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51.
Sandra A. Mayén-Hernández Gerardo Torres-Delgado Rebeca Castanedo-Pérez Mario Gutiérrez Villarreal Alfredo Cruz-Orea Julio G. Mendoza Alvarez Orlando Zelaya-Angel 《Journal of Materials Science: Materials in Electronics》2007,18(11):1127-1130
ZnO + Zn2TiO4 thin films were obtained by the sol–gel method using precursor solutions with different Ti/Zn ratios in the 0.18–2.13 range.
The films were deposited on glass substrates and annealed in an open atmosphere at 550 °C. The oxide was characterized by
X-ray diffraction and photoacoustic (PA) spectroscopy. The films were constituted of polycrystalline ZnO for the lowest Ti/Zn
ratio (0.18), polycrystalline Zn2TiO4 for the 0.70 and 1.0 ratios, and mixes of both oxides for the intermediate ratios (0.32 and 0.50). For the highest ratios
studied (1.44 and 2.13), the films were amorphous. The energy band gap (Eg) values were determined from optical absorption spectra, measured by means of the PA technique spectra. Eg varied in the 3.15 eV (ZnO) to 3.70 eV (Zn2TiO4) range. 相似文献
52.
Gerardo Treviño-Garza Krystel K. Castillo-Villar 《International journal of systems science》2013,44(9):1705-1716
In this paper we present two solution procedures to obtain the solution for a family of economic production quantity inventory models for an integrated vendor–buyer system considering that production system generates defective products, in which the number of shipments must be a discrete value and that the lot size can take continuous (case 1) or integer (case 2) values. These solution procedures provide a more realistic approach for solving a family of inventory models. Previous works only derive the optimal lot size considering the number of shipments as a given value or derive both the lot size and the number of shipments considering both decision variables as continuous. The number of shipments takes integer values in real life and thus it must be considered as a discrete variable. This paper revisits and solves previous inventory models considering the variables (lot size and number of shipments) according to their real-life nature. 相似文献
53.
Gerardo Navarro-García Juan C. Ramírez-Suárez Elizabeth Cota-Quiñones Fernando Márquez-Farías Lorena Bringas-Alvarado 《Food chemistry》2010
The effect of storage time on the quality of liver oil from two commercial rajiform species (Rhinoptera bonasus and Aetobatus narinari) captured in the Gulf of Mexico (State of Campeche coast line) was evaluated. Oil characterisation was conducted by physical (specific gravity, saponification index and water content) and chemical analyses (fatty acid content, carotenes and tocopherols) whilst storage stability (peroxide value, free fatty acids, conjugated dienes, anisidine value and changes in docosahexaenoic acid, DHA and content) was studied for 87 days at 25 °C. Increases (p < 0.05) in free fatty acids, conjugated dienes, peroxide value and anisidine value, and a decrease (p < 0.05) in DHA were observed during the storage time for both oil species as oxidation proceeded. It was concluded that R. bonasus and A. narinari oils lasted for 52 and 66 days under these storage conditions, respectively. 相似文献
54.
Jean‐Michel Savoie Dulce Salmones Gerardo Mata 《Journal of the science of food and agriculture》2007,87(7):1337-1344
Hydrogen peroxide is suspected of being highly implicated in mushroom nutrition and in substrate bleaching during cultivation. The parameters for measuring H2O2 in compost samples were examined and the methodology was applied to samples from both compost colonized by cultivars and wild isolates of Agaricus bisporus, and wheat straw or coffee pulp colonized by Pleurotus spp. Laccase and peroxidase activities were also measured. H2O2 concentration measured after heating at 80 °C for inactivating laccases and peroxidases was probably both H2O2 pre‐existing in the compost and H2O2 generated from quinones and active oxygen species. This potential H2O2 concentration increased during the vegetative growth for all the strains, in agreement with a direct relationship between H2O2 concentration and active biomass of A. bisporus or Pleurotus spp. in their cultivation substrates. Correlations were observed between H2O2 concentration and manganese peroxidase activity in cultivation substrates at the stage of primordia formation. At this stage of development, H2O2 generation via biotic or abiotic mechanisms should be an important physiological trait of mushrooms. Copyright © 2007 Society of Chemical Industry 相似文献
55.
