209 research outputs found

    Semiconductor-metal core-shell nanostructures by colloidal heterocoagulation in aqueous medium

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    In contrast to complex syntheses for the preparation of colloidal nanocomposites in a core-shell structure proposed in the literature, we present herein a facile colloidal route based on a heterocoagulation process promoted by the electrostatic interaction among ceramic NiO nanoplatelets and metallic Ni nanoparticles (NPs). Before the heterocoagulation process, NiO and Ni were synthetized separately in presence of ultrasound, by chemical precipitation and chemical reduction of the same nickel precursor, respectively. After that, NiO-Ni core-shell nanostructures were prepared forcing the electrostatic interaction among surfaces in aqueous medium. The surface charge balances of both types of particles were tuned effectively by adjusting the pH in a free-additives suspension. For the surface modification of NiO by Ni, the ceramic suspensions maintain a positive zeta potential at pH 9, while the surface of metallic particles is negatively charged. Then the uniform coating of NiO platelets, by the electrostatically induced coagulation with Ni NPs, was favors. The degree of coverage and the formation of NiO-Ni core-shell nanostructures were followed referring the evolution of zeta potential with the geometric calculation in terms of size and morphology of both nanoparticles, and then corroborated by field emission scanning electron microscopy (FESEM).The authors acknowledge the support of the projects S2013/MIT-2862 and MAT2012–38650-02–01, MAT2012–38650-C02–02. M. de Dios acknowledges MINECO through the grant FPI-2013 and Dr. Z González acknowledges to MINECO through the grant PTQ-13–05985

    Study of the expression of ecfG1 and ecfG2, two extracytoplasmic function sigma factors (ECFs) in Sphingopyxis granuli estirpe TFA

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    Motivation: In bacteria, the initiation of transcription requires a specific multi-domain subunits of RNA polymerase (RNAP) called sigma (σ) factors that binds to its core that play critical roles, including the recognition and opening of promoters for the RNA synthesis (Paget, 2015). One type of sigma factors are extracytoplasmic function sigma factors (ECF) which provide a means of regulating gene expression in response to a wide range of environmental changes (Feklistov et al., 2014). Sphingopyxis granuli TFA is a Gram-negative Alphaproteobacteria that is one of the few strains able to grow on the organic solvent tetralin as a sole carbon and energy source and able to grow respiring nitrate under anaerobic conditions (Gonzalez-Flores et al., 2016). In Sphingopyxis granuli TFA two ECF σ factors have been described, EcfG1 and EcfG2, that have a critcal biological role in the General Stress Response (GSR) in this bacterium (de Dios et al., 2020)Methods: With the aim of studying the transcriptional and postranscriptional regulation of each ecfG genes, a recombinant protein was built in which each EcfG have a FLAG-tag fused which allowed us to quantified the amount of each sigma factor by Western Blot studies in different growth conditions. This protein was constructed using a DNA-recombination method based on a double-strand break caused by SceI nuclease. Flanking regions of each ecfG genes were cloned in a multiple cloning site (MCS) of a non-replicative vector, this MCS is flanked by two SceI target sites. When this integrative vector is integrated into the chromosome of TFA, a broad host range vector including SceI gene downstream of an inducible promoter must be introduced and a double-strand break is caused in the chromosome. The final repair of this break results with a high frequency in the deletion of the target gene (ecfG). Thus we only get the gene with the FLAG-tagResults: In this work we analyzed the levels of expression of each sigma factors both at the transcriptional by RNA-seq and at translational level by quantifying the levels of each protein through Western Blot studies under different growth condition

    Chemical precipitation of nickel nanoparticles on Ti(C,N) suspensions focused on cermet processing

