Studies of methane reforming with carbon dioxide on hexaaluminates

In this paper, a series of Sr1-xLaxNiAl11O19 catalysts were synthesized and their chemical and physical properties were investigated by XRD, UV-DRS, H-2-O-2 titration, TPR and Py-IR techniques. The experimental results show that the Sr1-xLaxNiAl11O19 catalysts have a magnetoplumbite structure and Ni ion is shared between tetrahedral and octahedral sites of the spinel blocks, and the amount of nickel ions in the tetrahedral environment increases with the increase of x value in Sr1-xLaxNiAl11O19. The TPR study revealed that the reducibility of the series of the catalysts depends strongly on the substitution value x, that is, a low temperature peak appears for samples without substitution, in case of samples with x = 1 high temperature peak appears, and for samples with 0

六铝酸盐催化剂上甲烷与二氧化碳重整反应的研究

合成了具有磁铅石结构的Ｓｒ１－ｘＬａｘＮｉＡｌ１１Ｏ１９系列催化剂，并用ＸＲＤ、ＵＶ－ＤＲＳ、Ｈ２－Ｏ２滴定及Ｐｙ－ＩＲ等方法对其体相及表面性质进行了表征，考察了甲烷与二氧化碳重整反应活性及积炭性．结果表明，Ｌａ３＋离子能够同晶取代Ｓｒ２＋离子进入催化剂晶格内部，使催化剂的结晶度提高，还原性降低，同时降低了催化剂表面的酸性，有助于提高催化剂的抗积炭能力.

目前俄罗斯图书馆界对《ББК》分类法中马列主义及相关类目的修订处理

<正>1992至1993年间,笔者两次赴俄罗斯莫斯科及毗邻地区访问并工作.在前后七个月的时间内,有机会考察了解俄国图书馆界的一些情况.在与俄方交谈中得知,目前俄国各图书馆正根据“有关文件精神”对前苏联的图书分类法《ББК》的各种版本进行修订.笔者希望阅读这“有关文件”的要求被委婉谢绝后,却有幸借到莫斯科郊区城市谢尔布霍夫某一基层群众图书馆正在实施修改工作用的一册手改本《ББК》分类法.虽然这是用于群众图书馆的一种简本,对于了解苏联解体后俄罗斯政治变化对俄图书分类法

Identification of vhhP2, a novel genetic marker of Vibrio harveyi, and its application in the quick detection of V. harveyi from animal specimens and environmental samples

Aims: To investigate the species-specific prevalence of vhhP2 among Vibrio harveyi isolates and the applicability of vhhP2 in the specific detection of V. harveyi from crude samples of animal and environmental origins. Methods and Results: A gene (vhhP2) encoding an outer membrane protein of unknown function was identified from a pathogenic V. harveyi isolate. vhhP2 is present in 24 V. harveyi strains isolated from different geographical locations but is absent in 24 strains representing 17 different non-V. harveyi species, including V. parahaemolyticus and V. alginolyticus. A simple polymerase chain reaction method for the identification of V. harveyi was developed based on the conserved sequence of vhhP2. This method was demonstrated to be applicable to the quick detection of V. harveyi from crude animal specimens and environmental samples. The specificity of this method was tested by applying it to the examination of two strains of V. campbellii, which is most closely related to V. harveyi. One of the V. campbellii strains was falsely identified as V. harveyi. Conclusions: vhhP2 is ubiquitously present in the V. harveyi species and is absent in most of the non-V. harveyi species; this feature enables vhhP2 to serve as a genetic marker for the rapid identification of V. harveyi. However, this method can not distinguish some V. campbellii strains from V. harveyi. Significance and Impact of the Study: the significance of our study is the identification of a novel gene of V. harveyi and the development of a simple method for the relatively accurate detection of V. harveyi from animal specimens and environmental samples.

Recent 2000-year geological records of mud in the inner shelf of the East China Sea and their climatic implications

AXIS(14)C dating and grain-size analysis for Core DD2, located at the north of the Yangtze River-derived mud off the Zhejiang-Fujian coasts in the inner shelf of the East China Sea, provide us a high-resolution grain-size distribution curve varying with depth and time. Data in the upper mud layer of Core DD2 indicate that there are at least 9 abrupt grain-size increasing in recent 2000 years, with each corresponding very well with the low-temperature events in Chinese history, which might result from the periodical strengthening of the East Asian Winter Monsoon (EAWM), including the first-revealed maximum temperature lowering event at around 990 a BP. At the same time, the finer grain size section in Core DD2 agrees well with the Sui-Tang Warming Period (600-1000 a AD) defined previously by Zhu Kezhen, during which the climate had a warm, cold and warm fluctuation, with a dominated cooling period of 750-850 a AD. The Little Ice Age (LIA) can also be identified in the core. It starts around 1450 a AD and was followed by a subsequent cooling events at 1510, 1670 and 1840 a AD. Timing of these cold events revealed here still needs to be further verified owing to some current uncertainty of dating we used in this study.

