Development of a Filament Extruder Using Flow Theory with the Newtonian Fluid Assumption

This article presents an investigation of the flow characteristics of the polymer melt in a single-screw extruder and the design of a filament extruder to verify the above theory. The flow characteristics of the polymer melt in a single-screw extruder are likable to that of a viscous liquid between two infinitely parallel sheets, one moving and the other stationary. An integrated flow equation was then found for a case when the viscosity of a liquid remains constant in an isothermal extrusion. These flow behavior theories were then verified via the design and fabrication of a filament extruder for 3D printers

Development of a Filament Extruder Using Flow Theory with the Newtonian Fluid Assumption

This article presents an investigation of the flow characteristics of the polymer melt in a single-screw extruder and the design of a filament extruder to verify the above theory. The flow characteristics of the polymer melt in a single-screw extruder are likable to that of a viscous liquid between two infinitely parallel sheets, one moving and the other stationary. An integrated flow equation was then found for a case when the viscosity of a liquid remains constant in an isothermal extrusion. These flow behavior theories were then verified via the design and fabrication of a filament extruder for 3D printers

INVESTIGATING THE IMPACT OF PEER FFEDBACK AND TEACHER FEEDBACK USING GOOGLE DOCS ON EFL STUDENTS’ WRITING PERFORMANCE

Online written corrective feedback via Google Docs, in recent years, has been used and brought about positive outcomes in different teaching contexts. In this light, this study was conducted to examine the different effects between teacher feedback using Google Docs and the combined peer feedback and teacher feedback using Google Docs on EFL high school students’ performance in writing paragraphs. The study also attempted to gain insights into students’ attitudes towards the effect of peer feedback and teacher feedback using Google Docs on their paragraph writing. In this study, a mixed research method was employed; both quantitative and qualitative data were collected. Twenty two grade 11 students in a high school in the Mekong Delta of Vietnam were selected as participants. They were assigned to two groups of treatment: the experimental group, receiving both peer feedback and teacher feedback using Google Docs and the control group who only received teacher feedback using Google Docs. Participants completed two writing tasks; each of them included first draft, second draft and final draft. Prior to the study, students from the experimental group received a face-to-face training on giving peer feedback. Data were collected from six drafts of two writing tasks, three drafts for one task, and interviews at the end of the study. Results indicated that participants who received teacher feedback in the control group performed their paragraph writing better than those receiving both peer feedback and teacher feedback using Google Docs in the experimental group after the study. Also, participants in both groups improved their writing performance in their revised drafts. From the interviews, results showed participants’ positive attitudes towards the impact of peer feedback and teacher feedback using Google Docs on their paragraph writing.   Article visualizations

Experimental Study on the Use of the Modifying Agent for Expansive Soil Stabilization: Mockup Test on a Case Study

To improve the soft grounds, soil stabilization has been used widely in many tropical countries including Vietnam. This paper presents the experimental study on the use of the modifying agent for expansive soil stabilization. A real-scale one-kilometer rural road was used for the experimental test. It was divided into four parts, and each part was subjected to different stabilization tests. The specimens extracted from every quarter were denominated as Q1 (soil + cement), Q2 (soil + cement + fly ash), Q3 (soil + cement + fly ash + modifying agent) and Q4 (soil + cement + modifying agent). The assessment test showed that specimen Q1 yielded the highest water absorption percentage after 24 hours and 72 hours of soaking. The longer the soaking time, the more water diffusion occurred at specimens Q1 and Q2 rather than at specimens Q3 and Q4. When subjected to the unconfined compressive and indirect tensile tests, specimens Q1 and Q3 yielded the lowest and highest strength, respectively. The use of the modifying agent in the specimens Q3 and Q4 has improved noticeably unconfined compressive strength, indirect tensile strength, and water stability compared to the specimens Q1 and Q2. However, ettringite-based sulfate heaving might be exhibited with the use of fly ash, this may cause damage to the overlying pavement structure in the long term. Therefore, to improve the expansive soil stabilization using the modifying agent, it is recommended to use the constituent materials in specimen Q4 rather than in Q3

Genetic profiling of Vietnamese population from large-scale genomic analysis of non-invasive prenatal testing data

The under-representation of several ethnic groups in existing genetic databases and studies have undermined our understanding of the genetic variations and associated traits or diseases in many populations. Cost and technology limitations remain the challenges in performing large-scale genome sequencing projects in many developing countries, including Vietnam. As one of the most rapidly adopted genetic tests, non-invasive prenatal testing (NIPT) data offers an alternative untapped resource for genetic studies. Here we performed a large-scale genomic analysis of 2683 pregnant Vietnamese women using their NIPT data and identified a comprehensive set of 8,054,515 single-nucleotide polymorphisms, among which 8.2% were new to the Vietnamese population. Our study also revealed 24,487 disease-associated genetic variants and their allele frequency distribution, especially 5 pathogenic variants for prevalent genetic disorders in Vietnam. We also observed major discrepancies in the allele frequency distribution of disease-associated genetic variants between the Vietnamese and other populations, thus highlighting a need for genome-wide association studies dedicated to the Vietnamese population. The resulted database of Vietnamese genetic variants, their allele frequency distribution, and their associated diseases presents a valuable resource for future genetic studies

The clinical features and genomic epidemiology of carbapenem-resistant Acinetobacter baumannii infections at a tertiary hospital in Vietnam

ABSTRACT: Objectives: To characterise the clinical features of Acinetobacter baumannii infections and investigate the phylogenetic structure and transmission dynamics of A. baumannii in Vietnam. Methods: Between 2019 and 2020, a surveillance of A. baumannii (AB) infections was conducted at a tertiary hospital in Ho Chi Minh City, Vietnam. Risk factors for in-hospital mortality were analysed using logistic regressions. Whole-genome sequence data were used to characterise genomic species, sequence types (STs), antimicrobial resistance genes, surface antigens, and phylogenetic relatedness of AB isolates. Results: Eighty-four patients with AB infections were enrolled in the study, 96% of whom were hospital-acquired. Half of the AB isolates were identified from ICU-admitted patients, while the remaining isolates were from non-ICU patients. The overall in-hospital mortality was 56%, with associated risk factors including advanced age, ICU stay, exposure to mechanical ventilation/central venous catheterization, pneumonia as source of AB infection, prior use of linezolid/aminoglycosides, and AB treatment with colistin-based therapy. Nearly 91% of isolates were carbapenem-resistant; 92% were multidrug-resistant; and 6% were colistin-resistant. ST2, ST571, and ST16 were the three dominant carbapenem-resistant A. baumannii (CRAB) genotypes, exhibiting distinct AMR gene profiles. Phylogenetic analysis of CRAB ST2 isolates together with previously published ST2 collection provided evidence of intra- and inter-hospital transmission of this clone. Conclusions: Our study highlights a high prevalence of carbapenem resistance and multidrug resistance in A. baumannii and elucidates the spread of CRAB within and between hospitals. Strengthening infection control measures and routine genomic surveillance are crucial to reducing the spread of CRAB and detecting novel pan-drug-resistant variants in a timely fashion