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81.
Photocatalytic properties of titania have been studied very intensively for a variety of applications, including air and water purification. In order to clarify the influence of the phase composition and other parameters, thermal spraying with suspensions was applied to produce photocatalytically active titania coatings starting from two commercially available anatase and rutile submicron powders. Aqueous suspensions containing 40% solids by weight were sprayed with an HVOF process using ethylene as the fuel gas. The spray parameters were chosen in order to produce mechanically stable coatings and to preserve a high content of the initial crystalline phases of the powders. The coating microstructures, phase compositions, and surface properties were characterized. The photocatalytic performance was evaluated by degradation of the pink dye Rhodamine B (RB) using two techniques: degradation of an aqueous solution of RB and discoloration of impregnated RB. All the coatings exhibited photocatalytic activity to varying degrees, depending on the phase composition as well as other factors, namely, the coating microstructure, surface morphology, surface hydroxylation, light absorption, and interaction with the pollutant.  相似文献   
82.
Bunch compactness (or density) is a grapevine specific trait that affects the commercial quality and sanitary status of wine and tablegrapes. Compact bunches are more susceptible to diverse pests and diseases such as Botrytis bunch rot and their berries ripen more heterogeneously, causing important economic losses through a reduction in crop yield and grape and wine quality. Bunch compactness is determined by the fraction of the morphological volume of the bunch that is filled by berries, but this simple definition contrasts sharply with the difficulty to measure it. While there are several objective and quantitative methods available to measure bunch compactness, the lack of a consistent approach between researchers makes comparing measurements difficult. The complexity of bunch compactness initially arises from the several bunch and berry traits that influence it, and from the distinct effects that these traits may cause in different cultivars. In addition to this genetic effect, diverse environmental signals impact on bunch compactness by affecting those primary factors that contribute to the solid component of the bunch (berry number, berry size) or to its spatial arrangement (rachis architecture). Last, several viticultural approaches, including agronomic techniques and growth regulators, have also proven to affect bunch compactness in different ways. This review aims to discuss present knowledge about this relevant grapevine trait.  相似文献   
83.
    
Colloidal quantum dots (CQDs) are nanoscale building blocks for bottom‐up fabrication of semiconducting solids with tailorable properties beyond the possibilities of bulk materials. Achieving ordered, macroscopic crystal‐like assemblies has been in the focus of researchers for years, since it would allow exploitation of the quantum‐confinement‐based electronic properties with tunable dimensionality. Lead‐chalcogenide CQDs show especially strong tendencies to self‐organize into 2D superlattices with micrometer‐scale order, making the array fabrication fairly simple. However, most studies concentrate on the fundamentals of the assembly process, and none have investigated the electronic properties and their dependence on the nanoscale structure induced by different ligands. Here, it is discussed how different chemical treatments on the initial superlattices affect the nanostructure, the optical, and the electronic‐transport properties. Transistors with average two‐terminal electron mobilities of 13 cm2 V?1 s?1 and contactless mobility of 24 cm2 V?1 s?1 are obtained for small‐area superlattice field‐effect transistors. Such mobility values are the highest reported for CQD devices wherein the quantum confinement is substantially present and are comparable to those reported for heavy sintering. The considerable mobility with the simultaneous preservation of the optical bandgap displays the vast potential of colloidal QD superlattices for optoelectronic applications.  相似文献   
84.
85.
The degradation mechanisms of Pt nanoparticles supported on Carbon have been characterized during oxygen reduction reaction (ORR) conditions using IL-TEM. A TEM grid is used as the sole working electrode allowing a direct correlation between the electrochemical response and the TEM analysis. We mainly observe a decrease in nanoparticle size with some particle disappearance and some particle sintering after potential cycling simulating the start-up and shut-down of a fuel cell. The observation of nanoparticles with reduced particle size provides evidence that dissolution phenomena are the main cause of degradation in Pt/C electrocatalysts, under ORR conditions.  相似文献   
86.
