New Technique for the Synthesis of Carbon Nanotubes

Phan Ngoc Minh,Phan Hong Khoi,Nguyen Van Chuc,Phan Ngoc Hong,Ngo Thi Thanh Tam 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

Carbon nanotubes (CNTs) are considered as a promising material for various applications. However, due to their limited availability and high purchasing costs, at the present time, only a few of these applications have been realized. The realization of CNT-based devices and CNT-based materials depends on success in material synthesis and on the possibility of controlling the nanotube's chirality, diameter and purity. This paper describes new simple techniques for (i) synthesis of vertically-aligned carbon nanotubes (VA-CNTs), (ii) mass and low-cost production of multiwall carbon nanotubes (MWCNTs) and (iii) growth of individual CNTs on tungsten tips.

Fabrication of Carbon Nanotubes on Tungsten Tips

Phan Ngoc Hong,Phan Ngoc Minh,Vo Viet Cuong,Bui Hung Thang,Phan Hong Khoi 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

In this paper, we present the results of fabrication of carbon nanotubes on sharp W tips for advanced electron emiters and scanning probe microscopy. A calculation to optimize the elec- trochemical etching conditions for geting ultra-sharp W tips was caried out. W tips of 50 nm in diameter were formed by electrochemical etching of a 0.3-mm W wire in a 5 % KOH solution. Fe catalytic nanoparticles were deposited at the apex of the W tip by electroplating in a FeCl3 solution. By using hot-lament chemical vapor deposition in C2H2/H2 gases, we have sucesfuly grown individual CNTs of 4 m in length and 20 nm in diameter on a W tip.

Mental Health Among Healthcare Workers During the COVID-19 Pandemic in Vietnam

Nhan Phuc Thanh Nguyen,Ha Phan Ai Nguyen,Cao Khoa Dang,Minh Tri Phan,Huynh Ho Ngoc Quynh,Van Tuan Le,Chinh Van Dang,Tinh Huu Ho,Van Trong Phan,Van Trong Phan,Thang Phan,Dang Thi Anh Thu 대한예방의학회 2024 예방의학회지 Vol.57 No.1

Objectives: The objective of this study was to characterize mental health issues among Vietnamese healthcare workers (HCWs) and to identify related factors.Methods: A cross-sectional study was conducted with 990 HCWs in 2021. Their mental health status was measured using the Depression, Anxiety, and Stress Scale.Results: In total, 49.9%, 52.3%, and 29.8% of respondents were found to have depression, anxiety, and stress, respectively. The multivariable linear regression model revealed that factors associated with increased anxiety scores included depression scores (β, 0.45; 95% confidence interval [CI], 0.39 to 0.51) and stress scores (β, 0.46; 95% CI, 0.41 to 0.52). Factors associated with increased depression scores included being frontline HCWs (β, 0.57; 95% CI, 0.10 to 1.10), stress scores (β, 0.50; 95% CI, 0.45 to 0.56), and anxiety scores (β, 0.41; 95% CI, 0.36 to 0.47), while working experience was associated with reduced depression scores (β, -0.08; 95% CI, -0.16 to -0.01). Factors associated with increased stress scores included working experience (β, 0.08; 95% CI, 0.00 to 0.16), personal protective equipment interference with daily activities (β, 0.55; 95% CI, 0.07 to 1.00), depression scores (β, 0.54; 95% CI, 0.48 to 0.59), and anxiety scores (β, 0.45; 95% CI, 0.39 to 0.50), while age was associated with reduced stress scores (β, -0.12; 95% CI, -0.20 to -0.05).Conclusions: Specific interventions are necessary to enhance and promote the mental health of HCWs so they can successfully cope with the circumstances of the pandemic.

