Investigations on the structural, optical and electrical properties of Nb-doped SnO2 thin films

Niobium-doped tin oxide thin films were deposited on glass substrates by the chemical spray pyrolysis method at a substrate temperature of 400 °C. Effects of Nb doping on the structural, electrical and optical properties have been investigated as a function of niobium concentration (0–2 at.%) in the spray solution. X-ray diffraction patterns showed that the films are polycrystalline in nature and the preferred growth direction of the undoped film shifts to (200) for Nb-doped films. Atomic force microscopy study shows that the surface morphology of these films vary when doping concentration varies. The negative sign of Hall coefficient confirmed the n-type conductivity. Resistivity of ~4.3 × 10⁻³ Ω cm, carrier concentration of ~5 × 10¹⁹ cm⁻³, mobility of ~25 cm² V⁻¹ s⁻¹ and an average optical transmittance of ~70% in the visible region (500–800 nm) were obtained for the film doped with 0.5 at.% niobium.     

A strategic model using structural equation modeling and fuzzy logic in supplier selection

Supplier selection attained the state of paramount importance for companies in the current scenario because of increasing global competition. Improper selection of suppliers will have an adverse impact on the overall performance of the company. The number of available alternatives in the current market is on a rise, and hence it becomes difficult to select a supplier from among a large lot. An attempt has been made to develop a new composite model using structural equation modeling and fuzzy analytic hierarchy process technique, based on the results of a survey of 151 respondents. Based on the criteria that influence the selection of suppliers, the model has been developed. The study also examines the supplier selection criteria and measures the supplier selection score using the developed model.     

Cathodic protection of steel in concrete using magnesium alloy anode

Corrosion of steel embedded in concrete structures and bridges is prevented using cathodic protection. Majority of the structures protected employ impressed current system. Use of sacrificial system for the protection of steel in concrete is not as widely employed. The use of magnesium anodes for the above purpose is very limited. This study has been carried out with a view to analyse the use of magnesium alloy anode for the cathodic protection of steel embedded in concrete.Magnesium alloy anode, designed for three years life, was installed at the center of reinforced concrete slab, containing 3.5% sodium chloride with respect to weight of cement, for cathodic protection. Potential of the embedded steel and the current flowing between the anode and the steel were monitored, plotted and analyzed. Chloride concentration of concrete at different locations, for different timings, were also determined and analyzed.The magnesium anode was found to shift the potential of the steel to more negative potentials initially, at all distances and later towards less negative potentials. The chloride concentration was found to decrease at all the locations with increase in time. The mechanism of cathodic protection with the sacrificial anode could be correlated to the removal of corrosive ions such as chloride from the vicinity of steel.     

PTT——创新的聚合物及其在纺织品中的用途

被称为聚对苯二甲酸丙二酯（PTT）的芳族聚酯,例如Shell公司的Corterra PTT已为人所周知。Corterra PTT聚合物是由对苯二甲酸（PTA）和1,3-丙二醇（PDO）通过缩聚反应生产的。PTT可与其他的芳族聚酯——聚对苯二甲酸乙二酯（PET）和聚对苯二甲酸丁二酯（PBT）以及聚酰胺相竞争。     

Bactericidal effects of Lactobacillus reuteri and allyl isothiocyanate on Escherichia coli O157:H7 in refrigerated ground beef

Two naturally occurring antimicrobial agents were tested in packages of refrigerated ground beef for their ability to reduce the viability of Escherichia coli O157:H7 during storage. Allyl isothiocyanate (AITC) and Lactobacillus reuteri were tested separately and together for their action against a cocktail of five strains of E. coli O157:H7 in ground beef held at 4 degrees C for 25 days. Ground beef prepared from whole, raw inside round beef roasts was inoculated with low (3 log CFU/g) or high (6 log CFU/g) levels of the E. coli O157:H7 mixture. The beef was treated with AITC (about 1,300 ppm), L. reuteri, or both, along with 250 mM of glycerol per kg of meat at two levels (3 and 6 log CFU/g) and according to a design that yielded 8 controls plus 10 different treatments. Samples were analyzed for E. coli O157:H7 survivors, numbers of total bacteria, and lactic acid bacteria on days 0 to 25 at 5-day intervals. L. reuteri at both input levels with glycerol killed E. coli O157:H7 at both inoculated levels before day 20. AITC completely eliminated E. coli O157:H7 at the low-inoculum level (3 log CFU/g) and reduced viability >4.5 log CFU/g at the high-inoculum level (6 log CFU/g) by the end of the storage period. The combination of L. reuteri and AITC did not yield an additive effect against E. coli O157:H7 viability. L. reuteri in the presence of glycerol was highly effective against E. coli O157:H7 in ground beef during refrigerated storage (4 degrees C) in modified atmosphere packages. Sensory testing is planned to evaluate effects of treatments.     

