Evaluation of a sequential extraction for the speciation of thorium in soils from Baotou area, Inner Mongolia

Sequential extraction procedures were widely applied for speciation of radioactive elements. In this study, the sequential extraction procedure developed by Martinez-Aguirre was employed for quantification of different chemical forms of thorium in the soil. The total amount of thorium in contaminated soil was much higher by four-fold than the local background value. The soil properties affect the amount of thoriurn and distribution of fractions in contaminated soil. Results showed that the proportion of thorium in soils from Baotou was found as the residual fraction (F5 + F6) > absorbed fraction (F3), coprecipitated fraction (F4) > carbonates fraction (172) and exchangeable fraction (F1) that could be available to plants. The recovery, calculated by ratio of the sum of the six fractions to the pseudo-total content of thorium, was in the range from 96% to 110%. A comparison was carried out between the sequential extraction and the single extraction to evaluate the selectivity of the extractants. It was found that the amount of thorium of absorbed fraction (H) was higher in the single extraction than that estimated in the sequential extraction, possibly duo to transform of the labile form. While for non-residual fraction analysis, the single extraction scheme was a desirable alternative to the sequential extraction procedure.

Surface-enhanced Raman scattering studies on aggregated silver nanoplates in aqueous solution

Four different sizes of citrate-protected silver nanoplates with the corresponding in-plane dipole resonance band at 530, 619, 778, and 858 nm, respectively, are synthesized for surface-enhanced Raman scattering (SERS) study. Their aggregation behaviors are monitored by use of UV-vis spectroscopy. During the aggregation process, a marked red shift of the in-plane dipole resonance of silver nanoplates is observed, whereas other resonance modes of them only have small alterations in the site or intensity. Aggregated silver nanoplates can serve as active SERS substrates with an enhancement factor of about 4.5 x 10(5) using 2-aminothiophenol as a probing molecule. The SERS performance of silver nanoplates is even superior to the commonly used Lee-Meisel silver colloid, making them very attractive for SERS applications.

红外光谱法研究交联淀粉的退化行为

用红外光谱研究了交联淀粉的退化过程,结果表明,交联淀粉具有与原淀粉大分子类似的退化过程,即淀粉大分子临近的链段间形成双螺旋局部有序化结构,再进一步规则地排列成结晶有序的结构.由于交联键的限制,交联淀粉的有序化过程相对较慢、程度较低,而且当交联度过高时无法形成结晶结构.

A novel dimer - Heteropolytungstate with a vanadium atom as the centre - Synthesis and structural characterization of (H3O)(4)[VW12O40Na (H2O)(4)](2)

A novel dimer-tungstovanadate, (H3O)(4)[VW12O40Na (H2O)(4)](2), was hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, IR spectra, TGA-DSC thermal analysis and polarograpy. The yellowish crystal crystallized in the triclinic system, space group P1, a = 1.464 5(3) nm, b = 1.468 6(3) nm, c = 1.411 1(3) nm, alpha = 111.82(2)degrees, beta = 93.17(3)degrees, gamma = 117.47(3)degrees, V = 2.210 6(8) nm(3), Z = 1, D-c = 4.552 g . cm(-3), lambda (Mo K alpha) = 0.071 073 nm, mu = 31.402 mm(-1) F(000) = 2 6481 R = 0.078 0. The title compound consists of two Keggin structure units linked together with two hydrated sodium cations to form a dimer with a porous structure with the pore dimension of 0.766 nm X 0.778 5 nm.

Crystal structure and crystallinity of poly(aryl ether biphenyl ether ketone ketone)

The crystal structure of poly(aryl ether biphenyl ether ketone ketone) (PEDEKK) was determined to comprise a two-chain orthorhombic unit cell with dimensions a 0.778 nm, b = 0.606 nm and c = 2.375 nm by using wide-angle X-ray diffraction (WAXD). According to the orthorhombic system, the 12 reflections of this polymer were indexed. The crystallite size increases with increasing the crystallization temperature. The results of the degree of crystallinity (W-c,W-x) calculated from WAXD were compatible with those from density (W-c,W-d) and calorimetry (W-c,W-h) measurements.

INFRARED SPECTRA AND CRYSTAL STRUCTURE OF BIS-(DIMETHOXYLPHOSPHATO) COPPER

The title complex has beep synthesized by the reaction of CaCl2, with trimethyl phosphate. Its Infrared spectra from 4000 to 100 cm(-1) measured. The assignment of acme absorption bands was discussed. It is found that the stretching vibrations of bridge groups O-P-O are divided into two groups according to their bond length. The crystal structure of the complex boa been determined from single crystal K-ray diffraction data. The crystals belong to monoclinic system, space group P2(1)/c with cell parameteras, a = 1,0704(4), b = 0.5093(2), c = 1.9737(6)nm, beta = 96.23(3)degrees, V = 1.0696(6)nm(2), Z = 4, final R = 0.044. Copper ion is coordinated to five Rimester oxygen atoms to form a distorted square pyramid. The adjacent copper ions are connected by symmetric and non-symmetric bridge groups of O-P-O, forming an infinite one-dimensional chain coordination polymer.

{MoOS_3Cu_3(PPh_3)_3Cl}的合成及晶体结构

本文合成并测定了{MoOS_3Cu_3(PPh_3)C1}的晶体结构,簇合物属正交晶系,空间群为P_(212121)晶胞参数:a=12.833(5)×10~(-10)m,b=17.552(5)×10~(-10)m,c=22.778(7)×10~(-10)m;Z=4。结构用直接法解出,经最小二乘法修正,偏离因子R=0.069.

