一种纳米氧化锌的光催化性能研究

采用水热法制备出具有高比表面积的多层笼状结构的纳米氧化锌.通过XRD,SEM,EDS,TG-DTA,N2吸附等方法对产物的结构、组成、以及形貌进行了表征.以染料甲基橙的光催化降解为模型评价了所得不同形貌的ZnO的光催化活性.结果表明,所得的多层笼状ZnO纳米材料在高压汞灯照射下表现出良好的光催化性能,且多层笼状ZnO的光催化活性优于微米棒.该方法不仅具有工艺简单、绿色环保,且无需引入表面活性剂,便于大规模生产等优点.     

Seismic identification of along-axis hydrothermal flow on the East Pacific Rise

Hydrothermal circulation at the axis of mid-ocean ridges affects the chemistry of the lithosphere and overlying ocean, supports chemosynthetic biological communities and is responsible for significant heat transfer from the lithosphere to the ocean. It is commonly thought that flow in these systems is oriented across the ridge axis, with recharge occurring along off-axis faults, but the structure and scale of hydrothermal systems are usually inferred from thermal and geochemical models constrained by the geophysical setting, rather than direct observations. The presence of microearthquakes may shed light on hydrothermal pathways by revealing zones of thermal cracking where cold sea water extracts heat from hot crustal rocks, as well as regions where magmatic and tectonic stresses create fractures that increase porosity and permeability. Here we show that hypocentres beneath a well-studied hydrothermal vent field on the East Pacific Rise cluster in a vertical pipe-like zone near a small axial discontinuity, and in a band that lies directly above the axial magma chamber. The location of the shallow pipe-like cluster relative to the distribution and temperature of hydrothermal vents along this section of the ridge suggests that hydrothermal recharge may be concentrated there as a consequence of the permeability generated by tectonic fracturing. Furthermore, we interpret the band of seismicity above the magma chamber as a zone of hydrothermal cracking, which suggests that hydrothermal circulation may be strongly aligned along the ridge axis. We conclude that models that suggest that hydrothermal cells are oriented across-axis, with diffuse off-axis recharge zones, may not apply to the fast-spreading East Pacific Rise.     

金刚石晶体生长研究进展

介绍利用高温高压（HPHT）合成高质量金刚石单晶和化学气相沉积法（CVD）制备金刚石薄膜的设备、方法、工艺参数以及热丝CVD和微波等离子体CVD的优缺点;P型和N型金刚石掺杂研制现状.重点介绍N型金刚石掺杂的困难,氮、锂、钠、磷、硫等杂质的掺杂效果,共掺杂对于金刚石薄膜的影响,以及近年来P型和N型掺杂取得的成果.     

Effect of Al~(3+) on Tobermorite Crystallinity

The difference betWeen the systems of CaO-Sio,-H,o and CaO - S iO, -Al(oH), -H,o, was studie d,esPecially the effect ofAl3' on the crystallinity oftobermorite was focussed. As a result, in the system ofCaO-Sio,-H,o, tobermorite formed early, howeveY, with reaction tdrie forward, tobermorite was replaced byxonotlite. So far as CaO-SiO,-Al(OH),-H,O was concemed, hydrothermal reaction was carried out under thesaJne condition as CaO-Sio,-H,o to study the morphological changes oftobermorite crystals. It was found thatAls+ accelerated the crystal growth oftobermorite to some extent and was in favor ofplaty crystals. Moreovef,with the Al3+ contCllt increasing in the staning matCrial, the morphology of tobermoritC did not change mag-niflcentiy but platy crystals became more and more eminent. As soon as the Al,O, content was over 15.6%,synthetic mineral greatly changed in strUctUre and tUmed into hibschite different from l. l nm tobermorite. Ob-viously xonotlite was not aPt to form in the presence of Al3+.     

Larval dispersal potential of the tubeworm Riftia pachyptila at deep-sea hydrothermal vents

Hydrothermal vents are ephemeral because of frequent volcanic and tectonic activities associated with crust formation. Although the larvae of hydrothermal vent fauna can rapidly colonize new vent sites separated by tens to hundreds of kilometres, the mechanisms by which these larvae disperse and recruit are not understood. Here we integrate physiological, developmental and hydrodynamic data to estimate the dispersal potential of larvae of the giant tubeworm Riftia pachyptila. At in situ temperatures and pressures (2 degrees C and 250 atm), we estimate that the metabolic lifespan for a larva of R. pachyptila averages 38 days. In the measured flow regime at a fast-spreading ridge axis (9 degrees 50' N; East Pacific Rise), this lifespan results in potential along-ridge dispersal distances that rarely exceed 100 km. This limited dispersal results not from the physiological performance of the embryos and larvae, but instead from transport limitations imposed by periodic reversals in along-ridge flows and sustained episodes of across-ridge flow. The lifespan presented for these larvae can now be used to predict dispersal under current regimes at other hydrothermal vent sites.     

