The mechanism of dentine hypersensitivity:Stimuli-induced directional cation transport through dentinal tubules

Dentine hypersensitivity is an annoying worldwide disease,yet its mechanism remains unclear.The long-used hydrodynamic theory,a stimuli-induced fluid-flow process,describes the pain processes.However,no experimental evidence supports the statements.Here,we demonstrate that stimuli-induced directional cation transport,rather than fluid-flow,through dentinal tubules actually leads to dentine hypersensitivity.The in vitro/in vivo electro-chemical and electro-neurophysiological approaches reveal the cation current through the nanoconfined negatively charged dentinal tubules coming from external stimuli(pressure,pH,and temperature)on dentin surface and further triggering the nerve impulses causing the dentine hypersensitivity.Furthermore,the cationic-hydrogels blocked dentinal tubules could significantly reduce the stimuli-triggered nerve action potentials and the anionhydrogels counterpart enhances those,supporting the cation-flow transducing dentine hypersensitivity.Therefore,the inspired ion-blocking desensitizing therapies have achieved remarkable pain relief in clinical applications.The proposed mechanism would enrich the basic knowledge of dentistry and further foster breakthrough initiatives in hypersensitivity mitigation and cure.

Bile duct ligation differently regulates protein expressions of organic cation transporters in intestine,liver and kidney of rats through activation of farnesoid X receptor by cholate and bilirubin

Body is equipped with organic cation transporters(OCTs).These OCTs mediate drug transport and are also involved in some disease process.We aimed to investigate whether liver failure alters intestinal,hepatic and renal Oct expressions using bile duct ligation(BDL)rats.Pharmacokinetic analysis demonstrates that BDL decreases plasma metformin exposure,associated with decreased intestinal absorption and increased urinary excretion.Western blot shows that BDL significantly downregulates intestinal Oct2 and hepatic Oct1 but upregulates renal and hepatic Oct2.In vitro cell experiments show that chenodeoxycholic acid(CDCA),bilirubin and farnesoid X receptor(FXR)agonist GW4064 increase OCT2/Oct2 but decrease OCT1/Oct1,which are remarkably attenuated by glycine-β-muricholic acid and silencing FXR.Significantly lowered intestinal CDCA and increased plasma bilirubin levels contribute to different Octs regulation by BDL,which are confirmed using CDCA-treated and bilirubin-treated rats.A disease-based physiologically based pharmacokinetic model characterizing intestinal,hepatic and renal Octs was successfully developed to predict metformin pharmacokinetics in rats.In conclusion,BDL remarkably downregulates expressions of intestinal Oct2 and hepatic Oct1 protein while upregulates expressions of renal and hepatic Oct2 protein in rats,finally,decreasing plasma exposure and impairing hypoglycemic effects of metformin.BDL differently regulates Oct expressions via Fxr activation by CDCA and bilirubin.

An in vitro study on interaction of anisodine and monocrotaline with organic cation transporters of the SLC22 and SLC47 families

Current study systematically investigated the interaction of two alkaloids, anisodine and monocrotaline, with organic cation transporter OCT1, 2, 3, MATE1 and MATE2-K by using in vitro stably transfected HEK293 cells. Both anisodine and monocrotaline inhibited the OCTs and MATE transporters. The lowest IC50 was 12.9 μmol·L-1 of anisodine on OCT1 and the highest was 1.8 mmol·L-1 of monocrotaline on OCT2. Anisodine was a substrate of OCT2(Km = 13.3 ± 2.6 μmol·L-1 and Vmax = 286.8 ± 53.6 pmol/mg protein/min). Monocrotaline was determined to be a substrate of both OCT1(Km = 109.1 ± 17.8 μmol·L^-1, Vmax = 576.5 ± 87.5 pmol/mg protein/min) and OCT2(Km = 64.7 ± 14.8 μmol·L^-1, Vmax = 180.7 ± 22.0 pmol/mg protein/min), other than OCT3 and MATE transporters. The results indicated that OCT2 may be important for renal elimination of anisodine and OCT1 was responsible for monocrotaline uptake into liver. However neither MATE1 nor MATE2-K could facilitate transcellular transport of anisodine and monocrotaline. Accumulation of these drugs in the organs with high OCT1 expression(liver) and OCT2 expression(kidney) may be expected.

