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%.

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.

两种调理剂对水稻土pH值和重金属吸收的影响

探明两种调理剂对近中性水稻土pH值、重金属有效性和水稻吸收的影响,及其与土壤性质的关系,为调理剂的科学开发及合理施用提供科学依据。选取水淬高炉渣源调理剂(T1)及其腐殖质改性调理剂(T2),分别设置2个施用量梯度(T1L、T1H和T2L、T2H),通过盆栽试验分析了两种调理剂及不同用量对土壤pH值、有效硅、镉、锌、铜含量,以及水稻籽粒和秸秆镉、锌、铜含量的影响。与对照(CK)相比,2个施用T1调理剂处理土壤pH值分别升高0.64和1.02,2个施用T2调理剂处理pH值分别升高0.27和0.56(P<0.05),土壤pH值随调理剂施用量的增加而增加。T1L和T1H处理土壤有效硅含量与CK相比分别提高5和22倍(P<0.05),且显著高于施用T2调理剂处理。与CK相比,T1H处理土壤有效镉、锌、铜含量分别降低37.21%、45.57%和95.30%(P<0.05);T2L和T2H处理土壤有效锌含量分别降低31.55%和30.67%,有效铜含量分别降低6.53%和19.32%(P<0.05)。与CK相比,T1L和T1H水稻籽粒锌含量分别降低23.44%和18.12%(P<0.05);施用T2调理剂后,籽粒和秸秆锌、铜含量无显著变化。土壤pH值、有效硅含量与土壤有效镉、锌、铜含量呈显著或极显著负相关,土壤有效硅含量与籽粒、秸秆镉含量呈显著负相关。研究表明,在近中性水稻土上施用富含硅的强碱性调理剂,既有利于提高土壤p H值和有效硅含量,又可有效降低土壤重金属有效性及其水稻吸收量。

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.

NaCl胁迫下pH值和氮素形态对狗牙根生长及钠钾离子调控的影响

以狗牙根〔Cynodon dactylon(Linn.)Pers.〕品种‘阳江’(‘Yangjiang’)为实验材料、2-(N-吗啡啉)乙磺酸(MES)为pH缓冲剂,采用水培法研究NaCl胁迫下pH值和氮素形态(铵态氮和硝态氮)对狗牙根生长和钠钾离子调控的影响。结果表明:处理1周后,若不添加MES,铵态氮处理组培养液的pH值下降到pH 4.0左右,而硝态氮处理组培养液的pH值则上升到pH 9.0左右;添加20 mmol·L^(-1)MES的铵态氮处理组培养液的pH值也下降到pH 4.0左右,而硝态氮处理组培养液的pH值则接近pH 7.0。与0 mmol·L^(-1)NaCl处理组相比,300 mmol·L^(-1)NaCl处理组狗牙根的枝条长度和枝条干质量显著(P<0.05)下降,而根长度、根干质量、根和叶中Na^(+)含量和Na^(+)/K^(+)比、钠钾选择性转运系数、叶Na^(+)和K^(+)的分泌量及分泌物Na^(+)/K^(+)比总体上显著升高。300 mmol·L^(-1)NaCl胁迫下,硝态氮处理组狗牙根的枝条长度、根长度、根干质量、根冠比、根中Na^(+)含量总体上显著高于铵态氮处理组,而叶中Na^(+)和K^(+)含量及Na^(+)/K^(+)比、叶Na^(+)和K^(+)的分泌量明显低于铵态氮处理组。300 mmol·L^(-1)NaCl胁迫下,20 mmol·L^(-1)MES处理组狗牙根的多数生长指标显著高于0 mmol·L^(-1)MES处理组,而根和叶中Na^(+)和K^(+)含量及Na^(+)/K^(+)比、钠钾选择性转运系数在0和20 mmol·L^(-1)MES处理组间的差异不显著。三因素方差分析结果表明:3个因子的单一和交互作用对多数生长指标、叶中Na^(+)含量和泌盐量相关指标的影响具有统计学意义。研究结果显示:硝态氮能缓解NaCl胁迫对狗牙根的伤害,而用MES缓冲根际酸碱环境对NaCl胁迫下狗牙根生长有一定的促进作用,因此,施用硝态氮或添加MES均有利于提高狗牙根的抗盐性。

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.

转基因抗虫耐除草剂大豆JD321对根际土壤含水量和pH值的影响

为了评价转基因抗虫耐除草剂大豆JD321对土壤生态系统的影响,该实验研究了其对土壤主要理化性质的影响。在大豆苗期、花期、鼓粒期和成熟期,分析了转基因大豆JD321对根际土壤含水量和pH值的影响。与其对应的非转基因大豆相比,转基因大豆JD321的根际土壤含水量和pH值没有明显变化,除草剂处理转基因大豆也没有对土壤含水量和pH值产生明显影响,但土壤含水量和pH值在不同生育期间存在明显差异。研究结果为转基因大豆JD321的环境安全性提供了新的支撑。

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.

