bluuebunny/crossref_metadata_2025 huggingface dataset:
The preparation of composites between polyaniline-silver (PANI-Ag) via interfacial polymerization
Authors: Panloetparnich W , Loryuenyong V , Buasri A
Published: December 2020

In this study, polyaniline-silver (PANI-Ag) composites between aniline monomer and Ag particles in silver nitrate were prepared via interfacial polymerization method at room temperature. The objective was to study the effects of mass ratios of aniline monomer to Ag particles in silver nitrate (1:0.5, 1:1, 1:1.5, 1:2 and 1:2.5) on the electrochemical properties. The characterization techniques included FTIR, XRD, SEM and EDAX. FTIR and XRD results presented the success of the synthesis of the composites and crystallization of the PANI-Ag composites due to the presence of silver. SEM and EDAX techniques indicated that polyaniline nanofibers were successfully covered on the Ag particles. The CV results showed the higher specific capacitance with increasing amounts of Ag particles.
Effect of titanium dioxide on the properties of poly(butylene adipate-co-terephthalate) films
Authors: Arssanasuwan N. , Threepopnatkul P. , Sittattrakul A.
Published: December 2020

In this study, the effect of titanium dioxide (TiO2) in poly(butylene adipate-co-terephthalate) was investigated. PBAT/TiO2 biocomposite films containing different weight percentages (0.25, 0.5, 1 and 3 %w/w) of TiO2 were prepared by mixing PBAT and TiO2 in a twin screw extruder and thin films were prepared by cast film extruder. The thickness of each film is in the range of 50-90 micron. PBAT/TiO2 biocomposite films were characterized by Fourier transform infrared spectroscopy, X-Ray diffraction, Tensile testing, Scanning electron microscopy and Differential scanning calorimetry. Incorporating TiO2 (0.25-1 %w/w) in PBAT matrix was found the Young’s modulus and Tensile strength were increased while the addition of TiO2 more than 1 %w/w (3 %w/w) exhibited lower Young’s modulus and Tensile strength as a result of agglomeration of TiO2 that was shown in SEM images. Thermal properties of biocomposite films showed the percent of crystallinity increased by increasing TiO2 concentration up to 1 %w/w. Moreover, addition of TiO2 concentration up to 3 %w/w the percentage of crystallinity was decreased probably as a result of agglomeration of TiO2 that affected on crystallization of PBAT/TiO2 biocomposite films.
Carbothermic Reduction of the Waste Chromium Oxide Rods from Thermal Spray Processes
Authors: Thongyoug Penpisuth , Tungtrongpairoj Jennarong
Published: December 2020

The waste chromium-oxide rods from thermal spray processes contained the valuable components of high chromium. The carbothermic reduction with graphite powders can be used to recover the chromium from the chromium-oxide rod. The waste rods were prepared into small pieces with a half-dimensions of 6.3 mm diameter and 5 mm length, and heated under the reducing atmosphere at 1150 – 1350 °C. Besides, the effect of different types and sizes of reducing agent on the reduction was observed. During the heating and cooling period, argon gas was fed into the atmosphere. Chromium carbide formation was promoted when the temperature and time were increased. Cr-O and Cr-O-Al-Si were observed in the microstructures before and after the reduction. The outermost part of the waste rod can be reduced to chromium because of the interphase zone. Consequently, the carbothermic reduction is one possible recycling method for utilizing ceramic rod wastes from the thermal spray process.
Mechanical Properties and Melt Flow Index of Poly (butylene succinate) Blended with a Small Amount of Natural Rubber Compound
Authors: Singsang W , Rumjuan P , Ausungnoen Y , Charentanom W , Srakaew N , Prasoetsopha N
Published: December 2020

Natural rubber compound (NRC) was blended with biodegradable poly(butylene succinate) (PBS) with PBS/NRC weight ratios of 100/0, 97/3, 94/6 and 90/10. The PBS/NRC blends were melt mixed using an internal mixer at 145°C. Mechanical properties and melt flow index of the blends were investigated. The results showed that the percentage elogation at break and impact strength of the blends impoved when NRC was added. On the other hand, the Young’s modulus and tensile strength of the blends decreased with an increase in the amount of NRC. The melt flow index of the blends continuously decreased with an increase in NRC content. This implied that NRC increased the viscosity of the blends. Moreover, the fractured surface morphology of PBS/NRC blends showed a good dispersion of NRC particles in PBS matrix. The average particle size of NRC was 2-5 μm.
Effect of poly(ethylene oxide) on the properties of poly(lactic acid)-based blends
Authors: Khanteesa R. , Threepopnatkul P. , Sittattrakul A.
Published: December 2020

Poly(lactic acid) (PLA) was blended with poly(ethylene oxide) (PEO) with four different molecular weights of 1 × 105, 2 × 105, 3 × 105, and 4 × 105 g/mol to improve the flexibility of PLA. The blends were compounded in an internal mixer at 190 °C with 50 rpm for 15 minutes and using a hot press to mold rectangular sample sheets. The mechanical properties of PLA blends were analyzed to prove the ductility. Additionally, phase morphologies of blends were investigated by using tensile fracture surface. The addition of PEO into PLA matrix leads to slight increase in tensile strength, while the elongation at break was decreased by increasing the molecular weight of PEO. However, the elongation at break of PLA/PEO blends was higher than the one of neat PLA. In other words, PEO enhanced the flexibility of PLA blends, according to scanning electron microscope images. In brief, PLA-based blends greatly increased in ductility.
The effect of rotor speed on EVA/PBAT blend using Twin screw extruder and foamability of EVA/PBAT blend
Authors: Thongpin Chanchai , Theanchai Kanyapak , Riangpha Pattama , Anantawut Weena
Published: December 2020