Gerardo Aragon-Camarasa Haitham Fattah J. Paul Siebert 《Robotics and Autonomous Systems》2010,58(3):276-286
This paper presents the results of an investigation and pilot study into an active binocular vision system that combines binocular vergence, object recognition and attention control in a unified framework. The prototype developed is capable of identifying, targeting, verging on and recognising objects in a cluttered scene without the need for calibration or other knowledge of the camera geometry. This is achieved by implementing all image analysis in a symbolic space without creating explicit pixel-space maps. The system structure is based on the ‘searchlight metaphor’ of biological systems. We present results of an investigation that yield a maximum vergence error of ~6.5 pixels, while ~85% of known objects were recognised in five different cluttered scenes. Finally a ‘stepping-stone’ visual search strategy was demonstrated, taking a total of 40 saccades to find two known objects in the workspace, neither of which appeared simultaneously within the field of view resulting from any individual saccade. 相似文献
56.
57.
Gerardo C Saucedo Pedro B Gonzlez Sergio M Revah Gustavo G Viniegra Maurice Raimbault 《Journal of the science of food and agriculture》1990,50(4):467-477
The major effect of Lactobacillus inoculation on laboratory cassava (Manihot esculenta Crantz) silage was a change from a heterofermentative pattern observed in natural silage to a homofermentation. Small amounts of starter culture (1% v/w) were required to produce a high level of lactic acid (> 28 g kg?1 DM) and to reach a pH of at least 4. The Gompertz model was used to evaluate the effect of inoculation level on the lactic formation based on kinetic criteria. Also an empirical pH lactic acid correlation was proposed to monitor the progress of ensiling, based solely on pH measurements. The simulation model may be used to improve guidelines for silo safety and to evaluate the effect of lactobacilli inoculants. 相似文献
58.
59.
Mu?oz Ricardo F.; McQuaid John R.; González Gerardo M.; Dimas Juanita; Rosales Verónica A. 《Canadian Metallurgical Quarterly》1999,67(4):502
Clinical depression is frequently unrecognized, even in health care settings. This study (a) reports high levels of major depressive episodes (MDEs) and depressive symptoms in a public sector women's clinic, (b) compares computerized voice recognition with live interviews, and (c) compares Spanish and English versions of the depression-screening instruments. Patients (N?=?104) completed face-to-face interviews and/or computerized voice recognition interviews in counterbalanced order; 38% scored positive for current MDE, and 67% scored positive for lifetime MDE. The mean score on the Center for Epidemiological Studies Depression scale (CES-D) was 22.1 (SD?=?12.1), with 68% scoring 16 or above. No differences were found on either measure between English and Spanish speakers. Overall agreement between computer and live interviews was as follows: κ?=?.82 for both current and lifetime MDE and r?=?.89 for CES-D scores. Kappas between the MDE Screener developed for this study and the Primary Care Evaluation of Mental Disorders were .75 for live interviews and .81 for the computerized version. Depression screening with computerized voice recognition methods yielded results comparable with those of live interviews in both English and Spanish. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
60.
Gerardo Iñiguez Rafael A. Barrio János Kertész Kimmo K. Kaski 《Computer Physics Communications》2011,182(9):1866-1869
In a previous paper we proposed a model to study the dynamics of opinion formation in human societies by a co-evolution process involving two distinct time scales of fast transaction and slower network evolution dynamics. In the transaction dynamics we take into account short range interactions as discussions between individuals and long range interactions to describe the attitude to the overall mood of society. The latter is handled by a uniformly distributed parameter α, assigned randomly to each individual, as quenched personal bias. The network evolution dynamics is realised by rewiring the societal network due to state variable changes as a result of transaction dynamics. The main consequence of this complex dynamics is that communities emerge in the social network for a range of values in the ratio between time scales. In this paper we focus our attention on the attitude parameter α and its influence on the conformation of opinion and the size of the resulting communities. We present numerical studies and extract interesting features of the model that can be interpreted in terms of social behaviour. 相似文献