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Advances in sequencing technologies and bioinformatics have led to breakthroughs in the study of virus biodiversity. Millipedes (Diplopoda, Myriapoda, Arthropoda) include more than 12,000 extant species, yet data on virus diversity in Diplopoda are scarce. This study aimed to explore the virome of the millipedes collected in the Dong Nai Biosphere Reserve in Vietnam. We studied 14 species of millipedes and managed to assemble and annotate the complete coding genomes of 16 novel viruses, the partial coding genomes of 10 more viruses, and several fragmented viral sequences, which may indicate the presence of about 54 more viruses in the studied samples. Among the complete and partial genomes, 27% were putative members of the order Picornavirales. Most of the discovered viruses were very distant from the viruses currently present in the relevant databases. At least eight viruses meet the criteria to be recognized as a new species by the International Committee on Taxonomy of Viruses, and, for two of them, a higher taxonomic status (genus and even family) can be suggested.

Many studies report asymmetrical spatial distribution of soil respiration caused by presence of areas with significantly higher emission rates (so-called hot spots). For seasonally dry tropical forest soil respiration was measured on 1 ha plot with 20m, 5m and 1 m scale in the first half of dry season. 457 measurements made in 9 series at 54 sampling points. The results suggest that lognormal spatial distribution model appears to be much more supported rather than the normal one. A statistical method proposed for estimation the mean value and its confidence interval of lognormally distributed data. The mean emission rate E(RS) for the lognormal distribution amounted to 4.28 µmol m-2 s-1, the 95% confidence interval is 3.93 to 4.76 µmol m-2 s-1. However, the standard sample mean can be used as an estimator of the mean of lognormally distributed values of soil respiration if their coefficient of variance remains approximately the same as in our study (CV=0.35). Based on the data obtained and literature sources, recommendations are given on the number of sampling points for estimating the spatial average value with a given accuracy.

Vật liệu BaTiO3 nano hình cầu phân tán cao với kích thước đồng đều được tổng hợp bằng phương pháp thủy nhiệt. Ảnh hưởng của tỉ lệ mol Ba/Ti lên sự hình thành vật liệu được nghiên cứu bằng cách phân tích dữ liệu XRD và SEM. TiO2·nH2O tổng hợp bằng phương pháp axit sunfuric với sự hỗ trợ sóng siêu âm được sử dụng làm nguyên liệu ban đầu. Vật liệu nano BaTiO3 hình cầu với độ phân tán cao và kích thước trung bình khoảng 100 nm đã thu được tại 200 °C trong 12 giờ với tỉ lệ Ba/Ti = 1,5. Tỷ lệ Ba/Ti ảnh hưởng mạnh đến sự hình thành BaTiO3 nano hình cầu với quá trình chuyển pha. Khi tăng tỉ lệ Ba/Ti, kích thước hạt tăng và tính đồng nhất giảm.

Trong bài báo này, sợi nano bạc đã được tổng hợp bằng phương pháp polyol dưới tác động của siêu âm. Đã xác định được nồng độ tối ưu của polyvinyl pyrrolidone cho quá trình chế tạo dung dịch. Sản phẩm sợi nano được khảo sát bằng kỹ thuật XRD, SEM và UV-Vis. Dung dịch dẫn điện có điện trở thấp, bám dính tốt, tính linh hoạt cao và ổn định nhiệt. Dung dịch này đã được sử dụng để chế tạo màng dẫn điện. Sản phẩm có thể mở ra một hướng mới cho các ứng dụng công nghệ sau này.

Modern metagenomic approaches enable the effective discovery of novel viruses in previously unexplored organisms. Termites are significant ecosystem converters and influencers. As with the majority of tropical forest insects, termites are studied insufficiently, and termite virome remains especially understudied. Here, we studied the virome of lichenophagous and mycophagous termites (Hospitalitermes bicolor, Macrotermes carbonarius and Odontotermes wallonensis) collected in the Cat Tien National Park (Vietnam). We assembled four full genomes of novel viruses related to Solemoviridae, Lispiviridae, Polycipiviridae and Kolmioviridae. We also found several contigs with relation to Chuviridae and Deltaflexiviridae that did not correspond to complete virus genomes. All the novel viruses clustered phylogenetically with previously identified viruses of the termites. Deltaflexi-like contigs were identified in the fungi-cultivating M. carbonarius and showed homology with viruses recently discovered in the edible basidiomycete mushrooms.

