Central Part Of Vietnam Research Articles

222Rn in selected waters sources from Quang Nam - Da Nang region - Central part of Vietnam

This paper presents the radon concentrations of forty-eight samples collected from lakes, streams and rivers as surface water, from dug well as ground water and from boreholes and thermal waters as underground waters in the Da Nang – Quang Nam, central part of Vietnam. The measured radon concentrations varied from 0.265 (in lake water) to 107 Bq L−1 (in underground water) with the following trend from the lowest to the highest: 222Rn in lakes<222Rn in rivers<222Rn in stream<222Rn in dug wells<222Rn in thermal waters<222Rn in drilled wells. Overall, the average 222Rn concentration in groundwater is twelve times higher than that in the surface water.Assuming that each person drinks 2.10−3 m3 d−1 and uses six cubic meters for washing purposes per month, the estimated total annual effective dose due to ingestion and inhalation of radon from the studied water samples ranges from 1.3 to 541 μSv y−1 for adults; from 1.2 to 479 μSv y−1 for children; and from 2.1 to 838 μSv y−1 for infants.

Rational design of an acidic erythritol (ACER) medium for the enhanced isolation of the environmental pathogen Burkholderia pseudomallei from soil samples.

The soil bacterium Burkholderia pseudomallei causes melioidosis, a potentially fatal and greatly underdiagnosed tropical disease. Detection of B. pseudomallei in the environment is important to trace the source of infections, define risk areas for melioidosis and increase the clinical awareness. Although B. pseudomallei polymerase chain reaction (PCR)-based environmental detection provides important information, the culture of the pathogen remains essential but is still a methodological challenge. B. pseudomallei can catabolize erythritol, a metabolic pathway, which is otherwise rarely encountered among bacteria. We recently demonstrated that replacing threonine with erythritol as a single carbon source in the pH-neutral threonine-basal salt solution (TBSS-C50) historically used improved the isolation of B. pseudomallei from rice paddy soils. However, further culture medium parameters for an optimized recovery of B. pseudomallei strains from soils are still ill-defined. We, therefore, aimed to design a new erythritol-based medium by systematically optimizing parameters such as pH, buffer capacity, salt and nutrient composition. A key finding of our study is the enhanced erythritol-based growth of B. pseudomallei under acidic medium conditions. Our experiments with B. pseudomallei strains from different geographical origin led to the development of a phosphate-buffered acidic erythritol (ACER) medium with a pH of 6.3, higher erythritol concentration of 1.2%, supplemented vitamins and nitrate. This highly selective medium composition shortened the lag phase of B. pseudomallei cultures and greatly increased growth densities compared to TBSS-C50 and TBSS-C50-based erythritol medium. The ACER medium led to the highest enrichments of B. pseudomallei as determined from culture supernatants by quantitative PCR in a comparative validation with soil samples from the central part of Vietnam. Consequently, the median recovery of B. pseudomallei colony forming units on Ashdown's agar from ACER subcultures was 5.4 times higher compared to TBSS-C50-based erythritol medium (p = 0.005) and 30.7 times higher than TBSS-C50 (p < 0.001). In conclusion, our newly developed ACER medium significantly improves the isolation of viable B. pseudomallei from soils and, thereby, has the potential to reduce the rate of false-negative environmental cultures in melioidosis risk areas.

Early paleolithic of Vietnam and Southeast Asia

The article considers the discovery of a complex of Early Paleolithic sites with a bifacial industry in the central part of Vietnam. Vietnam is one of the unique regions of Southeast Asia, in terms of the settlement of ancient populations of people, the evolution of their culture and the development of man himself, due to its geographical proximity to South China in the north, and during the existence of Sundaland, could serve as one of the transit territories migrations of ancient hominins. In the Gia Lai province in the area of the city of An Khe, the Russian-Vietnamese expedition discovered more than thirty Early Paleolithic sites with pebble-flake industry and bifacially worked tools such as hand axes. According to the tektites found in the cultural layer together with bifaces and pebble tools, two dates were obtained using the 40K/38Ar method: 806 22 thousand years ago and 782 20 thousand years ago These dates indicate that the Early Paleolithic industry discovered in Vietnam existed simultaneously with the industry in the Baise Basin in southern China. Also on the territory of Southeast Asia, several sites with bifacially processed objects and stratified objects with similar technological characteristics of primary splitting dating back to this period were found.

