Cloning, Expression, Purification, and Properties of an Endoglucanase Gene (Glycosyl Hydrolase Family 12) from Aspergillus niger VTCC-F021 in Pichia pastoris

( Thi Hoa Pham ),( Dinh Thi Quyen ),( Ngoc Minh Nghiem ),( Thu Doan Vu ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.10

A gene coding for an endoglucanase (EglA), of the glycosyl hydrolase family 12 and derived from Aspergillus niger VTCC-F021, was cloned and sequenced. The cDNA sequence, 717 bp, and its putative endoglucanase, a 238 aa protein with a predicted molecular mass of 26 kDa and a pI of 4.35, exhibited 98.3-98.7% and 98.3-98.6% identities, respectively, with cDNA sequences and their corresponding endoglucanases from Aspergillus niger strains from the GenBank. The cDNA was overexpressed in Pichia pastoris GS115 under the control of an AOX1 promoter with a level of 1.59 U/ml culture supernatant, after 72 h of growth in a YP medium induced with 1% (v/v) of methanol. The molecular mass of the purified EglA, determined by SDS-PAGE, was 33 kDa, with a specific activity of 100.16 and 19.91 U/mg toward 1% (w/v) of β-glucan and CMC, respectively. Optimal enzymatic activity was noted at a temperature of 55℃ and a pH of 5. The recombinant EglA (rEglA) was stable over a temperature range of 30- 37℃ and at pH range of 3.5-4.5. Metal ions, detergents, and solvents tested indicated a slightly inhibitory effect on rEglA activity. Kinetic constants (K(m), V(max), k(cat), and k(cat)/ K(m)) determined for rEglA with β-glucan as a substrate were 4.04 mg/ml, 102.04 U/mg, 2,040.82 min-1, and 505.05, whereas they were 10.17 mg/ml, 28.99 U/mg, 571.71 min-1, and 57.01 with CMC as a substrate, respectively. The results thus indicate that the rEglA obtained in this study is highly specific toward β-glucan. The biochemical properties of rEglA make it highly valuable for downstream biotechnological applications, including potential use as a feed enzyme.

Isolation and Cytotoxic Potency of Endophytic Fungi Associated with Dysosma difformis, a Study for the Novel Resources of Podophyllotoxin

Hoa Thi Tran,Giang Thu Nguyen,Hong Ha Thi Nguyen,Huyen Thi Tran,Quang Hong Tran,Quang Ho Tran,Ngoc Thi Ninh,Phat Tien Do,Ha Hoang Chu,Ngoc Bich Pham 한국균학회 2022 Mycobiology Vol.50 No.5

Endophytic fungi are promising sources for the production of podophyllotoxin-an important anticancer compound, replacing depleted medical plants. In this study, the endophytes asso- ciated with Dysosma difformis-an ethnomedicinal plant species were isolated to explore novel sources of podophyllotoxin. Fifty-three endophytic fungi were isolated and identified by morphological observation and ITS-based rDNA sequencing, assigning them to 27 genera in 3 divisions. Fusarium was found the most prevalent genus with a colonization frequency of 11.11%, followed by Trametes (9.26%) and Penicillium (7.41%). Phylogenetic trees were constructed for the endophytic fungi community in two collection sites, Ha Giang and Lai Chau, revealing the adaptation of the species to the specific tissues and habitats. Cytotoxic activity of endophytic fungal extracts was investigated on cancer cell lines such as SK-LU-1, HL-60, and HepG2, demonstrating strong anti-cancer activity of six isolates belonging to Penicillium, Trametes, Purpureocillium, Aspergillus, and Ganoderma with IC50 value of lower than 10 mg/mL. The presence of podophyllotoxin was indicated in Penicillium, Trametes, Aspergillus and for the first time in Purpureocillium and Ganoderma via high-performance liquid chromatography, which implied them as a potential source of this anti- cancer compound.

