https://jst.vn/index.php/etsd Journal of Science and Technology - Technical Universities Hanoi University of Science and Technology en-US JST: Engineering And Technology For Sustainable Development 2734-9381 https://jst.vn/index.php/etsd/article/view/409 Titanium dioxide (TiO2) particles were synthesized by the sol-gel method (SG) and sol-gel low-temperature method (SG-L), utilizing titanium isopropoxide as the precursor. Subsequently, the particles underwent heat treatment with sodium hydroxide 10M, resulting in samples denoted as SG-H and SG-L-H samples, respectively. The purpose of this study is to compare these synthesis methods in terms of the stability and photocatalytic activity of TiO2 catalysts. To determine the optimal synthesis method for generating highly active TiO2, the obtained catalyst samples were characterized by a variety of techniques, including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and UV–vis spectroscopy measurements. The results demonstrated that the structure and phase of catalysts depend on the synthesis conditions. The surface area measurements indicated values of 0.95, 18.95, 82.65, and 168.59 m2/g for SG, SG-H, SG-L, and SG-L-H, respectively. Furthermore, the degradation efficiency of methylene blue under xenon lamp illumination was recorded at 87%, 91%, 97%, and 94% after 150 minutes, according to a pseudo-first-order reaction. These results suggest that the sol-gel low-temperature method is particularly effective in producing high purity, large specific surface area, and good decomposition of organic dye. Quynh Vi Nguyen Ngoc Duong Dinh Thanh Hung Nguyen Minh Thu Truong Minh Thang Le Ngoc Mai Nguyen Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development 35 2 1 8 10.51316/jst.181.etsd.2025.35.2.1 https://jst.vn/index.php/etsd/article/view/410 Glycyrrhiza glabra L. has a long-standing history in traditional medicine across both Eastern and Western areas. The plant's chemical constituents, such as glycyrrhizin, glycyrrhetic acid, and various flavonoids, offer significant therapeutic potential. Further research could explore its application in modern drug development for the treatment of systemic and non-systemic diseases. In the course of study on the chemical composition of Glycyrrhiza glabra L. in Vietnam, this paper described the extraction and structure evaluation of four compounds, including glabridin (1); 4'-O-methylglabridin (2); glabrol (3); kanzonol Y (4) as well as the melanin inhibition activity of these compounds. The stems of this plant were collected, identified, dried and extracted in different polarity solvents. These substances were isolated from the ethyl acetate extract on the basis of column chromatography combined with thin layer chromatography. Their structures were identified based on spectroscopic evaluation and comparison of corresponding authentic compounds. Thi Viet Thanh Nguyen Tran Nhu Hoang Minh Anh Tran Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development 35 2 9 17 10.51316/jst.181.etsd.2025.35.2.2 https://jst.vn/index.php/etsd/article/view/411 The combination of sulfamethoxazole (SMX) and trimethoprim (TMP) with a ratio of 5:1 is widely used in treating outpatient diseases against various gram-positive and negative bacteria as well as mycobacteria, parasites, and fungi. Monitoring these compounds in plasma is challenging due to the coexistence of complicated matrices. This study aimed to develop and validate the HPLC-DAD method combined with liquid-liquid extraction followed by an additional clean-up for the simultaneous determination of TMP and SMX in human plasma. The plasma sample was precipitated using the crashing solvent 1% acid formic in acetonitrile and then impurities were removed by a C18 sorbent (m = 100 mg). Two analytes were separated on a Hypersil Gold C8 column (100 mm × 2.1 mm i.d.; 3 µm particle size) under isocratic elution with 0.3% formic acid in water and methanol (80/20, v/v). A washing column with 100% MeOH was employed for 5 minutes after each injection to eliminate any potential impurities retained in the analytical column. The flow rate and the column temperature were constantly set up at 0.4 mL·min⁻¹ and 40 °C respectively. The maximum absorbance wavelengths were set 241 nm for TMP and 279 nm for SMX to achieve the highest selectivity and sensitivity. The method shows high recovery at 80.4% and 82.6% for TMP and SMX, respectively. The limit of quantification (LOQ) in plasma was 11.8 µg/L for TMP