Vietnam Journal of Science, Technology and Engineering

10-14

Authors: Cuong Huynh Le Huy*

This study presents synthesis results of catalysts made of perovskite-like oxide La2-xSrxCuO4 (x=0.0, 0.5, 1.0) using the citrate method and crystallisation at 800°C. The structure of the catalysts was characterised by X-ray diffraction (XRD). The perovskite-like oxide catalyst activity was enhanced with gold (Au) and platinum (Pt). Au was mounted on the perovskite-like oxide catalysts by the sol-gel method. The activity of the perovskite-like oxide La2-xSrxCuO4 (x=0.0, 0.5, 1.0) and the perovskite catalyst LaMnO3/LaCuO3 was evaluated by complete oxidation of volatile hydrocarbons (HCs) in a mixture of toluene and methyl ethyl ketone (MEK) and carbon monoxide (CO) in a microflow analysis system combined with gas chromatography. The results showed that the light-off temperature (the 50% conversion temperature of the catalysts) of the Pt, Au/perovskite catalyst samples decreased significantly. The light-off temperature of the Au/LaSrCuO4 Au nanoparticle catalysts in the complete CO oxidation reaction reached a temperature of 150°C, lower than the Pt/LaSrCuO4 catalyst (170°C), allowing replacement of previous Pt catalysts with Au nanoparticle catalysts. The LaSrCuO4 catalyst had better oxidising activities than the La2CuO4 catalyst, indicating that the addition of strontium (Sr) has increased the catalyst activity, and demonstrates the potential for application in catalytic converters in motorcycles.

20-25

Authors: Ngoc Tu Nguyen*, Quang Huy Trinh, Thi Thu Ha Nguyen, Van Duc Tran, Thi Thuy Hang Ho

This study was carried out to produce a complex coagulant containing aluminum and iron salt from coal fly ash by H2SO4 acid. An application of this extracted solution as a coagulant was also investigated by the jar-test process. Fly ash collected at the Electrostatic precipitation (ESP) system in Mong Duong thermal power plant are mainly round and fine particles with diameters ranging from 0.2-8 μm, containing aluminum and iron of 15 and 6% respectively. At a room temperature of 25oC, with 1 M H2SO4 acid solution and the retention time of 20 minutes, the maximum contents of around 60.16 mg.l-1 of Fe and 4.37 mg.l-1 of Al were the most favorable to convert aluminum and iron from mineral forms to sulfate salt-based forms. The produced complex coagulants from fly ash of the Mong Duong power plant are proved to be effective for total suspended solids (TSS) removal from wastewater where the highest efficiency achieved 83.6% at the coagulant solution ratio of 5% (w/w) with a concentration of TSS in the initial wastewater was 60 g.l-1. The positive results from this study open a meaningful approach toward a huge of fly ash produced from thermal power plants as well as other coal-burn-related activities in Vietnam.

30-36

Authors: Minh Ly Nguyen*, Ton Nu Bao Tien Huyen

Isolated microspore culture is a useful tool to produce pure, fully homozygous parental lines in a short time. This study evaluated factors including the microspore developmental stage, cell culture density, and heat treatment influencing callus formation from melon microspores (Cucumis melo L.). The results showed that the obtained number of calli induced was highest (11.00±1.02) when cultivating flower buds with sizes 7.0-7.9 mm that contained microspores at middle-to-late uninucleate stages. The optimal microspore density for culture is4×104 cells. The cultured medium was NLN, containing 130 g/l of sucrose at pH 5.8. Heat treatment at 40ºC for 48 hours was best suited for callus induction of all flower bud sizes. The survival rate of microspores after 7 days of culture was lower than before inoculation and was only 75.6%. The development of the microspores and the arising of calli and embryos have been observed and evaluated for morphological cell characteristics. However, in this study, no mature embryo formation or seedling regeneration was observed.

42-46

Authors: Nguyen Thanh Binh*, Bui Thi Kim Anh, Nguyen Van Thanh, Dang Dinh Kim, Nguyen Minh Phuong

Constructed wetlands (CWs) have been widely used for wastewater treatment due to advantages such as low cost and easy operation. However, pollutant concentrations directly affect treatment efficiency by inhibiting plant and microbial growth. This study aims to evaluate the relationship between pollutant concentrations, tolerance of plants, and treatment efficiency of horizontal subsurface flow (HSF) CWs receiving synthetic wastewater. The results showed that Cyperus alternifoliusL. grew well in conditions with concentrations of chemical oxygen demand (COD) and NH4+ up to 75 and 125 mg/l, respectively, and pH 5-8. The lowest treatment efficiency was 56.7% at an initial COD concentration of 1000 mg/l. There were several dead plants in the CWs with a NH4+ concentration of 200 mg/l. When the initial COD and NH4+ concentrations were in the range of 500-750 and 75-125 mg/l, respectively, the treatment efficiencies of organic matter (COD) and NH4+ were 82.5-85.1 and 31-69.7%, respectively. The pH value was stable at a neutral level during the treatment process. The concentration ranges of COD (500-750 mg/l) and NH4+ (75-125 mg/l) were the optimal thresholds for pollution control while also ensuring normal plant growth. This study serves as a basis for considering wastewater characteristics in the design of HSF CW systems in practice.

