•Fe-doped nanostructured WO3 films were synthesized using DC sputtering at RT.•The number of film defects was found to increase with increasing Fe concentrations.•The optical bandgap of the film ...(3.30eV) decreases to 3.15eV after doped with 2.6at% Fe.•The gas sensing of the 2.6at% Fe film to 3–12ppm NO2 at 150°C was significant.•The decrease in the material's band gap and an increase in defects enhanced sensing at lower temperature.
Fe-doped tungsten oxide thin films with different concentrations (0–2.6at%) were synthesized on glass and alumina substrates at room temperature using DC reactive sputtering and subsequently annealed at 300°C for 1h in air. The alumina substrate has pre-printed interdigitated Pt-electrodes for gas sensing measurements. The effects of Fe-doping on the film structure and morphology, electronic and optical properties for gas sensing were investigated. The grain size of the different films on the alumina and Pt regions of the substrate vary only slightly between 43 and 57nm with median size of about 50nm. Raman spectra showed that the integrated intensity of WO to OWO bands increases with increasing Fe concentrations and this indicated an increase in the number of defects. From XPS the different concentrations of the Fe-doped films were 0.03at%, 1.33at% and 2.6at%. All the films deposited on glass substrate have shown similar visible transmittance (about 70%) but the optical band gap of the pure film decreased form 3.30eV to 3.15eV after doping with 2.6at% Fe. The Fe-doped WO3 film with the highest Fe concentration (2.6at% Fe) has shown an enhanced gas sensing properties to NO2 at relatively lower operating temperature (150°C) and this can be attributed to the decrease in the optical band gap and an increase in the number of defects compared to the pure WO3 film.
•Pure and W-doped ZnO films were synthesized using sputtering at 0.4Pa and 1.33Pa.•The doped film deposited at 1.33Pa has shown spiky morphology with much lower grain density and porosity than the ...film deposited at 0.4Pa.•This film deposited at 1.33Pa favoured the formation of active site for OH adsorption and found not suitable for gas sensing.•A higher oxidation state of W (35.9eV) was found in the W-doped ZnO film deposited at 0.4Pa.•This film deposited at 0.4Pa has shown greater gas sensing to NO2 at lower operating temperature most likely due to enhanced free-carrier defects.
Pure and W-doped ZnO thin films were obtained using magnetron sputtering at working pressures of 0.4Pa and 1.33Pa. The films were deposited on glass and alumina substrates at room temperature and subsequently annealed at 400°C for 1h in air. The effects of pressure and W-doping on the structure, chemical, optical and electronic properties of the ZnO films for gas sensing were examined. From AFM, the doped film deposited at higher pressure (1.33Pa) has spiky morphology with much lower grain density and porosity compared to the doped film deposited at 0.4Pa. The average gain size and roughness of the annealed films were estimated to be 65nm and 2.2nm, respectively with slightly larger grain size and roughness appeared in the doped films. From XPS the films deposited at 1.33Pa favoured the formation of adsorbed oxygen on the film surface and this has been more pronounced in the doped film which created active sites for OH adsorption. As a consequence the W-doped film deposited at 1.33Pa was found to have lower oxidation state of W (35.1eV) than the doped film deposited at 0.4Pa (35.9eV). Raman spectra indicated that doping modified the properties of the ZnO film and induced free-carrier defects. The transmittance of the samples also reveals an enhanced free-carrier density in the W-doped films. The refractive index of the pure film was also found to increase from 1.7 to 2.2 after W-doping whereas the optical band gap only slightly increased. The W-doped ZnO film deposited at 0.4Pa appeared to have favourable properties for enhanced gas sensing. This film showed significantly higher sensing performance towards 5–10ppm NO2 at lower operating temperature of 150°C most dominantly due to increased free-carrier defects achieved by W-doping.
The stems of Khaya anthotheca yielded two new limonoids, which were identified on the basis of spectroscopic analysis as ...1α,8α-oxido-3β-acetoxy-2α-acylperoxy-1α,14α-dihydroxy-3.3.110,2-bicyclomeliac-7,19-olide (3) and 3-acetoxy-8,14-dien-8,30-seco-khayalactone (4). Methyl 1α,2β,3α,6,8α,14β-hexahydroxy-4.2.110,30.1 , -tricyclomeliac-7-oate, scopoletin, and 3-O-β-d-glucopyranosylsitosterol were also isolated. The limonoids were of little value to clarify the basis of the nonresistance against Hypsipyla grandella.
Phytochemical investigation from roots of Spathelia excelsa yielded the chromones 10(2,3-epoxy-3-methylbutanyl) spatheliachromen and 10(2,3-dihydroxy-3-methylbutanyl) methoxyspatheliacromen ...(5-methoxyspatheliabischromen); limonoid deacetylspathelin and protolimonoid C-21-epimers 3β-angeloyloxy-7α,24,25-trihydroxy-21,23-oxide-14,18-cycloapotirucall-21-hemiacetal; the alkaloids 7,8-dimethoxyflindersin, casimiroin and N-methyl-4,7,8-trimethoxyquinolin-2(1H)-one, besides a mixture of β-sitosterol and stigmasterol. Assays on promastigote forms of Leishmania braziliensis, deacetylspathelin showed moderate activity; and on epimastigote forms of Trypanossoma cruzi, 10(2,3-epoxy-3-methylbutanyl)spatheliachromen exhibited strong activity (IC50 = 11 µg mL-1).
