跨膜Ca~(2+)梯度通过磷脂酰胆碱调节肌质网Ca~(2+)-ATP酶

将纯化的肌质网Ca~(2+)-ATP酶重组在具有或不具有跨膜Ca~(2+)梯度的脂质体上,研究了磷脂(特别是磷脂酰胆碱)在跨膜Ca~(2+)梯度对肌质网Ca~(2+)-ATP酶功能调节中的作用。结果表明:(1)高浓度的(Ca~(2+)对与不同磷脂保温的去脂Ca~(2+)-ATP酶都产生抑制,但对与PC保温的Ca~(2+)-ATP酶抑制最大。(2)当存在一个正向跨膜Ca~(2+)梯度时(酶活性中心一侧Ca~(2+)浓度较低,类似生理条件),它只对与中性磷脂PC:PE重组的Ca~(2+)-ATP酶产生抑制,且PC:PE(摩尔比)为1:1时,抑制程度最大。如以酸性磷脂PS或PG替代PC则均无明显抑制。(3)比较不同脂肪酸侧链的PC的作用表明,当DOPC或DPPC存在时均有明显抑制作用,而DMPC则几乎不表现抑制作用。(4)若Ca~(2+)梯度逆转,则无论是与酸性磷脂或中性磷脂重组的肌质网Ca~(2+)-ATP酶都会被抑制。     

改进碳化氨水浓度分析的迠议

1.碳化氨水与纯氨水比重是不同的。碳化氨水以碳铵为主体,比重随所含CO_2及NH_3的多少而增减。当NH_3含量高而CO_2低时,比重小于1,增加CO_2的含量时,比重可大于1。纯氨水的比重皆小于1,它随着NH_3含量的增加而有规律的递减。碳化氨水则不同于纯氨水单纯受NH_3的影响有规律可循,它受到CO_2及NH_2双重影响。因此,将碳化氨水的滴度换算成百分含量时必须用比重计测其比重,或者由CO_2含量与比重差别进行计算。     

光度法测定硝酸镍中钴

曾报道用亚硝基R盐酸测定大量镍中微量钴。对于样品中钴含量高过3％,其测定结果不理想。我们在文献[2]基础上,在浓氨水、过硫酸铵存在下,使镍、钴分别形成Ni(NH_3)_6~(2+)、Co(NH_3)_6~(3+),然后用浓硝酸酸化,使Ni(NH_3)_6~(2+)分解,Co(NH_3)_6~(3+)不分解,在500nm处测定吸光度,此时镍不干扰测定。钴含量在0～14mg/25ml符合比耳定律。用于实际样品分析,结果满意。     

不同形态的氧氟沙星在凹凸棒土上的吸附特征

通过控制反应体系的pH值,探究了阳离子、兼性和阴离子形态的氧氟沙星(OFL,3种形态分别记为OFL~+,OFL~±和OFL~-)在凹凸棒土(ATP)上的吸附特征.实验结果表明,OFL~+主要通过与ATP表面的Ca~(2+),Mg~(2+)进行阳离子交换吸附于ATP上,当其吸附量较高时,会存在少量的氢键;OFL~±和OFL~-可与ATP表面的铁氧化物、铝氧化物进行表面络合,也可与溶液中从ATP中溶解出的Ca~(2+)和Mg~(2+)形成络合物,再通过静电作用吸附于ATP上.在中性至微碱性(pH=7.10~7.70)条件下,由于Ca的电负性小于Mg,[Ca~(2+)-OFL]+不能稳定地存在于溶液中,使得OFL±与Ca~(2+)进行阳离子交换而与Mg~(2+)形成络合物,再通过静电作用吸附于ATP上.当OFL主要以OFL~-形态存在于溶液中时(p H=9.00~10.00),Ca~(2+)和Mg~(2+)均可与OFL~-形成络合物,再通过静电作用吸附于ATP上.     