54-58

Authors: Canh Viet Cuong Le*, Phuong Ha Tran, That Huu Dat Ton, Tuan Anh Le, Thi Loi Nguyen, Thi Kim Thu Vo, Thi Quynh Chi Vu

Solanum melongena is a member of Solanum genus that widely cultivated as fruit vegetable in Vietnam. According to Vietnamese traditional medicine, the fruits and whole plants are used to treat toothache, turgescence, pruritus, and haemorrhoids. As part of our project to study the chemical composition and bioactivity of Solanum genus in Vietnam, five flavonoid glycosides including kaempferol-3-O-β-D-glucopyranoside (1), isovitexin (2), kaempferol 3-O-β-D-glucoside-7-O-α-L-rhamnoside (3),kaempferol 3-O-β-D-sophoroside-7-O-α-L-rhamnoside(4), and kaempferol 3-O-β-D-sophoroside (5) were isolated from the methanol extract of the leaves of Solanum melongenagrowing in Thua Thien Hue province, by using various chromatography methods. Their chemical structures were determined by detailed analysis of 1D- and 2D-NMR and HR-ESI-MS data as well as comparison with the literature. Compounds (2) and (5) were isolated from Solanum melongena for the first time while compounds (3) and (4) were the first isolated from the Solanum genus. Besides, compounds 2-4 showed weak anti-inflammatory activities against NO production in RAW 264.7 macrophage line with IC50 values ranging from 54.28 to 91.37 μg/ml.

65-70

Authors: Khac Ky Lam, Thi Bao Tran Nguyen, Thi Huynh Nhu Nguyen, Thi Thanh Lai Le, Sao Mai Dam, Minh Hiep Dinh, Dai Hung Ngo*

Cordyceps neovolkiana DL0004 is a group of insect parasitic fungi collected at an altitude of 1650 m above sea level at the top of Langbiang Mountain, Lam Dong province, Vietnam. C. neovolkiana DL0004 has been used in traditional medicine and possesses numerous biological effects such as anti-cancer, anti-inflammation, antioxidant properties. In this research, the fungi biomass and fruiting body of C. neovolkiana DL0004 were cultured and examined for their antioxidant properties using test methods such as reducing power, scavenging 2,2’-diphenyl-1-picrylhydrazyl (DPPH) free radical, neutralizing 2,2’-azinobis(3-ethylbenzothiazonline-6-sulfonate (ABTS) free radical, and inhibiting xanthine oxidase (XO). The results showed that all 7 extracts of the biomass were more active than the fruiting bodies of C. neovolkiana DL0004. Furthermore, the ethyl acetate (EtOAc) extract of C. neovolkiana DL0004 biomass showed DPPH, ABTS, and XO free radical scavenging with IC50 values (the concentration of the sample required to inhibit 50% of radical) of 107.01 μg/ml, 111.91 μg/ml, and 106.2248 μg/ml, respectively. Moreover, the reducing power of the EtOAc from C. neovolkiana DL0004 biomass was 0.184 at 1000 μg/ml.From the obtained results, the biomass EtOAc fraction extract of C. neovolkiana DL0004 was demonstrated to contain antioxidant compounds with potential applications in the production of functional foods.

79-87

Authors: Thi Thanh Ngoc Nguyen, Thi Thanh Tam Phan, Thi Hiep Nguyen*

To comprehensively manage wound infection, tri-layer fibre membranes have been designed with two antibacterial agents, including silver nanoparticles (AgNPs) and chitosan oligosaccharide (COS), and their antibacterial properties were evaluated using qualitative and quantitative tests. While the first polycaprolactone (PCL) silver layer and the second plasma-treated PCL layer were fabricated by electrospinning, the third COS layer was constructed via coating and heat-vacuum drying. The formation of the membranes and their fibrous and porous structures were examined using scanning electron microscopy (SEM). The antibacterial activities of the membranes against Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus were examined by disk diffusion and percentage reduction assays, which were performed simultaneously as per the certificates from the Ministry of Health Institute of Public Health in Ho Chi Minh city. The tri-layer membranes, named PCLAg50/PT (plasma treatment)/COS and PCLAg500/PT/COS, achieved desirable antibacterial results with extensive inhibition zones and bacterial reduction rates ranging from 99-100%. In addition, while the PCLAg500 membrane exhibited broad inhibition zones and reduction rates ranging from 94.6-97%, the PCLAg50 membrane achieved reduction rates ranging from 67.5-82.1% despite the absence of inhibition zones. As a result, the fabricated tri-layer membranes could reduce local and opportunistic infections. Depending on infectious risks, the concentration of silver utilsed as an infection-prevention agent must be adjusted from 50 to 500 ppm to ensure safety.

9-13

Authors: Thi Thu Hien Le*, Van Tuan Chu, Van Tuan Pham

The authors report the characteristics and optical properties of Bi3+-doped SnO2 quantum dots prepared bysol-gel and hydrothermal methods. The structure and morphology of the materials as a function of dopingconcentration were studied and analysed by X-ray diffraction (XRD) and scanning electron microscope(SEM). The structure of the material was assigned to the tetragonal crystal structures of the SnO2 rutile phase,reported in JCPDS Card No. 41-1445. With the increase of Bi3+ doping, the crystallinity of Bi-doped SnO2worsened. The average sizes of the SnO2 nanocrystals were within 3-8 nm. The effect of Bi3+ ion concentrationon the absorbance properties of the materials was investigated by UV-Vis absorption spectra. The absorbancedecreased with increasing the concentration of Bi3+ dopant in the SnO2 lattice. The bandgap width decreasedwith Bi3+ dopant concentration. All Bi3+-doped SnO2 samples presented an enlargement of the light absorptionrange due to a bandgap width decrease.

