173 results on '"Hung, D."'
Search Results
2. Encapsulation of anti-bacterial Piper betle leaf extract in thermo-sensitive and biodegradable chitosan hydrogels: synthesis, characterization and release kinetics.
- Author
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Do, Nga H. N., Huynh, Duyen My Thi, Le, Trieu T. H., Le, Thanh V. N., Vuong, Hung D., Nguyen, Trang P. T., Quach, Thao H. N., Le, Phung K., and Ha, Anh C.
- Abstract
Betel leaf extract (BLE) is well-known for its anti-bacterial, anti-inflammatory, and anti-oxidant activities as well as wound healing effects. For the first time, the ethanolic BLE has been successfully encapsulated into thermo-sensitive chitosan hydrogels to deliver the extract to infected wounds while preserving its biological activities. Morphologies, sol–gel transition, chemical structure, and pH of the hydrogels are comprehensively studied under the variation in the initial loading BLE concentration. Release kinetics of the hydrogels are evaluated in different environmental conditions to determine the BLE release behavior and the suitable mathematical model. The hydrogels exhibit sol–gel transition at 37.0–40.0 °C, a gelation time of 9.5–13.0 min at 37 °C, a neutral pH, and a hollow structure self-crosslinked by chitosan with both surface and internal adhesion of BLE. The BLE release from the hydrogels is affected by pH, temperature, and the BLE loading concentration and is governed by a controlled diffusion following the Korsmeyer-Peppas model. The hydrogels release 50.91–60.29% of their initial loading content and the release solutions demonstrate potent antibacterial activity against E. coli and S. aureus evidenced by the inhibition rate of 70.67–99.94%. Moreover, the chitosan hydrogels encapsulating BLE are biodegradable with a remarkably high degradability of 76.92–79.74% after 14 days of exposure to lysozyme under simulated physiological conditions. Based on the findings, the developed hydrogels are considered a potential delivery system to handle open skin wounds via local subcutaneous injection. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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3. ASSESSING DAILY MAXIMUM HEAT INDEX IN THE CONTEXT OF CLIMATE CHANGE FOR HANOI (VIETNAM).
- Author
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HUNG, D. N., PHUONG, C. T., THANG, N. N., CHIEN, N. Q., DUNG, B. T. T., and HANG, V. T.
- Subjects
HEAT index ,STOCK index futures ,HEAT stroke ,CLIMATE change ,HUMIDITY - Abstract
Hanoi is the second largest city in Vietnam. The effects of climate change, coupled with rapid, unchecked urbanization and population increase are resulting in a severe rise in incidents of heat stress, which has serious ramifications for community health. In this study, a multivariable linear regression, heat index (HI) methods, and climate change scenarios for Vietnam in 2020 are used as input data to calculate the daily maximum heat index (HImax) for Hanoi during 2024-2028. Findings indicate that HImax at danger level has already occurred and will happen again in the future, with seasonal characteristics mainly distributed in June, July, August. For the years 2024-2028, HImax at the danger level increases in two scenarios compared to 2017-2021. Notably, the number of days with HImax at the extreme danger level, which may be the main cause of heat stroke, has 0.4 days/year occurring during 2017-2021. However, it will also appear in the years 2024-2028 in both RCP 4.5 and RCP 8.5 scenarios from June to August, at 0.6 days/year and 2.6 days/year, respectively. Knowing the daily maximum heat index for the future at specific times is crucial information for acting on the risk of heat stress in Hanoi given the current danger posed by climate change. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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4. SOIL ORGANIC CARBON STOCKS IN NATURAL FORESTS OF DONGNAI CULTURE AND NATURE RESERVE, SOUTHEASTERN VIETNAM.
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CHAU, M. H., QUY, N. V., CUONG, L. V., HIEU, N. T., NGOAN, T. T., HUNG, D. V., HUNG, B. M., and PHU, N. V.
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SOIL moisture ,CARBON sequestration in forests ,CARBON in soils ,FOREST soils ,PEARSON correlation (Statistics) - Abstract
Even minor fluctuations in the carbon content in forest soil can significantly impact atmospheric carbon concentrations and future global climate patterns. Therefore, investigating the variation characteristics of soil organic carbon (SOC) in tropical forests is essential for comprehending the carbon sequestration potential of forest soil. This study delves into SOC dynamics within the natural forest types of Dongnai Culture and Nature Reserve in southeastern Vietnam. Nine 1000 m² plots were sampled across rich, medium, and poor forests. Soil samples were collected from depths ranging from 0 to 60 cm. The findings revealed increased SOC content from poor to rich forests, with a decrease in depth. The total carbon (C) stocks ranged from 92.20 Mg C ha
-1 in poor forests to 124.30 Mg C ha-1 in rich forests within the top 60 cm. Over 81% of soil C was concentrated in the upper 40 cm. Factors such as soil water content and slope gradient emerged as crucial determinants affecting SOC distribution. These results underscore the potential of forest management practices to augment SOC levels, thereby offering valuable insights for estimating carbon stocks in the forest ecosystems of southeastern Vietnam. [ABSTRACT FROM AUTHOR]- Published
- 2024
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5. ASSESSMENT OF CHANGE ON THE DAILY MAXIMUM HEAT INDEX FOR THAI BINH CITY (VIETNAM).
- Author
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CHIEN, N. Q., HUNG, D. N., PHUONG, C. T., HIEN, N. T. T., CHI, L. H., HIEN, V. T., and HUE, D. T.
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HEAT stroke ,HEAT waves (Meteorology) ,HUMAN physiology ,GREENHOUSE gases ,CLIMATE change - Abstract
Meteorological factors, especially temperature and humidity, have a great impact on human physiology. In the context of climate change, the impact of temperature on people's health in Thai Binh city (Vietnam) is becoming more and more serious. Based on meteorological data for the period of 1991-2021 and Vietnam climate change scenario data, the daily maximum heat index (HI
max ) scenario for the period of 2024-2054 is calculated by the method of correlation evaluation and regression equations. The results show that in the future the trend of HImax is 0.0875°C per year under the RCP 4.5 scenario (Medium Low Greenhouse Gases Concentration Scenario) and 0.0919°C per year under the RCP 8.5 scenario (High Greenhouse Gases Concentration Scenarios). The number of weeks per 5 years having daily HImax at danger level (HIwave ) tends to increase 6.14 times for scenario RCP 4.5; 7.0 times for scenario RCP 8.5. Especially, the number of days at risk of heat stroke in the past 31-year period is 5 days, then in the future 31-year period there are 77 days with scenario RCP 4.5 and 116 days with scenario RCP 8.5 and this phenomenon mainly concentrated in the months of June, July, August. [ABSTRACT FROM AUTHOR]- Published
- 2024
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6. Stability and Invariant Measure Asymptotics in a Model for Heavy Particles in Rough Turbulent Flows.
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Herzog, David P. and Nguyen, Hung D.
- Abstract
We study a system of Skorokhod stochastic differential equations modeling the pairwise dispersion (in spatial dimension d = 2 ) of inertial particles transported by a rough turbulent flow with Hölder exponent h ∈ (0 , 1) . Under the assumption that h > 0 is sufficiently small, we use Lyapunov methods and control theory to show that the Markovian system is nonexplosive and has a unique, exponentially attractive invariant probability measure. Furthermore, our Lyapunov construction is radially sharp and gives partial confirmation on a predicted asymptotic behavior with respect to the Hölder exponent h of the invariant probability measure. A physical interpretation of the asymptotics is that intermittent clustering is weakened when the carrier flow is sufficiently rough. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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7. Polynomial Mixing of a Stochastic Wave Equation with Dissipative Damping.
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Nguyen, Hung D.
- Abstract
We study the long time statistics of a class of semi-linear wave equations modeling the motions of a particle suspended in continuous media while being subjected to random perturbations via an additive Gaussian noise. By comparison with the nonlinear reaction settings, of which the solutions are known to possess geometric ergodicity, we find that, under the impact of nonlinear dissipative damping, the mixing rate is at least polynomial of any order. This relies on a combination of Lyapunov conditions, the contracting property of the Markov transition semigroup as well as the notion of d-small sets. [ABSTRACT FROM AUTHOR]
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- 2024
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8. Interface passivation using choline acetate for efficient and stable planar perovskite solar cells.
