Absorption of Sulphur Dioxide with Sodium Citrate Buffer Solution in a Rotating Packed Bed

Absorption of SO2 from a SO2/air mixture with sodium citrate buffer solution was investigated using a rotating packed bed(RPB) in laboratory scale.The effects of operating parameters,such as the rotation speed of RPB,liquid-gas ratio,inlet gas flow rate,inlet concentration of SO2 in flue gas,sodium citrate buffer concentration and initial pH of absorption solution,on the SO2 concentration in the absorption solution or removal efficiency of SO2 were examined.Incremental rate of sulfate radical ions in the absorption solution was also examined.Experimental results indicate that the efficiency of this regenerative process will be improved by using RPB under appropriate operating conditions,and the generation of SO2-4 will be restrained in the process in RPB.

High performance of zinc-ferrum redox flow battery with Ac^-/HAc buffer solution

A green low-cost redox flow battery using Zn/Znredox couple in HAc/NaAc medium and Fe/Feredox couple in HSOmedium was first proposed and investigated for potential stationary energy storage applications. The presence of HAc/NaAc in the negative electrolyte can keep the pH between 2.0 and 6.0even when a large amount of Hions move into negative electrolyte from positive electrolyte through ion exchange membrane. In the pH range of 2.0–6.0, the chemical reaction of Zn species with Hspecies is very insignificant; furthermore, the electroreduction of Hion on the negative electrode is significantly suppressed at this pH range. The zinc-ferrum redox flow battery（Zn/Fe RFB） operated within a voltage window of 0.5–2.0 V with a nearly 90% utilization ratio, and its energy efficiency is around 71.1% at room temperature. These results show that Zn/Fe RFB is a promising option as a stationary energy storage equipment.

Hemicellulose in corn straw:Extracted from alkali solution and produced5-hydroxymethyl furfural in HCOOH/HCOONa buffer solution

Hemicellulose in corn straw is a group of complex heteropolysaccharides which are composed of different sugar units, including mannans, xylans, arabinans and galactans. This study developed a simple and practical process for production of 5-hydroxymethyl furfural(HMF) using hemicellulose that was extracted from corn straw. In the hemicellulose degradation process HCOOH/HCOONa was used as buffer solution, and the optimum conditions for maximum HMF yield were explored. Various extraction conditions including NaOH concentration, reaction time,temperature, solid-to-liquid ratio and precipitant were tested for hemicellulose obtaining, giving the optimum condition of 55 °C, 4 h, solid-to-liquid ratio of 1:10, 1.5 mol·L^(-1) NaOH solution and ethanol as precipitant with the yield of 34.16%. Dehydration of hemicellulose under HCOOH/HCOONa buffer solution process, using solution medium of pH = 0.8 hydrolyzed hemicellulose in corn straw at 190 °C after 190 min and 82% of HMF yield was achieved.

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.

Possible Effect of Pressure Solution on the Movement of a Canister in the Buffer of Geological Disposal System

One of the major concepts of the geological disposal of high level radioactive waste is to enclose a metallic container with bentonite buffer which is considered to be impermeable and chemically stable. Since the average density of the container is around 6 to 7 and very heavy compared to bentonite, the scenario of container sinking has been evaluated because excess sinking makes short the pathway of nuclide migration in the bentonite and is detrimental to the safety of the disposal system. Previous considerations on container sinking have been made from the viewpoint of mechanical deformation of the bentonite. In this paper, a chemical deformation process is presented as another mechanism of container sinking, which has not been previously considered for the container sinking in the field of radioactive waste disposal. The chemical deformation mentioned in this paper is the deformation through the process of pressure solution of minerals constituting the buffer, transportation by diffusion and precipitation. That such chemical deformation is a ubiquitous phenomenon occurring in various scales in the crust of the earth will be shown through the review of previous works. Then, some future research topics will be suggested which would be required in order to evaluate the container sinking in the safety case for radioactive waste disposal.

