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211.
212.
Synthesis of trisaccharide repeating unit, -->3)-alpha-D-Rhap-(1-->2)-alpha-D-Manp3CMe-(1-->3)-alpha-L-Rha p-(1-->, and its dimeric hexa- and trimeric nonasaccharide subunits of the atypical O-antigen polysaccharide of the lipopolysaccharide from Danish H. pylori strains D1, D3, and D6 has been accomplished. Successful synthesis of the hexasaccharide and the nonasaccharide was possible by dimerization and trimerization of the suitably protected trisaccharide repeating unit, in which three monosaccharide moieties were arranged in a proper order by placing the sterically demanding 3-C-methyl-D-mannose moiety in between D- and L-rhamnoses. Key steps include the coupling of three monosaccharide moieties and dimerization and trimerization of the trisaccharide unit by glycosylations employing the 2'-carboxybenzyl glycoside method. Also presented is a method for the synthesis of the novel branched sugar, 3-C-methyl-D-mannose moiety by elaboration of its equatorial hydroxyl and axial methyl groups at C-3' in the disaccharide stage. 相似文献
213.
CONOR P. McGOWAN DAVID R. SMITH JOHN A SWEKA JULIEN MARTIN JAMES D NICHOLS RICHARD WONG JAMES E LYONS LAWRENCE J NILES KEVIN KALASZ JEFFREY BRUST MICHELLE KLOPFER BRADDOCK SPEAR 《Natural Resource Modeling》2011,24(1):117-156
Abstract Adaptive management requires that predictive models be explicit and transparent to improve decisions by comparing management actions, directing further research and monitoring, and facilitating learning. The rufa subspecies of red knots (Calidris canutus rufa), which has recently exhibited steep population declines, relies on horseshoe crab (Limulus polyphemus) eggs as their primary food source during stopover in Delaware Bay during spring migration. We present a model with two different parameterizations for use in the adaptive management of horseshoe crab harvests in the Delaware Bay that links red knot mass gain, annual survival, and fecundity to horseshoe crab dynamics. The models reflect prevailing hypotheses regarding ecological links between these two species. When reported crab harvest from 1998 to 2008 was applied, projections corresponded to the observed red knot population abundances depending on strengths of the demographic relationship between these species. We compared different simulated horseshoe crab harvest strategies to evaluate whether, given this model, horseshoe crab harvest management can affect red knot conservation and found that restricting harvest can benefit red knot populations. Our model is the first to explicitly and quantitatively link these two species and will be used within an adaptive management framework to manage the Delaware Bay system and learn more about the specific nature of the linkage between the two species. 相似文献
214.
215.
Oliviana Calin Dr. Steffen Eller Heung Sik Hahm Prof. Dr. Peter H. Seeberger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(12):3995-4002
The first total synthesis of the O‐antigen pentasaccharide repeating unit from Gram‐negative bacteria Escherichia coli O111 was achieved starting from four monosaccharide building blocks. Key to the synthetic approach was a bis‐glycosylation reaction to combine trisaccharide 10 and colitose 5 . The colitose building block ( 5 ) was obtained de novo from non‐carbohydrate precursors. The pentasaccharide was equipped at the reducing end with an amino spacer to provide a handle for subsequent conjugation to a carrier protein in anticipation of immunological studies. 相似文献
216.
Wonmok Lee Young Jin Cho Heung Ryul Choi Hye Jin Park Taihyun Chang Min Park Hyunjung Lee 《Journal of separation science》2012,35(23):3250-3256
We present a rigorous investigation on elution behaviors of ultrasonically shortened multiwalled carbon nanotubes in size‐exclusion chromatography. The size separation of five carbon nanotube samples that underwent ultrasonic shortening for varying lengths of time revealed the existence of three kinds of carbon species: large nanotubes, small nanotubes, and amorphous carbon species. Separation of the three different carbon species was confirmed by SEM analyses on the fractionated eluates and also by light scattering/UV absorbance double detection. The chromatographic peak intensity ratio between the large and small nanotubes suggested an increased amount of small carbon nanotubes upon longer mechanical treatment time. The effect of the concentration of carbon nanotube dispersion on elution behavior was examined, and the elution volume of the shortened nanotubes was found to decrease upon dilution while that of the large nanotubes showed the opposite tendency. Unusual elution behaviors of the multiwalled carbon nanotubes were also observed by altering the flow rate, and these behaviors could be explained by the longer equilibration time taken for large nanotubes to access the pores of the packing materials and a possible morphology change of small carbon nanotubes. 相似文献
217.
