Journal of Technical Education Science
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Published By Ho Chi Minh City University Of Technology And Education

2615-9740

Author(s):  
Ho Phuong

In this study, the Perovskite material CH3NH3PbI3 was prepared using two-step sequential solution deposition technique. The treatment condition for Perovskite film including dipping duration, reaction temperature and annealing temperature was studied. Crystal structure, grain size, and purity of the prepared material were examined using XRD and SEM methods. The results indicate that controlling treatment condition has a significant effect on the crystallinity and purity of Perovskite film. Under suitable condition, the obtained Perovskite material has a tetragonal structure and grain size ranges from 200 to 400 nm. The Perovskite film was then applied as a light-harvesting material in Perovskite solar cell. The device exhibits a power conversion efficiency of 5.18% with JSC of 13.6 mA cm-2, VOC of 0.83 V, and fill factor of 45.9%.


Author(s):  
Le Dang Khoa ◽  
Hoang Minh Hao

Curcumin, a phytochemical from turmeric, and its derivatives have been extensively investigated from both chemical and biological strategies. However, the main problem encountered while using curcumin in clinical trials is its poor solubility and rapid degradation, resulting in its low levels in tissues, thus decreasing the medicinal effect of curcumin. To overcome these problems several synthetic approaches have been carried out to prepare new derivatives possessing better properties. Curcumin as a β-diketone ligand can act as chelating ligands toward a variety of metals to form stable complexes. Some studies showed that a metal-curcumin complex displayed potential medicinal activities. In this work, a copper(II)-curcumin complex was synthesized in a two-step procedure: (i) curcumin was separated from commercial turmeric powder using chromatography techniques and (ii) the copper(II) chloride (1 eq.) and pure curcumin (2 eq.) were mixed together in ethanol. The mixture was stirred at 60 oC for 3 hours to afford a stoichiometric copper(II)-curcumin complex.  The curcumin ligand and its copper(II) complex were characterized by UV-Vis, IR, NMR spectroscopic methods, from which it was found that copper atoms are coordinated through keto-enol groups of two curcumin molecules. The ground state spectral features of the copper(II)-curcumin complex were consistent with that of the 1:2 copper(II)-curcumin complex. The antibacterial activities of curcumin ligand and its complex were evaluated against Staphylococcus aureus (ATCC 6538) using a well diffusion method on nutrient agar. The results showed that the inhibitory activity was not observed for free curcumin at any concentrations while the copper(II)-curcumin complex exhibited the inhibition zones (mm) of 7.8, 11.6 and 14.9 at various concentrations (mg/mL) of 1.0, 5.0 and 15.0, respectively.  


Author(s):  
Dang Dinh Khoi

Graphitic-carbon nitride quantum dots (g-CNQDs), a rising star in the carbon nitride family, has shown great potential in many fields including chemical and biomedical applications due to their good biocompatibility, stable fluorescence, high quantum yield, and nontoxicity. For this reason, enormous efforts have been devoted to optimizing synthetic methods and structures of g-CNQDs to discover the inner properties and structural features in the intriguing system. Also, a vast number of studies have been pursued to discuss the potential applications of g-CNQDs in chemical and biomedical areas. In this review, recent advances in synthesis and applications of g-CNQDs were summarized and the future challenges as well as opportunities of these g-CNQDs in the chemical and biomedical fields will be highlighted.


Author(s):  
Nguyen Thuy Kim Anh ◽  
Huynh Bao Ngan ◽  
Thai Hoang Nguyen Vu ◽  
Tran Thi Nhu Hao ◽  
Truong Thi Thu ◽  
...  

