污水源热泵系统污水干渠横向取水研究

从实际工程遇到的取水问题出发,以水泵运行流量和排水口处水深为控制因素,利用非均匀渐变明渠流理论进行分析,得到了最小自流高差、最大取水量及取排水口间距范围的关系式,为污水热能利用工程的取排水设计及施工提供参考.     

Tungsten isotope evidence that mantle plumes contain no contribution from the Earth's core

Osmium isotope ratios provide important constraints on the sources of ocean-island basalts, but two very different models have been put forward to explain such data. One model interprets (187)Os-enrichments in terms of a component of recycled oceanic crust within the source material. The other model infers that interaction of the mantle with the Earth's outer core produces the isotope anomalies and, as a result of coupled (186)Os-(187)Os anomalies, put time constraints on inner-core formation. Like osmium, tungsten is a siderophile ('iron-loving') element that preferentially partitioned into the Earth's core during core formation but is also 'incompatible' during mantle melting (it preferentially enters the melt phase), which makes it further depleted in the mantle. Tungsten should therefore be a sensitive tracer of core contributions in the source of mantle melts. Here we present high-precision tungsten isotope data from the same set of Hawaiian rocks used to establish the previously interpreted (186)Os-(187)Os anomalies and on selected South African rocks, which have also been proposed to contain a core contribution. None of the samples that we have analysed have a negative tungsten isotope value, as predicted from the core-contribution model. This rules out a simple core-mantle mixing scenario and suggests that the radiogenic osmium in ocean-island basalts can better be explained by the source of such basalts containing a component of recycled crust.     

广州西航道主要水源地水质达标分析

利用河网区非稳态水量、水质数学模型及水文、水质、污染源同步观测资料,推求了广州西航道水质降解系数;采用二维控制断面水质达标分析模型,建立了涨、落潮设计水文条件下水源地水质与污染源的响应关系;通过对影响广州西航道主要水源地西村、石门两水厂主要排污口的调查,研究了西村、石门两水厂的水质达标情况．结果表明：各排污口的削减方案涉及社会、经济等多种因素,很难仅从环境角度给出最佳方案;通过不同方案下水源地水质与排污量的响应关系曲线,可确定出水源地水质达标时各排污口的允许排污量．     

Structural basis of water-specific transport through the AQP1 water channel.

Water channels facilitate the rapid transport of water across cell membranes in response to osmotic gradients. These channels are believed to be involved in many physiological processes that include renal water conservation, neuro-homeostasis, digestion, regulation of body temperature and reproduction. Members of the water channel superfamily have been found in a range of cell types from bacteria to human. In mammals, there are currently 10 families of water channels, referred to as aquaporins (AQP): AQP0-AQP9. Here we report the structure of the aquaporin 1 (AQP1) water channel to 2.2 A resolution. The channel consists of three topological elements, an extracellular and a cytoplasmic vestibule connected by an extended narrow pore or selectivity filter. Within the selectivity filter, four bound waters are localized along three hydrophilic nodes, which punctuate an otherwise extremely hydrophobic pore segment. This unusual combination of a long hydrophobic pore and a minimal number of solute binding sites facilitates rapid water transport. Residues of the constriction region, in particular histidine 182, which is conserved among all known water-specific channels, are critical in establishing water specificity. Our analysis of the AQP1 pore also indicates that the transport of protons through this channel is highly energetically unfavourable.     

突水溃沙通道分区及发育高度研究

根据浅埋煤层不同基岩厚度所面临的突水溃沙灾害威胁程度差异,须对不同溃沙通道类型进行科学划分,并提出突水溃沙灾害配套的专有名词,为制定针对性的灾害防治措施提供可靠的理论依据。鉴于导水裂缝带是从顶板水害防治角度提出的概念,对于新时期条件下的水砂溃涌灾害问题已经无法适用,因此必须寻求一种基于水砂溃涌灾害防治要求的新概念,通过对其发育规律及高度的研究,为揭示顶板突水溃沙机理奠定基础。据此,通过相似模拟分析了浅埋煤层覆岩破坏特征,将浅埋煤层开采后的覆岩发育形态自上而下划分为网络性裂缝带和冒落性裂缝带,自外向内划分为贯通性裂缝区和方向性裂缝区,即竖"两带"、横"两区",并从防治突水溃沙灾害角度出发,提出了导水沙裂缝带的概念;同时依据物理模拟实验结果建立了"导水沙拱"力学模型,运用结构力学、岩体力学和散体力学对导水沙裂缝带高度进行了理论推导,在得出4个解后,将涉及到的各参数取值区间代入到4个解中,最终确定导水沙裂缝带高度计算公式并,该成果为突水溃沙灾害防治体系提供了一定的理论依据,有效指导该类灾害的防治工作。     

