A new approach for the synthesis of podophyllotoxin-naphthoquinone compounds using microwave-assisted three-component reactions is reported in this study. Novel podophyllotoxin-naphthoquinone ...derivatives with modification on ring E were synthesized. All the synthetic compounds were assessed in terms of their cytotoxicity profile against four cancer cell lines (KB, HepG2, A549, and MCF7), and noncancerous Hek-293 cell lines. Notably, treatment of SK-LU-1 cells with compounds
5a
and
5b
resulted in G2/M phase arrest of the cell cycle, caspase-3/7 activation, and apoptosis. Additionally, molecular docking studies were performed and showed important interaction of two compounds against residues in the colchicine-binding-site of tubulin as well. Taken together, compounds
5a
and
5b
were identified as potent anticancer agents.
A new approach for the synthesis of podophyllotoxin-naphthoquinone compounds using microwave-assisted three-component reactions is reported in this study.
Health personnel and community workers are at the front line of the COVID-19 emergency response and need to be equipped with adequate knowledge related to epidemics for an effective response. This ...study aimed to identify the coverage of COVID-19 health information via different sources accessed by health workers and community workers in Vietnam. A cross-sectional study using a web-based survey was carried out from January to February 2020 in Vietnam. Respondent-driven sampling (RDS) was used for recruiting participants. We utilized the exploratory factor analysis (EFA) to examine the construct validity of the questionnaire. A higher percentage of participants knew about "Clinical and pathogen characteristics of COVID-19", compared to "Regulations and policies related to COVID-19". The percentage of participants accessing the information on "Guidelines and policies on prevention and control of COVID-19" was the lowest, especially among medical students. "Mass media and peer-educators" channels had a higher score of accessing COVID-19 information, compared to "Organizations/ agencies/ associations" sources. Participants consumed most of their COVID-19 information via "Internet, online newspapers, social networks". Our findings indicate an urgency to re-design training programs and communication activities for a more effective dissemination of information related to the COVID-19 epidemic or epidemics in general.
BACKGROUND: Achieving access to clean water and basic sanitation remains as major challenges in Vietnam, especially for vulnerable groups such as minority people, despite all the progress made by the ...Millennium Development Goal number 7.C. OBJECTIVES: The study aimed to describe the access to improved water sources and sanitation of the ethnic minority people in Vietnam based on a national survey and to identify associated factors. METHODS: A cross-sectional study was conducted in 2019 with a sample size of 1385 ethnic minority households in 12 provinces in Vietnam. Multivariate logistic regression modeling was performed to examine the probability of having access to improved water sources and sanitation and sociodemographic status at a significance level of P < .05. RESULTS: The access to improved water sources and sanitation was unequal among the ethnic minority people in Vietnam, with the lowest access rate in the northern midland and mountainous and Central Highland areas and the highest access rate in the Mekong Delta region. Some sociodemographic variables that were likely to increase the ethnic minority people’s access to improved water sources and/or sanitation included older age, female household heads, household heads with high educational levels, religious households, and households in not poor status. CONCLUSION AND RECOMMENDATIONS: The study suggested more emphasis on religion for improving the ethnic minority’s access to improved water sources and sanitation. Besides, persons of poor and near-poor status and with low educational levels should be of focus in future water and sanitation intervention programs.
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•Pt/rGO catalysts were successfully synthesized using either NaBH4 or ethylene glycol.•Synthesis using NaBH4 could improve electrocatalytic towards methanol oxidation of Pt/rGO ...catalyst.•40%Pt/rGO synthesized using NaBH4 showed the best electrocatalytic performance.
The synthesis processes of Platinum (Pt) on reduced graphene oxide (rGO) catalysts from graphene oxide (GO) using two reducing agents including sodium borohydride and ethylene glycol is reported. Structure and morphology of Pt/rGO catalysts are characterized by X-ray powder diffraction, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Electrocatalytic methanol oxidation properties of these catalysts are evaluated by cyclic voltammetry and chronoamperometry. The results show that catalyst synthesized using sodium borohydride has a higher metallic Pt content and an improved catalytic performance in comparison to catalyst synthesized using ethylene glycol. Moreover, effect of Pt loading amount on electrocatalytic methanol oxidation performance of catalysts synthesized using sodium borohydride is systematically investigated. The optimal Pt loading amount on graphene is determined to be 40%.
In this study, rice husk ask (RHA)-SiO2 nanoparticles were successfully synthesized from rice husk ash by precipitation method. TEM images indicate that as-synthesized nanoparticles had amorphous ...structure with a relatively homogeneous size of about 20 nm. Crosslinking process, mechanical properties and weathering degradation of the nanocomposite coating based on acrylic polyols and polyisocyanate in the presence of nano RHA-SiO2 were investigated. The mechanical properties of the coating show the highest values with 2.5 wt%. of nano RHA-SiO2 as filler. FE-SEM analysis demonstrates that nano RHA-SiO2 nanoparticles were well dispersed in the coating. IR analysis, relative hardness, gel fraction and swelling degree measurements show that the nanoparticles improved conversion performance of isocyanate groups, gel fraction, swelling degree and relative hardness of the coating. Accelerated weathering test indicates that, after 36 cycles of test, the nanocomposite coating was degraded with the formation of several holes on the coating surface and the recorded weight loss was 9.1%. For the neat coating, the formation of various large holes of dimension ranging from 20 nm to several μm on the surface was observed and the weight loss is measured to be higher (12.7%) in the same conditions. Nano RHA-SiO2 possibly play a dual role: i) UV protector and ii) nanofiller helping to prevent the invasion of aging agents.
