Northern Part Of Vietnam Research Articles

Isolation and identification of the <i>Serratia marcescens</i> causing septicemia in the silkworms from Yen Bai province and prevention measures

In Yen Bai (Northern Viet Nam), sericulture is an important part of agriculture. However, bacterial diseases often cause severe economic loss in sericulture. The results of this research are the first to use a combination of biochemical identification methods and sequencing of the 16S rRNA gene region to diagnose and determine the origin of the pathogen causing septicemia in silkworms collected from Yen Bai province. From the collected silkworm samples with septicemia, a strain of Serratia marcescens bacteria was isolated with morphological characteristics, and typical basic biochemical test. Additionally, the 16S rRNA gene region of the bacterial strain S. marcescens was sequenced. Research results showed that the MD2-16-27F bacterial strain has 99.63% similarity with the S. marcescens strain JW-CZ2. Research on preventing this bacterium shows that the disinfection solution, which contains the active ingredients of trichloroisocyanuric acid (0.0008 mol), formaldehyde (0.0059 mol), calcium hypochloride (0.0031 mol) and alcohol (0.137 mol), effectively prevented the growth of this bacterium after exposed to it for 30 minutes at a temperature of 24-25oC. Antibiotic active ingredients, Norfloxacin (10 μg/l) and Doxycycline (30 μg/l), were effective in preventing S. marcescens bacterium with high sensitivity level; the antibacterial ring diameter of Doxycycline was 31 mm and that of Norfloxacin was 25 mm. The results of this study can be applied to the general prevention of septicemia in silkworms caused by S. marcescens bacteria in the Northern part of Vietnam, particularly in Yen Bai in particular and the North of our country in general.

Characterization and thermal behavior of some types of kaolin of different origin from Northern Vietnam

Kaolin (mainly composed of kaolinite, whose chemical formula is Al2Si2O5(OH)4), serves as a versatile raw material widely used in various industries including production of ceramics, paper, paints, cosmetics, pneumatics, building materials, and hazardous waste storage. In the northern part of Vietnam, due to favorable geological conditions, there are diverse deposits of high quality kaolin of different origin and scale. Decades of research indicate the diversity of kaolin sources in the region, with special attention paid to hydrothermally altered and exchange types of kaolin, the formation of which is associated with complex processes of weathering, hydrothermal alteration and reprecipitation. The aim of this study was to characterize three different types of kaolin derived from different sources in Northern Vietnam (from weathered pegmatites, weathered felsic effusives, and hydrothermal-metasomatic altered rocks). The main focus was to analyze the thermal behavior of these samples during calcination in the temperature range from 300 °C to 1,100 °C. The comprehensive characterization was performed by X-ray diffraction (XRD), FT-IR spectroscopy (FT-IR), thermal analysis (thermogravimetry / differential thermogravimetry (TG / DTG)) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). The results showed that kaolinite with particle size less than 2 μm was identified in all samples. Minor amounts of muscovite and montmorillonite are present in some samples, and pyrophyllite is present in a sample from the hydrothermally altered rocks. Kaolinite morphology in all the samples showed typical forms including hexagonal and pseudohexagonal. The main chemical constituents of the samples are SiO2 and Al2O3; in addition to these, K2O + Na2O, TiO2 and iron are present in smaller quantities. Thermal analysis allowed to reveal the formation of metakaolinite phase at temperatures around 494 °C and 507 °C in the two studied samples from weathered rocks, while the pyrophyllite-bearing sample undergoes this transition at a higher temperature of 653.8 °C. The onset of metakaolinization was observed at about 500 °C for the weathered rock samples and about 700 °C for the pyrophyllite-bearing sample. In addition, mullitization leading to the formation of mullite was evident at 1,100 °C. The study findings allow concluding that the studied kaolins can be used in traditional ceramics production.

