In January 2020, we identified two severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2)‐infected patients in a familial cluster with one person coming from Wuhan, China. The complete genome ...sequences of two SARS‐CoV‐2 strains isolated from these patients were identical and 99.98% similar to strains isolated in Wuhan. This is genetically suggestive of human‐to‐human transmission of SARS‐CoV‐2 and indicates Wuhan as the most plausible origin of the early outbreak in Vietnam. The younger patient had a mild upper respiratory illness and a brief viral shedding, whereas the elderly with multi‐morbidity had pneumonia, prolonged viral shedding, and residual lung damage. The evidence of nonsynonymous substitutions in the ORF1ab region of the viral sequence warrants further studies.
Highlights
Transmission of SARS‐CoV‐2 is a global public health and clinical concern.
This report describes clinical features, virus isolation, and complete genome sequences from the first two SARS‐CoV‐2 infections in Vietnam.
Epidemiological and phylogenetic analysis suggested evidence of human‐to‐human transmission of SARS‐CoV‐2. Comparison of SARS‐CoV‐2 strains isolated from these two patients with those from Wuhan showed high similarities.
Nonsynonymous substitutions existed in the ORF1ab region of the viral sequence.
Compared with mild clinical and virological manifestations in the younger patient, the elderly suffered from pneumonia, prolonged viral shedding, and residual lung damage.
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•Critical role of surface chemistry in dewatering the fine clay tailings.•Proposal of a two-step procedure of charge neutralization and flocculation.•Combining alum coagulant, ...salt-resistant flocculant and centrifugation for efficient solid-liquid separation.•A novel hybrid solid-liquid separation technique for safer, cleaner and more sustainable coal tailings disposals.
Solid-liquid separation to dewater mine tailings is critical to transforming tailings dams that are hazardous to the environment and surrounding communities into safer and sustainable disposal storages by dry stacking and co-disposals. Current tailings dewatering by thickening and filtration has experienced big challenges due to the presence of fine clay minerals with complex surface properties and gelation caused by their swelling characteristics. They retain water in their structure, settle very slowly in thickeners, and pass through filter media during filtration. Here, we have systematically investigated the effect of clay mineral surface chemistry on settling, flocculation, and dewatering using pure clay samples and coal tailings samples. Our results indicate the critical role of clay surface charge in the successful dewatering of the clay samples. A two-step procedure including neutralizing the clay surface charge by salts and then flocculating by salt-resistant flocculants can be significantly effective in the dewatering. The newly-developed dewatering technique by combining chemical reagents and mechanical force of solid bowl centrifugation can deliver successful dewatering outcomes by achieving the required final moisture of dewatered tailings and providing improved water quality for recycling. This paper highlights the importance of clay surface chemistry in controlling clay interactions with chemical reagents, and solid-liquid separation to dewater the clay-rich tailings inherently present in the mining industry.
Spatiotemporal analysis and monitoring of vegetation help us investigate ecological health and guide better forest conservation and land management practices for sustainable development. This paper ...proposes the use of spatial analysis approaches (i.e., ordinary least squares OLS and the Hurst exponent) combined with time‐series analysis using enhanced vegetation index (EVI) data, derived from LANDSAT via the Google Earth Engine, to estimate the trends and sustainability of vegetation dynamics in the Tra Vinh Province in the Mekong River Delta. We also assessed the EVI changes connected to land change issues to examine the influence of land use conversion on vegetation dynamics. Results show that a large portion of the study area was covered by abundant vegetation (over 50% of the total area), and the increased EVI area was about 5.5‐times greater than the area of EVI reduction. Additionally, vegetation sustainability was being seriously compromised (e.g., a decrease in the total area of 8,275 ha) due to several land conversion drivers such as shrimp farming, urbanisation, and industrialisation. Furthermore, results obtained from this research provide insight into the spatiotemporal dynamics of vegetation coverage and reveal the consistency of future vegetation trends. Moreover, the study also quantitatively assessed the positive impacts of Buddhist doctrines on reducing the negative trend of vegetation change in the study area. These findings can lay the ground to formulate sustainable land and environmental plans that meet the 11th, 13th and 15th Sustainable Development Goals (SDGs) (i.e., the sustainable cities and communities, the climate actions, and the life on land). Besides, the analytical procedure adopted in this study can also be applicable to any other coastal areas that require the accurate assessment of vegetation status over time.