19-24

Authors: Chi Tran Nhu, Phu Nguyen Dang*, Tung Bui Thanh, Trinh Chu Duc

In this report, we develop a low-cost cyclic voltammetry platform for electrochemical analyses based on the LMP91000 integrated circuit (IC). The proposed system can be suitable to detect chemicals of interest in food safety or biology. The system includes three main blocks: the electrodes, electrochemical measuring circuit, and data acquisition. An algorithm was also built to process and display the data on the screen. Experiments are carried out with a standard redox solution containing Fe(II)/Fe(III) 5 mM and KCl 0.1 mM to evaluate system performance and make comparisons to the commercial potentiostat. The results show that the obtained signals from the proposed system and the commercial potentiostat device are similar. With applications of the miniaturised potentiostat, a non-enzymatic electrochemical biosensor for urea detection was fabricated on cobalt sulphide materials (CoS) synthesized via a microwave assisted method. The sensing performance for urea was determined by changing the oxidation potential peak of 100 mV. The sensor had a linear range from 1-8 mM corresponding to the urea concentration in blood. The sensor sensitivity was comparable (7.5 μAmM-1cm-2) to some previous publications. With the achieved results, the proposed system demonstrates potential in urea detection and can be a prototype to develop a commercial device for point-of-care testing in the future.

32-37

Authors: Ngoc Lieu Le*, My Thi Huyen Le, Nguyen Hoang Khoa Nguyen, Linh Tran Khanh Vu

The aim of this research was to investigate the effect of thermal treatments, including roasting, microwaving, and steaming, on anti-nutritional factors and physical and antioxidant properties of black gram (Vigna cylindrica L. Skeels). Regarding its physical properties, thermal treatment increased the water-holding capacity (WHC) and decreased the oil-holding capacity (OHC) of the black gram samples. No significant difference was observed between the roasted sample and the control. Regarding the chemical properties, anthocyanins accounted for the vast majority of total phenolic content (TPC). The steamed sample had the lowest TPC and anthocyanin values, which were 272.46 mg/100 g dry basis and 121.20 mg/100 g dry basis, respectively. Among the three types of thermal treatments, roasting resulted in the highest TPC content, which was 424.35 mg/100 g dry basis. Particularly, the steaming treatment led to the lowest anthocyanin content and antioxidant capacity (AC) in the flour sample; furthermore, there were no significant differences in the TPC and AC values between the microwaved and roasted samples. The phytate content was significantly reduced in all heat-treated samples and there were no significant differences among these cooked samples. The tannin content of the steamed sample was recorded to be the lowest, which was 164.19 mg/100 g dry basis. In summary, roasting, microwaving, and steaming significantly influenced the nutritive values of black gram (Vigna cylindrica L. Skeels).

43-46

Authors: Thi Thu Hoai Pham*

The rapidly developing of industry and population leads to various problems, such as an increase in the energy used and discharging of pollutants into the environment. Water pollution is a big issue in Vietnam as well as in the world. Therefore, finding the method for the treatment of water is urgent.This work investigated activated carbon derived from rice straw biomass (ACRS) for the adsorption of phenol. The surface morphology, surface functional group, and surface area of the ACRS were determined by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and Brunauer-Emmett-Teller (BET) analysis, respectively. ACRS had a porous structure along with a larger surface area of 216.3 m2/g, which effectively enhanced the adsorption performance of phenol. The removal performance of phenol increased with increasing the contact time (10-60 min), then reached equilibrium at 90 min. The maximum adsorption capacity of phenol using ACRS was 128.4 mg/g and the adsorption behaviour of the pollutant fit well to the Langmuir and Freundlich isotherms. Experimental results revealed that adsorption by surface area, activated sites, pores, and complexation between functional groups of the adsorbent and phenol were major mechanisms.

54-62

Authors: Sang Van Le*

This study was conducted to compare the genetic gain per sow per year of Duroc pigs in twelve scenarios. These scenarios were based on the number of traits used such as average daily gain (ADG), feed conversion ratio (FCR), intramuscular fat content (IMF) and were also based on the number of records of phenotype for these traits from the individual animal and its relatives. The values of all relevant genetic and economic parameters were selected from the literature and applied to the magnetotail (MT) index model to calculate the index selection accuracy and response per trait. Genetic gain per sow per year was calculated based on a farm with 400 Duroc sows. The results showed that the economic value of FCR was much larger than the economic value of ADG and IMF. The selection response in units of ADG was higher when using phenotypes measured using ADG and FCR only while selection response per unit of IMF was the opposite. The economic weight of the response for IMF using three traits (ADG, FCR, and IMF) information was doubled when using ADG and FCR trait information. The standard deviation (SD) index and genetic gain per year when using information from the three traits were higher than those when using information from ADG and FCR. Within the same number of traits measured, the genetic gain per sow per year was highest at $568.05 when using information of the three traits from the individual animal’s phenotype and their progeny. It was the lowest at $473.06 when using ADG and FCR information from only the animal itself.