Military Reforms in North Vietnam in the 17th–18th Centuries and their Impact on the Combat Capability of the Army

Throughout Vietnam's medieval history, the military aristocracy has always played a crucial role in government, relying on private armies that formed the basis of the armed forces. Nevertheless, in the second half of the 17th –– first quarter of the 18th centuries in the northern part of Vietnam, with the temporary cessation of wars, there has been a transition from military dictatorship and related forms of government to a state in which, at least formally, the first place would be given to civilian officials. This transition required a major reorganization of the army, which was carried out in two stages. At the first stage, in 1674, under the ruler Trinh Tac, the administration of the northern part of the country finally ceased campaigns against the separatists in the south and significantly limited the military's ability to interfere in the affairs of the civilian government. At the same time, private military armies and the principle of recruiting professional military personnel, mainly from the South, were preserved. At the second stage, in the 1720s, under Trinh Cuong, it was decided to abandon professional detachments as the basis of the armed forces completely, and troops began to be formed through recruitment and centralized training of senior and middle-level commanders at the military schools. The latter of these reforms caused significant damage to the combat capability of the troops, which clearly manifested during the civil wars that broke out in the country in the 1730s–40s.

Hybrid machine learning models for aboveground biomass estimations

Forest biomass provides a quantitative assessment for carbon stock marketing on a national or regional scale. Some countries have committed to net zero carbon emissions, so proper biomass estimations are essential. This study investigates the uses of machine learning (LightGBM, XGBoost), in which hyperparameters were tuned by Bayesian-based Optimisers and a novel Tasmanian Devil Optimisation algorithm for estimates of aboveground biomass (AGB) using Sentinel 1A, Landsat images, and ground survey data. A province in the northern part of Vietnam was selected as a case study since the change in land cover has been considered crucial. The models were optimized/trained and validated using statistical indicators, namely, root mean square error (RMSE), coefficient of determination (R2), and mean absolute error (MAE). The trained models were further explained using SHAP values to understand better how they perform and the contribution of each feature to the overall estimates. The results showed that the three indicators of the proposed model were statistically better than those of the reference methods. Specifically, the hybrid model ended up at RMSE ∼13.87, MAE ∼ 10.62, and R2 ∼ 0.79 for the estimation of AGB. Based on the experience, such hybrid integration can be recommended as an alternative solution for biomass estimation. In a broader context, the fast growth of machine learning and optimization algorithms has created new scientifically sound solutions for a better analysis of forest cover.

Estimated population size of the people who inject drugs in Thai Nguyen, Vietnam: A two survey capture-recapture study using respondent driven sampling.

To develop an appropriate programmatic response to the concentrated HIV epidemic, program managers require reliable estimates of the sizes of the key populations. This study attempts to estimate the population size of people who inject drugs (PWID) in Thai Nguyen-a province in the northern part of Vietnam. Two source capture-recapture population size estimates were calculated using data from two respondent driven sampling survey rounds conducted in 5 selected districts from May to August 2019. The population size of the PWID was calculated based on the number of PWID recruited in each survey and 'recaptured' during the first and the second survey. Additionally, personal network size data collected in the RDS was used to measure the population of PWID using the Successive Sampling Population Size Estimate (SS-PSE) method. The population of PWID estimated in five selected districts using the two capture-recapture method (CRC) (median = 5,396, 95% CI: 4,011-9,100) was slightly lower than estimated using SS-PSE with RDS survey 1 (median = 5,580, 95% CI: 3,024-9,272) and higher than when using SS-PSE with RDS survey 2 (median = 4,793; 95% CI: 2,310-8,618). The provincial PWID population estimates based on various approaches (e.g. extrapolation based on the prevalence of PWID in the districts) ranged from 6,498 (95% CI: 4,829-10,957) to around 6,807 (95% CI: 5,341-10,527). A provincial estimate of 6,782 PWID, with a confidence interval ranging from 5,312 to 10,527, will help guide planning and resource allocation to support appropriate levels of HIV prevention, care, and treatment services in the Thai Nguyen province.

