基于不同提取物中的花青素智能pH复合膜的研究进展

食品包装是食物给人的第一印象,它可以引起或抑制人们的食欲,在提高食物的外观和质量方面发挥着极其重要的作用。如何更好地保护广大消费者免受变质腐烂的食品带来未知疾病的困扰,进一步提高食品质量已成为重要的研究方向。而花青素是重要的天然水溶性色素,广泛存在于植物中,其属于多酚家族的黄酮类物质,具有良好的pH敏感性。该文综述了近几年研究人员从不同植物中提取出花青素,将其作为指示剂制备智能pH复合膜,通过复合膜颜色的变化以监测肉类、牛奶和果蔬等的新鲜程度方面的最新研究进展,还讨论了花青素的来源、结构和性质,为研究人员探索从不同植物中提取的花青素智能pH指示膜在其他领域中的应用潜力提供一定的思路。

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高压射流协同pH循环处理对大米-豌豆复合蛋白功能性及结构的影响

为探究复合植物蛋白经高压射流磨与p H循环共同处理后的增溶作用,明晰其增溶机制,采用大米蛋白与豌豆蛋白作为原料,配制蛋白比例1:1,总蛋白浓度4%的混合蛋白溶液,并将混合液p H调整至12,在高压射流磨不同压力下进行处理,再将溶液pH调回中性后得到复合蛋白。采用氮溶解指数、粒径、荧光光谱、圆二色谱、分子量等手段表征本工艺过程中复合蛋白理化性质和结构的变化。结果表明,经高压射流磨协同pH循环处理4%的复合蛋白,复合蛋白氮溶解指数随着压力增大而提升,处理压力为120MPa时,氮溶解指数为92.67%±0.77%。扫描电镜与粒径结果显示,射流磨处理后的复合蛋白尺寸降低,比表面积增大。内源荧光光谱、表面疏水性、巯基二硫键、圆二色谱结果显示,两种蛋白之间产生了相互作用,形成了新的共架体,且复合蛋白随处理压力增大,表面疏水性由4025.33显著增大至7359.45(P<0.05),疏水区域增加、游离巯基含量由26.46±0.32μmol/g显著上升至最高32.66±0.35μmol/g(P<0.05),二硫键含量由9.86±0.42μmol/g显著下降至5.48±0.27μmol/g(P<0.05),α-螺旋实际含量(25.3%)高于理论值(21.83%),二级结构向更亲水的α-螺旋转变。此外,氨基酸分析显示复合蛋白的氨基酸配比均衡完整。经处理后的复合蛋白在高溶解性的基础上,乳化与起泡性能均明显优于大米蛋白与豌豆蛋白。本研究表明高压射流磨协同pH循环的处理方法能够有效改善复合蛋白的功能特性,为植物蛋白工业化增溶改性提供理论支撑。

Influence of pH value and chelating reagent on performance of Li_3V_2(PO_4)3/C cathode material

The Li3V2（PO4）3/C composite cathode material was synthesized via sol-gel method using three different chelating agents （citric acid, salicylic acid and polyacrylic acid） at pH value of 3 or 7. The crystal structure, morphology, specific surface area and electrochemical performance of the prepared samples were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS） and galvanostatic charge/discharge test. The results show that the effects of pH value on the performance of the prepared materials are greatly related to the chelating agents. With salicylic acid or polyacrylic acid as the chelating reagent, the structure, morphology and electrochemical performance of the samples are greatly influenced by the pH values. However, the structure of the materials with citric acid as the chelating agent does not change as pH value changes, and the materials own uniform particle size distribution and good electrochemical performance. It delivers an initial discharge capacity of 113.58 mA·h/g at 10C, remaining as high as 108.48 mA·h/g after 900 cycles, with a capacity retention of 95.51%.