Bacterial cellulose (BC), a microbial polysaccharide, has chemically equivalent structure to plant cellulose with unbranched pellicle structure of only glucose monomers. Due to the unique nanostructure, BC has great potential in enzyme immobilization. In this study, the effects of different cultivation conditions including rotational speed, initial inoculum concentration and medium pH on the film-like cellulosic biomass formation of Gluconacetobacter xylinus JCM 9730 were examined. The resultant BC films were then studied for its feasibility in the immobilization of lipase, a widely used enzyme in biotechnological and industrial processes including food, pharmaceutical, chemical and paper industries. Results showed that increasing in rotational speed from 0 rpm to 200 rpm converted cellulose-producing cells to non-cellulose-producing ones, leading to a significant decline in BC film formation. The increase in initial inoculum size from 0.01 g/L to 0.1 g/L reduced sugar concentration and surface area of the medium, and therefore inhibiting the formation of film-like cellulosic biomass. In addition, the optimum pH range of Acetobacter species from 5.4 – 6.3 was found not optimal for BC film formation. The highest amount of film-like cellulosic biomass of 19.01 g/L was obtained under static condition (0 rpm) with initial cell concentration of 0.04 g/L and initial pH of 4.0. The BC film samples were then acetylated with acetic anhydride/iodine system to convert the hydroxyl groups to less hydrophilic acetyl groups and were used for lipase immobilization. Results showed that lipase immobilized on acetylated BC still maintained its lipid hydrolytic activity. It can be hence concluded that BC films produced by G. xylinus JCM 9730 were potential for lipase immobilization.


Author(s):  
Pham Thi Hoan ◽  
Khanh Son Trinh

The purpose of this study was to evaluate the effect of microbial transglutaminase (MTGase) on cheese quality properties using citric acid as a coagulant agent. The experimental results showed that citric acid has a temperature-dependent ability to agglomerate milk proteins. The process of protein coagulation at 50°C by citric acid (2.0%) gave fresh cheese with yield production (% H), dry matter content (% TS) and cheese solids yield (CSY) of 12.81%, 41.17%, 38.73%, respectively. The reconstituted milk was incubated with MTGase under different conditions of enzyme concentration (0-6.0 IU / g protein), processing temperature (30-50 °C) and time (60-180 min.). Enzyme treatment at 37 °C with enzyme concentration of 2 IU/g protein for 2 hrs showed the highest values of yield (15.03%), dry matter content (46.96%) and cheese solids yield (46.83%). Analytical results of the sensory score, acidity, whey separation and color difference of fresh cheese samples during storage (28 days) showed that using MTGase better maintained the quality of the product. Furthermore, MTGase also improved water holding capacity (reduced whey separation) during storage and did not affect the color of fresh cheese products. Moreover, the physicochemical and microbiological parameters of the product were also determined. The results showed that the quality of fresh cheese coagulated by citric acid met CODEX STAN 221-2001 for unripened cheese including fresh cheese.


Author(s):  
Nguyen Ha Trang ◽  
Nguyen Thi Tuyet Nam

Nitrogen dioxide (NO2) in the atmosphere can be measured using the tropospheric NO2 columns, indicating the number of molecules of NO2 in an atmospheric column from the ground surface to the top of the atmosphere above a square centimeter of the surface. In this study, the temporal variations of tropospheric NO2 columns in Vietnam during 2015–2020 were investigated. To do this, data on the columnar NO2 obtained from the Ozone monitoring instrument (OMI) onboard the NASA’s Earth orbiting satellite Aura were used. Consequently, northeastern Vietnam showed the highest values of the tropospheric NO2 columns over the whole study period (2015–2020), suggesting that this area would be a hot spot of NO2 pollution in Vietnam. In addition, the lowest and highest mean levels of columnar NO2 were found in 2020 and 2016, respectively. However, there is no statistical significance among the columnar NO2 in 2015–2020. Regarding the monthly variation, March and April exhibited the highest levels of tropospheric NO2 columns, which would be affected by frequent combustion activities (e.g., post-harvesting combustion) and meteorological conditions, such as lower air temperature. Results of this study can contribute to an understanding of NO2 pollution in Vietnam over long period.  


