| 1. |
- von Seidlein, Lorenz, et al.
(författare)
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The impact of targeted malaria elimination with mass drug administrations on falciparum malaria in Southeast Asia: A cluster randomised trial
- 2019
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Ingår i: PLoS Medicine. - : PUBLIC LIBRARY SCIENCE. - 1549-1277 .- 1549-1676. ; 16:2
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Tidskriftsartikel (refereegranskat)abstract
- Background The emergence and spread of multidrug-resistant Plasmodium falciparum in the Greater Mekong Subregion (GMS) threatens global malaria elimination efforts. Mass drug administration (MDA), the presumptive antimalarial treatment of an entire population to clear the subclinical parasite reservoir, is a strategy to accelerate malaria elimination. We report a cluster randomised trial to assess the effectiveness of dihydroartemisinin-piperaquine (DP) MDA in reducing falciparum malaria incidence and prevalence in 16 remote village populations in Myanmar, Vietnam, Cambodia, and the Lao Peoples Democratic Republic, where artemisinin resistance is prevalent. Methods and findings After establishing vector control and community-based case management and following intensive community engagement, we used restricted randomisation within village pairs to select 8 villages to receive early DP MDA and 8 villages as controls for 12 months, after which the control villages received deferred DP MDA. The MDA comprised 3 monthly rounds of 3 daily doses of DP and, except in Cambodia, a single low dose of primaquine. We conducted exhaustive cross-sectional surveys of the entire population of each village at quarterly intervals using ultrasensitive quantitative PCR to detect Plasmodium infections. The study was conducted between May 2013 and July 2017. The investigators randomised 16 villages that had a total of 8,445 residents at the start of the study. Of these 8,445 residents, 4,135 (49%) residents living in 8 villages, plus an additional 288 newcomers to the villages, were randomised to receive early MDA; 3,790 out of the 4,423 (86%) participated in at least 1 MDA round, and 2,520 out of the 4,423 (57%) participated in all 3 rounds. The primary outcome, P. falciparum prevalence by month 3 (M3), fell by 92% (from 5.1% [171/3,340] to 0.4% [12/2,828]) in early MDA villages and by 29% (from 7.2% [246/3,405] to 5.1% [155/3,057]) in control villages. Over the following 9 months, the P. falciparum prevalence increased to 3.3% (96/2,881) in early MDA villages and to 6.1% (128/2,101) in control villages (adjusted incidence rate ratio 0.41 [95% CI 0.20 to 0.84]; p = 0.015). Individual protection was proportional to the number of completed MDA rounds. Of 221 participants with subclinical P. falciparum infections who participated in MDA and could be followed up, 207 (94%) cleared their infections, including 9 of 10 with artemisinin-and piperaquine- resistant infections. The DP MDAs were well tolerated; 6 severe adverse events were detected during the follow-up period, but none was attributable to the intervention. Conclusions Added to community-based basic malaria control measures, 3 monthly rounds of DP MDA reduced the incidence and prevalence of falciparum malaria over a 1-year period in areas affected by artemisinin resistance. P. falciparum infections returned during the follow-up period as the remaining infections spread and malaria was reintroduced from surrounding areas. Limitations of this study include a relatively small sample of villages, heterogeneity between villages, and mobility of villagers that may have limited the impact of the intervention. These results suggest that, if used as part of a comprehensive, well-organised, and well-resourced elimination programme, DP MDA can be a useful additional tool to accelerate malaria elimination.
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| 2. |
- Hoang-Minh, Thao, et al.
(författare)
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Mineralogical Characterization of Di Linh Bentonite, Vietnam: A Methodological Approach of X-ray Diffraction and Transmission Electron Microscopy
- 2014
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Ingår i: Proceedings of 13th International Symposium on Mineral Exploration (ISME-XIII). - Hanoi : Vietnam National University Press, Hanoi. - 9786046215400 ; , s. 143-148
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Konferensbidrag (refereegranskat)abstract
- Vietnam has decided to establish nuclear power as further energy option. In order to develop a Vietnamese reference bentonite as potential barrier in a final repository for high radioactive waste, a detailed mineralogical investigation of Di Linh bentonite (Lam Dong province), lacustrine clay, was carried out by different methods especially transmission electron microscopy (TEM) linked with energy-dispersive X-ray (EDX). From a sample homogenized from 5 tones of the bentonite, mineral formulae of clay particles was calculated The calculation also focuses on randomly interstratifications of two and three members. The fraction <2 μm of Di Linh bentonite is composed mainly by montmorillonite (Ca0.06Mg0.03Na0.09K0.03Al1.39Fe0.25Mg0.26(OH)2 Si3.96Al0.04O10) and regular ordering (R1) illite-smectite interstratifications with K- and charge-deficiency (Ca0.04Mg0.07Na0.18K0.16Al1.76Fe0.08Mg0.16(OH)2Si3.62Al0.38O10). Additionally, Fe-poor kaolinite-smectite-vermiculite interstratifications and trace of Fe-rich chloritesmectite- vermiculite interstatifications were identified. TEM-investigations showed analytical proofs of the sedimentary character of smectite formation in the Di Linh deposit. Parent muscovite was weathered in several steps in two different environments: (i) K-leaching and layer-wise alteration into kaolinite; (ii) further edge- controlled alteration of mica into lathlike montmorillonite particles under dissolution of kaolinite layers from former kaolinite-mica intergrowths. Mineralogical composition of the Di Linh bentonite with mainly montmorillonite and illite-rich illite-smectite interstratifications shows that the Di Linh bentonite can be a suitable barrier candidate in final repositories.