Trace metal concentrations in suspended particles, sediments and clams (Ruditapes philippinarum) from Jiaozhou Bay of China

Suspended particulate matter (SPM), sediments and clams were collected at three sites in Jiaozhou Bay to assess the magnitude of trace metal pollution in the area. Metal concentrations in SPM (Cu: 40.11-203; Zn: 118-447; Pb: 50.1-132; Cd: 0.55-4.39; Cr: 147.6-288; Mn: 762-1670 mu g/g), sediments (Cu: 17.64-34.26; Zn: 80.79-110; Pb: 24.57-49.59; Cd: 0.099-0.324; Cr: 41.6-88.1; Mn: 343-520 mu g/g) and bivalves (Cu: 6.41-19.76; Zn: 35.5-85.5; Pb: 0.31-1.01; Cd: 0.51-0.67; Mn: 27.45-67.6 mu g/g) are comparable to those reported for other moderately polluted world environments. SPM showed a less clear pattern. Metal concentrations in sediments displayed a clear geographical trend with values increasing with proximity to major urban centers. The clams (on dry weight) showed a complex pattern due to the variability introduced by age-related factors. Cd showed an apparent reverse industrial trend with higher concentrations in clams collected at distant stations. Zn, Pb and Mn showed no clear geographical pattern, whereas Cu increased in the clams collected in the most industrialized area. In addition, the bioaccumulation factors (BAF) were calculated. The result indicated that the studied Ruditapes philippinarum in Jiaozhou Bay possessed different bioaccumulation capacities for Cd, Zn, Cu, Pb and Mn, and Cd, Zn had a relatively high assimilation of those metals from sediment particles. A significant relationship with clam age was observed for Zn (positive) and Cu (negative) suggesting different physiological requirements for both metals with age. Trace metal concentrations measured in the tissue of the investigated clam were in the range considered safe by the WHO for human use.

CAD/CAM一体化的应用与开发

文章概要地介绍了CAD/CAM系统的结构、CAD/CAM一体化的工作流程,提出实现CAD/CAM一体化的几种可行方案,并以具体零件机床为例,给出从设计到数控编程和机床加工的全过程。

通过第一性原理计算研究内地核的结构与成分

The determination of the composition and structure of the Earth’s inner core has long been the major subject in the study of the Earth’s deep interior. It’s widely believed that the Earth’s core is formed by iron with a fraction of nickel. However, light elements must exist in the inner core because the earth core is less dense than pure iron-nickel alloy (~2-3% in the solid inner core and ~6-7% in the liquid outer core). The questions are what and how much light element is there in the iron-nickel alloy. Besides the composition, the crystal structure of the iron with or without light element is also not well known. According to the seismological observations, the sound waves propagate 3-4% faster along the spin axis than in the equatorial plane. That means the inner core is anisotropic. The densest structure of iron-nickel alloy should be h.c.p structure under the very high pressures. However, the h,c,p structure does not propagate waves anisotropic ally. Then what is the structure of the iron-nickel alloy or the iron-nickle-light element alloy. In this study, we tried to predict the composition and the structure of the inner core through ab initio calculation of the Gibbs free energy, which is a function of internal energy, density and entropy. We conclude that the h.c.p structure is more stable than the b.c.c structure under high pressure and 0 K, but with the increase of temperature, the free energy of the b.c.c structure is decreasing much faster than the h.c.p structure caused by the vibration of the atomics, so the b.c.c structure is more stable at high temperatures. With the addition of light elements (S or Si or both), the free energy of b.c.c. decreases even faster, about 3at% of Si not only explains why the inner core is about 2-3 % lighter than the iron-nickle alloy, but also reasons why the inner core is anisotropic, since the b.c.c. structure becomes more stable than the h.c.p structure at 5500-6000K and b.c.c. is anisotropic in propagating seismic waves. Therefore, we infer that the inner core of the earth is formed by b.c.c iron and a fraction of nickel plus ~3at.% Si, with a temperature higher than 5500K, which is consistent with the studies from other approaches.