70-75

Authors: Thanh Dat Ta, Khanh Tran Van, Thanh Binh Nguyen, Manh Thuong Le, Long Ha Le Hai, Hoang Viet Nguyen*

Major histocompatibility complex class I chain-related A (MICA) is a tumour antigen that is greatly expressed on the surfaces of human malignancies and infection cells, which trigger attachment to immune cells. Although many studies have investigated the role of the MICA rs2596542 variant involved in high risk of hepatocellular carcinoma (HCC), the expression regulation of rs2596542 MICA in nasopharyngeal carcinoma (NPC) susceptibility with the Epstein-Barr virus (EBV) is still ambiguous. Therefore, this study was conducted to elucidate the association of rs2596542C/T and EBV load to MICA expression in NPC tissues. A total of 70 tumour tissues from NPC patients were enrolled in the current study. The genetic variant of rs2596542 was identified by Real-time PCR genotyping, and MICA protein expression was quantified by immunohistochemistry staining. A significant difference was observed in the expression of MICA regarding EBV copy numbers (p<0.01). High expression of MICA presented a considerably lower EBV status. In addition, higher expression of homologous MICA rs2596542 CC was significantly associated with a lower EBV load (p<0.001) thus suggesting a protective role of allele C against the infection of EBV. In summary, rs2596542 MICA plays an important role in the immune response preventing the EBV among NPC patients as well as developing a new predictive biomarker for virus susceptibility to cancers.

81-88

Authors: Thanh Diem Ngo Thi, Xuan Hoan Nguyen, Hiep Vu Phung, Minh Thanh Le, Lan Huong Nguyen*

In this study, a simple method for fabrication of a ZnO@TiO2 nanocomposite was developed to degrade amoxicillin (AMX) from aqueous solution by heterogeneous photocatalytic perozone under UV irradiation (O3/H2O2/ZnO@TiO2/UV). ZnO nanoparticles were formed by the sol-gel method. The ZnO-NPs were then composited with commercial TiO2 at modification ratios of 0, 10, 20, 30, 40, and 50% of ZnO-NPs to generate ZnO@TiO2 nanocomposites. The physical-chemical characteristics of ZnO, TiO2, and ZnO@TiO2 at the optimal modification ratio were determined using SBET, SEM, EDX, and XRD analysis. The catalytic activity of ZnO@TiO2 was evaluated by degradation of AMX in an O3/H2O2/ZnO@TiO2/UV system. The results showed that 10%ZnO@TiO2 exhibited the highest catalytic activity in degradation (in term of COD removal) of AMX with about 80% for 70 min of reaction time. This efficiency was higher than that of both systems using ZnO or TiO2 only by double. This primary finding demonstrates the feasibility of 10%ZnO@TiO2 photocatalysts in perozone systems to degrade persistent organic compounds in practical applications.

10-15

Authors: Minh Truong Nguyen, Viet-Hung Dang, Truong-Thang Nguyen*

In this article, deep learning probabilistic models are applied to a case study on evaluating the influence of specialized mini projects (SMPs) on the performance of engineering students on their final year project (FYP) and cumulative grade point average (CGPA). This approach also creates a basis to predict the final performance of undergraduate students based on their SMP scores, which is a vital characteristic of engineering training. The study is conducted in two steps: (i) establishing a database by collecting 2890 SMP and FYP scores and the associated CGPA of a group of engineering students that graduated in 2022 in Hanoi; and (ii) engineering two deep learning probabilistic models based on Bayesian neural networks (BNNs) with the corresponding architectures of 8/16/16/1 and 9/16/16/1 for FYP and CGPA, respectively. The significance of this study is that the proposed probabilistic models are capable of (i) providing reasonable analysis results such as the feature importance score of individual SMPs as well as an estimated FYP and CGPA; and (ii) predicting relatively close estimations with mean relative errors from 6.8% to 12.1%. Based on the obtained results, academic activities to support student progress can be proposed for engineering universities.

28-31

Authors: Chinh N. Le, Cuong X. Luu, Son Tung Ngo, Van V. Vu*

AA13 polysaccharide monooxygenases (AA13 PMOs) are novel enzymes that break down starch using a copper active site in a substrate binding groove on a solvent-exposed surface. The structure of the copper active site is influenced by the residues in the groove, while the crystal structure of Cu(II)-AA13 was damaged by photoreduction and lacked two exogenous ligands. We utilized density functional theory (DFT) calculations to obtain insights into the structure of Cu(II)-AA13 in the presence and absence of a key residue (G89) of the groove that interferes with the distal coordination site. Results show that the copper active site of AA13 PMOs can exhibit both 6-coordinate and a 5-coordinate structures depending on position of G89. The active site features are intermediate to those in AA9 and AA10 PMOs, which are the most abundant and well characterized PMO families. In addition, the superoxo species of AA13 has structural parameters halfway between those in AA9 and AA10 PMOs. The structural relationship between the active site and intermediates of AA13 with AA9 and AA10 PMOs is also consistent with their evolutionary relationship.

36-44

Authors: Tran Thang Do*, Van Phong Dinh, Quang Hoang Nguyen, Duc Hoang Chu

Many key factors driving the Fourth Industrial Revolution (Industry 4.0) are to construct industrial robots to become increasingly intelligent, multi-functional, flexible, and efficient, as well as a complementing platform for collaboration with people. The latest generation of intelligent robots, known as Cobots (collaborative robots), can now cooperate and stand side-by-side with humans in a safe way and perform many tasks that require the same skills as humans. This paper firstly overviews the new generation of Cobots used for manufacturing and other applications to see forward into the future. Secondly, we briefly mention innovation technologies that should be integrated and extended deeper into smart robots to develop their applications in smart manufacturing, science and technology, high education, and so on. As a result, it is necessary to build new prototype robot systems that possess open hardware and software architectures for the development of both their smartness and dynamic skills. The main content of this paper will propose an open-architecture system for smart robots as well as like-robot machines using a CompactDAQ platform from National Instruments (NI). In the end, some information about the realized system implemented at the Institute of Mechanics of Vietnam Academy of Science and Technology will be shown for far joint discussion.

