Maintenance of resting potential in anoxic guinea pig ventricular muscle: electrogenic sodium pumping

Anoxic ventricular muscle maintained a normal resting potenitial despite a large loss of potassium. The resting potential was separated into two components: one that depended on the potassium distribution, and one that depended on the activity of an electrogenic sodium pump.     

Cochlear function and sodium and potassium activated adenosine triphosphatase

The maintenance of the cation gradients between endolymph and perilymph in the cochlea requires the operation of a cation pump. An adenosine triphosphatase system activated by sodium and potassium is present in high activity in the cochlear membranes (tegmentum vasculosum and stria vascularis). The cochlear microphonic potential is inhibited by perilymphatic perfusion of ouabain and erythrophleine. Since the microphonic potential depends on the high concentration of potassium ions in the endolymph, our findings strongly suggest the operation of an adenosine triphosphatase cation pump system activated by sodium and potassium, in the generation of cochlear cation gradients.     

Structure,mechanism, and regulation of the Neurospora plasma membrane H+-ATPase

Proton pumps in the plasma membrane of plants and yeasts maintain the intracellular pH and membrane potential. To gain insight into the molecular mechanisms of proton pumping, we built an atomic homology model of the proton pump based on the 2.6 angstrom x-ray structure of the related Ca2+ pump from rabbit sarcoplasmic reticulum. The model, when fitted to an 8 angstrom map of the Neurospora proton pump determined by electron microscopy, reveals the likely path of the proton through the membrane and shows that the nucleotide-binding domain rotates by approximately 70 degrees to deliver adenosine triphosphate (ATP) to the phosphorylation site. A synthetic peptide corresponding to the carboxyl-terminal regulatory domain stimulates ATPase activity, suggesting a mechanism for proton transport regulation.     

Electrogenic sodium pump and high specific resistance in nerve cell bodies of the squid

An electrogenic sodium pump contributes to the membrane potential in squid nerve cell bodies, imparting a temperature dependence to the resting potential that is abolished by strophanthidin. The existence of a potential produced by the pump in the soma but not the axon is correlated with a higher membrane resistance in the soma. Thus, membranes from different parts of a neuron may have functionally significant differences in resistance.     

变频软启动控制方式在高位栈桥装车中的应用

针对吐哈油库低位置输油、高位置装车过程中存在的输油压力和油流不稳的问题,提出对输油泵采用变频加软启动的控制方式,通过PLC控制系统优化编程,将PID控制与开关量控制进行有机结合,并增设超压报警保护和紧急停泵保护.实践表明,变频加软启动的控制方式能有效保证吐哈油库输油泵的安全、平稳、高效运转,提高油库的经济效益.     

Synaptic activation of an electrogenic sodium pump

An identified molluscan interneuron mediates different cholinergic synaptic actions by increasing the conductance of its follower cells to different ions. We have now found that this interneuron also mediates a new class of synaptic actions which does not involve a conductance change but the activation of an electrogenic sodium pump. This synaptic action results in a prolonged inhibitory synaptic potential which is dependent on metabolism and is selectively blocked by cooling and ouabain. In cells which have this synaptic potential, part of the resting membrane potential is also maintained by an electrogenic sodium pump. The same transmitter, acetylcholine, can independently stimulate both a chloride ion conductance and a sodium pump mechanism in the same follower cell by acting on two different postsynaptic receptors.     

贵阳市污水源热泵应用的可行性及环境效益分析

介绍了污水源热泵技术的工艺流程,分析了贵阳市污水的基本分布和可利用情况,监测了污水的水温、水量以及主要环境污染指标,并对使用污水源热泵系统后污染物的潜在减排值进行了预测。结果表明,贵阳开发、利用污水热能的条件良好,市内污水完全可以满足污水源热泵的经济运转,具有明显的节能减排效益和环保效益。     

Effects of NaCl and Iso-Osmotic Polyethylene Glycol Stress on Na+/H+ Antiport Activity of Three Malus species with Different Salt Tolerance

Salt stress contains osmotic and ionic stress, while iso-osmotic polyethylene glycol (PEG) has only osmotic stress. This study aimed to compare the different effects on the activity of H+-ATPase, proton pump and Na+/H+ antiport in Malus seedlings between osmotic and ionic stress. Species of salt tolerant Malus zumi, middle salt tolerant Malus xiaojinensis and salt sensitive Malus baccata were used as experimental materials. Malus seedlings were treated with NaCl and iso-osmotic PEG stress. The activity of H⁺-ATPase, proton pump and Na⁺/H⁺ antiport of plasmolemma and tonoplast in Malus seedlings were obviously increased under salt stress, and those in salt-tolerant species increased more. Under the same NaCl concentration, the activity of H⁺-ATPase, proton pump and Na⁺/H⁺ antiport of plasmolemma and tonoplast in salt-tolerant species were all obviously higher than those in salt-sensitive one. Higher Na+/H+ antiport activity of plasmolemma and tonoplast in salt-tolerant species could help to extrude and compartmentalize sodium in roots under salt stress. The ascent rate of activity of H+-ATPase, proton pump and Na+/H⁺ antiport in Malus seedlings under the three salt concentration stress was all obviously higher than that under the iso-osmotic PEG stress. It indicated that the sodium ion effect had more stimulation on the activity of H+-ATPase, proton pump and Na+/H+ antiport in salt-tolerant species, and salt-tolerant species has higher capability of sodium extrusion and compartmentalization in roots and is therefore more salt tolerant.     

