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Publication

A molecular docking simulation study on potent inhibitors against Rhizoctonia solani and Magnaporthe oryzae in rice: silver-tetrylene and bis-silver-tetrylene complexes vs. validamycin and tricyclazole pesticides

( 2020)

Bui Thi Phuong Thuy

;

Tran Thi Ai My

;

Nguyen Thi Thanh Hai

;

Huynh Thi Phuong Loan

;

Le Trung Hieu

;

Tran Thai Hoa

;

Thanh Q. Bui

;

Ho Nhat Tuong

;

Nguyen Thi Thu Thuy

;

Doan Kim Dung

;

Pham Van Tat

;

Phan Tu Quy

;

Nguyen Thi Ai Nhung

Rice, well known as the most important staple food source worldwide, is highly susceptible to many infectious diseases, especially rice sheath blight caused by fungus Rhizoctonia solani and rice blast caused by fungus Magnaporthe oryzae. The inhibitory ability of silver- and bis-silver-tetrylene complexes, including Ag-E and bis-Ag-E with E = C, Si, Ge, onto protein 4G9M in Rhizoctonia solani and protein 6JBR in Magnaporthe oryzae was theoretically investigated using molecular docking simulation methodology. Two commercial pesticides selected as inhibitory references are validamycin for 4G9M and tricyclazole for 6JBR. The results reveal that bis-silver-tetrylene complexes perform the strongest inhibitory effects towards both proteins. The structures of the complexes exhibit good site–site binding to both proteins given the observations on the hydrogen bond interactions, cation–π bonds, π–π bonds, and ionic interactions, interaction distance between amino acids and ligands, and van der Waals interactions. The inhibitory capacity onto protein 4G9M decreases in the following order: bis-Ag-C > bis-Ag-Si > bis-Ag-Ge > validamycin > Ag-C ≈ Ag-Si ≈ Ag-Ge. The corresponding order observed from the study for protein 6JBR is bis- Ag-C > bis-Ag-Si ≈ bis-Ag-Ge > tricyclazole ≈ Ag-C ≈ Ag-Si ≈ Ag-Ge. The study opens a promising approach to tackle rice blast and rice sheath blight based on a family of silver-tetrylene organometallic chemicals given the theoretical proof of environment-advanced properties and molecule-scaled effectiveness.

Publication

On the Inhibitability of Natural Products Isolated from Tetradium ruticarpum towards Tyrosine Phosphatase 1B (PTP1B) and α-Glucosidase (3W37): An In Vitro and In Silico Study

( 2021)

Dao-Cuong To

;

Thanh Q. Bui

;

Nguyen Thi Ai Nhung

;

Quoc-Toan Tran

;

Thi-Thuy Do

;

Manh-Hung Tran

;

Phan-Phuoc Hien

;

Truong-Nhan Ngu

;

Phan-Tu Quy

;

The-Hung Nguyen

;

Huu-Tho Nguyen

;

Tien-Dung Nguyen

;

Phi-Hung Nguyen

Folk experiences suggest natural products in Tetradium ruticarpum can be effective inhibitors towards diabetes-related enzymes. The compounds were experimentally isolated, structurally elucidated, and tested in vitro for their inhibition effects on tyrosine phosphatase 1B (PTP1B) and α-glucosidase (3W37). Density functional theory and molecular docking techniques were utilized as computational methods to predict the stability of the ligands and simulate interaction between the studied inhibitory agents and the targeted proteins. Structural elucidation identifies two natural products: 2-heptyl-1-methylquinolin-4-one (1) and 3-[4-(4-methylhydroxy-2-butenyloxy)-phenyl]-2-propenol (2). In vitro study shows that the compounds (1 and 2) possess high potentiality for the inhibition of PTP1B (IC50 values of 24.3 ± 0.8, and 47.7 ± 1.1 μM) and α-glucosidase (IC50 values of 92.1 ± 0.8, and 167.4 ± 0.4 μM). DS values and the number of interactions obtained from docking simulation highly correlate with the experimental results yielded. Furthermore, in-depth analyses of the structure–activity relationship suggest significant contributions of amino acids Arg254 and Arg676 to the conformational distortion of PTP1B and 3W37 structures overall, thus leading to the deterioration of their enzymatic activity observed in assay-based experiments. This study encourages further investigations either to develop appropriate alternatives for diabetes treatment or to verify the role of amino acids Arg254 and Arg676.

