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( Tran Huyen Dang ),이현주 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Although chloride-ligated Pt compounds like (bpym)PtCl<sub>2</sub>, K<sub>2</sub>PtCl<sub>4</sub> and (DMSO)<sub>2</sub>PtCl<sub>2</sub> has been reported to be highly active catalysts for the methane oxidation to methyl bisulfate (MBS) in the oleum media, their applications is hampered by the catalyst deactivation to PtCl<sub>2</sub>. In this study, we investigated Pt-black catalyzed methane oxidation, which has no ligand. A MBS yield of 82.1% with a selectivity of 96.5% was obtained at a catalyst loading of 1.6 mM at 180 ℃, which proved the highest catalytic activity of Pt-black for this reaction. The reaction was thought to proceed by the dissolved Pt species, and no deactivation was observed during four consecutive experiments. However, at a concentration of over 30 mM, MBS yield fell down due to the decomposition of MBS to CO<sub>2</sub> on the surface of heterogeneous Pt(0). Vacuum distillation experiments showed the potential for isolating MBS from the oxidation product mixture as a major component.
Oxidation of methane to methyl trifluoroacetate by Dioxygen
( Tran Huyen Dang ),이현주 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
For the optimal utilization of abundant natural gas, direct oxidative methane functionalization using an environmental benign and inexpensive oxidant, dioxygen O<sub>2</sub>, is very important. Co(OAc)<sub>2</sub>-NHPI catalyst system was known to activate C-H group in alkanes such as cyclohexane, ethane, and isobutane in the presence of O<sub>2</sub>. In this reaction system, NHPI (N-hydroxyphthalimde) acts as a radical mediator to activate stable C-H bond. In this study, we conducted methane oxidation using Co(II)-NHPI-O<sub>2</sub> system in the presence of CF<sub>3</sub>CO<sub>2</sub>H as a solvent to synthesized trifluoroacetate CF<sub>3</sub>CO<sub>2</sub>Me, a methanol precursor. In the presence of NHPI, the catalytic activity increased significantly and the catalytic activity highly depended on the reaction time as well as the catalyst concentration. Degradation of NHPI was also monitored using IR and <sup>1</sup>H-NMR.
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.
Tran Ha Thi Thanh,Dang Anh Kieu,Ly Duc Viet,Vu Hao Thi,Hoang Tuan Van,Nguyen Chinh Thi,Chu Nhu Thi,Nguyen Vinh The,Nguyen Huyen Thi,Truong Anh Duc,Pham Ngoc Thi,Dang Hoang Vu 아세아·태평양축산학회 2020 Animal Bioscience Vol.33 No.10
Objective: The rapid and reliable detection of the African swine fever virus (ASFV) plays an important role in emergency control and preventive measures of ASF. Some methods have been recommended by FAO/OIE to detect ASFV in clinical samples, including real-time polymerase chain reaction (PCR). However, mismatches in primer and probe binding regions may cause a false-negative result. Here, a slight modification in probe sequence has been conducted to improve the qualification of real-time PCR based on World Organization for Animal Health (OIE) protocol for accurate detection of ASFV in field samples in Vietnam. Methods: Seven positive confirmed samples (four samples have no mismatch, and three samples contained one mutation in probe binding sites) were used to establish novel real-time PCR with slightly modified probe (Y = C or T) in comparison with original probe recommended by OIE. Results: Both real-time PCRs using the OIE-recommended probe and novel modified probe can detect ASFV in clinical samples without mismatch in probe binding site. A high correlation of cycle quantification (Cq) values was observed in which Cq values obtained from both probes arranged from 22 to 25, suggesting that modified probe sequence does not impede the qualification of real-time PCR to detect ASFV in clinical samples. However, the samples with one mutation in probe binding sites were ASFV negative with OIE recommended probe but positive with our modified probe (Cq value ranked between 33.12-35.78). Conclusion: We demonstrated for the first time that a mismatch in probe binding regions caused a false negative result by OIE recommended real-time PCR, and a slightly modified probe is required to enhance the sensitivity and obtain an ASF accurate diagnosis in field samples in Vietnam.
