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.

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.

Alteration of chemical behavior of L-ascorbic acid in combination with nickel sulfate at different pH solutions in vitro

Objective:To evaluate the alteration of chemical behavior of L-ascorbic acid(vitamin C) with metal ion(nickel) at different pH solutions in vitro.Methods:Spectra of pure aqueous solution of L-ascorbic acid(E mark) compound and NiSO_4(H_2O)(sigma USA) were evaluated by UV visible spectrophotometer.Spectral analysis of L-ascorbic acid and nickel at various pH(2.0, 7.0,7.4 and 8.6) at room temperature of 29℃ was recorded.In this special analysis,combined solution of L-ascorbic acid and nickel sulfate at different pH was also recorded.Results:The result revealed that λ_(max)(peak wavelength of spectra) of L-ascorbic acid at pH 2.0 was 289.0 run whereas at neutral pH 7.0,λ_(max) was 29S.4 run.In alkaline pH 8.6,λ_(max) was 295.4 nm and at pH 7.4 the λ_(max) of L-ascorbic acid remained the same as 295.4 nm.Nickel solution at acidic pH 2.0 was 394.5 nm,whereas at neutral pH 7.0 and pH 7.4 were the same as 394.5 nm.But at alkaline pH 8.6,λ_(max) value of nickel sulfate became 392.0 nm.The combined solution of L-ascorbic acid and nickel sulfate(6 mg/mL each) at pH 2.0 showed 292.5 nm and 392.5 nm,respectively whereas at pH 7.0,L-ascorbic acid showed 296.5 nm and nickel sulfate showed 391.5 nm.At pH 7.4,L-ascorbic acid showed 297.0 nm and nickel sulfate showed 394.0 nm in the combined solution whereas at pH 8.6(alkaline) L-ascorbic acid and nickel sulfate were showing 297.0 and 393.5 nm,respectively. Conclusions:Results clearly indicate an altered chemical behavior of L-ascorbic acid either alone or in combination with nickel sulfate in vitro at different pH.Perhaps oxidation of L-ascorbic acid to L-dehydro ascorbic acid via the free radical(HSc*) generation from the reaction of H,ASc + Ni(Ⅱ) is the cause of such alteration of λ_(max),value of L-ascorbic acid in the presence of metal nickel.

CHEMOTHERAPEUTIC POLYMERS ⅩⅩⅢ SYNTHESIS AND ANTITUMOR ACTIVITY OF POLYPHOSPHATES CONTAINING BOTH NUCLEIC ACID BASE AND PHOSPHONOACETIC ACID ETHYL ESTER

Eight new polyphosphates containing both nucleic acid base and phosphonoacetic acid ethyl ester were synthesized by the polycondensation of P, P-dichloride of phosphonoacetic acid ethyl ester with 1, 3-dihydroxyalkyl-5-fluorouracil, 1,3-dihydroxyalkyl-uracil and 1,3-dihydroxyalkylthymine. These polyphosphates were tested against Ehrlich Ascites Carcinoma in mice. Polymer IIa and IIc exhibited excellent antitumor activity. IIc also showed lower toxicity.

Synthesis, Crystal Structure and Antioxidant Activity of 5,6-O-(4-bromophenyl)-L-ascorbic Acid

The title compound 5,6-O-（4-bromophenyl）-L-ascorbic acid （C13H11BrO6, Mr = 343.13） has been synthesized and its structure was characterized by IR, 1H NMR and single-crystal X-ray diffraction. The product is a mixture of two diastereomer compounds （a （7S） and b （7R））. The crystal of a （7S） belongs to orthorhombic system, space group P212121 with a = 6.5362（10）, b = 7.8226（11）, c = 25.294（4） ？, V = 1293.3（3） ？3, Z = 4, Dc = 1.762 g/cm3, μ（MoKα） = 3.202 mm-1, F（000） = 688, R = 0.0235 and wR （I 〉 2σ（I）） = 0.0566. The hydrogen bonding interactions link the molecules to form a three-dimensional system. In addition, 5,6-O-（4-bromophenyl）-L-ascorbic acid （BPAA） exhibits strong free-radical scavenging activities in vitro against 2,2-diphenyl-1-picrylhy- drazyl and superoxide anion. BPAA should be investigated further as a worthy antioxidant.