Kim IJ Kim YJ Son BH Nam SO Kang HC Kim HD Yoo MA Choi OH Kim CM 《Experimental & molecular medicine》2006,38(2):119-125
Rett syndrome (RTT) is an X-linked dominant neurodevelopmental disorder affecting 1 per 10,000-15,000 female births worldwide. The disease-causing gene has been identified as MECP2 (methyl-CpG-binding protein 2). In this study, we performed diagnostic mutational analysis of the MECP2 gene in RTT patients. Four exons and a putative promoter of the MECP2 gene were analyzed from the peripheral blood of 43 Korean patients with Rett syndrome by PCR-RFLP and direct sequencing. Mutations were detected in the MECP2 gene in approximately 60.5% of patients (26 cases/43 cases). The mutations consisted of 14 different types, including 9 missense mutations, 4 nonsense mutations and 1 frameshift mutation. Of these, three mutations (G161E, T311M, p385fsX409) were newly identified and were determined to be disease-causing mutations by PCR- RFLP and direct sequencing analysis. Most of the mutations were located within MBD (42.3%) and TRD (50%). T158M, R270X, and R306C mutations were identified at a high frequency. Additionally, an intronic SNP (IVS3+23C>G) was newly identified in three of the patients. IVS3+23C>G may be a disease-related and Korea-specific SNP for RTT. L100V and A201V are apparently disease-causing mutations in Korean RTT, contrary to previous studies. Disease-causing mutations and polymorphisms are important tools for diagnosing RTT in Koreans. The experimental procedures used in this study should be considered for clinical molecular biologic diagnosis. 相似文献
218.
Cu2O纳米阵列的铜阳极氧化法制备及其光催化杀菌性能研究 总被引:3,自引:3,他引:0
本文通过阳极氧化法直接在铜片上生长出纳米氧化亚铜阵列,所得到的样品通过扫描电子显微镜(SEM),紫外可见漫反射(UV-Vis diffuser reflectance),X-射线光电子能谱(XPS)等方法进行了表征,并研究了不同形貌氧化亚铜的杀菌效果。实验结果表明:反应过程中在阳极液中加入一定量的CTAB,有助于氧化亚铜的定向生长。通过控制反应条件(如电流密度,温度,和反应时间),可以得到不同形貌的氧化亚铜。随着电流密度的增大,氧化亚铜的形貌从网状,片状到棒状进行转化。所得到氧化亚铜的禁带宽度为1.95 eV。用所得样品进行杀菌实验,1 h内棒状氧化亚铜的杀菌率达到90.85%,而其它形貌的氧化亚铜杀菌率只有50%左右,与空铜片的杀菌率30%相比,所制得氧化亚铜具有较好的杀菌效果。 相似文献
219.
推导了多次相平衡顶空气相色谱法测定海水中二甲基硫 (DMS)亨利常数 (K)的理论关系式 ,根据两次或多次气、液相平衡的关系式 ,只测定DMS在气相中的浓度就可测定亨利常数。实测 2 2℃时DMS在胶州湾海水中的亨利常数是 0 0 89,相对标准偏差为 5 5 0 %。亨利常数的对数与环境水体中NaCl的质量分数 [w(NaCl) ]之间的关系为 :logK =0 0 688·w(NaCl) - 1 3 5 68,相关系数为 0 997。亨利常数的对数与环境水体的绝对温度 (T)的倒数之间的相关方程为 :logK =- 15 4 4 8/T + 4 2 112 ,相关系数为 0 996。 相似文献
220.
This study discusses the applications of the Sharpe rule in portfolio measurement and management. It proposes that a portion of the portfolio value should be invested in some other assets for portfolio improvement. By applying the Sharpe rule, it can be determined that new stocks are worthy of adding to the old portfolio if they satisfy a condition, in which the average return rate of these stocks is greater than the return rate of the old portfolio multiplied by the sum of the elasticity of the VaR and 1. One attraction of our approach is diversification. A numerical example in the Hong Kong stock market is presented for illustration. Some experimental results show that a new portfolio with the 'highest' Sharpe ratio can be obtained by adding only a few new assets. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献