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A Vapor Sensor Based on a Porous Silicon Microcavity for the Determination of Solvent Solutions
Huy Bui,Thuy Van Nguyen,The Anh Nguyen,Thanh Binh Pham,Quoc Trung Dang,Thuy Chi Do,Quang Minh Ngo,Roberto Coisson,Van Hoi Pham 한국광학회 2014 Current Optics and Photonics Vol.18 No.4
A porous silicon microcavity (PSMC) sensor has been made for vapors of solvent solutions, and a method has been developed in order to obtain simultaneous determination of two volatile substances with different concentrations. In our work, the temperature of the solution and the velocity of the air stream flowing through the solution have been used to control the response of the sensor for ethanol and acetone solutions. We study the dependence of the cavity-resonant wavelength shift on solvent concentration, velocity of the airflow and solution temperature. The wavelength shift depends linearly on concentration and increases with solution temperature and velocity of the airflow. The dependence of the wavelength shift on the solution temperature in the measurement contains properties of the temperature dependence of the solvent vapor pressure, which characterizes each solvent. As a result, the dependence of the wavelength shift on the solution temperature discriminates between solutions of ethanol and acetone with different concentrations. This suggests a possibility for the simultaneous determination of the volatile substances and their concentrations.
Pham Hong Quang,유성초,Do Hong Minh,Huynh Thanh Nhan,Nguyen Huy Sinh 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.3
Substitution of Mn by Fe, Co, and Ni ions suppresses double exchange (DE), leading to a reduction in ferromagnetic interaction, or equivalently to lower values of Curie temperature, TC. The intensity of the electron paramagnetic resonance (EPR) line decreases exponentially with temperature, and the temperature dependence of EPR linewidth undergoes a minimum near TC. The activation energy values, Ea, derived from the temperature dependence of EPR line intensity, are equal to 0.074 eV, 0.093 eV and 0.086 eV for TM = Fe, Co, and Ni, respectively. In the case of cobalt substitution, an anomaly in the thermal evolution of the EPR linewidth has been observed. We attribute the cause of this anomaly to a Jahn-Teller transition or an electronic phase separation.
( Hai The Pham ),( Phuong Ha Vu ),( Thuy Thu Thi Nguyen ),( Ha Viet Thi Bui ),( Huyen Thanh Thi Tran ),( Hanh My Tran ),( Huy Quang Nguyen ),( Byung Hong Kim ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.10
Sediment bioelectrochemical systems (SBESs) can be integrated into brackish aquaculture ponds for in-situ bioremediation of the pond water and sediment. Such an in-situ system offers advantages including reduced treatment cost, reusability and simple handling. In order to realize such an application potential of the SBES, in this laboratory-scale study we investigated the effect of several controllable and uncontrollable operational factors on the in-situ bioremediation performance of a tank model of a brackish aquaculture pond, into which a SBES was integrated, in comparison with a natural degradation control model. The performance was evaluated in terms of electricity generation by the SBES, Chemical oxygen demand (COD) removal and nitrogen removal of both the tank water and the tank sediment. Real-life conditions of the operational parameters were also experimented to understand the most close-to-practice responses of the system to their changes. Predictable effects of controllable parameters including external resistance and electrode spacing, similar to those reported previously for the BESs, were shown by the results but exceptions were observed. Accordingly, while increasing the electrode spacing reduced the current densities but generally improved COD and nitrogen removal, increasing the external resistance could result in decreased COD removal but also increased nitrogen removal and decreased current densities. However, maximum electricity generation and COD removal efficiency difference of the SBES (versus the control) could be reached with an external resistance of 100 Ω, not with the lowest one of 10 Ω. The effects of uncontrollable parameters such as ambient temperature, salinity and pH of the pond (tank) water were rather unpredictable. Temperatures higher than 35℃ seemed to have more accelaration effect on natural degradation than on bioelectrochemical processes. Changing salinity seriously changed the electricity generation but did not clearly affect the bioremediation performance of the SBES, although at 2.5% salinity the SBES displayed a significantly more efficient removal of nitrogen in the water, compared to the control. Variation of pH to practically extreme levels (5.5 and 8.8) led to increased electricity generations but poorer performances of the SBES (vs. the control) in removing COD and nitrogen. Altogether, the results suggest some distinct responses of the SBES under brackish conditions and imply that COD removal and nitrogen removal in the system are not completely linked to bioelectrochemical processes but electrochemically enriched bacteria can still perform nonbioelectrochemical COD and nitrogen removals more efficiently than natural ones. The results confirm the application potential of the SBES in brackish aquaculture bioremediation and help propose efficient practices to warrant the success of such application in real-life scenarios.
