Infrared spectroscopy for the study of urinary calculi

The occurance of the urinary stones varies according to the geographical regions. The presence of stones in the urinary system causes pain and discomfort. These generate colics and hence are sometimes life threatening. In the present study, infrared measurements have been made on several stone samples. It has been found that calcium oxalate, calcium phosphate, magnesiunm ammonium phosphate, calcium carbonate, uric acid, -cystine and xanthin are present, as expected. Also, silicon dioxide is found to be present in some of the stones but in small quantity, in addition to the above constituents. This constituent is responsible to exhibit piezoelectricity in the urinary calculi.     

Base hydrolysis ofcis-(methyl/ethylamine)bis(ethylenediamine) (salicylato)cobalt(III) complexes

The kinetics of the base hydrolysis ofcis-[Co(en)₂(RNH₂)-(SalH)]²⁺ (R=Me or Et; SalH=HOC₆H₄CO ₂ ⁻ ) were investigated in aqueous ClO ₄ ⁻ in the 0.004–0.450 mol dm⁻³ [OH⁻] range, I=0.50 mol dm⁻³ at 30–40°C. The phenoxide species is hydrolysed via [OH⁻]-independent and [OH⁻]-dependent paths, the latter being first order in [OH⁻]. The high rate of alkali-independent hydrolysis of the phenoxide species is associated with high ΔH^≠ and ΔS^≠ values, in keeping with the SNICB mechanism involving an amido conjugate base generated by the phenoxide-assisted NH-deprotonation of the coordinated amine. The [OH⁻]-dependent path also involves the conventional SN₁ CB mechanism. The rate constant, k₁, for the SNICB path exhibits a steric acceleration with the increasing size of the non-labile alkylamine, whereas the rate constant, k₂, for the SN₁CB path shows a reverse trend. TMC 2578     

A new method for determining the local environment and orientation of individual side chains of membrane-binding peptides

We studied here the binding of the mastoparan X peptide to a zwitterionic lipid bilayer (POPC) and demonstrated that nitrile-derivatized amino acids can be used to determine the hydration state (or change in hydration state) of specific sites of membrane-interactive peptides (upon binding). We have also shown that polarized ATR-FTIR measurements can further be used to uncover information regarding the spatial orientation of individual side chains as well as their conformational preference within the lipid bilayer.     

Grafting Vinyl Monomers onto Silk Fibers. XIII. Graft Copolymerization of Methyl Methacrylate onto Silk Using Fe3+−Cysteine Redox System

The graft copolymerization of methyl methacrylate onto silk fibers initiated by the ferric chloride-eysteine redox system has been investigated in aqueous medium. The rate of grafting was calculated by varying the concentrations of monomer, initiator, acidity of the medium, cysteine, and temperature. The percentage of grafting increases with an increase of Fe³⁺ concentration up to 2,5 × 10^?3 mol/L and thereafter it decreases. The graft yield increases steadily upon increasing the monomer concentration. The graft yield also increases with increasing cysteine concentration up to 0.5 × 10^?3 mol/L and then decreases. The effect of the perchloric acid concentration, temperature, solvents, and certain neutral salts on graft yield has also been investigated and a suitable reaction scheme has been proposed.     

Perchloric Acid-Catalyzed Synthesis of 9-Aryl Xanthenes-9H-3,6-diol and 1,3,6,8-Tetraol in Water

Efficient syntheses of xanthenes have been described using a catalytic amount of perchloric acid in water. The high temperature and lengthy reaction time normally required for formation of xanthenes derivatives are not necessary when using a catalytic amount of perchloric acid. The method is relatively inexpensive, easily available, nonvolatile, nonexplosive, and thermally robust to catalyze the reaction at 80 °C by simple heating with good to excellent yields. The advantages of the reaction involve simple reaction protocol, simple workup, and improved synthesis in the presence of perchloric acid as catalyst.     

Preliminary Investigation of the Antioxidant,Anti-Diabetic,and Anti-Inflammatory Activity of Enteromorpha intestinalis Extracts

Marine algae are a promising source of potent bioactive agents against oxidative stress, diabetes, and inflammation. However, the possible therapeutic effects of many algal metabolites have not been exploited yet. In this regard, we explored the therapeutic potential of Enteromorpha intestinalis extracts obtained from methanol, ethanol, and hexane, in contrasting oxidative stress. The total phenolic (TPC) and flavonoids (TFC) content were quantified in all extracts, with ethanol yielding the best values (about 60 and 625 mg of gallic acid and rutin equivalents per gram of extract, respectively). Their antioxidant potential was also assessed through DPPH^•, hydroxyl radical, hydrogen peroxide, and superoxide anion scavenging assays, showing a concentration-dependent activity which was greater in the extracts from protic and more polar solvents. The α-amylase and α-glucosidase activities were estimated for checking the antidiabetic capacity, with IC₅₀ values of about 3.8 µg/mL for the methanolic extract, almost as low as those obtained with acarbose (about 2.8 and 3.3 µg/mL, respectively). The same extract also showed remarkable anti-inflammatory effect, as determined by hemolysis, protein denaturation, proteinase and lipoxygenase activity assays, with respectable IC₅₀ values (about 11, 4, 6, and 5 µg/mL, respectively), also in comparison to commercially used drugs, such as acetylsalicylic acid.     

Computation-led design of pollutant gas sensors with bare and carbon nanotube supported rhodium alloys

Quantum chemical study has been performed on finite-sized bi-metallic Rh3M alloys, M = Ag, Ir, Pd, Pt, Au, derived from magic cluster, Rh4. Bond length of C–O and N–O are noticed to be elongated in the presence of rhodium alloy clusters. CO2 and NO2 gases are found to be highly adsorbed on Rh3M clusters, which is confirmed by stretching frequency of C–O and N–O. DFT evaluated dipole moment and electronic charge redistribution suggests the sensing capability of CO2 and NO2 gases by Rh3M clusters which is further confirmed by the calculated HOMO–LUMO gap. Mixed rhodium alloy clusters supported on single-wall carbon nanotube (SWCNT) exhibits much higher ability to sense CO2 and NO2. On the other hand, SWCNT@Rh3M shows higher catalytic activity for the activation of CO2 and NO2 in comparison to bare Rh3M because of the higher electronic charge redistribution in the case of SWCNT@Rh3M. In case of SWCNT-supported gas adsorbed clusters, p electrons play a major role in bonding.     

Plane Symmetric Viscous Fluid Cosmological Models with Varying <Emphasis Type="Italic">Λ</Emphasis>-Term

Plane symmetric viscous fluid cosmological models of the universe with a variable cosmological term are investigated. The viscosity coefficient of bulk viscous fluid is assumed to be a power function of mass density whereas the coefficient of shear viscosity is to be proportional to rate of expansion in the model. We have also obtained a special model in which the shear viscosity is assumed to be zero. The cosmological constant Λ is found to be a decreasing function of time and a positive which is supported by results from recent supernovae Ia observations. Some physical and geometric properties of the models are also discussed.