- Author
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Thambidurai, M., Dewi, Herlina Arianita, Wang Xizu, Mathews, Nripan, Cuong Dang, and Hung D. Nguyen
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- 2023
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9. Exploration of Bifunctionality in Mn, Co Codoped CuO Nanoflakes for Overall Water Splitting.
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Rani, B. Jansi, Mohana, P., Swathi, S., Yuvakkumar, R., Ravi, G., Thambidurai, M., Nguyen, Hung D., and Velauthapillai, Dhayalan
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COPPER oxide ,HYDROGEN evolution reactions ,OXYGEN evolution reactions ,LAMINATED metals ,CHARGE transfer ,CHEMICAL kinetics - Abstract
Herein, bimetal (Mn, Co) codoping on a CuO host is aimed at enhancing oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activity. Codoping of Mn and Co on CuO to enhance bifunctional action in electrochemical water splitting has not yet been investigated to the best of our knowledge. Literatures are focused on unary Mn-doped CuO or Co-doped CuO nanostructures. Mn, Co codoped CuO through an easy chemical coprecipitation method has been successfully attempted and is more beneficial which is the novelty of the present work. Defect-enriched ample active sites (Mn
2+ /Mn3+ and Co2+ /Co3+ ) along with Cu2+ in the host CuO achieved high current density (100 mA/cm2 ) in OER and HER with low overpotential such as 468 mV and 271 mV, respectively. Faster charge transfer and diffusion ability was stimulated by the bimetal codoping CuO. Reasonable Tafel plot values (OER: 199 mV/dec, and HER: 21 mV/dec) with improved water-splitting reaction kinetics were achieved for the Mn, Co codoped CuO nanoflakes. The double-layer capacitance ( C dl ) value of 27.5 mF/cm2 for Mn, Co codoped CuO nanoflakes was achieved. Similarly, the increasing order of an electrochemically active surface area (EASA) was exhibited by the consequent addition of bimetal doping on CuO, denoted as Mn , Co / CuO > Co / CuO > Mn / CuO > CuO. The evidence shows that the codoping strategy could facilitate rapid reaction kinetics to develop overall water splitting. The charge transfer resistances ( R ct ) of 3.6 Ω and 1.2 Ω for the Mn, Co codoped CuO nanostructure corresponding to the OER and HER, respectively, were reported. The long-term stability over 16 h with negligible loss was reported for both the OER and the HER performance. Thus, this work contributes to better insight and analysis of the successful codoping of bimetal elements in earth-abundant electrocatalysts to enhance and make practical the electrocatalytic water-splitting activity. [ABSTRACT FROM AUTHOR]- Published
- 2023
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10. Distributed Energy Resource Exploitation through Co-Optimization of Power System and Data Centers with Uncertainties during Demand Response.
- Author
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Weng, Yu, Liu, Yang, Lim, Rachel Li Ting, and Nguyen, Hung D.
- Abstract
This paper presents a robust bi-level co-optimization model that promotes the active participation of Internet Data Centers (IDCs) in demand response (DR) programs, thereby enhancing the flexibility of power systems. Our approach involves leveraging virtual power lines to migrate workloads among IDCs, optimizing resource allocations, and benefiting both domains. The model incorporates a Gaussian Process Regression (GPR)-constructed DR price–amount curve, which largely contributes to the simplification of the optimization problem with high accuracy and computational efficiency. It also respects the information barriers between the two domains of power systems and IDCs, and thus safeguards the privacy and flexibility of IDCs. The uncertainty in IDC operations is considered by incorporating the variance in GPR into the demand response curve. By integrating IDCs as DR resources, the framework of this research enhances the flexibility of power systems and the efficiency of cross-domain co-optimization. The model and algorithm are validated using modified IEEE test systems. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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11. Sr doped TiO2 photocatalyst for the removal of Janus Green B dye under visible light.
- Author
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Keerthana, SP., Yuvakkumar, R., Ravi, G., Thambidurai, M., Nguyen, Hung D., and Velauthapillai, Dhayalan
- Published
- 2023
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12. Ternary Copper Iron Sulfide Microflowers Anchored on Reduced Graphene Oxide for Water Splitting.
- Author
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Swathi, Srinivasan, Yuvakkumar, Rathinam, Ravi, Ganesan, Thambidurai, Mariyappan, Nguyen, Hung D., and Velauthapillai, Dhayalan
- Abstract
Transition metal sulfides are widely employed as bifunctional electrocatalysts owing to their unique structural features, well-off active sites, and modifiable electronic and mechanical properties. Herein, we have synthesized highly efficient ternary copper iron sulfide (CuFeS
2 )/reduced graphene oxide (rGO) composites via a hydrothermal approach for an overall water splitting process. The tetragonal structure of CuFeS2 microflowers anchored on rGO sheets is identified by using X-ray analysis and compared with standard Joint Committee on Powder Diffraction Standards (JCPDS) #35-752. In Raman spectra, the existence of two bands D (defects) and G (graphitic) confirms the presence of the rGO composite with CuFeS2, and the ratio of D and G band (ID /IG ) is observed to be 1.18. The morphological analysis using scanning electron microscopy and transmission electron microscopy substantiates the formation of microflowers with rGO sheets. The elemental composition of CuFeS2 /rGO was analyzed by energy-dispersive X-ray analysis, which demonstrated a weight percentage of various compositions of Cu (18.07%), Fe (11.32%), S (13.88%), and C (56.74%). Moreover, the CuFeS2 /rGO composites exhibited a high surface area, pore volume, and diameter of 50.352 m2 /g, 0.162 cc/g, and 2.471 nm, respectively. The fabricated electrodes were examined by using electrochemical characterization. The obtained results clearly showed low overpotential and low Tafel slope values in both the oxygen evolution reaction (OER) (176 mV and 216 mV/dec) and hydrogen evolution reaction (HER) (153 mV and 150 mV/dec) processes. In addition, the fabricated composite exhibited low 1.59 V cell voltages for an overall water splitting process with more excellent stability, and it showed a faradaic efficiency of 97.8% for H2 and 95.5% for O2 . Therefore, the composite of rGO in ternary metal sulfide plays a predominant role in improving the electrocatalytic activity of the material, and the CuFeS2 /rGO composite emerges as a promising electrode for the water splitting process. [ABSTRACT FROM AUTHOR]- Published
- 2023
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13. Polyisoprenylated benzophenones and xanthones from the pericarp of Garcinia planchonii Pierre.
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Trinh, Duong H., Huynh, Oanh N., Nguyen, Trung Q., Nguyen, Hieu T., Nguyen, Thao-Ly T., Pham, Hung D., Nguyen, Lien-Hoa D., and Tran, Phuong T.
- Subjects
BENZOPHENONES ,GARCINIA ,PERICARP ,ETHYL acetate ,PREGNANE ,CANCER cells ,ALPHA-glucosidases - Abstract
Two new polyisoprenylated benzophenones, planchoniones A (1) and B (2), together with two known benzophenones (3, 4) and six known xanthones (5-10), were isolated from an ethyl acetate extract of the pericarp of Garcinia planchonii Pierre. Their structures were established using spectroscopic methods, mainly 1D and 2D NMR. The four benzophenones were evaluated for their cytotoxicity against MCF-7 human breast cancer cells, and showed almost no activity. Meanwhile, compounds 5-10 were investigated for their inhibitory effects towards α-glucosidase, and γ-mangostin (5) exhibited the most remarkable effect with IC
50 value of 15.3 ± 0.9 µM (compared with acarbose, IC50 = 224.9 ± 3.6 µM). [ABSTRACT FROM AUTHOR]- Published
- 2023
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14. A static and dynamic copula-based ARIMA-fGARCH approach to determinants of carbon dioxide emissions in Argentina.
- Author
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Ly, Sel, Sarwat, Salman, Wong, Wing-Keung, Ramzan, Muhammad, and Nguyen, Hung D.
