87 research outputs found

    Degradation of LaMnO{3-y} surface layer in LaMnO{3-y}/ metal interface

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    We report electrical measurements showing the degradation processes of LaMnO3y_{3-y} (LaMnO) in LaMnO/normal metal interface in both point contact and planar-type junctions. Immediately after the preparation of the interface, the degradation process was followed by measuring the evolution of the junction resistance versus time. This process is characterized by the appearance of a second maximum in the resistance vs. temperature (R-T) dependence at temperatures lower than the Curie temperature Tc_c, at which the metal-insulator transition occurs in the bulk. These effects are explained in terms of the formation of a depleted interface layer in LaMnO caused by an out-diffusion of oxygen from the manganite surface to the normal metal. This assumption is confirmed by XPS measurement. Similar results on LaSrMnO3y_{3-y} interfaces are also obtained.Comment: 4 pages, 3 figures, accepted for publication in Appl. Phys. Lett.(2002

    Strain-driven elastic and orbital-ordering effects on thickness-dependent properties of manganite thin films

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    We report on the structural and magnetic characterization of (110) and (001) La2/3Ca1/3MnO3 (LCMO) epitaxial thin films simultaneously grown on (110) and (001)SrTiO3 substrates, with thicknesses t varying between 8 nm and 150 nm. It is found that while the in-plane interplanar distances of the (001) films are strongly clamped to those of the substrate and the films remain strained up to well above t=100 nm, the (110) films relax much earlier. Accurate determination of the in-plane and out-of-plane interplanar distances has allowed concluding that in all cases the unit cell volume of the manganite reduces gradually when increasing thickness, approaching the bulk value. It is observed that the magnetic properties (Curie temperature and saturation magnetization) of the (110) films are significantly improved compared to those of (001) films. These observations, combined with 55Mn-nuclear magnetic resonance data and X-ray photoemission spectroscopy, signal that the depression of the magnetic properties of the more strained (001)LCMO films is not caused by an elastic deformation of the perovskite lattice but rather due to the electronic and chemical phase separation caused by the substrate-induced strain. On the contrary, the thickness dependence of the magnetic properties of the less strained (110)LCMO films are simply described by the elastic deformation of the manganite lattice. We will argue that the different behavior of (001) and (110)LCMO films is a consequence of the dissimilar electronic structure of these interfaces.Comment: 16 pages, 15 figure

    Influence of thickness and coatings morphology in the antimicrobial performance of zinc oxide coatings

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    "Author's copy"In this research work, the production of undoped and silver (Ag) doped zinc oxide (ZnO) thin films for food-packaging applications were developed. The main goal was to determine the influence of coatings morphology and thickness on the antimicrobial performance of the produced samples. The ZnO based thin films were deposited on PET (Polyethylene terephthalate) substrates by means of DC reactive magnetron sputtering. The thin films were characterized by optical spectroscopy, X-Ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Scanning Electron Microscopy (SEM). The antimicrobial performance of the undoped and Ag-doped ZnO thin films was also evaluated. The results attained have shown that all the deposited zinc oxide and Ag-doped ZnO coatings present columnar morphology with V-shaped columns. The increase of ZnO coatings thickness until 200 nm increases the active surface area of the columns. The thinner samples (50 and 100 nm) present a less pronounced antibacterial activity than the thickest ones (200–600 nm). Regarding Ag-doped ZnO thin films, it was verified that increasing the silver content decreases the growth rate of Escherichia coli and decreases the amount of bacteria cells present at the end of the experiment.The work described in this paper was supported by project NANOPACKSAFER: NANO-engineered PACKaging systems for improving quality, SAFEty and health characteristics of foods, Portugal-Spain International Nanotechnology Laboratory Nanotechnology Projects Call; and also by the FEDER funding through the COMPETE program and FCT PEst-C/BIA/UI4050/2011 project

    Efficacy and safety of trabectedin in metastatic uterine leiomyosarcoma: A retrospective multicenter study of the Spanish ovarian cancer research group (GEICO)