Ionic covalent organic frameworks with tailored anionic redox chemistry and selective ion transport for high-performance Na-ion cathodes

Employing cathode materials with multiple redox couples and electrolytes with efficient cation transport kinetics are two effective approaches to improving the electrochemical performance of batteries.In this work,for the first time,we present a design strategy of simultaneously realizing reversible cationic and anionic redox chemistries as well as selective anion/cation transport in the viologen-based COFs(BAVCOF:X,coordinated anions of X=Cl^(-),Br^(-),I^(-),and ClO_(4)^(-))for high-performance Na-ion cathodes.Besides the cationic redox of viologen segments,the different redox activities of anions effectively tune the total capacities of the COFs.Meanwhile,electrochemical analysis and ab-initial molecular dynamics(AIMD)calculation illustrate that the anion/cation transport kinetics of electrolytes caged in the COFs'channels can be selectively tuned by the coordinated anions.As a result,combining high-potential Br-/Br_(2)redox couple,cationic redox of viologen segments,and enhanced Na+transport kinetics,the BAV-COF:Brdemonstrates stable performance with energy densities of 358.7 and 145.2 Wh kg^(-1)at power densities of 116.5 and 2124.1 W kg^(-1),respectively.This study offers new insight into the fabrication of organic cathodes with anionic redox and the advantages of COFs electrode materials in anion/cation transport selectivity for energy storage applications.

国内深海油气田开发用无缝钢管的设计及应用现状

随着能源需求的不断增加,全球海洋油气开发需求与日俱增。本文介绍了国内深海油气田开发现状及发展趋势,总结出深海油气田开发用管的特点及主要技术要求,调研了国内油气输送用大口径海洋用无缝管线管生产现状,论述了钢管的种类、轧制方法及国内主要钢管生产企业的生产能力,并结合国内某深水油田实际海管设计要求,指出了我国深海油气田输送管线管材料设计、生产工艺、几何尺寸和力学性能要求。鉴于我国深海油气开发起步晚,与国外发达国家相比仍存在很大差距,今后应重点完善管材设计和生产装备,同时结合输送工况的需求开发高品质大口径输送油气用无缝管线管。

Copper transportion of WD protein in hepatocytes from Wilson disease patients in vitro

AIM: To study the effect of copper transporting P-type ATPase in copper metabolism of hepatocyte and pathogenesis of Wilson disease (WD).METHODS: WD copper transporting properties in some organelles of the cultured hepatocytes were studied from WD patients and normal controls. These cultured hepatocytes were incubated in the media of copper 15mg.L-1 only, copper 15 mg. L-1 with vincristine (agonist of P-type ArPase) 0.5mg. L-1, or copper 15 mg. L-1 withvanadate (antagonist of P-type ATPase) 18.39 mg. L-1separately. Microsome (endoplasmic reticulum and Golgi apparatus), lysosome, mitochondria, and cytosol were isolated by differential centrifugation. Copper contents in these organelles were measured with atomic absorption spectrophotometer, and the influence in copper transportion of these organelles by vanadate and vincristine were comparatively analyzed between WD patients and controls.WD copper transporting P-type ATPase was detected by SDS-PAGE in conjunction with Western blot in liver samples of WD patients and controls.RESULTS: The specific WD proteins (Mr155 000 lanes) were expressed in human hepatocytes, including the control and WD patients. After incubation with medium containing copper for 2 h or 24 h, the microsome copper concentration in WD patients was obviously lower than that of controls,and the addtion of vanadate or vincristine would change the copper transporting of microsomes obviously. When incubated with vincristine, levels of copper in microsome were significantly increased, while incubated with vanadate,the copper concentrations in microsome were obviously decreased. The results indicated that there were Wdproteins, the copper transportion P-type ATPase in the microsome of hepatocytes. WD patients possessed abnormal copper transporting function of WD protein in the microsome, and the agonist might correct the defect of copper transportion by promoting the activity of copper transportion P-type ATPase.CONCLUSION: Copper transportion P-type ATPase plays an important role in hepatocytic copper metabolism.Dysfunction of hepatocytic WD protein copper transportion might be one of the most important factors for WD.

