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141.
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143.
Feng X Sayle DC Wang ZL Paras MS Santora B Sutorik AC Sayle TX Yang Y Ding Y Wang X Her YS 《Science (New York, N.Y.)》2006,312(5779):1504-1508
Ceria nanoparticles are one of the key abrasive materials for chemical-mechanical planarization of advanced integrated circuits. However, ceria nanoparticles synthesized by existing techniques are irregularly faceted, and they scratch the silicon wafers and increase defect concentrations. We developed an approach for large-scale synthesis of single-crystal ceria nanospheres that can reduce the polishing defects by 80% and increase the silica removal rate by 50%, facilitating precise and reliable mass-manufacturing of chips for nanoelectronics. We doped the ceria system with titanium, using flame temperatures that facilitate crystallization of the ceria yet retain the titania in a molten state. In conjunction with molecular dynamics simulation, we show that under these conditions, the inner ceria core evolves in a single-crystal spherical shape without faceting, because throughout the crystallization it is completely encapsulated by a molten 1- to 2-nanometer shell of titania that, in liquid state, minimizes the surface energy. The principle demonstrated here could be applied to other oxide systems. 相似文献
144.
Zheng W Yates SR Papiernik SK Guo M Gan J 《Journal of agricultural and food chemistry》2006,54(6):2280-2287
The chlorinated fumigants chloropicrin (trichloronitromethane) and 1,3-dichloropropene (1,3-D) are extensively used in agricultural production for the control of soilborne pests. The reaction of these two fumigants with hydrogen sulfide species (H2S and HS-) was examined in well-defined anoxic aqueous solutions. Chloropicrin underwent an extremely rapid redox reaction in the hydrogen sulfide solution. Transformation products indicated reductive dechlorination of chloropicrin by hydrogen sulfide species to produce dichloro- and chloronitromethane. The transformation of chloropicrin in hydrogen sulfide solution significantly increased with increasing pH, indicating that H2S is less reactive toward chloropicrin than HS- is. For both 1,3-D isomers, kinetics and transformation products analysis revealed that the reaction between 1,3-D and hydrogen sulfide species is an S(N)2 nucleophilic substitution process, in which the chlorine at C3 of 1,3-D is substituted by the sulfur nucleophile to form corresponding mercaptans. The 50% disappearance time (DT50) of 1,3-D decreased with increasing hydrogen sulfide species concentration at a constant pH. Transformation of 1,3-D was more rapid at high pH, suggesting that the reactivity of hydrogen sulfide species in the experimental system stems primarily from HS-. Because of the relatively low smell threshold values and potential environmental persistence of organic sulfur products yielded by the reaction of 1,3-D and HS-, the effects of reduced sulfide species should be considered in the development of alternative fumigation practices, especially in the integrated application of sulfur-containing fertilizers. 相似文献
145.
Brown C Thompson S Vroegindewey G Pappaioanou M 《Journal of veterinary medical education》2006,33(3):411-415
Globalization has created an entirely new landscape for veterinarians. Opportunities abound to meet the formidable challenges presented as animals, people, and microbes travel at a previously unimagined speed, fueled by the engine of commerce, resulting in a plethora of new diseases, issues, and partnerships. Re-tooling our profession to ensure that we can continue to fulfill our veterinary oath in the face of these changes will require both short- and long-term changes. It is essential that a single overarching, non-affiliated organization be formed to tie together all entities, providing the structure to create needed synergy to enhance our currently fragmented professional responses and to solicit funds to effect necessary changes. 相似文献
146.
Bentz BG Maxwell LK Erkert RS Royer CM Davis MS MacAllister CG Clarke CR 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2006,20(3):589-594
The purpose of the study reported here was to describe the bioavailability and pharmacokinetics of acyclovir after intravenous and oral administration to horses. Six healthy adult horses were used in a randomized cross-over study with a 3 x 3 Latin square design. Three treatments were administered to each horse: 10 mg of injectable acyclovir/kg of body weight in 1 L of normal saline delivered as an infusion over 15 minutes; 10 mg of acyclovir/kg in tablets by nasogastric intubation; and 20 mg of acyclovir/kg in tablets by nasogastric intubation. A 2-week washout period was provided between each treatment. Serum samples were obtained for acyclovir assay using reversed-phase, high-performance liquid chromatography with fluorescence detection. Deproteinated serum was injected onto a C18 column, and elution occurred under isocratic conditions. The limit of quantification was 0.04 microg/mL. The assay exhibited suitable accuracy, precision, and recovery. The IV data were analyzed by a 3-compartment model, and oral data were analyzed noncompartmentally. Intragastric acyclovir administration at either dose was associated with high variability in serum acyclovir-time profiles, low Cmax, and poor bioavailability. The dosage of 20 mg/kg was associated with mean (+/- SD) Cmax of 0.19 +/- 0.10 microg/mL, and bioavailability was 2.8%. Inhibition of equine herpesvirus has been reported to require significantly higher acyclovir concentrations than those obtained here. The results of this study do not support a therapeutic benefit for the oral administration of acyclovir up to doses of 20 mg/kg. 相似文献
147.
