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211.
Michelle Min Fang Yee Kok-Yong Chin Soelaiman Ima-Nirwana Sok Kuan Wong 《Molecules (Basel, Switzerland)》2021,26(6)
Vitamin A is a fat-soluble micronutrient essential for growth, immunity, and good vision. The preformed retinol is commonly found in food of animal origin whereas provitamin A is derived from food of plant origin. This review summarises the current evidence from animal, human and cell-culture studies on the effects of vitamin A towards bone health. Animal studies showed that the negative effects of retinol on the skeleton were observed at higher concentrations, especially on the cortical bone. In humans, the direct relationship between vitamin A and poor bone health was more pronounced in individuals with obesity or vitamin D deficiency. Mechanistically, vitamin A differentially influenced the stages of osteogenesis by enhancing early osteoblastic differentiation and inhibiting bone mineralisation via retinoic acid receptor (RAR) signalling and modulation of osteocyte/osteoblast-related bone peptides. However, adequate vitamin A intake through food or supplements was shown to maintain healthy bones. Meanwhile, provitamin A (carotene and β-cryptoxanthin) may also protect bone. In vitro evidence showed that carotene and β-cryptoxanthin may serve as precursors for retinoids, specifically all-trans-retinoic acid, which serve as ligand for RARs to promote osteogenesis and suppressed nuclear factor-kappa B activation to inhibit the differentiation and maturation of osteoclasts. In conclusion, we suggest that both vitamin A and provitamin A may be potential bone-protecting agents, and more studies are warranted to support this hypothesis. 相似文献
212.
Quantification of curium isotopes in environmental samples: drawbacks,speciation and specific tracer
Habibi Azza Le Corre Roselyne Wampach Aubert Christèle Fleury Sandrine Hennequet Patricia Augeray Céline Galliez Kévin Agarande Michelle 《Journal of Radioanalytical and Nuclear Chemistry》2021,329(2):545-554
Journal of Radioanalytical and Nuclear Chemistry - In this study, drawbacks of the use of 243Am as a tracer in order to quantify curium isotopes during a complex chemical procedure were... 相似文献
213.
Tomasz Porba Michelle Ernst Dominik Zimmer Piero Macchi Nicola Casati 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(20):6697-6701
We report the high‐pressure structural characterization of an organic polyiodide salt in which a progressive addition of iodine to triiodide groups occurs. Compression leads to the initial formation of discrete heptaiodide units, followed by polymerization to a 3D anionic network. Although the structural changes appear to be continuous, the insulating salt becomes a semiconducting polymer above 10 GPa. The features of the pre‐reactive state and the polymerized state are revealed by analysis of the computed electron and energy densities. The unusually high electrical conductivity can be explained with the formation of new bonds. 相似文献
214.
Computational Management Science - We introduce a variant of Multicut Decomposition Algorithms, called CuSMuDA (Cut Selection for Multicut Decomposition Algorithms), for solving multistage... 相似文献
215.
Yonghui Wang Jian Jin Todd L. Graybill Michelle A. Wang Qian Jin 《Tetrahedron letters》2004,45(35):6645-6648
A protocol for monoacylation of unprotected symmetrical diamines with a resin-bound benzoic acid is described. The nature of the resin (gel-based polystyrene vs highly crosslinked macroporous polystyrene) was found to play a minor role in acylation selectivity. Rather, the concentration of the diamine dictates the ratio of mono- and diacylated products. Thus, by employing a high concentration of symmetrical diamine (e.g., 1 M, 20 equiv), monoacylation can be selectively achieved for a variety of unprotected symmetrical alkyl and aryl diamines. 相似文献
216.
Chemical and Physical Analysis of Acetate-Oxide Sol-Gel Processing Routes for the Y-Ba-Cu-O System 总被引:2,自引:0,他引:2
Tarek?MouganieEmail author Michelle?A.?Moram Joy?Sumner Bartek?A.?Glowacki Bart?Schoofs Isabel?Van?Driessche Serge?Hoste 《Journal of Sol-Gel Science and Technology》2005,36(1):87-94
The formation of three sols by fluorine-free aqueous and non-aqueous processes were analyzed and modified to vary the chemical properties of the sols (inks) to suit a variety of deposition processes such as dip-coating and ink-jet coating/printing. Ink-jet printing requires high wetting angles; choosing the right complexing agents to modify the ink allows the formation of droplets with high wetting angles on the surface. Dip-coating and ink-jet coating require low wetting angles; additives added to the sols reduce wetting angles to 10∘ and allow complete coverage of the substrate surface. The deposition theories and requirements are briefly discussed, as are some initial tests with the printing and converting of the developed superconducting inks. 相似文献
217.
Maximizing the Catalytic Activity of Nanoparticles through Monolayer Assembly on Nitrogen‐Doped Graphene
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Dr. Chao Yu Xuefeng Guo Mengqi Shen Bo Shen Michelle Muzzio Zhouyang Yin Prof. Qing Li Zheng Xi Junrui Li Prof. Christopher T. Seto Prof. Shouheng Sun 《Angewandte Chemie (International ed. in English)》2018,57(2):451-455
We report a facile method for assembly of a monolayer array of nitrogen‐doped graphene (NG) and nanoparticles (NPs) and the subsequent transfer of two layers onto a solid substrate (S). Using 3 nm NiPd NPs as an example, we demonstrate that NiPd‐NG‐Si (Si=silicon wafer) can function as a catalyst and show maximum NiPd catalysis for the hydrolysis of ammonia borane (H3NBH3, AB) with a turnover frequency (TOF) of 4896.8 h?1 and an activation energy (Ea) of 18.8 kJ mol?1. The NiPd‐NG‐S catalyst is also highly active for catalyzing the transfer hydrogenation from AB to nitro compounds, leading to the green synthesis of quinazolines in water. Our assembly method can be extended to other graphene and NP catalyst materials, providing a new 2D NP catalyst platform for catalyzing multiple reactions in one pot with maximum efficiency. 相似文献
218.
Sheila Sundaram Michelle Wachs 《Transactions of the American Mathematical Society》1997,349(3):935-954
We determine the character of the action of the symmetric group on the homology of the induced subposet of the lattice of partitions of the set obtained by restricting block sizes to the set . A plethystic formula for the generating function of the Frobenius characteristic of the representation is given. We combine techniques from the theory of nonpure shellability, recently developed by Björner and Wachs, with symmetric function techniques, developed by Sundaram, for determining representations on the homology of subposets of the partition lattice.
219.
Mau CM Nakao Y Yoshida WY Scheuer PJ Kelly-Borges M 《The Journal of organic chemistry》1996,61(18):6302-6304
From the sponge, Ircinia dendroides, collected in Indonesia we isolated a new cyclic hexapeptide, waiakeamide (1). Its structure, consisting of three proline residues, two methionine sulfoxides, and one thiazolylphenylalanine, was elucidated by spectral analysis and chemical degradation. Isolation and structural elucidation of waiakeamide is described. 相似文献
220.