Role of a remote leucine residue in the catalytic function of polyol dehydrogenase

This study examined the role of remote residues on the structure and function of zinc-dependent polyol dehydrogenases.

High performance chemiresistive H2S sensors using Ag-loaded SnO2 yolk–shell nanostructures

Highly selective, sensitive, and reversible H₂S sensors were designed using Ag-loaded SnO₂ yolk–shell nanostructures prepared by one-pot ultrasonic spray pyrolysis.

Large-scale production of spherical Y2O3:Eu3+ phosphor powders with narrow size distribution using a two-step spray drying method

Dense spherical Y₂O₃:Eu³⁺ phosphor particles with a narrow size distribution were successfully prepared by using a two-step spray drying method. This method is easily scalable and can therefore be applied to the mass production of phosphor particles with high photoluminescence.

One-pot rapid synthesis of core-shell structured NiO@TiO2 nanopowders and their excellent electrochemical properties as anode materials for lithium ion batteries

Core-shell structured NiO@TiO2 nanopowders for application as anode materials for lithium ion batteries are prepared by one-pot flame spray pyrolysis from aqueous spray solution containing Ni and Ti components. A new formation mechanism of the core-shell structured nanopowders in the flame spray pyrolysis is proposed. Composite nanopowders are first formed by surface growth and coagulation from NiO and TiO2 vapors. A small amount of TiO2 in composite powders disturbs the crystallization of TiO2. Therefore, the TiO2 component moves out to the surface of the powders forming an amorphous shell during the formation of single crystalline NiO. The initial discharge and charge capacities of the NiO@TiO2 nanopowders at a current density of 300 mA g(-1) are 1302 and 937 mA h g(-1), respectively. The discharge capacities of the pure NiO and NiO@TiO2 nanopowders after 80 cycles are 542 and 970 mA h g(-1), respectively. The capacity retentions of the pure NiO and NiO@TiO2 nanopowders after 80 cycles measured after the first cycles are 75 and 108%, respectively.

One-pot synthesis of Fe2O3 yolk-shell particles with two, three, and four shells for application as an anode material in lithium-ion batteries

Fe2O3 yolk-shell particles with two, three, and four shells are prepared by one-pot spray pyrolysis. The discharge capacity of the Fe2O3 yolk-shell particles with two shells showing the best electrochemical properties is as high as 848 mA h g(-1) after 80 cycles at a current density of 300 mA g(-1).

Electrochemical properties of yolk-shell-structured CuO-Fe(2)O(3) powders with various Cu/Fe molar ratios prepared by one-pot spray pyrolysis

Several yolk-shell-structured CuO-Fe2 O3 powders with various Cu/Fe molar ratios have been successfully prepared under equivalent reaction conditions using a one-pot spray pyrolysis process. The Cu and Fe components are uniformly distributed throughout the powders, irrespective of composition. The Brunauer-Emmett-Teller surface areas of the yolk-shell CuO-Fe2 O3 systems increased from 5 to 16 m(2)  g(-1) if the Cu/Fe molar ratios are decreased from 3:1 to 1:3. The initial discharge and charge capacities of the yolk-shell CuO-Fe2 O3 system (Cu/Fe=1:2), showing maximum values at a constant current density of 1000 mA g(-1) , are 1436 and 1012 mA h g(-1) , respectively. After 130 cycles, the discharge capacities of the yolk-shell CuO-Fe2 O3 powders with Cu/Fe molar ratios of 1:3, 1:2, 1:1, 2:1, and 3:1 are 1159, 1151, 755, 655, and 651 mA h g(-1) , respectively. The discharge capacities of the yolk-shell and dense powder samples after 50 cycles, when subjected to a series of current density increases from 500 to 5000 mA g(-1) , are 735 and 495 mA h g(-1) , respectively.

