نتایج جستجو برای: samarium compounds
تعداد نتایج: 227605 فیلتر نتایج به سال:
Experiments on co-doped CsI:Tl,Sm suggest that samarium electron traps scavenge electrons from thallium traps and that electrons subsequently released by samarium recombine non-radiatively with trapped holes, thus suppressing afterglow. These experiments support the inference that electrons tunnel freely between samarium ions and are trapped preferentially as substitutional Sm near VKA(Tl) cent...
A sensitive, simple method for the determination of trace amounts of samarium by spectrophotometry is described based on the formation of the samarium-chrome azurol S (CAS) complex in micellar medium. The molar absorptivities of the complexes at pH 7.5 at 505 nm were 3.6x10(4) and 1.4x10(5) l mol(-1) cm(-1) for water media and cetylpyridinium chloride (CPC), respectively. Beer's law is obeyed f...
One of the current therapeutic approaches in the treatment of osteoblastic bone metastases uses the affinity of Samarium ((153)Sm) ethylene-diamine-tetramethylene phosphonic acid (EDTMP) for bone areas of bone turnover. As Samarium EDTMP is a beta-emitter, the radiotherapy contributes to osteoblastic bone lesion control over time. To date, the safety and effectiveness of Samarium therapy have n...
Many years ago while studying for a degree in mineralogy, I was privileged to visit the Russian Ilmen Mountains, host to two minerals from which several rare-earth elements were discovered — monazite ((Ce, La, Nd, Th)PO4), and another mineral that was first described in 1839 by the German mineralogist Gustav Rose. He found uranium and tantalum in its composition and thus proposed the name urano...
Since thermoelectrics are an important way to produce electricity from waste heat, the thermoelectric properties of gadolinium copper telluride, GdCuTe2, together with the doped compounds gadolinium samarium copper telluride, Gd1-xSmxCuTe2, and gadolinium dysprosium copper telluride, Gd1-xDyxCuTe2, with x = 0.02 and x = 0.05 were investigated. Upon doping, a decrease in thermal conductivity and...
A samarium-mediated Barbier reaction was performed to aord N-acetylneuraminic acid -Cglycosyl compounds (`` -C-glycosides'') in excellent yield. The neuraminic acid phenyl sulfone or 2-pyridyl sulfone derivatives reacted with ketones or aldehydes resulting in the instantaneous and stereospeci®c formation of Neu5Ac -C-glycosides. The phenyl and the 2-pyridyl sulfone derivatives were equally ee...
In this communication we show that the instability of samarium diiodide (SmI(2)) in acetonitrile is a consequence of ionization of the reductant in this solvent. Samarium triflate (Sm(OTf)(2)) is exceptionally stable in acetonitrile for periods over six months and can be used with appropriate additives to initiate a ketyl-olefin coupling reaction in high yield.
The first synthesis of the racemic 8-deoxy WP3688-2 angucycline antibiotic (3), with characteristic cis-hydroxy groups at C-4 a and C-12b, is reported. Key steps involve the coupling, mediated by samarium diiodide, of the bicyclic trione 37 to the tricyclic cis-diol 39. Biomimetic aldol cyclization of the corresponding dione 41 gave a mixture of the tetracyclic cis- and trans-3,4a-diols 42 and ...
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