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The Global ETD Search service is a free service for researchers
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Showing 11 to 16 of 16 (0.041 seconds)| 11 |
Adjusting the mechanical behavior of embroidered scaffolds to lapin anterior cruciate ligaments by varying the thread materialsHahner, Judith, Hinüber, Claudia, Breier, Annette, Siebert, Tobias, Brünig, Harald, Heinrich, Gert 17 September 2019 (has links)
Traumatic rupture of the anterior cruciate ligament (ACL) can cause local destabilization and loss of mobility. Reconstruction using engineered ACL grafts is rarely successful due to sub-optimal material choice and mechanical performance.
Thus, the presented work demonstrates the fabrication of various embroidered single- and bi-component scaffolds made of two commercially available monofilament threads (polydioxanone, poly(lactic acid-co-ɛ- caprolactone)) as well as a novel melt spun poly(L-lactic acid) multifilament and their mechanical analysis by tensile tests and under cyclic loading. Selected scaffolds, adjusted by material composition and textile parameters, revealed a load–strain behavior comparable to native lapin ACL tissue exhibiting a sufficient amount of elastic deformation within the toe-region of 1.7%, scaffold stiffness of 123 N/mm and adequate maximum tensile load (300 N) and strain (20%). Therefore, the design of resorbable embroidered bi-component scaffolds represents a promising approach to replace artificial non-resorbable ligament grafts and allows for innovative tissue engineering strategies.
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Temperature Driven Transformation of the Flexible Metal–Organic Framework DUT-8(Ni)Ehrling, Sebastian, Senkovska, Irena, Efimova, Anastasia, Bon, Volodymyr, Abylgazina, Leila, Petkov, Petko, Evans, Jack D., Attallah, Ahmed Gamal, Wharmby, Michael Thomas, Roslova, Maria, Huang, Zhehao, Tanaka, Hideki, Wagner, Andreas, Schmidt, Peer, Kaskel, Stefan 20 March 2024 (has links)
DUT-8(Ni) metal–organic framework (MOF) belongs to the family of flexible pillared layer materials. The desolvated framework can be obtained in the open pore form (op) or in the closed pore form (cp), depending on the crystal size regime. In the present work, we report on the behaviour of desolvated DUT-8(Ni) at elevated temperatures. For both, op and cp variants, heating causes a structural transition, leading to a new, crystalline compound, containing two interpenetrated networks. The state of the framework before transition (op vs. cp) influences the transition temperature: the small particles of the op phase transform at significantly lower temperature in comparison to the macroparticles of the cp phase, transforming close to the decomposition temperature. The new compound, confined closed pore phase (ccp), was characterized by powder X-ray diffraction and spectroscopic techniques, such as IR, EXAFS, and positron annihilation lifetime spectroscopy (PALS). Thermal effects of structural transitions were studied using differential scanning calorimetry (DSC), showing an overall exothermic effect of the process, involving bond breaking and reformation. Theoretical calculations reveal the energetics, driving the observed temperature induced phase transition.
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Vinylene-Linked 2D Conjugated Covalent Organic Frameworks by Wittig ReactionLiu, Yannan, Fu, Shuai, Pastoetter, Dominik L., Khan, Arafat Hossain, Zhang, Yingying, Dianat, Arezoo, Xu, Shunqi, Liao, Zhongquan, Richter, Marcus, Yu, Minghao, Položij, Miroslav, Brunner, Eike, Cuniberti, Gianaurelio, Heine, Thomas, Bonn, Mischa, Wang, Hai I., Feng, Xinliang 27 February 2024 (has links)
Vinylene-linked two-dimensional covalent organic frameworks (V-2D-COFs) have shown great promise in electronics and optoelectronics. However, only a few reactions for V-2D-COFs have been developed hitherto. Besides the kinetically low reversibility of C=C bond formation, another underlying issue facing the synthesis of V-2D-COFs is the attainment of high (E)-alkene selectivity to ensure the appropriate symmetry of 2D frameworks. Here, we tailor the E/Z selectivity of the Wittig reaction by employing a proper catalyst (i.e., Cs2CO3) to obtain more stable intermediates and elevating the temperature across the reaction barrier. Subsequently, the Wittig reaction is innovatively utilized for the synthesis of four crystalline V-2D-COFs by combining aldehydes and ylides. Importantly, the efficient conjugation and decent crystallinity of the resultant V-2D-COFs are demonstrated by their high charge carrier mobilities over 10 cm2 V−1 s−1, as revealed by non-contact terahertz (THz) spectroscopy.
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Combination of Knoevenagel Polycondensation and Water-Assisted Dynamic Michael-Addition-Elimination for the Synthesis of Vinylene-Linked 2D Covalent Organic FrameworksXu, Shunqi, Liao, Dr. Zhongquan, Dianat, Arezoo, Park, Sang-Wook, Addicoat, Matthew A., Fu, Yubin, Pastoetter, Dominik L., Fabozzi, Filippo Giovanni, Liu, Yannan, Cuniberti, Gianaurelio, Richter, Marcus, Hecht, Stefan, Feng, Xinliang 22 April 2024 (has links)
Vinylene-linked two-dimensional conjugated covalent organic frameworks (V-2D-COFs), belonging to the class of two-dimensional conjugated polymers, have attracted increasing attention due to their extended π-conjugation over the 2D backbones associated with high chemical stability. The Knoevenagel polycondensation has been demonstrated as a robust synthetic method to provide cyano (CN)-substituted V-2D-COFs with unique optoelectronic, magnetic, and redox properties. Despite the successful synthesis, it remains elusive for the relevant polymerization mechanism, which leads to relatively low crystallinity and poor reproducibility. In this work, we demonstrate the novel synthesis of CN-substituted V-2D-COFs via the combination of Knoevenagel polycondensation and water-assisted dynamic Michael-addition-elimination, abbreviated as KMAE polymerization. The existence of C=C bond exchange between two diphenylacrylonitriles (M1 and M6) is firstly confirmed via in situ high-temperature NMR spectroscopy study of model reactions. Notably, the intermediate M4 synthesized via Michael-addition can proceed the Michael-elimination quantitatively, leading to an efficient C=C bond exchange, unambiguously confirming the dynamic nature of Michael-addition-elimination. Furthermore, the addition of water can significantly promote the reaction rate of Michael-addition-elimination for highly efficient C=C bond exchange within 5 mins. As a result, the KMAE polymerization provides a highly efficient strategy for the synthesis of CN-substituted V-2D-COFs with high crystallinity, as demonstrated by four examples of V-2D-COF-TFPB-PDAN, V-2D-COF-TFPT-PDAN, V-2D-COF-TFPB-BDAN, and V-2D-COF-HATN-BDAN, based on the simulated and experimental powder X-ray diffraction (PXRD) patterns as well as N2-adsorption–desorption measurements. Moreover, high-resolution transmission electron microscopy (HR-TEM) analysis shows crystalline domain sizes ranging from 20 to 100 nm for the newly synthesized V-2D-COFs.
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Mechanisms of Neuroligin Function in Inhibitory Postsynaptic Differentiation / Mechanismen der Neuroligin- Funktion in inhibitorischer postsynaptischer DifferenzierungPoulopoulos, Alexandros 28 April 2008 (has links)
No description available.
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Neuroligin 2 Induced Allosteric Transition of Collybistin Underlies Inhibitory Postsynaptic Differentiation / Neuroligin 2 induzierter allosterischer Übergang in Collybistin liegt der inhibitorischen postsynaptischen Differenzierung zugrundeSoykan, Tolga 03 June 2011 (has links)
No description available.
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