Effect of Saline Concentrations on Biological Nitrification in Batch Reactor

Young Joon Lee, Nguyen Viet Hoang, Nguyen Hong Khanh, Pham Tuan Linh, Gi Youn Kim 조선대학교 기초과학연구원 2011 조선자연과학논문집 Vol.4 No.2

Pham Tuan Linh2 and Gi Youn Kim This study was carried out on 4 batch reactors to determine the specific ammonium oxidizing rate (SAOR), specific nitrate forming rate (SNFR) and inhibitory degree of nitrifying activities with saline concentrations. Under salt free condition ammonia was consumed during the reaction period within 200 min. When the salt level increased to 10, 20 and 30 g NaClL-1 in reactor, ammonia depletion took 250, 300 and above 350 min, respectively. During concentration above 10 g NaClL-1, there was nitrite accumulation. Also, at 30 g NaClL-1 ammonia did not depleted and NO2 --N accumulated until the final reaction. Nitrate formation rates decreased with increasing salt concentration. SAOR and SNFR showed a decreasing trend as salinity concentrations were increased. The SAOR was reduced from 0.2 to 0.08 mg NH4+-N g-1VSS day-1 as the salt concentration increased from 0 to 30 g NaCLL-1. Similarly, the SNFR decreased from 0.26 kg NO3--N kg-1VSS day-1 at saline free to 0.1 kg NO3--N kg-1VSS day-1 at saline 30 g L-1. A severe inhibition of nitrifiers activity was observed at increased salt concentrations. The inhibition ratio of specific ammonium oxidation rates were 17, 47 and 60% on the reactor of 10, 20 and 30 g NaClL-1 added, respectively. The inhibition ratio of specific nitrate forming rates also were inhibited 30, 53 and 62% on the reactor of 10, 20 and 30 g NaClL-1 added, respectively. As the salinity concentrations increased from 0 to 30 mg NaClL-1, the average MLSS concentration increased from 1,245 to 1,735 mgL-1. The SS concentration of supernatant in reactor which settled about 30 minutes was not severely difference between concentration of salt free reactor and one of those high salt contained reactors

Understanding the COVID-19 Infodemic: Analyzing User-Generated Online Information During a COVID-19 Outbreak in Vietnam

Ha-Linh Quach,Thai Quang Pham,Ngoc-Anh Hoang,Dinh Cong Phung,Viet-Cuong Nguyen,Son Hong Le,Thanh Cong Le,Dang Hai Le,Anh Duc Dang,Duong Nhu Tran,Nghia Duy Ngu,Florian Vogt,Cong-Khanh Nguyen 대한의료정보학회 2022 Healthcare Informatics Research Vol.28 No.4

Objectives: Online misinformation has reached unprecedented levels during the coronavirus disease 2019 (COVID-19) pandemic. This study analyzed the magnitude and sentiment dynamics of misinformation and unverified information about public health interventions during a COVID-19 outbreak in Da Nang, Vietnam, between July and September 2020. Methods: We analyzed user-generated online information about five public health interventions during the Da Nang outbreak. We compared the volume, source, sentiment polarity, and engagements of online posts before, during, and after the outbreak using negative binomial and logistic regression, and assessed the content validity of the 500 most influential posts. Results: Most of the 54,528 online posts included were generated during the outbreak (n = 46,035; 84.42%) and by online newspapers (n = 32,034; 58.75%). Among the 500 most influential posts, 316 (63.20%) contained genuine information, 10 (2.00%) contained misinformation, 152 (30.40%) were non-factual opinions, and 22 (4.40%) contained unverifiable information. All misinformation posts were made during the outbreak, mostly on social media, and were predominantly negative. Higher levels of engagement were observed for information that was unverifiable (incidence relative risk [IRR] = 2.83; 95% confidence interval [CI], 1.33–0.62), posted during the outbreak (before: IRR = 0.15; 95% CI, 0.07–0.35; after: IRR = 0.46; 95% CI, 0.34-0.63), and with negative sentiment (IRR = 1.84; 95% CI, 1.23–2.75). Negatively toned posts were more likely to be misinformation (odds ratio [OR] = 9.59; 95% CI, 1.20–76.70) or unverified (OR = 5.03; 95% CI, 1.66–15.24). Conclusions: Misinformation and unverified information during the outbreak showed clustering, with social media being particularly affected. This indepth assessment demonstrates the value of analyzing online “infodemics” to inform public health responses.

Fast pyrolysis of pitch pine biomass in a bubbling fluidized-bed reactor for bio-oil production

Quoc Khanh Tran,Manh Linh Le,Hoang Vu Ly,우희철,김진수,김승수 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.98 No.-

The kinetic parameters for the pyrolysis of biomass of the pitch pine (Rigida pine P. Mill) were examinedby thermogravimetric analysis in the temperature range 25 C to 700 C, in which the maindecomposition was occurred from 250 C to 400 C. Pyrolysis of pitch pine has been investigated in abubblingfluidized bed reactor. In this system, silica sand and nitrogen were used as thefluidizing bedmaterial andfluidizing medium, respectively. The experimental was systemically performed on differenttemperature,fluidized velocity, and particle size of biomass. The optimum temperature condition atwhich the bio-oil yields reached the highest value (65.5%) was 500 C. In addition, the higher heatingvalues of bio-oils from pitch pine biomass were reached in the range 22 MJ/kg to 24 MJ/kg. Moreover, thisbio-oil had high content of useful chemicals including such as levoglucosan, furfural, and guaiacol. Thelarge amount of C5–C11 (gasoline fraction) produced make the pyrolyzed oil originating from pitch pinetrees a promising biofuel candidate.

