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1.
Quantitative UPLC‐MS/MS analysis of chlorogenic acid derivatives in antioxidant fractionates from dandelion (Taraxacum officinale) root 下载免费PDF全文
Owen Kenny Thomas J. Smyth Chandralal M. Hewage Nigel P. Brunton 《International Journal of Food Science & Technology》2015,50(3):766-773
While qualitative studies have identified chlorogenic acids in antioxidant extracts, particularly ethyl acetate‐derived extracts, of Taraxacum officinale, quantitative analysis of these phenolic compounds remains largely unreported for this species. In this study, bioactivity‐guided fractionation of an antioxidant crude ethyl acetate extract (DPPH = 295.481 ± 0.955 mg TE g?1 extract) from T. officinale root resulted in a number of reverse‐phase fractions that demonstrated high antioxidant activity (DPPH = 1058.733–1312.136 mg TE g?1 extract), stronger than that of the synthetic antioxidant Trolox®. UPLC‐MS/MS screening of these fractions for the presence of selected mono‐ and di‐caffeoylquinic acids revealed large quantities of 1,5‐dicaffeoylquinic acid present in several fractions (853.052–907.324 μg mg?1), respectively. Due to the antioxidant potency and high levels of 1,5‐dicaffeoylquinic acid observed in these fractions, it was concluded that specifically this chlorogenic acid derivative is a major contributor to the antioxidant efficacy of dandelion root. 相似文献
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The bubble eater is a device which can sense, capture, and recycle bubble gas in a bubbling fluidized bed. The theory describing the enhancement of reactant gas conversion are presented and illustrated by means of a numerical example. 相似文献
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Based on successful results in animal models, it has been proposed that high-dose myeloablative therapy followed by autologous bone marrow or stem cell transplantation (ABMT/ASCT) may cure autoimmune disease. The coexistence of autoimmune disease and hematologic malignancy provides an opportunity to examine the response of autoimmune disease to ABMT or ASCT. We describe 4 patients with autoimmune disease (3 with psoriasis and 1 with rheumatoid arthritis) and hematologic malignancy. In each patient, the autoimmune disease remitted posttransplantation, but, in 4 patients with long-term followup, it recurred at 8-24 months. The earliest relapse occurred in a patient treated with interferon-alpha. Our experience suggests that a single autograft with unpurged stem cells is unlikely to cure autoimmune disease, but that other strategies building on this approach are worthy of investigation. 相似文献
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Methods are presented for modeling the failure and repair of transmission equipment and their impact on subtransmission system reliability. The methods account for arbitrary load variation and nonexponential downtime distribution for components. The effects of single independent outages common-mode outages and independent overlapping outages are studied. The results are used to identify conditions when nonexponentially distributed downtimes can lead to significant errors if the method of analysis does not take this factor into account 相似文献
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In this paper, the microstructure of a 1 wt.% Cu/γ-Al2O3 catalyst that was reduced in a 4% hydrogen/argon atmosphere at temperatures of 523, 773 and 1073 K, is studied by Z-contrast imaging and electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM). Results show that the copper species are well dispersed when the catalyst is reduced below 523 K. At 773 K, separated Cu(I) and Cu(0) species are found existing as ring-like and bulk-like particles. This appears to indicate that the copper has not been reduced to its metallic form due to the interaction between the copper oxide and the support. Large spherical particles having core-shell structures with Cu(I) in the shells and Cu(0) in the cores are generated when the catalyst is reduced at 1073 K. The formation of partially oxidized copper species upon reduction at 1073 K is attributed to the metallic copper interaction with the alumina support. This study also demonstrates that high-spatial resolution Z-contrast imaging and EELS performed simultaneously can provide unique information on the morphology and chemistry of metal species in supported metal catalysts. 相似文献
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Foreman Nigel; Save Etienne; Thinus-Blanc Catherine; Buhot Marie-Christine 《Canadian Metallurgical Quarterly》1992,106(3):529