Mg-PV-CTMAB光度法测定水中Mg

在pH11.05的氨性缓冲溶液中,以乙醇为增敏剂,聚乙烯醇作稳定剂,研究了Mg-PV-CTMAB体系的显色反应。配合物在波长670～680nm处有最大吸收;摩尔吸光系数为7.4×10~4L·mol~(-1)·cm~(-1);Mg;PV=1:2;0～10μg Mg/25ml符合比尔定律。本法具有较高的灵敏度和较好的重现性,用草酸铵掩蔽Ca~(2+)后,可作天然水中Mg的测定。共存离子影响:对8μg Mg的回收率在93～115％时,允许50μg Cr~(6+);20μgV~(5+),Mo~(6+)、Mn~(2+)、Cu~(2+);10μg Ca~(2+)Sn~(4+)、La~(3+)、Ba~(2+)、Ti~(4+)、Pb~(2+);5μg Fe~(3+)、Al~(3+)、Co~(2+)、Ni~(2+)、Zn~(2+)存在。天然水中,在取样量内,上述离子量除Ca~(2+)外均达不到,而Ca~(2+)的负干扰,用0.5ml草酸铵(1％)至少可以掩蔽100μg Ca~(2+)。     

电泳沉积技术制备海藻酸钙-纳米铜复合抗菌膜

通过调节电解液中纳米铜的含量,经电泳沉积得到海藻酸钙-纳米铜新型抗菌纳米复合膜(Ca~(2+)-Alg-Cu)。以扫描电子显微镜(SEM)、能谱仪(EDS)和傅里叶变换红外光谱(FT-IR)表征了Ca~(2+)-Alg-Cu的结构。使用稀释涂板法研究了Ca~(2+)-Alg-Cu对大肠杆菌(E. coli.)、金黄色葡萄球菌(S. aureus)和绿脓杆菌(P. aeruginosa)的抗菌性能。使用小鼠成纤维细胞(L929)与Ca~(2+)-Alg-Cu共培养表征了其细胞相容性。结果表明,Ca~(2+)-Alg-Cu能够破坏细菌形貌,高效杀死上述3种细菌;Ca~(2+)-Alg-Cu对细胞存活率的影响主要依赖电解液中纳米铜的质量浓度,当纳米铜的质量浓度小于0.4 mg/mL时,细胞存活率大于80%,能够兼顾高效的杀菌活性和良好的生物相容性。     

CPP杨梅型树脂的交换性能

本文研究了Zn~(2+)、Cd~(2+)、Hg~(2+)、Ca~(2+)、Mg~(2+)、Pb~(2+),Co~(2+)、Ni~(2+)、Cu~(2+)等二价金属离子在CPP杨梅型树脂上的交换过程。CPP—Na/Me~(2+)的交换容量一般在3meq/g-R以上;动态交换20分钟以后,除Hg~(2+)离子外,可达2.3—3.2meq/g—R。(CPP)_2—Me的稳定性顺序测得为:Cu~(2+)>Zn~(2+)>Co~(2+)>Ni~(2+)>Cd~(2+)>Hg~(2+)>Mg~(2+)>Ca~(2+)。在不同pH溶液中,二价全属离子在溶液相和树脂相之间的分配系数表明,pH<2.5时(CPP)_2—Me容易被酸再生,并且当两种或两种以上的金属离子在给定的pH溶液中分配系数差足够大时,有希望获得淋洗分离。     

改性Cu-Mn/SAPO-34催化剂在SCR脱硝反应中的特性研究

采用浸渍法制备了系列铜锰复合氧化物分子筛催化剂(Cu-Mn/SAPO-34),在固定床反应器上考察不同Cu/Mn质量比对分子筛催化剂选择催化还原NO的影响,利用XRD、NH_3-TPD、H_2-TPR、XPS等手段对催化剂进行了表征分析。结果表明,双金属改性的Cu-Mn/SAPO-34催化剂在NH_3-SCR反应中表现出较为优异的催化活性,具有较宽的活性温度窗口。当Cu/Mn质量比为1∶4时,催化剂具有最宽的活性温度窗口,NO_x转化率在250℃已达到85.39%,在300-400℃转化率均达到96%以上,450℃时仍能达到90%。铜和锰物种高度分散于催化剂表面,未改变SAPO-34的晶体结构,且构成协同作用。Cu-Mn共同负载促进了Cu~(2+)向Cu~+的转变,增加了高价态Mn~(4+)和Mn~(3+)的比例,有利于提高低温活性,促进催化反应的进行。Cu-Mn/SAPO-34/1∶4具备丰富的酸性位、良好的氧化还原性能和抗SO_2/H_2O性能,该配比有助于催化剂的催化活性和稳定性的提高。     

