Vietnam Academy of Science and Technology: Journals Online
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Modified techniques in quantification of intracellular Listeria monocytogenes in vitro infection
No full textThe demand for reliable methods for the quantification of intracellular bacteria is growing. Among modern methods such as PCR and flow cytometry, traditional methods including colony forming unit assay and immune-fluorescence are still the two most commonly techniques worldwide. In colony forming unit assay, there are variations among publications, making data results inconsistent across studies. The aim of this paper is to evaluate available techniques and develop improved protocols for the quantification of intracellular Listeria monocytogenes (LM) in vitro infection assay. This study has suggested different uptake time for phagocytic and non-phagocytic cells. Specifically, uptake time was determined at 0.5 hour after infection for RAW264.7 macrophages and 2 hours for L929 fibroblast host cells. To efficiently remove extracellular bacteria during infection period, gentamicin at high and low concentrations was used during the infection assay. High concentration of gentamicin was used to kill extracellular bacteria while low concentration of gentamicin was used to prevent secondary infection of host cells during the infection period. To obtain a more accurate number of alive LM from a large scale experiment, phosphate-buffered saline/PBS should be used rather than mili-Q (mQ) water to lyse the host cell as mQ water can kill additional bacteria unexpectedly. In immune-fluorescence, LM can be visualized by using either the LM expressing green fluorescence protein (GFP) or antibody against LM. To observed GFP signal, cells should be fixed with paraformaldehyde as methanol will rapidly dim the GFP signal. Findings from this study will benefit researchers engaged in both basic cell biology and infectious diseases
Characterization of kappa-carageenan from the red alga Kappaphycus striatum
No full textThe red alga Kappaphycus striatum is an economically important species and extensively cultivated in Vietnam as a material source for carrageenan production. To evaluate carrageenan quality, the characterization of carrageenan extracted from this alga was investigated. As a result, chemical composition of carrageenan consists of 32.4% of 3,6 anhydrogalactose and 24.3% of sulfate. Gelling and metling temperatures are 34.4oC and 55.6oC, respectively. Gel strength of 1.5% is 615 g/cm2 and average molecular weight is about 267 kDa. Furthermore, FT-IR spectrum showed intense absorption bands at 930 cm-1 and 850 cm-1 that attributed to 1,4-linked 3,6 anhydro-α-D-galactose and 1,3-linked β-D-galactose-4-sulfate of kappa-carrageenan, respectively. 13C NMR spectrum indicated the signals for anomeric carbon of β-D-galactose-4-sulfate at 102.6 ppm and anomeric carbon of 3,6-anhydro-α-D-galactose at 95.3 ppm. 13H NMR spectrum showed peak signals at 3.57 ppm and 5.1 ppm that corresponds with O-methyl proton of 1,3-linked 6-O-methyl-D-galactose and α-anomeric proton of 3,6 anhydro-α-D-galactose residues, respectively. The results show that the carrageenan from the red alga Kappaphycus striatus is kappa-carrageenan with the repeating disaccharide unit consisting of 1,3-linked 6-O-methylated, β-D-galactose-4-sulfate and 1,4-linked 3,6 anhydro-α-D-galactose and did not contain iota-carrageenan. Therefore, this alga may promise to be a good source for carrageenan production for application in food or medicine
EVALUATION OF THE CHARACTERISTICS OF PLASTIC EXPLOSIVE ADHERED BY LIQUID NATURAL RUBBER
