Showing papers by "Hong Kong Polytechnic University published in 2013"

Social media in tourism and hospitality : a literature review

Abstract: Being one of the “mega trends” that has significantly impacted the tourism system, the role and use of social media in travelers' decision making and in tourism operations and management have been widely discussed in tourism and hospitality research. This study reviews and analyzes all extant social media-related research articles published in academic journals during 2007 to 2011, mainly in tourism and hospitality fields. Based on a content analysis on the analyzed articles from both the consumers' and the suppliers' perspectives, this article found that consumer-centric studies generally focused on the use and impact of social media in the research phase of the travelers' travel planning process. Supplier-related studies have concentrated closely on promotion, management, and research functions, but few discussed product distribution. Research findings thoroughly demonstrate the strategic importance of social media for tourism competitiveness. This study also contributes to the academia and ind...

Application of decision-making techniques in supplier selection: A systematic review of literature

Abstract: Despite the importance of decision-making (DM) techniques for construction of effective decision models for supplier selection, there is a lack of a systematic literature review for it. This paper provides a systematic literature review on articles published from 2008 to 2012 on the application of DM techniques for supplier selection. By using a methodological decision analysis in four aspects including decision problems, decision makers, decision environments, and decision approaches, we finally selected and reviewed 123 journal articles. To examine the research trend on uncertain supplier selection, these articles are roughly classified into seven categories according to different uncertainties. Under such classification framework, 26 DM techniques are identified from three perspectives: (1) Multicriteria decision making (MCDM) techniques, (2) Mathematical programming (MP) techniques, and (3) Artificial intelligence (AI) techniques. We reviewed each of the 26 techniques and analyzed the means of integrating these techniques for supplier selection. Our survey provides the recommendation for future research and facilitates knowledge accumulation and creation concerning the application of DM techniques in supplier selection.

Recent Advances in Asymmetric Organocatalytic Construction of 3,3′-Spirocyclic Oxindoles

Abstract: The asymmetric organocatalysis is definitely one of the most powerful and versatile tools for the rapid construction of various spirocyclic oxindoles. In the past few years, a number of successful strategies based on organocatalysis have been developed for the construction of 3,3′-spirocyclic oxindoles in high yields and excellent enantioselectivities under mild conditions. In this review, recent advances in this area are summarized and classified according to the spiro ring fused at the 3-position of the oxindole core.

“Do We Believe in TripAdvisor?” Examining Credibility Perceptions and Online Travelers’ Attitude toward Using User-Generated Content

Abstract: Recent press reports and complaints by hoteliers have called into question the credibility of travel-related user-generated content (UGC). Yet our understanding of the role of credibility perceptions in the context of UGC is limited, notwithstanding the rising interest in social media. Using an online survey of 661 travel consumers, this study applies the component-based structural equation modeling technique of partial least squares to examine online travelers’ perceptions of the credibility of UGC sources and how these perceptions influence attitudes and intentions toward UGC utilization in the travel planning process. The model also draws on the theory of homophily to make predictions about the antecedent of credibility. Results validate the Source Credibility Theory in the context of UGC but also accentuate the central mediating role of attitude. In addition, the study finds support for perceptual homophily as a critical determinant of both credibility and attitude. Theoretical and managerial implicat...

Exceptional Tunability of Band Energy in a Compressively Strained Trilayer MoS2 Sheet

Abstract: Tuning band energies of semiconductors through strain engineering can significantly enhance their electronic, photonic, and spintronic performances Although low-dimensional nanostructures are rela

Review on life cycle assessment of energy payback and greenhouse gas emission of solar photovoltaic systems