WO_3改性CeO_2-TiO_2催化剂的低温NH_3-NO/NO_2 SCR活性和机理研究（英文）

在铈钛基NH_3-SCR催化材料中,改性元素对催化材料的酸性位和氧化还原性能的影响较大。本文采用过量浸渍法分别制备了CeO_2-TiO_2(CeTi)和CeO_2/WO_3-TiO_2(CeWTi)催化剂,研究了CeWTi催化材料结构、酸性位及氧化还原性能对NH_3-NO/NO_2 SCR反应性能的影响.结果发现,CeTi和CeWTi样品均有较优异的NH_3-NO/NO_2 SCR催化性能,后者略高.WO_3的加入增加了催化材料的表面酸性,对其氧化还原性能影响不大.通过对反应中间物种NH_4NO_3的研究,发现NH_4NO_3的分解主要与氧化还原性能相关,而NO还原NH_4NO_3的反应需要氧化还原能力和酸性位共同作用,即在氧化还原性能差异不大的条件下,酸性对该反应起到重要作用.而该反应也是NH_3-NO/NO_2 SCR的限速步骤,这是CeWTi催化材料活性高于CeTi催化材料的原因.同时,为了获得NH_3-NO/NO_2 SCR反应的高活性,NO_2:NO比例宜为1:1.然而现实情况中,预氧化催化材料的氧化活性、NO_x浓度、温度等变量使得准确控制NO_2的比例较难,因此,深入了解NO_2浓度对NH_3–NO/NO_2 SCR反应的影响至关重要.本文探讨NO_2:NO的比例、O_2浓度等对NH_3-NO/NO_2 SCR反应性能的影响;并研究了不同NO_2含量条件下NH_3-NO/NO_2 SCR反应网络.通过分析CeWTi材料上NH_3-NO/NO_2 SCR反应网络可知,当NO与NO_2比例为1:1时,NH_3-SCR催化活性最高,并以快速SCR形式进行;当NO与NO_2比例为1:1消耗完全之后,剩余的NO或NO_2各自独立以标准或慢速SCR进行,不影响其本来的反应活性.催化材料的标准SCR、快速SCR和慢速SCR均取决于材料表面酸度和氧化还原性能,但快速SCR和慢速SCR对材料这两方面性能的要求相对较低.同时O_2并不参与快速和慢速SCR,而NO_2可以取代O_2作为SCR反应中主要的氧化剂,氧化Ce~(4+)为Ce~(3+),甚至比O_2和NO再氧化活性位的能力更强,保持催化材料的高催化活性.低温条件时,慢速SCR和快速SCR反应均在材料表面生成硝酸铵中间物种,但由于慢速SCR气氛中缺乏NO将硝酸铵还原,进而引发快速SCR反应,因此材料表面快速SCR的NO_x转化率要高于慢速SCR反应;高温条件下,由于硝酸铵容易热分解,导致硝酸铵的抑制效应不太明显.NH_4NO_3分解是NO_2含量升高后N2O的形成的主要途径     

基于联萘酚衍生物的荧光传感器对Ca~(2+)的选择性测定

设计了基于联萘酚衍生物(LZ)的高选择性的荧光化学传感器,分别采用荧光光谱和紫外-可见光谱法研究了其对Ca~(2+)的识别.结果显示,与其他金属离子,如Ag~+、Al ~(3+)、Bi ~(3+)、Cd~(2+)、Co~(3+)、Cr~(3+)、Cu~(2+)、Fe~(3+)、Hg~(2+)、K~+、Mg~(2+)、Mn~(2+)、Ni ~(2+)、Pb~(2+)、Zn~(2+)相比,探针LZ对Ca~(2+)呈现良好的选择性.并且该探针在486nm处的荧光强度与Ca~(2+)浓度在2~7μmol/L范围内呈现良好的线性关系,其回归系数为0.994,检测限为0.8μmol/L,多次测定的相对标准偏差为2%.     

