Two new species of Camellia (Theaceae) from Vietnam

Lieu Thi Nguyen,Ninh Tran,Uematsu CHIYOMI,Katayama HIRONORI,Dung Van Luong,Son Thanh Hoang,Ky Danh NGUYEN,Hung Viet NGUYEN,Toan Canh THAI 한국식물분류학회 2018 식물 분류학회지 Vol.48 No.2

Two new species of Camellia (Theaceae) are described from Vietnam: Camellia vuquangensis Luong, Tran & L. T. Nguyen and Camellia hatinhensis Luong, Tran & L. T. Nguyen. The new taxa were col- lected from Vu Quang National Park in the center of Vietnam. The new finds are morphologically dissimilar to all known Camellia species. Recent Camellia discoveries have increased the number of species recorded in Viet- nam from 50 to 75, making Vietnam a center of diversity and a crucial area for more research into the diversity and distributions of Camellia.

Effect of salicylic acid and yeast extract on curcuminoids biosynthesis gene expression and curcumin accumulation in cells of Curcuma zedoaria

Nguyen Hoang Loc,Truong Thi Phuong Lan,Nguyen Duc Huy,Nguyen Ngoc Luong,Hoang Tan Quang,Trinh Huu Tan,Le Thi Anh Thu,Nguyen Xuan Huy 한국식물생명공학회 2019 JOURNAL OF PLANT BIOTECHNOLOGY Vol.46 No.3

The aim of this study is to evaluate the effect of yeast extract (YE) and salicylic acid (SA) on the expression of curcuminoid-biosynthesis genes (CzDCS and CURS1-3), and accumulation of curcumin in Curcuma zedoaria cell cultures. The results showed that, in cells treated with YE or SA, the expression levels of curcuminoid genes were 1.14- to 3.64-fold higher than the control (untreated cells), in which the YE exhibited a stronger effect in comparison with SA. Curcumin accumulation also tended to be similar to gene expression, curcumin contents in YE- or SA-treated cells were 1.61- to 2.53-fold higher than the control. The SA treatment at the fifth day of culture stimulated the curcumin accumulation and expression in all four genes compared to that at the beginning. While the YE treatments gave different results, the CzCURS1 and CzCURS3 genes were expressed strongly in cells that were treated at the beginning. However, the CzDCS and CzCURS2 genes showed the opposite expression pattern, they were activated strongly in the treatments at day five of the culture. However, the content of curcumin reached its maximum value on the fifth day of culture in all investigations.

Applications of Magnetite Nanoparticles for Water Treatment and for DNA and Cell Separation

Nguyen Hoang Hai,Nguyen Chau,Nguyen Hoang Luong,Nguyen Thi Van Anh,Phan Tuan Nghia 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.3

Magnetic nanoparticles with a diameter of 15 nm prepared by using the coprecipitation method have been applied to enforce the sedimentation of the solid waste, to adsorb the arsenic ions in water, to increase the DNA concentration by using a magnetic eld for the electrochemical DNA sensor and to separate the helper CD4+ T cells to determine the number of the cells in blood. A combination of magnetic nanoparticles and alum makes the solid waste in water under a magnetic field aggregate a dozen times faster than under the gravity alone. A concentration of 0.1 mg/l of arsenic in water was reduced to a value lower than the permissible concentration of 0.01 mg/l after few minutes of stirring. The particles functionalized with 3-aminopropyl triethoxysilane were used to enrich the DNA of the Herpes virus, which extended the sensitivity of an electrochemical sensor down to a concentration lower than nM/l. The particles coated with fluorescent-labeled antiCD4 antibody were used to count the helper CD4+ T cells. The fluorescence signals of the particle/cell system were two times stronger than those of the uorescence antiCD4 cell system. This can be used for the treatment of an HIV-infected patient with a simple fluorescent microscope. Magnetic nanoparticles with a diameter of 15 nm prepared by using the coprecipitation method have been applied to enforce the sedimentation of the solid waste, to adsorb the arsenic ions in water, to increase the DNA concentration by using a magnetic eld for the electrochemical DNA sensor and to separate the helper CD4+ T cells to determine the number of the cells in blood. A combination of magnetic nanoparticles and alum makes the solid waste in water under a magnetic field aggregate a dozen times faster than under the gravity alone. A concentration of 0.1 mg/l of arsenic in water was reduced to a value lower than the permissible concentration of 0.01 mg/l after few minutes of stirring. The particles functionalized with 3-aminopropyl triethoxysilane were used to enrich the DNA of the Herpes virus, which extended the sensitivity of an electrochemical sensor down to a concentration lower than nM/l. The particles coated with fluorescent-labeled antiCD4 antibody were used to count the helper CD4+ T cells. The fluorescence signals of the particle/cell system were two times stronger than those of the uorescence antiCD4 cell system. This can be used for the treatment of an HIV-infected patient with a simple fluorescent microscope.

