Trang T. Nguyen

Psychological capital, quality of work life and quality of life of marketers : evidence from Vietnam

This study examines the roles of psychological capital (PsyCap) in job performance and quality of work life (QWL) of marketers in a transitioning market, Vietnam. It also investigates the impacts of marketers’ QWL on their job performance and quality of life (QoL). A test based upon a sample of 364 marketers in Ho Chi Minh (HCM) City reveals that PsyCap has positive impacts on both job performance and QWL of marketers. In addition, QWL underlies both job performance and QoL of marketers. These findings confirm the importance of PsyCap in marketers’ work and lives in a transitioning market.

Hedonic shopping motivations, supermarket attributes, and shopper loyalty in transitional markets: Evidence from Vietnam

Purpose – This study aims to explore the impact of hedonic shopping motivations (HSM) and supermarket attributes (SMA) on shopper loyalty (SLO).Design/methodology/approach – A sample of 608 supermarket shoppers in Ho Chi Minh City, Vietnam was surveyed to test the model. Structural equation modeling was used to analyze the data.Findings – It was found that SMA and HSM had positive effects on SLO. It was also found that the impact of hedonic motivations on SLO was different between the younger and older, as well as lower and higher income groups of customers. However, no such difference was found between female and male shoppers.Research limitations/implications – A major limitation of this study was the use of a sample drawn from one transitional market. Cross‐national samples will be a direction for further research. Also, the study focuses on attitudinal loyalty. Behavioral loyalty should be taken into account in future research.Practical implications – The findings suggest that the supermarket managers...

Comparison of the energetics of avidin, streptavidin, neutrAvidin, and anti-biotin antibody binding to biotinylated lipid bilayer examined by second-harmonic generation.

A comparison of the binding properties of avidin, streptavidin, neutrAvidin, and antibiotin antibody to a biotinylated lipid bilayer was studied using second-harmonic generation. Protein binding assays were performed on a planar supported lipid bilayer of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) containing 4 mol % biotinylated-cap-1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (biotin-cap-DOPE). The equilibrium binding affinities of these biotin-protein interactions were determined, revealing the relative energetic contributions for each protein to the biotinylated lipid ligand. The results show that the binding affinities of avidin, streptavidin, and neutrAvidin for biotin were all strengthened by protein-protein interactions but that the stronger protein-protein interactions observed for streptavidin and neutrAvidin make their binding more energetically favorable. It was also shown that neutrAvidin has the highest degree of nonspecific adsorption to a pure DOPC bilayer, compared to avidin and streptavidin. In addition, the biotin-binding affinity of the antibiotin antibody was found to be of the same order of magnitude as that of avidin, streptavidin, and neutrAvidin. These findings provide important new insights into these biotin-bound protein complexes commonly used in several bioanalytical applications.

High-throughput screening of drug-lipid membrane interactions via counter-propagating second harmonic generation imaging.

Here we report the use of counter-propagating second harmonic generation (SHG) to image the interactions between the local anesthetic tetracaine and a multicomponent planar supported lipid bilayer array in a label-free manner. The lipid bilayer arrays, prepared using a 3D continuous flow microspotter, allow the effects of lipid phase and cholesterol content on tetracaine binding to be examined simultaneously. SHG images show that tetracaine has a higher binding affinity to liquid-crystalline phase lipids than to solid-gel phase lipids. The presence of 28 mol % cholesterol decreased the binding affinity of tetracaine to bilayers composed of the mixed chain lipid, 1-steroyl-2-oleoyl-sn-glycero-3-phophocholine (SOPC), and the saturated lipids 1,2-dimyristoyl-sn-glycero-3-phophocholine (DMPC) and 1,2-dipamitoyl-sn-glycero-3-phophocholine (DPPC) while having no effect on diunsaturated 1,2-dioleoyl-sn-glycero-3-phophocholine (DOPC). The maximum surface excess of tetracaine increases with the degree of unsaturation of the phospholipids and decreases with cholesterol in the lipid bilayers. The paper demonstrates that SHG imaging is a sensitive technique that can directly image and quantitatively measure the association of a drug to a multicomponent lipid bilayer array, providing a high-throughput means to assess drug-membrane interactions.