Author(s):  
Nguyen Dang My Duyen ◽  
Nguyen Quang Duy ◽  
Ly Ngoc Bin

Solvent exchange is considered an effective method that changes the physicochemical properties of starch, especially the absorption. Ethanol concentration is one of the important influencing factors to form porous pores from the surface to inside starch granules. In this study, the effect of ethanol concentration on technical properties of starch treated by solvents were investigated. The ratio of ethanol/water was prepared at 1/9, 3/7, 5/5, 7/3 and 10/0 (w/w), respectively. Corn starch was treated by solvent at 8% concentration. Morphology, oil and water holding capacity, solubility, swelling power, viscosity, and transmittance were studied to elucidate the effect of the ethanol concentration on the morphological and technical properties of corn starch treated by solvent. As a result, starch treated by solvent with different concentrations tended to form wrinkles and pore from the surface to the inside of the starch granules during ethanol immersion. Therefore, the oil and water holding capacity, solubility, swelling and viscosity of the solvent-treated starch samples increase as the concentration of ethanol increases. Otherwise, the transmittance of starch glues tends to decrease when the ethanol concentration increases.


Author(s):  
Nguyen My Linh ◽  
Nguyen Duy Dat

In this study, the commercial powder activated carbon (PAC) was added to a bench scale conventional activated sludge (CAS) system to enhance phenol removal. The mixed liquor suspended solid (MLSS) concentration of CAS with adding PAC was stable in all stages of operation, while MLSS concentrations in CAS without PAC addition sharply decreased as the Phenol loading reached 1.8 g phenol/L.day. Higher removal of chemical oxygen demand (COD) and Phenol achieved with the CAS by PAC addition compared with those achieved with CAS without PAC addition. The difference in COD removal efficiency was 7 - 9% in stages 3 and 4 (0.8 and 1.2 g phenol/L.day, respectively), and about 33% in stage 5 (1.8 g phenol/L.day). The advantage of CAS with PAC addition was clearly observed in the highest phenol loading (1.8 g phenol/L.day) because the MLVSS/MLSS ratio of CAS with PAC addition increased and the COD and phenol removal efficiencies kept stable in this stage, while reverse trends were found for CAS without PAC addition. The results indicated that the adaptive ability of the CAS by adding PAC was significantly higher than the CAS without AC addition. This study offers useful preliminary results for applying a hybrid system between CAS and adsorption with PAC for further research and application in future.


Author(s):  
Nguyen Thi Tinh Au

To date, work in the field of climate change adaptation has resulted in many strategies for adaptation. In Vietnam, there have been many climate change adaptation activities implemented but has not been evaluated fully on effectiveness so that we can modify or make a replica of them systematically. In order to evaluate the effectiveness of carried out climate change adaptation activities, it is necessary to assess the current status of climate change adaptation for each local. In this paper, a set of CCA status evaluation indicators was developed and appreciated for Moc Hoa district, Long An province, to support a comprehensive assessment of the adaptation ability of this study area, the validity of investment resources allocation, and vulnerability to expose suitable policies. This set includes three indicators which are natural environment resilience, climate change vulnerability and climate change risk mitigation. The results showed that the environmental resilience indicators and the risk mitigation indicators were arranged at the medium level, while the climate change vulnerability indicators were high.


Author(s):  
Le Thi Duy Hanh

The aim of this work was to strengthen the evidence of using micro diatom frustule as a promising candidate for drug loading materials for both hydrophobic and hydrophilic drug models. The morphological, surface elemental composition of diatomite powder, a raw source of micro diatom frustules and purified diatomite to collect micro diatom frustule were investigated. Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) confirmed again the porous silica structure of micro diatom structure as well as validated a necessity of raw diatomite purification before using. UV- vis was used to measure drug loading content of untreated and treated surface of micro diatom frustule with maximum loading for hydrophobic and hydrophilic drugs after 24 hours were at 5.48 ± 0.42% and 5.70 ± 0.34, respectively. Moreover, we also proved that the ability of drug adsorption on materials surface by the reduction of specific surface area and pore size of micro diatom frustule after loading using a (Brunauer–Emmett–Teller) BET method. Besides, the hydrophobic loading capacity of materials was affected by surface modification. Based on the results, micro diatom frustule showed a potential for a drug delivery system.


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