51-54

Authors: Van Tuan Nguyen*, Anh Tuan Tran, Thi Hoang Yen Vu

Indirect carotid cavernous fistulas (ICCFs) are rare disease entities triggered by indirect low flow between the cavernous sinus and the meningeal branches of the internal or external carotid artery or from both. To evaluate clinical characteristics, angiography, and relationship to the result of endovascular treatment of indirect carotid cavernous fistulas. A prospective study of 32 patients diagnosed to identify ICCFs through digital subtraction angiography (DSA) and intravascular intervention. Results showed that indirect carotid cavernous fistulas were more common in females of advanced age (68.8%) and occurred spontaneously (87.5%); the most common symptoms included chemosis (93.75%), headache (87.5%), proptosis (53.1%), and tinnitus (37.5%) with type D being the most common (81.2%). Thirty out of thirty-two patients with intervention had complete flow block (83.3%), near complete (13.3%), and failure in one case. Incomplete occlusion interventions and failures were of the type D complication. The complication and number of drainage veins are related (p<0.05). ICCFs have diverse symptoms that depend on the drainage veins but most commonly were red eyes, headache, and protruding eyes. The ICCFs were mostly D-type formation and endovascular treatments were safe and effective. Common complications occurred in the case of many veins draining.

60-63

Authors: Hang Thi Thu Dinh*, Mai Ngoc Nguyen, Su Xuan Hoang

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus Disease 2019 (COVID-19), has rapidly spread through the entire world and has become the worst pandemic from December 2019 until now. The establishment of positive standards for molecular diagnostic testing for SARS-CoV-2 plays a critical role in development and assessment of diagnostic assays associated with the shortage of positive specimens and viral culture fluids. This study aims to establish a novel assay for in-vitro RNA fragment synthesis based on amplicons of self-priming PCR targeting envelope protein gene and RNA-dependent RNA polymerase (RdRp) gene of SARS-CoV-2. The cDNA library of the targeted genes of SARS-CoV-2 was generated by using long-primers named sMn1 forward/reverse primer (E gene) and sMn2 forward/reverse primer (RdRp gene) for self-priming PCR assays. The synthesised amplicons that overlap the target sequence of the World Health Organization (WHO) assay were cloned into a pGEM-T easy vector, then transformed into E. coli competent cells by conventional methods. The recombinant plasmids were used as materials for in-vitro RNA transcription. Concentrations of the in-vitro transcribed RNA were 200-800 ng/μl with A260/A280 ratios of 2.0-2.2. Gel electrophoresis showed a single band of each RNA molecule with sizes of 216 and 214 bases for sMn1- E and sMn2- RdRp gene, respectively. Furthermore, we effectively evaluated the in-vitro transcribed RNA by a one-step, real-time RT-PCR assay according to the standard WHO protocol. The stability of in-vitro RNA over a 6-month storage period was then investigated. In conclusion, our assay for in-vitro synthesis of RNA fragments transcribed from self-priming amplicons were successfully established and thus these positive standards were useful for molecular diagnosing of SARS-CoV-2.

70-78

Authors: Emerson Joseph Addison*

Methicillin-resistant Staphylococcus aureus (MRSA) is a global health concern. Many antibiotics are no longer effective at treating MRSA, which causes an increase in adverse patient outcomes. This has led to calls for new antibiotics and treatment strategies to combat the spread of MRSA and multidrug resistance (MDR). The antimicrobial secondary metabolites found in plants are a promising source for new antibiotics and treatment strategies. Cannabis sativa L. is especially promising, as it produces dozens of antimicrobial secondary metabolites that are active against Staphylococcus aureus (S. aureus) and MRSA strains. In addition to its antimicrobial properties against S. aureus and MRSA, cannabis has many other desirable properties for potential antibiotics. Cannabis secondary metabolites are active against a wide range of microorganisms, are generally safe, target multiple bacterial processes and structures, have antimicrobial synergies, have a low potential for resistance development, can be produced inexpensively and combined with existing antibiotics to further reduce costs, and contain secondary metabolites capable of penetrating a variety of in vivo environments. These characteristics make cannabis a potential resource against MRSA and MDR bacteria.

84-90

Authors: Tien Dat Nguyen, Van Toi Vo, Thi Thanh Huong Ha*

Bipolar disorder (BD) is a serious mental disorder that globally affected 40 million people in 2019. According to the National Alliance on Mental Illness (NAMI), the present state of scientific knowledge only permits psychiatrists to diagnose BD using subjective and imprecise questionnaires. Therefore, developing a diagnostic tool with objective and precise biomarkers should be a major focus of research in this field. Among the potential biomarkers for BD, electroencephalogram (EEG)-based signatures of BD are considered to be the most optimal marker due to their strong links with behavioural symptoms and also their non-invasiveness. The goal of this review is to give a detailed summary of current techniques for investigating the traces of BD through EEG abnormalities. In this review, 13 studies from databases such as ScienceDirect and PubMed seeking to utilize EEG characteristics to diagnose BD were selected. The search keywords were “EEG in BD diagnosis”, “EEG microstates in BD”, and “EEG features for BD patients”. The publication date was set from 2007 to 2021. From these studies, we synthesize the effects of BD on each EEG feature, as well as detail the pros and cons when using each feature as a biomarker for BD. Results showed that EEG microstates demonstrate their potential among the seven EEG properties discussed in this article, as shown by several studies. By definition, EEG microstates are a dynamic representation of the spatial distribution of the scalp's electric potential as it varies over time. Specifically, four microstate classes recorded in different brain regions are classified into A (right-frontal left-posterior), B (left-frontal right-posterior), C (midline frontal-occipital), and D (midline frontal topographies). Greater presence of microstate class B in BD patients during task-free resting states are a distinctive characteristic of BD patients from which BD can be differentiated from other psychiatric illnesses. Besides microstates, EEG resting states are also considered to have a bright future in BD diagnosis. Specifically, by investigating brain frequency bands, researchers have discovered that BD patients exhibit abnormal delta and alpha signals as compared to healthy controls (HCs). The abnormalities of microstate B in EEG microstate characteristics would be the most promising biomarker for detecting BD. In addition, anomalies in delta and alpha signals during resting EEG states are possible BD diagnostic indicators.