Large Magnetocaloric Effect above 300 K and Magnetoresistance in (La0.5Pr0.5)1-xPbxMnO3 Perovskites

Nguyen Chau,Duong Thi Hanh,Bui Cong Tinh,Nguyen Hoang Luong,Nguyen Duc Tho,Nguyen Hoang Hai 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Perovskite compounds (La0.5Pr0.5)₁- xPbxMnO₃ (x = 0.1 - 0.5) with orthorhombic structure were prepared by using a solid-state reaction technique. In the studied samples, the spin-glass-like state occurs at low temperatures and the Curie temperature, Tc, increases from 170 K (x = 0.1) to 336 K (x = 0.5) because of a strong double exchange. The magnetic entropy change, │△Sm│, reached its largest value of 2.06 J/kg·K at △H = 13.5 kOe for the sample with x = 0.4 (Tc = 323 K). Due to the large │△Sm│ and high Tc, these materials are suggested for use as active magnetic refrigerants for magnetic refrigeration technology at temperatures above room temperature. While the conductivity of the samples with x = 0.1 and 0.2 exhibits only a semiconducting behavior over the whole measured temperature range, there is insulator-metallic phase transition on the R(T) curves of the samples with x = 0.3 - 0.5. The magnetoresistance of the samples was measured and large values for MR were found. Perovskite compounds (La0.5Pr0.5)₁- xPbxMnO₃ (x = 0.1 - 0.5) with orthorhombic structure were prepared by using a solid-state reaction technique. In the studied samples, the spin-glass-like state occurs at low temperatures and the Curie temperature, Tc, increases from 170 K (x = 0.1) to 336 K (x = 0.5) because of a strong double exchange. The magnetic entropy change, │△Sm│, reached its largest value of 2.06 J/kg·K at △H = 13.5 kOe for the sample with x = 0.4 (Tc = 323 K). Due to the large │△Sm│ and high Tc, these materials are suggested for use as active magnetic refrigerants for magnetic refrigeration technology at temperatures above room temperature. While the conductivity of the samples with x = 0.1 and 0.2 exhibits only a semiconducting behavior over the whole measured temperature range, there is insulator-metallic phase transition on the R(T) curves of the samples with x = 0.3 - 0.5. The magnetoresistance of the samples was measured and large values for MR were found.

Effects of Media on the Callogenensis and Cell Mass Production in Cell Cultures of Panax vietnamensis

Hoang Van Luong,Nguyen Van Long,Vu Binh Duong,Nguyen Linh Toan,Nguyen Van Minh,Le Bach Quang,Nam Hyuck Kim,Sang Yo Byun 한국생물공학회 2009 KSBB Journal Vol.24 No.2

This study was initiated to investigate the impacts of media types and other components on the callogenensis and cell mass production of Panax vietnamensis in the first step of the cell biomass procedure. Four media were checked: Murashige-Skoog (MS), White, Gamborg and Nitch-All. All the four media were shown potential media for Panax vietnamensis callogenensis and cell mass production, in which the MS medium showed the best results: the successful callogenensis ratio and cell mass formation were 30% and 62,93 ± 3,63 mg (DW) respectively, the Nitch medium showed the lowest results: the successful callogenensis ratio and cell mass formation were 15% and 27,10 ± 2,24 mg (DW) respectively. The results showed that the MS medium is the most suitable medium for Panax vietnamensis callogenensis and cell mass production.