Publication

Different Transfer Functions for Binary Particle Swarm Optimization with a New Encoding Scheme for Discounted {0-1} Knapsack Problem

( 2021)

Tung Khac Truong

;

Luigi Rodino

The discounted {0-1} knapsack problem (DKP01) is a kind of knapsack problem with group structure and discount relationships among items. It is more challenging than the classical 0-1 knapsack problem. In this paper, we study binary particle swarm optimization (PSO) algorithms with different transfer functions and a new encoding scheme for DKP01. An effective binary vector with shorter length is used to represent a solution for new binary PSO algorithms. Eight transfer functions are used to design binary PSO algorithms for DKP01. A new repair operator is developed to handle isolation solution while improving its quality. Finally, we conducted extensive experiments on four groups of 40 instances using our proposed approaches. The experience results show that the proposed algorithms outperform the previous algorithms named FirEGA and SecEGA . Overall, the proposed algorithms with a new encoding scheme represent a potential approach for solving the DKP01.

Publication

Beta-decay half-lives of the extremely neutron-rich nuclei in the closed-shell N = 50, 82, 126 groups

( 2021)

Nguyen Kim Uyen

;

Kyung Yuk Chae

;

Nguyen Ngoc Duy

;

Nguyen Duy Ly

The β−-decay half-lives of extremely neutron-rich nuclei are important for understanding nucleosynthesis in the rapid neutron capture process (r-process). However, most of their half-lives are unknown or very uncertain, leading to the need for reliable calculations. In this study, we updated the coefficients in recent semi-empirical formulae using the newly updated mass (AME2020) and half-life (NUBASE2020) databases to improve the accuracy of the half-life prediction. In particular, we developed a new empirical model for better calculations of the β−-decay half-lives of isotopes ranging in Z = 10–80 and N = 15–130. We examined the β−-decay half-lives of the extremely neutron-rich isotopes at and around the neutron magic numbers of N = 50, 82, and 126 using either five different semi-empirical models or finite-range droplet model and quasi-particle random phase approximation method. The β−-decay rates derived from the estimated half-lives were used in calculations to evaluate the impact of the half-life uncertainties of the investigated nuclei on the abundance of the r-process. The results show that the half-lives mostly range in 0.001 < T1/2 < 100 s for the nuclei with a ratio of N/Z < 1.9; however, they differ significantly for those with the ratio of N/Z > 1.9. The half-life differences among the models were found to range from a few factors (for N/Z < 1.9 nuclei) to four orders of magnitude (for N/Z > 1.9). These discrepancies lead to a large uncertainty, which is up to four orders of magnitude, in the r-process abundance of isotopes. We also found that the multiple-reflection time-of-flight technique is preferable for precise mass measurements because its measuring timescale applies to the half-lives of the investigated nuclei. Finally, the results of this study are useful for studies on the β-decay of unstable isotopes and astrophysical simulations.

Publication

p-Coumaric Acid Enhances Hypothalamic Leptin Signaling and Glucose Homeostasis in Mice via Differential Effects on AMPK Activation

( 2021)

Linh V. Nguyen

;

Khoa D. A. Nguyen

;

Chi-Thanh Ma

;

Quoc-Thai Nguyen

;

Huong T. H. Nguyen

;

Dong-Joo Yang

;

Trung Le Tran

;

Ki Woo Kim

;

Khanh V. Doan

AMP-activated protein kinase (AMPK) plays a crucial role in the regulation of energy homeostasis in both peripheral metabolic organs and the central nervous system. Recent studies indicated that p-Coumaric acid (CA), a hydroxycinnamic phenolic acid, potentially activated the peripheral AMPK pathway to exert beneficial effects on glucose metabolism in vitro. However, CA’s actions on central AMPK activity and whole-body glucose homeostasis have not yet been investigated. Here, we reported that CA exhibited different effects on peripheral and central AMPK activation both in vitro and in vivo. Specifically, while CA treatment promoted hepatic AMPK activation, it showed an inhibitory effect on hypothalamic AMPK activity possibly by activating the S6 kinase. Furthermore, CA treatment enhanced hypothalamic leptin sensitivity, resulting in increased proopiomelanocortin (POMC) expression, decreased agouti-related peptide (AgRP) expression, and reduced daily food intake. Overall, CA treatment improved blood glucose control, glucose tolerance, and insulin sensitivity. Together, these results suggested that CA treatment enhanced hypothalamic leptin signaling and whole-body glucose homeostasis, possibly via its differential effects on AMPK activation.