Yolk-shell, hollow, and single-crystalline ZnCo(2)O(4) powders: preparation using a simple one-pot process and application in lithium-ion batteries

The electrochemical properties of yolk-shell-structured, multi-component, transition-metal oxides have not yet been properly compared to those of hollow-structured or nanoscale powders. In this study, yolk-shell, hollow, and single-crystalline ZnCo2 O4 powders with uniform compositions are prepared by using simple gas-phase reaction methods. Double-shelled ZnCo2 O4 yolk-shell powder is prepared directly from the spray solution by using spray pyrolysis. Single-crystalline ZnCo2 O4 nanopowder is prepared by means of flame spray pyrolysis. The yolk-shell ZnCo2 O4 powder shows higher charge and discharge capacities than the hollow and single-crystalline powders. The yolk-shell, hollow, and single-crystalline ZnCo2 O4 powders deliver discharge capacities of 753, 586, and 206 mAh g(-1) , respectively, after 200 cycles at a charge/discharge rate of 3 A g(-1) , and the corresponding capacity retentions measured after the first cycle are 99, 74, and 27 %, respectively. The yolk-shell ZnCo2 O4 powders are structurally stable during cycling and have good electrochemical properties even at high current densities.

One-pot facile synthesis of ant-cave-structured metal oxide-carbon microballs by continuous process for use as anode materials in Li-ion batteries

This paper introduces a facile one-pot method for synthesizing a new structured material, named "ant-cave microball", by continuous ultrasonic spray pyrolysis. The ant-cave-structured microballs are prepared from a colloidal spray solution with polystyrene nanobeads and sucrose. Networking between the nanovoids formed by decomposition of the polystyrene nanobeads results in the formation of nanochannels. The electrochemical properties of these ant-cave-structured MoO3-C microballs, prepared as the first target material for lithium ion batteries, are investigated. The nanochannels are uniformly distributed inside the microballs with MoO3 and carbon components uniformly distributed within the microballs. Further, the microballs have initial discharge and charge capacities of 1212 and 841 mA h g(-1), respectively, at a current density of 2 A g(-1), and the initial discharge and charge capacities based on the weight of MoO3 (disregarding carbon component) are as high as 1814 and 1259 mA h g(-1). The microballs deliver a high discharge capacity of 733 mA h g(-1) even after 300 cycles. This is although microsized MoO3 powders with a filled structure have discharge capacities of 1256 and 345 mA h g(-1) for the first and 300th cycles, respectively.

A new strategy for synthesizing yolk-shell V₂O₅ powders with low melting temperature for high performance Li-ion batteries

This paper presents the fabrication of yolk-shell V₂O₅ powders with a low melting temperature of 690 °C by using a simplified two-step process. The spherical V₂O₃-C composite obtained by spray pyrolysis transforms into yolk-shell V₂O₅ powder by a simple combustion process at 400 °C. The yolk-shell V₂O₅ powders are composed of nanoplate crystals several tens of nanometers in size, and have a BET surface area of 15 m(2) g(-1). The powders exhibit initial discharge and charge capacities of 271 and 264 mA h g(-1) at a current density of 1000 mA g(-1), respectively, and a corresponding Coulombic efficiency of 97.4%. After 100 cycles, the discharge capacity of the yolk-shell V2O5 powders is 201 mA h g(-1). In contrast, spherical V2O5 powders with a dense structure exhibit low initial discharge and charge capacities of 160 and 145 mA h g(-1), respectively. The structural stability of the yolk-shell during Li-ion insertion and extraction improves the electrochemical properties of the V2O5 powders, even at high current densities.