and 28.0 µg/L for SMX and intra- and inter-day precisions were less than 15% for both analytes. This validated method could be applied to pharmacokinetic studies in treatments. Van Hoi Bui Cam Tu Vu Ngoc Phuong Linh Phung Thi Thu Nguyen Thi Quynh Mai Duong Dinh Binh Chu Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development 35 2 18 25 10.51316/jst.181.etsd.2025.35.2.3 https://jst.vn/index.php/etsd/article/view/412 Pakchoi (Brassica rapa subsp. chinensis) is a familiar vegetable and is widely grown in Vietnam and many other Southeast Asian countries. Like other Brassica plants, Pakchoi has long been known for its ability to accumulate a variety of metals. Using the metal content data in the edible part of Pakchoi from Chuong My, Me Linh, and Dan Phuong (3 areas specializing in growing Pakchoi serving Hanoi market) during the period from September 2021 to April 2024, this study evaluated the ability to authenticate the origin of Pakchoi using the PCA and LDA methods. 27 kinds of metal in the edible parts of Pakchoi from these areas, including Li, Bo, Mg, Al, Ti, V, Cr, Mn, Zn, Fe, Co, Ni, Cu, As, Rb, Sr, Nb, Mo, Ag, Cd, Sb, Cs, Ba, Hg, Tl, Pb, and Bi, were determined by ICP-MS. Multivariate Statistical Analysis methods (Principal component analysis-PCA and Linear Discriminant Analysis-LDA) were used and LDA method was successful in distinguishing the three geographical areas. Of the total 27 metals, the characteristic metals used for distinction in LDA were shown, including: As, Ba, Co, Cs, Li. In addition, the model constructed by LDA showed the ability to accurately recognize 27/27 prepared prediction samples. This research shows the potential of using metal content results in building a model to authenticate the geographical origin of Pakchoi in particular and other vegetable crops in general in the food market in the Hanoi, Vietnam. The Vinh Mac Ngoc Minh Truong Thi Huong Nguyen Thi Minh Tu Nguyen Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development 35 2 26 32 10.51316/jst.181.etsd.2025.35.2.4 https://jst.vn/index.php/etsd/article/view/413 Identifying energy consumption trends is difficult as the food processing industry is very fragmented, products are processed to varying degrees, and production is not always continuous. This study has collated data better to understand energy consumption across different food processing sectors. Based on energy consumption data, GHG emissions are calculated for direct emissions from fuel usage and indirect emissions from the use of grid-supplied electricity. Energy figures show that electricity, LPG, and coal are the main energy sources used in the food industry in the big cities of Ho Chi Minh City (HCMC), Hanoi, and Hai Phong. Patterns of energy sources are different from city to city depending on the composition of subsectors and the availability of local energy resources. GHG emissions from the food industry in HCM are estimated to be 22,014,696 tons of CO2-eq, with 98% of these emissions coming from indirect sources. The figures for Hanoi and Hai Phong are 493,000 and 36,016 tons of CO2-eq, respectively, with 29% and 49% indirect emissions. The most GHG emission-intensive food industry sub-sector in HCMC includes processing and preservation of meat products and processing and preservation of frozen seafood; in Hanoi, it is processing milk and dairy products, and in Hai Phong, it is seafood products processing and preservation and production of beer and malt. The study proposed three energy-saving solutions in food processing plants that can be considered: Optimizing the use of existing equipment in production, Innovating and upgrading equipment, and Investing in low-carbon energy sources. Dieu Anh Van Bich Thuy Ly Thi Thu Huong Hoang Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development 35 2 33 39 10.51316/jst.181.etsd.2025.35.2.5 https://jst.vn/index.php/etsd/article/view/414 Self-healing vulcanized natural rubber (S-H V-NR) was prepared with MgO/ZnO as a binary activator system in this study. Standard Vietnam Rubber graded 3L (SVR3L) was used as NR source. The SVR3L was vulcanized with different activators of ZnO, MgO/ZnO, or MgO and other vulcanizing reagents. The total amount of activators were 5 parts per hundred rubber (phr); in which the MgO/ZnO binary activator system was compounded with the SVR3L at a 3:2 ratio of MgO to ZnO amount. Furthermore, sulfur amount was either 1.0 or 1.5 phr. V-NR underwent S-H process at S-H temperatures of 