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| 3. |
- Hoang-Minh, Thao, et al.
(författare)
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Use of TEM-EDX for structural formula identification of clay minerals : a case study of Di Linh bentonite, Vietnam
- 2019
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Ingår i: Journal of applied crystallography. - : International Union of Crystallography (IUCr). - 0021-8898 .- 1600-5767. ; 52:1, s. 133-147
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Tidskriftsartikel (refereegranskat)abstract
- Transmission electron microscopy linked with energy-dispersive X-ray spectroscopy (TEM-EDX) was applied to characterize mineralogical signals ofweathering processes in the Di Linh bentonite deposit (Vietnam) and to visualize the effects of Na activation on the smectitic phases. Modelling of X ray diffraction patterns (oriented mount) was applied in order to refine the computed structural formula. X-ray diffraction, X-ray fluorescence and Fouriertransform infrared spectroscopy (FT-IR) methods were also applied to verify the TEM-EDX results. An Excel-based routine has been developed in this research to allow fast computation of structural formulae and classification of the investigated clay particles. This routine supports the acquirement of 100 300 TEM-EDX analyses as a representative set of individual particles for each sample. The Excel-based routine involves end members of different clay mineral groups and interstratifications with two or three members (e.g. illite smectite interstratifications – IS-ml; dioctahedral vermiculite–smectite interstratifications – diVS-ml; and kaolinite–montmorillonite–dioctahedral vermiculite interstratifications – KSV-ml). The routine is now freely available. According to the identification procedure, the <2 mm fraction of the Di Linh bentonite (Vietnam) is composed mainly of K- and charge-deficient illite smectite interstratifications (or diVS-ml): montmorillonite-rich randomly ordered (R0) type and illite-rich regularly ordered (R1) type. Additionally, Fe-poor KSV-ml was identified.Industrial Na activation of the Di Linh bentonite resulted in an increase of theR1 diVS-ml portion and dissolution of a large part of the smectite-rich phases.The TEM-EDX approach also gave analytical proof of a sedimentary processfor Di Linh smectite. The parent muscovite was altered in two different environments: (i) K-leaching and layer-wise alteration into kaolinite (weathering), and (ii) further edge-controlled alteration of mica into lath-like montmorillonite particles associated with a dissolution of kaolinite layers from the former kaolinite–mica intergrowths by heat impact (basalt flow).
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| 4. |
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| 5. |
- Pham-Thanh, Long, et al.
(författare)
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Dogs as Sentinels for Flavivirus Exposure in Urban, Peri-Urban and Rural Hanoi, Vietnam
- 2021
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Ingår i: Viruses. - : MDPI. - 1999-4915. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- Diseases caused by flaviviruses, including dengue fever and Japanese encephalitis, are major health problems in Vietnam. This cross-sectional study explored the feasibility of domestic dogs as sentinels to better understand risks of mosquito-borne diseases in Hanoi city. A total of 475 dogs serum samples from 221 households in six districts of Hanoi were analyzed by a competitive enzyme-linked immunosorbent assay (cELISA) for antibodies to the pr-E protein of West Nile virus and other flaviviruses due to cross-reactivity. The overall flavivirus seroprevalence in the dog population was 70.7% (95% CI = 66.4-74.8%). At the animal level, significant associations between seropositive dogs and district location, age, breed and keeping practice were determined. At the household level, the major risk factors were rural and peri-urban locations, presence of pigs, coil burning and households without mosquito-borne disease experience (p < 0.05). Mosquito control by using larvicides or electric traps could lower seropositivity, but other measures did not contribute to significant risk mitigation of flavivirus exposure in dogs. These results will support better control of mosquito-borne diseases in Hanoi, and they indicate that dogs can be used as sentinels for flavivirus exposure.
