Luminescence chronology of ＂Old Red Sand＂ in Jinjiang and its implications for optical dating of sediments in South China

A weathered deposit in South China is widespread on the coastal areas of Fujian and Guangdong provinces, China. This deposit consists of slightly cemented, medium- to fine-grained sands, and is characterized by its colors of red, brown red, light reddish brown or dark yellowish orange, and is usually called ＂Old Red Sand＂. The uncertainty in its formation age has been a major obstacle to the study of this type of deposit. In this paper, optically stimulated luminescence （OSL） techniques were used to date the ＂Old Red Sand＂ sediments from Jinjiang, Fujian Province, China. The effect of the geochemical behavior of uranium and thorium in sediment during chemical weathering on estimation of annual dose was investigated. The results show that the change in annual dose due to weathering poses a major problem for the optical dating of such weathered sediments. The optical dating of these weathered deposits will produce erroneous ages if average annual dose during burial cannot be correctly estimated. For the profiles studied, the OSL dates obtained on samples from the upper part do not represent the burial age of the samples. It is highly likely that they are underestimated due mainly to the accumulated radioactive elements as a result of chemical weathering. It is concluded that changes in annual dose due to chemical weathering must be considered when dating similar sediments in South China. With a detailed analysis of the OSL dating results, the chronology of the marine terraces in this area was suggested. The lowest terrace was formed at -3.5 ka and the second terrace was dated to -74 ka. The age of the highest terrace may not be established accurately, but is inferred to be older than the apparent OSL date of -77 ka and so is the Paleolithic artifacts from it.     

Environmental changes reflected by n-alkanes of lake core in Nam Co on the Tibetan Plateau since 8.4 kaB.P.

The n-alkanes are extracted from NMLC-1 core that was drilled in the Nam Co, central Tibet. They are measured by using Gas Chromatography and Mass Spectrometry （GC/MS） for componential and quantitative analyses. According to the constructed depth-age model, the component and concentration of n-alkanes, together with total organic carbon （TOC）, total nitrogen （TN） and carbonate are used to elucidate palaeoenvironmental changes of Nam Co during the past 8.4 ka. The results indicate that Holocene environment performs three stages in the lake area. In the stage of 8.4-6.7 kaB.P., it was warmer while precipitation slightly increased. This stage was ended by an obvious cold/dry event. During 6.7-5.8 kaB.P., temperature increased rapidly and reached its maximum values at about 6.0 kaB.P. The environments were warm/wet optimum for the blooming of terrestrial plants and submerged aquatic plants. After that, temperature decreased continuously and showed the lowest values at about 3.0 kaB.P. From 2.9 kaB.P, to the present, temperature rose again but alternated with cold and warm. The lake area tended to be dry after 1.4 kaB.P. During 600-400 aB.P., the environmental feature was the reflection of ＂Little Ice Age＂.     

Preliminary research on Megalake Jilantai-Hetao in the arid areas of China during the Late Quaternary

We identified geomorphological, sedimentary and biological evidence of high lake levels around the current Jilantai Salt Lake through field investigations and through analyses of regional remote sensing images. There are four groups of shorelines at elevations of around 1060, 1050, 1044 and 1035 m a.s.l., being 37, 27, 21 and 12 m above the current salt lake surface, respectively. Littoral deposits of sand and gravels are found at elevations between 1070 and 1080 m a.s.l., 47 to 57 m higher than the current salt lake surface, although palaeoshoreline landforms are only preserved at several sites. At Herimuxini, on the northern margin of the Ulan Buh Desert, typical lacustrine sediments and sand-gravel littoral deposits also occur at elevations of 1080 m a.s.I, and below. A 11-km-long typical spit extends eastward from this shoreline gradually reducing in elevation from 1050 to 1035 m a.s.I. In some sand-gravel quarries along the southern bank of the Yellow River on its Great Bend, such as those located near the Hydrological Gauge Station and Shilazhao Town, shoreline features were identified. Littoral deposits overlying the alluvial-diluvial layers occur in a sand quarry near Balagong in Hangjin County. There are also beachrock and littoral deposits preserved on the cut-and-built terraces at several sites along the southern piedmont of Langshan-Yinshan Mountains. In addition, a profile revealing subaqueous delta sediments was identified near Wuhai, where the Yellow River enters the basin. Typical lake sediments also exist at the Togtoh Platform on the eastern end of the Hetao Plain. Aquatic Mollusk shells are common in the littoral deposits, including several species of Corbicula, Radix lagotis, R. xauricularia and Gyraulus convexiusculus. Ostracode shells can also be identified in finer sediments. Typical ver- tical prograding sequences are evident in outcrops where lacustrine sediments were well preserved. Wave-rolled cobbles and beachrock are very commonly preserved on the top of profiles in the embankments at     

Crystal structure and surface photo-electric property of Mn（Ⅱ） coordination supramolecules

Two Mn（Ⅱ） coordination supramolecules, [Mn2（C8HTO2）4（phen）2（p-H20）] （1） and [Mn2（btec）（phen）2（H2O）6]·2H2O （2） （phen=1,10-phenanthroline, H4btec=1,2,4,5-benzenetetracarboxylic acid）, were synthesized by hydrothermal method. The crystal structures of the complexes were determined by X-ray single crystal diffraction. The result indicates that （1） and （2） are both binuclear Mn（Ⅱ） complexes. The existence of hydrogen bonds makes the binuclear complexes become further connected to coordination supramolecules, which possess 1D and 3D infinite structures respectively. The complexes were identified by IR, UV-Vis, surface photovoltage spectrum （SPS） and field-induced surface photovoltage spectrum （FISPS）. The results of SPS for the complexes indicate that they both exhibit positive surface photovoltage response bands in the range of 300-600 nm. The SPS phase spectrum and FISPS of complexes indicate that they show certain p-type semiconductor characteristic. However, the intensity, position and number of the SPV response bands are different obviously. The difference of the SPV response bands is mainly attributed to the different structures of the complexes and the different coordination environment of Mn（ll） in the two complexes. This paper discusses the action of hydrogen bonds in the construction of the supramolecule and the change on the surface photovoltage of complex in different coordination environment.     

