21 results on '"Nguyen, Hang T."'
Search Results
2. Nitrogen and phosphorus ecophysiology of coralline algae.
- Author
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Nguyen, Hang T. T., Pritchard, Daniel W., and Hepburn, Christopher D.
- Abstract
The characteristics of nutrient uptake in macroalgae are generally well known but surprisingly little is known about nutrient uptake in coralline algae despite their ecological importance and extensive depth distribution. This study provides the first information on nitrate, ammonium and phosphate storage and uptake by articulated and crustose coralline algae that are dominant features of temperate subtidal rocky reefs. A comparison was made between an articulated coralline alga, Arthrocardia sp. in the Corallinales and crustose coralline spp. within the Hapalidiales. Seawater nutrient concentration and nutrient storage by coralline algae were monitored between June 2016 and November 2017 in a kelp forest in southern New Zealand. Time-course nutrient depletion experiments were conducted to determine appropriate incubation times for multiple-flask experiments and evaluate maximal uptake of nitrate, ammonium, and phosphate over time in winter and summer. The uptake of ammonium exhibited a saturable kinetics with Vmax of Arthrocardia sp. (2.07 ± 0.32 μmol gDW−1 h−1) significantly higher than that of crustose coralline spp. (0.58 ± 0.17 μmol gDW−1 h−1). A linear relationship with concentration was observed in nitrate and phosphate uptake by both coralline algae. Ammonium was considered a preferred nitrogen source for these corallines compared with nitrate in both summer and winter. Morphological difference is suggested to be an important factor resulting in the difference in nitrogen and phosphorus uptake rates and kinetic parameters of these corallines. Further research is required to understand if these differences are general attributes of the functional ecology of crustose and articulated corallines. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
3. Formation of 2D silicon-carbide nanoribbons by cooling from the melt and out-of-plane displacements of atoms.
- Author
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Van Hoang, Vo, Le Nguyen, Tue Minh, and Nguyen, Hang T. T.
- Subjects
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THERMODYNAMICS , *NANORIBBONS , *ATOMS , *HONEYCOMB structures , *FIRST-order phase transitions - Abstract
Formation of two-dimensional (2D) crystalline silicon carbide (SiC) from the melt is studied using molecular dynamics (MD) simulations. Model containing 11040 atoms interacted via the Vashishta interaction potential is cooled from 4500 to 300 K to investigate the change in structure and thermodynamic properties. We find evidence that crystallization of 2D SiC from the melt undergoes over some stages as follows. At temperature high enough, liquid 2D SiC exhibits the chain-like structure and further cooling leads to the formation of 2D SiC liquid with the ring-like structure. After that massive occurrence/growth of solid-like atoms occurs in the system leading to the formation of 2D SiC with a honeycomb structure. Moreover, out-of-plane displacements of atoms in the SiC nanoribbons at the selected temperatures are found and discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. Prior hypoxia prevents downregulation of ACE-2 by hyperoxia in fetal human lung fibroblasts.
- Author
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Mohamed, Tarek L., Nguyen, Hang T., Abdul-Hafez, Amal, Dang, Vinh X., Dang, MyTrang T., Gewolb, Ira H., and Uhal, Bruce D.
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HYPEROXIA , *HYPOXEMIA , *RENIN-angiotensin system , *LUNG cancer treatment , *DOWNREGULATION , *ACE inhibitors , *DIAGNOSIS , *THERAPEUTICS - Abstract
Purpose/Aim of Study:The renin angiotensin system is involved in experimentally induced lung fibrosis. Angiotensin (ANG)-II is profibrotic. Angiotensin converting enzyme-2 (ACE-2) cleaves ANG-II and is thus protective. ACE-2 has recently been reported to be significantly decreased under hyperoxic conditions. Hyperoxia is linked to Bronchopulmonary Dysplasia and lung fibrosis. Fetal lung cells normally do not undergo fibrotic changes with physiologic hypoxemia. We hypothesized that hypoxia prior to hyperoxic exposure in fetal lung fibroblasts (IMR-90 cell line) might be protective by preventing ACE-2 downregulation.Materials and Methods:IMR-90 cells were exposed to hypoxia (1%O2/99%N2) followed by hyperoxia (95%O2/5%CO2) or normoxia (21%O2) in vitro. Cells and culture media were recovered separately for assays of ACE-2, TNF-α-converting enzyme (TACE), αSmooth muscle actin (αSMA)—myofibroblast marker-, N-cadherin, and β-catenin immunoreactive protein.Results:ACE-2 significantly increased when IMR-90 were hypoxic prior to hyperoxic exposure with no recovery. In contrast to hyperoxia alone, ACE-2 did not decrease when IMR-90 were hypoxic prior to hyperoxic exposure with recovery. TACE/ADAM17 protein and mRNA were significantly decreased under these conditions. αSMA N-cadherin, and β-catenin proteins were significantly decreased with or without normoxic recovery.Conclusions:Hypoxia prior to hyperoxic exposure of fetal lung fibroblasts prevented ACE-2 downregulation and decreased ADAM17/TACE protein and mRNA. αSMA, N-cadherin, and β-catenin were also significantly decreased under these conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
5. A fast random walk algorithm for computing diffusion-weighted NMR signals in multi-scale porous media: A feasibility study for a Menger sponge.
