低扩散系数对Pd77 Cu6 Si17合金易非晶化的影响

采用激光熔凝技术,研究了Pd₇₇Cu₆Si₁₇合金快速凝固组织的演变规律.研究表明:随着生长速度的增大,Pd₇₇Cu₆Si₁₇合金晶体生长组织形貌发生了Pd₃Si枝晶+共晶-ξ枝晶+共晶-共晶团簇-规则共晶-非晶的转变;共晶失稳即非晶形成的临界生长速度为6 mm/s,最小层片间距为35 nm.通过与Al-25 wt%Sm,Al-32.7 w     

Compact and tunable mid-infrared source based on a 2 μm dual-wavelength KTiOPO4 intracavity optical parametric oscillator

Using a double resonant KTiOPO₄ (KTP) intracavity optical parametric oscillator operating at degenerated point of 2 μm, we demonstrate a unique mid-infrared source based on difference frequency generation in GaSe crystal. The output tuning range is 8.42-19.52 μm, and a peak power of 834 W for type-I phase matching scheme and 730 W for type-II phase matching scheme are achieved. Experimental results show that this oscillator is a good alternative to the generator of a compact and tabletop mid-infrared radiation with a widely tunable range.     

Improved understanding of petroleum migration history in the Hongche fault zone,northwestern Junggar Basin (northwest China): Constrained by vein-calcite fluid inclusions and trace elements

Calcite veins and cements occur widely in Carboniferous and Permian reservoirs of the Hongche fault zone, northwestern Junggar Basin in northwest China. The calcites were investigated by fluid inclusion and trace-element analyses, providing an improved understanding of the petroleum migration history. It is indicated that the Hongche fault behaved as a migration pathway before the Early Cretaceous, allowing two oil charges to migrate into the hanging-wall, fault-core and footwall reservoirs across the fault. Since the Late Cretaceous, the Hongche fault has been sealed. As a consequence, meteoric water flowed down only into the hanging-wall and fault-core reservoirs. The meteoric-water incursion is likely an important cause for degradation of reservoir oils. In contrast, the footwall reservoirs received gas charge (the third hydrocarbon event) following the Late Cretaceous. This helps explain the distribution of petroleum across the fault. This study provides an example of how a fault may evolve as pathway and seal over time, and how reservoir diagenetic minerals can provide clues to complex petroleum migration histories.     

Spatial–temporal distribution of phytoplankton pigments in relation to nutrient status in Jiaozhou Bay,China

We conducted studies of phytoplankton and hydrological variables in a semi-enclosed bay in northern China to understand the spatial–temporal variability and relationship between these variables. Samples were collected during seven cruises in Jiaozhou Bay from November 2003 to October 2004, and were analyzed for temperature, nutrients and phytoplankton pigments. Pigments from eight possible phytoplankton classes (Diatoms, Dinoflagellates, Chlorophyceae, Prasinophyceae, Chrysophyceae, Haptophyceae, Cryptophyceae and Caynophyceae) were detected in surface water by high performance liquid chromatography (HPLC). Phytoplankton pigment and nutrient concentrations in Jiaozhou Bay were spatially and temporally variable, and most of them were highest in the northern and eastern parts of the sampling regions in spring (May) and summer (August), close to areas of shellfish culturing, river estuaries, dense population and high industrialization, reflecting human activities. Chlorophyll a was recorded in all samples, with an annual mean concentration of 1.892 μg L⁻¹, and fucoxanthin was the most abundant accessory pigment, with a mean concentration of 0.791 μg L⁻¹. The highest concentrations of chlorophyll a (15.299 μg L⁻¹) and fucoxanthin (9.417 μg L⁻¹) were observed in May 2004 at the station close to the Qingdao Xiaogang Ferry, indicating a spring bloom of Diatoms in this area. Although chlorophyll a and other biomarker pigments showed significant correlations, none of them showed strong correlations with temperature and nutrients, suggesting an apparent de-coupling between the pigments and these hydrological variables. The nutrient composition and phytoplankton community composition of Jiaozhou Bay have changed significantly in the past several decades, reflecting the increasing nutrient concentrations and decline of phytoplankton cell abundance. The unchanged total chlorophyll a levels indicated that smaller species have filled the niche vacated by the larger species in Jiaozhou Bay, as revealed by our biomarker pigment analysis.     

海洋青鳉鱼专用型基因芯片的设计及其在生态毒理学上的应用研究

以生物芯片技术为核心,结合生态毒理学与功能基因组学的方法,制备了海洋青鳉鱼专用型生物芯片,包含180个与细胞分裂、解毒反应、缺氧反应、氧化应激反应、凋亡、生长和发育、性别决定和性腺分化以及生殖激素分泌等功能相关的基因.我们提取了雌性海洋青鳉鱼成体在正常培养和缺氧处理12周后的肝脏和卵巢组织总RNA,利用自制的基因芯片进行了基因表达谱分析,结果显示海洋青鳉鱼在缺氧压力环境下,肝脏和卵巢组织的差异性表达基因分别检测出9个和6个,表明应用此类自制良好的芯片可有效获得海洋青鳉鱼的组织特异性基因表达图谱,也将加强对海洋缺氧状态、氧化应激等反应的分子生物学机制的理解.本研究对于识别异常环境状态下的基因表达模式和组织特异性标志物,进一步开展监测海洋生态毒理因素的研究奠定良好的基础.     

