Vibrational spectroscopic and density functional theory studies of chloranil-imidazole interaction

The present work reports vibrational spectra and density functional theory calculations for chloranil, imidazole and their complexes. The experimentally observed infrared and Raman bands have been assigned with the help of calculated vibrational frequencies and potential energy distribution analysis. Some bands of chloranil and imidazole have been found to shift on the complex formation due to partial electronic charge transfer from imidazole to chloranil. The charge transfer between these molecules is also corroborated by the electronic absorption spectroscopy and calculations. The theoretical values of the interaction energy of various possible chloranil-imidazole interactions suggest that the two molecules interact preferably via N and H atoms of imidazole and CO group of chloranil with their molecular planes almost perpendicular to each other.     

Disruption of urogenital biofilms by lactobacilli

The process that changes a relatively sparse vaginal microbiota of healthy women into a dense biofilm of pathogenic and potentially pathogenic bacteria is poorly understood. Likewise, the reverse step whereby an aberrant biofilm is displaced and returns to a healthy lactobacilli dominated microbiota is unclear. In order to study these phenomena, in vitro experiments were performed to examine the structure of biofilms associated with aerobic vaginosis, urinary tract infections, and bacterial vaginosis (BV). Uropathogenic Escherichia coli were able to form relatively thin biofilms within five days (6 μm height), while Atopobium vaginae and Gardnerella vaginalis formed thicker biofilms 12 μm in height within two days. Challenge of E. coli biofilms with lactobacilli did not result in pathogen displacement. However, the resulting thicker lactobacilli infused biofilms, caused significant E. coli killing. E. coli biofilms challenged with secreted products of L. rhamnosus GR-1 caused a marked decrease in cell density, and increased cell death. Similarly challenge of BV biofilms with lactobacilli infiltrated BV biofilms and caused bacterial cell death. Metronidazole produced holes in the biofilm but did not eradicate the organisms. The findings provide some evidence of how lactobacilli probiotics might interfere with an aberrant vaginal microbiota, and strengthen the position that combining probiotics with antimicrobials could better eradicate pathogenic biofilms.     

Orange Dye Removal Efficiency by Few-layer Graphene: an Investigation by UV-Vis Spectroscopy

Optics and Spectroscopy - Nowadays, few-layer graphene (FLG) has been introduced as a new type of adsorbent. In this research, the orange dyes including, methyl orange (MO) as an industrial dye and...     

Proposal of an infrared electro-optic switch based on grapheme–silicone–graphene metamaterial with electrically dynamic tunability

Optical Review - The electrically dynamic tunability of a proposed metamaterial switch based on graphene–silicene–graphene heterogeneous structure is theoretically investigated in the...     

An efficient regioselective sonochemical synthesis of novel 4-aryl-3-methyl-4,5-dihydro-1H-pyrazolo[3,4-b]pyridin-6(7H)-ones

An efficient ultrasound-assisted preparation of a series of novel 4-aryl-3-methyl-4,5-dihydro-l//-pyrazolo[34-b]pyridin-6(7H)ones via the reaction of 5-amino-3-methyl-1H-pyrazole,Meldrum’s acid and various arylaldehydes using one-pot three-component approach is described.This rapid method produced the products in short reaction times(3-4 min) and excellent yields(87-95%).     

High-resolution analyses of cell fusion dynamics in a biochip

In this study, we analyzed the electrofusion of two cells in a biochip that has been developed to perform the capture by dielectrophoresis and the electrofusion of pairs of cells. The good transparency of the microsystem allowed analyzing the details of the fusion events. By staining one of the cells, the mixing of the two cytosols could be observed during the electrofusion experiment. We show for the first time the rapidity of the mixing of the two cytosols: less than 5 s under our experimental conditions. By comparing these experimental results to a numerical simulation, we found that the rate of this phenomenon is compatible with a diffusion-only mechanism, showing that during the fusion, the two cell membranes in contact are affected by very rapid structural changes and do not limit the exchange of the cytosols between the two cells. A point of interest is the use of dielectric structures to concentrate the electric field and of positive dielectrophoresis to capture cells in the area where the electric field is more intense. This technique allows the increase of the cell-to-cell contact and limits cell cytosol leakages during the fusion process.     