Publication

Isolation and Plant Growth Promoting Characterization of Potassium Solubilizing Bacteria in Rhizosphere of Some Crops in Vietnam

( 2021)

Võ Thị Xuyến

Many soil microorganisms are able to dissolvethese types of potassium and have been applied in agriculture. These potassium solubilizing bacteria (KSB) have also been shown to have by many other direct or indirect plant growth-promoting activities. This study's aim was isolation, screening and plant growth-promoting characterization of KSB from rhizospheric soil of some crops in Vietnam. The results were that thirty-four KSB isolates were collected on Aleksandrov agar medium from ten soil samples from the rhizospheres of banana, pitaya, and mango. By the spot streak technique on this medium, three KSB isolates including BE204, BE208 and BE220 were screened with the potassium solubility indexes 10.87, 10.97, and 10.72, respectively. All of three selected isolates were identified as belong to Burkholderia genus by the specific protein springers, in which, BE208 had the best match with B. gladiola. The two strains BE204 and BE208 showed a higher potential because of the capility to antagonize to most of thirteen surveyed phytopathogens including Phomopsis longicolla, Neoscytalidium dimidiatum, and Phyllosticta cavendishii, based on the dual culture technique, causing significant damage on many crops in Vietnam. In addition, the two strains were also able to dissolve phosphate and zinc and produce enzymes hydrolyzing protein, starch and cellulose by also the spot streak technique. The results contributed the potential bacterial collection for the research and development of products from indigenous KSB in Vietnam. However, additional classifications as well as the safety of these selected strains need to be further investigated.

Publication

Electrochemical Determination of Diclofenac by Using ZIF-67/g-C3N4 Modified Electrode

( 2021)

Dang Thi Ngoc Hoa

;

Nguyen Thi Thanh Tu

;

Le Van Thanh Son

;

Le Vu Truong Son

;

Tran Thanh Tam Toan

;

Pham Le Minh Thong

;

Dao Ngoc Nhiem

;

Pham Khac Lieu

;

Dinh Quang Khieu

;

Thanh Son Le

A facial differential pulse voltammetric procedure using a glassy carbon electrode modified with zeolite imidazolate framework-67/graphitic carbon nitride (ZIF-67/g-C3N4) for the diclofenac (DCF) determination is demonstrated. ZIF-67/g-C3N4 with different mass ratios of the components was synthesized in a self-assembly process. The obtained materials were characterized by using X-ray diffraction, scanning electron microscopy (SEM), EDX-mapping, and nitrogen adsorption/desorption isotherms. The peak current varies linearly with the DCF concentration in the range of 0.2–2.2 μmol·L−1 and has a detection limit of 0.071 μmol·L−1. The modified electrode exhibits acceptable repeatability, reproducibility, and selectivity towards DCF. The proposed electrode allows determining DCF in human urine without pretreatment, and the results are comparable with those determined with HPLC.

Publication

Effects of NaB2O4:Mn2+ and Ba2Li2Si2O7:Sn3+,Mn2+ phosphors and remote structure organizations on the white light-emitting diodes with quantum dots and phosphors

( 2021)

Phan Xuan Le

;