Financial Characteristics effect on Vietnam Small and Medium Enterprises’ Profitability

( Pham Thi Phuong Hoa ),( Rae Soo Park ) 숙명여자대학교 경제경영연구소 2012 기업경제연구 Vol.41 No.1

This paper examines the relationship between financial characteristics of Vietnam SMEs and profitability to find what determinant of financial characteristics impact on SME profitability. Findings showed that liquidity and leverage are negatively related to SME profitability; and turnover, are positively related to SME’s profitability. All three hypotheses are supported. By examining the relationship between these three financial characteristics and SME profitability, this study also contributes to further researches in this field

Control Strategy for Accurate Reactive Power Sharing in Islanded Microgrids

Pham, Xuan Hoa Thi,Le, Toi Thanh The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4

This paper presents a control strategy to enhance the accuracy of reactive power sharing between paralleled three-phase inverters in an islanded microgrid. In this study, the mismatch of power sharing when the line impedances have significant differences between inverters connected to a microgrid has been solved, the accuracy of the reactive power sharing in an islanded microgrid is increased, the voltage droop slope is tuned to compensate for the mismatch of voltage drops across the line impedances by using an enhanced droop controller. The proposed method ensures accurate power sharing even if the microgrid has local loads at the output of the inverters. The control model has been simulated by MATLAB/Simulink with two or three inverters connected in parallel. Simulation results demonstrate the accuracy of the implemented control method. Furthermore, in order to validate the theoretical analysis and simulation results, an experimental setup was built in the laboratory. Results obtained from the experimental setup verify the effectiveness of the proposed method.

SOCIALIZING CUSTOMER FOR CO-CREATING TOURISM VALUE: A MODERATED MEDIATION MODEL OF CUSTOMER READINESS AND PRODUCT INVOLVEMENT

Hoa Pham Thi,HsiuJu Rebecca Yen,Chen-ya Wang 글로벌지식마케팅경영학회 2018 Global Marketing Conference Vol.2018 No.07

