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Mine ventilation aims to dilute toxic gas concentrations, dilute dust concentrations, remove them from the mine and ensure pleasant microclimate conditions in the mine, especially at work sites. Currently, in underground coal mines in general and in Giap Khau mine area, Hon Gai coal company, in particular, is in the process of converting the mining area into deep, as well as increasing output. Therefore, it is important to ensure that ventilation is a top priority in long-term occupational safety and meets the plan to increase coal production. In this study, we have evaluated the current state of ventilation in Giap Khau mine area. From those research results, on the basis of computational research methods, we have come up with reasonable solutions to change and improve ventilation efficiency for the mine in the condition of complicated mining plan and technology characteristics are still limited compared to those in the world. Specific solutions solve 2 problems: First, ensure ventilation for the current mining operation stage; Secondly, we have researched and proposing suitable solutions for ventilation of Giap Khau area mine when it has to increase production and move down to an adjacent project at a deeper level.

The first investigation of arsenic (As) contamination in soil cores in the biggest estuarine ecosystem in northern Vietnam was conducted using FE-EPMA, ICP-MS and XRD techniques. Concentrations of arsenic and five heavy metals were measured and mineralogical characteristic of soils and sediments in different land uses were analyzed. Most of the soils contained high proportions of As and heavy metals in the potential mobility fractions and silicate minerals. High concentrations of As and heavy metals were observed in river sediments and top-layers of mangrove forest soil cores. Qualitative analyses using WDS technique on FE-EPMA found As on the iron (hydro)oxides and framboidal pyrite surfaces in the samples. The principal component analysis indicated the enrichment of As and heavy metals in the upper soil layers, suggesting that intensive human activities in upstream of the Red river in recent decades could be the cause of elevated levels of these toxic elements in the estuarine ecosystem.

The paper considers comprehensive solution providing functional stability of the spacecraft with changes in its moments of inertia. There was developed the mathematical description of the spacecraft angular position stabilization system (APSS) in the linear and discrete forms. There was shown the process of obtaining spacecraft APSS diagnostic models for the particular kind and class of failure. There was proved possible to diagnose and restore functionality spacecraft APSS at the systemic level, using the regulator coefficients parametric adjustment

Heavy metal (Cr, Cu, Zn, As, Cd, and Pb) contamination in irrigation water, soil, and vegetables was investigated in farmland adjacent to a multi-industry zone in Bangladesh in dry and wet seasons. In the zone, many factories release wastewater into nearby irrigation canals, and vegetables cultivated with this water could be a major food chain route for human exposure. In the irrigation water and vegetables, heavy metal concentrations exceeded permissible levels in the two seasons, but this was not the case in soil. Zn had the highest concentration, and Cd had the lowest concentration in irrigation water, soil, and vegetables. All heavy metal concentrations were found to be lower in the wet than in the dry season, which is due to the dilution of water by rainfall, lower absorption of heavy metals from the diluted irrigation water, and heavy metal absorption from low concentrated irrigation water and/or soil. The cluster analysis data of irrigation water, soil, and vegetables revealed that the heavy metals in vegetables were considered to be absorbed from irrigation water in the wet season and from soil in the dry season. In the dry season, the high heavy metal concentrations in vegetables might be caused by a high bioconcentration factor (mostly &gt, 20%).

In saline aquaculture ponds in the tropics, intermittent rainfall during the rainy season can cause salinity stratification, and strong solar radiation can cause thermal stratification. The combination of these factors may result in thermohaline convection in the ponds. Thermohaline convection in a closed saline water body can in turn induce heat storage in these ponds. Heat storage in saline aquaculture ponds strongly influences the water environment and consequently affects the quality and yield of aquaculture products from these ponds. We investigated how heat storage in experimental saline aquaculture ponds was influenced by the variation in the weather and water properties during the rainy season. If the pond stratifies into three layers with a salinity gradient in the middle layer, heat storage can occur. The salinity gradient prevents heat from escaping from the lower layer by effectively insulating it from nighttime radiative cooling. When the salinity gradient is perturbed by rainfall, solar radiation, or wind, the heat stored in the pond can begin to dissipate. We explain how the stratification stability and the heat balance in the ponds account for the occurrence of heat storage in the ponds.