Constituents of essential oils from the leaves and twigs of Zanthoxylum avicennae (Lamk.) DC. Growing in limestone forest, northern Viet Nam

Zanthoxylum avicennae (Lam.) DC. is a medicinal and aromatic plant, belong to the Zanthoxylum genus. The plant is found in some Asian contries, including Viet Nam. The various parts of this plant has been used to medicine and contain essential oils. In this study, the essential oil of Z. avicennae was isolated. Two essential oils from the leaves and twigs of Zanthoxylum avicennae (Lamk.) DC. collected from a limestone forest in Northern part of Vietnam were separately obtained by hydrodistillation and analyzed by GC-MS. A total of 42 and 53 compounds were identified in the leaf and twig oil, respectively. Mono- and sesquiterpenes were found to be the main chemical classes in both oils. Major constituents of the leaf oil were β-caryophyllene (18.71 %), α-humulene (14.03 %), α-terpinene (10.65 %), γ-terpinene (10.64 %), and linalool (9.42 %). Major constituents of the twig oil were linalool (18.3 %), β-phellandrene (8.82 %), α-terpinene (7.85 %), o-cymene (7.79 %), γ-terpinene (7.99 %), and (E)-β-ocimene (6.62 %). In the leaf oil the total amounts of mono- and sesquiterpenes were nearly equal (49.15 % and 44.27 %, respectively), while the twig oil was dominated by monoterpenes (76.66 % and 2.65 %, respectively). Previous literature data on essential oils obtained from this plant species were reviewed and discussed.

Discrimination of the geographical origins of rice based on polycyclic aromatic hydrocarbons.

Over the past few decades, several techniques have been applied to identify the geographical origins of rice products. In this study, the chemical characterization of polycyclic aromatic hydrocarbons (PAHs) was carefully conducted by analysing PAHs in rice samples collected from private sector planting areas located in Bali and Yogyakarta, Indonesia (i.e. ID; n = 20), west sides of Malaysia (i.e. MY; n = 20), Mandalay, Legend, Myingyan, Myanmar (i.e. MM; n = 20), northern parts of Lao PDR (i.e. LA; n = 20), central parts of Cambodia (i.e. KH; n = 20), northern parts of Vietnam (i.e. VN; n = 20), and Thailand (i.e. TH; n = 22). Percentage contributions show the exceedingly high abundance of 5-6 ring PAH congeners in rice samples collected from Indonesia, Malaysia, Thailand, Myanmar, Cambodia and Vietnam. Lao PDR rice samples were overwhelmed by 4-ring PAH congeners with the percentage contribution of 46% followed by 5-6 ring PAHs (33%) and 3-ring PAHs (21%). In addition, hierarchical cluster analysis and principal component analysis can successfully categorize some rice samples based on its geographical origins.

Effect of Temperature on Life History of Bemisia Tabaci (Gennadius) (Homoptera: Aleyrodidae) on Cassava Manihot Esculenta Crantz

The aim of the present study was to evaluate the relationships between environmental temperatures and life-history traits of whitefly Bemisia tabaci on cassava in the Northern part of Vietnam. The influence of temperature on the biological characteristics of whitefly B. tabaci fed on cassava was evaluated at 20ºC, 25ºC, 27.5ºC, and 30ºC using individual insect rearing methodology. Results of the study showed that the development time from egg to adult of B. tabaci was influenced by temperatures. The data indicated that under different temperatures (20ºC, 25ºC, 27.5ºC, and 30ºC), the life cycle of B. tabaci were 41.46, 28.64, 24.29, and 20.25 days, respectively. The determination of lower developmental threshold and degree days for whitefly development were 11.2ºC and 344.8 degree-days. There were 14.31 whitefly generations within 1 year on cassava suggesting this plant is a suitable host plant for the development and reproduction of B. tabaci. Female longevity ranged from 4.92 to 10.23 days. The fecundity ranged from 49.3 to 74.0 eggs/female. The mortality rate reached its highest rate of 36.27% at 30ºC. Our results suggested that B. tabaci had high reproduction rates and demonstrated their positive fitness traits on cassava in a wide range of temperatures, being a potential important pest of cassava cultivars.

