Effect of replacing [NTf2] by [PF6] anion on the [BMIm][NTf2] ionic liquid confined by gold

The effect of replacing bis(trifluoromethylsulphonyl)imide ([NTf₂]) by hexafluorophosphate ([PF₆]) in room temperature ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulphonyl)imide ([BMIm][NTf₂]) confined between two gold interfaces is herein reported through molecular dynamics simulations using all-atom non-polarisable force-fields. Five systems were studied ranging from pure [BMIm][NTf₂] to pure [BMIm][PF₆], with [PF₆] molar fractions of 0, 0.125, 0.25, 0.375 and 0.5. Special attention was drawn to investigate the impact of the [PF₆] anion on the IL, in particular on the first layers of the liquid in close contact with the solid gold surface.     

Terpenoids from Euphorbia helioscopia and Their Cytotoxic Activities against H1975 Cells

Three previously undescribed diterpenoids, helioscopnoids A–C, and eight known compounds were isolated from the whole plants of Euphorbia helioscopia. Their structures were established by extensive analysis of spectra and data comparison with previous literatures. Among them, compound 4 was identified as 24,24-dimethoxy-25,26,27-trinoreuphan-3β-ol with revised configurations of C-13, C-14, and C-17 (13R*, 14R*, 17R*). Cytotoxicity assays revealed that all compounds exhibited varying levels of cytotoxicity against H1975 cells, with compound 9 displaying the most potent activity, as indicated by cell viability rates of 18.13 % and 20.76 % at concentrations of 20 μM and 5 μM, respectively. This study expands the understanding of E. helioscopia terpenoids’ structural diversity and biological activities, contributing to the exploration of potential therapeutic applications.     

Impact of Land-Use Patterns on Chemical Properties of Trace Elements in Soils of Rural,Semi-Urban,and Urban Zones of the Niger Delta,Nigeria

The study of the concentrations of Cr, Zn, Cd, Pb, Ni, and Cu in soils under different land uses in rural, semi-urban, and urban zones in the Niger Delta was carried out with a view to providing information on the effects of the different land uses on the concentrations of trace elements in soils. Our results indicate significant variability in concentrations of these metals in soils under different land uses in rural, semi-urban, and urban zones. The maximum concentrations of metals in the examined soil samples were 707.5 mg.kg^?1, 161.0 mg.kg^?1, 2.6 mg.kg^?1, 59.6 mg.kg^?1, 1061.3 mg.kg^?1, and 189.2 mg.kg^?1 for Cr, Zn, Cd, Pb, Ni, and Cu, respectively. In the rural zone, the cassava processing mill is a potent source of Ni, Cr, Cu, and Zn while agricultural activities are a source of Cd, and automobile emissions and the use of lead oxide batteries constitute the major sources of Pb. In the urban zone, soils around the wood processing mill showed elevated concentrations of Cu, Cr, Zn, and Ni, while soils around automobile mechanic works and motor parks showed elevated levels of Pb. Elevated Cd concentrations were observed in soils under the following land uses: urban motor park, playground, welding and fabrication sheds, and metallic scrap dump. The contamination/pollution index of metals in the soil follows the order: Ni > Cd > Cr > Zn > Cu > Pb. The multiple pollution index of metals at different sites were greater than 1, indicating that these soils fit into “slight pollution” to “excessive pollution” ranges with significant contributions from Cr, Zn, Cd, Ni, and Cu.     

论自我效能感对学生学习活动的影响及培养策略

自我效能感是Bandura自我效能理论的核心概念,是指个体对自己是否能够成功地进行某一成就行为的主观判断。文章介绍了自我效能感的概念、形成因素及对学生学习活动的影响,在此基础上,探讨了对学生学习自我效能感的培养策略。     

Design,synthesis and algicides activities of thiourea derivatives as the novel scaffold aldolase inhibitors

By using a new Fragment-Based Virtual Screen strategy, two series of novel FBA-II inhibitors (thiourea derivatives) were de novo discovered based on the active site of fructose-1, 6-bisphosphate aldolase from Cyanobacterial (CyFBA). In comparison, most of the N-(2-benzoylhydrazine-1-carbonothioyl) benzamide derivatives (L14～L22) exhibit higher CyFBA-II inhibitory activities compared to N-(phenylcarbamothioyl) benzamide derivatives (L1～L13). Especially, compound L14 not only shows higher CyFBA-II activity (K_i?=?0.65?μM), but also exhibits most potent in vivo activity against Synechocystis sp. PCC 6803 (EC₅₀?=?0.09?ppm), higher (7-fold) than that of our previous inhibitor (EC₅₀?=?0.6?ppm). The binding modes of compound L14 and CyFBA-II were further elucidated by jointly using DOX computational protocol, MM-PBSA and site-directed mutagenesis assays. The positive results suggest that strategy adopted in this study was promising to rapidly discovery the potent inhibitors with novel scaffolds. The satisfactory algicide activities suggest that the thiourea derivatives is very likely to be a promising lead for the development of novel specific algicides to solve Cyanobacterial harmful algal blooms (CHABs).     