Er～（3＋）、Yb～（3＋）掺杂NaYF4微米晶体的设计合成及光学性能研究

采用水热合成法制备了Er3＋、Yb3＋掺杂的NaYF4微米晶体.当反应温度为180°C时,得到了纯的六方相微米晶体.样品的颗粒分布均匀,形貌为边长约300nm的六方棱柱.在980nm激光的激发下,得到了很强的红色上转换发光.     

铁基粉末触媒合成金刚石

本文利用六种铁基粉末触媒（FeNiNa,n=0,1,2,3,d,5X。代表Fe在触媒中的含量,Xn〉xn-1）在国产六面顶压机上进行了金刚石单晶的合成实验,研究了高温高压条件下（～6GPa,～1600℃）,铁基粉末触媒随铁含量的改变,石墨碳—铁基触媒体系合成金刚石条件的变化规律以及金刚石单晶的生长特性,利用穆斯堡尔谱对金刚石中铁元素形成的包裹体进行了检测．结果表明,随着铁基粉末触媒中铁含量的增加,合成金刚石的压力和温度条件逐渐增高,金刚石生长的“V形区”上移,同时得出了铁基粉末触媒适合高温区（110）和（111）面生长以及金刚石中铁元素以FeNi和FeyC形式存在的结论．     

纳米羟基磷灰石-地塞米松载药体系的制备及体外缓释研究

以CaCl2和Na2HPO4·12H2O为前驱体,在生物安全性能良好的十二烷基硫酸钠(SDS)-聚乙烯吡咯烷酮(PVP)体系中,采用化学沉淀法水热合成得到了纳米羟基磷灰石(nHAP).采用透射电镜、红外光谱、X射线衍射等方法对产品的形貌、晶相、化学组成等进行表征,结果显示:所制备的nHAP为长40～120 nm、宽约30 nm的纳米棒,晶体形貌规则,结晶良好.采用地塞米松作为药物负载对象的研究证实,所合成的nHAP载药性能良好；体外药物缓释实验表明,nHAP-地塞米松载药体系在模拟体液环境中,12h后药物释放率才达到96.8％,具有良好的药物缓释效果.     

稀土镧掺杂的TiO2微球制备及其光催化性能研究

以四氯化钛为原料,采用溶胶-凝胶法制备了掺杂镧的TiO2 微球. 采用X-射线衍射、荧光光谱、扫描电镜等手段对样品进行表征,结果表明:所制得的掺杂镧的TiO2 微球直径在300~600 μm之间,微球中TiO2 晶粒为锐钛矿相和金红石相的混合晶型,且以锐钛矿为主相,平均粒径为20 nm左右. 分别在太阳光和300 W高压汞灯的光照下,考察了不同光催化剂对甲基橙染料的光催化效果,结果表明,掺杂La2 O3 的TiO2 复合微球具有较好的光催化性能.     

Rapid growth of ZnO hexagonal tubes by direct microwave heating

Zinc oxide hexagonal tubular crystals were synthesized by direct microwave heating from ZnO powders within 5 min without any metal catalysts or transport agents. ZnO source materials were evaporated from the high-temperature zone in an enclosure, and crystals were grown on the self-source substrate in an appropriate condition. The ZnO vapor formed in the high-temperature zone can deposit and grow on the powders located in the low-temperature zone to form crystals. The scanning electron microscopy (SEM) reveals that these products are hexagonal tube crystals with 80 μm in diameter and 250 μm in length, having a well faceted end and side surface. A possible growth mechanism and the influence of reaction temperature on the formation of crystalline ZnO hexagonal tubes were presented. The photoluminescence (PL) exhibits strong ultraviolet emission at room temperature, indicating the potential applications in short-wave light-emitting photonic devices.     

