Synthesis and characterization of lactose and lactulose derived oligosaccharides by glucansucrase and trans-sialidase enzymes

Human milk oligosaccharides (hMOS) have an essential role in infants’ health by stimulating growth of health-beneficial gut bacteria for the human host. These hMOS also directly reduce pathogenic microbial infections by serving as antiadhesives against pathogenic microbes, and stimulating immune responses. Many babies have limited access to human milk, and alternative sources for hMOS are not available in nature. Infant formula with the commercial prebiotics lack pathogen exclusion and immune and barrier modulating effects exerted by hMOS. Development of efficient routes for synthesis of hMOS or structurally/functionally effective mimics is currently focus of attention. At present, whole cell biosynthetic routes and single/multiple enzyme biocatalytic systems for synthesis of hMOS (mimics) are studied. In this project, the glucansucrases Gtf180-ΔN and GtfA-ΔN from Lactobacillus reuteri were used to glucosylate lactose or GOS. The mixture of glucosylated lactose derivatives obtained showed selective effects on growth of various gut bacteria, including lactobacilli, bifidobacteria and commensal bacteria. Mutational analysis of Gtf180-ΔN revealed that three amino acid residues (N1029, W1065 and Q1140) play important roles in determining linkage specificity in lactose trans-glycosylation. Finally, trans-sialidase from Trypanosoma cruzi was used to transfer sialic acid to mixtures of glucosylated-lactose, galactosylated-lactulose and galacto-oligosaccharide (Vivinal GOS) molecules. The newly synthesized galactose-containing oligosaccharides and sialylated oligosaccharides hold strong potential for further applications as hMOS mimics. Glucansucrase and trans-sialidase enzymes are promising tools as biocatalysts for efficient synthesis of new functional oligosaccharides

FOSTERING STUDENTS’ EXPERIENCES IN ENGLISH WRITING WITH MICROBLOGGING IN TWITTER

Twitter and Microblogging are two separate entities but completes each other. Both of them can be used as language learning tools and their potential has been proved by several scholars. This study tries to examine students’ experiences in integrating microblogging with twitter. It is also study about the beneficial roles of microblogging with Twitter in language learning, its relation to writing, and its appropriateness in language learning. This study employs a qualitative research methodology, and case study as its research design. Semi-structured interviews and questionnaires were employed in this study to find out about participants' views about microblogging and Twitter. From this study, it can be concluded that the participants of the study underwent various experiences during the implementation of microblogging with Twitter. They also felt that microblogging with Twitter at some point advantages them to systematically arrange their ideas, and allows them to choose appropriate diction of their ideas. They also stated that Twitter can be an appropriate means in language learning, especially in English writing

Essays on the Missing Middle

The missing middle refers to the empirical fact that most employment in developing countries is located in either small-sized or large-sized firms. In this thesis,we investigated the missing middle phenomenon in a developing country, Vietnam. The first chapter consists of an introduction. The second chapter provides an overall picture of related literature. The third chapter focuses on the development of a theoretical model designed to capture the effect of corruption on the missing-middle formulation. The fourth chapter provides empirical evidence on the existence of a distinct distribution of firm size in Vietnam and some insights into the underlying mechanism of the phenomenon, focusing on corruption and productivity. The fifth chapter focuses on the industry efficiency score. In general, the fourth chapter is empirically oriented, whereas the third and fifth chapters are theoretically oriented. In particular, in the third chapter, we develop a theoretical model to capture an effect of corruption in the development of firms. The model incorporates the increasing costs of large-sized firms, compared to smaller ones. This model shows the firm size distribution (FSD) normally observed in developing economies along a continuum of infinitesimal firms in the market. In the fourth chapter, we discuss the empirical relationship between firm size and production efficiency, inefficiencies associated with scale, and the relationship between firm size and the likelihood of paying bribes, using firm level data from Vietnam. Our analysis indicates that middle-sized firms production efficiencies tend to be lower than the efficiencies in small-sized or large-sized firms in most manufacturing industries. In addition, the least-efficient firm size differs across sectors, indicating the necessity of sector-by-sector analyses to study the underlying mechanisms of the missing-middle phenomenon. Moreover, our results show that as firm size increases, the likelihood of paying bribes also increases. This finding, together with our productivity analysis showing that small sized firms produce more efficiently compared to middle- or large-sized firms, indicates that corruption can be one of the reasons for firms to decide not to grow. We analyzed production efficiency at the aggregate level and provide an approximation proposition that simplifies the computation and interpretation of various industry inefficiency measures proposed in the literature. Moreover, we extended the proposed framework to the meta-technology approach. We found a difference between the group-frontiers and the meta-frontiers. In addition, the meta-technology efficiency (MTE) scores were highest for small-sized firms, in particular, firms with fewer than 50 employees. This finding confirms the differences in the characteristics of firms operating environment across size groups

BENEFITTING HIGHER EDUCATION STUDENTS WITH DIGITAL GAMES IN LANGUAGE LEARNING

There has been an abundant raise in recent years in the concern in using digital games for language learning. Additionally, gaming plays an important role in the everyday lives of youngsters and young adults in developed countries. It is a considerable option for teacher to adapt gaming into language learning since gaming itself became a habit that will easily be adopted into learning. This study will examine gaming opportunities in language learning, and how higher education students benefitting from that. It will employ quantitative research that uses Structured Interview and Online Questionnaire as research Instruments. By the end of the study, higher education students found out that digital game is an easy media to implement in language learning due to their familiarity to digital games. The implementation of digital games excites the students in learning English, and makes a conducive learning situation

Impacts of credit rating changes on stock returns

This paper studies the impact of credit ratings issued by CIC, a Vietnamese local rating agency, on stock returns of listed companies on the Vietnamese stock exchanges in the period of 2007-2010. The findings of the study confirm the assertions of the previous researches by Holthausen and Leftwich (1986), Hand, Holthausen and Leftwich (1992), Chan and Poor (2008). Specifically, CIC’s credit ratings slightly affect the stock prices of the listed firms, an evidence supporting CIC’s role and its rating quality to a certain extent. This paper also confirms semi-strong form of the Vietnamese stock market efficiency

The integration ofcredit default swapmarkets in the pre andpost-subprime crisis incommon stochastic trends

It was evident that credit default swap (CDS) spreads have been highly correlated during the recent financial crisis. Motivated by this evidence, this study attempts to investigate the extent to which CDS markets across regions, maturities and credit ratings have integrated more in crisis. By applying the Panel Analysis of Non-stationarity in Idiosyncratic and Common components method (PANIC) developed by Bai and Ng (2004), we observe a potential shift in CDS integration between the pre- and post-Lehman collapse period, indicating that the system of CDS spreads is tied to a long-run equilibrium path. This finding contributes to a credit risk management task and also coincides with the missions of Basel III since the more integrated CDS markets could result in correlated default, credit contagion and simultaneous downgrading in the future

FIELD TEST ON CLEANING OF OIL POLLUTION ON NHATRANG BEACH OF VIETNAM

Joint Research on Environmental Science and Technology for the Eart