- Author
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Grebenkov, Denis S., Nguyen, Hang T., and Li, Jing-Rebecca
- Subjects
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DIFFUSION magnetic resonance imaging , *RANDOM walks , *NUCLEAR magnetic resonance spectroscopy , *POROUS materials , *FEASIBILITY studies , *MATHEMATICAL models - Abstract
Abstract: A fast random walk (FRW) algorithm is adapted to compute diffusion-weighted NMR signals in a Menger sponge which is formed by multiple channels of broadly distributed sizes and often considered as a model for soils and porous materials. The self-similar structure of a Menger sponge allows for rapid simulations that were not feasible by other numerical techniques. The role of multiple length scales on diffusion-weighted NMR signals is investigated. [Copyright &y& Elsevier]
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- 2013
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- View/download PDF
6. Variational inference for Student-t MLP models
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Nguyen, Hang T. and Nabney, Ian T.
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INFERENCE (Logic) , *PATTERN perception , *PATTERN recognition systems , *METHODOLOGY , *MATHEMATICAL models , *LINEAR statistical models , *ALGORITHMS , *FORECASTING - Abstract
Abstract: This paper presents a novel methodology to infer parameters of probabilistic models whose output noise is a Student-t distribution. The method is an extension of earlier work for models that are linear in parameters to non-linear multi-layer perceptrons (MLPs). We used an EM algorithm combined with variational approximation, an evidence procedure, and an optimisation algorithm. The technique was tested on two forecasting applications. The first one is a synthetic dataset and the second is gas forward contract prices data from the UK energy market. The results showed that forecasting accuracy is significantly improved by using Student-t noise models. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
7. Short-term electricity demand and gas price forecasts using wavelet transforms and adaptive models
- Author
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Nguyen, Hang T. and Nabney, Ian T.
- Subjects
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REGRESSION analysis , *AUTOCORRELATION (Statistics) , *RADIAL basis functions , *GARCH model , *PERCEPTRONS , *KALMAN filtering , *PREDICTION theory , *STOCHASTIC processes - Abstract
Abstract: This paper presents some forecasting techniques for energy demand and price prediction, one day ahead. These techniques combine wavelet transform (WT) with fixed and adaptive machine learning/time series models (multi-layer perceptron (MLP), radial basis functions, linear regression, or GARCH). To create an adaptive model, we use an extended Kalman filter or particle filter to update the parameters continuously on the test set. The adaptive GARCH model is a new contribution, broadening the applicability of GARCH methods. We empirically compared two approaches of combining the WT with prediction models: multicomponent forecasts and direct forecasts. These techniques are applied to large sets of real data (both stationary and non-stationary) from the UK energy markets, so as to provide comparative results that are statistically stronger than those previously reported. The results showed that the forecasting accuracy is significantly improved by using the WT and adaptive models. The best models on the electricity demand/gas price forecast are the adaptive MLP/GARCH with the multicomponent forecast; their NMSEs are 0.02314 and 0.15384 respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