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•Nano SiO2 with size of ~20 nm have been successfully synthesized from rice husk ash.•The presence of nanoparticles enhanced the conversion performance of isocyanate groups.•The addition of nanoparticles improved the gel fraction, swelling degree of coating.•The nanoparticles enhanced mechanical properties and weathering resistance of coating.
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•Highly efficient visible light driven photocatalyst S doped g-C3N4 was synthesized.•S doped g-C3N4 can reduce the recombination rate of electron-hole and narrowed band gap ...energy.•The S doped g-C3N4 had high recyclability and can reuse for 5 cycles.•TC was effectively removed from different wastewater by S doped g-C3N4.
Due to the coronavirus problem in 2020, lot of antibiotic compounds such as tetracycline (TC) have been used and discharge into water, leading to environment and human heal problem. Thus, preparing new catalysts for tetracycline removal have become a significant challenge in the areas of environmental engineering. Here we provide advanced photocatalyst based on sulfur (S) doped carbon nitride (CN) for treatment of TC. The characterization results confirmed that S doping reduced the recombination rates of electrons and holes, improved light absorption behavior. Under solar light the removal of TC just required only 30 mins and the degradation efficiency was 98.7%. S doped CN was able to degrade TC from different wastewaters with a maximum degradation efficiency of 93.8%. Furthermore, S-CN can be recycled multiple times, indicating it is suitable photocatalyst to solve the problem of antibiotic contamination in wastewaters.
Combining semiconductor and noble metal nanostructures into a hybrid system has shown many complementary advantages in the optical properties, making them more attractive in practical applications. ...Herein, we prepared a semiconductor/noble metal hybrid system composed of Ag nanoparticles decorated on ZnO nanoplates acting as a surface-enhanced Raman scattering (SERS) substrate for probing methyl red. The tuning of the optical characteristics of the hybrid system was demonstrated through the changes in the absorption, fluorescence, and Raman spectra. The formation of the local electromagnetic field at the heterostructure interface plays a pivotal role in its SERS activity. Thanks to density functional theory calculations, methyl red's vibrational modes and symmetry properties were assigned to be consistent with the contribution of the neutral
trans
conformer and protonated state. Then, using Herzberg-Teller-surface selection rules, these assignments strongly support the realization that the SERS mechanism based on the ZnO/Ag substrate has a significant electromagnetic contribution
versus
the Ag substrate in which charge transfer plays a pivotal role. To the best of our knowledge, this is the first investigation that has clarified the mechanism and advantage of semiconductor/metal (ZnO/Ag nanostructures) even over noble metals (Ag nanoparticles) in SERS applications. Moreover, the SERS behavior based on the ZnO/Ag substrate was also examined and the results indicated high sensitivity and good repeatability.
Using Herzberg-Teller-surface selection rules in combination with the results of DFT calculations, the SERS mechanism based on the ZnO/Ag substrate has indicated a significant electromagnetic contribution
versus
the Ag substrate, in which charge transfer plays a pivotal role.
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.
Abstract
Current WHO-recommended diagnostic tools for tuberculosis infection (TBI) have well-known limitations and viable alternatives are urgently needed. We compared the diagnostic performance and ...accuracy of the novel QIAreach QuantiFERON-TB assay (QIAreach; index) to the QuantiFERON-TB Gold Plus assay (QFT-Plus; reference). The sample included 261 adults (≥ 18 years) recruited at community-based TB case finding events. Of these, 226 underwent Tuberculin Skin Tests and 200 returned for interpretation (TST; comparator). QIAreach processing and TST reading were completed at lower-level healthcare facilities. We conducted matched-pair comparisons for QIAreach and TST with QFT-Plus, calculated sensitivity, specificity and area under a receiver-operating characteristic curve (AUC), and analyzed concordant-/discordant-pair interferon-gamma (IFN-γ) levels. QIAreach sensitivity and specificity were 98.5% and 72.3%, respectively, for an AUC of 0.85. TST sensitivity (53.2%) at a 5 mm induration threshold was significantly below QIAreach, while specificity (82.4%) was statistically equivalent. The corrected mean IFN-γ level of 0.08 IU/ml and corresponding empirical threshold (0.05) of false-positive QIAreach results were significantly lower than the manufacturer-recommended QFT-Plus threshold (≥ 0.35 IU/ml). Despite QIAreach’s higher sensitivity at equivalent specificity to TST, the high number of false positive results and low specificity limit its utility and highlight the continued need to expand the diagnostic toolkit for TBI.
A series of substituted 4
H
-pyrano2,3-
d
pyrimidines were synthesized from corresponding substituted 4
H
-pyrans by ring-closing reaction with acetic anhydride or acetic acid in the presence of ...trifluoroacetic acid as catalyst. The successive alkylation reaction of lactam N–H bond on pyrimidine-4-one ring was carried out using propargylic bromide in dry acetonitrile in the presence of anhydrous potassium carbonate. Three procedures applied for this purpose, including MW-assisted heating conditions at power of 100 W, under conventional heating conditions in water bath at 50 °C, and under ultrasound-assisted heating conditions at 50 °C. Dry acetonitrile was used as reaction solvent. Excellent yields of
N
-propargyl-4
H
-pyrano2,3-
d
pyrimidine derivatives were obtained. The single-crystal X-ray structure of compound
6a
has been recorded, and the study helps to confirm the structure of synthesized
N
-propargyl derivative of 4
H
-pyrano2,3-
d
pyrimidines
6a
–
6p
.
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