Electrodeposition of nickel from alkaline NH_4OH/NH_4Cl buffer solutions

The electrodeposition of nickel on steel and copper from alkaline NH4OH/NH4Cl buffer solutions was investigated by cyclic voltammetry (CV), chronopotentiometry (CP), chronoamperometry (CA) as well as an opto-digital microscope, glow-discharge optical emission spectroscopy (GD-OES), XRF, and SEM-EDS techniques. The aim was to obtain Ni coatings from weak alkaline solutions and to optimize the process. The electrolyte composition, pH, temperature as well as current and potential parameters of the process were optimized using the quality of Ni deposit as a criterion. The role of hydrogen evolution in the process was discussed. An influence of Co as an additive was also investigated. It was found that a small amount of Co catalyzes Ni deposition process and improves the quality and color of the deposit. Therefore, in the possible application, the Ni/Co codeposition should be seriously considered. It was also shown that for constant current deposition mode, the width of self-established potential range, revealed at the very beginning of the process by the chronopotentiometric E=f(t) curves, is related to the quality of the coating.

Tolerance to Zn deficiency and P-Zn interaction in wheat seedlings cultured in chelator-buffered solutions

Zinc deficiency is a common constraint for wheat production in the regions with limited precipitation,particularly in the regions with high levels of available phosphate （P） in soil.Two experiments were conducted using chelator-buffered nutrient solutions to characterize differences in tolerance to Zn deficiency among three winter wheat （Triticum aestivum L）.genotypes and to investigate the relationship between P and Zn nutrition in wheat species.Four indices,Zn efficiency,relative shoot-to-root ratio,total Zn uptake in shoot,and shoot dry weight were used to compare the tolerance to Zn deficiency among three wheat genotypes.The results indicated that the four indices could be used in breeding selection for Zn uptake-efficient genotypes.The genotype H6712 was the most tolerant to Zn deficient,followed by M19,and then X13.Specifically,H6712 had the highest Zn uptake efficiency among the three genotypes.The addition of P to the growth medium increased Zn uptake and translocation from roots to shoots.Total Zn content of the wheat plant was 43% higher with 0.6 mmol/L P treatment than that of control with 0 mmol /L P treatment.The Zn translocation ratios from roots to shoots were increased by 16% and 26% with 0.6 mmol/L P treatment and 3 mmol/L P treatment,respectively,compared with 0 mmol/L P treatment.In contrast,high Zn concentrations in the growth medium inhibited P translocation from roots to shoots,but the inhibitive effects were not strong.Sixty-six percent of P taken up by wheat plants was translocated to the wheat shoots at 0 μmol/L Zn treatment,while the percent was 60% at 3 μmol/L Zn treatment.The result may be due to the fact that the wheat plants need more P than Zn.

Bicarbonate used as a buffer for controlling nutrient solution pH value during the growth of hydroponic lettuce

Unstable pH of nutrient solution in hydroponic systems is a major obstacle to production.To simplify the management of nutrient solution pH and attenuate negative effects of pH on plant growth,this study investigated the effect of different buffer salt additions on nutrient solution pH,ion uptake,growth and photosynthesis of Yamazaki lettuce,with the equivalent concentrations of macro-element unchanged.The results indicated that the pH of nutrient solution was buffered to varying degrees by the 2 mol/L HCO_(3)^(-),1 mol/L HCO_(3)^(-),and 0.33 mol/L HPO_(4)^(2-)The 0.33 mol/L HPO_(4)^(2-)treatment fluctuated most with a pH of 1.74 units,while the addition of HCO_(3)^(-)buffered nutrient solution pH was better,with higher pH values(7.2-7.7).The CK-pH control solution,1 mol/L HCO_(3)^(-)and 0.33 mol/L HPO_(4)^(2-)treatments all promoted the uptake of ion and then the growth of lettuce was better in comparison with the CK-pH no adjustment treatment,while the 2 mol/L HCO_(3)^(-)treatment inhibited K uptake and reduced the availability of Fe,the shoot and root fresh weight of lettuce decreased by 21.3%and 10.1%,respectively.In addition,although the chlorophyll content and net photosynthetic rate under 1 mol/L HCO_(3)^(-)and 0.33 mol/L HPO_(4)^(2-)treatments were significantly lower than the CK-pH control solution treatment,there were no significant differences in leaf length and leaf number of lettuce among them,and shoot fresh weight per plant was 83.09,82.95,and 78.92 g,respectively.In conclusion,adding 1 mol/L HCO_(3)^(-)to the nutrient solution in a single dosage not only buffered the pH of nutrient solution better but also promoted ion uptake,it had no negative effects on the growth,photosynthesis and ion uptake of hydroponic lettuce in comparison with the CK-pH control solution treatment.Therefore,1 mol/L HCO_(3)^(-)can be used as a buffer during the growth of hydroponic lettuce and reduce frequent addition of acids or alkalis,and then simplify the management of nutrient solution for hydroponic lettuce production.