8. Enhanced Photocatalytic Activity of Spherical Nd 3+ Substituted ZnFe 2 O 4 Nanoparticles.
- Author
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Nguyen, Loan T. T., Nguyen, Hang T. T., Le, Thieng H., Nguyen, Lan T. H., Nguyen, Hai Q., Pham, Thanh T. H., Bui, Nguyen D., Tran, Ngan T. K., Nguyen, Duyen Thi Cam, Lam, Tan Van, and Tran, Thuan Van
- Subjects
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PHOTOCATALYSTS , *OPTICAL rotation , *RHODAMINE B , *NANOPARTICLES , *ZINC ferrites , *PLATINUM nanoparticles - Abstract
In this study, nanocrystalline ZnNdxFe2−xO4 ferrites with x = 0.0, 0.01, 0.03 and 0.05 were fabricated and used as a catalyst for dye removal potential. The effect of Nd3+ ions substitution on the structural, optical and photo-Fenton activity of ZnNdxFe2−xO4 has been investigated. The addition of Nd3+ ions caused a decrease in the grain size of ferrites, the reduction of the optical bandgap energies and thus could be well exploited for the catalytic study. The photocatalytic activity of the ferrite samples was evaluated by the degradation of Rhodamine B (RhB) in the presence of H2O2 under visible light radiation. The results indicated that the ZnNdxFe2−xO4 samples exhibited higher removal efficiencies than the pure ZnFe2O4 ferrites. The highest degradation efficiency was 98.00%, attained after 210 min using the ZnNd0.03Fe1.97O4 sample. The enhanced photocatalytic activity of the ZnFe2O4 doped with Nd3+ is explained due to the efficient separation mechanism of photoinduced electron and holes. The effect of various factors (H2O2 oxidant concentration and catalyst loading) on the degradation of RhB dye was clarified. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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9. Evolution of the Graphene Layer in Hybrid Graphene/Silicon Carbide Heterostructures upon Heating.
- Author
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Nguyen, Hang T. T. and Tranh, Duong Thi Nhu
- Subjects
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SILICON carbide , *RADIAL distribution function , *MELTING points , *HETEROSTRUCTURES , *GRAPHENE , *ZONE melting - Abstract
The hybrid graphene/SiC model is studied via molecular dynamics simulation to observe the evolution of the graphene layer upon heating. A two-layer model containing 10,000 graphene atoms and 7000 SiC atoms is heated from 50 K to 6000 K via Tersoff and Lennard-Jones potentials. The melting point zone is defined as the temperature range from 4400 K to 4600 K, which is close to the melting zone of graphite in an experiment. The Lindemann criterion for the 2D case is calculated and used to observe the appearance of liquid-like atoms. The evolution upon heating is analyzed on the basis of the occurrence/growth of liquid-like atoms, the radial distribution functions, and the formation of clusters. The liquid-like atoms tend to form clusters, and the largest cluster increases in size slightly to form a single largest cluster of liquid-like atoms. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
10. Crohn's Disease-Associated Adherent-Invasive Escherichia coli Manipulate Host Autophagy by Impairing SUMOylation.
- Author
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Dalmasso, Guillaume, Nguyen, Hang T. T., Faïs, Tiphanie, Massier, Sébastien, Barnich, Nicolas, Delmas, Julien, and Bonnet, Richard
- Subjects
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CROHN'S disease diagnosis , *MICRORNA , *SMALL ubiquitin-related modifier proteins , *GENE expression , *CANCER cells , *APOPTOSIS - Abstract
The intestinal mucosa of Crohn's disease (CD) patients is abnormally colonized with adherent-invasive Escherichia coli (AIEC) that are able to adhere to and to invade intestinal epithelial cells (IECs), to survive in macrophages, and to induce a pro-inflammatory response. AIEC persist in the intestine, and induce inflammation in CEABAC10 transgenic mice expressing human CAECAM6, the receptor for AIEC. SUMOylation is a eukaryotic-reversible post-translational modification, in which SUMO, an ubiquitin-like polypeptide, is covalently linked to target proteins. Here, we investigated the role of SUMOylation in host responses to AIEC infection. We found that infection with the AIEC LF82 reference strain markedly decreased the levels of SUMO-conjugated proteins in human intestinal epithelial T84 cells. This was also observed in IECs from LF82-infected CEABAC10 transgenic mice. LF82-induced deSUMOylation in IECs was due in part to increased level of microRNA (miR)-18, which targets PIAS3 mRNA encoding a protein involved in SUMOylation. Over-expression of SUMOs in T84 cells induced autophagy, leading to a significant decrease in the number of intracellular LF82. Consistently, a decreased expression of UBC9, a protein necessary for SUMOylation, was accompanied with a decrease of LF82-induced autophagy, increasing bacterial intracellular proliferation and inflammation. Finally, the inhibition of miR-18 significantly decreased the number of intracellular LF82. In conclusion, our results suggest that AIEC inhibits the autophagy response to replicate intracellularly by manipulating host SUMOylation. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
11. Structural evolution of free-standing 2D silicon carbide upon heating.
- Author
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Le Nguyen, Tue Minh, Van Hoang, Vo, and Nguyen, Hang T. T.