This research is aimed to study EVA/PBAT blends with various EVA and PBAT composition and screw speeds. At PBAT contents 40% EVA and PBAT present as co-continuous phase morphology. The morphology did not change due to screw speed. At PBAT 50% by weight, co-continuous phase occurred and the morphology becomes dispersed as screw speed was increased to 80 and 100 rpm. Extrudates obtained from twin screw extruder were tensioned under tensile force. The results show elastomeric behavior of the blends. Elongation at break was higher than 800 % strain and exhibited strain hardening characteristic. Secant modulus of EVA/PBAT blends was increased with PBAT contents due to the high modulus of semi-crystalline PBAT. Content of EVA controls elongation ability of the blends. EVA/PBAT blends with the content of 40/60, 50/50, 60/40, 70/30 and 80/20 were form for foam and found that all composition could be able to be foam. This could be further studied and carried on for shoes sole application.
Isolation and characterization of PLA-degrading bacteria from landfill soil at mesophilic temperature
Authors: Jalani J C , Arshad Z I M , Shaarani S Md , Che Man R , Abdul Mudalip S K , Sulaiman S Z
Published: December 2020

This study aimed to isolate and characterize polylactic acid (PLA) degrading bacteria present in landfill soils located in Pekan, Pahang. The conducted study involves collecting four soil samples from four different sources and stored at room temperature before undergoing serial dilution from dilution factor (DF) 10−1 until dilution factor 10−10. Characterization of bacteria via Gram staining was done only on isolates (69 colony) with DF 10-6 until DF 10-10 but only 13 isolates from plate with DF 10-8 and 10-10 were re-streaked to obtain single colony. The single colony obtained were further characterized for their morphological characteristics and tested for presence of protease enzyme by streaking the colony on skim milk agar which resulted with only four (A10K, A10B, B8A and D10A) showing positive presence of protease enzyme. The four plates were tested for catalase using 3%(v/v) hydrogen peroxide and all resulted with vigorous bubbling which indicate positive catalase enzyme. Relative enzyme activity was calculated for all four bacteria through observation of halo zones on skim milk agar, and isolate A10B shows the highest relative enzyme activity with 3.86, and thus showing potential to accelerate the degradation of PLA at mesophilic temperature. Therefore, in this study, it is proven to be possible to isolate bacteria that can degrade PLA at mesophilic temperature from landfill soil.
Ultrasonic assisted fermentation for production of xylanase enzyme using locally isolated strain of Bacilus badius
Authors: Masngut N , Rajandran P , Damanhuri N A
Published: December 2020

Ultrasonic assisted fermentation has been shown to improve the fermentation and product yield; however, less attention has been given to the xylanase production via ultrasonic assisted fermentation. The purpose of this study was to investigate the conditions in which ultrasonic has been employed to enhance fermentation reactions of interest to xylanase production. Previously, the xylanase production from locally isolated strain identified as Bacillus Badius was successfully carried out at an optimum condition. In this study, xylanase production was further explored by incorporated ultrasonic assisted fermentation. The study was conducted by varying the ultrasonic process parameters including treatment time, amplitude and duty cycle. Within the studied range, the highest xylanase production was 9.21 U/mL at duty cycle of 10 %, amplitude of 2 % and treatment time of 25 min. However, the production was 21 % lower than that the conventional optimized fermentation. This is due to unoptimized condition of the ultrasonic assisted fermentation as compared to the conventional one. Ultrasonication at the best process parameters is an effective and feasible way to enhance xylanase activity. In the future, we are looking forward to optimize the ultrasonic assisted fermentation to maximized xylanase production.
Comparative evaluation of the antibacterial activities of the essential oils of Citrus grandis (L.) Osbeck obtained by hydrodistillation and microwave assisted extraction methods
Authors: Tran T H , Dao T P , Ngo Q C T , Bach L G , Huynh X P
Published: December 2020

The essential oils (EOs) from peels of Citrus grandis (L.) Osbeck was investigated for their antimicrobial activities against food-related microorganisms by hydrodistillation method (HD), and microwave-assisted extraction (MAHD). The total yield of the volatile fractions obtained through HD and MAHD was 4.4 mL/g and 4.75 mL/g, respectively. The gas chromatography–mass spectrometry (GC–MS) analyses of the oils revealed the presence of different compounds in Citrus grandis EOs obtained from MAHD and HD methods, including α-pinene, sabinene, β-myrcene, α-phellandrene and d-limonene. The essential oils obtained from the two extraction methods were found to inhibit six bacteria strains including Bacillus cereus, Bacillus subtilis, Pseudomonas aeruginosa, E. coli, Clostridium perfringens and Salmonella typhi. The results of antibacterial properties of Citrus grandis (L.) Osbeck EOs against six bacterial strains showed that essential oil extracted from the HD method were more bacteriostatic than the oil extracted from MAHD method. With this result, the essential oil obtained by the HD method was more active than that of the MADH method against the bacteria.
Extraction of Essential oils and volatile compounds of Kaffir lime (Citrus hystrix D.C) by hydrodistillation method
Authors: Le X T , Ha P T H , Phong H X , Hien T T , Ngan T T K
Published: December 2020