Hepatocellular transport proteins and their role in liver disease

MOLECULAR PHYSIOLLGY OF HEPATOCELLULAR TRANSPORT PROTEINS Basolaferal transport systems Na+-dependent bile salt uptake Uptake of bile salts into the liver was first isolated perfused rat liver[1],isolated hepatocyte cultures and basolateral plasma membrane vesicles [2,4].

Substances Transport in an Underground River of Typical Karst Watershed During Storm Events

Hydrologic process,turbidity,suspended particles matters(SPM),major cations and TOC concentrations during two storm events in late April 2008 were monitored at Jiangjia Spring which is the outlet of Qingmuguan underground river system.Scanning electron microscopy(SEM) and energy disperse spectroscopy(EDS) analyses of SPM were

Inhibitory effects of apigenin and kaempferol on the essential solute carrier transporters

AIM: To evaluate the inhibitory effects of apigenin and kaempferol on the uptake of several important solute carrier(SLC) transporters.METHODS: Various SLC transporters including the essential human organic anion transporter 1(OAT1), OAT2, OAT3 and OAT4 as well as the important organic cation transporter 1(OCTN1) and OCTN2, were overexpressed in human embryonic kidney(HEK)-293 cells, a well-established cell model of transporter studies. Transport uptake assay was performed 24 h after the transfection. The transport activity was assessed with the uptake of previously determined transporter model substrates and the inhibitory effect of apigenin and kaempferol was evaluated with the substrate uptake in the presence of 10 μmol/L of each compound. Uptakemeasurements with varying concentrations of inhibitors(ranged from 0.0001 to 50 μmol/L) were performed to further characterize the inhibitory potency of apigenin and kaempferol. The IC50 value(the concentration that inhibits 50% of the transporter function) of each compound was then calculated by the nonlinear regression model of Graphpad Prism 6.0 software.RESULTS: Our data indicated that apigenin could potently inhibit the uptake of estrone-3-sulfate(ES) mediated by the HEK-293 cells expressing OAT2, OAT3 and OAT4 as well as the L-ergothioneine uptake via OCTN1-expressing HEK-293 cells. Among these transporters, the most prominent inhibition of apigenin was observed in the case of OAT3. Kaempferol showed significant inhibitory effects on the uptake of ES mediated through OAT2 and OAT3. Impaired L-ergothioneine uptake due to the presence of kaempferol was also observed in OCTN1-expressing HEK-293 cells. Similar to apigenin, kaempferol showed the most potent inhibitory effect on OAT3 as well. To further assess the inhibitory potencies of these two compounds on the uptake of ES mediated by OAT3-expressing HEK-293 cells, their IC50 values were then determined. Both chemicals showed pronounced inhibitory potencies on OAT3 with the IC50 values of 1.7 ± 0.1 and 1.0 ± 0.1 μmol/L(P < 0.01) for apigenin and kaempferol, respectively. CONCLUSION: Both apigenin and kaempferol are potent inhibitors of OAT3; precautions will be necessary when co-administrating them with drugs that are substrates of OAT3.

Selective transport of Ag(Ⅰ) ion across a bulk liquid and polymer membranes incorporated with di-N-benzylated O_3N_2 donor macrocycles

The selective bulk liquid membrane and polymer membrane transports of Ag（Ⅰ） from an aqueous solution containing seven metal cations,Co（Ⅱ）,Ni（Ⅱ）,Cu（Ⅱ）,Zn（Ⅱ）,Ag（Ⅰ）,Cd（Ⅱ） and Pb（Ⅱ）,was studied.The source phases contained equimolar concentrations of the above-mentioned cations,with the source and receiving phases being buffered at pH 5.0 and 3.0,respectively. Ag（Ⅰ） ion transport occurred with a good efficiency from the aqueous source phases across the bulk liquid membrane and polymer membrane（derived from cellulose triacetate） containing ligand 1 as the ionophores,into the aqueous receiving phases.Clear transport selectivity for Ag（Ⅰ） was observed using ligand 1.There was no selectivity for the cations using ligand 2 in the both bulk liquid membrane and polymer membrane transports.

