Novel monofunctional and bifunctional boronic acid‐functionalized squarylium dyes as precolumn and on‐column labels for protein analysis by capillary electrophoresis with laser‐induced fluorescence

This article presents a continuous capillary electrophoresis with laser‐induced fluorescence (CE‐LIF) following spectral studies of the noncovalent interactions between novel Squarylium Boronic Acid 4 (SQ‐BA4) & Squarylium Diboronic Acid 2 (SQ‐DBA2) squarylium dyes and human serum albumin (HSA). Two protocols were used wherein the on‐column‐labeling protocol was found to be more sensitive than the precolumn one by showing a better enhancement in the peak area of the HSA–dye complex besides lower limits of detection (LODs) for HSA. Also, stability studies were conducted with or without HSA using precolumn‐labeling mode over one week exhibiting the superiority of SQ‐BA4 to SQ‐DBA2. Then, a mixture containing three model proteins, HSA, β‐lactoglobulin B, and transferrin, was labeled on‐column with both dyes and completely resolved by CE‐LIF after optimization of several parameters. Both dyes provided lower LODs for HSA than those of β‐lactoglobulin B and transferrin with higher sensitivities. In addition, the SQ‐BA4 dye showed again greater sensitivities with all the three proteins than SQ‐DBA2.     

Catalytic comparison of various polar Zn(II)-Schiff base complexes and VO(II)-Schiff base complexes in (ep)oxidation processes of 1,2-cyclohexene and cyclohexane

Research on Chemical Intermediates - The reactivity of Zn2+ and VO2+ ions towards pyridinyl Schiff bases, in the absence or presence of a p-sodium sulfonate group (HPSNa and HPS, respectively),...     

Reactive intermediates in the reaction of hydrazinecarbothioamides with 2-(bis(methylthio)methylene)malononitrile and ethyl 2-cyano-3,3-bis(methylthio)acrylate

Research on Chemical Intermediates - The reaction of N-substituted hydrazinecarbothioamides with both 2-(bis(methylthio)methylene)malononitrile and ethyl 2-cyano-3,3-bis(methylthio)acrylate...     

Electrospun EGNPs reinforced precursor carbon nanofibril composites by using RSM

Response surface methodology (RSM),based on five‐level, four variable Box‐Benkhen technique was investigated for modeling the average fiber diameter of electrospun polyacrylonitrile (PAN) nanofibers. The four important electrospinning parameters were studied including applied voltage (kV), Berry's number, deposition distance from nozzle to collector (cm), and spinning angle (? in degree). The measured fiber diameters were in a good agreement with the predicted results by using RSM technique. High‐regression coefficient between the variables and the response (R² = 87.74%) indicates excellent evaluation of experimental data by second‐order polynomial regression model. The optimum PAN average fiber diameters of 208 and 37‐nm standard deviation were collected at 19 kV, Berry's number = 10, 25^° spinning angle, and 16‐cm deposition distance. The PAN/N,N‐dimethylformamide (DMF) polymer solution with the optimum weight concentration (10 wt.%) was selected to study the effect of dispersing exfoliated graphite nanoplatelets (EGNPs) in PAN/DMF solution on the electrospun EGNP/PAN fibril composite diameter. Five different EGNPs weight concentrations (2, 4, 6, 8, and 10 wt.%) were dispersed in the optimized PAN/DMF polymer solution. Morphology of EGNPs/PAN fibril composites and its distribution were investigated by scanning electron microscopy (SEM) to show the minimum fiber diameter for the above‐mentioned 5 wt. % of EGNPs. A minimum fibril composite diameter of 182 nm was obtained at 10 wt.% of EGNPs. Morphological characteristics of electrospun fibers and their distribution were tested by Raman spectroscopy, SEM, differential light scattering, and high‐resolution transmission electron microscopy.     

Properties of ethylene propylene diene rubber/white and black filler composites cured by gamma radiation in presence of sorbic acid

The effect of incorporating sorbic acid (SA), an echo-friendly curing agent, and silica or carbon black (CB) filler, as well as gamma irradiation on the physico-chemical, mechanical and thermal properties of ethylene propylene diene monomer rubber (EPDM) was investigated. The results indicated that the developed composites revealed improvement in the studied parameters over the untreated samples. Filler incorporation into rubber matrix has been proven a key factor in enhancing the swelling resistance, tensile strength and thermal properties of the fabricated composites. The improvement in tensile strength and modulus was attributed to better interfacial bonding via SA. Alternatively, a comparison was established between the performance of the white and black fillers. The utmost mechanical performance was reported for the incorporated ratios 10 phr SA and 40 phr white filler into a 50 kGy irradiated composite. Meanwhile, the incorporation of CB yielded better thermally stable composites than those filled with silica at similar conditions.     

Pyrazoles and Isoxazoles Based Sulfanilamide and Phenazone as Antimicrobial Agents: Synthesis and Biological Activity

New pyrazole and pyridine derivatives have been synthesized from sulfanilamide and phenazone via diazotization and coupling with a wide range of α-CH acids followed by heterocyclization with hydrazine derivative, hydroxylamine and cyanoacetamide. The antimicrobial tests of the products demonstrate high to moderate activity against Gram (?ve) bacteria and the tested fungi. No positive action of the products is observed against Gram (+ve) bacteria.

     

Multicomponent access to novel proline/cyclized cysteine tethered monastrol conjugates as potential anticancer agents

The versatility of multicomponent Biginelli’s reaction is exploited in the development of proline and cyclized cysteine tethered conjugates of monastrol, a kinesin Eg5 inhibitor. Ten new conjugates are synthesized focusing on structural replacement of the ester moiety (C-5 position) of the monastrol backbone with amino acid based amide moieties. On cytotoxic evaluation, conjugate 24 has shown promising in vitro cytotoxic activity against leukemia. Molecular docking studies revealed that the conjugates 19 and 24 exhibit better interaction at kinesin Eg5 receptor compared to monastrol. Moreover, computational calculations and predictions of important molecular properties suggest that these new amino acid based conjugates could be further improved to provide potential anticancer agents.     

Control of combined convection in a nanofluid-filled lid-driven closed space via rectangular bar in the presence of magnetic field

Journal of Thermal Analysis and Calorimetry - In the present study, a computational work has been done to see the heat transfer, fluid flow and temperature distribution in a lid-driven cavity due...     

Characterization and evaluation of Nafion HP JP as proton exchange membrane: transport properties,nanostructure, morphology,and cell performance

Journal of Solid State Electrochemistry - In this study, a novel membrane (Nafion HP JP) was studied and investigated intensively for use as a proton exchange membrane for fuel cell. A standard...     

Negative Charging of Au Nanoparticles during Methanol Synthesis from CO2/H2 on a Au/ZnO Catalyst: Insights from Operando IR and Near‐Ambient‐Pressure XPS and XAS Measurements

The electronic and structural properties of Au/ZnO under industrial and idealized methanol synthesis conditions have been investigated. This was achieved by kinetic measurements in combination with time‐resolved operando infrared (DRIFTS) as well as in situ near‐ambient pressure X‐ray photoelectron spectroscopy (NAP‐XPS) and X‐ray absorption near‐edge spectroscopy (XANES) measurements at the O K‐edge together with high‐resolution electron microscopy. The adsorption of CO during the reaction revealed the presence of negatively charged Au nanoparticles/Au sites during the initial phase of the reaction. Near‐ambient‐pressure XPS and XANES demonstrate the build‐up of O vacancies during the reaction, which goes along with a substantial increase in the rate of methanol formation. The results are discussed in comparison with previous findings for Cu/ZnO and Au/ZnO catalysts.