Mobilité quotidienne dans l’espace périurbain à Bình Tân (Municipalité de Hô Chi Minh-Ville)

La mobilité quotidienne urbaine est l’un des phénomènes les plus complexes des grandes agglomérations contemporaines de l’Asie du Sud-Est. Les zones périurbaines, avec leurs paysages d’activités rurales et urbaines étroitement imbriquées représentent une forme d’urbanisation qui interroge la dualité urbain-rural. Les zones périurbaines de Hô Chi Minh-Ville sont analysées dans leur contexte local, prenant en compte les questions posées par ce phénomène socio-géographique. Les trois statuts résidentiels identifiés dans cette étude sont caractérisés par leurs façons différentes de vivre l’espace suburbain à Hô Chi Minh-Ville. On analyse leur mode de vie qui subit d’importants changements, et en particulier au niveau de la mobilité. Les résultats sont présentés pour les trois groupes : d’abord, les anciens résidents propriétaires ; deuxièmement, les nouveaux accédants à la propriété qui ont le droit d’utiliser leur propre terrain et le groupe de locataires. L’analyse montre que le niveau individuel, la localisation centrale du travail ou des activités détermine les modèles de flux.Daily urban mobility is one of the most complex and relevant phenomena of contemporary megacities in Southeast Asia. Peri-urban areas, with their landscapes of closely mixed rural and urban activities represent a form of urbanization generating an emerging question on the traditional urban-rural duality. The peri-urban areas of Ho Chi Minh City are viewed in their local context, taking into account the issues raised by this socio-geographical phenomenon. Three types of housing tenure have been identified and characterized by their ways of living the suburban space in Ho Chi Minh City. Their lifestyle is analyzed, on the basis of in-depth interviews, questionnaires and actual observations in peri-urban Binh Tan District, one of the rapidly growing areas in Ho Chi Minh City. The results are presented for the three groups including: first, the old resident group who have the use of their land ownership in the locality; second, the new residents who have the right to use their own land and the group of tenants. The results show that the central position of work or activities in people’s lives determines the flows patterns. The objective of the article is also to carry out an analysis of different models of peri-urban mobility, the purpose of mobility in different contexts, but also mobility conditions

Mobilité quotidienne dans l’espace périurbain à Bình Tân (Municipalité de Hô Chi Minh-Ville)

La mobilité quotidienne urbaine est l’un des phénomènes les plus complexes des grandes agglomérations contemporaines de l’Asie du Sud-Est. Les zones périurbaines, avec leurs paysages d’activités rurales et urbaines étroitement imbriquées représentent une forme d’urbanisation qui interroge la dualité urbain-rural. Les zones périurbaines de Hô Chi Minh-Ville sont analysées dans leur contexte local, prenant en compte les questions posées par ce phénomène socio-géographique. Les trois statuts résidentiels identifiés dans cette étude sont caractérisés par leurs façons différentes de vivre l’espace suburbain à Hô Chi Minh-Ville. On analyse leur mode de vie qui subit d’importants changements, et en particulier au niveau de la mobilité. Les résultats sont présentés pour les trois groupes : d’abord, les anciens résidents propriétaires ; deuxièmement, les nouveaux accédants à la propriété qui ont le droit d’utiliser leur propre terrain et le groupe de locataires. L’analyse montre que le niveau individuel, la localisation centrale du travail ou des activités détermine les modèles de flux.Daily urban mobility is one of the most complex and relevant phenomena of contemporary megacities in Southeast Asia. Peri-urban areas, with their landscapes of closely mixed rural and urban activities represent a form of urbanization generating an emerging question on the traditional urban-rural duality. The peri-urban areas of Ho Chi Minh City are viewed in their local context, taking into account the issues raised by this socio-geographical phenomenon. Three types of housing tenure have been identified and characterized by their ways of living the suburban space in Ho Chi Minh City. Their lifestyle is analyzed, on the basis of in-depth interviews, questionnaires and actual observations in peri-urban Binh Tan District, one of the rapidly growing areas in Ho Chi Minh City. The results are presented for the three groups including: first, the old resident group who have the use of their land ownership in the locality; second, the new residents who have the right to use their own land and the group of tenants. The results show that the central position of work or activities in people’s lives determines the flows patterns. The objective of the article is also to carry out an analysis of different models of peri-urban mobility, the purpose of mobility in different contexts, but also mobility conditions

Anxiety symptoms and coping strategies among high school students in Vietnam after COVID-19 pandemic: a mixed-method evaluation