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    Ti(C,N)-based cermets are currently used in high speed cutting tools industry due to its high thermal stability. In previous works, Fe was proposed as metal matrix, however the use of iron as continuous matrix strongly affects the processing due to the low wetting capability of molten Fe with the reinforcement phase, Ti(C,N). To solve this problem, the use of alloys such as FeNi has been proposed, where Ni improves the wettability between the ceramic and the metal phases. This work proposes a bottom-up approach to build the cermet microstructure through the synthesis of metal nanoparticles (NPs) on the surface of Ti(C,N) micrometric particles, creating Ti(C,N)-Ni core-shell structures. For that purpose, the in-situ synthesis of Ni NPs through the chemical reduction of a Ni precursor onto the surface of micrometric Ti(C,N) particles, previously stabilized in an aqueous suspension, was proposed. Core-shell structures were characterized by X-Ray Diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), scanning transmission electron microscopy (STEM), high resolution scanning electron microscopy (HRTEM), energy-dispersive X-Ray spectroscopy (EDX) and Raman Spectroscopy.The authors acknowledge the support of the projects S2013/MIT 2862 MAT2015 70780 C4 1 P and MAT2015 70780 C4 2 P. M. De Dios acknowledges MINECO through the grant BES 2013 065760 and Dr. Z González acknowledges to MINECO through the grant PTQ 13 05985

    Ti(C,N)-Fe/Ni/FeNi core-shell structures for cermets processing

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    Proceedings of : The World PM2016 Congress & Exhibition, Hamburg, Germany, 9-13 October 2016This work proposes an alternative bottom-up approach to build cermet microstructures through the synthesis of metal hydroxide nanoparticles (NPs) on the surface of Ti(C,N) micrometric particles, creating core-shell Ti(C,N)-Ni(OH)2 and Ti(C,N)-FeO(OH) and their subsequent calcination cycle. This calcination cycle will help us to obtain Ti(C,N)- based cermets with fine microstructure and low amount of metal binder avoiding mechanical milling, the risks of handling nanoparticles, as well as overcoming the lack of availability and the high prices of those metal nanoparticles. The obtained structures were characterized by differential thermal analysis (DTA), thermogravimetry (TG), X-Ray Diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-Ray spectroscopy (EDX).The authors acknowledge the support of the projects S2013/MIT-2862, MAT2012-38650-C02-01, MAT2012-38650-C02-02 and MAT2015-70780-C4-1-P. M. Dios acknowledges MINECO through the grant BES-2013-065760 and Dr. Z Gonzalez acknowledges to MINECO through the grant PTQ-13-0598

    Interface study for the design of alternative matrixes in cermets

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    Proceedings of: European Congress and Exhibition on Powder Metallurgy (Euro PM2015 Congress & Exhibition), Reims (France), 4-7 September 2015.Liquid Phase Sintering (LPS) is used in the fabrication of hard materials and cermets which are difficult to densify by other approaches. During this process the melting point of the metal matrix is reached and the solid reinforcement is soluble in it. Thereby, via rearrangement and solucion-reprecipitation mechanism, these composite materials are sintered obtaining hihg density, hardness and wear resistance.For this sintering mechanism it is very important to know the solubility and wetting behaviour at high temperature of the metallic matrix and the reinforcement. In recent years one of the research topics in the field of hard materials is the search for new metallic matrixes so it becomes mandatory to study its interaction with the reinforcement from the viewpoint of solibility and wettability. This work shows a study combination of simulation tools and experimental testing of contacta angle mesurement at high temperature of the system Ni/TiCN because Ni is the conventional metallic matrix used in cermets and it is compared with the systems Fe/TiCN and Fe-15Ni/TiCN because the Fe is the main candidate for an alternative metallic matrix.The authors would like to acknowledge the financial support from the Spanish Government through the project MAT2012-38650-C02-01, the Regional Government of Madrid through the program MULTIMAT-CHALLENGE, ref. S2013/MIT-2862

    Novel colloidal approach for the microstructural improvement in Ti(C,N)/FeNi cermets