AcrAB Efflux Pump in Fluoroquinolone Resistant Salmonella gallinarum Induced by Ciprofloxacin Selective Pressure

Salmonella gallinarum has shown multiple drug resistance (MDR),especially high level fluoroquinolone (FQ) resistance in recent years.To determine whether the active efflux system was responsible for high-level FQ resistance,this research studied AcrAB efflux pump in Salmonella gallinarum on molecular level.The resistant strains were induced by standard strain C79-13 with ciprofloxacin in vitro.With carbonylcyanide-p-chlorophenyl hydrazone (CCCP) as an energy inhibitor,efflux inhibition test initially showed the potential impact of efflux pump on drug resistance.Sequence analysis of acrA gene indicated that gene mutation of AcrAB efflux pump was not definitely associated with MDR and drug resistance level of Salmonella gallinarum.Detected by competitive RT-PCR,the mRNA expression of acrA and acrB genes in the resistant strains significantly increased (p0.01) compared with that of the control strain C79-13.The mRNA expression level of acrB gene (increased from 1.6-to 2.9-folds) was consistent with that of acrA gene (increased from 1.6-to 2.8-folds),which increased with the drug resistance level.However,gene mutation of acrA gene showed no correlation with its mRNA expression level,indicating that gene mutation did not affect the expression of AcrAB pump itself.The results suggested that the overexpression rather than the gene mutation of AcrAB efflux pump was an important factor causing the high level drug resistance of Salmonella gallinarum.     

太阳能-水源热泵联合加热温室系统研究

为了探索太阳能-水源热泵技术在设施农业领域的应用方法和发展潜力,寻求解决温室加温费用高、存在污染等问题的方法,对一种用于温室的太阳能和水源热泵联合加温系统进行了试验研究。结果表明:此项研究对太阳能-水源热泵这项新能源技术在农业领域的应用具有重要的意义,可减少连栋温室水源热泵加温系统一次性投资和运行成本,降低能源消耗,为太阳能水源热泵联合作为温室有效的加温系统提供了一定的理论依据。     

p-nitrophenyl phosphate hydrolysis and calcium ion transport in fragmented sarcoplasmic reticulum

The calcium ion pump of fragmented sarcoplasmic reticulum can be coupled to hydrolysis of p-nitrophenyl phosphate, in the absence of added adenosine triphosphate. Comparison of the activities obtained with the two substrates suggests an analogous mechanism of transport. Independent of the substrate, a 2 : 1 ratio between calcium ion transport and substrate hydrolysis is displayed by the system, and an identical amount of work is required for ion transport against a given gradient. A phosphate ester appears necessary for substrate utilization in the pump mechanism, whereas the structure of the substrate determines the rates of activity and the affinity of the system for calcium ion.     

长输管道泵特性粘度换算动态处理方法

提出了长输管道加热输送原油时对泵特性的影响及特性粘度换算的动态处理方法，实现了修正系数的态搜寻及泵性能自动换算的目标，针对输油管道泵管耦合进行了运行优化分析，对先泵后炉及先炉后泵两种工艺的运行经济性进行了计算比较，计算结果表明，该方法具有良好的工程精度及实用性，进泵原油粘度对泵流量，扬程影响较小，但对泵较大，采用先泵后炉工艺，在不考虑泵粘性影响的情况下，动力费和总运费分别上升10％和4％以上，这说明泵的粘性影响在优化分析时不可忽略，若采用先炉后泵工艺，则可以很大程度上消除泵的粘性影响。     

温室太阳能与空气源热泵联合加温系统的试验

为了探索太阳能、空气源热泵技术在设施农业领域的应用方法和发展潜力,寻求解决温室加温费用高、存在污染等问题的方法,对一种用于温室的太阳能和空气源热泵联合加温系统进行了实验研究,介绍了系统的总体设计和试验方法,并在昆明地区对系统性能和温室加温效果进行了实验。结果表明：在昆明地区最冷月1月,蓄热水箱平均水温可达41.1℃,空气源热泵运行时,制热系数COP平均值均在3以上。无论晴天还是阴天,温室都能够满足作物生长需求。为太阳能空气源热泵联合作为温室有效的加温系统提供了一定的理论依据。     

Direct observation of the femtosecond excited-state cis-trans isomerization in bacteriorhodopsin