IntroductionThe objective of the current study was to examine the rate of high school students at risk of anxiety disorder during the COVID-19 pandemic in Vietnam, as well as the coping strategies utilized within this demographic.MethodsAn evaluation was conducted through the utilization of mixed methods, consisting of a combination of a cross-sectional study and in-depth interviews. In this study, a sample of 3,910 students from 13 high schools in Hanoi, Vietnam were selected for participation. The measurement of symptoms of anxiety disorder was conducted through the application of the seven-item General Anxiety Disorder (GAD-7) scale. To comprehend the underlying causes of anxiety and the various coping mechanisms employed, in-depth interviews were conducted.ResultsThe findings indicate a prevalence rate of anxiety disorder symptoms among students at 40.6% The prevalence rates of mild, moderate, and severe anxiety symptoms were found to be 23.9%, 10.9%, and 5.8%, respectively. In-depth interviews uncovered multiple sources of anxiety experienced by high school students, namely their academic performance, social interactions, prejudicial attitudes from their social circle, and familial expectations. Numerous coping strategies were then documented.DiscussionThe current investigation ascertained that there exists a moderate level of anxiety amongst high school students in Hanoi, Vietnam during the COVID-19 outbreak. Furthermore, this study configured potential indicators to identify vulnerable individuals and further suggests the development of targeted interventions

Arsenate reductase gene from Pityrogramma calomelanos L. enhances tolerance to arsenic in tobacco

Arsenic (As) contamination in soil, water and air is an alarming issue worldwide and has serious effects on human health and environment. Arsenic is a naturally occurring element found in rocks, soil, and water, and exposure to high levels of arsenic can lead to a range of health problems. The effects of arsenic contamination can also be felt in the environment, as it can harm plants and animals and disrupt ecological systems. The major purpose of this study was to produce transgenic plants with improved tolerance to and accumulation of arsenic via transformation of arsenate reductase gene (ArsC) into tobacco genome. Transgenic plants were screen by PCR and southern blot. Further, their tolerance and accumulation to arsenic were evaluated. In the result, we have cloned, characterized, and transformed the ArsC gene from Pityrogramma calomelanos L. (PcArsC). Its phylogenetic analysis revealed 99% homology to ArsC gene in GenBank (accession number X80057.1). Moreover, Southern blot analysis showed that ArsC gene was integrated into the tobacco genome as a single-copy. These single-copy transgenic lines showed much higher tolerance to and accumulation of As than wild type, with no other phenotypes observed. These results demonstrated that Pityrogramma calomelanos ArsC gene can improve arsenic tolerance and accumulation in transgenic tobacco lines. Thus, using Pityrogramma calomelanos L. ArsC gene for genetic engineering has potential implications in the decontamination of arsenic-containing soil

Les réactions de la communauté citadine de Hô Chi Minh-Ville aux inondations et à la fièvre hémorragique virale

Hô Chi Minh-Ville est une mégapole du Vietnam qui a connu un processus d’urbanisation rapide et anarchique au même titre que les autres mégapoles des pays en développement. L’augmentation du nombre de migrants ruraux qui viennent à Hô Chi Minh-Ville a mis la pression sur les services en charge de la gestion urbaine en général, de celle des infrastructures, et tout particulièrement de celle du système de drainage de la ville. Ceci a pour conséquence l’apparition d’inondations en ville dont les effets sont néfastes pour la santé des habitants, en particulier la prolifération des moustiques qui sont les vecteurs de la fièvre hémorragique virale. Notre recherche vise à explorer la perception qu’ont les gens de la relation de cause à effet qui peut exister entre les inondations et la dengue. Nos études ont porté sur trois districts périodiquement inondés représentant trois zones affectées différemment par l’urbanisation à Hô Chi Minh-Ville. Nous avons réalisé 458 questionnaires et 18 entretiens multiples semi-directifs de ménages touchés par la dengue. Questionnaires et entretiens nous ont également aidés à appréhender la perception que peuvent avoir les habitants de la gravité de la dengue et de leur sensibilité à celle-ci, ainsi que leur comportement face aux mesures de prévention mises en œuvre dans les trois zones étudiées.Ho Chi Minh City experiences a rapid urbanization. Like any other cities in the developing countries, the increasing number of rural migrants coming to Ho Chi Minh City caused many pressures on urban management, housing and infrastructure, especially on the city drainage system as the resources of the city are limited. Consequently, the occurrence of urban floods is very high and has adverse impacts on city residents’ health, including dengue hemorrhagic fever. To date, the literature review in Vietnam suggested there had been a minimum research about perception and responses of urban communities on dengue. This research aims to explore perception of people about the relationships between urban flood and dengue, the connections between social dimensions of vulnerability and appearance of dengue caused by flood hazard and prevention of health risks in the community. Observations and interviews were conducted in three flood-prone districts which have been chosen as representative of three areas variously impacted by urbanization in Ho Chi Minh City, including a rural area where urbanization just starts, a suburban area where urbanization strongly occurs and a central area where urbanization is stabilized. Empirical data were extracted from a structured questionnaire with 458 people and in-depth interviews with 12 households and six local health officers. The main quantitative and qualitative data gathering by the research team focuses on such issues as social-economic and residential characteristics of households living in the flood prone areas, people’s perception on the susceptibility and severity of dengue, fact of dengue in households and flood and dengue preventive behaviour of people. The main findings show that dengue in Ho Chi Minh City has tended to increase by time and, strongly associated with urban flood, appearance and spread of dengue, is closely linked with social-economic and residential characteristics of residential community dengue perception. Many constraints still remain in the preventive behaviour of people and existing preventive health activities are not yet received the sufficient investment and concern from various social actors. Thus, the geographical distribution of dengue, shows that suburban areas characterized with poor living conditions and most impacted by flood hazard are also the ones who suffer the highest rate of dengue. To reduce the prevalence of dengue in Ho Chi Minh City requires comprehensive solutions such as orientation of urbanization management, improvement of the living condition of urban poor communities and enhancement of dengue preventive activities of the official health sector