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    In this work, the combination of colloidal and powder metallurgy techniques was proposed as an alternative route to produce Ti(C,N)-based cermets with a 15-20 vol% of Fe/Ni alloy (85/15 wt%) as metal matrix. The novelty of this processing route is based in the mixture of fine powders (1;-3 µm) in suspension which promotes the uniformity of the phase distribution and consequently its reactivity, leading to 99.9% dense cermets with 1300 Vickers Hardness (HV30). The preparation of colloidal and chemically stable slurries of non-oxide and metal powders in aqueous media is a key step of the process. Highly concentrated aqueous slurries of Ti(C,N), Fe, Ni and C powders were prepared and mixed. Then bulk pieces were shaped by Slip casting (SC), Slip Casting + Cold Isostatic Pressing (SC-CIP) and Spray-Dry + Uniaxial Pressing of the obtained spherical granules (SDP). The composite formulation and the thermal treatment were optimized to prevent Ni sublimation during sintering as well as to improve liquid phase sintering in terms of wetting and reactivity among well packed particles. The effective dispersion of the slurry and the synergistic effect of combined techniques yielded the preparation of reliable materials by the SDP process with 15 wt% of FeNi with the addition of 0.5 wt% of C. The optimization of the composite formulation and the processing parameters improves both density and hardness of a finer microstructure of the composite after a short sintering treatment (120 min) at 1450 °C in vacuum.The authors acknowledge the financial support from the Spanish Government through the projects MAT2015-70780-C4-1-P and MAT2015-70780-C4-2-P, and the Regional Government of Madrid through the program MULTIMAT CHALLENGE, ref. S2013/MIT-2862. M. Dios acknowledges MINECO through the grant BES-2013-06576

    Observational study of HR+/HER2− metastatic breast cancer patients treated with abemaciclib in Spain in the Named Patient Use Program (AbemusS)

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    Metastatic breast cancer; Abemaciclib; EffectivenessCàncer de mama metastàtic; Abemaciclib; EficàciaCáncer de mama metastásico; Abemaciclib; EficaciaIntroduction/objectives To describe abemaciclib use in patients with hormone receptor-positive, human epidermal growth factor receptor-negative (HR+/HER2−) metastatic breast cancer (mBC) who participated in the Named Patient Use program (NPU) in Spain. Material and methods This retrospective study was based on medical record review of patients across 20 centers during 2018/2019. Patients were followed up until death, enrolment in a clinical trial, loss of follow-up or study end. Clinical and demographic characteristics, treatment patterns and abemaciclib effectiveness were analyzed; time-to-event and median times were estimated using the Kaplan–Meier (KM) method. Results The study included 69 female patients with mBC (mean age 60.4 ± 12.4 years), 86% of whom had an initial diagnosis of early BC and 20% had an ECOG ≥ 2. Median follow-up was 23 months (range 16–28). Metastases were frequently observed in bone (79%) and visceral tissue (65%), with 47% having metastases in > 2 sites. Median number of treatment lines before abemaciclib was 6 (range 1–10). Abemaciclib monotherapy was received by 72% of patients and combination therapy with endocrine therapy by 28% of patients; 54% of patients required dose adjustments, with a median time to first adjustment of 1.8 months. Abemaciclib was discontinued in 86% of patients after a median of 7.7 months (13.2 months for combination therapy and 7.0 months for monotherapy) mainly due to disease progression (69%). Conclusion These results suggest that abemaciclib is effective, as monotherapy and in combination, for patients with heavily pretreated mBC, consistent with clinical trial results.Sponsorship for this study was funded by Lilly. It was conducted with the support of the Clinical Research Organization IQVIA for the following activities: protocol development, site monitoring and statistical analysis

    Reading comprehension: threshold of reading and writing in children of primary education in Malaga