Calcium Ion Coordinated Polyamide Nanofiltration Membrane for Ultrahigh Perm-selectivity Desalination

Improving the permeate flux but retaining the rejection of thin-film composite(TFC) polyamide nanofiltration(NF) membrane is a high requirement for desalination. In this work, a calcium ion(Ca²⁺) coordinated polyamide(PA) NF membrane was prepared by directly adding CaCl₂ to the piperazine(PIP) aqueous solution during the interfacial polymerization process. Due to the coordination interaction between Ca²⁺ and the amide bond in PA active layer, the number of hydrogen bonds in the PA active layer was reduced, causing in turn the decrease of physical cross-linking degree. As a consequence, the pore of the PA active layer was enlarged, prominently enhancing the water permeance of NF membrane. With the increase of CaCl₂ concentration, the pure water flux of TFC NF increased significantly while the rejection of Na₂SO₄ decreased sightly. Compared with TFC NF membrane prepared without CaCl₂, the permeate flux of the Ca²⁺ coordinated polyamide NF membrane prepared under optimal conditions was increased by 3-4 folds with Na₂SO₄ rejection of 95.26%. Meanwhile, such a Ca²⁺ coordinated PA NF membrane showed a better SO₄^2-/Cl^- selectivity.     

辛烷基酚聚氧乙烯醚反相微乳体系的相行为及纳米复合碳酸盐的制备

绘制了一系列辛烷基酚聚氧乙烯醚(OP-10)+正辛醇+环己烷+水(或CaCl₂水溶液)拟三元体系相图,分别研究了助表面活性剂正辛醇的添加比例和CaCl₂水溶液的浓度对微乳区域的影响,发现在OP-10+正辛醇+环己烷+水拟三元体系相图中,随着正辛醇/OP-10的质量比逐渐增大,微乳区的面积逐渐增大,当正辛醇/OP-10质量比为1:2.5时微乳区的面积最大,之后微乳区面积随着其质量比的增大而减小,表明适量地加入助表面活性剂正辛醇有利于微乳区的形成;但过多地增加正辛醇的量反而不利于微乳相的形成。 确定正辛醇/OP-10的质量比为1:2.5,改变CaCl₂的浓度,发现OP-10+正辛醇+环己烷+CaCl₂水溶液拟三元体系相图中,CaCl₂浓度为0.1 mol/L时微乳区面积最大。分别配制总浓度为0.1 mol/L的5种不同摩尔比的Ca²⁺/Ba²⁺微乳液,并与等摩尔的碳酸钠水溶液反应制备共沉淀碳酸盐,使用扫描电子显微镜(SEM)对所制备样品进行表征分析,发现当微乳液为钙离子盐时,主要形成大的立方形颗粒;掺入钡离子,Ca²⁺和Ba²⁺摩尔比为3:1、1:1和1:3时,形成的沉淀分别为四棱锥形、球形和玉米棒形;当微乳液为钡离子盐时,沉淀主要为不规则多面体。     

The effect of the amount of ammonia on the Cu~0/Cu~+ ratio of Cu/SiO_2 catalyst for the hydrogenation of dimethyl oxalate to ethylene glycol

The effect of the amount of precipitant ammonia on the Cu0/Cu＋ratio of Cu/Si O2 prepared by the deposition–precipitation method is investigated. Species at different preparation stages, resulted from the amount of ammonia used, are identified by the XRD and FTIR techniques. Chrysocolla together with either copper nitrate hydroxide or copper hydroxide coexist in the uncalcined catalysts. Upon calcination, the latter two species are converted to Cu O particles while chrysocolla remains. Following reduction, Cu O is transformed to metallic Cu and chrysocolla is converted to Cu2 O. The value of Cu0/Cu＋ratio can be evaluated using the peak areas in their TPR profiles. Hydrogenation of dimethyl oxalate（DMO） to ethylene glycol（EG） shows that the selectivity of EG depends on the Cu0/Cu＋ratio. Catalyst prepared with the addition of ammonia solution at n（NH3）/n（Cu2＋） = 0.9 for precipitation–deposition gains a more suitable Cu0/Cu＋ratio upon reduction and thus has a higher selectivity for EG.     

