An integrated platform for gas-diffusion separation and electrochemical determination of ethanol on fermentation broths

An integrated platform was developed for point-of-use determination of ethanol in sugar cane fermentation broths. Such analysis is important because ethanol reduces its fuel production efficiency by altering the alcoholic fermentation step when in excess. The custom-designed platform integrates gas diffusion separation with voltammetric detection in a single analysis module. The detector relied on a Ni(OH)₂-modified electrode. It was stabilized by uniformly depositing cobalt and cadmium hydroxides as shown by XPS measurements. Such tests were in accordance with the hypothesis related to stabilization of the Ni(OH)₂ structure by insertion of Co²⁺ and Cd²⁺ ions in this structure. The separation step, in turn, was based on a hydrophobic PTFE membrane, which separates the sample from receptor solution (electrolyte) where the electrodes were placed. Parameters of limit of detection and analytical sensitivity were estimated to be 0.2% v/v and 2.90 μA % (v/v)⁻¹, respectively. Samples of fermentation broth were analyzed by both standard addition method and direct interpolation in saline medium based-analytical curve. In this case, the saline solution exhibited ionic strength similar to those of the samples intended to surpass the tonometry colligative effect of the samples over analyte concentration data by attributing the reduction in quantity of diffused ethanol vapor majorly to the electrolyte. The approach of analytical curve provided rapid, simple and accurate analysis, thus contributing for deployment of point-of-use technologies. All of the results were accurate with respect to those obtained by FTIR method at 95% confidence level.     

Design and synthesis of two epoxide derivatives from 3-ethynylaniline

For several years ago, several epoxide derivatives have been prepared using different methods; however, some protocols use reagents which could be expensive and require specials conditions. The aim of this investigation was to prepare two new epoxide-derivatives from 3-ethynylaniline using some reactions such as oximation, acetylation, 2 + 2 addition, functionalized chloroamides, and epoxidation via Darzens reaction. The chemical characteristics of epoxide derivatives were determinate through a spectroscopic and spectrometric analysis. In conclusion, it is noteworthy that the reactions used in this study do not involve expensive reagents or special conditions for the synthesis of epoxide derivatives.     

Production of secondary drops during the single water drop impact onto a plane water surface

The normal impact of single water drops onto a plane water surface was studied experimentally to reveal the amount of secondary drops produced from the rim of crown-like interfacial structure. Within the experimental ranges tested, the ratio of the total mass of secondary drops to the mass of primary drop was approximately within 0–1 and correlated well as the function of dimensionless parameter K that consisted of the impact Weber number We and the Ohnesorge number Oh (K = We Oh ^−0.4). The dependences of the number and the mean diameter of secondary drops on K and dimensionless film thickness were also investigated.     

Synthesis of Methyl 6′-Deoxy- and 6′-Thiolactosaminides and Their Inhibitory Activity Toward CMP-NeuNAc:D-galactoside-(2→6)-α-D-sialyltransferase

Abstract

Specific inhibitors of glycosyltransferases have become of interest1 not only for investigation of carbohydrate-participating cell-surface phenomena but also for practical use such as chemotherapeutic reagents. Glycosyltransferases catalyze the transfer of glycosyl moieties from nucleotide donors to oligosaccharide acceptors. Therefore, two kinds of substrate-analog inhibitors are possible. The donor analogs have been rather well studied, but are not specific. On the other hand, glycosyltransferases have in general smct acceptor specifkity. Recently, acceptor analogs which inhibit the corresponding glycosyltransferases were reported^2-5 and as expected were acceptor-specific inhibitors.     

Partially bio‐based tri‐ and hexaallyl monomers: Synthesis from naturally occurring myo‐inositol and polyaddition with dithiols

myo‐Inositol, a naturally occurring cyclic hexaol, was converted to 2,4,6‐tri‐O‐allyl‐myo‐inositol and 1,2,3,4,5,6‐hexa‐O‐allyl‐myo‐inositol. Polyaddition of the former product, a tri(allyl ether) bearing three hydroxyl groups, with dithiols yielded the corresponding networked polymers. Their glass transition temperatures (T_gs) were higher than those of networked polymers formed by the polyaddition of 1,3,5‐tri‐O‐methyl‐2,4,6‐tri‐O‐allyl‐myo‐inositol. This implied the reinforcement of the networks by hydrogen bonding between the hydroxyl groups. Polyaddition of the latter product, a hexa(allyl ether), with dithiols yielded the corresponding networked polymers with much higher T_gs than those of all of the aforementioned networked polymers. This implied that efficient use of the hexafunctional monomer leads to the formation of more densely crosslinked polymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1524–1529     

Influence of pH on the incorporation and growth of Pb<Subscript>2</Subscript>CrO<Subscript>5</Subscript> crystallites in silica matrix

Pb₂CrO₅ nanoparticles were embedded in an amorphous SiO₂ matrix by the sol–gel process. The pH and heat treatment effects were evaluated in terms of structural, microstructural and optical properties from Pb₂CrO₅/SiO₂ compounds. X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), and diffuse reflectance techniques were employed. Kubelka–Munk theory was used to calculate diffuse reflectance spectra that were compared to the experimental results. Finally, colorimetric coordinates of the Pb₂CrO₅/SiO₂ compounds were shown and discussed. In general, an acid pH initially dissolves Pb₂CrO₅ nanoparticles and following heat treatment at 600 °C crystallized into PbCrO₄ composition with grain size around 6 nm in SiO₂ matrix. No Pb₂CrO₅ solubilization was observed for basic pH. These nanoparticles were incorporated in silica matrix showing a variety of color ranging from yellow to orange.     

Development of a Carbon Paste Electrode for Lactate Detection Based on Meldola’s Blue Adsorbed on Silica Gel Modified with Niobium Oxide and Lactate Oxidase

A reagentless amperometric biosensor sensitive to lactate was developed. The sensor employs a carbon paste electrode modified with lactate oxidase (LOx) and Meldola’s Blue (MB) adsorbed on silica gel coated with niobium oxide. The dependence on the biosensor response was investigated in terms of pH, supporting electrolyte, ionic strength, lactate oxidase (LOx) amounts and applied potential. The biosensor showed an excellent operational stability (96 % of the activity was maintained after 150 determinations) and storage stability (allowing measurements for more than 1.5 months, when stored in a refrigerator). The proposed biosensor also presented good sensitivity allowing lactate quantification at levels down to 6.5×10^?7 mol L^?1. Moreover, the biosensor showed a good linear response range (from 0.1 to 5.0 mmol L^?1 for lactate). Lactate analysis in biological samples such as blood was also performed. The precision of the data obtained by the proposed biosensor showed reliable results for real complex matrices.     

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