湖南省柑橘园土壤pH值空间变异特征、成因及养分有效性

[目的]研究湖南省柑橘园土壤pH值的空间变异特征、影响因素及主要养分的有效性,为减缓柑橘园土壤酸化,提升土壤肥力提供科学依据。[方法]本研究以湖南省38个柑橘重点县的15722个柑橘园土壤为对象,利用地统计学、相关性分析、结构方程模型等方法,探究了湖南省柑橘园土壤pH值的空间变异特征,分析了土壤pH值对地理、气候、土壤性质等因子的响应,并研究了土壤pH值对土壤氮、磷、钾有效性的影响。[结果]湖南省柑橘园土壤pH值范围为3.00~8.50,均值为5.58,变异系数为18.06%,空间变异为中等程度。最适合柑橘生长的弱酸性土壤面积占44.35%,而酸性、强酸性、中性和碱性土壤分别占48.92%、1.69%、4.95%和0.08%。通过Pearson相关性分析发现,土壤pH值与降水量呈显著正相关(P<0.05),与速效钾含量呈极显著正相关(P<0.01),而与气温、碱解氮和有效磷含量呈极显著负相关(P<0.01)。结构方程模型模拟结果表明,土壤类型与成土母质是解释土壤pH值空间变异的主导因子。除少量强碱性土壤中碱解氮和有效磷含量处于较低水平外,柑橘园土壤各酸度等级土壤中的碱解氮、有效磷和速效钾含量皆处于适宜水平。[结论]由于特有的土壤类型和成土母质,湖南省柑橘园超过一半(50.61%)的土壤处于过酸状态(酸性和强酸性)。湖南省柑橘园土壤速效氮、磷、钾养分含量基本处于适宜水平,因此,应重视改善土壤酸性。

Oxidative coupling of methane over LaAlO3 perovskite catalysts prepared by a co-precipitation method: Effect of co-precipitation pH value

Oxidative coupling of methane(OCM) was conducted over LaAlO3X catalysts that were prepared by a coprecipitation method using different co-precipitation pH values(X = 6–10). The aim is to investigate the effect of p H values on the catalytic activity of La AlO3 catalysts in this reaction. The results showed that the co-precipitation pH value affected greatly on the formation of chemical species of precipitate precursors in the co-precipitation step, leading to different phases of the finally obtained LaAlO3 catalysts.When the co-precipitation pH value increased up to 8, the lanthanum-related phases such as La2 O3 and La(OH)3 were gradually formed as by-products, preventing the formation of LaAlO3 perovskite crystalline structure and facilitating the formation of oxygen vacancies on catalyst surface. However, at pH value of9 or higher, the lanthanum content in the precipitate precursor was increased greatly. Not LaAlO3 perovskite but lanthanum-related phases were developed as main phases, reducing their catalytic activities in this reaction. Among LaAlO3 catalysts, the one prepared at pH = 8 showed the highest C2 yield due to its well-developed oxygen vacancies and electrophilic lattice oxygen. Therefore, the co-precipitation pH value strongly affected the LaAlO3 catalyst activity in OCM reaction. A precious pH control should be required to prepare various perovskite catalysts for the OCM.

24h pH-阻抗监测对胃食管反流病患者治疗反应性的预测价值

目的探讨24 h pH-阻抗监测对胃食管反流病(gastroesophageal reflux disease,GERD)患者治疗反应性的预测价值。方法选取2020年12月—2022年11月成都市第三人民医院接受治疗的286例具有典型反流症状的GERD患者作为研究对象,所有患者均接受质子泵抑制剂(proton pump inhibitors,PPI)治疗,2个月后根据治疗效果,将患者分为有效组和无效组。对比2组患者的日常生活习惯、高分辨率测压结果、24 h pH-阻抗监测结果、症状及量表评分。采用多因素logistic回归分析筛选治疗反应影响因素,构建预测模型,绘制ROC曲线分析其预测价值。结果治疗2个月后,有效组纳入184例,无效组纳入102例。有效组治疗前食管下括约肌(low esophageal sphincter,LES)长度以及LES静息压均低于无效组(P<0.10),远端潜伏期(distal latency,DL)及远端收缩积分(distal contractile integral,DCI)均高于无效组(P<0.10),有效组患者治疗前的酸暴露时间(acid exposure time,AET)≥6%、总反流发作次数、DeMeester评分均低于无效组(P<0.10);有效组反流后吞咽诱发的蠕动波(post-reflux swallow-induced peristaltic wave,PSPW)指数≥61%比例、平均夜间基线阻抗(mean nocturnal baseline impedance,MNBI)值≥2292Ω比例高于无效组(P<0.10)。多因素logistic回归分析显示,LES静息压(OR=0.738)、DL(OR=3.643)、DCI(OR=1.124)及24 h pH-阻抗监测综合预测(OR=1.940)水平均可影响GERD治疗反应性(P<0.10)。ROC曲线分析显示,24 h pH-阻抗监测的综合预测水平(AUC=0.969,特异度=90.2%,敏感度=91.3%)高于其他影响因素。结论24 h pH-阻抗监测的相关参数可高度预测典型的GERD患者对采用PPI后的治疗反应。

