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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.
Nguyen Van Hung,Bui Thi Minh Nguyet,Nguyen Huu Nghi,Nguyen Minh Luon,Nguyen Ngoc Bich,Le Van Thanh Son,Nguyen Trung Kien,Dao Ngoc Nhiem,Nguyen Thanh Tuoi,Dinh Quang Khieu 대한환경공학회 2024 Environmental Engineering Research Vol.29 No.4
In the present work, ZnO/g-C₃N₄/biochar was prepared, and it was used for visible-light driven photocatalytic degradation of some colorants (methylene blue, rhodamine B, methyl orange) and some antibiotics (doxycycline, ciprofloxacin, amoxicilline). Biochar was prepared by pyrolysing Phragmites australis biomass. The ZnO/g-C₃N₄/biochar composite was synthesized with the alkaline hydrolysis method. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transition electron microscopy, energy dispersive X-ray/elemental mapping, ultraviolet-visible-diffuse reflectance spectroscopy, photoluminescence spectroscopy, nitrogen adsorption/desorption isotherms and X-ray photoelectron spectroscopy. The results show that ZnO nanoparticles with a large surface area are highly dispersed on the g-C₃N₄ particle surface and biochar. The composite exhibits superior photocatalytic degradation ability toward doxycycline, a broad-spectrum antibiotic of the tetracycline compared with individual components (ZnO or g-C₃N₄) and satisfies stability after six treatment cycles. The kinetics and degradation mechanisms of doxycyline were also addressed. In addition, the present catalyst also exhibits the photocatalytic degradation of methylene blue, rhodamine B, methyl orange, ciprofloxacin and amoxicillin in visible-light regions.
Factors Affecting Night-Time Economic Development: Research in Hanoi, Vietnam
Ngoc Son NGUYEN(Ngoc Son NGUYEN ),Vu Hiep HOANG(Vu Hiep HOANG ),Quoc Dung NGO(Quoc Dung NGO ),Van Hoa HOANG(Van Hoa HOANG ) 한국유통과학회 2023 Asian Journal of Business Environment (AJBE) Vol.13 No.2
Purpose: The purpose of the study is to explore the factors which influence the night-time economic development in Hanoi, Vietnam. The results can help policymakers achieve a scientific basis to plan the development of night-time economy in Hanoi. Research design, data and methodology: The research model is developed from literature review with 7 independent variables, including natural conditions and resources, infrastructure, safety, environmental issues, promotion and international integration, development of sharing economy, and institution and policy. This model is then adjusted by exploratory factors analysis to have 4 new variables: Institution and environment, Infrastructure and safety, Promotion and sharing, and Nature and resources. The model is regressed based on the data of 463 observations of night-time economy in Hanoi, Vietnam. Results: Consistent with the current literature addressing night-time economy, the results show positive impacts of all of the independent variables studied. Conclusions: It is recommended for the local authorities to strengthen advertising and promoting investment for NTE development in Hanoi city and also enhance the role of state management in NTE activities by raising awareness of the state management apparatus towards a more open-minded multi-dimensional view of the NTE, developing the NTE to overcome the barrier of thinking “if it cannot be managed, it is forbidden” in state management agencies, and defining responsibilities and authority among state management agencies in the management of NTE activities and strengthening decentralization and decentralization of powers for localities in the management and development of NTE.