Supplementation of L-ascorbic acid improves the in vitro development of buffalo(Bubalus bubalis)embryos and alters the expression of apoptosis-related genes

Objective:To study the effect of L-ascorbic acid supplementation on the in vitro development of buffalo embryos and evaluate the relative mRNA abundance of some pro-apoptotic,anti-apoptotic,and embryonic development-related genes.Methods:In experiment 1,we evaluated the effect of the addition of 0(control),50,and 100μM L-ascorbic acid to the in vitro maturation medium on the developmental competence in terms of blastocyst rate and relative mRNA abundance of some pro-apoptotic(BAX,BID),anti-apoptotic(BCL-XL,MCL1),and embryonic development(GDF9,BMP15)related genes.Based on the results,we chose 50μM as the suitable dose of L-ascorbic acid for the subsequent experiments.We further evaluated the blastocyst rates following the addition of 50μM L-ascorbic acid to the in vitro culture medium(experiment 2),and in vitro maturation and in vitro culture media(experiment 3).In all three experiments,the maturation and culture media devoid of L-ascorbic acid served as the control group.Results:The blastocyst rate after adding 50μM L-ascorbic acid to the in vitro maturation medium was significantly higher than the control group(P<0.05),whereas 100μM L-ascorbic acid exhibited a negative effect on the blastocyst rate.The blastocyst rates for embryos cultured in 50μM L-ascorbic acid in the in vitro culture medium alone and both in vitro maturation and in vitro culture media were significantly higher than their corresponding control groups(P<0.05).The relative mRNA abundance of BAX significantly decreased in blastocysts produced after the addition of 50μM L-ascorbic acid as compared with the control group(P<0.05),whereas,for MCL1,it significantly decreased in blastocysts produced after the addition of 100μM L-ascorbic acid(P<0.05).Conclusions:The supplementation of 50μM L-ascorbic acid to in vitro maturation and in vitro culture media supports in vitro embryonic development in buffaloes by improving developmental competence and altering the expression of apoptosis-related genes.

Synthesis of L-Ascorbic Acid Lactone Derivatives

A small focused library which comprised of L-AA lactone derivatives was built with a facile method.This reported method was optimized by modifying the acidity of the solvent.As a result,12 L-AA lactones were synthesized.Among these lactones,lactones 8–12 were new compounds.The cytotoxicity of these synthetic compounds were investigated.

Influence of Polyphosphate Hydrolysis on the Degradation of Volatile Fatty Acids (VFAs) in Anaerobic Digestion

The degradation rate of Volatile Fatty Acids (VFAs) produced predominantly in the acidogenesis stage is a key process parameter to be optimised to ensure a successful Anaerobic digestion (AD). Thermodynamically, the oxidation of the VFAs are energetically unfavourable, and as such external energy source apart from the energy derived from the hydrolysis of Adenosine Triphosphate (ATP) is needed for the initial activation of the VFAs, initial growth of the methanogens in AD process and improved degradation rate of the VFAs. Thus, this research investigated the influence of polyphosphate hydrolysis on the degradation rate of the VFAs at high concentration. Sodium-propionate, Sodium-butyrate and Sodium-acetate salts were added at the start of experiments in order to increase the concentration of the VFAs. The polyphosphate salts used were;Na-hexametaphosphate, Na-tripolyphosphate and potassium pyrophosphate. The control experiment was polyphosphate free and three process parameters (degradation rate, cumulative biogas production and specific methane content) of anaerobic digestion were investigated. The experiments were carried out at a mesophilic temperature of 37.5°C for 41 days. The results of the investigation showed that the treated reactors with the polyphosphate salt solution in low concentration performed better than the reactors with high concentration of the polyphosphate salts solution. All the treated reactors with poly-P salts performed better than reactor Nr-9 (control experiment), but reactor Nr-1 was outstanding with an improved degradation rate of 47%, cumulative biogas production of 21% and specific methane content of 23%.

