Surface Energy and Lewis Acid-base Characteristics of Lignocellulosic Fibers upon Modification by Chemical Vapor Deposition of Trichloromethylsilane: An Inverse Gas Chromatography Study

Supplemental data for this article can be accessed on the publisher’s website at http:// dx.doi.org/10.1080/02773813.2018.1454961The surface of a thermomechanical pulp (TMP), containing 26 wt% of lignin, was modified by silanization with trichloromethylsilane (TCMS) via chemical vapor deposition, and thoroughly analyzed for its physicochemical properties by inverse gas chromatography (attenuated total reflection-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy being used as complementary tools). For a 2-min TCMS-treated TMP, a decrease of the dispersive component of the surface energy from 38 to 14 mJ m−2 (at 40°C), and, at the same time, an increase of the Lewis acidic and Lewis basic characters were found. The surface of this sample, modified in a high extent, was similar to that of a bleached kraft pulp (<0.1 wt% of lignin) subjected to the same silanization process, which is suggested as being due, in both cases, to the formation of a methyl-silica coating on the fiber’s surface. The new silanized fibers obtained from cheap TMP can be used for the production of a new generation of biocomposites with a variety of matrices

Mechanical Characterization of Tungsten-Titanium-Lanthana alloy: Influence of Temperature and Atmosphere

The target is to evaluate the mechanical behavior of Ti and La2O3 dispersed W alloy, processed by HIP and compare it with a reference pure-W. Tests were performed in both oxidant (air) and inert (vacuum) atmosphere in a temperature range from -196 to 1200 °C

Study in COMSOL of the generation of traveling waves in an AEF robot by piezoelectric actuation

[Abstract] This paper presents a study of motion of an artificial eukaryotic flagellum (AEF) microrobot in COMSOL Multiphysics®. The microrobot is essentially a body, consisting of an aluminum beam structure with two piezoelectric patches bonded on its surface. It requires the same voltage with different frequencies or phases be applied to each piezoelectric or use one of the piezoelectrics as absorber in order to generate a traveling wave on the body. Different types of actuation are simulated to demonstrate that a non-reciprocal motion can be obtained with this kind of configuration.[Abstract] Este artículo presenta un estudio del movimiento de un microrobot de eukaryotic flagellum (AEF) en COMSOL Multiphysics®. El microrobot es esencialmente un cuerpo, que consiste en una estructura de vigas de aluminio con dos parches piezoeléctricos adheridos en su superficie. Requiere que se aplique la misma tensión con diferentes frecuencias o fases a cada piezoeléctrico o use uno de los piezoeléctricos como absorbente para generar una onda viajera en el cuerpo. Se simulan diferentes tipos de actuación para demostrar que se puede obtener un movimiento no recíproco con este tipo de configuración.Ministerio de Economía y Competitividad; DPI2016-80547-

Frequency response of IPMC actuators: physical characterization and identification for control

[Abstract] Ionic polymer metal composite (IPMC) actuators have promising applications in robotics and medicine in a not distance future, which will require a big knowledge in different fields, such as, manufacturing, material characterization and control theory. In this paper, frequency response of several IPMC actuators, cut from the same bulk IPMC sheet with a micro laser etching machine, is analyzed. Specifically, the objective is to 1) characterize each actuator, i.e., determine how cutting affects to the parameters of the physical model of this kind of actuators, and 2) identify a model for each actuator for control purposes. The frequency responses have been obtained experimentally in LabVIEW by attaching a couple of gold electrodes to each IPMC unit and measuring the tip deection by means of a laser distance meter.[Resumen] Los actuadores de compuesto de polímero metálico iónico (IPMC) tienen aplicaciones prometedoras en robótica y medicina en un futuro no lejano, lo que requerirá un gran conocimiento en diferentes campos, como la fabricación, la caracterización de materiales y la teoría de control. En este documento, se analiza la respuesta de frecuencia de varios actuadores IPMC, cortados de la misma hoja de IPMC a granel con una máquina de grabado por láser micro. Específicamente, el objetivo es 1) caracterizar cada actuador, es decir, determinar cómo afecta el corte a los parámetros del modelo físico de este tipo de actuadores, y 2) identificar un modelo para cada actuador con fines de control. Las respuestas de frecuencia se han obtenido experimentalmente en LabVIEW al conectar un par de electrodos de oro a cada unidad IPMC y medir la división de la punta por medio de un medidor de distancia láser.Ministerio de Economía y Competitividad; DPI2016-80547-

