Polyphenolics with Strong Antioxidant Activity from Acacia nilotica Ameliorate Some Biochemical Signs of Arsenic-Induced Neurotoxicity and Oxidative Stress in Mice

Neurotoxicity is a serious health problem of patients chronically exposed to arsenic. There is no specific treatment of this problem. Oxidative stress has been implicated in the pathological process of neurotoxicity. Polyphenolics have proven antioxidant activity, thereby offering protection against oxidative stress. In this study, we have isolated the polyphenolics from Acacia nilotica and investigated its effect against arsenic-induced neurotoxicity and oxidative stress in mice. Acacia nilotica polyphenolics prepared from column chromatography of the crude methanol extract using diaion resin contained a phenolic content of 452.185 ± 7.879 mg gallic acid equivalent/gm of sample and flavonoid content of 200.075 ± 0.755 mg catechin equivalent/gm of sample. The polyphenolics exhibited potent antioxidant activity with respect to free radical scavenging ability, total antioxidant activity and inhibition of lipid peroxidation. Administration of arsenic in mice showed a reduction of acetylcholinesterase activity in the brain which was counteracted by Acacia nilotica polyphenolics. Similarly, elevation of lipid peroxidation and depletion of glutathione in the brain of mice was effectively restored to normal level by Acacia nilotica polyphenolics. Gallic acid methyl ester, catechin and catechin-7-gallate were identified in the polyphenolics as the major active compounds. These results suggest that Acacia nilotica polyphenolics due to its strong antioxidant potential might be effective in the management of arsenic induced neurotoxicity.     

Synthesis and Characterization of Polyesters Based on Diethylketone Moiety

A new class of unsaturated polyesters based on diethylketone have been prepared by interfacial polymerization of 2,4-bis（4-hydroxybenzylidene）-3-pentanone（I） and 2,4-bis（4-hydroxy-3-methoxybenzylidene）-3-pentanone（II） with 4,4’-azodibenzoyl chloride and 3,3’-azodibenzoyl chloride at ambient temperature. The model compounds were synthesized by reaction of（I） and（II） with benzoyl chloride. The new monomers, model compounds and polyesters have been characterized by different spectral analyses. The polyesters have inherent viscosity of 0.55-0.80 d L/g and moderate number average molecular weight（Mn） in the range of 6150-7400 g/mol. Most of the compounds exhibited their solubility in aprotic solvents while partial solubility in various halogenated organic solvents was observed. The temperatures of 10% weight loss were high（225-330 °C） in nitrogen, indicating that these polyesters have excellent thermal stability. Doping with iodine dramatically raised the conductivity and produced brown colored semiconductive polymers with a maximum conductivity of 2.7 × 10-6 --1cm-1. Moreover, the morphological properties of selected example of polyesters were detected by SEM.     

Metal Enhanced Electrochemical Cyclooxygenase‐2 (COX‐2) Sensor for Biological Applications

Pain measurement is commonly required in biomedical and other emergency situations, yet there has been no pain biosensor reported in literature. Conventional approaches for pain measurement relies on Wong‐Baker face diagrams, which are grossly inadequate for situations involving children or unconscious people. We report a label‐free immunosensor for monitoring the pain biomarker cylooxygenase‐2 (COX‐2) in blood. The sensor is based on the concept of metal‐enhanced detection (MED). MED relies on the idea that the immobilization of underpotential deposition (upd) metallic films deposited either as a monolayer or electrostatically held onto a solid gold substrate could significantly amplify bimolecular recognition such as involving antigen‐antibody (Ab‐Ag) interactions. The surface bound Ab‐Ag complex insulates the electrode; causing a decrease in concentration‐dependent redox signals. A linear detection range of (3.64–3640.00)×10^?4 ng/mL was recorded with a detection limit of 0.25×10^?4 ng/mL, which was 4 orders of magnitude lower than that reported for ELISA for the same biomarker. The immunosensor exhibited selectivity of less than 6 % for potential interferents.     

Inhibition efficiency and adsorption mechanism of 4-aminobenzoic acid for copper corrosion in nitric acid medium: a combined experimental and theoretical investigation

Structural Chemistry - A combined experimental and theoretical study is presented to predict and analyze the inhibition efficiency and adsorption mechanism of 4-aminobenzoic acid molecule for...     

