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排序方式: 共有240条查询结果,搜索用时 15 毫秒
11.
Wei Fan François Stoffelbach Jutta Rieger Laure Regnaud Angélique Vichot Bruno Bresson Nicolas Lequeux 《Cement and Concrete Research》2012,42(1):166-172
It is well-established that a competitive adsorption exists between polycarboxylate superplasticizers (SP) and sulfate ions solubilized in the interstitial solution of cement paste, which may cause a loss of the dispersing properties. This has been explained by competitive weak ionic interactions between functional carboxyl groups and sulfate ions with cement grains. In this study, SPs including trialkoxysilane functional groups have been synthesized. Adsorption and dispersing properties of these SPs were evaluated in the presence of different concentrations of Na2SO4 added in aqueous solution. It appeared that a partial substitution of carboxyl groups by trialkoxysilane in the polymer makes them more resistant to sulfate ions. We suggested that the high adsorption capacity of these SPs results from the formation of strong bonds between hydroxysilane groups and calcium silicate hydrate phases. The improved compatibility of these new silylated SPs has been demonstrated through the formulation of two different concrete equivalent mortars. 相似文献
12.
Dr. Christina Haußner Dominik Damm Sandra Nirschl Anette Rohrhofer Prof. Dr. Barbara Schmidt Prof. Dr. Jutta Eichler 《Chembiochem : a European journal of chemical biology》2017,18(7):647-653
The broadly neutralizing HIV‐1 antibody b12 recognizes the CD4 binding site of the HIV‐1 envelope glycoprotein gp120 and efficiently neutralizes HIV‐1 infections in vitro and in vivo. Based on the 3D structure of a b12 ? gp120 complex, we have designed an assembled peptide (b12‐M) that presents the parts of the three heavy‐chain complementarity‐determining regions (CDRs) of b12, which contain the contact sites of the antibody for gp120. This b12‐mimetic peptide, as well as a truncated peptide presenting only two of the three heavy‐chain CDRs of b12, were shown to recognize gp120 in a similar manner to b12, as well as to inhibit HIV‐1 infection, demonstrating functional mimicry of b12 by the paratope mimetic peptides. 相似文献
13.
Mari Kallioinen Mika Mänttäri Jutta Nuortila-Jokinen Timo Sutela 《Desalination》2010,250(3):1002-1004
The total effluent load of a paper mill can be significantly decreased by recycling of purified clear filtrate (CF) back to paper-making process. The CF treated with membranes can be reused, for instance, as wire section shower water and in the dilution of chemicals. The main requirements for a membrane in CF treatment are high filtration capacity, high retention of turbidity and low fouling tendency. Previous studies have shown that the regenerated cellulose (RC) ultrafiltration (UF) membrane C30F (current trade name UC030T) is especially suitable for the treatment of paper mill process waters. Every paper-making process is, however, different. Thus, filtration experiments are required in order to find the most optimal membrane for the treatment of a certain process water. In this study the best membrane for the treatment of acidic clear filtrate (ACF) was searched. The performance of the C30F membrane was compared with five UF and three microfiltration (MF) membranes. The results revealed that in addition to the C30F membrane, also some other membranes produced high filtration capacity with ACF (approximately 200 L/(m2h bar)). All the tested membranes also retained over 90% of turbidity. The extremely hydrophilic C30F membrane had, however, lower fouling tendency compared to the other tested membranes. Therefore, it was concluded that the C30F membranes were the best possible membrane for the ACF treatment. 相似文献
14.
