Dengue is one of the most dangerous vector-borne diseases transmitted by
mosquitoes. The use of mosquito repellents to protect human hosts and insecticides to reduce the mosquito population is a ...crucial strategy to prevent the disease. Here, we reported larvicidal and repellent activities of
L. essential oil against
, the main vector of the disease. The essential oil was extracted by hydro-distillation from the aromatic plant grown in Vietnam. The yield was 0.67% based on the weight of fresh leaves. The essential oil was analyzed by gas chromatography-mass spectrometry (GC-MS). The main components were menthol (66.04%), menthyl acetate (22.19%), menthone (2.51%), and limonene (2.04%). Toxicity test on
larvae showed that the median lethal concentrations, LC
and LC
were 78.1 ppm (part per million) and 125.7 ppm, respectively. Besides, the essential oil showed excellent repellency on
mosquitoes. At 25%, 50%, and 100% concentration, the respective complete protection times (CPTs) were 45 min, 90 min, and 165 min. When adding 5% vanillin to the essential oil (25%), the complete protection time of the essential oil increased up to 120 min. In conclusion, the EO from
L. has been shown to be a promising natural larvicide and repellent against
mosquitoes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This paper investigates Vietnam’s scientific publications between 1996 and 2013 from Scopus database, focusing on international collaboration. The total scientific output of the country increased ...about 16 publications per year during 1996–2001 and quickly increased 20 % per year during 2002–2013. However, the share of international collaboration was about 77 % of the total output. Biological and agricultural science, medicine dominated the total output, but 80–90 % of these publications are from international collaboration. In contrast, mathematics is the only field that domestic output is larger than collaboration output. Japan is the largest collaborating country, followed by United States, France, South Korea and United Kingdom. Analyzing titles of publications with these collaborating countries, we found high frequency of “Vietnam” or “Vietnamese” words. This result suggested that many study subjects of these research collaborations were from Vietnam. Furthermore, corresponding authors of these research collaborations are mainly from collaborating countries, which suggested that these research collaborations mainly led by foreign authors. Although the total output was quickly increased, especially collaboration output, Vietnamese researchers should be aware about their low contribution to these collaborations.
The k0-standardization neutron activation analysis method has successfully determined the mass fraction of elements of interest using around a hundred analytical radionuclides. However, several very ...short-lived nuclides with half-life less than 100 s have not been used at Dalat research reactor. One of the reasons is that the values of k0-factors of these nuclides are significantly different. Therefore, this work focused on re-determination and evaluation of k0-factors of very short-lived nuclides 110Ag (T1/2 = 24 s) and 46mSc (T1/2 = 18.75 s). The results of determination of the short-lived nuclides revealed that k0-factor of 110Ag is significantly difference between the existing data and the obtained results in this work. The evaluation of the k0-factors was done by using the obtained results for application of k0-NAA for NIST-1566b and NIST-2711A standard reference materials.
As a generation of ‘digital natives,’ secondary students who were born from 2002 to 2010 have various approaches to acquiring digital knowledge. Digital literacy and resilience are crucial for them ...to navigate the digital world as much as the real world; however, these remain under-researched subjects, especially in developing countries. In Vietnam, the education system has put considerable effort into teaching students these skills to promote quality education as part of the United Nations-defined Sustainable Development Goal 4 (SDG4). This issue has proven especially salient amid the COVID−19 pandemic lockdowns, which had obliged most schools to switch to online forms of teaching. This study, which utilizes a dataset of 1061 Vietnamese students taken from the United Nations Educational, Scientific, and Cultural Organization (UNESCO)’s “Digital Kids Asia Pacific (DKAP)” project, employs Bayesian statistics to explore the relationship between the students’ background and their digital abilities. Results show that economic status and parents’ level of education are positively correlated with digital literacy. Students from urban schools have only a slightly higher level of digital literacy than their rural counterparts, suggesting that school location may not be a defining explanatory element in the variation of digital literacy and resilience among Vietnamese students. Students’ digital literacy and, especially resilience, also have associations with their gender. Moreover, as students are digitally literate, they are more likely to be digitally resilient. Following SDG4, i.e., Quality Education, it is advisable for schools, and especially parents, to seriously invest in creating a safe, educational environment to enhance digital literacy among students.
