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TiO2 thin films were used as photocatalysts in CO2 photoconversion to solar fuels under UV irradiation. The films were deposited via sputtering while varying the working pressure for each deposition and could produce CH2O2 and CH3OH. According to Raman results, the films Ti-1 (3.87 Pa) and Ti-2 (3.73 Pa) deposited at high working pressure have a higher contribution of brookite phase compared with the films Ti-3 (3.47 Pa) and Ti-4 (3.33 Pa) obtained at low working pressure. Likewise, a higher presence of the brookite phase increases the atomic concentration of C–O bonds and −OH groups on the film surface, which reaches the CO2 photoconversion, as the TiO2 capacity to adsorb CO2 on the surface is determined by the O and C species present in the film. Therefore, the films Ti-1 and Ti-2, deposited at high working pressures and significantly contributing to the brookite phase, can produce 0.56 and 0.94 μmol of CH3OH, respectively. Meanwhile, according to the Raman and XPS results, the highest formic acid production was obtained from the Ti-3 and Ti-4 films, which show a less brookite phase presence and a higher contribution of O2− ions in TiO2. [ABSTRACT FROM AUTHOR]

Doping titanium dioxide has become a strategy for enhancing its properties and reducing its recombination issues, with the aim of increasing its efficiency in photocatalytic processes. In this context, this work studied its deposition over glass substrates using a sol–gel dip coating methodology. The effect of doping TiO2 with Zirconium cations in low molar concentrations (0.01, 0.05, 0.1%) in terms of its structural and optical properties was evaluated. The structural characterization confirmed the formation of amorphous thin films with Zr introduced into the TiO2 cell (confirmed by XPS characterization), in addition to increasing and defining the formed particles and their size slightly. These changes resulted in a decrease in the transmittance percentage and their energy band gap. Otherwise, their photocatalytic properties were evaluated in hydrogen production using ethanol as a sacrificial agent and UV irradiation. The hydrogen evolution increased as a function of the Zr doping, the sample with the largest Zr concentration (0.1% mol) being the most efficient, evolving 38.6 mmolcm−2 of this gas. Zr doping favored the formation of defects in TiO2, being responsible for this enhancement in photoactivity. [ABSTRACT FROM AUTHOR]

CO2 photoconversion to solar fuels requires materials with a high affinity to the acidic CO2, and MgO and Mg(OH)2 films represent good candidates due to their basic sites are highly active for CO2 capture in a wide interval of temperatures. However, the deposition of MgO and Mg(OH)2 as thin film is difficult to obtain by traditional methods. As an alternative, in this work, the successive ionic layer adsorption and reaction (SILAR) method is proposed to obtain MgO/Mg(OH)2 mixtures over glass substrates at significantly lower temperatures (200–400 °C). The films were tested as photocatalysts in the CO2 photoconversion to solar fuels (HCOOH and CH3OH) under UV–visible-NIR irradiation. The as-prepared films exhibited the hexagonal structure of the Mg(OH)2 phase. As the temperature increased, XRD and XPS analysis confirmed the presence of orthorhombic MgO, while the morphology remains with similar grains with an estimated size of 1 µm. The annealing temperatures change the chemical species (Mg–O, Mg–OH, and Mg–CO3) on the films affected their photocatalytic activity. The films exhibited high affinity for CO2 due to the presence of defects (F and F+ centers) in both phases. The photocatalytic behavior was directly related to OH− species present in each sample. According to the results, it seems that fewer hydroxides and defects on the films favored higher efficiencies for the CO2 photoconversion. In addition, the films were exposed to accelerated weathering tests to evaluate their efficiency for more extended periods. The results indicated that the aged films still have activity for CO2 photoconversion. [ABSTRACT FROM AUTHOR]

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Aim Delay in commencing adjuvant therapy for colorectal cancer seems to impair survival in some retrospective studies. This study was planned to evaluate its impact on survival. Methods This was a retrospective study enrolling patients registered from 2000 to 2012 in two large cancer-dedicated institutions in Brazil. The primary outcome was overall survival according to early vs late chemotherapy initiation. The interval between the primary surgery and the start of adjuvant chemotherapy was calculated. Survival was estimated using the Kaplan-Meier method and the impact of multiple prognostic factors on survival by Cox regression analysis. Results By the end of 2012, a total of 1963 Stage II and III colorectal patients were identified and 1318 patients received adjuvant chemotherapy, with 22% and 46% of those starting adjuvant chemotherapy within 6 weeks and 8 weeks of surgery. The median period of follow-up was 41 months. Patients starting chemotherapy within 6-8 weeks of surgery had longer overall survival compared with those who started after (6 weeks vs later, hazard ratio 0.76, 95% CI 0.57-0.99, P = 0.046; 8 weeks vs later, hazard ratio 0.74, 95% CI 0.59-0.93, P = 0.011). In the multivariate analysis, age, stage, histological grade, angiolymphatic invasion, emergency surgery and preoperative therapy were independent prognostic factors, but the interval between surgery and start of adjuvant therapy was not. Conclusion In this large retrospective study, the standard prognostic factors impacted on survival whereas the timing of adjuvant therapy did not. Patients with delayed adjuvant chemotherapy may have worse prognostic factors which could play a major role in their poor outcome. [ABSTRACT FROM AUTHOR]