EFFECTS OF SALT STRESS ON PLANT GROWTH AND BIOMASS ALLOCATION IN SOME WETLAND GRASS SPECIES IN THE MEKONG DELTA

Salt stress causes serious damage to many cellular and physiological processes that leads to yield reduction. The study induced salt stress using Hoagland solution added NaCl to evaluate its effects on plant growth and biomass allocation of some wetland grass species in order to identify salt-tolerant species for replacing and/or supplementing rice/grass in rice-shrimp model and salt-affected area in the Mekong Delta. The study also seeks to evaluate the response of leaf chlorophyll (SPAD unit) and proline content in salt-treated plants to varying application of salinity. Typha orientalis, Lepironia articulata, Eleocharis dulcis and Scirpus littoralis were studied in hydroponics condition with four levels of NaCl of 5, 10, 15, 20‰ and the control treatment (without adding NaCl). The experiment was arranged in a completely randomized design with 3 replications. The salt-treated plants showed visually clear responses of inhibited growth under salt stress condition compared to the control plants. Among the four studied species, T. orientalis produced the highest dry shoot biomass (15.5 g DW/plant), while E. dulcis had the lowest value (2.8 g DW/plant). However, only T. orientalis showed significantly decreased in biomass as salinity increased with 9.3 and 4.6 times lower of fresh and dry biomass in plants grown at the salinity level of 20‰ compared to those grown in the control treatment. The other three plant species did not affect by salinity levels. The results indicated that S. littoralis, L. articulata and E. dulcis could tolerate at high salinity of 20‰ (eq. to the EC value in the nutrient solution of 38.0 dS/m) and could be potential candidate to grow in the rice-shrimp model or in the salt-affected soils. 

Nitrate pollution in the Red River Delta

The Red River Delta is home to the capital of Vietnam, Hanoi. The large population relies on the catchment for the provision of primary water resources for its industry and agriculture. This critical reserve is rapidly becoming impacted by anthropogenic activities and we demonstrate how nitrate pollution, in particular, is influencing the health of the Red River Delta

Identifying the controls on nitrate and metabolic state within the Red River delta (Vietnam) with the use of stable isotopes

In many places around the world, anthropogenic activities have resulted in nitrate (NO3−) pollution and changes in the metabolic state of aquatic ecosystems. Here we combined stable isotope and physico-chemical monitoring to assess the sources of NO3− and the overall metabolic state within the Red River delta, Vietnam. River water stable isotope compositions (δ18O-H2O) ranged between −11.2 and −2.7 ‰, δ18O-NO3− between −7.1 and + 29.7 ‰ and δ15N-NO3− between −3.9 and + 14.0 ‰. We identified the dominant NO3− sources as: 1) soil leachate, 2) domestic waste flushed from urban areas, and 3) NH4+ fertilizers washed from paddy fields. The relative impact of each source depends on geographical location within the delta and the time of year, due to dilution and concentration effects during wet and dry seasons. The primary NO3−source upstream is natural soil leachates, predominantly from tributaries connected to the Red River’s main stream. Within the middle-lower section of Red River delta, urban pollution from manure and septic waste reaches as high as 50 % of the total NO3− load during dry season. NO3− leached from fertilizers is also high at sites in the middle of the delta, related to agricultural activities. Dissolved oxygen isotope (δ18O-O2) values calculated from δ18O-H2O and δ18O-NO3− values indicate that the aquatic metabolism is net autotrophic (oxygen from primary production exceeds consumption by respiration), but high inputs of biodegradable organic matter from untreated domestic waste and high rates of sediment oxygen demand (SOD) and chemical oxygen demand (COD) have resulted in the whole river system becoming undersaturated in oxygen. High NO3− loads and low DO saturation are of critical concern and require mitigation practices to improve water quality for millions of people

Synthesis and Characterization of Silver Nanoplates by a Seed-mediated Method

Silver nanoplates (SNPs) having different size were synthesized by a seed-mediated method. The seeds -silver nanoparticles with 4 – 6 nm diameters were synthesized first by reducing silver nitrate with sodium borohydride in the present of Trisodium Citrate and Hydrogen peroxide. Then these seeds were developed by continue reducing Ag$^+$ ions with various amount of L-Ascorbic acid to form SNPs. Our analysis showed that the concentratrion of L-Ascorbic acid, a secondary reducing agent, played an important role to form SNPs. In addition, the size and in-plane dipole plasmon resonance wavelenght of silver nanoplates were increased when the concentration of added silver nitrate increased. The characterization of SNPs were studied by UV-Vis, FE-SEM, EDS and TEM methods