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CARBON emissions ,ENVIRONMENTAL quality ,ECONOMIC globalization ,ENERGY consumption ,ENVIRONMENTAL degradation - Abstract
This paper attempts to model both static and dynamic dependence structures and measure impacts of energy consumptions (both renewable (EC) and non-renewable (REN) energies), economic globalization (GLO), and economic growth (GDP) on carbon dioxide (CO
2 ) emissions in Argentina over the period 1970–2020. For analyses purpose, the current research deploys the novel static and dynamic copula-based ARIMA-fGARCH with different submodels. The static bivariate copula results show that the growth rates of the pairs EC-CO2 and GDP-CO2 are asymmetrically positive co-movements and have high left tail (extreme) dependencies, implying that the increase in non-renewable energy and economic growth can critically contribute to the environmental degradation, and the decrease in the consumption of non-renewable energy at a high level will consequently reduce the CO2 emissions at the same level. Based on several copula-based dependence measures, we document that between the two factors, the non-renewable energy has a stronger impact than the economic growth regarding the CO2 emissions. On the other hand, the growth rates of both economic globalization and renewable energy symmetrically negatively co-move with the growth rates of the CO2 emissions, but they have no extreme dependencies, indicating that these factors contribute to Argentina's environmental quality, in which the factor of renewable energy has a greater impact. Furthermore, the dynamic copula outcomes show that the (tail) dependencies of CO2 emissions on the non-renewable energy and economic growth are time-varying, while the pairs REN-CO2 and GLO-CO2 possess only dynamic dependencies, but no dynamic tail dependencies. Moreover, through the dynamic copula-based dependence, the environmental Kuznets curve (EKC) hypothesis can be estimated and illustrated explicitly. In addition, we leverage multivariate vine copulas for modelling dependence structures of the five variables simultaneously, which can reveal rich information regarding conditional associations among the relevant variables. Some policy implications are also provided to mitigate CO2 emissions. [ABSTRACT FROM AUTHOR]- Published
- 2022
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15. The Generalized Langevin Equation in Harmonic Potentials: Anomalous Diffusion and Equipartition of Energy.
- Author
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Didier, Gustavo and Nguyen, Hung D.
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LANGEVIN equations ,MONOTONIC functions ,VELOCITY - Abstract
We consider the generalized Langevin equation (GLE) in a harmonic potential with power law decay memory. We study the anomalous diffusion of the particle's displacement and velocity. By comparison with the free particle situation in which the velocity was previously shown to be either diffusive or subdiffusive, we find that, when trapped in a harmonic potential, the particle's displacement may either be diffusive or superdiffusive. Under slightly stronger assumptions on the memory kernel, namely, for kernels related to the broad class of completely monotonic functions, we show that both the free particle and the harmonically bounded GLE satisfy the equipartition of energy condition. This generalizes previously known results for the GLE under particular kernel instances such as the generalized Rouse kernel or (exactly) a power law function. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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16. Interfacial passivation with 4-chlorobenzene sulfonyl chloride for stable and efficient planar perovskite solar cells.
- Author
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Shini, Foo, Thambidurai, M., Dewi, Herlina Arianita, Jamaludin, Nur Fadilah, Bruno, Annalisa, Kanwat, Anil, Mathews, Nripan, Dang, Cuong, and Nguyen, Hung D.
- Abstract
The interfacial passivation technique is an effective method to improve the stability and photovoltaic performance of perovskite solar cells. Here, we demonstrate the importance of passivating undercoordinated halide ions in minimizing carrier losses at the perovskite/spiro-OMeTAD interface. 4-Chlorobenzene sulfonyl chloride (CBSC) has been utilized as a Lewis acid passivation material. CBSC molecules act as electron acceptors, which bind to the negatively charged undercoordinated halide ions and Pb–I antisite defects (PbI
3 − ). The champion CBSC-passivated perovskite device shows a high power conversion efficiency (PCE) of 20.02%, unlike the pristine device with an efficiency of 18.29%. Significant long term-stability in the CBSC passivated device is also observed, maintaining 93% of the initial PCE after 768 h stored in ambient conditions with 30% relative humidity. [ABSTRACT FROM AUTHOR]- Published
- 2022
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17. Estimating the Region of Attraction for Power Systems Using Gaussian Process and Converse Lyapunov Function.
- Author
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Zhai, Chao and Nguyen, Hung D.
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LYAPUNOV functions ,PHASOR measurement ,ANALYTIC functions ,RENEWABLE energy sources ,GAUSSIAN processes ,SYSTEM dynamics - Abstract
The significant penetration of renewable energy resources into power systems introduces intermittent disturbances that drive the system away from its stable operating point (i.e., equilibrium). Nevertheless, as long as the system states are still contained inside a region of attraction (ROA), the system will finally return to the normal operating equilibrium. Thus, the ROA plays a crucial role in the stability assessment of dynamical power systems under uncertainties. This brief introduces a novel framework to construct the ROA of a power system centered around a stable equilibrium by using stable state trajectories of system dynamics. Most existing works on estimating ROA rely on analytic Lyapunov functions, which are subject to two limitations: the analytic Lyapunov functions may not be always readily available and the resulting ROA may be overly conservative. This work overcomes these two limitations by leveraging the converse Lyapunov theorem in control theory to eliminate the need for an analytic Lyapunov function and learning unknown Lyapunov functions with the Gaussian process (GP) approach. In addition, a GP upper confidence bound (GP-UCB)-based sampling algorithm is designed to reconcile the tradeoff between the exploitation for enlarging the ROA and the exploration for enhancing the confidence level of the sample region. Within the constructed ROA, it is guaranteed in the probability that the system state will converge to the stable equilibrium with a confidence level. Extensive simulations and experimental validations are conducted to substantiate the assessment approach for the ROA of IEEE test systems and a real smartgrid using phasor measurement unit (PMU) data. It is demonstrated that the proposed approach can significantly enlarge the estimated ROA compared to that of the analytic Lyapunov counterpart. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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18. On the Hölder Regularity of a Linear Stochastic Partial-Integro-Differential Equation with Memory.
- Author
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McKinley, Scott A. and Nguyen, Hung D.
- Abstract
In light of recent work on particles fluctuating in linear viscoelastic fluids, we study a linear stochastic partial-integro-differential equation with memory that is driven by a stationary noise on a bounded, smooth domain. Using the framework of generalized stationary solutions introduced in McKinley and Nguyen (SIAM J Math Anal 50(5):5119–5160, 2018), we provide conditions on the differential operator and the noise to obtain the existence as well as Hölder regularity of the stationary solutions for the concerned equation. As an application of the regularity results, we compare to analogous classical results for the stochastic heat equation. When the 1d stochastic heat equation is driven by white noise, solutions are continuous with space and time regularity that is Hölder (1 / 2 - ϵ) and (1 / 4 - ϵ) respectively. When driven by colored-in-space noise, solutions can have a range of regularity properties depending on the structure of the noise. Here, we show that the particular form of colored-in-time memory that arises in viscoelastic diffusion applications, satisfying what is called the Fluctuation–Dissipation relationship, yields sample paths that are Hölder (1 / 2 - ϵ) and (1 / 2 - ϵ) in space and time. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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19. Peer-to-Peer Energy Trading Enabled Optimal Decentralized Operation of Smart Distribution Grids.
- Author
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Sampath, Lahanda Purage Mohasha Isuru, Paudel, Amrit, Nguyen, Hung D., Foo, Eddy Y. S., and Gooi, Hoay Beng
- Abstract
Currently, the distribution systems are moving towards decentralized operation due to the high penetration of distributed energy resources (DERs). Peer-to-peer (P2P) energy trading has been an emerging concept that promotes autonomous DER participation in energy markets while preserving their privacy concerns. In this work, a novel P2P energy trading enabled decentralized market framework is proposed for the optimal operation of distribution grids. Nodal agents and P2P agents are established as market participants, and market equilibrium is iteratively achieved via alternating direction method of multipliers based algorithms. The proposed market framework guarantees grid constraint satisfaction, market equilibrium, and global optimality for all market participants without violating their privacy concerns. The agent coordination and local optimization are designed such that fairness of the market clearing mechanism, prosumer autonomy, and prosumer anonymity is preserved without compromising the market efficiency. Further, costs/rewards of ancillary services associated with the P2P energy transactions are considered as trade-offs within the market mechanism, and those are accurately allocated to the respective trading pairs. The case studies illustrate the effectiveness and scalability of the proposed market framework. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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20. A Framework for Analytical Power Flow Solution Using Gaussian Process Learning.