Yolk-shelled cathode materials with extremely high electrochemical performances prepared by spray pyrolysis

A facile, continuous preparation process of yolk-shell-structured lithium-metal oxide powders without a template for use as cathode materials in lithium ion batteries is introduced for the first time. Single and double-shelled LiNi0.5Mn1.5O4 yolk-shell powders as the first target materials are prepared directly by spray pyrolysis from a spray solution with sucrose, at a short residence time of 4 s. Fast combustion and contraction of a carbon-mixed oxide composite intermediate, formed from a micro-sized droplet inside a hot wall reactor maintained at 700 °C, produces the yolk-shell powders. The yolk-shell structure of the precursor powders directly prepared by spray pyrolysis is well maintained even at a high post-treatment temperature of 750 °C. The yolk-shell LiNi0.5Mn1.5O4 powders delivered a 1000(th) high discharge capacity of 108 mA h g(-1) at 10 C. The discharge capacities are as high as 103, 95, and 91 mA h g(-1) at extremely high discharge rates of 100, 200, and 300 C and the corresponding specific energy densities are 420, 370, and 328 W h kg(-1). The capacity retention at a constant discharge rate of 200 C is 90% after 500 cycles.

Optimization of β-glucosidase production by a strain of Stereum hirsutum and its application in enzymatic saccharification

A high beta-glucosidase (BGL)-producing strain, Stereum hirsutum, was identified and isolated and showed a maximum BGL activity (10.4 U/ml) when cultured with Avicel and tryptone as the carbon and nitrogen sources, respectively. In comparison with other BGLs, BGL obtained from S. hirsutum showed a higher level of activity to cellobiose (V(max) = 172 U/mg, and k(cat) = 281/s). Under the optimum conditions (600 rpm, 30°C, and pH 6.0), the maximum BGL activity of 10.4 U/ml with the overall productivity of 74.5 U/l/h was observed. BGL production was scaled up from a laboratory scale (7-L fermenter) to a pilot scale (70-L fermenter). When S. hirsutum was cultured in fed-batch culture with rice straw as the carbon source in a 70-L fermenter, a comparable productivity of 78.6 U/l/h was obtained. Furthermore, S. hirsutum showed high levels of activity of other lignocellulases (cellobiohydrolase, endoglucanase, xylanase, and laccase) that are involved in the saccharification of biomasses. Application of S. hirsutum lignocellulases in the hydrolysis of Pinus densiflora and Catalpa ovata showed saccharification yields of 49.7% and 43.0%, respectively, which were higher than the yield obtained using commercial enzymes.

One-pot synthesis of yolk-shell materials with single, binary, ternary, quaternary, and quinary systems

A facile, one-pot method of systematically synthesizing yolk-shell materials with complex compositions is proposed. The spray pyrolysis process for obtaining yolk-shell materials is advantageous because it is highly efficient, allows high throughput, comprises a single-step reaction, and is a continuous process that yields homogeneous composition and enables facile control of the mean size.

One-pot facile synthesis of Janus-structured SnO2-CuO composite nanorods and their application as anode materials in Li-ion batteries

SnO2-CuO composite nanorods with a Janus structure were prepared by one-step flame spray pyrolysis. High-aspect-ratio SnO2 nanorods were positioned on one side of the spherical CuO powder. The mean length of the rod-shaped crystals decreased from 200 to 20 nm when the SnO2 content in the composite powders decreased from 70 to 10 wt%. Initially, SnO2-CuO composite nanopowders formed from the vapors in the high-temperature diffusion flame by surface growth and coagulation. Phase separation of the composite nanopowders occurred and rod-like Janus structures evolved during the growth of SnO2 and CuO crystals in the quenching process. The maximum charge capacities of pure SnO2 and the composite powders with SnO2/CuO of 90/10, 70/30, and 50/50 were 547, 499, 493, and 316 mA h g(-1), respectively, at a high current density of 3000 mA g(-1). The corresponding capacity retentions after 50 cycles were found to be 39, 47, 80, and 85%, respectively. The decrease in the charge capacity with increasing current density was slower in SnO2-CuO (70/30) composite powders than in pure SnO2. The Janus-structured SnO2-CuO (70/30) composite powders showed a high charge capacity and excellent cycling performance at high current densities.