Kaffir lime (Citrus hystrix D.C.), a member of the Citrus family, is a lemon tree naturally grown in tropical regions of Asia. Kaffir lime contains a specific aroma currently used worldwide as spices and cosmetics. Kaffir lime leaves are a famous spice for many dishes of Thai cuisine. The peel of Kaffir lime collected in the southwest of Vietnam was used for essential oil extraction using the process of hydro-distillation. During extraction, 100 g Kaffir lime peel was input at 1:3 ratio, at 120 °C for 90 min. The phytochemical profile of Kaffir Lime essential oil was analyzed by using gas chromatography/mass spectrometry (GC/MS) assay. The optimal essential oil yield reached 4.6%. A total of twenty-six components have been identified to account for 99.998% of essential oils. B-pinene (47.926%) was characterized as the main ingredient of peel oil. Other major components of Kaffir lime essential oil included D-limonene (24.121%), citronelal (11.84%), and α-pinene (2.834%). The present study evaluated the chemical compositions of Kaffir lime essential oil and compared with other previous studies. Future research on Kaffir lime EO can be expanded by using different extraction methods to improve its bioactive and applicability in many regions.
Phytochemicals and Antioxidant Activity of Aqueous and Ethanolic Extracts of Mentha aquatica L.
Authors: Thi N Q N , Duc L T , Minh L V , Tien L X
Published: December 2020

In Vietnam, Mentha aquatica L. is often used as a spice in dishes, fragrance and pharmaceuticals. The tea made from the plants’ leaves has been used as a traditional medicine for fevers, headaches, digestive disorders and mouthwash. The present study aimed to explore the phytochemical profile of aqueous and ethanolic extracts of M. aquatica L. leaves as well as their total phenolics content, total flavonoid content and antioxidant activity. Various bioactive constituents were detected in M. aquatica L. extracts, including alkaloid, flavonoid, terpenoid, tannin, coumarin, anthraquinone and saponin. Furthermore, the total content of phenolics of aquaeous extract was higher than ethanolic extract. We then evaluated the antioxidant capacity of these two extracts by using DPPH and ABTS scavenging assays. Results have shown that the aquaeous extract exhibited scavenging activity more actively against both free radicals, as compared to the aquaeous extract. Overall, the study proposed that M. aquatica L. leaves can be an enriched source of phytochemicals that can be used as natural antioxidants in multiple industries.
Chlorophyll content and antioxidant activity from folium sauropi (Sauropus androgynus (L.) Merr) with microwave-assisted extraction
Authors: Nguyen N H K , Tien H T C , Truc T T , Quoc L P T
Published: December 2020

Folium sauropi is grown commonly in Vietnam, it is a vegetable that contains many bio-active compounds such as chlorophyll, polyphenol, and antioxidant activity. The use of natural pigments having clear origin is a trend in food processing nowadays. The objective of this study was to find suitable conditions for extracting chlorophyll with antioxidant activity (DPPH) in folium sauropi leaves by microwave-assisted extraction. When extracted with acetone of 90°, microwave power of 300W, solid to solvent ratio of 1:30, microwave-assisted extraction time of 120 seconds; chlorophyll content (14.43± 0.16 μg/mL), and DPPH radical-scavenging activity (886.64± 15.89 μmol/L) obtained highest.
Comparison of chemical composition of essential oils obtained by hydro-distillation and microwave-assisted extraction of Japanese mint (Mentha arvensis L.) grown in Vietnam
Authors: Bui-Phuc T , Nhu-Trang T T , Cong-Hau N
Published: December 2020

The Japanese mint (Mentha arvensis L.) is known as a culinary and medicinal herb widely cultivated in several countries. The mint essential oil is considered as one main source of menthol. In this study, the Japanese mint collected from the Central Highlands of Lam Dong Province (Vietnam) was extracted the essential oil by hydro-distillation (HD) and microwave-assisted extraction (MAE). Different extraction parameters were investigated, involving mint leaf drying periods (30, 60, and 90 mins) at 50 °C, material to water ratios (1:4, 1:6, 1:8, and 1:10 for HD and 1:1, 1:1.5, 1:2, and 1:2.5 for MAE), extraction durations (60-180 for HD and 10-25 mins for MAE), and microwave energy (230, 380, 540, and 700 W) in order to discover the conditions with the highest yields for both HD and MAE. The GC-MS was used to determine the oil chemical constituents. For dried mint leaves (nearly 40 % moisture), the highest oil yield of 0.0832 mL g−1 (dried weight) was recorded, and the content of menthol was up to 70.60 % extracted by MAE whilst 0.0510 mL g−1 of yield (dried weight) and lower menthol (62.80 %) were obtained from HD. Besides, menthol, trans- and cis-menthone were found at relatively high concentrations for both HD and MAE (20.19-16.30 and 4.62-5.01 %, respectively). Compared to HD, MAE exhibited higher oil yields and menthol contents, but lower distillation time, resulting in more effective extraction performance of MAE.
Determination of structure and anticancer activity of MM2 compound, isolated from endophytic fungus Aspergillus terreus-RTN3 of Alpinia chinensis Rosc.
Authors: Vo T N M , Nguyen D N , Nguyen V T
Published: December 2020

The study has isolated endogenous A. terreus-RTN3 strain from young stems of Alpinia chinensis Rosc.-Zingiberaceae family. Cultivating and extracting compounds containing metabolites that are resistant to Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus (MRSA). Determining the number of antibacterial compounds in the crude extract by thin-layer chromatography and vacuum liquid chromatography (VLC), the research has isolated pure MM2 compound with high antioxidant activity and spectral resolution to find the structure compound MM2 (Methyl 2-((4-amino-2-bromo-3-methyl-5-thioxocyclopenta-1,3-dien-1-yl) oxygen) -4-hydroxy-6-methoxybenzoate). This is a new compound that has not been announced in any works in the world. MM2 compound has a high antioxidant activity, the ability to catch α, α-diphenyl-β-picrylhydrazyl (DPPH) free radicals increases linearly by concentration, at concentration 400ppm of MM2 is capable of catching over 75% of DPPH free radicals. The MM2 compound also has the ability to inhibit 4 test cell lines: breast cancer (MCF-7), cervical cancer (Hela), liver cancer (Hep G2) and lung cancer (NCI-H460). The results showed that MM2 compound’s ability to inhibit cancer cell lines increased linearly, at concentrations of 100 µg/ml of MM2 compound, which inhibited nearly 80% of cancer cell lines and was high most in liver cancer cell line HepG2 (at a concentration of 100 µg/ml inhibits 86.82% of liver cancer cells HepG2).
Isolation and determination of FUB-AMB in synthetic cannabinoids by gas chromatography-mass spectrometry
Authors: Nguyen T A , Lam T D , Nguyen T Đ
Published: December 2020