X-ray absorption spectroscopies of Mg-Al-Ni hydrotalcite like compound for explaining the generation of surface acid sites

Hong Khanh Dieu Nguyen,Toan Dang Nguyen,Dung Ngoc Hoang,Duc Sy Dao,Thao Tien Nguyen,Limphirat Wanwisa,Lan Linh Hoang 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.2

Hydrotalcite-like compound containing metal cations such as Mg2+, Al3+ and Ni2+ was characterized using Ni K-edge EXAFS and in situ Ni K-edge XANES techniques for clarifying its bonding environment around Ni2+ sites and structure changes during calcination from room temperature to 550 oC, respectively. At the fixed molar ratio of Mg/Ni/Al of 2/1/1, the results obtained from EXAFS analysis showed a slight blue shift before and after the calcination at 550 oC and a reduction in white line peak; the best fits of the two samples revealed tiny change in coordination number about 7 for Ni-O path but considerable difference for Ni-Mg(Al) path from about 4.5 to 9.5, confirming a modification from brucite like to mixed oxide structure. On the other hand, bond distances of the Ni-O and Ni-Mg paths nearly fixed at about 2.06 Å to 3.0 Å reflected stability of the cationic bond order on each plane, but partial collapse and decomposition of the interlayer formed by water molecules and anion CO3 2− after the calcination. Linear combination fit extracted from the in situ Ni K-edge XANES also confirmed the changes along with the calcination such as slow and fast decreases of brucite fraction at 150 oC and 330 oC, respectively, in corresponding to the mixed oxide fraction increases. The achieved bonding structures were also applied to explain acid-base occurrence of the hydrotalcite-like material, especially the acid sites generated by different static charges along with the bonds. The explanation was illustrated by NH3-TPD method.

Vingroup: The Rising Dragon That Put Vietnam on the Global Map

Giap Vu Nam Duong,Hoang Khanh Linh,정경화,Nguyen Khanh Linh,Nguyen Phuong Hoa,Phan Hai Dang,Thai Thi Phuong Nga Academy of Asian Business (AAB) 2022 Academy of Asian Business Review Vol.8 No.1

Vingroup JSC (formerly Technocom) was founded in Ukraine in 1993 as an instant noodle factory. Since then, the Group has expanded into many other industries, placing tourism and hospitality as their first stepping-stone, then venturing into retail, real estate, education, and recently shifting towards a promising industrial and technology industry. Vingroup has now become the largest conglomerate in Vietnam in terms of market capitalization (VnExpress International, 2019). Having established a solid foundation in the Vietnamese market, Vingroup is eyeing the new promising yet challenging international market, with its competitive advantage in industrials and technology. Standing at a crucial juncture in its ascent, the conglomerate must implement a comprehensive and long-term strategy to reach its next milestone. In 2016, Vingroup primarily focused on four main business segments, encompassing property, hospitality - entertainment, consumer retail, and social infrastructure services. Over the course of two decades, Vinpearl and Vincom have grown into the market-leading hospitality and shopping malls brand in Vietnam. The brands’ establishment coincided with the flourishing economy of the country in the early 2000s, therefore, quickly achieved market dominance. Having such favorable conditions, the Group continued its expansion and investment in other backboned industries, which has reaped correspondingly fruitful results. The key success factors of Vingroup lies in an entrepreneurial mindset, speed, perfectionism and discipline, and last but not least, the national spirit. These traits have allowed the Group to unleash its potential capabilities and go beyond all boundaries. Both small-and-medium-sized companies and big firms can take Vingroup as a lesson for their strategy and corporate culture so that they can lead successful and sustainable growth in today’s competitive market.

Hydrodeoxygenation of Spent Coffee Bio-oil from Fast Pyrolysis using HZSM-5 and Dolomite Catalysts

Jeong Woo Park,Hoang Vu Ly,Le Manh Linh,Quoc Khanh Tran,Seung-Soo Kim,Jinsoo Kim 한국청정기술학회 2019 청정기술 Vol.25 No.2

Spent coffee is one of biomass sources to be converted into bio-oil. However, the bio-oil should be further upgraded to achieve a higher quality bio-oil because of its high oxygen content. Deoxygenation under hydrotreating using different catalysts (catalytic hydrodeoxygenation; HDO) is considered as one of the promising methods for upgrading bio-oil from pyrolysis by removal of O-containing groups. In this study, the HDO of spent coffee bio-oil, which was collected from fast pyrolysis of spent coffee (460 ℃, 2.0 × Umf), was carried out in an autoclave. The product yields were 72.16~96.76 wt% of bio-oil, 0~18.59 wt% of char, and 3.24~9.25 wt% of gas obtained in 30 min at temperatures between 250 ℃ and 350 ℃ and pressure in the range of 3 to 9 bar. The highest yield of bio-oil of 97.13% was achieved at 250 ℃ and 3 bar, with high selectivity of D-Allose. The carbon number distribution of the bio-oil was analyzed based on the concept of simulated distillation. The C12~C14 fraction increased from 22.98 wt% to 27.30 wt%, whereas the C19~C26 fraction decreased from 24,74 wt% to 17.18 wt% with increasing reaction time. Bio-oil yields were slightly decreased when the HZSM-5 catalyst and dolomite were used. The selectivity of CO was increased at the HZSM-5 catalyst and decreased at the dolomite.