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    Objective: We assessed trabectedin in patients with advanced uterine leiomyosarcoma (uLMS) in real-life clinical practice given according to the marketing authorization. Methods: Thirty-six women from 11 tertiary hospitals across Spain who received trabectedin after anthracycline-containing regimen/s were retrospectively analyzed. The primary endpoint was progression-free survival (PFS). Results: Median PFS and overall survival (OS) since starting trabectedin treatment were 5.4 (95%CI: 3.5–7.3) and 18.5 months (95%CI: 11.5–25.6), respectively. Median OS was significantly higher (P = 0.028) in patients receiving trabectedin in = 2nd line (25.3 months) than in = 3rd (15.1 months) and with ECOG performance status = 1 at trabectedin start (19.8 months) than ECOG 2–3 (6.0 months, P = 0.013). When calculating OS since diagnosis, patients had longer OS with localized disease at diagnosis (87.4 months) vs. locally advanced (30.0 months) or metastatic (44.0 months, P = 0.041); and patients who received adjuvant therapy (87.4 months) compared with those who did not (30.0 months, P = 0.003), especially when receiving radiochemotherapy (106.7 months, P = 0.027). One patient (2.8%) had a complete response (CR) and nine patients (25.0%) achieved a partial response (PR) for an objective response rate of 27.8% with median response duration of 11 months (range: 4–93). Eighteen patients (50.0%) had disease stabilization for a disease control rate (DCR) of 77.8%. More patients receiving trabectedin in 1st-line of advanced disease achieved CR (16.7%) and PR (50.0%) than those in = 2nd line/s (0.0% and 20.0%), whereas the DCR was similar across treatment lines. Reversible neutropenia was the most common grade 3/4 laboratory abnormality (19.4%). Conclusions: Trabectedin confers clinical benefit in patients with recurrent/metastatic uLMS, given after failure to an anthracycline-based regimen being comparable to those reported in clinical trials and with a manageable safety profile

    Critical Role of Oxygen in Silver-Catalyzed Glaser-Hay Coupling on Ag(100) under Vacuum and in Solution on Ag Particles

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    The essential role of oxygen in enabling heterogeneously catalyzed Glaser-Hay coupling of phenylacetylene on Ag(100) was elucidated by STM, laboratory and synchrotron photoemission, and DFT calculations. In the absence of coadsorbed oxygen, phenylacetylene formed well-ordered dense overlayers which, with increasing temperature, desorbed without reaction. In striking contrast, even at 120 K, the presence of oxygen led to immediate and complete disruption of the organic layer due to abstraction of acetylenic hydrogen with formation of a disordered mixed layer containing immobile adsorbed phenylacetylide. At higher temperatures phenylacetylide underwent Glaser-Hay coupling to form highly ordered domains of diphenyldiacetylene that eventually desorbed without decomposition, leaving the bare metal surface. DFT calculations showed that, while acetylenic H abstraction was otherwise an endothermic process, oxygen adatoms triggered a reaction-initiating exothermic pathway leading to OH(a) + phenylacetylide, consistent with the experimental observations. Moreover, it was found that, with a solution of phenylacetylene in nonane and in the presence of O, Ag particles catalyzed Glaser-Hay coupling with high selectivity. Rigorous exclusion of oxygen from the reactor strongly suppressed the catalytic reaction. Interestingly, too much oxygen lowers the selectivity toward diphenyldiacetylene. Thus, vacuum studies and theoretical calculations revealed the key role of oxygen in the reaction mechanism, subsequently borne out by catalytic studies with Ag particles that confirmed the presence of oxygen as a necessary and sufficient condition for the coupling reaction to occur. The direct relevance of model studies to a mechanistic understanding of coupling reactions under conditions of practical catalysis was reaffirmed.Support from the European Union FEDER Program and MINECO under projects MAT2013-40852-R and 201560E055 is acknowledged. Computational resources were provided by the Spanish Ministerio de Economía y Competitividad, grant CTQ2015-64669-P, and the EU FEDER Program

    Influence of the chemical and electronic structure on the electrical behavior of zirconium oxynitride films

