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...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.展开更多
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 obs...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.展开更多
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...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.展开更多
Three electrokinetic（EK） experiments were designed to study the remediation efficiency of Cr（Ⅲ） by EK-oxidation method and to investigate the influence of complexes and p H buffer solution in EK-oxidation process...Three electrokinetic（EK） experiments were designed to study the remediation efficiency of Cr（Ⅲ） by EK-oxidation method and to investigate the influence of complexes and p H buffer solution in EK-oxidation process. Sediments Cr（Ⅲ） can be oxidized into Cr（Ⅵ） effectively by KMn O4, but the oxidation efficiency is not proportional to the dose of oxidant, and chemical oxidation process leads to a bit lower buffering capacity of the sediment. Compared with the simple EK remediation, the removal efficiency of total Cr in the sediments increased 32.6% by EK-oxidation method, and the concentrations of total chromium in the sediment showed increasing trend from the cathode to the anode after EK-oxidation treatment. The p H control and KMn O4 improved the removal of Cr（Ⅵ） and total Cr from the sediments. Due to stronger complexation action of citric acid with Cr（Ⅲ） in sediments, citric acid in the catholyte obviously increased the removal rate of total Cr in sediments. Finally, the removal rate of total Cr from sediments reached 60.9% by adding complex and controlling the p H of cathode and anode pond solution on EK-oxidation processes.展开更多
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 (exte...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.展开更多
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 (lotraf...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.展开更多
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 p...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.展开更多
Aqueous zinc-ion batteries(AZIBs)have developed rapidly in recent years but still face several challenges,including zinc dendrites growth,hydrogen evolution reaction,passivation and corrosion.The pH of the electrolyte...Aqueous zinc-ion batteries(AZIBs)have developed rapidly in recent years but still face several challenges,including zinc dendrites growth,hydrogen evolution reaction,passivation and corrosion.The pH of the electrolyte plays a crucial role in these processes,significantly impacting the stability and reversibility of Zn^(2+)deposition.Therefore,pH-buffer tris(hydroxymethyl)amino methane(tris)is chosen as a versatile electrolyte additive to address these issues.Tris can buffer electrolyte pH at Zn/electrolyte interface by protonated/deprotonated nature of amino group,optimize the coordination environment of zinc solvate ions by its strong interaction with zinc ions,and simultaneously create an in-situ stable solid electrolyte interface membrane on the zinc anode surface.These synergistic effects effectively restrain dendrite formation and side reactions,resulting in a highly stable and reversible Zn anode,thereby enhancing the electrochemical performance of AZIBs.The Zn||Zn battery with 0.15 wt%tris additives maintains stable cycling for 1500 h at 4 mA·cm^(−2) and 1120 h at 10 mA·cm^(−2).Furthermore,the Coulombic efficiency reaches~99.2%at 4 mA·cm^(−2)@1 mAh·cm^(−2).The Zn||NVO full batteries also demonstrated a stable specific capacity and exceptional capacity retention.展开更多
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...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。展开更多
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...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。展开更多
文摘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.
文摘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.
基金supported by the National Key R&D Program of China (No. 2016YFC0400406)
文摘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.
基金Supported by the“Twelfth Five-Year”National Science and Technology Major Projects(2014ZX07104-005)
文摘Three electrokinetic（EK） experiments were designed to study the remediation efficiency of Cr（Ⅲ） by EK-oxidation method and to investigate the influence of complexes and p H buffer solution in EK-oxidation process. Sediments Cr（Ⅲ） can be oxidized into Cr（Ⅵ） effectively by KMn O4, but the oxidation efficiency is not proportional to the dose of oxidant, and chemical oxidation process leads to a bit lower buffering capacity of the sediment. Compared with the simple EK remediation, the removal efficiency of total Cr in the sediments increased 32.6% by EK-oxidation method, and the concentrations of total chromium in the sediment showed increasing trend from the cathode to the anode after EK-oxidation treatment. The p H control and KMn O4 improved the removal of Cr（Ⅵ） and total Cr from the sediments. Due to stronger complexation action of citric acid with Cr（Ⅲ） in sediments, citric acid in the catholyte obviously increased the removal rate of total Cr in sediments. Finally, the removal rate of total Cr from sediments reached 60.9% by adding complex and controlling the p H of cathode and anode pond solution on EK-oxidation processes.
文摘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.
文摘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.
文摘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.
基金supported by the Fund of Xuzhou Science and Technology Key R&D Program(Social Development)Project(No.KC22289)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX22_2783).
文摘Aqueous zinc-ion batteries(AZIBs)have developed rapidly in recent years but still face several challenges,including zinc dendrites growth,hydrogen evolution reaction,passivation and corrosion.The pH of the electrolyte plays a crucial role in these processes,significantly impacting the stability and reversibility of Zn^(2+)deposition.Therefore,pH-buffer tris(hydroxymethyl)amino methane(tris)is chosen as a versatile electrolyte additive to address these issues.Tris can buffer electrolyte pH at Zn/electrolyte interface by protonated/deprotonated nature of amino group,optimize the coordination environment of zinc solvate ions by its strong interaction with zinc ions,and simultaneously create an in-situ stable solid electrolyte interface membrane on the zinc anode surface.These synergistic effects effectively restrain dendrite formation and side reactions,resulting in a highly stable and reversible Zn anode,thereby enhancing the electrochemical performance of AZIBs.The Zn||Zn battery with 0.15 wt%tris additives maintains stable cycling for 1500 h at 4 mA·cm^(−2) and 1120 h at 10 mA·cm^(−2).Furthermore,the Coulombic efficiency reaches~99.2%at 4 mA·cm^(−2)@1 mAh·cm^(−2).The Zn||NVO full batteries also demonstrated a stable specific capacity and exceptional capacity retention.
文摘将葡萄糖、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。
