Vietnam Journal of Science, Technology and Engineering

9-13

Authors: Phuong Hue Luu, Phuong Hue Tran, Hoang Van Nguyen, An Le Bao Phan, Oanh Hoang Nguyen, Man Van Tran, Phung My Loan Le, Thanh Duy Vo*

In this study, we aimed to evaluate the effect of sulfolane (SL) as a co-solvent in conventional carbonate-based electrolytes and its compatibility with a LiMn2O4 (LMO) cathode. The amount of SL was varied from 10 to 50 vol.% in an EC-DMC mixture (1:1 vol. ratio) within a 1.0-M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. The thermal properties of the electrolytes were studied using thermogravimetric analysis (TGA). Solvent flammability was measured via self-extinguishing time (SET) and ignition time indexes while viscosity was gauged by the Ostwald method. Ionic conductivity was evaluated by electrochemical impedance spectroscopy (EIS). Electrochemical techniques such as cyclic voltammetry (CV) and galvanostatic cycling with potential limitation (GCPL) were carried out to evaluate battery performance with the selected electrolytes. The results indicated that an increasing proportion of SL leads to an enhancement of the thermal and oxidation stability of the electrolytes. At 20-vol.% SL and below, the as-synthesized electrolytes exhibited a high ionic conductivity of 7.45 mS.cm-1 (25oC) and enabled LMO to deliver a specific capacity of 103 mAh.g-1 with a capacity retention of 92% after 20 cycles at C/10 rate. Due to such favourable properties, SL can be used as a co-solvent in EC-DMC systems to enhance the safety of lithium-ion batteries under high voltage conditions.

20-26

Authors: Thi Minh Thu Tran*, Thanh Binh Nguyen, Peter Winterhalter, Gerold Jerz

Opuntia stricta var. dillenii and Atriplex hortensis var. rubra, two plant species with abundant betalain and flavonoid content, were studied by high performance countercurrent chromatography (HPCCC) coupled with ESI-MS/MS in an off-line detection process. Both CCC runs used tert.-butyl-methyl-ether/n-butanol/acetonitrile/water 1% trifluoroacetic acid (v/v/v/v, 2:2:1:5) as a biphasic solvent system within an elution-extrusion mode. The resulting fractions were scanned by an off-line sequential injection to ESI-MS/MS approach. The separation of Opuntia stricta var. dillenii extract showed a partial isolation of principal betalains (betanin) from their derivatives (betanidin, phyllocactin, feruloyl-betanin, betaxanthin), degraded products (hydroxyl-neobetanin, mono decarboxy-betanins), and flavonoid glycosides (isorhamnetin-rutinoside, kaempferol-rutinoside). In case of Atriplex hortensis var. rubra, this study confirmed the coexistence of several flavonoids (quercetin-O-malonyl glucoside, kaempferol-O-malonyl glucoside) and generated few pure pigment fractions (celosianin II) for structural elucidation.

33-38

Authors: Tien Manh Hoang*, Thi Thanh Nguyen

Lung cancer is the leading cause of cancer death globally. Non-small cell lung cancer (NSCLC) constitutes more than 80% of all lung cancers, and patients with distant metastasis have much higher mortality. The survival times of NSCLC patients with metastasis have been reported in early studies, however, it remains unclear whether there are variations or patterns in survival times of patients with different metastases. Therefore, we assessed risk factors for distant metastases and the effects of different organ metastasis on overall survival (OS) in patients with NSCLC. Methods: demographics and clinical data of NSCLC patients with and without distant metastasis were collected from the Surveillance, Epidemiology, and End Result (SEER) database between 2010 and 2016. We investigated risk factors for distant metastasis patients and compared the difference in OS of NSCLC patients with different metastatic sites. Results: a total of 3849 patients diagnosed with NSCLC were screened from the SEER database with 41% (1577) of the patients having distant metastasis. During the follow-up period, 3221 (83.7%) patients died and, of all the deceased patients, 2935 (88.4%) died of lung cancer while only 286 (11.6%) died from other diseases or causes. The occurrence of distant metastasis was closely related to the patient’s age, primary tumour site, tumour grade, T stage, N stage, surgery of primary site, radiation therapy, and chemotherapy (p<0.05). Compared to patients without metastasis, whose median OS was 13 months, the median OS of patients with metastasis was 6 months (lung), 5 months (liver), 5 months (bone), 4 months (brain), and 3 months (multiple organs). Conclusions: distant metastasis indicates a poor prognosis in NSCLC patients. There were significant differences in the prognosis of different metastatic sites and the order of their OS from high to low was: no metastasis > lung metastasis, liver metastasis, bone metastasis > brain metastasis, multiple organ metastasis

