Some Results of Recent Investigation and Application of Rubber Blends in Vietnam

Bui Chuong,Nguyen Thanh Liem,Dang Viet Hung,Nguyen Huy Tung,Nguyen Pham Duy Linh,Nguyen Thanh Nhan,Pham Ngoc Linh,Le Anh Kien,Chu Chien Huu 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1

We have investigated the change of tensile strength (TS) of Natural rubber/chloroprene rubber (NR/CR) blends during combination ageing, including heating and dynamic mechanical loading. Using model of statistical experiment, we built the equation describing the dependence of TS on four factors: temperature T, number of cyclic loadings N, contents of NR (C_NR) and chloroprene (CCR). This equation allows predict the TS change of NR/CR blends after combination ageing with accepted inaccuracy – less than 10%. We also investigated the effect of nanofillers, such as nanoclay, SiO2, Fe₃O4, on adhesion of some rubber blends to polyester and steel cords. It was found, in the case of EPDM/CIIR rubber blends, both nanoclay and SiO2 have no effect on adhesion to steel cords, while nano SiO2 may enhance adhesion to polyester cords. On other side, Fe₃O4 may remarkably enhance adhesion of NR/CR blends to steel. Mentioned results are successfully applied in some practical rubber products working under fatigue conditions, such as rubber/steel antivibration pad for locomotive, heat resistant conveyor, water dam, underwater lift bag.

Safety assessment of an underground tunnel subjected to missile impact using numerical simulations

Duc-Kien Thai,Duy-Liem Nguyen,Thanh-Tung Pham,Thai-Hoan Pham 사단법인 한국계산역학회 2021 Computers and Concrete, An International Journal Vol.27 No.1

This work presents a safety assessment of an underground tunnel subjected to a ballistic missile attack employing the numerical approach. For the impact simulation, a box shaped reinforced concrete (RC) structure with a cross section dimension of 8.0×10.0 m under a soil layer that was attacked by a SCUD missile was modeled using finite element (FE) software LS-DYNA. SCUD missile is one of a series of tactical ballistic missiles developed by Soviet Union during the Cold War, which is adopted for a short-range ballistic missile. The developed FE simulation for the penetration depth of the missile impacting into the soil structure was verified from the well-known formula of the penetration prediction. The soil-structure interaction, the soil type, and the impact missile velocity effects on the penetration depth of the missile into the different soil types were investigated. The safety assessment of the underground tunnel was performed with regard to the different depths of the underground tunnel. For each missile velocity and soil type, a specific depth called the unsafe depth was obtained from the analysis results. The structure beneath the soil beyond this depth remains safe. The unsafe depth was found to be increased with the increasing missile velocity.

The role of rapid tissue expansion in separating xipho-omphalopagus conjoined twins in Vietnam

Tran, Thiet Son,Pham, Thi Viet Dung,Ta, Thi Hong Thuy,Vu, Duy Kien,Nguyen, Thanh Liem Korean Society of Plastic and Reconstructive Surge 2021 Archives of Plastic Surgery Vol.48 No.4

Conjoined twins are rare, and each set of conjoined twins has a unique conjoined anatomy. It is necessary to perform separation to increase the chance of patient survival. Tissue expansion is an advanced technique for providing sufficient soft tissue and skin for wound closure. We report the successful application of rapid tissue expansion in 10-month-old xipho-omphalopagus conjoined twins in Vietnam. A tissue expander was placed on the anterior body between the sternum and umbilicus with a baseline of 70 mL sterile saline (0.9% NaCl). The first injection into the tissue expander began on the 6th day after expander insertion, and injections continued every 2 days with approximately 30-70 mL per injection according to the expansion of the skin. The expander reached 335 mL after six injections and within 10 days. In order to prepare for surgical separation, expansion was completed on the 15th day after insertion. The expanded skin area was estimated to be 180 cm², which was sufficient to cover both patients' skin deficiencies. The twins presented for surgical separation 6 days following the completion of tissue expansion. Both babies were discharged in good health 1 month after separation.

