pH Dependent Molecular Self-Assembly of Octaphosphonate Porphyrin of Nanoscale Dimensions: Nanosphere and Nanorod Aggregates

Self-assembled nanostructures of zwitterionic octaphosphanatoporphyrin 1, of either nanoparticles or nanorods, depending on small changes in the pH, is demonstrated based on the J-aggregates. Porphyrin 1 self-assembled into nanosphere aggregates with a diameter of about 70–80 nm in the pH range 5–7, and nanorod aggregates were observed at pH 8.5. Hydrogen bonding, π-π stacking and hydrophilic interactions play important roles in the formation of this nanostructure morphology. Nanostructures were characterized by UV/Vis absorbance, fluorescence, atomic force microscopy (AFM) and transmission electron microscopy (TEM). This interesting pH dependent self-assembly phenomenon could provide a basis for development of novel biomaterials

Kinetic and Mechanistic Study of Glucose Isomerization Using Homogeneous Organic Brønsted Base Catalysts in Water

The isomerization of glucose to fructose represents a key intermediate step in the conversion of cellulosic biomass to fuels and renewable platform chemicals, namely, 5-hydroxymethyl furfural (HMF), 2,5-furandicarboxylic acid (FDCA), and levulinic acid (LA). Although both Lewis acids and Brønsted bases catalyze this reaction, the base-catalyzed pathway received significantly less attention due to its lower selectivity to fructose and the poor yields achieved (\u3c10%). However, we recently demonstrated that homogeneous organic Brønsted bases present a similar performance (∼31% yield) as Sn-containing beta zeolite, a reference catalyst for this reaction. Herein, we report on the first extensive kinetic and mechanistic study on the organic Brønsted base-catalyzed isomerization of glucose to fructose. Specifically, we combine kinetic experiments performed over a broad range of conditions (temperature: 80–120 °C; pH 9.5–11.5; reactant: glucose, fructose) with isotopic studies and in situ 1H NMR spectroscopy. Pathways leading to isomerization and degradation of the monosaccharides have been identified through careful experimentation and comparison with previously published data. Kinetic isotope effect experiments were carried out with labeled glucose to validate the rate-limiting step. The ex situ characterization of the reaction products was confirmed using in situ 1H NMR studies. It is shown that unimolecular (thermal) and bimolecular (alkaline) degradation of fructose can be minimized independently by carefully controlling the reaction conditions. Fructose was produced with 32% yield and 64% selectivity within 7 min

Isolation of L-asparginase from marine bacterium Bacillus subtilis and its characterization

97-106Microbial L-asparginases has wide range of applications as therapeutic agents and in industries. In the present study, 57 bacterial isolates from Konark beach, Bhubaneshwar were screened for L-asparginase production and KBI-13 isolate was found to be potential producer strain. KBI-13 was identified as Bacillus subtilis at molecular levels. During production optimization, pH (8.0), temperature (40 ºC), carbon and nitrogen sources (dextrose- 0.5 %; yeast extract 1 %), aeration conditions, metal salts (FeSO4) and NaCl (4 %) were found to be optimum. The enzyme was produced under optimized conditions and was purified by sephadex G-50 column and the purification was obtained upto 61.54 fold. The activity of enzyme was increased upto pH 8.0 and temperature 40 ºC and its stability was observed upto 16 hrs at 40 ºC temperature and pH 8.0. Pretreatment of 0.5 mM CaCl2 increased the enzyme activity upto 20 % while, 250 mM concentration of L-aspargine was suitable for optimum activity of enzyme which was further confirmed by values of Vmax (1.25 µM/min) and Km (0.05 mM). The reaction end products did not show any significant change in enzyme activity. 

Isolation of L-asparginase from marine bacterium Bacillus subtilis and its characterization

Microbial L-asparginases has wide range of applications as therapeutic agents and in industries. In the present study, 57 bacterial isolates from Konark beach, Bhubaneshwar were screened for L-asparginase production and KBI-13 isolate was found to be potential producer strain. KBI-13 was identified as Bacillus subtilis at molecular levels. During production optimization, pH (8.0), temperature (40 ºC), carbon and nitrogen sources (dextrose- 0.5 %; yeast extract 1 %), aeration conditions, metal salts (FeSO4) and NaCl (4 %) were found to be optimum. The enzyme was produced under optimized conditions and was purified by sephadex G-50 column and the purification was obtained upto 61.54 fold. The activity of enzyme was increased upto pH 8.0 and temperature 40 ºC and its stability was observed upto 16 hrs at 40 ºC temperature and pH 8.0. Pretreatment of 0.5 mM CaCl2 increased the enzyme activity upto 20 % while, 250 mM concentration of L-aspargine was suitable for optimum activity of enzyme which was further confirmed by values of Vmax (1.25 µM/min) and Km (0.05 mM). The reaction end products did not show any significant change in enzyme activity

1,3-Dipolar reactions for the synthesis of new substituted isoxazolidines and isoxazoles

1239-124

High temperature optical absorption investigation into the electronic transitions in sol–gel derived C12A7 thin films

Optical absorption into 6 mm thick sol–gel derived films, annealed at 1300 °C of 12CaO·7Al2O3 calcium aluminate binary compound on MgO〈100〉 single crystal substrates was studied at temperatures ranging from room temperature to 300 °C. Experimental data were analysed in both Tauc and Urbach regions. The optical band gap decreased from 4.088 eV at 25 °C to 4.051 eV at 300 °C, while Urbach energy increased from 0.191 eV at 25 °C to 0.257 eV at 300 °C. The relationship between the optical band gap and the Urbach energy at different temperatures showed an almost linear relationship from which the theoretical values of 4.156 and 0.065 eV were evaluated for the band gap energy and Urbach energy of a 12CaO·7Al2O3 crystal with zero structural disorder at 0 K

Measurements of π±\pi^\pm, K±^\pm, p and pˉ\bar{\textrm{p}} spectra in proton-proton interactions at 20, 31, 40, 80 and 158 GeV/c with the NA61/SHINE spectrometer at the CERN SPS

Measurements of inclusive spectra and mean multiplicities of $\pi^\pm$, K$^\pm$, p and $\bar{\textrm{p}}$ produced in inelastic p+p interactions at incident projectile momenta of 20, 31, 40, 80 and 158 GeV/c ($\sqrt{s} =$ 6.3, 7.7, 8.8, 12.3 and 17.3 GeV, respectively) were performed at the CERN Super Proton Synchrotron using the large acceptance NA61/SHINE hadron spectrometer. Spectra are presented as function of rapidity and transverse momentum and are compared to predictions of current models. The measurements serve as the baseline in the NA61/SHINE study of the properties of the onset of deconfinement and search for the critical point of strongly interacting matter