Le Nguyen Hoa Binh

In order to increase the optical features of white light-emitting diodes (WLEDs), quantum dots (QDs) and phosphor materials have been proposed because of outstanding performance. The configuration of WLEDs with QDs layer and phosphor-silicone layer suggested placing these components separately to limit light loss, and enhance consistency at contact surface of QDs. In this research, the effects of QDs and phosphor on the performance of WLEDs are concluded through experiments. The emitted light and PL spectra were examined thoroughly, and infrared thermal imagers were applied to simulate the heat generation of an actual WLED device. The results show that with the configuration of 60 mA energy source, WLEDs which has the QDs-on-phosphor form attained luminous efficiency (LE) of 110 lm/W, with color rendering index (CRI) of Ra=92 and R9=80, whereas the WLEDs which has the phosphor-on-QDs form only has 68 lm/W in LE, Ra=57 and R9=24. Furthermore, WLEDs which has the QDs-on-phosphor form has less high temperature generated at the components’ conjunction in comparison to the counterpart, the peak generated heat in QDs-on-phosphor WLEDs is also lower and the heating capacity gap between 2 structures can go up to 12.3°C.

Publication

Triple-layer remote phosphor structure: a selection of the higher color quality and lumen efficiency for WLEDs

( 2021)

Phan Xuan Le

;

Le Hung Tien

To enhance color quality of glass-based phosphor-converted white light-emitting diodes (pc-WLEDs) with multi-layer remote phosphor layer structures, two phosphors, green CdS:In and red ZnS:Te,Mn, are integrated into the glass matrix and applied to the dual-layer and triple-layer WLED packages. The attained results were examined with Mie-scattering theory and Lambert-Beer law. The dual-layer showed significant enhancement in color rendering index (CRI), in the range of approximate 80-90. Meanwhile, CRI in the triple-layer was lower and stayed around 66. In terms of color quality scale (CQS), a more overall color evaluating index, triple-layer structure helps the glass-based WLED achieve higher value than the dual-layer. The triple-layer is also beneficial to the luminous efficacy, according to the experimented results. Thus, the triple-layer structure can be used to strengthen the benefit of the glass matrix used in WLED products.

Publication

Ảnh hưởng của phân bón hữu cơ tạo từ thân chuối đến sinh trưởng và năng suất cây ngải cứu

( 2021)

Vũ Thị Quyền

;

Lê Quốc Bảo

Nghiên cứu nhằm đánh giá ảnh hưởng của phân hữu cơ từ thân chuối (gọi tắt là phân chuối) đến sinh trưởng và năng suất cây ngải cứu trồng theo phương thức hữu cơ tại vùng đất xám thuộc xã Phước Hiệp, huyện Củ Chi, thành phố Hồ Chí Minh. Kết quả sau hơn 2 tháng thử nghiệm đã chỉ ra rằng: (i) bón phân chuối với liều lượng 15 tấn/ha cho chiều cao cây đạt 44,11 cm, tổng số lá/cây 150 lá, năng suất sinh khối binh quân 18 tấn/ha, hệ số giữa sinh khối khô và sinh khối tươi của cây ngải cứu dao động ở mức 23 - 27%; (ii) việc bón lót phân chuối đé trồng ngải cứu có ý nghĩa rất lớn trong việc cải thiện pH và độ dẫn điện của đất (EC) đối vói khu vực đất xám thuộc huyện Củ Chi. Chỉ sau 70 ngày thí nghiệm, độ pHH20 từ 5,26 (chua) tăng lên 6,77 (trung tính) và độ dẫn điện của đất (EC) từ 124 pS/cm tăng lên 252,25 pS/cm, thể hiện đất được tăng cường ion hòa tan sau khi bón lót phân chuối và thực hiện canh tác hữu cơ cho cây ngải cứu; giúp tăng khả năng cung cấp dinh dưỡng cho cây từ đất. Điều này ghi nhận vai trò to lớn của phân bón hữu cơ từ thân chuối đến năng suất cây ngải cứu, cũng như việc cải thiện tính chất lý, hóa của đất canh tác.

