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Aiqin Wang et al.
Accounts of chemical research, 46(7), 1377-1386 (2013-02-21)
With diminishing fossil resources and increasing concerns about environmental issues, searching for alternative fuels has gained interest in recent years. Cellulose, as the most abundant nonfood biomass on earth, is a promising renewable feedstock for production of fuels and chemicals.
Malcolm H Chisholm et al.
Chemical record (New York, N.Y.), 5(5), 308-320 (2005-10-08)
The reaction of M2(O2CBu(t))4 (M = Mo, W) with a dicarboxylic acid in toluene yields compounds of general formula [M2]-O2C-X-CO2-[M2] ([M2] = M2(O2CBu(t))3; X = conjugated spacer). The M2 units are electronically coupled via interactions between the M2 delta and
Congshang Wan et al.
Ultramicroscopy, 119, 106-110 (2011-11-15)
Thermionic electron emission from 200 to 500 nm thick coatings of scandium oxide on tungsten foil have been examined in thermionic emission microscopy, spectroscopic photoelectron microcopy, synchrotron radiation and ultraviolet photoelectron spectroscopy (UPS). A clear dependence of the scandium oxide-W
A Koutsospyros et al.
Journal of hazardous materials, 136(1), 1-19 (2005-12-14)
Since its discovery, tungsten, a transition element of Group VIb of the Periodic Table of Elements, and its compounds have been considered environmentally benign. Its presence in biological and drinking water samples in Fallon, Nevada, an acute lymphocytic leukemia cluster
Vernon G Thomas et al.
Ecotoxicology and environmental safety, 72(4), 1031-1037 (2009-02-24)
The toxicity of elemental tungsten released from discharged shot was assessed against previous studies that established a 1% toxic threshold for soil organisms. Extremely heavy theoretical shot loadings of 69,000shot/ha were used to generate estimated environmental concentrations (EEC) for two
Matthias Boll et al.
Biological chemistry, 386(10), 999-1006 (2005-10-13)
The molybdenum enzymes 4-hydroxybenzoyl-CoA reductase and pyrogallol-phloroglucinol transhydroxylase and the tungsten enzyme acetylene hydratase catalyze reductive dehydroxylation reactions, i.e., transhydroxylation between phenolic residues and the addition of water to a triple bond. Such activities are unusual for this class of
José L Domingo
Biological trace element research, 88(2), 97-112 (2002-09-26)
Tungstate is an oxyanion that has biological similarities to vanadate. In recent years, a number of studies have shown the antidiabetic effects of oral tungstate in animal models of diabetes. However, because of the tissue accumulation and potential toxicity derived
Russ Hille
Trends in biochemical sciences, 27(7), 360-367 (2002-07-13)
Molybdenum is the only second-row transition metal that is required by most living organisms, and the few species that do not require molybdenum use tungsten, which lies immediately below molybdenum in the periodic table. Because of their unique chemical versatility
Hideki Sugimoto et al.
Chemical Society reviews, 37(12), 2609-2619 (2008-11-21)
Recent characterisation of molybdenum and tungsten enzymes revealed novel structural types of reaction centres, as well as providing new subjects of interest as synthetic chemical analogues. This tutorial review highlights the structure/reactivity relationships of the enzyme reaction centres and chemical
L Samuel Keith et al.
Toxicology and industrial health, 23(5-6), 309-345 (2008-04-05)
As part of its mandate, the Agency for Toxic Substances and Disease Registry prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation and Liability Act, National Priorities List sites that have the greatest public health impact. These
Carlos D Brondino et al.
Current opinion in chemical biology, 10(2), 109-114 (2006-02-17)
Mononuclear molybdenum and tungsten are found in the active site of a diverse group of enzymes that, in general, catalyze oxygen atom transfer reactions. Enzymes of the xanthine oxidase family are the best-characterized mononuclear Mo-containing enzymes. Several 3D structures of
Gijsbert B van der Voet et al.
Military medicine, 172(9), 1002-1005 (2007-10-17)
Tungsten and tungsten compounds are considered toxicologically relatively safe. Concern regarding the potential health and environmental effects of depleted uranium and lead in military applications has lead many countries to explore the possibility of applying toxicologically safer metals. Heavy metal
Dae Yup Han et al.
International journal of radiation oncology, biology, physics, 89(3), 666-673 (2014-04-23)
To demonstrate that utilization of the direction-modulated brachytherapy (DMBT) concept can significantly improve treatment plan quality in the setting of high-dose-rate (HDR) brachytherapy for cervical cancer. The new, MRI-compatible, tandem design has 6 peripheral holes of 1.3-mm diameter, grooved along
Jan R Andreesen et al.
Annals of the New York Academy of Sciences, 1125, 215-229 (2007-12-22)
The history and changing function of tungsten as the heaviest element in biological systems is given. It starts from an inhibitory element/anion, especially for the iron molybdenum-cofactor (FeMoCo)-containing enzyme nitrogenase involved in dinitrogen fixation, as well as for the many
Mehran Ahmadlou et al.