Ca2+离子掺杂对γ-Ce2S3合成温度及热稳定性的影响

以CeCl₃·7H₂O、CaCl₂·2H₂O和C₂H₂O₄·2H₂O为原料,在制备钙铈氧化物前驱体基础上,再以Ar气为载气、CS₂为硫源对钙铈氧化物前驱体进行硫化合成Ca²⁺掺杂的γ-Ce₂S₃色料。 通过X射线衍射(XRD)、紫外-可见漫反射光谱(UV-Vis)及差热-热重分析(TG-DTA)等技术手段表征了色料的结构和性能。 结果表明,Ca²⁺掺杂能够明显降低γ-Ce₂S₃的合成温度,当n(Ca²⁺):n(Ce³⁺)≥0.16时,在900 ℃硫化150 min即可获得纯相的γ-Ce₂S₃,与不掺杂时合成γ-Ce₂S₃的温度相比降低了300 ℃左右。 同时,Ca²⁺掺杂能够提升γ-Ce₂S₃的抗氧化能力,当n(Ca²⁺):n(Ce³⁺)=0.64时,氧化放热峰的温度由不掺杂时的490.6 ℃提高至541.0 ℃。     

Calcium as a factor influencing the response of Serratia marcescens strain SMG40 to growth surfaces

Serratia marcescens, like several other bacterial species, is able to adhere to and swarm on growth surfaces, and this property is correlated with changes in the structures and functions of cells which pass from broth to solid media. In the case of the pigmented form of S. marcescens strain SMG40, the response to the contact with agar was influenced by the presence of Ca²⁺ ions as follows. (1) In the swimming phase, i.e. in soft 0.35% agar media, expansion was not modified upon the addition of 5–35 mM Ca²⁺ ions. (2) On growth surfaces inducing swarming, i.e. on media containing 0.75% agar (low agar), Ca²⁺ ions used at low concentrations (e.g. 0.5mM) enhanced both growth and expansion. (3) At higher concentrations (from 3 mM). the Ca²⁺ ions inhibited expansion but not growth. Correlatively, the cell density per unit of the surface occupied by bacteria inhibited from swarming was increased: expansion rates of swarms at successive periods were lower and showed less fluctuation than normal. In a non-pigmented but still good swarmer mutant, found to be more sensitive to calcium, expansion was reduced to 50% with at most 0.5 mM Ca²⁺ ions. One-step revenants recovered pigmentation and the initial response to Ca²⁺ ions described in points (2) and (3) above. The inhibitory activity of CaCl₂ was partly antagonized by NaCl. Other properties implied in the interactions of Serratia cells with agar, i.e. pigmentation, adherence to solid surfaces and the production of an extracellular surfactant were not inhibited by Ca²⁺ ions.     

Molecular Dynamics Simulation for the Impact of External Electric Fields on CaCl2 Aqueous Solution

Non-equilibrium molecular dynamics(MD) simulations were performed according to the electronic anti-fouling technology, and some structural parameters and dynamic parameters of CaCl₂ aqueous solution were taken as indicators to compare the different effect on the anti-fouling performance by applying different electric fields. The results show that electric fields can effectively decrease the viscosity of CaCl₂ aqueous solution and enhance the ionic activity by enlarging the self-diffusion coefficient. In addition, with the same electric field strength, the electrostatic field is more effective at decreasing the viscosity of CaCl₂ aqueous solution and increasing the self-diffusion coefficient of water molecules, while the alternating electric field is more effective at increasing the self-diffusion coefficient of Ca²⁺. Furthermore, an alternating electric field with different frequencies was applied; the results show that an 800 kHz frequency is most effective to decrease the viscosity, and a 700 kHz frequency is most effective to enhance the self-diffusion coefficient of water molecule. Otherwise, 400 kHz is most effective to enhance the self-diffusion coefficient of Ca²⁺. Additionally, by studying the change of structure parameters, it was concluded that an external electric field can enhance the hydration between Ca²⁺ and coordinated water molecules, and the alterna- ting electric field is more effective in this respect.     