8-12

Authors: Danh Duc Ha*, Thi Oanh Nguyen

The herbicide propanil has been widely applied in Vietnam and around the world to control weeds. In this study, Acinetobacter baumannii DT isolated from soil was used to determine propanil degradation. Degradation experiments were carried out with condensed cells at 109 CFU/ml with both free and immobilized forms of the bacteria. Propanil degradation rates by bacteria immobilized in alginate were higher than those of free cells at the same concentrations. The degradation curve as a function of concentration fit well to the degradation kinetics described by the Edwards model with a maximum degradation of 0.034±0.003 mM/h for free cells and 0.053±0.005 mM/h for immobilized cells. Moreover, the immobilized bacteria could tolerate higher propanil concentrations and degrade propanil in a well-known herbicide more effectively compared to the freely suspended bacteria. These results demonstrate that A. baumannii DT immobilized in alginate is suitable for degradation of propanil in herbicides.

19-23

Authors: Thi Thu Ha Nguyen, Thi Tu Anh Le, Thanh Tra Nguyen, The Son Ninh*

A phytochemical investigation on the ethanolic (EtOH) extract of the Vietnamese Curcuma longa (C. longa) rhizomes has led to the isolation of four curcuminoids including curcumin (1), demethoxycurcumin (2), bisdemethoxycurcumin (3), and cyclocurcumin (4). The chemical structure of compounds 1-4 was elucidated by Nuclear magnetic resonance (NMR) and Mass spectrometry (MS) spectral data. Based on High-performance liquid chromatography (HPLC) quantitative analysis, the amounts of three major compounds 1-3 in the C. longa extract were calculated and reached 7.215±0.101, 3.927±0.031, and 2.255±0.049 mg/g, respectively. Curcuminoids 1-4 have induced IC50 values of 9.23-14.6 μg/ml in a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay as compared with that of the positive control resveratrol (IC50 11.5 μg/ml). Compounds 1-4 with IC50 values ranging between 8.7-15.54 μg/ml were better than the positive control acarbose (IC50 169.14 μg/ml) in α-glucosidase inhibitory examination. In addition, the EtOH extract and compounds 1-4 were also responsible for inhibitions against enzyme acetylcholinesterase and four cancer cell lines including including epidermoid carcinoma (KB), hepatocellular carcinoma (HepG2), lung cancer (SK-LU-1), and breast cancer (MCF7).

29-37

Authors: Cuong Mai Bui, Thinh Xuan Ho

The flow of a thixotropic Bingham material past a rotating cylinder is studied under a wide range of Reynolds and Bingham numbers, thixotropic parameters, and rotational speeds. A microstructure transition of the material involving breakdown and recovery processes is modeled using a kinetic equation, and the Bingham- Papanastasiou model is employed to represent shear stress-strain rate relations. Results show that the material’s structural state at equilibrium depends greatly on the rotational speed and the thixotropic parameters. A layer around the cylinder resembling a Newtonian fluid is observed, in which the microstructure is almost completely broken, the yield stress is negligibly small, and the apparent viscosity approximates that of the Newtonian fluid. The thickness of this Newtonian-like layer varies with the rotational speed and the Reynolds number, but more significantly with the former than with the latter. In addition, the lift and moment coefficients increase with the rotational speed. These values are found to be close to those of the Newtonian fluid as well as of an equivalent non-thixotropic Bingham fluid. Many other aspects of the flow such as the flow pattern, the unyielded zones, and strain rate distribution are presented and discussed

44-48

Authors: Khoa Mai Trong, Phuong Pham Cam, Luan Nguyen Duc, Hung Nguyen Quang, Phuong Dao Manh, Thai Pham Van

To assess the effectiveness of radiosurgery with a rotating gamma system (RGS) for paediatric brain tumours and arteriovenous malformation (AVM), this work was carried out on 123 patients with brain tumours or AVM received radiosurgery at Bach Mai hospital. The median dose was 13 Gy from a range of 8 to 20 Gy. Endpoints include the effects of increased intracranial pressure, seizures, hemiplegia, and tumour size on the syndrome. Results exhibited that the percentages of patients with complete response, partial response, and disease progression out of 59 patients with headache accounted for 11.9, 69.5, and 18.6%, respectively. Of the 20 patients with seizures, 30% had complete response, 65% partial response, and 5% stable disease. Regarding brain tumour size, 9 months after treatment, those with complete response, partial response, stable disease, and disease progression made up 18.7, 50.4, 14.6, and 16.3% of the total patients, respectively. There was no statistically significant effect of radiation dose on the results. This study showed a high percentage of children with brain tumours and AVM undergoing radiosurgery with a RGS had symptomatic responses after treatment.