Introduction Customer co-creation – customers‘ active participation and interaction with the company during their consumption processes, has gained increasing attention in tourism industry (Bertella, 2014; Chathoth et al., 2016; Campos, 2015). For example, Finnair and Helsinki airport invited passengers to workshop for co-developing new service concepts to improve passenger experience (Loukas, 2013). Despite of the increasing enthusiasm at the firm‘s side, customers do not necessarily share the mindset and feel ready for cocreation. The success of value co-creation greatly depends on continuous collaboration between customers and companies (Chathoth et al., 2013), making knowledge regarding customers‘ engagement in value co-creation essential. However, insufficient research attention has been devoted to theorize and empirically investigate the drivers of cocreation behavior in tourism (Grissemann & Stokburger-Sauer, 2012). To address this research gap, we draw on the organizational socialization theory (Van Maanen & Schein, 1979) to propose and empirically test customer education as driving factor for tourists‘ co-creation behavior during their tours. Additionally, we propose customer readiness as a mechanism mediating the effect of customer education on value co-creation behavior, while such effect should depend on tourists‘ involvement with tourism. Background and hypotheses development Organizational socialization refers to the process by which a newcomer gradually absorbs values, abilities, expected behaviors, and necessary social knowledge for assuming an organizational role and for participating as an organizational member (Louis, 1980, p. 229–230). Similar to the organizational socialization perspective, customer socialization characterizes how customers develop skills, knowledge, and attitude relevant to the marketplace (Ward, 1975), which offers a lens to explain how service providers can assist customers and behave as effective co-creators in the service system (Claycomb, Lengnick-Hall, and Inks, 2001). B?ttgen et al (2012) demonstrated that customer socialization by training tactic has more important influence on consistent beliefs of service quality than prior reinforcement experiences, which engenders co-production motivation, in turn, leading to coproduction behavior as distal outcome of the socialization tactic. Previous studies suggest favorable customer outcomes to derive from the provision of customer education (Damali et al., 2016). Thus, this study proposed customer education as a socializing tactic, which is mediated by customer readiness for co-creation, to determine tourists co-creation behavior. The concept of co-creation has gained increasing attention in tourism literature, which is often described as the tourist‘s active participation, engagement and interaction during the consumption experience (e.g., Bertella, 2014; So et al., 2014). As Prahalad and Ramaswamy (2004, p. 8) stated, cocreation is ―the joint creation of value by the company and the customer, allowing the customer to co-construct the service experience to suit her context‖. Indeed, creating a favorable, memorable experience involves not only the service providers but also the tourism customers because customers are always the value co-creator (Vargo and Lusch, 2004). Challagalla and colleagues (2009) posit that firms can reach out to contact the customers to provide service after a sale is complete, rather than respond upon the customer‘s requests. In specific, Challagalla and et al. (2009) suggest the proactive service initiatives to consist of three dimensions, namely proactive prevention, proactive education, and proactive feedback seeking. In this study, the three key forms of proactive post-sales services proposed by Challagalla et al. (2009) provides a foundation that helps us to conceive customer co-creation behavior and define the dimensions underlying customer co-creation behavior of tourism services. Customer education, according to Meer (1984), involves learning activities that are organized and sustained by a firm to impart attitudes, knowledge or skills to customers or potential customers. Meanwhile, customer co-creation readiness (CCR) as a customer‘s condition or state in which he/she feels prepared to collaborate with service provider in value co-creation behavior, indicated by role clarity, ability and motivation to co-create (Meuter et al., 2005). Proper socialization process helps customers understand the product or service process as well as their role in performing service tasks, which not only could prevent customer‘s disruptive behaviors during the service process but also facilitate service flow and productivity (Rollag, 2012). Taken together, we propose the following hypotheses: H1: customer education will have a positive effect on customer co-creation behavior H2: Customer co-creation readiness will mediate the positive effect of customer education on customer co-creation behavior. Further, we postulate that tourist‘s product involvement is a boundary condition that constrains the positive effect of customer socialization. Socialization process does not always have much weight on tourists because the influence of socialization on each individual depends on tourists‘ individual characteristics (Van Maanen & Schein, 1979). Some tourists are highly interested in traveling whereas some consider traveling as a dessert in their meal. In line of this sense, we suggest the following hypothesis: H3: Product involvement will negatively moderate the mediation effect of customer co-creation readiness on co-creation behavior. Methodology The survey was posted on several well-known travel forums and referral networks. After eliminating invalid surveys, the authors obtain 300 valid questionnaires. Table 1 presents the sample characteristics. Customer education are measured by four items adapted from Bell and Eisingerich (2007). Product involvement depicts a customer‘s inherent needs, values, and interest towards tourism and is measured by ten items from Zaichkowsky (1985, 1994). Customer co-creation readiness is measured as a reflective first-order and reflective second-order construct by three dimensions: role clarity, ability, and motivation with 12 items adapted by Dellande et al. (2004) and Meuter et al. (2005). Customer co-creation behavior is measured as a reflective second order and reflective first order construct constituted by three dimensions of co-creation behavior with 12 items developed based on the review of concerns in the pre-site, on-site and post-site from several famous travel agencies. Results Measurement validation of constructs from construct reliability, convergent validity to discriminant validity were examined; and the results are provided in the table 2, indicating measurement validation requirements are satisfactory. Then, hypotheses testing was performed. In each analysis, we control variables, including customer gender, previous transaction experience with the travel agency (EP), and social desirability (SD), which are expected to have potential influence on co-creation behavior. H1 predicts a positive relationship between customer education and value co-creation. In support of H1, the analysis shows that customer education positively relates to co-creation of customers (β = 0.272, p = 0.043, R2adjusted= 0.292). Gender (β =-0.170, p<0.001) and SD (β =0.141, p=0.011) are negatively and positively related to customer co-creation behavior respectively. To test the mediating effect of customer readiness on the relationship between customer education and customer co-creation behavior, we used the PROCESS Macro (model 4) developed by Hayes‘s (2013) and estimated the effects with a bootstrap sample of 5000 cases. The indirect effect test indicates that customer education had a significantly positive effect on customer co-creation via the mediation of customer readiness for co-creation (0.312; 95% bootstrap CI [0.157, 0.517]) because the confidence interval did not include zero. The results support H2. Gender also has a significant effect on customer co-creation (β =-0.189, p <0.05). H3 postulated that product involvement will moderate the mediation effect of customer readiness. We used the PROCESS macro model 8 established by Hayes (2013) to test the moderated mediation. The conditional indirect effect test shows that customer readiness significantly mediates the influence of customer education on customer co-creation behavior, regardless of the level of product involvement (zero was not included in the confidence intervals). Nonetheless, customer education on customer co-creation behavior via customer readiness is significant and stronger in low level of product involvement (0.281; 95% bootstrap CI [0.186, 0.398]) but weaker in high level of product involvement (0.128; 95% bootstrap CI [0.029, 0.256]). Therefore, H3 is supported. Among the controlled variables, gender is the only significant predictor of customer co-creation behavior (β =-0.158, p<0.05). In a summary of dominant results of control variables, gender is significant in all three of the tested hypotheses; particularly, female shows a higher level of co-creation behavior than male. Conclusion we introduced organizational socialization theory to the literature on co-creation of tourism context and explored the effect of firms‘ education effort to socialize customers in co-creation activities. We found customer education as a socialization tactic and then conducting an empirical study by collecting data from several travel agencies to investigate the effect of firms‘ socialization tactic on customer co-creation. The results suggest that customer education could promote customer co-creation through customer readiness as a mediator. We also investigated whether the effect of socialization tactic differs on the different levels of product involvement. The results show that customers with high involvement were less influenced by customer education than those with low involvement.