Khe Cham coal mine is managed by Ha Long Coal Company TKV. Currently, Khe Cham coal mine is exploited from the ground up to 350 and is ranked III for methane. In 2008, a methane explosion at -168 level of the 13.2 coal seam of Khe Cham coal mine occurred, injuring 16 people and killing 8. In order to avoid gas explosions at mines like 2008, it is necessary to have appropriate solutions to eliminate methane accumulation in the pit paths. We have studied to determine the relationship between the level of methane emissions with the methane content in the coal seam and the bazaar’s mining output because of the methane content in the coal seam and coal mining output. These are the two factors that greatly affect the release of methane from the longwall. The paper used practical measurement, sampling, and analysis methods to determine the level of methane emissions from longwalls at different extraction levels of the 13.2 coal seam and determine the relationship between the methane drainage and the methane content in the coal seam and the exploitation output of the longwall. This relationship is expressed by the equation y = a.x2 + b.x + c (Fig. 2 and Fig. 3). The results will help with planning for mining and have specific solutions for diluting methane in the mine’s pit lines

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 > 20%).

The effects of disturbance regimes on the spatial patterns of the five most abundant species were investigated in three sites in a tropical forest at Xuan Nha Nature Reserve, Vietnam. Three permanent one-ha plots were established in undisturbed forest (UDF), lightly disturbed forest (LDF), and highly disturbed forest (HDF). All trees ≥5 cm DBH were measured in twenty-five 20 m × 20 m subplots. A total of 57 tree species belonging to 26 families were identified in the three forest types. The UDF had the highest basal area (30 m2 ha−1), followed by the LDF (17 m2 ha−1) and the HDF (13.0 m2 ha−1). The UDF also had the highest tree density (751 individuals ha−1) while the HDF held the lowest (478 individuals ha−1). Across all species, there were 417 “juveniles,” 267 “subadults,” and 67 “adults” in the UDF, while 274 “juveniles,” 230 “subadults,” and 36 “adults” were recorded in the LDF. 238 “juveniles,” 227 “subadults,” and 13 “adults” were obtained in the HDF. The univariate and bivariate data with pair- and mark-correlation functions of intra- and interspecific interactions of the five most abundant species changed in the three forest types. Most species indicated clumping or regular distributions at small scale, but a high ratio of negative interspecific small-scale associations was recorded in both the LDF and HDF sites. These were, however, rare in the UDF.

Harvest residues can play a crucial role in conserving nutrients for recycling in forests, but little is known about the rates of decomposition and nutrient release from these residues following logging in tropical acacia plantations. In this study, we examined the biomass and nutrient content of harvest residue components (bark, leaves, and branches) using the litterbag technique for a 1.5-year-period following harvest of a seven-year-old Acacia mangium plantation in Northern Vietnam. At harvest, the total dry biomass of harvest residues was 18 t ha−1 comprising bark (8.9 t ha−1), branches (6.6 t ha−1), and leaves (2.5 t ha−1). The retained bark on site conserved 51% N, 29% P, 32% K, 64% Ca, and 24% Mg content from harvest residues for recycling. Decomposition rate of the leaves was the most rapid (k = 1.47 year−1; t0.5 = 0.47 year), then branches (k = 0.54 year−1; t0.5 = 1.29 year), and bark (k = 0.22 year−1; t0.5 = 3.09 year). During decomposition, the loss of nutrients from harvest residues was K ≈ Ca > N > P> Mg. Decomposition of harvest residues and the associated rate of nutrient release can potentially supply a significant amount of nutrients required for stand development in the next rotation.

Methane hazard has always been considered for underground coal mining as it can lead to methane explosion. In Quang Ninh province, several coal mines such as Mạo Khe coal mine, Khe Cham coal mine, especially Duong Huy mine that have high methane content. Experimental data to examine contents of methane bearing coal seams at different depths are not similar in Duong coal mine. In order to ensure safety, this report has been undertaken to determine a pattern of changing methane contents of coal seams at different exploitation depths in Duong Huy underground coal mine.