N-[[1-[(4-fluorophenyl)methyl]-1H-indazol-3-yl]carbonyl]-L-valine, methyl ester (FUB-AMB) is the most recent psychoactive substance in Vietnam. FUB-AMB is a synthetic cannabinoid (SC) with has similar biological effects to tetrahydrocannabinol (THC), the main active component of natural cannabis. The previous study exhibits a harmful SC compound, which may cause many threatening to consumer health and social security due to the intensive effect of this compound on the mental status and behavior of the consumer. In this study, FUB-AMB was isolated the first time in Vietnam (1 g) with a purity of 98.34% (determined by High Performance Liquid Chromatography). Spectroscopic data (ultraviolet, infraRed 1Hydro - nuclear magnetic resonance, 13carbon - nuclear magnetic resonance) confirmed the structure of that isolated compound. The isolated FUB-AMB was used as a reference standard to develop an analytical method to detect drugs in the general marijuana group. Chromatography separation was achieved using a diphenyl dimethyl polysiloxane Gas chromatography (GC) column (30m×0.25mm×0.25µm) with a total run time of 10 minutes. The limits of detection and quantification for FUB-AMB was 0.15 μg/mL and 0.5 μg/mL, respectively. The developed method was used to detect FUB-AMB in synthetic cannabinoids in 30 samples. The results showed that the content of FUB-AMB ranged from 3.4-59.2 mg/g in 30 synthetic cannabinoids. The advanced GC-MS method is simple, sensitive, accurate and practically useful for the determination of FUB-AMB in synthetic cannabinoids, which supports the authorities’ crime handling.
Physicochemical, Physical Characteristics and Antioxidant Activities of Three Edible Red Seaweeds (Kappaphycus alvarezii, Eucheuma spinosum and Eucheuma striatum) from Sabah, Malaysia
Authors: Farah Nurshahida M S , Nazikussabah Z , Subramaniam S , Wan Faizal W I , Nurul Aini M A
Published: December 2020

Kappaphycus alvarezii (KA), Eucheuma spinosum (ESp) and Eucheuma striatum (Est are tropical red seaweeds taken from Kunak, Sabah, contain essentials source of bioactive compounds to produce variety of functional foods. This study was intended to investigate the physicochemical, physical properties and antioxidant activities related to these edible seaweeds. Physicochemical properties value of swelling capacity (SWC) and oil retention capacity (ORC) in KA species showed the highest value (p<0.05) compared to ESp and ESt, and water retention capacity (WRC) in ESp species was significantly different than KA and ESt (p<0.05). As in physical properties, ESp exhibited higher in moisture content and opacity than KA and ESt. KA showed the highest water solubility (p<0.05) which associated to its carrageenan compound. The antioxidant activities; DPPH and TEAC assay with total phenolic content (TPC) of three seaweed species indicated that KA displayed the highest TPC (19.17±0.04 mg GAE/g DW) and the lowest radical scavenging activity in both TEAC and DPPH assays. Hence, the findings disclose the physical and physiochemical properties and antioxidant values of these seaweeds application as new information and potential antioxidant sources in foods manufacturing commodities.
Comparison of essential oil extracted from black pepper by using various distillation methods in laboratory scale
Authors: Dinh P N , Cam H D T , Quoc T P
Published: December 2020

Black pepper is an indispensable spice in life—pepper oil used in various fields as pharmaceutical, cosmetic, repellent. Black pepper was picked in Vietnam and its essential oil was obtained by distillation methods. This study investigated the effect of several parameters such as material/water ratio, distillation time, the weight of the sample, and extraction power on the yield and the quality of black pepper essential oil from three distillation methods. The results showed that the hydrodistillation method reached the highest yield of 2.19% at conditions of 60 minutes extraction time and material/water ratio of 1:15 g/mL compare to the steam distillation method and microwave assisted hydrodistilation method. GC-MS analysis resulted in the identification of 70 components accounting for 99% of the total amount: β-caryophyllene, 3-carene, D-limonene, and β-pinene, are among the main compounds in black pepper essential oil.
Production of cellulose and microcellulose from pineapple leaf fibre by chemical-mechanical treatment
Authors: Gnanasekaran S , Li Y Y , Shariffuddin J H , Ahamad Nordin N I Amalina
Published: December 2020

