基于逆Leidenfrost效应的多孔地聚合物微球孔结构及pH缓冲性能

以水玻璃、矿渣粉为材料,基于逆Leidenfrost效应制备了多孔地聚合物微球,研究了其孔结构及pH缓冲性能.结果表明:改变水玻璃掺量和水固比可以调控多孔地聚合物微球的孔结构和pH缓冲性能;当水固比为1.0、水玻璃掺量由4%增大至8%时,微球的孔隙率、中位孔径和孔比表面积均减小,pH值波动范围为1.50~1.90;当水玻璃掺量为4%、水固比由1.0增大至1.2时,微球的孔隙率、中位孔径和孔比表面积均增大,pH值波动范围超过2.00;与双氧水直接发气法制备的多孔地聚合物相比,基于逆Leidenfrost效应制备的多孔地聚合物具有更好的pH缓冲性能和更高的OH-累积浸出量.

在线清洗式泵出口pH测量装置的设计与应用

在有色湿法冶炼中,pH值经常被作为重要的工艺反应指标,但是在实际生产中,工艺介质浆料往往由于性状粘稠,易结垢,会对pH电极进行包裹,导致pH电极寿命缩短、测量参数不稳定,甚至失真。为了解决以上的问题,本文结合实际应用,介绍一种可在线清洗式泵出口pH测量装置,通过对pH电极的在线清洗,解决了pH测量偏差的问题。在现场应用中发挥了良好效果。

碳化条件下混凝土中钢筋腐蚀pH阈值研究

目的 确定碳化条件下几种典型缓冲溶液及模拟混凝土孔隙液中钢筋的腐蚀pH阈值范围。方法 采用电化学阻抗谱法,对不同pH、不同配制方法的缓冲溶液及模拟混凝土孔隙液中的钢筋试片进行电化学测量,选用不同的等效电路进行拟合,对测量中钢筋试片发生的电化学过程进行简要阐述。结合阻抗谱测量结果、等效电路拟合结果及工作电极典型宏观形貌,判断钢筋试片腐蚀状态,给出不同溶液对应的钢筋腐蚀pH阈值范围。结果离子环境不同,各缓冲溶液及模拟混凝土孔隙液中钢筋腐蚀pH阈值均存在一定差异,位于9~10.5不等。结论 混凝土碳化引入的HCO_(3)^(–)和CO_(3)^(2–)对钢筋腐蚀有促进作用。混凝土孔隙液pH越低,钢筋腐蚀越容易发生。因此,仅根据pH判断混凝土中钢筋腐蚀状态的方法并不可靠。

缓冲液pH值对单晶冰糖色值检测的影响

采用《冰糖试验方法》(QB/T 5010—2016)中的分光光度计法测定单晶冰糖的色值,并研究缓冲溶液p H值对单晶冰糖色值检测结果的影响。结果表明,缓冲溶液pH值为7.0时,单晶冰糖色值的检测结果更为准确。

复杂组成缓冲溶液pH值的讨论

缓冲溶液是酸碱解离平衡的重点内容,为解决复杂组成缓冲溶液pH值计算的问题,以磷酸盐体系为例,讨论了三种组成的缓冲溶液pH值的计算方法,考察了近似计算和精确计算的区别,旨在培养学生的逻辑思维和推导能力,加深学生对基本概念和理论的理解,也是对现行教材有益的补充.

Buffer standards for the physiological pH of the zwitterionic buffer 3-[<i>N</i>-tris(hydroxymethyl)methylamino]-2-hydroxypropanesulfonic Acid (TAPSO) From (278.15 to 328.15) K

The second dissociation constant, pK2, and related thermodynamic quantities for TAPSO have been previously determined and reported from the temperatures (278.15 to 328.15) K. In the current study there are five buffer solutions without NaCl and five buffer solutions with NaCl present which yield an ionic strength (I = 0.16 mol·kg-1) similar to that of blood plasma. These buffer solutions have been evaluated in the temperature range of (278.15 to 328.15) K using the extended Debye-Hückel equation, due to the limitations of the Bates-Guggenheim convention such that it is only valid when I -1. The liquid junction potential (Ej) values between the TAPSO solution and the saturated KCl calomel electrode solution have been estimated at (298.15 and 310.15) K using a flowing junction cell measurement. The previously mentioned Ej values have been used in determining the operational pH values at (298.15 and 310.15) K. These TAPSO buffer solutions are recommended as reference solutions for pH measurements in saline media with an ionic strength of I = 0.16 mol·kg-1.