Abstract: This paper aims to examine the sustainability and environmental performance of PV-based electricity generation systems by conducting a thorough review of the life cycle assessment (LCA) studies of five common photovoltaic (PV) systems, i.e., mono-crystalline (mono-Si), multi-crystalline (multi-Si), amorphous silicon (a-Si), CdTe thin film (CdTe) and CIS thin film (CIS), and some advanced PV systems. The results show that, among the five common PV systems, the CdTe PV system presents the best environmental performance in terms of energy payback time (EPBT) and greenhouse gases (GHG) emission rate due to its low life-cycle energy requirement and relatively high conversion efficiency. Meanwhile, the mono-Si PV system demonstrates the worst because of its high energy intensity during the solar cells’ production process. The EPBT and GHG emission rate of thin film PV systems are within the range of 0.75–3.5 years and 10.5–50 g CO 2 -eq./kW h, respectively. In general, the EPBT of mono-Si PV systems range from 1.7 to 2.7 years with GHG emission rate from 29 to 45 g CO 2 -eq./kW h, which is an order of magnitude smaller than that of fossil-based electricity. This paper also reviews the EPBT and GHG emission rates of some advanced PV systems, such as high-concentration, heterojunction and dye-sensitized technologies. The EBPT of high-concentration PV system is lower, ranging from 0.7 to 2.0 years, but the CO 2 emission rate of dye-sensitized PV system is higher than the ones of other PV systems at the moment. The LCA results show that PV technologies are already proved to be very sustainable and environmental-friendly in the state of the art. With the emerging of new manufacturing technologies, the environmental performance of PV technologies is expected to be further improved in the near future. In addition, considering the existing limitations in the previous LCA studies, a few suggestions are recommended.

Mechanical Exfoliation and Characterization of Single- and Few-Layer Nanosheets of WSe2, TaS2, and TaSe2

Abstract: Single- and few-layer transition-metal dichalcogenide nanosheets, such as WSe₂ , TaS₂, and TaSe₂, are prepared by mechanical exfoliation. A Raman microscope is employed to characterize the single-layer (1L) to quinary-layer (5L) WSe₂ nanosheets and WSe₂ single crystals with a laser excitation power ranging from 20 μW to 5.1 mW. Typical first-order together with some second-order and combinational Raman modes are observed. A new peak at around 308 cm⁻¹ is observed in WSe₂ except for the 1L WSe₂, which might arise from interlayer interactions. Red shifting of the A(1g) mode and the Raman peak around 308 cm⁻¹ is observed from 1L to 5L WSe₂. Interestingly, hexagonal- and monoclinic-structured WO₃ thin films are obtained during the local oxidation of thinner (1L-3L) and thicker (4L and 5L) WSe₂ nanosheets, while laser-burned holes are found during the local oxidation of the WSe₂ single crystal. In addition, the characterization of TaS₂ and TaSe₂ thin layers is also conducted.

Is Corporate Social Responsibility (CSR) Associated with Tax Avoidance? Evidence from Irresponsible CSR Activities

Abstract: We examine the empirical association between corporate social responsibility (CSR) and tax avoidance. Our findings suggest that firms with excessive irresponsible CSR activities have a higher likelihood of engaging in tax sheltering activities and greater discretionary/permanent book-tax differences. Moreover, at the onset of FASB Interpretation No. 48, these firms have more uncertain tax positions; also, these firms’ initial tax positions are likely supported by weaker facts and circumstances as indicated by their larger post-FIN 48 settlements with tax authorities and their higher likelihood of a net decrease in the overall level of uncertain tax positions after FIN 48. Collectively, these results suggest that firms with excessive irresponsible CSR activities are more aggressive in avoiding taxes, lending credence to the idea that corporate culture affects tax avoidance.

New Perspectives on How to Discover Drugs from Herbal Medicines: CAM's Outstanding Contribution to Modern Therapeutics.

Abstract: With tens of thousands of plant species on earth, we are endowed with an enormous wealth of medicinal remedies from Mother Nature. Natural products and their derivatives represent more than 50% of all the drugs in modern therapeutics. Because of the low success rate and huge capital investment need, the research and development of conventional drugs are very costly and difficult. Over the past few decades, researchers have focused on drug discovery from herbal medicines or botanical sources, an important group of complementary and alternative medicine (CAM) therapy. With a long history of herbal usage for the clinical management of a variety of diseases in indigenous cultures, the success rate of developing a new drug from herbal medicinal preparations should, in theory, be higher than that from chemical synthesis. While the endeavor for drug discovery from herbal medicines is “experience driven,” the search for a therapeutically useful synthetic drug, like “looking for a needle in a haystack,” is a daunting task. In this paper, we first illustrated various approaches of drug discovery from herbal medicines. Typical examples of successful drug discovery from botanical sources were given. In addition, problems in drug discovery from herbal medicines were described and possible solutions were proposed. The prospect of drug discovery from herbal medicines in the postgenomic era was made with the provision of future directions in this area of drug development.

