The reduced reversible phase transition field of lead–free Bi–based ceramic composites by adding nonergodic relaxor

Dinh, Thi Hinh,Tran, Vu Diem Ngoc,Nguyen, Thi Thao,Hoang, Quyen Thi Ngoc,Han, Hyoung–,Su,Lee, Jae–,Shin Elsevier 2017 CERAMICS INTERNATIONAL Vol.43 No.18

<P><B>Abstract</B></P> <P>This study investigated the microstructure, dielectric, ferroelectric, and strain properties of lead‒free 0.995Bi<SUB>1/2</SUB>(Na<SUB>0.82</SUB>K<SUB>0.18</SUB>)<SUB>1/2</SUB>TiO<SUB>3</SUB>–0.005BaZrO<SUB>3</SUB>/0.98Bi<SUB>1/2</SUB>(Na<SUB>0.78</SUB>K<SUB>0.22</SUB>)<SUB>1/2</SUB>TiO<SUB>3</SUB>–0.02LaFeO<SUB>3</SUB> (BNKT18BZ/BNKT22LF) ceramic composites. We found that the required electric field for trigging the phase transition from ergodic relaxor (ER) to ferroelectric of BNKT18BZ/BNKT22LF ceramic composites can be effectively decreased by adding BNKT18BZ as nonergodic relaxor (NER) with changes of three different stabilized regions and the highest <I>S</I> <SUB>usable</SUB> peak points as a function of the applied electric field. The highest <I>d</I> <SUB>33</SUB> <SUP>*</SUP> value of 690p.m./V was obtained at 4kV/mm for 0.3wt BNKT18BZ fraction ceramic composites. This value was higher than 575 p.m./V of BNKT22LF ceramics under an applied electric field of 5kV/mm.</P>

Cloning, High-Level Expression, Purification, and Properties of a Novel Endo-β-1,4-Mannanase from Bacillus subtilis G1 in Pichia pastoris

( Vu Thi Thu Hang ),( Dinh Thi Quyen ),( Thi Tuyet Dao ),( Sy Le Thanh Nguyen ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.3

A novel gene coding for an endo-β-1,4-mannanase (manA) from Bacillus subtilis strain G1 was cloned and overexpressed in P. pastoris GS115, and the enzyme was purified and characterized. The manA gene consisted of an open reading frame of 1,092 nucleotides, encoding a 364-aa protein, with a predicted molecular mass of 41 kDa. The β-mannanase showed an identity of 90.2-92.9% (≤95%) with the corresponding amino acid sequences from B. subtilis strains deposited in GenBank. The purified β- mannanase was a monomeric protein on SDS-PAGE with a specific activity of 2,718 U/mg and identified by MALDITOF mass spectrometry. The recombinant β-mannanase had an optimum temperature of 45oC and optimum pH of 6.5. The enzyme was stable at temperatures up to 50oC (for 8 h) and in the pH range of 5-9. EDTA and most tested metal ions showed a slightly to an obviously inhibitory effect on enzyme activity, whereas metal ions (Hg2+, Pb2+, and Co2+) substantially inhibited the recombinant β-mannanase. The chemical additives including detergents (Triton X- 100, Tween 20, and SDS) and organic solvents (methanol, ethanol, n-butanol, and acetone) decreased the enzyme activity, and especially no enzyme activity was observed by addition of SDS at the concentrations of 0.25-1.0% (w/v) or n-butanol at the concentrations of 20-30% (v/v). These results suggested that the β-mannanase expressed in P. pastoris could potentially be used as an additive in the feed for monogastric animals.

Preliminary study of doxycycline adsorption from aqueous solution on alkaline modified biochar derived from banana peel

Van-Truc Nguyen,Thanh-Binh Nguyen,Thi-Dieu-Hien Vo,Nguyen Duy Dat,Thi-Kim Quyen Vo,Xuan Cuong Nguyen,Viet-Cuong Dinh,Thi-Ngoc-Chau Le,Thi-Giang-Huong Duong,Manh-Ha Bui,Xuan-Thanh Bui 대한환경공학회 2023 Environmental Engineering Research Vol.29 No.3