Acidification of the Skin and Maintenance of the Physiological Skin pH Value by Buffered Skin Care Products Formulated around pH 4

Each biological system possesses a widely unrecognized buffer system to maintain acid-base balance to a specific pH. The skin pH is crucial for physiological skin function. In aged or diseased skin, pH increase is observed and may negatively affect skin health. Skin care products with a pH that is slightly more acidic than the average normal skin pH and have an adequate buffering capacity, are considered beneficial for the skin. However, the buffer capacity of these products also plays an important role. In the present study, a possible normalization or acidification of skin surface pH and influence on skin hydration and skin barrier function was assessed via application of buffered skin care products that are formulated with pH ≤ 4.5. 48 subjects aged above 50 were treated with three different skin care products (Vitamin C Spheres, Collagen Spray, and Collagen Mask) and skin surface pH, skin hydration and barrier integrity were assessed before treatment start and after 4 weeks. The results show that after 4-week treatment with Vitamin C, the skin pH is acidified. Treatment with Collagen Spray and Collagen Mask showed maintenance of a physiological skin pH. Subgroup analysis of subjects that had a higher than average skin pH at study start demonstrated that all three tested skin care products were able to acidify the skin surface. In addition, skin hydration was also increased for two of the three tested products, whereas skin barrier is not significantly changed. This demonstrates that buffered skin care products formulated to a pH ≤ 4.5 are able to acidify and maintain physiological skin pH and may contribute to a physiological skin function.

pH-Responsive and Buffering Macromolecule Aqueous Absorbent and Mathematic Model-Based Feasibility Evaluation for SO_2 Capture

An organic macromolecule, poly(1-vinylimidazole), with an appropriate polymerization degree was proposed and mixed with water to form a novel aqueous absorbent for SO_2 capture. This aqueous solution absorbent has the advantages of simple preparation, good physicochemical properties, environment-friendliness, high ability in deep removal of SO_2, and excellent reusability. Moreover, pH-responsive behavior, pH buffering absorption mechanism, and their synergistic effect on absorption performance were revealed. The solubilities of SO_2 in the absorbent were measured in detail, and the results demonstrated excellent absorption capacity and recyclability. Then, mathematic models that describe SO_2 absorption equilibrium were established, and the corresponding parameters were estimated. More importantly, on the basis of model and experimental data, the absorption and desorption could maintain high efficiency within a wide operating region. In summary, this work provided a low-cost, efficient, and unique absorbent for SO_2 capture and verified its technical feasibility in industrial application.

Buffer Standards for Physiological pH of the Buffer N-(2-Acetamido)-2-aminoethanesulfonic Acid from 5°C to 55°C

Electromotive force (emf) measurements of the Cell Pt(s), H2(g)|ACES(m1) + NaACES(m2) + NaCl (m3)| AgCl, Ag(s) have been carried out from 5°C to 55°C . The agreement of pH values between two calculated (extended Debye-Hückel and liquid junction correction) is very good. Two buffer solutions without the chloride ion and seven buffer solutions with NaCl, at an ionic strength (I = 0.16 mol.kg-1) similar to that of physiological fluids, have been studied. The pH values for these buffer solutions have been evaluated in the temperature range of 5°C to 55°C using the extended Debye-Hückel equation of the Bates-Guggenheim convention. Values of the residual liquid junction potential (δEj) between the ACES solutions and the saturated KCl calomel electrode solution have been estimated at 25°C and 37°C from the previously determined Ej values using the flowing junction cell to determine the operational pH values at 25°C and 37°C. These ACES buffer solutions are recommended as secondary standard reference solutions for pH measurements in the range of physiological applicati on at I = 0.16 mol.kg-1.