Electrochemical properties of ZrO2-doped V2O5 amorphous powders with spherical shape and fine size

Amorphous V2O5 powders with zirconia (ZrO2) dopant are prepared by one-pot spray pyrolysis at temperatures above the melting temperature of V2O5. The powders with 7 wt % ZrO2 are completely spherical and dense with a clean surface, on which crystals of pure V2O5 powders are scarcely observed. The V2O5 powders with 7 wt % ZrO2 have uniformly distributed V and Zr components. The uniformly distributed Zr component disturbs the crystallization of V2O5 during the quenching of the melted powders. These powders also give smooth initial discharge curves with a single slope, which is typical to amorphous materials. The discharge capacities of the V2O5 powders with 7 wt % ZrO2 are 309, 269, and 222 mA h g(-1) after the first, second, and 50th cycles, respectively, even at a high current density of 294 mA g(-1). The capacity retention measured after the first cycle is 83% after 50 cycles.

Enzymatic hydrolysis of aspen biomass into fermentable sugars by using lignocellulases from Armillaria gemina

A white rot fungus, identified as Armillaria gemina SKU2114 on the basis of morphological and phylogenetic analyses, was found to secrete efficient lignocellulose-degrading enzymes. The strain showed maximum endoglucanase, cellobiohydrolase, and β-glucosidase activities of 146, 34, and 15 U/mL, respectively, and also secreted xylanase, laccase, mannanase, and lignin peroxidase with activities of 1270, 0.16, 57, and 0.31 U/mL, respectively, when grown with rice straw as a carbon source. Among various plant biomasses tested for saccharification, aspen biomass produced the maximum amount of reducing sugar. Response surface methodology was used to optimize the hydrolysis of aspen biomass to achieve the highest level of sugar production. A maximum saccharification yield of 62% (429 mg/g-substrate) was obtained using Populus tomentiglandulosa biomass after 48 h of hydrolysis. A. gemina was shown to be a good option for use in the production of reducing sugars from lignocellulosic biomass.

Molecular cloning and characterization of a GH11 endoxylanase from Chaetomium globosum, and its use in enzymatic pretreatment of biomass

An endo-1,4-β-xylanase gene, xylcg, was cloned from Chaetomium globosum and successfully expressed in Escherichia coli. The complete gene of 675 bp was amplified, cloned into the pET 28(a) vector, and expressed. The optimal conditions for the highest activity of the purified recombinant XylCg were observed at a temperature of 40 °C and pH of 5.5. Using oat-spelt xylan, the determined K m, V max, and k cat/K m values were 0.243 mg ml⁻¹, 4,530 U mg⁻¹ protein, and 7,640 ml s⁻¹ mg⁻¹, respectively. A homology model and sequence analysis of XylCg, along with the biochemical properties, confirmed that XylCg belongs to the GH11 family. Rice straw pretreated with XylCg showed 30 % higher conversion yield than the rice straw pretreated with a commercial xylanase. Although xylanases have been characterized from fungal and bacterial sources, C. globosum XylCg is distinguished from other xylanases by its high catalytic efficiency and its effectiveness in the pretreatment of lignocellulosic biomass.

Saccharification of poplar biomass by using lignocellulases from Pholiota adiposa

A basidiomycetous fungus, identified as Pholiota adiposa SKU0714 on the basis of morphological and phylogenetic analyses, was found to secrete efficient lignocellulose degrading enzymes. The strain showed maximum endoglucanase, cellobiohydrolase and β-glucosidase activities of 26, 32 and 39 U/mL, respectively and also secreted xylanase, laccase, mannanase, and lignin peroxidase with activities of 1680, 0.12, 65 and 0.41 U/mL, respectively when grown with rice straw as a carbon source. Among the various plant biomasses tested for saccharification, poplar biomass produced the maximum amount of reducing sugar. Response surface methodology was used to optimize hydrolysis parameters. A maximum saccharification yield of 83.4% (667 mg/g-substrate), the highest yield from any plant biomass, was obtained with Populus biomass after 24h of hydrolysis. P. adiposa was proven to be a good choice for the production of reducing sugars from cellulosic biomass.

