160 research outputs found
Ideal, Defective, and Gold--Promoted Rutile TiO2(110) Surfaces: Structures, Energies, Dynamics, and Thermodynamics from PBE+U
Extensive first principles calculations are carried out to investigate
gold-promoted TiO2(110) surfaces in terms of structure optimizations,
electronic structure analyses, ab initio thermodynamics calculations of surface
phase diagrams, and ab initio molecular dynamics simulations. All computations
rely on density functional theory in the generalized gradient approximation
(PBE) and account for on-site Coulomb interactions via inclusion of a Hubbard
correction, PBE+U, where U is computed from linear response theory. This
approach is validated by investigating the interaction between TiO2(110)
surfaces and typical probe species (H, H2O, CO). Relaxed structures and binding
energies are compared to both data from the literature and plain PBE results.
The main focus of the study is on the properties of gold-promoted titania
surfaces and their interactions with CO. Both PBE+U and PBE optimized
structures of Au adatoms adsorbed on stoichiometric and reduced TiO2 surfaces
are computed, along with their electronic structure. The charge rearrangement
induced by the adsorbates at the metal/oxide contact are also analyzed and
discussed. By performing PBE+U ab initio molecular dynamics simulations, it is
demonstrated that the diffusion of Au adatoms on the stoichiometric surface is
highly anisotropic. The metal atoms migrate either along the top of the
bridging oxygen rows, or around the area between these rows, from one bridging
position to the next along the [001] direction. Approximate ab initio
thermodynamics predicts that under O-rich conditions, structures obtained by
substituting a Ti5c atom with an Au atom are thermodynamically stable over a
wide range of temperatures and pressures.Comment: 20 pages, 12 figures, accepted for publication in Phys. Rev.
Solid-state transformers in locomotives fed through AC lines: A review and future developments
One of the most important innovation expectation in railway electrical equipment is the replacement of the on-board transformer with a high power converter. Since the transformer operates at line-frequency (i.e., 50 Hz or 16 2/3 Hz), it represents a critical component from weight point of view and, moreover, it is characterized by quite poor efficiency. High power converters for this application are characterized by a medium frequency inductive coupling and are commonly referred as Power Electronic Transformers (PET), Medium Frequency Topologies or Solid-State Transformers (SST). Many studies were carried out and various prototypes were realized until now, however, the realization of such a system has some difficulties, mainly related to the high input voltage (i.e., 25 kV for 50 Hz lines and 15 kV for 16 2/3 Hz lines) and the limited performance of available power electronic switches. The aim of this study is to present a survey on the main solutions proposed in the technical literature and, analyzing pros and cons of these studies, to introduce new possible circuit topologies for this application
Soft-switching cells for Modular Multilevel Converters for efficient grid integration of renewable sources
The Modular Multilevel Converter (MMC) concept is a modern energy conversion structure that stands out for a number of interesting features that opens wide application chances in Power Systems, for example for efficient grid integration of renewable sources. In these high-voltage, high-power application fields, a high efficiency is mandatory. In this regard, an interesting and promising development opportunity could be to make soft-switching the elementary converters of the submodules (cells), half H-bridges or full H-bridges, obtaining at the same time the advantage of increasing the switching frequency. The-Active Resonant Commutated Pole Converter (ARCP) or the Auxiliary Quasi Resonant DC-link Inverter (AQRDCL) soft-switching topologies appear adequate for this purpose. This paper is dedicated to examining these development possibilities
Clinical Outcomes of Patients With Metastatic Urothelial Carcinoma After Progression to Immune Checkpoint Inhibitors: A Retrospective Analysis by the Meet-Uro Group (Meet-URO 1 Study)
Background: Immune checkpoint inhibitors (ICIs) are currently the standard of care for metastatic urothelial cancer (mUC) after the failure of previous platinum-based chemotherapy. The choice of further therapy after ICI progression is a new challenge, and scarce data support it. We aimed to examine the outcomes of mUC patients after progression to ICI, especially when receiving chemotherapy. Methods: Data were retrospectively collected from clinical records of mUC patients whose disease progressed to anti-programmed death 1 (PD-1)or programmed death ligand 1 (PD-L1) therapy at 14 Italian centers. Patients were grouped according to ICI therapy setting into SALVAGE (ie, ICI delivered ⩾ second-line therapy after platinum-based chemotherapy) and NAÏVE (ie, first-line therapy) groups. Progression-free survival (PFS) and overall survival (OS) rates were calculated using the Kaplan-Meier method and compared among subgroups. Cox regression assessed the effect of treatments after progression to ICI on OS. Objective response rate (ORR) was calculated as the sum of partial and complete radiologic responses. Results: The study population consisted of 201 mUC patients who progressed after ICI: 59 in the NAÏVE cohort and 142 in the SALVAGE cohort. Overall, 52 patients received chemotherapy after ICI progression (25.9%), 20 (9.9%) received ICI beyond progression, 115 (57.2%) received best supportive care only, and 14 (7.0%) received investigational drugs. Objective response rate to chemotherapy in the post-ICI setting was 23.1% (28.0% in the NAÏVE group and 18.5% in the SALVAGE group). Median PFS and OS to chemotherapy after ICI-PD was 5 months (95% confidence interval [CI]: 3-11) and 13 months (95% CI: 7-NA) for the NAÏVE group; 3 months (95% CI: 2-NA) and 9 months (95% CI: 6-NA) for the SALVAGE group, respectively. Overall survival from ICI initiation was 17 months for patients receiving chemotherapy (hazard ratio [HR] = 0.09, p < 0.001), versus 8 months for patients receiving ICI beyond progression (HR = 0.13, p < 0.001), and 2 months for patients who did not receive further active treatment (p < 0.001). Conclusions: Chemotherapy administered after ICI progression for mUC patients is advisable irrespective of the treatment line