Tung Nguyen-Thach,Nguyen Canh-Hung,Nguyen Van-Duong,Nguyen Thi-Hong-Thuy,Nguyen Van-Lam,Tran Cao-Son,Pham Thi-Minh-Hue 한국약제학회 2020 Journal of Pharmaceutical Investigation Vol.50 No.4
Purpose The study aimed firstly to determine the release behavior of the model drug (berberine chloride) from the dry coated tablets. The second objective of this study was to evaluate the exact location of the dry coated tablets in in vivo. Methods The colon targeting tablets were developed by dry powder coating technique on pan coater. The drug release behavior was determined in the three continuous mediums: pH 1.2; 7.4 and 6.8 plus pectinase. The location of the dry coated tablets in the gastrointestinal tract of human volunteers was observed through the X-ray imaging of the dry coated tablets containing the optimized radiocontrast agents. Results The release kinetics of berberine chloride from the dry coated tablets was mainly controlled by erosion and enzyme sensitive mechanism. The optimum dry coated tablets having the coating powders of pectin 102:HPMC K4 M (2:1) with the coating level of 200%, and the tablet core with BaSO4 10% and iobitridol 30% as radiocontrast agents were observed in the caecum and ascending colon of human volunteers after 5–6 h of oral administration. Conclusion The successful development of these dosage forms is believed to have a high potential in precisely monitoring the release of highly potent drugs such as anti-inflammatory drugs in bowel diseases.
Truong Giang Nguyen,Thanh Khiem Nguyen,Ham Hoi Nguyen,Hong Son Trinh,Tuan Hiep Luong,Minh Trong Nguyen,Van Duy Le,Hai Dang Do,Kieu Hung Nguyen,Van Minh Do,Quang Huy Tran,Cuong Thinh Nguyen 한국간담췌외과학회 2024 Annals of hepato-biliary-pancreatic surgery Vol.28 No.1
Backgrounds/Aims: Parenchymal-sparing anatomical hepatectomy (Ps–AH) based on portal ramification of the right anterior section (RAS) is a new technique to avoid unnecessarily transecting too much liver parenchyma, especially in cases of major anatomical hepatectomy. Methods: We prospectively assessed 26 patients with primary hepatic malignancies having undergone major Ps–AH based on portal ramification of the RAS from August 2018 to August 2022 (48 months). The perioperative indications, clinical data, intra-operative index, pathological postoperative specimens, postoperative complications, and follow-up results were retrospectively evaluated. Results: Among the 26 patients analyzed, there was just one case that had intrahepatic cholangiocarcinoma The preoperative level of α– Fetoprotein was 25.2 ng/mL. All cases (100%) had Child–Pugh A liver function preoperatively. The ventral/dorsal RAS was preserved in 19 and 7 patients, respectively. The mean surgical margin was 6.2 mm. The mean surgical time was 228.5 minutes, while the mean blood loss was 255 mL. In pathology, 5 cases (19.2%) had microvascular invasion, and in the group of HCC patients, 92% of all cases had moderate or poor tumor differentiation. Six cases (23.1%) of postoperative complications were graded over III according to the Clavien–Dindo system, including in three patients resistant ascites or intra-abdominal abscess that required intervention. Conclusions: Parenchymal-sparing anatomical hepatectomy based on portal ramification of the RAS to achieve R0-resection was safe and effective, with favorable short-term outcomes. This technique can be used widely in clinical practice.
Nguyen Hoang Linh,Nguyen Minh Son,Tran The Quang,Nguyen Van Hoi,Vuong Thanh,Do Van Truong Materials Research Society of Korea 2023 한국재료학회지 Vol.33 No.5
This study uses first-principles calculations to investigate the mechanical properties and effect of strain on the electronic properties of the 2D material 1H-PbX<sub>2</sub> (X: S, Se). Firstly, the stability of the 1H Pb-dichalcogenide structures was evaluated using Born's criteria. The obtained results show that the 1H-PbS<sub>2</sub> material possesses the greatest ideal strength of 3.48 N/m, with 3.68 N/m for 1H-PbSe<sub>2</sub> in biaxial strain. In addition, 1H-PbS<sub>2</sub> and 1H-PbSe<sub>2</sub> are direct semiconductors at equilibrium with band gaps of 2.30 eV and 1.90 eV, respectively. The band gap was investigated and remained almost unchanged under the strain ε<sub>xx</sub> but altered significantly at strains ε<sub>yy</sub> and ε<sub>bia</sub>. At the fracture strain in the biaxial direction (19 %), the band gap of 1H-PbS<sub>2</sub> decreases about 60 %, and that of 1H-PbSe<sub>2</sub> decreases about 50 %. 1H-PbS<sub>2</sub> and 1H-PbSe<sub>2</sub> can convert from direct to indirect semiconductor under the strain ε<sub>yy</sub>. Our findings reveal that the two structures have significant potential for application in nanoelectronic devices.