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Pareek, Parikshit and Nguyen, Hung D.
- Abstract
This paper proposes a novel analytical solution framework for power flow (PF) solutions in active distribution networks under uncertainty. We use the Gaussian process (GP) regression to learn node voltage as a function of effective bus load or negative net-injection vector. The proposed approximation is valid over a subspace of load and provides an understanding of system behavior under uncertainty via GP interpretability. We interpret the relative variation extent of different node voltages using the quality ratio (QR) defined based on the hyper-parameters of GP. Further, the application of the proposed framework in calculation of voltage limit violation probability and dominant voltage influencer ranking has also been presented. Through test simulations for 33-bus and 56-bus systems, the proposed method achieves low mean absolute error (MAE) of order E-05 (pu) in voltage magnitude and E-04 (rad) in angle. The discussions on salient features of the proposed method and comparative analysis with large-scale Monte-Carlo simulations, and state-of-art methods is also presented for the proposed applications. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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21. Dietary supplementation of fish protein hydrolysate in high plant protein diets modulates growth, liver and kidney health, and immunity of barramundi (Lates calcarifer).
- Author
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Siddik, Muhammad A. B., Pham, Hung D., Francis, David S., Vo, Binh Van, and Shahjahan, Md
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DIETARY proteins ,GIANT perch ,PROTEIN hydrolysates ,PLANT proteins ,FISH growth ,DIETARY supplements ,LEUKOCYTES - Abstract
A 60‐day feeding trial was carried out to investigate the effects of fish protein hydrolysate (FPH) in high lupin meal (LM) diets on growth, health and immunity of barramundi. Fish were fed a fishmeal‐based control diet (FM) and three test diets to replace 75% fishmeal protein in the control diet by lupin meal alone (LM), lupin meal with FPH (LM+FPH) and fermented lupin meal with FPH supplementation (FLM+FPH). Each dietary group was stocked with 120 fish with an initial weight of 6.18 ± 0.08 g and fed three times daily to apparent satiation. Fish fed the LM diet had significantly lowered final body weight and specific growth rate compared with control and the remaining dietary groups (p <.05). The decreased growth performance was further exacerbated by liver steatosis and necrosis in the kidney of LM‐fed fish. Fish fed the FLM+FPH diet had significantly increased white blood cells and protein contents compared with the control. A significant reduction in mortality was observed in fish fed FLM+FPH compared with fish fed the LM diet following a 14‐day challenge with Vibrio harvei. Overall, this study suggests that high LM diets with FPH supplementation could be incorporated into the diet of juvenile barramundi without compromising growth and health. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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22. Experimental Study of a Modified Command Governor Adaptive Controller for Depth Control of an Unmanned Underwater Vehicle.
- Author
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Makavita, Charita D., Jayasinghe, Shantha G., Nguyen, Hung D., and Ranmuthugala, Dev
- Abstract
Command governor–based adaptive control (CGAC) is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles (UUVs) with parameter variations. CGAC is derived from standard model reference adaptive control (MRAC) by adding a command governor that guarantees acceptable transient performance without compromising stability and a command filter that improves the robustness against noise and time delay. Although simulation and experimental studies have shown substantial overall performance improvements of CGAC over MRAC for UUVs, it has also shown that the command filter leads to a marked reduction in initial tracking performance of CGAC. As a solution, this paper proposes the replacement of the command filter by a weight filter to improve the initial tracking performance without compromising robustness and the addition of a closed-loop state predictor to further improve the overall tracking performance. The new modified CGAC (M-CGAC) has been experimentally validated and the results indicate that it successfully mitigates the initial tracking performance reduction, significantly improves the overall tracking performance, uses less control force, and increases the robustness to noise and time delay. Thus, M-CGAC is a viable adaptive control algorithm for current and future UUV applications. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
23. Stochastic Model of the Adaptive Immune Response Predicts Disease Severity and Captures Enhanced Cross-Reactivity in Natural Dengue Infections.
- Author
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Nguyen, Hung D., Chaudhury, Sidhartha, Waickman, Adam T., Friberg, Heather, Currier, Jeffrey R., and Wallqvist, Anders
- Subjects
DENGUE hemorrhagic fever ,IMMUNE response ,STOCHASTIC models ,DENGUE ,INFECTION ,CROSS reactions (Immunology) - Abstract
The dengue virus circulates as four distinct serotypes, where a single serotype infection is typically asymptomatic and leads to acquired immunity against that serotype. However, the developed immunity to one serotype is thought to underlie the severe manifestation of the disease observed in subsequent infections from a different serotype. We developed a stochastic model of the adaptive immune response to dengue infections. We first delineated the mechanisms initiating and sustaining adaptive immune responses during primary infections. We then contrasted these immune responses during secondary infections of either a homotypic or heterotypic serotype to understand the role of pre-existing and reactivated immune pathways on disease severity. Comparison of non-symptomatic and severe cases from heterotypic infections demonstrated that overproduction of specific antibodies during primary infection induces an enhanced population of cross-reactive antibodies during secondary infection, ultimately leading to severe disease manifestations. In addition, the level of disease severity was found to correlate with immune response kinetics, which was dependent on beginning lymphocyte levels. Our results detail the contribution of specific lymphocytes and antibodies to immunity and memory recall that lead to either protective or pathological outcomes, allowing for the understanding and determination of mechanisms of protective immunity. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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24. Applicability Assessment of Electrocoagulation in Real Dyeing Wastewater Treatment.
- Author
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Hung, D. P., K Oanh, L. T., Chi, V. T. D., Thinh, L. N. Q., Nguyen, D. T., Tuan, N. Q., and Han, H. T. N.
- Subjects
WASTEWATER treatment ,IRON electrodes ,DYES & dyeing ,OPERATING costs ,ENERGY consumption - Abstract
In this study, the applicability of electrocoagulation using iron electrodes in real dyeing wastewater treatment was assessed based on pollutants removal efficiency, sludge generation, energy consumption and operation cost in practice. The effects of current density, pH, conductivity, and reaction time on treatment performance were evaluated. The operation cost of electrocoagulation was calculated including the energy cost, the iron plate cost, generated sludge treatment cost, and added substances cost. The results indicated that the colour, CODcr and TSS removal efficiencies were high and quite stable with short reaction time (reached 92.07 ± 1.21%, 65.7 ± 1.47%, and 89.8 ± 1.2%, respectively, with only 15 min). Average sludge generation, specific energy consumption, and operation cost were determined respectively as 0.645±0.0543 kg/m3, 1.182 kWh/m3 and 0.517 USD/m3. Coagulationflocculation using FeSO4 was performed as a control experiment as well. Compared to coagulationflocculation, electrocoagulation has the same removal efficiency but has less generated sludge (only 50%) and little to no added chemicals. Therefore, the operating cost was quite less than the others, with only 0.517 USD/m3 instead of 1.99 USD/m3 (equal to 1/3.5). [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
25. Contribute to knowledge about risks in implementing green building projects in developing countries: a case of Vietnam.