When hooded rats with bilateral lesions of Krieg's Area 7 (parietal cortex) were trained to locomote toward visual targets in a runway, they ran less accurately than did controls, although unilaterals ran accurately. When flashing lights were presented unexpectedly during their run, bilateral parietals were less disrupted than were controls, but they failed to show total neglect. Unilateral parietals turned toward distracters on either side but turned preferentially toward distracters contralateral to the intact hemisphere, particularly when distracters occurred bilaterally and simultaneously. Effects due to the omission of expected distracters were similar in parietals and controls. Rat parietal cortex is not essential for the redirection of attention to stimuli notable for their unexpected presence or absence, but parietal cortex may resolve interhemispheric competition. Results suggest a homology between parietal cortex in rat and primate. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Alpass Fiona; Flett Ross; Humphries Steve; Massey Claire; Morriss Stuart; Long Nigel 《Canadian Metallurgical Quarterly》2004,11(3):270
Previous studies have identified a number of different farm stressors and have reported gender and age differences in levels of stress. This study aimed to determine stress experienced by New Zealand dairy farmers, particularly in relation to adoption of new technology and its relationship to age and gender. Measures of farm stress and adoption of technology were completed by 985 dairy farmers. The highest levels of stress were reported for time pressures, machinery breakdown, weather, and government policies. Stress related to new technologies occurred rarely. Women reported more stress and higher levels of stress for understanding new technologies. There was also an increase in severity of stress with age related to new technologies. Overall, stress levels were moderate and may reflect favorable economic conditions. The findings suggest a need to tailor stress interventions to meet specific needs. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Adam Jacobson Fan Zeng David Smith Nigel Boswell Thierry Peynot Michael Milford 《野外机器人技术杂志》2021,38(1):5-27
Robustly and accurately localizing vehicles in underground mines is particularly challenging due to the unavailability of GPS, variable and often poor lighting conditions, visual aliasing in long tunnels, and airborne dust and water. In this paper, we present a novel, infrastructure‐less, multisensor localization method for robust autonomous operation within underground mines. The proposed method integrates with existing mine site commissioning and operation procedures and includes both an offline map‐building process and an online localization algorithm. The approach combines the strengths of visual‐based place recognition, LIDAR‐based localization, and odometry in a particle filter fusion process. We provide an extensive experimental validation using new large data sets acquired in two operational Australian underground hard‐rock mines (including a 600m‐deep multilevel mine with approximately 33 km of mapping data and 7 km of vehicle localization) by actual mining vehicles during production operations. We demonstrate a significant increase in localization accuracy over prior state‐of‐the‐art SLAM research systems and real‐time operation, with processing times in the order of 10 Hz. We present results showing a mean error of 0.68 m from the Queensland Mine data set and 1.32 m from the New South Wales Mine data set and at least 86% reduction in error compared with prior state of the art. We also analyze the impact of the particle filter parameters with respect to localization accuracy. Together this study represents a new approach to positioning systems for currently deployed autonomous vehicles within underground mine environments. 相似文献
10.
L. Guan I.U. Awan I. Phillips A. Grigg W. Dargie 《Simulation Modelling Practice and Theory》2009,17(3):558-568
The provision of guaranteed QoS for various Internet traffic types has become a challenging problem for researchers. New Internet applications, mostly multimedia-based, require differentiated treatments under certain QoS constraints. Due to a rapid increase in these new services, Internet routers are facing serious traffic congestion problems. This paper presents an approximate analytical performance model in a discrete-time queue, based on closed form expressions using queue threshold, to control the congestion caused by the bursty Internet traffic. The methodology of maximum entropy (ME) has been used to characterize closed form expressions for the state and blocking probabilities. A discrete-time GGeo/GGeo/1/{N1, N2} censored queue with finite capacity, N2, external compound Bernoulli traffic process and generalised geometric transmission times under a first come first serve (FCFS) rule and arrival first (AF) buffer management policy has been used for the solution process. To satisfy the low delay along with high throughput, a threshold, N1, has been incorporated to slow the arrival process from mean arrival rate λ1 to λ2 once the instantaneous queue length has been reached, otherwise the source operates normally. This creates an implicit feedback from the queue to the arrival process. The system can be potentially used as a model for congestion control based on the Random Early Detection (RED) mechanism. Typical numerical experiments have been included to show the credibility of ME solution against simulation for various performance measures and to demonstrate the performance evaluation of the proposed analytical model. 相似文献