53-61

Authors: Tin Dai Luong, An Tran-My Le, Nhan Thien Vo, Thi Hiep Nguyen

Hydrogel materials have attracted extensive research over the last few decades, especially in tissue engineering, due its many comparable properties with native tissue. This study proposes a new approach to hydrogel fabrication that combines oxidized alginate (OA) into N,O-carboxymethyl chitosan (NOCC) and an oxidized hyaluronan-based hydrogel system employing low cost, domestically sourced chitosan and alginate. Hydrogel fabrication parameters including component ratio and hydrogel concentration were studied. Fourier transform infrared spectroscopy (FT-IR) analysis was applied to confirm the chemical structure of the modified materials. Fabricated hydrogel samples were assessed by cross-sectional surface morphology, equilibrium swelling degree, and in vitro degradation behaviour. The results revealed NOCC and oxidized hyaluronic acid (OHA)-OA component contributions toward hydrogel properties, a threshold of raising total polymer content within the network, and a comparison with previous formulations using unmodified alginate. Using low cost domestic resources is a promising way to reduce fabrication expenses, and further work should be performed to evaluate the potential of this cost-effective hydrogel for the tissue engineering field.

69-75

Authors: Lam Quang Nguyen, Hoang Minh Anh An, Vu Quang Thinh Tran, Phuc Hoang Anh Le, Van Luan Tran, Mai Thao Le, Trong Kien Nguyen, Thi Thanh Huong Ha

Cognition is one of the most vital brain functions, which ranges from assisting students in recalling what they have been taught to assisting us in concentrating while accomplishing chores. Nowadays, many jobs require advanced cognitive abilities, particularly among high school and university students. As a result, preserving or improving our cognitive abilities has become necessary in modern society. Alpha-wave music, which targets the brain frequency range from 8 to 12 Hz, is a promising approach to boosting cognitive performance. The purpose of this study is to evaluate the immediate, short term, or long term effects of alpha wave music on the cognitive performance and brain activity of students. In an online experiment, two groups of students were recruited and randomized into control and experimental groups. The experimental group was required to listen to alpha music for two weeks (here called the intervention). Participants from both groups will have their cognitive performance assessed before, immediately after, and two weeks following the intervention. In the immediate effect experiment, another group of participants have their alpha relative power evaluated while performing different tasks. The results of the online experiment revealed that feedback from participants listening to alpha music are mostly positive, while the response time of cognitive tasks indicated an improvement trend (p<0.05). The positive potential of alpha music was also confirmed with the immediate effect study where the alpha power was higher during alpha music exposure than during the remaining sessions. In conclusion, this study provided preliminary evidence to support the implementation of alpha music intervention to improve the cognitive function of students.

82-89

Authors: Thi Hoa Tran, Boris Fabres, Ngoc Ha Hoang, Hoai Le Tran

While the tourism and hospitality sectors in Vietnam have been rapidly developing, the increasing consumption of natural resources and production of associated waste, especially in coastal and island sites, threaten these marine areas with pollution. This study provides data on solid waste from 10 hotels in three coastal provinces of Vietnam, namely, Hai Phong, Quang Nam and Phu Yen. The results indicated significant percentages and volumes of organic waste especially from large-scale hotels with in-house food services like restaurants and bars. The proportions of organic and recyclable solid waste from all three surveyed cities ranged between 35-84% and 10-27%, respectively. Plastic waste accounted for a relatively high proportion of solid waste ranging from 27 to 60% total solid waste by volume and from 7 to 30% by weight. In particular, PET plastic made up the highest proportion of solid waste in Cat Ba town (52.41%) and Tuy Hoa city (39.81%) while single-layer plastic accounted for the highest proportion (29.55%) in Hoi An city. Plastic waste from food packaging, related to the cultural habits of guests that bring instant food items during their stay, was identified as an important issue, which reflects a valuable but presently wasted potential resource. These quantities of hotel solid waste can be recovered and provide additional environmental and health benefits to the community by not being dumped, landfilled, or openly burned.

10-15

Authors: Nam Trung Tran*, Thi Minh Huong Pham, Tan Lam Nguyen

Considering its superior photocatalytic activity and excellent chemical stability, titanium dioxide (TiO2) is an excellent candidate for photoelectrochemical (PEC) hydrogen production. Besides, many challenges exist ahead of improving the photoresponse of TiO2 to visible light while maintaining high photocatalytic activity. Herein, the authors report recent efforts to improve the visible light PEC activity of TiO2 nanorods by in-situ doping with various iron (Fe) concentrations using a hydrothermal method. The influences of Fe doping concentrations on the morphological and structural properties of TiO2 nanorods were investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. Furthermore, this work demonstrates that Fe doping could improve the PEC activity of TiO2 nanorods under visible light irradiation. The authors achieve a remarkable enhancement in the photocurrent density, as high as 2.9 mA/cm2 at an applied voltage of 0.5 V, for the sample synthesised with an Fe doping concentration of 10 mM. These results reveal that Fe-doped TiO 2 nanorods can serve as ideal materials for PEC applications.

21-27

Authors: Tien Cong Nguyen*, Duc Dung Pham, Thi Minh Dinh Tran, Thi Thuy Linh Bui

Five new derivatives of N-(4-oxo-2-thioxothiazolidin-3-yl)-2-((3-aryl-4-oxo-3,4-dihydroquinazolin-2-yl)thio) acetamides have been synthesized successfully through a four-step process from anthranilic acid and aryl isothiocyanates as starting materials. The total yields ranged from 29 to 31% and these structures were determined by IR, 1H-NMR, 13C-NMR, and HR-MS spectra.

