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排序方式: 共有1007条查询结果,搜索用时 312 毫秒
821.
Shehrazade Jekhmane Marek Prachar Raffaele Pugliese Federico Fontana Joo Medeiros‐Silva Fabrizio Gelain Markus Weingarth 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(47):17099-17107
Stem‐cell behavior is regulated by the material properties of the surrounding extracellular matrix, which has important implications for the design of tissue‐engineering scaffolds. However, our understanding of the material properties of stem‐cell scaffolds is limited to nanoscopic‐to‐macroscopic length scales. Herein, a solid‐state NMR approach is presented that provides atomic‐scale information on complex stem‐cell substrates at near physiological conditions and at natural isotope abundance. Using self‐assembled peptidic scaffolds designed for nervous‐tissue regeneration, we show at atomic scale how scaffold‐assembly degree, mechanics, and homogeneity correlate with favorable stem cell behavior. Integration of solid‐state NMR data with molecular dynamics simulations reveals a highly ordered fibrillar structure as the most favorable stem‐cell scaffold. This could improve the design of tissue‐engineering scaffolds and other self‐assembled biomaterials. 相似文献
822.
Antonio Coppola Alessandro Esposito Fabio Montagnaro Mauro Iuliano Fabrizio Scala Piero Salatino 《Proceedings of the Combustion Institute》2019,37(4):4379-4387
The effect of steam and sulphur dioxide on CO2 capture by limestone during calcium looping was studied in a novel lab-scale twin fluidised bed device (Twin Beds – TB). The apparatus consists of two interconnected batch fluidised bed reactors which are connected to each other by a duct permitting a rapid and complete pneumatic transport of the sorbent (limestone) between the reactors. Tests were carried out under typical calcium looping operating conditions with or without the presence of H2O and/or SO2 during the carbonation stage. Carbonation was carried out at 650°C in presence of 15% CO2, 10% steam (when present) and by investigating two SO2 levels, representative of either raw (1500?ppm) or pre-desulphurised (75?ppm) typical flue gas derived from coal combustion. The sorbent used was a reactive German limestone. Its performance was evaluated in terms of CO2 capture capacity, sulphur uptake, attrition and fragmentation. Results demonstrated the beneficial effect of H2O and the detrimental effect of SO2 on the CO2 capture capacity. When both species were simultaneously present in the gas, steam was still able to enhance the CO2 capture capacity even outweighing the negative effect of SO2 at low SO2 concentrations. A clear relationship between degrees of Ca carbonation and sulphation was observed. As regards the mechanical properties of the sorbent, both H2O and SO2 hardened the particle surface inducing a decrease of the measured attrition rate, that was indeed always very low. Conversely, the fragmentation tendency increased in presence of H2O and SO2 most likely due to the augmented internal stresses within the particles. Clear bimodal particle size distributions for in-bed sorbent fragments were observed. Microstructural scanning electron microscope and porosimetric characterisations aided in explaining the observed trends. 相似文献
823.
Elena Bonetti Pierluigi Colli Mauro Fabrizio Gianni Gilardi 《Archive for Rational Mechanics and Analysis》2016,219(1):203-254
We consider a strongly nonlinear PDE system describing solid–solid phase transitions in shape memory alloys. The system accounts for the evolution of an order parameter χ (related to different symmetries of the crystal lattice in the phase configurations), of the stress (and the displacement u), and of the absolute temperature ?. The resulting equations present several technical difficulties to be tackled; in particular, we emphasize the presence of nonlinear coupling terms, higher order dissipative contributions, possibly multivalued operators. As for the evolution of temperature, a highly nonlinear parabolic equation has to be solved for a right hand side that is controlled only in L 1. We prove the existence of a solution for a regularized version by use of a time discretization technique. Then, we perform suitable a priori estimates which allow us pass to the limit and find a weak global-in-time solution to the system. 相似文献
824.
Matteo Moretti Isabella Marzi Cristina Cantarutti Mirella Vivoli Vega Walter Mandaliti Maria Chiara Mimmi Francesco Bemporad Alessandra Corazza Fabrizio Chiti 《Molecules (Basel, Switzerland)》2022,27(13)
TAR DNA-binding protein 43 (TDP-43) forms intraneuronal cytoplasmic inclusions associated with amyotrophic lateral sclerosis and ubiquitin-positive frontotemporal lobar degeneration. Its N-terminal domain (NTD) can dimerise/oligomerise with the head-to-tail arrangement, which is essential for function but also favours liquid-liquid phase separation and inclusion formation of full-length TDP-43. Using various biophysical approaches, we identified an alternative conformational state of NTD in the presence of Sulfobetaine 3-10 (SB3-10), with higher content of α-helical structure and tryptophan solvent exposure. NMR shows a highly mobile structure, with partially folded regions and β-sheet content decrease, with a concomitant increase of α-helical structure. It is monomeric and reverts to native oligomeric NTD upon SB3-10 dilution. The equilibrium GdnHCl-induced denaturation shows a cooperative folding and a somewhat lower conformational stability. When the aggregation processes were compared with and without pre-incubation with SB3-10, but at the identical final SB3-10 concentration, a slower aggregation was found in the former case, despite the reversible attainment of the native conformation in both cases. This was attributed to protein monomerization and oligomeric seeds disruption by the conditions promoting the alternative conformation. Overall, the results show a high plasticity of TDP-43 NTD and identify strategies to monomerise TDP-43 NTD for methodological and biomedical applications. 相似文献
825.