Antiproliferative effects of Tubi-bee propolis in glioblastoma cell lines
Propolis is a resin formed by a complex chemical composition of substances that bees collect from plants. Since ancient times, propolis has been used in folk medicine, due to its biological properties, that include antimicrobial, anti-inflammatory, antitumoral and immunomodulatory activities. Glioblastoma is the most common human brain tumor. Despite the improvements in GBM standard treatment, patients’ prognosis is still very poor. The aim of this work was to evaluate in vitro the Tubi-bee propolis effects on human glioblastoma (U251 and U343) and fibroblast (MRC-5) cell lines. Proliferation, clonogenic capacity and apoptosis were analyzed after treatment with 1 mg/mL and 2 mg/mL propolis concentrations for different time periods. Additionally, glioblastoma cell lines were submitted to treatment with propolis combined with temozolomide (TMZ). Data showed an antiproliferative effect of tubi-bee propolis against glioblastoma and fibroblast cell lines. Combination of propolis with TMZ had a synergic anti-proliferative effect. Moreover, propolis caused decrease in colony formation in glioblastoma cell lines. Propolis treatment had no effects on apoptosis, demonstrating a cytostatic action. Further investigations are needed to elucidate the molecular mechanism of the antitumor effect of propolis, and the study of its individual components may reveal specific molecules with antiproliferative capacity
Axitinib after Sunitinib in Metastatic Renal Cancer: Preliminary Results from Italian "Real-World" SAX Study.
Axitinib is an oral angiogenesis inhibitor, currently approved for treatment of metastatic renal cell carcinoma (mRCC) after failure of prior treatment with Sunitinib or cytokine. The present study is an Italian Multi-Institutional Retrospective Analysis that evaluated the outcomes of Axitinib, in second-line treatment of mRCC. The medical records of 62 patients treated with Axitinib, were retrospectively reviewed. The Progression Free Survival (PFS), the Overall Survival (OS), the Objective Response Rate (ORR), the Disease Control Rate (DCR), and the safety profile of axitinib and sunitinib–axitinib sequence, were the primary endpoint. The mPFS was 5.83 months (95% CI 3.93–7.73 months). When patients was stratified by Heng score, mPFS was 5.73, 5.83, 10.03 months according to poor, intermediate, and favorable risk group, respectively. The mOS from the start of axitinib was 13.3 months (95% CI 8.6–17.9 months); the observed ORR and DCR were 25 and 71%, respectively. When stratified patients by subgroups defined by duration of prior therapy with Sunitinib (≤ vs. >median duration), there was a statistically significant difference in mPFS with 8.9 (95% CI 4.39–13.40 months) vs. 5.46 months (95% CI 4.04–6.88 months) for patients with a median duration of Sunitinib >13.2 months. DCR and ORR to previous Sunitinib treatment was associated with longer statistically mPFS, 7.23 (95% CI 3.95–10.51 months, p = 0.01) and 8.67 (95% CI 4.0–13.33 months, p = 0.008) vs. 2.97 (95% CI 0.65–5.27 months, p = 0.01) and 2.97 months (95% CI 0.66–5.28 months, p = 0.01), respectively. Overall Axitinib at standard schedule of 5 mg bid, was well-tolerated. The most common adverse events of all grades were fatig (25.6%), hypertension (22.6%), gastro-intestinal disorders (25.9%), and hypothyroidism (16.1%). The sequence Sunitinib–Axitinib was well-tolerated without worsening in side effects, with a median OS of 34.7 months (95% CI 18.4–51.0 months). Our results are consistent with the available literature; this retrospective analysis confirms that Axitinib is effective and safe in routine clinical practice
Discovery of a single male Aedes aegypti (L.) in Merseyside, England
© The Author(s). 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. The file attached is the published (publishers PDF) version of the article
siRNA-Mediated Gene Targeting in Aedes aegypti Embryos Reveals That Frazzled Regulates Vector Mosquito CNS Development
Although mosquito genome projects uncovered orthologues of many known developmental regulatory genes, extremely little is known about the development of vector mosquitoes. Here, we investigate the role of the Netrin receptor frazzled (fra) during embryonic nerve cord development of two vector mosquito species. Fra expression is detected in neurons just prior to and during axonogenesis in the embryonic ventral nerve cord of Aedes aegypti (dengue vector) and Anopheles gambiae (malaria vector). Analysis of fra function was investigated through siRNA-mediated knockdown in Ae. aegypti embryos. Confirmation of fra knockdown, which was maintained throughout embryogenesis, indicated that microinjection of siRNA is an effective method for studying gene function in Ae. aegypti embryos. Loss of fra during Ae. aegypti development results in thin and missing commissural axons. These defects are qualitatively similar to those observed in Dr. melanogaster fra null mutants. However, the Aa. aegypti knockdown phenotype is stronger and bears resemblance to the Drosophila commissureless mutant phenotype. The results of this investigation, the first targeted knockdown of a gene during vector mosquito embryogenesis, suggest that although Fra plays a critical role during development of the Ae. aegypti ventral nerve cord, mechanisms regulating embryonic commissural axon guidance have evolved in distantly related insects
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