•The eccentrically stiffened (ES) circular cylindrical auxetic shells.•The nonlinear dynamic and vibration of the sandwich auxetic shells.•The negative Poisson's ratios in auxetic honeycombs core ...layer of the shell.•The shells are resting on elastic foundations and subjected to blast and mechanical loads.•Used Reddy's FSDT, the Airy stress functions, Galerkin method and the fourth-order Runge–Kutta method.
Present research aims to analyse the nonlinear dynamic behavior of eccentrically stiffened (ES) circular cylindrical shells with negative Poisson's ratios in auxetic honeycombs core layer on elastic foundations and subjected to blast and mechanical loads. This study considers a three – layer circular cylindrical shells in which the core layer is the auxetic material with negative Poisson's ratio, and the external layers are reinforced by a system of stiffeners. Based on the analytical solution, Reddy's first order shear deformation theory with the geometrical nonlinear in von Karman and Airy stress functions method, Galerkin method and the fourth-order Runge–Kutta method, out explicit expressions can be determined: fundamental frequency, dynamic response and frequency-amplitude curves. Numerical results are provided to explore the effects of geometrical parameters, material properties, elastic foundations, imperfections, eccentrically stiffeners, mechanical and blast loads on the nonlinear dynamic behavior: fundamental frequency, dynamic response and frequency-amplitude curves.
In this study, we firstly aimed to use Nb as dopant to dope into the TiO
lattice in order to narrow band gap energy or enhance photocatalytic activity of the Nb-TiO
. Then, the prepared Nb-TiO
was ...combined with g-C
N
to establish Nb-TiO
/g-C
N
direct Z-scheme system for superior reduction of CO
into valuable fuels even under visible light. The obtained results indicated that the band gap energy of the Nb-TiO
(2.91 eV) was lower than that of the TiO
(3.2 eV). In the successfully established Nb-TiO
/g-C
N
direct Z-scheme system, the photo-excited e
in the CB of the Nb-TiO
combined with the photo-excited h
in the VB of the g-C
N
preserving the existence of e
in the CB of the g-C
N
and h
in the VB of Nb-TiO
, and thereby, the system produced numerous amount of available e
/h
pairs for the reduction of CO
into various valuable fuels. In addition, the produced e
of the Nb-TiO
/g-C
N
existing in the CB of the g-C
N
, which the potential energy is approximately -1.2 V, would be strong enough for the reduction of CO
to generate not only CH
and CO but also HCOOH. Among established Nb-TiO
/g-C
N
materials, the 50Nb-TiO
/50 g-C
N
material was the best material for the CO
reduction.
The paper adopts the bootstrap procedures for data envelopment analysis to analyze the technical efficiency in the Vietnam's intensive white-leg shrimp farming. The results demonstrate that the null ...hypothesis of constant returns-to-scale is rejected in favor of variable returns-to-scale for the production technology. Moreover, the potential improvement is greater using bootstrapping than that achieved by using the conventional data envelopment analysis, which has been widely adopted in the aquaculture literature for technical efficiency estimation. By adopting the double bootstrap proposed by Simar and Wilson, the bias-corrected technical efficiency is 0.69 and at the 95% confidence interval, with the lower limit of 0.65 and the upper limit of 0.75. In addition, statistically positive influences on technical efficiency in this type of farming are larger farm size and having access to formal credit, with cultivation period in the production year being a negative influence.
The study aimed to determine potential risk factors associated with Premenstrual Syndrome and Premenstrual Dysphoric Disorder.
Three hundred two female student participants who were 18-45 years old ...completed a questionnaire including demographic characteristics, lifestyle factors, and a Vietnamese Premenstrual Syndrome Screening Tool. We then followed up participants during at least two menstrual cycles using the Daily Record of Severity of Problems. The Premenstrual Syndrome and Premenstrual Dysphoric Disorder diagnosis was established using The Carolina Premenstrual Assessment Scoring System, based on the American College of Obstetrics and Gynecology and Diagnostic and Statistical Manual of Mental Disorders.
