Effects of Fructose and Temperature on the Micellization of a Cationic Gemini Surfactant,Pentanediyl-1,5-bis(dimethylcetylammonium) Bromide in Aqueous Solutions

By the conductivity measurements the effects of fructose and temperature (293–308 K) on the micellization of a cationic gemini surfactant (GS), pentanediyl-1,5-bis(dimethylcetylammonium) bromide in aqueous solutions have been investigated. The critical micelle concentration (CMC) of GS was measured at the different temperatures and fructose concentrations. An increasing trend of the CMC values is with addition of fructose. With increasing temperature, the CMC values are in a similar increasing trend. The CMC of GS by dye solubilization method at room temperature have been determined. The standard Gibbs energy, enthalpy and entropy of GS micellization have been evaluated. From these thermodynamic parameters, it was found that in presence of fructose, the stability of the GS aqueous solutions decreases.     

Autoacetylation induced specific structural changes in histone acetyltransferase domain of p300: probed by surface enhanced Raman spectroscopy

Reversible acetylation of histone and non-histone proteins plays an important role in the regulation of gene expression and cellular homeostasis. A balance between acetylation and deacetylation of these proteins are maintained by histone acetyltransferases (HATs) and histone deacetylases (HDACs). Among different HATs, p300/CBP is the most widely studied chromatin modifying enzymes. p300 is involved in several physiological processes like cell growth, regulation of gene expression, development, and tumor suppressor, and therefore its dysfunction causes different diseases. The autoacetylation of p300 is one of the key regulators of its catalytic activity. Mechanistically, autoacetylation induced structural changes in the p300 HAT domain acts as a master switch. In this report, we have shown that the natural HAT inhibitor garcinol could potently inhibit the autoacetylation activity. Furthermore, for the first time, we demonstrate that indeed autoacetylation induces structural changes in p300 HAT domain, as probed by surface-enhanced Raman scattering. Presumably, SERS will be a very useful tool to find out the structural changes in the other self-modifying enzymes like kinases and methyltransferases.     

Sensitive and selective determination of peptides,PG and PGP,using a novel fluorogenic reagent 4-chlorobenzene-1,2-diol

A novel fluorometric method was developed for the sensitive and selective detection of Pro-Gly (PG) and Pro-Gly-Pro (PGP) using 4-chlorobenzene-1,2-diol (4-CBD) as a fluorogenic reagent. The reaction was performed at 37°C for 30 min in the presence of a borate buffer (pH 7.0) and sodium periodate. The resulting fluorescence intensity was measured using a spectrofluorometer with excitation and emission wavelengths of 450 nm and 535 nm. To obtain a stable fluorescent signal and maximise its intensity, different reaction conditions such as the concentrations of the reagents, the reaction time, and the pH were optimised. Under the optimised conditions, a linear relationship was obtained between fluorescence intensity and peptide concentrations from 1.0–40.0 µmol L^?1 with a limit of detection of 1.0 µmol L^?1 (S/N = 3). Both PG and PGP generated a strong signal out of all the peptides tested and no other biogenic substances such as amino acids or proteins produced any fluorescence. The reaction thus developed is simple, rapid, selective, and sensitive. It can be applied to the determination of peptides as biomarkers or substrates.     

Electrocatalytic Nitrite Determination Using Iron Phthalocyanine Modified Gold Nanoparticles

Electrochemical detection of nitrite was achieved via electrodeposition of gold nanoparticles (AuNPs) onto glassy carbon electrodes, followed by 3‐mercaptopropionic acid (MPA) self‐assembly, enabling attachment of an iron(III) monoamino‐phthalocyanine (FeMAPc) catalyst via amide bond formation. The use of scanning electron microscopy, energy dispersive X‐ray spectroscopy and ultraviolet‐visible spectroscopy realised surface characterisation while cyclic voltammetry and electrochemical impedance spectroscopy techniques were applied for electrochemical interrogation. The electrochemical behaviour of nitrite at the bare (GCE), AuNPs/GCE, FeMAPc/GCE and FeMAPc‐MPA/AuNPs/GCE was further scrutinised using differential pulse voltammetry in phosphate buffer solution (0.1 M PBS, pH 5.8). Overall the FeMAPc‐MPA/AuNPs/GCE resulted in sensitivity 14.5 nA/µM, which was double that of AuNPs/GCE, 2.4 times FeMAPc/GCE and 3.5 times the response at a bare GCE, with linear range 1.9 µM–2.04 mM (PBS, pH 5.8) and LOD 0.21 µM. An interference study revealed that the proposed sensor (FeMAPc‐MPA/AuNPs/GCE) exhibited a selective response in the presence of interfering anions and the analytical capability of the sensor was demonstrated via nitrite ion determination in real water samples.     