- Subjects
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ANGULAR distribution (Nuclear physics) , *MELTING points , *HEAT capacity , *SILICON carbide , *MOLECULAR dynamics - Abstract
Two-dimensional Silicon Carbide (2D SiC) model is studied via molecular dynamics simulation to observe the structural evolution upon heating. A model contains 11040 atoms interacting via Vashishta potentials. The model is heated up from 50 K to 4500 K in order to observe the changes in structures during heating process. The melting point of free-standing 2D SiC is defined to be around 4050 K by temperature dependence of the heat capacity. The Lindemann criterion for 2D case is calculated and used to classify the behaviors of the liquid like and solid like atoms. The atomic mechanism of structural evolution upon heating is analyzed based on the occurrence/growth of liquid like atoms the average coordination number the ring statistics as well as the angular distributions. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
12. Closing the gap for cervical cancer research in Vietnam: current perspectives and future opportunities: a report from the 5th Gynecologic Cancer InterGroup (GCIG) Cervical Cancer Research Network (CCRN) Education Symposium.
- Author
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Phan, Ngoc T. H., Tran, Quy T., Nguyen, Nhan P. T., Nguyen, Hang T., Tran, Linh D. N., Pham, Viet C., Bennett, Katherine, Chávez-Blanco, Adriana, Plante, Marie, Dong Hoon Suh, Nout, Remi, and Tan, David S. P.
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CERVICAL cancer , *GYNECOLOGIC cancer , *CANCER research , *CANCER hospitals - Published
- 2023
- Full Text
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13. The future of molecular ecology in Aotearoa New Zealand: an early career perspective.
- Author
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Liggins, Libby, Arranz, Vanessa, Braid, Heather E., Carmelet-Rescan, David, Elleouet, Joane, Egorova, Ekaterina, Gemmell, Michael R., Hills, Simon F. K., Holland, Lyndsey P., Koot, Emily M., Lischka, Alexandra, Maxwell, Kimberley H., McCartney, Laura J., Nguyen, Hang T. T., Noble, Cory, Rojas, Pamela Olmedo, Parvizi, Elahe, Pearman, William S., Sweatman, Jenny Ann N., and Kaihoro, Te Rangitākuku
- Subjects
- *
BIOTIC communities , *PHILOSOPHY of science , *SCIENTIFIC community , *ECOLOGISTS , *GOVERNMENT agencies - Abstract
The skills, insights, and genetic data gathered by molecular ecologists are pivotal to addressing many contemporary biodiversity, environmental, cultural, and societal challenges. Concurrently, the field of molecular ecology is being revolutionised by rapid technological development and diversification in the scope of its applications. Hence, it is timely to review the future opportunities of molecular ecological research in Aotearoa New Zealand, and to reconcile them with philosophies of open science and the implications for Indigenous data sovereignty and benefit sharing. Future molecular ecologists need to be interdisciplinary, equipped to embrace innovation, and informed about the broader societal relevance of their research, as well as advocates of best practice. Here, we present an ideal future for molecular ecology in Aotearoa, based on the perspectives of 23 early career researchers from tertiary institutions, Crown Research Institutes, research consultancies, and government agencies. Our article provides: a guide for molecular ecologists embarking on genetic research in Aotearoa, and a primer for individuals in a position to support early career molecular ecologists in Aotearoa. We outline our goals and highlight specific considerations – for molecular ecology and the scientific community in Aotearoa – based on our own experience and aspirations, and invite other researchers to join this dialogue. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
14. Small-scale microcosms to detect chemical induced changes in soil nematode communities — Effects of crystal proteins and Bt-maize plant material.