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| 6. |
- Thanh Hoan, Nguyen, et al.
(författare)
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Novel Time Series Bagging Based Hybrid Models for Predicting Historical Water Levels in the Mekong Delta Region, Vietnam
- 2022
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Ingår i: CMES - Computer Modeling in Engineering & Sciences. - : Tech Science Press. - 1526-1492 .- 1526-1506. ; 131:3, s. 1431-1449
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Tidskriftsartikel (refereegranskat)abstract
- Water level predictions in the river, lake and delta play an important role in flood management. Every year Mekong River delta of Vietnam is experiencing flood due to heavy monsoon rains and high tides. Land subsidence may also aggravate flooding problems in this area. Therefore, accurate predictions of water levels in this region are very important to forewarn the people and authorities for taking timely adequate remedial measures to prevent losses of life and property. There are so many methods available to predict the water levels based on historical data but nowadays Machine Learning (ML) methods are considered the best tool for accurate prediction. In this study, we have used surface water level data of 18 water level measurement stations of the Mekong River delta from 2000 to 2018 to build novel time-series Bagging based hybrid ML models namely: Bagging (RF), Bagging (SOM) and Bagging (M5P) to predict historical water levels in the study area. Performances of the Bagging-based hybrid models were compared with Reduced Error Pruning Trees (REPT), which is a benchmark ML model. The data of 19 years period was divided into 70:30 ratio for the modeling. The data of the period 1/2000 to 5/2013 (which is about 70% of total data) was used for the training and for the period 5/2013 to 12/2018 (which is about 30% of total data) was used for testing (validating) the models. Performance of the models was evaluated using standard statistical measures: Coefficient of Determination (R2), Root Mean Square Error (RMSE) and Mean Absolute Error (MAE). Results show that the performance of all the developed models is good (R2 > 0.9) for the prediction of water levels in the study area. However, the Bagging-based hybrid models are slightly better than another model such as REPT. Thus, these Bagging-based hybrid time series models can be used for predicting water levels at Mekong data.
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| 7. |
- Dai, Heng, et al.
(författare)
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Finned zeolite catalysts
- 2020
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Ingår i: Nature Materials. - : Springer Science and Business Media LLC. - 1476-1122 .- 1476-4660. ; 19:10, s. 1074-1080
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Tidskriftsartikel (refereegranskat)abstract
- Nanosized zeolites enable better catalytic performance; however, their synthesis is non-trivial. Here, a simple treatment is presented that enables the growth of nanosized fins on zeolites that act as pseudo-nanoparticles, reducing deactivation rates for methanol-to-hydrocarbon catalysis. There is growing evidence for the advantages of synthesizing nanosized zeolites with markedly reduced internal diffusion limitations for enhanced performances in catalysis and adsorption. Producing zeolite crystals with sizes less than 100 nm, however, is non-trivial, often requires the use of complex organics and typically results in a small product yield. Here we present an alternative, facile approach to enhance the mass-transport properties of zeolites by the epitaxial growth of fin-like protrusions on seed crystals. We validate this generalizable methodology on two common zeolites and confirm that fins are in crystallographic registry with the underlying seeds, and that secondary growth does not impede access to the micropores. Molecular modelling and time-resolved titration experiments of finned zeolites probe internal diffusion and reveal substantial improvements in mass transport, consistent with catalytic tests of a model reaction, which show that these structures behave as pseudo-nanocrystals with sizes commensurate to that of the fin. This approach could be extended to the rational synthesis of other zeolite and aluminosilicate materials.
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| 8. |
- Duy, Nguyen Van, et al.
(författare)
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Enhancement of NH3 gas sensing with Ag-Pt co-catalyst on SnO2 nanofilm towards medical diagnosis
- 2023
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 767
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Tidskriftsartikel (refereegranskat)abstract
- Exhaled breath analysis is a noninvasive diagnostic method for fatal disease monitoring and screening, which is recently gained extensive interest of researchers worldwide emphasizing on the development of effective chemiresistive gas sensor for practical application. Here, the Ag-Pt bimetallic nanoparticles were used to deco-rate nanofilms of SnO2 making different gas sensors with high performance. We found that the bimetal alloy improved the sensor performance significantly with super sensitivity as compared with the separate Ag and Pt catalyst. The right ratio of the bimetal made the sensor very sensitive to NH3, so that it was able to quickly (12 s) detect 1 parts-per-million of NH3 with a response of 4.31 at a temperature of 250 degrees C. The sensor limit of detection for NH3 was less than 10 parts-per-billion. The response of the sensor was negligibly affected by humidity and interfering gases. The results showed that the tiny, robust, and inexpensive sensor developed in this work can be used in breath analysis for early diagnosis via NH3 monitoring.
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