An Overview of the Tectonic Evolution of the Indochina block and Granitoid Emplacement, particularly in the central and south Vietnam

Introduction: Vietnam is mainly located within the Indochina block in Southeast Asia. Asmall northern part of Vietnam belongs to the South China block, the southwest part liesadjacent to the Sibumasu block and opens to the East Sea on the east side. Tectonicactivities in Vietnam were very complicated they relate to intense interactions betweenmany geological blocks at different times. Magmatic emplacement is the final and instantproduct of tectonic activities.
 Methods: Geochemical data analysis from rock samples withinVietnam collected by other researchers has been reused in the scope of this study to verifythe relation between tectonic evolutions and their granitic magmatism. GCD (GeochemicalData Toolkit), an R language program for handling and recalculation of geochemical data.
 Results: Geochronology and geotectonic model derived from rock analysis have beenascertained main tectonic evolutions of the Indochina. The current granitoidclassification in Vietnam mostly based on petrographical studies. The Nui Cam granitoid isbeing classified as Deo Ca, Dinh Quan granitoid. However, based on trace elements, they aredifferent. They may belong to different granitoid system.
 Conclusion: Major tectonic eventswithin the Indochina block are well supported by the nature of granitoid emplacements. Petrological studies of these magmatic rocks would bring out valuable information toconfirm and clearly understand the tectonic evolutions of the region. Igneous rocksclassification must based on tectonic fundamental instead of petrographical studies.

The Properties of High-strength Concrete with High Volume of Natural Pozzolan

This paper presents the properties of high-strength concrete containing a high volume of N-class natural pozzolan sourced from the Northern part of Vietnam. Based on the conducted studies’ results showed that the mechanical properties of the natural pozzolan concrete were generally lower than those of control concrete. However, with effects combined of natural pozzolan and SR-5000F superplasticizer on the microstructure of concrete, mechanical properties of high-strength concrete increases with the amount of natural pozzolan from 10 to 20% by mass of cement, then descends. In addition, the maximum temperature of both conventional and High-strength concrete specimens significantly decreases with the increasing content of natural pozzolan. Furthermore, the relationship between compressive and flexural strength, modulus of elasticity and compressive strength of heavyweight concrete specimens are also determined in this investigation.

Contribution to the taxonomy of the paper wasp genus Polistes (Polistella) (Hymenoptera: Vespidae: Polistinae) from Vietnam, with description of a new species.

One species of the genus Polistes, Polistes (Polistella) caobangensis Nguyen, sp. nov. is described from the northern part of Vietnam. In addition, males of two other species, Polistes (Polistella) gilvus Nguyen, Kojima and Saito and Polistes (Polistella) brunus Nguyen and Carpenter are also described for the first time.

Association of Eating Behavior and Parental Body Mass Index with Obesity of Primary School Children: A Case Study in Hai Phong City, Vietnam

Obesity in children has adverse effects on both health and psychology. Obesity is known to be influenced by environmental factors and genetic factors, as well as the interaction between genes and environment. Hai Phong city located in the northern part of Vietnam has rapid economic growth and urbanization.

Developing critical thinking of students through STEM educational orientation program in Vietnam

One of the requirements in teaching process is to develop the thinking of learners. Thus, how an educator could organize teaching activities in order to enable the critical thinking ability of students in high school? Based on the stages of the solving process in the learning process of the student, the expression of critical thinking in each stage, the author would like to suggest educational orientation program following STEM system (STEM activities) in order to develop critical thinking of students. This article analyses the impact of using STEM activities on the development of students in some high schools in mountainous regions in the northern part of Vietnam. The results show the development of critical thinking of students through STEM activities and some superior suggestions for using STEM activities to motivate critical thinking of students in high school.

DƯ LƯỢNG HÓA CHẤT BẢO VỆ THỰC VẬT CƠ CLO TRONG MỘT SÓ SINH VẬT VÙNG TRIỀU PHÍA BẮC VIỆT NAM

Organochlorinated pesticides (OCPs) had been used widely in agriculture for protecting crop, eliminating insects. However, OCPs are banned in most countries because of their toxicity, long persistence and bio-accumulation. They are listed in carcinogen group and POP group (Persistent organic pollutants). In Vietnam, OCPs were banned in 1990s, but their residues are still found in the environments, including seawater, sediment and organisms. This paper presents the survey data of residues of OCPs in some organisms living in tidal flats in the northern part of Vietnam during the year 2013–2014. The results show that the total residue of OCPs in shellfish ranged from 5.57 µg/kg to 116.04 µg/kg dry weight. Compared with the American Guide for mollusk shellfish (2007), it is found that the organisms living in the tidal flats were not polluted by OCPs. However, these compounds can be accumulated in fat tissue even in very low concentration. Therefore, their presence in organism is alarming.