Removal, preconcentration and spectrophotometric determination of U(VI) from water samples using modified maghemite nanoparticles

Arsenazo III modified maghemite nanoparticles (A-MMNPs) was used for removing and preconcentration of U(VI) from aqueous samples. The effects of contact time, amount of adsorbent, pH and competitive ions was investigated. The experimental results were fitted to the Langmuir adsorption model in the studied concentration range of uranium (1.0 × 10^?4–1.0 × 10^?2 mol L^?1). According to the results obtained by Langmuir equation, the maximum adsorption capacity for the adsorption of U(VI) on A-MMNPs was 285 mg g^?1 at pH 7. The adsorbed uranium on the A-MMNPs was then desorbed by 0.5 mol L^?1 NaOH solution and determined spectrophotometrically. A preconcentration factor of 400 was achieved in this method. The calibration graph was linear in the range 0.04–2.4 ng mL^?1 (1.0 × 10^?10–1.0 × 10^?8 mol L^?1) of U(VI) with a correlation coefficient of 0.997. The detection limit of the method for determination of U(VI) was 0.01 ng mL^?1 and the relative standard deviation (R.S.D.) for the determination of 1.43 and 2.38 ng mL^?1 of U(VI) was 3.62% and 1.17% (n = 5), respectively. The method was applied to the determination of U(VI) in water samples.     

Reaction kinetics of a novel thermoset nanocomposite: the glycerol diglycidyl ether/3,3-dimethylglutaric anhydride/nano-Al2O3 system

Abstract  

The curing behavior of the glycerol diglycidyl ether/3,3-dimethylglutaric anhydride/nano-alumina system was examined using a dynamic differential scanning calorimetry technique. The activation energy of the system was calculated using the Kissinger, Ozawa, Barrett, and two-parameter Sestak–Berggren models. Under the assumption of a constant activation energy and an autocatalytic mechanism, the activation energy, frequency factor, and total order of reaction were computed. The theoretical reaction rate was also calculated and compared to the experimental results. Good agreement was seen between the experimental and calculated data confirming the autocatalytic mechanism. The effect of triethylamine concentration on the reaction rate was clarified using the Barrett method. Fourier transform infrared spectroscopy (FT-IR) spectroscopy was used to verify the formation of internal ester groups. Scanning electron microscopy (SEM) and X-ray mapping analyses revealed that the nanofiller was homogeneously distributed in the continuous phase.     

硅胶键合的N-丙基三亚乙基四胺氨基磺酸作为可回收固体酸催化剂催化合成2-氨基-4,6-二芳基烟腈(英文)

A simple and efficient procedure for the preparation of silica-bound N-propyl triethylenetetramine sulfamic acid(SBPTETSA) by the reaction of silica-bound N-propyl triethylenetetramine(SBPTET) with chlorosulfonic acid in chloroform is described.Silica-bound N-propyl triethylenetetramine sulfamic acid was employed as a recyclable catalyst for the synthesis of 2-amino-4,6-diarylnicotinonitriles from the multi-component reaction of an acetophenone derivative,an aromatic aldehyde,malononitrile,and ammonium acetate under solvent-free conditions at 100 °C.The heterogeneous catalyst was recycled for five consecutive runs in the optimized multi-component reaction of 4-chloroacetophenone,4-chloroenzaldehyde,malononitrile,and ammonium acetate without significant loses to its catalytic activity.     

Highly cis‐Diastereoselective Synthesis of Coumarin‐Based 2,3‐Disubstituted Dihydrobenzothiazines by Organocatalysis

An efficient and organocatalyzed asymmetric reaction of phenacyl halides with coumarin‐based dihydrobenzothiazoles was developed to afford cis‐2,3‐disubstituted 3,4‐dihydro‐2H‐benzothiazines. This method provides a one‐step and highly diastereoselective route to a wide variety of coumarin‐based 3,4‐dihydro‐2H‐benzothiazines using the cheap and commercially available Cinchona alkaloid quinine hydrochloride.