Diversity of Silica-Scaled Chrysophytes in Central Vietnam

This paper focuses on the flora of scale-bearing chrysophytes from eight provinces located in the central part of Vietnam. Khanh Hoa, Phu Yen, Binh Dinh, Thua Thien Hue, Quang Tri, and Quang Binh provinces are located in the coastal area of Vietnam. Lam Dong and Dak Lak provinces represent mountain territories with an elevation of 500–2000 metres above sea level. In total, 212 water bodies of different origins were studied. Samples were obtained from swamp areas, lakes, rivers, reservoirs, ponds, and small temporary water bodies. In total, 76 taxa were identified by electron microscopic observations of samples. A total of 54 taxa were found in the mountainous provinces, while 73 were found in the coastal provinces. Of these, 51 species are common for both areas. The most diverse was the genus Mallomonas with 66 species, varieties, and forms; followed by Synura with 7 taxa; Chrysosphaerella with 2; and Spiniferomonas with 1. Seven taxa of the genus Mallomonas were not identified to the lower rank. All these unidentified specimens may potentially represent new species for science. Ten taxa are reported for the first time in Vietnam.

The development of safe riding guidelines for young riders – A case study of Phu Yen, Vietnam

Phu Yen is a small province located in the central part of Vietnam and is suffering from a tremendous number of traffic casualties, compared with other cities in Vietnam and developed countries. Young riders take a large proportion, accounting for 47.6% in total traffic crashes. To resolve this issue, the present study aims to (i) analyze young riders' behavior and their attitudes towards traffic safety and to (ii) propose a procedure to develop a book of safe riding guidelines to reduce their involvement in dangerous situations. A set of 73 questions in the questionnaire survey have been conducted to determine the risk-taking behavior and attitude towards traffic safety of 300 individuals, who are using bicycles, e-bikes, mopeds, scooters, and motorcycles less than 150 cc. The statistical results indicate that there are significant differences among riding behavior and attitudes of respondents towards traffic safety regarding the regional factor (rural, suburb, and urban), the demographic factor (gender and age), and the travel distance factor. The guidelines designed based on the questionnaire survey are used to alter adolescents' riding behavior and attitudes and so help them recognize, avoid, and handle risks in demanding traffic situations. An analysis of the before and after the traffic safety training workshop to evaluate the effectiveness of the proposed guidelines indicated that there was a significant increment in the perceived risks of young riders after training them by using this book.

Analysis of the 56-kDa type specific antigen gene of Orientia tsutsugamushi from northern Vietnam.

Scrub typhus has been documented since 1932 in Vietnam, however, the disease burden of scrub typhus remains poorly understood in the country. We conducted this study to describe the phylogenetic analysis of the 56-kDa type-specific antigen (TSA) gene of Orientia tsutsugamushi associated with PCR positive cases of scrub typhus. Of 116 positive samples, 65 type-specific antigen gene sequences were obtained and classified into 3 genogroups: Karp, Kato and Gilliam. The Karp genogroup was the most frequently detected phylogenetic cluster in the study with 30 samples (46%), followed by Kato and Gilliam with 20 (31%) and 15 (23%), respectively. All sequences showed 94–100% nucleotide similarity to reference sequences collected in the central part of Vietnam in 2017. Patients infected with Karp genogroup were more likely to have significant thrombocytopenia than the other genogroups. These results suggest that any scrub typhus vaccine considered for use in Vietnam should provide protection against each of these 3 genogroups.

Cultural exchanges, intergration and developmet of the chinese community in central coastal provinces

In the circumstance of the Chinesse emigrants going abroad to seek shelter and find new lands, especially southeast Asia, Dang Trong of Dai Viet kingdom has gradually become a point of arrival which attracts them strongly. Depending on geographic position of contigous sea and advantage of Dang Trong context at home and abroad, Chinese merchants and emigrants have come to the central coastal parts (especially in Quang Nam, Quang Ngai, Binh Dinh, and Phu Yen). Having settled in southeast Asia region as well as in the central part of Vietnam, Chinese emigrants have preseved their traditional culture to gain achievements in this land region. Besides, they have actively integrated into native communities, exchanging culture for prosperity and development. This paper indicates cultural exchanges, integration and development of the Hoa in the central coastal provinces in history and present, which asserts their contributions in the fields of culture, economy and society to build Vietnam nation, notably in the age of present international integration.

Estimation of radiological parameters associated with mining and processing of coastal sand in Binh Dinh province, Vietnam

In Vietnam mining industry is significantly contributing to the socio-economic development. For the industrialization, many kinds of minerals are being exploited and processed that caused the Earth surface to be disconcerted leading to the increase of erosion of soil that possibly carries radioactive nuclides of the natural radioactive chains. Mining could cause increasing radioactive background to the miners as well as to the public members around the mines. This paper presents radiological parameters associated with mining and processing ilmenite minerals in coastal sand for titanium for export in Binh Dinh province, Central Part of Vietnam.