34-41

Authors: Suong V. Hoa*, Daniel I. Rosca

This paper presents an application of 4D printing of composites (4DPC) to make composite structures of complex geometries without the need for complex moulds. This application is illustrated through the formations of the letters V, i, e, t, n, a, and m, which form the word Vietnam. In the procedure, laminates made of carbon/epoxy prepregs are laid on a flat mould. The deposition of the prepregs on the flat mould is done using an automated fibre placement machine (AFP), which can be considered as a large size 3D printer. For a smaller structure, the prepreg deposition can be accomplished using an AFP machine or by hand lay-up. Upon curing and cooling to room temperature, the laminate transforms itself from a flat configuration to the shape of the intended letter, except for the letter V. The mechanism that enables this transformation relies on the anisotropy of the laminate. This method has many potential applications, particularly in the delivery of bulky three-dimensional structures to remote locations.

50-53

Authors: Thi Loan Pham*, Xiao Jian Zhuang, Thi Hoai Thu Nguyen, Phan Anh Nguyen, Duy Thanh Trinh

After almost 30 years and many projects investigated all over the world, the full potential that 3D printing technology can bring to the construction industry has yet to be realised. There are many challenges that face the application of 3D printing technology to the construction field. Among these challenges, mixture proportion design is crucial for the preparation of 3D printing concrete. Therefore, this study focuses on mix proportion design approaches and tests, which access some rheological properties of the fresh mortar. Because they are highly practical and convenient in construction, materials including cement, fly ash, and natural sand were selected for mixing proportion analysis. Slump-flow tests, V-funnel tests, and buildability tests were also employed in this study. This first analysis on the mixture proportion and method to evaluate rheological properties of 3D printing mortar can be considered a reference and orientation to develop 3D printing technology in Vietnam.

59-64

Authors: Van Thieu Ha*, Huu Tung Trinh

Eosinophilic gastroenteritis (EGE) is a digestive disorder in children and adults that is characterised by eosinophilic infiltration in the stomach and intestine. Depending on the dominant layer of infiltration, this disorder is classified into three types, namely, mucosal, muscularis, and subserosa. Subserosa clinical presentation usually begins with ascites and is sometimes associated with symptoms of intestinal obstruction. Ascites is characterised by marked eosinophilia in ascitic fluid. EGE with ascites simulating appendicitis and peritonitis is rare in paediatric patients. This publication aims to report a case series of EGE with clinical features, treatment responses, and a review of the current strategies in the management of eosinophilic ascites.

69-75

Authors: Thi Thu Hang Ta, Bao Kim Nguyen, Thi Hong Khanh Do, Thanh Tung Bui*

The COVID-19 pandemic causing acute respiratory syndrome is a significant public health problem. Drugs that can treat this disease are currently a high priority. The SARS-CoV-2 spike protein and human ACE2 enzyme receptor, which both play important roles in virus entry into the host cell, are promising therapeutic targets for inhibiting viral infection. This research evaluates the potential of chalcone compounds to inhibit the spike proteins and ACE2 enzymes through molecular docking in silico approaches. Based on the ChemFaces database, we collected 92 chalcone compounds. These compounds were further docked to target the active sites of spike protein and human ACE2. After comparing the binding energies of the 92 compounds to artemisinin, ribavirin, and lopinavir, which have inhibitory activity to these protein targets of SARS-CoV-2, we chose 20 out of the 92 compounds that had a higher ability to inhibit the protein targets than the reference inhibitors. Next, five phytochemical compounds with the best binding energy were selected, which included flavanomarein, sarcandrone B, sarcandrone A, calyxin H, and sieboldin. Then, Lipinski’s 5 rule was used to evaluate the druglike properties of these compounds. Predictive ADME/tox filtering tests were also applied to the top docked compounds. The results suggest that sarcandrone B has good pharmacokinetic properties, which should be further explored as an anti-SARS-CoV-2. To confirm these findings, experimental studies are recommended.

82-85

Authors: Yen Hoang Luu, Thai Hong Pham*, Hong Minh Bui, Jérôme Constant

A taxonomic study on the genus Macrosemia from Vietnam in which a new species Macrosemia sapaensis sp. nov. is described. This species was collected from Lao Cai province in north Vietnam. Information on the distribution, photos of an adult, and illustrations of the male genitalia are provided for the new species. Based on the male characteristics, we provide a key to the genus Macrosemia Kato, 1925 (Hemiptera: Cicadidae) of Vietnam.

95-98

Authors: Khon Huynh

Fibronectin is an abundant and ubiquitous extracellular matrix component that regulates a wide range of cell functions by directly interacting with cell surface integrin receptors. In a prior study, we observed that fibronectin can accelerate the autologous cellular repopulation of implanted decellularized grafts, enhancing their adhesion capacity and biocompatibility, through fibronectin fibrillogenesis. The supportive effect of deposited fibronectin was shown to be dissimilar in different regions of implanted decellularized grafts. This led us to question whether there is any difference in conformation of fibronectin deposited on the luminal and adventitial surfaces of decellularized aortic conduits after implantation. In this study, we doubly labelled fibronectin with a fluorescent resonance energy transfer (FRET) pair and use this to analyse differences in conformational changes of adsorbed fibronectin at different sites of the decellularized aortic conduits.