نتایج جستجو برای: metal ions

تعداد نتایج: 311944  

2004
Ricardo B. Metz

Multiply charged ions are intruiging species whose reactivity and thermodynamic stability depends on the extent of ligation. The possibility of dissociating to two singly charged ions, which is often highly exothermic, leads to spectroscopy and dissociation dynamics that are qualitatively different from their singly charged counterparts. Various methods of producing multiply charged ions are di...

Journal: :Biochemistry 2001
S Shan A V Kravchuk J A Piccirilli D Herschlag

Divalent metal ions play a crucial role in catalysis by many RNA and protein enzymes that carry out phosphoryl transfer reactions, and defining their interactions with substrates is critical for understanding the mechanism of biological phosphoryl transfer. Although a vast amount of structural work has identified metal ions bound at the active site of many phosphoryl transfer enzymes, the numbe...

Journal: :Dental materials : official publication of the Academy of Dental Materials 1993
J C Wataha C T Hanks R G Craig

The effect of cell density (number of cells per unit area of a monolayer culture) on the in vitro cytotoxicity of metal ions which are known to be released from dental materials was investigated. The effects of cell density (1) may explain previous discrepancies in in vitro tests, (2) may be important in wound healing where cell density changes over time, and (3) may help clarify the mechanisms...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت معلم تهران - دانشکده علوم 1379

لایه نیترات سیلیکون ‏‎(sixny)‎‏ در صنایع میکروالکترونیک کاربرد فراوانی پیدان کرده است. به عنوان نمونه مواردی از قبیل: لایه های دی الکتریک عایق، سدهای نفوذی (در مقابل اکسیژن، رطوبت، سدیم و...) استفاده به عنوان ماسک در تهیه مدارات مجتمع و خواص فعال - غیرفعال سازی در قطعات الکترونیکی را می توان نام برد. این خصوصیات به مقدار زیادی به روش ساخت، نسبت استوکیومتری مناسب ‏‎(si3n4)‎‏ وجود ناخالصی هایی مث...

Journal: :Metal-Based Drugs 1997

Journal: :Nature materials 2009
Jun Yang Edward H Sargent Shana O Kelley Jackie Y Ying

Nanocrystals prepared in organic media can be easily self-assembled into close-packed hexagonal monolayers on solvent evaporation for various applications. However, they usually rely on the use of organometallic precursors that are soluble in organic solvents. Herein we report a general protocol to transfer metal ions from an aqueous solution to an organic medium, which involves mixing the aque...

2001
Y. S. Ho G. McKay C. F. Forster

A pseudo-second order rate equation describing the kinetics of sorption of divalent metal ions on to sphagnum moss peat at various initial metal ion concentrations and peat doses has been developed. The sorption kinetics were followed based on the concentrations of metal sorbed at various time intervals. Results show that chemical sorption processes might be rate-limiting for the sorption of di...

2014
Qingqing Wang Jing Cui Guohui Li Jinning Zhang Fenglin Huang

In this work, amidoxime polyacrylonitrile (AOPAN) nanofibrous membrane was prepared by a reaction between PAN nanofibers and hydroxylamine hydrochloride. The AOPAN nanofibrous membranes were used for four metal ions (Fe, Cu, Ni, Cd) chelation under different conditions. Further, the competition of different metal ions coordinating with AOPAN nanofibrous membrane was also studied. The AOPAN chel...

Journal: :Macromolecular Rapid Communications 2012

Journal: :RNA 2012
John K Frederiksen Nan-Sheng Li Rhiju Das Daniel Herschlag Joseph A Piccirilli

Within the three-dimensional architectures of RNA molecules, divalent metal ions populate specific locations, shedding their water molecules to form chelates. These interactions help the RNA adopt and maintain specific conformations and frequently make essential contributions to function. Defining the locations of these site-bound metal ions remains challenging despite the growing database of R...

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