Toward the synthesis of thiadiazole-based therapeutic agents: synthesis,spectroscopic study,X-ray analysis,and cross-coupling reactions of the key intermediate 3,5-diiodo-1,2,4-thiadiazole

Research on Chemical Intermediates - The 1,2,4-thiadiazole moiety is an important component of several biologically active compounds, and varying substituents on this aromatic ring is one of the...     

One-pot green synthesis,study of fluorescence properties,and biological activity of pyrano[3,2-c]chromenes derivatives via mesoporous materials MgO/SBA-15

This current work describes the preparation of MgO-SBA-15 catalysts by ultrasonic method, and it is characterized by the different analysis techniques of XRD, BET, SEM, and IRTF. In order to find out an application for this mesoporous material, MgO/SBA-15 was used as a heterogeneous catalyst in the one-pot synthesis of pyrano[3,2-c]chromenes derivatives isolated at room temperature reaction according to green chemistry criteria. To enhance these derivatives, a spectroscopic study of molecular fluorescence properties was carried out as well as an identification analysis by nuclear magnetic resonance and FTIR was used. Furthermore, biological activity experiment is also carried out, from where the obtained test results were satisfactory for AC09 , AC05 , and AC10 compounds and they are checked after computation by molecular modeling.     

Détection de fissures dans les poutres d'acier : une nouvelle approche par balayage de mesures de vibrations

In the last few years, the techniques of detection and identification of damage in structures benefited from important research efforts. Several methods of non-destructive damage detection, such as techniques based on modal analysis, were developed in addition to the traditional methods. The difficulties encountered by these techniques are their low performance, considering the industrial requirements to detect cracks as early as possible.     

Homogenization of multicoated inclusion-reinforced linear elastic composites with eigenstrains: Application to thermoelastic behavior

A new micromechanical approach for arbitrary multicoated ellipsoidal elastic inclusions with general eigenstrains is developed. We start from the integral equation of the linear elastic medium with eigenstrains adopting the Green's function technique and we apply an ‘(n+1)-phase’ model with a self-consistent condition to determine the homogenized behavior of multicoated inclusion-reinforced composites. The effective elastic moduli and eigenstrains are obtained as well as the residual stresses through the local stress concentration equations. The effective eigenstrains are determined either with the concentration tensors obtained here by the present model, or, more classically, with Levin's formula. In order to assess our micromechanical model, some applications to the isotropic thermoelastic behavior of composites with and without interphase are given. In particular, ‘four-phase’ and ‘three-phase’ models are derived for isotropic homothetic spherical inclusion-reinforced materials, and the results are successfully compared to exact analytical solutions regarding the effective elastic moduli and the effective thermal expansion.     

Pyrolysis of corrugated cardboard in inert and oxidative environments

The thermal decomposition of corrugated cardboard has been studied in inert and oxidative (non-flaming) atmospheres under a range of radiant heat fluxes relevant to fire conditions in warehouse storage applications. Experiments were performed in a Fire Propagation Apparatus (FPA) on double-wall corrugated cardboard at heat flux levels of 20, 60, and 100 kW/m². Pyrolysis data comprised of gasification rates and surface temperatures were collected for tests carried out in ambient atmospheres consisting of 100% N₂ as well as 2%, 6%, 8%, 10%, and 14% (mol) O₂ in balance nitrogen. It is shown that the presence of oxygen has an appreciable effect at all heat flux levels; however, it is most prevalent at low heat fluxes. Analyses are presented in an effort to gain further understanding of char oxidation processes. Results show that the maximum heat evolved in oxidative environments is relatively constant and similar for all conditions tested. Furthermore this heat release rate is found to be comparatively small relative to the high radiant fluxes tested; this explains the experimentally observed behavior. This study provides a comprehensive dataset that may be used in conjunction with approaches recently adopted in the fire community in which optimization procedures are employed to generate material properties for pyrolysis models used in CFD fire simulations.