Activated nitrocompounds, in the presence of dipolarophiles and a tertiary diamine (e.g., DABCO), undergo dehydration to afford directly isoxazoline derivatives, formal cycloadducts of nitrile oxides; this mild procedure is very efficient for the synthesis of the reported isoxazolines. 相似文献
826.
Dr. Fabrizio Creazzo Prof. Sandra Luber 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(68):17024-17037
Notwithstanding that RuO2 is a promising catalyst for the oxygen evolution reaction (OER), a plethora of fundamental details on its catalytic properties are still elusive, severely limiting its large-scale deployment. It is also established experimentally that corrosion and wettability of metal oxides can, in fact, enhance the catalytic activity for OER owing to the formation of a hydrated surface layer. However, the mechanistic interplay between surface wettability, interfacial water dynamics and OER across RuO2, and what degree these processes are correlated are still debated. Herein, spin-polarized Density Functional Theory Molecular Dynamics (DFT-MD) simulations, coupled with advanced enhanced sampling methods in the well-tempered metadynamics framework, are applied to gain a global understanding of RuO2 aqueous interface (explicit water solvent) in catalyzing the OER, and hence possibly help in the design of novel catalysts in the context of photochemical water oxidation. The present study quantitatively assesses the free-energy barriers behind the OER at the (110)-RuO2 catalyst surface revealing plausible pathways composing the reaction network of the O2 evolution. In particular, OER is investigated at room temperature when such a surface is exposed to both gas-phase and liquid-phase water. Albeit a unique efficient pathway has been identified in the gas-phase OER, a surprisingly lowest-free-energy-requiring reaction route is possible when (110)-RuO2 is in contact with explicit liquid water. By estimating the free-energy surfaces associated to these processes, we reveal a noticeable water-assisted OER mechanism which involves a crucial proton-transfer-step assisted by the local water environment. These findings pave the way toward the systematic usage of DFT-MD coupled with metadynamics techniques for the fine assessment of the activity of catalysts, considering finite-temperature and explicit-solvent effects. 相似文献
827.
Michael R. Harvey Fabrizio Chiodo Wouter Noest Cornelis H. Hokke Gijsbert A. van der Marel Jeroen D.C. Code 《Molecules (Basel, Switzerland)》2021,26(8)
Schistosomiasis is caused by blood-dwelling parasitic trematodes of the genus Schistosoma and is classified by the WHO as the second most socioeconomically devastating parasitic disease, second only to malaria. Schistosoma expresses a complex array of glycans as part of glycoproteins and glycolipids that can be targeted by both the adaptive and the innate part of the immune system. Some of these glycans can be used for diagnostic purposes. A subgroup of schistosome glycans is decorated with unique α-(1-2)-fucosides and it has been shown that these often multi-fucosylated fragments are prime targets for antibodies generated during infection. Since these α-(1-2)-fucosides cannot be obtained in sufficient purity from biological sources, we set out to develop an effective route of synthesis towards α-(1-2)-oligofucosides of varying length. Here we describe the exploration of two different approaches, starting from either end of the fucose chains. The oligosaccharides have been attached to gold nanoparticles and used in an enzyme-linked immunosorbent assay ELISA and a microarray format to probe antibody binding. We show that binding to the oligofucosides of antibodies in sera of infected people depends on the length of the oligofucose chains, with the largest glycans showing most binding. 相似文献
828.
829.
Manuela Simonato Francesca Ricci Chiara Catozzi Matteo Storti Sonia Giambelluca Alessio Correani Fabrizio Salomone Paola Cogo Virgilio Carnielli 《Journal of mass spectrometry : JMS》2022,57(2):e4808
Stable isotope tracing can be safely used for metabolic studies in animals and humans. The endogenous biosynthesis of lipids (lipogenesis) is a key process throughout the entire life but especially during brain and lung growth. Adequate synthesis of pulmonary surfactant lipids is indispensable for life. With this study, we report the use of deuterium-depleted water (DDW), suitable for human consumption, as metabolic precursor for lipogenesis. We studied 13 adult rabbits for 5 days. Four rabbits drank tap water (TW) and served as controls; in four animals, DDW was substituted to drinking water, whereas five drank deuterium-enriched water (DEW). After 5 days, a blood sample and a bronchoalveolar lavage (BAL) sample were collected. The 2H/1H (δ2H) of BAL palmitic acid (PA) desaturated phosphatidylcholine (DSPC), the major phospholipid of pulmonary surfactant, and of plasma water was determined by high-resolution mass spectrometry. We found that the δ2H values of DDW, DEW and TW were −984 ± 2‰, +757 ± 2‰ and −58 ± 1‰, respectively. After 5 days, plasma water values were −467 ± 87‰, +377 ± 56‰ and −53 ± 6‰, and BAL DSPC-PA was −401 ± 27‰, −96 ± 38‰ and −249 ± 9‰ in the DDW, DEW and TW, respectively. With this preliminary study, we demonstrated the feasibility of using DDW to label pulmonary surfactant lipids. This novel approach can be used in animals and in humans, and we speculate that it could be associated with more favourable study compliance than DEW in human studies. 相似文献
830.