According to the Carolina Premenstrual Assessment Scoring System, 35 out of 302 students (11.6%; 95%CI: 8.2-15.7%) met the diagnosis of PMS (31 students) or PMDD (4 students). We found that age at menarche (PR = 0.77, 95%CI: 0.63-0.96), having negative Rh blood type (PR = 4.43, 95%CI: 1.95 to 10.08), being moderately depressed or higher (PR = 2.81, 95%CI: 1.24 to 6.36), and consuming caffeine more than three times per week were statistically associated with having Premenstrual Syndrome or Premenstrual Dysphoric Disorder after adjusting for other variables.
The prominent risk factors for Premenstrual Syndrome and Premenstrual Dysphoric Disorder were negative Rhesus blood type, menarche age, caffeine consumption, and self-reported depression.
Aims
Anthrax is reported with frequency but poorly understood in Southeast Asian countries including Vietnam. In Vietnam, anthrax surveillance is national. However, case detection, prevention, and ...control are implemented locally at the provincial level. Here, we describe the epidemiological characteristics, identify spatial clusters of human anthrax, and compare the variation in livestock anthrax vaccine coverage to disease incidence in humans and livestock using historical data in Son La province, Vietnam (2003–2020).
Methods and Results
Most human cases occurred between April and September. Most of the patients were male, aged 15–54 years old. The human cases were mainly reported by public district hospitals. There was a delay between disease onset and hospitalization of ~5 days. We identified spatial clusters of high–high incidence communes in the northern communes of the province using the local Moran's I statistic. The vaccine coverage sharply decreased across the study period. The province reported sporadic human anthrax outbreaks, while animal cases were only reported in 2005 and 2022.
Conclusions
These results suggest underreporting for human and livestock anthrax in the province. Intersectoral information sharing is needed to aid livestock vaccination planning, which currently relies on reported livestock cases. The spatial clusters identify areas for targeted surveillance and livestock vaccination, while the seasonal case data suggest prioritizing vaccination campaigns for February or early March ahead of the April peak. A regional approach for studying the role of livestock trading between Son La and neighbouring provinces in anthrax occurrence is recommended.
Mosquito-borne diseases (MBDs) are causing high morbidity and mortality for humans. Urban livestock keeping is still common in cities around the world. The animals may serve as reservoirs for ...zoonotic MBDs, which increase the risks for humans. Here we assess the knowledge and practices related to MBDs in households with livestock and without livestock and explore the perceptions of the health care sector about MBDs and livestock keeping in Hanoi city of Vietnam in a cross-sectional study. A quantitative survey was conducted including 513 households with and without livestock-keeping in six districts and complemented with qualitative surveys with four health staff from Hanoi Center of Disease Control and three district health centers. The quantitative survey indicated that the participants possessed basic knowledge on MBDs with an average score of 18.3 out of 35, of which non-livestock-keeping households had a better knowledge than households keeping livestock (p<0.05). Both household categories had low score, 3.5 out of 11, regarding preventive practices against MBDs. The negative binomial model showed that occupation and location of living were factors associated to the knowledge on MBDs. Farmers were likely to have better preventive practices as compared to office workers (p<0.05). Those who had better knowledge also had more adequate preventive practices against MBDs (p<0.001). The qualitative survey revealed that livestock keeping was determined as increasing risks of MBDs due to the increase of mosquito population. It is recommended that community campaigns to raise the awareness and change behavior on MBDs should be organized based on collaboration between the health sector and the veterinary sector for households with and without livestock living in central urban and peri-urban areas. Further studies are needed to confirm the association between urban livestock keeping and potential increasing risks of MBDs such as dengue and Japanese encephalitis.
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•A novel hydrothermal route has been developed for the synthesis of MoS2/graphene composite with controllable structures.•The effects of Mo4+-to-C precursor ratios and crystalline ...time on properties of MoS2/graphene were investigated by FESEM, HRTEM, XRD, FTIR, Raman spectroscopy, HAADF-STEM/EDS and HXPES.•The memristive properties of the MoS2/graphenenanocomposite were presented.