Selective decoration of Au nanoparticles on monolayer MoS2 single crystals.

Abstract: We report a controllable wet method for effective decoration of 2-dimensional (2D) molybdenum disulfide (MoS2) layers with Au nanoparticles (NPs). Au NPs can be selectively formed on the edge sites or defective sites of MoS2 layers. The Au-MoS2 nano-composites are formed by non-covalent bond. The size distribution, morphology and density of the metal nanoparticles can be tuned by changing the defect density in MoS2 layers. Field effect transistors were directly fabricated by placing ion gel gate dielectrics on Au-decorated MoS2 layers without the need to transfer these MoS2 layers to SiO2/Si substrates for bottom gate devices. The ion gel method allows probing the intrinsic electrical properties of the as-grown and Au-decorated MoS2 layers. This study shows that Au NPs impose remarkable p-doping effects to the MoS2 transistors without degrading their electrical characteristics.

Hollow carbon-nanotube/carbon-nanofiber hybrid anodes for Li-ion batteries.

Abstract: By a novel in situ chemical vapor deposition, activated N-doped hollow carbon-nanotube/carbon-nanofiber composites are prepared having a superhigh specific Brunauer–Emmett–Teller (BET) surface area of 1840 m(2) g(–1) and a total pore volume of 121 m(3) g(–1) As an anode, this material has a reversible capacity of ~1150 mAh g(–1) at 01 A g(–1) (027 C) after 70 cycles At 8 A g(–1) (215 C), a capacity of ~320 mAh g(–1) fades less than 20% after 3500 cycles, which makes it a superior anode material for a Li-ion battery

Genome-wide meta-analyses of multiancestry cohorts identify multiple new susceptibility loci for refractive error and myopia

Abstract: Refractive error is the most common eye disorder worldwide and is a prominent cause of blindness Myopia affects over 30% of Western populations and up to 80% of Asians The CREAM consortium conducted genome-wide meta-analyses, including 37,382 individuals from 27 studies of European ancestry and 8,376 from 5 Asian cohorts We identified 16 new loci for refractive error in individuals of European ancestry, of which 8 were shared with Asians Combined analysis identified 8 additional associated loci The new loci include candidate genes with functions in neurotransmission (GRIA4), ion transport (KCNQ5), retinoic acid metabolism (RDH5), extracellular matrix remodeling (LAMA2 and BMP2) and eye development (SIX6 and PRSS56) We also confirmed previously reported associations with GJD2 and RASGRF1 Risk score analysis using associated SNPs showed a tenfold increased risk of myopia for individuals carrying the highest genetic load Our results, based on a large meta-analysis across independent multiancestry studies, considerably advance understanding of the mechanisms involved in refractive error and myopia

Beauty is in the Eye of the Beholder: The Effect of Corporate Tax Avoidance on the Cost of Bank Loans

Abstract: We find that firms with greater tax avoidance incur higher spreads when obtaining bank loans. This finding is robust in a battery of sensitivity analyses and in two quasi experimental settings including the implementation of Financial Accounting Standards Board Interpretation No. 48 and the revelation of past tax sheltering activity. Firms with greater tax avoidance also incur more stringent non-price loan terms, incur higher at-issue bond spreads, and prefer bank loans over public bonds when obtaining debt financing. Overall, these findings indicate that banks perceive tax avoidance as engendering significant risks.

