宇宙成因核素10Be,26Al:原理及其在地表过程中的应用

地表岩石中宇宙成因核素10Be和26Al含量是侵蚀速率和辐射时间的函数,通过对岩石中10Be和26Al含量的测定能反映较长时间(103~107a)和较大空间尺度上的侵蚀作用大小和过程.根据10Be含量估算出长江中下游地区平均侵蚀速率为30~60m·Ma-1,攀枝花至三峡长江流域内地表平均侵蚀速率为200m·Ma-1.     

宇宙成因核素10Be:估算长江流域侵蚀速率的新方法

首次将宇宙成因核素10Be方法引入对长江流域地表侵蚀速率的研究.对长江流域东西子流域的对比发现,长江干流西部流域10Be含量普遍高于东部流域,这主要与长江上游高海拔导致的核素产生率高有关;西部流域主要支流10Be含量较低,反应了较高的侵蚀速率.通过金沙江、岷江—大渡河和沅江不同子流域的10Be含量与侵蚀速率关系模型,估算出岷江—大渡河流域平均侵蚀速率为300~500mm·ka-1,长江中下游地区的沅江—湘江流域侵蚀速率为30~50mm·ka-1.与水文数据推导的侵蚀速率相比而言,二者在数量级上基本一致,反映了宇宙成因核素10Be法在估算侵蚀速率方面的有效性和可靠性,为研究长江流域侵蚀与沉积问题提供了一种有效的定量方法.     

应用宇宙成因核素10Be和26Al估算剥蚀面的暴露时间及剥蚀速率和剥蚀厚度

宇宙成因核素10 Be和2 6Al的浓度记录着岩层剥蚀面的暴露时间和岩石剥蚀速率等信息。利用数学换算法分析影响10 Be和2 6Al浓度的因素 ,并利用10 Be和2 6Al的半衰期的近似倍数关系建立联立方程组 ,从理论上得到了年轻地质体中遭受快速埋藏的剥蚀面的暴露时间和剥蚀速率的估算公式。在此基础上 ,对整个剥蚀区不同位置剥蚀速率进行了分析。通过分析可以更准确地估算出整个剥蚀区不同位置的剥蚀厚度 ,从而可恢复剥蚀面的古地貌。     

Growth ages of ferromanganese crusts from the western and central Pacific： Comparison between nannofossil analysis and ^10Be dating

Based on results of nannofossil analysis and 10Be dating in ferromanganese crusts M1-1 and A1-1 (no nannofossils were found in it),from the western and central Pacific respectively,it is found that the crust growth ages from nannofossil biostrati-graphy agree well with those based on 10Be isotope analysis. Both crusts have three growth layers,and the oldest layer was deposited in Miocene at about 12.80 Ma. The maximum,minimum,and average growth rates of crust A1-1 (from the central Pacific) are 8.11,1.92 and 3.47 mm/Ma,and those of crust M1-1 (from the western Pacific) are 2.93,0.47,and 0.94 mm/Ma.     

厦门地区~7Be和~(210)Pb的大气沉降通量

7Be和210Pb是大气中天然存在的放射性核素.本文测定了2001年8月至2002年8月间厦门地区7Be和210Pb大气沉降通量,平均值分别为1.90和0.41Bqm-2d-1.对7Be和210Pb的沉降特征及其影响因素进行了探讨,表明降雨是影响沉降通量的主要因素,两个核素的沉降通量之间存在较好线性相关性.     

Laser step-heating ^40Ar/^39Ar dating on young volcanic rocks

An attempt was made to use CO_2 laser step-heating method to date the late Pleistocene basaltic groundmass (DF-2) from Tengchong volcanic field. Among the fourteen heating steps, ten define a good inverse isochron (MSWD = 1.4) with an age of 32.2 ± 7.1 ka (2 σ).The inverse isochron also shows that the initial argon isotopic ratio is 297.1±2.0 (2σ) which is the same as the atmospheric argon at the 2σ error level. Study indicates that it is a useful means to date young volcanic groundmass with low K content by using CO_2 laser step-heating ~(40)Ar/~(39)Ar method.     