两歧双歧杆菌F35培养基优化及恒定pH发酵研究

为提高两歧双歧杆菌F35发酵液中活菌浓度,对该菌株发酵培养基进行优化。以发酵液活菌数为主要评价指标,以添加0.5 g/L L-半胱氨酸盐酸盐MRS培养基为基础培养基,对两歧双歧杆菌F35发酵培养基的L-半胱氨酸盐酸盐添加量、氮源的种类及添加量进行优化。在此基础上,于恒定pH发酵条件下优化葡萄糖添加量。结果表明,L-半胱氨酸盐酸盐的最优添加量为1.5 g/L;氮源的最优复配为:酵母蛋白胨10 g/L,酵母提取物FM98510 g/L,在200 L体系恒定pH 5.7发酵时,葡萄糖最优添加量为32 g/L。经优化后,两歧双歧杆菌F35发酵液最高活菌数为(8.01±0.70)×109 CFU/mL,是优化之前的57倍。

Influence of pH Value on Photocatalytic Activity of Bi4Ti3O12 Crystals Obtained by Hydrothermal Method

Bi4Ti3O12 （BIT） crystals were controllably synthesized via a facile hydrothermal process without adding any surfactant or template. The morphologies of BIT with nanosphere, nanoplate, nanobelt, and nanosheet can be selectively obtained by adjusting the pH value of the reactant. The formation mechanisms of these distinctive morphologies were then discussed based on the structural analysis of samples obtained at different pH values. BIT sample prepared at pH=1 showed the highest photocatalytic activity under visible light irradiation. The photocatalytic activities difference for the BIT samples synthesized at different pH values was studied based on their shape, size, and the variation of local structure.

pH值对MICP固化修复镉污染尾矿的影响研究

微生物诱导碳酸钙沉淀(MICP)方法是一种生态友好、可持续的污染土固化与修复技术,而对于MICP在不同土壤p H值环境下处理重金属污染土影响的研究较少。利用巴氏芽孢杆菌ATCC 11859分别在pH值为5,7,9,1条件下进行了MICP修复Cd溶液试验、Cd污染尾矿固化修复试验。结果表明,水溶液修复试验中,在pH为5~11范围内均能有效钝化Cd^(2+),当pH值为9时对Cd^(2+)钝化效果最佳;尾矿固化试验中,酸性淋溶液会加快尾矿中的Cd^(2+)浸出,MICP主要将尾矿中Cd的酸可溶态转化为可还原态和残渣态,且钝化效果与碳酸盐生成率呈正相关关系。通过对生物矿化沉淀的FTIR、XRD、XPS和SEM-EDS分析表征,揭示了MICP钝化重金属和固化尾矿的机理:MICP通过生物吸附和碳酸钙的吸附、离子交换、共沉淀等作用完成对重金属离子的钝化,通过覆膜作用、黏结作用和桥接作用增大土颗粒内摩擦角和土粒间的黏聚力。

pH条件对铝合金化学机械抛光过程中纳米摩擦化学行为的影响

目的探讨pH条件对铝合金化学机械抛光微观过程中纳米摩擦化学行为的影响,表征抛光液在铝合金表面所形成的表面薄膜厚度及力学性能,并分析铝合金化学机械抛光过程中单磨粒接触状态与摩擦学特性。方法使用0.6%(体积分数)过氧化氢(H_(2)O_(2))和0.5%(质量分数)壳寡糖(COS)构成抛光液对铝合金表面进行处理,在铝合金表面反应生成的表面薄膜借助扫描电子显微镜进行细化表征。分析不同pH条件的抛光液对单磨粒/表面薄膜接触状态的影响规律,利用原子力显微镜测量了单磨粒/表面薄膜吸引力与黏附力数值。在纳米摩擦化学行为试验中,结合微观摩擦学理论模型阐明铝合金化学机械抛光过程中的摩擦化学去除机制。结果在抛光液化学反应后,铝合金表面将会形成100μm左右致密的氧化薄膜与40μm左右稀疏的氧化络合薄膜。当抛光液pH值升高至11~12时,探针针尖与铝合金表面薄膜的吸引力和黏附力将会分别降低至24.49、32.01nN。结论原子力显微镜试验和微观摩擦学理论模型的分析表明,铝合金的摩擦化学去除过程不是黏附力引起的磨粒法向接触载荷增大所产生的,而可能是抛光液的化学腐蚀作用所引起的。当化学机械抛光液pH值大于9时,铝合金表面将会形成氧化络合层,成为材料磨损加剧的主要影响因素。在界面摩擦力作用下,沉积在铝合金表面薄膜的铝原子会吸附在探针针尖OH^(*)基团上,从而产生黏合作用,探针针尖在纳米摩擦划动过程中将其除去。最后,铝合金表面薄膜呈现出更低的摩擦因数。

