广西红树林根际土壤放线菌的原位培养分离及其活性筛选

为了发掘广西红树林根际土壤的放线菌资源,本文利用原位培养装置,埋于根际土壤中俘获放线菌,30d后取回实验室,采用平板涂布法对4个地点的原位培养样品于15种培养基上进行分离纯化;对分离株基于16SrRNA基因序列进行系统发育分析;进一步进行抗菌活性和产酶活性检测。共分离得到113株放线菌。对其中33株放线菌进行测序,结果表明20株属于链霉菌属,11株属于拟诺卡氏菌属,1株属于伦兹氏菌属,1株与拟诺卡氏菌属相似性最高为90%,很可能属于放线菌一个新属。抗菌实验结果显示其中有7株、4株、18株、6株、10株、3株实验菌株分别对大肠埃希菌、铜绿假单胞菌、金黄色葡萄球菌、普通变形杆菌、乙型溶血性链球菌和肺炎克雷伯氏菌具有抑制作用;有55株、62株、24株、72株的实验菌株分别具有纤维素酶活性、淀粉酶活性、胶原蛋白酶活性、酯酶活性。原位培养可以丰富对广西红树林根际土壤的认识,分离到了新种甚至可能是新属的放线菌,分离得到的部分放线菌菌株具有较高生物活性,为后续工作提供了良好的实验材料。     

Characterization,dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(Pb<Subscript>x</Subscript>Ca<Subscript>1−x</Subscript>)<Subscript>5</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>OH] at 25 °C and pH 2–9

Background

The interaction between Ca-HAP and Pb²⁺ solution can result in the formation of a hydroxyapatite–hydroxypyromorphite solid solution [(Pb_xCa_1?x)₅(PO₄)₃(OH)], which can greatly affect the transport and distribution of toxic Pb in water, rock and soil. Therefore, it’s necessary to know the physicochemical properties of (Pb_xCa_1?x)₅(PO₄)₃(OH), predominantly its thermodynamic solubility and stability in aqueous solution. Nevertheless, no experiment on the dissolution and related thermodynamic data has been reported.

Results

Dissolution of the hydroxypyromorphite–hydroxyapatite solid solution [(Pb_xCa_1?x)₅(PO₄)₃(OH)] in aqueous solution at 25 °C was experimentally studied. The aqueous concentrations were greatly affected by the Pb/(Pb + Ca) molar ratios (X_Pb) of the solids. For the solids with high X_Pb [(Pb_0.89Ca_0.11)₅(PO₄)₃OH], the aqueous Pb²⁺ concentrations increased rapidly with time and reached a peak value after 240–720 h dissolution, and then decreased gradually and reached a stable state after 5040 h dissolution. For the solids with low X_Pb (0.00–0.80), the aqueous Pb²⁺ concentrations increased quickly with time and reached a peak value after 1–12 h dissolution, and then decreased gradually and attained a stable state after 720–2160 h dissolution.

Conclusions

The dissolution process of the solids with high X_Pb (0.89–1.00) was different from that of the solids with low X_Pb (0.00–0.80). The average K _sp values were estimated to be 10^?80.77±0.20 (10^?80.57–10^?80.96) for hydroxypyromorphite [Pb₅(PO₄)₃OH] and 10^?58.38±0.07 (10^?58.31–10^?58.46) for calcium hydroxyapatite [Ca₅(PO₄)₃OH]. The Gibbs free energies of formation (ΔG _f ^o ) were determined to be ?3796.71 and ?6314.63 kJ/mol, respectively. The solubility decreased with the increasing Pb/(Pb + Ca) molar ratios (X_Pb) of (Pb_xCa_1?x)₅(PO₄)₃(OH). For the dissolution at 25 °C with an initial pH of 2.00, the experimental data plotted on the Lippmann diagram showed that the solid solution (Pb_xCa_1?x)₅(PO₄)₃(OH) dissolved stoichiometrically at the early stage of dissolution and moved gradually up to the Lippmann solutus curve and the saturation curve for Pb₅(PO₄)₃OH, and then the data points moved along the Lippmann solutus curve from right to left. The Pb-rich (Pb_xCa_1?x)₅(PO₄)₃(OH) was in equilibrium with the Ca-rich aqueous solution.

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Graphical abstractLippmann diagrams for dissolution of the hydroxypyromorphite–hydroxyapatite solid solution [(Pb_xCa_1?x)₅(PO₄)₃OH] at 25??C and an initial pH of 2.00.