Noninvasive detection of cancer-associated genome-wide hypomethylation and copy number aberrations by plasma DNA bisulfite sequencing

Abstract: We explored the detection of genome-wide hypomethylation in plasma using shotgun massively parallel bisulfite sequencing as a marker for cancer. Tumor-associated copy number aberrations (CNAs) could also be observed from the bisulfite DNA sequencing data. Hypomethylation and CNAs were detected in the plasma DNA of patients with hepatocellular carcinoma, breast cancer, lung cancer, nasopharyngeal cancer, smooth muscle sarcoma, and neuroendocrine tumor. For the detection of nonmetastatic cancer cases, plasma hypomethylation gave a sensitivity and specificity of 74% and 94%, respectively, when a mean of 93 million reads per case were obtained. Reducing the sequencing depth to 10 million reads per case was found to have no adverse effect on the sensitivity and specificity for cancer detection, giving respective figures of 68% and 94%. This characteristic thus indicates that analysis of plasma hypomethylation by this sequencing-based method may be a relatively cost-effective approach for cancer detection. We also demonstrated that plasma hypomethylation had utility for monitoring hepatocellular carcinoma patients following tumor resection and for detecting residual disease. Plasma hypomethylation can be combined with plasma CNA analysis for further enhancement of the detection sensitivity or specificity using different diagnostic algorithms. Using the detection of at least one type of aberration to define an abnormality, a sensitivity of 87% could be achieved with a specificity of 88%. These developments have thus expanded the applications of plasma DNA analysis for cancer detection and monitoring.

Long-term mechanical and durability properties of recycled aggregate concrete prepared with the incorporation of fly ash

Abstract: This paper presents the findings of a long-term study on the mechanical and durability properties of concrete prepared with 0%, 50% and 100% recycled concrete aggregate that were cured in water or outdoor exposure conditions for 10 years. The recycled aggregate concrete (RAC) was prepared by using 25%, 35% and 55% class-F fly ash, as cement replacements. It was found that, after 10 years, the compressive strength and modulus of elasticity of the concrete prepared with 100% recycled concrete aggregate was still lower than that of the control concrete. Over this period, the highest gain in compressive strength and modulus of elasticity was recorded for the concrete mixture prepared with 55% fly ash. Fly ash improved the resistance to chloride ion penetration but it also increased the carbonation depth of the concrete.

Direct measurements of conformer-dependent reactivity of the Criegee intermediate CH3CHOO

Abstract: Although carbonyl oxides, “Criegee intermediates,” have long been implicated in tropospheric oxidation, there have been few direct measurements of their kinetics, and only for the simplest compound in the class, CH2OO. Here, we report production and reaction kinetics of the next larger Criegee intermediate, CH3CHOO. Moreover, we independently probed the two distinct CH3CHOO conformers, syn- and anti-, both of which react readily with SO2 and with NO2. We demonstrate that anti-CH3CHOO is substantially more reactive toward water and SO2 than is syn-CH3CHOO. Reaction with water may dominate tropospheric removal of Criegee intermediates and determine their atmospheric concentration. An upper limit is obtained for the reaction of syn-CH3CHOO with water, and the rate constant for reaction of anti-CH3CHOO with water is measured as 1.0 × 10−14 ± 0.4 × 10−14 centimeter3 second−1.

Carbon nanotube membranes with ultrahigh specific adsorption capacity for water desalination and purification

Abstract: Development of technologies for water desalination and purification is critical to meet the global challenges of insufficient water supply and inadequate sanitation, especially for point-of-use applications. Conventional desalination methods are energy and operationally intensive, whereas adsorption-based techniques are simple and easy to use for point-of-use water purification, yet their capacity to remove salts is limited. Here we report that plasma-modified ultralong carbon nanotubes exhibit ultrahigh specific adsorption capacity for salt (exceeding 400% by weight) that is two orders of magnitude higher than that found in the current state-of-the-art activated carbon-based water treatment systems. We exploit this adsorption capacity in ultralong carbon nanotube-based membranes that can remove salt, as well as organic and metal contaminants. These ultralong carbon nanotube-based membranes may lead to next-generation rechargeable, point-of-use potable water purification appliances with superior desalination, disinfection and filtration properties.

