During the era of COVID-19 (COronaVIrus Disease of 2019), telework has been adopted extensively in developing countries for the first time. This study analyzes data of 355 teleworkers in Hanoi ...(Vietnam) during April 2020, the period of social distancing, to examine various factors associated with (1) complete home-based telework (HBT), (2) the perception of HBT, and (3) the attitude toward the combination between HBT and conventional work at workplace post-COVID-19. It finds that the company’s closure policy and the frequency of working from a distance before the social distancing period were the primary determinants of exclusively teleworking. Regarding the perception of HBT, while the fear of COVID-19 was a strong positive factor, difficulties in focusing on work and accessing data were negative factors. Regarding the attitude toward the future development of HBT, attitudinal factors, commute distance, gender, children in household, and the perception of HBT in the social distancing period were the main predictors. The presence of more than one child negatively affected the perception of telework but positively affected the attitude toward establishing the hybrid work mechanism. The findings suggested that HBT has the potential to alleviate traffic congestion in developing countries and it can be promoted by emphasizing its environment-related benefits. The sample used in this research was collected in the initial stage of constrained mobility and it was not well representative; therefore, this study serves as a proof of concept for ongoing wider analyses on HBT post-COVID-19 or in the subsequent lockdown periods.
The pathogenesis of severe dengue is not well understood. Maternally derived subneutralizing levels of dengue virus-reactive IgG are postulated to be a critical risk factor for severe dengue during ...infancy. In this study, we found that, in healthy Vietnamese infants, there was a strong temporal association between the Fc-dependent, dengue virus infection-enhancing activity of neat plasma and the age-related epidemiology of severe dengue. We then postulated that disease severity in infants with primary infections would be associated with a robust immune response, possibly as a consequence of higher viral burdens in vivo. Accordingly, in infants hospitalized with acute dengue, the activation phenotype of peripheral-blood NK cells and CD8+ and CD4+ T cells correlated with overall disease severity, but HLA-A*1101-restricted NS3133–142-specific CD8+ T cells were not measurable until early convalescence. Plasma levels of cytokines/chemokines were generally higher in infants with dengue shock syndrome. Collectively, these data support a model of dengue pathogenesis in infants whereby antibody-dependent enhancement of infection explains the age-related case epidemiology and could account for antigen-driven immune activation and its association with disease severity. These results also highlight potential risks in the use of live attenuated dengue vaccines in infants in countries where dengue is endemic.
•Ag/rGO was successfully synthesized by co-precipitation.•L-ascorbic acid (environmentally friendly and abundant) was used as the reducing agent.•AgNPs with size 16 ± 3.7 nm were decorated on ...rGO.•Amount of reducing agents and catalysts, reaction time and type of dye significantly affect the antibacterial activity.•Ag/rGO effectively inhibited the development of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.
The present study involved the preparation of silver-reduced graphene oxide (Ag/rGO) using co-precipitation method. The characteristics of Ag/rGO were confirmed by X-ray Diffraction patterns, Fourier transformation infrared spectroscopy, Raman spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller specific surface area, scanning electron microscopy, and energy-dispersive spectroscopy. The results demonstrated that silver nanoparticles (AgNPs) having diameter of 16 ± 3.7 nm were uniformly integrated on reduced graphene oxide (rGO) The as-synthesized Ag/rGO had a specific area of 54m2/g and 67.36 wt% silver. Antibacterial and catalytic properties of Ag/rGO were then further investigated. Ag/rGO was found to effectively inhibit the developing of gram-negative and gram-positive bacteria such as Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa with the bactericidal rates of 89.35, 95.67, and 99.99 %, respectively. In addition, the catalytic property of Ag/rGO in the reduction of organic dyes was tested with different dosage of reducing agent, amount of catalyst, type of dye, and reaction time. More than 99 % of dyes in aqueous solution at 20 mg/L concentration were reduced after 30 min with amounts of Ag/rGO and sodium borohydride of 10 and 30 mg successively. All results confirmed the potential application of Ag/rGO in the treatment of infected water and dye contamination.
