991 resultados para nearly-stoichiometric LiTaO3
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This paper investigates the gasification of two biomass types (pine wood and olive stones) in a laboratory scale bubbling fluidized bed reactor, in order to evaluate comparatively their potential in the production of syngas.
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Positron-emission tomography and functional MRS imaging signals can be analyzed to derive neurophysiological values of cerebral blood flow or volume and cerebral metabolic consumption rates of glucose (CMRGlc) or oxygen (CMRO2). Under basal physiological conditions in the adult mammalian brain, glucose oxidation is nearly complete so that the oxygen-to-glucose index (OGI), given by the ratio of CMRO2/CMRGlc, is close to the stoichiometric value of 6. However, a survey of functional imaging data suggests that the OGI is activity dependent, moving further below the oxidative value of 6 as activity is increased. Brain lactate concentrations also increase with stimulation. These results had led to the concept that brain activation is supported by anaerobic glucose metabolism, which was inconsistent with basal glucose oxidation. These differences are resolved here by a proposed model of glucose energetics, in which a fraction of glucose is cycled through the cerebral glycogen pool, a fraction that increases with degree of brain activation. The “glycogen shunt,” although energetically less efficient than glycolysis, is followed because of its ability to supply glial energy in milliseconds for rapid neurotransmitter clearance, as a consequence of which OGI is lowered and lactate is increased. The value of OGI observed is consistent with passive lactate efflux, driven by the observed lactate concentration, for the few experiments with complete data. Although the OGI changes during activation, the energies required per neurotransmitter release (neuronal) and clearance (glial) are constant over a wide range of brain activity.
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The effectiveness of drugs is often limited by their insufficient selectivity. I propose designs of therapeutic agents that address this problem. The key feature of these reagents, termed comtoxins (codominance-mediated toxins), is their ability to utilize codominance, a property characteristic of many signals in proteins, including degradation signals (degrons) and nuclear localization signals. A comtoxin designed to kill cells that express intracellular proteins P1 and P2 but to spare cells that lack P1 and/or P2 is a multidomain fusion containing a cytotoxic domain and two degrons placed within or near two domains P1* and P2* that bind, respectively, to P1 and P2. In a cell containing both P1 and P2, these proteins would bind to the P1* and P2* domains of the comtoxin and sterically mask the nearby (appropriately positioned) degrons, resulting in a long-lived and therefore toxic drug. By contrast, in a cell lacking P1 and/or P2, at least one of the comtoxin's degrons would be active (unobstructed), yielding a short-lived and therefore nontoxic drug. A comtoxin containing both a degron and a nuclear localization signal can be designed to kill exclusively cells that contain P1 but lack P2. Analogous strategies yield comtoxins sensitive to the presence (or absence) of more than two proteins in a cell. Also considered is a class of comtoxins in which a toxic domain is split by a flexible insert containing binding sites for the target proteins. The potentially unlimited, combinatorial selectivity of comtoxins may help solve the problem of side effects that bedevils present-day therapies, for even nonselective delivery of a comtoxin would not affect cells whose protein "signatures" differ from the targeted one.
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SIMS analyses have been carried out on clinopyroxenes, plagioclases and amphiboles of six gabbroic samples from Holes 921-924 of the Ocean Drilling Program Leg 153 sited in the MARK area of the Mid-Atlantic Ridge at the ridge-transform intersection, to investigate the rare earth, trace and volatile element distribution in the lower ocean crust during igneous crystallization and higher grade metamorphic conditions. The metagabbros underwent granulite to subgreenschist facies conditions through three main tectono-metamorphic phases: (1) ductile regime (750 < T < 1000 °C and P = 0.3 GPa); (2) transitional regime (600 < T < 700 °C and P = 0.2 GPa); (3) brittle regime (350 < T < 600 °C and P < 0.2 GPa). Igneous clinopyroxenes show Cl-chondrite normalized patterns depleted in LREE, and nearly flat for HREE. The rare earth and trace element distributions in igneous clinopyroxenes and plagioclases indicate that these minerals act as REE reservoirs, and comprise the main contribution to the overall rock content. The abundances in igneous minerals reflect the degree of fractionation of the parent liquids. In metamorphic clinopyroxenes recrystallized in anhydrous assemblages, the REE and trace elements patterns mimic those of the primary ones. Conversely, clinopyroxerie re-equilibrated in amphibolebearing assemblages shows a significant increase in REE, Ti, Zr, Y and V, a negative Eu anomaly, and slight decreases in Sr and Ba. An overall increase of REE and some trace elements is evident in hydrous assemblages, with preferential partitioning in the amphibole. It shows high Ti (18196-22844 ppm), LREE depleted patterns and LaN/SmN = 0.10-0.33, LaN/YbN = 0.10-0.30. Amphiboles from granoblastic assemblages show homogeneous patterns with no or a positive anomaly for TiN and negative anomalies for SrN and ZrN. Volatiles in amphibole are low, with Cl/F < 1; H2O% is significantly lower than the stoichiometric ratio (1.33-1.53%). The composition of the clinopyroxene and amphibole recrystallized in low-strain domains records evidence of incomplete re-equilibration, and element diffusion and partitioning is in part controlled by the textural site. The possible origins of the fluids involved in the metamorphic recrystallization are discussed: (1) remobilization from igneous amphibole; (2) exsolution from evolved melts; (3) introduction of seawater-derived fluids modified in rock-dominated systems; (4) injection of highly evolved hydrous melts during the metamorphic process.
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Includes sections on: comforts for invalids, removes, entrees, dishes with the remains of lamb, garniture for omlettes, beverages for evening parties.
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"Domestic wines and liquors": p. 226-236.
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Mode of access: Internet.
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Mode of access: Internet.
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Mode of access: Internet.