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• The Factors Affecting the Attachment to Bac Ninh City of Immigrant Workers after the Covid-19 Pandemic

  Dong Thanh Mai, Vu Thi My Hue, Doan Bich Hanh, Nguyen Huy Hoang

  Received: 01-03-2024 / Accepted: 21-06-2024

   Abstract PDF (VIETNAMESE)

  The Covid-19 pandemic has caused many losses in terms of employment, income, health and spirit to labors, especially immigrant workers - a group that has suffered a lot from the pandemic in the Bac Ninh city. Immigrant workers are facing the decision of whether to continue to stay or leave Bac Ninh city. This study aims to evaluate the impact of the Covid-19 epidemic on immigrant workers and measure factors affecting their attachment to Bac Ninh city after the impacts of the Covid-19 pandemic through taking the survey of 250 immigrant lworkers and using Probit regression analysis. Research results show that household registration, length of time living in the immigration area, changes in ejobs and income are the most important factors affecting immigrant lworkers' decision to stick with Bac Ninh city.

• Characterizing Glycoprotein-gene Encoding Sequences of Avian MetapneumovirusFound in Poultry in Northern Vietnam

  Nguyen Van Giap, Cao Thi Bich Phuong, Huynh Thi My Le, Dang Huu Anh, Chu Thi Thanh Huong, Vu Thi Ngoc, Vo Van Hieu, Ta Thi Kim Chung, Le Ba Hiep, Le Thi Trinh, Truong Quang Lam, Nguyen Thi Hoa, Le Thi Luyen

  Received: 05-03-2021 / Accepted: 09-04-2021

   Abstract PDF (VIETNAMESE)

  Avian Metapneumovirus (aMPV) is one of the causative agents of respiratory disease complex in turkeys and chickens, which has been recently detected in Vietnam. Due to its novelty, a few published papers are available on preliminary results, describing the clinical disease, sero- and viral-positivity rates. This study aimed at providing more details about the molecular characterizations of the circulating virus by sequenced and then applied bioinformatics for data mining. Based on the sequence of partial attachment glycoprotein coding gene, 5/5 aMPV strains were classified as subgroup B. Though 5/5 strains belonged to the vaccine-derived lineage, all of them had differences at the nucleotide and amino acid levels compared to the attenuated strain of Nemovac vaccine available in Vietnam.

• Research and Apply Automatic Submerged Arc Welding Technology to Weld Q345B High-Strength Low-Alloy Steel

  Nguyen Huu Huong, Tong Ngoc Tuan

  Received: 04-07-2016 / Accepted: 25-12-2016

   Abstract PDF (VIETNAMESE)

  Based oOn the currentavailableequipments, constructing an experimental model combining with equipment system, attachment and automatic submerged arc welding machine to weld Q345B high-strength low-alloy (HSLA) steel with T-letter shapedjointwith,a thickness of plates isof5 mm and 8 mm,respectively. Based on theoretic research into on automatic submerged arc welding technology, experimental welding,using design ofexperimental designsand,data processing were performed to find out parameters of for welding conditions to serve welding process of Q345B steel. Through the initial survey,fix somewith constantparameters and experimental welding with about input parameterintervals and evaluating output parameters, determining the followingparameters of welding conditionswere determined: welding current Ih≈ 440 Aand,welding speed Vh≈ 19,.6 m/h. With parameters of welding conditions that were determined,combining with technological elementsand specific structure, T-letterjoint that was weldinged toensureproducedgood form, dimension and quality.

• Application of Membrane Filtration to Harvest Microalgae Cultivated from Piggery Wastewater

  Do Khac Uan, Doan Thi Thai Yen, Nguyen Tien Thanh

  Received: 24-02-2016 / Accepted: 20-11-2016

   Abstract PDF (VIETNAMESE)

  Currently, many methods such as filtration, centrifugation, flotation, and flocculation for harvesting algae for biofuel production development have been studied. In this study, application of membrane filtration to harvest microalgae was evaluated in a lab-scale system. The working volume of the system was 1 l. A hollow fiber membrane (with the surface of 0.065 m2, pore size of 0.2 µm) was submerged in the system. During the experiment, the air was supplied to prevent the membrane fouling due to the attachment of the micoralgae on the membrane surface. As a result, when the air intensity increased from 0 to 0.315 l/cm2.min, the flux increased and the transmembrane pressure decreased. When the air intensity was lower than 0.189 l/cm2.min, the flux decreased and the transmembrane pressure increased rapidly. When the air intensity was maintained higher than 0.189 l/cm2.min, the flux and the transmembrane pressure were relatively constant. Operational mode of suction pump should be maintained at 5 min on: 5 min off to keep the flux and the transmembrane pressure stable. During opertation, microalgae concentration significantly affected the flux and the transmembrane pressure. In conclusion, membrane filtration could be applied to harvest the microalgae. During operation, the air intensity should be maintained higher than 0.189 L/cm2.min to help the filtration longer. Membrane filtration could be an effective method for harvesting microalgae.