Hydrodeoxygenation of Spent Coffee Bio-oil from Fast Pyrolysis using HZSM-5 and Dolomite Catalysts

Park, Jeong Woo,Ly, Hoang Vu,Linh, Le Manh,Tran, Quoc Khanh,Kim, Seung-Soo,Kim, Jinsoo The Korean Society of Clean Technology 2019 청정기술 Vol.25 No.2

Spent coffee is one of biomass sources to be converted into bio-oil. However, the bio-oil should be further upgraded to achieve a higher quality bio-oil because of its high oxygen content. Deoxygenation under hydrotreating using different catalysts (catalytic hydrodeoxygenation; HDO) is considered as one of the promising methods for upgrading bio-oil from pyrolysis by removal of O-containing groups. In this study, the HDO of spent coffee bio-oil, which was collected from fast pyrolysis of spent coffee ($460^{\circ}C$, $2.0{\times}U_{mf}$), was carried out in an autoclave. The product yields were 72.16 ~ 96.76 wt% of bio-oil, 0 ~ 18.59 wt% of char, and 3.24 ~ 9.25 wt% of gas obtained in 30 min at temperatures between $250^{\circ}C$ and $350^{\circ}C$ and pressure in the range of 3 to 9 bar. The highest yield of bio-oil of 97.13% was achieved at $250^{\circ}C$ and 3 bar, with high selectivity of D-Allose. The carbon number distribution of the bio-oil was analyzed based on the concept of simulated distillation. The $C_{12}{\sim}C_{14}$ fraction increased from 22.98 wt% to 27.30 wt%, whereas the $C_{19}{\sim}C_{26}$ fraction decreased from 24.74 wt% to 17.18 wt% with increasing reaction time. Bio-oil yields were slightly decreased when the HZSM-5 catalyst and dolomite were used. The selectivity of CO was increased at the HZSM-5 catalyst and decreased at the dolomite.

Trends in Second-Hand Tobacco Smoke Exposure Levels at Home among Viet Nam School Children Aged 13-15 and Associated Factors

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

Second-hand tobacco smoke (SHS) exposure at home, especially among children, is a serious issue in Viet Nam. During the past decade, much effort has been taken for tobacco control in the country, including various prgorammes aiming to reduce SHS exposure among adults and children. This article analysed trends and factors associated with SHS exposure at home among school children aged 13-15 in Viet Nam, using the Global Youth Tobacco Surveys conducted in 2007 and 2014. Descriptive and inferential statistical methods with logistic regression were applied. Overall, there was a significant reduction in the level of exposure, from 58.5% (95%CI: 57.6-59.3) in 2007 to 47.1% (95%CI: 45.4-48.8) in 2014. Of the associated factors, having one or both parents smoking was significantly associated with the highest odds of SHS exposure at home (OR=5.0; 95%CI: 4.2-6.1). Conversely, having a mother with a college or higher education level was found to be a protective factor (OR=0.5; 95%CI: 0.3-0.8).

Effect of Saline Concentrations on Biological Nitrification in Batch Reactor

Young Joon Lee,Nguyen Viet Hoang,Nguyen Hong Khanh,Pham Tuan Linh,Gi Youn Kim 조선대학교 기초과학연구원 2011 조선자연과학논문집 Vol.4 No.2

Proposal for the development of a national open access database in Vietnam and comparison with other Asian countries’ national literature databases

Loc My Thi Nguyen,Tien-Trung Nguyen,Thanh Thi Nghiem,Hien Thu Thi Le,Thao Phuong Thi Trinh,Thuan Van Pham,Thanh Chi Nguyen,Linh Khanh Hoang,Trung Tran 한국과학학술지편집인협의회 2020 Science Editing Vol.7 No.1

In the context of the need to ensure appropriate signalling of the publication of high-quality, international-calibre publications in Vietnam, as well as new policies to improve the quality and effectiveness of scientific research in Vietnam, it is practical to investigate the possibility of developing a national open access database (NOAD). This study aims to answer the question of whether it is necessary to establish a NOAD in Vietnam. We used document analysis to evaluate issues related to NOADs. The results of this study show the complexity, lack of consistency, and difficulty in obtaining practical statistics and assessing research and scientific records in Vietnam today. Furthermore, the findings of this study imply that it is necessary to establish a NOAD of scientific research in Vietnam. The information in this report can be used to develop a NOAD for Vietnam in particular, and for any country that lacks one in general.