Label-Free Detection of Drug-Membrane Association using Ultraviolet-Visible Sum-Frequency Generation

Drug-membrane interactions play a crucial role in the pharmacology and activity of drugs. The measurement of drug association to lipid membranes has conventionally been measured by fluorescence and other spectroscopic methods. However, a main disadvantage of fluorescence labeling of drugs is that the introduction of fluorophores may change the molecules physical properties, such as charge, hydrophobic or hydrophilic character, and structure. To circumvent these problems, Ultraviolet-Visible Sum Frequency Generation (UV-Vis SFG) has been developed as an ultrasensitive and label-free technique to detect small-molecule drug association to lipid membranes. Four different classes of drugs, a nonsteroidal anti-inflammatory drug (ibuprofen), antibiotic (azithromycin), antifungal (tolnaftate), and local anesthetic (tetracaine), were examined. Drug association was measured on planar supported lipid bilayers (PSLBs) of 1,2-dioleoyl-sn-glycero-3-phophocholine (DOPC). Equilibrium association constants of the drugs were obtained and correlate well to the partition coefficients of the drugs in a liposome membrane-water system. UV-Vis SFG is a powerful and novel technique to directly measure the association of drugs to a single biological membrane without chemical modification.

Prevalence and Distribution of Avian Influenza A(H5N1) Virus Clade Variants in Live Bird Markets of Vietnam, 2011–2013

SUMMARY Active surveillance for avian influenza (AI) viruses in poultry sold at live bird markets (LBMs) was conducted in 44 of 63 provinces throughout Vietnam over two periods from September 2011 to February 2012 and October 2012 to June 2013. The study objectives were to assess the prevalence of avian influenza type A, H5, and H5N1 subtype viruses and characterize the geographical and temporal distribution of H5N1 virus genetic variants across the country. Monthly sampling was conducted in 394 LBMs located in 372 communes. A total of 9790 oropharyngeal swabs from poultry were screened for influenza A virus by real-time reverse-transcriptase PCR. Virus isolation was attempted on all positive samples in embryonated chicken eggs, and the HA1 region of each H5 virus isolate was sequenced. Market prevalence of H5 subtype virus was 32.2% (127/394) over the cumulative 15 mo of surveillance. Phylogenetic analyses indicated that clade 1.1 viruses persisted in the south, whereas three genetically distinct subgroups of clade 2.3.2.1 were found simultaneously in northern, central, and southern Vietnam. Clade 2.3.2.1c viruses first appeared in July 2012 and spread rapidly to the center and south of Vietnam in late 2012, where they were predominant among clade 2.3.2.1 viruses and were detected in both active LBM surveillance and poultry outbreaks. Given the overlapping geographic distribution of clade variants and the antigenic divergence previously described for these clades, current AI poultry vaccines used in Vietnam may require bivalent formulations containing representatives of both clade 1.1 and clade 2.3.2.1 viruses. RESUMEN Prevalencia y distribución de virus variantes de clado de la influenza aviar A H5N1 en mercados de aves vivas en Vietnam, 2011-2013. Se llevó a cabo vigilancia activa para virus de influenza aviar (IA) en las aves que se venden en los mercados de aves vivas en 44 de 63 provincias de Vietnam por dos períodos entre septiembre del 2011 a febrero 2012 y entre octubre del 2012 hasta junio de 2013. Los objetivos del estudio fueron evaluar la prevalencia del virus de la influenza aviar tipo A, H5 y subtipo H5N1 y caracterizar la distribución geográfica y temporal de las variantes genéticas del virus H5N1 en todo el país. Se realizó un muestreo mensual en 394 mercados de aves vivas ubicados en 372 municipios. Un total de 9,790 hisopos orofaríngeos de aves fueron analizados para detectar la presencia de influenza A virus por transcripción reversa y PCR en tiempo real. Se intentó el aislamiento del virus en huevos embrionados de todas las muestras positivas y se secuenció la región de HA1 de cada aislamiento viral H5. La prevalencia en los mercados del subtipo H5 fue del 32.2% (127/394) acumulada durante los 15 meses de vigilancia. Los análisis filogenéticos indican que los virus del clado 1.1 persistieron en el sur, mientras que se encontraron tres subgrupos genéticamente diferentes del clado 2.3.2.1 al mismo tiempo en el norte, en el centro y en el sur de Vietnam. Los virus del clado 2.3.2.1c aparecieron por primera vez en julio de 2012 y se extendieron rápidamente al centro y sur de Vietnam a finales del 2012, donde predominaron dentro de los virus del clado 2.3.2.1 y se detectaron tanto en el muestreo activo de mercados de aves vivas y en los brotes avícolas. Considerando la superposición de la distribución geográfica de los clados variantes y la divergencia antigénica descrita previamente para estos subtipos, las vacunas actuales contra influenza aviar utilizadas en la avicultura de Vietnam pueden requerir formulaciones bivalentes que contengan virus representantes de ambos clados; clado 1.1 y clado 2.3.2.1.