Valorization of industrial low-value side-streams are of great interest, contributing to boosts in the circular economy. In this context, lignin side-streams of the pulp and paper industry were ...oxypropylated to produce biobased polyols and tested in the synthesis of rigid polyurethane (RPU) foams. E. globulus lignins, namely a lignin isolated from an industrial Kraft black liquor and depolymerized lignins obtained as by-products of an oxidation process, were used. RPU foams, synthesized with 100% lignin-based polyols and using a 1.1 NCO/OH ratio, were characterized concerning apparent density, morphology, thermal conductivity, thermal stability, and heat release rate (HRR). Foams containing the lignin-based polyols presented densities varying from 44.7 to 112.2 kg/m3 and thermal conductivity in the range of 37.2–49.0 mW/mK. For the reference foam (sample produced with 100% wt. Daltofoam TP 32015 polyol), values of 70.9 kg/m3 and 41.1 mW/mK were obtained, respectively. The achieved results point out the viability of using the generated lignin-based polyols at 100% content in RPU foams, mainly when depolymerized lignins are used. Moreover, fire retardancy was favored when the lignin-based polyols were introduced. The proposed strategies can contribute to establishing the integrated pulp and paper biorefinery concept where material synthesis (polyols and RPU foams) can be combined with chemical production (vanillin and syringaldehyde).
The fire resistance of composite slabs with steel decking, in Europe, is usually defined using simple calculation models provided by the Eurocode EN 1994-1-2. For assessing the methodology of these ...simple calculation methods, a new advanced calculation method is presented, using the software ANSYS. The numerical model is first validated with experimental data reported on bibliography and then a parametric analysis is conducted to better understand the effect of the load level on the composite structure under fire. The validation of the simulations consisted of three different models: the first model considers perfect contact between the steel deck and the concrete topping, and the two following models consider the existence of an air gap between these materials, acting as a thermal resistance on the temperature field through the thickness of the slab. The numerical results show good approximation to the experimental results, mainly when using the non-perfect contact model, reaching 3.88% and 16.91% of difference with respect to the insulation and load-bearing criteria, respectively. Based on the validation models, a parametric study is presented, modifying the load level from 10% up to 75%. New simple calculation models are presented to define the fire resistance of composite slabs, considering the load level, and the debonding effect between the concrete and the steel deck.
The human Respiratory Syncytial Virus (hRSV) is one of the most common causes of acute respiratory diseases such as bronchiolitis and pneumonia in children worldwide. Among the viral proteins, the ...nucleoprotein (N) stands out for forming the nucleocapsid (NC) that functions as a template for replication and transcription by the viral polymerase complex. The NC/polymerase recognition is mediated by the phosphoprotein (P), which establishes an interaction of its C-terminal residues with a hydrophobic pocket in the N-terminal domain of N (N-NTD). The present study consists of biophysical characterization of N-NTD and investigation of flavonoids binding to this domain using experimental and computational approaches. Saturation transfer difference (STD)-NMR measurements showed that among the investigated flavonoids, only hesperetin (Hst) bound to N-NTD. The binding epitope mapping of Hst suggested that its fused aromatic ring is buried in the protein binding site. STD-NMR and fluorescence anisotropy experiments showed that Hst competes with P protein C-terminal dipeptides for the hRSV nucleoprotein/phosphoprotein (N/P) interaction site in N-NTD, indicating that Hst binds to the hydrophobic pocket in this domain. Computational simulations of molecular docking and dynamics corroborated with experimental results, presenting that Hst established a stable interaction with the N/P binding site. The outcomes presented herein shed light on literature reports that described a significant antireplicative activity of Hst against hRSV, revealing molecular details that can provide the development of a new strategy against this virus.
Communicated by Ramaswamy H. Sarma
Metal machining is one of the most important manufacturing processes in today’s production sector. The tools used in machining have been developed over the years to improve their performance, by ...reducing the cutting forces, the friction coefficient, and the heat generated during the cutting process. Several cooling systems have emerged as an effective way to remove the excessive heat generated from the chip-tool contact region. In recent years, the introduction of nano and micro-textures on the surface of tools has allowed to further improve their overall performance. However, there is not sufficient scientific data to clearly show how surface texturing can contribute to the reduction of tool temperature and identify its mechanisms. Therefore, this work proposes an experimental setup to study the tool surface characteristics’ impact on the heat transfer rate from the tools’ surface to the cooling fluid. Firstly, a numerical model is developed to mimic the heat energy flow from the tool. Next, the design variables were adjusted to get a linear system response and to achieve a fast steady-state thermal condition. Finally, the experimental device was implemented based on the optimized numerical model. A good agreement was obtained between the experimental tests and numerical simulations, validating the concept and the implementation of the experimental setup. A square grid pattern of 100 μm × 100 μm with grooves depths of 50, 100, and 150 μm was introduced on cutting insert surfaces by laser ablation. The experimental results show that there is a linear increase in heat transfer rate with the depth of the grooves relatively to a standard surface, with an increase of 3.77% for the depth of 150 μm. This is associated with the increase of the contact area with the coolant, the generation of greater fluid turbulence near the surface, and the enhancement of the surface wettability.
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