Chemico-Viscous Remanent Magnetization in the Fe3O4-yFe2O3 System

The chemical remanent magnetization (CRM) acquired when single-domain size magnetite (Fe(3)0(4)) oxidizes to maghemite (gammaFe(2)O(3)) in a 50-microtesla field at a series of 13 temperatures from 1000 to 6560C is of similar intensity to viscous remanent magnetization (VRM) acquired under the same field and temperature conditions by unoxidized magnetite. The remanences of the oxidized and unoxidized phases also have similar resistances to demagnetization. These similarities imply that the remanence of the oxidized material is a chemico-viscous remanent magnetization (CVRM) having some of the characteristics of both classic growth CRM and thermally activated VRM. At low temperatures in partially oxidized grains, VRM of the magnetite core and growth CRM of the maghemite surface layer contribute about equally to CVRM. Near the Curie point, intensity of CVRM increases to a Hopkinson-type peak. High-temperature CVRM is more resistant to demagnetization than the thermoremanent magnetization (TRM) produced from cooling through the Curie point.     

Melting of (Mg, Fe)SiO3-Perovskite to 625 Kilobars: Indication of a High Melting Temperature in the Lower Mantle

The melting curves of two compositions of (Mg,Fe) SiO3-perovskite, the likely dominant mineral phase in the lower mantle, have been measured in a C02 laser-heated diamond cell with direct temperature measurements and in situ detection of melting. At 625 kilobars, the melting temperature is 5000 +/- 200 kelvin, independent of composition. Extrapolation to the core-mantle boundary pressure of 1.35 megabar with three different melting relations yields melting temperatures between 7000 and 8500 kelvin. Thus, the temperature at the base of the lower mantle, accepted to lie between 2550 and 2750 kelvin, is only at about one-third of the melting temperature. The large difference between mantle temperature and corresponding melting temperature has several important implications; particularly the temperature sensitivity of the viscosity is reduced thus allowing large lateral temperature variations inferred from seismic tomographic velocity anomalies and systematics found in measured velocity-density functions. Extensive melting of the lower mantle can be ruled out throughout the history of the Earth.     

Melting of (Mg,Fe)2SiO4 at the Core-Mantle Boundary of the Earth

The lower mantle of the Earth is believed to be largely composed of (Mg,Fe)O (magnesiowustite) and (Mg,Fe)SiO3 (perovskite). Radiative temperatures of single-crystal olivine [(Mg0.9,Fe0.1)2SiO4] decreased abruptly from 7040 +/- 315 to 4300 +/- 270 kelvin upon shock compression above 80 gigapascals. The data indicate that an upper bound to the solidus of the magnesiowustite and perovskite assemblage at 4300 +/- 270 kelvin is 130 +/- 3 gigapascals. These conditions correspond to those for partial melting at the base of the mantle, as has been suggested occurs within the ultralow-velocity zone beneath the central Pacific.     

Fe2+/S2O2-8/S2O2-3体系下噻虫嗪的降解研究

为探讨噻虫嗪在Fe2+/S2O2-8/S2O2-3体系下降解情况,首先通过单因素实验研究了不同Fe2 、S2O2-8和S2O2-3浓度对噻虫嗪降解率的影响,然后通过中心复合实验,研究各单因素之间的相互影响,得出了Fe2 /S2O2-8/S2O2-3体系下Fe2 、S2O2-8和S2O2-3三种离子的最佳配比,建立了噻虫嗪化学氧化降解模型,并确定其最佳降解条件为：Fe2 浓度为0.69 mmol·L-1,S2O2-3为0.69 mmol·L-1,S2O2-8为3.29 mmol·L-1。最后在三种离子最佳配比条件下探究了不同溶液初始pH值、不同底物浓度及其活性氧物种淬灭剂对噻虫嗪的降解情况影响。研究结果表明,噻虫嗪在pH=9.0时降解率较好,噻虫嗪的降解率随着底物浓度的增加而减小,活性氧物种淬灭剂会降低噻虫嗪的降解率。     

High-Pressure Brillouin Studies and Elastic Properties of Single-Crystal H2S Grown in a Diamond Cell

High-pressure Brillouin spectra of crystalline hydrogen sulfide (H(2)S) have been measured at up to 7 gigapascals at room temperature. The best fit of the angular dependence of Brillouin acoustic velocities between experimental values and calculations based on Every's expression for elastic waves of an arbitrary direction yielded the orientation of an H(2)S cubic crystal grown in the diamond-anvil high-pressure cell. In situ determinations of sound velocities, as a function of pressure, could be made for any direction, the refractive index, the density, and the elastic constants. This method provides a means for the systematic study of elastic properties and phase transitions of condensed gases under ultrahigh pressures.     

