Vietnam Academy of Science and Technology: Journals Online
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HO production in Lactobacillus strains isolated from the intestinal microbiome of healthy people
Get PDFLactobacillus sp. in the digestive tract are capable of producing H2O2 to inhibit the growth of harmful bacteria and balance the gut microflora. In this study, we have isolated 115 strains of Lactobacillus spp. from stool samples of healthy people in Ha Noi. Of the 50 tested Lactobacillus strains, 9 strains were capable of producing H2O2, of which the Lac.VFE-14 strain produced highly H2O2 with a concentration of 2.183 mM, followed by Lac.VFE-08 strains (2.081 mM) and Lac.VFE-04 (2.067 mM). All three strains grew well in MRS medium supplemented with bile salts or adjusted to low pH value. With 0.3% of bile salt, the survival rates of these 3 strains were 99%, 95% and 97%, respectively. At pH 3.0, after 3 hours of cultivation, the survival rates of the three strains were 98.54%, 94.15% and 95.27%, respectively. In addition, each of the cell-free culture supernatants of these three strains that inhibit the growth of S. aureus ATCC-23235. The inhibition zone diameters of the three strains were 19.0±1.0 mm, 14.0±1.0 mm and 11.7±1.3 mm, respectively. The results of 16S rRNA gene analyses showed that Lac.VFE-14, Lac.VFE-08 and Lac.VFE-04 had high similarity scores with L. plantarum ZZU 23 (100%), L. rhamnosus JCM 1136 (99%) and L. plantarum S7 (98.65%), respectively. This study indicates that all three strains have the potential to be used as probiotics in the future.
The impact of intraspecific competition on tree growth in planted Korean pine forest
Get PDFThe aim of this study was to explore the correlation of competition indices (CIs) on individual tree growth for Korean pine (Pinus koraiensis) plantation using partial correlation analysis and generalized linear models. The data were collected from 15 permanent plots in Mengjiagang forestry farm, Northeast China. The results showed that the distance dependent CIs have a higher predictive capacity for individual growth of pine trees. The control index of competitive trees number (CI1) combined with the selection fixed competitor trees (M2) was found to be the most well correlated competition measure with five - years diameter increment. Thus, the competition index (CI1- M2) was recommended for developing individual tree growth models. The subject tree diameter at breast height, crown width, height to crown base, tree volume and basal area all showed a significantly linear correlation with tree competition intensity (P 0,05). Diameter at breast height, crown width, tree volume and basal area all decreased with increasing competition intensity, whereas the height to crown base increased. There was no significant relationship between competition intensity and tree height (P 0,05). The optimal model of predicting individual growth with logarithm of diameter at breast height and CIs as the independent variables due to the best fitting performance. This results also showed considerable improvement in predicting individual tree periodic growth when including competition indices that the mean absolute error is reduced in the range of 22−25%.
Chemical composition and antimicrobial activity of the essential oil from twigs and leaves of Magnolia macclurei (Dandy) Figlar from Ha Giang Province, Vietnam
Get PDFThe chemical composition of the essential oil obtained by hydrodistillation of the twigs and leaves of Magnolia macclurei collected in Hoang Su Phi, Ha Giang Province, Vietnam was analyzed using GC/MS. A total of 38 compounds were detected in essential oil, accounting for 94.49% of the oil, in which 37 compounds were identified accounting for 93.33%. cis-β-Elemene (14,30%), bicyclogermacrene (18,57%), and 10-epi-ᵧ-eudesmol (16,86%) were the main components of essential oil. The minor components present with rather high amount were: Germacrene D (2,12%), guaiol (8,52%), hinesol (2,34%), valerianol (6,76%), and bulnesol (2,93%). Antibiotic activity of the essential oil sample was tested against a Gram positive bacteria Staphylococcus aureus, a Gram negative bacteria Escherichia coli, and a yeast Candida albicans using an agar disk diffusion method. All three microorganisms tested are resistant to the oil from twigs and leaves of M. macclurei. That is exhibited through the inhibitory zone diameters ranging from 4 to 12 mm
SOME STATISTICAL TECHNIQUES APPLIED TO ENGINEERING MECHANICS PROBLEMS