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    This work is devoted to the investigation of decorative zirconium oxynitride, ZrOxNy, films prepared by dc reactive magnetron sputtering, using a 17:3 nitrogen-to-oxygen-ratio gas mixture. The color of the films changed from metallic-like, very bright yellow pale, and golden yellow, for low gas mixture flows [from 0 to about 9 SCCM (SCCM denotes cubic centimeter per minute at STP)] to red brownish for intermediate gas flows (values up to 12 SCCM). Associated to this color change there is a significant decrease of brightness. With further increase of the reactive gas flow, the color of the samples changed from red brownish to dark blue (samples prepared with 13 and 14 SCCM). The films deposited with gas flows above 14 SCCM showed only apparent colorations due to interference effects. This change in optical behavior from opaque to transparent (characteristic of a transition from metallic to insulating-type materials), promoted by the change in gas flow values, revealed that significant changes were occurring in the film structure and electronic properties, thus opening new potential applications for the films, beyond those of purely decorative ones. Taking this into account, the electrical behavior of the films was investigated as a function of the reactive gas flow and correlated with the observed chemical, electronic, and structural features. The variations in composition disclosed the existence of four different zones, which were correlated to different crystalline structures. For the so-called zone I, x-ray diffraction revealed the development of films with a B1 NaCl face-centered cubic zirconium nitride-type phase, with some texture changes. Increasing the reactive gas flow, the structure of the films is that of a poorly crystallized over-stoichiometric nitride phase, which may be similar to that of Zr3N4, but with some probable oxygen inclusions within nitrogen positions. This region was characterized as zone II. Zone III was indexed as an oxynitride-type phase, similar to that of gamma-Zr2ON2 with some oxygen atoms occupying some of the nitrogen positions. Finally, occurring at the highest flow rates, zone IV was assigned to a ZrO2 monoclinic-type structure. The composition/structure variations were consistent with the chemical bonding analysis carried out by x-ray photoelectron spectroscopy, which showed oxygen doping in both Zr3N4- and ZrN-type grown films. The electronic properties of the films exhibited significant changes from zone to zone. Resistivity measurements revealed a very wide range of values, varying from relatively highly conductive materials (for zone I) with resistivity values around few hundreds of micro-ohm cm to highly insulating films within zones III and IV, which presented resistivity values in the order of 1015 micro-ohm cm. Regarding zone II, corresponding to oxygen doped Zr3N4-type compounds, the observed behavior revealed resistivity values increasing steeply from about 103 up to 1015 micro-ohm cm, indicating a systematic transition from metallic to insulating regimes.Fundação para a Ciência e Tecnologia (FCT) -PTDC/CTM/69362/2006, SFRH/BD/31907/2006 and SFRH/BBD/27114/2006

    A Systematic Review of the Efficacy and Toxicity of Brachytherapy Boost Combined with External Beam Radiotherapy for Nonmetastatic Prostate Cancer

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    Context The optimum use of brachytherapy (BT) combined with external beam radiotherapy (EBRT) for localised/locally advanced prostate cancer (PCa) remains uncertain. Objective To perform a systematic review to determine the benefits and harms of EBRT-BT. Evidence acquisition Ovid MEDLINE, Embase, and EBM Reviews—Cochrane Central Register of Controlled Trials databases were systematically searched for studies published between January 1, 2000 and June 7, 2022, according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Eligible studies compared low- or high-dose-rate EBRT-BT against EBRT ± androgen deprivation therapy (ADT) and/or radical prostatectomy (RP) ± postoperative radiotherapy (RP ± EBRT). The main outcomes were biochemical progression-free survival (bPFS), severe late genitourinary (GU)/gastrointestinal toxicity, metastasis-free survival (MFS), cancer-specific survival (CSS), and overall survival (OS), at/beyond 5 yr. Risk of bias was assessed and confounding assessment was performed. A meta-analysis was performed for randomised controlled trials (RCTs). Evidence synthesis Seventy-three studies were included (two RCTs, seven prospective studies, and 64 retrospective studies). Most studies included participants with intermediate-or high-risk PCa. Most studies, including both RCTs, used ADT with EBRT-BT. Generally, EBRT-BT was associated with improved bPFS compared with EBRT, but similar MFS, CSS, and OS. A meta-analysis of the two RCTs showed superior bPFS with EBRT-BT (estimated fixed-effect hazard ratio [HR] 0.54 [95% confidence interval {CI} 0.40–0.72], p < 0.001), with absolute improvements in bPFS at 5–6 yr of 4.9–16%. However, no difference was seen for MFS (HR 0.84 [95% CI 0.53–1.28], p = 0.4) or OS (HR 0.87 [95% CI 0.63–1.19], p = 0.4). Fewer studies examined RP ± EBRT. There is an increased risk of severe late GU toxicity, especially with low-dose-rate EBRT-BT, with some evidence of increased prevalence of severe GU toxicity at 5–6 yr of 6.4–7% across the two RCTs. Conclusions EBRT-BT can be considered for unfavourable intermediate/high-risk localised/locally advanced PCa in patients with good urinary function, although the strength of this recommendation based on the European Association of Urology guideline methodology is weak given that it is based on improvements in biochemical control. Patient summary We found good evidence that radiotherapy combined with brachytherapy keeps prostate cancer controlled for longer, but it could lead to worse urinary side effects than radiotherapy without brachytherapy, and its impact on cancer spread and patient survival is less clear