Spatial evaluation of the pesticide application method by farmers in a paddy field in the northern part of Vietnam

The pesticide application method is important for controlling a target pest effectively. The current status of pesticide application techniques for small-scale rice farmers in Red River Delta, Vietnam aims to be clarified to control serious rice pest insects, such as Nilaparvata lugens (Stal) (Hemiptera: Delphacidae), which live on the bottom of rice plants. Interviews with farmers revealed their preferences and practices towards pesticide application. The farmers’ application technique was evaluated by investigating the droplet deposition level at different heights of rice plants (bottom, middle, and top) and the distance from the spray walking path (near, middle, and far) in a rice paddy field using water-sensitive paper (WSP). Droplet deposition on WSPs was categorized into eight ranks. Ordered logistic model analysis revealed that the droplet did not reach to the bottom of plant, while no significant differences were found among the distances from the walking path. The droplet deposition rank and the mortality of N. lugens were positively correlated. The low efficiency of the pesticide applied by farmers to control N. lugens could be one of the factors that contribute to the insecticide-resistance development of N. lugens in Vietnam.

Impacts of Different Physical Parameterization Configurations on Widespread Heavy Rain Forecast over the Northern Area of Vietnam in WRF-ARW Model

This study investigates the impacts of different physical parameterization schemes in the Weather Research and Forecasting model with the ARW dynamical core (WRF-ARW model) on the forecasts of heavy rainfall over the northern part of Vietnam (Bac Bo area). Various physical model configurations generated from different typical cumulus, shortwave radiation, and boundary layer and from simple to complex cloud microphysics schemes are examined and verified for the cases of extreme heavy rainfall during 2012–2016. It is found that the most skilled forecasts come from the Kain–Fritsch (KF) scheme. However, relating to the different causes of the heavy rainfall events, the forecast cycles using the Betts–Miller–Janjic (BMJ) scheme show better skills for tropical cyclones or slowly moving surface low-pressure system situations compared to KF scheme experiments. Most of the sensitivities to KF scheme experiments are related to boundary layer schemes. Both configurations using KF or BMJ schemes show that more complex cloud microphysics schemes can also improve the heavy rain forecast with the WRF-ARW model for the Bac Bo area of Vietnam.

Factors structuring phytoplankton community in a large tropical river: Case study in the Red River (Vietnam)

Algal assemblages have been widely used as an ecological indicator of aquatic ecosystem health conditions because of their specific sensitivity to a wide variety of environmental conditions. In turbid rivers, as in other aquatic systems, phytoplankton structure plays an important role in structuring aquatic food webs. Worldwide, phytoplankton is less studied in turbid, large tropical rivers compared to temperate river systems. The present study aimed to describe the phytoplankton diversity and abundance in a turbid tropical river (the Red River, northern part of Vietnam from 20°00 to 25°30 North; from 100°00 to 107°10 East) and to determine the importance of a series of environmental variables in controlling the phytoplankton community composition. Phytoplankton community was composed of 169 phytoplankton taxa from six algal groups including Bacillariophyceae, Chlorophyceae, Cryptophyceae, Euglenophyceae, Dinophyceae and Cyanobacteria. Community composition varied both spatially and with season. Sixteen measurement environmental variables were used as input variables for a three-layer backpropagation neural network that was developed to predict the phytoplankton abundance. Phytoplankton abundance was successfully predicted using the tagsig transfer function and the Levenberg-Marquardt backpropagation algorithm. The network was trained to provide a good overall linear fit to the total data set with a slope (R) and mean square error (MSE) of 0.808 and 0.0107, respectively. The sensitivity analysis and neutral interpretation diagram revealed that total phosphorus (TP), flow discharge, water temperature and P-PO43− were the significant variables. The results showed that the developed ANN model was able to simulate phytoplankton abundance in the Red River. These findings can help for gaining insight into and the relationship between phytoplankton and environmental factors in this complex, turbid, tropical river.

