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61.
Marek Gnatowski Rebecca Ibach Mathew Leung Grace Sun 《Wood material science & engineering》2015,10(1):94-111
AbstractTwo wood plastic composite (WPC) boards, one experimental and one commercial, were exposed to exterior conditions and evaluated non-destructively using a clinical magnetic resonance imaging (MRI) unit for moisture content (MC) and distribution. The experimental board was exposed in Vancouver, British Columbia, for more than 8 years, and the commercial board was exposed near Hilo, Hawaii, for 2 years. Both boards were characterized in terms of wood content, density, water uptake properties and voids content. The experimental board was additionally destructively analysed for water absorption of the WPC and MC calculated based on the wood content for verification of MRI results. MRI detected the presence of free water and its distribution in both of the WPC boards. Fibre saturation in the experimental board was found to be about 22–24%, in comparison to 25–30% present in most wood species. There was good correlation between the detection of free water by MRI and by destructive testing. Magnetic resonance images showed various major points of water entry in the WPC boards such as the support area, the cut ends, the dripping edge and the sides of the boards. For the experimental board, significant water entry also occurred at the upper exposed surface. 相似文献
62.
All fuel usage produces air pollutants, causing local and trans-boundary air pollution and acid rain problems. Biodiesel is a clean renewable fuel with properties similar to diesel but produced from renewable resources such as vegetable oils and animal fats. Although this fuel has been developed some two to three decades ago, it is not commonly used, mainly due to the higher production cost involved. Due to the increasing concern on environmental protection, a lot of researches on the usage of this fuel are conducted in recent years. To study the characteristics of this fuel, a special biodiesel fuel is produced using waste cooking oil and animal fat from restaurants as feedstock. Reusing of these wastes has both the benefit of producing a cleaner fuel and waste cycling. Tests of the fuel with different proportions of diesel have been conducted on various diesel engines and the results obtained are encouraging. The environmental benefits and suitability of this fuel to Hong Kong to reduce air pollution problems are discussed based on the assessment results. 相似文献
63.
Liu JH Lee CS Leung KM Yan ZK Shen BH Zhao ZZ Jiang ZH 《Journal of agricultural and food chemistry》2007,55(22):8830-8835
A sensitive method for quantitating the pharmacologically active polyacetylenes panaxynol and panaxydol in Radix Ginseng was developed using a capillary gas chromatography-mass spectrometric (GC-MS) method. The detection mode of selected ion monitoring (SIM) allowed sensitive and selective quantitation of the two compounds in ginseng. Method validation showed that the GC-MS method has much lower detection and quantitation limits than the high-performance liquid chromatography (HPLC)-UV method. This indicates that GC-MS is particularly useful for the analysis of polyacetylene compounds, which have relatively low abundances compared with ginsenosides in ginseng. Based on the quantitative results of different types of ginseng herbs, it was found that the panaxydol and panaxynol contents were higher in forest ginseng than in cultivated ginseng. This method was further applied to the quantitative analyses of panaxynol and panaxydol in Radix Notoginseng and American ginseng. The ratio of panaxydol to panaxynol can be utilized as a marker for differentiating ginseng, notoginseng, and American ginseng. This study introduces the first GC-MS method for the quantitative analysis of polyacetylenes in herbs of the Panax genus. 相似文献
64.
Polymorphisms of 5' flanking region of chicken prolactin gene 总被引:9,自引:0,他引:9
65.
Mathew C. Lovett William R. Fenner Adam T. Watson Roger A. Hostutler 《Veterinary radiology & ultrasound》2012,53(6):650-654
A 2‐year‐old male American Bulldog experienced paroxysmal staggering, altered consciousness, and hyperesthesia. Magnetic resonance (MR) imaging enabled recognition of a fourth ventricular mass causing compression of the cerebellum and brainstem and obstructive hydrocephalus. The mass was uniformly T2‐hyperintense and predominantly T1‐hypointense. A fluid line was evident on the fluid‐attenuated inversion recovery images. A thin rim of contrast enhancement was noted. Histopathologic diagnosis was a cholesterol granuloma. We were unable to identify any other reports of a cholesterol granuloma residing in the fourth ventricle of a dog. This case report documents the clinical, diagnostic imaging, and histopathologic findings of a canine intracranial cholesterol granuloma. © 2012 Veterinary Radiology & Ultrasound. 相似文献
66.
Bruce A. Rosa Mi-Sung Yim Lee Burdenuk Bruce H. Kjartanson Kam Tin Leung 《Water, air, and soil pollution》2010,210(1-4):243-254
Little is known about the transport of microorganisms through freeze-fractured clay soils. Normally consolidated clay (NCC) and compacted clay (CC) columns (representing a natural clay barrier and a compacted barrier, respectively) were exposed to six consecutive freeze–thaw cycles and permeated for 21 days with an Escherichia coli cell suspension (approximately 1?×?107 colony forming units (CFU)/mL) containing a 2.1-mM bromide tracer. An unfractured sand column was also examined for comparison with the clay columns. While no E. coli was detected in the effluent of both untreated NCC and CC control clay columns, a relatively low density of E. coli (between 228 and 270 CFU/mL compared to 1?×?107 CFU/mL in the influent) was first detected in the effluent of the freeze-fractured NCC and CC columns at 0.29 and 0.31 pore volumes (or at 5.4 and 4.1 h), respectively. It took 11 min for a full breakthrough of E. coli through the sand column, but only about 0.1% of the influent E. coli density was detected in the effluents of the freeze-fractured NCC and CC columns at day 21. These observations show that despite the high bacterial retention capacity of the freeze-fractured clay columns, the fractures were large enough for the E. coli to flow through. Based on batch sorption tests and the permeation data, it is estimated that 18%, 7%, and 84% of the freeze-fractured NCC, CC, and sand columns would be exposed to the influent, respectively, under a full E. coli breakthrough condition. Our data show that the high bacterial retention capacity of clay barriers can be compromised by freeze–thaw conditions. 相似文献
67.