ISEA reversed event in the Cretaceous Normal Super-chron （CNS）： ^40Ar／^39Ar dating and paleomagnetic results

ThegeomagneticfieldwasfoundtobeofnormalpolarityforalongtimeduringtheCretaceousbyHelsleyandSteiner[1]andthiswaslaternamedasCretaceousNormalSuperchron(CNS)[2].TheCNSlastedalmost37Ma(120—83Ma).Severalabnormalgeologicalevents,suchasanoceanicanoxicevent,alargenumberofvol-canismandglobalclimaticwarmingduringtheCNShavebeenreported[3—11].Thishasledtomanyquestionsbeingraised.IsittruethattheEarthsmagneticfielddidnotreverseatallintheCNS?Ifitdidreverse,howmanytimesandwhendidthishappen?Istherea…     

Concentration and seasonal variation of 10Be in surface aerosols of Lhasa,Tibet

Thirty samples of total suspended particles were collected at a site in western part of Lhasa, Tibet from August 2006 to July 2007. The ¹⁰Be concentrations were determined by Accelerator Mass Spectrometer (AMS). Analysis of correlation between ¹⁰Be con-centrations and meteorological factors revealed that the wet scavenging has little effect on ¹⁰Be. ¹⁰Be can be used as a proxy of transport processes of the upper atmosphere over the Tibetan Plateau. Analysis of correlation between ¹⁰Be concentrations and NCEP reanalysis data demonstrated that higher ¹⁰Be concentrations in spring were probably caused by the atmosphere exchange from stratosphere to troposphere during February to June. Lower ¹⁰Be concentrations during August to September were consistent with the synchronous lower O₃ values, suggestive of both ¹⁰Be and O₃ were probably influenced by the atmosphere exchange from troposphere to stratosphere.     

210Pb和137Cs法对比研究武汉东湖现代沉积速率

对采自东湖Ⅰ站和Ⅱ站的沉积物采用^210Pb和^137Cs相结合的方法测定沉积速率,^210Pb法测出东湖Ⅰ站和Ⅱ站的沉积速率为8．73mm／a和6．90mm／a,^137Cs测出东湖Ⅰ站和Ⅱ站的沉积速率为7．4mm／a和5．8mm／a．分析了两种方法测定结果差异产生的原因,并与以往的研究相对比,探讨东湖沉积速率空间分布的规律性,沉积速率变化与人类活动的关系、沉积速率与扰动的关系．     

+10-孪生素数问题及一个猜想

首次提出+10-孪生素数的概念,确定了1000以内+10-孪生素数的对数,并证明了在自然数列中+10-三孪生素数对的唯一性(定理6);最后提出了+10-孪生素数对有无限多的猜想.     

大块金属玻璃Zr41.2Ti13.8Cu12.5Ni10Be22.5在玻璃转变区轧制行为的研究

在玻璃转变区内对大块金属玻璃Zr41.2Ti13.8Cu12.5Ni10Be22.5以不同的轧制率(0％，12.5％，25%，37.5％和50%)进行轧制，用XRD、HRTEM、SEM、DSC和直流四探针法研究了轧制行为对其结构、表面形貌、热性能和相对电阻率的影响．研究结果表明，轧制后的试样仍然保持非晶相，但在非晶基体相中已经出现了一些有序团簇；第一晶化峰的起始温度降低，导致过冷液相区变窄，金属玻璃的热稳定性有下降的趋势；同时，随着轧制率的增加。室温表面相对电阻率表现为先上升、后下降的趋势．     

10Be/7Be implies the contribution of stratosphere-troposphere transport to the winter-spring surface O3 variation observed on the Tibetan Plateau

10Be/7Be is a stratospheric sensitive tracer.In this paper,measurements of 10Be/7Be and surface O3 from October 2005 to May 2006 at Mt.Waliguan (hereafter WLG,100.898°E,39.287°N,3810 m,a.s.l.),China global atmospheric watch (GAW) observatory,are introduced and used to investigate the stratosphere-troposphere transport (STT) and its impact on surface O3 on the Tibetan Plateau.The results show that the magnitude of STT is weak in winter,followed by strengthening from the end of winter to the middle of spring (from mid February to mid April) with large increases in 10Be,7Be,10Be/7Be and surface O3.At the end of spring (from the end of April to mid May in this paper),the STT weakened,and the continuous increase of surface O3 at WLG is produced by tropospheric photochemistry reactions.     

