A microfluidic glucose biofuel cell to generate micropower from enzymes at ambient temperature

A Y-shaped microfluidic channel is applied for the first time to the construction of a glucose/O₂ biofuel cell, based on both laminar flow and biological enzyme strategies. During operation, the fuel and oxidant streams flow parallel at gold electrode surfaces without convective mixing. At the anode, the glucose oxidation is performed by the enzyme glucose oxidase whereas at the cathode, the oxygen is reduced by the enzyme laccase, in the presence of specific redox mediators. Such cell design protects the anode from an interfering parasite reaction of O₂ at the anode and offers the advantage of using different streams of oxidant and fuel for optimal performance of the enzymes. Electrochemical characterizations of the device show the influence of the flow rate on the output potential and current density. The maximum power density delivered by the assembled biofuel cell reached 110 μW cm^?2 at 0.3 V with 10 mM glucose at 23 °C. The microfluidic approach reported here demonstrates the feasibility of advanced microfabrication techniques to build an efficient microfluidic glucose/O₂ biofuel cell device.     

Synthetic models for the zinc sites in the methionine synthases

The syntheses and molecular structures of a series of tetrahedral zinc complexes designed to model the active sites in Escherichia coli methionine synthases are reported. [PhTttBu]ZnBr (PhTttBu = phenyltris((tert-butylthio)-methyl)borate) was prepared and characterized crystallographically to provide entry into [S3]ZnX complexes. Metathesis with KSPh yielded the phenylthiolato complex, [PhTttBu]Zn(SPh), which represents a structural mimic of the homocysteine ligated form of the enzyme. Alternatively, [S2N]ZnX (X = Br, CH3, SPh) species were prepared using the new mixed-donor ligands, [Ph(pz)BttBu] (phenyl(pyrazolyl)bis((tert-butylthio)methyl)borate) and [Ph(pztBu)BttBu] (phenyl(3-tert-butylpyrazolyl)bis((tert- butylthio)methyl)borate). Protonolysis of [Ph(pztBu)-BttBu]Zn(CH3) by PhSH in toluene yielded [Ph(pztBu)BttBu]Zn(SPh), a synthetic analogue of the homocysteine ligated form of cobalamin-independent methionine synthase (Met E). The average Zn-S bond distance in [Ph-(pztBu)BttBu]Zn(SPh) of 2.37 A compares well with the EXAFS-derived distance of 2.31 A found in the homocysteine-bound form of Met E.     

Analysis of the influence of polymer viscosity on the dispersion of magnesium hydroxide in a polyolefin matrix

The dispersion of Mg(OH)₂ agglomerates at low concentration in a polymer melt was investigated in a transparent counter-rotating shear cell. The influence of the viscosity of the matrix, the initial agglomerate size and the infiltration of the matrix was evaluated. Mg(OH)₂ agglomerates have a low cohesion and a fractal structure. Two dispersive mechanisms already mentioned in the literature were identified: erosion and rupture. Critical conditions for rupture were measured and particle size analysis was performed in order to determine the kinetics of erosion. The infiltration of the matrix, which depends on the viscosity, was found to play a key role on dispersion mechanisms. In contrast to previous works, infiltration is more important with the high viscosity matrix. In infiltrated matrix, rupture was found to occur firstly through plastic deformation of the infiltrated agglomerate, and then the agglomerates split into small fragments. In the low viscosity matrix, fragments produced either by rupture or erosion are small aggregates.     

Antimicrobial activities of 1-phenyl-3-methyl-4-trichloroacetyl-pyrazolone: Experimental,DFT studies,and molecular docking investigation

The rate of bacterial resistance to antibiotics is faster than the rate of discovery of new antibiotic classes. However, development of novel compounds with similar behavior but with a better therapeutic action has posed a serious challenge to researchers. Therefore, discovering of new novel drugs is of great importance in combating health problems and improving the quality of human life. In this research, first principle density functional theory (DFT) along with molecular docking approach were utilized for the investigation of 1-phenyl-3-methyl-4-trichloroacetyl-pyrazolone-5 (HTcP) to address some factors that are linked to this phenomenon. The theoretical computations were carried out utilizing the Becke-3-Parameter-hybrid model of Lee-Yang-Parr (B3LYP) with the 6-31+G (d, p) basis set. The most active site of the studied compound was studied within the framework of molecular electrostatic potential (ESP) meanwhile the strength and nature of the bond was studied using quantum theory of atoms in molecules (QTAIM). The antibacterial activities of the title structure was tested in this study using three proteins, 4YNT, 4YNU, and 5UZ9, with the help of Bio – via discovery studio and Auto dock vina tool via molecular docking simulations. The compound had a higher binding energy with the 4YNT and 4YNU proteins (?7.7 kcal/mol). Also controlled model was used in the docking analysis which shows no much significant different between the modelled structure and the commercial drug Kanamycin. In addition, a computer simulation was used to predict the absorption, distribution, metabolism, excretion, and toxicity profiles of the compound under investigation (ADMET). The result obtained from the ADMET studies indicated that the structure under study has moderate antibacterial activities.     

