排序方式: 共有31条查询结果,搜索用时 15 毫秒
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JC Hernández Guerrero J Portilla Robertson C Ledezma Montes S Ponce-Bravo A Miranda Gómez EM Arias Rivera 《Canadian Metallurgical Quarterly》1996,44(1-4):25-30
Several forms of cell perturbation have been associated with ethanol ingestion. Fetal alcohol syndrome (FAS) as well as diminished maxillofacial development and inhibition of cell regeneration in vitro and in vivo have been described. Epidermal growth factor (EGF) stimulates maxillofacial growth, DNA synthesis, and it is a potent mitogen for a number of various cell types. EGF exerts its effects on cells through binding to a specific cell surface receptor which leads to activation of a thyrosine kinase in the intracellular part of the receptor. The inhibitory effect of alcohol on EGF in the mouse dental follicle was studied in the offspring of alcoholic mothers using immunocytochemistry. Adult female mice were given 22% alcohol in their drinking water and fed a pelleted diet before and during pregnancy. Maternal blood alcohol levels were 262 +/- 1.3 mg/100 ml on gestation day 12.5. The offspring of the alcoholic and control mice were sacrificed on postnatal day 1.5, their mandibles were dissected, weighed and processed by routine immunocytochemistry with the following results. 1) Significant differences were found in mandible weight p < 0.01 after parturition. 2) The tooth germs in the offspring of ethanol treated mice were morphometrically smaller than those of control littermates. 3) Immunoexpression of EGF in the mandibular first molar of the control group was strong and homogeneous while in the experimental group the expression was light and heterogeneous. It is concluded that maternal alcoholism reduces EGF in the offspring. 相似文献
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A Parametric Texture Model Based on Joint Statistics of Complex Wavelet Coefficients 总被引:27,自引:0,他引:27
We present a universal statistical model for texture images in the context of an overcomplete complex wavelet transform. The model is parameterized by a set of statistics computed on pairs of coefficients corresponding to basis functions at adjacent spatial locations, orientations, and scales. We develop an efficient algorithm for synthesizing random images subject to these constraints, by iteratively projecting onto the set of images satisfying each constraint, and we use this to test the perceptual validity of the model. In particular, we demonstrate the necessity of subgroups of the parameter set by showing examples of texture synthesis that fail when those parameters are removed from the set. We also demonstrate the power of our model by successfully synthesizing examples drawn from a diverse collection of artificial and natural textures. 相似文献
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J Ena V Valls J López Aldeguer MP García Gascó S A?ón V Navarro R Sánchez V Boix J Portilla P Roig MM Masiá A Maestre Peiró 《Canadian Metallurgical Quarterly》1998,37(3):213-216
A case of metachronous malignancy in an elderly postmenopausal lady is presented. She had previously been successfully treated for squamous cell carcinoma of the cervix and now four years later, presented with a right lower lobe lung abscess. On evaluation she was found to have a small cell carcinoma of the lung involving the right intermediate and right lower lobe bronchus. She improved clinically and radiologically with parenteral antibiotics, combination chemotherapy and local external radiotherapy. 相似文献
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Thermal evolution in air and argon of nanocrystalline MoS2 synthesized under hydrothermal conditions
X. Bokhimi J. A. Toledo J. Navarrete X. C. Sun M. Portilla 《International Journal of Hydrogen Energy》2001,26(12):1271-1277
Nanocrystalline molybdenum sulfide was synthesized between 150°C and 225°C under hydrothermal conditions starting from ammonium heptamolybdate and thiourea. Samples were characterized with X-ray powder diffraction, electron microscopy, nitrogen adsorption, thermoanalysis and infrared spectroscopy. The hydroxyls involved in the synthesis and adsorbed on crystals surface hindered crystallization and samples still recrystallized after the final dehydroxylation step above 300°C, just when hydroxyls were isolated from each other. This also promoted sulfur bond breaking that gave rise to partial transformation of the MoS2 into MoO2 when the annealing atmosphere was argon, and to the total transformation of the sulfide into MoO3 when it was air. The initial MoS2 crystals were bend; many of them were isolated, and others associated in bundles that formed worm-like grains interacting with each other to produce spherical grains aggregated in clusters. This morphology gave rise to samples with a low specific surface area. 相似文献
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Collantes J.M. Bouysse P. Portilla J. Quere R. 《Microwave and Wireless Components Letters, IEEE》2001,11(7):296-298