岩溶生态系统脆弱性剖析

生态系统的脆弱性评价对于生态系统管理具有重要作用。在分析岩溶生态系统脆弱性特征和影响因素的基础上,构建了针对岩溶自然系统的脆弱性评价指标体系,涵盖了岩溶生态系统的结构脆弱性、生态过程脆弱性、生态功能脆弱性和人为胁迫脆弱性4个方面,评价指标分别是结构稳定性、多样性生境、能量利用和积累、直接使用价值、石漠化程度和速率等。以不同类型的原生岩溶生态系统的生态基准值作为比较基础,评价系统将现有的退化岩溶生态系统的脆弱性划分为轻微脆弱、中度脆弱、重度脆弱以及系统崩溃4级

湖泊沉积物碳氧同位素和介形虫Li/Ca比值与古环境重建

了解过去是认识现在和预测未来的基础。晚全新世是PAGES研究的目标时段之一。寻找和解译最近2000年连续、高分辨率自然记录是古气候研究的热点与难点。本项研究有针对性地选择程海、草海和青海湖开展湖泊沉积物环境记录的精细研究，结合14C、210Pb和137Cs定年，系统探讨了碳酸盐碳氧同位素、纤维素碳氧同位素、有机质碳同位素以及介形虫壳体Li/Ca比值指标的古环境指示意义。 通过研究，本论文取得了如下成果和新的认识： 1. 建立了一套有效的四阶段湖泊沉积物有机质纤维素提取方法（5%NaOH碱洗、5%HCl酸洗、亚氯酸钠和冰醋酸混合溶液漂白以及17.5%NaOH碱洗），红外光谱鉴定提取物为纯的α-纤维素，表明该实验方法是可行的，为今后广泛开展湖泊沉积物纤维素稳定同位素研究打下了坚实基础。 2. 多指标综合辨识了程海和草海沉积物碳酸盐主要是自生碳酸盐。程海和草海沉积物有机质C/N比值结合有机质碳同位素结果表明两湖的有机质分别源于水生植物藻类和大型水草。程海和草海沉积物碳酸盐含量主要反映了湖区温度的变化。 3. 程海、草海沉积物碳酸盐与青海湖沉积物介形虫壳体氧同位素组成均反映了湖区降水/蒸发比。降水/蒸发比大的湿润期，碳酸盐δ18O值小；降水/蒸发比小的干旱期，碳酸盐δ18O值大。程海沉积物碳酸盐碳同位素组成影响因素复杂，除了受大气与湖水之间的CO2交换影响外，还受水生植物光合/吸收作用的影响；草海沉积物碳酸盐碳同位素组成更大的变化范围，反映了湖区水生植物光合/吸收作用的影响，其异常的正值可能指示了湖区细菌参与有机质碳同位素分馏过程。 4. 利用草海沉积物有机质纤维素氧同位素定量恢复了湖水氧同位素组成变化。在此基础上，结合碳酸盐氧同位素组成初步恢复了草海地区过去500年来温度变化历史：草海地区在过去500年明显存在四个冷期，包括1550－1610年，1670－1730年，1770－1870年和1890－1920年冷期，其中前三个发生在传统意义上的现代小冰期时段。与其它记录研究结果的一致性表明纤维素氧同位素结合碳酸盐氧同位素是恢复古温度变化的最有效途径之一，同时也为现代小冰期在中国西南地区的存在提供了湖泊沉积学方面的证据。 5. 不同类型水生植物湖泊，湖泊沉积物有机质δ13C值对湖泊初级生产力变化的响应过程不同。大型水草为主的湖泊（草海），其沉积物有机质δ13C值随湖泊生产力的增大呈现增加的变化趋势；藻类为主的湖泊（程海），其沉积物有机质δ13C随湖泊生产力的增大呈现减小的变化趋势，藻类易降解是导致δ13C值随湖泊生产力的增大呈现减小变化趋势的主要原因。 6. 程海沉积物碳酸盐和有机质碳同位素组成的正相关变化以及草海沉积物碳酸盐和有机质碳同位素组成的负相关变化.表明湖泊生产力变化并不是导致碳酸盐和有机质碳同位素正相关变化的主要原因，湖泊水生植物类型以及湖泊大小均起着重要作用。湖泊沉积物碳酸盐与有机质之间的碳同位素分馏（△δ13C）是一种有效的湖泊生产力指示剂，即使是在有微生物参与有机质碳同位素分馏过程的草海，△δ13C值也反映了湖泊生产力的变化过程。 7. 青海湖沉积物单一种属介形虫壳体胖真星介（Eucypris inflata）Li/Ca比值与气象记录以及邻近地区都兰和祁连山树轮宽度指数恢复的古温度变化序列的对比研究揭示，介形虫壳体Li/Ca比值与温度呈明显的负相关变化（Li/Ca比值高，温度低；Li/Ca比值低，温度高），表明介形虫壳体Li/Ca比值是一种有效的古温度代用指标。 8. 青海湖沉积物单一种属介形虫壳体胖真星介（Eucypris inflata）Li/Ca比值、氧同位素与反映太阳活动的大气14C含量和冰芯10Be含量的一致性变化表明青海湖地区温度和降雨量的同步变化主要受太阳活动控制。