The 2021 IAEA software intercomparison for k0-INAA Blaauw, Menno; D’Agostino, Giancarlo; di Luzio, Marco ...
Journal of radioanalytical and nuclear chemistry,
08/2023, Letnik:
332, Številka:
8
Journal Article
Recenzirano
Odprti dostop
In order to establish the variation between results in mass fractions due to software implementation, as measured by the
k
0
-method for INAA, the IAEA has organized a software intercomparison. A ...complete set of test spectra and associated information was assembled. Efficiency curves, neutron spectrum parameters, correction factors and mass fractions were calculated with the participating programs (k0-IPEN, k0-INRIM, k0-DALAT, k0-IAEA and KayWin) using identical peak areas. In this paper, we report on the observed discrepancies, causes, remedies and future software developments. The test data, as well as intermediate results and observed mass fractions of the certified reference material BCR-320R “channel sediment” are available through the IAEA on request. The variations in concentrations attributed to differences between the programs were initially found to be 5.6 and 7.9%, for certified and uncertified concentrations, respectively. After the certified concentrations had been made available to the participants and they had been allowed to improve their programs, the variations found were 2.7 and 3.4%, respectively. The main identified remaining causes of variation are differences in the procedures used for detector efficiency characterisation and neutron spectrum parameter determination.
Nanoparticles, due to their extensive production and application, can have significant consequences for the environment, including soil and plant pollution. Therefore, it is very important to assess ...how nanoparticles will affect plants depending on the exposure pathways. The effect of gold nanoparticles in a concentration range of 1–100 mg/L on Mentha spicata L. during a 28-day experiment was investigated. Two routes of nanoparticles exposure were applied: root and foliar. Transmission electron microscopy was used to characterize nanoparticles and their effect on plant leaves’ ultrastructure. Gold content in soil and plant segments was determined using k0-neutron activation analysis. For root exposure, gold was mainly accumulated in soil (15.2–1769 mg/kg) followed by root systems (2.99–454 mg/kg). The maximum accumulation of gold in leaves (5.49 mg/kg) was attained at a nanoparticle concentration of 100 mg/L. Foliar exposure resulted in the maximum uptake of gold in leaves (552 mg/kg) and stems (18.4 mg/kg) at the highest applied nanoparticle concentration. The effect of nanoparticles on the Mentha spicata L. leaves’ biochemical composition was assessed. Nanoparticles affected the content of chlorophyll and carotenoids and led to an increase in antioxidant activity. Root exposure to gold nanoparticles resulted in an increase in the number of starch grains in chloroplasts and also suppressed the activity of the soil microbiota. Gold extraction from mint leaves into herbal infusion varied from 2 to 90% depending on the concentration of nanoparticles in the solution and the exposure route. The health risk as a result of gold exposure via herbal tea intake was assessed through estimated daily intake. The hazard quotient values were found to be less than the cutoff, indicating that a cup of tea infusion should not cause a serious impact to human health.
Epithermal Neutron Activation Analysis (ENAA) in which the resonance reactions are utilised by using a cadmium filter to remove thermal neutrons from the reactor spectrum and measuring decay gamma ...rays leads to an improved detection limit for a number of elements with the resonance integrals higher than the thermal cross-sections. A computer program for data processing of the
k
0
-based ENAA has been developed at the Dalat research reactor. The program allows to choose one of the two options of the
k
0
-based conventional NAA or ENAA methods, according to the bare or Cd-covered irradiations, respectively. The NIST SRM 1633b (Constituent Elements in Coal Fly Ash) was used to check the results of the
k
0
-ENAA program in which the samples along with the comparators were packed in Cd boxes for irradiations. The results show that the elements: As, Br, Cd, Ga, Gd, Ho, Na, Sm, Ba, Cs, Eu, Rb, Sc, Se, Sr, Ta, Tb, Th and U, in the NIST SRM 1633b have been determined by the
k
0
-ENAA. The precision of the analytical results obtained using
k
0
-ENAA for the above mentioned SRM is also discussed. The
k
0
-ENAA program has been developed to assist users of the
k
0
-method in NAA to exploit the advantages of ENAA.