Pineapple leaf fibre (PALF) is major waste from pineapple cultivation with high cellulose content that exhibits superior mechanical properties. In this study, chemical-mechanical treatments were conducted to produce cellulose and microcellulose. For alkali and steam treatment, PALF treated with 5 wt% sodium hydroxide solution and steamed in an autoclave at temperature of 121 °C and pressure of 21 psi. Next, the PALF was bleached with 5 wt% sodium chlorite. Continued with acid hydrolysis with 3.5 M and 7.5 M hydrochloric acid to produce cellulose. For, the mechanical treatment which involved homogenization and ultrasonication to produce the microcellulose, the ultrasonication was varied for 30 and 60 min. The samples were analysed by Scanning Electron Microscopy, Thermal Gravimetric Analysis and Fourier Transform Infrared Spectroscopy (FTIR) to study surface morphology, thermal stability and functional group respectively. The results showed that ABAHU60 with alkali treatment, bleaching, acid hydrolysis, homogenization and ultrasonication of 60 min exhibits excellent thermal stability and surface morphology, where the maximum degradation temperature occurs at 349 °C, which is a 5% improvement compare to untreated fibre. Its surface is smoother without impurities, with a loose structure and reduce diameter of fibre.
Dilute acid hydrolysis pretreatment for sugar and organic acid production from pineapple residues
Authors: Ariffin K K , Masngut N , Seman M N A , Saufi S M , Jamek S , Sueb M S M
Published: December 2020

Pineapple residue which is pineapple leaves composed of about 80% of carbohydrate containing lignin, cellulose and hemicellulose was utilised for the production of fermentable sugars. However, pretreatment of lignocellulosic material is required to remove hemicellulose and lignin and reducing crystallinity of cellulose to enhance hydrolysis. This paper presents an experimental study of acid hydrolysis pretreatment in pineapple residue to produce sugar and organic acid using sulphuric acid. The effect of different acid concentration (4%, 8% and 12% v/v), solid-to-liquid ratio (10%, 15% and 20% w/v) and reaction time (40, 80, and 120 minutes) of acid hydrolysis pretreatment on pineapple residue at temperature of 100°C were studied to produce high yield of sugar and low organic acid production. As a result, the highest of sugar concentration simultaneously with the lowest of organic acids concentration from pineapple residue were 2.68 ± 0.12 g/L (xylose), 8.84 ± 0.11 g/L (glucose), 1.62 ± 0.20 g/L (formic acid) and 3.28 ± 0.26 g/L (acetic acid); recorded at conditions of 12% acid concentration (v/v), 20% solid-to-liquid ratio and 80 minutes of reaction time. In conclusion, dilute acid hydrolysis pretreatment was a great approach in order to produce high sugar at the same time with low organic acids yield from pineapple residue at mild conditions.
Evaluation of Antibacterial Activity of fractions from stem extract of Tinospora crispa (L.) Hook. f. & Thomson
Authors: Pham T N , Nguyen T V
Published: December 2020

The aim of this study is to evaluate the antibacterial activity of fractions from Tinospora crispa (L.) Hook. f. & Thomson stem extract. The extraction was fractionated by solvents with increasing polarity, then partioned with acidic water and base to concentrate alkaloids. There are totally 7 fractions named PD-hex, PD-K, PD-Cf2, PD-Cf1, PD-EtOAc, PD-BuOH and PD-N. With the help of disc diffusion method, 7 fractions were separately evaluated for their ability to inhibit the growth of some common bacterial species, including 3 Gram-positive and 3 Gram-negative bacteria. The result showed that Tinospora crispa was able to restrain the growth of the 3 Gram-positive species but not the 3 Gram-negative species. Antibacterial substances distributed in 6 over 7 fractions tested, excluding PD-K fraction. PD-K sample mainly contained strong basic alkaloid and soluble water. Especially, weak basic alkaloids in PD-Cf2 were able to restrict the bacterial growth stronger than stronger basic alkaloids in PD-K. On the other hand, ethyl acetate fraction (PD-EtOAc), which contained medium polar compounds, were able to restrict the growth of bacteria slightly better than the others. It was subjected to traditional column chromatography to isolate some components. The purified substance was structurally identified by thin-layer chromatography, high performance liquid chromatography and spectroscopic data analyses.
Isolation, identification and evaluation of Lactic acid synthesis of bacteria in traditional fermented products in Vietnam
Authors: Ong B N , Lam T D , Le T L , Nguyen T C , Tran Thi B H , Phan T M
Published: December 2020

Nowadays, many food products are promoted as being particularly healthy due to the characteristics of certain strains of lactic acid bacteria. Lactic acid bacteria (LAB) play a vital role in different fields, including food, pharmacy due to their benefit for young children, pregnant women and the elderly. LAB is one of the most significant groups of microorganisms used in food fermentations. They improve the flavour and texture of fermented foods. Moreover, LAB kills food spoilage bacteria by developing growth-inhibiting compounds. In this study, seven strains of LAB were isolated from traditional fermented products in VietNamm including fermented rice, kimchi, and yoghurt. Moreover, LAB isolated was identified by amplification and sequencing of 16s rDNA gene. The isolated strains were Lactobacillus plantarum (M2 and M7), Lactobacillus paracasei (M4), Lactobacillus sakei (M10), Leuconostoc mesenteroides (M15), Lactobacillus curvatus (M17), Lactobacillus delbruekii sub sp. (M19). Cultural characteristics of M1 and M7 surface colony are 2mm wide, raised, smooth and white on MRS agar. The morphology of the colonies M4 and M10 is rounded, smooth, light yellow. Nevertheless, M4 and M10 are quite different in colour, white and light yellow, respectively. Moreover, M15 colonies are convex, with flat edges, smooth, semitransparent. M17 and M19 are small, normally rough and non-pigment. Acid lactic content produced by the isolated strains determined by spectral absorbance at 390 nm with FeCl3 (0.2%), was highest in M2 strain (37.814g/l), followed by M17 (32.357g/l), M19 (27.336g/l), M4 (20.853g/l), M10 (9.408g/l), M7 (8.864g/l), and M15 (6.645g/l). In this study, the highest lactic acid content produced was M2 stain (Lactobacillus plantarum) and the lowest was M15 (Leuconostoc mesenteroides).
Multifunctional catalyst of Cu/ZnO and molecular sieve for low temperature CO2 conversion to methanol
Authors: Boonamnuay T , Kim-Lohsoontorn P
Published: December 2020