Thanh, Tran Dang,Huyen Yen, Pham Duc,Hau, Kieu Xuan,Bau, Le Viet,Yu, S. C. IEEE 2018 IEEE transactions on magnetics Vol.54 No.11
<P>In this paper, we have investigated the critical properties in the vicinity of the ferromagnetic (FM)–paramagnetic (PM) phase transition in a polycrystalline sample of La<SUB>0.75</SUB>Ca<SUB>0.2</SUB>Ag<SUB>0.05</SUB>MnO<SUB>3</SUB>, which was prepared by a solid-state reaction method. Temperature dependence of the inverse of the susceptibility <TEX>$\chi ^{-1}$</TEX> ( <TEX>$T$</TEX>) proves an existence of the Griffiths phase well above Curie temperature ( <TEX>$T_{C} = 230$</TEX> K). Detailed analyses of the isothermal magnetization <TEX>$M$</TEX>( <TEX>$H$</TEX>, <TEX>$T$</TEX>) data reveal the sample exhibiting a second-order magnetic phase transition, and its temperature dependences of the saturation magnetization and the initial susceptibility obey the asymptotic relations. Using the modified Arrott plots method, the Kouvel–Fisher method, and the critical isotherm analysis, the critical parameters ( <TEX>$\beta$</TEX>, <TEX>$\gamma$</TEX>, <TEX>$\delta$</TEX>, and <TEX>$T_{C}$</TEX>) of La<SUB>0.75</SUB>Ca<SUB>0.2</SUB>Ag<SUB>0.05</SUB>MnO<SUB>3</SUB> compound have been estimated. Using these critical exponent values, almost <TEX>$M$</TEX>( <TEX>$H$</TEX>, <TEX>$T$</TEX>) data measured at different temperatures around FM–PM phase transition are collapsed onto two universal curves of <TEX>$M/\vert \varepsilon \vert ^{\boldsymbol {\beta }}$</TEX> versus <TEX>$H/\vert \varepsilon \vert ^{\boldsymbol {\beta }+\boldsymbol {\gamma }}$</TEX> corresponding to the regular functions for <TEX>$T > T_{C}$</TEX> and <TEX>$T < T_{C}$</TEX>, respectively.</P>
Thanh, Tran Dang,Linh, Dinh Chi,Yen, Pham Duc Huyen,Bau, Le Viet,Ky, Vu Hong,Wang, Zhihao,Piao, Hong-Guang,An, Nguyen Manh,Yu, Seong-Cho Elsevier 2018 PHYSICA B-CONDENSED MATTER - Vol.532 No.-
<P><B>Abstract</B></P> <P>In this work, we present a detailed study on the magnetic properties and the magnetocaloric effect (MCE) of La<SUB>1−x</SUB>K<SUB>x</SUB>MnO<SUB>3</SUB> compounds with <I>x</I>=0.05–0.2. Our results pointed out that the Curie temperature (<I>T</I> <SUB>C</SUB>) could be controlled easily from 213 to 306K by increasing K-doping concentration (<I>x</I>) from 0.05 to 0.2. In the paramagnetic region, the inverse of the susceptibility can be analyzed by using the Curie-Weiss law, <I>χ</I>(<I>T</I>)=<I>C</I>/(<I>T</I>−<I>θ</I>). The results have proved an existence of ferromagnetic clusters at temperatures above <I>T</I> <SUB>C</SUB>. Based on Banerjee's criteria, we also pointed out that the samples are the second-order phase transition materials. Their magnetic entropy change was calculated by using the Maxwell relation and a phenomenological model. Interestingly, the samples with <I>x</I>=0.1–0.2 exhibit a large MCE in a range of 282–306K, which are suitable for room-temperature magnetic refrigeration applications. The composites obtained from single phase samples (<I>x</I>=0.1–0.2) exhibit the high relative cooling power values in a wide temperature range. From the viewpoint of the refrigerant capacity, the composites formed out of La<SUB>1−x</SUB>K<SUB>x</SUB>MnO<SUB>3</SUB> will become more useful for magnetic refrigeration applications around room-temperature.</P>