The characteristics of the quantitative distribution of fish and decapod crustaceans of benthic and demersal communities were first studied in the six main channels of the Tien River in the lower part of the Mekong Delta, and the coastal zone adjacent to estuaries. The material was collected during the low water season from April to June 2018 using standard commercial beam trawl. The region from the estuary zone upstream to a distance of 110 km has been studied. The coordinates of the beginning and the end of the trawling were determined using a GPS navigator. The average weight of the catch was about 30 kg, the maximum was 100 kg and more. The average catch of fish and crustaceans was about 1.5 kg, the maximum was 4 kg; the anthropogenic wastes and remnants of vegetation made up the rest of the catch. The average specific amount and biomass values which were collected at 36 stations based on 102 trawling results were computed for a comparative analysis of the spatial variability of fish and decapods abundance. The presence of wide limits of variations in quantitative indicators was established. Specific number of fish varied from 23.4 to 1978.2 (average 333.3) specimens·ha-1, decapod crustaceans – from 10.6 to 5091.5 (358.1) specimens·ha-1, the biomass of these groups was 219.1–22773.5 (average 1969.9) g·ha-1 and 31.4–9337.1 (average 740.6) g·ha-1, respectively. The main regularities of the spatial distribution of the density of hydrobionts have been identified. The increase in the average specific abundance of fish in the upper part of the investigated watercourses to 656.2 specimens·ha-1 was noted, its value is twice higher than that of the whole areas along the delta, whereas the distribution of the average specific biomass was fairly uniform. These patterns were associated with the presence of juveniles of commercial species and small-sized fish species in the upper reaches of rivers. The trends in the spatial distribution of abundance and biomass of decapods were very close. The highest values were observed at the mouths of rivers and the estuary zone of the delta, as the shrimps of the suborder Dendrobrachiata and the crabs of the suborder Pleocyemata appeared in the communities. Among the fish, the representatives of the marine-originated families which belong to Polynemidae, Ariidae, and Engraulidae were dominant. Their share in catches was 39.4, 20.4 and 13.4 % in abundance and 28.5, 34.9 and 9.2 % in biomass, respectively. Euryhaline estuarine and coastal (shelf) species prevailed. Sea shrimps of the families Penaeidae, Aristeidae and freshwater prawn from the family Palaemonidae prevailed among the decapods. Representatives of the Cyprinidae family (the richest in terms of diversity, abundance and biomass in the Mekong Delta) and a number of other freshwater fish, with the exception of Akysidae, were insignificant in abundance, probably due to their migrations in dry season from upstream sections of the river. The influence of some anthropogenic factors on the quantitative indicators of benthic and demersal communities was analyzed. Large amounts of solid domestic and industrial waste, especially from towns, could be one reason for the relatively low average values of density of fish and decapods. This could have a negative impact on feeding and on the life cycles of these hydrobionts in general. Anomalies in the distribution of water salinity and the specific density of fish and crustaceans in the region of the dam on the river Balay were discovered. Upstream from the dam, the water was fresh, whereas, in downstream part, the salinity of the bottom water layer could reach 17 ‰. The average specific abundance of fish was higher in the lower reaches of the dam, and the average specific biomass was higher in the upper dam. The low average specific abundance and biomass of decapod crustaceans were noted there, possibly due to the cessation of spawning migrations of both marine and freshwater shrimps. The obtained results can be used as the basis for subsequent monitoring studies of the structural changes in the bottom communities of fish and decapod crustaceans of the Mekong Delta.

In this study, we investigated the level of contamination of agricultural soil near an old recycling lead smelter in Vietnam and proposed an effective treatment for the remediation of the soil. The analysis of soil samples using an ICP-MS method revealed that the soil in the area was heavily contaminated by heavy metals, especially lead (Pb) with concentrations in surface soil of >3000 μg g−1. High concentrations of metals, including Pb, copper (Cu) and zinc (Zn), were found in whole soil profile. The FE-EPMA and Laser-Raman spectrometer results suggested that iron minerals and carbon materials in the soil are the important hosts of the toxic metals. Subsequently, a series of washing experiment were performed on the soil using biodegradable chelators, including N, N-dicarboxymethyl glutamic acid tetrasodium salt (GLDA), ascorbic acid and citric acid. The results showed that the mixture of GLDA-ascorbic (100 mM: 100 mM) can be considered as a potential candidate for Pb and Zn removal, which removes approximately 90% of Pb and 70% of Zn. Meanwhile, a mixture of GLDA-citric would be preferred for Cu removal based on its greater extraction efficiency compared to other mixtures.

Confirmed by high biodiversity richness of the soil resources of the Dong Nai biosphere reserve as a result of unique natural conditions. Revealed of plants and animals in the Red book of Vietnam and the IUCN Red list. The authors list includes 2.236 species of flora, 121 species of mammals, 373 species of birds and 2.109 species of insect in the biosphere reserve. Described 117 species of plants and animals listed in the Red book of Vietnam and 74 species included in the IUCN Red list. At monitoring sites identified 122 species of birds from 42 families. Of these 72 species are found in natural tropical forest (A, F, LV, LN, PL and PD1) and disturbed (B2 and PD2), 20 species are found only in the primary, 29 species in the anthropogennically transformed. The maximum rates of species richness of oribatid mites characteristic of the natural forest formations and decrease in anthropogenic transformed conditions. In natural forest ecosystems are more diverse species composition and high density of individuals. Identified an inverse relationship between the number of oribatid mites and their species diversity.