    Impact of Epithelial Histological Types, Subtypes, and Growth Patterns on Oncological Outcomes for Patients with Nonmetastatic Prostate Cancer Treated with Curative Intent: A Systematic Review

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    Context The optimal management for men with prostate cancer (PCa) with unconventional histology (UH) is unknown. The outcome for these cancers might be worse than for conventional PCa and so different approaches may be needed. Objective To compare oncological outcomes for conventional and UH PCa in men with localized disease treated with curative intent. Evidence acquisition A systematic review adhering to the Referred Reporting Items for Systematic Reviews and Meta-Analyses was prospectively registered on PROSPERO (CRD42022296013) was performed in July 2021. Evidence synthesis We screened 3651 manuscripts and identified 46 eligible studies (reporting on 1 871 814 men with conventional PCa and 6929 men with 10 different PCa UHs). Extraprostatic extension and lymph node metastases, but not positive margin rates, were more common with UH PCa than with conventional tumors. PCa cases with cribriform pattern, intraductal carcinoma, or ductal adenocarcinoma had higher rates of biochemical recurrence and metastases after radical prostatectomy than for conventional PCa cases. Lower cancer-specific survival rates were observed for mixed cribriform/intraductal and cribriform PCa. By contrast, pathological findings and oncological outcomes for mucinous and prostatic intraepithelial neoplasia (PIN)-like PCa were similar to those for conventional PCa. Limitations of this review include low-quality studies, a risk of reporting bias, and a scarcity of studies that included radiotherapy. Conclusions Intraductal, cribriform, and ductal UHs may have worse oncological outcomes than for conventional and mucinous or PIN-like PCa. Alternative treatment approaches need to be evaluated in men with these cancers. Patient summary We reviewed the literature to explore whether prostate cancers with unconventional growth patterns behave differently to conventional prostate cancers. We found that some unconventional growth patterns have worse outcomes, so we need to investigate if they need different treatments. Urologists should be aware of these growth patterns and their clinical impact

    Autosomal recessive cerebellar ataxias

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    Autosomal recessive cerebellar ataxias (ARCA) are a heterogeneous group of rare neurological disorders involving both central and peripheral nervous system, and in some case other systems and organs, and characterized by degeneration or abnormal development of cerebellum and spinal cord, autosomal recessive inheritance and, in most cases, early onset occurring before the age of 20 years. This group encompasses a large number of rare diseases, the most frequent in Caucasian population being Friedreich ataxia (estimated prevalence 2–4/100,000), ataxia-telangiectasia (1–2.5/100,000) and early onset cerebellar ataxia with retained tendon reflexes (1/100,000). Other forms ARCA are much less common. Based on clinicogenetic criteria, five main types ARCA can be distinguished: congenital ataxias (developmental disorder), ataxias associated with metabolic disorders, ataxias with a DNA repair defect, degenerative ataxias, and ataxia associated with other features. These diseases are due to mutations in specific genes, some of which have been identified, such as frataxin in Friedreich ataxia, α-tocopherol transfer protein in ataxia with vitamin E deficiency (AVED), aprataxin in ataxia with oculomotor apraxia (AOA1), and senataxin in ataxia with oculomotor apraxia (AOA2). Clinical diagnosis is confirmed by ancillary tests such as neuroimaging (magnetic resonance imaging, scanning), electrophysiological examination, and mutation analysis when the causative gene is identified. Correct clinical and genetic diagnosis is important for appropriate genetic counseling and prognosis and, in some instances, pharmacological treatment. Due to autosomal recessive inheritance, previous familial history of affected individuals is unlikely. For most ARCA there is no specific drug treatment except for coenzyme Q10 deficiency and abetalipoproteinemia
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