- Author
-
Nguyen, Hung D, Do, Quang N H, and Macchion, Laura
- Published
- 2021
- Full Text
- View/download PDF
26. An optical observational cluster mass function at z ∼ 1 with the ORELSE survey.
- Author
-
Hung, D, Lemaux, B C, Gal, R R, Tomczak, A R, Lubin, L M, Cucciati, O, Pelliccia, D, Shen, L, Le Fèvre, O, Zamorani, G, Wu, P-F, Kocevski, D D, Fassnacht, C D, and Squires, G K
- Subjects
MONTE Carlo method ,LARGE scale structure (Astronomy) ,GALAXY clusters ,PHYSICAL cosmology ,REDSHIFT - Abstract
We present a new mass function of galaxy clusters and groups using optical/near-infrared (NIR) wavelength spectroscopic and photometric data from the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) survey. At z ∼ 1, cluster mass function studies are rare regardless of wavelength and have never been attempted from an optical/NIR perspective. This work serves as a proof of concept that z ∼ 1 cluster mass functions are achievable without supplemental X-ray or Sunyaev-Zel'dovich data. Measurements of the cluster mass function provide important contraints on cosmological parameters and are complementary to other probes. With ORELSE, a new cluster finding technique based on Voronoi tessellation Monte Carlo (VMC) mapping, and rigorous purity and completeness testing, we have obtained ∼240 galaxy overdensity candidates in the redshift range 0.55 < z < 1.37 at a mass range of 13.6 < log (M/M
⊙ ) < 14.8. This mass range is comparable to existing optical cluster mass function studies for the local universe. Our candidate numbers vary based on the choice of multiple input parameters related to detection and characterization in our cluster finding algorithm, which we incorporated into the mass function analysis through a Monte Carlo scheme. We find cosmological constraints on the matter density, Ωm , and the amplitude of fluctuations, σ8 , of |$\Omega _{m} = 0.250^{+0.104}_{-0.099}$| and |$\sigma _{8} = 1.150^{+0.260}_{-0.163}$|. While our Ωm value is close to concordance, our σ8 value is ∼2σ higher because of the inflated observed number densities compared to theoretical mass function models owing to how our survey targeted overdense regions. With Euclid and several other large, unbiased optical surveys on the horizon, VMC mapping will enable optical/NIR cluster cosmology at redshifts much higher than what has been possible before. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
27. Legumain Induces Oral Cancer Pain by Biased Agonism of Protease-Activated Receptor-2.
- Author
-
Nguyen Huu Tu, Jensen, Dane D., Anderson, Bethany M., Chen, Elyssa, Jimenez-Vargas, Nestor N., Scheff, Nicole N., Kenji Inoue, Tran, Hung D., Dolan, John C., Meek, Tamaryn A., Hollenberg, Morley D., Liu, Cheng Z., Vanner, Stephen J., Janal, Malvin N., Bunnett, Nigel W., Edgington-Mitchell, Laura E., and Schmidt, Brian L.
- Subjects
CANCER pain ,ORAL cancer ,ADENYLATE cyclase ,PROTEIN kinases ,SQUAMOUS cell carcinoma - Abstract
Oral squamous cell carcinoma (OSCC) is one of the most painful cancers, which interferes with orofacial function including talking and eating. We report that legumain (Lgmn) cleaves protease-activated receptor-2 (PAR
2 ) in the acidic OSCC microenvironment to cause pain. Lgmn is a cysteine protease of late endosomes and lysosomes that can be secreted; it exhibits maximal activity in acidic environments. The role of Lgmn in PAR2 -dependent cancer pain is unknown. We studied Lgmn activation in human oral cancers and oral cancer mouse models. Lgmn was activated in OSCC patient tumors, compared with matched normal oral tissue. After intraplantar, facial or lingual injection, Lgmn evoked nociception in wild-type (WT) female mice but not in female mice lacking PAR2 in NaV1.8-positive neurons (Par2 Nav 1.8), nor in female mice treated with a Lgmn inhibitor, LI-1. Inoculation of an OSCC cell line caused mechanical and thermal hyperalgesia that was reversed by LI-1. Par2 Nav 1.8 and Lgmn deletion attenuated mechanical allodynia in female mice with carcinogen-induced OSCC. Lgmn caused PAR2 -dependent hyperexcitability of trigeminal neurons from WT female mice. Par2 deletion, LI-1, and inhibitors of adenylyl cyclase or protein kinase A (PKA) prevented the effects of Lgmn. Under acidified conditions, Lgmn cleaved within the extracellular N terminus of PAR2 at Asn30 ↓Arg31 , proximal to the canonical trypsin activation site. Lgmn activated PAR2 by biased mechanisms in HEK293 cells to induce Ca2+ mobilization, cAMP formation, and PKA/protein kinase D (PKD) activation, but not β-arrestin recruitment or PAR2 endocytosis. Thus, in the acidified OSCC microenvironment, Lgmn activates PAR2 by biased mechanisms that evoke cancer pain. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
28. The generalized Langevin equation with power-law memory in a nonlinear potential well.
- Author
-
Glatt-Holtz, Nathan E, Herzog, David P, McKinley, Scott A, and Nguyen, Hung D
- Subjects
LANGEVIN equations ,POTENTIAL well ,INVARIANT measures ,PROBABILITY measures ,MEMORY ,UNIQUENESS (Mathematics) ,INTEGRO-differential equations - Abstract
The generalized Langevin equation (GLE) is a stochastic integro-differential equation that has been used to describe the velocity of microparticles in viscoelastic fluids. In this work, we consider the large-time asymptotic properties of a Markovian approximation to the GLE in the presence of a wide class of external potential wells. The qualitative behavior of the GLE is largely determined by its memory kernel K, which summarizes the delayed response of the fluid medium on the particles past movement. When K can be expressed as a finite sum of exponentials, it has been shown that long-term time-averaged properties of the position and velocity do not depend on K at all. In certain applications, however, it is important to consider the GLE with a power law memory kernel. Using the fact that infinite sums of exponentials can have power law tails, we study the infinite-dimensional version of the Markovian GLE in a potential well. In the case where the memory kernel K is integrable (i.e. in the asymptotically diffusive regime), we are able to extend previous results and show that there is a unique stationary distribution for the GLE system and that the long-term statistics of the position and velocity do not depend on K. However, when K is not integrable (i.e. in the asymptotically subdiffusive regime), we are able to show the existence of an invariant probability measure but uniqueness remains an open question. In particular, the method of asymptotic coupling used in the integrable case to show uniqueness does not apply when K fails to be integrable. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
29. Establishing a new technique for discovering large-scale structure using the ORELSE survey.
- Author
-
Hung, D, Lemaux, B C, Gal, R R, Tomczak, A R, Lubin, L M, Cucciati, O, Pelliccia, D, Shen, L, Le Fèvre, O, Wu, P-F, Kocevski, D D, Mei, S, and Squires, G K
- Subjects
MONTE Carlo method ,GALACTIC evolution ,SPECTROSCOPIC imaging ,GALAXY clusters ,GALAXIES ,CATALOGS ,REDSHIFT - Abstract
The Observations of Redshift Evolution in Large-Scale Environments (ORELSE) survey is an ongoing imaging and spectroscopic campaign initially designed to study the effects of environment on galaxy evolution in high-redshift (z ∼ 1) large-scale structures. We use its rich data in combination with a powerful new technique, Voronoi tessellation Monte Carlo (VMC) mapping, to search for serendipitous galaxy overdensities at 0.55 < z < 1.37 within 15 ORELSE fields, a combined spectroscopic footprint of ∼1.4 deg
2 . Through extensive tests with both observational data and our own mock galaxy catalogues, we optimize the method's many free parameters to maximize its efficacy for general overdensity searches. Our overdensity search yielded 402 new overdensity candidates with precisely measured redshifts and an unprecedented sensitivity down to low total overdensity masses (|$\mathcal {M}_{\mathrm{ tot}}\gtrsim5\times 10^{13}$| M⊙ ). Using the mock catalogues, we estimated the purity and completeness of our overdensity catalogue as a function of redshift, total mass, and spectroscopic redshift fraction, finding impressive levels of both 0.92/0.83 and 0.60/0.49 for purity/completeness at z = 0.8 and z = 1.2, respectively, for all overdensity masses at spectroscopic fractions of ∼20 per cent. With VMC mapping, we are able to measure precise systemic redshifts, provide an estimate of the total gravitating mass, and maintain high levels of purity and completeness at z ∼ 1 even with only moderate levels of spectroscopy. Other methods (e.g. red-sequence overdensities and hot medium reliant detections) begin to fail at similar redshifts, which attests to VMC mapping's potential to be a powerful tool for current and future wide-field galaxy evolution surveys at z ∼ 1 and beyond. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