现代农业发展与“三S”技术的有机结合

论述了我国现代农业与“三S”技术的内涵、特征和发展趋势 ;讨论了“三S”技术应用于现代农业的关键性问题 ;指出现代信息农业应以产业化、生态化、市场化和科技为主导 ,以提高农业经营者的科技意识为中心 ,在合理规划的基础上 ,注重效益。     

UV/Fe3+/H2O2体系降解邻苯二甲酸二甲酯

利用UV/Fe3+/H2O2体系降解水溶液中的邻苯二甲酸二甲酯(DMP).导致DMP有效降解的·OH来自Fe(Ⅲ)-H2O络合物、H2O2的光致激发以及由此引发的Fenton反应过程.分析了酯浓度、pH值、H2O2浓度和Fe3+用量等条件对DMP降解的影响.结果表明,pH=3.0,[Fe(Ⅲ)]0=9.0×10-4～2.9×10-3 mol/L,[H2O2]0=8.9×10-4～2.0×10-3 mol/L,光照75 min条件下,50 mol/L DMP的光降解率可达99％以上.DMP浓度增大时,降解率下降.pH=3.0时,对反应进程以一级反应动力学模型进行拟合的结果表明,H2O2是影响反应速率的主要浓度因素,可通过加快Fe3+转化成Fe2+的速度,达到减少其用量,降低处理成本的目的.     

Ordering of V2+, Mn2+, and Fe3+ Ions in Zoisite, Ca2Al3Si3O12(OH)

The presence of very small amounts of Mn(2+), V(2+), and Fe(3+) ions in zoisite can be easily detected by the electron paramagnetic resonance technique at room temperature. The Mn(2+) and Fe(3+) ions are completely ordered and are probably located in the Ca(1)- and Al(II)-sites, respectively, whereas the V(2+) ions probably occupy both Ca(1)- and Ca(2)-sites, with a preference for the Ca(1)-site.     

纳米Fe0/Fe3O4复合体系对溶液中PCB77的降解研究

研究了纳米Fe0与纳米Fe3O4单一与复合体系对溶液中PCB77的降解动力学,以及影响降解效率的不同因素.结果表明,投加纳米Fe0对PCB77有显著的降解效果,反应240 min后PCB77残留率为8.94％;投加纳米Fe0同时配以不同比例的纳米Fe3O4能明显影响PCB77的降解速率,纳米Fe0/Fe3O4投加比例为1∶0.1、1∶0.2和1∶1时,PCB77的残留率分别为6.46％、10.23％和38.20％.溶液pH对纳米Fe0/Fe3O4复合体系降解PCB77具有较大的影响,当溶液pH为6.8时,纳米Fe0/Fe3O4复合体系降解PCB77的效果最好.纳米Fe0Fe3O4复合体系对PCB77的降解是一个还原脱氯的过程,随着PCB77残留率的减小,氯离子浓度不断增大,同时反应体系中氧化还原电位不断降低.研究结果将为环境中残留PCBs提供一种高效去除方法,并为PCBs污染水体和土壤的修复提供理论依据.     

Fe2+对小麦籽粒萌发及幼苗铁积累和分配的影响

采用水培方法研究了不同供铁(Fe2 )水平对济麦20和长5864两个小麦品种籽粒萌发、幼苗生长及铁积累和分配的影响,并对不同品种间的差异进行了分析。结果表明,随铁浓度增加,小麦籽粒的发芽势、发芽率、发芽指数、活力指数和幼苗的芽长、根长、芽重、根重呈先上升后下降的趋势,且铁对小麦根的抑制作用明显大于对芽的抑制;小麦幼苗芽和根中铁含量随处理浓度增大而增多;而芽中的铁积累量随着处理浓度的增大呈先上升后下降再上升的趋势,根中的铁积累量呈先上升后下降的趋势,且品种间积累量差异显著。     