Upconverting Near‐Infrared Light through Energy Management in Core–Shell–Shell Nanoparticles

Abstract: Lanthanide-doped upconversion materials, capable of converting low-density (< 1000 W cm ) near-infrared (NIR) excitation to ultraviolet (UV) and visible emissions, have generated a large amount of interests in the areas of information technology, biotechnology, energy, and photonics. Significantly, recent developments in the synthetic and multicolor tuning methods have allowed easy access to upconversion nanoparticles with well-defined phase and size, core–shell structure, optical emission, and surface properties. The technological advances provide promising applications in sensitive biodetection and advanced bioimaging without many of the constraints associated with conventional optical biolabels. Despite the attractions, further progress in using upconversion processes has been largely hindered because upconversion nanoparticles are typically sensitized by Yb ions that only respond to narrowband NIR excitation centered at 980 nm. The absorption of 980 nm light by the water component in biological samples usually limits deep tissue imaging and induces potential thermal damages to cells and tissues. Excitation of conventional upconversion nanoparticles at other wavelengths has been proposed to minimize the effect of water absorption. But the use of this technique is limited mainly by the largely sacrificed excitation efficiency. Efforts have also been devoted to tuning the NIR response of photon upconversion through integration of various sensitizers such as metal ions (e.g.; Nd, V or Cr) and organic dyes. The progress has resulted in visible emission by NIR excitation in the 700–900 nm range where the transparency of biological samples is maximal. However, upconversion emission across a broad range of spectra in these systems have not been demonstrated largely owing to the uncontrollable nonradiative processes. Herein, we describe a novel design, based on nanostructural engineering to separate unwanted electronic transitions for constructing a new class of materials displaying tunable upconversion emissions spanning from UV to the visible spectral region by single wavelength excitation at 808 nm. We also show that these nanoparticles can surpass the constraints associated with conventional upconversion nanoparticles for biological studies. The nanostructure design for management of energy transitions is depicted in Figure 1. A core–shell–shell nanoparticle platform is used to host light-harvesting, upconvert-

Metagenomic profiles of antibiotic resistance genes (ARGs) between human impacted estuary and deep ocean sediments

Abstract: Knowledge of the origins and dissemination of antibiotic resistance genes (ARGs) is essential for understanding modern resistomes in the environment. The mechanisms of the dissemination of ARGs can be revealed through comparative studies on the metagenomic profiling of ARGs between relatively pristine and human-impacted environments. The deep ocean bed of the South China Sea (SCS) is considered to be largely devoid of anthropogenic impacts, while the Pearl River Estuary (PRE) in south China has been highly impacted by intensive human activities. Commonly used antibiotics (sulfamethazine, norfloxacin, ofloxacin, tetracycline, and erythromycin) have been detected through chemical analysis in the PRE sediments, but not in the SCS sediments. In the relatively pristine SCS sediments, the most prevalent and abundant ARGs are those related to resistance to macrolides and polypeptides, with efflux pumps as the predominant mechanism. In the contaminated PRE sediments, the typical ARG profiles suggest a prevailing resistance to antibiotics commonly used in human health and animal farming (including sulfonamides, fluoroquinolones, and aminoglycosides), and higher diversity in both genotype and resistance mechanism than those in the SCS. In particular, antibiotic inactivation significantly contributed to the resistance to aminoglycosides, β-lactams, and macrolides observed in the PRE sediments. There was a significant correlation in the levels of abundance of ARGs and those of mobile genetic elements (including integrons and plasmids), which serve as carriers in the dissemination of ARGs in the aquatic environment. The metagenomic results from the current study support the view that ARGs naturally originate in pristine environments, while human activities accelerate the dissemination of ARGs so that microbes would be able to tolerate selective environmental stress in response to anthropogenic impacts.

Impact of store environment on impulse buying behavior

Abstract: Purpose – This paper aims to explore the process by which four store environment (music, light, employee, and layout) and two individual characteristics (shopping enjoyment tendency (SET) and impulse buying tendency (IBT)) influence impulse buying behavior through positive and negative affect, and urge to buy impulsively. Design/methodology/approach – The data were obtained using a structured questionnaire from 733 respondents in a mall survey conducted in Chennai, South India. Findings – In the structural model tested with AMOS, the authors found that store environment drove impulse buying (IB) through positive affect and urge. Results also showed that the personality variables (SET and IBT) influenced IB through positive affect and urge. This paper did not find support for the relationship between negative affect and urge. Research limitations/implications – Theoretically, the authors add to the list of antecedents of impulse buying, and to the outcomes of store environment. From a managerial viewpoint,...