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941.
Novel lithiated carbanions derived from ethyl glycosyl- and diglycosyl methylphosphonates were used in a direct and convenient synthesis of P1,P2-diglycosyl, P1,P1,P2-triglycosyl, and P1,P1,P2,P2-tetraribosyl methylenediphosphonates involving a one-pot methylidenediphosphonylation of sugars. 相似文献
942.
The socle of a graded Buchsbaum module is studied and is related to its local cohomology modules. This algebraic result is then applied to face enumeration of Buchsbaum simplicial complexes and posets. In particular, new necessary conditions on face numbers and Betti numbers of such complexes and posets are established. These conditions are used to settle in the affirmative Kühnel's conjecture for the maximum value of the Euler characteristic of a 2k-dimensional simplicial manifold on n vertices as well as Kalai's conjecture providing a lower bound on the number of edges of a simplicial manifold in terms of its dimension, number of vertices, and the first Betti number. 相似文献
943.
Bassam Felipe Mogharbel Marco Andr Cardoso Ana Carolina Irioda Priscila Elias Ferreira Stricker Robson Camilotti Slompo Julia Maurer Appel Nathalia Barth de Oliveira Maiara Carolina Perussolo Claudia Sayuri Saaki Nadia Nascimento da Rosa Dilcele Silva Moreira Dziedzic Christophe Travelet Sami Halila Redouane Borsali Katherine Athayde Teixeira de Carvalho 《Molecules (Basel, Switzerland)》2022,27(9)
Background: Parkinson’s disease (PD) is the second most common age-related neurodegenerative disorder. Levodopa (L-DOPA) remains the gold-standard drug available for treating PD. Curcumin has many pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial, anti-amyloid, and antitumor properties. Copolymers composed of Poly (ethylene oxide) (PEO) and biodegradable polyesters such as Poly (ε-caprolactone) (PCL) can self-assemble into nanoparticles (NPs). This study describes the development of NH2–PEO–PCL diblock copolymer positively charged and modified by adding glutathione (GSH) on the outer surface, resulting in a synergistic delivery of L-DOPA curcumin that would be able to pass the blood–brain barrier. Methods: The NH2–PEO–PCL NPs suspensions were prepared by using a nanoprecipitation and solvent displacement method and coated with GSH. NPs were submitted to characterization assays. In order to ensure the bioavailability, Vero and PC12 cells were treated with various concentrations of the loaded and unloaded NPs to observe cytotoxicity. Results: NPs have successfully loaded L-DOPA and curcumin and were stable after freeze-drying, indicating advancing into in vitro toxicity testing. Vero and PC12 cells that were treated up to 72 h with various concentrations of L-DOPA and curcumin-loaded NP maintained high viability percentage, indicating that the NPs are biocompatible. Conclusions: NPs consisting of NH2–PEO–PCL were characterized as potential formulations for brain delivery of L-DOPA and curcumin. The results also indicate that the developed biodegradable nanomicelles that were blood compatible presented low cytotoxicity. 相似文献
944.
945.
Based on measurements we investigate the velocity-power characteristic of a 2 MW wind turbine. We apply a stochastic analysis where we describe the evolution of the power output with a Langevin equation, with special respect to short-time fluctuations in wind speed. Standard procedures, such as the IEC 61400-12 standard, are limited due to the fact that only mean values over several minutes of wind speed and power output are considered. According to this, short-time dynamics of wind and power fluctuations are usually not taken into account. We introduce an improved method which enables us to extract these dynamics of the power characteristic from the measured data. In particular, we get the response dynamics of the power L (u (t)) via the estimation of Kramers-Moyal coefficients, describing its evolution in time (t) with a Langevin equation where we separate the power output into a relaxation and a noise part. A fixed-point analysis provides the required power characteristic. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
946.
Dr. Matteo Capone Dr. Abhishek Sirohiwal Prof. Massimiliano Aschi Dr. Dimitrios A. Pantazis Prof. Isabella Daidone 《Angewandte Chemie (International ed. in English)》2023,62(16):e202216276
Photosystem-II (PSII) is a multi-subunit protein complex that harvests sunlight to perform oxygenic photosynthesis. Initial light-activated charge separation takes place at a reaction centre consisting of four chlorophylls and two pheophytins. Understanding the processes following light excitation remains elusive due to spectral congestion, the ultrafast nature, and multi-component behaviour of the charge-separation process. Here, using advanced computational multiscale approaches which take into account the large-scale configurational flexibility of the system, we identify two possible primary pathways to radical-pair formation that differ by three orders of magnitude in their kinetics. The fast (short-range) pathway is dominant, but the existence of an alternative slow (long-range) charge-separation pathway hints at the evolution of redundancy that may serve other purposes, adaptive or protective, related to formation of the unique oxidative species that drives water oxidation in PSII. 相似文献
947.