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%.
Van Duy, Nguyen,Jung, Sungwook,Nga, Nguyen Thanh,Son, Dang Ngoc,Cho, Jaehyun,Lee, Sunhwa,Lee, Wonbaek,Yi, Junsin Elsevier 2010 Materials science and engineering B. Advanced Func Vol.175 No.2
<P><B>Abstract</B></P><P>Beside silicon nitride, silicon rich SiO<SUB><I>x</I></SUB> is a good charge storage material for the charge trap type of nonvolatile memory due to the high density of the charge traps. In this study, the charge storage ability of various amorphous SiO<SUB><I>x</I></SUB> materials has been investigated. By controlling the ratio of N<SUB>2</SUB>O/SiH<SUB>4</SUB> gases from a 1:6 to a 2:1 input gas flow rate, the deposited SiO<SUB><I>x</I></SUB> bandgap changed from 2.3 to 3.9eV. The charge storage properties of the SiO<SUB><I>x</I></SUB> system were studied on metal–insulator–semiconductor structures with an insulator stack of SiO<SUB>2</SUB>/SiO<SUB><I>x</I></SUB>/SiO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> on an n-type silicon wafer. In this structure, the SiO<SUB>2</SUB> was used for the blocking layer and the SiO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> was used for the tunneling layer. By analyzing the FTIR and the photoluminescence spectra, it is shown that the richest silicon material incorporates numerous non-bridging oxygen hole-center (NBOHC) defect sources and a rich silicon phase in the base material. These defects, as well as the amorphous silicon clusters that exist in the SiO<SUB><I>x</I></SUB> layer, enhanced the charge storage capacity of the device compared to the oxygen rich SiO<SUB><I>x</I></SUB> cases. The retention property was optimized by surveying the tunneling thickness of the 2.3, 2.6, 2.9, and 3.2nm SiO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> layers.</P>
Van Duy, Nguyen,Jung, Sungwook,Kim, Kwangryul,Son, Dang Ngoc,Nga, Nguyen Thanh,Cho, Jaehyun,Choi, Byoungdeog,Yi, Junsin Institute of Physics [etc.] 2010 Journal of physics. D, applied physics Vol.43 No.7
<P>Silicon-rich SiO<SUB><I>x</I></SUB> material is a good charge storage candidate for memory applications that promise a large memory window and low operation voltage. Nonvolatile memory (NVM) devices fabricated on excimer laser-annealed polysilicon using SiO<SUB>2</SUB>/SiO<SUB><I>x</I></SUB>/SiO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> (OOxOn) structure are investigated with SiO<SUB>2</SUB> blocking thicknesses changing from 15 to 20 to 30 nm. The Si-rich SiO<SUB><I>x</I></SUB> material exposed numerous non-bridging oxygen hole-centre defect sources and a rich silicon phase in the base material. These defects, as well as amorphous silicon clusters existing in the SiO<SUB><I>x</I></SUB> layer, enhance the charge storage capacity of the device. Retention properties were ensured by 3.2 nm SiO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> tunnelling layer growth via N<SUB>2</SUB>O plasma-assisted oxynitridation. NVM characteristics showed a retention exceeding 85% of the threshold voltage shift after 10<SUP>4</SUP> s and greater than 70% after 10 years. Depending on the blocking thickness of 15, 20 or 30 nm, operating voltages varied from ±9 to ±13 V at a programming/erasing duration of only 1 ms. These excellent operating properties of the OOxOn structure make it a potential competitor among the new generation of memory structures on glass.</P>