氧化镥中杂质对铈掺杂硅酸镥多晶粉体光谱性质影响

氧化镥中杂质元素对其分离制备工艺、生产成本及镥基硅酸盐闪烁晶体的性能有很大影响,但杂质元素对晶体的性质影响研究较为有限,有待进一步完善。 本文采用高温固相法制备了Lu₂O₃分离过程中关键杂质元素Yb³⁺和Ca²⁺共掺杂Lu₂SiO₅∶Ce多晶粉体,研究了Yb³⁺或Ca²⁺含量对多晶粉体光谱性质的影响,结果表明:Yb³⁺或Ca²⁺共掺并未改变发射光谱的形状和位置,随着杂质元素摩尔分数的增加,光谱强度和荧光寿命逐渐降低。     

NH3-SCR反应过程中NH3和NOx在Cu/SAPO-34分子筛催化剂上的吸附特性和作用

通过离子交换法制得Cu/SAPO-34菱沸石分子筛催化剂, 同时研究了NH₃和NO_x (NO和NO₂)在该催化剂上的吸附位、吸附强度、吸附量和吸附速率, 得到了不同反应气氛在Cu/SAPO-34 上的吸附性能及其在NH₃选择性催化还原(NH₃-SCR)反应中的作用. 研究采用瞬态实验、程序升温脱附(TPD)和漫反射傅里叶变换红外光谱(DRIFTS)等方法进行表征实验. 瞬态实验结果表明NH₃是吸附性气体. 程序升温脱附实验和红外漫反射实验结果表明NH₃可以吸附在布朗斯特和路易斯酸性位上形成不同的NH₃物种, 它们显示不同的SCR活性. NH₃在Cu²⁺上的吸附速率最快, 且键强最强. NO_x可以氧化并以硝酸盐/亚硝酸盐的形式吸附在Cu物种上. 最后, 本文讨论了NH₃选择性催化还原反应过程中在Cu物种上的中间物种并推测反应机理.     

Ammonia sorption by Dawson acid studied by IR spectroscopy and microbalance

Using in-situ microbalance and infrared spectroscopy techniques the double ammonia proton complexation was traced. The results confirm the formation of N₂H₇⁺ dimer in solid Dawson acid H₆P₂W₁₈O₆₂, previously reported only for N₂H₇I and for (N₂H₇)₄SiW₁₂O₄₀. The formation of such dimers was evidenced by the microbalance results, the molar ratio of ammonia to proton was measured as 2:1 at 10.7 kPa and 298 K. The formation of NH₄⁺ monomer (band at 1410 cm⁻¹) and N₂H₇⁺ dimer (1460 cm⁻¹) was revealed by IR spectroscopy. Enthalpy of ammonia sorption on Dawson structure was calculated to be −127.9 kJ mol⁻¹, indicating the lower acid strength of Dawson-type compared to that of the Keggin-type heteropolyacids, like H₄SiW₁₂O₄₀.     

前驱体溶液pH值对V2O5-WO3/TiO2催化剂的低温NH3-SCR性能的影响

采用调节前驱体溶液pH值的方法制备了用于低温NH₃-SCR的V₂O₅-WO₃/TiO₂催化剂。通过XPS、Raman光谱、H₂-TPR、NH₃-TPD、NH₃-DRIFT、XRD及物理吸附等手段对催化剂进行了表征分析,并对其脱硝催化活性进行了测试。结果表明,前驱体溶液酸性的增强能够提高催化剂表面聚合态钒物种和V⁴⁺⁽³⁺⁾/V⁵⁺的比值以及表面酸性,增加活性位数量、降低反应的活化能、提高其脱硝催化性能。因此,通过提高前驱体溶液的酸性,有助于制备出脱硝活性较好的NH₃-SCR催化剂。