Nonlinear instability of a viscous liquid jet

We investigate the weakly nonlinear temporal instability of an axisymmetric Newtonian liquid jet. Early nonlinear studies on the capillary instability of inviscid liquid jets were carried up to the third order contributions to the jet deformation and showed the nonlinear interaction between different modes. A recent study on the weakly nonlinear instability of planar Newtonian liquid sheets revealed the role of the liquid viscosity in the sheet stability behavior and showed a complicated influence [1]. Here, the instability of a liquid jet is examined as the axisymmetric counterpart of the sheet, in search for corresponding insight into the role of the liquid viscosity in the jet instability mechanism. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Identification of aerosol particle sources in semi‐rural area of Kwabenya,near Accra,Ghana, by EDXRF techniques

Small aerosol particles have for a long time been known to be harmful to humans, and are today regarded to cause a larger number of deaths than traffic accidents globally. Energy dispersive x‐ray fluorescence (EDXRF) is a well known method that has been used for identification of toxic as well as non‐toxic elements in the particles. The combination of elements will together with other information help to identify the sources and predict the effects of particles on environment and human health. The present work was conducted in Kwabenya, a suburb of the capital Accra of Ghana, which is frequently exposed to Harmattan dust from the Sahara–Sahel region. In total 171 filters each of PM2.5 and PM(2.5–10) were collected during 1 year. Levels of elements, black carbon (BC) and mass, were determined for both particle sizes. Principal component analysis (PCA) was performed on the datasets from Harmattan and non‐Harmattan periods. The daily average of PM10 was very high, 179 µg m^?3 and the BC contents were 4 µg m^?3. The presence of crustal elements was large in PM(2.5–10) as well as in PM2.5, and had a more than tenfold increase in PM(2.5–10) during the Harmattan period. Major characteristic elements for different sources were identified from correlation coefficients and regression analysis of the data. Sahara sand aerosol was the major source in both study periods, but influence from biomass burning, sea‐spray and metal industries was also observed. Copyright © 2009 John Wiley & Sons, Ltd.     

Constant electrical resistivity of Zn along the melting boundary up to 5 GPa

We measured the electrical resistivity of high purity Zn along the melting boundary, up to 5?GPa in a large volume press. The electrical resistivity remained constant on the melting boundary, as predicted in a thermodynamics-based model for simple metals. The effects of pressure and temperature on the electrical resistivity of the solid and liquid states are interpreted in terms of their antagonistic effects on the electronic structure of Zn. Within the error of measurements, our melting temperature data agree well with those of the previous studies. The electronic thermal conductivity was calculated from resistivity data using the Wiedemann–Franz law and shows a decrease with temperature in the solid state and an increase in the liquid state, with a large decrease on melting. Comparison of calculated electronic and measured total thermal conductivities indicates that the electronic component dominates over the phonon component in Zn.     

Experimental and computational modeling of the biological activity of benzaldehyde sulphur trioxide as a potential drug for the treatment of Alzheimer disease

Alzheimer's disease is a major public brain infection that has resulted in many deaths as revealed by the world health organization (WHO). Conventional Alzheimer treatments such as chemotherapy, surgery, and radiotherapy are not very effective and are usually associated with several adverse effects. Therefore, it is necessary to find new therapeutic approach that completely treat Alzheimer disease without much side effects. In this research work, we report the experimental and in silico molecular modeling of the biological activity of a novel azo-based compound as potential candidate for Alzheimer's disease. The synthesized compound was obtained by coupling reactions with 4-amino-3-nitrobenzaldehyde. Suitable purification and characterization techniques were employed and density functional theory (DFT) computational approach as well as in-silico molecular modeling has been employed to assess the electronic properties and anti-Alzheimer's potency. Suitable protein targets often regarded as target sites for most therapeutic vaccines for the said disease (4EY7, 1QTN, 4EY7, and 6EUE) have been selected for molecular docking investigation. For proper valuation of the drug candidacy, molecular docking studies were compared with conventional Alzheimer drug (donepezil). Also, the spectroscopic properties of the studied compound were investigated and compared with experimental data. Our findings show that the studied structure is relatively stable and expresses greater binding affinities of ?6.10, ?9.01, ?5.90, and ?11.20 kcal/mol than donepezil which had binding affinities of: 5.30, ?6.30, 5.90, and ?10.70 kcal/mol for each protein target. Thus, demonstrating the efficacy of the studied compound as potential candidate for Alzheimer's disease.     

In Vitro Antioxidant and Anticancer Properties of Various E. senegalensis Extracts

Although Erythrina senegalensis is a plant widely used in traditional medicine in sub-Saharan Africa, its biological properties have been poorly investigated to date. We first characterized by conventional reactions the composition of several stem bark extracts and evaluated in acellular and cellular assays their pro- or antioxidant properties supported by their high phenolic and flavonoid content, particularly with the methanolic extract. The pro- or antioxidant effects observed did not correlate with their IC₅₀ concentrations against five cancer cell lines determined by MTT assay. Indeed, the CH₂Cl₂ extract and its ethyl acetate (EtOAc) subfraction appeared more potent although they harbored lower pro- or antioxidant effects. Nevertheless, at equipotent concentration, both extracts induced ER- and mitochondria-derived vacuoles observed by fluorescent microscopy that further led to non-apoptotic cell death. LC coupled to high resolution MS investigations have been performed to identify chemical compounds of the extracts. These investigations highlighted the presence of compounds formerly isolated from E. senegalensis including senegalensein that could be retrieved only in the EtOAc subfraction but also thirteen other compounds, such as 16:3-Glc-stigmasterol and hexadecanoic acid, whose anticancer properties have been previously reported. Nineteen other compounds remain to be identified. In conclusion, E. senegalensis appeared rich in compounds with antioxidant and anticancer properties, supporting its use in traditional practice and its status as a species of interest for further investigations in anticancer drug research.