Nano-porous Silicon Microcavity Sensors for Determination of Organic Fuel Mixtures
Van Hoi Pham,Huy Bui,Le Ha Hoang,Thuy Van Nguyen,The Anh Nguyen,Thanh Son Pham,Quang Minh Ngo 한국광학회 2013 Current Optics and Photonics Vol.17 No.5
We present the preparation and characteristics of liquid-phase sensors based on nano-porous silicon multilayer structures for determination of organic content in gasoline. The principle of the sensor is a determination of the cavity-resonant wavelength shift caused by refractive index change of the nano-porous silicon multilayer cavity due to the interaction with liquids. We use the transfer matrix method (TMM)for the design and prediction of characteristics of microcavity sensors based on nano-porous silicon multilayer structures. The preparation process of the nano-porous silicon microcavity is based on electrochemical etching of single-crystal silicon substrates, which can exactly control the porosity and thickness of the porous silicon layers. The basic characteristics of sensors obtained by experimental measurements of the different liquids with known refractive indices are in good agreement with simulation calculations. The reversibility of liquid-phase sensors is confirmed by fast complete evaporation of organic solvents using a low vacuum pump. The nano-porous silicon microcavity sensors can be used to determine different kinds of organic fuel mixtures such as bio-fuel (E5), A92 added ethanol and methanol of different concentrations up to 15%.
Micropropagation from root segments to improve seedling quality in Chinese foxglove crops
Thanh Loan Pham,Van Huy Nguyen,Thi Le Thu Hoang,Thi Tam Tien Ha,Trung Kien Tran,Xuan Duong Vu,Phi Bang Cao,Quang Trung Nguyen 한국식물생명공학회 2020 JOURNAL OF PLANT BIOTECHNOLOGY Vol.47 No.3
This is the first study to establish a complete protocol for micropropagation of Rehmannia glutinosa from root segments. The study involved investigating the effect of plant growth regulators on in vitro shoot regeneration and rooting and identifying substrates supporting survival and growth performance of ex vitro seedlings. A Murashige and Skoog (MS) medium containing 30 g/L sucrose for shoot induction and 0.2 mg/L indole-3-acetic acid (IAA), 1 mg/L 6-benzylaminopurine (BAP), and 1 g/L polyvinylpyrrolidone (PVP) for shoot multiplication resulted in the highest number of shoots per explant and shoot height. Applying a medium containing 0.5 mg/L IAA and 1 g/L PVP yielded optimal rooting of the shoots grown in vitro. Compost enriched with microbial inoculants and perlite enhanced seedling growth better than that with organic biofertilizer-free substrates (soil and sand). We recommend the continuous production of micropropagated R. glutinosa seedlings from root segments under the aforementioned conditions as a possible propagation technique for crops of this species.
( Hai The Pham ),( Hien Thi Tran ),( Linh Thuy Vu ),( Hien The Dang ),( Thuy Thu Thi Nguyen ),( Thu Ha Thi Dang ),( Mai Thanh Thi Nguyen ),( Huy Quang Nguyen ),( Byung Hong Kim ) 한국미생물·생명공학회 2019 Journal of microbiology and biotechnology Vol.29 No.7
In this study, we investigated the potential of using sediment bioelectrochemical systems (SBESs) for in situ treatment of the water and sediment in brackish aquaculture ponds polluted with uneaten feed. An SBES integrated into a laboratory-scale tank simulating a brackish aquaculture pond was established. This test tank and the control (not containing the SBES) were fed with shrimp feed in a scheme that mimics a situation where 50% of feed is uneaten. After the SBES was inoculated with microbial sources from actual shrimp pond sediments, electricity generation was well observed from the first experimental week, indicating successful enrichment of electrochemically active bacteria in the test tank sediment. The electricity generation became steady after 3 weeks of operation, with an average current density of 2.3 mA/㎡ anode surface and an average power density of 0.05 mW/㎡ anode surface. The SBES removed 20-30% more COD of the tank water, compared to the control. After 1 year, the SBES also reduced the amount of sediment in the tank by 40% and thus could remove approximately 40% more COD and approximately 52% more nitrogen from the sediment, compared to the control. Insignificant amounts of nitrite and nitrate were detected, suggesting complete removal of nitrogen by the system. PCR-DGGE-based analyses revealed the dominant presence of Methylophilus rhizosphaerae, Desulfatitalea tepidiphila and Thiothrix eikelboomii, which have not been found in bioelectrochemical systems before, in the bacterial community in the sediment of the SBES-containing tank. The results of this research demonstrate the potential application of SBESs in helping to reduce water pollution threats, fish and shrimp disease risks, and thus farmers’ losses.