Get PDFThis article deals with statistical techniques normally used in Engineering. Variables or parameters in models of Engineering Mechanics always face data: a) of materials (with technical specification); b) of analysing model using specific software; c) of measurement using variety of devices and approaches; and d) of the technology process of manufacture (outcome). An engineering object to be studied has k variables and each variable has m values or level of status, it will need mk cases to be solved. This has to conduct a very large number of test cases to be solved for target objective(s). A Taguchi Method will be applied for finding solution in which much less effort of computation is paid and other different conditions of noise could be taken into account. Besides, other statistical tools, ANOVA have also proved to be useful in quantifying uncertainties in engineering problems, both in aleatory (nature) and epistemic (knowledge and measurement) categories. A typical example of engineering problem is chosen to study using above-mentioned Taguchi method and statistical tools. This method is very useful for design of experiments, both in traditional laboratory and computer numerical modeling and it can used to optimize the set of input data for obtaining the best results of outcome product
Applications of fluorescence in situ hybridization (FISH) in genome research
No full textFluorescence in situ hybridization (FISH) technique enables the direct detection of DNA sequences inintact cellular materials (e.g. individual chromosomes in metaphase spreads). This review article focuses on theapplications of FISH in genome research, including validation and correction of the genome assembly from thenext-generation sequencing (NGS) projects. DNA probes for specific DNA fragments of the assembly can beobtained from PCR amplicon or cloned products using different vector systems. Localization of these probeson their respective chromosomal regions can be visualized by FISH, providing useful information to crosscheckthe assembly data. Furthermore, the recent refinements in the FISH technology including using smartpooling scheme of differently colored DNA probes, together with consecutive FISH experiments (stripping andreprobing of the same slide) are described. These advances in multicolor FISH can provide crucial linkageinformation on association of linkage groups and assembly scaffolds, resulting in so-called cytogenetic maps.Integration of the cytogenetic maps and assembly sequences assists to resolve the chromosome-level genomeassembly and to reveal new insights in genome architecture and genome evolution. Especially, comparativechromosome painting with pooled DNA probes from one reference species can be used to investigate ancestralrelationships (chromosome homeology and rearrangements) among other not-yet-sequenced species. Inaddition, FISH using DNA probes for certain specific classes of repetitive DNA elements as well as for basicchromosome structures (e.g. centromere or telomere DNA repeats, ribosomal DNA loci) can be used to studythe genome organization and karyotype differentiation. We also discussed about limitations and futureperspectives of the FISH technology
Angiotensin-converting enzyme inhibitory and antibacterial activities of low molecular weight peptides derived from spent brewer’s yeast
No full textAccording to the World Health Organization (WHO), hypertension is one of the most common chronic diseases. Cardiovascular disease causes 17.5 million deaths each year, in which hypertension is a direct cause to the death of up to 40%. This hypertension is caused by angiotensin-converting enzyme (ACE). ACE inhibitors consider as an effective therapy in hypertension treatment.Many ACE inhibitors are synthesized by chemical pathways to control high blood pressure, however, these drugs often cause side effects. Therefore, in the last two decades, many authors have been interested in studying and producing a variety of ACE inhibitory peptides, which are naturally derived (plants, animals, and microorganisms) that help reduces blood pressure and less cause side effects. On the other hand, biologically active peptides that are resistant to pathogenic bacteria are also of special interest. In this study, we refer to the limited hydrolysis of spent brewer's yeast by proteases to collect peptides with a molecular size of ≤ 10, 5 and 3 kDa. Peptide fraction with molecular size ≤ 10 kDa have ACE inhibitory activity. The results showed that smaller peptide fractions had higher ACE inhibitory activity. At concentration of 30 µg/mL, inhibitory activitiy of peptides with molecular sizes ≤ 10, 5, 3 kDa was 16.3, 27.7 and 32.7%, respectively, and the best IC50 was 48,85 µg/ml. The lowest peptide concentration for completely inhibition bacteria after 24 h of incubation was 30 mg/mL (V. cholerae), 35 mg/mL (E. coli) and 50 mg/mL (S. typhi)
FLAVONOIDS FROM FLOWERS OF AMESIODENDRON CHINENSE (SAPINDACEAE)
No full textFrom the flowers of Amensiodendron Chinese (Merr.) Hu, six known flavonoids, (-)-catechin (1), (-)-epi-catechin (2), chrysoeriol (3), quercetin-3-O-β-D-glucopyranoside (4), astragalin (5) and kaempferide-3-O-β-D-glucopyranoside (6) were isolated. Their chemical structures were elucidated by analysis of the physicochemical parameters, the NMR and mass spectral data, and comparison with those reported in the literatures
