Preparation of Cu nanoparticles with ascorbic acid by aqueous solution reduction method

Cu nanoparticles were prepared by reducing Cu2＋ ions with ascorbic acid through aqueous solution reduction method. The effects of solution pH and average size of Cu2O particles on the preparation of Cu nanoparticles were investigated. Cu particles were prepared at pH 3, 5 or 7, with the smallest Cu particles obtained at pH 7. However, Cu particles could not be prepared at pH 9 or 11. The average size of Cu2O particles can affect that of Cu particles. Larger Cu2O particles result in larger Cu particles. In addition, experiments were conducted to explore the reaction process by measuring the X-ray diffraction （XRD） patterns of specimens collected at different time points during the reaction. It was found that Cu（OH）2 was initially formed as a precursor, followed by the formation of Cu2O, which was finally reduced to Cu particles.

Development of a miniature silicon wafer fuel cell using L-ascorbic acid as fuel

In the current studies a miniature silicon wafer fuel cell(FC) using L-ascorbic acid as fuel was developed. The cell employs L-ascorbic acid and air as reactants and a thin polymer electrolyte as a separator. Inductively coupled plasma(ICP) silicon etching was employed to fabricate high aspect-ratio columns on the silicon substrate to increase the surface area. A thin platinum layer deposited directly on the silicon surface by the sputtering was used as the catalyst layer for L-ascorbic acid electro-oxidation. Cyclic voltammetry shows that the oxidation of L-ascorbic acid on the sputtered platinum layer is irreversible and that the onset potentials for the oxidation of L-ascorbic acid are from 0.27 V to 0.35 V versus an Ag/AgCl reference electrode. It is found that at the room temperature,with 1 mol/L L-ascorbic acid/PBS(phosphate buffered solution) solution pumped to the anode at 1 ml/min flow rate and air spontaneously diffusing to the cathode as the oxidant,the maximum output power density of the cell was 1.95 mW/cm2 at a current density of 10 mA/cm2.

Measurement and Correlation on Viscosity and Apparent Molar Volume of Ternary System for L-ascorbic Acid in Aqueous D-Glucose and Sucrose Solutions

Viscosities and densities at several temperatures from 293.15 K to 313.15K are reported for L-ascorbic acid in aqueous glucose and sucrose solutions at different concentrations. The parameters of density, viscosity coefficient B and partial molar volume are calculated by regression. The experimental results show that densities and viscosities decrease as temperature increases at the same solute and solvent (glucose and sucrose aqueous solution) concentrations, and increase with concentration of glucose and sucrose at the same solute concentration and temperature. B increases with concentration of glucose and sucrose and temperature. L-ascorbic acid is structure-breaker or structure-making for the glucose and sucrose aqueous solutions. Furthermore, the solute-solvent interactions in ternary systems of water-glucose-electrolyte and water-sucrose-electrolyte are discussed.

Antiphotooxidative Effect of Ascorbic Acid Microemulsion in Virgin Coconut Oil

This study was intended to determine the effectiveness of ascorbic acid microemulsion for inhibiting photooxidation of virgin coconut oil （VCO）. The ascorbic acid microemulsion was prepared by mixing ascorbic acid, deionized water, surfactant mixture, and VCO as continuous phase. Ascorbic acid microemulsion at 50, 100, 150, 200, or 250 ppm was dispersed into VCO. The same level of ascorbyl palmitate, TBHQ （tertiary butylhydroquinone）, and BHA （butylated hidroxyanisole） were added into VCO and used for comparison. All of these samples were subsequently subjected to photooxidation under fluorescent light exposure （4,000 lux） for up to 8 hours at room temperature （30 ~ 1 ~C）. Peroxide values and p-anisidine values of photooxidized samples were measured at 1 hour interval. The result indicated that at the level of 250 ppm, ascorbic acid which was included into the microemulsion system effectively inhibited photooxidation of VCO in comparison with the other antioxidants. This study confirmed that a highly hydrophilic singlet oxygen quencher （SOQ） such as ascorbic acid can be successfully incorporated into the microemulsion system and the addition of ascorbic acid microemulsion effectively inhibited photooxidation of VCO during storage under fluorescent light.

食用菌保鲜验方

氯化钠(即食盐)保鲜 新采收的平菇、风尾菇等经整理后浸入0．6％的盐水中约10分钟，捞出沥干后装入塑料袋内贮藏，能保鲜5天～8天。

Effect of oral administration of vitamin C on human aqueous humor ascorbate concentration

AIM:To study oral administration of vitamin C on human aqueous humour ascorbate concentration.METHODS:High performance liquid chromatography(HPLC)coupled with electrochemical detector(BCD)was used.The effect of oral administration of various doses of ascorbic acid,0(control),1.0,1.5,2.0,3.0,and 5.0 g,on its concentration in aqueous humour,obtained from volunteer cataract patients was studied.RESULTS:The concentration of ascorbic acid in aqueous humour of control group without administration of vitamin-C tablet or drug containing ascorbic acid was(254±119)mg·L^(-1).This study revealed that the administration of 2.0 g of.ascorbic acid saturate the aqueous humour and further increase in the dose(3.0 g and 5.0 g)did not increase its concentration in aqueous humour,although its concentration was increased in plasma.CONCLUSION:Oral administration of 2.0 g of Vc is sufficient to saturate the aqueous humour where it may be helpful in controlling the intra-ocular pressure.