( Minh Hai Pham ),( Quan Anh Tuan Le ),( Hoang Bac Nguyen ),( Quang Hung Vu ),( Thai Ngoc Huy Tran ),( Hang Dang Khoa N Guyen ),( Thi Ngoc Sang Duong ),( Van Toan Tran ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1
Aims: Laparoscopic pancreaticoduodenectomy (LPD) is considered as a safe and effective procedure in well - selected patients and appropriate surgical technique. Our aim is to evaluate suitability of using protocol for LPD in treatment of periampullary cancer at a single team. Methods: case series Results: Indication for LPD included 37 cases with resectable tumors which were classified basing on NCCN. All witness evaluation risk of complications with PREPARE score, ASA and evaluation risk of postoperative pancreatic fistula (POPF) with FRS classification. There were 2 open conversions because of vein resections, accounting for 5.4%. Standard lymphadenectomy was performed in all of 37 cases. In term of PREPARE score, major complications (Clavien - Dindo >= III) were 17.8%, 0% and 0% (5/28, 0/5 and 0/2 cases) in low risk, intermediate risk and high risk group, respectively. All of cases had ASA I or II. POPF happened 11.1% (1/9), 4.1% (1/24) and 50% (1/2) in low risk, intermediate risk and high risk group, respectively. Frozen section was needed for R0 margin. Retrieved lymph nodes was 8 - 18 with 12 lymph nodes in average. Conclusions: Indication for LPD with resectable tumors is acceptable. ASA I or II is a safe measure to select patient for LPD. FRS classification shows appropriation to evaluate risk of POPF.
Van Tu Vu,Quang Huy Tran,Thanh Loc Pham,Phuong Nam Dao 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.3
This article addresses a trajectory tracking control approach for an uncertain surface vessel using the new cascade structure of adaptive reinforcement learning (ARL) algorithm and kinematic controller, feed-forward term. Since a surface vessel is decoupled by kinematic sub-system and dynamic sub-system, the cascade control system is an ideal method for obtaining the tracking problem. In the proposed control structure, the dynamic control loop is designed to be the optimized method of the corresponding dynamic sub-system and the kinematic control loop is implemented by a nonlinear controller combining with feed-forward term. The online actor-critic architecture is considered in ARL algorithm to overcome the challenge of solving the Hamilton-Jacobi-Bellman (HJB) equation. Additionally, the proposed controller is able to handle the difficulty of the non-autonomous optimal control problem by designing the ARL technique for the corresponding system with a small number of state variables. Based on theoretical analysis, the ARL based control design has been made to guarantee the uniformly ultimately bounded (UUB) stability of the closed system. Finally, the simulation results are illustrated to verify the effectiveness of the proposed control scheme.
Duc Khanh Le,Quang Khai Le,Thi Thuy Hang Tran,Duc Viet Nguyen,Thi Hang Dao,Thi Thuy Nguyen,Xuan Lam Truong,Quang Cuong Nguyen,Huy Phong Pham,Thi Thu Thuy Phan,Gajendra Babu Baktavachalam 한국응용곤충학회 2019 Journal of Asia-Pacific Entomology Vol.22 No.2
Susceptibility of Asian corn borer (ACB), Ostrinia furnacalis (Guenée) to Bacillus thuringiensis (Bt) Cry1Ab protein was studied between 2015 and 2016 with 11 ACB populations, collected from various geographical regions in Vietnam. A concentration range of Cry1Ab from 0.20 to 26.10 ng/cm 2 of diet was evaluated against F 1 ACB neonates using diet surface-overlay bioassays. Mortality data was recorded daily until seven days after infestation. Growth inhibition was recorded at the end of seven days. The median lethal concentration (LC 50 ) varied ≈3-fold among the different populations, ranging from 0.58 to 1.83 ng/cm 2 of diet with an overall mean of 0.86 ng/cm 2 of diet. Even the lowest concentration of 0.20 ng/cm 2 caused 73.53% growth inhibition. > 90% growth inhibition was achieved at 0.82 ng/cm 2 or higher concentrations. The results reflect natural variation in Bt susceptibility among ACB populations rather than variation caused by prior exposure to selection pressures. LC 99 value (17.26 ng/cm 2 ) was generated by pooling mortality data across different populations. The upper fiducial limit of LC 99 (24.38 ng/cm 2 ) could be a potential diagnostic dose for future resistance monitoring programs. The findings from this study suggest that ACB populations in Vietnam are highly susceptible to Cry1Ab protein. This is the first report of Cry1Ab susceptibility of different ACB populations in Vietnam and will serve as a baseline for future resistance monitoring work.