Chromosomal mapping of major ribosomal rRNA genes in the hard clam (Mercenaria mercenaria) using fluorescence in situ hybridization

Karyotype and chromosomal location of the major ribosomal RNA genes were studied in the hard clam (Mercenaria mercenaria Linnaeus) using fluorescence in situ hybridization (FISH). Metaphase chromosomes were obtained from early embryos. Internal transcribed spacers (ITS) between major RNA genes were amplified and used as FISH probes. The probes were labeled with digoxigenin-11-dUTP by polymerase chain reaction and detected with fluorescein-labeled anti-digoxigenin antibodies. FISH with the ITS probes produced two to four signals per nucleus or metaphase. M. mercenaria had a haploid number of 19 chromosomes with a karyotype of seven metacentric, four metacentric or submetacentric, seven submetacentric, and one submetacentric or subtelocentric chromosomes (7M + 4M/SM + 7SM + 1SM/ST). Two ITS loci were observed: one located near the centromere on the long arm of Chromosome 10 and the other at the telomere of the short arm of Chromosome 12. FISH signals on Chromosome 10 are strong and consistent, while signals on Chromosome 12 are variable. This study provides the first karyotype and chromosomal assignment of the major RNA genes in M. mercenaria. Similar studies in a wide range of species are needed to understand the role of chromosomal changes in bivalve evolution.

AUV水下回收研究

世界各国对海底的开发探索促进了AUV 技术的发展，但是传统回收AUV 的方法效率低、可靠性差、作业环境危险因此回收一直是影响AUV 广泛应用的主要因素。以至于学者们指出，回收问题是影响AUV 事业发展的瓶颈问题。水下回收被认为是比较有前途的一种回收方法。使用水下回收的方法操作者可以不必冒险下小艇，并且水下回收所使用的设备完全可以利用现有的技术储备。水下回收不仅可以帮助AUV 实现安全回收，而且还具有其他潜在用途。如它可以为AUV 在水下补充能量和交换数据，以及为载入潜器问人员、物资流动提供安全路径。通过分析探索者号AUV 水下回4欠的得失，作者提出种新的水下回收方案。就是当AUV 上浮到一定深度以后自动定深悬浮，派捕捉者(一艘有缆潜器)去捕捉吕标AUV ，然后把AUV 拖人回收舱，有缆潜器的运动可以是受人遥控的也可以是自动的，视具体情况而定。文章中历数了方案实施过程中将遇到的技术难点，并指出捕捉过程中捕捉者和AUV 的运动控制问题是水下回收过程中的关键问题。提出捕捉过程中用模糊逻辑算法来确定捕捉者的捕捉航线，并对控制算法进行仿真。在不同的方案中对AUV的运动控制要求有所不同，文章针对不同的运动控制分别作了讨论，并对其中些运动控制进行了仿真试验。在文章第一章里叙述了AUV 发展的背景和现状，指出AUV 的回收问题是影响AUV (泛应用的瓶颈问题，并总结了探索者号AUV 水下回收得失。在第二章里提出了个水下回收方案，并对这个方案进行了论证。在第三章里提出了水下回收过程中可供选择的三个捕捉方案，并总结了每个方案的优缺点。在第四章里提出用模糊逻辑的方法解决捕捉过程中的运动控制问题e在第五章里建立了AUV 的数学模型，以便于在下一章分析AUV 的运动控制。在第六章里分析了不同捕捉方案中对ACV 控制品质的不同要求，并根据要求讨论了AUV 的运动控制在最后一章里作者对文章作了综述和总结、并对水下回收技术未来的发展趋势作出展望。

新型托辊切管机控制系统设计

文章介绍了一种新型托辊切管机控制系统的设计,对该系统的硬件组态及控制功能作了主要描述。该机床是托辊自动化加工装配线上的一台机电一体化自动加工设备,其主要功能是对托辊装配所需原料管进行定尺切断,并在整个加工过程中自动上下料。整个机床控制系统主要由SIEMENS Simotion D运动控制系统、触摸屏TP177B、远程输入输出模块ET200M等组成。

贵州省燃煤型氟中毒地区的氟源新认

目的：调查贵州省燃煤型氟中毒地区的氟源。方法：测定3个典型氟中毒重病村的煤、拌煤粘土、煤饼、煤饼灰的含氟量；调查贵州省煤含氟量。结果：化落、马家庄、偏坡寨3个村子的煤氟分别为107．8、104．1、117．6mg/kg，拌煤粘土氟分别为6103．7、1900．5、2619．7mg/kg，煤饼氟分别为805．3、480．7、1713．6mg/kg，煤饼灰氟分别为639．6、332．5、841．7mg/kg；贵州省煤氟均值为115．5mg/kg.结论:氟源主要是拌煤粘土，其含氟量一般很高。

The effect of Rh particle size on the catalytic performance of porous silica supported rhodium catalysts for CO hydrogenation

Silica-supported Rh catalysts with different Rh particle dimensions were investigated for CO hydrogenation. The catalysts were characterized by various techniques such as TEM, H-2-TPR and N-2 adsorption to study the catalyst morphology, the size distributions of Rh particles and the silica pores. It was found that the distribution and the size of Rh particles were affected by the silica pores, and the metal grains were enclosed in the pores of the support, and thereby their growth was limited. The catalytic activity and selectivity to C-2-oxygenates for CO hydrogenation were found to be significantly controlled by the Rh particle sizes, and the higher activity and selectivity to C2-oxygenates were obtained over bigger Rh particles, within the range of the reported particle sizes.