Behavior of Cu-Y2O3 and CuCrZr-Y2O3 composites before and after irradiation

ABSTRACT: The Cu-Y2O3 and CuCrZr-Y2O3 materials have been devised as thermal barriers in nuclear fusion reactors. It is expected that in the nuclear environments, the materials should be working on extreme conditions of irradiation. In this work the Cu-Y2O3 and CuCrZr-Y2O3 were prepared and then irradiated in order to understand the surface irradiation resistance of the material. The composites were prepared in a glove box and consolidated with spark plasma sintering. The microstructures revealed regions of Y2O3 dispersion and Y2O3 agglomerates both in the Cu matrix and in the CuCrZr. The irradiated samples did not show any surface modification indicating that the materials seem to be irradiation resistant in the present situation. The thermal conductivity values for all the samples measured are lower than pure Cu and higher than pure W, however are higher than those expected, and therefore, the application of these materials as thermal barriers is compromised.info:eu-repo/semantics/publishedVersio

Self-passivating W-Cr-Y alloys: characterization and testing

The use of self-passivating tungsten alloys for the first wall armor of future fusion reactors is advantageous concerning safety issues in comparison with pure tungsten. Bulk W-10Cr-0.5Y alloy manufactured by mechanical alloying followed by HIP resulted in a fully dense material with grain size around 100 nm and a dispersion of Y-rich oxide nanoparticles located at the grain boundaries. An improvement in flexural strength and fracture toughness was observed with respect to previous works. Oxidation tests under isothermal and accident-like conditions revealed a very promising oxidation behavior for the W-10Cr-0.5Y alloy. Thermo-shock tests at JUDITH-1 to simulate ELM-like loads resulted in a crack network at the surface with roughness values lower than those of a pure W reference material. An additional thermal treatment at 1550 °C improves slightly the oxidation and thermo-shock resistance of the alloy

Microstructural and mechanical characteristics of W-2Ti and W-1TiC processed by Hot Isostatic Pressing

It has been demonstrated that mechanical alloying and subsequent consolidation by hot isostatic pressing (HIP) is a successful route to produce dispersion strengthened W alloys with properties satisfying the design requirements of particular plasma facing components in the fusion reactor. However, the presence of the alloying element as a phase filling large interstices between W particles appears to reduce the mechanical properties of these alloys. In order to limit this phase separation induced by the HIP treatment and the detrimental effects on the mechanical properties, the enhancement of the mechanical alloying process, and the effect of a postconsolidation heat treatment in an reducing atmosphere, have been investigated

Hexanucleotide Repeat Expansions in c9FTD/ALS and SCA36 Confer Selective Patterns of Neurodegeneration In Vivo

A G4C2 hexanucleotide repeat expansion in an intron of C9orf72 is the most common cause of frontal temporal dementia and amyotrophic lateral sclerosis (c9FTD/ALS). A remarkably similar intronic TG3C2 repeat expansion is associated with spinocerebellar ataxia 36 (SCA36). Both expansions are widely expressed, form RNA foci, and can undergo repeat-associated non-ATG (RAN) translation to form similar dipeptide repeat proteins (DPRs). Yet, these diseases result in the degeneration of distinct subsets of neurons. We show that the expression of these repeat expansions in mice is sufficient to recapitulate the unique features of each disease, including this selective neuronal vulnerability. Furthermore, only the G4C2 repeat induces the formation of aberrant stress granules and pTDP-43 inclusions. Overall, our results demonstrate that the pathomechanisms responsible for each disease are intrinsic to the individual repeat sequence, highlighting the importance of sequence-specific RNA-mediated toxicity in each disorder