https://scholar.dlu.edu.vn/handle/123456789/517 Mon, 20 Jul 2026 01:37:37 GMT 2026-07-20T01:37:37Z https://scholar.dlu.edu.vn/handle/123456789/6839 Title: Tối ưu thông số vận hành cho hệ chưng cất màng trực tiếp (DCMD) trong quá trình xử lý nước biển Authors: Nguyễn, Công Nguyên; Phạm, Hầu Thanh Việt; Nguyễn, Thị Hậu; Nguyễn Thị Mỹ Lệ; Trương, Đông Phương; Lê, Vũ Trâm Anh; Nguyễn, Thị Tố Uyên Abstract: Climate change is intensifying saltwater intrusion and freshwater scarcity in many regions, creating an urgent need for effective, sustainable desalination solutions. In this context, membrane distillation (MD) is regarded as a highly promising option for producing high-quality water at low cost by utilizing solar energy and waste heat. However, key challenges remain in selecting suitable MD membranes and establishing optimal operating parameters to simultaneously achieve high flux and stable salt rejection. Therefore, this study systematically investigates a direct contact membrane distillation (DCMD) system using a PVDF-MD membrane fabricated with isoamyl alcohol as the solvent, evaluating the effects of temperature difference, cross-flow velocity, feed salinity, and operating time. The results indicate optimal conditions of 70 °C (hot/feed) and 25 °C (cold/permeate) with a cross-flow velocity of 0.33 m/s, delivering a permeate flux of 20.5 LMH and salt rejection >99.9% while mitigating pore wetting. The membrane also operated stably with a high concentration of brine and, after 30 days of continuous treatment of real seawater, produced distillate meeting drinking-water standards. Thu, 01 Jan 2026 00:00:00 GMT https://scholar.dlu.edu.vn/handle/123456789/6839 2026-01-01T00:00:00Z https://scholar.dlu.edu.vn/handle/123456789/6702 Title: Simultaneous HPLC quantification of epicatechin and epigallocatechin gallate in the leaves of Camellia species cultivated in Lam Dong Authors: Trịnh, Thị Điệp; Trần, Thị Kim Ngân; Phùng, Văn Trung Abstract: The genus Camellia is highly diverse in Vietnam, yet the phytochemical profiles of many native species remain largely unexplored. This study aimed to develop an analytical method to quantify two important bioactive catechins, epicatechin (EC) and epigallocatechin gallate (EGCG), in the leaves of 23 Camellia species. A high-performance liquid chromatography (HPLC) method was successfully developed and validated according to International Council of Harmonisation guidelines. The analysis revealed significant variations in the content of these two compounds among the species, with 15 of 23 samples found to contain EC and/or EGCG. The EC content ranged from 0.10 to 14.07 mg/g dry weight (dw), with Camellia thuongiana exhibiting the highest concentration. The EGCG content ranged from 0.03 to 4.03 mg/g dw, with Camellia hacodae having the highest level. The study identified promising Camellia species such as C. thuongiana, C. hacodae, and C. puhoatansis as rich sources of these valuable catechins. These data provide an important scientific basis for screening, conservation, and guiding the sustainable development of native Camellia resources in Lam Dong for applications in the pharmaceutical and nutraceutical industries. Mon, 01 Jun 2026 00:00:00 GMT https://scholar.dlu.edu.vn/handle/123456789/6702 2026-06-01T00:00:00Z https://scholar.dlu.edu.vn/handle/123456789/6701 Title: Fatty oil composition of Camellia cattienensis seeds collected in Lam Dong province, Vietnam Authors: Trịnh, Thị Điệp; Nguyễn, Thị Tố Uyên; Huỳnh Thị Kim Ngân Abstract: For the first time, oil was extracted from the seeds of Camellia cattienensis Orel. Its composition was studied using gas chromatography-mass spectrometry (GC-MS). The oil content of the seed kernel was found to be 0.89% of its dry weight. GC-MS analysis revealed that fatty acids were the predominant compound group, representing 55.55% of the total sample weight. Oleic acid (19.96%), linoleic acid (16.55%), and palmitic acid (16.09%) were identified as the major constituents. In addition, squalene (11.97%), sterols, aliphatic hydrocarbons, alcohols, and esters were detected. A high proportion of compounds (12.39%) were tentatively identified as glycidyl derivatives. The high proportion of unsaturated fatty acids and bioactive compounds such as squalene and sterols suggests that C. cattienensis seed oil may have promising applications in the cosmetic and pharmaceutical industries. However, further studies are mandatory to confirm the identity, rule out artifact formation, and assess the toxicological implications of the potentially toxic glycidyl derivatives. Mon, 01 Jun 2026 00:00:00 GMT https://scholar.dlu.edu.vn/handle/123456789/6701 2026-06-01T00:00:00Z https://scholar.dlu.edu.vn/handle/123456789/6688 Title: A plumbagin-based UV–Vis spectrophotometric method for lanthanum(III) determination in fertilizer samples: complexation, validation, and practical applicability Authors: Do Tam Nhan; Le Van Tan; Lê, Thị Thanh Trân; Nguyen Viet Duc; Pham Van Tat Abstract: The complexation of lanthanum(III) with plumbagin (PLB) was investigated and applied to the development of a UV–Vis spectrophotometric method for La(III) determination in inorganic fertilizer samples. The La(III)–PLB system exhibited a characteristic absorbance response in the 300–320 nm region, while Job’s plot and mole-ratio analyses supported an apparent 1:3 La stoichiometry under the selected experimental conditions. The apparent conditional formation constant was estimated as logβ3,app ≈ 13.7. Under optimized conditions, the proposed method showed good linearity over the concentration range of 7.19 × 10–6–3.24 × 10–4 M, following the regression equation A = 631.0644C + 0.0228 (R2 = 0.9995). The limits of detection and quantification were 1.73 × 10–6 and 5.25 × 10–6 M, respectively. The method was successfully applied to inorganic fertilizer samples, providing results comparable to those obtained by ICP-MS. Complementary spectroscopic analyses supported the formation of a La-containing PLB coordination system consistent with an apparent 1:3 coordination model. This work presents a simple, low-cost, and practically accessible UV–Vis approach for La(III) determination in selected fertilizer matrices. Wed, 24 Jun 2026 00:00:00 GMT https://scholar.dlu.edu.vn/handle/123456789/6688 2026-06-24T00:00:00Z