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Self-healing and mechanical properties of reinforced nickel-dispersed alumina hybrid nanocomposites
Hai Vu Pham,Makoto Nanko 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.5
Dense specimens of 5 vol%Ni/Al2O3 nanocomposites with fine grain size of Al2O3 and nano-Ni particles were fabricated by the pulsed current sintering technique. Vickers hardness, fracture toughness and bending strength of the nanocomposites were investigated at room temperature. Self-healing performance was evaluated at temperatures ranging 1100 ~ 1300 o C for 1 ~ 24 h. Bending tests were conducted on samples before and after heat-treatment in order to clarify the self-healing performance. As a result, fabricated sample achieved 995 MPa in bending strength and 6.1 MPam1/2 in fracture toughness. Introduced cracks on sample surface completely disappeared after heat-treatment at 1100 o C for 24 h. However, only 80% of cracks disappeared after heat-treatment at 1200 o C for 1 h in air. Bending strength of samples that were introduced cracks recovered up to the level as high as that of sintered samples after heat-treatment at 1200 o C for 6 h in air.
( 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.
Chemical Constituents of the Morinda tomentosa Leaves and their α-Glucosidase Inhibitory Activity
Vu, Huong Giang,Ninh, Khac Ban,Nguyen, Xuan Nhiem,Phan, Van Kiem,Chau Van, Minh,Hoang, Le Tuan Anh,Pham, Hai Yen,Bui, Huu Tai,Nguyen, Xuan Cuong,Nguyen, Hoai Nam,Kim, Seung Hyun,Kwon, Young-In,Kim, Yo Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.5
( 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.
New Dibenzocyclooctadiene Lignan from Kadsura induta and Their Cytotoxic Activities
Pham, Thi Hong Minh,Do, Tien Lam,Nguyen, Quyet Tien,Nguyen, Ngoc Tuan,Vu, Phuong Nhung,Nong, Van Hai,Phan, Van Kiem,Nguyen, Xuan Nhiem,Chau, Van Minh,Park, SeonJu,Kim, Seung Hyun Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.6
Management of Antibiotic-Resistant Helicobacter pylori Infection: Perspectives from Vietnam
Vu Van Khien,Duong Minh Thang,Tran Manh Hai,Nguyen Quang Duat,Pham Hong Khanh,Dang Thuy Ha,Tran Thanh Binh,Ho Dang Quy Dung,Tran Thi Huyen Trang,Yoshio Yamaoka 거트앤리버 소화기연관학회협의회 2019 Gut and Liver Vol.13 No.5
Antibiotic resistance is the most important factor leading to the failure of eradication regimens. This review focuses on the prevalence of Helicobacter pylori primary and secondary resistance to clarithromycin, metronidazole, amoxicillin, levofloxacin, tetracycline, and multidrug in Vietnam. We searched the PubMed, EMBASE, Vietnamese National Knowledge Infrastructure, and Vietnamese Biomedical databases from January 2000 to December 2016. The search terms included the following: H. pylori infection, antibiotic (including clarithromycin, metronidazole, amoxicillin, levofloxacin, tetracycline, and multidrug) resistance in Vietnam. The data were summarized in an extraction table and analyzed manually. Finally, Excel 2007 software was used to create charts. Ten studies (three studies in English and seven in Vietnamese) were included in this review. A total of 308, 412, 523, 408, 399, and 268 H. pylori strains were included in this review to evaluate the prevalence of H. pylori primary resistance to amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, and multidrug resistance, respectively. Overall, the primary resistance rates of amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, and multidrug resistance were 15.0%, 34.1%, 69.4%, 27.9%, 17.9% and 48.8%, respectively. Secondary resistance rates of amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, and multidrug resistance were 9.5%, 74.9%, 61.5%, 45.7%, 23.5% and 62.3%, respectively. In Vietnam, primary and secondary resistance to H. pylori is increasing over time and affects the effectiveness of H. pylori eradication.
( 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.
Triterpenoids from aerial parts of Glochidion eriocarpum.
Thu, Vu Kim,Kiem, Phan Van,Yen, Pham Hai,Nhiem, Nguyen Xuan,Tung, Nguyen Huu,Cuong, Nguyen Xuan,Minh, Chau Van,Huong, Hoang Thanh,Lau, Trinh Van,Thuan, Ngo Thi,Kim, Young Ho Natural Product Communications 2010 Natural product communications Vol.5 No.3
<P>From the aerial parts of Glochidion eriocarpum, a new triterpene, glochieriol (1), three new triterpenoid saponins, glochieriosides C - E (2 - 4), together with four known triterpenes (glochidonol, glochidiol, lupeol, and 3-epi-lupeol) were isolated by using combined chromatographic separations. The structures of the new compounds were elucidated on the basis of spectroscopic data, including FTICR-MS, 1D and 2D NMR.</P>
Improving Utilization of GPS Data for Urban Traffic Applications
Nguyen Duc Hai,Nguyen Tan Phuc,Doan Khue,Ta Ho Thai Hai,Pham Tran Vu,Huynh Nam,Le Thanh Van 한국인터넷방송통신학회 2015 International Journal of Internet, Broadcasting an Vol.7 No.1
The use of Intelligent Transportation System (ITS) is promising to bring better solutions for managing and handling the city traffic. This system combines many fields in advanced technology such as Global Positioning System (GPS), Geographic Information System (GIS) and so on. The basement of applications in ITS is the effective collections and data integration tools. The purpose of our research is to propose solutions which involve the use of GPS time series data collected from GPS devices in order to improve the quality of output traffic data. In this study, GPS data is collected from devices attached to vehicles travelling on routes in Ho Chi Minh City (HCMC). Then, GPS data is stored in database system to serve in many transportation applications. The proposed method combines the data usage level and data coverage to improve the quality of traffic data.
Dual-band isotropic metamaterial absorber based on near-field interaction in the Ku band
The Linh Pham,Hong Tiep Dinh,Dinh Hai Le,Xuan Khuyen Bui,Son Tung Bui,Hong Luu Dang,Anh Duc Phan,Dac Tuyen Le,Dinh-Lam Vu 한국물리학회 2020 Current Applied Physics Vol.20 No.2
We numerically and experimentally investigate single-band and dual-band isotropic metamaterial absorbers (IMAs) based on metallic disks. By optimizing the diameter of the metallic disks and the thickness of the dielectric substrate, the single-band IMA is observed at 16.2 GHz with absorptivity of 97%. When adding one diskpair to the structure, the dual-band IMA is obtained at 12.8 and 15.5 GHz due to the symmetry breaking. The physical mechanics is explained by near-field coupling effect and equivalent LC circuit model. The measurement results performed in the range 12–18 GHz show a good agreement with simulation and theoretical analysis. Our findings demonstrate a new approach to achieve dual-band and multi-band IMAs.