Herein, Cu was incorporated into ZnO lattice to reduce its band gap as well as to extend its visible radiation response. The obtained Cu-ZnO was continuously integrated with g-C3N4 to create ...Cu-ZnO/g-C3N4Z-direct scheme photocatalyst for advanced atrazine removal. Radical scavenging experiments have been also conducted to clearly figure out photocatalytic mechanism for degradation of atrazine by the synthesized photocatalyst. The synthesized Cu-ZnO only utilized the generated h+ for atrazine degradation (direct and indirect via formation hydroxyl radicals (•OH)) and the g-C3N4 only utilized the generated e− for atrazine degradation (indirect via reaction with O2 to form superoxide anion, which needed to continuously react with H2O to form •OH). Therefore, the photocatalytic atrazine degradation by synthesized Cu-ZnO material was greater than that by synthesized g-C3N4 material. Cu-ZnO/g-C3N4 utilized both generated e− and h+ for degradation of atrazine. Thus, the photocatalytic atrazine degradation by the synthesized Cu-ZnO/g-C3N4 was greater than those of single g-C3N4 or Cu-ZnO materials. Finally, the conducted recycling experiments indicated great stability of synthesized Cu-ZnO/g-C3N4 during long-term atrazine degradation process opening new era for application of the material in practical systems.
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•Cu doped into ZnO lattice to reduce its band gap and to extend its visible radiation response.•Cu-ZnO was successfully combined with g-C3N4 to establish Z direct scheme system.•Z-scheme prevented fast recombination of e− and h+ and maintained their re-dox potential.•The Cu-ZnO/g-C3N4 utilized both generated e− and h+ for degradation of atrazine.•The Cu-ZnO/g-C3N4 showed excellent activity and stability during long-term photocatalysis.
The current study reports the preparation and investigation of several Pt-based anode catalysts loaded on reduced graphene oxide (rGO) as electrocatalysts in both acid and alkaline media for ethanol ...electrooxidation. The synthesized catalysts are evaluated by the method of XRD, Raman spectroscopy, XPS and TEM. Electrocatalytic properties of these catalysts for ethanol oxidation were investigated by cyclic voltammetry and chronoamperometry. It was found that the as-prepared nanocatalysts doped by metals and oxide metals showed the improvement of catalytic performance compared to Pt-only supported on graphene catalyst. The results indicated that the presence of Al favoured Pt nanoparticles dispersing on the surface of rGO sheets. Indeed, the PAG catalyst exhibits the highest mass activity for the ethanol oxidation of 1194 mA mg−1Pt in acid medium and 3691 mA mg−1Pt in alkaline medium. In addition, the PAG catalyst also shows good antipoisoning ability for ethanol electrooxidation in both media. This catalyst could be a potential catalyst for direct ethanol fuel cell (DEFC).
•Graphene-supported Pt-based multimetallic catalysts were successfully synthesized.•Electrocatalytic performances of catalysts were examined in acid and alkaline media.•Catalyst containing Pt and Al shows the best electroactivity for ethanol electrooxidation.•Promotion effect of catalysts should be attributed to the presence of AlOOH.•Durability of PtAl-based catalyst was evaluated in both media.
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.
In the study, we used two conducting polymers, polyaniline (PANI) and polypyrrole (PPy), to sensitize Ta3N5, thereby enhancing its photocatalytic activity, and then applied this novel photocatalyst ...to overall water splitting to produce hydrogen and oxygen even under visible light irradiation. The two polymers increased the charge transfer efficiency, prevented the recombination of the generated electrons and holes of the Ta3N5 photocatalyst, and thereby enhanced its electron-hole separation efficiency and improved its photocatalytic activity for efficient visible light water splitting. The two polymers completely covering the Ta3N5 particles facilitated charge transfer for quick migration of the generated electrons and holes to the polymer surface and thus prevented contact between the holes and nitride of Ta3N5. Therefore, these conducting polymers also protected the Ta3N5 particles from self-photocorrosion during long-term water splitting. Because of the existence of the protonated nitrogen (-N+) state in PPy, the electric conductivity of PPy was lower than that of PANI, which lowered the sensitizing ability of PPy compared to that of PANI. Thus, the water splitting efficiency of Ta3N5/PANI was higher than that of Ta3N5/PPy. The production rates of H2 and O2 generated from water splitting of Ta3N5/PANI were 60.5 and 30.2 (μmol. g−1cat. h−1), respectively.
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•Polymer sensitizers enhanced the separation of e−/h+ pairs and prolonged the Ta3N5 lifetime.•Polymer cover protected Ta3N5 from self-photocorrosion (oxidation of generated holes).•Ta3N5/polymers greatly exhibited overall photocatalytic water splitting.•Lower electric conductivity lowered the sensitizing ability of the polymer.•PANI was better than PPy for enhancing the photocatalytic activity of Ta3N5.
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.
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.