30. Persistence of the colour–density relation and efficient environmental quenching to z ∼ 1.4.
- Author
-
Lemaux, B C, Tomczak, A R, Lubin, L M, Gal, R R, Shen, L, Pelliccia, D, Wu, P-F, Hung, D, Mei, S, Le Fèvre, O, Rumbaugh, N, Kocevski, D D, and Squires, G K
- Subjects
STELLAR mass ,GALAXIES ,GALAXY clusters ,GALAXY formation ,STAR formation ,POPULATION density - Abstract
Using ∼5000 spectroscopically confirmed galaxies drawn from the Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey we investigate the relationship between colour and galaxy density for galaxy populations of various stellar masses in the redshift range 0.55 ≤ z ≤ 1.4. The fraction of galaxies with colours consistent with no ongoing star formation (f
q ) is broadly observed to increase with increasing stellar mass, increasing galaxy density, and decreasing redshift, with clear differences observed in fq between field and group/cluster galaxies at the highest redshifts studied. We use a semi-empirical model to generate a suite of mock group/cluster galaxies unaffected by environmentally specific processes and compare these galaxies at fixed stellar mass and redshift to observed populations to constrain the efficiency of environmentally driven quenching (Ψconvert ). High-density environments from 0.55 ≤ z ≤ 1.4 appear capable of efficiently quenching galaxies with |$\log (\mathcal {M}_{\ast }/\mathcal {M}_{\odot })\gt 10.45$|. Lower stellar mass galaxies also appear efficiently quenched at the lowest redshifts studied here, but this quenching efficiency is seen to drop precipitously with increasing redshift. Quenching efficiencies, combined with simulated group/cluster accretion histories and results on the star formation rate-density relation from a companion ORELSE study, are used to constrain the average time from group/cluster accretion to quiescence and the elapsed time between accretion and the inception of the quenching event. These time-scales were constrained to be 〈 tconvert 〉 = 2.4 ± 0.3 and 〈 tdelay 〉 = 1.3 ± 0.4 Gyr, respectively, for galaxies with |$\log (\mathcal {M}_{\ast }/\mathcal {M}_{\odot })\gt 10.45$| and 〈 tconvert 〉 = 3.3 ± 0.3 and 〈 tdelay 〉 = 2.2 ± 0.4 Gyr for lower stellar mass galaxies. These quenching efficiencies and associated time-scales are used to rule out certain environmental mechanisms as being the primary processes responsible for transforming the star formation properties of galaxies over this 4 Gyr window in cosmic time. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
31. A Framework for Robust Long-Term Voltage Stability of Distribution Systems.
- Author
-
Nguyen, Hung D., Dvijotham, Krishnamurthy, Yu, Suhyoun, and Turitsyn, Konstantin
- Abstract
Power injection uncertainties in distribution power grids, which are mostly induced by aggressive introduction of intermittent renewable sources, may drive the system away from normal operating regimes and potentially lead to the loss of long-term voltage stability (LTVS). Naturally, there is an ever increasing need for a tool for assessing the LTVS of a distribution system. This paper presents a fast and reliable tool for constructing inner approximations of LTVS regions in multidimensional injection space such that every point in our constructed region is guaranteed to be solvable. Numerical simulations demonstrate that our approach outperforms all existing inner approximation methods in most cases. Furthermore, the constructed regions are shown to cover substantial fractions of the true voltage stability region. This paper will later discuss a number of important applications of the proposed technique, including fast screening for viable injection changes, constructing an effective solvability index and rigorously certified loadability limits. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
32. Optical and geometrical properties of cirrus clouds from lidar measurements above Hanoi, Vietnam.
- Author
-
Bui, Hai V., Le, Manh D., Dinh, Trung V., Nguyen, Tuan X., Pham, Tien M., Tran, Hung N., Pham, Bang D., Nguyen, Bao T. T., Nguyen, Binh T., and Nguyen, Hung D.
- Published
- 2019
- Full Text
- View/download PDF
33. Total Synthesis of Lophirone F Hexamethyl Ether.
- Author
-
Le, Hoang M., Mac, Hung D., Oh, Chang Ho, and Do, Dung T.
- Subjects
COCARCINOGENS ,NATURAL products ,TETRAHYDROFURAN synthesis ,ARYL group ,ETHERS ,FLAVONOIDS - Abstract
A practical and efficient approach for the total synthesis of the (±)‐lophirone F hexamethyl ether was reported. The compound was synthesized in 8 steps with a 14.6 % overall yield. The key features of this synthesis are the stereoselective synthesis of a 2,5‐diaryl‐3,4‐disubstituted tetrahydrofuran skeleton via a sequence of [3+2] cycloaddition/Krapcho decarboxylation and the installation of two aryl ketone groups bypassing potential epimerization of adjacent stereocenters. Lophirone F, a hexaphenolic biflavonoid natural product, shows inhibitory activities against tumor promoter. A new route (8 steps) to the natural product derivative lophirone F hexamethyl ether was developed. Key steps involve the [3+2] cycloaddition of donor–acceptor cyclopropane with aldehyde to construct the tetrahydrofuran core of the natural product. The route is flexible and would be amenable to the synthesis of analogues of this class of natural products. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
34. Relaxation behaviors of the bismuth-substituted yttrium iron garnet in the microwave range.
- Author
-
Hung, D. S., Fu, Y. P., Lee, S. F., Yao, Y. D., and Abdul Ahad, Faris B.
- Subjects
YTTRIUM ,GARNET ,POLYCRYSTALLINE semiconductors ,FERROMAGNETIC materials ,ALUMINUM - Abstract
The spin damping behavior of the bismuth-substituted yttrium iron garnets (Bi
x Y3-x Fe5 O12 ) prepared by the coprecipitation process was investigated using the ferromagnetic resonant (FMR) in this study. By analyzing the FMR responses, the spin damping coefficient of the x=0.25-1.25 in polycrystalline Bi:YIG (yttrium aluminum garnet) samples was obtained from the 3 dB linewidth of their FMR spectra. The data demonstrated that the damping coefficient started from 3.21×10-3 for x=0.25 and went to its minimum value of 0.31×10-3 for x=0.75. However, the damping coefficient enhanced to 8.55×10-3 with increasing of the bismuth concentration to x=1.25. The results revealed that the spin damping behavior of the Bi:YIG garnets was strongly dependent on a YFeO3 (111) phase. [ABSTRACT FROM AUTHOR]- Published
- 2010
- Full Text
- View/download PDF
35. Investigation on electromagnetic and microwave absorbing properties of La0.7Sr0.3MnO3-δ/carbon nanotube composites.
- Author
-
Tsay, C. Y., Yang, R. B., Hung, D. S., Hung, Y. H., Yao, Y. D., and Lin, C. K.
- Subjects
ELECTROMAGNETIC compatibility ,CARBON nanotubes ,CARBON composites ,PERMITTIVITY ,PERMEABILITY - Abstract
In this study, the influence of the addition of carbon nanotube (CNT) (0, 0.5, 1.0, and 2.0 wt %) on complex permittivity, complex permeability, and reflection loss for La
0.7 Sr0.3 MnO3-δ (LSMO)/ polymer composites was investigated. Microwave absorbing composites were prepared by molding and curing a mixture of LSMO powders, CNTs, and epoxy resin. The complex permittivity and complex permeability for LSMO/CNT composites were examined by a cavity perturbation technique. The experimental results showed that the complex permittivity increased with increasing CNT addition and the imaginary part of the permeability decreased with rising frequency. In the present study, a microwave absorbing composite filled with 80 wt % LSOM powders and 2 wt % CNTs exhibited the optimum performance, that is, the microwave absorbing peak was -22.85 dB at 9.5 GHz and the -10 dB absorbing bandwidth reached 3.3 GHz for the sample with a matching thickness of 3 mm. [ABSTRACT FROM AUTHOR]- Published
- 2010
- Full Text
- View/download PDF
36. Dielectric constant at x-band microwave frequencies for multiferroic BiFeO3 thin films.
- Author
-
Abdul Ahad, Faris B., Hung, D. S., Yao, Y. D., Lee, S. F., Tu, C. S., Wang, T. H., Chen, Y. Y., and Fu, Y. P.
- Subjects
DIELECTRICS research ,MICROWAVES ,ELECTRIC properties of thin films ,MAGNETIZATION ,TRANSITION temperature ,PERMITTIVITY - Abstract
The magnetic-induced dielectric responses of BiFeO
3 (BFO) thin films were measured at the X-band microwave frequency ranged from 7 to 12.5 GHz. The measurement was given initially by a high-precision cavity microwave resonator without magnetic field. Both the real and imaginary parts of the permittivity showed its dielectric property as a function of the measuring frequency. The X-band dielectric responses of the BFO thin film were then measured by a controlled magnetic field at room temperature. The data demonstrated up to 2.2% dielectric tunability by using only 3.46 kOe magnetic field at TE107 mode (9.97705 GHz). [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
37. Complex permittivity and permeability of iron-based composite absorbers measured by cavity perturbation method in X-band frequency range.