Investigation of the characteristics of platinum group metal modified alumina nanofibers

Alumina nanofibers containing either platinum or rhodium crystalline nanoparticles have been successfully fabricated by electrospinning a solution of polyvinylpyrrolidone mixed with platinum or rhodium chloride and subsequent calcination and hydrogen reduction. Transmission electron microscopy images indicate that the platinum and rhodium nanoparticles are well dispersed on the electrospun alumina nanofibers. X-ray diffraction results demonstrate that the platinum and rhodium nanoparticles are crystalline, while the alumina matrix is amorphous. Furthermore, X-ray photoelectron spectroscopy was used to investigate the chemical nature of these nanofibers containing noble metals before and after calcination and hydrogen processing.

Synthesis of nano-sized biphasic calcium phosphate ceramics with spherical shape by flame spray pyrolysis

Nanometer size biphasic calcium phosphate (BCP) powders with various Ca/P molar ratios satisfied with appropriate phase ratios of HA/beta-TCP were prepared by high temperature flame spray pyrolysis process. The BCP powders had spherical shapes and narrow size distributions irrespective of the ratios of Ca/P. The mean size of the BCP powders measured from the TEM image was 38 nm. The composition ratio of Ca/P was controlled from 1.500 to 1.723 in the spray solution, and required phase ratios of HA/TCP are controlled systematically. The calcium dissolution of the pellets obtained from the BCP powders directly prepared by flame spray pyrolysis in buffer solution increased with the decrease of Ca/P ratios except with the Ca/P ratio of 1.713. The pellet surface with Ca/P ratio of 1.500, which consisted of beta-TCP, was eroded dramatically for 7 days. On the other hand, the pellet surface with Ca/P ratio of 1.667 was stable and did not disintegrate after immersion in Tris-HCl buffer solution based on the SEM observation.

Dimethyl methylphosphonate decomposition on Cu surfaces: supported Cu nanoclusters and films on TiO2(110)

The thermal decomposition of dimethyl methylphosphonate (DMMP), which is a simulant molecule for organophosphorus nerve agents, has been investigated on Cu clusters as well as on Cu films deposited on a TiO(2)(110) surface. Scanning tunneling microscopy studies were conducted to characterize the cluster sizes and surface morphologies of the deposited Cu clusters and films. Temperature-programmed desorption experiments demonstrated that the surface chemistry of DMMP is not sensitive to the size of the Cu clusters over the range studied in this work. DMMP reaction on an annealed 40 monolayer Cu film resulted in the desorption of H(2), methane, methyl, formaldehyde, methanol, and molecular DMMP, and reaction on the small (4.4 +/- 0.9 nm diameter, 1.8 +/- 0.6 nm height) and large (10.7 +/- 1.9 nm diameter, 4.8 +/- 1.0 nm height) Cu clusters generated similar products. Formaldehyde and methane production is believed to occur via a methoxy intermediate on the Cu surface. These products are favored on the higher coverage Cu films that completely cover the TiO(2) surface since competing reaction pathways on TiO(2) are suppressed. X-ray photoelectron spectroscopy studies showed that DMMP begins to decompose on the Cu clusters upon adsorption at room temperature and that atomic carbon, atomic phosphorus, and PO(x) remain on the surface after DMMP decomposition.

Egg production capacity of one-pair worms of Schistosoma japonicum in albino mice

In the present study, a series of procedures of egg count were carried out to determine the egg production capacity in 21 ICR mice each infected with one-pair of Schistosoma japonicum. The egg count began from the first day, they were detected in the feces, which was based on a stool collection over 24 hours, twice a week. Each female S. japonicum produced an average of 2,198 eggs/day during the study period of 99 days after infection (ranged 61-147 days). Fourty-seven percent of the eggs were in the feces and 53% in tissues (45% in large intestine, 31% in small intestine, 23% in liver, 0.4% in pancreas, 0.2% in lungs, 0.1% in spleen, 0.1% in lymph nodes, 0.06% in stomach and 0.05% in heart, kidney, diaphragm and brain).