基于数字孪生的高温高压容器寿命预测

为解决高温高压容器剩余寿命在线预测难题,提出一种基于数字孪生的高温高压容器剩余寿命预测模型构建方法。该方法基于实时工况条件,采用ANSYS仿真模型进行耦合仿真,获取高温高压容器一定时域物理场,通过多轴蠕变损伤模型建立高温高压容器剩余寿命预测样本数据集,利用Tent-SSA优化的BP神经网络算法进行训练预测,建立机理模型与机器学习融合驱动的数字孪生高温高压容器寿命预测模型。最后以某型钠冷快堆蒸汽发生器关键部件的管板作为对象,试验结果表明该预测模型总体均方误差由优化前的3.2197E-02降低至7.7449E-03,模型更稳定且鲁棒性强、收敛快。     

Deep-sea ecology. Developmental arrest in vent worm embryos

Temperature is a key factor in controlling the distribution of marine organisms and is particularly important at hydrothermal vents, where steep thermal gradients are present over a scale of centimetres. The thermophilic worm Alvinella pompejana, which is found at the vents of the East Pacific Rise (2,500-m depth), has an unusually broad thermotolerance (20-80 degrees C) as an adult, but we show here that the temperature range required by the developing embryo is very different from that tolerated by adults. Our results indicate that early embryos may disperse through cold abyssal water in a state of developmental arrest, completing their development only when they encounter water that is warm enough for their growth and survival.     

人工合成金刚石技术比较

静压法是当前工业合成金刚石的主要的合成手段,合成工业用金刚石主要采用静压法中的静压触媒法,合成宝石级金刚石主要采用静压晶种触媒法生产,通过静压法中的直接变换法,纯净的多晶石墨棒可以在短时间内转化为多晶金刚石,二十世纪八十年代还出现了一种在低压下生长金刚石的新方法——化学气相沉积法(CVD),目前只能用于制备金刚石薄膜,本文通过总结比较各种金刚石合成技术,提出了利用激光控制金刚石生长的设想,使用这种方法将提高金刚石的质量,     

Primary Sn-rich titianite in the Qitianling granite, Hunan Province, southern China: An important type of tin-bearing mineral and its implications for tin exploration

The Qitianling calc-alkaline granite in Hunan Province (South China) has attracted much attention since the discovery of the Furong super-large tin deposit. The present study provides new mineralogical data to address their implications for exploration of tin deposits. In the Taoxiwo granite in the southeastern part of the Qitianling granite body, Sn-rich titanite was identified as an important type of Sn-bearing mineral. The titanite commonly occurs with biotite as euhedral crystals, exhibiting typical envelope-like shape and sector-zoning texture. These indicate that the titanite most likely crystallized in the magmatic stage. Electron-microprobe analyses show that the titanite is enriched in tin up to 1.12 wt% SnO₂, with an average of 0.43 wt%. With the crystallization of the granite, primary minerals undertook hydrothermal alteration by magma-derived fluids. Subsequently, in the hydrothermal stage, the primary Sn-bearing titanite was altered (at least partially), but still preserved its typical envelope-shaped outline. Micro-scale cassiterite is a representative product of such alteration; other secondary minerals include fluorite, ilmenite, Sn-bearing rutile and quartz. Therefore, the titanite, commonly present in the calcalkaline granites, can be treated as an important Sn-carrying mineral in the Qitianling granite, reflecting the primary magmatic environment with tin enrichment. The hydrothermal alteration of the primary titanite and subsequent crystallization of cassiterite recorded a process of leaching and accumulation of tin in magmatic-hydrothermal evolution of the Sn-bearing granite. Thus, this titanite has important implications for tin exploration. Supported by National Natural Science Foundation of China (Grant Nos. 40730423 and 40221301) and Project of China Geological Survey (Grant No. 1212010632100)     

纳米颗粒对高温高压钻井液性能的影响

随着油气行业对深部储层的不断勘探,对钻井液的性能要求越来越高。纳米颗粒的添加可以提高高温高压钻井液特定性能。同传统钻井液添加剂相比,纳米颗粒能够有效改善钻井液的流变性,降低滤失量,提高热稳定性、润滑性,以应对高温高压油藏条件。基于纳米颗粒优异的热性能、机械性能、化学性能以及与基液相容性,对金属纳米颗粒、碳基纳米颗粒、二氧化硅纳米颗粒在耐高温高压钻井液中的应用进行了论述。同时,讨论了纳米颗粒在高温高压条件下对钻井液性能的影响,阐述了纳米颗粒的形状、尺寸和添加浓度是影响其性能的关键因素。将纳米颗粒作为高温高压钻井液添加剂也为降低其环境影响和生产成本提出了新思路。     

单根In掺杂的n-ZnO纳米线/p+-Si异质结的紫外电致发光

采用化学气相沉积的方法在In_0.1Ga_0.9N衬底上生长出In掺杂的n-ZnO纳米线阵列。电学输运测量得到单根n-ZnO纳米线的电阻率为0.001 Ω cm,比同样方法在GaN衬底上生长的ZnO纳米线低约20倍。这个结果表明来自于In_0.1Ga_0.9N衬底中的In原子在高温生长过程中可能被掺入ZnO纳米线。制备成功单根n-ZnO纳米线/p⁺-Si异质结构并研究了其电致发光特性。室温下电致发光光谱中可以看到一个窄的ZnO激子峰（约380 nm）和一个中心位于700 nm 的来自Si衬底表面自然氧化硅发光中心的发光峰。     