Conductive Polyacrylonitrile Fiber Prepared by Copper Plating with L-Ascorbic Acid as Reducing Agent

Conductive polyacrylonitrile fibers were prepared by electroless copper plating under weak alkaline conditions,with L-ascorbic acid as reducing agent.The influences of CuSO_(4)·5H_(2)O,L-ascorbic acid,2,2′-bipyridine and K_(4)Fe(CN)_(6) concentration on the conductivity and mass gain percentage of the fibers were studied.The morphological structure of the fibers was characterized by scanning electron microscopy(SEM),and the mechanical properties of the fibers were analyzed through the mechanical property test.The results showed that the optimal reaction conditions were as follows:26 g/L CuSO_(4)·5H_(2)O,26 g/L L-ascorbic acid,12 mg/L 2,2′-bipyridine,7 mg/L K 4Fe(CN)6,and 38℃.The volume resistivity of the conductive PAN fibers prepared by the process was only 3.84×10^(-3)Ω·cm.

Microencapsulation of L-Ascorbic Acid by Spray Drying Using Sodium Alginate as Wall Material

L-ascorbic acid is a water soluble vitamin (vitamin C) widely used as an additive in foods and cosmetics. It has high instability against certain environmental factors;the main cause of its deterioration is oxidation. Microencapsulation is an effective protection technique of L-ascorbic acid from its degradation reactions. This work is focused on the encapsulation of L-ascorbic acid by spray drying technique using sodium alginate as wall material. The microcapsules morphology was observed by scanning electron microscopy (SEM) and the encapsulation efficiency was determined by spectrophotometric analysis. Results showed that encapsulation efficiency was of 93.48% and after 30 days was of 92.55%;differences were not significant, so that the stability of L-ascorbic acid was not affected. Encapsulation yields obtained were low, at around 30%, but the microcapsules morphology obtained is spherical.

高效聚磷酸镁肥料的研制及应用

研究高效聚磷酸镁制备,对合成反应所需的基本要求进行了探讨,筛选出符合要求的采用聚磷技术并在农业生产中应用。研究方法采用磷酸溶液放入装有电动搅拌器的聚合反应釜中,聚合5~6h,反应结束产物降至常温,控制物料的pH值为1.5~3.0;然后加入碱性含镁化合物粉末进行混合,在常温常压下进行搅拌混合反应,混合后物料的化学计量摩尔比为n(MgO):n(P_(2)O_(5))=0.7~1.0:1.0,混合后物料的pH值控制在6.0~7.0之间;加入丁二酸双二乙氨基乙醇酯柠檬酸盐混匀,即为所需的高效聚磷酸镁肥料。农田蔬菜的应用结果指出:高效聚磷酸镁的有效性提高一倍以上,肥料质量稳定、控释性能好。

萃余酸氨化制备农用聚磷酸铵的工艺研究

以湿法磷酸溶剂萃取净化过程中副产物萃余酸、合成氨、尿素为原料,通过预中和反应再聚合制备农用聚磷酸铵,考察萃余酸MER值、原料配比、聚合过程升温速率、反应温度对合成农用聚磷酸铵的影响。试验得出:MER值越高越不利于农用聚磷酸铵的合成。反应温度和中和度的提高对产品聚合率指标是有利的。农用聚磷酸铵总养分随着升温速率的升高而降低,但预中和过程的中和度对其影响较小,在一定范围内,n(磷酸)∶n(尿素)为1∶1.2,反应温度197℃时,总养分最高分别为64%和62%。

自动电位滴定法测定115%以下多聚磷酸中的磷酸含量

将115%以下的聚磷酸加热水解成正磷酸,用已知浓度的氢氧化钠标准滴定溶液在全自动电位滴定仪上进行滴定,用自动电位滴定仪记录滴定曲线,根据曲线上的2个拐点处所消耗的氢氧化钠标准滴定溶液的体积,计算出聚磷酸中磷酸的含量。该方法与重量法相比,具有分析过程简单、快速、准确度高、成本低的优点。

Effect of using ascorbic acid and cysteamine supplementation onin-vitrodevelopment of buffalo embryos

