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排序方式: 共有340条查询结果,搜索用时 349 毫秒
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Abstract We have investigated the fatigue of electromechanical and dielectric properties of sol-gel derived PZT(53/47) thin films deposited on metallic substrates by means of electric and mechanical cycling. For the mechanical cycling a two point bending method was used to apply transversal stress to the samples. During mechanical cycling the piezoelectric coefficient d31 remained constant up to about 105 cycles, for a higher number of cycles a strong decrease was observed. During electric cycling no significant changes in the ferroelectric and electromechanical hysteresis loops could be found up to about 3×105 cycles. Above this number the coercive field increases, the maximum strain and the remanent polarization decrease. Obviously each electric cycling of the investigated films is accompanied by a mechanical cycling. It is assumed, that microcracks induced by mechanical stress are the main reason for the deterioration of the physical properties films during electric and mechanical cycling both. 相似文献
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Yvonne Rellmann Elco Eidhof Uwe Hansen Lutz Fleischhauer Jonas Vogel Hauke Clausen-Schaumann Attila Aszodi Rita Dreier 《International journal of molecular sciences》2022,23(1)
Ageing or obesity are risk factors for protein aggregation in the endoplasmic reticulum (ER) of chondrocytes. This condition is called ER stress and leads to induction of the unfolded protein response (UPR), which, depending on the stress level, restores normal cell function or initiates apoptotic cell death. Here the role of ER stress in knee osteoarthritis (OA) was evaluated. It was first tested in vitro and in vivo whether a knockout (KO) of the protein disulfide isomerase ERp57 in chondrocytes induces sufficient ER stress for such analyses. ER stress in ERp57 KO chondrocytes was confirmed by immunofluorescence, immunohistochemistry, and transmission electron microscopy. Knee joints of wildtype (WT) and cartilage-specific ERp57 KO mice (ERp57 cKO) were analyzed by indentation-type atomic force microscopy (IT-AFM), toluidine blue, and immunofluorescence/-histochemical staining. Apoptotic cell death was investigated by a TUNEL assay. Additionally, OA was induced via forced exercise on a treadmill. ER stress in chondrocytes resulted in a reduced compressive stiffness of knee cartilage. With ER stress, 18-month-old mice developed osteoarthritic cartilage degeneration with osteophyte formation in knee joints. These degenerative changes were preceded by apoptotic death in articular chondrocytes. Young mice were not susceptible to OA, even when subjected to forced exercise. This study demonstrates that ER stress induces the development of age-related knee osteoarthritis owing to a decreased protective function of the UPR in chondrocytes with increasing age, while apoptosis increases. Therefore, inhibition of ER stress appears to be an attractive therapeutic target for OA. 相似文献
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Bouma M Nuijen B Harms R Rice JR Nowotnik DP Stewart DR Jansen BA van Zutphen S Reedijk J van Steenbergen MJ Talsma H Bult A Beijnen JH 《Drug development and industrial pharmacy》2003,29(9):981-995
AP 5280 is a novel polymer-conjugated platinum anticancer agent showing promising in vitro and in vivo activity against solid tumors. The aim of this study was to develop a parenteral pharmaceutical dosage form for phase I clinical trials. AP 5280 drug substance was characterized by using a wide range of analytical techniques and showed excellent solubility in water. However, as aqueous solutions of AP 5280 proved to be labile upon sterilization by moist heat, it was decided to develop a lyophilized dosage form. Initially, glass vials were used as primary packaging, but this led to a high breakage rate, which could be completely prevented by the use of CZ® resin vials. Stability studies to date show that the lyophilized product in glass vials is stable for at least 12 months when stored at 2-8°C in the dark and the lyophilized product in CZ resin vials is stable for at least 6 months under these conditions. Photostability testing revealed photolability of AP 5280 drug substance and lyophilized product in both types of primary container, necessitating storage in the dark. The first clinical experiences indicate that the proposed formulation is fully applicable for use in the clinical setting. 相似文献
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A Series of comparisons were conducted to test the capabilities of a range of metrological techniques and analytical laboratories engaged in the assay of thorium in the workplace. The results of these exercises are presented together with the decision criteria used to determine whether results are significantly different from the true value. The discussion highlights those aspects which warrant closer and further attention. 相似文献
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Richter Susanne A.; Stubenrauch Kay; Lilie Hauke; Rudolph Rainer 《Protein engineering, design & selection : PEDS》2001,14(10):775-783
The de novo design of a molecular adapter for directed associationand covalent linkage of two polypeptides is presented. Usingpeptides containing charged amino acid residues and an additionalcysteine residue (AlaCysLys8 and AlaCysGlu8) we demonstratethat the electrostatic interaction promotes the associationof two synthetic peptides and, subsequently, disulfide bondformation. The reaction depends on both the redox potentialand on the ionic strength of the buffer. Varying the redox potential,the interaction of the peptides was quantified by a G0' of 6.6± 0.2 kcal/mol. Heterodimerization of the peptides ishighly specific, a competition of association by other cysteinecontaining compounds could not be observed. Two proteins comprisingcysteine-containing polyionic fusion peptides, a modified Fabfragment and an -glucosidase fusion, could be specifically conjugatedby directed association and subsequent disulfide bond formation.Both proteins retain their functional characteristics withinthe bifunctional conjugate: enzymatic activity of the glucosidaseand antigen-binding capacity of the Fab fragment are equivalentto the non-conjugated components. 相似文献
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