948 resultados para basic carbonate
Effect of internal partitioning on indoor air quality of rooms with mixing ventilation - basic study
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The internal partitioning, which is frequently introduced in open-space planning due to its flexibility, was tested to study its effects on the room air quality as well as ventilation performance. For the study, physical tests using a small model room and numerical modeling using CFD computation were utilized to evaluate different test conditions employing mixing ventilation from the ceiling. The partition parameters, such as its location, height, and the gap underneath, as well as contaminant source location were tested under isothermal conditions. This paper summarizes the results from the study.
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Over the last 25 years, the effects of fatty acids on the immune system have been characterized using in vitro, animal and human studies. Advances in fatty acid biochemistry and molecular techniques have recently suggested new mechanisms by which fatty acids could potentially modify immune responses, including modification of the organization of cellular lipids and interaction with nuclear receptors. Possibilities for the clinical applications of n-3 PUFA are now developing. The present review focuses on the hypothesis that the anti-inflammatory properties of n-3 PUFA in the arterial wall may contribute to the protective effects of n-3 PUFA in CVD, as suggested by epidemiological and secondary prevention studies. Studies are just beginning to show that dietary n-3 PUFA can be incorporated into plaque lipid in human subjects, where they may influence the morphology and stability of the atherosclerotic lesion.
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The influence of soil organisms on metal mobility and bioavailability in soils is not currently fully understood. We conducted experiments to determine whether calcium carbonate granules secreted by the earthworm Lumbricus terrestris could incorporate and immobilise lead in lead- and calcium- amended artificial soils. Soil lead concentrations were up to 2000 mg kg-1 and lead:calcium ratios by mass were 0.5-8. Average granule production rates of 0.39 + 0.04 mgcalcite earthworm-1 day-1 did not vary with soil lead concentration. The lead:calcium ratio in granules increased significantly with that of the soil (r2 = 0.81, p = 0.015) with lead concentrations in granules reaching 1577 mg kg-1. X-ray diffraction detected calcite and aragonite in the granules with indications that lead was incorporated into the calcite at the surface of the granules. In addition to the presence of calcite and aragonite X-ray absorption spectroscopy indicated that lead was present in the granules mainly as complexes sorbed to the surface but with traces of lead-bearing calcite and cerussite. The impact that lead-incorporation into earthworm calcite granules has on lead mobility at lead-contaminated sites will depend on the fraction of total soil lead that would be otherwise mobile.
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The dissolution of CaCO3 granules secreted by earthworms in soil leaching columns was governed by soil pH and exchange sites available for Ca. Results indicate that granules could last for significant periods of time in soils and that, therefore, granules could be an important source of soil calcite.
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Lumbricus terrestris earthworms exposed to 11 soils of contrasting properties produced, on average, 0.8 ± 0.1 mgCaCO3 earthworm−1 day−1 in the form of granules up to 2 mm in diameter. Production rate increased with soil pH (r2 = 0.68, p < 0.01). Earthworms could be a significant source of calcite in soils.
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We show how teacher judgements can be used to assess the quality of vocabulary used by L2 learners of French.
