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Search Results: 1 - 10 of 6497 matches for " Chi-yuen "
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PITT investigation of apparent diffusion of lithium-ion through PLD-deposited HT-LiCoO2 films
脉冲激光沉积制备的HT-LiCoO2薄膜中Li离子表观扩散的研究

ZHANG Yao,Chi-Yuen CHUNG,
张耀
,钟志源,朱敏

金属学报 , 2007,
Abstract: 采用脉冲激光沉积(PLD)方法在镀Pt的Si衬底上制备了LiCoO2薄膜,运用XRD、Raman光谱、SEM和循环伏安等方法对其结构与电化学性能进行表征,在此基础上着重采用电位间歇滴定技术(PITT)对其Li离子表观扩散进行了分析.结果表明,600 ℃制备的LiCoO2薄膜为HT-LiCoO2相,呈柱状晶结构,平均晶粒尺寸在100 nm以下,结晶度高,并且具有明显的001]择优取向,但少量缺Li.伏安循环曲线表明,该LiCoO2薄膜具有良好的电化学可逆性,但只在3.9 V(vs Li/Li )附近出现一对氧化还原峰.PITT测试表明,PLD方法制备的HT-LiCoO2薄膜的Li离子扩散系数在10-8-10-9cm2/s,与其它方法(如射频磁控溅射)制备的HT-LiCoO2薄膜相比,扩散系数高1-2个数量级;并且PLD方法制备的HT-LiCoO2薄膜中Li离子扩散系数与相变有关,在两相共存区,由于相界钉扎的作用,Li离子扩散系数比其它区域小1-2个数量级.
韧脆性剪切带滑移叶片中超微磨粒结构的发现和分析
孙岩,葛和平,陆现彩,朱文斌,郭继春,刘德良,Chi-yuen,Wang
中国科学 地球科学 中国科学 地球科学 , 2003,
Abstract: ?在美国加州深钻岩心超微滑移叶片中发现优选排列的微粒密集带,后在陕北油气钻孔岩心中又发现同样现象.兹系与滚动、研磨和压扭作用有关,故将球形微粒称磨粒,并属纳米、微米级超微尺度.研究表明,细究其成因则同岩石韧脆性变形、滑移侧压力作用和动力甚低级变质活动有关.系统样品测试分析显示,花岗质岩石中的磨粒带由动力分异使Nb和Ta相关元素富集;泥岩中的含磨粒滑移叶片带具“涂抹效应”,是优良的油气封盖层,为研究快速粘滑运动和剪切范式提供了依据.
Total colorectal and terminal ileal duplication presenting as intussusception and intestinal obstruction
Yuen Chi Ho
World Journal of Gastroenterology , 2012, DOI: 10.3748/wjg.v18.i43.6338
Abstract: Colonic intussusception and gastrointestinal duplication are diseases that arise in young children. The clinical presentation of adult cases of intussusception and enteric duplication is non-specific and thus poses a diagnostic challenge. A computed tomography (CT) scan is recommended in adult cases as the most sensitive diagnostic tool and the pathognomonic finding of outer intussuscepiens and central intussusceptum is diagnostic. A septum of a duplicated colon in a non-intussuscepted segment has been rarely reported in the literature. With advancements in radiological imaging technology and the increased availability of CT scanners, the capacity for a correct pre-operative diagnosis has been significantly enhanced. Our current case report illustrates the importance of considering an uncommon etiology for enteric intussusception and duplication as a differential diagnosis of acute abdomen in an adult patient. Our analyses of this patient also highlight the successful use of CT scanning to make this diagnosis.
Geometric Bijections Between Spanning Trees and Break Divisors
Chi Ho Yuen
Mathematics , 2015,
Abstract: The Jacobian group ${\rm Jac}(G)$ of a finite graph $G$ is a group whose cardinality is the number of spanning trees of $G$. $G$ also has a tropical Jacobian which has the structure of a real torus; using the notion of break divisors, An et al. obtained a polyhedral decomposition of the tropical Jacobian where vertices and cells correspond to elements of ${\rm Jac}(G)$ and spanning trees of $G$, respectively. We give a combinatorial description of bijections coming from this geometric setting. This provides a new geometric method for constructing bijections in combinatorics. We introduce a special class of geometric bijections that we call edge ordering maps, which have good algorithmic properties. Finally, we study the connection between our geometric bijections and the class of bijections introduced by Bernardi; in particular we prove a conjecture of Baker that planar Bernardi bijections are "geometric". We also give sharpened versions of results by Baker and Wang on Bernardi torsors.