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    Andalucía suele salir mal parada en los Informes PIRLS y PISA sobre comprensión lectora, por lo tanto, conocer cómo y cuándo comienzan nuestros alumnos a tener contacto con la lectura y la escritura es el punto de partida indiscutible para advertir qué mecanismos de aprendizaje están bien estructurados desde el comienzo y cuáles deberían mejorarse. Cuándo, cómo y de qué forma escriben y leen sus primeras palabras, cuáles son y por qué. Partir de estos datos, y de sus conclusiones y reflexiones es útil para adaptar la metodología y poder cimentar la base para otros estudios como un nuevo escalón en el conocimiento de base de la lectora en Andalucía. Toda esta información conforma el conocimiento del germen lecto escritor en nuestros alumnos.Andalucía suele salir mal parada en los Informes PIRLS y PISA sobre comprensión lectora, por lo tanto, conocer cómo y cuándo comienzan nuestros alumnos a tener contacto con la lectura y la escritura es el punto de partida indiscutible para advertir qué mecanismos de aprendizaje están bien estructurados desde el comienzo y cuáles deberían mejorarse. Cuándo, cómo y de qué forma escriben y leen sus primeras palabras, cuáles son y por qué. Partir de estos datos, y de sus conclusiones y reflexiones es útil para adaptar la metodología y poder cimentar la base para otros estudios como un nuevo escalón en el conocimiento de base de la lectora en Andalucía. Toda esta información conforma el conocimiento del germen lecto escritor en nuestros alumnos.Andalucía usually go badly in the PIRLS and PISA reports on reading comprehension, therefore, know how and when our students begin to have contact with reading and writing is the indisputable starting point to warn what learning mechanisms are well structured from the start and what should be improved. All this information forms the seed knowledge reading-writing in our students. From these data, and their findings and useful insights to adapt the methodology and to build the basis for further studies as a new step in the knowledge base of reading comprehension in Andalusia. When, how and how write and read their first words, what and why.Andalucía usually go badly in the PIRLS and PISA reports on reading comprehension, therefore, know how and when our students begin to have contact with reading and writing is the indisputable starting point to warn what learning mechanisms are well structured from the start and what should be improved. All this information forms the seed knowledge reading-writing in our students. From these data, and their findings and useful insights to adapt the methodology and to build the basis for further studies as a new step in the knowledge base of reading comprehension in Andalusia. When, how and how write and read their first words, what and why

    Mechanical characterization of Ti(C,N)-based cermets fabricated through different colloidal processing routes

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    In this work the influence of different colloidal processing routes on the mechanical behavior of several Ti(C,N)-based cermets has been studied. The materials were designed with a Ti(C, N) content ranging between 80 and 85 vol %, in a Fe-Ni alloy matrix (with and without carbon addition). Three processing techniques were investigated: (i) Slip Casting (SC), (ii) Slip Casting + Cold Isostatic Pressing (SC+CIP), and (iii) Spray-Dry + Uniaxial Pressing (SDP). Biaxial strength distributions were determined in all samples using the ball-on-three-balls (B3B) method on disc-shaped specimens. Results were interpreted in the framework of Weibull theory. The characteristic strength ranged between 1090 MPa and 1870 MPa. A fractographic analysis performed on selected specimens showed different critical flaws, depending on the processing route, related to the composition and porosity level in each case. Single Edge V-Notched Beam (SEVNB) specimens fabricated with SDP were tested under 4-point-bending, in order to identify the effect of Fe-Ni content and carbon addition on their fracture resistance. Detailed fractographic analyses revealed slightly different mechanisms of fracture associated with the Fe-Ni and carbon content. Fracture toughness values ranging between similar to 12 and similar to 14 MPa m(1/2) were measured. Based upon these findings the SDP route is proposed to improve both the strength and toughness of Ti(C, N) cermets, which can be enhanced by the addition of carbon during the colloidal processing.The authors acknowledge the financial support from the Spanish Government through the projects MAT2015-70780-C4-1-P and MAT2015-70780-C4-2-P, and the Regional Government of Madrid through the program MULTIMAT-CHALLENGE, ref. S2013/MIT-2862. M.Dios acknowledges MINECO through the grant BES-2013-065760
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