Showing papers by "University of Macau published in 2009"

Recent developments in stainless steels

Abstract: This article presents an overview of the developments in stainless steels made since the 1990s. Some of the new applications that involve the use of stainless steel are also introduced. A brief introduction to the various classes of stainless steels, their precipitate phases and the status quo of their production around the globe is given first. The advances in a variety of subject areas that have been made recently will then be presented. These recent advances include (1) new findings on the various precipitate phases (the new J phase, new orientation relationships, new phase diagram for the Fe–Cr system, etc.); (2) new suggestions for the prevention/mitigation of the different problems and new methods for their detection/measurement and (3) new techniques for surface/bulk property enhancement (such as laser shot peening, grain boundary engineering and grain refinement). Recent developments in topics like phase prediction, stacking fault energy, superplasticity, metadynamic recrystallisation and the calculation of mechanical properties are introduced, too. In the end of this article, several new applications that involve the use of stainless steels are presented. Some of these are the use of austenitic stainless steels for signature authentication (magnetic recording), the utilisation of the cryogenic magnetic transition of the sigma phase for hot spot detection (the Sigmaplugs), the new Pt-enhanced radiopaque stainless steel (PERSS) coronary stents and stainless steel stents that may be used for magnetic drug targeting. Besides recent developments in conventional stainless steels, those in the high-nitrogen, low-Ni (or Ni-free) varieties are also introduced. These recent developments include new methods for attaining very high nitrogen contents, new guidelines for alloy design, the merits/demerits associated with high nitrogen contents, etc.

Design and Analysis of a Totally Decoupled Flexure-Based XY Parallel Micromanipulator

Abstract: In this paper, a concept of totally decoupling is proposed for the design of a flexure parallel micromanipulator with both input and output decoupling. Based on flexure hinges, the design procedure for an XY totally decoupled parallel stage (TDPS) is presented, which is featured with decoupled actuation and decoupled output motion as well. By employing (double) compound parallelogram flexures and a compact displacement amplifier, a class of novel XY TDPS with simple and symmetric structures are enumerated, and one example is chosen for further analysis. The kinematic and dynamic modeling of the manipulator are conducted by resorting to compliance and stiffness analysis based on the matrix method, which are validated by finite-element analysis (FEA). In view of predefined performance constraints, the dimension optimization is carried out by means of particle swarm optimization, and a prototype of the optimized stage is fabricated for performance tests. Both FEA and experimental studies well validate the decoupling property of the XY stage that is expected to be adopted into micro-/nanoscale manipulations.

The effects of reform on China’s bank structure and performance

Abstract: This paper investigates the relationship between market structure and performance in China’s banking system from 1985 to 2002, a period when this sector was subject to gradual but notable reform. Using panel data estimation techniques, both the market-power and efficient-structure hypotheses are tested. In addition, the model is extended to consider issues such as the impact of bank size/ownership and whether the big four banks enjoy a “quiet life”. On average, X-efficiency declined significantly and most banks were operating below scale efficient levels. Estimation of the structure–performance models lends some support to the relative market-power hypothesis in the early period. The reforms had little impact on the structure of China’s banking sector, though the “joint stock” banks became relatively more X-efficient. There was no evidence to support the quiet-life hypothesis, probably because strict interest rate controls prevented the state banks from earning monopoly profits. Thus the ongoing liberalisation of interest rates should be accompanied by reduced concentration. Overall, to improve competitive structure, new policies should be directed at encouraging market entry and increasing the market share of the most efficient banks.