Effects of Functionalized Silica Nanoparticles on Characteristics of Nanocomposites PES Cation Exchange Membranes

Nanocomposite cation exchange membranes（CEMs） were prepared by adding various loadings of functionalized silica nanoparticles to the sulfonated polyethersulfone（s PES） polymeric matrix. The silica nanoparticles were functionalized by mercaptopropyl（F1, IEC=0）, propylsulfonic acid（F2, IEC= 2.71）, and sulfonic acid（F3, IEC=2.84）. The properties of prepared membranes were investigated by varying the loadings of functionalized silica nanoparticles. Applying functionalized nanoparticles provides additional ion exchange groups and enhances water contents as well as conductivities and permselectivities of the membranes. The maximum IEC of 1.9 meq.g^-1 was obtained for the membrane having 3 wt% F3 nanoparticles and the maximum conductivity of 0.237 S·cm^-1 was achieved for the membrane having 2 wt% F3 nanoparticles, which were 19.6% and 64% higher than the corresponding values for s PES membrane, respectively. The excellent properties of the nanocomposite cation-exchange membranes make them appropriate candidates for electrodialysis and desalination processes.

A New Adaptive EDCA Approach to QoS of Wireless Communications

Under the background of intelligent transportation application, QoS for various services is different in wireless com-munication. Based on the MAC layer protocol, this paper analyzes the QoS in IEEE 802.11 MAC protocol framework, and proposes a new design of a Differentiation Enhanced Adaptive EDCA (enhanced distribution channel access) approach. The proposed approach adjusts the window zooming dynamically according to the collision rate in sending data frames, makes random offset, and further distinguishes the competition parameters of the data frames that have the same priority, so as to reduce the conflict among the data frames, and improve the channel utilization. Experiments with different service cases were conducted. The simulation results show that: comparing with the conventional EDCA method, the proposed approach can ensure that high priority services are sent with priority, and the overall QoS is highly improved.

基于OCT2、MRP2探讨加味生脉饮对Lewis肺癌小鼠顺铂化疗的增效减毒机制

【目的】观察加味生脉饮对顺铂化疗Lewis肺癌小鼠有机阳离子转运体2(OCT2)、多药耐药相关蛋白2(MRP2)的影响,探讨其对Lewis肺癌小鼠顺铂化疗的增效减毒机制。【方法】采用腋窝皮下接种Lewis肺癌细胞(LLC)构建肺癌移植瘤小鼠模型,造模成功后随机分为对照组、顺铂组、联合组(顺铂联合加味生脉饮)和生脉饮组,每组7只小鼠,给药14 d。观察4组小鼠一般状态、肿瘤生长情况,肿瘤、肾脏组织病理学以及血清尿素氮(BUN)、肌酐(Cr)浓度。通过免疫组织化学染色(IHC)和Western Blot的方法检测OCT2、MRP2蛋白表达情况,并使用高效液相色谱串联质谱(HPLC-MS/MS)法测定肾脏和肿瘤组织中顺铂含量。【结果】(1)给药结束后,各组小鼠体质量均有下降,顺铂组下降幅度最大,顺铂组体质量变化显著高于联合组、生脉饮组(P<0.05),生脉饮组和联合组小鼠一般状态均优于对照组和顺铂组。(2)干预结束时,顺铂组肿瘤体积和质量小于生脉饮组和对照组,联合组肿瘤体积和质量显著小于顺铂组(P<0.05)。(3)组织病理学结果显示:生脉饮组、对照组肿瘤细胞结构清晰,细胞形态正常;顺铂组与联合组可见肿瘤细胞坏死,肿瘤细胞边缘模糊,联合组肿瘤细胞坏死面积更大。生脉饮组、对照组肾脏细胞形态正常;联合组肾脏细胞损伤较轻,无明显病变;顺铂组肾组织明显病变,肾小管上皮细胞边缘模糊。(4)顺铂组小鼠血清BUN、Cr水平显著高于其他3组(P<0.05)。(5)顺铂组肾脏组织OCT2表达相比对照组显著增加,联合组OCT2表达相比顺铂组显著降低(均P<0.05);顺铂组肿瘤组织MRP2表达相比对照组显著增加,联合组MRP2表达相比顺铂组显著降低(均P<0.05)。(6)联合组肿瘤组织中顺铂含量显著高于顺铂组,联合组肾脏组织中顺铂含量显著低于顺铂组(均P<0.05)。【结论】OCT2、MRP2在顺铂肾脏毒性与耐药性中起重要的调控作用,加味生脉饮可能通过抑制肾脏中OCT2与肿瘤细胞中MRP2的蛋白表达,降低了顺铂治疗的肾脏毒性,提高了顺铂的抗肿瘤效果。