供水管网铁腐蚀机理及快速检测技术研究

探讨了供水管网铁在氧的不同存在状态下的腐蚀机理及细菌加速腐蚀的作用，水中可溶性总铁含量大于0．5mg／L可作为判别管网铁腐蚀警戒指标。研究开发了测试管法快速检测水中铁技术。     

Permeation study of the potassium channel from streptomyces Lividans

A three-state hopping model is established according to experiments to study permeation of an open-state potassium channel from Streptomyces Lividans (KcsA potassium channel). The master equations are used to characterize the dynamics of the system. In this model, ion conduction involves transitions of three states, with one three-ion state and two two-ion states in the selectivity filter respectively. In equilibrium, the well-known Nernst equation is deduced. It is further shown that the current follows Michaelis-Menten kinetics in steady state. According to the parameters provided by Nelson, the current-voltage relationship is proved to be ohmic and the current-concentration relationship is also obtained reasonably. Additional validation of the model in the characteristic time to reach the steady state for the potassium channel is also discussed. This model lays a possible physical basis for the permeation of ion channel, and opens an avenue for further research.     

桥梁桩群存在条件下的河道水面线计算方法研究

河道水面线计算是防洪规划中的重要内容.在河道上修建桥梁工程,桥墩多采用桩群基础结构型式.洪水期,水中桩群的存在会显著抬高河道的水位,造成阻水,使河道的泄洪能力降低,其河道水面线的计算必须考虑桩群摩水的影响.为此,本文以桩群阻力的物理模型实验数据为依据,通过将桩群阻水作用概化成等效糙率,并考虑桩群引起的过流断面缩小造成的局部阻力损失,建立了桥梁桩群存在条件下的河道水面线计算方法,为防洪规划设计标准的合理确定提供了参考依据.     

Importance of NPA motifs in the expression and function of water channel aquaporin-1

The asparagine-proline-alanine sequences (NPA motifs) are highly conserved in aquaporin water channel family. Crystallographic studies of AQP1 structure demonstrated that the two NPA motifs are in the narrow central constriction of the channel, serving to bind water molecules for selective and effi-cient water passage. To investigate the importance of the two NPA motifs in the structure, function and biogenesis of aquaporin water channels, we generated AQP1 mutations with NPA1 deletion, NPA2 de-letion and NPA1,2 double deletion. The coding sequences of the three mutated cDNAs were subcloned into the mammalian expression vector pcDNA3.1 to form expression plasmids. We established stably transfected CHO cell lines expressing these AQP1 mutants. Immunofluorescence indicated that all the three mutated AQP1 proteins are expressed normally on the plasma membrane of stably transfected CHO cells, suggesting that deletion of NPA motifs does not influence the expression and intracellular processing of AQP1. Functional analysis demonstrated that NPA1 or NPA2 deletion reduced AQP1 water permeability by 49.6% and 46.7%, respectively, while NPA1,2 double deletion had little effect on AQP1 water permeability. These results provide evidence that NPA motifs are important for water per-meation but not essential for the expression, intracellular processing and the basic structure of AQP1 water channel.     

河床下切对珠江三角洲峰值水位演变的影响

为研究珠江三角洲峰值水位对采沙造成的河床下切响应过程,通过调和分析方法去除水位时间序列中潮汐节点调制波动的影响,并提出概率密度函数法诊断河网内峰值水位的历史演变趋势。结果表明:三角洲上游峰值水位随着河床的下切而显著降低;河网中腹部地区,峰值水位随着河床的下切出现显著的上升,从而增加了中腹部地区的防洪风险;在下游地区,峰值水位的变化与海平面上升或其他人类活动相关。     

快滤池进水渠道内堰板的正交试验与优化设计

为了提高快滤池的利用率和生产效率,提出在快滤池进水渠道内添加堰板的方案.以镇江金西自来水厂为例,采用拟水平方法设计L9(34)正交表,选取了堰板距进水渠道前端面的距离、高度和宽度因素,每个因素取3水平,设计了9种堰板.然后采用CFX中的均相流自由表面模型和基于SST模型的k-ω方程的数值模拟方法,对渡槽、过渡段和快滤池进水渠道内的自由表面流动进行了数值模拟.以各虑池流量均布为优化目标,确定最优方案并进行现场改造试验.试验结果证明:1号滤池的流量提高了16.5%,各池流量较均匀分布,最高差异为1.4%.均相流自由表面模型为自来水厂等水利工程提供新型的优化设计方法.     

Phosphorylation-regulated Cl- channel in CHO cells stably expressing the cystic fibrosis gene.