Tetraalkyl-substituted zinc phthalocyanines used as anode buffer layers for organic light-emitting diodes

Two soluble tetraalkyl-substituted zinc phthalocyanines(ZnPcs)for use as anode buffer layer materials in tris(8-hydroxyquinoline)aluminum(Alq3)-based organic light-emitting diodes(OLEDs)are presented in this work.The holeblocking properties of these Zn Pc layers slowed the hole injection process into the Alq3 emissive layer greatly and thus reduced the production of unstable cationic Alq3(Alq3^+)species.This led to the enhanced brightness and efficiency when compared with the corresponding properties of OLEDs based on the popular poly-(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)buffer layer.Furthermore,because of the high thermal and chemical stabilities of these Zn Pcs,a nonaqueous film fabrication process was realized together with improved charge balance in the OLEDs and enhanced OLED lifetimes.

Buffer Standards for the Biochemical pH of the Zwitterionic Buffer <i>N</i>-Tris-(Hydroxymethyl) Methyl-2-Aminoethanesulfonic Acid (TES) from 5℃ to 55℃

The authors have undertaken the determination of pH values for one buffer solution of TES without NaCl and nine buffer solutions with NaCl yielding an ionic strength I = mol.kg-1. similar to that of blood. These buffer solutions have been evaluated in the temperature range of 5℃ to 55℃ using an extended version of the Debye-Hückel equation. The pH values are reported using 1) the Debye-Hückel extension of the Bates-Guggenheim convention in the tempera- ture range 5℃ to 55℃ and 2) with and without liquid junction correction at 25℃ and 37℃. These TES buffer solutions are recommended as secondary standard references for pH measurements in the range of pH 7.2 to 7.5 for physiological application with an ionic strength of I = 0.16 mol.kg-1.

Buffer Sizing Method for Constructing Stable Schedules with Duration Constraints

The assumption of static and deterministic conditions is common in the practice of construction project planning. However, at the construction phase, projects are subject to uncertainty. This may lead to serious schedule disruptions and, as a consequence, serious revisions oft.he schedule baseline. The aim of the paper is developing a method for constructing robust project schedules with a proactive procedure. Robust project scheduling allows for constructing stable schedules with time buffers introduced to cope with multiple disruptions during project execution. The method proposed by the authors, based on Monte Carlo simulation technique and mathematical programming for buffer sizing optimization, was applied to scheduling an example project. The results were compared, in terms of schedule stability, to those of the float factor heuristic procedttre.

