Photocatalytic activities of electrospun tin oxide doped titanium dioxide nanofibers

SnO₂ doped TiO₂ electropsun nanofiber photocatalysts were successfully prepared by means of electrospinning process. The surface morphology, structure and optical properties of the resultant products were characterized by field-emission electron microscopy (FE-SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy, photoluminescence (PL) and cathodoluminescence (CL) techniques. The utilized physiochemical analyses indicated that the introduced SnO₂ doped TiO₂ nanofibers have a smooth surface and uniform diameters along their lengths. The photocatalytic performance of the composite nanofibers was tested for degradation of methylene blue (MB) and methyl orange (MO) dye solution under ultraviolet (UV) irradiation. Under the UV irradiation, the photocatalytic reaction rate in case of utilizing SnO₂-doped TiO₂ nanofibers was rapidly increased than that of the pristine TiO₂ nanofibers. Overall, this study demonstrates cheap, stable and effective material for photocatalytic degradation at room temperature.     

Effects of gamma irradiation on the thermal and mechanical properties of chitosan/PVA nanofibrous mats

Chitosan/poly(vinyl alcohol) (PVA) nanofibrous mats were prepared by the electrospinning method. The morphology and structure of electrospun nanofibers were investigated by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. SEM images showed that the uniform and bead-free fibers were obtained at concentrations greater than 8 wt%. Chitosan/PVA mats were irradiated with different doses (50–200 kGy) of ⁶⁰Co gamma rays. The effect of irradiation dose on the mechanical and thermal properties of these films was also investigated. Increasing the irradiation dose led to a decrease in tensile strength. FT-IR and DSC demonstrated that there were strong intermolecular hydrogen bonds between the chitosan and PVA molecules.     

Fatty Acids Released from Milk Fat by Lipoprotein Lipase and Lipolytic Psychrotrophs

ABSTRACT: The ability of 13 different strains of psychrotrophs to release free fatty acids in milk was evaluated by using GC analysis. The 13 strains could be categorized into 3 groups: Group 1 consisted of bacteria that grew well and released large quantities of free fatty acids, group 2 consisted of bacteria that grew well but released low amounts of free fatty acids, and group 3 consisted of bacteria that did not grow well nor released large quantities of fatty acids. In group 1, 3 strains were determined to be highly lipolytic, releasing short‐chain fatty acids in amounts greater than reported threshold values. Group 3 consisted of 2 strains, which did not grow well in heat‐treated milk, and the subsequent release of free fatty acids was minor during the 10‐d monitoring time. The other 8 strains tested showed no specific pattern of fatty acid release and quantities of short‐chain fatty acids were not large, despite the ability to grow to high numbers in the treated milk. This work indicates that the lipolytic activity of psychrotrophs common in raw milk is specific to the species and a general prediction of free fatty acid release may not be possible.     

Chemical reduction of U(VI) by Fe(II) at the solid-water interface using natural and synthetic Fe(III) oxides

Abiotic reduction of 0.1 mM U(VI) by Fe(II) in the presence of synthetic iron oxides (biogenic magnetite, goethite, and hematite) and natural Fe(III) oxide-containing solids was investigated in pH 6.8 artificial groundwater containing 10 mM NaHCO3. In most experiments, more than 95% of added U(VI) was sorbed to solids. U(VI) was rapidly and extensively (> or = 80%) reduced in the presence of synthetic Fe(III) oxides and highly Fe(II) oxide-enriched (18-35 wt % Fe) Atlantic coastal plain sediments. In contrast, long-term (20-60 d) U(VI) reduction was less than 30% in suspensions of six other natural solids with relatively low Fe(III) oxide content (1-5 wt % Fe). Fe(II) sorption site density was severalfold lower on these natural solids (0.2-1.1 Fe(II) nm(-2)) compared tothe synthetic Fe(lII) oxides (1.6-3.2 Fe(II) nm(-2)), which may explain the poor U(VI) reduction in the natural solid-containing systems. Addition of the reduced form of the electron shuttling compound anthrahydroquinone-2,6-disulfonate (AH2DS; final concentration 2.5 mM) to the natural solid suspensions enhanced the rate and extent of U(VI) reduction, suggesting that AH2DS reduced U(VI) at surface sites where reaction of U(VI) with sorbed Fe(II) was limited. This study demonstrates that abiotic, Fe(II)-driven U(VI) reduction is likely to be less efficient in natural soils and sediments than would be inferred from studies with synthetic Fe(III) oxides.     