Taxonomic studies on the genus Orancistrocerus van der Vecht, 1963 (Hymenoptera: Vespidae: Eumeninae) from Vietnam, with description of a new species.

Two species of the genus Orancistrocerus van der Vecht, 1963 from Vietnam are recorded. Of them, a new species, O. altus sp. nov. from Lang Son province in the northern part of Vietnam is described and illustrated. In addition, one subspecies, O. aterrimus nigriceps van der Vecht, 1963 is newly recorded from China.

Active Tectonic Controls on Hydrothermal Flow in the Northern Part of Vietnam: Implications for The Geothermal Exploration at Uva geothermal reservoir in Dien Bien Phu Basin

Geologic characteristic controls the development of high-flux hydrothermal conduits that geothermal system formation which is evaluated at large and small scales in the Northern part of Vietnam. There are also several active fault zones here including the Red River fault zone (RRFZ), and Dien Bien-Lai Chau fault zone (DBLCFZ) which have been shown by the previous study. However, the investigation for geothermal potential relating to these fault zones has not been implemented yet. Therefore, this work has made a synthesis of geothermal potential in Northern part of Vietnam basing on the geostructural, geochemical and geophysical data. It shows the first study for the assessing of the geothermal potential of DBLCFZ which is based on the presence of hot springs at the southern DBPB (Uva geothermal reservoir). This study focuses on the deformation characteristics of fault, determining the heat source basing on both electrical field geophysical data and geo-thermometric calculations of K+-Na+cations from thermal water in this area, in combination with the assessment of groundwater potential by the hydrogeological survey. The result shows that firstly the hot spring phenomenon at Uva geothermal reservoir (with flow rate attending to 216m3 per day) which is related to the DBLCFZ, and secondly, the geothermal potential in Uva area belongs to medium level in the worldwide classification grade with the calculated heat source is up to 145,3oC in average. Considerations on the restorable capacity of groundwater and its geothermal potential, this result suggests that the geothermal source of Uva can be used to build a geothermal power plant on a small scale.

Water as Human Right: Impact of Thai Binh 1 Thermal Plant Project on Domestic Water Supply of Riverine People in Chi Thien Village, Vietnam

The research studies on the typical context of Chi Thien village, an area having new- operated coal-power plant as the development project in the northern part of Vietnam. As the focus of the research, domestic water supply is studied. Conventionally, villagers harvest rainwater into big reservoirs that later on were demolished for house renovation after the agricultural compensation for the coal plant construction. Since the establishment of the Thai Binh 1 Thermal plant, locals are recommended not to drink raining water because of potential negative impacts of coal ash on human health. Findings of the research indicate that local households have been provided with tap water service since 2014 by the Chieu River water plant of the local authority. However, doubts on the low tap water quality and its unstable frequency, rainwater returns to be the preferable choice for their domestic water supply. There is a regular check on water affirmed by the engineer from Chieu River plant. Nevertheless, for confidentiality, it was not allowed to publish regardless of the request to have evidence on qualified tap water. This is considered as the violation of the right to information and the participation in environmental decision making of the villagers. For certain disadvantages of water situation, local people have adaptation by buying reverse osmosis(RO)water filters(wealthier family only)and need to pay for water consumption expense with the low quality received. Study on domestic water is a study on human well-being, human rights and state obligation to ensure the water sanitation, the accessibility, and affordability to people. The role of the Vietnamese government is analyzed in addressing these potential impacts caused by the coal plant project towards an adequate standard of living and the highest attainable standard of health in Chi Thien. The thesis is social research using qualitative research methodology of in-depth interviews and referral samples to approach the topic and elicit reliable information, particularly on opinions and hands-on experiences of villagers.