Binding Energy of Exciton in Quantum Dots with the Central-cell Correction Depending on the Dot Sizes

The binding energy of exciton in quantum dots with a parabolic confinement potential was calculated by variational methods beyond the Kohn-Luttinger effective mass theory, when the central-cell correction was taken into account.We have assumed that a short range potential with two parameters for strength and range for exciton, representing the center-cell effect also depends on dot size. Our result is in good agreement with experiment

The Distribution of Microplastics in Beach Sand in Tien Giang Province and Vung Tau City, Vietnam

Microplastics threaten the ecosystem because of undesirable properties such as non-biodegradability, easy-to-absorb persistant organic compounds, etc. They are found worldwide in marine, fresh water and beach sand environments. In this study, microplastics in beach sand samples from two sites in Tien Giang province and two sites in Vung Tau city were investigated. The results showed that the microplastics amount was 0 to 295 pieces/kg dry sand and they mainly distributed near estuarine areas. Microplastics were more prevalent at bathing sites than non-bathing sites. In Tien Giang fragments were the most dominant among the three types of shapes (fragments, fibers, granules) at 60.2%. In Vung Tau granules were most prevalent at 71.7%. The composition of the plastics was confirmed by Fourier-transform infrared spectroscopy. It was revealed that PE, PP and PS were the main types of plastics found in the sampling sites.

Learning to be Researchers: A Study of Pedagogical Students in Hanoi, Vietnam

Doing research in colleges and universities is an essential activity since it may provide students a good basis to become professional researcher and teacher in the future. However, few students in Vietnam can recognize the importance of research activities or possess an adequate background of knowledge to participate in these activities, and additionally, the obligatory course of Research Methodology offered in many universities cannot bring enough understanding in doing research to students. This study, thus, aims at investigating the effects of Research Methodology courses in both of their good and bad sides) on students at a pedagogical university. The study also attempts to survey the attitude of those students toward the activity of doing research and the impact of the attitude on their process of learning to be researcher

Application of value chain analysis in understanding the losses and wastes of cassava in Vietnam

To reduce post-harvest losses and foster development of cassava, it is necessary to evaluate the full range of activities required to bring fresh cassava root through different stages of production, processing, and marketing until it reaches the end-user. A Value Chain Analysis (VCA) provides the approach for such an understanding in that it is a process of tracing a product’s flow from the point of production to the point of consumption along with tracing the roles and relationships of different actors and stakeholder at different points in the value chain. This paper provides an overview of the main cassava value chains in Vietnam, and the extent and nature of losses and wastes in those value chains

On the Information Problem of DNA in the Denaturation Process

The information problem of DNA in the denaturation process was studied by the relationship between entropy and information. Using the previous PB’s (Peyrard and Bishop) numerical results obtained from their microscopic arharmonic model of DNA, we propose a new effective simple model to calculate DNA information. A shape change of information at the denaturation phase transition point was found and discussed

Molecular identification of three Habenaria species from Binh Chau-Phuoc Buu Nature Reserve, Vietnam

The present provides molecular data for species of Habenaria diphylla (Nimmo) Dalzell, H. khasiana Hook.f. and H. rostellifera Rchb.f. collected from Binh Chau-Phuoc Buu Nature Reserve, Vietnam for the first time. Along with other DNA sequences from GenBank database, the phylogenetic trees for Habenaria species from Vietnam have been established

MODIFICATION OF GRAPHENE OXIDE BY CURCUMIN AND APPLICATION IN POLYURETHANE COATING

Curcumin modified graphene oxide (GO-CR) was prepared using adsorption method and polyurethane (PU) coating containing 0.3 wt% GO-CR was prepared on carbon steel. Synthesized GO-CR was characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and zeta potential measurement. Corrosion protection property of polyurethane coating containing GO-CR was evaluated and compared with blank polyurethane coating and coating containing GO by electrochemical impedance spectroscopy. The results showed that GO-CR has layer structure like GO with lower crystallinity. In GO-CR structure curcumin was attached on GO surface. The presence of curcumin on GO-CR surface provided corrosion inhibition action for PU coating and also improved the dispersion of GO in PU coating

Viral Metagenomic Analysis of Cerebrospinal Fluid from Patients with Acute Central Nervous System Infections of Unknown Origin, Vietnam.

Central nervous system (CNS) infection is a serious neurologic condition, although the etiology remains unknown in >50% of patients. We used metagenomic next-generation sequencing to detect viruses in 204 cerebrospinal fluid (CSF) samples from patients with acute CNS infection who were enrolled from Vietnam hospitals during 2012-2016. We detected 8 viral species in 107/204 (52.4%) of CSF samples. After virus-specific PCR confirmation, the detection rate was lowered to 30/204 (14.7%). Enteroviruses were the most common viruses detected (n = 23), followed by hepatitis B virus (3), HIV (2), molluscum contagiosum virus (1), and gemycircularvirus (1). Analysis of enterovirus sequences revealed the predominance of echovirus 30 (9). Phylogenetically, the echovirus 30 strains belonged to genogroup V and VIIb. Our results expanded knowledge about the clinical burden of enterovirus in Vietnam and underscore the challenges of identifying a plausible viral pathogen in CSF of patients with CNS infections

Age-time-specific transmission of hand-foot-and-mouth disease enterovirus serotypes in Vietnam: a catalytic model with maternal immunity

Hand, foot and mouth disease (HFMD) is highly prevalent in the Asia Pacific region, particularly in Vietnam. To develop effective interventions and efficient vaccination programs, we inferred the age-time-specific transmission patterns of HFMD serotypes enterovirus A71 (EV-A71), coxsackievirus A6 (CV-A6), coxsackievirus A10 (CV-A10), coxsackievirus A16 (CV-A16) in Ho Chi Minh City, Vietnam from a case data collected during 2013–2018 and a serological survey data collected in 2015 and 2017. We proposed a catalytic model framework with good adaptability to incorporate maternal immunity using various mathematical functions. Our results indicate the high-level transmission of CV-A6 and CV-A10 which is not obvious in the case data, due to the variation of disease severity across serotypes. Our results provide statistical evidence supporting the strong association between severe illness and CV-A6 and EV-A71 infections. The HFMD dynamic pattern presents a cyclical pattern with large outbreaks followed by a decline in subsequent years. Additionally, we identify the age group with highest risk of infection as 1-2 years and emphasise the risk of future outbreaks as over 50% of children aged 6-7 years were estimated to be susceptible to CV-A16 and EV-A71. Our study highlights the importance of multivalent vaccines and active surveillance for different serotypes, supports early vaccination prior to 1 year old, and points out the potential utility for vaccinating children older than 5 years old in Vietnam