Catalysts characteristics of Ni/YSZ core-shell according to plating conditions using electroless plating

This study aims to develop an anode catalyst for a solid oxide fuel cell (SOFC) using electroless nickel plating. We have proposed a new method for electroless plating of Ni metal on yttria-stabilized zirconia (YSZ) particles. We examine the uniformity of the Ni layer on the plated core-shell powder, in addition to the content of Ni and the reproducibility of the plating. We have also evaluated the carbon deposition rate and characteristics of the SOFC anode catalyst. To synthesize Ni-plated YSZ particles, the plated powder is heat-treated at 1200 °C. The resultant particles, which have an average size of 50 μm, were subsequently used in the experiment. The size of the Ni particles and the Ni content both increase with increasing plating temperature and plating time. The X-ray diffraction pattern reveals the growth of Ni particles. After heat-treatment, Ni is oxidized to NiO, leading to the co-existence of Ni and NiO; Ni₃P is also observed due to the presence of phosphorous in the plating solution. Following heat treatment for 1 h at 1200 °C, Ni is mostly oxidized to NiO. The carbon deposition rate of the reference YSZ powder is ~135%, while that of the Ni-plated YSZ is 1%-6%.     

MECHANISMS OF ICE CRYSTALLIZATION AND RECRYSTALLIZATION IN ICE CREAM: A REVIEW

This review article focuses on the mechanisms of ice crystallization and recrystallization and factors that influence them in ice creams. Ice crystallization is an important factor that determines ice cream's final quality. The smaller the ice crystal size is in the final product, the better the quality is. Large ice crystals cause a coarse, grainy, and icy texture in ice cream. The initial ice crystals are formed in the freezer barrel and then grow in size during hardening and storage. Recrystallization during storage is influenced by various factors, including total solids, initial freezing temperature, unfrozen water, stabilizer type, sweetener type, and storage temperature. The roles of these factors, especially stabilizers, are discussed.     

Two additional cases of metformin‐associated encephalopathy in patients with end‐stage renal disease undergoing hemodialysis

We report on two additional cases of metformin‐associated encephalopathy in patients with end‐stage renal disease (ESRD) undergoing hemodialysis. Two patients were seen at our hospital with abnormal neurological signs and symptoms. Magnetic resonance imaging (MRI) revealed the same pattern of high signal intensity in both basal ganglia in T2‐weighted images in the two patients. The two patients had started taking metformin 5 and 6 weeks earlier at the same dose of 1000 mg per day. Metformin was immediately stopped, and regular hemodialysis was conducted. Their signs and symptoms resolved completely after these measures. The high signal intensity in both ganglia in T2‐weighted MRI also disappeared. We should suspect metformin‐induced encephalopathy and withdraw the drug when presented with diabetic patients with chronic kidney disease and neurological signs and symptoms of unknown cause.     

Die quenching limit of AA2024 aluminum alloy billet on servo press

Die quenching of AA2024 aluminum alloy billets was carried out on a servo press with ram-motion control of WC-20 mass%Co dies directly after solution heat treatment (SHT). To clarify the dependence on billet size for die quenching, two billets with a height of h₀ = 8 mm or 16 mm and with the same diameter of 16 mm were prepared. The cylindrical billets were heated in an electric furnace at 823 K and transferred to the press. Then the billets were uniaxially compressed with a reduction in height (Δh/h₀) of 2% or 5%, and further held between the dies. The sandwiching duration by dies (t_d.q.) was varied from 0 to 8 s. Based a measured temperature change, hardness and TG–DTA analysis, it is found that die quenching is successfully carried out without precipitation hardening only in the case of the billet with a height of 8 mm and t_d.q. > 6 s. The reduction in height is limited less than 5% by intergranular fracture on side surface of billet during the die quenching process.     

Utilization of carbon derived from mustard oil cake (CMOC) for the removal of bivalent metal ions: Effect of anionic surfactant on the removal and recovery

Effect of sodium dodecyl sulfate (SDS) on the adsorption of Zn(II) and Ni(II) on CMOC was investigated. Addition of SDS favored the adsorption process. Adsorption process was found to be dependent on concentration, pH, dose, contact time and temperature. Thermodynamic studies showed that the process is endothermic and spontaneous. The spontaneity increases with increase in temperature. D–R isotherm suggests that the adsorption is chemical in nature. Kinetics studies showed better applicability of pseudo second order model. Reichenberg equation showed that pore diffusion was not only the rate determining step but some other process like film diffusion was also involved in the adsorption. These metals could be desorbed (75–80%) with 0.1 M HCl as eluent.