Complex Zernike Moments Features for Shape-Based Image Retrieval

Abstract: Shape is a fundamental image feature used in content-based image-retrieval systems. This paper proposes a robust and effective shape feature, which is based on a set of orthogonal complex moments of images known as Zernike moments (ZMs). As the rotation of an image has an impact on the ZM phase coefficients of the image, existing proposals normally use magnitude-only ZM as the image feature. In this paper, we compare, by using a mathematical form of analysis, the amount of visual information captured by ZM phase and the amount captured by ZM magnitude. This analysis shows that the ZM phase captures significant information for image reconstruction. We therefore propose combining both the magnitude and phase coefficients to form a new shape descriptor, referred to as invariant ZM descriptor (IZMD). The scale and translation invariance of IZMD could be obtained by prenormalizing the image using the geometrical moments. To make the phase invariant to rotation, we perform a phase correction while extracting the IZMD features. Experiment results show that the proposed shape feature is, in general, robust to changes caused by image shape rotation, translation, and/or scaling. The proposed IZMD feature also outperforms the commonly used magnitude-only ZMD in terms of noise robustness and object discriminability.

TNF-α, a potent lipid metabolism regulator

Abstract: As a multifunctional cytokine, tumor necrosis factor alpha (TNF-α) exerts a series of biological actions in different cells, tissues, organs, and species and has been demonstrated to regulate and interfere with energy metabolism, especially lipid homeostasis. A large body of researches suggested that the effects of TNF-α on lipid metabolism mainly include five aspects: (1) suppresses free fatty acid (FFA) uptake and promotes lipogenesis; (2) induces lipolysis; (3) inhibits lipid-metabolism-related enzymes activity; (4) regulates cholesterol metabolism; (5) regulates other adipocyte-derived adipokines. The molecular mechanisms underlying these actions are complex and several signal transduction pathways might be involved. Regulation of metabolism-related gene expression at transcriptional and protein levels and impact on enzymes activity might be of importance. Identification and verification of these pathways might provide novel potential strategies and drug targets for dyslipidemia therapy. However, the inconsistent and even conflict conclusions on lipid profile drawn from human subjects after infliximab therapy poses the possibility that the effect of TNF-α on lipid metabolism might be more complicated than it appeared to be. Copyright © 2009 John Wiley & Sons, Ltd.

Formulation Development and Bioavailability Evaluation of a Self-Nanoemulsified Drug Delivery System of Oleanolic Acid

Abstract: This study aims to formulate and evaluate bioavailability of a self-nanoemulsified drug delivery system (SNEDDS) of a poorly water-soluble herbal active component oleanolic acid (OA) for oral delivery. Solubility of OA under different systems was determined for excipient selection purpose. Four formulations, where OA was fixed at the concentration of 20 mg/g, were prepared utilizing Sefsol 218 as oil phase, Cremophor EL and Labrasol as primary surfactants, and Transcutol P as cosurfactant. Pseudo-ternary phase diagrams were constructed to identify self-emulsification regions for the rational design of SNEDDS formulations. Sefsol 218 was found to provide the highest solubility among all medium-chained oils screened. Efficient self-emulsification was observed for the systems composing of Cremophor EL and Labrasol. The surfactant to cosurfactant ratio greatly affected the droplet size of the nanoemulsion. Based on the outcomes in dissolution profiles, stability data, and particle size profiles, three optimized formulations were selected: Sefsol 218/Cremophor EL/Labrasol (50:25:25, w/w), Sefsol 218/Cremophor EL/Labrasol/Transcutol P (50:20:20:10, w/w), and Sefsol 218/Cremophor EL/Labrasol/Transcutol P (50:17.5:17.5:15, w/w). Based on the conventional dissolution method, a remarkable increase in dissolution was observed for the SNEDDS when compared with the commercial tablet. The oral absorption of OA from SNEDDS showed a 2.4-fold increase in relative bioavailability compared with that of the tablet (p < 0.05), and an increased mean retention time of OA in rat plasma was also observed compared with that of the tablet (p < 0.01). These results suggest the potential use of SNEDDS to improve dissolution and oral bioavailability for poorly water-soluble triterpenoids such as OA.

Four-factor justice and daily job satisfaction: a multilevel investigation.