冬季牛舍中三种吸附剂对NH3、CO2和H2S的吸附

[目的]选用三种不同孔径分子筛吸附剂对冬季奶牛圈舍中CO2 、NH3和H2S吸附试验.[方法]用便携式气体检测仪检测排风扇口排出的CO2 、NH3和H2S浓度,悬挂吸附剂的为试验组,不悬挂吸附剂的为对照组.两者之差即为吸附剂XF-1、XF-2、XF-3的吸附浓度,根据实际测得的气温、气压、风速,利用理想气体状态方程推导出公式,将mg/kg换算为mg/m3.当试验组与对照组浓度无差异性时停止试验.[结果]1 kgXF-1吸附剂可吸附CO2 70.91 g、NH3 2.29 g、H2S1.57 g;1kg XF-2吸附剂可吸附CO2 75.49 g、NH3 2.65g、H2S 1.65 g;1kg XF-3吸附剂可吸附CO2 85.95 g、NH3 2.87 g、H2S 1.88 g.[结论]三种吸附剂对CO2 、NH3和H2S气体的吸附量与圈舍内相应气体浓度正相关性显著(P＜0.05),与温湿度负相关性不显著(P＞0.05).吸附剂的吸附能力与总孔体积、比表面积成正比,吸附剂XF-3对气体吸附能力最强,吸附剂XF-1最弱.三种吸附剂在1～3h吸附效果最好,此后缓慢下降,吸附剂XF-1悬挂30 h需要更换,吸附剂XF-2悬挂27h需要更换,吸附剂XF-3悬挂25h需要更换.     

3S系统在安徽省林业上的应用现状及发展前景

简述了地理信息系统 (GIS)、遥感 (RS)、全球定位系统 (GPS)的概念和特点 ,介绍 3S技术在安徽省林业系统的发展过程和应用现状。作为一种崭新的现代技术管理手段 ,3S技术将在森林资源监测、营林规划设计、森林灾害预警、科学宏观决策等方面带来巨大的变革和深远的影响。     

缺铁条件下菜豆植株茎生长素(IAA)与根系Fe3+还原酶活性的关系

研究了营养液培养条件下,对缺铁菜豆植株进行去顶、涂抹生长素极性运输抑制剂CFM或生长素类物质萘乙酸（NAA）等处理后,其根系还原酶活性的变化情况;同时对缺铁菜豆茎尖可扩散型IAA和茎尖内源生长素进行了测定。结果表明,缺铁菜豆根系Fe3 还原酶活性在处理后第4天有所增加,第6、8天显著提高。缺铁同时去顶或涂抹CFM处理可抑制缺铁菜豆根系Fe3 还原酶活性,而涂抹NAA则可较明显地提高去顶后缺铁菜豆植株根系Fe3 还原酶活性。在缺铁处理后不同天数对缺铁菜豆进行去顶处理,在第7天其根系Fe3 还原酶活性表现为：在0～2日进行处理的植株其根系还原酶活性完全受到抑制;在4～6天处理的植株去顶的抑制作用逐渐减弱。从处理后第1天起,缺铁处理植株茎尖内源生长素含量就显著高于对照,在第2天略有降低,随后在第4、6天又迅速增加。缺铁处理植株茎尖可扩散型IAA含量也经过同样变化过程,只是变化幅度相对较大。因此,从时间进程上看,缺铁菜豆茎尖生长素合成、运输的变化情况及人为进行缺铁菜豆植株生长索运输的改变与其根系Fe3 还原酶活性变化的关系,更加确定地反映出茎尖所合成的生长素可能在调控缺铁菜豆根系Fe3 还原酶活性方面发挥作用。     

Fe3+-N改性二氧化钛光催化剂的研制

利用微波等离子体沉膜技术和溶胶-凝胶法在载玻片上制备同时掺Fe3 和N的TiO2膜,经500℃焙烧后所得光催化剂性能较好.分别以紫外和可见光为光源,光催化降解茜素红,结果发现:掺铁量均为0.1%的Fe-N/TiO2较Fe/TiO2的光催化活性好,而且可见光的利用率明显增强;UV-Vis扫描显示掺铁0.1%的Fe-N/TiO2紫外吸收峰较其他TiO2光催化剂强且明显红移.XRD谱图结果表明,分别在500℃和550℃焙烧后的0.1?-N/TiO2,均为锐钛矿型,晶体粒度分别为15.3 nm和20.6 nm,XPS谱图显示Fe-N/TiO2有N1s谱峰.     