Microstructure of nano precursors of La-Mg hydrogen storage alloy synthesized by sol-gel technology at different pH values

Sol-gel technology was employed to synthesize nanosized precursors of La-Mg hydrogen storage alloy at different pH values (0.5, 1.5, 8.0 and 9.0) of reaction solution. The effect of pH value on microstructure of the nano precursors of La-Mg hydrogen storage alloy was studied by infrared radiation (IR), thermo-gravimetric and differential thermal analysis (TG/DTA), X-ray diffraction analyzer (XRD) and transmission electron microscopy (TEM). IR results indicate that the chelating agent, citric acid, is not fully ionized, and carboxyl groups are not entirely used to complex metal ions in acidic solutions. The efficiency of complexing metal ions is enhanced in basic solutions. TG/DTA results show that the combustion may take place with low rate of the flame propagation that causes the longer combustion time when pH<1.5. On the contrary, the dry gel synthesized in basic solution combusts at low ignition temperature and combustion reaction is violent; it is easy to form fine particles. XRD and TEM results reveal that the precursor powders are mainly two-phase mixture of La 2 O 3 and MgO. The morphology of the particles is almost flake with the size of ~30 nm when pH is 8.0.

Correspondence between Susceptibility to SCC of 7050 Aluminum Alloy and Passive Film-induced Stress at Various pH Values

The passive film-induced stress and the susceptibility to SCC of 7050 aluminum alloy in 3.5%sodium chloride solution at various pH values were investigated by slow strain rate testing（SSRT） and flowing stress differential method.The results showed that the passive film-induced stress and the susceptibility to SCC decreased with increasing pH values when pH≤7,while they increased with increasing pH values when pH7.However,the corrosion type was interpreted as exfoliation corrosion when pH=l and 14,and there was no film formed on the surface of the specimens.The whole variation plots of film-induced stress and the SCC susceptibility with pH values were both presented as a valley shape.The symbol and amount of the film-induced stress were related to the compositions of the passive film,which were analyzed using X-ray photoelectron spectroscopy（XPS）.

不同pH值下蛋白氧化对牦牛肉肌原纤维蛋白凝胶特性的影响

该文以不同pH值的Fenton氧化体系孵育24 h的牦牛肉肌原纤维蛋白(MP)形成的凝胶为研究对象,通过对其白度、持水性、质构等特性的研究,探究不同pH值下蛋白氧化对凝胶特性的影响,分析该条件下化学作用力、流变、微观结构的差异性变化。结果表明:不同pH值下随H2O_(2)浓度的增加,蛋白凝胶白度、持水、质构显著降低(P<0.05)。疏水相互作用力是维持凝胶的主要作用力,其次是二硫键、离子键和氢键,随着H2O_(2)浓度的增加,疏水作用力和二硫键显著上升,离子键和氢键显著下降(P<0.05)。pH值为5.0时氧化对凝胶特性影响最为明显,MP凝胶持水性最低,为77.20%,质构强度最差,仅有53.40g,储能模量、蛋白分子间作用力最小,微观结构松散、无序。pH值为6.0时氧化对凝胶特性影响最弱,MP凝胶质构强度最大,为61.40g,储能模量、分子间作用力最大,微观结构致密有序。为牦牛肉中蛋白氧化控制提供理论基础。

Effects of temperatures and pH values on rheological properties of cemented paste backfill