REMOVAL OF POLLUTANTS FROM DISPERSE BLACK DYE WASTEWATER BY MUCILAGE FROM DRAGON FRUIT PEEL
No full textApart from the large revenue, the textile industry in general and the dyeing process in particular are releasing huge amounts of wastewater that pollutes the environment and adversely affects human health. Treatment of this type of wastewater by coagulation and flocculation process requires lots of synthetic chemicals, implying a chemical hazard. Thus, this study evaluated the efficacy of mucilage extracted from the peel of dragon fruit (Hylocereus undatus) towards partly substitution of Poly Aluminium Chloride (PAC) used in coagulation and flocculation process for removal of turbidity and other pollutants from disperse black dye wastewater. The effects of pH, settling time, coagulant dosage and mucilage dosage on removal of turbidity, chemical oxygen demand (COD) and color, etc. were analyzed based on Jar-tests. The results showed that the addition of mucilage at 10 mg/L after PAC at 245 mg/L under optimal pH 7 and settling time 40 minutes removed turbidity up to 94.92%. The amount of PAC used was 3-10% less compared to total PAC needed for obtaining equal efficiency when used alone. The pollutant removal by mucilage was also comparable to Polyacrylamide (PAM) – a synthetically organic flocculants
Synthesis and investigation of a novel nanocomposite for improved solar radiation absorbance of MD membranes
No full textMembrane distillation (MD) has emerged as a promising technology for seawater desalination to provide drinking water. The most considerable advantage of MD is the capacity to utilize thermal energy to reduce the energy cost of the solar-driven MD seawater desalination systems. However, limited thermal efficiency is one of the key challenges that prevent the wide application of MD for seawater desalination. Due to low thermal efficiency, most solar-driven MD systems require large and complex arrays of solar thermal collectors, leading to the significantly high investment costs of the MD systems. MD membranes coated with solar radiation absorbing materials have been proposed for the solar-driven MD process to obviate the need for large arrays of solar thermal collectors. In this study, we synthesized a novel black spinel-carbon nanocomposite for MD membrane coating to improve the solar radiation absorbance of the membrane, thus enhancing thermal efficiency of the MD system. The preliminary experimental results demonstrated that the black spinel-carbon nanocomposite could absorb light at a wider wavelength range from visible to far-red; therefore, they exhibited increased solar radiation absorbance and hence heating efficiency compared with single materials
Correlation of trace element composition of oils and other caustobiolites with chemical content of different types of biota and the Upper, Middle and the Lower Earth's Crust
No full textThe trace element (TE) content of oils is known to have a polygenetic character and to be inherited from an organic matter, surrounding rocks and from formation waters. The presence of some TEs indicates the involvement of the deep source, at least from the Lower Crust. However, these conclusions have a qualitative character. We present the results of the correlation analysis of TE content of oils with the chemical compositions of the Upper, Middle, and Lower Crust, with different types of organic matter, clays, and causetobiolites. A logarithmic instead of a linear scale for TE concentration values are used in calculations because the examining values change by several orders of magnitude. The TE compositions of clays, coals, and shales correlate better with the composition of the upper continental crust and an organic matter. In contrast, the TE contents in the majority of oils correlate stronger with the Lower crust, which indicates a significant contribution from the Lower continental crust. This finding points to the role that the uprising flow of fluid plays in the process of the formation of oil. Only young oils from Kamchatka and from White Tiger huge oil fields indicate a better correlation with the Upper crust. This finding is explained by the lower depth of formation of the uprising flow of deep waters because of higher deep temperatures in Kamchatka and in the White Tiger oil field area. The obtained trend of change of TE content in clays and different caustobiolites oils including is interpreted as a mixing line between the subsurface end member (which is characterized by high correlation with the chemical content of the Upper crust and biota) and the deep end member (high correlation with the chemical content of the Lower crust)