用MET分析NdFe_（10）V_2，NdFe_（10）V_2N_（0．5）Nd

用两格点分子场理论分析了ＮｄＦｅ１０Ｖ２，ＮｄＦｅ１０Ｖ２Ｎ０．５，ＮｄＦｅ１０Ｍｏ２，ＮｄＦｅ１０Ｍｏ２Ｎ０．５的饱和磁化强度随温度的变化关系，得到了分子场系数ｎＦＦ，ｎＦＲ和ｎＲＲ，计算结果与实验基本一致，计算结果表明，氮元素增大了交换场ＨＲ．     

一批考古,地质样品的^14C年龄数据报道

近年,应用~(14)C年龄测定法测定了一批广东、福建、海南等省的考古及地质样品的年龄,涉及多种类型的样品,对人类考古学、第四纪地质学及地貌学有一定的参考价值。     

水热法合成[(C3H7)2 NH2]4(H2O)4 Ge4S10及晶体结构分析

在二丙胺存在的条件下，Ge,S,Cd^2 或Mn^2 于150℃水热反应生成[(C3H7)2NH2]4(H2O)4Ge4S10单晶。单晶X射线衍射分析结果显示：该单晶为四方晶系，空间群I4（1）/amd；晶胞参数a=20.9275(4)A,c=11.3351(2)A。此晶体由分隔的[Ge4S10]^4-团族构成，每个[Ge4S10]^4-团族周围被四个丙二胺分子所包围。     

First-Principles Study of ZnO (10(1)0) non- polar Surface

The structure of the ZnO(10 0) non-polar surface is studied using first-principles slab calculations based on density functional theory(DFT). We find that the uppermost zinc atoms have a significant relaxation towards the bulk 0.328 ? ,and the Zn atoms in the second layer show a significant relaxation away from the bulk 0. 237 (A) ,allowing them to appear as surface atoms. For oxygen atoms a small relaxation 0. 146(A) is found. Which leading to a rotation angle 9. 2° of the Zn-O dimer on the surface. Results in excellent agreement with experiment have been obtained for the geometric and electric structures.     

芳香族有机物萘和蒽的非线性光学特性研究

采用波长为532nm、脉宽为35ps、重复频率为10Hz的Nd∶YAG锁模脉冲激光,运用前向简并四波混频技术研究芳香族有机物萘和蒽的三阶非线性光学特性,并探讨它们的非线性形成机制。结果测得萘和蒽的非线性折射率分别为3.50×10-10esu和4.45×10-10esu,响应时间分别为24.7ps和21.4ps。强场下的光克尔效应是萘和蒽产生非线性的主要机制。     

陆面岩石中生成的同位素10Be与26Al的实验室提取方法

宇生核素的样品采集需要考虑侵蚀速率,海拔高度,纬度,深度等因素,对于沉积地区的样品采集必须同时取表层样和埋藏样,并同时采集多个样品以减小随机性造成的误差;样品的处理采用离子交换法,是行之有效的方法,但需要有高纯度的石英,操作过程也必须谨慎,从而避免和消除污染,以提高宇生核素的提取率。     

河南省主要城市大气气溶胶中的TSP和PM10污染特性

大气气溶胶中的颗粒物(TSP、PM10)是大气污染物研究的主要对象．本文论述了我国北京、重庆、贵阳、济南、郑州等城市的大气气溶胶的特征一讨论了河南省东、西、南、北、中几个重要城市大气气溶胶中的TSP和PM10对环境空气的污染状况；分析了河南省城市环境大气气溶胶中TSP和PM10污染特性。