pH依赖-酶触发型黄芩苷结肠靶向微丸制备研究

目的制备pH依赖-酶触发型黄芩苷结肠靶向微丸,并优化工艺处方。方法以目标微丸收率及圆整度为综合评价指标,用正交实验优化丸芯制备工艺;以累积体外释放度为评价指标,采用Box-Behnken响应面法优化包衣工艺。结果正交实验得到的优化工艺处方为:黄芩苷用量为18%,微晶纤维素与乳糖之比为5∶1,滚圆时间为5min;Box-Behnken响应面法确定的最优包衣工艺处方为:丙烯酸树脂Ⅲ∶抗性淀粉RS3(2∶1),增塑剂用量17.1%,包衣增重29.8%,老化时间1.6h。最优工艺处方制备的样品在人工小肠液(pH6.8磷酸盐缓冲液)累积体外释放率约为2.9%,在人工结肠液(pH7.6磷酸盐缓冲液)累积体外释放率约为93.0%;在(含有胰蛋白酶)模拟肠液体累计释放度为2.9%,在(4%盲肠内容物法制备)模拟结肠液32h时累积释放度达70.37%,证明此微丸具有pH依赖及酶触发性。结论正交实验结合Box-Behnken响应面法可用于黄芩苷结肠靶向微丸的制备,且最优处方得到的微丸具有pH依赖及酶触发性。

One-pot synthesis of ordered mesoporous Cu-KIT-6 and its improved catalytic behavior for the epoxidation of styrene:Effects of the pH value of the initial gel

The heterogeneously copper-catalyzed oxidative cleavage of styrene was studied using copper-doped mesoporous KIT-6（CU-KIT-6_x） prepared via pH adjustment（where x is the pH：1.43,2.27,3.78,3.97,4.24 or 6.62）.Variations in the catalyst structure and morphology with pH values were characterized by X-ray power diffraction,nitrogen adsorption-desorption analysis,transmission electron microscopy and X-ray photoelectron spectroscopy.As the pH value applied during the initial synthesis,the resulting Cu-KIT-6_x exhibited different structural,textural and surface characteristics,especially in terms of specific copper species and copper content At a pH value of 3.78,approximately 4.6 wt%copper（Ⅱ） was successfully incorporated into the framework of the initial KIT-6,in the form of-Cu-O-Si- groups.The catalytic performance of each catalyst was evaluated by following the epoxidation of styrene,employing tert-butyl hydroperoxide as the oxidant and CH_3CN as the solvent.A significant styrene conversion of 43.5%with 86.6%selectivity for the desired styrene epoxide was obtained over the Cu-KIT-63.78.A higher Cu content,an ordered cubic laid mesoporous architecture and various specific textural characteristics all combined to endow the Cu-KIT-63.78 with high catalytic activity and good stability.

不同pH条件下镉对水稻幼苗生长的影响

为探究不同pH条件下镉对水稻幼苗生长的影响,以湘岳占为供试品种,采用溶液培养法研究镉胁迫对水稻幼苗生长的影响。结果表明,不同pH清水与镉离子溶液浸种下的水稻幼苗苗高、最长根长与总根数间有差异,pH为9时各值最大。与清水浸种比较,镉离子溶液浸种过的水稻幼苗苗高、最长根长、总根数与百株鲜重均明显降低。当pH为8或9时,无论清水还是镉离子溶液浸种过的水稻幼苗光合色素可达最高值。不同pH可显著影响水稻幼苗丙二醛含量,当pH为9时,清水浸种过的水稻幼苗丙二醛含量最高,而镉离子溶液浸种过的水稻幼苗丙二醛含量最低。该研究揭示了pH与镉对水稻幼苗生长特性的耦合影响,为水稻生产提供了实践参考。