Expeditionary studies of the functioning of landscapes of mid-mountain monsoon (including fog) forests have been being conducted within the landscape and ecological station in the territory of the Bidoup-Nui Ba National Park and the adjacent Hon Giao since 2018 and are currently underway. One of the research objectives is to clarify the biogeochemical migrations of the material composition of soils in the "leaf debris–soil" system. We have consistently studied natural objects for their material composition as well as the intensity and rate of involvement of chemical elements in physicochemical migration processes in the "leaf debris–soil" system. Our findings indicate an active influx of a select group of examined elements (Se, Pd, Ag, Cd, Sn, Bi), particularly Bi, Pd, Se, and Cd, through the leaf debris and the detachment of aboveground plant organs, warranting their integration into organogenic soil horizons. Subsequently, lateral migration (Pd, Cd, Se) ensues. Slope processes within subordinate landscape facets, in addition to soil moisture and aeration processes, contribute to the subsequent redistribution of elemental volumes introduced into organogenic soil horizons. [ABSTRACT FROM AUTHOR]

In this paper, the Local Fractional Laplace Decomposition Method (LFLDM) is used for solving a type of Two-Dimensional Fractional Diffusion Equation (TDFDE). In this method, first we apply the Laplace transform and its inverse to the main equation, and then the Adomian decomposition is used to obtain approximate/analytical solution. The accuracy and applicability of the LFLDM is shown through two examples. The LFLDM results are in good agreement with the exact solution of the problems. [ABSTRACT FROM AUTHOR]

In this paper, we use the local fractional variational iteration transform method LFVITM to solve a class of linear and nonlinear partial differential equations (PDEs), as well as a system of PDEs which are involving local fractional differential operators (LFDOs). The technique combines the variational iteration transform approach and the Yang–Laplace transform. To show how effective and precise the LFVITM four examples are given. [ABSTRACT FROM AUTHOR]

This study explores and tests the different factors affecting the revisit intentions of visitors to spiritualcultural tourist destinations in Vietnam. A sample of 460 tourists participated in the study, which used AMOS software to test the relationship between the constructs and evaluate their reliability and validity. The research findings confirm that tourist satisfaction helps mediate the relationship between each emotional factor and visitors' intentions to revisit spiritual-cultural sites. Four factors influencing tourist satisfaction in Vietnam are: (1) individual learning and research needs; (2) personal preference; (3) perceived value of site; and (4) religious belief. The findings from the tests in variances indicate that the strength of the relationship between visitor satisfaction and revisit intention was different across male and female groups and stronger in female groups. Based on these findings, the paper gives recommendations for destination management organisations about how to better exploit cultural and spiritual tourism products, thus, diversifying tourism products and increasing their perceived value. Such measures will soon expand the spiritual-tourism destination choices of tourists. [ABSTRACT FROM AUTHOR]

The non-destructive sampling method is an urgent need in forestry applications since it allows sampled trees to be alive and continue growing. 3D scanning technique was used in this study for images of 92 sampling trees of Pterocarpus macrocarpus, Cassia siamea and Dipterocarpus dyeri, which were used for calculating stem height (H), diameter at breast height (DBH), volume and then transferred to aboveground biomass (AGB) through known wood density. Allometric equations of individual species and mixed species were fitted by using an only DBH model, a DBH and H model in the form of power and logarithm. The best fitted models were selected based on AIC, Adjusted R2, residual standard error, and deviation of the predicted versus measured total AGB. By using an only DBH model, the best fitted for individual species was AGB = a + 1•DBH2 with R2 of 0.596-0.954 and Log (AGB) = a + 1•Log (DBH) with R2 of 0.855 for mixed species. While using DBH and H model, the best fitted for both individual species and mixed species was Log (AGB) = a + 1 •Log (DBH2•H) with R2 of 0.810-0.958. In cases, H is unable to measure accurately, it is recommended to use an only DBH model. While the mixed model can be extended to apply to other species, which have similar ecological and growth characteristics, especially for tree species in the same genera and families. [ABSTRACT FROM AUTHOR]