This study explores the adsorption of doxycycline (DOX) from aqueous solutions onto biochar derived from banana peel, which was prepared using a potassium hydroxide activation method (KOH-BPB). The biochar properties were characterized based on morphology, surface area (SBET of 710.241 ㎡ g<SUP>−1</SUP>), functional groups, and surface charge (pHPZC = 7.7). Parameters, including initial pH, DOX concentration, and ionic strength, that influenced the DOX adsorption capacity of KOH-BPB were examined. Adsorption equilibrium of DOX on KOH-BPB was assessed through four isothermal models: the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. The obtained data were most compatible with the Langmuir model (R² = 0.9879). KOH-BPB has a maximum DOX absorption capacity of 121.95 mg g<SUP>-1</SUP> which exceeds that of many comparable absorbents. The maximum DOX removal was 96.7% at pH 6, a DOX concentration of 20 mg L<SUP>-1</SUP>, and a KOH-BPB dose of 1.0g L<SUP>-1</SUP>. These findings reveal that biochar from banana peel effectively removes antibiotic residues from water. This study provides a potential, low-cost, and environmentally friendly adsorbent.

Applying Stochastic Fractal Search Algorithm (SFSA) in Ranking the Determinants of Undergraduates Employability: Evidence from Vietnam

DINH, Hien Thi Thu,CHU, Ngoc Nguyen Mong,TRAN, Van Hong,NGUYEN, Du Van,NGUYEN, Quyen Le Hoang Thuy To Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.12

Employability has recently become the first target of the national higher education. Its model has been updated to catch the new trend of Industry 4.0. This paper aims at analyzing and ranking the determinants of undergraduate employability, focusing on business and economics majors in Ho Chi Minh City, Vietnam. In-depth interviews with content analysis have been primarily conducted to reach an agreement on a key group of factors: human capital, social capital, and identity. The Stochastic Fractal Search Algorithm (SFSA) is then applied to rank the sub-factors. Human capital is composed of three major elements: attitude, skill, and knowledge. Social capital is approached at both structural and cognitive aspects with three typical types: bonding, bridging, and linking. The analysis has confirmed the change of priority in employability determinants. Human capital is still a driver but the priority of attitude has been confirmed in the contemporary context. Then, social capital with the important order of linking, bridging, and bonding is emphasized. Skill, knowledge, and identity share the least weight in the model. It is noted that identity is newly proposed in the model but a certain role has been found. The findings are crucial for education strategies to enhance university graduate employability.

Cloning, Expression, Purification, and Properties of an Endoglucanase Gene (Glycosyl Hydrolase Family 12) from Aspergillus niger VTCC-F021 in Pichia pastoris

( Thi Hoa Pham ),( Dinh Thi Quyen ),( Ngoc Minh Nghiem ),( Thu Doan Vu ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.10

A gene coding for an endoglucanase (EglA), of the glycosyl hydrolase family 12 and derived from Aspergillus niger VTCC-F021, was cloned and sequenced. The cDNA sequence, 717 bp, and its putative endoglucanase, a 238 aa protein with a predicted molecular mass of 26 kDa and a pI of 4.35, exhibited 98.3-98.7% and 98.3-98.6% identities, respectively, with cDNA sequences and their corresponding endoglucanases from Aspergillus niger strains from the GenBank. The cDNA was overexpressed in Pichia pastoris GS115 under the control of an AOX1 promoter with a level of 1.59 U/ml culture supernatant, after 72 h of growth in a YP medium induced with 1% (v/v) of methanol. The molecular mass of the purified EglA, determined by SDS-PAGE, was 33 kDa, with a specific activity of 100.16 and 19.91 U/mg toward 1% (w/v) of β-glucan and CMC, respectively. Optimal enzymatic activity was noted at a temperature of 55℃ and a pH of 5. The recombinant EglA (rEglA) was stable over a temperature range of 30- 37℃ and at pH range of 3.5-4.5. Metal ions, detergents, and solvents tested indicated a slightly inhibitory effect on rEglA activity. Kinetic constants (K(m), V(max), k(cat), and k(cat)/ K(m)) determined for rEglA with β-glucan as a substrate were 4.04 mg/ml, 102.04 U/mg, 2,040.82 min-1, and 505.05, whereas they were 10.17 mg/ml, 28.99 U/mg, 571.71 min-1, and 57.01 with CMC as a substrate, respectively. The results thus indicate that the rEglA obtained in this study is highly specific toward β-glucan. The biochemical properties of rEglA make it highly valuable for downstream biotechnological applications, including potential use as a feed enzyme.