Publication

Phytochemical profiling and GC–MS analysis of Vitis rotundifolia pulp extract (Jumbo muscadine)

( 2021)

Tan Phat Chau

;

Van Hung Tran

;

Mona S. Alwahibi

;

M. Ajmal Ali

;

Rajasree Shanmuganathan

Now a days, phytochemical screening and GCMS analysis draw the attention of researchers, as it is the important tool to analyze secondary metabolites and bioactive compounds which are used to produce the herbal medicines, food colorants, flavors and fragrances. In this study bioactive compounds and phytochemical constituents of Jumbo muscadine grape pulp extract are analyzed. The extract has been characterized by UV and FTIR in which both the optical property and functional groups are identified. Absorption spectra of UV showed the highest peak at 270 nm which associates to the polyphenol and functional groups such as alcohol; alkene has been interpreted using FTIR spectrum. Presence of phytochemicals is confirmed by qualitative tests and quantified. Bioactive compounds are interpreted using gas chromatography–mass spectrometry analysis. This grape extract contains phenols, terpenoids, saponins and carbohydrates as major phytochemicals. Identified essential bioactive compounds of this extract include Glycerin, oleic acid, palmitic acid and 5-hydroxymethyl furfural.

Publication

Optimization of Anthocyanin Extraction from Rhodomyrtus tomentosa (ait.) Hassk. Fruits and their Antioxidant Potentials

( 2021)

Fruits of Rhodomyrtus tomentosa (sim fruits) are comprised of high amount of anthocyanin content. They are among the richest sources of anthocyanins, an indication that the plant is endowed with potential bioactive agents. Anthocyanins are plant pigments that play important roles in plant physiology, as well as, beneficial health effects to humans. In this study, optimal conditions for extraction of total anthocyanins of R. tomentosa fruits and their antioxidant activity were investigated. Parameters, such as solvent, acid concentration, solid-to-solvent, ultrasound, temperature, and time were applied for investigation of extraction efficiency of anthocyanins of the plant. Total anthocyanin content was determined via the pH differential method. Antioxidant activity of the anthocyanin-rich extract was then examined using DPPH and ABTS+ radical-scavenging assays and DCFH-DA method. The results showed that total anthocyanin content of up to 123.9 mg/kg was obtained from the sim fruits under the extraction conditions of acidified 50% aqueous ethanol by hydrochloric acid solution 0.1 M at a solid-to-solvent ratio of 1:4 with the assistance of ultrasound for 60 min before being processed at a temperature of 60oC for 60 min. The anthocyanins-rich extract was able to scavenge DPPH and ABTS+ radicals with IC50 values of 0.0173 ± 0.001 μg/mL and 0.0238 ± 0.0002 μg/mL, respectively. Moreover, the inhibitory activity of the anthocyanin-rich extract on intracellular reactive oxygen species production from macrophage RAW 264.7 cells was also evidenced. As a result, anthocyanins from R. tomentosa fruits might be a useful source of ingredients for the prevention of oxidant-induced disorders.

Publication

Fluoride and Arsenite Removal by Adsorption on La2O3-CeO2/Laterite

( 2021)

Duong Thi Lim

;

Trinh Ngoc Tuyen

;

Dao Ngoc Nhiem

;

Dao Hong Duc

;

Pham Ngoc Chuc

;

Nguyen Quang Bac

;

Dang Xuan Tung

;

Ngo Nghia Pham

;

Luu Thi Viet Ha

;

Nguyen Thi Thanh Tu

;

Vo Thang Nguyen

;

Dinh Quang Khieu

;

Dong kee Yi

In the present article, the adsorbent prepared from laterite with lanthanum and cerium oxides (La2O3-CeO2/laterite (LCL)) was efficiently employed for the removal of arsenite and fluoride from an aqueous environment. The obtained materials were characterized by XRD, SEM, and nitrogen adsorption/desorption. The synthesized LCL exhibited a high adsorption capacity towards arsenite (As(III)) and fluoride. The adsorption of both analytes on LCL, which was well-fitted to a pseudo-second-order equation, was found to be kinetically fast in the first 20 minutes and reached equilibrium at around 180 minutes. Weber’s intraparticle diffusion model in multilinearity using the piecewise linear regression combined with Akaike’s criteria was addressed. The adsorption capacities of LCL calculated from Langmuir’s isotherm model were found to be 67.08 mg·g-1 for arsenite and 58.02 mg·g-1 for fluoride. Thermodynamic parameters presented an endothermic nature of arsenite adsorption but an exothermic nature for fluoride and a negative Gibbs free energy for the spontaneous process of arsenite or fluoride adsorption at the studied temperature range. The excellent adsorption performance and stability make the composite of laterite and La-Ce binary oxides an alternative efficient and cheap adsorbent for the removal of arsenite and fluoride in an aqueous solution.