Synthesis of Carbon Nanotubes on Steel Foils

Nguyen Van Chuc,Nguyen Duc Dung,Phan Ngoc Hong,Le Dinh Quang,Phan Hong Khoi,Phan Ngoc Minh 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Carbon nanotubes (CNTs) were synthesized by using a thermal chemical vapor deposition (CVD) at 800 ℃ in a mixture of C₂H₂, H₂ and N₂ gases with steel foils as both catalysts and substrates. More than 2 grams of CNTs were grown on approximately 7 grams of steel foil with a 0.5 cm² surface area after 30 minutes of growth. The effects of CVD parameters, such as the growth temperature and the deposition time, on the size and the morphology of the CNTs were studied using scanning electron microscopy (SEM). We found that the optimized temperature and growth time for having high quality CNTs were 800 ℃ and 30 minutes, respectively. The purity of the CNTs was evaluated by using thermogravimetric analysis (TGA) and the result showed that the carbon content was approximately 93 wt.%. The graphite crystallinity of the CNTs was analyzed by using Raman spectroscopy. The steel foil was found to maintain its catalytic behavior after several growths. The technique holds great promise for use in mass production (approximately 120 grams CNTs per day) with signicantly reduced cost. Carbon nanotubes (CNTs) were synthesized by using a thermal chemical vapor deposition (CVD) at 800 ℃ in a mixture of C₂H₂, H₂ and N₂ gases with steel foils as both catalysts and substrates. More than 2 grams of CNTs were grown on approximately 7 grams of steel foil with a 0.5 cm² surface area after 30 minutes of growth. The effects of CVD parameters, such as the growth temperature and the deposition time, on the size and the morphology of the CNTs were studied using scanning electron microscopy (SEM). We found that the optimized temperature and growth time for having high quality CNTs were 800 ℃ and 30 minutes, respectively. The purity of the CNTs was evaluated by using thermogravimetric analysis (TGA) and the result showed that the carbon content was approximately 93 wt.%. The graphite crystallinity of the CNTs was analyzed by using Raman spectroscopy. The steel foil was found to maintain its catalytic behavior after several growths. The technique holds great promise for use in mass production (approximately 120 grams CNTs per day) with signicantly reduced cost.

Anti-inflammatory tirucallane saponins from Paramignya scandens.

Phan, Nguyen Huu Toan,Thuan, Nguyen Thi Dieu,Ngoc, Ninh Thi,Thao, Nguyen Phuong,Kim, Sohyun,Koh, Young Sang,Thanh, Nguyen Van,Cuong, Nguyen Xuan,Nam, Nguyen Hoai,Kiem, Phan Van,Kim, Young Ho,Minh, Cha Pharmaceutical Society of Japan 2015 Chemical & pharmaceutical bulletin Vol.63 No.7

<P>Five new tirucallane saponins, paramignyosides A-E (1-5), were isolated from the water fraction of the Paramignya scandens stem and leaves. Their structures were elucidated on the basis of spectroscopic evidence including high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) and one dimensional (1D)- and 2D-NMR. The effects of isolated compounds on pro-inflammatory cytokines were evaluated by measuring the production of interleukin (IL)-12 p40, IL-6, and tumor necrosis factor-α (TNF-α) in lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells (BMDCs). Paramignyoside C (3) exhibited selective and potent inhibitory effect (IC50=5.030.19??M) on the production of IL-12 p40 comparable to that of the positive control, SB203580 (IC50=5.000.16??M). Further studies are required to confirm efficacy in vivo and the mechanism of anti-inflammatory effects.</P>

Employee Retention and Talent Management: Empirical Evidence from Private Hospitals in Vietnam

PHAN, Minh Duc,NGUYEN, Thi Mai Thoa,DUONG, Ngoc Anh,NGUYEN, Thi Tuoi Korea Distribution Science Association 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.6

Amidst the Covid-19 pandemic, human resources play a vital role in the health industry because the staff all has to confront a lot of stresses in serving the country and the people to overcome the severe contagiousness and infection of the virus. It is also the case of Family General Hospital, Da Nang (Vietnam). Therefore, the Hospital identifies talented personnel as a core resource in its sustainable development strategy. Researching on how to retain talented staff to serve the sustainable and long-term development of a private hospital such as Family Hospital is extremely necessary, especially when there are fewer large and modern private health facilities for the healthcare system in Central Vietnam compared to the North and the South. With the analysis of survey data and in-depth interviews from both qualitative and quantitative perspectives (via SPSS 20.0), especially the ANOVA and EFA analyses, and linear multiple regression (Generation 1 methods), this study aims to clarify the aspects that affect the talent retention in the representative Family Hospital. The lessons learned have been a good reference for similar private healthcare models in the process of bringing health-related services to a new level in the competition.