Carbon dioxide (CO2) conversion to methanol is a promising way to mitigated CO2 emission. the Cu/ZnO catalyst applied with molecular sieves was tested on alcohol assisted methanol synthesis at 423 K and 5 MPa. The Cu/ZnO was synthesized by coprecipitation at optimal parameters (precipitation temperature = 333 K, pH = 8) in two different aging time (30min and 1h). The formation of Cu/ZnO was confirmed by XRD technique. The physiochemical properties of Cu/ZnO were analysed by SEM-EDX, N2-adsorption and desorption, and H2-TPR. the Cu/ZnO_1h with a longer aging time showed a larger specific surface area (100.58 m2/gcat) and well dispersion. The effect of molecular sieve was investigated. The molecular sieve only adsorbed the target compounds and did not involve as catalyst in the reaction. Methanol yield increased from 8.5% to 33.6% when Cu/ZnO was loaded with molecular sieve 3Å. The adsorption of water shifted the reaction equilibrium toward to more methanol yield. In contrast, when Cu/ZnO with molecular sieve 5Å was used, methanol yield decreased to 4%. It was likely that methanol product was adsorbed by molecular sieve 5Å and was separated from ethyl acetate which is a by-product.
Cross metathesis of plant oil: A mini review on reaction condition and catalysis
Authors: Thangavel M , Chin S Y
Published: December 2020

The extensive use of the renewable plant oil-derived polyols could be hindered by its low hydroxyl value owing to the oil saturation level and structural limitations. In recent years, olefin cross-metathesis has turn out to be one of the attractive methods to overcome this constraint by redistributing alkenes fragments and regenerating carbon-carbon double bonds in the plant oil. The product distribution of the cross-metathesis of plant oil is significantly influenced by the types of catalysts and olefin as well as reaction conditions. Accordingly, dissimilar from the extensive reviews on the types of bio-based feedstocks and catalysts for cross metathesis, this article evaluates in specific the operating condition of cross-metathesising the plant oils using different olefins and catalysts, aiming to identify the future research avenues in developing a more technical feasible process to value add the plant oil. It is anticipated that the product yield resulted from the cross-metathesis of another potential feedstocks, the palm oil could be increased within a practical timeframe using 1-propene or 1-octene with a temperature not more than 60 °C and catalyst loading in ppm level.
An optimal water regeneration, reuse and resource recovery network integrating domestic and industrial sources
Authors: Misrol M A , Wan Alwi S R , Lim J S , Manan Z A
Published: December 2020

Implementation of reduce, reuse, recycle strategies are pertinent to ensure sustainability. There are studies to minimize freshwater reduction via mathematical modelling method. However, study to explore possibilities of combining both domestic and industrial wastewater regeneration, reuse, and resource recovery in a centralised facility is yet to be made. This study develops a mathematical model that could provide optimal water regeneration and reuse network that also be capable to produce biogas from the selected wastewater streams. The main objective is to maximize profit from the network established. A superstructure that consists of sources, outsource, freshwater, mixers-demands, and biogas systems is developed. A combination of the sources, regenerated sources, outsource water, and freshwater is performed in the mixers. The multi integer non-linear programming (MINLP) model is optimized by BARON solver in General Algebraic Modelling System (GAMS) software. The case study result shows that freshwater water saving is 42% and 377 kW of electricity can be generated from the biogas produced. This offers possibilities to consider the idea of the centralised wastewater facility that considers water regeneration, reuse, and resource recovery for both domestic and industrials sources, as the Eco-Industrial Park (EIP) may serve as the suitable platform.
Study on septic sludge utilization to coordinate with agricultural wastes to produce compost fertilizer
Authors: Tran T , Hong L T A , Kieu N T T , Le D A , Tuong L Q , Tan L V
Published: December 2020

IVietnam, little attention is being paid to the management and treatment of septic tank sludge to take advantage of the number of nutrients in this available resource. This paper presents the potentials and performance of the compost production on the mixing of septic tank sludge and agricultural residues as coffee husk, coconut husk, peat. It added supplementary by 5% bioproducts of Trichoderma sp and 30 ml of molasses in 45days. The results showed the highest quality compost, being mixes of septic tank sludge and coffee husks with total N = 4.01%, total P = 0.41%, total K2O = 3.68% and accepting for the Vietnam standards of fertilizer regulations, resulted also illustrated that E.coli concentration in septic tank sludge sample decreased 2.5 - 3.3 times compared to the previous sample. The second one, the composting efficiency was surveyed on the growth of green mustard plant during 31 days by basal fertilizing and top dressing of this compost at 10 days. The growth of the green mustard plant showed the high compost efficiency septic tank sludge and coffee husk based on 28.21cm of height and 62.5g / plant weight. Especially, NT4 combining from septic tank waste, coffee husk with chemical fertilizers was a good formula by getting the best result in all treatment by combined of compost and chemical fertilizer was at the top dressing period, seems the high compost efficiency in helping Brassica juncea grow well by growing green mustard, being 31.25cm of height and 95.83g / plant weight.
Study on the zeta potential effect of Artocarpus heterophyllus natural-based coagulant in wastewater treatment
Authors: Priyatharishini M , Mokhtar N M
Published: December 2020