拮抗香蕉枯萎病菌海洋细菌的筛选和鉴定

从93份中国南部海域近海海泥样品中分离出1800多株海洋细菌,以对峙培养法,测定海洋细菌对香蕉枯萎菌的拮抗作用,再以琼脂划线培养法(agar streak)测定菌株的抑菌活性,结果表明:约55.6%的菌株对香蕉枯萎菌有一定的拮抗作用,其中58株菌株抑制香蕉枯萎菌生长所形成的抑菌带宽度大于10.0mm,抑菌作用较好,复筛后其中13个菌株形成的抑菌带宽在15.0mm以上。经反复转接和对峙培养,筛选出拮抗效果好、抑菌活性稳定的菌株TC-1,初步鉴定为芽孢杆菌属的细菌,TC-1对14种病原微生物都有较好的抑菌效果。     

Formation and early development of tetraspores of Polysiphonia urceolata （Rhodomelaceae, Rhodophyta）

Polysiphonia urceolata is one type of potential commercial red seaweeds used for breeding and cultivation, because of its significant biochemical and biomedical application. However, the information of breeding and seedling incubation for cultivation is limited, especially the early development. In this study, tetrasporohyte and gametophyte of P. urceolata were taken as the study materials in Huiquan Bay, Qingdao, China. The cleaned and sterilized tetrasporophytes and gametophytes were pre-cultured in sterilized seawater, then nurtured at 18°C, 25 μmol photons m⁻² s⁻¹ in 12:12 h (light:dark) photoperiod. Continuous observation under microscope showed that the early development consists of bipolar division stage and seedling stage. In the division stage, tetraspores germinate into bipolar sporelings that further differentiate into a colorless rhizoidal portion and a lightly pigmented upright shoot. The lightly pigmented rhizoidal cell develops to a rhizoid and the larger pigmented cell transforms to an erect axis. In the seedling stage, several quasi-protuberances appear on the erect axis and form juvenile seedlings. The results demonstrate the culture of P. urceolata from tetraspores under laboratory conditions. Supported by National Key Technology Support Program, Development Program of China (No.2006AA09Z21), National Natural Science Foundation of China (No. 40618001 and N_CUHK438/06) and Shandong Agricultural Seed Stock Breeding Project     

汶川地震对湖北地震活动趋势的影响

探讨汶川地震对湖北地震活动的影响,认为龙门山断裂带与襄樊-广济构造带同属于扬子板块西部和北部边缘,是扬子板块逆冲插入青藏板块和秦岭微板块之下形成的。历史强震统计结果表明,四川中西部及周边强震活动对湖北及周边地区中强地震活动影响明显,且对应率较高。汶川地震后3年内,湖北及周边地区具有发生中等强度地震的可能。同时也指出,近几年湖北及周边的地震活动是汶川地震前期东部地区应力场调整的结果。     

Stress Responses to Rapid Temperature Changes of the Juvenile Sea Cucumber （Apostichopusjaponicus Selenka）

Activities of hexokinase （HK）, pyruvate kinase （PK）, superoxide dismutase （SOD） and catalase （CAT） and Hsp70 level were measured to evaluate the response of the commercially important sea cucumber （Apostichopus japonicus Selenka） to rapid temperature changes in laboratory. Animals were subjected to a higher temperature （from 10 to 20℃） （Tinc treatment） or to a lower temperature （from 20 to 10℃） （Tddec treatment） for 72 h. At 1, 3, 12, 24, 72 h of exposure, animals were removed and prepared for further analysis. Results showed that the effect of acute temperature changes on enzyme activities was significant. In Tinc treatment, activities of SOD and CAT increased immediately. The significant enhancement of SOD and CAT activities suggested that oxidative stress increases significantly when ambient temperature increasing from 10 to 20℃. The up-regulation of Flsp70 in Tinc and Tdec treatments indicated that Hsp70 was a bioindicator of thermal stress in the sea cucumber, and the expression pattern depended on the thermal treatment.     

耦合手机信令数据和房价数据的城市不同经济水平人群行为活动模式研究

有效分析城市不同经济水平人群的分布特征和活动模式对优化城市资源配置和揭示空间隔离现象有着极高的价值。但人群活动和社会经济等级数据较敏感,使得以往研究仅停留在宏观层面,难以合理划分人群经济等级并对其空间分布和活动模式进行定量分析。本研究以深圳为研究区,基于空间位置关联分析方法,耦合手机信令数据和细尺度房价数据实现了人群经济水平的准确划分,通过计算活动指标定量的分析了不同经济水平人群的空间分布和行为活动特征。研究表明：深圳市不同经济水平人群活动分布与各行政区经济发展相关,呈现“南高北低,西高东低”的格局;深圳市不同经济水平人群之间活动模式存在差异,活动范围、出行距离、出行速度与经济水平存在正向相关;高经济水平人群职住地点相距较远,存在跨行政区分布的现象。本研究分析了城市不同经济水平人群的空间分布特征和活动模式,对城市规划和解决社会不平等问题具有重要的参考价值。