There is a need to assess the risk of exposure to metals via roadside dust in Vietnam where many people live along the road/highways and are constantly exposed to roadside dust. In this study, we collected dust samples at 55 locations along two major Highways in north-east Vietnam, which passed through different land use areas. Samples were sieved into three different particle sizes and analyzed for concentrations of eight metals using a X-ray fluorescence instrument. The concentrations and environmental indices (EF, I geo) of metals were used to evaluate the degree of pollution in the samples. Among different land uses, industrial areas could be highly polluted with heavy metals in roadside dust, followed by commerce and power plants. Additionally, the traffic density probably played an important role; higher concentrations were observed in samples from Highway No. 5 where traffic is several times higher than Highway No. 18. According to the risk assessment, Cr poses the highest noncarcinogenic risk even though the health hazard index values of assessed heavy metals in this study were within the acceptable range. Our assessment also found that the risk of exposure to heavy metals through roadside dust is much higher for children than for adults.

Background and Aim Helicobacter pylori can survive long incubation periods under anaerobic conditions, and should be possible to isolate under anaerobic conditions. Our aim was to isolate H. pylori in anaerobic conditions, from gastric biopsies of H. pylori infected patients. Methods We enrolled 27 patients with bleeding (erosive) gastritis (mean age 36.3 years, 55.6% male) from Hanoi, Vietnam. H. pylori status was confirmed by qPCR. Results H. pylori were recovered under anaerobic and micro-aerobic conditions from gastric biopsies in 16 patients. Anaerobic conditions yielded significantly higher H. pylori recovery rates than micro-aerobic conditions (81.3% vs. 31.3%, P = 0.01). H. pylori isolates were characterized by PCR for specific virulence markers and the genotypes were similar to those previously described in this region of the world. Conclusions H. pylori can be isolated under anaerobic conditions. These findings may provide new insight into the physiology of this human pathogen and help to identify the route of H. pylori transmission.

The genus Macrostylopyga gen. nov. and two species (M. grandis sp. nov. and M. bidupi sp. nov.) are described. A detailed morphological description with special attention to the male genitalic structures is provided. Some aspects of the evolution of wingless cockroaches are briefly discussed.

The prevalence of hepatitis B virus (HBV), hepatitis C virus (HCV), and GB virus C or hepatitis G virus (GBV-C/HGV) infections was determined in 289 patients with liver disease in Ho Chi Minh City and 890 healthy inhabitants of its rural area, Dalat City, Vietnam, respectively. Serum HCV RNA and GBV-C/HGV RNA were detected by reverse transcription-polymerase chain reaction (RT-PCR). HBsAg, HCV antibodies, and GBV-C/HGV RNA were detected in 139 (47%), 69 (23%), and ten (3%) subjects, respectively, often accompanied by elevated serum levels of alanine aminotransferase. HBsAg and HCV antibodies or HCV antibodies and GBV-C/HGV RNA were detectable simultaneously in 8% and 2% of the patients, respectively. In the inhabitants, HBsAg, HCV antibodies, and GBV-C/HGV RNA were found in 51 (5.7%), nine (1.0%), and 11 (1.2%) subjects, respectively. Thus, the prevalence of HBsAg, HCV antibodies, and GBV-C/HGV RNA was significantly higher in liver disease patients than those in the general population. In the samples from 69 patients and nine inhabitants who were seropositive for HCV antibodies, HCV RNA was detectable in 42 (61%) and 4 (44%), respectively. In patients with liver disease, ten belonged to HCV genotype 1a, ten to HCV 1b, three to HCV 2a, four to HCV 2b, and two to HCV 3a by PCR with genotype-specific primers. Nine patients had mixed genotypes, and the remaining four were not classified. Of the GBV-C/HGV RNA-positive individuals, two patients and two inhabitants were positive for HBsAg, while none of the residents had HCV antibodies, although six HCV antibodies (60%) and four HCV RNA (40%) were found in patients. When a phylogenetic tree of GBV-C/HGV was constructed based on the nucleotide sequences, the 21 isolates were classified into at least two genotypes; four isolates belonged to G2, and 17 to G3. The results indicate that in Ho Chi Minh HCV infection prevails with broad distribution of genotypes together with HBV infection among patients with liver disease. This study suggests that GBV-C/HGV infection occurs independently in the two different districts in association with HCV infection.

A total of 135 stomach samples from patients with gastrointestinal diseases and normal controls were examined for Helicobacter pylori infection and Candida colonization. Candida krusei was found in specimens from 20% bleeding, 52% ulcer, and 100% gastritis patients, whereas H. pylori infection rates were 82%, 35% and 30%, respectively, for the same groups of patients. C. krusei was not detected in stomach samples from normal controls.

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

The microlens arrays created by ultrasonic waves in acousto-optical material Germanium (Ge) is theoretically proposed. The simulated results show the proposed microlens arrays can be used for optical tweezers arrays to trap an assembly micro-beads. Moreover, with the control by changing of the ultrasonic intensity and frequency, the optical tweezers arrays will act as the dynamical one, which can sieve the beads in (X,Y) plane in the embedding fluid.