In this study,different influence mechanisms associated with temperatures and pH values were investigated through cemented paste backfill(CPB)systems.CPB samples were prepared with temperatures ranging from 10 to 50℃ in 10℃ increments and pH values of 3,7,and 13.Then,the CPB mixture were subjected to rheological tests,thermogravimetric analysis(TG),derivative thermogravimetry analysis(DTG),Fourier-transform infrared spectroscopy(FT-IR),and scanning electron microscopy(SEM).Results demonstrated that the temperatures had significant effects on the rheological properties of CPB,whereas the effects of pH values were relatively unapparent.Higher temperatures(over 20℃)were prone to bring higher shear stress,yield stress,and apparent viscosity with the same pH value condition.However,an overly high temperature(50℃)cannot raise the apparent viscosity.Non-neutral conditions,for pH values of 3 and 13,could strengthen the shear stress and apparent viscosity at the same temperature.Two different yield stress curves could be discovered by uprising pH values,which also led to apparent viscosity of two various curves under the same temperatures(under 50℃).Microscopically,rheological properties of CPB were affected by temperatures and pH values which enhanced or reduced the cement hydration procedures,rates,products and space structures.

Comparison of pH Value, TBA Value, Glycogen and Lactic Acid Content in Muscle of Landrace and Yorkshire under Different Storage Time and Conditions

In order to assess the meat quality under different storage time and conditions, the pH value, TBA value, glycogen and lactic acid content in muscle of Landrace and Yorkshire were measured. The results showed that within 10 h post slaughtering, post slaughtering time had extremely significant influence on pH value and lactic acid content of Landrace, but had no significant influence on glycogen content and TBA value. On the other hand, post slaughtering time had extremely significant influence on pH value of Yorkshire, but had no significant influence on glycogen, lactic acid content and TBA value. The pH values of Yorkshire at 3, 5 and 10 h post slaughtering were 5.21% （ P 〈 0.01 ）, 5.64% （ P 〈 0.05 ） and 5.59% （ P 〈 0.05 ） higher than those of Landrace, respectively ; the lactic acid content in muscle of Landrace at 10 h post slaughtering was 56.04% （P 〈0.05） higher than that of Yorkshire; the TBA value in muscle of Yorkshire at 10 h post slaughtering was 89. 19% （P 〈 0.01 ） higher than that of Landrace; there was no significant difference in glycogen content between Yorkshire and Landrace. When pork stored at 4℃, storage time had no significant influence on pH value and glycogen content in muscle of Landrace, but had significant influence on drip loss, lactic acid content and TBA value ; storage time had no significant influence on pH value, glycogen content and TBA value in muscle of Yorkshire, but extremely significant influence on drip loss and significant influence on lactic acid content. The pH value in muscle of Yorkshire at 24 h post storage at 4℃ was 6.56% （P 〈0.05） higher than that of Landrace; the glycogen contents in muscle of Landrace at 24, 48, 72, 96, 120 and 144 h post storage at 4℃ were 84.90% （P〈0.05）,78.40% （P〈0.01）, 101.87% （P〈0.05）, 83.80% （P〈0.05）, 83.59% （P〈 0.05）and67.25% （P〈0.01）higher than those of York-shire, respectively; the drip loss of Landrace at 72 h post storage and TBA value at 144 h post storage were 55.70% （ P 〈 0.05 ） and 141.33 % （ P 〈 0.01 ） higher than those of Yorkshire, respectively; there was no significant difference in glycogen content between Yorkshire and Landrace. When pork stored at -20℃, storage time had significant influence on TBA value in muscle of Landrace, but had no significant influence on pH value, thawing water loss rate, glycogen and lactic acid content; storage time had no significant impact on pH value, thawing water loss rate, glycogen content and TBA value in muscle of Yorkshire, and had significant influence on lactic acid content. The pH value in muscle of Yorkshire at 24 h post storage at - 20℃ was 5.43 % （ P 〈 0.05 ） higher than that of I.andrace ; the glycogen contents in muscle of Landrace at 24, 48, 72, 96, 120 h post storage at - 20℃ were 85.08% （ P 〈0. 05 ）, 108.66% （ P 〈 0.01 ）, 72.69% （ P 〈 0.05 ）, 90.31% （ P 〈 0.01 ）, 70.38% （ P 〉 0.05 ） higher than those of Yorkshire, respectively ; the thawing water loss rates of Landrace at 24 and 72 h were 160.14% （ P 〈 0.05 ） and 74.32% （ P 〈 0.05 ） higher than those of Yorkshire, respectively ; there was no significant difference in lactic acid content and TBA value at the same time point between Yorkshire and Landrace.