No full textPlastic explosive (PBX) is an explosive that a polymer binder is used to reduce the sensitivity of high explosives for various applications. This paper presents the characteristics of the PBXs based on liquid natural rubber (LNR) and hexogen (RDX). The PBXs are prepared according to a modified formulation of the Composition C-4. The plasticity of the PBXs is determined according to the MIL-STD-650 method 211.1. The uniaxial compression of the PBXs examined by the STANAG 4443. The test of the sensitivity of PBXs to friction is carried out by STANAG 4487. The thermal stability is tested by the STANAG 4556 at 100 oC for 40 hours. The results indicated that the plasticity is found to be more than 0.018 in accordance with the MIL-C-45010A. Further, the modulus of elasticity, yield strength, and strain can be adjusted by the composition of the LNR binder. In addition, the frictional sensitivity of the PBXs is significantly reduced to more 360 N of the load. The thermal stability is in the range of 0.156 to 0.225 ml.g-1 and completely meets technical requirements. Therefore, the direction of using LNR as a binder for PBXs gives acceptable results for further researches
SET DECIPHERABLE LANGUAGES AND GENERATORS
No full textWe investigate the problem to characterize whether the infinite product of a given language is generated by an -code. Up to now, this problem is open even if language is a finite language.In this work, we consider a class of languages named -set decipherable languages which are very close to the -codes. We solve the problem in the restricted case where is -set decipherable and is the greatest generator of
“Garnierite” in weathering crust of ultramafic blocks from Cao Bang area, north Viet Nam
No full text"Garnierite" is an important group of ore minerals in the supergene nickel deposits. Garnierite group minerals are Ni-bearing hydrous magnesium silicate formed due to the lateritic weathering of ultramafic rocks under humid tropical conditions. In the weathering crust on ultra-mafic blocks Ha Tri and Phan Thanh (Cao Bang province), garnierite group minerals have been found in the saprolite zone or as a coating on the surface of the fissures. Analytical results show that garnierite consists of a mixture of three solid solutions: (i) serpentine-like - 7Ao (lizardite-nepouite), (ii) talc-like - 10 Ao (pimelite-willemseite) and (iii) chlorite-like - 14 Ao (clinochlore-minite). EPMA analysis shows that garnierite in Cao Bang area is characterized by high Ni content (25.50-40.06%), low Fe content (0.09-0.9%) and almost no Al (0.02%), similar to garnierite in the famous nickel mines in New Caledonia, Dominican Republic, etc... Notable, Ni and Mg contents in garnierite show a clear negative correlation, indicating the replacement for each other in the phases. Under the scanning electron microscope (SEM), garnierite has a raspberry shape forming continuous zones covering the unfinished weathered rock surface. These zones represent different stages of garnierite formation. The results of the study allow proposing a model of garnierite formation in the lateritic weathering zone in ultramafic blocks in the Cao Bang area
Study on the association SLC2A9 RS12510549 with uric acid and gout in Vietnamese population
No full textGout is the most common form of arthritis in Vietnam and around the world, caused by an excess of blood uric acid levels. The occurrence of gout is influenced by many risk factors such as diet, living and genetic factors. Studies showed gout is associated with polymorphisms located on genes that encode transport protein channels, including SLC2A9 rs12510549. To evaluate the association of polymorphism SLC2A9 rs12510549 to uric acid levels and gout in the Vietnamese population, we genotyped rs12510549 of 519 subjects (168 gout patients and 351 healthy people) by the PCR–RFLP method. The relationship between genotype distribution, the allele frequency of polymorphism with uric acid levels and gout was assessed through statistical methods. The results show that SLC2A9rs12510549 was in accordance with HWE (p 0.05) and the genotype frequencies of TT, TC and CC were 0.73, 0.25 and 0.02, respectively, confirming the randomness and representation of the study population. The genotype distribution and frequency of the rs12510549 allele were determined unrelated to uric acid levels and gout in the Vietnamese population (p0.05). Further study with a larger sample size should be implemented to confirm our results on the association of SLC2A9rs12510549 and gout in the Vietnamese population
Detection of 16S rRNA and 23S rRNA gene mutations in multidrug resistant Salmonella serovars isolated from different sources using RNA sequencing method