Adsorption Kinetics of NH_4^+ by Purple Soils with Different pH Values

Ammonium adsorption and desorption properties by purple soils with dif- ferent pH were studied. The results showed that the adsorption and desorption amounts of NH4＋ by purple soils increased with the increase of NH4＋ concentration, regardless of soil pH values; the largest adsorption and desorption amounts of NH4＋ by purple soil at pH 6.0 were 10.3 and 7.96 mg/g, respectively; the largest adsorp- tion and desorption amounts of NH4＋ by purple soil at pH 7.2 were 12.8 and 4.62 mg/g, respectively; the largest adsorption and desorption amounts of NH4＋ by purple soil at pH 8.0 were 13.5 and 2.23 mg/g, respectively. The isothermal adsorption ki- netics of NH4＋ by purple soils fits the Freundlich equation best （R〉0.95）. This study shows that the adsorption of NH4＋ by purple soils with different pH values is multi- molecular layer uneven surface adsorption.

电解质溶液pH的相关计算

平衡思想是重要的化学学科思想,为学生认识世界提供了独特的化学视角,不仅如此,平衡思想也是学生化学学科核心素养的重要组成部分。该文针对近年来高考试题中关于缓冲溶液中有关pH的计算,找出相关规律,帮助学生全面、深刻地认识化学平衡问题,有利于平衡思想的形成与巩固。

超声辅助pH值偏移对苦荞蛋白结构和功能特性的影响

探讨pH偏移联合超声处理对苦荞蛋白结构及功能特性影响的结果表明:通过超声辅助及pH偏移处理,苦荞蛋白的游离巯基含量显著增加(P<0.05),这可能是由于蛋白质去折叠导致内部巯基暴露,或蛋白质中二硫键断裂而生成新的巯基所致。在超声时间为20 min,功率为300 W时,苦荞蛋白表现出最高的表面疏水性,表明蛋白质在改性过程中经历了重组,导致疏水相互作用下形成的蛋白聚集体被破坏,蛋白粒径减小,进而暴露更多内部的疏水基团。此外,经超声辅助pH偏移处理显著提升了苦荞蛋白的溶解度,尤其在碱性pH条件下,溶解度从63.85%显著提升至103.48%。该处理也导致了苦荞蛋白粒径的显著下降(P<0.05),以及绝对电位和乳化活性的显著增强(P<0.05)。综上所述,超声辅助pH偏移处理不仅有效改善了苦荞蛋白的结构特性,还显著提升了其功能特性,为苦荞蛋白在食品工业中的应用开辟了新的前景。

Effect of pH values on extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans during chalcopyrite bioleaching

The effect of pH values on the extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans was comparatively investigated in different phases of bacterial growth during chalcopyrite bioleaching. The results indicate that the extracellular protein is always more than the extracellular polysaccharide secreted by attached cells on the chalcopyrite, on the contrary, and is always less than the extracellular polysaccharide secreted by free cells in the solution at bacterial adaptive phase, logarithmic phase and stationary phase whenever pH value is at 1.0, 1.5, 2.0 or 2.5; free cells are mainly through the secretion of extracellular polysaccharide rather than the extracellular protein to fight against disadvantageous solution environment, such as high concentration of metal ions and unsuitable pH solution; both amounts of polysaccharide and protein secreted by attached cells are mainly positively related to the solution acidity rather than the total concentration of soluble metal ions. The experimental results imply that bacteria are mainly through secreting more extracellular polysaccharide to fight against disadvantageous environment and the extracellular protein perhaps plays an important role in oxidation？reduction reactions in the bioleaching system.

Corrosion behaviour of die-cast AZ91D magnesium alloys in sodium sulphate solutions with different pH values

The corrosion behaviours of die-cast AZ91D magnesium alloys were investigated in 0.1 mol/L sodium sulphate （Na 2 SO 4 ） solutions with different pH values. The corrosion rates, morphologies, and compositions of the corrosion products were studied by means of scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FTIR）, and X-ray diffractometry （XRD）. The results indicate that the order of corrosion rates in Na 2 SO 4 solutions with various pH values is pH 2pH 4pH 7pH 9pH 12. The corrosion rates in acidic solutions are higher than those in alkaline solutions, and the corrosion products are mainly magnesium hydroxide （Mg（OH） 2 ） and hydrated sulphate pickeringite （MgAl 2 （SO 4 ） 4 ·22H 2 O）. The results also indicate that the solution pH can influence the corrosion rate and morphology of corrosion products. Chloride ions and sulphate ions have different pitting initiation time.