Abstract: This study examined the differential effects of 4 types of organizational justice on daily job satisfaction at between- and within-individual levels. Specifically, the authors predicted that interpersonal justice and informational justice would exhibit meaningful daily variations and would have direct impacts on individuals’ job satisfaction on a daily basis. They further theorized that distributive justice and procedural justice at a between-person level would moderate the within-person relationships. The authors used hierarchical linear modeling to test their hypotheses with a sample of 231 full-time employees in Hong Kong over the course of 25 working days. The results showed that both daily interpersonal and informational justice were positively related to daily job satisfaction. As hypothesized, betweenindividual distributive justice moderated the relationship between daily interpersonal justice and daily job satisfaction, and between-individual procedural justice moderated the relationship between daily informational justice and daily job satisfaction.

Linking Leader-Member Exchange and Employee Work Outcomes: The Mediating Role of Organizational Social and Economic Exchange

Abstract: This study presents and tests a framework that links leader-member exchange (LMX) with two different forms of employee-organization exchange: organizational social exchange and organizational economic exchange. We propose that these two forms of employee exchange with the organization would be the main mechanisms through which LMX affects employees' affective commitment and intention to leave. We used structural equation modelling to analyze the data collected from 239 employees in a foreign-invested enterprise in China. Results showed that both organizational social exchange and organizational economic exchange acted as full mediators in the relationships between LMX and the two outcome variables but in different directions. Theoretical and practical implications are discussed. more_149 401..422

Family friendly work practices, organizational climate, and firm performance: A study of multinational corporations in Hong Kong

Abstract: Summary We developed and tested a conceptual model to examine the impact of family friendly work practices (FFWPs) at the organizational level. In our model, top management support for equal opportunities is considered an antecedent of FFWPs and positive organizational climate, and firm performance and employee turnover are considered outcome variables. Structural equation modeling (SEM) was used to analyze the data collected from a sample of HR managers in multinational corporations (MNCs) in Hong Kong. The results showed that top management support for equal opportunities was positively related to a firm’s level of FFWPs and organizational climate. In addition, FFWPs were positively related to organizational climate. We further found that organizational climate acted as a mediator between FFWPs and firm-level outcomes. Copyright # 2009 John Wiley & Sons, Ltd.

Adiponectin, an unlocking adipocytokine.

Abstract: A large number of studies revealed that adiponectin, a protein secreted specifically by adipose tissue, exhibits antiinflammatory, antiatherogenic, and antidiabetic properties. This 247-amino acid protein contains four differentiable domains and exists in five different configurations, which binds three kinds of receptors. The plasma adiponectin concentration is at amazing microgram level and the gender difference is very clear. Obese subjects showed decreased plasma level of adiponectin while exercise seems to restore it. Many researchers demonstrated that it could be a reliable biomarker for multiple diseases. However, there is controversy about its role in inflammation since its plasma concentration decreases in some inflammatory diseases and increases under some other inflammatory conditions. The signal transduction pathway is still not very clear yet. Could adiponectin be a promising drug target?

Chemical characteristics of Salvia miltiorrhiza (Danshen) collected from different locations in China.

Abstract: The chemical characteristics of Salvia miltiorrhiza , also called "danshen" in China, were investigated on the basis of the simultaneous quantitative determination of 13 hydrophilic and lipophilic compounds, namely, protocatechuic acid, protocatechuic aldehyde, caffeic acid, ferulic acid, isoferulic acid, rosmarinic acid, salvianolic acid B, salvianolic acid A, dihydrotanshinone I, przewalskin, cryptotanshinone, tanshinone I, and tanshinone IIA, in 74 samples collected from different locations using ultraperformance liquid chromatography (UPLC). Hierarchical clustering analysis based on 13 investigated compounds and the similarity of the entire chromatographic pattern showed that S. miltiorrhiza was significantly different from Salvia przewalskii , an adulterant of danshen. The chemical characteristics of S. miltiorrhiza collected from different locations in China were revealed, and salvianolic acid B, rosmarinic acid, cryptotanshinone, and tanshinones I and IIA were optimized as markers for the evaluation, which is helpful in the quality control of S. miltiorrhiza.

