Design,synthesis and biological activity of some novel benzimidazole derivatives against Coxsackie virus B_3

A series of novel benzimidazole derivatives was synthesized and their anti-Coxsackie virus B_3(CVB_3) activity was evaluated in VERO cells.Compounds 9 and 10 exhibited better inhibitory activity than those of ribavirin(RBV) with IC_(50) values of 5.30 and 1.06μg/mL,respectively.     

A new ent-labdane eiterpenoid lactone from Andrographis paniculata

A new ent-labdane diterpenoid lactone with a new natural product was isolated from Andrographis paniculata. Their structures were elucidated on the basis of spectral evidences including 2D NMR.     

Highly effective direct synthesis of DMC from CH_3OH and CO_2 using novel Cu-Ni/C bimetallic composite catalysts

Novel Cu-Ni/C has been prepared and utilized as an efficient catalyst system in direct synthesis of DMC from CH3OH and CO2.     

Thermal degradation and isothermal crystalline behavior of poly（trimethylene terephthalate）

Poly(trimethylene terephthalate)(PTT) is an excellent fiber material.Its thermal degradation and isothermal crystalline behaviors were in this study investigated using thermogravimetric analysis(TGA),thermogravimetric analysis-Fourier transform infrared spectroscopy(TGA-FTIR) analysis,differential scanning calorimetry(DSC) and X-ray diffraction(XRD).The thermal degradation mechanism of PTT follows Mclafferty rearrangement principle.The PTTwithintrinsicviscosity(Ⅳ) of 0.74 dL/g has a maximum crystallinity...     

Influence of High Temperatures on PET-Concrete Properties

Lightweight aggregate is an important material in reducing the unit weight of concrete and it is essential in the construction of high-rise buildings; besides, the use of recycled PET bottles as lightweight aggregate in concrete is an effective contribution for environmental preservation. So, the objective of the present work is to study the flexural strength of PET-concrete and PET thermal degradation in the concrete, when the blends with 10 and 20 vol% of PET are exposed to different temperatures (200, 400, 600 °C). The flexural strength of PET-concrete exposed to a heat source is strongly dependent on the temperature, the water/cement ratio, as well as on the content and particle size of PET. Furthermore, the activation energy for PET degradation is affected by temperature, location of PET particles on the slabs and the water/cement ratio. A higher content of water gives rise to hydrolytic degradation on PET and a higher vapor pressure that increases the formation of cracks on the concrete. The values of activation energy are higher on the center of the slabs than on the surface, due to the poor heat conduction of concrete.     

Characterization of Biocatalysts Prepared with Thermomyces lanuginosus Lipase and Different Silica Precursors,Dried using Aerogel and Xerogel Techniques

The use of lipases in industrial processes can result in products with high levels of purity and at the same time reduce pollutant generation and improve both selectivity and yields. In this work, lipase from Thermomyces lanuginosus was immobilized using two different techniques. The first involves the hydrolysis/polycondensation of a silica precursor (tetramethoxysilane (TMOS)) at neutral pH and ambient temperature, and the second one uses tetraethoxysilane (TEOS) as the silica precursor, involving the hydrolysis and polycondensation of the alkoxide in appropriate solvents. After immobilization, the enzymatic preparations were dried using the aerogel and xerogel techniques and then characterized in terms of their hydrolytic activities using a titrimetric method with olive oil and by the formation of 2-phenylethyl acetate in a transesterification reaction. The morphological properties of the materials were characterized using scanning electron microscopy, measurements of the surface area and pore size and volume, thermogravimetric analysis, and exploratory differential calorimetry. The results of the work indicate that the use of different silica precursors (TEOS or TMOS) and different drying techniques (aerogel or xerogel) can significantly affect the properties of the resulting biocatalyst. Drying with supercritical CO₂ provided higher enzymatic activities and pore sizes and was therefore preferable to drying, using the xerogel technique. Thermogravimetric analysis and differential scanning calorimetry analyses revealed differences in behavior between the two biocatalyst preparations due to the compounds present.     

Non‐Invasive Salivary Electrochemical Quantification of Paraquat Poisoning Using Boron Doped Diamond Electrode

The present work describes the first electrochemical method for quantifying paraquat herbicide poisoning in human saliva samples. Paraquat shows two couples of well‐defined peaks in aqueous solution using a boron doped diamond (BDD) electrode. By using square wave voltammetry (SWV) technique under optimum experimental conditions, a linear analytical curve was obtained for paraquat concentrations ranging from 0.800 to 167 µmol L^?1, with a detection limit of 70 nmol L^?1. This method was applied to quantify paraquat spikes in human saliva samples and in two different water samples (tap and river). The recovery values obtained ranged from 83.0 to 104 % and 99.1 to 105 %, respectively, which highlight the accuracy of the proposed method.     

Phosphonate‐Modified UiO‐66 Brønsted Acid Catalyst and Its Use in Dehydra‐Decyclization of 2‐Methyltetrahydrofuran to Pentadienes

Phosphorus‐modified all‐silica zeolites exhibit activity and selectivity in certain Brønsted acid catalyzed reactions for biomass conversion. In an effort to achieve similar performance with catalysts having well‐defined sites, we report the incorporation of Brønsted acidity to metal–organic frameworks with the UiO‐66 topology, achieved by attaching phosphonic acid to the 1,4‐benzenedicarboxylate ligand and using it to form UiO‐66‐PO₃H₂ by post‐synthesis modification. Characterization reveals that UiO‐66‐PO₃H₂ retains stability similar to UiO‐66, and exhibits weak Brønsted acidity, as demonstrated by titrations, alcohol dehydration, and dehydra‐decyclization of 2‐methyltetrahydrofuran (2‐MTHF). For the later reaction, the reported catalyst exhibits site‐time yields and selectivity approaching that of phosphoric acid on all‐silica zeolites. Using solid‐state NMR and deprotonation energy calculations, the chemical environments of P and the corresponding acidities are determined.     

Base-base interactions in the minor groove of double-stranded DNA

A method has been developed for the synthesis of bisheaded nucleosides with thymine and adenine base moieties. We have demonstrated that, when incorporated in oligonucleotides, extrahelical A-T base interactions are possible when the bisheaded nucleosides are positioned in opposite strands of the duplex and are separated from each other by one regular base pair.