43-48

Authors: Hai Trieu Ly, Vu Khanh Trang Le, Van Minh Le, Cong Sanh Phan, Chau Tuan Vo, Minh Ly Nguyen, Thi Anh Dao Phan*

This study screened phytochemicals to determine their total polyphenols content (TPC) by Folin-Ciocalteu reagents and to evaluate antioxidant activity using DPPH scavenging, ABTS cation decolorization, and reducing power assays of various extracts of Symplocos cochinchinensis leaves. A correlation between TPC and antioxidant activity was analysed by Pearson’s method. The results indicated that S. cochinchinensisleaves contained triterpenoids, alkaloids, anthraglycosides, flavonoids, anthocyanosides, proanthocyanidins, polyphenols, tannins, saponins, polyuronics, and reducing agents. All extracts had antioxidant properties with the ethyl acetate fraction exhibiting the highest antioxidant capacity, which had the lowest IC50 in DPPH (83.33 μg/ml), an ABTS of 46.21 μg/ml, and EC50 of 69.10 μg/ml in reducing power. There was a significant negative correlation between the TPC in S. cochinchinensis leaf extracts and their IC50 and EC50 values of antioxidant activity. It was suggested that S. cochinchinensis leaves have a great potential for antioxidant activity based on its high total polyphenol content and potential for use as a traditional treatment

53-62

Authors: Thai Phuong Thao Nguyen, Phuong Hien Le, Thi-Hiep Nguyen*

Xanthan gum (XG) is recognised as one of the most popular natural polymers extensively used today due to its biode-gradable and biocompatible properties, and, therefore, XG can be used to produce hydrogels with other polymers to expand its uses. However, at present, there has not been much research on preparing injectable hydrogels from XG. Moreover, up to now, there are only a limited number of review articles related to this topic. This review will provide a well-organised and somewhat extensive presentation of previous studies that have been executed on injectable hydrogels from XG. Also, applications have been using XG to fabricate injectable hydrogels such as cartilage tissue engineering, bone tissue engineering, delivery system, and bioink will be reviewed.

72-77

Authors: Yen-Nhi Ha Nguyen, Long Binh Vong, Hong-Anh Pham, Dang-Quan Nguyen, Phan Ngoc Uyen Phuong, Huu-Phuong Mai, Nhu-Thuy Trinh*

Type 2 diabetic patients have an increased risk of developing serious long-term complications such as cardiovascular disease, retinopathy, nephropathy, neuropathy, diabetic foot, and osteoporosis. However, the correlation between hyperglycaemia and osteoporosis has not yet been fully clarified. In this research, we investigated the effect of different high D-glucose concentrations (25, 50, and 100 mM) on osteogenic differentiation of human non-diabetic and diabetic adipose tissue-derived mesenchymal stem cells (nAT-MSCs and dAT-MSCs). The differentiated cells were qualified by Alizarin Red S staining and quantified by measuring the absorbance at 482 nm. The expressions of osteogenic master genes were examined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) methods. Interestingly, the osteogenic differentiation and the expression of osteogenic-specific genes (Runx-2 and ALP) decreased with an increase of D-glucose concentration. Our work contributes to the understanding of the relationship between hyperglycaemia and osteoporosis and support the role of stem cells in developing new medicine or therapeutic treatment for preventing diabetic complications

85-89

Authors: Huy Toan Do*, Thanh Binh Nguyen, Tuan Minh Ly

Tidal energy is a renewable energy source produced by the rise and fall of ocean tides. Tidal energy can be exploited using a special type of generator that converts tidal energy into electricity. Tidal power generation has the potential to open up many prospects for energy field and minimize carbon dioxide emissions that cause the greenhouse effect. To evaluate the possibility of tidal power, it is necessary to have documents and data on average annual tidal amplitude, tidal regime, and main tidal waves in the study area. To calculate the tidal power potential for the east coast of Vietnam, this article applies the calculation formula of tidal power energy by Russian scientist L.B. Bernstein. The annual mean tidal amplitude and the K1, O1, and M2 wave amplitude data at nearly 2000 calculation points along the coast of Vietnam were extracted from the TPOX8-Atlas harmonic constant set. Research results showed that Vietnam has great potential for tidal energy along the Hai Phong - Quang Ninh coastal area and the southeast region with a prospective 41.6 GWh/km2/y.