Titanium oxide hydrates: optical properties and applications

PhDTiO2 has been extensively studied in the last decades due to its interesting optical and electronic properties, which, combined with low fabrication costs, renders this material very attractive for applications in photovoltaic and photocatalysis. However, the performances of titania in specific device applications were found to be strongly dependent on the synthetic methods selected for its production. The majority of such synthetic procedures rely on the hydrolysis of suitable precursors and often produce an amorphous solid, generally referred as the “amorphous” titanium oxide beside the crystalline titania. In this thesis, we thus set out to investigate amorphous materials produced by the hydrolysis of titanium tetrachlorides and tetraisopropoxide. We show that these amorphous products consists of titanium oxide hydrates, which are relatively stable at room temperature and fully convert into crystalline titania only after extended temperature treatments. We also find that titanium oxide hydrates may display highly desirable characteristic such as a strong photochromic response – especially when placed in a suitable chemical environment. In the following chapter, we then show 3 that hybrid systems can be readily prepared of titanium oxide hydrates with, for instance, macromolecular materials such as poly(vinylalcohol). The amorphous nature of the titanium oxide hydrates allows to introduce more than 90 vol.% of the inorganic species into such systems – compared to 15 vol.% or less when producing hybrids comprising, e.g., crystalline nanoparticles of TiO2. Therefore, materials can be realized that display a refractive index n of at least 2.1, without compromising transparency of the resulting structures. Remarkably, n can not only be adjusted by varying the content of the inorganic species, but also through suitable heat treatments and/or irradiation with UV-light. Potential applications for such new, versatile and tunable optical systems are also discussed in this thesis

Plastic flow behavior of twinning induced plasticity steel from low to warm temperatures

This work investigates the tensile behavior of twinning induced plasticity (TWIP) steel under room to warm temperatures. Stress-strain flow curves have been obtained from steady-state uniaxial tensile tests performed at different temperatures, that is, from 20 to 800 °C, and different engineering strain rates, 0.003 and 0.5 s−1. The yield and ultimate tensile strength, elongation at fracture, reduction of area, strain hardening exponent and strain hardening rate have been defined to describe the plastic behavior of TWIP steel. It has been found that the plastic flow behavior of TWIP steel is characterized by negative strain rate sensitivity and strain hardening, at temperatures from 20 to 300 °C, until the twinning mechanism occurs. At these temperatures, dynamic strain aging starts at the beginning of plastic deformation, with the appearance of fluctuations in the work hardening rate and local strain rate. Pronounced local serrations also appear at 300 °C and 0.003 s−1. Plastic deformation is mainly driven by dislocation gliding at 550 and 800 °C, and mechanical twins are absent. As a result, negative strain rate sensitivity and local serrations disappear in the stress-strain curves. Creep also contributes notably to plastic deformation at 800 °C, as was also observed on the fracture surfaces of tensile samples. Mechanical twins were only visible for the lower temperatures. The grains in the sample tested at 800 °C and 0.003 s-1 were fully recrystallized. Keywords: Twinning induced plasticity steel, Plastic flow behavior, Warm temperature, Mechanical strength, Strain hardening, Dynamic strain agin

Reply to: "The Possible Role of Anti-methicillin-resistant Staphylococus Aureus Antimicrobial Agents in Spontaneous Bacterial Peritonitis"

Letter answering to a comment about an articl

Use of electrode displacement signals for electrode degradation assessment in resistance spot welding

In resistance spot welding, the quality of welds is not only affected by the correct design of the welding cycle, but also by the electrode degradation that occurs over time. This work proposes a novel approach to indirectly monitor the electrode degradation during welding by analyzing the electrode displacement signal from a non-contact sensor embedded in the welding machine and the electrode tip shape obtained from carbon imprint tests. As a result of an experimental campaign involving more than 1200 weld spots, the electrode speed during the final hold stage has been determined as the most explanatory feature describing the electrode displacement. Based on the mechanical strength of spot welds, the electrode contact face area has been defined as the most representative feature characterizing electrode degradation. A regression analysis has been carried out to infer a relationship between the electrode speed and the contact area representative of tool wear. A Neural Network has been built to use some features extracted from the electrode displacement signals to predict the contact area and thus indirectly the electrode degradation. The model has shown a good accuracy, with a mean error of the contact area about 1.61 mm2, and with a standard deviation of about 3.73 mm2. The data-driven approach proposed allows through the evaluation of the electrode contact area to have better real-time knowledge and control of the welding process

A COMPARISON OF META-ANALYSIS METHODS FOR DETECTING DIFFERENTIALLY EXPRESSED GENES IN MICROARRAY EXPERIMENTS: AN APPLICATION TO MALIGNANT PLEURAL MESOTHELIOMA DATA