面向多曲线的通用高性能ECC处理器设计

该文针对广泛应用的TLS1.3协议,提出了一种高性能的椭圆曲线密码处理器.该处理器支持TLS1.3协议中定义的两类素数域椭圆曲线的通用模数.通过对高基蒙哥马利算法的改进,提出了一种支持521 bit及以下位宽的模乘运算单元,并提出了一种双模乘单元并行结构的标量乘法器.基于该结构在两类椭圆曲线下设计了雅阁比坐标系下并行的点运算时序排布,使模乘单元的利用率在不同点运算情况下达到100%,95.4%和86.5%.与现有设计相比,本文中标量乘法运算消耗的周期更少,运算单元利用率更高,在相似的时间面积乘积前提下,具有更强的通用性和可配置性的优势.在TSMC 55 nm CMOS工艺下达到454 MHz的时钟频率,等效逻辑门数851k,Secp256r1曲线的标量乘运算速度为31230 times/s.

不同pH/离子强度时Cu/Cd复合污染土壤解吸和迁移特征

重金属污染土壤在用固化/稳定化技术修复后,若外部环境发生变化,失去活性的重金属是否再次释放并在土壤中迁移,造成污染风险,是一个值得探讨的重要科学问题。为揭示不同化学因素对污染土壤中重金属活化及迁移过程的影响,通过室内土柱实验,研究了不同离子强度、pH及阳离子类型(Ca^(2+)、Na+)下Cu^(2+)、Cd^(2+)在土壤中的解吸及迁移行为。结果表明:总体而言,离子强度增大,Cu^(2+)、Cd^(2+)淋出浓度峰值也随之增大;此外,在CaCl2淋溶阶段,0.005、0.01、0.05、0.1 mol·L^(–1)CaCl_(2)时,Cu^(2+)、Cd^(2+)解吸量依次增加,且Cd^(2+)的解吸量高于Cu^(2+),而0.5 mol·L^(–1)CaCl_(2)时抑制了Cd^(2+)的解吸,且Cu^(2+)的解吸量高于Cd^(2+)。pH减小时,Cu^(2+)、Cd^(2+)解吸量增大,即偏酸性的环境有利于Cu^(2+)、Cd^(2+)的解吸;但从Cu^(2+)、Cd^(2+)浓度峰值来看,pH为3时的Cu^(2+)、Cd^(2+)浓度峰值反而小于pH为4、5时。Ca^(2+)较Na+更有利于Cu^(2+)、Cd^(2+)的解吸,但在0.005 mol·L^(–1)时,NaCl溶液更有利于Cu^(2+)的解吸,并且去离子水淋溶阶段Cu^(2+)浓度要高于CaCl2淋溶阶段;此外,离子强度为0.005、0.05和0.5 mol·L^(–1)NaCl的三种情况下均出现了土壤颗粒的出流,且0.05和0.5 mol·L^(-1)NaCl时,存在流速下降的现象。