Angiogenic Effect of Saponin Extract from Panax notoginseng on HUVECs In Vitro and Zebrafish In Vivo

Abstract: Angiogenesis plays an important role in a wide range of physiological processes such as wound healing and fetal development. In fact, many diseases are associated with imbalance in the regulation of angiogenesis in which there is either excessive or insufficient blood vessel formation. Panax notoginseng, a blood circulation invigorating herb, is commonly used in traditional Chinese medicine to treat circulation-related diseases. However, the biological effects of saponin extract from Panax notoginseng (PNS) on angiogenesis and the underlying mechanisms are yet to be fully elucidated. This investigation describes the angiogenic effects of PNS on human umbilical vein endothelial cells (HUVECs) in vitro and zebrafish in vivo. The 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)5[(phenylamino)carbonyl]2H-tetrazolium hydroxide (XTT) assay and microscopic cell counting demonstrated that the extract was able to stimulate the proliferation of HUVECs. Meanwhile, the numbers of invaded cells and tube branches were significantly increased in PNS treatment groups. PNS was also shown to promote changes in the subintestinal vessels, a feature of angiogenesis, in zebrafish. In addition, by using real-time polymerase chain reaction (PCR), PNS was found to enhance vascular endothelial growth factor (VEGF) and kinase-domain region/fetal liver kinase-1 in mice (KDR/Flk-1) mRNA expression, and the PNS-induced HUVECs proliferation could be abolished by a KDR/Flk-1 inhibitor. Furthermore, the proliferation of HUVECs induced by PNS was significantly attenuated by inhibitors of PI3K-Akt-eNOS. All the results suggest that PNS can promote angiogenesis, and that the proangiogenic effects involve the VEGF-KDR/Flk-1 and PI3K-Akt-eNOS signaling pathways.

Organizational socialization: the missing link between employee needs and organizational culture

Abstract: Purpose – The purpose of this paper is to address the two research gaps in the literature between employee needs and organizational socialization; and organizational socialization and organizational culture by examining the relationships among four employee motivational needs (for achievement, affiliation, autonomy, and power), four organizational socialization content areas (training, understanding, coworker support, and future prospects), and three facets of organizational culture (bureaucratic, innovative, and supportive).Design/methodology/approach – Questionnaire data of 156 full‐time employees from a variety of organizations are analyzed by correlations, regressions, and structural equation modeling (SEM).Findings – Employee motivational needs explain significant variance for all socialization domains; whereas socialization explains significant variance for all organizational cultures (while needs explain little or no variance for culture). Regression and SEM analyses establish that organizational s...

Evaluating the Temporal and Spatial Urban Expansion Patterns of Guangzhou from 1979 to 2003 by Remote Sensing and GIS Methods

Abstract: China has experienced and is experiencing expeditious urban expansion in the recent decades, especially in the coastal areas and big cities. Rapid urban expansion and dramatic changes of landscape have caused great economic, environmental and social impacts consequently. It is crucial to understand urban temporal, spatial expansion patterns and their related effects. In this paper, urban expansion of Guangzhou, a rapid growing city in south‐east China, from 1979 to 2003 is studied temporally and spatially. Four time ranges including 1979–1990, 1990–1995, 1995–2000 and 2000–2003 are designed and the urban expansion area, expansion rate and the spatial expansion pattern are discussed by using remote sensing data and Geographical Information System (GIS) tool. Two transects are designed along two axes of Guangzhou expansion and the structural of urban expansion patches at different orientations are compared in order to quantitively understand the urban expansion of Guangzhou during the past 24 years. The gra...