- Author
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Höss, Sebastian, Reiff, Nicola, Nguyen, Hang T., Jehle, Johannes A., Hermes, Hanna, and Traunspurger, Walter
- Subjects
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SOIL nematodes , *BIOTIC communities , *CORN proteins , *COMPOSITION of corn , *LABORATORIES , *COMPARATIVE studies - Abstract
Abstract: Small-scale laboratory microcosms (30g soil in 50ml tubes) were evaluated for their suitability to assess the impact of chemicals on in situ soil nematode communities. For this purpose, appropriate conditions in the microcosms were explored to ensure stable conditions and a homogenous distribution of the nematodes. Then, the microcosms were used to assess the toxicity of insecticidal crystal proteins (Cry1A.105, Cry2Ab2, Cry3Bb1) present in genetically modified maize (MON89034×MON88017) on in situ nematode communities. Highly abundant and genus rich nematode communities could be maintained over a period of 12weeks. Due to a low variance between the replicates of the treatments, low detection limits could be achieved. Using meaningful stress indices, such as the maturity indices, the microcosm study revealed dose-dependent effects of the insecticidal Cry proteins that could be verified as toxic effects by comparing with effects of two positive controls (Cu, nematicidal Cry5B). Moreover, toxic effects could be differentiated from organic enrichment effects that were induced by the addition of plant material. With a NOECCommunity of 0.1mgkg−1 dry wt, the nematode communities reacted considerably more sensitive to the Cry proteins than a single-species nematode toxicity test (NOEC: 29mgl−1). The small-scale microcosm set-up turned out to be a suitable, low-budget tool for assessing the toxicity of chemicals on soil nematodes on community level, representing a link between single-species toxicity tests and large scale outdoor mesocosms. [Copyright &y& Elsevier]
- Published
- 2014
- Full Text
- View/download PDF
15. The future of molecular ecology in Aotearoa New Zealand: an early career perspective.
- Author
-
Liggins, Libby, Arranz, Vanessa, Braid, Heather E., Carmelet-Rescan, David, Elleouet, Joane, Egorova, Ekaterina, Gemmell, Michael R., Hills, Simon F. K., Holland, Lyndsey P., Koot, Emily M., Lischka, Alexandra, Maxwell, Kimberley H., McCartney, Laura J., Nguyen, Hang T. T., Noble, Cory, Olmedo Rojas, Pamela, Parvizi, Elahe, Pearman, William S., Sweatman, Jenny Ann N., and Kaihoro, Te Rangitākuku
- Subjects
- *
BIOTIC communities , *PHILOSOPHY of science , *SCIENTIFIC community , *ECOLOGISTS , *GOVERNMENT agencies - Abstract
The skills, insights, and genetic data gathered by molecular ecologists are pivotal to addressing many contemporary biodiversity, environmental, cultural, and societal challenges. Concurrently, the field of molecular ecology is being revolutionised by rapid technological development and diversification in the scope of its applications. Hence, it is timely to review the future opportunities of molecular ecological research in Aotearoa New Zealand, and to reconcile them with philosophies of open science and the implications for Indigenous data sovereignty and benefit sharing. Future molecular ecologists need to be interdisciplinary, equipped to embrace innovation, and informed about the broader societal relevance of their research, as well as advocates of best practice. Here, we present an ideal future for molecular ecology in Aotearoa, based on the perspectives of 23 early career researchers from tertiary institutions, Crown Research Institutes, research consultancies, and government agencies. Our article provides: a guide for molecular ecologists embarking on genetic research in Aotearoa, and a primer for individuals in a position to support early career molecular ecologists in Aotearoa. We outline our goals and highlight specific considerations – for molecular ecology and the scientific community in Aotearoa – based on our own experience and aspirations, and invite other researchers to join this dialogue. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
16. Provider Perspectives on Integration of Substance Use Disorder and HIV Care in Vietnam: A Qualitative Study.
- Author
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Edsall, Andrew, Dinh, Thanh Thuy Thi, Mai, Pham Phuong, Hoffman, Kim, Nguyen, Hang T., Khuyen, Tong Thi, Trang, Nguyen Thu, Bart, Gavin, Giang, Le Minh, and Korthuis, P. Todd
- Subjects
- *
SUBSTANCE abuse , *ALCOHOLISM , *HIV , *QUALITATIVE research , *OPIOID abuse - Abstract
UNAIDS recommends integration of medications for substance use disorders (SUD) with HIV care to improve HIV outcomes. Yet, integration of HIV and SUD services remains limited in many countries. The objective of this study was to assess provider perceptions of care integration in Vietnam. Qualitative interviews were conducted with 43 providers (nurses, physicians, counselors, pharmacists, and clinic managers) in 8 HIV clinics in northern Vietnam, 2013–2015. Providers identified five themes informing HIV and SUD treatment integration: (1) treatment for alcohol use disorder is often neglected compared to other SUD treatment; (2) structural challenges must be addressed to increase integration feasibility; (3) workforce limitations; (4) societal and healthcare stigmatization of SUD; and (5) providers' conflicting views regarding integration challenges. The experience of providers in Vietnam may be useful to other countries attempting to integrate HIV and SUD services. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