Nature communications, 6, 6773-6773 (2015-04-04)
The superior colliculus is a layered structure important for body- and gaze-orienting responses. Its superficial layer is, next to the lateral geniculate nucleus, the second major target of retinal ganglion axons and is retinotopically organized. Here we show that in
Mark L Witten et al.
Chemico-biological interactions, 196(3), 87-88 (2011-12-21)
There is emerging evidence that tungsten has toxic health effects. We summarize the recent tungsten toxicity research in this short review. Tungsten is widely used in many commercial and military applications because it has the second highest melting temperature of
N P L'vov et al.
Biochemistry. Biokhimiia, 67(2), 196-200 (2002-04-16)
The biological importance of tungsten has been fully proved in the last decade due to isolation of a number of tungsten-containing enzymes (W-enzymes) from hyperthermophilic archaea. Tungsten was previously considered only as an antagonist of molybdenum, because the replacement of
J R Marbach et al.
Physics in medicine and biology, 26(3), 435-443 (1981-05-01)
Curves relating beam energy, scattering foil thickness, central-axis depth-dose, and beam flatness have been generated using data taken on a Siemens 200A betatron. The curve set allows a single combination of tungsten foil thickness and electron beam energy to be
P Thongkumkoon et al.
Toxicology letters, 226(1), 90-97 (2014-02-08)
The toxicity of nanomaterials has been well known, but mechanisms involved have been little known. This study was aimed at looking at direct interaction between nanomaterials and naked DNA for some fundamental understanding. Two different types of nanomaterials, carbon nanotubes
C K Bomford
Medical physics, 3(2), 120-121 (1976-03-01)
Three causes of reduced output of orthovoltage radiotherapy units have recently been reported in this journal, each being due to faults external to the tube insert. A further incident is now reported where the output was reduced by 30% due
Ivan Jirka et al.
The journal of physical chemistry. B, 110(47), 23837-23844 (2006-11-28)
A model catalyst system, palladium on tungsten oxide, has been examined by temperature-programmed desorption and photoemission spectroscopy. The samples were prepared by evaporation of palladium onto an oxidized tungsten foil under ultrahigh vacuum conditions. Mostly three-dimensional (3-D) palladium (Pd) clusters
Maria João Romão
Dalton transactions (Cambridge, England : 2003), (21)(21), 4053-4068 (2009-05-20)
Molybdenum and tungsten enzymes which contain the pyranopterin cofactor are ubiquitous in Nature and perform a wide variety of biological functions. They catalyze a diversity of mostly two-electron oxidation-reduction reactions crucial in the metabolism of nitrogen, sulfur and carbon. These
Synthetic analogues and reaction systems relevant to the molybdenum and tungsten oxotransferases.
John H Enemark et al.
Chemical reviews, 104(2), 1175-1200 (2004-02-12)
Elias Papaconstantinou et al.
Frontiers in bioscience : a journal and virtual library, 8, s813-s825 (2003-09-06)
Polyoxometalates (POM) have a rich and promising photochemical behavior. Upon illumination at the O M CT band (i.e., in UV and near-visible area) become powerful oxidizing reagents able to oxidize various organic compounds. In the process POM undergo stepwise reduction
K C Li et al.
The New Zealand dental journal, 110(4), 138-142 (2015-01-20)
The purpose of the study was to observe whether conventional porcelain firings had an effect on the underlying microstructure of cobalt-chromium alloys used in porcelain-fused-to-metal systems. One as cast (non-veneered) and two porcelain veneered Co-Cr specimens layered with and without
Richard R Schrock et al.
Angewandte Chemie (International ed. in English), 42(38), 4592-4633 (2003-10-09)
Catalytic olefin metathesis has quickly emerged as one of the most often-used transformations in modern chemical synthesis. One class of catalysts that has led the way to this significant development are the high-oxidation-state alkylidene complexes of molybdenum. In this review
Nikolay Strigul
Ecotoxicology and environmental safety, 73(6), 1099-1113 (2010-09-16)
Tungsten is a widely used transition metal that has not been thoroughly investigated with regards to its ecotoxicological effects. Tungsten anions polymerize in environmental systems as well as under physiological conditions in living organisms. These polymerization/condensation reactions result in the
Frank R Cichocki et al.
Journal of biomedical materials research. Part B, Applied biomaterials, 94(2), 493-500 (2010-06-25)
Suture needles are essential instruments for performing blood vessel anastomosis in coronary artery bypass graft (CABG) surgeries. Exceptional needle performance is needed now as never before because of the increasing prevalence of elderly patients with advanced stages of coronary disease
V N Korobenko et al.
Journal of physics. Condensed matter : an Institute of Physics journal, 26(4), 045701-045701 (2014-01-07)
Tungsten foil strip sandwiched between two sapphire plates was rapidly heated by an electrical current pulse so that it experienced a two-fold thermal expansion in less than 400 ns under increasing dynamic pressure. The dependence of density on specific enthalpy
S Miao-Kang et al.
The Analyst, 117(2), 137-140 (1992-02-01)
A sensitive, selective method for the determination of lanthanum in food and water samples by atomic absorption spectrometry using a graphite tube lined with tungsten foil is described. The atomization of lanthanum from the tungsten surface gives better analytical sensitivity
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