Effects of Glycerol and Shikimic Acid on Rapamycin Production in Streptomyces rapamycinicus

( Huyen Thi Huong La ),( Thao Kim Nu Nguyen ),( Hang Thuy Dinh ),( Quyen Minh Huynh Nguyen ),( Minh Hong Nguyen ) 한국미생물 · 생명공학회 2020 한국미생물·생명공학회지 Vol.48 No.3

Rapamycin, derived from Streptomyces rapamycinicus, is an important bioactive compound having a therapeutic value in managing Parkinson’s disease, rheumatoid arthritis, cancer, and AIDS. Because of its pharmaceutical activity, studies over the past decade have focused on the biosynthesis of rapamycin to enhance its yield. In this study, the effect of rapG on rapamycin production was investigated. The rapG expression vector was constructed by utilizing the integration vector pSET152 under the control of the erythromycin resistance gene (ermE*), a strong constitutive promoter. The rapamycin yield of wild type (WT) and WT/ rapG overexpression mutant strains, under fermentation conditions, was analyzed by high-performance liquid chromatography (HPLC). Our results revealed that overexpression of rapG increased rapamycin production by approximately 4.9-fold (211.4 mg/l) in MD1 containing 15 g/l of glycerol, compared to that of the WT strain. It was also found that Illicium verum powder (10 g/l), containing shikimic acid, enhanced rapamycin production in both WT and WT/rapG strains. Moreover, the amount of rapamycin produced by the WT/rapG strain was statistically higher than that produced by the WT strain. In conclusion, the addition 15 g/l glycerol and 15 g/l I. verum powder produced the optimal conditions for rapamycin production by WT and WT/rapG strains.

An Empirical Study of Perceived Organizational Support and Affective Commitment in the Logistics Industry

HOA, Nguyen Dinh,NGAN, Pham Thi Hong,QUANG, Nguyen Minh,THANH, Vu Ba,QUYEN, Huynh Vo Thuc Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.8

The study examines the impact of organizational rewards, procedure justice, and perceived supervisor support on perceived organizational support, and examine the impact of perceived organizational support on affective commitment to the organization in the logistic enterprises as well. Quantitative research is applied to measure relationships by regression analysis with SPSS. The research data was collected by convenient method from 180 employees who work in different departments in the logistics industry. The study results in the model 1 found that organizational rewards, procedure justice, and perceived supervisor support have a positive relationship to the perceived organizational support. The study results in the model 2 also found that perceived organizational support has strong impact on the affective commitment to the organization. The study results contribute to both management theory and management practice. For the management theory aspect, the authors suggest that perceived organizational support should be considered the key antecedent of affective commitment about which researchers should pay more attention as a concept. Based on the research results, the authors also recommend for the management practice that managers should pay attention to the implementation of rewards, procedure justice, and supervisor support to increase the perceived organizational support and affective commitment in the logistic enterprises.

Highly effective adsorption of organic dyes from aqueous solutions on longan seed-derived activated carbon

Nguyen Van Hung,Bui Thi Minh Nguyet,Nguyen Huu Nghi,Nguyen Mau Thanh,Nguyen Duc Vu Quyen,Vo Thang Nguyen,Dao Ngoc Nhiem,Dinh Quang Khieu 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.3

In this study, longan seeds - an agricultural by-product was used to fabricate activated carbon (LSAC) through two-step pyrolysis with pre-carbonization at low temperature in the first step and then activation by H3PO4. LSAC with large surface area and porous structure exhibits an excellent capacity of absorption towards both cationic dyes (methylene blue (MB), rhodamine-B (RhB)) and anionic dyes (methyl orange (MO), congo red (CR)). Experimental data can be described well by the pseudo-second kinetic model. The maximum adsorption capacity based on Langmuir isotherm model was found as 502.84; 397.77; 464.66 and 350.64 mg.g−1 for MB, RhB, MO and CR, respectively. The adsorption of MB, RhB and CR on LSAC is spontaneous and endothermic, while that for MO is spontaneous but exothermic. Furthermore, the adsorption mechanism of dyes on LSAC was also studied showing that it can occur by electrostatic interaction, hydrogen bonding, the filling of pores involving the interaction between dye ions with specific functional groups such as –OH, –COOH, –NH2 and –PO43− on the LSAC surface. These results suggest that LSAC material may be envisaged as a promising adsorbent for treatment of wastewater in textile industries.