CeO_(2)-Ps-LaCoO_(3)/Al_(2)O_(3)的制备及其对高浓度有机废水的臭氧催化降解研究

为有效降解高浓度造纸废水有机物,通过电化学沉积法分别在磷酸盐中性缓冲溶液和纯水中制得CeO_(2)-Ps-LaCoO_(3)/Al_(2)O_(3)和CeO_(2)-LaCoO_(3)/Al_(2)O_(3)。通过对CeO_(2)-Ps-LaCoO_(3)/Al_(2)O_(3)、CeO_(2)-LaCoO_(3)/Al_(2)O_(3)以及LaCoO_(3)/Al_(2)O_(3)进行XRD、SEM、析氧过电位和电阻抗等物性表征发现,CeO_(2)-Ps-LaCoO_(3)/Al_(2)O_(3)具有更强催化氧化性及稳定性。对高浓度造纸废水臭氧催化氧化降解3 h后,CeO_(2)-Ps-LaCoO_(3)/Al_(2)O_(3)对废水COD的降解率为76.5%,而相同条件下CeO_(2)-LaCoO_(3)/Al_(2)O_(3)和LaCoO_(3)/Al2O_(3)的化学需氧量(COD)降解率分别为68.5%和63.5%。

“缓冲溶液的配制及性质”的创新设计

缓冲溶液是一种能使体系pH值稳定的溶液,在生活中有广泛的应用。无机化学实验、无机及分析化学实验课程中均设置了该实验内容。但根据实践教学发现,传统的实验内容只是设置了单一浓度条件,用pH试纸测试溶液的pH变化,这样的设计存在不直观、设置条件单一等问题,达不到本实验的教学目的。为此,我们重新设计了这部分实验内容:采用指示剂的显色变化代替pH试纸来检验溶液酸碱度的变化;增设不同浓度、不同缓冲比的缓冲溶液及使用精密pH计,考察缓冲容量的影响因素。以上创新设计,学生可以直观地观察溶液颜色的变化,从而理解缓冲溶液的缓冲作用,又可以通过多因素的实验设计,系统地掌握不同的缓冲条件对缓冲容量的影响。从而达到本实验的教学目的及培养学生的自主思考能力和归纳总结能力。

血清蛋白乙酸纤维素薄膜电泳方法的优化

乙酸纤维素薄膜电泳是生物化学与分子生物学实验常规项目之一,临床上广泛应用于血清蛋白、糖蛋白及核酸等生物大分子的分离与检测。该实验受环境和人为因素影响较多,初次操作往往难以取得理想的实验结果,更换乙酸纤维素薄膜厂家后,原来的实验条件分离血清蛋白存在蛋白条带聚集、分不开现象。缓冲液离子浓度和成分是影响乙酸纤维素电泳的最关键因素,采用pH 8.6,离子强度0.025 M/L、0.075 M/L的巴比妥缓冲液;pH 8.6,离子强度0.05 M/L、0.08 M/L的硼酸缓冲液,用4种缓冲液对新膜进行筛选,并对电泳时长及上样进行优化。结果表明,用pH 8.6、离子强度为0.08 M/L硼酸缓冲液,电压100 V,电泳时长50 min,分离兔血清蛋白实验结果比较理想,能满足实验教学及临床检验要求。

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。

高浓度磷酸盐缓冲液中多巴胺电化学氧化过程的在线质谱分析

研究高浓度缓冲盐体系中物质的电化学氧化还原过程,对于准确理解电化学反应机理具有重要意义。本研究研制了一款体积小、性能稳定、结构简单、制作方便的流动电解池,将其与大气压化学电离质谱联用,构建了一种可在线分析高浓度缓冲盐溶液中电化学过程的电化学-质谱分析装置,用于在线、实时研究缓冲盐溶液中多巴胺的电化学氧化过程。结果表明,通过热沉积方式可高效地在线去除缓冲溶液中的无机盐组分,有机组分可经大气压化学电离方式进行离子化,随后进入质谱检测。多巴胺电化学氧化质谱分析结果表明:在0 V氧化电位下,多巴胺不发生氧化,主要获得多巴胺的质子化信号m/z 154[M+H]^(+);当氧化电位为+0.3 V时,除多巴胺的质子化信号外,还可获得多巴胺失去4个e-的氧化产物多巴色素(dopachrome)质子化峰m/z 150[M+H]^(+),以及多巴色素与多巴胺通过分子间氢键形成的加合物信号m/z 303[M+H]^(+);当氧化电位升高至+0.6 V时,氧化产物m/z 150和303的丰度进一步提高。