Effects of Media on the Callogenensis and Cell Mass Production in Cell Cultures of Panax vietnamensis

Luong, Hoang Van,Long, Nguyen Van,Duong, Vu Binh,Toan, Nguyen Linh,Minh, Nguyen Van,Quang, Le Bach,Kim, Nam-Hyuck,Byun, Sang-Yo The Korean Society for Biotechnology and Bioengine 2009 KSBB Journal Vol.7 No.4

This study was initiated to investigate the impacts of media types and other components on the callogenensis and cell mass production of Panax vietnamensis in the first step of the cell biomass procedure. Four media were checked: Murashige-Skoog (MS), White, Gamborg and Nitch-AII. All the four media were shown potential media for Panax vietnamensis callogenensis and cell mass production, in which the MS medium showed the best results: the successful callogenensis ratio and cell mass formation were 30% and 62,93 ${\pm}$ 3,63 mg (DW) respectively, the Nitch medium showed the lowest results: the successful callogenensis ratio and cell mass formation were 15% and 27,10 ${\pm}$ 2,24 mg (DW) respectively. The results showed that the MS medium is the most suitable medium for Panax vietnamensis callogenensis and cell mass production.

Effects of Foreign Direct Investment and Human Capital on Labour Productivity: Evidence from Vietnam

Nguyen Hoang LE,Luong Vinh Quoc DUY,Bui Hoang NGOC 한국유통과학회 2019 The Journal of Asian Finance, Economics and Busine Vol.6 No.3

The paper aims to investigate whether foreign direct investment (FDI) has positive effect on the labour productivity in Vietnam. Labour productivity is the elemental determinant of a country’s development level in long-term. In recent years, although increasing consistently, labour productivity of Vietnam remains low in comparison to other South East Asian countries. To identify the direction of effect and the level of effect of FDI and human capital on the labour productivity of Vietnam, Autoregressive Distributed Lag (ARDL) model was used to examine the effect of FDI and human capital on labour productivity in Vietnam from 1986 to 2014. The results of bounds test confirm the existence of cointegration among the variables. Further, the Toda and Yamamoto Granger causality test affirms that there is unidirectional causality running from foreign direct investment and human capital index to labour productivity. The empirical results provide strong statistical evidence that foreign direct investment and human capital has a positive impact on labour productivity in Vietnam in long-term. These findings imply that workers are expected to further improve their knowledge, skills and that policy-maker should establish concrete plans to increase human capital. Results from this study provide suggestion necessary for Vietnam to achieve sustainable development.

Magnetic Properties of Bulk Nd50Co10Fe30Al10-xVx Alloys

Hoang Duc Anh,Cao Xuan Huu,Nguyen Chau,Nguyen Hoang Luong 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