A nonlinear charge model for RF power FETs is presented. The model, intended for use in harmonic-balance simulators, calculates the time evolution of the nonlinear charge in a period of the steady-state regime. For that, the experimentally extracted capacitances are integrated using the device dynamic load cycle as integration path. The proposed approach is technology independent and it has been applied here to a Si LDMOSFET and a SiC MESFET. Load pull measurements have been performed to verify the validity of the model 相似文献
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In the literature, different techniques have been presented for the phase-noise analysis of free-running oscillator circuits. In order to give some insight into the relationships existing between them, an analytical comparison is carried out in this paper between three different approaches. Two of them are time-domain approaches, based on Floquet's theory and the impulse sensitivity function, respectively, and the third one is the carrier modulation approach, in frequency domain. The application of Floquet's theory enables the calculation of periodic sensitivity functions to the noise perturbations. Here, the possibility to determine these functions through harmonic balance is demonstrated. This allows applying the whole stochastic characterization of phase noise, obtained from time-domain analysis, to circuits simulated through harmonic balance. For illustration, calculations in a cubic-nonlinearity oscillator are presented. 相似文献
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Revalorisation of vine trimming wastes using Lactobacillus acidophilus and Debaryomyces hansenii 总被引:1,自引:0,他引:1
Oscar M Portilla Beatriz Rivas Ana Torrado Ana B Moldes José M Domínguez 《Journal of the science of food and agriculture》2008,88(13):2298-2308
BACKGROUND: Mild acid treatments of vine‐shoot trimmings result in the hydrolysis of hemicellulosic sugars that can be utilised by Lactobacillus acidophilus CECT‐4179 (ATCC 832) and Debaryomyces hansenii NRRL Y‐7426 as carbon sources to obtain food additives. Since the high content of glucose in these hydrolysates reduces the effective bioconversion of xylose into xylitol by D. hansenii, the use of Lactobacillus acidophilus, one of the main probiotic species, allows this problem to be solved by the selective consumption of glucose. In order to use both sugars (glucose and xylose), hemicellulosic vine‐shoot trimming hydrolysates can be sequentially fermented by both micro‐organisms. RESULTS: It was found that, in the first step, L. acidophilus generated almost exclusively lactic acid (32.7 g of lactic acid L?1, QLA = 1.363 g L?1 h?1, YLA/S = 0.72 g g?1) by homofermentative degradation of sugars (mainly glucose), and in the second step, the remaining hemicellulosic sugars were transformed primarily into xylitol by Debaryomyces hansenii (31.3 g of xylitol L?1, QXylitol = 0.708 g L?1 h?1, YXylitol/S = 0.66 g g?1). Furthermore, L. acidophilus proved to be a strong cell‐bounded biosurfactant producer. Cell extracts were able to reduce the surface tension (ST) of PBS in 18 mN m?1 units. Lactobacillus acidophilus cells showed no difference in viability before or after PBS extraction of biosurfactants, achieving values of 0.9 × 109 colony‐forming units (CFU) mL?1 in both cases. CONCLUSIONS: These results have made a serious contribution to the re‐evaluation of a useless and pollutant residue, producing a wide range of natural food additives. Copyright © 2008 Society of Chemical Industry 相似文献
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Marco Sarcletti Dustin Vivod Tobias Luchs Tobias Rejek Luis Portilla Lukas Müller Hanno Dietrich Andreas Hirsch Dirk Zahn Marcus Halik 《Advanced functional materials》2019,29(15)
Various hydrocarbons are efficiently extracted from water by using a new sorbent material based on covalently functionalized magnetic nanoparticles. The functionalization of the magnetite nanoparticles with a self‐assembled monolayer of hexadecylphosphonic acid renders the nanoparticles oleophilic and the magnetic nature of magnetite allows for simple extraction of the hydrocarbon‐soaked sorbent. The sorbent material is capable of extracting single contaminants such as alkanes and aromatics and complex hydrocarbon mixtures such as crude oils in high extraction rates of up to 14 times the sorbent volume. Experimental results are explained by molecular dynamics simulations on the adsorption of single components from a hydrocarbon‐water mixture to the alkylphosphonic acid layer on the nanoparticles. The core–shell sorbent material is highly stable and therefore, reusable over several successive extraction cycles without degradation. The extraction performance is determined at different water temperatures, different water sources, and different magnetic core materials and evaluated compared to heptadecanoic acid functionalized magnetite. The new sorbent material provides the opportunity for an efficient, reliable, inexpensive, and environmental friendly removal of hydrocarbons from water. 相似文献