In this work, a systematic variation of the processing parameters, such as gas mixture, time of nitriding and current density, has been carried out to determine how these will influence the sliding wear behaviour of plasma nitrided layers on AISI H13. Optical profilometry and scanning electron microscopy were used to characterise the worn sample and to determine the wear mechanism. The results revealed the strong influence of the current density on the formation of different diffusion and nitrided layers, which explained the wear behaviour of the studied samples, especially for those which were tested at room temperature. It was found that the wear volume of the nitrided samples without the existence of a compound layer was around 200 times smaller than that of the untreated samples and nearly 7 times smaller than that of nitrided samples when the compound layer was present. During the tests carried out at 300°C, the wear behaviour for the nitrided samples was worse than that for the untreated ones, due to the formation of higher amount of debris as a consequence of the breakdown of the compound layer and the subsequent removal of the enriched CrN from the ferritic matrix, generating a severe abrasion wear mechanism. All the samples tested at 600°C presented a similar tribological behaviour irrespective to the processing parameters values chosen for nitriding, as a consequence of the formation of a uniform and 'lubricious' iron oxide layer which, however, was insufficient to protect the steel against wear at this temperature to the levels which were obtained for the samples tested at room temperature. [ABSTRACT FROM AUTHOR]

In the present paper, five different operating conditions of a plasma nitriding process on annealed AISI H13 were investigated. A systematic variation of processing parameters such as gas mixture, time of processing and current density has been carried out in order to study their effect on microstructure. X-ray diffraction, microhardness testing and scanning electron microscopy techniques coupled with semiquantitative energy dispersive X-ray analysis were used to characterise the nitrided samples. The results revealed that the current density during plasma processing has a considerable influence on both the compound layer formation and depth of the diffusion zone. Also, it has been shown that the geometrical configuration of the workload may affect the uniformity of the diffusion zone, giving rise to the presence of heterogeneous nitrogen distribution zones along it. [ABSTRACT FROM AUTHOR]

In the present work, study on a systematic variation of the processing parameters such as gas mixture, time of nitriding and current density has been carried out in order to determine how these will influence the sliding wear behaviour of plasma nitrided layers on AISI H13. Optical profilometry and scanning electron microscopy were used to characterise the worn sample and to determine the wear mechanism. The results revealed a strong influence of the current density on the formation of different diffusion and nitrided layers, which explained the wear behaviour of the studied samples, especially for those tested at room temperature. It was found that the wear volume of the nitrided samples without the existence of a compound layer was ∼200 times smaller than the wear volume of the untreated samples and nearly seven times smaller than the wear volume of nitrided samples when the compound layer was present. When the tests were carried out at 300°C, the wear behaviour was worse for the nitrided samples than for the untreated ones, owing to the formation of higher amount of debris as a consequence of the breakdown of the compound layer and the subsequent removal of the enriched Cr–N from the ferritic matrix, generating a severe abrasion wear mechanism. All the samples tested at 600°C presented a similar tribological behaviour irrespective of the processing parameters values chosen for nitriding, as a consequence of the formation of a uniform and 'lubricious' iron oxide layer which, however, was insufficient to protect the steel against wear at this temperature to the levels which were obtained for the samples tested at room temperature. [ABSTRACT FROM AUTHOR]

ZnO thin films with grain morphology were obtained over glass substrates using the sol-gel method; these films were used as substrates to grow ZnO nanorods using chemical bath deposition (CBD) technique. The transmittance percentage of two films was over 85% and the electrical resistivity decreased when ZnO nanorods were grown over the ZnO thin film with grain morphology. A laser is incident at the thin film surface to measure the electrical response as a function of the wavelength change, it is found that electrical response is higher for the thin films with ZnO nanorods; these results shows that ZnO nanorods are a good choice for their use in photosensors. [ABSTRACT FROM AUTHOR]