- Author
-
Yang, R. B., Tsay, C. Y., Hung, D. S., Liang, W. F., Yao, Y. D., and Lin, C. K.
- Subjects
PERMITTIVITY ,PERMEABILITY ,PERTURBATION theory ,IRON powder ,EPOXY resins - Abstract
A cavity perturbation resonance technique is used to determine the complex permittivity and permeability of iron-based composite absorbers prepared by mixing various weight percentages of carbonyl iron powder with epoxy as the matrix. The complex permittivity ([variant_greek_epsilon]
′ -j[variant_greek_epsilon]″ ) and permeability (μ′ -jμ″ ) are measured around X-band (7–12.5 GHz for permittivity and 7.5–14 GHz for permeability) by the cavity perturbation resonance technique and the results are compared with those obtained by the transmission/reflection method. Experimental results show that the average differences of real parts of permittivity ([variant_greek_epsilon]′ ) and real and imaginary parts of permeability (μ′ and μ″ ) measured by these two techniques are less than 10%. The differences in [variant_greek_epsilon]″ , however, is apparently higher than the others. As a general trend, the difference increases with increasing weight percentage of carbonyl iron. [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
38. Permittivity study of multiferroic AlN/NiFe/AlN multilayer films.
- Author
-
Hung, D. S., Yao, Y. D., Wei, D. H., Wu, K. T., Hsu, J. C., Ding, T., and Chen, Y. C.
- Abstract
NiFe inserted layer with different thicknesses on the dielectric properties of multiferroic AlN/NiFe/AlN multilayer films fabricated on the B270 glass substrates by the reactive sputtering technique was studied. The variation of dielectric constant for multilayer films is dependent on the thickness of the NiFe inserted layer observed from 40 Hz to 30 MHz. In this work, single AlN layer exhibits dielectric constant value of around 6.5. However, we find that the dielectric constant of the AlN/NiFe/AlN multilayer films is raised up to 60 for even with a 1 nm thick NiFe inserted layer. Additionally, this work also indicates that the dielectric tunability of AlN/NiFe/AlN films is dependent on the external magnetic field. These results conclude some magnetoelectric properties of AlN films those in relation to the NiFe ferromagnetic inserted layer. Possible mechanisms for the enhanced dielectric constant in the AlN/NiFe/AlN films have been discussed in the paper. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
39. Holocene ostracod assemblages from the Co To Islands, northeastern Vietnam.
- Author
-
Niiyama, Sota, Tanaka, Gengo, Komatsu, Toshifumi, Doan, Hung D., Nguyen, Hung B., Trinh, Ha T., and Nguyen, Minh T.
- Subjects
OSTRACODA ,HOLOCENE Epoch ,BIOGEOGRAPHY ,SPECIES ,SEDIMENT sampling - Abstract
In this study, we investigated ostracod assemblages from the Co To Islands in northeastern Vietnam. We identified 77 ostracod species belonging to 46 genera in nine surface sediment samples and recognized three biofacies (I, II, and III) based on Q-mode cluster analysis. The dominant species of biofacies I and II were Aurila hataii , Loxoconcha japonica , and Xestoleberis hanaii , which commonly occur in seaweed beds from southern China to Japan. This is the first report on the ostracod assemblage from the open-sea area in northeastern Vietnam. We clarified that the ostracod assemblages in the Gulf of Tongking, including northern Vietnam, have a strong biogeographical relationship with East Asia seas. A new species, Loxoconcha cotoensis sp. nov., was described herein from the Co To Islands (http://www.zoobank.org/NomenclaturalActs/41d3fb9f-ae17-4215-82c1-0874a8bf1a30 , last access: 3 June 2019). [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
40. Constructing Convex Inner Approximations of Steady-State Security Regions.
- Author
-
Nguyen, Hung D., Dvijotham, Krishnamurthy, and Turitsyn, Konstantin
- Subjects
STEADY-state flow ,APPROXIMATION theory ,FIXED point theory ,NONLINEAR equations ,ELECTRIC power systems - Abstract
We propose a scalable optimization framework for estimating convex inner approximations of the steady-state security sets. The framework is based on Brouwer fixed point theorem applied to a fixed-point form of the power flow equations. It establishes a certificate for the self-mapping of a polytope region constructed around a given feasible operating point. This certificate is based on the explicit bounds on the nonlinear terms that hold within the self-mapped polytope. The shape of the polytope is adapted to find the largest approximation of the steady-state security region. While the corresponding optimization problem is nonlinear and non-convex, every feasible solution found by local search defines a valid inner approximation. The number of variables scales linearly with the system size, and the general framework can naturally be applied to other nonlinear equations with affine dependence on inputs. Test cases, with the system sizes up to 1354 buses, are used to illustrate the scalability of the approach. The results show that the approximated regions are not unreasonably conservative and that they cover substantial fractions of the true steady-state security regions for most medium-sized test cases. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
41. The Small-Mass Limit and White-Noise Limit of an Infinite Dimensional Generalized Langevin Equation.
- Author
-
Nguyen, Hung D.
- Subjects
WHITE noise ,LANGEVIN equations ,PROBABILITY theory ,GRAPH theory ,LIPSCHITZ spaces - Abstract
We study asymptotic properties of the Generalized Langevin Equation (GLE) in the presence of a wide class of external potential wells with a power-law decay memory kernel. When the memory can be expressed as a sum of exponentials, a class of Markovian systems in infinite-dimensional spaces is used to represent the GLE. The solutions are shown to converge in probability in the small-mass limit and the white-noise limit to appropriate systems under minimal assumptions, of which no global Lipschitz condition is required on the potentials. With further assumptions about space regularity and potentials, we obtain L1
convergence in the white-noise limit. [ABSTRACT FROM AUTHOR] - Published
- 2018
- Full Text
- View/download PDF
42. ANOMALOUS DIFFUSION AND THE GENERALIZED LANGEVIN EQUATION.
- Author
-
MCKINLEY, SCOTT A. and NGUYEN, HUNG D.
- Subjects
LANGEVIN equations ,MEAN square algorithms ,KERNEL (Mathematics) ,MATHEMATICAL models ,NUMERICAL analysis - Abstract
The generalized Langevin equation (GLE) is a stochastic integro-differential equation that is commonly used to describe the velocity of microparticles that move randomly in viscoelastic uids. Such particles commonly exhibit what is known as anomalous subdiffusion, which is to say that their position mean-squared displacement (MSD) scales sublinearly with time. While it is common in the literature to observe that there is a relationship between the MSD and the memory structure of the GLE, and that there exist special cases where explicit solutions exist, this connection has never been fully characterized. Here, we establish a class of memory kernels for which the GLE is well-defined, we investigate the associated regularity properties of solutions, and we prove that large-time asymptotic behavior of the particle MSD is entirely determined by the tail behavior of the GLE's memory kernel. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
43. Inducible T-Cell Co-Stimulator Impacts Chronic Graft-Versus-Host Disease by Regulating Both Pathogenic and Regulatory T Cells.