17. Autophagy: A Novel Mechanism Involved in the Anti-Inflammatory Abilities of Probiotics.
- Author
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Zaylaa, Mazen, Alard, Jeanne, Kassaa, Imad Al, Peucelle, Veronique, Boutillier, Denise, Desramaut, Jérémy, Rosenstiel, Philip, Nguyen, Hang T. T., Dabboussi, Fouad, Pot, Bruno, and Grangette, Corinne
- Subjects
- *
AUTOPHAGY , *ANTI-inflammatory agents , *PROBIOTICS , *IMMUNE response , *CROHN'S disease - Abstract
Background/Aims: Deregulation of the complex interaction among host genetics, gut microbiota and environmental factors on one hand and aberrant immune responses on the other hand, are known to be associated with the development of inflammatory bowel disease. Recent studies provided strong evidence that autophagy plays a key role in the etiology of Crohn’s disease (CD). Probiotics may exhibit many therapeutic properties, including anti-inflammatory abilities. While successful results have been obtained in ulcerative colitis patients, probiotics remain inefficient in CD for unknown reason. It remains therefore important to better understand their molecular mechanisms of action. Methods: The activation of autophagy was examined by stimulating bone marrow-derived dendritic cells by the bacteria, followed by confocal microscopy and western blot analysis. The impact of blocking in vitro autophagy was performed in peripheral blood mononuclear cells using 3-methyl adenine or bafilomycin followed by cytokine secretion measurement by ELISA. The role of autophagy in the anti-inflammatory capacities of the bacterial strains was evaluated in vivo using an acute trinitrobenzene sulfonic acid-induced murine model of colitis. The impact of BMDC was evaluated by adoptive transfer, notably using bone marrow cells derived from autophagy-related 16-like 1-deficient mice. Results: We showed that selected lactobacilli and bifidobacteria are able to induce autophagy activation in BMDCs. Blocking in vitro autophagy abolished the capacity of the strains to induce the release of the anti-inflammatory cytokine interleukin-10, while it exacerbated the secretion of the pro-inflammatory cytokine interleukin- 1β. We confirmed in the TNBS-induced mouse model of colitis that autophagy is involved in the protective capacity of these selected strains, and showed that dendritic cells are involved in this process. Conclusion: We propose autophagy as a novel mechanism involved in the regulatory capacities of probiotics. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
18. A Facile Synthesis, Characterization, and Photocatalytic Activity of Magnesium Ferrite Nanoparticles via the Solution Combustion Method.
- Author
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Nguyen, Loan T. T., Nguyen, Lan T. H., Manh, Nhuong Chu, Quoc, Dung Nguyen, Quang, Hai Nguyen, Nguyen, Hang T. T., Nguyen, Duy Chinh, and Bach, Long Giang
- Subjects
- *
CALCINATION (Heat treatment) , *FERRITES , *MAGNESIUM , *COMBUSTION , *NANOPARTICLES , *METHYLENE blue - Abstract
In this study, we adopted the solution combustion method to synthesize magnesium ferrite (MgFe2O4) using urea as the fuel. Various techniques including TGA, XRD, SEM, TEM, FTIR, UV-Vis DRS, and EDS were employed to characterize the synthesized MgFe2O4 nanoparticles. The XRD analysis revealed that single-phase MgFe2O4 was formed at a calcination temperature of at 500–600°C for 3 hours in the absence of an intermediate phase. TEM analysis also revealed the formation of monodisperse magnesium ferrite nanoparticles, averaged at 30 nm in size. The photocatalytic activity of the synthesized MgFe2O4 nanoparticles against methylene blue dye under visible light was investigated, showing the efficiency of 89.73% after 240 minutes of light irradiation with the presence of H2O2. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
19. The loss patterns of reduced sulfur compounds in contact with different tubing materials
- Author
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Kim, Ki-Hyun, Ahn, Ji-Won, Choi, Ye-Jin, and Nguyen, Hang T.