Publication

Chemical Constituents of Cordyceps neovolkiana DL0004

( 2021)

Chi-Dung Nguyen

;

Thi-My-Ninh Pham

;

Thi-Bich-Hang Ha

;

Thi-Phuong Nguyen

;

Huu-Hung Nguyen

;

Hoang-Vinh-Truong Phan

;

Thuc-Huy Duong

;

Minh-Hiep Dinh

Publication

Applying SiO2 nano-particles for improving optical properties of WLED conformal and in-cup structures

( 2021)

Phan Xuan Le

;

Pham Quang Minh

This article is the analysis of SiO2 nano-particles’ influences on the luminous efficiency and the color temperature uniformity of a remote phosphor structure in a WLED. The purpose of integrating SiO2 into the silicone layer in the remote phosphor structure is to significantly promote the scattering occurrences. Particularly, with an appropriate proportion of SiO2, there could be more blue lights generated at large angles, leading to reducing the angular-dependent color temperature deviation. The luminous flux also can get benefits from SiO2 addition owing to a proper air-phosphor layer refractive index ratio provided by this SiO2/silicone compound. The attained experimental results were compared with optical values of a non-SiO2 remote phosphor configuration and showed a notable enhancement. The color deviation was reduced by approximately 600 K in the angles from -700 to 700. Additionally, the lumen efficiency was improved by 2.25% at 120 mA driving current. Hence, SiO2 can be used to boost both color uniformity and luminous efficacy for remote-phosphor WLED.

Publication

Nickel ferrite: synthesis and application for voltammetric determination of uric acid

( 2021)

Nguyen Thi Vuong Hoan

;

Nguyen Ngoc Minh

;

Nguyen Thi Lieu

;

Nguyen Van Thang

;

Vo Thang Nguyen

;

Nguyen Thi Thanh Tu

;

Tran Thanh Tam Toan

;

Nguyen Hoang Tuan

;

Duong Quang Nhan

;

Ho Van Minh Hai

;

Tran Ngoc Tuyen

;

Dinh Quang Khieu

In this paper, the synthesis of nickel ferrite and its use for voltammetric determination of uric acid (UA) are presented. Nickel ferrite was synthesized via a hydrothermal process using spherical carbons as hard template followed by calcination at 500 °C. It was found that iron and nickel compositions in nickel ferrite can be controlled by the initial Fe/Ni molar ratio. The stoichiometric nickel ferrite (NiFe2O4) with hollow spherical morphology was obtained from a reaction mixture with Fe/Ni molar ratio of around 1.2–1.5. Glassy carbon electrode modified with nickel ferrite was employed to quantitatively determine UA by different pulse voltammetric method. Under the optimum conditions, the anodic peak current was linearly proportional to UA concentration in the range of 0.398 to 6.761 μM. The detection limit (3σ) was found to be 0.15 μM. The proposed method has been employed to determine UA in human urine samples with acceptable recoveries of 95.15–104.8%. On the other hand, the results obtained from this method were also compared with that from standard HPLC method, showing no statistical difference.

Publication

Effects of air temperature and blanching pre-treatment on phytochemical content, antioxidant activity and enzyme inhibition activities of Thai basil leaves (Ocimum basilicum var. thyrsiflorum)

( 2021)

N.L. Le

;

T.T.H. Le

;

N.B. Ma

Thai basil leaves (Ocimum basilicum var. thyrsiflorum) have been used in food flavoring and traditional medicine. Hot-air drying is a convenient and low-cost method to preserve them for long-term use but causes the loss of their bioactive compounds during the process. In this work, the effect of pre-blanching on preserving these characteristics of Thai basil leaves dried at different air temperatures was studied. The antioxidant characteristics were evaluated by the contents of total phenolics, total flavonoids and total chlorophylls and the scavenging capacity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. In addition, the inhibitory activities against starch-digesting enzymes were assessed with α-amylase and amyloglucosidase. At the air temperature of 50oC, antioxidant characteristics of dried leaves with pre-blanching were proven better than those without blanching and came close to those of the fresh sample. The drying temperature had more evident effects on inhibitory activities against starch-digesting enzymes than blanching. These activities of hot-air dried leaves were comparable to those of the fresh one. This study could provide insights into the integration of blanching and hot-air drying to preserve medicinal plants.