25, 50, or 100 °C for S-H times of either 12 or 24 h. The cure characteristics of the NR compounds were measured to examine optimal vulcanization time (t90) and maximum torque (MH). Raman spectroscopy was used to evaluate relative ratio of disulfide and polysulfide bonds. Self-healability was assessed by determining the stress and strain at break of S-H V-NR before and after S-H process. The results showed that the use of the MgO/ZnO as binary activator system and MgO as activator to replace ZnO shortened the t90. V-NR prepared with MgO activator had the best self-healability among all V-NR since the disulfide bonds were dominantly formed over polysulfide bonds when the MgO activator was used, based on the results of Raman measurements for V-NR. Meanwhile, the self-healability of V-NR prepared with the MgO activator at high temperature did not depend on the S-H time. Thi Thuong Nghiem Minh Tho Le Viet Hung Dang Trung Nghia Phan Van Hai Pham Ba Lam Nguyen Seiichi Kawahara Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development 35 2 40 48 10.51316/jst.181.etsd.2025.35.2.6 https://jst.vn/index.php/etsd/article/view/415 The mechanical properties of Compositionally graded nanocrystalline materials (CGNMs) are studied via molecular dynamics simulation. Similarly to metal and alloys, these materials' grain size significantly affects their mechanical properties. However, achieving a complete understanding of the mechanical behavior of CGNMs with different grain sizes, particularly at the atomic level, has remained indefinable. This article uses molecular dynamics (MD) simulations to investigate the tensile mechanical properties of CuNi CGNMs with varying grain sizes. The CGNMs exhibit a dual dependence on grain sizes. The findings demonstrate that the yielding stress of CGNMs increases with a decrease in the grain sizes. Research shows that the critical value of the average grain diameter available to transform the positive Hall-Petch relationship to inverse one is dc equals 11.09 nm, at this size, the yield strength (YS) is 2.7 GPa and is the largest value in the samples. This is explained when the average grain diameter has not reached the critical value, the dislocations moving during plastic deformation will be accumulated at grain boundaries to form dislocation clusters (or walls) that prevent the further movement of other dislocations, and at the same time create a dislocation stress field around the grain boundaries, causing the materials strengthening. The yield stress decreases if the average grain diameter is smaller than 11.09 nm. When the grain size is smaller than the critical value, the grain volume is too small to contain enough dislocations. Therefore, they glide across the boundary very quickly, decreasing the YS of the material, which means materials softening due to rotation or gliding of grain boundaries. This change in yield stress is consistent with the inverse Hall-Petch relationship. These conclusions have positive significance for the design of these compositionally graded nanocrystalline CuNi. Thi Hong Hue Dang Minh Quan Doan Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development 35 2 49 57 10.51316/jst.181.etsd.2025.35.2.7 https://jst.vn/index.php/etsd/article/view/416 Shaped knitted clothes such as sweaters and cardigans are popular and abundant textile products but in the fast fashion trend, their normal life cycle is usually short, about 28 laundry cycles. Therefore, recycling used shaped knitted clothes is of interest to many designers all over the world for a more sustainable environment and development. Sweaters and cardigans are often produced by shaped knitting method. So, an effective recycling process is unravelling continuous yarn from the used clothes to get input for knitting of recycled items. In this way, the longer the length of yarn collected the better, and managing the length of recovered yarn in stock is very important for designers. This study investigated the influence of product construction and knitted structure on the length of continuous yarn unravelling from used shaped knitted clothes. In addition, a method to estimate the pattern area designed from collected yarn was proposed basing on specifications recommended by SDS-One Apex Design system of Shima seiki. Thi Chinh Thuy Dao Khanh Trang Le Thi Thuy Vu Thi Thanh Thao Nguyen Thi Phuong Anh Tong Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development 35 2 58 64 10.51316/jst.181.etsd.2025.35.2.8