The application of chemical coagulants which is damaging to environment and human health has triggered to the exploration of new coagulants from natural based sources. This study emphasized on the performance of a treatment process to remove particles in the synthetic domestic wastewater by coagulation using Artocarpus heterophyllus (jackfruit) peel extract and evaluation of zeta potential (ζ). The measurement of zeta potential which is the criteria defining the electrostatic interaction between pollutants and natural coagulant agent is used in proposing mechanism of coagulation. The jar test experiment was carried out and the treated wastewater was analysed to determine reduction in turbidity, BOD, COD and TSS. The coagulant extracts were characterized in terms of surface charge. The best operating conditions were: pH 2 and dosage 60 mg/L. The corresponding removal efficiencies for turbidity, TSS, COD and BOD were 80 %, 70 %, 46 % and 20 % respectively. The measured zeta potential of the coagulant was -25.2 mV at its original pH, 6.95. On the other hand, the surface charge of synthetic wastewater was positive at pH 2 and later turned to be negative as the pH is increased up to pH 12. This best describes that jackfruit peel coagulant possessed the characteristic of anionic polyelectrolytes which involves bridging mechanism. The results obtained here suggest that coagulation using Artocarpus heterophyllus peel extract can be employed as an effective and low-cost preliminary technique in wastewater treatment process.
Formulation and antioxidant properties of curcumin gum Arabic nanoparticles for delivery to cancer cells
Authors: Hassani A , Hussain S A , Enezei H H , Saeed S , Ibrahim W N , Al-Qubaisi M S , Zentou H , Rosli R , Doolaanea A A
Published: December 2020

Curcumin nanoparticles (Cur/GANPs) were formulated based on gum arabic (GA) as a stabilizer coatings for nanoparticles through efficient synthesis approach. The current study investigated the antioxidant properties and antihypertensive activity of curcumin (Cur) using various established in vitro assays, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) as well as angiotensin converting enzyme (ACE) inhibitory activity. The in vitro cytotoxicity of Cur/GANPs against human liver cancer (HepG2), and colon cancer (HT29) was investigated. The exposure of human cancer cells to Cur/GANPs (1.56-100 µg/ml) using MTT (3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide) has revealed that the Cur/GANPs inhibited the growth of cell lines examined in a dose dependent manner. Hence, Cur/GANPs nanoparticles may have great potential to be applied for cancer treatment.
Investigation of carbonization process parameters to manage Japanese knotweed (Fallopia japonica) in the UK
Authors: Cheok Q , Kuenzel C , Smith S R , Fowler G D
Published: December 2020

Japanese knotweed (Fallopia japonica) is an invasive and destructive floral species in the UK. It causes a significant problem to natural and built environments. Stems and/or rhizomes need to be burned before disposal in order to prevent further propagation [1]. This process has a high carbon footprint and a decrease is favored. Hence, carbonization of Japanese knotweed into char, bio-oil and syngas has been proposed. In this paper, carbonization has been demonstrated to be possible. Japanese knotweed can be separated into 2 main parts: stems and rhizomes. Both parts were characterized for their chemical, physical & thermal properties and subsequently carbonized between 300 to 800°C with the duration held for 1h and 2h. It was found that stable carbonization parameters occurred at 600°C with duration of 1h. At higher temperatures, no further formation of char, oil or gas occurred. The calorific values for Japanese knotweed stem char and bio-oil were 31.2 MJ kg−1 and 13.7 MJ kg−1, respectively, whereas those for Japanese knotweed rhizomes char and bio-oil were 31.7 MJ kg−1 and 23.3 MJ kg−1, respectively. Carbonization may therefore, be a viable bio-fuel option for the management of Japanese knotweed.
Kinetic Model of Moisture Diffusivity in Soursop Leaves (Annona muricata L.) by Convection Drying
Authors: Nhi T T Y , Thinh P V , Vu N D , Bay N T , Tho N T M , Quyen N N , Truc T T
Published: December 2020

Tea is considered to be a product that brings health benefits. The drying process showed high efficiency in processing this product. However, the process of moisture is not qdequately controlled, resulting in wasted energy in the drying process. The dynamics of the drying process of soursop leaves and the effect of temperature on the process speed were assessed in the present study. Five models (Newton, Henderson and Pabis, Page, Logarithmic, and Weibull) were used to determine the suitable drying dynamic at temperatures of 50°C, 55°C, 60°C and 65°C. The mechanism of the processing is based on the principle of dehumidification of the convection drying system with hot air, which caused the moisture inside the material to move outwards. The results showed that the drying temperature is directly proportional to the drying rate of the process, as the increase in drying temperaturefrom 50°C to 65°C produced the link breaking energy and heating thatleads to evaporation. Dehumidification rate depends on the temperature, change in Deff value as 1 x (RTa) -1 from from 9,264 95 × 10−9 m/s2 to 9.76485 × 10−9 m/s2. Page model with determination coefficient R2> 0.99 was found to be the most suitable model for experimental data.
Bare Conductive® role as filler in mechanical and electrical reinforcement of polyvinyl alcohol-based strain sensor
Authors: Abu Kasim N F , Idris W F W , Yusoh K , Ismail Z
Published: December 2020

Polyvinyl alcohol (PVA) is a water-soluble polymer typically suited for food and biomedical applications. However, its non-conductive properties limit PVA potential as material in electronic or sensor-based devices. In order to enhance the electrical as well as mechanical properties of PVA, Bare Conductive ® (BC) paste was incorporated into PVA solution using solution intercalation method. It is discovered that the addition of BC could enhance the mechanical and electrical properties of PVA. The tensile test data showed that the presence of carbon black in BC had resulted in the tensile stress improvement at about 50-170 % as compared to that of the original value. On the other hand, the electrical conductivity of PVA/BC composite film at a higher wt% had demonstrated a significant increment in resistance/length ratio (1.86 kΩ/cm at 0.2 wt%BC).
Preparation of Tamanu Oil Nanoemulsions by Phase Inversion Temperature
Authors: Pham D H , Nguyen T T
Published: December 2020