Computer simulations of astronomical objects as seen by ground based optical telescopes

Computer simulations were carried out to investigate the limitations imposed by atmospheric turbulence on observing astronomical objects by 3·5 and 1·25 m optical telescopes. These limitations were studied in terms of the modulation transfer function of a reference star and the autocorrelation function of a binary star. Results demonstrate the quantitative comparative study between these telescopes in the presence of different seeing conditions for both short- and long-exposure recording.     

Binding and Ionophoric Properties of Polyamide Compounds. Lead Selectivity

The extraction and transport properties of macrocyclic dioxa-, dithia- and diazatetralactams are reported along with those of open-chain analogous compounds. The preference of three of them for lead over alkali, alkaline-earth or other heavy metal cations is discussed.     

The electrochemistry of antibody-modified conducting polymer electrodes

The modification of conducting polymer electrodes with antibodies (i.e. proteins) by means of electrochemical polymerization is a simple step that can be used to develop an immunological sensor. However, the electrochemical processes involved leading to the generation of analytical signals by the sensor have not been fully investigated. In this work, we report on the characterization of the interaction between an antigen, human serum albumin (HSA) and an antibody-immobilized polypyrrole electrode (such as anti-HSA) using cyclic voltammetry (CV) and impedance spectroscopy. This interaction was monitored using electrochemical impedance spectroscopy at three different potentials. The potentials correspond to the three redox states of the electroconducting polymer (i.e. reduced, doped and overoxidized states). Evidence from the CV experiments confirmed that there was a shift in the potential, which was found to be proportional to the concentration. Both the CV and the impedance experiments indicated that this potential-dependent shift could be attributed to antibody–antigen (Ab–Ag) binding.     

Extremal Problems in the Class of Delta-Subharmonic Functions of Finite Order in a Half-Plane

We obtain exact lower bounds of the upper limits of ratios of the Nevanlinna characteristics of a delta-subharmonic function in the upper half-plane.     

Forced convection from a microstructure on a flat plate

In this work, a cooling of a flat microelectronic structure with single-phase forced convection is investigated. The axial conduction, usually neglected in boundary layer theory, is considered here since the length of the heated element is in the same order of magnitude as the thickness of the boundary layer. The microstructure represents a package of chips mounted flush with the surface of the plate, and uniformly heated with a constant heat flux. The differential method is used to reduce the governing partial differential equations to ordinary differential ones, which are solved numerically by the use of a computational code developed by the authors. This code is based on Keller–Box method. The temperature profiles and Nusselt numbers are plotted at several locations on the heated element and are given as functions of the Reynolds number at the beginning of heated microstructure and of the ratio of unheated to heated length. Furthermore, the average Nusselt numbers on the heated length are computed for Prandtl numbers in the range 0.7≤Pr≤7,000. The results are compared to the boundary layer solution of unheated starting length problem. The results will be used as a baseline for successively more complex situations of cooling in electronics.     

Biophysical Properties of Phenyl Succinic Acid Derivatised Hyaluronic Acid

Modification of hyaluronic acid (HA) with aryl succinic anhydrides results in new biomedical properties of HA as compared to non-modified HA, such as more efficient skin penetration, stronger binding to the skin, and the ability to blend with hydrophobic materials. In the present study, hyaluronic acid has been derivatised with the anhydride form of phenyl succinic acid (PheSA). The fluorescence of PheSA was efficiently quenched by the HA matrix. HA also acted as a singlet oxygen scavenger. Fluorescence lifetime(s) of PheSA in solution and when attached to the HA matrix has been monitored with ps resolved streak camera technology. Structural and fluorescence properties changes induced on HA-PheSA due to the presence of singlet oxygen were monitored using static light scattering (SLS), steady state fluorescence and ps time resolved fluorescence studies. SLS studies provided insight into the depolymerisation kinetics of PheSA derivatised HA matrix in the presence of singlet oxygen. Time resolved fluorescence studies grave insight into the dynamics of the reaction mechanisms induced on HA-PheSA by singlet oxygen. These studies provided insight into the medical relevance of PheSA derivatised HA: its capacity of scavenging singlet oxygen and of quenching PheSA fluorescence. These studies revealed that HA-PheSA is a strong quencher of electronic excited state PheSA and acts as a scavenger of singlet oxygen, thus medical applications of this derivatised form of HA may protect tissues and organs, such as skin, against reactive oxygen species damage.