Full text linkThe rapid emergence of resistant bacteria is occurring worldwide. Antibiotic resistance is a serious problem for human beings because pathogenic microorganisms that acquire such resistance void antibiotic treatments. Bacterial antibiotic resistance mechanisms include efflux, reduced influx, modification and degradation of the drug, as well as mutation, modification or overexpression of the target. However, our knowledge as to how bacteria acquire antibiotic resistance is still fragmented, especially for ribosome-targeting drugs. Salmonella is a leading cause of foodborne salmonellosis in the world. The number of antibiotic resistant isolates identified in humans is steadily increasing, suggesting that the spread of antibiotic resistant strains is a major threat to public health. Salmonella is commonly identified in a wide range of animal hosts, food sources, and environments, but our knowledge as to how Salmonella resistance to antibiotics is still fragmented in this ecologically complex serovar. Therefore, the aim of this study was to support for finding novel mechanisms that render bacteria resistant to the ribosome targeting antibiotics, we screen for antibiotic resistant 16S and 23S ribosomal RNAs (rRNAs) in multidrug resistant Salmonella serovars isolated from raw retail meats isolated from Hanoi, Vietnam. Bioinformatic analysis identified 193 unknown novel mutations (64 mutations in 16S rRNA and 129 mutations in 23S rRNA genes). These mutations might play a role in streptomycin resistant in Salmonella serovars. These results suggest that uncharacterized antibiotic resistance mutations still exist, even for traditional antibiotics. This study is only a preliminary kind, further validation before they are applied in Salmonella or other closely related species are required
VOLATILE COMPOUNDS AND BIOLOGICAL ACTIVITIES OF ESSENTIAL OIL OF GLOBBA PENDULA ROXB. COLLECTED AT AN GIANG PROVINCE
No full textTwenty-five compounds were identified from the essential oil of Globba pendula Roxb. by gas chromatography–mass spectrometry (GC-MS) with Selinened- (22.09%) as the main component, followed by Ishwarane (6.52%). The essential oil was found to possess moderate NO inhibitory effect with IC50 of 41.68 ±4.51 µg/ml, significant cytotoxic activity against MCF7 and Hep3B cell lines with IC50 of 28.15±1.08 and 35.24±0.06 (µg/ml), respectively. This is the first report on volatile compounds and biological activities of essential oil of Globba pendula Roxb. collected at An Giang province, Vietnam
REMOVAL OF NICKEL, COPPER, AND ZINC IONS FROM AQUEOUS SOLUTION USING COFFEE BEAN HUSK (CFH)
Full text linkAgricultural waste has been received much attention for its potential of being efficient and low-cost adsorbents to remove heavy metals from water. This paper presents a batch investigation of the potential of an adsorbent produced from coffee bean husk for removing copper, nickel and zinc ions from aqueous solution. At the initial pH of 5.0, a dose of 10 g/L, initial concentration of 50 mg/L, shaking speed of 100 rpm, particle size of 0.6-1 mm and at 25oC, the removal of nickel, copper, and zinc ions reached 95% and the highest adsorption capacity of coffee bean husk approached 23, 32, 22 mg/g, respectively. The adsorption isotherm of these ions preferred to the Freundlich isotherm with the relative coefficient R2 equal and or greater than 0.98. Thus, an initial conclusion drawn from the study was that coffee bean husk could potentially be as an effective and economical adsorbent for removing nickel, copper, and zinc ions from the aqueous solution
MECHANICAL, THERMAL PROPERTIES AND MORPHOLOGY OF COMPOSITE COATING BASED ON ACRYLIC EMULSION POLYMER AND GRAPHENE OXIDE
Full text linkStudied results showed that graphene oxide (GO) had insignificant effect on adhesion of composite coating while graphene oxide improved abrasion resistance of composite coatings. The abrasion durability of studied coatings increased with GO ratio rising to 0.5% and then abrasion resistance of coatings decreased with GO ratio continuous growing up. SEM images witnessed that GO dispersed well into polymer matrix if GO weight ratio was 0.5%. TGA results also illustrated that thermal property of GO composite was better than that of neat coating