Learning to build quality business relationships in export markets: evidence from Vietnamese exporters

A firms competitive advantage can be created through keeping long-term relationships with customers. To achieve successful long-term relationships, partners have to develop and maintain quality relationships with each other, especially in international markets. In this study, we examine the role of learning orientation in relationship quality between exporters in a transition economy, Vietnam, and their foreign importers. We also investigate the mediating role of exporter ethnocentrism. A test based on a random sample of 297 exporters in Vietnam indicates that learning orientation is a key factor that assists exporters in building quality relationships with their importers. In addition, learning orientation lessens the degree of exporter ethnocentrism, a behaviour which prohibits exporters to build quality relationships with their importers.

Determinants of Learning Performance of Business Students in a Transitional Market.

Purpose – The purpose of this paper is to examine the impacts of instructor capability and learning motivation on learning performance of business students in Vietnam. It also explores the moderating effect of personal development competitiveness on the roles of instructor capability in both learning motivation and learning performance.Design/methodology/approach – Two phases of study were undertaken. A pilot phase was used to preliminary assess the measures and a main survey with a sample of 1,278 undergraduate business students was conducted to validate the measures and to test the models.Findings – Instructor capability was found to have a positive impact on learning motivation and, subsequently, on learning performance. The results further show that the impacts of instructor capability on both learning motivation and learning performance are greater in the group of students which has a higher level of personal development competitiveness.Research limitations/implications – A key limitation of this stu...

The Role of Market and Learning Orientations in Relationship Quality - Evidence from Vietnamese Exporters and Their Foreign Importers

This study examines the roles of market and learning orientations in relationship quality between exporters in transition economies and their foreign importers and subsequently, export performance. A random sample of 283 export firms in Vietnam provides evidence to support the hypothesized main effects. The results further indicate that learning orientation plays a role in building high-quality relationships for both new and mature relationships. However, the impact of market orientation on relationship quality is found only in the new relationship. In addition, firm-ownership structure does not moderate the relationships between learning orientation, market orientation, relationship quality, and export performance.

Enhancing business relationship quality through cultural sensitization

An understanding of and adaptation to differences in culture in foreign countries can help exporters to reduce the distance between parties in an export relationship and enhance the quality of the relationship. This research investigates the impact of 2 cultural factors, namely, exporter cultural sensitivity and exporter ethnocentrism, on business relationship quality between transitioning economy–based exporters and their foreign importers and, subsequently, export performance. Using a systematic sample of 297 exporting firms in Vietnam we find that exporter cultural sensitivity has a positive effect, and ethnocentrism has a negative effect, on relationship quality. Furthermore, relationship quality enhances the performance of exporters.