三七土壤钾、pH值及其产量和品质对水肥制度的响应研究

[目的]探究三七土壤钾素、pH值对不同水肥处理的响应以及提高三七产量和品质的最佳水肥制度。[方法]以试验区云南省红河哈尼族彝族自治州泸西县大栗树村种植区三七为研究对象,试验设置4个施肥水平,施肥总量均为480 kg/hm^(2),根据苗期、花期、果期和根增重期的施肥占比不同,分别记为:F1(25%∶25%∶25%∶25%)、F2(25%∶30%∶20%∶25%)、F3(30%∶30%∶15%∶25%)、F4(40%∶20%∶10%∶30%);设置3个灌水水平W1(200m^(3)/hm^(2))、W2(300m^(3)/hm^(2))、W3(400m^(3)/hm^(2)),设置对照试验(CK),其灌水量为92 m^(3)/hm^(2),施肥总量为480 kg/hm^(2),各生育期施肥比例为苗期∶花期∶果期∶根增重期=25%∶25%∶25%∶25%。分析13种水肥制度下土壤钾素和pH值变化规律,以及钾素、pH值、三七产量、品质、水分利用效率和肥料偏生产力的影响,运用优劣解距离法(Technique for Order Preference by Similarity to Ideal Solution, TOPSIS)对各处理进行综合品质评价,探究三七最优水肥制度。[结果](1)相同灌水水平和施肥比例下,土壤pH值随土层增加而降低,随生育期增加变化小;随生育期增加和施肥的不同无明显变化规律;相同灌溉水平下,三七土壤pH值均小于对应CK。三七所有生育期0~60 cm土层13种处理pH值范围为4.80~8.66,结合三七最适土壤pH值,W3F1、W2F4处理和W2F3处理适宜三七生长。(2)相同处理土壤全钾量和速效钾量随土层增加而减小;0~60 cm土层全钾量平均值随生育期的增加而增加,速效钾量平均值先减小后增加,全钾量平均值随灌水水平增加而减小,速效钾量平均值先增加后减小,全钾量平均值随施肥比例不同先减小后增加,速效钾量平均值先增加后减小。不同生育期吸钾规律为:果期>花期>根增重期>苗期,W2F3处理为钾素中最优处理,其全钾量和速效钾量为10.40g/kg和56.69mg/kg。(3)三七产量和肥料偏生产力随灌水水平的增加先增加后减小,水分利用效率随灌水水平的增加而减小,产量、水分利用效率和肥料偏生产力随施肥比例的不同而增加;皂苷R1、Rg1、Re、Rb1和Rd以及总皂苷量在W2处理下较高,综合得分表明三七品质在W2处理下较好,W2F3处理品质最优。其灌水水平为200 m^(3)/hm^(2),苗期、花期、果期和根增重期施肥量为144、144、72 kg/hm^(2)和120 kg/hm^(2)。[结论]本研究结合最适土壤p H值范围,钾素及三七产量品质分析,W2F3处理为最优水肥制度,有利于三七生长和根系有效成分积累,为实现三七绿色可持续发展具有重要理论及指导意义。

Electrochemical Behavior of Steel Bar in Electrolytes:Influence of pH Value and Cations

Steel bar corrosion on electrolytes and the influence of cation were investigated. Three electrolytes of Ca（OH）2, NaOH and KOH with pH levels of 12.5, 11.5, 10.5, 9.5, 8.5 were prepared, meanwhile, the methods of free corrosion potential and electrochemical impedance spectra （EIS） were used to evaluate the influence of cations on the depassivation of the steel bar in electrolytes. The experimental results indicate that the initial corrosion pH value of the steel bar is influenced by the cation in electrolyte and the influence of K＋ in electrolyte is the most remarkable, followed by Na＋ and Ca2＋. The initial corrosion pH values are 10.5 in KOH electrolyte, 9.5 in NaOH electrolyte and lower than 8.5 in Ca（OH）2 electrolyte.

pH值对大豆分离蛋白功能性质的影响及其精准调控研究

大豆分离蛋白(Soybean protein isolate,SPI)对外界环境的变化极其敏感,中和工段中pH值微小的变化就会改变蛋白质的结构和功能性质。通过添加NaOH调控凝乳的pH值,利用红外光谱和内源荧光光谱分析SPI的结构及功能性质,研究发现在中性条件下SPI具有较好的起泡性,碱性条件时SPI具有较好的乳化性,当体系pH值为7时,SPI的起泡性最佳,当体系pH值为8.5时,SPI的乳化性最佳。建立了25 L大豆SPI中和工段pH值精细调控体系,利用Matlab模拟生产过程,通过动态线性与静态非线性拟合,采用模糊自适应控制结合Wiener模型调控中和罐的加碱量,当将中和罐中pH值调控为7时,调节时间为37.4 s,生产的SPI起泡性指数为57.22%,将中和罐中pH值调控为8.5时,调节时间为33.4 s,生产的SPI乳化活性指数为69.35 m^(2)/g,体系无超调量用碱。