| 1. |
- Duoc, Vo Thanh, et al.
(författare)
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New Design of ZnO Nanorod- and Nanowire-Based NO2 Room-Temperature Sensors Prepared by Hydrothermal Method
- 2019
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Ingår i: Journal of Nanomaterials. - : HINDAWI LTD. - 1687-4110 .- 1687-4129.
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Tidskriftsartikel (refereegranskat)abstract
- Room-temperature gas sensors are attracting attention because of their low power consumption, safe operation, and long-term stability. Herein, ZnO nanorods (NRs) and nanowires (NWs) were on-chip grown via a facile hydrothermal method and used for room-temperature NO2 gas sensor applications. The ZnO NRs were obtained by a one-step hydrothermal process, whereas the NWs were obtained by a two-step hydrothermal process. To obtain ZnO NW sensor, the length of NRs was controlled short enough so that none of the nanorod-nanorod junction was made. Thereafter, the NWs were grown from the tips of no-contact NRs to form nanowire-nanowire junctions. The gas-sensing characteristics of ZnO NRs and NWs were tested against NO2 gas at room temperature for comparison. The gas-sensing characteristics of the sensors were also tested at different applied voltages to evaluate the effect of the self-activated gas-sensing performance. Results show that the diameter of ZnO NRs and NWs is the dominant parameter of their NO2 gas-sensing performance at room temperature. In addition, self-activation by local heating occurred for both sensors, but because the NWs were smaller and sparser than the NRs, local heating thus required a lower applied voltage with maximal response compared with the NRs.
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| 2. |
- 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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| 3. |
- Phu, Vu Dinh, et al.
(författare)
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Burden of Hospital Acquired Infections and Antimicrobial Use in Vietnamese Adult Intensive Care Units
- 2016
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Vietnam is a lower middle-income country with no national surveillance system for hospital-acquired infections (HAIs). We assessed the prevalence of hospital-acquired infections and antimicrobial use in adult intensive care units (ICUs) across Vietnam. Methods Monthly repeated point prevalence surveys were systematically conducted to assess HAI prevalence and antimicrobial use in 15 adult ICUs across Vietnam. Adults admitted to participating ICUs before 08: 00 a.m. on the survey day were included. Results Among 3287 patients enrolled, the HAI prevalence was 29.5% (965/3266 patients, 21 missing). Pneumonia accounted for 79.4% (804/1012) of HAIs Most HAIs (84.5% [855/1012]) were acquired in the survey hospital with 42.5% (363/855) acquired prior to ICU admission and 57.5% (492/855) developed during ICU admission. In multivariate analysis, the strongest risk factors for HAI acquired in ICU were: intubation (OR 2.76), urinary catheter (OR 2.12), no involvement of a family member in patient care (OR 1.94), and surgery after admission (OR 1.66). 726 bacterial isolates were cultured from 622/1012 HAIs, most frequently Acinetobacter baumannii (177/726 [24.4%]), Pseudomonas aeruginosa (100/726 [13.8%]), and Klebsiella pneumoniae (84/726 [11.6%]), with carbapenem resistance rates of 89.2%, 55.7%, and 14.9% respectively. Antimicrobials were prescribed for 84.8% (2787/ 3287) patients, with 73.7% of patients receiving two or more. The most common antimicrobial groups were third generation cephalosporins, fluoroquinolones, and carbapenems (20.1%, 19.4%, and 14.1% of total antimicrobials, respectively). Conclusion A high prevalence of HAIs was observed, mainly caused by Gram-negative bacteria with high carbapenem resistance rates. This in combination with a high rate of antimicrobial use illustrates the urgent need to improve rational antimicrobial use and infection control efforts.
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| 4. |
- Vu Nguyen Thanh,, et al.
(författare)
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Surveying of acid-tolerant thermophilic lignocellulolytic fungi in Vietnam reveals surprisingly high genetic diversity
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Thermophilic fungi can represent a rich source of industrially relevant enzymes. Here, 105 fungal strains capable of growing at 50 degrees C and pH 2.0 were isolated from compost and decaying plant matter. Maximum growth temperatures of the strains were in the range 50 degrees C to 60 degrees C. Sequencing of the internal transcribed spacer (ITS) regions indicated that 78 fungi belonged to 12 species of Ascomycota and 3 species of Zygomycota, while no fungus of Basidiomycota was detected. The remaining 27 strains could not be reliably assigned to any known species. Phylogenetically, they belonged to the genus Thielavia, but they represented 23 highly divergent genetic groups different from each other and from the closest known species by 12 to 152 nucleotides in the ITS region. Fungal secretomes of all 105 strains produced during growth on untreated rice straw were studied for lignocellulolytic activity at different pH and temperatures. The endoglucanase and xylanase activities differed substantially between the different species and strains, but in general, the enzymes produced by the novel Thielavia spp. strains exhibited both higher thermal stability and tolerance to acidic conditions. The study highlights the vast potential of an untapped diversity of thermophilic fungi in the tropics.
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| 5. |
- Eriksson, Leif, 1971-, et al.