醋柴胡多糖对拉米夫定体外抗乙型肝炎病毒的增效作用研究

目的:考察醋柴胡多糖对拉米夫定抗乙型肝炎病毒(HBV)的增效作用,并初步探讨其作用机制。方法:将不同浓度的醋柴胡多糖、拉米夫定及二者联合作用于人肝癌细胞HepG2.2.15,同时设立对照组,孵育48 h,酶联免疫吸附试验试剂盒检测细胞上清液中乙型肝炎表面抗原(HBsAg)、乙型肝炎e抗原(HBeAg)分泌量,荧光探针定量聚合酶链式反应(PCR)检测细胞HBV脱氧核糖核酸(DNA)表达量,金(正均)氏公式定量分析醋柴胡多糖的增效作用。采用高效液相色谱法测定细胞内拉米夫定含量;Western blot法测定有机阳离子转运蛋白(OCT)1、OCT2、P糖蛋白(P-gp)和多药耐药蛋白2(MRP2)的表达量。结果:与拉米夫定单用组相比,醋柴胡多糖增加拉米夫定对HBsAg分泌的抑制作用,表现为相加作用、对HBeAg作用表现为协同增强,Q值达6.55、对HBV-DNA抑制作用表现为相加。醋柴胡多糖低剂量组、醋柴胡多糖低中剂量组、醋柴胡多糖低高剂量组可显著促进拉米夫定的摄取;醋柴胡多糖高剂量联用组可显著降低P-gp的表达;醋柴胡多糖单用及联用组均可显著提高OCT1的表达。结论:醋柴胡多糖可通过增加拉米夫定的摄取发挥协同抗HBV作用,其作用机制可能P-gp、OCT1有关。

OCTN2与前列腺癌细胞对奥沙利铂化疗敏感性的相关性

目的研究新型有机阳离子转运体2(OCTN2)与前列腺癌细胞对奥沙利铂化疗敏感性的相关性。方法收集行前列腺癌根治术患者的前列腺癌组织标本,采用免疫组化法检查组织中的OCTN2蛋白表达;培养标本原代细胞得到前列腺癌细胞株。采用电感耦合等离子体质谱法检测癌细胞对低浓度(0.1μmol/L)奥沙利铂的摄取量,采用Real time PCR及Western blot法检测癌细胞中OCTN2 mRNA及蛋白的表达水平;选择OCTN2蛋白表达最高及最低的前列腺癌细胞株,采用三磷酸腺苷肿瘤药物敏感性检测法(ATP-TCA)计算奥沙利铂对癌细胞的半数抑制浓度(IC50);采用MTT法检测血药峰浓度奥沙利铂(50μmol/L)对前列腺癌细胞的抑制率。采用Spearman法分析前列腺癌细胞对奥沙利铂摄取量与奥沙利铂对前列腺癌细胞抑制率及OCTN2 mRNA表达的相关性。结果OCTN2定位于癌细胞膜;癌细胞对奥沙利铂的摄取量为0.283±0.264(n=12);不同癌细胞中OCTN2 mRNA和蛋白表达差异明显;OCTN2高表达的癌细胞对奥沙利铂的敏感性(IC50为4.61μmol/L)高于OCTN2低表达的癌细胞(IC50为26.23μmol/L)。奥沙利铂对癌细胞的抑制率为(25.4±10.8)%(n=12)。前列腺癌细胞对奥沙利铂的摄取量与奥沙利铂对前列腺癌细胞的增殖抑制率及前列腺癌细胞中OCTN2 mRNA表达水平三者间存在相关性(P<0.05)。结论OCTN2高表达可能促进前列腺癌细胞对奥沙利铂的摄取,其表达水平可作为预测前列腺癌细胞对奥沙利铂化疗敏感性的参考依据之一。