Femtosecond optical measurement techniques have been used to study the primary photoprocesses in the light-driven transmembrane proton pump bacteriorhodopsin. Light-adapted bacteriorhodopsin was excited with a 60-femtosecond pump pulse at 618 nanometers, and the transient absorption spectra from 560 to 710 nanometers were recorded from -50 to 1000 femtoseconds by means of 6-femtosecond probe pulses. By 60 femtoseconds, a broad transient hole appeared in the absorption spectrum whose amplitude remained constant for about 200 femtoseconds. Stimulated emission in the 660- to 710-nanometer region and excited-state absorption in the 560- to 580-nanometer region appeared promptly and then shifted and decayed from 0 to approximately 150 femtoseconds. These spectral features provide a direct observation of the 13-trans to 13-cis torsional isomerization of the retinal chromophore on the excited-state potential surface. Absorption due to the primary ground-state photoproduct J appears with a time constant of approximately 500 femtoseconds.     

高效液相色谱法测鸡饲料中微胶囊化的V_A含量

VA是不稳定的物质,容易失效,微胶囊化后可大大提高其活性.试验先皂化微胶囊VA样品,用乙醚提取未皂化的化合物,最后将甲醇提取物注入用C18填充的高效液相色谱拄,运用高效液相色谱法,在326nm下,测定鸡饲料里VA的含量,结果表明,该方法分辩率高,灵敏快速、准确.     

储罐网状阳极阴极保护电流密度需求

网状阳极系统的优点在于储罐外底板保护电位分布均匀,对附近管道干扰小。采用瞬时同步断电法对2个站场的11座储罐进行检测,结果表明：控制电位达到一1．1V时,储罐仍可能未达到有效保护,原因是恒电位仪输出电流或保护电流密度过小,而日常管理通常只关注通电电位,易忽视因IR降造成的欠保护。储罐阴极保护相关标准要求电流密度在1～10rnA／m^2,推荐范围为5～10mA／m^2,而检测结果表明：两站场电流密度为1～2mA／m。时,断电电位基本达到了-850mV。由于电流密度需求受储罐液位和季节等其他因素影响,虽然标准中仅要求在阴极保护系统投运时以消除IR降电位确认电流密度需求,但在运行维护过程中仍需定期以断电电位确认电流密度需求,以有效避免潜在的欠保护风险。（表12,参5）     

荞麦主要拒Na+部位及其Na+/H+逆向转运活性的研究

 【目的】确定荞麦(Fagopyrum esculentum Moench)的主要拒Na+部位、质子泵和Na+/H+逆向转运活性与其拒Na+特性的关系。【方法】以耐盐荞麦品种川荞1号和盐敏感荞麦品种TQ-0808为试验材料,采用“压力室”法压取木质部汁液,测定各部位拒Na+能力;采用蔗糖密度梯度离心法分离细胞质膜和液泡膜,测定质子泵和Na+/H+逆向转运活性。【结果】盐敏感品种的主要拒Na+部位在根部,耐盐品种的主要拒Na+部位在根部和茎基部,耐盐品种整体拒Na+能力明显大于盐敏感品种;相同盐浓度处理下,耐盐品种质子泵和Na+/H+逆向转运活性明显大于盐敏感品种,说明耐盐品种主要拒Na+部位细胞的排Na+能力和Na+区隔化能力明显大于盐敏感品种。【结论】耐盐品种主要拒Na+部位Na+的区隔化在限制Na+向地上部运输中发挥了重要作用,是耐盐荞麦品种主要拒Na+部位拒Na+的主要方式。     

输水管道装置增压泵的节能分析

在输水管道均匀分流和沿管长水力坡降不变的情况下,对一级集中供水泵站、中间加设加压泵站及管道增压泵三种方案的能耗进行了分析。结果表明,采用管道增压泵节能效果最好,并确定了加压泵站及管道增压泵的最佳位置计算式。     

西大滩泵站管道破裂事故的处理

格拉成品油管道西大滩泵站１号主油泵，在输送７０号车用汽油过程中，泵吸入管道与闸阀法兰连接处的焊缝裂开了长８０ｍｍ的裂缝，喷油不止。造成裂缝的原因为泵出口压力大，泵震动较大，泵吸入管道刚度小，使原有焊缝缺陷扩大等。针对泵吸入管道和集油管垂直焊接成一体的实际情况，采用了停泵卸压的泵房内焊接的抢修方案，在抢修过程中，通过停泵停输、泵房内通风换气、塞堆黄油确保集油管中油气不冒出等措施，保证了安全。在抢修施     

泗县输油泵站站内阴极保护

输油泵站站内区域较小，生产设施及其相连的工艺管网相对集中，分支较多，管网的构成复杂，这些因素给站内采用常规的阴极保护系统带来了一定困难。区域阴极保护的特点就是保护对象为一定区域内金属结构的复合体。通过对站区区域性阴极保护技术课题的现场实施，提出：①阴极保护对象应首先集中在油罐底板，其次是埋地、地沟管道及其相关设备，②站内区域性阴极保护的极化电位在－０．８５￣－１．２０Ｖ范围比较恰当合理，③深井阳极