As the global population continues to grow, food needs will increase as well. The amount of land and other resources devoted to agriculture production is not expected to grow significantly, leading most to agree that the substantial increases in food production to meet food security needs will come through the development of technologies that improve production efficiency. Diseases are constant threats to efficiency in all segments of agriculture. In livestock production, many of the bacterial pathogens that infect food animals are controlled through the use of antimicrobials. Antimicrobials are currently used in the United States not only to treat specific diseases, but also as feed additives to prevent bacterial disease in general or to improve growth performance. In recent years, there have been several proposals in the United States, both at state and federal levels, aimed at curtailing or dramatically reducing the use antimicrobials as feed additives, creating a policy similar to that of the European Union. Here we review the current policies on antimicrobial use in the European Union and their impact on food animal production. In addition, we discuss the future of antimicrobial use in food animal production in the United States and the increasing role of biosecurity programs. Finally, we discuss the role of Cooperative Extension Service in creating improved biosecurity programs and extension programs that provide policy makers and voters information on modern food animal production practices and technologies so that policies and regulations are effective and appropriate. 相似文献
68.
Mathew SR McCaughey WP Kennedy AD Lewis NJ Crow GH 《The Canadian veterinary journal. La revue veterinaire canadienne》1999,40(11):796-798
An automated heatmount detection system was employed to detect estrus for artificial insemination in 57 beef cows. First service conception rate was 84.2% and the pregnancy rate was 89.5% for a 42-day breeding season. Duration of estrus was 9.6 h, sx = 0.5 h and mounting activity was lowest during the dark part of the day. 相似文献
69.
American canine hepatozoonosis is caused by Hepatozoon americanum, a protozoan parasite, the definitive host of which is the tick, Amblyomma maculatum. Infection of the dog follows ingestion of ticks that harbor sporulated H. americanum oocysts. Following penetration of the intestinal mucosa, sporozoites are disseminated systemically and give rise to extensive asexual multiplication in cells located predominantly in striated muscle. The parasitized canine cells in "onion skin" cysts and in granulomas situated within skeletal muscle, as well as those in peripheral blood leukocytes (PBL), were identified as macrophages by use of fine structure morphology and/or immunohistochemical reactivity with macrophage markers. Additionally, two basic morphologic forms of the parasite were observed in macrophages of granulomas and PBLs. The forms were presumptively identified as merozoites and gamonts. The presence of a "tail" in some gamonts in PBLs indicated differentiation toward microgametes. Recognition of merozoites in PBLs supports the contention that hematogenously redistributed merozoites initiate repeated asexual cycles and could explain persistence of infection for long periods in the vertebrate host. Failure to clearly demonstrate a host cell membrane defining a parasitophorous vacuole may indicate that the parasite actively penetrates the host cell membrane rather than being engulfed by the host cell, as is characteristic of some protozoans. 相似文献
70.
Nadeau JA Andrews FM Patton CS Argenzio RA Mathew AG Saxton AM 《American journal of veterinary research》2003,64(4):413-417
OBJECTIVE: To identify in vitro effects of hydrochloric acid, valeric acid, and other volatile fatty acids (VFAs) on the pathogenesis of ulcers in the nonglandular portion of the equine stomach. SAMPLE POPULATION: Gastric tissues from 13 adult horses. PROCEDURE: Nonglandular gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference were measured and electrical resistance and conductance calculated after tissues were bathed in normal Ringer's solution (NRS) or NRS and hydrochloric, valeric, acetic, propionic, and butyric acids. Treated tissues were examined histologically. RESULTS: Incubation in 60mM valeric acid at pH < or = 7.0 abruptly and irreversibly abolished Isc, which was followed by a slower decrease in resistance and an increase in conductance. Incubation in 60mM acetic, propionic, and butyric acids and, to a lesser extent, hydrochloric acid at pH < or = 7.0 significantly decreased Isc, which was followed by an increase in resistance and a decrease in conductance. CONCLUSIONS AND CLINICAL RELEVANCE: Incubation in valeric acid at pH < or = 7.0 caused a dramatic decrease in mucosal barrier function in the nonglandular portion of the stomach. Changes in barrier function attributable to exposure to valeric acid were associated with histopathologic evidence of cellular swelling in all layers of the nonglandular mucosa. Because of its high lipid solubility, valeric acid penetrates the nonglandular gastric mucosa, resulting in inhibition of sodium transport and cellular swelling. Valeric acid and other VFAs in gastric contents may contribute to the pathogenesis of ulcers in the nonglandular portion of the stomach of horses. 相似文献