Deoxyribonucleic acid sample preparation in scanning probe microscope

The process of deoxyribonucleio acid (DNA) sample preparation in scanning tunneling microscope (STM) and atomic force microscope (AFM) is reviewed. The main discussions are devoted to the methods, advantages or drawbacks and improvement of the DNA sample's immobilization and spreading.

Vertical distribution of bacterial and archaeal communities along discrete layers of a deep-sea cold sediment sample at the East Pacific Rise (similar to 13 degrees N)

The community structure and vertical distribution of prokaryotes in a deep-sea (ca. 3,191 m) cold sediment sample (ca. 43 cm long) collected at the East Pacific Rise (EPR) similar to 13 degrees N were studied with 16SrDNA-based molecular analyses. Total community DNA was extracted from each of four discrete layers EPRDS-1, -2, -3 and -4 (from top to bottom) and 16S rDNA were amplified by PCR. Cluster analysis of DGGE profiles revealed that the bacterial communities shifted sharply between EPRDS-1 and EPRDS-2 in similarity coefficient at merely 49%. Twenty-three sequences retrieved from DGGE bands fell into 11 groups based on BLAST and bootstrap analysis. The dominant groups in the bacterial communities were Chloroflexi, Gamma proteobacteria, Actinobacterium and unidentified bacteria, with their corresponding percentages varying along discrete layers. Pairwise Fst (F-statistics) values between the archaeal clone libraries indicated that the archaeal communities changed distinctly between EPRDS-2 and EPRDS-3. Sequences from the archaeal libraries were divided to eight groups. Crenarchaea Marine Group I (MGI) was prevalent in EPRDS-1 at 83%, while Uncultured Crenarchaea group II B (UCII B) abounded in EPRDS-4 at 61%. Our results revealed that the vertically stratified distribution of prokaryotic communities might be in response to the geochemical settings and suggested that the sampling area was influenced by hydrothermalism. The copresence of members related to hydrothermalism and cold deep-sea environments in the microbial community indicated that the area might be a transitional region from hydrothermal vents to cold deep-sea sediments.

管理干部胜任特征评价方法的初步研究

Competency Assessment Method (CAM) is an important technique of Human Resource Management and Development in theory and practice, especially in personnel selection and training. Based on literatures of related fields, the thesis explored the feasibility of CAM in China. The main results found in this study are as follows: 1. Competencies scored in Behavioral Event Interviews (BEI) are not influenced by length of protocol, by performance in the preceding year. Average level and maximal level of complexity correlate significantly with length of protocol. Total competency frequency of outstanding executives is not significantly different from that of typical executives. These results support McCleland's view. But there is significant correlation between length of protocol and competency frequencies, which which is not agreed by McCleland. We found that competency scores using coding standard of average level and maximal level of complexity show more reliability than that using coding standard of competency frequencies. But this isn't confirmed by McCleland. 2. Inter-rater reliability was studied. The results indicated: total Category Agreement (CA) is 55.45%, over 70 percent of 20 competencies of the inter-rater reliability coefficients based on the classical test theory are significantly correlated. G coefficient based on the generalization theory is 0.85697. 3. Study of criterion sample shows that manager's competencies of China's communication enterprise are as follows: Impact and Influence, Organization Commitment, Information Seeking, Achievement Orientation, Team Leadership, Interpersonal Understanding, Initiative, Market Awareness, Self-confidence, Developing Others. This result in similar to the generic competency model of managers presented in Spencer's book. 4. CAM showed more advantages than the method of experts panel judgement.

Determination of heavy metal ions by capillary electrophoresis with contactless conductivity detection after field-amplified sample injection

A method has been developed for determining of heavy metal ions by field-amplified sample injection capillary electrophoresis with contactless conductivity detection. The effects of the 2-N-morpholinoethanesulfonic acid/histidine (MES/His) concentration in the sample matrix, the injection time and organic additives on the enrichment factor were studied. The results showed that MES/His with a low concentration in the sample matrix, an increase of the injection time and the addition of acetonitrile improved the enrichment factor. Four heavy metal ions (Zn2+, Co2+, Cu2+ and Ni2+) were dissolved in deionized water, separated in a 10 mM MES/His running buffer at pH 4.9 and detected by contactless conductivity detection. The detection sensitivity was enhanced by about three orders of magnitude with respect to the non-stacking injection mode. The limits of detection were in the range from 5 nM (Zn2+) to 30 nM (Cu2+). The method has been used to determine heavy metal ions in tap water.