as grafting substrate for thiol‐terminated telomers

A combined surface activation and “grafting to” strategy was developed to convert divinylbenzene particles into weak cation exchangers suitable for protein separation. The initial activation step was based on plasma modification with bromoform, which rendered the particles amenable to further reaction with nucleophiles by introducing Br to a surface content of 11.2 atom‐%, as determined by X‐ray photoelectron spectroscopy. Grafting of thiol‐terminated glydicyl methacrylate telomers to freshly plasma activated surfaces was accomplished without the use of added initiator, and the grafting was verified both by reduction in bromine content and the appearance of sulfur‐carbon linkages, showing that the surface grafts were covalently bonded. Following grafting the attached glydicyl methacrylate telomer tentacles were further modified by a two‐step procedure involving hydrolysis to 2,3‐hydroxypropyl groups and conversion of hydroxyl groups to carboxylate functionality by succinic anhydride. The final material was capable of baseline separating four model proteins in 3 min by gradient cation exchange chromatography in a fully aqueous eluent.     

Radiation-Induced Reactions with Cellulose. XV. Effect of Mineral and Organic Acids on Grafting of Monomers Using Ionizing Radiation

The effect of a range of inorganic and organic acids on the radiation-induced grafting of styrene in methanol to cellulose is discussed using the simultaneous method. Sulfuric acid is the most effective acid for increasing the grafting yield, hydrochloric being the next most efficient. Acetic acid retards the copolymerization. Under the most favorable radiation conditions, inclusion of sulfuric acid (up to 1.1 M) produces a twentyfold increase in graft. The presence of mineral acid also 1) enhances the intensity of a Trommsdorff peak if already present in the grafting solution and 2) induces a peak if none were previously present without acid. A mechanism for the enhanced acid effects in these grafting reactions is proposed involving charge-transfer intermediates.     

A novel reagent for spectroscopic determination of Mo(VI)

A new reagent for spectrophotometric determination of Mo(VI) was developed utilizing micellar effects. For this purpose, differences in the ultraviolet and visible spectral properties of Mo(VI), gallic acid, L-serine, and their binary and ternary solutions were studied in the presence and absence of cationic, anionic, and non-ionic surface active agents. L-serine was observed to form binary complexes and a ternary complex with Mo(VI) and gallic acid below its isoelectric point. The maximum Mo(VI) sensitivity was exerted by the Mo(VI) + gallic acid + L-serine + hexadecyltrimethylammonium bromide system at pH of 4.5. This system was proposed for use in the spectrophotometric determination of Mo(VI) as a superior alternative to the Mo(VI) + gallic acid + hexadecyltrimethylammonium bromide system and to most of the instrumental analysis methods referred to in the literature. The mechanism of micellar effects was discussed on the basis of the spectral data obtained above and below the isoelectric point of L-serine and explained in terms of the molecular charge of the substrates and the surfactants.