In this study, a novel hydrothermal route has been developed for the synthesis of MoS2/graphene composite with controllable structures, in which ammonium molybdatetetrahydrate, as-prepared graphene oxide (GO), and thioacetamide were used as staring materials. Effects of Mo4+-to-C precursor ratios and crystalline time on the structures, components and morphologies of MoS2/graphene were investigated. MoS2/graphene samples were characterized using XRD, FESEM, HRTEM, FTIR, Raman spectroscopy, HAADF-STEM/EDS, HXPES and electrical measurements. The results show that petal-like MoS2 nanostructures with ultrathin petals (~1–10 layers) and coexistence of 1T- and 2H-MoS2 phases can be synthesized on graphene surface in a short time (~2 h). Comparison of crystallization conditions, we found that the crystallization time had a significant effect on the size of the MoS2 nanopetals. The shorter the reaction time is, the thinner the petal-like MoS2 nanoscale is. On the other hand, by adjusting the ratios of Mo4+to C (denoted as: MoS2/C (1:2), MoS2/C (3:2), MoS2/C (2.5:1) and MoS2/C (3:1)), different MoS2/graphene architectures including “sandwich-liked”, “layer–by–layer” and “anchored” can be obtained. On the basis of these results, a possible growth mechanism of MoS2nanopetals on GO was proposed. Interestingly, the as-synthesized material depicts its memristive behavior through the Volt-Ampere characteristics, suggesting a potential application in logic memory devices.
Urban livestock provides an important source of food and income, but it may increase the risks for disease transmission. Vectors, such as mosquitoes, might increase and thereby cause an enhanced ...transmission of infectious diseases, such as dengue fever; considered the most important mosquito-borne viral disease globally. This cross-sectional study evaluated the awareness of dengue fever and investigated how the presence of dengue vectors is affected by the keeping of livestock in urban households in the city of Hanoi, Vietnam. From February to March 2018, during the season of lowest occurrence of dengue in Hanoi, 140 households were interviewed, of which 69 kept livestock. A general trend was observed; respondents living in the Dan Phuong district, a peri-urban district, had better knowledge and practice regarding dengue as compared to the urban Ha Dong district. In total, 3899 mosquitoes were collected and identified, of which 52 (1.33%) were Aedes species. A significant difference between the two districts was observed, with more households in Ha Dong having Aedes spp. mosquitoes (p = 0.02) and a higher incidence of dengue fever (p = 0.001). There was no significant association between livestock-rearing and the presence of Aedes spp. mosquitoes (p = 0.955), or between livestock-rearing and the incidence of dengue fever (p = 0.08). In conclusion, this study could not find any indication that households keeping livestock were at higher risk of dengue virus infections in Hanoi during the season of lowest occurrence of dengue, but clearly indicated the need of more information provided to urban inhabitants, particularly on personal protection.
Adolescents who are willing to perform first aid can help prevent injuries and ultimately death among themselves and others involved in accidents or injuries. This study aims to estimate the ...prevalence of students' willingness to perform first aid procedures and additionally examine associated factors among high school students in Hue, Vietnam. A cross-sectional study utilizing multi-stage stratified random sampling was conducted between April to July 2020 by investigating 798 high school students in Hue, Vietnam. Participants were invited to complete a self-reported questionnaire pertaining to individual demographic characteristics, personal perception of self-efficacy, and willingness to perform first aid. To better interpret these findings, both multivariable linear and Poisson regression models were fitted to evaluate the association between individual student characteristics and the willingness to perform first aid. The prevalence of having willingness to perform first aid (defined as greater than or equal to4 points out of 5 to all three questions) was 49.9% (95%CI:28.6-71.2%). The major reported barriers in performing first aid were fear of making mistakes and hurting victims (34.4%, 95%CI:31.9-37.0%), no prior first aid training (29.8%, 95%CI:25.9-33.9%), and forgetting first aid steps (23.0%, 95%CI:15.8-32.2%). By employing the multivariable linear regression model, it was identified that students with high (beta = 0.614, 95%CI:0.009-1.219) or very high (beta = 1.64, 95%CI:0.857-2.422) levels of self-efficacy appeared to be more willing to perform first aid. Similarly, in the Poisson regression models, compared to neutral students, students who reported high (PR = 1.214, 95%CI:1.048-1.407) or very high (PR = 1.871, 95%CI:1.049-3.337) levels of self-efficacy were more willing to perform first aid. The level of willingness to perform first aid among high school students in this study population was found to be moderate. Therefore, integrating activities to promote self-efficacy in first aid training could be considered a progressive step towards improving a student's willingness to provide such life-saving procedures.
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