Objective:To improvein vitro embryo production in buffalo by supplementation of L-ascorbic acid during maturation and development (experiment 1) and combination with another antioxidant as cysteamine (experiment 2).Methods:Two experiments were performed, the first one aimed to evaluate the different concentrations (0, 25, 50, 100 μM) of L-ascorbic acid on embryo developmental rate of buffalo oocytes. The L-ascorbic acid was added to the maturation and culture media. In the second experiment, oocytes were cultured in media with two type of antioxidant (ascorbic acid + cysteamine) or ascorbic acid only.Results:There was a significant increase in cleavage rate at 25, 50 μM than 100 μM and control group. But, the blastocyst rate was higher at 50 μM ascorbic acid than other concentrations (0, 25, 100 μM). Supplementation of ascorbic acid and cysteamine to maturation and cultured media improved embryo development than ascorbic acid alone.Conclusions: Using of 50 μM L-ascorbic acid duringin vitro maturation and development improve the developmental competence of buffalo oocytes, this effect was increase with the presence of cysteamine.

Preparation and Properties of Bio-Based Flame Retardant L-APP/Poly(L-lactic acid)Composites

Poly(L-lactic acid)(PLLA)is a thermoplastic material with complete degradability,high biocompatibility and excellent mechanical properties.It can replace petroleum-based polymers are currently being used in the fields of packaging,agriculture,textiles,medical and so on.However,PLLA’s extremely flammability greatly limits its wider application.An bio-based flame retardant L-APP/PLLA composites was prepared by melt blending of the L-APP and PLLA.The morphology,impact properties,thermal properties and flame retardant properties of composites were investigated by field emission scanning electron microscope(SEM),impact tester,differential scanning calorimeter(DSC),thermogravimetric analyzer(TGA),limiting oxygen indexer(LOI)and horizontalvertical burning tester.The results showed that the degree of crystallization(X_(c))and LOI of L-APP/PLLA composites increased as increasing of L-APP content.What’s more,the impact strength first increased and then decreased,the glass transition temperature(T_(g))and melting temperature(T_(m))do not changed significantly.The impact strength of composites was 9.1 kJ/m^(2) at a 5 wt%loading for L-APP,which was the highest level.When the content of L-APP was 20%,the LOI was 30.8%,the Xc was 42.3%and the UL-94 level was V-0.This research can promote the value-added utilization of lignin and the application of PLLA in the fields of flame retardant materials.

Molecular cloning and functional characterization of a soybean GmG MP1 gene reveals its involvement in ascorbic acid biosynthesis and multiple abiotic stress tolerance in transgenic plants

L-Ascorbic acid （AsA） plays an important role in plants and animals. In plants, GDP-D-mannose pyrophosphorylase （GMP） is essential in the AsA biosynthetic pathway. However, little is known about the genes encoding GMP in soybean and here we report genetic and functional analysis of the GmGMP1 （Glycine max GDP-D-mannose pyrophosphorylase 1） gene in this species. GmGMP1 encoded a GDP-mannose pyrophosphorylase and exhibited higher transcript levels in the leaf than in the root, stem, flower, and seed. Transcript of this gene was ubiquitous in the vegetative and reproductive organs, and was induced by abiotic stress and light. Increasing expression of GmGMP1 in Arabidopsis and soybean through an overexpressing approach caused pronounced enhancement of AsA content, and was implicated in lowering the superoxide anion radical content and lipid peroxidation levels in Arabidopsis, and conferring tolerance to osmotic and high salt stresses during seed germination. The present study represents the first systematic determination of soybean genes encoding GDP-mannose pyrophosphorylase and provides useful evidence for the functional involvement of GmGMP1 in control of AsA content and conferring tolerance to osmotic and salt stress.

磷化瓜尔胶与APP协同阻燃PLA的性能研究

采用9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)和1,2,3,6-四氢邻苯二甲酸酐(THPA)对瓜尔胶(GG)进行改性得到磷化瓜尔胶(DTGG),并通过核磁共振和傅里叶变换红外光谱对其结构进行表征。以DTGG为碳源,聚磷酸铵(APP)为酸源和气源对聚乳酸(PLA)进行阻燃改性。通过垂直燃烧(UL 94)、极限氧指数(LOI)和锥形量热仪(CONE)对PLA共混物的阻燃性能进行测试。采用热失重分析(TG)和场发射扫描电子显微镜(FESEM)对其热性能和形貌进行表征。结果表明,当DTGG/APP的质量比为9/11时,LOI值为33.4%,达到UL 94 V-0等级。同时,样品的总热释放(THR)值最低,与纯PLA相比降低了33.8%。从FESEM观察到阻燃剂在PLA基质中分布均匀。DTGG和APP的协同作用有效地增强了PLA共混物的阻燃性能。最后讨论了DTGG和APP对PLA共混物的协同阻燃作用机制。