酸性条件下二氧化碳高效电还原策略

二氧化碳电还原技术可以将可再生电能与温室气体二氧化碳转化为高价值燃料和化学品.选择性、能量转化效率、碳利用效率和可持续性是评价二氧化碳电还原技术是否具有工业应用前景的主要指标.在碱性或中性电解液中进行二氧化碳电还原,由于部分二氧化碳在阴极转化为碳酸盐,导致碳利用效率降低.碱性电解液和中性电解液还分别存在电解液再生过程耗能巨大和溶液电阻较高等问题.这些因素导致使用碱性和中性电解液的二氧化碳电还原技术能量转化效率低下.最近,酸性条件下二氧化碳电还原技术有望提高碳利用效率和能量利用效率,成为研究热点.然而,在酸性条件下提升二氧化碳还原选择性具有挑战.前期研究已发展了多种策略以抑制酸性条件下的氢离子还原反应并促进二氧化碳还原反应,但研究者对于酸性条件下的阳离子效应以及局域pH效应等基础科学问题认识尚不一致.此外,气体扩散电极内的碳酸氢盐盐析问题仍限制着酸性条件下二氧化碳还原电解系统的可持续性.因此,亟需对促进酸性条件下二氧化碳电还原的不同策略及可能机制进行总结,并探讨进一步提升电解系统可持续性的潜在路径.本文首先概述了酸性条件下二氧化碳电还原技术的提出及发展历程,对比了碱性、中性和酸性电解液中进行二氧化碳电还原的优势和劣势.着重从传质过程和电极反应两方面对已报道的酸性条件下二氧化碳电还原技术进行归纳总结.探讨了传质过程中二氧化碳还原半反应引起的局域高pH对氢离子还原反应的抑制作用,碱金属离子对于氢离子电迁移过程的抑制作用,以及抑制氢离子扩散过程的基本策略.对于电极反应,探讨了催化位点本征活性的调控、碱金属离子调控界面电场对于二氧化碳还原动力学的影响,以及碱金属离子与反应中间体的直接配位作用.然后,概述了近期无金属离子酸性电解液中二氧化碳电还原技术的进展,该技术旨在提升二氧化碳电还原性能的可持续性.介绍了酸性条件二氧化碳电还原过程的理论模拟方法,提出了将原子尺度的密度泛函理论模拟与电极微反应动力学模拟及介观、宏观尺度传质过程的有限元分析相结合的研究思路.最后,总结了促进酸性条件二氧化碳电还原的不同策略,展望了电极微环境检测、模拟和调控的可能途径,以及进一步提升酸性条件二氧化碳电还原稳定性及降低成本的策略.

离子交换行为对溶质运移影响作用的实验研究

为研究河流阶地和洪积扇这类典型水力沉积单元污染物运移规律,搭建了大尺寸室内渗流槽开展溶质运移实验。通过点投放NaNO_(3)溶液模拟点源污染物在水力沉积物中的运移过程,测定不同位置主要离子成分随时间的变化,用于分析离子交换过程对于溶质运移的影响及溶质迁移规律。结果表明:在运移过程中,NO_(3)^(2-)属于保守性离子,穿透曲线呈尖瘦形,Na^(+)受阳离子交替吸附作用的显著影响,峰形陡升缓降;阳离子交替吸附作用降低了Na^(+)的弥散度,离子交替吸附作用对弥散度的影响随着运移距离的增加愈加明显;运移初期高浓度Na+在砂层中能交换出相当数量的Ca^(2+),Mg^(2+),K^(+)等离子;运移后期阳离子交替吸附反应方向改变,沉积砂层吸附水中的Ca^(2+),Mg^(2+),K^(+),穿透曲线存在3种阳离子低于背景值的情况;交替吸附作用使得对流-弥散作用下的Na^(+)质量浓度穿透曲线形状更加宽缓,“拖尾”现象更为明显;渗流砂槽内不同区域的水化学类型在空间上产生了差异性。研究成果对于开展水力沉积单元地下水污染防治具有一定指导意义。

植物抗旱和耐重金属基因工程研究进展

干旱和重金属污染严重影响植物的生长发育.植物耐逆相关基因的克隆和功能鉴定研究,为通过基因工程途径提高植物的抗逆性奠定了理论基础.水分亏缺、高盐、低温和重金属胁迫都能诱导LEA(late embryogenesis abundant protein)基因的表达.转基因研究表明,LEA蛋白具有抗旱保护作用、离子结合特性以及抗氧化活性;水孔蛋白存在于细胞膜和液泡膜上,在细胞乃至整个植物体水分吸收和运输过程中发挥重要作用.干旱和盐胁迫促进水孔蛋白基因转录物的积累.过量表达水孔蛋白可增强水分吸收和运输,提高植物的抗旱能力.金属转运蛋白参与重金属离子的吸收、运输和累积等过程.这些蛋白基因在改良草坪草植物的抗旱节水和耐重金属能力等方面具有潜在的应用价值.