Vietnam Journal of Science, Technology and Engineering

3-8

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

Experimental results of the mix design and fresh properties of a proposed concrete for 3D printing are presented in this paper. Layer-by-layer sample components were built by the designed concrete and extruded through a nozzle. The two most critical rheological properties of the designed mix are extrudability and buildability as they are both highly influenced by mix proportion and the presence of superplasticizers. Therefore, this study focused on mix proportion design approaches and laboratory test methods, which generally allowed access to the fresh concrete’s printable properties. Because they are efficient and convenient in construction, materials including cement, fly ash, natural sand, and superplasticizer were selected for mixing proportion analysis. Slump-flow tests, V-funnel tests, buildability tests, and extrudability tests were also employed to access the printability of the proposed mixture in this study. This first analysis on the mixture design approach and laboratory test methods to evaluate the printable properties of 3D-printable concrete can be considered a reference and orientation to further develop 3D printing technology in Vietnam.

14-18

Authors: Thao Phuong Le Nguyen, Thao Thanh Bui, Bao Kim Doan, Linh Phuong Bui, Tam Hoang Luu, Chau Duc Tran, Tung Viet Tuan Tran, Tsutomu Yokozawa, Ha Tran Nguyen*

A conjugated molecular triad based on pyrene and 9,9-dioctyl-9H-fluorene has been successfully synthesised via the Suzuki cross-coupling reaction with yield of 48%. In this polymerization, the Pd(PPh3)4 has been used as the catalytic in the presence of K2CO3 as base in a mixture of toluene/ethanol/H2O at 80oC under N2. The chemical structures of the conjugated molecules were determined via Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H-NMR) that proved the chemical structure of 1,1’-(9,9-dioctyl-9H-fluorene-2,7-diyl)dipyrene. The optical properties of the molecules were investigated via UV-Vis in different concentration that exhibited the maximum absorption of 340 nm. The conjugated molecular triad also have been investigated by fluorescence spectroscopy that showed a mission peak at 475 nm under the excitation of 350 nm of wavelength. In addition, the 1,1’-(9,9-dioctyl-9H-fluorene-2,7-diyl)dipyrene exhibited a fluorescence quenching as a chemosensor in the presence of mesotrione, a nitroaromatic herbicide. This phenomenon proved the efficient energy and electron transfer from a photo-excited pyrene moiety to the ground state electron-deficient mesotrione as a result of Forster resonance energy transfer (FRET) mechanism.

25-31

Authors: Hung-Cuong Luu, Cuong Quoc Ngo, Ngoc Hoi Nguyen, Dieu Linh Tran, Dai Hai Nguyen, Cuu Khoa Nguyen*

Mesoporous silica nanoparticles (MSNs) have been demonstrated as a promising candidate in drug delivery applications. With the ambition of enhancing their drug loading capacity and controlled release, in this innovative study, MSNs were tailored with polyamidoamine (PAMAM) dendrimers thereby exerting advantageous properties onto the surface of the nanoplatforms. MSNs were prepared by Stöber’s method, sequentially functionalised by amine groups, and respectively grafted with PAMAMs layer-by-layer. Morphology and characterisation of the nanoparticles were carried out through transmission electron microscopy, dynamic light scattering, thermogravimetric analysis, and Fourier-transform infrared spectroscopy. Ninhydrin assay and zeta potential analysis were further employed to investigate the amine-modified nanomaterials. The drug loading and release profiles of particles were also studied. As a result, PAMAM-grafted MSNs, with the highest hydrodynamic size of 185.3 nm, exhibited high encapsulation efficiency (85.8%) and controlled release ability compared to conventional MSNs, suggesting that PAMAM-grafted MSNs would be a promising drug delivery system.

38-42

Authors: Hoang Giang Pham, Tran Thanh Son Nguyen, Thi Thuy Pham*, Manh Khai Nguyen, Bart Vander Bruggen, Thi Thanh Mai Nguyen

The presence of inorganic forms of arsenic in water causing a serious threat to human health. Exposure of arsenic can cause serious diseases such as skin discoloration, cancer of skin, kidney and lung, blood vessel diseases, high blood pressure, and reproductive disorders. Removal of arsenic to provide safe drinking water was conducted to investigate the effects of individual and combined anions (sulphate, nitrate, phosphate, and chloride ions) on the arsenate adsorption capacity of modified granular ferric hydroxide adsorbent in batch experiments. The observed adsorption data fit the Langmuir model well. The presence of sulphate (400 mg/l), nitrate (15 mg/l), and chloride (250 mg/l) ions did not significantly affect the arsenate adsorption and the maximum adsorption capacity of arsenic was reduced by less than 5%. In contrary, phosphate ions showed strong competition for the adsorption process as the maximum adsorption capacity of the material was reduced by 59.8 and 73% at concentrations of 0.2 and 0.5 mg/l, respectively. The results also showed that phosphate anions were slightly preferable than arsenate in their competitive adsorption by the adsorbent.