A Review on Current Osteoporosis Research: With Special Focus on Disuse Bone Loss
Roy Yuen-chi Lau,Xia Guo
Journal of Osteoporosis , 2011, DOI: 10.4061/2011/293808
Abstract: Osteoporosis is a multifactorial skeletal disorder characterized by decreased bone mass and deteriorated microarchitecture that lead to increased risk of fracture. The disuse osteoporosis refers to bone mass decrements under conditions of decreased mechanical loading, including decreased ground force reaction, muscular contraction, and microgravity-related bone loss in astronauts after space flights. Although there are many effective treatments available for primary osteoporosis, there is a lack of effective treatments for disuse osteoporosis. This is because that the aetiology, pathophysiology, and resultant pathology of disuse osteoporosis differ from those of primary osteoporosis. The objective of this paper is to examine the unique pathology and underlying pathophysiology of disuse osteoporosis.
The Effects of Ganoderma lucidum on Initial Events Related to the Bacillus Calmette-Guérin Efficacy and Toxicity on High-Risk Uroepithelial Cells: An in Vitro Preliminary Study  [PDF]
John Wai-Man Yuen, Mayur-Danny I. Gohel, Chi-Fai Ng
Chinese Medicine (CM) , 2013, DOI: 10.4236/cm.2013.42009
Abstract:

A novel prophylactic regimen is demanded for preventing bladder cancer recurrence, because of the high side-effect tolls of conventional adjuvant Bacillus Calmette-Guérin (BCG) immunotherapy, in addition to its only moderate efficacy. In vitro and animal studies have demonstrated the anti-cancer properties of a medicinal mushroom called Ganoderma lucidum (GL). In this study, a pre-malignant human uroepithelial cells (HUC-PC) model was utilized to compare the effectiveness between ethanol extract of GL (GLe) and BCG on interleukin-6 (IL-6) secretion and lactate dehydrogenase (LDH) cytotoxicity. Additionally, parameters relevant to the BCG efficacy and safety, including free soluble fibronectin (FN) and cell-surface glycosaminoglycans (GAGs) levels were tested, following the exposure of GLe to the cells. GLe at 100 μg/ml and BCG at 4.8 × 107 CFU were shown to induce equivalent levels of IL-6, suggesting the potential synergism, while the tested concentrations of GLe were non-cytotoxic. During the initial four hours of GLe exposure, the free FN concentrations in harvested media were significantly reduced that might facilitate the binding of BCG for uroepithelial internalization to enhance BCG efficacy. Furthermore, the cell membrane-bound GAGs levels of HUC-PC cells were significant increased in response to GLe to suggest cellular protection from BCG infection. In summary, current findings suggest the potential additive synergism of GLe with the BCG efficacy, as well as its protective effects, and thus reducing the BCG toxicity.

A Review on Current Osteoporosis Research: With Special Focus on Disuse Bone Loss
Roy Yuen-chi Lau,Xia Guo
Journal of Osteoporosis , 2011, DOI: 10.4061/2011/293808
Abstract: Osteoporosis is a multifactorial skeletal disorder characterized by decreased bone mass and deteriorated microarchitecture that lead to increased risk of fracture. The disuse osteoporosis refers to bone mass decrements under conditions of decreased mechanical loading, including decreased ground force reaction, muscular contraction, and microgravity-related bone loss in astronauts after space flights. Although there are many effective treatments available for primary osteoporosis, there is a lack of effective treatments for disuse osteoporosis. This is because that the aetiology, pathophysiology, and resultant pathology of disuse osteoporosis differ from those of primary osteoporosis. The objective of this paper is to examine the unique pathology and underlying pathophysiology of disuse osteoporosis. 1. Introduction Osteoporosis is the condition in which a low bone mass and altered microarchitecture of the bone leads to increased risk of fracture. Traditionally, osteoporosis has been classified into primary and secondary osteoporosis. Primary osteoporosis refers to osteoporotic conditions which are not related to other chronic illnesses and is usually associated with aging and decreased gonadal function, such as decreased level of estrogen, whereas secondary osteoporosis is the type of osteoporosis caused by other health problems. Disuse is one of the many reasons inducing bone loss and resulting in secondary osteoporosis [1]. Disuse osteoporosis has been shown to be a regional phenomenon in the areas with tremendous decrease in weight bearing like lower limbs. Bones of lower limbs are subjected to mechanical stimulations during daily life provided by static gravity-related weight-bearing, ground reaction forces, and dynamic loading generated by muscle contractions during locomotion. Physical exercise is essential for increasing or maintaining bone mass and strength [2]. Milliken et al. [3] have investigated the effect of 1-year supervised weight training exercise on bone mineral density (BMD) in postmenopausal women. The result showed higher BMDs of trochanter and femoral neck in women with weight training exercise than in those lacking exercise. Chan et al. [4] have studied the effect of Tai-Chi excercise on bone quality in postmenopausal women. Postmenopausal women were randomly assigned to an exercise group or a control group. Subjects in the exercise group performed 5 sessions of 45 minutes Tai-Chi per week. After 1 year of Tai-Chi exercise, a greater percentage loss in bone density was observed in the control group when compared to the exercise