- Subjects
- *
PHYSICAL measurements , *WASTE products , *MOLECULAR weights , *SULFUR compounds - Abstract
Abstract: To collect or transfer samples of airborne pollutants, tubings made of various materials are used. To analyze the reactive loss patterns of reduced sulfur compounds (RSC) in the use of tubing fittings, a series of laboratory experiments were conducted so that the concentration changes were induced by the physical contact between gas samples and tubing walls. For the purpose of this study, a total of five tubing materials were investigated in reference to silcosteel (S1) tubing: stainless steel (S2), silicone (S3), PTFE Teflon (T1), tygon (T2), and copper (C). This comparative experiment was made using gaseous standards containing equimolar concentrations of four RSCs (H2S, CH3SH, DMS, and DMDS). The loss patterns of RSC were then evaluated and compared in terms of their calibration slope values across different tubing materials. The results of this comparative analysis indicated that except for a few cases, a fairly good compatibility was seen consistently among different tubing types and different RSCs. The results generally showed that the magnitude of calibration slope values obtained from different tubing materials tend to increase with an increase in RSC molecular weights. If the results are compared between different tubing materials, a highly contrasting pattern was evident. For instance, C tubing shows significant losses of light RSCs (H2S and CH3SH), while S3 tubing experiences the large losses of DMS and DMDS. A line of evidence found in this study thus suggests that most tubing types have their unique loss mechanism for RSCs, when they contact RSCs in sample gas stream passing through the tubing walls. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
20. Accelerated Synthesis of Graphene Oxide from Graphene.
- Author
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Costa, Mariana C. F., Marangoni, Valeria S., Ng, Pei Rou, Nguyen, Hang T. L., Carvalho, Alexandra, Castro Neto, A. H., and Giancane, Gabriele
- Subjects
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GRAPHENE oxide , *CHEMICAL properties , *GRAPHENE , *ENERGY storage , *MAGNITUDE (Mathematics) , *GRAPHENE synthesis , *GRAPHITE , *GRAPHITE oxide - Abstract
Graphene oxide (GO) is an oxygenated functionalized form of graphene that has received considerable attention because of its unique physical and chemical properties that are suitable for a large number of industrial applications. Herein, GO is rapidly obtained directly from the oxidation of graphene using an environmentally friendly modified Hummers method. As the starting material consists of graphene flakes, intercalant agents are not needed and the oxidation reaction is enhanced, leading to orders of magnitude reduction in the reaction time compared to the conventional methods of graphite oxidation. With a superior surface area, the graphene flakes are quickly and more homogeneously oxidized since the flakes are exposed at the same extension to the chemical agents, excluding the necessity of sonication to separate the stacked layers of graphite. This strategy shows an alternative approach to quickly producing GO with different degrees of oxidation that can be potentially used in distinct areas ranging from biomedical to energy storage applications. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
21. Pilot-Scale Removal of Arsenic and Heavy Metals from Mining Wastewater Using Adsorption Combined with Constructed Wetland.
- Author
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Nguyen, Ha T. H., Nguyen, Bien Q., Duong, Thuy T., Bui, Anh T. K., Nguyen, Hang T. A., Cao, Ha T., Mai, Nhuan T., Nguyen, Khai M., Pham, Thuy T., and Kim, Kyoung-Woong
- Subjects
- *
WETLANDS , *CONSTRUCTED wetlands , *ARSENIC removal (Water purification) , *HEAVY metals , *SEWAGE , *ATOMIC absorption spectroscopy - Abstract
This study was conducted to assess the removal of arsenic (As) and heavy metals from mining wastewater by the combination of adsorption, using modified iron-ore drainage sludge, and horizontal-subsurface-flow constructed wetland with common reed (Phragmites australis). The pilot-scale experiment with a constant flow rate of 5 m3/day was operated for four months using real wastewater from a Pb–Zn mine in northern Vietnam. Atomic absorption spectroscopy was used for elemental analysis in wastewater and plant. X-ray diffraction (XRD), surface charge measurements (by a particle charge detector (PCD)), Fourier-transform infrared (FTIR), and surface area Brunauer–Emmet–Teller (BET) measurements were performed to determine the characteristics of the adsorbent. The results showed that the average removals of As, Mn, Cd, Zn, and Pb by the combined system with limestone substrate during four months were 80.3%, 96.9%, 79.6%, 52.9%, and 38.7%, respectively. The use of another constructed wetland substrate, laterite, demonstrated better removal efficiency of As than limestone. The concentrations of As and heavy metals in the effluent were lower than the limits established by the QCVN 40:2011/BTNMT for industrial wastewater, which indicated the feasibility of combining adsorption and constructed wetland for the treatment of mining wastewater. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
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