The pathogenesis of dengue in infants is poorly understood. We postulated that dengue severity in infants would be positively associated with markers of viral burden and that maternally derived, ...neutralizing anti-dengue antibody would have decayed before the age at which infants with dengue presented to the hospital. In 75 Vietnamese infants with primary dengue, we found significant heterogeneity in viremia and NS1 antigenemia at hospital presentation, and these factors were independent of disease grade or continuous measures of disease severity. Neutralizing antibody titers, predicted in each infant at the time of their illness, suggested that the majority of infants (65%) experienced dengue hemorrhagic fever when the maternally derived neutralizing antibody titer had declined to <1:20. Collectively, these data have important implications for dengue vaccine research because they suggest that viral burden may not solely explain severe dengue in infants and that neutralizing antibody is a reasonable but not absolute marker of protective immunity in infants.
•The agricultural transformation timeline of the Mekong delta is developed.•Drivers of transformation are found in groups: Price, Producer, Place and Policy.•A transformation framework using value ...chain and agribusiness concepts is proposed.
Drivers of agricultural transformation vary from place to place. They need to be explored, especially under the new context of changing climate, environment and socio-economic development in coastal regions. This paper aims to discover the drivers of change through an analysis of the agricultural transformation process in the Vietnamese Mekong delta and then develop a framework for the next steps to meet sustainable development objectives. A mixed approach of qualitative and quantitative methods was applied to collect primary and secondary data. Major techniques used in data collection consist of Key Informant Interviews (KII), Focus Group Discussions (FGD) and household surveys with 203 farmers in three coastal provinces, including Ben Tre, Kien Giang and Soc Trang. The results showed that the agricultural sector has been transforming towards the diversification of crops and livelihoods. For example, there has been a shift from rice monoculture to integrated farming systems (i.e. rice-shrimp or grass-cattle) and a move from on-farm to more off-farm or non-farm incomes. This transformation was found to be driven by many factors that can be categorised into the ‘4Ps of change’, consisting of the Price, the Producer, the Place and the Policy. The 4Ps of change are not isolated but interrelated. Then, considering the 4Ps of change, a holistic framework for sustainable agricultural transformation (SAT) has been developed. What distinguishes this SAT framework from others is a combination of value chain theory and agribusiness concepts. Hence, it would create resource use efficiency, add more value to products, deliver healthy food and contribute to successful transformation in the future. Successful implementation would need the government’s readiness to provide a practical legal framework and efficient support to motivate all actors involved in the transformation process.
High-performance methane gas sensors were developed from Ni2O3-decorated SnO2 semiconducting films. The SnO2 film was fabricated by the sputter deposition of Sn metal followed by oxidation. Ni ...nanoparticles were then deposited onto the SnO2 film by the arc discharge deposition of single-wall carbon nanotubes followed by the burning out of carbon nanotubes. The catalytic Ni nanoparticles distributed in the carbon nanotubes were oxidized to Ni2O3. The surface morphology and structural properties were examined by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The methane gas sensing properties were examined at different operation temperatures with SnO2 thickness and Ni2O3 quantity as variables. The synergetic effects induced by the Ni2O3-decoration including enhanced response and lowered operation temperature were observed. We also report very high sensor responses. The sensing mechanism of the hybrid sensor structure was also discussed.
In this study, the zinc oxide-decorated graphitic carbon nitride composite (ZnO/gC3N4 – ZCN) was synthesized for photocatalytic degradation of organic dyes in aqueous media. Particularly, ZnO was ...fabricated by the calcination method with the assistance of Garcinia mangostana pericarp extract as a stabilizer and reducing agent, while graphitic carbon nitride (gC3N4 – CN) was prepared by the calcination method and exfoliated using a strong oxidizer mixture. Characterization results showed ZnO possesses a spherical shape with an average diameter of 30–80 nm and is distributed evenly on the CN sheets. Subsequently, ZCN was subjected to photodegradation towards methylene blue (MB), which indicated that under optimal conditions of 50 mg of catalyst, pH 9, and 10 mg/L of MB concentration, the overall efficiency reached up to 99.16 % after 180 min of visible irradiation. Additionally, ZCN also possesses the degradation ability for other organic dyes, for instance, malachite green (MG) and methyl orange (MO) with an overall efficiency of 96.42 and 57.57 %, respectively. Moreover, the radical scavenging experiments elucidated that the major responsible component for the photodegradation was the photogenerated holes, while other radicals also facilitated the process. Besides, the reusability of the material was excellent as only 10 % of the yield decreased after five cycles. The aforementioned findings reveal the notable potential applications of the ZCN material in the environmental remedial field.
