Spectroscopic and optical studies on pure and doped single crystals of sulphate-mixed L-arginine phosphate monohydrate--a nonlinear optical crystal

Single crystals of pure and transition metal ions (Cu(2+) and VO(2+))-doped L-arginine sulpho phosphate monohydrate (sulphate-mixed L-arginine phosphate monohydrate, abbreviated as LASP) have been grown by solvent evaporation of the saturated aqueous solution at room temperature and characterized by single-crystal XRD, FT-IR, UV-Vis-NIR and EPR (single-crystal rotation) spectral studies. Kurtz powder technique shows an enhanced second harmonic generation (SHG) efficiency for LASP and its doped analogues than pure LAP. The EPR studies on LASP:VO(2+) reveal that the in-plane sigma-bonding is moderately covalent and the out-of-plane pi-bonding is highly covalent, which could be attributed to the cause of enhanced powder efficiency.     

Micro-total analysis system for virus detection: microfluidic pre-concentration coupled to liposome-based detection

An integrated microfluidic biosensor is presented that combines sample pre-concentration and liposome-based signal amplification for the detection of enteric viruses present in environmental water samples. This microfluidic approach overcomes the challenges of long assay times of cell culture-based methods and the need to extensively process water samples to eliminate inhibitors for PCR-based methods. Here, viruses are detected using an immunoassay sandwich approach with the reporting antibodies tagged to liposomes. Described is the development of the integrated device for the detection of environmentally relevant viruses using feline calicivirus (FCV) as a model organism for human norovirus. In situ fabricated nanoporous membranes in glass microchannels were used in conjunction with electric fields to achieve pre-concentration of virus–liposome complexes and therefore enhance the antibody–virus binding efficiency. The concentrated complexes were eluted to a detection region downstream where captured liposomes were lysed to release fluorescent dye molecules that were then quantified using image processing. This system was compared to an optimized electrochemical liposome-based microfluidic biosensor without pre-concentration. The limit of detection of FCV of the integrated device was at 1.6 × 10⁵ PFU/mL, an order of magnitude lower than that obtained using the microfluidic biosensor without pre-concentration. This significant improvement is a key step toward the goal of using this integrated device as an early screening system for viruses in environmental water samples.     

子半理想环

本文提出了环论中的一个新概念：子半理想，得到了群环为子半理想环的一个充要条件。     

Synthesis, characterization and pharmacologically active sulfamethoxazole polymers

Three anti-microbial pharmaceutical drugs were synthesized from two different synthetic routes. 4-acrylamido-N-(5-methyl-3-isoxazolyl)benzenesulfonamide (AMBS) and 4-methacrylamido-N-(5-methyl-3-isoxazolyl)benzenesulfonamide (MMBS) were prepared by reacting acryloyl chloride and methacryloyl chloride with 4-amino-N-(5-methyl-3-isoxazolyl)benzenesulfonamide in the presence of triethylamine. N-[4-sulfamido-N-(5-methyl-3-isoxazolyl)phenyl]maleimide (SMPM) was prepared by reacting maleic anhydride with 4-amino-N-(5-methyl-3-isoxazolyl)benzenesulfanamide. These monomers (AMBS, MMBS and SMPM) were polymerized using BPO as a free radical initiator. The pharmacological activity of SMPM compound depends on the functional group in the structure and small structural changes has resulted in higher pharmacological activity of sulfamethoxazole. Thus, maleimide polymer drug conjugate showed greater anti-microbial activity when compared with that of the native drug.     

论环{R×G×S}

本文定义了一个新的代数系｛Ｒ×Ｃ×Ｓ｝这是一个有环结构的自由Ｒ－模，并讨论了结构性质与Ｒ的性质．     

Effect of hydroxypropyl-β-cyclodextrin on the electrochemical oxidation and polymerization of 3,4-ethylenedioxythiophene

The electrochemical oxidation of 3,4-ethylenedioxythiophene (EDOT) on platinum is studied in electrolyte solutions containing hydroxypropyl-β-cyclodextrin (HP-β-CD). HP-β-CD is found to increase the solubility of EDOT up to a concentration of 0.026 M in aqueous solutions. Addition of HP-β-CD (0.1 M) produces a slight red shift of the EDOT main absorption band from 254.9 to 257.7 nm and an increase of the HP-β-CD concentration decreases the absorption coefficient, _max to 6150 l mol⁻¹ cm⁻¹ in the UV–vis region, indicating complex formation. The cyclic voltammetric response of EDOT in 0.1 M aqueous LiClO₄ solutions consists of an ill-defined wave (P₁) and an adsorption peak (P₂). Contrary to the case of oxidation in acetonitrile medium, a post-peak is observed in the voltammograms of EDOT electro-oxidation in aqueous LiClO₄ solutions due to the adsorption of the oxidized EDOT species. A gradual reduction of the peak current of P₂ with increasing [HP-β-CD] and its total disappearance at high [HP-β-CD] suggest complex formation between HP-β-CD and EDOT√⁺ and also the peak P₂ to be due to adsorption of EDOT√⁺ species. The experiments intended to show the effect of ‘pre-adsorbed’ HP-β-CD on EDOT oxidation led to the conclusion that adsorbed HP-β-CD also solubilizes EDOT at the electrode surface. The CV behaviour of EDOT in HP-β-CD is discussed in comparison with that in sodium dodecylsulfate micellar solutions. Addition of increasing amounts of HP-β-CD shifts P₁ positively and P₂ negatively while also suppressing P₂ totally and reducing the peak current of P₁ to a significant extent. At a higher concentration of HP-β-CD, viz. 0.05 M, a peak appears at 1.29 V as a result of the above two opposing effects of CD on the peak potentials of P₁ and P₂. This resultant peak (P_composite) is more positive relative to the position of P₁ observed in the absence of HP-β-CD. The positive shift of the peak and peak current reduction indicate that EDOT (or an oxidized EDOT species) possibly interacts with the outer nucleophilic part of HP-β-CD. The electro-oxidation processes occurring at P₁ and P₂ are explained using an oligomeric approach, in which the electrochemical reactions are coupled to chemical reactions or adsorption of the oxidized species. Potential cycling of the platinum electrode in solutions containing 0.026 M EDOT+0.05 M HP-β-CD+0.1 M LiClO₄ between −0.5 and 1.2 V yields an adherent and smooth polymer film of poly(ethylenedioxythiophene), as shown in the SEM examination. In situ resistance measurements carried out with the polymer films in the electroactive region show a minimum resistance in the potential range of 0.3–0.4 V. Even the electrochemically-reduced films are found to possess some residual electrical conductivity.     

The first total synthesis of (±)-lagopodin A

The first total synthesis of (±)-lagopodin A and a formal total synthesis of enokipodins A and B is described. The requisite precursors containing two vicinal quaternary carbon atoms were assembled employing Claisen rearrangement and an RCM reaction as key steps starting from 2,5-dimethoxy-4-methylacetophenone.