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Earthworms secrete granules of calcium carbonate. These are potentially important in soil biogeochemical cycles and are routinely recorded in archaeological studies of Quaternary soils. Production rates of calcium carbonate granules by the earthworm Lumbricus terrestris L. were determined over 27 days in a range of soils with differing chemical properties (pH, organic matter content, water holding capacity, bulk composition, cation exchange capacity and exchangeable cations). Production rate varied between soils, lay in the range 0–0.043 mmolCaCO3 (0–4.3 mg) earthworm−1 d−1 with an average rate of 8 × 10−3 mmolCaCO3 (0.8 mg) earthworm−1 d−1 and was significantly correlated (r = 0.68, P ≤ 0.01) with soil pH. In a second experiment lasting 315 days earthworms repeatedly (over periods of 39–57 days) produced comparable masses of granules. Converting individual earthworm granule production rates into fluxes expressed on per hectare of land per year basis depends heavily on estimates of earthworm numbers. Using values of 10–20 L. terrestris m−2 suggests a rate of 18– 3139 molCaCO3 ha−1 yr−1. Data obtained from flow-through dissolution experiments suggest that at near neutral pH, granule geometric surface areanormalised dissolution rates are similar to those for other biogenic and inorganic calcium carbonate. Fits of the data to the dissolution relationship r = k(1 − ˝)n where r = dissolution rate, k = a rate constant, ˝ = relative saturation and n = the reaction order gave values of k = 1.72 × 10−10 mol cm−2 s−1 and n = 1.8 for the geometric surface area-normalised rates and k = 3.51 × 10−13 mol cm−2 s−1 and n = 1.8 for the BET surface area-normalised rates. In 196 day leaching column experiments trends in granule dissolution rate referenced to soil chemistry corresponded to predictions made by the SLIM model for dissolution of limestone in soil. If soil solution approaches saturation with respect to calcium carbonate granule dissolution will slow or even stop and granules be preserved indefinitely. Granules have the potential to be a small but significant component of the biogeochemical cycling of C and Ca in soil.
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The complex [(C(NH2)3)3ZrOH(CO3)3·H2O]2 (A) has been shown by means of a single crystal X-ray diffraction study to contain [C(NH2)3]+ cations and dimeric anions of formulation [(ZrOH(CO3)3)2]6−. The anion is centrosymmetric with each metal being bonded to two bridging OH groups and three chelating CO2−3 ions. The Zr atoms are thus eight coordinate with a dodecahedral environments. The ZrO distances formed by the bridgng OH groups are shorter than those formed through zirconiu carbonate interactions. The non-bonded Zr…Zr distance is 3.47(2) Å. An infrared spectroscopic investigation of A provides data which support the findings of the crystallographic study. Likewise the complex Na6(ZrOH(CO2O4)3)2·7H2O (B) contains the anion [(ZrOH(C2O4)3)2]6−. This anion is structurally related to the anion in A as each Zr atom has an eight-coordinate dodecahedral environment being bonded to two bridging OH groups and three chelating oxalate ligands, but has no imposed crysallographic symmetry. The Zr…Zr non-bonded distance is 3.50(1) Å. The OZrO bridge angles are 69.7(4)° and A and 67.4(3)° in B.
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The impact of North Atlantic SST patterns on the storm track is investigated using a hierarchy of GCM simulations using idealized (aquaplanet) and “semirealistic” boundary conditions in the atmospheric component (HadAM3) of the third climate configuration of the Met Office Unified Model (HadCM3). This framework enables the mechanisms determining the tropospheric response to North Atlantic SST patterns to be examined, both in isolation and in combination with continental-scale landmasses and orography. In isolation, a “Gulf Stream” SST pattern acts to strengthen the downstream storm track while a “North Atlantic Drift” SST pattern weakens it. These changes are consistent with changes in the extratropical SST gradient and near-surface baroclinicity, and each storm-track response is associated with a consistent change in the tropospheric jet structure. Locally enhanced near-surface horizontal wind convergence is found over the warm side of strengthened SST gradients associated with ascending air and increased precipitation, consistent with previous studies. When the combined SST pattern is introduced into the semirealistic framework (including the “North American” continent and the “Rocky Mountains”), the results suggest that the topographically generated southwest–northeast tilt in the North Atlantic storm track is enhanced. In particular, the Gulf Stream shifts the storm track south in the western Atlantic whereas the strong high-latitude SST gradient in the northeastern Atlantic enhances the storm track there.
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Certain embodiments include carbonate esters of rapamycin at position 42 that are synthesized by a lipase catalyzed regio-specific process. These compounds or a pharmaceutically acceptable salt thereof are useful in the treatment of organ and tissue transplant rejection, autoimmune disease, proliferative disorder, restenosis, cancer, or microbial infection.