PURPOSE: To analyze the results of round 1 of the population-based Valencia Breast Cancer Screening Program. MATERIALS AND METHODS: In this program, 78,224 (72.98%) of the 107,178 women invited (aged 45-65 years) underwent screening. Complementary views were obtained in 5,771 women (7.38%). Among the total population studied, 3,502 (4.48%) underwent short-term mammographic follow-up studies; 3,898 (4.98%) underwent additional studies and treatment at hospitals. Five hundred eighty-seven women (0.75%) underwent biopsy. RESULTS: Cancer was detected in 334 patients (4.27 cancers per 1,000 women [3.24 per 1,000 women aged 45-49 years, 6.30 per 1,000 women aged 60-65 years]; six patients with lobular carcinoma in situ excluded). The estimated sensitivity was 89%; specificity, 99%. The positive predictive value of mammography was 8.56%; of mammography with additional examinations, 26.82%; and of biopsy, 56.89%. Forty-one patients (12.28%) had ductal carcinoma in situ; 284 (85.03%) had infiltrating carcinoma. In 73 (25.70%) of the 284 patients, infiltrating carcinomas were smaller than 1 cm. Two hundred twenty-five patients (76.27%) had no lymph node involvement. One hundred seventy-nine (61.09%) had stage 0 or 1 cancer. CONCLUSION: Results are consistent with other published results; differences are due to methods and patient population characteristics.  相似文献   
87.
88.
Traumatic optic neuropathy (TON) causes blindness of varied severity and occurs infrequently as a complication of closed head injury. A case is presented of TON that occurred in a patient who suffered complete T4 paraplegia from a motorcycle accident but in whom no severe head injury took place. In this case, high-dose intravenous methylprednisolone was begun for the spinal cord injury and repeated 24 hours later for the TON. Vision improved from near total blindness to 20/400 in the left eye (OS) and 20/130 in the right eye (OD). Two weeks later, however, the patient's vision suddenly worsened. Magnetic resonance imaging (MRI) using fat suppression confirmed a lesion along the optic nerve consistent with TON. A third course of methylprednisolone again led to improved vision. The steroids were then tapered orally over 2 weeks and the patient had no further relapses. Moderate to severely impaired vision of 20/ 400 OS and 20/130 OD continues to interfere with the patient's function and spinal cord rehabilitation program. It was concluded that a steroid taper was important in maintaining initial visual gains in this case. Awareness of TON and careful attention to the patient's clinical course can minimize deficit and maximize functional outcomes.  相似文献   
89.
Neuroblastoma, a childhood tumour of the sympathetic nervous system, may sometimes regress spontaneously in infants, or progress to a poor clinical outcome despite intensive therapy. Neuroblastomas express neurotrophin receptors and high levels of mRNA for trk-A correlates with favourable outcome, whereas trk-B mRNA is expressed by more unfavourable tumours. Using a sensitive RNase protection assay, mRNA expression for the neurotrophin receptor trk-C was investigated in 50 tumour samples from 45 children at different stages including metastatic and relapsing tumour tissue, out of which 22 were also investigated for trk-A mRNA. Thirty-seven of 43 primary tumours (86%) showed trk-C mRNA with more than 300-fold difference between the highest and the lowest values. A higher trk-C index (trk-C mRNA/GAPDH mRNA) was associated with favourable features such as younger age (P = 0.009-0.003), favourable tumour stage (1, 2 or 4S; P < 0.001) and favourable prognosis (P = 0.044). Better survival probability was shown in children with intermediate or high trk-C index compared with patients with low or undetectable levels (P = 0.031). All localised tumours co-expressed mRNA for trk-A and trk-C receptors. RT-PCR analysis detected mRNA encoding the cytoplasmic trk-C tyrosine kinase region only in favourable neuroblastomas. We conclude that favourable neuroblastoma may express the full-length trk-C receptor while unfavourable tumours, especially those with MYCN amplification, seem to either express no trk-C or truncated trk-C receptors with unknown biological function. Trk-C and possibly its preferred ligand NT-3 may be involved in the biology of favourable neuroblastomas showing apoptosis or differentiation.  相似文献   
90.
This paper reports on the synthesis of triglycerides by enzymatic esterification of polyunsaturated fatty acids (PUFA) with glycerol. A PUFA concentrate obtained from cod liver oil was used to optimize the reaction to favor triglyceride synthesis with lipases. The type and amount of lipase and organic solvent, glycerol content, temperature, water content, and amount and time of addition of molecular sieves were studied. The optimal reaction mixture and conditions were: 9 mL hexane, 60°C, 0.5% (vol/vol) water, 1 g molecular sieves added after 24 h of reaction, glycerol/fatty acid molar ratio 1:3 and 100 mg of Novozym 435 (Novo Nordisk A/S) lipase. Under these conditions, an enriched triglyceride yiedl of 84.7% containing 27.4% eicosapentaenoic acid and 45.1% docosahexaenoic acid was obtained from a cod liver oil PUFA concentrate.  相似文献   
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