Publication

Evaluation of fatty acids, phenolics and bioactivities of spent coffee grounds prepared from Vietnamese coffee

( 2021)

Danh C. Vu

;

Quyen T. Vu

;

Long Huynh

;

Chung-Ho Lin

;

Sophie Alvarez

;

Xuyen T. Vo

;

Trang H. D. Nguyen

Spent coffee ground (SCG) is a residue released during coffee brewing. Disposal of SCG is able to lead to a loss of bioactive constituents and have a negative impact upon the environment. This study aimed to explore fatty acids, bioactive phenolics, antioxidant and anti-aging potentials of SCG samples obtained from coffee shops in Ho Chi Minh city, Vietnam. The oil content of the SCG samples ranged from 6.3 to 10.5%, and linoleic (43%), palmitic (33.4%) and oleic (11%) acids were identified as major constituents of the oil. Chlorogenic acid was the most abundant phenolic acid examined (832.9–7657.7 μg/g of dry weight), followed by ferulic acid (40.5–1041.7 μg/ g). Through anti-collagenase and anti-elastase assays, SCG showed a promising anti-aging activity, with IC50 values comparable with those of epigallocatechin gallate. The correlation analysis revealed gallic acid positively correlated with the free radical scavenging potential evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) assay and the inhibitory effect on elastase. The results demonstrated that utilization of SCG prepared from Vietnamese coffee could open new avenues for food and cosmeceutical industry.

Publication

Temperature Effect of Water Coagulation Bath on Chitin Fiber Prepared through Wet-Spinning Process

( 2021)

Khoa Dang Nguyen

Chitin was chemically extracted from crab shell waste and dissolved in N,N-dimethyl acetamine/5% lithium chloride (DMAc/5% LiCl) at room temperature to obtain 1% and 2% concentrations of chitin solution. Chitin fibers were prepared by phase inversion at different temperatures of water coagulation bath at 5, 20, and 60 °C. The deconvolution of FTIR spectra indicated that the area portion of the intermolecular hydrogen bonding NH…OC increased at 60 °C due to the higher density of the chitin segment in the fiber. As a result, scanning electron microscope (SEM) measurement suggests that a denser structure of the chitin fiber was observed when the temperature of the coagulation bath increased. In addition, the resultant chitin fibers generated better mechanical properties relative to the amount of chitin concentration and temperature. At 2% of chitin solution, the tensile strength significantly increased from 80 to 182 MPa for the fiber obtained at temperatures of 5 and 60 °C of the water coagulation bath, respectively. Meanwhile, the water content in the fiber significantly decreased from 1101% to 335%. This green synthesis route has high potential for the fabrication of the fiber as future material of interest for biomedical application.

Publication

Development of polyvinyl (alcohol)/D-glucose/agar/silver nanoparticles nanocomposite film as potential food packaging material

( 2021)

Bao-Tran Tran Pham

;

Thuy-Hang Thi Duong

;

Thuong Thi Nguyen

;

Dai Van Nguyen

;

Chinh Dung Trinh

;

Long Giang Bach

The functional nanocomposite films from polyvinyl (alcohol) (PVA), D-glucose, agar, and silver nanoparticles (AgNPs) components were synthesized through the facile casting method. Results from the evaluation of antimicrobial activity and composite film properties showed that the combination of PVA/D-glucose/agar with AgNPs significantly enhanced bactericidal activity against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, as well as mechanical property. Furthermore, the coating from the combination of PVA/D-glucose/agar with AgNPs was also applied in Areca banana preservation for 7 days at 25 ℃. Appearance, physiological weight loss, total soluble sugars, and titratable acidity were daily evaluated during storage period. The obtained results of this study show the promising potential of PVA/D-glucose/agar nanocomposite film incorporated with AgNPs for food packaging applications in the near future.

Journal Articles - Natural Science - 2021

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