A cyclic AMP-stimulated chloride conductance appears when the cystic fibrosis gene is expressed in non-epithelial cells by infection with recombinant viruses. Cyclic AMP-stimulated conductance in this system is mediated by the same ohmic, low-conductance Cl- channel as in human secretory epithelia, but control of this channel by phosphorylation has not been directly demonstrated. Here we report the appearance of the low-conductance Cl- channel in Chinese hamster ovary cells after stable transfection with the cystic fibrosis gene. The channel is regulated on-cell by membrane-permeant analogues of cAMP and off-cell by protein kinases A and C and by alkaline phosphatase. These results are further evidence that the cystic fibrosis transmembrane regulator is a Cl- channel which can be activated by specific phosphorylation events and inactivated by dephosphorylation; they reveal an unsuspected synergism between converging kinase regulatory pathways.     

A cyclic GMP-activated channel in dissociated cells of the chick pineal gland.

Phototransduction in the vertebrate retina is dependent in part on a cyclic GMP-activated ionic channel in the plasma membrane of rods and cones. But other vertebrate cells are also photosensitive. Cells of the chick pineal gland have a photosensitive circadian rhythm in melatonin secretion that persists in dissociated cell culture. Exposure to light causes inhibition of melatonin secretion, and entrainment of the intrinsic circadian oscillator. Chick pinealocytes express several 'retinal' proteins, including arrestin, transducin and a protein similar to the visual pigment rhodopsin. Pinealocytes of lower vertebrates display hyperpolarizing responses to brief pulses of light. Thus it is possible that some of the mechanisms of phototransduction are similar in retinal and pineal photoreceptors. We report here the first recordings of cyclic GMP-activated channels in an extraretinal photoreceptor. Application of GMP, but not cyclic AMP, to excised inside-out patches caused activation of a 15-25 pS cationic channel. These channels may be essential for phototransduction in the chick pineal gland.     

Purification and reconstitution of the calcium release channel from skeletal muscle

The calcium release channel from rabbit muscle sarcoplasmic reticulum (SR) has been purified and reconstituted as a functional unit in lipid bilayers. Electron microscopy reveals the four-leaf clover structure previously described for the 'feet' that span the transverse tubule (T)-SR junction. Ca2+ release from the SR induced by T-system depolarization during excitation-contraction coupling in muscle may thus be effected through a direct association of the T-system with SR Ca2+-release channels.     

A prokaryotic proton-gated ion channel from the nicotinic acetylcholine receptor family

Ligand-gated ion channels (LGICs) mediate excitatory and inhibitory transmission in the nervous system. Among them, the pentameric or 'Cys-loop' receptors (pLGICs) compose a family that until recently was found in only eukaryotes. Yet a recent genome search identified putative homologues of these proteins in several bacterial species. Here we report the cloning, expression and functional identification of one of these putative homologues from the cyanobacterium Gloeobacter violaceus. It was expressed as a homo-oligomer in HEK 293 cells and Xenopus oocytes, generating a transmembrane cationic channel that is opened by extracellular protons and shows slow kinetics of activation, no desensitization and a single channel conductance of 8 pS. Electron microscopy and cross-linking experiments of the protein fused to the maltose-binding protein and expressed in Escherichia coli are consistent with a homo-pentameric organization. Sequence comparison shows that it possesses a compact structure, with the absence of the amino-terminal helix, the canonical disulphide bridge and the large cytoplasmic domain found in eukaryotic pLGICs. Therefore it embodies a minimal structure required for signal transduction. These data establish the prokaryotic origin of the family. Because Gloeobacter violaceus carries out photosynthesis and proton transport at the cytoplasmic membrane, this new proton-gated ion channel might contribute to adaptation to pH change.     

不同生长期和不同产地山茱萸中马钱苷的测定

目的为进一步开发陕南山茱萸资源,明确不同生长期和不同产地的山茱萸马钱苷含量。方法采用HPLC法测定。结果不同产地山茱萸果实中马钱苷含量在4．08‰～26．17‰之间,其中以西北大学果园的样品含量最高;不同生长期中,以11月中旬采集的马钱苷含量最高。结论不同生长期和不同产地山茱萸马钱苷含量差异较大,其中山茱萸最佳采收时间为每年11月中旬果实脱落之前;另外,利用HPLC法进行测定,操作简单、快速、重现性好。     

农药高效氯氰菊酯对小鼠肾细胞氧化损伤的研究

为了研究农药高效氯氰菊酯对生物体的氧化损伤,以昆明小鼠为受试体,高效氯氰菊酯按10、20和40mg/kg 3个剂量水平,灌胃染毒小鼠7d,以肾匀浆测定ROS和GSH,以肾细胞测定DPC系数.实验结果表明:随着高效氯氰菊酯染毒剂量的升高,ROS和DPC系数逐渐上升,GSH含量逐渐降低,各指标呈一定的剂量效应关系.染毒剂量...