Polyphenol Contents, Gas Chromatography-Mass Spectrometry (GC–MS) and Antibacterial Activity of Methanol Extract and Fractions of Sonneratia Caseolaris Fruits from Ben Tre Province in Vietnam

Tran Thien khanh,Ha Pham Thi Thu,Henry Robert. J.,Nguyen Dang Nguyen Thao,Tuyen Phung Thi,Liem Nguyen Thanh 한국미생물·생명공학회 2024 Journal of microbiology and biotechnology Vol.34 No.1

Plants contain a large number of phytochemical components, many of which are known as bioactive compounds and responsible for the expression of various pharmacological activities. The extract of Sonneratia caseolaris fruit collected in Vietnam was investigated for its total phenolic and total flavonoid contents using methanol solvent and different fractions of S. caseolaris fruits (hexane, ethyl acetate, n-butanol, and aqueous). GC–MS analysis was conducted to identify the bioactive chemical constituents occurring in the active extract. Further, the antibacterial activity was tested in vitro on bacterial isolates, namely Escherichia coli, Staphylococcus aureus, and Bacillus subtilis, using the disc diffusion method on tryptic soya agar (TSA) medium. The methanol extract showed high total flavonoid (82.3 ± 0.41 mg QE/g extract) and phenolic (41.0 ± 0.34 mg GAE/g extract) content. GC–MS of the methanol extract and different fractions of S. caseolaris fruits detected 20 compounds, principally fatty alcohols, fatty acids, phenols, lipids, terpenes derivatives, and carboxylic acids derivatives. A 50 mg/ml concentration of methanol extract had the strongest antibacterial activity on E. coli, S. aureus, and B. subtilis. Furthermore, ethyl acetate, aqueous, and n-butanol fractions inhibited S. aureus and B. subtilis the most. The results of the present study suggested that the fruits of S. caseolaris are rich sources of phenolic compounds that can contribute to safe and cost-effective treatments.

BONEcheck: A digital tool for personalized bone health assessment

Dinh Tan Nguyen,Thao P. Ho-Le,Liem Pham,Vinh P. Ho-Van,Tien Dat Hoang,Thach S. Tran,Steve Frost,Tuan V. Nguyen 대한골다공증학회 2023 Osteoporosis and Sarcopenia Vol.9 No.3

Objectives: Osteoporotic fracture is a significant public health burden associated with increased mortality risk and substantial healthcare costs. Accurate and early identification of high-risk individuals and mitigation of their risks is a core part of the treatment and prevention of fractures. Here we introduce a digital tool called 'BONEcheck' for personalized assessment of bone health. Methods: The development of BONEcheck primarily utilized data from the prospective population-based Dubbo Osteoporosis Epidemiology Study and the Danish Nationwide Registry. BONEcheck has 3 modules: input data, risk estimates, and risk context. Input variables include age, gender, prior fracture, fall incidence, bone mineral density (BMD), comorbidities, and genetic variants associated with BMD. Results: Based on the input variables, BONEcheck estimates the probability of any fragility fracture and hip fracture within 5 years, subsequent fracture risk, skeletal age, and time to reach osteoporosis. The probability of fracture is shown in both numeric and human icon array formats. The risk is also contextualized within the framework of treatment and management options on Australian guidelines, with consideration given to the potential fracture risk reduction and survival benefits. Skeletal age was estimated as the sum of chronological age and years of life lost due to a fracture or exposure to risk factors that elevate mortality risk. Conclusions: BONEcheck is an innovative tool that empowers doctors and patients to engage in wellinformed discussions and make decisions based on the patient's risk profile. Public access to BONEcheck is available via https://bonecheck.org and in Apple Store (iOS) and Google Play (Android).

Citrus diaspidids in Viet Nam: New, and confirmation of previous, records based on morphological and molecular verification of taxa

Hang T. Dao,George A.C. Beattie,Gillian W. Watson,Van Lam Pham,Van Liem Nguyen,Duc Khanh Le,Thi Hoa Nguyen,Viet Nguyen,Paul Holford 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.1

Armoured scales (Hemiptera: Diaspididae) belong to the largest scale insect family and are among the mostinvasive insects in the world. Accurate identification of armoured scales is essential for systematic and phylogeneticstudies; biogeography; trade and plant quarantine; and pest management, particularly biological control. Several species are serious pests of citrus. Records of past field surveys conducted in Viet Nam between 1967 and2010 indicated the presence of 28 species on citrus there. Discrepancies in these records, and the retention ofspecimens of only five species in collections, led us to undertake surveys throughout the citrus-growing regionsof the country in 2013 and 2014 to verify previous records and conserve voucher specimens. The presence of 21diaspidid species was confirmed based on morphological and molecular data. The species observed werecommon but rarely abundant. Populations in commercial orchards may have been influenced by use of pesticides,but most species were recorded also in gardens and orchards where pesticide use was uncommon. Naturalenemies were abundant, but were not thoroughly documented for all the diaspidids we observed. An identificationkey to the species collected is provided. Differences between our findings and previous records from VietNam, from Yunnan and Guangxi in China, and from Indochinese countries neighbouring Viet Nam, indicate theneed for extensive surveys to fully document the diaspidid fauna on citrus in the region.