- Author
-
Mengmeng Zhang, Yongxia Wu, Bastian, David, Supinya Iamsawat, Jinsam Chang, Daenthanasanmak, Anusara, Nguyen, Hung D., Schutt, Steven, Min Dai, Fangping Chen, Woong-Kyung Suh, and Xue-Zhong Yu
- Subjects
T cells ,HEMATOPOIETIC stem cell transplantation - Abstract
The incidence of chronic graft-versus-host disease (cGVHD) is on the rise and still the major cause of morbidity and mortality among patients after allogeneic hematopoietic stem cell transplantation (HCT). Both donor T and B cells contribute to the pathogenesis of cGVHD. Inducible T-cell co-stimulator (ICOS), a potent co-stimulatory receptor, plays a key role in T-cell activation and differentiation. Yet, how ICOS regulates the development of cGVHD is not well understood. Here, we investigated the role of ICOS in cGVHD pathogenesis using mice with germline or regulatory T cell (Treg)-specific ICOS deficiency. The recipients of ICOS
-/- donor grafts had reduced cGVHD compared with wild-type controls. In recipients of ICOS-/- donor grafts, we observed significant reductions in donor T follicular helper (Tfh), Th17, germinal center B-cell, and plasma cell differentiation, coupled with lower antibody production. Interestingly, Tregs, including follicular regulatory T (Tfr) cells, were also impaired in the absence of ICOS. Using ICOS conditional knockout specific for Foxp3+ cells, we found that ICOS was indispensable for optimal survival and homeostasis of induced Tregs during cGVHD. Furthermore, administration of anti-ICOS alleviated cGVHD severity via suppressing T effector cells without affecting Treg generation. Taken together, ICOS promotes T- and B-cell activation and differentiation, which can promote cGVHD development; however, ICOS is critical for the survival and homeostasis of iTregs, which can suppress cGVHD. Hence, ICOS balances the development of cGVHD and could offer a potential target after allo-HCT in the clinic. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
44. A Fully Integrated Quartz MEMS VHF TCXO.
- Author
-
Kubena, Randall L., Stratton, Frederic P., Nguyen, Hung D., Kirby, Deborah J., Chang, David T., Joyce, Richard J., Yong, Yook-Kong, Garstecki, Jeffrey F., Cross, Matthew D., and Seman, S. E.
- Subjects
MICROELECTROMECHANICAL systems ,VHF oscillators ,TEMPERATURE compensation in electronic circuits ,CRYSTAL oscillators ,COMPLEMENTARY metal oxide semiconductors ,VACUUM packaging - Abstract
We report on a 32-MHz quartz temperature compensated crystal oscillator (TCXO) fully integrated with commercial CMOS electronics and vacuum packaged at wafer level using a low-temperature MEMS-after quartz process. The novel quartz resonator design provides for stress isolation from the CMOS substrate, thereby yielding classical AT-cut f/T profiles and low hysteresis which can be compensated to < ±0.2 parts per million over temperature using on-chip third-order compensation circuitry. The TCXO operates at low power of 2.5 mW and can be thinned to $\le 300~\mu \text{m}$ as part of the wafer-level eutectic encapsulation. Full integration with large state-of-the-art CMOS wafers is possible using carrier wafer techniques. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
45. Electroconducting Elements of the Ultradeep Fluid-Fault Systems as Indicators of Seismically Active Zones of the Eastern Margin of the Eurasian Continent: Evidence from Magnetotelluric Data.
- Author
-
Nikiforov, V. M., Zhukovin, A. Yu., Shkabarnya, G. N., Kaplun, V. B., Varentsov, I. M., Palshin, N. A., Cuong, D. H., Trung, N. N., and Hung, D. Q.
- Subjects
FAULT zones ,FLUID dynamics ,EARTHQUAKE zones ,MAGNETOTELLURICS - Abstract
A fundamentally new conclusion that zones of high seismic activity are controlled by electroconducting (fluid-saturated) fragments rather than by the entire deep fault is drawn. It is shown that the areal abundance of earthquake foci in geoelectric blocks of the Earth’s crust within Sakhalin and Vietnam containing electroconducting formations is mostly controlled by their roof occurring at a depth of ≤15 km. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
46. The Equivalent Linearization Method with a Weighted Averaging for Solving Undamped Nonlinear Oscillators.
- Author
-
Hieu, D. V., Hai, N. Q., and Hung, D. T.
- Subjects
MATHEMATICAL equivalence ,PERTURBATION theory ,NONLINEAR oscillators ,HOMOTOPY theory ,PROBLEM solving - Abstract
The Equivalent Linearization Method (ELM) with a weighted averaging is applied to analyze five undamped oscillator systems with nonlinearities. The results obtained via this method are compared with the ones achieved by Parameterized Perturbation Method (PPM), Min–Max Approach (MMA), Variational Iteration Method (VIM), Homotopy Perturbation Method (HPM), Energy Balance Method (EBM), Harmonic Balance Method (HBM), 4th-Order Runge-Kutta Method, and the exact ones. The obtained results demonstrate that this method is very convenient for solving nonlinear equations and also can be successfully applied to a lot of practical engineering and physical problems. [ABSTRACT FROM AUTHOR]
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- 2018
- Full Text
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47. ACUTE RESPIRATORY DISTRESS SYNDROME AMONG SEVERE BURN PATIENTS IN A DEVELOPING COUNTRY: APPLICATION RESULT OF THE BERLIN DEFINITION.
- Author
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Lam, N. N., Hung, T. D., and Hung, D. K.
- Subjects
ADULT respiratory distress syndrome ,BURN patients ,BURNS & scalds ,INTENSIVE care units ,TREATMENT for burns & scalds - Abstract
Copyright of Annals of Burns & Fire Disasters is the property of Euro-Mediterranean Council for Burns & Fire Disasters and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2018
48. Unexpected length dependence of excited-state charge transfer dynamics for surface-confined perylenediimide ensembles.
- Author
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Mazaheripour, Amir, Kladnik, Gregor, Jocson, Jonah-Micah, Wardrip, Austin G., Markegard, Cade B., Frey, Nathan, Cossaro, Albano, Floreano, Luca, Verdini, Alberto, Bartlett, Andrew, Burke, Anthony M., Hüsken, Nina, Miller, Kelsey, Van Wonterghem, Katarina, Lopez, Robert, Lu, Michelle, Masurkar, Amrita, Dickson, Mary N., Sharifzadeh, Sahar, and Nguyen, Hung D.
- Published
- 2017
- Full Text
- View/download PDF
49. Increased risk of chronic osteomyelitis after hip replacement: a retrospective population-based cohort study in an Asian population.
- Author
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Hung, D.-Z., Tien, N., Lin, C.-L., Lee, Y.-R., Wang, C., Chen, J.-J., and Lim, Y.-P.
- Subjects
OSTEOMYELITIS ,TOTAL hip replacement ,COHORT analysis ,IMMUNE system ,OPERATIVE surgery ,DISEASE risk factors - Abstract
The correlation between hip replacement (Hip-Repl) and chronic osteomyelitis (COM) has not been studied in Asian populations. Thus, we assessed Hip-Repl-related risk of developing COM via a population-based, nationwide, retrospective cohort study. The Hip-Repl cohort was obtained from Taiwan's Longitudinal Health Insurance Database 2000, and included patients who underwent Hip-Repl between 2000 and 2010; the control cohort was also selected from this database. Patients with a history of COM were excluded in both cohorts. We used univariate and multivariate Cox proportional hazards regression models to calculate the adjusted hazard ratios (aHRs) by age, sex, and comorbidities for developing COM. A total of 5349 patients who received a Hip-Repl and 10,372 matched controls were enrolled. In the Hip-Repl group, the risk for COM was 4.18-fold [95 % confidence interval (CI) = 2.24-7.80] higher than that in the control group after adjustment. For patients aged ≤65 years, the risk was 10.0-fold higher (95 % CI = 2.89-34.6). Furthermore, the risk was higher in the Hip-Repl cohort than in the non-Hip-Repl cohort, for both patients without comorbidity (aHR = 16.5, 95 % CI = 2.07-132.3) and those with comorbidity (aHR = 3.49, 95 % CI = 1.78-6.83). The impact of Hip-Repl on the risk for COM was greater among patients not using immunosuppressive drugs, and occurred during the first postoperative year. Patients who received Hip-Repl have an increased risk of developing COM. This risk was higher among males and patients aged 65 years or younger, and during the first postoperative year. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
50. A SUMO-ubiquitin relay recruits proteasomes to chromosome axes to regulate meiotic recombination.
- Author
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Rao, H. B. D. Prasada, Huanyu Qiao, Bhatt, Shubhang K., Bailey, Logan R. J., Tran, Hung D., Bourne, Sarah L., Qiu, Wendy, Deshpande, Anusha, Sharma, Ajay N., Beebout, Connor J., Pezza, Roberto J., and Hunter, Neil
- Published
- 2017
- Full Text
- View/download PDF
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