In this study, the phase inversion temperature (PIT) method was used to prepare a stable tamanu oil nanoemulsion at the lowest surfactant content. The factors affecting the formation of nanoemulsions such as type of surfactant, surfactant to oil ratio (SOR), and water content were investigated. The results showed that Tween 80 is suitable for making a stable nanoemulsion. The SOR is more than or equal to 1.5:1 produced emulsions with particle size less than 100 nm. The particle size decreased as SOR, and water content increased. A higher quantity of surfactant caused higher turbulence and affinity towards the aqueous phase, resulting in smaller droplets. Decreasing droplet size by increasing water content may result from a decreased viscosity of the surfactant at the interface that promotes fluidity and the easy movement of the oil phase towards the aqueous phase. The SOR of 3:1 and water content of 80% were selected due to cost, taste, and toxicity concerns. The impact of storage condition on nanoemulsion stability was also investigated. After one month, samples were stored in the refrigerator had an insignificant increase in absorbance. Particle size analysis also showed a similar result (< 20 nm).
The Kinetic Model of Essential Oil Hydrodistillation from Turmeric (Curcuma longa)
Authors: Pham D H , Le H H N
Published: December 2020

Turmeric is commonly used as a spice, food preservative, coloring agent, and medicine. Turmeric essential oil (EO) is effective in acne treatment, skin lightening, anti-aging, analgesic, and anti-inflammatory. In this study, the kinetic model evaluates variable conditions that affect the hydrodistillation (HD) process. The HD method was chosen because it is easy for industrial-scale applications. The significant HD parameters, including turmeric-water ratio (TWR), heating oil temperature (HOT), and distillation time, were investigated. The highest yield (6.72%) was achieved under the following conditions: the turmeric-water ratio of 1:5, heating oil temperature of 150°C, and distillation time of 4 hours. There have been no studies on the kinetic model of essential oil extraction from turmeric by hydrodistillation. Therefore, three kinetic models were proposed to test for compatibility. The results showed that the two-site desorption model had a better fit than other models. The TWR and HOT had a more significant impact on the cell and tissue alteration of oil glands than the diffusion of essential oil.
Yield and Composition Analysis of Vietnamese Lemon (Citrus aurantifolia) Essential Oils Obtained from Hydrodistillation and Microwave-assisted Hydrodistillation
Authors: Ngo T C Q , Tran T K N , Dao T P , Tran T H , Ngo H D , Huynh X P , Tran T T , Mai H C
Published: December 2020

In this study, the essential oils from lemon (Citrus aurantifolia) peels were extracted using hydrodistillation and microwave-assisted hydrodistillation and their volatile compositions were compared via gas chromatography-mass spectrometry (GC-MS) analysis. Microwave-assisted hydrodistillation (MHD) achieved the oil yield of 2.48% at microwave power of 470W and extraction time of 60 min. The yield obtained using conventional hydrodistillation (HD) was 2.2% at 90 min at 120 °C. GC-MS analysis revealed a total of 17 and 8 components existing in the oil samples produced by MHD and HD methods respectively. The main components shared by both samples were limonene, α-pinene, β-pinene, β-cymene, ocimene, and sabinene. Overall, these results suggest that MHD could produce lemon (Citrus aurantifolia) peels essential oil at a higher yield within a shortened period of time as compared to the traditional HD, thus it could be used as an alternative for HD to reduce costs of the extraction process.
Optimization of genetic algorithm parameter in hybrid genetic algorithm-neural network modelling: Application to spray drying of coconut milk
Authors: Ming J L K , Taip F S , Anuar M S , Noor S B M , Abdullah Z
Published: December 2020

Application of Artificial Neural Network (ANN) and Genetic Algorithm (GA) are to provide an accurate model of the spray drying system. In this study, a comparative study is performed between ANN and GA enhanced ANN to estimate their abilities in emulating the spray drying process of coconut milk powder under restricted parameters. The GA parameter is optimized through response surface methodology (RSM). Through RSM, GA parameter such as population size, mutation and crossover are optimized and is used for the development of GA-ANN network. The optimized GA parameters values are at maximum population size (100), minimum crossover rate (0.2) and maximum mutation rate (1.0). The optimized GA parameters is then applied in the development of the GA-ANN network as the networks applied genetic algorithm to determine the initial weights in its neural network. Both models are then compared by placing importance of highest correlation of determination (R2) and lowest mean square error (MSE) values. The results have shown GA-ANN’s MSE (0.033396) is lower than ANN’s MSE value (0.082263), which the GA-ANN’s R2value (0.88245) is higher than ANN (0.8499). This have shown that GA as a global search technique can be integrated in the development of the ANN.
Magnetohydrodynamic micropolar nanofluid flow over a wedge with chemical reaction
Authors: Zulkifli S N , Sarif N M , Salleh M Z , Samsudin A
Published: December 2020

In this paper, the flow of electrically conducting micropolar nanofluid flow over a wedge with the effect of chemical reaction is considered. A new boundary condition that assumed nanoparticle flux at the surface to be zero is incorporated in this study. This boundary condition is more physically acceptable due to the condition of nanoparticle volume fraction at the boundary that is passively controlled. In order to obtain the numerical solution, a set of similarity transformation variable was applied to reduce the governing non-linear partial differential equations to non-dimensional ordinary differential equations. The following non-linear ordinary differential equations are solved numerically using Runge-Kutta-Fehlberg (RKF45) method. Based on our findings, concentration profile is enhanced with uprising value of chemical reaction parameter.