(författare)
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Secular trend, seasonality and effects of a community-based intervention on neonatal mortality : follow-up of a cluster-randomised trial in Quang Ninh province, Vietnam
- 2018
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Ingår i: Journal of Epidemiology and Community Health. - : BMJ. - 0143-005X .- 1470-2738. ; 72:9, s. 776-782
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Tidskriftsartikel (refereegranskat)abstract
- Background: Little is know about whether the effects of community engagement interventions for child survival in low-income and middle-income settings are sustained. Seasonal variation and secular trend may blur the data. Neonatal mortality was reduced in a cluster-randomised trial in Vietnam where laywomen facilitated groups composed of local stakeholders employing a problem-solving approach for 3 years. In this analysis, we aim at disentangling the secular trend, the seasonal variation and the effect of the intervention on neonatal mortality during and after the trial.Methods: In Quang Ninh province, 44 communes were allocated to intervention and 46 to control. Births and neonatal deaths were assessed in a baseline survey in 2005, monitored during the trial in 2008–2011 and followed up by a survey in 2014. Time series analyses were performed on monthly neonatal mortality data.Results: There were 30 187 live births and 480 neonatal deaths. The intervention reduced the neonatal mortality from 19.1 to 11.6 per 1000 live births. The reduction was sustained 3 years after the trial. The control areas reached a similar level at the time of follow-up. Time series decomposition analysis revealed a downward trend in the intervention areas during the trial that was not found in the control areas. Neonatal mortality peaked in the hot and wet summers.Conclusions: A community engagement intervention resulted in a lower neonatal mortality rate that was sustained but not further reduced after the end of the trial. When decomposing time series of neonatal mortality, a clear downward trend was demonstrated in intervention but not in control areas.Trial registration number: ISRCTN44599712, Post-results.
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| 6. |
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| 7. |
- Hien Tran, Thi, et al.
(författare)
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Triolein from Coix lacryma-jobi induces cell cycle arrest through p53/p21 signaling pathway
- 2016
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Ingår i: Biomedical and Pharmacology Journal. - : Oriental Scientific Publishing Company. - 0974-6242. ; 9:2, s. 519-524
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Tidskriftsartikel (refereegranskat)abstract
- p53, a tumor suppressor protein, has important roles in DNA repair, cell cycle and apoptosis, is a one of the key events in cancer development. Coix lacryma-jobi seed has been used as a food and traditional medicine plant with anti-oxidant, anti-cancer and anti-diabetic effects. In currently research, we identified the most potent p53-increasing compound among 4 compounds (1-4) found in Coix lacryma-jobi and demonstrated its molecular mechanism in MCF-7 cells. Among the four isolated compounds (1-4), triolein most increased p53. Triolein treatment induced p53, p21, p27 and Bax in MCF-7 cells. Moreover, triolein caused S phase arrest through suppression of CDK1, phopho-Rb and E2F1 in dose-dependent manner. We also observed the decreasing of DNA synthesis by triolein. These data suggest that triolein may induced cell cycle restart involve DNA synthesis and apoptosis pathway in MCF-7 cells.
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| 8. |
- Neubeck, Anna, 1974-, et al.
(författare)
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Low-temperature dunite hydration : evaluating CH4 and H2 production from H2O and CO2
- 2016
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Ingår i: Geofluids. - : Wiley. - 1468-8115 .- 1468-8123. ; 16:3, s. 408-420
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Tidskriftsartikel (refereegranskat)abstract
- Abiotic methane (CH4) and hydrogen (H2) produced after hydration of mafic/ultramafic rocks represent energy sources for microbes that may thrive in the deep subsurface regions of Earth and possibly on other planets. While H2 is a direct product of serpentinization, CH4 can form via Fischer–Tropsch Type (FTT) reactions (carbon reduction) that, due to potential H2 migration, can be spatially and temporally detached from serpentinization. We tested an alternative process hypothesized by some scholars, in which CO2 can be reduced through dunite hydration without initially added H2, implying that CH4 can form in the same serpentinized fluid–rock system. The experiment used natural dunite sand (Forsterite 92), CO2 with δ13C ~ −25‰ (VPDB), and a 1 mm dissolved SiO2 solution mixed in 30 glass bottles (118 mL) stored for up to 8 months at low temperature (50°C) to simulate land-based serpentinization systems. In addition, 30 control bottles without olivine were used as blanks. Trivial amounts of CH4 (orders of 0.2–0.9 ppmv) were detected in both samples and blanks, likely representing analytical noise; essentially, no significant amount of CH4 formed under the experimental conditions used in this work. Low amounts of H2 (~2.55 ± 1.39 ppmv) were generated, with production yields that were one order of magnitude lower than in previously published experiments. Moderate concentrations of SiO2 appeared to hinder low-temperature H2 production. Our experiment confirms that the low-temperature reduction of CO2 into CH4 through direct olivine hydration, without initial H2, is sluggish and not straightforward, which is consistent with previous studies. The presence of substantial amounts of H2, as well as suitable metal catalysts, appears to be essential in the low-temperature production of abiotic CH4, as observed in published FTT experiments.
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