EFFECT OF OXYGEN PLASMA PRETREATMENT AND TITANIUM DIOXIDE OVERLAY COATING ON FLAME RETARDANT FINISHED COTTON FABRICS
Yin Ling Lam,Chi Wai Kan,Chun Wah Yuen
BioResources , 2011,
Abstract: Flammability properties of plasma pretreated cotton fabrics subjected to flame-retardant treatment were studied. Plasma pretreatment, using an atmospheric pressure plasma jet (APPJ), was applied to cotton fabrics to enhance material properties, while retaining inherent advantages of the substrates. An organic phosphorus compound (flame-retardant agent, FR) together with a melamine resin (crosslinking agent, CL) and phosphoric acid (catalyst, PA) were used. Titanium dioxide (TiO2) or nano-TiO2 was used as a co-catalyst for cotton fabrics to improve treatment effectiveness and minimize side effects. Surface morphology of plasma pretreated cotton specimens subjected to flame-retardant treatment showed a roughened and wrinkled fabric surface with high deposition of the finishing agent, caused by an etching effect of plasma and attack of acidic FR. Combustibility of FR-CL-PA-TiO2 and FR-CL-PA-Nano-TiO2 treated fabrics was evaluated by a 45° flammability test. FR-CL-PA-treated specimens showed superior flame-retardancy, which was further improved by plasma pretreatment and addition of metal oxide as a co-catalyst. However, in comparison with the control sample, flame-retardant-treated cotton specimens had lower breaking load and tearing strength, resulting from side effects of the crosslinking agent used, while plasma pretreatment might compensate for the reduction in tensile strength caused by flame-retardant agents. In addition, both plasma pretreatment and metal oxide co-catalyst added in the flame-retardant finishing improved the crosslinking process between FR and cotton fabric, minimizing formation of free formaldehyde and allowing the use of FR in industry.
Information Flow in One-Dimensional Vehicular Ad Hoc Networks
Chi Wan Sung,Kenneth W. Shum,Wing Ho Yuen
Mathematics , 2010,
Abstract: We consider content distribution in vehicular ad hoc networks. We assume that a file is encoded using fountain code, and the encoded message is cached at infostations. Vehicles are allowed to download data packets from infostations, which are placed along a highway. In addition, two vehicles can exchange packets with each other when they are in proximity. As long as a vehicle has received enough packets from infostations or from other vehicles, the original file can be recovered. In this work, we show that system throughput increases linearly with number of users, meaning that the system exhibits linear scalability. Furthermore, we analyze the effect of mobility on system throughput by considering both discrete and continuous velocity distributions for the vehicles. In both cases, system throughput is shown to decrease when the average speed of all vehicles increases. In other words, higher overall mobility reduces system throughput.
Synergistic Cytotoxic Effects of Ganoderma lucidum and Bacillus Calmette Guérin on Premalignant Urothelial HUC-PC Cells and Its Regulation on Proinflammatory Cytokine Secretion
John Wai-man Yuen,Mayur-Danny I. Gohel,Chi-fai Ng
Evidence-Based Complementary and Alternative Medicine , 2012, DOI: 10.1155/2012/147896
Abstract: Bacillus Calmette-Guérin (BCG) is conventionally used as an adjuvant immunotherapy to reduce the recurrence of bladder cancer. To address the issues of efficacy and safety, an ethanol extract of Ganoderma lucidum (GLe) was evaluated for its interaction with BCG. In a model of premalignant human uroepithelial cells (HUC-PC), GLe exerted immediate cytotoxic effects while BCG showed a delayed response, given that both were immunological active in inducing the secretion of interleukin (IL)-6, IL-8, and monocyte chemotactic protein-1 (MCP-1). Synergistic cytotoxic effects were observed when cells were either coincubated with both drugs or firstly preincubated with GLe. Synergism between GLe and BCG was demonstrated to achieve a complete cytostasis in 24 hours, and such effects were progressed in the subsequent 5 days. However, the pretreatment of GLe resulted in suppression of IL-6, IL-8, and MCP-1 secretions without affecting the cytotoxicity. Given that numerous proinflammatory cytokines are associated with the high side effects toll of BCG, results herein suggested the potential implications of GL to supplement the BCG immunotherapy in bladder cancer, for better efficacy and reducing side effects.
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