Composition and distribution of freshwater eels Anguilla spp. in Vietnam

A sampling survey to determine the composition and distribution of freshwater eel species was conducted in 12 provinces along the coast of Vietnam from October 2014 to February 2015. The sampled provinces spanned the country from central Vietnam to the south, but freshwater eels were only found in the central part of Vietnam. Species identification of 77 specimens, collected from different habitats (rivers and estuaries), was performed by analysis of both morphological characters and nucleotide sequences of mitochondrial cytochrome oxidase subunit I (COI). The 77 specimens were morphologically and genetically identified as 58 Anguilla marmorata, 17 A. bicolor pacifica, and two A. japonica. This is the first definitive survey about the composition and distribution of freshwater eels in Vietnam where distribution has been hitherto unknown.

Hydrogeochemical Features of Thermal Waters of South Trungbo (Central Vietnam)

The results of studying the features of the hydrogeological structure and chemical and isotope composition of thermal waters from the central part of Vietnam that are characterized by intense manifestations of intrusive magmatism are presented. It is established that low–and high–thermal waters with temperature varying within 30–85°C are developed in the area under study. The value of total mineralization of the hydrotherms ranges from 0.05 to 10.05 g/dm3. It is assumed that the circulation of thermal waters that are different in temperature and chemical composition occurs at two levels. The regular change of the hydrotherm composition in the direction from mineralized chloride sodium, including with increased Ca content, to fresh sodium bicarbonate is revealed. The ratio of δ18O–δ2H isotopes indicates that the water component is based on meteoric water. In the coastal areas, there is an isotope shift towards the ocean waters, which is also confirmed by the hydrogeochemical data. The key factors for forming the chemical composition of the thermal waters in South Trungbo are their genetic type, the interaction processes in the “water–rock–gas–organic substance” system, and their equilibrium–nonequilibrium state.

THE SOLUTION TO THE PROBLEM OF USING GROUND WATER TO COOL LIVESTOCK BUILDINGS

Ambient temperature in the central part of Vietnam in summer can reach 32–35°C; in some places it can be more than 42°C. Hot climate strongly affects the animal organism alongside with the animal weight reduction and reduction the quantity of egg-laying in poultry. Therefore, air conditioning in livestock buildings is necessary. There are several ways to cool the temperature in such buildings, and each one has its own advantages and disadvantages. We propose to use underground water at the temperature of 24–25°C for this purpose. One of the methods of cooling sheds for livestock is sprinkler irrigation of water on the roof. For calculating the amount of heat, removed from the indoor air in the shed to the cooling water, in the first approximation specialists believe in some cases that an appropriate amount of heat being removed is determined mainly by heat transfer from the air inside the shed to the cooling water through the surface of the roof, represented by the lower part of the wave that form the surface of a metal tile, neglecting the influence of heat conduction on top of the wave of the tile surface. Consequentially, such a simplification leads to possible errors. Therefore, the authors solved the problem of cooling shed by irrigation of water on the roof by an analytical method. Specifically, we solved the problem of heat conductivity of the fin of the finite length of constant cross section, wherein different sides of the fin are conjugate with different environments. Additionally, the calculation considered the effect of solar radiation. For this purpose, the authors have created a heat balance equation at steady state for any infinitesimal element of the fin, and solved the differential equation afterwards. The authors applied the results for calculating practical problem of ground water irrigation of a roof of a livestock shed made of metal areas tiles.

QUANTITATIVE ANALYTICAL RESULTS ON TOPOGRAPHIC FEATURE OF THE VIETNAM’S CONTINENTAL SHELF WITHIN COORDINATES 11.7 - 14.00 AND 109.5 - 110.20

This paper presents some analytical results of bathymetry data according to three maps: Three dimensions (3D), slope, aspect on the continental slope and shelf area in the central part of Vietnam within the coordinates of 11.7 - 14.00 and 109.5 - 110.20. The obtained results have reflected clearly the geomorphic characteristics in this area. For example, on the 3D map, the continental slope exists three steps at the depths of 500 - 700 m, 1,250 m, and 1,500 - 1,700 m, running along the meridian 109.70, about 250 km long. These results are also shown on the slope and aspect map. On the slope map, from the depth of about 250 m to the first step base, the slope angle varies within 5 - 200 and from the first step base to second step base, the slope angle varies within 5 - 100; In the remaining part, the slope angle varies within 2 - 80. The other analytical results from the aspect map are also shown clearly, the aspect direction on the wall of three slope steps varies from 50 to 1000, reflecting the topographic slope towards the east, where is abyssal plain. The existence of Pliocene - Quaternary sediments along with steep continental slope caused landslide phenomenon in this area.