The proliferation of microarray experiments and the increasing availability of relevant amount of data in public repositories have created a need for meta-analysis methods to efficiently integrate and validate microarray results from independent but related studies. Despite its increasing popularity, meta-analysis of microarray data is not without problems. In fact, although it shares many features with traditional meta-analysis, most classical meta-analysis methods cannot be directly applied to microarray experiments because of their unique issues. Several meta-analysis techniques have been proposed in the context of microarrays. However, only recently a comprehensive framework to carry out microarray data meta-analysis has been proposed. Moreover very few software packages for microarray meta-analysis implementation exist and most of them either have unclear manuals or are not easy to apply. We applied four meta-analysis methods, the Stouffer’s method, the moderated effect size combination approach, the t-based hierarchical modeling and the rank product method, to a set of three microarray studies on malignant pleural mesothelioma. We focused on differential expression analysis between normal and malignant mesothelioma pleural tissues. Both unfiltered and filtered data were analyzed. The lists of differentially expressed genes provided by each method for either kind of data were compared, also by pathway analysis. These comparisons highlighted a poor overlap between the lists of differentially expressed genes and the related pathways obtained using the unfiltered data. Conversely, a higher concordance of the results, both at the gene and the pathway level, was observed when filtered data were considered. The fact that a significant number of genes were identified by only one of the tested methods shows that the gene ranking is based on different perspectives. In fact, the analyzed methods are based on different assumptions and focus on diverse aspects in selecting significant genes. Since so far there is no consensus on what is (are) the ‘best’ meta-analysis method(s), it may be useful to select candidate genes for further analysis using a combination of different meta-analysis methods. In particular, differentially expressed genes detected by more than one method may be considered as the most reliable ones while genes identified by only a single method may be further explored to expand the knowledge of the biological phenomenon of interest

Stroke Blues : Erkennen und Handeln! Eine Literaturarbeit über die Post-Stroke-Depression im Akutspital

Hintergrund: Die Post-Stroke-Depression (PSD) ist eine häufige und schwerwiegende Komplikation. Sie hat einen signifikanten Einfluss auf die Lebensqualität und den Rehabilitationsverlauf der Betroffenen. Trotz hoher Prävalenz wird sie selten erkannt, bleibt unbehandelt und verursacht Folgekosten. Pflegefachpersonen nehmen aufgrund des intensiven Kontaktes zu den Betroffenen eine wichtige Rolle bei der Identifizierung einer PSD ein. Fragestellungen: Was sagt die Literatur zur Erfassung einer PSD durch Pflegefachpersonen im Akutspital und welche pflegerischen Interventionen können aus den gefundenen Ergebnissen abgleitet werden? Methode: Eine systematisierte Literaturrecherche erfolgte im Zeitraum vom 20. September bis 15. Oktober 2019 in den Datenbanken CINAHL, PubMed und PsychInfo. Ergebnisse: Gefunden wurden acht Studien zur Erfassung, zwei Studien und ein Fachartikel zu Interventionen. Besonders das Screeninginstrument, der PHQ-2 in Kombination mit PHQ-9 haben eine hohe Sensitivität, Spezifität und klinische Nützlichkeit gezeigt. Darüber hinaus benötigt es einen multiprofessionellen Ansatz mit einem strukturierenden Plan, Interventionen, Folllow-ups und einer guten interprofessionellen Zusammenarbeit. Schlussfolgerung: Eine PSD verstärkt das ohnehin einschneidende Stroke-Ereignis für einen betroffenen Menschen. Mit dieser Arbeit werden effektive Verfahren zur Einschätzung und Behandlung vorgestellt. Pflegefachpersonen können damit einen wichtigen Beitrag bei der Erkennung und Pflege von PSD leisten

Weldability and monitoring of resistance spot welding of Q&P and TRIP steels

This work aims at investigating the spot weldability of a new advanced Quenching and Partitioning (Q&P) steel and a Transformation Induced Plasticity (TRIP) steel for automotive applications by evaluating the effects of the main welding parameters on the mechanical performance of their dissimilar spot welds. The welding current, the electrode tip voltage and the electrical resistance of sheet stack were monitored in order to detect any metal expulsion and to evaluate its severity, as well as to clarify its effect on spot strength. The joint strength was assessed by means of shear and cross tension tests. The corresponding fracture modes were determined through optical microscopy. The welding current is the main process parameter that affects the weld strength, followed by the clamping force and welding time. Metal expulsion can occur through a single large expulsion or multiple expulsions, whose effects on the shear and cross tension strength have been assessed. Longer welding times can limit the negative effect of an expulsion if it occurs in the first part of the joining process. The spot welds exhibit different fracture modes according to their strengths. Overall, a proper weldability window for the selected process parameters has been determined to obtain sound joints

Heat-shock pretreatment inhibits sorbitol-induced apoptosis in K562, U937 and HeLa cells.