Bioactive-guided phytochemical investigation of
L. growing in Vietnam led to the isolation of five
-atisanes, one
-
-atisane, and one lathyrane (ingol-type). The structures were elucidated as
-1
3
16
...17-tetrahydroxyatisane (
), ethyl
-3,4-
-4,16
,17-trihydroxyatisane-3-carboxylate (
),
-atisane-3-oxo-16
,17-acetonide (
),
-3
-acetoxy-16
,17-dihydroxyatisane (
),
-16
,17-dihydroxyatisane-3-one (
), calliterpenone (
), and ingol 12-acetate (
). Their chemical structures were unambiguously determined by analysis of one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) and high resolution mass spectrometry, as well as by comparison with literature data. Among them,
is a new compound while
is an ethylated artifact of
-3,4-
-4,16
,17-trihydroxyatisane-3-carboxylic acid, a new compound. Isolates were evaluated for alpha-glucosidase inhibition. Compound
showed the most significant inhibitory activity against alpha-glucosidase with an IC
value of 69.62 µM. Further study on mechanism underlying yeast alpha-glucosidase inhibition indicated that
could retard the enzyme function by noncompetitive.
Abstract
Background
To investigate the knowledge, attitudes, and practices of the healthcare professionals (HCPs) including physicians and nurses regarding dengue transmission, diagnosis and clinical ...classification using the warning signs of World Health Organization (WHO) 2009 classification.
Results
Out of 471 respondents from three countries, 80.9% of physicians and 74% of nurses did not receive previous training regarding the dengue infection. The majority of respondents could identify the primary dengue vector (86%), while only a third of HCPs knew the biting time of dengue mosquitoes. Only half of our respondents knew about immunity induced by serotypes; Moreover, half of our participants could determine the diagnostic tests. On the other hand, about 90% of the respondents took responsibility for talking to the patients about preventive measures. Our respondents also showed wide variations in definition of warning signs listed in the WHO 2009 classification. Multivariate analysis linked the impact of different cofactors including prior training on dengue infection, type of profession, frequency of taking care of dengue patients and country on how HCPs defined these warning signs.
Conclusions
This study could declare the variation in employing the warning signs listed in the WHO 2009 classification. We have figured that most of the HCPs did not take prior training on the dengue viral infection; Also, we found gaps in the knowledge regarding various topics in dengue fever. This paper recommends the gathering of efforts to establish the proper knowledge of dengue infection and the warning signs listed by the WHO.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Here, new catalysts for application in the Direct Alcohol Fuel Cells (DMFC and DEFC), comprising of 1–8 wt% Pt dispersed on few layer graphene (FLG), are successfully synthesized, by means of a ...rapid, simple, inexpensive and environmentally friendly one-pot method. The mass activity of the PFG3 catalyst for methanol, in acid and alkaline media, was 25,243 mA mgPt−1 and 112,882 mA mgPt−1, respectively; for ethanol, in acid and alkaline media, was 25,000 mA mgPt−1 and 65,272 mA mgPt−1, respectively. These values were from tens to hundreds of times higher than those recently published for graphene-support Pt electrocatalysts. Our results suggest that the one-pot synthesis method result in simultaneous exfoliation, reduction and deposition during microwave irradiation in a very short time for producing catalysts with extremely high electrochemical performance, which may be effective alternative method for synthesis of electrocatalysts for DMFC and DEFC.
In this study, sol–gel combining with hydrothermal methods were successfully used to synthesize N and S co-doped TiO
2
nanotubes (N@S-TiO
2
NTT) for efficient photocatalytic degradation of volatile ...organic compounds (VOCs). The obtained characterization results indicated that the synthesized N@S co-doped TiO
2
existed as nanotubes. Specific surface areas of these synthesized nanotubes was greatly that of these nanoparticles. The largest surface area recorded at N@S-TiO
2
nanotubes was 105.3 m
3
/g. FTIR spectrum results showed that the presence of N–H and S–O bond, which confirmed that nitrogen and sulfur were successfully doped into TiO
2
lattice. We also investigated that N@S dopants significantly improved the photocatalytic activity of TiO
2
nanotubes for efficient degradation of gaseous VOCs. Therefore, photocatalytic activity for VOCs degradation by the N@S-TiO
2
nanotubes was greater than that by the undoped TiO
2
nanotube. Optimized humidity for degradation of VOCs was medium condition (55–70%). Under dry conditions, lack of water for hydroxyl radical production led to decrease in photocatalytic activity. Under humidity conditions, the excess water molecules competed with VOCs for adsorbing on material surface leading to decrease in photocatalytic degradation efficiency. Under the optimized humidity, the highest photocatalytic efficiency of the synthesized N@S-TiO
2
nanotubes for degradation of gaseous VOCs for 3 h was approximately 94%. The VOCs degradation capacity by the synthesized N@S-TiO
2
nanotubes was approximately 90 (ppm/g h).
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