Antimalarial effect of synthetic endoperoxide on synchronized Plasmodium chabaudi infected mice

Nagwa S. M. Aly,Hiroaki Matsumori,Thi Quyen Dinh,Akira Sato,Shin-Ichi Miyoshi,장경수,유학선,Fumie Kobayashi,김혜숙 대한기생충학ㆍ열대의학회 2023 The Korean Journal of Parasitology Vol.61 No.1

The discovery of new antimalarial drugs can be developed using asynchronized Plasmodium berghei malaria parasites in vivo in mice. Studies on a particular stage are also required to assess the effectiveness and mode of action of drugs. In this report, we used endoperoxide 6-(1,2,6,7-tetraoxaspiro [7.11] nonadec-4-yl) hexan-1-ol (N-251) as a model antimalarial compound on P. chabaudi parasites. We examined the antimalarial effect of N-251 against ring-stage- and trophozoite-stage-rich P. chabaudi parasites and asynchronized P. berghei parasites using the 4-day suppressive test. The ED50 values were 27, 22, and 22 mg/kg, respectively, and the antimalarial activity of N-251 was verified in both rodent malaria parasites. To assess the stage-specific effect of N-251 in vivo, we evaluated the change of parasitemia and distribution of parasite stages using ring-stage- and trophozoite-stage-rich P. chabaudi parasites with one-day drug administration for one life cycle. We discovered that the parasitemias decreased after 13 and 9 hours post-treatment in the ring-stage- and trophozoite-stage-rich groups, respectively. Additionally, in the ring-stage-rich N-251 treated group, the ring-stage parasites hindered trophozoite parasite development. For the trophozoite-stage-rich N-251 treated group, the distribution of the trophozoite stage was maintained without a change in parasitemia until 9 hours. Because of these findings, it can be concluded that N-251 suppressed the trophozoite stage but not the ring stage. We report for the first time that N-251 specifically suppresses the trophozoite stage using P. chabaudi in mice. The results show that P. chabaudi is a reliable model for the characterization of stage-specific antimalarial effects.

Evaluating the activity of N-89 as an oral antimalarial drug

Nagwa S. M. Aly,Hiroaki Matsumori,Thi Quyen Dinh,Akira Sato,Shin-Ichi Miyoshi,장경수,유학선,Takaaki Kubota,Yuji Kurosaki,Duc Tuan Cao,Gehan A. Rashed,김혜숙 대한기생충학ㆍ열대의학회 2023 The Korean Journal of Parasitology Vol.61 No.3

Despite the recent progress in public health measures, malaria remains a troublesome disease that needs to be eradicated. It is essential to develop new antimalarial medications that are reliable and secure. This report evaluated the pharmacokinetics and antimalarial activity of 1,2,6,7-tetraoxaspiro[7.11]nonadecane (N-89) using the rodent malaria parasite Plasmodium berghei in vivo. After a single oral dose (75 mg /kg) of N-89, its pharmacokinetic parameters were measured, and t1/2 was 0.97 h, Tmax was 0.75 h, and bioavailability was 7.01%. A plasma concentration of 8.1 ng/ml of N-89 was maintained for 8 h but could not be detected at 10 h. The dose inhibiting 50% of parasite growth (ED50) and ED90 values of oral N-89 obtained following a 4-day suppressive test were 20 and 40 mg/kg, respectively. Based on the plasma concentration of N-89, we evaluated the antimalarial activity and cure effects of oral N-89 at a dose of 75 mg/kg 3 times daily for 3 consecutive days in mice harboring more than 0.5% parasitemia. In all the N-89- treated groups, the parasites were eliminated on day 5 post-treatment, and all mice recovered without a parasite recurrence for 30 days. Additionally, administering oral N-89 at a low dose of 50 mg/kg was sufficient to cure mice from day 6 without parasite recurrence. This work was the first to investigate the pharmacokinetic char-acteristics and antimalarial activity of N-89 as an oral drug. In the future, the following steps should be focused on developing N-89 for malaria treatments; its administration schedule and metabolic pathways should be investigated.