Oxygen permeability of soft contact lenses in different pH, osmolality and buffering solution

AIMTo determine the effect of pH, osmolality, and buffering system on the oxygen permeability (Dk) of soft contact lenses.METHODSTwo hydrogel lenses (nelfilcon A and etafilcon A) and 2 silicone hydrogel lenses (lotrafilcon A and balafilcon A) were used in the study. These lenses were incubated in phosphate-buffered saline (PBS) and borate-buffered saline (BBS) solutions adjusted by 0.8 pH increments to a pH in the range of 5.8-9.0 or in hypotonic (280 mOsmol/kg), isotonic (310 mOsmol/kg) and hypertonic (380 mOsmol/kg) PBS solutions. Polarographic method was used for measuring the Dk and lenses were stacked as 4 layers to correct the boundary effect.RESULTSDk values of all contact lenses measured in BBS solutions were more stable than those in PBS solutions. Especially the etafilcon A lens showed a relative big change compared with other types of contact lenses at the same conditions. When the osmolality of PBS solution increased from hypotonic to hypertonic, Dk of all contact lenses decreased. Variations in Dk existed depending on lens materials, etafilcon A lens was the most affected and nelfilcon A was the least affected by osmolality.CONCLUSIONFrom the result obtained, it is revealed that Dk of contact lenses is changed by the pH, osmolality, and buffering condition of tear. Thus, Dk of contact lens can be varied by the lens wearers' physiological and/or pathological conditions.

Calculation of the pH of Buffer Solution of 2-[<i>N</i>-Morpholino]ethanesulfonic Acid (MES) from 5°C to 55°C

This paper reports the results for the pH of three buffer solutions free of chloride ion. The remaining six buffer solutions have saline media of the ionic strength I = 0.16 mol.kg-1, matching closely to that of the physiological sample. Conventional paH values for the three buffer solutions without the chloride ion and six buffer solutions with the chloride ion at I = 0.16 mol.kg-1 from 5°C to 55°C have been calculated. The operational pH values for five buffer solutions at 5°C and 55°C have been determined based on the difference in the values of the liquid junction potentials between the blood phosphate standard and the experimental buffer solutions. Five of these buffers are recommended as standards for the physiological pH range 7.5 to 8.5.

应用Octyl Sepharose FF疏水层析分离好食脉孢霉发酵产生的纤溶酶

疏水层析是分离纯化蛋白质和多肽等生物大分子的常用方法,采用Octyl Se pharose FF疏水层析填料对好食脉孢霉(N.sitophila)发酵产生的纤溶酶进行了初步分离,比较了样品初始盐浓度、缓冲液pH值和洗脱方式对分离效果的影响。实验结果表明,采用样品初始盐浓度为40%、缓冲液pH值为7.4和步阶式梯度洗脱方式对样品分离效果较好,经测定样品中有3种疏水性不同的纤溶活性组分,其中活性组分Ⅲ经Octyl Sepharose FF疏水层析分离后比活力为855.56U/mg,总纯化倍数为7.12倍。

SO_2伤害与葡萄汁液含酸量、pH值、缓冲容量的关系

成熟葡萄汁液含酸量在0．5％～0．7％之间，pH值在3．7～3．8之间，耐SO2巨峰品种的汁液含酸量、pH值和汁液缓冲容量均高于不耐SO2红地球品种。自然衰老时，葡萄果肉汁液含酸量下降、汁液缓冲容量下降；SO2常量处理可抑制含酸量及缓冲容量的下降，SO2超量处理则使葡萄汁液酸化、汁液缓冲容量下降幅度增大。

六种沙生灌木pH值、缓冲容量及对脲醛树脂胶(UF)固化时间的影响

为了合理开发我国西北地区的沙生灌木，研究了内蒙西部地区沙柳、柠条、沙棘、红柳、桦棒、杨柴６种主要沙生灌木的ｐＨ值、酸碱缓冲容量与ＵＦ胶混合物固化时间。结果表明：６种灌木均呈弱酸性，ｐＨ值为６０３～４５４，酸缓冲容量为０１０５～００４０ｍｍｏｌ，碱缓冲容量为０３１４～０２２２ｍｍｏｌ。种间的ｐＨ值、缓冲容量和ＵＦ胶固化时间差异显著，而每种灌木部位间的上术指标均无显著差异。

不同pH值缓冲液对玉米叶片蒸腾速率和相对含水量的影响

利用磷酸缓冲液和人造缓冲液(artificialsolution,AS)研究了玉米去根地上部分和离体叶片的蒸腾速率。结果表明,不同pH处理能够显著影响蒸腾速率,同一缓冲液不同pH值下的蒸腾速率差异较大;不同缓冲液影响下的蒸腾速率更是不同。不同pH值AS缓冲液对玉米离体叶片的相对含水量(RWC)有不同影响,pH7.5时的RWC较低。

