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Huang Z.,Northwest University, China | Zhu H.,Northwest A and iversity | Wang S.,Northwest University, China
Transactions of the ASABE | Year: 2015

Radio frequency (RF) heating has been extensively studied as a novel disinfestation method for dry agricultural products. A major difficulty in using this method is that different heating rates at the corners and edges of materials may cause negative effects on product quality. A systematic analysis of factors that influence the RF heating rate is desirable to help in designing effective treatment protocols. A finite element model using COMSOL Multiphysics software was developed and experimentally validated with 3 kg of mung beans in a 6 kW, 27.12 MHz free-running oscillator RF system to study the influence of sample moisture content, density, specific heat capacity, thermal conductivity, dielectric properties, top electrode voltage, and electrode gap on RF heating rate. Simulation results demonstrated that the variation in sample density and specific heat capacity, especially thermal conductivity, had a relatively slight effect on RF heating rate. The RF heating rate was significantly influenced by electrode gap, top electrode voltage, and the dielectric properties and moisture content of the sample. These heating rate distributions might be valuable in guiding and optimizing RF treatment conditions, which are helpful to improve RF heating uniformity for disinfecting dry products. ©2015 American Society of Agricultural and Biological Engineers.. Source


Zhao J.,Northwest University, China | Wang L.,Northwest University, China | Wang Z.,Northwest University, China | Chen X.,Washington State University | And 6 more authors.
Phytopathology | Year: 2013

The wheat stripe rust pathogen (Puccinia striiformis f. sp. tritici) population in China has been reported to be a distinct genetic group with higher diversity than those in many other countries. Genetic recombination in the P. striiformis f. sp. tritici population has been identified with molecular markers but whether sexual reproduction occurs in China is unknown. In this study, we surveyed barberry plants for infection by rust fungi in the stripe rust "hotspot regions in Gansu, Sichuan, and Shaanxi provinces; collected barberry plants and inoculated plants of 20 Berberis spp. with germinated teliospores under controlled greenhouse conditions for susceptibility to P. striiformis f. sp. tritici; and tested P. striiformis f. sp. tritici isolates obtained from aecia on naturally infected barberry plants on the wheat genotypes used to differentiate Chinese P. striiformis f. sp. tritici races to determine virulence variations. Different Berberis spp. were widely distributed and most surveyed plants had pycnia and aecia of rust fungi throughout the surveyed regions. In total, 28 Berberis spp. were identified during our study. From 20 Berberis spp. tested with teliospores of P. striiformis f. sp. tritici from wheat plants, 18 species were susceptible under greenhouse conditions. Among 3,703 aecia sampled from barberry plants of three species (Berberis shensiana, B. brachypoda, and B. soulieana) under natural infections in Gansu and Shaanxi provinces, four produced P. striiformis f. sp. tritici uredinia on susceptible wheat Mingxian 169'. Sequence of the internal transcribed spacer (ITS) regions of the four isolates from barberry shared 99% identity with the P. striiformis f. sp. tritici sequences in the National Center for Biotechnology Information database. The four isolates had virulence patterns different from all previously reported races collected from wheat plants. Furthermore, 82 single-uredinium isolates obtained from the four barberry isolates had high virulence diversity rates of 9.0 to 28.1%, indicating that the diverse isolates were produced through sexual reproduction on barberry plants under natural conditions. In addition to P. striiformis f. sp. tritici, sequence analysis of polymerase chain reaction products of the ITS regions and inoculation tests on wheat identified P. graminis (the stem rust pathogen). Our results indicated that P. striiformis f. sp. tritici can infect some Berberis spp. under natural conditions, and the sexual cycle of the fungus may contribute to the diversity of P. striiformis f. sp. tritici in China. © 2013 The American Phytopathological Society. Source


Lu X.,Kyoto University | Lu X.,Northwest A and iversity | Saka S.,Kyoto University
Biomass and Bioenergy | Year: 2010

Hydrolysis of lignocellulosic biomass by hot-compressed water is creating an opportunity to obtain saccharides from both hemicelluloses and cellulose for biofuel production as well as saccharides production. In this work, the hydrolysis of Japanese beech (Fagus crenata) by batch and semi-flow hot-compressed water was investigated. After the treatments, the monosaccharides, oligosaccharides and decomposition products in water-soluble portion were determined, while the structural variation as well as chemical composition of residue was analyzed. The results demonstrated that the production of total saccharides increased with the temperature for both batch and semi-flow hot-compressed water treatments. The maximum yield of total saccharides was achieved at 250 °C when treated by semi-flow hot-compressed water, which was higher than the corresponding maximum production of saccharides obtained at 190 °C when treated by batch hot-compressed water. The xylooligosaccharides which came from hemicelluloses were produced until the temperature was higher than 230 °C when treated by batch hot-compressed water, while they were produced until 270 °C when treated by semi-flow hot-compressed water. On the other hand, the cellooligosaccharides which came from cellulose began to produce from 170 °C when treated by batch hot-compressed water, while they were not produced below 210 °C when treated by semi-flow hot-compressed water. In conclusion, both batch and semi-flow hot-compressed water can be used to hydrolyze hemicelluloses though at different optimal temperature, while semi-flow hot-compressed water was better than batch hot-compressed water for hydrolysis of cellulose. © 2010 Elsevier Ltd. Source


Zhao Q.,Shandong Agricultural University | Zhou E.M.,Shandong Agricultural University | Zhou E.M.,Northwest A and iversity | Dong S.W.,Shandong Agricultural University | And 6 more authors.
Emerging Infectious Diseases | Year: 2010

Avian hepatitis E virus (HEV) has been identified in chickens; however, only 4 complete or near-complete genomic sequences have been reported. We found that the near-complete genomic sequence of avian HEV in chickens from China shared the highest identity (98.3%) with avian HEV from Europe and belonged to avian HEV genotype 3. Source


Lu H.,Northwest A and iversity | Huang Y.D.,Gansu Agricultural University | Zhao B.Y.,Northwest A and iversity | Hu J.J.,Gansu Agricultural University | And 2 more authors.
African Journal of Biotechnology | Year: 2010

A series of investigations were carried out including epidemiology, etiology and pathology on hemorrhagic pneumonia in Moschus sifanicus, which had prevailed in Xinglong Mountain National Nature Reserve District in Gansu province of China. The results indicated that the prevalence of this disease could be correlated with local humidity in Xinglong Mountain in Gansu province of China. The disease is caused by single infection of Pasteurella multocida or mix of P. multocida, Escherichia coli and Pseudomonas aeruginosa, and is a contagious disease. The pathological changes were mainly manifested in the vessel wall of bronchia and bronchiole appeared congested, bleeding, edemic with infiltration of inflammatory cells, mucosa of bronchiole degenerates, with the presence of necrosis and exfoliation, pulmonary alveolus generated suppuration, disaggregation and necrosis. It was concluded that the diseases are mainly caused by local bacteria and affected M. sifanicus finally die of hemorrhagic or purulent, necrotic pneumonia. © 2010 Academic Journals. Source

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