This paper presents the results of study on the structure and the properties of the bulk Nd50Co₁0Fe₃0Al₁0xVx (x = 0, 2, 4, 6, 8, 10) alloys prepared by arc-melting and suction cast- ing with water cooling. The cast surfaces of the samples are partly crystalline and the amorphous volume fraction increases with distance into cast samples. With increasing V content, the crys- tallization volume fraction increases and for x = 10, the alloy is fully crystallized. In general, the melting temperature increases, but Ms and Hc decrease with V content. The Curie temperature increases clearly from 430 K (x = 0) to 512 K (x = 10). Thermomagnetic measurements of all samples done in low elds indicate the existence of the Hopkinson effect, which shows a coherent rotation magnetization and a strong reduction of the magnetic anisotropy in partly crystallized sam- ples. The eld-cooled (FC) and the zero field-cooled (ZFC) curves measured in low elds reveal an obvious separation from each other at low temperatures, pointing to the existence of a cluster-glass state. The cluster-glass fraction decreases with increasing V content in the samples. This paper presents the results of study on the structure and the properties of the bulk Nd50Co₁0Fe₃0Al₁0xVx (x = 0, 2, 4, 6, 8, 10) alloys prepared by arc-melting and suction cast- ing with water cooling. The cast surfaces of the samples are partly crystalline and the amorphous volume fraction increases with distance into cast samples. With increasing V content, the crys- tallization volume fraction increases and for x = 10, the alloy is fully crystallized. In general, the melting temperature increases, but Ms and Hc decrease with V content. The Curie temperature increases clearly from 430 K (x = 0) to 512 K (x = 10). Thermomagnetic measurements of all samples done in low elds indicate the existence of the Hopkinson effect, which shows a coherent rotation magnetization and a strong reduction of the magnetic anisotropy in partly crystallized sam- ples. The eld-cooled (FC) and the zero field-cooled (ZFC) curves measured in low elds reveal an obvious separation from each other at low temperatures, pointing to the existence of a cluster-glass state. The cluster-glass fraction decreases with increasing V content in the samples.

Inverse MR and Dual-AMR Phenomena in Co/CoO/Ag/Co Sandwiches

Nguyen Anh Tuan,Luong Van Su,Hoang Quoc Khanh,Nguyen Anh Tue,Nguyen Thi Luyen 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.7

Band-form Co/CoO/Ag/Co sandwiches were prepared using radio-frequency magnetron sputtering. The sandwiches had rather thick Co (tCO = 63 nm) and Ag (tAg = 2 ÷ 65 nm) layers and a super-thin paramagnetic cobalt monoxide (CoO) layer (< 1 nm) inserted in the Co/Ag interface. The sandwiches exhibited anomalous magnetoresistance (MR) behavior depending on the tAg value. Inverse magnetoresistance (IMR) effect was observed only at thin tAg values of 2 nm and 6 nm, whereas the dual-anisotropic MR (dual-AMR) occurred at thicker tAg values of 12 nm, 25 nm and 65 nm. A superposition of the dual-AMR and the weak IMR effects was obtained at the thickest Ag layer of 65 nm. The origin of these anomalous MR behaviors was discussed to show the prominent role of the CoO layer and large thickness of the Co and Ag layers.

Access to Anti-smoking Information among School Children and its Potential Impact on Preventing Smoking Initiation: Results from the Global Youth Tobacco Use Survey (GYTS) 2014 in Viet Nam

Hoang, Van Minh,Kim, Bao Giang,Phan, Thi Hai,Trinh, Dinh Hoang,Doan, Thu Huyen,Luong, Ngoc Khue,Nguyen, Thuy Linh,Nguyen, Tuan Lam,Pham, Thi Quynh Nga Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup1

Scientific evidence on all aspects of smoking amongst youth is very important for designing appropriate interventions to reduce smoking among this vulnerable population. This paper describes current access to anti-smoking information among school children aged 13 to 15 years in Vietnam in 2014 and examines its potential impact on preventing smoking initiation. The data used in this paper were obtained from the 2014 Global Youth Tobacco Survey (GYTS) in Vietnam. Students were asked questions about their level of awareness of anti-smoking information from various sources in the past 30 days and about lessons in school regarding the dangers of tobacco use during the last 12 months. Those who have never smoked were asked "whether or not they thought about avoiding cigarettes because of health warnings on cigarette packages" and answers were analyzed in combination with data on access to anti-smoking information from other sources. The prevalence of exposure to antismoking campaigns was high among school children in Viet Nam: 55.3% of current smokers reported thoughts of smoking cessation because of health warnings on cigarette packages; 60.5% of never smokers avoided initiating smoking because of the same health warnings. The potential impact of graphic health warnings to prevent school-aged children from smoking initiation would be stronger if there was concurrent access to anti-smoking programs on the dangers of tobacco use in schools. However, school education for tobacco prevention and control has not been as strong as expected. A more comprehensive school curriculum on tobacco prevention and control is recommended to reinforce antismoking messages among school children.