基于改进关键链技术的营房工程应用

营房工程建设有别于传统的建筑工程,往往建设过程更为严格要求,建设时间周期更为紧迫,建设质量更为可靠。当前,在奋力推动实现百年建军目标,打造世界一流军队的新征程中,需要进一步提高营房工程的建设质量、效率,以更好的服务军队战斗力建设。论文以某部营房工程中车库工程项目为例,重点针对非关键链管控不到位问题,引入传统里程碑管理理念,提出非关键链的里程碑缓冲,从而有效应对现有管理中非关键链进度管控不力,达到提升项目进度稳定性的目标。从实践结果来看,某部车库工程采用改进后的关键链方法,在不增加项目总工期的前提下,通过非关键链里程事件碑缓冲设置,提升了非关键链吸收不确定性能力,避免非关键链缓冲消耗过大造成的项目延期,最终使得整体项目的解的鲁棒性提高。

“线上线下混合+翻转课堂”教学模式应用研究——以基础化学教学中的“缓冲溶液及作用机制”为例

在“学生中心、产出导向”的教育背景下,以基础化学中的“缓冲溶液及作用机制”为例,根据小学教育专业学生特点,运用“线上线下混合+翻转课堂”教学模式,合理安排学生进行课前线上自学,课中创设情景、翻转课堂、知识迁移等,课后巩固提高。引导学生主动思考,激发学生的学习兴趣,促进学生化学学习思维的形成。

Cu箔缓冲层对SiO_(2)/TC4接头组织性能的影响

针对SiO_(2)石英玻璃/TC4钛合金钎焊接头易脆裂难题,以Cu箔为缓冲层,采用AgCuTi活性钎料对石英玻璃/TC4钛合金进行真空钎焊。通过金相显微镜、扫描电镜、能谱仪以及X射线衍射仪、力学试验机分析Cu缓冲层及不同钎焊工艺对SiO_(2)/TC4接头组织结构及力学性能的影响。研究结果表明,在合适的钎焊温度下,Cu箔缓冲层的加入一方面在SiO_(2)/AgCuTi界面处形成了合适厚度的TiSi_(2)+Ti_(4)O_(7)/Cu_(2)Ti_(4)O双层结构,另一方面在焊缝中形成大量韧性较好的Cu固溶体,这些固溶体在钎焊冷却过程中通过钎缝自身的蠕变和屈服吸收接头中的残余应力,减少接头残余应力,提高了钎焊接头的力学性能。当钎焊温度为900℃、保温时间10 min时,SiO_(2)/TC4钎焊接头抗剪强度最高,达到38 MPa。Cu箔缓冲层的加入显著改善了SiO_(2)石英玻璃/TC4钎焊接头的力学性能。

钾盐镀锌溶液中硼酸含量的测定

硼酸作为一种弱酸缓冲剂,在电镀行业中通常用于调节电镀液的pH值。快速准确地测定电镀溶液中硼酸含量对镀液pH值的有效控制、改善镀层致密度性和提高产品质量有着重要作用。基于钕铁硼永磁材料钾盐镀锌溶液中硼酸浓度的严格要求,通过对等离子参数、光谱参数、分析谱线及溶液介质等因素的探讨,建立电感耦合等离子体原子发射光谱(ICP-AES)法测定钾盐镀锌溶液中的硼含量,进而换算得到镀锌溶液中硼酸含量的方法。结果表明:钾盐镀锌溶液的稀释倍数,需参照硼元素的标准曲线,使稀释溶液中硼元素的含量在其标准曲线范围内。最后得出硼元素的检出限(3s)为0.01~0.05 mg/L;经测试后换算得硼酸回收率为98%~102%,其相对标准偏差(n=11)为1%~3%,充分验证了本方法的可靠性。该方法可推广用于所有镀液中硼酸含量的测定,具有准确、方便、快捷的优点,为电镀行业中的硼酸含量的准确测试提供了一种新的思路。