Spatial and temporal variation in magnetic properties of street dust in Lanzhou City, China

Urban environmental problems are of increasing concern. Lanzhou is a large industrial city in Northwest China. Street dust samples representing different temporal and spatial scales were collected for magnetic properties study. Magnetic measurements indicate a high concentration of magnetic minerals in Lanzhou street dust, dominated by pseudo-single domain （PSD） magnetite. The concentration of magnetic materials is distinctly high in winter and spring, low in autumn. Similarly, higher concentrations associated with heavy industry, concentrated residential development, and vehicular traffic suggest mixed contributions of magnetic material from both anthropogenic and natural sources. XIf and SOFT% are effective magnetic parameters that denote seasonal differences among magnetic properties in street dust, convenient and economical methods for monitoring street dust pollution.     

High quality p-type ZnO film growth by a simple method and its properties

P-type ZnO：N films have been grown successfully by chemical vapor deposition （CVD） using Zn4（OH）2（O2CCH3）6·2H2O as the solid source material and ZnNO3 as the doping source material. XPS, Hall-effect measurement and PL spectra were employed to analyze the structural, electrical and optical properties and study the influence of substrate temperature on the film. Results showed that with a lower substrate temperature, the film exhibited p-type conduction and its resistivity decreased when the substrete temperature increased. When the substrates temperature was 400℃, p-type ZnO films were obtained with carrier concentration of ＋5.127×10^17 cm^-3, resistivity of 0.04706 Ω· cm and Hall mobility of 259 cm^2/（V·s）; they still exhibited p-type conduction after a month. When the substrate temperature was too high, the film was transformed from p-type to n-type conduction.     

北京地区表土磁性特征及其环境意义

发展便捷快速的污染检测技术是当今环境研究的需要. 能够有效地区分环境背景值与人为造成的污染是新的检测技术所必需的. 近年来, 磁学技术因其测量快速、简便的特点, 正在逐步应用于城市环境污染监测中. 城市或郊区的表土中磁性矿物来源复杂, 能否通过磁学测量识别自然和人类活动的来源是土壤磁监测技术成为环境污染监测有效手段的关键所在. 通过对北京城郊各区县地表0~10 cm的表土层环境磁学性质的测量, 初步获得了北京地区大尺度的表土磁性分布特征, 对各区县表土的磁学性质与土壤母质、人类活动、地形地貌的相互关系进行了探讨. 实验结果表明, 在北京西北部和西南部的山地地区, 表土的磁学性质主要受自然环境(地形地貌和母岩)的控制, 磁性较强, 大部分表土的磁化率(χ_lf)大于4×10–6 m3/kg, 为较粗颗粒的单畴(SD)或多畴(MD)亚铁磁性矿物; 在北京中部和东部的山间谷地以及平原地区, 表土的磁性较弱; 而在一些工厂和交通要道附近, 受到人类活动的影响, χ_ARM/SIRM和χ_ARM/χ_lf值明显增高, 为较细颗粒的单畴-假单畴(SD-PSD)亚铁磁性矿物. 在应用环境磁学参数对表土污染进行检测时, 尤其是区分强磁性的土壤母质发育的表土和严重污染的表土时, χ_ARM/SIRM和χ_ARM/χ_lf比χ_lf, χ_ARM和SIRM更为敏感.     

Effects of ytterbium on outward K<Superscript>+</Superscript> currents in NIH3T3 cell

Using the whole cell patch-clamp technique, we observed the outward K+ currents and studied for the first time the effects of Yb3+ on the currents and kinetics of activation and inactivation in non-excitable NIH3T3 cell. Our results show that the outward K+ currents were promoted with increasing concentration of Ca2+ in pipette solution and saturated at the concentration of 100 μmol/L Ca2+. Yb3+ in bath solution inhibited the currents in a concentration-dependent manner. At the concentration of 1 μmol/L, Yb...     

Vesicle-related OsSEC27P enhances H<Superscript>+</Superscript> secretion in the iron deficient transgenic tobacco root

Iron is an essential micronutritional element for plants. In addition to the iron uptake mechanism Strategy I and Strategy II, the vesicle transport process was also found to participate in iron uptake and homeostasis. Herein, a new iron deficiency induced OsSEC27P gene was isolated and investigated in both its localization and its function in transgenic plants. The vesicle-related protein OsSEC27P may play a potential role in enhancing H⁺ secretion in roots under the iron deficiency conditions.     

攀枝花苏铁（Cycas Panzhihuaensis L．Zhou et S．Y．Yang）受精作用及胚胎发生的研究

报道了C .panzhihuaensis的受精作用 ,胚胎发生和分化 .人工授粉 15d后 ,颈卵器开始发育 ,7月底到 8月中旬受精作用发生 ,受精过程有三种情况 :即球形精细胞或蠕虫状精子从卵顶部进入卵细胞内 ,纤毛带遗弃在颈卵器室中 ,或具纤毛带的精细胞进入卵中 ,纤毛带遗弃在卵细胞质内 ,精卵核融合 .胚胎发生经历较长的游离核原胚阶段 ,游离核原胚形成细胞后 ,幼胚开始分化 .受精后的雌配子体发育成胚乳 .成熟的胚由子叶 (二片 )、胚芽、胚根、胚根鞘及螺旋折叠的胚柄组成