Laura Köring Dr. Arne Stepen Dr. Bernhard Birenheide Simon Barth Maxim Leskov Dr. Roland Schoch Dr. Felix Krämer Prof. Dr. Frank Breher Prof. Dr. Jan Paradies 《Angewandte Chemie (International ed. in English)》2023,62(13):e202216959
A series of redox-responsive ferrocenyl-substituted boranes and boronic esters were synthesized. Oxidation of the ferrocenyl ligand to the ferrocenium resulted in a drastic increase in the Lewis acidity beyond the strength of SbF5, which was investigated experimentally and computationally. The resulting highly Lewis acidic boron compounds were used for catalytic C−F and S−F bond activation. 相似文献
948.
Maurizio Galimberti Emilio Martini Fabrizio Piemontesi Franco Sartori Isabella Camurati Luigi Resconi Enrico Albizzati 《Macromolecular Symposia》1995,89(1):259-275
In this paper, new polyolefin elastomers, obtained from metallocene based catalytic systems, are presented. The potentialities of metallocenes for the preparation of polyolefin elastomers are discussed with reference to the traditional vanadium and titanium based catalysts. The role played by a Ziegler - Natta catalyst, either stereospecific or aspecific, is discussed. 相似文献
949.
Dr. Lorena Mendive-Tapia Dr. Laia Miret-Casals Dr. Nicole D. Barth Jinling Wang Dr. Anne de Bray Dr. Massimiliano Beltramo Vincent Robert Prof. Dr. Christophe Ampe Prof. Dr. David J. Hodson Prof. Dr. Annemieke Madder Prof. Dr. Marc Vendrell 《Angewandte Chemie (International ed. in English)》2023,62(20):e202302688
The G protein-coupled kisspeptin receptor (GPR54 or KISS1R) is an important mediator in reproduction, metabolism and cancer biology; however, there are limited fluorescent probes or antibodies for direct imaging of these receptors in cells and intact tissues, which can help to interrogate their multiple biological roles. Herein, we describe the rational design and characterization of a new acid-resistant BODIPY-based amino acid (Trp-BODIPY PLUS), and its implementation for solid-phase synthesis of fluorescent bioactive peptides. Trp-BODIPY PLUS retains the binding capabilities of both short linear and cyclic peptides and displays notable turn-on fluorescence emission upon target binding for wash-free imaging. Finally, we employed Trp-BODIPY PLUS to prepare some of the first fluorogenic kisspeptin-based probes and visualized the expression and localization of GPR54 receptors in human cells and in whole mouse pancreatic islets by fluorescence imaging. 相似文献
950.
Yaowen Liu Martin C. Dietl Robin Heckershoff Chunyu Han Hongwei Shi Dr. Matthias Rudolph Dr. Frank Rominger Dr. Isabella Caligiuri Kanwal Asif Muhammad Adeel Dr. Thomas Scattolin Prof. Dr. A. Stephen K. Hashmi 《Angewandte Chemie (International ed. in English)》2023,62(34):e202304672
Due to its excellent bioactivity profile, which is increasingly utilized in pharmaceutical and synthetic chemistry, spirooxindole is an important core scaffold. We herein describe an efficient method for the construction of highly functionalized new spirooxindolocarbamates via a gold-catalyzed cycloaddition reaction of terminal alkynes or ynamides with isatin-derived ketimines. This protocol has a good functional group compatibility, uses readily available starting materials, mild reaction conditions, low catalyst loadings and no additives. It enables the transformation of various functionalized alkyne groups into cyclic carbamates. Gram-scale synthesis was achieved and DFT calculations verify the feasibility of the mechanistic proposal. Some of the target products exhibit good to excellent antiproliferative activity on human tumor cell lines. In addition, one of the most active compounds displayed a remarkable selectivity towards tumor cells over normal ones. 相似文献