不同土壤灭菌方法对土壤微生物活性的影响

灭菌处理是土壤生态学、微生物学及其相关学科的一种重要研究手段,灭菌效果的好坏直接关系到后续研究的进行及其结果的准确性.常用土壤灭菌方法的灭菌效果及其评估仍然存在很大的不确定性.本文选取目前常用的3种灭菌方法,即高温高压蒸汽法、氯仿熏蒸法及辐射灭菌法,对不同背景的土壤样品进行灭菌.通过改变灭菌次数及灭菌间隔时间,观察灭菌后土壤微生物呼吸速率的变化.结果表明:(1)常规氯仿熏蒸灭菌后土壤微生物呼吸速率并不完全随着微生物量的减小而降低,说明单纯从土壤微生物量的角度不能准确界定灭菌效果以及解析微生物在土壤生态过程中的作用;(2)高温高压蒸汽比常规氯仿熏蒸和辐射灭菌方法有更好的土壤微生物灭活效果.实际应用中采用高温高压蒸汽灭菌时,建议采用灭菌2次、时间间隔为3d的灭菌处理;在相关研究中,对使用该方法灭菌效果的分析研究最佳时间不宜超过2d.     

基于Mg—O—C棒状次级结构单元的镁配合物的合成及晶体结构

一个新型的镁配合物Mg(H2O)2(oba2-)(1)(H2oba=4,4’-oxybis(benzoate))是在水热条件下成功合成的,该化合物通过元素分析、红外光谱、热重分析及X-射线单晶衍射等结构表征,X-射线单晶结构解析表明该化合物属于单斜结构,P21/c空间群,晶胞参数:a=1.408 5(3)nm,α=90°,b=1.002 5(2)nm,β=105.47(3)°,c=1.019 8(2)nm,γ=90°,V=1.387 8(5)nm3,Z=4,R1=0.040 5,wR2=0.091 7.由Mg—O—C构成的相邻且平行的一维棒状次级结构单元通过有机配体连接成该配合物的二维结构,又通过氢键将此二维结构连接成为三维超分子结构.     

Synchrotron X-ray diffraction techniques for in situ measurement of hydride formation under several gigapascals of hydrogen pressure

The high-pressure technique is a fundamental tool for realizing novel phase transitions, chemical reactions, and other exotic phenomena. Hydrogenation is one example of a high-pressure reaction; at high pressures of several gigapascals, hydrogen becomes chemically active and reacts with metals and alloys to form hydrides. This paper covers a high-pressure study of the hydrogenation process and the synthesis of hydrides using a cubic-type multi-anvil apparatus. The experimental details of a hydrogenation cell assembly, high-temperature and highpressure generation, and an in situ observation technique are presented. These experiments are conducted with the aid of in situ synchrotron radiation X-ray diffraction measurements operated in an energy-dispersive mode in the conventional manner for time-resolved measurements and a newly developed angle-dispersive mode for observation of the crystal growth process during formation of metal hydrides. Two successful cases of high-pressure hydrogenation are presented： aluminum hydride, Al H3, and an aluminum-based alloy hydride, Al2 Cu Hx, which are potential candidates for hydrogen storage materials.     

纳米SrxCa1-xTiO3固溶体粉体的制备及性能表征

采用低温液相法以廉价的TiCl₄、SrCl₂、CaCl₂为原料，以NaOH溶液为沉淀剂一步合成了纳米Sr_xCa_1-xTiO₃固溶体粉体。为了提高粉体颗粒结晶度，改善形貌，进行了水热后处理。通过XRD，TEM，FT IR，TG和ICP等表征手段对所得粉体的物相、形貌、颗粒尺寸及分布、杂质含量、Ca²⁺与Ti⁴⁺摩尔比进行了分析和测试。结果表明，Sr_xCa_1-xTiO₃在0.1≤x≤0.9范围形成了固溶体，且随x的增大相结构从斜方相逐渐过渡到立方相。水热处理前粉体结晶度低，形貌不规整，而进行水热处理后粉体中O—H缺陷和CO₃^2-杂质显著减少，结晶度提高，形貌规整均匀，随着x从0.3增加到0.9，颗粒粒径从230nm减小到65nm(水热处理前：从220nm减小到45nm)。