稀释液溶质、渗透压、pH值和缓冲指数与低温保存鸡精液效果的关系

将葡萄糖、氯化钠、氯化钾、柠檬酸钠四种物质分别配制成三个渗透压水平(278m O sm、328m O sm、378m O sm)的12种单方精液稀释液,在低温(1～4℃)下进行鸡精液稀释保存试验,在四种物质中各选出一种好的稀释液,再将所选四种单方稀释液按不同比例制成复方精液稀释液,再次进行保存试验。所有稀释液均测定渗透压、pH值、缓冲指数、精子存活时间、精子生存指数等指标。结果表明:①柠檬酸钠、葡萄糖对鸡精液的保存具有重要作用,而氯化钾在鸡精液稀释液中并不是必需的。②复方稀释液保存效果普遍优于单方稀释液。③低温下鸡精液稀释液渗透压应为等渗或接近等渗,且最适渗透压还与构成稀释液的物质种类和相互配比有关系。④稀释液pH值应接近中性,最好与精液pH值保持一致。⑤在缓冲指数为3.894～7.257的范围内,缓冲指数与精子存活时间和生存指数呈现显著的负相关。

硫化物矿物溶解度与溶液pH值的关系

硫化物作为自然界常见的一大类矿物 ,由于溶解度很小 ,硫化物对水pH值的影响以及水对它的溶解度影响往往被人们所忽视。通过计算常见硫化物矿物的自由能ΔG0f、溶度积Ksp和溶解度S、绘制logS—pH曲线 ,得出硫化物矿物在不同 pH值条件下的溶解规律 ,水溶液的pH值受硫化物矿物的控制 ;反过来 ,水溶液的pH值也影响着矿物溶解度的大小。此外 ,对硫化物矿物饱和溶液的缓冲范围。

模拟不同pH降雨和施氮对水耕铁渗人为土酸化的影响

室内模拟研究3个pH梯度降雨和3水平的施氮量对水耕铁渗人为土土壤酸化的影响。结果表明,不同pH降雨及施氮处理土壤的酸度累积量为4.73～15.57 mmol H+每柱,分别以pH 6.5降雨和不施氮处理、pH 2.5添加高氮量(N2)处理酸化速率为最低和最高,相同pH降雨处理下,致酸量随施氮量增加而上升;相同施氮下,不施氮处理土壤酸度累积随降雨pH降低而增加,但中施氮量(150 mg kg-1土)和高施氮量(300 mg kg-1土)下,pH 4.5处理土壤酸度累积量则小于pH 6.5处理;不同降雨及施氮处理NO3-淋溶致酸量为4.32～12.88 mmol每柱,NH+4淋溶消耗H+量为0.01～0.29 mmol每柱;正常酸沉降(pH 6.5)下,中施氮量和高施氮量处理致酸量都大于各梯度pH降雨的致酸量。以上结果表明,单施氮处理的致酸量大于单纯的酸沉降处理,而无论是降雨还是施氮,NO-3淋溶在加速土壤酸化进程中占主导作用。

泡桐和毛白杨的pH值与酸碱缓冲容量

实测了河南巩义产泡桐和毛白杨木材的化学成分;分析了这两种速生材的pH值、酸碱缓冲容量及其对脲醛树脂胶凝胶时间的影响,同时与北京产的毛白杨作了相应性质的对比.研究结果表明,泡桐材的各种溶液抽出物的含量均较高;三个树种的pH值范围为5.19～6.28,为弱酸性;北京毛白杨的边、心材的酸缓冲容量存在较大差异;三个树种对脲醛树脂胶凝胶时间的影响程度基本是相同的.

染色木材pH值与缓冲容量的比较分析

分别用酸性染料与活性染料,对大青杨和桦木单板进行直接染色和NaOH溶液预处理后染色,测量2种染色单板的pH值和缓冲容量,并与未染色单板进行对比。结果表明,NaOH溶液预处理、酸性染料、活性染料的染色对2种单板的pH值及缓冲容量的影响规律一致;染色可小幅度增加木材pH值,显著降低酸缓冲容量;预处理则可较大幅度增加pH值,并一定程度上增加酸缓冲容量;大青杨单板经2种工艺染色后,其酸缓冲容量均有明显下降;桦木单板直接染色酸缓冲容量减小,而预处理后染色则酸缓冲容量增大。