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•The ZnO/gC3N4 composite was biosynthesized with the aid of sonication.•The spherical ZnO distributed evenly on the gC3N4 exfoliation sheet.•The composite exhibited great methylene blue photodegradation under visible light.
Diterpenes that were isolated from
Crossopetalum gaumeri
(Loes.) Lundell (Celastraceae) plants are reported to exhibit a range of biological activities, in particular as radical scavengers. Thus ...further insight into the antioxidant activity of diterpenes in physiological environments is much needed but not studied yet. In this study, the antioxidant activity of nine natural diterpenes was evaluated using kinetic and thermodynamic calculations. It was found that the sequential proton loss electron transfer (SPLET) mechanism is favored in polar environments, whereas formal hydrogen transfer (FHT) is the main pathway for the radical scavenging of these diterpenes in the gas phase as well as in lipid media. The rate constants for the HOO&z.rad; radical scavenging of these compounds in the gas phase, polar and nonpolar solvents are in the range of 2.29 × 10
−2
to 4.58 × 10
7
, 9.74 × 10
−3
to 1.67 × 10
8
and 3.54 × 10
−5
to 1.31 × 10
5
M
−1
s
−1
, respectively. 7-Deoxynimbidiol (
6
), exhibits the highest HOO&z.rad; radical scavenging with
k
overall
= 1.69 × 10
8
M
−1
s
−1
and 9.10 × 10
4
M
−1
s
−1
in water and pentyl ethanoate solvents, respectively, that is about 1300 times higher than that of Trolox in polar environments. It is thus a promising natural antioxidant in physiological environments.
Diterpenes that were isolated from
Crossopetalum gaumeri
(Loes.) Lundell (Celastraceae) plants are reported to exhibit a range of biological activities, in particular as radical scavengers.
•A facile manufacturing process of new Rb2CO3-decorated In2O3 sensor.•The Rb2CO3/In2O3 composite sensor detecting 100 ppb level NO2 gas at room temperature under visible light illumination.•Propose ...the mechanism for the high sensing performance realized by high rate of electron supply to the receptor.•Good sensing performance of high selectivity, stability, repeatability, linearity, with discussion of the humidity effect.
The Rb2CO3-decorated In2O3 sensor is prepared for detection of NO2 at room temperature under light irradiation. Physical and chemical properties of the materials and structures are thoroughly investigated by various analytical tools of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy, thereby confirming the formation of the Rb2CO3/In2O3 p-n junction at the interface. The Rb2CO3-decoration effect on In2O3 sensor is examined under light irradiation of different wavelengths and intensities. Rb2CO3-decoration exhibits much higher sensing performance than pure In2O3 sensor, and furthermore, the visible light irradiation improves in the response level and sensing kinetics. The sensor detects less than 100 ppb NO2. In addition, the Rb2CO3-decorated In2O3 sensor shows high selectivity, stability, repeatability, and linearity. The ultimate performance of the nanostructured sensor is elucidated by the depletion model of the conduction type gas sensors. The effect of humidity on the sensing performance is also investigated.
•Ag/GO was successfully synthesized by co-precipitation.•LAA was used as a reducing agent, which is easy to find, and eco-friendly.•AgNPs with size 17.65 ± 4.76 nm were decorated on GO.•Concentration ...and contact time significantly affect the antibacterial activity.•The antibacterial activity of Ag/GO increased when pH value was decreased.
Herein, silver/graphene oxide (Ag/GO) nanocomposite was fabricated by co-precipitation with green reducing agent and then was characterized with modern analytical techniques. The antibacterial activities were conducted via the effects of Ag/GO concentration, time, and pH. Results show that silver nanoparticles were uniformly distributed on the GO sheets nanosized of 17.65 ± 4.76 nm. The antibacterial performance was optimized at pH 5.6, eradicating P. aeruginosa in 180 min at 50 µg/mL Ag/GO concentration and S. aureus in 480 min at 300 µg/mL Ag/GO. This demonstrates the potential of Ag/GO as an antibacterial nanocomposite material.
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