潮褐土镉、锌、铅复合污染与土壤酶活性的关系

野外调查的典型相关分析表明,在Cd、Zn和Pb复合污染的潮褐土上,土壤脲酶活性与植物吸收Zn量呈高度的负相关,用它作为评价Zn污染程度的指标,可反映Zn污染的植物有效性;过氧化氢酶活性与植物吸收Pb量、碱性磷酸酶活性与植物吸收Cd量有可能相关,作出此判断分别有80%和50%的把握,尚难以判定它们能否作为评价土壤Pb、Cd污染的指标;转化酶活性与Cd、Zn、Pb的植物吸收量均未达到相关,不能作为评价Cd、Zn、Pb复合污染的指标。     

猪EIF2S3基因克隆测序及其组织表达谱分析

[目的]克隆猪EIF2S3基因mRNA全长,并进行生物信息学分析及检测其在猪各组织中的表达特征,为研究真核翻译起始因子2(eIF2)蛋白γ亚基的生物学功能打下基础.[方法]以荣昌猪胸腺mRNA为模板,采用RCAE-PCR克隆EIF2S3基因的mRNA全长序列,在线完成各种生物信息学分析后,利用实时荧光定量PCR分析猪EIF2S3基因的组织表达特征.[结果]猪EIF2S3基因mRNA全长1813 bp,其中蛋白质编码区(CDS)长1419 bp,5'UTR区、3'UTR区分别长14和380 bp,编码472个氨基酸.EIF2S3蛋白分子量51.1 kD,理论等电点(pI)8.62,包含58个带正电的氨基酸和52个带负电的氨基酸,其前体蛋白靠近N端区域有一个强疏水区;EIF2S3蛋白的空间结构由α-螺旋、β-折叠、延伸及无规则卷曲构成.EIF2S3蛋白氨基酸序列与狗和大白鼠的相似性最高(99.6%),其次是马、猫、牛、羊和人类(99.4%),与斑马鱼的相似性最低(96.6%).EIF2S3基因在猪的心脏、胸腺和淋巴组织中表达量较高,在脾脏和肌肉中呈中度表达,在肾脏中的表达量较低,而在肝脏中基本不表达.[结论]猪EIF2S3基因全长1813 bp,在核酸和氨基酸水平上与其他物种的EIF2S3基因高度同源,尤其与狗和大白鼠的遗传距离最近;其在猪心脏、胸腺和淋巴组织中的表达量较高,在肝脏中基本不表达,据此推测EIF2S3参与合成的蛋白更多地参与心脏泵血和免疫相关功能,基本不发挥能量代谢功能.     

H_2O_2/Fe~(2+)体系处理难降解废水的动力学模型研究进展

概述了H2O2/Fe2+体系(Fenton)处理难降解废水中有关反应动力学模型的研究进展,包括一级、二级动力学模型、反应级数推导模型、稳态假设动力学模型和反应因素相关模型,并对Fenton法处理难降解废水的动力学模型发展趋势进行了展望。     

Frequency metrology in quantum degenerate helium: direct measurement of the 2 3S1 --> 2 1S0 transition

Precision spectroscopy of simple atomic systems has refined our understanding of the fundamental laws of quantum physics. In particular, helium spectroscopy has played a crucial role in describing two-electron interactions, determining the fine-structure constant and extracting the size of the helium nucleus. Here we present a measurement of the doubly forbidden 1557-nanometer transition connecting the two metastable states of helium (the lowest energy triplet state 2 (3)S(1) and first excited singlet state 2 (1)S(0)), for which quantum electrodynamic and nuclear size effects are very strong. This transition is weaker by 14 orders of magnitude than the most predominantly measured transition in helium. Ultracold, submicrokelvin, fermionic (3)He and bosonic (4)He atoms are used to obtain a precision of 8 × 10(-12), providing a stringent test of two-electron quantum electrodynamic theory and of nuclear few-body theory.     

美国、日本的银企关系及其发展

当今西方国家银企关系最为典型的是美国的市场主导型融资制度下形成的松散型银企关系,日本的银行主导型融资制度下形成的紧密型银企关系,它们都与特定的经济环境相联系。在目前世界经济一体化、全球化以及地区经济集团化的趋势下,银企关系制度的市场性特征更加突出,市场化趋向成为主流。