     

地下水对地电前兆影响的实验研究

以含水岩土为样本，研究了不同含水率，不同矿化度，不同压力，不同温度以及岩土层中重力水面的不等高度状态下岩土电阻率的定量变化，实验表明，岩土介质电阻率与所含水的特性有十分密切的关系，该实验首次把地下水前兆与地地前兆作为一个整体，来研究地者之间的内在联系，并分析其相关特征。     

气象装备保障效能评估技术

随着气象部门装备保障业务重要性的不断提高,开展装备保障评估方法的研究,对保障质量进行科学评价成为一个新的课题。就监控、维护和维修3个装备保障子业务分别建立了各自的评估体系,还利用监控、维护和维修业务的独立性,提出了根据业务单位职责的组成,使用监控率、故障率和维修率三者的加权平均值评估装备保障综合效能的方法,对建立装备保障业务的考核体系有一定的参考借鉴意义。     

广州前汛期暴雨各层天气系统特征分析

本文对广州前汛期暴雨的地面、850hPa、500hPa、200hPa系统特征进行了分析，给出了各层系统配置图，为日常预报业务提供分析依据。     

Removal of 2,4-dichlorophenol and pentachlorophenol from aqueous media by electrochemical process

Chlorophenols are persistent toxins in the natural environment. In this investigation, 2,4-dichlorophenol (2,4-DCP) and pentachlorophenol (PCP) in aqueous media were degraded using an electrokinetic process (EK) and an electro-Fenton process (EF) using stainless steel and graphite as the anode and cathode, respectively. Chlorophenols were degraded via direct electrolysis at the surface of the electrode in the EK process. However, in the EF process, the degradation mechanism includes direct electrolysis and oxidation by hydroxyl radicals. The optimal conditions were a current density of 0.75 mA/cm² and an air flow of 0.7 l/min at pH 4. Under the optimal conditions, the 2,4-DCP and PCP removal rates in the EF process were 80.18 and 64.03 %, respectively. The mineralization efficiencies of 2,4-DCP and PCP were 78.23 and 75.77 %, respectively. The results of dechlorination reveal that almost all of the chlorines were released, but some were retained in the intermediates. The dechlorination efficiency revealed that the EF and EK4 processes two chlorines from 2,4-DCP. They released four or five chlorines and four chlorines from PCP, respectively. The kinetic results provide evidence of pseudo-first degradation. The rate constant (k _cp) declined as pH_i was increased from 4 to 10. The k _cp values reveal that the pH is an important factor that affects the degradation efficiency in the electrochemical process.     

GPS掩星技术低轨卫星计划的现状及进展

主要介绍了几个国际上已经实施的GPS掩星计划（GPS／MET，Φrsted,Sunsat,SAC-C,CHAMP)和在研的（COSMIC，ACE）低轨卫星计划的现状及取得的进展。通过总结可知，下一代GPS掩星接收器应具有体积小、质量轻（几百克）、低功耗的特点；能提供实时的卫星物理状态参数；飞行器上的自主计算和控制；星上数据通信和命令解释；所有跟踪数据应符合厘米级精密定轨的要求；能提供掩星和海洋反射实验的测量。     

山东埠后古火山机构显微构造研究

埠后古火山机构由早白垩世陆相火山岩和次火山岩组成,铅、锌、铜、硫矿与后者有关。为了圈定火山通道的大致位置,在熔岩中采制定向切片,进行显微构造分析。通过变形、压密、阻挡、涡流等显微构造标志确定流动方位;利用长条状晶体的长轴方向确定流动线理。根据流动方位和流动线理圈出古火山口位置,进而指出在环火山颈的大断裂一侧,可能具区域找矿前景。     

A Review of Radar- and Satellite-based Observational Studies and Nowcasting Techniques on Convection Initiation

Convection often produces severe weather which causes a great loss to human lives and properties. Precisely predicting the convection initiation process is crucial but challenging in operational convection nowcasting (0~2 h forecasting). Before the radar-defined CI occurring (e.g., the first occurrence of ≥35 dBZ echoes), observations at high spatial and temporal resolutions from weather radars and geostationary meteorological satellites can reveal precursor information such as the boundary-layer convergence lines and the rapid growth of newborn cumulus clouds. These radar- and satellite-observed precursor information are helpful for evaluating the pre-CI conditions and thus nowcasting the accurate CI timing and location. This paper reviewed the current status of radar- and satellite-based CI research and nowcasting techniques. The milestone works and the following studies in the last four decades were summarized to demonstrate how radar and satellite observations can be related to CI occurrence. The objectives and approaches of the CI research advance as the improvement in the capability of radars and were explained satellites. The research progress aids in the development of various CI nowcasting techniques. This paper introduced three well-established techniques that have been put into operational application, namely, ANC system, SATCAST algorithm, and UWCI algorithm. Some scientific issues with respect to radar- and satellite-based CI research and nowcasting were also presented.     

累托石制备润滑脂的初步研究

累托石是一种具有独特的结构组成和性质的粘土矿物,其既具有象蒙脱石一样的阳离子交换性,吸水膨胀性,制浆性等,又具有象云母一样的耐高温性和光滑性等性能。经提纯和有机改性后的累托石吸油速度快,膨胀率高,是一种较好的稠化剂,用它制备的润滑脂滴点〉６３３．１５Ｋ,远高于膨润土润滑脂的指标要求,研究表明,累托石是制备润肖脂稠化剂的好原料,累托石润滑脂是一种新型高温润滑脂。