壳聚糖/植酸钠包覆聚磷酸铵复合物对聚乳酸复合材料阻燃性能的影响

通过包覆技术用生物基材料壳聚糖(CS)和植酸钠(PA-Na)依次改性聚磷酸铵(APP),获得包覆APP(MCAPP),通过红外光谱仪(FTIR)、热重分析仪(TG)和冷场发射扫描电子显微镜(SEM)等对其进行表征和分析;通过熔融共挤出,将其应用于聚乳酸(PLA)复合材料中,以改善PLA阻燃性能。结果表明,相比于纯PLA,7.5%(质量分数,下同)MCAPP(CS与APP质量比为1/2)可有效改善PLA的阻燃性能和成炭能力,热释放速率峰值(pHRR)由654 kW/m2降至469 kW/m^(2),残炭率由0.37%提升至6.85%。

金属杂质对高聚聚磷酸铵产品性能的影响

采用以磷酸氢二铵(DAP)为原料的高温熔融聚合工艺制备了高聚合度Ⅱ型聚磷酸铵(Ⅱ-APP)。利用XRD、FT-IR、SEM等表征手段对其结构形貌进行表征,以产品水溶性为质量指标,考察了氧化铁、氧化镁、磷酸氢钙3种杂质以及杂质质量分数对高聚Ⅱ-APP产品水溶性和形貌的影响。结果表明,在实验设定的添加量范围内,杂质不影响高聚Ⅱ-APP的晶型结构,但会使1100~850 cm-1范围内的红外吸收峰发生偏移,降低产品聚合度,增大产品水溶性。当原料中氧化铁、氧化镁以及磷酸氢钙质量分数分别低于DAP质量分数的0.364%、0.122%、0.163%时,聚合所得高聚Ⅱ-APP产品的溶解度能够满足国标要求。原料中的杂质会对Ⅱ-APP产品的形貌产生影响,过量杂质会造成聚合物颗粒表面粗糙,增加产品的团聚。但是当镁离子质量分数低于DAP质量分数的0.182%时,Ⅱ-APP产品的粒径及形貌均优于未添加杂质的产品,表明适量的金属镁离子可以起到修饰高聚Ⅱ-APP产品形貌的作用。

三聚氰胺聚磷酸盐协效二乙基次膦酸铝阻燃PLA

为研究三聚氰胺聚磷酸盐(MPP)协同二乙基次膦酸铝(ADP)对聚乳酸(PLA)的阻燃效果及阻燃机理,采用熔融共混工艺制备了不同ADP/MPP配比的PLA/ADP/MPP复合材料,并通过热重分析、垂直燃烧、极限氧指数(LOI)、锥形量热(CCT)和扫描电子显微镜(SEM)等对复合材料的阻燃性能进行分析。结果表明,MPP作为协效剂,与ADP协同阻燃效果明显,当ADP和MPP的质量分数分别为13.3%和6.7%时,可使PLA的LOI提高至36.2%,垂直燃烧等级达到V-0级,同时残炭率由纯PLA的0.9%提升至6.35%,MPP协同ADP对催化PLA成炭具有较为明显的作用;CCT测试结果表明,当ADP和MPP的质量分数分别为13.3%和6.7%时,MPP协同ADP有效提高了PLA材料的阻燃性能,阻燃指数达到了1.18,平均热释放速率和热释放速率峰值分别降低至105 kW/m^(2)和331.6 kW/m^(2),与纯PLA相比,降幅分别为55.3%和27.6%,且烟生成速率和总烟释放显著下降;SEM表征结果表明,当ADP和MPP的质量分数分别为13.3%和6.7%时,材料的炭层结构连续致密且强度大,能有效隔绝基体与外界的气体接触和热交换,ADP/MPP阻燃体系的凝聚相和气相相互补充作用达到最佳效果,阻燃能力最好。