Partial purification of alpha-amylase from culture supernatant of Bacillus subtilis in aqueous two-phase systems

The original publication can be found at www.springerlink.comA study was made of the partition and purification of -amylase from a culture supernatant of Bacillus subtilis in the polyethylene glycol (PEG)—citrate aqueous two-phase system (ATPS). Factors that influenced the partition of the protein in this system, including the molecular weight of the PEG, the tie line length of ATPS, the pH value and the sodium chloride concentration, were investigated. Purification of -amylase was attained with a purification factor (PF) of 1.8 and 90% yield at pH 6.0 in a PEG1000-citrate ATPS with short tie line length. By utilizing the salt-out effect of neutral salt, the purification of -amylase was further improved to 2.0 of PF and 80% yield in a PEG3350-citrate ATPS with 4% sodium chloride.Wenbo Zhi, Jiangnan Song, Jingxiu Bi and Fan Ouyan

Solar Intranetwork Magnetic Elements: bipolar flux appearance

The current study aims to quantify characteristic features of bipolar flux appearance of solar intranetwork (IN) magnetic elements. To attack such a problem, we use the Narrow-band Filter Imager (NFI) magnetograms from the Solar Optical Telescope (SOT) on board \emph{Hinode}; these data are from quiet and an enhanced network areas. Cluster emergence of mixed polarities and IN ephemeral regions (ERs) are the most conspicuous forms of bipolar flux appearance within the network. Each of the clusters is characterized by a few well-developed ERs that are partially or fully co-aligned in magnetic axis orientation. On average, the sampled IN ERs have total maximum unsigned flux of several 10^{17} Mx, separation of 3-4 arcsec, and a lifetime of 10-15 minutes. The smallest IN ERs have a maximum unsigned flux of several 10^{16} Mx, separations less than 1 arcsec, and lifetimes as short as 5 minutes. Most IN ERs exhibit a rotation of their magnetic axis of more than 10 degrees during flux emergence. Peculiar flux appearance, e.g., bipole shrinkage followed by growth or the reverse, is not unusual. A few examples show repeated shrinkage-growth or growth-shrinkage, like magnetic floats in the dynamic photosphere. The observed bipolar behavior seems to carry rich information on magneto-convection in the sub-photospheric layer.Comment: 26 pages, 14 figure

HDB LIFT UPGRADING PROGRAMME IN SINGAPORE � IMPACT ON SOCIAL CAPITAL

Bachelor'sBACHELOR OF SCIENCE (REAL ESTATE

Theoretical insight into the roles of cocatalysts in the Ni-NiO/β-Ga2O3 photocatalyst for overall water splitting

The formation and stability of Nin and (NiO)n (n = 1-4) clusters on the β-Ga2O3 surface have been studied by means of first-principles density functional theory calculations. It is found that the optimum interaction of the Nin and (NiO)n clusters with the surface requires different surface sites. This optimizes the formation of interfacial bonds between the atoms from clusters and the coordinatively unsaturated atoms from the surface. The stability of the adsorbed Ni clusters increases with the number of Ni atoms. In a Nin/Ga2O3 system, as the Ga unoccupied states overlap with the unoccupied Ni state, the excited electrons transferred from Ga to Ni participate in the proton reduction reaction. Our calculations show that (NiO)n clusters strongly adsorb on the Ga2O3 surface due to the negative adsorption energies within -1.9 eV to -3.7 eV. For (NiO)n/Ga2O3, occupied states from the (NiO)n cluster may accept the holes from O atoms in the Ga2O3 surface to take part in the photocatalytic water oxidation reaction

Rapid quantitative analysis of six flavonoids in licorice by ultra-performance convergence chromatography

Abstract Objective This study was to establish a rapid quantitative method for determination of six characteristic flavonoids, including licochalcone A (1), liquiritigenin (2), glabridin (3), isoliquiritigenin (4), liquiritoside (5), and isoliquiritoside (6) in licorice by a ultra-performance convergence chromatography (UPC2) apparatus equipped with a photodiode-array detector (PDA). Methods: The flavonoids studied were separated on an ACQUITY UPC2 TM Torus 2-PIC column (2.1 × 100 mm, 1.7 μm) using gradient elution (85:15–70:30) with a mobile phase consisting of CO2 and methanol: formic acid (99.8:0.2, v/v), back pressure of 2,000 psi, flow rate of 0.8 mL/min, and detection at 254 nm. This method was further applied for the analysis of the flavonoids present in 10 batches of licorice roots samples. Results: Good linearity (R2 = 0.9990–0.9998) was achieved and limits of detection (LOD) and quantification (LOQ) ranging from 0.12 to 0.49 µg/mL and 0.46 to 1.61 µg/mL, respectively. The relative standard deviations (RSD) for repeatability and reproducibility were 2.30–2.80% and 2.30–2.98%, respectively. The flavonoids distributed differently in Glycyrrhiza uralensis , Glycyrrhiza glabra, and Glycyrrhiza inflate . Conclusion: The established rapid quantitative analysis method was environment friendly and suitable to the quality control of species licorice

A Novel Sr_2CuInO_3S p-type semiconductor photocatalyst for hydrogen production under visible light irradiation

A novel Sr 2 CuInO 3 S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type semiconductor character of the synthesized Sr 2 CuInO 3 S was confirmed by Hall efficient measurement and Mott-Schottky plot analysis. First-principles density functional theory calculations (DFT) and electrochemical measurements were performed to elucidate the electronic structure and the energy band locations. It was found that the as-synthesized Sr 2 CuInO 3 S photocatalyst has appreciate conduction and valence band positions for hydrogen and oxygen evolution, respectively. Photocatalytic hydrogen production experiments under a visible light irradiation (λ>420 nm) were carried out by loading different metal and metal-like cocatalysts on Sr 2 CuInO 3 S and Rh was found to be the best one among the tested ones

Theoretical insight into the roles of cocatalysts in the Ni-NiO/β-Ga2O3 photocatalyst for overall water splitting

The formation and stability of Nin and (NiO)n (n = 1-4) clusters on the β-Ga2O3 surface have been studied by means of first-principles density functional theory calculations. It is found that the optimum interaction of the Nin and (NiO)n clusters with the surface requires different surface sites. This optimizes the formation of interfacial bonds between the atoms from clusters and the coordinatively unsaturated atoms from the surface. The stability of the adsorbed Ni clusters increases with the number of Ni atoms. In a Nin/Ga2O3 system, as the Ga unoccupied states overlap with the unoccupied Ni state, the excited electrons transferred from Ga to Ni participate in the proton reduction reaction. Our calculations show that (NiO)n clusters strongly adsorb on the Ga2O3 surface due to the negative adsorption energies within -1.9 eV to -3.7 eV. For (NiO)n/Ga2O3, occupied states from the (NiO)n cluster may accept the holes from O atoms in the Ga2O3 surface to take part in the photocatalytic water oxidation reaction