Occurrence and distribution of lipoxygenase in Camellia sinensis (L) O Kuntze and their changes during CTC black tea manufacture under southern Indian conditions

The optimal activity of tea lipoxygenase was found to be at pH 7·5 and 9·0, indicating the presence of two types of isoenzymes. Tea lipoxygenase was inhibited by cyanide and a small fraction appeared to be quite heat stable. Clonal and seasonal variations in lipoxygenase activity was significant. An increase in lipoxygenase activity was observed with leaf maturity. The lipoxygenase activity decreases with age from pruning and increases with an increase in plucking interval. The changes of lipoxygenase activity during CTC manufacture revealed that it increased with the degree of withering and upon rolling. However, a gradual decline was recorded during the fermentation and drying processes. The residual lipoxygenase activity in black tea is expected to affect its quality on storage. © 1998 Society of Chemical Industry.     

Continuous biogenic hydrogen production from dilute acid pretreated algal hydrolysate using hybrid immobilized mixed consortia

This study investigated the bioconversion of dilute acid (2% H₂SO₄) pretreated red algae (Gelidium amansii) hydrolysate into H₂ by anaerobic fermentation in a continuous stirred tank reactor under mesophilic conditions using hybrid immobilized cells as microbial catalyst. Two different hydraulic retention times (HRT) of 24 h and 16 h with a feed concentration of 15 g/L hexose equivalent have been investigated over 85 days of operation to evaluate H₂ production performance and stability of the continuous system. The highest hydrogen production rate (HPR) and hydrogen yield (HY) of 2.7 L/L/d and 1.3 mol/mol substrate hexose_added was achieved at 24 h HRT, while further operation at 16 h HRT led to a significant drop in the hydrogen production with a HPR and HY values of 1.8 L/L/d and 0.7 mol/mol substrate hexose_added, respectively. The bacterial community analysis characterized by 454 pyrosequencing revealed that the changes in HRT significantly influence the composition of the dominant microflora. At longer HRT (24 h), the phyla Firmicutes was abundant over 98%, whereas at shorter HRT (16 h), Proteobacteria being the dominant populations with 84%. These outcomes suggested that controlling appropriate HRT is prerequisite for efficient hydrogen production.     

Ni0.5Zn0.5Fe2O4-dispersed In2O3-spotted ZnO nanoparticles: Ammonia-source and surface and photocatalytic properties

Ammonia-source, used to attain the desired pH during synthesis, is conceived to influence the physical characteristics of ZnO-based nanomaterials, and the catalytic activity is susceptible to surface characteristics of semiconductor–photocatalyst. In this context, Ni_0.5Zn_0.5Fe₂O₄-dispersed In₂O₃-spotted ZnO nanoparticles have been obtained by using either tetramethyl ammonium hydroxide or ammonium carbonate as ammonia-source at identical pH (9) using identical quantities of the precursors following identical synthetic procedure. The nanoparticles have been characterized using energy dispersive X-ray spectroscopy, elemental mapping, selected area electron and X-ray diffractometries, transmission electron microscopy, etc. The nanoparticles obtained using ammonium carbonate possess larger (1) pore width, (2) pore volume, and (3) surface area compared with nanoparticles prepared employing tetramethyl ammonium hydroxide. Although the electrical properties of both the samples do not differ remarkably, the violet light-absorption of the sample prepared using the carbonate is slightly larger than that of the other sample. Further, the In₂O₃-spotting is slightly larger on using ammonium carbonate than using tetramethyl ammonium hydroxide. To degrade dye under visible light, the sample obtained using ammonium carbonate shows larger catalytic activity compared with nanoparticles prepared using tetramethyl ammonium hydroxide. The observed photocatalytic activities are explained based on the surface characteristics.     

Effects of O swift heavy ion irradiation on indium oxide thin films

Indium oxide thin films deposited by spray pyrolysis were irradiated by 100 MeV O⁷⁺ ions with different fluences of 5 × 10¹¹, 1 × 10¹² and 1 × 10¹³ ions/cm². X-ray diffraction analysis confirmed the structure of indium oxide with cubic bixbyite. The strongest (2 2 2) orientation observed from the as-deposited films was shifted to (4 0 0) after irradiation. Furthermore, the intensity of the (4 0 0) orientation was decreased with increasing fluence together with an increase in (2 2 2) intensity. Films irradiated with maximum fluence exhibited an amorphous component. The mobility of the as-deposited indium oxide films was decreased from ∼78.9 to 43.0 cm²/V s, following irradiation. Films irradiated with a fluence of 5 × 10¹¹ ions/cm² showed a better combination of electrical properties, with a resistivity of 4.57 × 10⁻³ Ω cm, carrier concentration of 2.2 × 10¹⁹ cm⁻³ and mobility of 61.0 cm²/V s. The average transmittance obtained from the as-deposited films decreased from ∼81% to 72%, when irradiated with a fluence of 5 × 10¹¹ ions/cm². The surface microstructures confirmed that the irregularly shaped grains seen on the surface of the as-deposited films is modified as “radish-like” morphology when irradiated with a fluence of 5 × 10¹¹ ions/cm².