The Distribution Characteristics of Soil pH Values of Tobacco-growing Areas in Dali City and Its Correlation with Soil Nutrients

[Objective] The aim was to study the distribution characteristics of soil pH values and its correlation with soil nutrients in tobacco-growing areas. [Method] Soil nutrients of 43 samples from tobacco-growing areas in Dali City were analyzed.[Results] The results showed that average pH value of tobacco-planting soil in Dali City was 6.52, soil samples which suited for flue-cured tobacco cultivation accounted for 72.09% of total soil samples. In four soil types of tobacco-growing areas, the pH values in a descending order were as follows： alluvial soil〉 paddy soil 〉purple soil〉 red soil. At the altitude range of 1 780-2 200 m, soil pH values showed a gradual decreasing trend. The average contents of soil organic matters were relatively abundant and generally suited for high-quality tobacco cultivation; the average contents of soil alkali-hydrolyzable nitrogen, available phosphorus, exchangeable calcium and exchangeable magnesium were generally at medium and abundant level, however,their rations under the medium level in some tobacco-growing areas were 6.98%,11.63%, 2.33% and 4.65%, respectively; moreover, soil with lower available potassium contents occupied a large proportion, namely 58.14%. [Conclusion] Soil pH values had significant correlation with exchangeable magnesium and exchangeable magnesium, however, they had no significant correlation with other soil nutrients.

17-4PH板增材再制造温度场及残余应力研究

为了探究预制槽长度(L_(c))、再制造路径对熔池热循环曲线、冷却速率以及残余应力峰值的影响规律,基于热-弹塑性理论和有限元法,利用Simufact welding软件建立了17-4PH板再制造的热力耦合有限元模型,分析了再制造件的温度场和残余应力的分布规律。结果表明,相同路径与交叉路径再制造温度循环曲线变化趋势相同;除预制槽长度为12W外,随着焊缝数量的增大,冷却速率逐渐增大。交叉路径的残余应力峰值略小于相同路径的残余应力峰值,垂直焊缝方向上的残余应力值小于沿焊缝方向的值;沿焊缝方向上的残余拉应力最大值在最后一道焊缝的熄弧端及邻近的母材区,垂直焊缝方向上残余应力的峰值发生在在第一道焊缝中间位置及其邻近母材区域上。为避免高的残余拉应力,预制槽的长度应不小于16W,预制槽长度为4W时的残余应力值均大于其他预制槽长度的值,因此,再制造时预制槽的长度不应过短。研究结果能够为17-4PH零件再制造的预制槽设计、再制造路径的优选、残余应力调控提供参考。

8万大奖和8万创业资源支持 第四届“濮院杯”PH Value中国针织设计师大赛正式启动

7月21日，第二届全国针织服装设计工艺培训班结业典礼暨第四届“濮院杯”PH Value中国针织设计师大赛启动仪式在濮院举行。中国纺织工业联合会副会长、中国针织工业协会会长杨纪朝，中国国际贸易促进委员会纺织行业分会副会长林云峰，中国服装设计师协会秘书长黄萍以及桐乡市濮院镇党委书记、濮院针织产业园区管理委员会主任苏伟明，濮院镇党委委员沈利敏，濮院针织产业园区管理委员会副主任钱伟国等有关领导、专家学者以及相关院校、企业代表出席了本次活动，会议由中国针织工业协会副秘书长徐国强主持。

PH Value,时尚听你的

当针织服装是服装中的＂低值易耗品＂这一概念,从人们的意识中剥离出去的时候,针织正在向时尚产品大跨步转型.而＂PH Value＂,也成为为针织品搭建的时尚舞台.