The
k
0
-based neutron activation analysis (
k
0
-NAA) and Particle-induced X-ray emission (PIXE) have been performed for 48 automobile window glass samples in forensic applications. A total of 29 ...elements determined by both
k
0
-NAA and PIXE techniques in the glass are: Al, Ba, Ca, Ce, Cl, Co, Cs, Cu, Eu, Fe, Hf, K, La, Mg, Mn, Na, Ni, Rb, S, Sc, Si, Sm, Sr, Tb, Th, Ti, Yb, Zn and Zr. The car glass samples were grouped using Agglomerative Hierarchical Clustering method. Based on dataset of the samples analyzed along with statistical analysis using Principal Component Analysis method, the results of grouping by car brand indicated that the only
k
0
-NAA dataset was well grouped by vehicle maker. Moreover, the Factor Analysis results also suggested that REEs contributed highly to the grouping with percentage variability of 20.88%, on the other hand, the macro elements had a high level of clustering according to the car model from different vehicle makers.
In this study, we measured the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the blood of 9-year-old children living in a dioxin hotspot ...area and a nonexposed area in Vietnam. Forty-five blood samples were collected in the hotspot area while twelve pooled blood samples were collected in the nonexposed area. We found that the dioxin level of children in the hotspot was significantly higher than that of children in the nonexposed area. The total TEQ of PCDD/Fs in the hotspot and the nonexposed was 10.7 and 3.3 pg TEQ/g fat, respectively. However, TCDD, the maker of Agent Orange, was not detected in the blood of children in the hotspot area. In the hotspot area, four congeners 1,2,3,4,6,7,8-HpCDD, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, and 1,2,3,4,6,7,8-HpCDF in mothers' breast milk showed a significantly positive correlation with those in children's serum although the correlations of 1,2,3,7,8-PeCDD and 2,3,4,7,8-PeCDF were not significant. In addition, the duration of breastfeeding also correlates with dioxins in children. These results suggested that children in the hotspot area were exposed to dioxin through mothers' milk and other foods or environmental factors. The present study is the first study that shows dioxin levels in Vietnamese children.
ObjectiveDioxin (polychlorinated dibenzodioxins+polychlorinated dibenzofurans) is one of the most toxic chemical substances known. Although it is suspected to cause endocrine disruption, very few ...epidemiological studies have been carried out on its effects on human steroid hormones. The aim of this study was to elucidate the association of dioxin exposure with steroid hormone levels in the saliva and serum of Vietnamese women.Study designTwo areas, namely Phu Cat (hot spot) and Kim Bang (nonexposed area), were selected for the study. The study subjects consisted of 51 and 58 women respectively. Saliva, blood, and breast milk samples were collected from the subjects in both the areas.MethodsCortisol, cortisone, DHEA, androstenedione, estrone, and estradiol levels in serum and saliva were determined by liquid chromatography–tandem mass spectrometry; dioxin concentrations in breast milk were measured by gas chromatography–mass spectrometry.ResultsDioxin concentrations in the breast milk of women from the dioxin hot spot were three to four times higher than those in the breast milk of women from the nonexposed area. Good correlations were found between the levels of six steroid hormones in saliva and those in serum respectively. Salivary and serum cortisol and cortisone levels in women from the dioxin hot spot were significantly higher than those in women from the nonexposed area (P<0.001) and those in all the subjects were positively associated with dioxin concentrations in Vietnamese women (P<0.01).ConclusionThese results suggest that dioxin influences steroidogenesis in humans. Saliva samples can be used for hormone analysis and are therefore excellent specimens in epidemiological studies.
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