https://dthujs.vn/index.php/dthujs Tạp chí Khoa học Đại học Đồng Tháp vi-VN Fri, 13 Dec 2024 09:38:46 +0000 OJS 3.2.1.1 http://blogs.law.harvard.edu/tech/rss 60 https://dthujs.vn/index.php/dthujs/article/view/1721 In this investigation, the total polyphenol content (TPC) and total flavonoid content (TFC) of E. bulbosa bulbs were quantified using the Folin–Ciocalteu and aluminum chloride methods, respectively. The antioxidant capacity was evaluated using DPPH and ABTS radical scavenging assays. Additionally, the antibacterial and antifungal activities of fractionated extracts from E. bulbosa bulbs were assessed. Results showed that the TPC and TFC in the crude ethanol extracts of E. bulbosa bulbs were 93.51 ± 0.60 mg GAE/g and 32.25 ± 0.25 mg QE/g extract, respectively. The antioxidant activity of the ethyl acetate extract from E. bulbosa bulbs exhibited significant potency, with IC50 values of 103.49 µg/mL and 141.25 µg/mL for the DPPH and ABTS assays, respectively. The ethyl acetate extract demonstrated the highest antibacterial activity against A. hydrophila, with the largest zone of inhibition measuring 26.51 ± 0.15 mm. It also indicated a potent antifungal effect of E. bulbosa bulb extracts, with 96.8% inhibition against B. dothidea at 312.5 µg/mL and a MIC value of 10,000 µg/mL. Therefore, the development of innovative food and pharmaceutical products derived from the bulbs of E. bulbosa is of considerable interest. Le Thi Bach, Pham Thi Kim Phuong, Le Thi Thanh Xuan, Ho Thi Kieu Trinh, Le Thi To Nhu, Nguyen Tien Phong, Ngo Loc Ngu, Huynh Tran Bao Tran Copyright (c) 2024 Tạp chí Khoa học Đại học Đồng Tháp https://creativecommons.org/licenses/by-nc/4.0 https://dthujs.vn/index.php/dthujs/article/view/1721 https://dthujs.vn/index.php/dthujs/article/view/1711 In this work, we first present a new class of generalized differentials, namely subdifferentials with degrees of freedom as well as their applications in nonsmooth optimization problems. We then establish some computation rules for subdifferentials with degree of frecdom of functions under basic qualification constraints. By using these computation rules, we provide necessary and sufficient conditions for unconstraint optmization problems and for optimization problems with geometric constraints. Vo Duc Thinh, Huynh Ngoc Cam Copyright (c) 2024 Tạp chí Khoa học Đại học Đồng Tháp https://creativecommons.org/licenses/by-nc/4.0 https://dthujs.vn/index.php/dthujs/article/view/1711 https://dthujs.vn/index.php/dthujs/article/view/1847 Carbon dots (CDs), also known as C-dots, are microscopic carbon nanoparticles with dimensions less than ten nanometers. These particles possess numerous distinctive characteristics and have witnessed a growing use across diverse domains in recent times. In this report, CD was synthesized from various sources of organic waste peels (pomelo, dragon fruit, passion fruit, pineapple, mung bean, watermelon, and carrot), focusing on the hydrothermal method. The main target is to find appropriate biomass materials for the production of cost-effective, eco-friendly, and non-hazardous CDs. The morphology, crystal structure, optical and luminescent properties were investigated and evaluated for perspective applications in biomedical issues, optoelectronics, catalysis, anticounterfeiting and sensors. Pham Hoang Phuc, Nguyen Kim Khanh, Huynh Thanh Thuy, Pham Thi Kim Hang, Ngo Hai Dang Copyright (c) 2024 Tạp chí Khoa học Đại học Đồng Tháp https://creativecommons.org/licenses/by-nc/4.0 https://dthujs.vn/index.php/dthujs/article/view/1847 https://dthujs.vn/index.php/dthujs/article/view/1741 The hierarchical nanoporous structure is often described as a corrosion-derived, bi-continuous porous network of interconnected ligaments. Nanoporous metallic materials have attracted much interest as they hold great potential for advanced applications in various areas. In this study, nanoporous Au-Ag thin films were formed on the n-doped Si (110) wafers, using magnetron sputtering deposition and subsequent electrochemical etching in HF solution. The etched Au0.12Ag0.23Si0.65 film had a highly rough surface, including ligaments in sizes of 30-40 nm and small pore channels with cross sizes of 10-30 nm on SEM analysis. AES depth profiling data showed that Ag atoms tended to distribute more on the surface than underlying regions after the dealloying process. The thicknesses of films before and after etching were approximately 150 nm and 100 nm, respectively. The nanoporous film exhibited a significant current response toward the electrochemical oxidation of phenol at 0.7 V. The results indicate that the as-fabricated nanoporous Au-Ag structure with the mentioned characteristics can be studied further for potential applications in chemical and biochemical areas. Bui Thi Phuong Quynh Copyright (c) 2024 Tạp chí Khoa học Đại học Đồng Tháp https://creativecommons.org/licenses/by-nc/4.0 https://dthujs.vn/index.php/dthujs/article/view/1741