The aim of this study was to determine whether heat-shock pretreatment exerted a protective effect against sorbitol-induced apoptotic cell death in K562, U937 and HeLa cell lines and whether such protection was associated with a decreased cytochrome c release from mithocondria and a decreased activation of caspase-9 and -3. Following heat-shock pretreatment (42 6 0.3C for 1 hr), these cell lines were exposed to sorbitol for 1 hr. Apoptosis was evaluated by DNA fragmentation, whereas caspase-9,-3 activation, cytochrome c release and heat-shock protein70 (HSP70) were assayed by Western Blot. Sorbitol exposure-induced apoptosis in these different cell lines with a marked activation of caspase-9 and caspase- 3, whereas heat-shock pretreatment before sorbitol exposure, induced expression of HSP70 and inhibited sorbitol-mediated cytochrome c release and subsequent activation of caspase-9 and caspase- 3. Similarly, overexpression of HSP70 in the three cell lines studied prevented caspase-9 cleavage and activation as well as cell death. Furthermore, we showed that the mRNA expression of iNOS decreased during both the heat-shock treatment and heat-shock pretreatment before sorbitol exposure. By contrast, the expression of Cu-Zn superoxide dismutase (SOD) and Mn-SOD proteins increased during heat-shock pretreatment before sorbitol exposure. We conclude that, heat-shock pretreatment protects different cell lines against sorbitol-induced apoptosis through a mechanism that is likely to involve SOD family members

ADSORÇÃO DE NAPROXENO, NORFLOXACINA E RODAMINAS EM MATERIAIS MESOPOROSOS ORDENADOS

O presente trabalho foca o estudo da influência das propriedades texturais e químicas de materiais mesoporosos, assim como, das condições operacionais do meio, nomeadamente, temperatura e pH, no processo de adsorção / imobilização de alguns compostos das classes referidas. O trabalho envolve a preparação, funcionalização e caracterização de materiais mesoporosos ordenados (incluindo do tipo MCM-41 e SBA-15) e estudos cinéticos e de equilíbrio de adsorção / imobilização de fármacos e de compostos luminescentes com dimensão molecular considerável, como por exemplo, o naproxeno (anti-inflamatório não esteroíde), a norfloxacina (antibiótico) e as rodaminas B e 6G (corantes orgânicos da família das fluoronas)

ERK-1 MAP kinase prevents TNF-induced apoptosis through bad phosphorylation and inhibition of bax translocation in HeLa cells

Extracellular signal-regulated kinase (ERK) 1/2 signaling is involved in tumor cell survival through the regulation of Bcl-2 family members. To explore this further and to demonstrate the central role of the mitochondria in the ERK1/2 pathway we used the HeLa cellular model where apoptosis was induced by tumor necrosis factor (TNF) and cycloheximide (CHX). We show that HeLa cells overexpressing ERK-1 displayed resistance to TNF and CHX. HeLa cells overexpressing a kinase-deficient form of ERK-1 (K71R) were more sensitive to TNF and CHX. In the ERK-1 cells, Bad was phosphorylated during TNF + CHX treatment. In the HeLa wt cells and in the K71R clones TNF and CHX decreased Bad phosphorylation. ERK-1 cells treated with TNF and CHX did not release cytochrome c from the mitochondria. By contrast, HeLa wt and K71R clones released cytochrome c. Bax did not translocate to the mitochondria in ERK-1 cells treated with TNF + CHX. Conversely, HeLa wt and K71R clones accumulated Bax in the mitochondria. In the HeLa wt cells and in both ERK-1 transfectants Bid was cleaved and accumulated in the mitochondria. The caspase-8 inhibitor IETD-FMK and the mitochondrial membrane permeabilization inhibitor bongkrekic acid (BK), partially prevented cell death by TNF + CHX. Anisomycin, a c-Jun N-terminal kinases activator, increased TNF-killing. The ERK-1 cells were resistant to TNF and anisomycin, whereas K71R clones resulted more sensitive. Our study demonstrates that in HeLa cells the ERK-1 kinase prevents TNF + CHX apoptosis by regulating the intrinsic mitochondrial pathway through different mechanisms. Inhibition of the intrinsic pathway is sufficient to almost completely prevent cell death. © 2009 Wiley-Liss, Inc