Using a multivariate drought index that incorporates important environmental variables and is suitable for a specific geographical region is essential to fully understanding the pattern and impacts ...of drought severity. This study applied feature scaling algorithms to MODIS time-series imagery to develop an integrated Multivariate Drought Index (iMDI). The iMDI incorporates the vegetation condition index (VCI), the temperature condition index (TCI), and the evaporative stress index (ESI). The 54,474 km
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Vietnamese Central Highlands region, which has been significantly affected by drought severity for several decades, was selected as a test site to assess the feasibility of the iMDI. Spearman correlation between the iMDI and other commonly used spectral drought indices (i.e. the Drought Severity Index (DSI-12) and the annual Vegetation Health Index (VHI-12)) and ground-based drought indices (i.e. the Standardized Precipitation Index (SPI-12) and the Reconnaissance Drought Index (RDI-12)) was employed to evaluate performance of the proposed drought index. Pixel-based linear regression together with clustering models of the iMDI time-series was applied to characterize the spatiotemporal pattern of drought from 2001 to 2020. In addition, a persistent area of LULC types (i.e. forests, croplands, and shrubland) during the 2001-2020 period was used to understand drought variation in relation to LULC. Results suggested that the iMDI outperformed the other spectral drought indices (r > 0.6; p < 0.005). The analysis revealed an increase in drought risk in some provinces of the Central Highlands including Gia Lai, Kon Tum, and Dak Lak. It was also found that changes in LULC patterns could minimize (reforestation) or exacerbate (deforestation) the impacts of drought. Our study suggests that applying a multivariate drought index enables a better understanding of drought patterns at the local scale. This provides valuable information for the development of appropriate land and environmental management practices that can affect and mitigate climate change effects.
Vietnam has emerged as one of the world's leading success stories in responding to COVID-19. After a prolonged period of little to no transmission, there was an outbreak of unknown source in July, ...2020, in the Da Nang region, but the outbreak was quickly suppressed. We aimed to use epidemiological, behavioural, demographic, and policy data from the COVID-19 outbreak in Da Nang to calibrate an agent-based model of COVID-19 transmission for Vietnam, and to estimate the risk of future outbreaks associated with reopening of international borders in the country.
For this modelling study, we used comprehensive data from June 15 to Oct 15, 2020, on testing, COVID-19 cases, and quarantine breaches within an agent-based model of SARS-CoV-2 transmission to model a COVID-19 outbreak in Da Nang in July, 2020. We applied this model to quantify the risk of future outbreaks in Vietnam in the 3 months after the reopening of international borders, under different behavioural scenarios, policy responses (ie, closure of workplaces and schools), and ongoing testing.
We estimated that the outbreak in Da Nang between July and August, 2020, resulted in substantial community transmission, and that higher levels of symptomatic testing could have mitigated this transmission. We estimated that the outbreak peaked on Aug 2, 2020, with an estimated 1060 active infections (95% projection interval 890–1280). If the population of Vietnam remains highly compliant with mask-wearing policies, our projections indicate that the epidemic would remain under control even if a small but steady flow of imported infections escaped quarantine into the community. However, if complacency increases and testing rates are relatively low (10% of symptomatic individuals are tested), the epidemic could rebound again, resulting in an estimated 2100 infections (95% projected interval 1050–3610) in 3 months. These outcomes could be mitigated if the behaviour of the general population responds dynamically to increases in locally acquired cases that exceed specific thresholds, but only if testing of symptomatic individuals is also increased.
The successful response to COVID-19 in Vietnam could be improved even further with higher levels of symptomatic testing. If the previous approaches are used in response to new COVID-19 outbreaks, epidemic control is possible even in the presence of low levels of imported cases.
Ministry of Science and Technology (Vietnam).
For the Vietnamese translation of the abstract see Supplementary Materials section.