Stephan Altmann Jürgen Mut Natalia Wolf Jutta Meißner-Weigl Maximilian Rudert Franz Jakob Marcus Gutmann Tessa Lühmann Jürgen Seibel Regina Ebert 《International journal of molecular sciences》2021,22(6)
Metabolic glycoengineering enables a directed modification of cell surfaces by introducing target molecules to surface proteins displaying new features. Biochemical pathways involving glycans differ in dependence on the cell type; therefore, this technique should be tailored for the best results. We characterized metabolic glycoengineering in telomerase-immortalized human mesenchymal stromal cells (hMSC-TERT) as a model for primary hMSC, to investigate its applicability in TERT-modified cell lines. The metabolic incorporation of N-azidoacetylmannosamine (Ac4ManNAz) and N-alkyneacetylmannosamine (Ac4ManNAl) into the glycocalyx as a first step in the glycoengineering process revealed no adverse effects on cell viability or gene expression, and the in vitro multipotency (osteogenic and adipogenic differentiation potential) was maintained under these adapted culture conditions. In the second step, glycoengineered cells were modified with fluorescent dyes using Cu-mediated click chemistry. In these analyses, the two mannose derivatives showed superior incorporation efficiencies compared to glucose and galactose isomers. In time-dependent experiments, the incorporation of Ac4ManNAz was detectable for up to six days while Ac4ManNAl-derived metabolites were absent after two days. Taken together, these findings demonstrate the successful metabolic glycoengineering of immortalized hMSC resulting in transient cell surface modifications, and thus present a useful model to address different scientific questions regarding glycosylation processes in skeletal precursors. 相似文献
15.
16.
Rohrlack T Christoffersen K Hansen PE Zhang W Czarnecki O Henning M Fastner J Erhard M Neilan BA Kaebernick M 《Journal of chemical ecology》2003,29(8):1757-1770
This paper describes the purification and characterization of microviridin J, a newly discovered metabolite of Microcystis that causes a lethal molting disruption in Daphnia spp., upon ingestion of living cyanobacterial cells. Microviridin J consists of an acetylated chain of 13 amino acids arranged in three rings and two side chains. Unlike other known isoforms of microviridin, microviridin J contains arginine that imparts a unique solution conformation characterized by proximal hydrophobic interactions between Arg and other regions of the molecule. This eventually results in the formation and stabilization of an additional ring system. Microviridin J potently inhibits porcine trypsin, bovine chymotrypsin, and daphnid trypsin-like proteases. The activity against trypsin is most likely due to Arg and its distinctive conformational interactions. Overall, the data presented for microviridin J emphasize once again the ability of cyanobacteria to produce numerous and potent environmental toxins. 相似文献
17.
Researchers have documented that children of depressed mothers are at elevated risk for developing a depressive disorder themselves. There is currently little understanding, however, of what factors place these children at elevated risk. In the present study, the authors investigated whether never-disordered daughters whose mothers have experienced recurrent episodes of depression during their daughters' lifetime are characterized by biased processing of emotional information. Following a negative mood induction, participants completed an emotional-faces dot-probe task. Daughters at elevated risk for depression, but not control daughters of never-disordered mothers, selectively attended to negative facial expressions. In contrast, only control daughters selectively attended to positive facial expressions. These results provide support for cognitive vulnerability models of depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
18.
This study was designed to examine attentional biases in the processing of emotional faces in currently and formerly depressed participants and healthy controls. Using a dot-probe task, the authors presented faces expressing happy or sad emotions paired with emotionally neutral faces. Whereas both currently and formerly depressed participants selectively attended to the sad faces, the control participants selectively avoided the sad faces and oriented toward the happy faces, a positive bias that was not observed for either of the depressed groups. These results indicate that attentional biases in the processing of emotional faces are evident even after individuals have recovered from a depressive episode. Implications of these findings for understanding the roles of cognitive and interpersonal functioning in depression are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
19.
The present study was designed to examine the operation of depression-specific biases in the identification or labeling of facial expression of emotions. Participants diagnosed with major depression and social phobia and control participants were presented with faces that expressed increasing degrees of emotional intensity, slowly changing from a neutral to a full-intensity happy, sad, or angry expression. The authors assessed individual differences in the intensity of facial expression of emotion that was required for the participants to accurately identify the emotion being expressed. The depressed participants required significantly greater intensity of emotion than did the social phobic and the control participants to correctly identify happy expressions and less intensity to identify sad than angry expressions. In contrast, social phobic participants needed less intensity to correctly identify the angry expressions than did the depressed and control participants and less intensity to identify angry than sad expressions. Implications of these results for interpersonal functioning in depression and social phobia are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
20.
Using aqueous hydrogen peroxide containing 30% H2O2, solid acid catalysts were compared in their performance as catalysts for the transformation of cyclopentanone to δ-valerolactone. It could be shown that organic ion exchange resins with sulphonic acid groups providing acid functionality are promising catalysts for this reaction. The variation of several reaction parameters was studied in more detail. The obtained results were compared to investigations of zeolites and Nafion® composite materials. 相似文献