Dynamic modeling and robust control of a 3-PRC translational parallel kinematic machine

Abstract: The dynamic modeling and robust control for a three-prismatic-revolute-cylindrical (3-PRC) parallel kinematic machine (PKM) with translational motion have been investigated in this paper. By introducing a mass distribution factor, the simplified dynamic equations have been derived via the virtual work principle and validated on a virtual prototype with the ADAMS software package. Based upon the established model, three dynamics controllers have been attempted on the 3-PRC PKM. The intuitive co-simulations with the combination of MATLAB/Simulink and ADAMS show that the control performance of neither inverse dynamics control nor robust inverse dynamics control is satisfactory in the presence of parametric uncertainties in PKM dynamics. On the contrary, the controller based on the passivity-based robust control scheme is more suitable for tracking control of the PKM in terms of both control performances and controller design procedures. The results presented in the paper provide a sound base for both the mechanical system design and control system design of a 3-PRC PKM.

Bayesian Probabilistic Approach for the Correlations of Compression Index for Marine Clays

Abstract: The compression index is an important soil property that is essential to many geotechnical designs. Over the decades, a number of empirical correlations have been proposed to relate the compressibility to other soil index properties, such as the liquid limit, plasticity index, in situ water content, void ratio, specific gravity, etc. The reliability and thus predictability of these correlations are always being questioned. Moreover, selection between simple and complicated models is a difficult task and often depends on subjective judgments. A more complicated model obviously provides "better fit" to the data but not necessarily offers an acceptable degree of robustness to measurement noise and modeling error. In the present study, the Bayesian probabilistic approach for model class selection is used to revisit the empirical multivariate linear regression formula of the compression index. The criterion in the formula structure selection is based on the plausibility of a class of formulas conditional on the measurement, instead of considering the likelihood only. The plausibility balances between the data fitting capability and sensitivity to measurement and modeling error, which is quantified by the Ockham factor. The Bayesian method is applied to analyze a data set of 795 records, including the compression index and other well-known geotechnical index properties of marine clay samples collected from various sites in South Korea. It turns out that the correlation formula linking the compression index to the initial void ratio and liquid limit possesses the highest plausibility among a total of 18 candidate classes of formulas. The physical significance of this most plausible correlation is addressed. It turns out to be consistent with previous studies and the Bayesian method provides the confirmation from another angle.

Conflicting Identities and Power Between Communities of Practice: The Case of IT Outsourcing

Abstract: Previous studies of communities of practice had often emphasized the ease with which members are able to participate in the collective learning process through joint practices within a particular community. However, nothing much has been done to reveal the difficulties and problems of learning between different communities due to different and sometimes conflicting identities and power inequalities. This article reports a failed experience of a tertiary institution to outsource its information technology (IT) department. By highlighting the social conflicts experienced by the in-house IT technicians in coordinating with the outsourcing staff, we argue that the received unitary, managerialist viewpoints of communities of practice somehow neglect the broader social context and micro-political factors of learning. This neglect underestimates the critical challenges of resolving the social tensions caused by multiple identities and embedded power differentials across different communities of practice.

Evaluation of Antiproliferative Activities and Action Mechanisms of Extracts from Two Species of Ganoderma on Tumor Cell Lines

Abstract: The antiproliferative activities on tumoral cells, namely, human breast cancer (MCF-7 and MDA-MB-231), hepatoma (HepG2) and myeloid leukemia (HL-60), of ethanolic extracts from two species of Ganoderma, G. lucidum and G. sinense, were investigated. Though both extracts had certain antiproliferative activities, their chemical characteristics, including nucleosides, triterpenoids and sterols, were significantly different. Their effects on MDA-MB-231 cells were further studied using apoptotic detection and cell cycle analyses. As a result, both had apoptosis induction through the alternation of mitochondrial transmembrane depolarization, though no triterpenoids were detected in ethanolic extract of G. sinense. Furthermore, the two extracts from G. lucidum and G. sinense could arrest cell cycle at different phases. This study showed that ethanol extracts of both G. lucidum and G. sinense have antitumoral proliferation effect through both apoptosis pathway and cell cycle arrest effect, and some other compounds such as sterols and/or nucleosides may contribute to their activity besides triterpenoids.