Improving coiled-coil stability by optimizing ionic interactions

Alpha-helical coiled coils are a common protein oligomerization motif stabilized mainly by hydrophobic interactions occurring along the coiled-coil interface. We have recently designed and solved the structure of a two-heptad repeat coiled-coil peptide that is stabilized further by a complex network of inter- and intrahelical salt-bridges in addition to the hydrophobic interactions. Here, we extend and improve the de novo design of this two heptad-repeat peptide by four newly designed peptides characterized by different types of ionic interactions. The contribution of these different types of ionic interactions to coiled-coil stability are analyzed by CD spectroscopy and analytical ultracentrifugation. We show that all peptides are highly alpha-helical and two of them are 100% dimeric under physiological conditions. Furthermore, we have solved the X-ray structure of the most stable of these peptides and the rational design principles are verified by comparing this structure to the structure of the parent peptide. We show that by combining the most favorable inter- and intrahelical salt-bridge arrangements it is possible to design coiled-coil oligomerization domains with improved stability properties.     

“城-郊-乡”森林生态样带植被变化梯度分析

沿纽约市“市区－郊区－农区”１４０ｋｍ森林生态样带,对９个样地１９个样方的森林植被进行了研究。植被组成和结构沿样带变化明显,分异出城区森林、郊区森林和农区森林等不同类型,优势种替代明显,植物种类也形成了不同的生态类型。植被的梯度变化与人类活动密切相关,城市化对植被有重要影响。森林生态样带是研究人类活动对植被影响的好手段。     

A room temperature ionic liquid as convenient solvent for the oxidative folding of conopeptides

We report the first example of conopeptide oxidation performed in a biocompatible ionic liquid, 1‐ethyl‐3‐methylimidazolium acetate ([C₂mim][OAc]), which enables the efficient formation of both hydrophilic and poorly water‐soluble conotoxins compared with conventional methods. Moreover, the method features a high‐concentration approach ultimately leading to higher yields at reduced separation effort. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.     

北细辛内生真菌的分离鉴定及代谢产物的生物活性

采用表面消毒法分别从3种北细辛中分离获得10株形态特征不同的优势内生真菌,经形态学和18S rDNA ITS分子分类学分析鉴定为小丛壳属(Glomerella sp.)、叶点霉属(Phyllosticta sp.)、柄孢壳菌属(Po-dospora sp.)、刺盘孢属(Colletotrichum sp.)和镰孢属(Fusarium sp.)。对北细辛优势内生真菌的发酵产物进行体外抗肿瘤和抗菌活性检测,结果表明:除菌株E3、E4和E10外,其余菌株均有不同程度的抗肿瘤和抗菌活性;镰孢属(Fusarium sp.)菌株E9对A549、MDA-MB-231和PANC-1肿瘤细胞抑制率达75%以上;小丛壳属(Glomerella sp.)菌株E1和叶点霉属(Phyllosticta sp.)菌株E2靶向FabI的抗菌活性较强,抑制率达59%。     

Physiological analysis of Methylobacterium extorquens AM1 grown in continuous and batch cultures

Chemostat cultures of Methylobacterium extorquens AM1 grown on methanol or succinate at a range of dilution rates were compared to batch cultures in terms of enzyme levels, poly-β-hydroxybutyrate content, and intracellular concentrations of adenine and pyridine nucleotides. In both chemostat and batch cultures, enzymes specific to C₁ metabolism were up-regulated during growth on methanol and down-regulated during growth on succinate, polyhydroxybutyrate levels were higher on succinate, intracellular ATP levels and the energy charge were higher during growth on methanol, while the pools of reducing equivalents were higher during growth on succinate. For most of the tested parameters, little alteration occurred in response to growth rate. Overall, we conclude that the chemostat cultivation conditions developed in this study roughly mimic the growth in batch cultures, but provide a better control over the culturing conditions and a better data reproducibility, which are important for integrative functional studies. This study provides baseline data for future work using chemostat cultures, defining key similarities and differences in the physiology compared to existing batch culture data.