47-53

Authors: Minh Thi Nguyen*, Kazuhira Yokoyama, Takuya Marumoto

The establishment of the surviving arbuscular mycorrhizal (AM) fungi, Gigaspora margarita Becker & Hall, inoculated in revegetation at the Nukui Dam was studied. The population of AM fungi and AM colonization of three plant species Japanese hill cherry (Prunus jamasakura Sieb. ex Koidz, yamazakura-inoculated plant), eulalia (Miscanthus sinensis Anderss, susuki), and mugwort (Artemisia vulgaris Pampan, yomogi) were investigated to compare inoculated and non-inoculated treatments. The AM colonisation was enhanced in inoculated plots although natural or accidental AM fungi were involved in non-inoculated plots and successfully colonised. Coverage of soil surface was more than 80% and even reached nearly 100% in summer regardless of the soil amendment type.The number of spores and the percentage of colonisation of investigated plant roots, as well as the density of typical AM structures such as arbuscules, auxiliary cells, vesicles, and coiling hyphae by AM fungi in inoculated plots were higher than those in non-inoculated ones. Some spores were Gigaspora andGlomus-inoculated species and were relatively rich in inoculated plots of Yamazakura. There was a significant increase in the number of AM spores in inoculated treatments at a 5% confidence level (ANOVA, p<0.05) in Susuki and Yamazakura. Much more spores of Gigaspora sp.occurred in the rhizosphere soil of Yamazakura and Susuki plants in inoculated plots than in non-inoculated plots (2.33 and 3.73 times, respectively).The colonisation intensity and spore number in the rhizosphere were positively correlated. Therefore, inoculation at an early establishment should be important for the successive development of AM-plant symbiosis formation.

63-69

Authors: Thanh Truc Nguyen, Duc Minh Nguyen Huu, Thanh-Hai Le, Quoc-Hung Phan, Thi-Thu-Hien Pham*

Early detection of skin cancer matters because diagnosis, prognosis and treatment plan differ for each skin cancer type at their stages. Medical imaging taking the advantages of the non-invasive and non-ionizing polarized light is emerging as a tool for the development of screening and diagnotic tests. In this work, we proposed a novel framework to classify human melanoma and nonmelanoma skin cancer using the Classification and Regression Tree algorithm (CART). The samples were prepared from twenty-four non-melanoma skin cancer samples (consisting of twelve squamous cell carcinoma and twelve basal cell carcinoma samples); and three melanoma skin cancer samples. We calculated ten optical parameters from anisotropic biological tissues, namely the LB orientation angle (α), the LB phase retardance (β), the CB optical rotation angle (γ), the LD orientation angle (θd), the linear dichroism (D), the circular dichroism (R), the degrees of linear depolarization (e1 and e2), the degree of circular depolarization (e3), and the depolarization index (∆) using Stokes-Mueller matrix formalism. All effective optical parameters of biological tissue were then input into the CART classifier as predictors. The model yielded an accuracy of 92.6%, which is desirable for any robust and interpretable classification model. The results showed that for biological tissue samples, linear polarization properties dominate over circular ones due to the cellular microstructural composition of tissue, especially under anomalous growth as seen in skin cancer. This novel framework can potentially assist physicians in making timely and well-informed medical decisions.

76-80

Authors: Khanh Van Nguyen, Thi Kim Yen Pham, Thi Au Hoang, Quang Minh Luu, Doan Lan Pham*

The aim of the present study was to evaluate the effect of foetal calf serum (FCS) on the production of bovine embryo in vitro. We conducted two experiments: (1) to evaluate the effect of FCS on the production of bovine embryo in vitroand (2) to evaluate the effect of duration of FCS supplementation on the production of bovine embryo in vitro. In experiment 1, we divided mature bovine oocytes after in vitro fertilization into four embryo culture media: CR1aa, CR1aa+FCS, SOFaa, and SOFaa+FCS. Embryos cultured in CR1aa and SOFaa media supplemented with FCS resulted in a higher cleavage and blastocyst formation rates than when cultured in CR1aa and SOFaa without FCS (74.22 and 82.96% vs. 71.6 and 70.62%; 4.11 and 22.31% vs. 16.98 and 34.51%; respectively, p<0.05). The percentage of hatching blastocysts was highest when embryos were cultured in SOFaa medium supplemented with FCS (10.54%; p<0.05). Embryos cultured in the medium with FCS had a higher the average number of cells/blastocyst than the medium without FCS. The SOFaa+FCS group had a higher average number of cells/embryos than the other groups (94.32;p<0.05). In experiment 2, we added FCS to bovine embryo culture in vitro at the following times: 0 h, 48 h, and 120 h after fertilization. The rate of oocyte cleavage, blastocyst formation, and hatching blastocyst rate of the 0-h group were higher than that of 48-h and 120-h groups (82.96 vs 70.5 and 70.24%; 34.51 vs 24.21 and 23.18%; 10.5 vs 6.12 and 4.13%; respectively, p<0.05). However, there was no difference in the average number of cells/blastocysts between the groups. In conclusion, the addition of FCS to embryo culture media improved the efficiency of bovine embryo production in vitro and in vitro bovine embryo quality. The appropriate time to add FCS to bovine embryo culture in vitro was 0 h after fertilization.

89-96

Authors: Thi Trang Le*, Doan Dang Phan, Van Tien Tran, Van Tu Nguyen

This study was carried out to evaluate the seasonal variation of phytoplankton and its relationship with environmental parameters of some inland water bodies in Soc Trang province. A total of 171 phytoplankton taxa belonging to Cyanophyta (24 species), Chrysophyta (2 species), Bacillariophyta (65 species), Chlorophyta (43 species), Euglenophyta (34 species), and Dinophyta (3 species) were studied. The phytoplankton species composition during the rainy season was higher than in the dry season, in which Bacillariophyta dominated in both seasons. Surface water quality was classified into class A2 for pH, phosphate, and nitrate whereas class B2 for dissolved oxygen (DO), total suspended solids (TSS), ammonium, chemical oxygen demand (COD), and biochemical oxygen demand (BOD) (according to QCVN 08:2015/BTNMT). Canonical correspondence analysis (CCA) results revealed that environmental factors influenced the phytoplankton community. Of which the factors of pH, electric conductivity (EC), salinity, turbidity, TSS, and phosphate affected the phytoplankton assemblage in both seasons. The results confirm the potential of using phytoplankton as a bioindicator for surface water quality assessment.