Facile synthesis of multifunctional Ag/Fe3O4-CS nanocomposites for antibacterial and hyperthermic applications

Ngoan Thi Nguyen,Dai Lam Tran,Duc Cuong Nguyen,Thai Loc Nguyen,Thi Cham Ba,Binh Hai Nguyen,Thi Duong Ba,Nam Hong Pham,Dzung Tuan Nguyen,Thai Hoa Tran,Gia Dien Pham 한국물리학회 2015 Current Applied Physics Vol.15 No.11

Nanocomposites containing two or more functional constituents are attractive candidates for advanced nanomaterials. In this study, multifunctional Ag/Fe3O4-CS nanocomposites were successfully prepared, using chitosan as a stabilizing and cross-linking agent. The as-synthesized nanocomposites were characterized by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), UVevisible spectrophotometer (UVeVis) and vibrating sample magnetometer (VSM). The results demonstrated that Ag/Fe3O4-CS composite nanoparticles (NPs) were composed of parent components, Fe3O4 and Ag NPs, which were uniformly dispersed in the chitosan matrix. The hybrid NPs exhibited strong antibacterial property against Pseudomonas aeruginosa. With high magnetization value (67 emu/g), the synthesized Ag/Fe3O4-CS composite can be easily separated or recycled in potential biomedical applications. Furthermore, the results showed that the multicomponent hybrid nanostructures appeared to be the promising material for local hyperthermia, which can be used as thermoseeds for localized hyperthermia treatment of cancers.

Landscape Function and Tourism Industry: A Case Study of Moc Chau Plateau, Vietnam

LE, Hoa Thi Thu,TONG, Binh Thanh,VU, Ngoc Thi Minh,HO, Luu Si,PHAM, Thang Viet,TRINH, Hang Thi Thu Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.12

Tourism is not only a cultural service but also a resource consuming industry. Landscape function framework is a powerful tool to show the relationship between nature and people. This study collects 50 documents around the world to analyze the relationship between the 4 functional groups of the landscape (regulatory functions, production and supply functions, resident functions, information and entertainment functions) and the tourism industry. On that basis, we created an establishment for practical contact analysis of the goods and services of the landscape for tourism development in Moc Chau plateau, Vietnam. Research results show that tourism is an economic sector that benefits from the landscape and has a clear resource orientation. Moc Chau plateau has rich tourism resources and has the conditions to develop various types of tourism, especially cultural tourism based on community and resort tourism. The two cultural functions and the providing functions are the two most important functional groups for the tourism development of Moc Chau district, bringing the two most important tourism icons for Moc Chau, a green steppe, cool milk benevolent and also a district rich in national culture. From these conclusions, the authors give recommendations and notable points about landscapes in the tourism industry, especially in places with topography like Moc Chau.