Kronen PW Ludders JW Erb HN Moon PF Gleed RD Koski S 《Veterinary anaesthesia and analgesia》2006,33(4):258-265
OBJECTIVE: To evaluate whether a synthetic analogue of feline facial pheromone (FFP) calms cats before, and reduces struggling during intravenous catheterization. DESIGN: Block-randomized, 'blinded' clinical trial. ANIMALS: Seventy-seven healthy cats presented for elective surgery. PROCEDURE: Cats given glycopyrrolate and oxymorphone were assigned to one of four treatments: acepromazine and exposure to FFP (aceFFP); acepromazine and exposure to a placebo (acePlac); exposure to FFP only (FFP) and exposure to placebo only (Plac). The behaviour of cats was recorded on videotape for evaluation by assessors unaware of treatment group. Cats' veins were then catheterized by veterinary students unaware of the study protocol. Based on each cat's response to catheterization, the student independently decided whether intramuscular ketamine was required. RESULTS: Cats in the aceFFP group appeared to be calmer than acePlac cats on the basis of head position and their location in the cage (suggesting benefit from FFP among cats receiving acepromazine) but appeared to be less sedated. Cats in the aceFFP group also appeared to be calmer than FFP cats on the basis of head position and location in the cage. Feline facial pheromone cats were also calmer than Plac cats when compared using body and leg position. Exposure to FFP did not significantly reduce struggling at catheterization, nevertheless, the students were able to catheterize the veins in all cats. CONCLUSION AND CLINICAL RELEVANCE: There were no detrimental behavioural effects associated with either FFP or acepromazine. The FFP had additional calming effects in cats given acepromazine and, to a lesser degree, helped to calm cats that were not given acepromazine. Feline facial pheromone helps to calm cats in unfamiliar surroundings. 相似文献
148.
Hime T Reichardt PA Plourde BL Robertson TL Wu CE Ustinov AV Clarke J 《Science (New York, N.Y.)》2006,314(5804):1427-1429
The ability to switch the coupling between quantum bits (qubits) on and off is essential for implementing many quantum-computing algorithms. We demonstrated such control with two flux qubits coupled together through their mutual inductances and through the dc superconducting quantum interference device (SQUID) that reads out their magnetic flux states. A bias current applied to the SQUID in the zero-voltage state induced a change in the dynamic inductance, reducing the coupling energy controllably to zero and reversing its sign. 相似文献
149.
150.
Dunayer EK Gwaltney-Brant SM 《Journal of the American Veterinary Medical Association》2006,229(7):1113-1117
CASE DESCRIPTION: 8 adult dogs were evaluated for treatment of lethargy and vomiting after ingestion of xylitol, a sugar alcohol used as a sweetener in various products. CLINICAL FINDINGS: In addition to vomiting and lethargy, 5 of the dogs had widespread petechial, ecchymotic, or gastrointestinal tract hemorrhages. Common clinicopathologic findings included moderately to severely high serum activities of liver enzymes, hyperbilirubinemia, hypoglycemia, hyperphosphatemia, prolonged clotting times, and thrombocytopenia. Necropsies were performed on 3 dogs and severe hepatic necrosis was found in 2. In the third dog, histologic examination revealed severe hepatocyte loss or atrophy with lobular collapse. TREATMENT AND OUTCOME: Treatments varied among dogs and included IV administration of fluids; plasma transfusions; and, if indicated, administration of dextrose. Three dogs were euthanatized, 2 dogs died, 2 dogs made a complete recovery, and 1 dog was recovering but was lost to follow-up. CLINICAL RELEVANCE: Although xylitol causes hypoglycemia in dogs, hepatic failure after ingestion has not previously been reported. Because an increasing number of consumer products contain xylitol, clinicians should be aware that ingestion of xylitol can have serious, life-threatening effects. 相似文献