双-(磷酸二甲酯)合铜的红外光谱与晶体结构

合成了单元化学式为-Cu[(CH_3O)_2PO_2]_2-的铜(Ⅱ)与磷酸二甲酯的配位聚合物。测定了4000—100cm~(-1)谱区内的红外光谱,讨论了某些谱带的归属,解释了配位化合物形成后的光谱变化。由单晶X-射线衍射法确定此配合物的晶体属单斜晶系,空间群为P2_1/c,晶胞参数a=1.0704(4),b=0.5093(2),c=1.9737(6)nm;β=96.23(3)°;V=1.0696(6)nm~3;Z=4.M=313.5,F(000)=636e,D_c=1.943g·cm~(-3)。铜与五个配体中的五个非酯氧配位成四角锥体,相邻两铜原子以对称的“O—P—O”桥和不对你的“O—P—O”桥相连,形成一维链状配位聚合物。

应用PCR-DGGE技术分析长江口低氧区和黄海冷水团的细菌群落组成

利用PCR-DGGE技术对长江口外低氧区海域和黄海冷水团海域的细菌群落组成进行了分析。 长江口外低氧区海域的细菌群落组成分析结果为：对获得的25条DGGE条带进行了克隆、测序，所得到的序列进行了系统进化分析（细菌16S rRNA基因V3区序列），分别归属于4个细菌类群：变形菌门(Proteobacteria)、拟杆菌门(Bacteroides)、厚壁菌门(Firmicutes)和蓝细菌门(Cyanobacteria)。其中有16条分别与变形细菌亚群的γ和δ-Proteobacteria相似。通过时空分析发现，低氧水体的细菌群落组成与非低氧水体的组成是不同的。低氧水体的优势菌群是拟杆菌门(Bacteroides)中的Flavobacteria。 黄海冷水团海域的细菌群落组成和优势菌群分析结果为：细菌16S rDNA V3区特征片段经DGGE分离、条带切割，共得到24条DGGE条带，克隆、测序后，将所得序列进行系统进化分析，分别归属于2个细菌类群：变形细菌门(Proteobacteria)和拟杆菌门(Bacteroides)。在24条序列中有16条分别与变形细菌亚群的γ和δ-Proteobacteria相似，有5条与拟杆菌门相似。通过时空分析发现，10月份（冷水团存在期），冷水团内部水体的细菌群落组成包括γ-Proteobacteria、δ-Proteobacteria和Bacteroides，而冷水团外部的水体的细菌群落组成包括γ-Proteobacteria和Bacteroides。冷水团内部水层的优势菌群为γ-Proteobacteria。4月份虽然冷水团没有形成，但是所调查的海域海水温度都不高，在7℃－12℃范围内，所以4月份所有站位，不管是底层的还是总的的细菌群落组成都与10月份冷水团内部（海水温度低于10℃）水体的相同，与10月份冷水团外部（海水温度大于19℃）的不同。

种植青海大黄叶中矿物质元素研究

青海地道中药材“西宁大黄”，野生资源濒临枯竭，人工种植规模不断扩大。定期采集了青海西宁及邻近地区两年生种植大黄叶，分析测试了其矿物质元素，为西宁大黄资源的可持续开发和利用提供科学依据。研究表明，种植大黄叶中矿物质营养元素的协同性以及有效蓄积对大黄的生长具有重要意义。钠元素在大黄叶中的有效蓄积以及环境中水分的及时补给对种植大黄的生长具有重要作用。

具有加速度反馈的机器人伺服系统鲁棒性控制

本文提出了利用加速度反馈实现机器人伺服系统的鲁棒性控制。作者从动力学及工程角度详细地讨论分析了该方法，证明了该方法对机器人的强耦合及复惯量的抑制作用。并具体实现了利用此方法构成的系统且给出了详尽的实验数据证实了该方法的有效性。另外，介绍了加速度计的使用方法。

当代大学生消费价值观与消费行为的调查研究——北京大学生中的消费主义倾向及有关影响因素研究

The aim of this study was to investigate consuming values and behaviors in Chinese college students, to detect the factorial structure in consuming values, and to explore possible determinants of those values and their effects on consuming behaviors. A total of 778 students from various universities in Beijing were investigated with questionnaire survey. The main results and conclusions are as follows: (1) College students were basically satisfied with their current life and study conditions in university, and their main pressures or stresses were from their studies. They were highly motivated in the development of their academic and life careers, and also valued the importance of family and having children in the future. About 11% of the students had pressures due to less favorable financial conditions of their families. (2) Five basic consuming values were found among college students, namely, “industrious and thrifty-aimed value”, “status and brand-aimed value”, “personal and unique-oriented value”, “relation-aimed value”, and “autonomous-aimed value”. The “industrious and thrifty-aimed value” stands for the traditional consuming values in the culture, and the “status and brand-aimed value” shows an explicit tendency of consumerism. The other three consuming values had moderate relations with both of the two values. (3) There was a high negative correlation between the first two values, which showed both a general acceptance and the main trend of “industrious and thrifty-aimed value” among the students. The basic “status and brand-aimed value” was shown among 3.3% of the students. (4) The consuming values were significantly correlated with life values, indicating that consuming values could be in consistence with or be determined by basic life values. The “industrious and thrifty-aimed value” and the “autonomous-aimed value” were shown as collectivistic values, while the “status and brand-aimed value” and “relation-aimed value” were shown as individualistic values. (5) Consuming values had significant influences on consuming behaviors. (6) The demographic factors such as financial conditions of parents, children of number in family, urban-rural location of family, gender, age, and campus culture could affect consuming values and consuming behaviors of college students in both direct and indirect ways.