Status of pinnipeds in Southeast Asia

AbstractThere are no published records of pinnipeds in Southeast Asia. Photographs in the national media between January 2010 and December 2013 documented seven pinniped records. All were individuals caught by fishermen in the central part of Vietnam (17°56′N south to 15°23′N). All except one pinniped record can be assigned to Largha (=Spotted) Seal

Overview on the species composition of the landsnails fauna of Vietnam

In Vietnam, researsch on the landsnails fauna has begun since the middle of the XIX Century, with the first publication of Souleyet (1841) on the landsnails of the Indochina Region, including some new species, described from central part of Vietnam (Tourane). In the following period, during 60’s years, other important study results on the landsnails fauna of the southern part of Vietnam (Annam, Cochinchine) has been published: Crosse et Fischer (1863, 1854, 1869); Mabille et Le Mesle (1866); Crosse (1867, 1868). Publications on the landsnails species of the northern part of Vietnam occured later, with many very known research works of different authors: Morlet (1855, 1891, 1892); Dautzenberg et Hamonville (1897): Dautzenberg (1893); Bavay et Dautzenberg (1891, 1900, 1901, 1903); Fischer (1848); Mollendorff (1901); Dautzenberg et Fischer (1905). During the war time in Vietnam until 1975, research on the landsnails were almost interrupted, except a few works of Saurin (1955, 1960); Jaeckel (1950); Varga (1963). It continued only after the war, with some recent publications realized in northern part of Vietnam (Vermeulen et Maassen, 2003). Based on the aboved mentioned research results on the landsnails fauna of Vietnam until now, some preliminary remarks could be noted. 1. The species composition of the landsnails fauna of Vietnam, although far to be considered as full, is rather rich and diverse. Until now, totally 776 species has been recorded, essentially from mountain regions of the northern and southern parts of the country. 2. Landsnails fauna of Vietnam is rich of Prosobranchia species, among them, the genera Cyclophorus, (30 species), Alycaeus (11), Pupina (15) are the most high species number groups, living in limestone caves of high humidity of mountain region. 3. The species composition of landsnails of Vietnam, especially of the northern part, is clearly different in comparison with the fauna of the southern part of the indochinese region (Laos, Cambodge, Thailand). 4. Because of the great change in the classification of landsnails in malacology at present times in comparison with the past, it needs a total revision on the taxonomy of published landsnails species composition of Vietnam.

Detection of tetrodotoxin-producing Providencia rettgeri T892 in Lagocephalus pufferfish

Tetrodotoxin (TTX) is a potent toxin but it could be used in pharmaceutical field. Identification of TTX producing bacteria in pufferfish is necessary for TTX yield and the pufferfish conservation. In this study, Lagocephalus was collected from Cam Ranh Sea, a central part of Vietnam during spring season. The liver and intestine were incubated in 0.9% NaCl for TTX detection in pufferfish. To be benefited from the isolation of new TTX producing bacteria, the liver and intestine were incubated in 6.5% NaCl. The cultures were used to test the toxin and to isolate the bacterial community that could yield TTX. Surprisingly, Providencia rettgeri T892 in intestine could produce TTX identified by biochemical test and 16S rRNA sequencing. This strain was used to test the production of TTX, based on thin layer chromatography (TLC), mouse bioassay and high performance liquid chromatography (HPLC) analysis. The bacterium was optimized for TTX production in media prepared from the meat-washing water of Auxis thazard, Megalaspis cordyla and Decapterus maruadsi. Interestingly, the TTX obtained 0.106mg/mL and 0.055mg/mL in medium prepared from A. thazard and M. cordyla, respectively while there was no TTX production detected in medium prepared from D. maruadsi. This paper could contribute to warn to the human health care system about a possible TTX poisoning in some cases related to eating fishes.

Heavy Metals in a Tropical Eel Anguilla marmorata from The Central Part of Vietnam

In order to understand the present status of heavy metal contamination and the risk associated with human consumption, commercial freshwater eels in Vietnam were examined. The concentration of eight elements (Cr, Mn, Co, Cu, Zn, Sr, Cd, and Pb) was determined in muscle tissue of tropical eel Anguilla marmorata collected in four provinces, Quang Tri, Quang Ngai, Binh Dinh, and Phu Yen, from the central part of Vietnam. Concentrations of Cu, Zn, Cd, and Sr were found to be highest, whereas Co concentration showed the lowest at Quang Tri. Cr was recorded to be lowest in Quang Ngai, while the amounts of Mn and Pb did not vary among locations. Although the metal concentrations in the muscle of A. marmorata did not represent a risk for human consumption, elevated Cd concentrations in Quang Tri related to agriculture activities suggest that further investigations should be undertaken to clarify the potential risk to the eel population.

Association of environmental tobacco smoking exposure with an increased risk of hospital admissions for pneumonia in children under 5 years of age in Vietnam

Background:The association between environmental tobacco smoking (ETS) and childhood pneumonia has not been established in developed or developing countries. A study was conducted to assess the effect and impact of...

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Traces of the buried Late Pleistocene ancient coastline in the coastal shallow bed of the North Central part of Vietnam and associated placer potential