Drought is a complex natural hazard which can create significant impacts on society and environment. Given that this phenomenon varies across space and changes over time dependent on various factors ...(e.g., physical conditions and human activities), the available of spatiotemporal drought data enables a better monitoring and assessment of drought severity This study introduced the integrated multivariate drought index (iMDI) data, a new regional drought index, at 1 km spatial and monthly temporal resolutions for the Vietnamese Central Highlands over a 20-years period. The iMDI was developed recently which is a combination of vegetation condition index (VCI), the temperature condition index (TCI), and the evaporative stress index (ESI) based on the feature of scaling algorithms (i.e., normalisations and standardisation). The data were processed using the median values of MODIS time-series imagery obtained from the Google Earth Engine (GEE) platform. The iMDI datasets are available for monthly and annual drought monitoring between 2001 and 2020. Additionally, the datasets of VCI, TCI, and ESI were provided so that users can apply for their own purposes even though these data can directly obtain from GEE or other sources. Users, especially those without technical expertise, can reap the advantages of having open access to iDMI data. By doing so, they can reduce their expenses and the time required to process data. As such, this accessibility can promote the use of data for diverse applications, such as evaluating the impact of droughts on the environment and human activities and monitoring droughts regionally.
Article Note: Manh H. Dao and Hieu T. Nguyen contributed equally to this study and are joint first authors. CAPTION(S): Supplementary information. Byline: Guangxiang (George) Luo, Hinh Ly, Shou-Jiang ...Gao, Manh H. Dao, Hieu T. Nguyen, Thinh V. Nguyen, Anh H. Nguyen, Quang C. Luong, Nhung H. P. Vu, Hang T. T. Pham, Thao N. T. Nguyen, Dung H. Thach, Lo V. Nguyen, Luan V. Bui, Hang M. Nguyen, Loan K. T. Huynh, Long T. Nguyen, Thang M. Cao, Quang D. Pham, Thuong V. Nguyen, Lan T. Phan
Genome‐wide analysis of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) strains is essential to better understand infectivity and virulence and to track coronavirus disease 2019 ...(COVID‐19) cases and outbreaks. We performed whole‐genome sequencing of 27 SARS‐CoV‐2 strains isolated between January 2020 and April 2020. A total of 54 mutations in different genomic regions was found. The D614G mutation, first detected in March 2020, was identified in 18 strains and was more likely associated with a lower cycle threshold (<25) in real‐time reverse‐transcription polymerase chain reaction diagnostic tests than the original D614 (prevalence ratio = 2.75; 95% confidence interval, 1.19–6.38). The integration of sequencing and epidemiological data suggests that SARS‐CoV‐2 transmission in both quarantine areas and in the community in Vietnam occur at the beginning of the epidemic although the country implemented strict quarantine quite early, with strict contact tracing, and testing. These findings provide insights into the nature of the epidemic, as well as shape strategies for COVID‐19 prevention and control in Vietnam.
•Developing XCT methodology to obtain characteristics of density separation.•Applying XCT methodology to describe partition curves for DMCs.•Analysing XCT images to obtain key properties of ...individual particles.•Determining mass yield using mass reconciliation to build partition curves.•Advantages of XCT technology over traditional float-and-sink analysis.
The partition curve is an important tool to evaluate the separation performance of mineral separators like dense medium cyclones (DMCs). This curve is constructed by float-and-sink (FaS) analysis which involves the use of heavy liquids and suspensions. This traditional technique is hazardous to the environment, laborious, and time-consuming. Here, a new technique using X-ray computed tomography (XCT) scanning was successfully developed and applied for describing the partition curve of a DMC at an Australia-based lead–zinc mineral processing plant. The DMC feed, concentrate and reject streams were sampled and sieved into several size classes. The chemical assays and averaged densities according to each class were analysed by X-ray fluorescence spectrometry and gas pycnometry, respectively. The partition behaviour was investigated by XCT analysis. A model was proposed to determine the mass yield value – an important parameter to define partition curves – by mass balance and reconciliation, which is generally unknown during the sampling of continuous separation processes. From the reconstructed XCT images, we obtained detailed information on individual particles such as volume, surface area, mass, and density. Cumulative mass distribution curves and partition curves of the DMC for different size classes were then constructed and agreed with the FaS analysis. Using the XCT technology can help overcome the issues of the traditional FaS analysis. Moreover, this technology would allow for evaluating DMC separation efficiency with continuous, online, and real-time monitoring and control.
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