Huge Tongue Base Neurilemmoma : Excision by Intraoral Coblation

김준선,phan huu ngoc minh,홍기환 대한이비인후과학회 부산,울산,경남 지부회 2016 임상이비인후과 Vol.27 No.2

Neurilemoma arising from the tongue base are very rare and only a few cases have been reported so far. The tumor is resistance to radiotherapy, and therefore, the treatment of choice is surgery. Diagnosis was confirmed by imaging studies and biopsy followed by surgical excision designed to preserve nerve function. We report a case of huge neurilemoma of the tongue base treated with intraoral coblation. Case reports and a review of the world literature concerning treatment methods and surgical approaches of neurilemoma of tongue base. A number of surgical approaches have been described for tongue base neurilemomas. We report a case of tongue base neurilemoma which was completely extirpated with a coblation through the intraoral approach. The postoperative course was uneventful and improved within 2 weeks like as tonsillectomy patient. The intraoral coblation assisted excision is a safe and useful surgical technique for the removal of tongue base neurilemoma.

Evaluation of Crack Resistance of Aramid Fiber Reinforced Asphalt Mixture

Tam Minh Phan,Son Ngoc Nguyen,Chang-Bae Seo,Dae-Wook Park 한국도로학회 2020 한국도로학회 학술대회 발표논문 초록집 Vol.2020 No.09

Phenothiazine Derivative as Organic Photocatalyst for Metal Free Atom Transfer Radical Polymerization

Hoan Minh Tran,Lan Ngoc Tan Phan,Thang Van Le,Thuy Thuy Truong,Tam Huu Nguyen,Khuong Tung Truong,Le-Thu T. Nguyen,Mai Thanh Phong,Ha Tran Nguyen 한국고분자학회 2019 폴리머 Vol.43 No.4

A novel organic photocatalyst, 4-(10H-phenothiazin-10-yl)-N,N-diphenylaniline (PDPA) has been successfully synthesized from triphenylamine and phenothiazine moiety via Buchwald-Hartwig C-N coupling. The chemical structure of catalyst was characterized via proton nuclear magnetic resonance (1H NMR) and the optical properties were investigated via UV-vis spectroscopy. The PDPA has been applied as an organic photocatalyst for metal free atom transfer radical polymerization (O-ATRP). The well-controlled molecular weights of polymethacrylates have been obtained with high yield of 95% and narrow polydispersity index (Đ).

Which Plosive Consonant Is More Useful for the Aerodynamic Analysis of Pathologic Voice?

홍용태,phan huu ngoc minh,홍기환 대한이비인후과학회 2020 Clinical and Experimental Otorhinolaryngology Vol.13 No.2

Objectives. Both acoustic and aerodynamic analyses are essential to evaluate the phonetic characteristics of voice pathology. The purpose of the study is to determine the magnitude of their correlation with the different types of bilabial plosive consonants. Methods. A controlled prospective study of 35 patients diagnosed with unilateral vocal fold paralysis was performed. The sustained vowel /a/ and bilabial voiceless consonants were used. Three common acoustic parameters were measured from a sustained vowel /a/ and aerodynamic parameters from a set of syllables /pi/, /phi/, and /p’i/. We determined the correlation coefficients between acoustic and aerodynamic measurements for the bilabial plosive consonants /pi/, /phi/, and /p’i/. Results. The mean values of acoustic parameters were higher than the thresholds of pathology. The mean values of aerodynamic parameters varied according to the types of consonants. The correlation between acoustic and aerodynamic parameters was significantly larger with the consonant /phi/ compared with the consonants /p’/ and /p/. The magnitudes of correlation were higher with the consonant /phi/ compared with the consonants /p’/ and /p/. Conclusion. The plosive consonant /phi/ may represent a more valuable investigative consonant than the consonants /p/ or/p’/ for aerodynamic analysis of voice pathology, especially in patients with unilateral vocal fold paralysis.