Control Strategy for Accurate Reactive Power Sharing in Islanded Microgrids

Xuan Hoa Thi Pham,Toi Thanh Le 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4

This paper presents a control strategy to enhance the accuracy of reactive power sharing between paralleled three-phaseinverters in an islanded microgrid. In this study, the mismatch of power sharing when the line impedances have significantdifferences between inverters connected to a microgrid has been solved, the accuracy of the reactive power sharing in an islandedmicrogrid is increased, the voltage droop slope is tuned to compensate for the mismatch of voltage drops across the lineimpedances by using an enhanced droop controller. The proposed method ensures accurate power sharing even if the microgridhas local loads at the output of the inverters. The control model has been simulated by MATLAB/Simulink with two or threeinverters connected in parallel. Simulation results demonstrate the accuracy of the implemented control method. Furthermore, inorder to validate the theoretical analysis and simulation results, an experimental setup was built in the laboratory. Resultsobtained from the experimental setup verify the effectiveness of the proposed method.

The Relationship between Foreign Capital Inflows and Economic Growth: Empirical Evidence from Vietnam

Cung Huu NGUYEN,Thi Truc Quynh PHAM,Thi Hoa TRAN,Thi Hoa NGUYEN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.11

Foreign capital inflows play an essential role in each country’s socio-economic growth, particularly for undeveloped and developing countries where capital accumulation is limited in the early stages of development, and Vietnam is no exception. The purpose of this article is to examine the impact of foreign capital inflows on economic growth in Vietnam. The empirical method employed secondary time-series data set during the period 1995–2018 to determine the impact of FDI, foreign aid, foreign loans, and exports on economic growth in Vietnam by using a linear approach. For this study, data was collected from the World Bank and relevant agencies in Vietnam. The results show that FDI (net inflows), foreign aid, foreign loans, exports, and GDP (current), have a positive effect at a 1% significance level on economic growth. Rather, an increase in FDI (net inflows), foreign aid, foreign loans, exports has beneficial effects on the Vietnamese economy in the study period. Based on the findings of this study, the article proposes several important policy implications for Vietnam in maintaining a high rate of economic growth via the contribution of FDI inflows, foreign aid, foreign loans, and exports.

Impact of Community Attachment and Resident's Support on Destination Sustainability: Evidence from Spiritual and Community Destination in Vietnam

THAN, Trong Thuy,KIEU, Thi Phuong Hoa,PHAM, Thi Anh Duong,HOANG, Thi Cam Van,TRAN, Thi Hau,NGUYEN, Huu Doan,DAO, Trung Kien Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.8

This study investigates the influence of community involvement on the destination sustainability for community destinations and spiritual destinations in Vietnam. Community involvement is measured by two constructs, which are community attachment and residents' support. A structural questionnaire consisting of 41 observation variables measured on a 5-point Likert scale was used to survey households who live in a spiritual destination in An Giang province and three community destinations in Lang Son province with the help of local tour guides and Youth Union. 168 out of 200 responses collected were valid for multivariate data analysis. The results of confirmatory factor analysis (CFA) and structural equation modeling (SEM) reveal three main findings. Firstly, community attachment has a direct effect on both perceived benefits and destination sustainability. Secondly, while residents' support has a direct effect on perceived benefits, it indirectly affects destination sustainability. Finally, community destinations have a higher level of sustainability than the spiritual destination. Based on those findings, this study proposed three suggestions for local authorities, policymakers, and residents to improve the sustainable development of their local tourism destinations, including (1) diversifying local tourism products, (2) encouraging the community participation in tourism development programs, and (3) increasing in the expected benefits in local tourism development policies.