Ethyl group as matrix modifier and inducer of ordered domains in hybrid xerogels synthesised in acidic media using ethyltriethoxysilane (ETEOS) and tetraethoxysilane (TEOS) as precursors

Hybrid silica xerogels favourably combine the properties of organic and inorganic components in one material; consequently these materials are useful for multiple applications. The versatility and mild synthetic conditions provided by the sol-gel process are ideal for the synthesis of hybrid materials. The specific aims of this study were to synthesise hybrid xerogels in acidic media using tetraethoxysilane (TEOS) and ethyltriethoxysilane (ETEOS) as silica precursors, and to assess the role of the ethyl group as a matrix modifier and inducer of ordered domains in xerogels. All xerogels were synthesised at pH 4.5, at 60 °C, with 1:4.75:5.5 TEOS:EtOH:H₂O molar ratio. Gelation time exponentially increased with the ETEOS molar ratio. Incorporation of the ethyl groups into the structure of xerogels reduced cross-linking, increased the average siloxane bond length, and promoted the formation of ordered domains. As a result, a transition from Qⁿ to Tⁿ signals detected in the ²⁹Si NMR spectra, the Si–O structural band in the FTIR spectra shifted to lower wavelength, and a new peak in the XRD pattern at 2θ < 10° appeared in the XRD patterns. Mass spectroscopy detected fragments with high numbers of silicon atoms and a polymeric distribution.     

Evaluation of the effect of heat input in superduplex stainless steel deposition by the plasma powder process*

Plasma powder surfacing is one of the latest processes for application of coatings, with control of dilution as its main feature. Surfacing with superduplex stainless steels is an interesting option for the construction and repair of equipment for applications in a highly corrosive environment, allowing the desired characteristics to be achieved: corrosion resistance and good mechanical properties. The aim of this work is to assess the ferrite content in the weld metal and the mechanical characteristics via microhardness profiles in surfacing of C-Mn steel pipes with deposition of UNS S32760 by plasma powder surfacing. Welding operations were carried out on pipes with deposition of SDSS, employing three welding heat input levels, varying the welding speed or the welding current. Then the geometry was analysed, the ferrite content in the weld metal was quantified and the microhardness profile was recorded. Variation in welding heat input caused changes in weld bead geometry, with variation in the welding current producing the most significant changes. Increase in heat input caused decrease in ferrite content of the weld metal. Regarding microhardness, only the condition with a higher level of welding current gave sufficiently high levels of microhardness in the weld metal.     

Corn grain-processing method interacts with calcium salts of palm fatty acids supplementation on milk production and energy balance of early-lactation cows grazing tropical pasture

The objective of our study was to investigate the associative effects of feeding Ca salts of palm fatty acids (FA) and corn grain-processing method on production, nutrient digestibility, energy balance, and carryover effects of early-lactation dairy cows grazing a tropical pasture. Treatment diets were offered from 3 to 16 wk postpartum (treatment period), in which all cows grazed elephant grass (Pennisetum purpureum L. Cameroon) and treatments were added to a concentrate supplement. Treatments were flint corn grain-processing method either as fine ground (FGC) or steam-flaked (SFC) associated with Ca salts of palm FA supplementation either not supplemented or supplemented (CSPO). From 17 to 40 wk postpartum (carryover period) all cows received a common diet fed as total mixed ration. During the treatment period, a tendency for an interaction between CSPO and corn grain-processing method were observed for milk yield, milk fat yield, and energy-corrected milk (ECM), as CSPO caused them to increased to a greater extent in the FGC diet compared with the SFC diet. Furthermore, a tendency for an interaction between CSPO and corn grain-processing method was observed for body weight change, because CSPO increased body weight loss in the FGC diet but not in the SFC diet. The CSPO increased milk yield, milk fat yield, 3.5% fat-corrected milk, ECM, and cumulative milk yield compared with not supplemented. Also, CSPO increased energy intake, milk energy output, and energy partitioning toward milk, whereas reduced energy was allocated to body reserves. The SFC increased milk yield, ECM, milk protein yield, milk casein yield, and cumulative milk yield, and decreased milk urea N compared with FGC. The SFC compared with FGC also increased body condition score and body weight change, and increased energy partitioning toward body reserves. During the carryover period, an interaction between CSPO and corn grain-processing method was observed for milk yield, which occurred because CSPO maintained higher milk yield in the FGC diet but not in the SFC diet. Therefore, in the carryover period, the additive effect between SFC and CSPO that occurred in the treatment period was not maintained throughout the carryover period. However, CSPO increased yields of milk fat, protein, casein as well as fat-corrected milk and ECM. In conclusion, corn grain-processing method interacts with CSPO supplementation on production responses and carryover effects of grazing cows. When CSPO was fed in the FGC diet, milk production increased to a greater extent than when fed in the SFC diet, but also caused greater mobilization of reserves at early lactation. This suggests an interaction between fat supplementation and corn grain-processing method on energy partitioning of dairy cows. Also, both supplementation with CSPO and SFC were effective strategies to increase energy intake and yields of milk and milk solids. The carryover effect on milk production was greater for CSPO supplementation than corn grain-processing method, whereas feeding SFC diets had lower mobilization of reserves and less body weight and body condition score variation throughout lactation.     

Playing on a holo-stage: towards the interaction between real and virtual performers

This paper presents a number of ongoing projects that will be valuable to the development of technologies for digital theatre and performance. This paper describes an EU ACTS project called RESOLV which develops an integrated system to capture real 3D environments using laser and video. Current research on motion tracking, statistical behaviour modelling and simulation is presented, and possible applications, both for visual augmentation and audio generation, are discussed. The projects presented were not originally designed in the domain of theatre and performance, however their results and output seem to be well suited to be applied in this area.     

Propagating and evanescent waves associated with inhibited reflection in uniaxial crystals: Extraordinary incidence

Abstract

When an extraordinary wave under inhibited reflection conditions is incident on an interface between a uniaxial crystal and an isotropic medium, the reflected extraordinary wave is evanescent and the polarization of the refracted wave changes from linear to elliptical. In the present paper it is shown that the refracted ray undergoes a shift which is not only longitudinal (as the Goos—Hänchen effect in total reflection in isotropic interfaces) but also transversal. The structure of the evanescent reflected wave is studied and the polarization of the transmitted wave is analysed.     

Computing the lowest equilibrium pose of a cable-suspended rigid body

We solve the problem of finding the lowest stable-equilibrium pose of a rigid body subjected to gravity and suspended in space by an arbitrary number of cables. Besides representing a contribution to fundamental rigid-body mechanics, this solution finds application in two areas of robotics research: underconstrained cable-driven parallel robots and cooperative towing. The proposed approach consists in globally minimizing the rigid-body potential energy. This is done by applying a branch-and-bound algorithm over the group of rotations, which is partitioned into boxes in the space of Euler-Rodrigues parameters. The lower bound on the objective is obtained through a semidefinite relaxation of the optimization problem, whereas the upper bound is obtained by solving the same problem for a fixed orientation. The resulting algorithm is applied to several examples drawn from the literature. The reported Matlab implementation converges to the lowest stable equilibrium pose generally in a few seconds for cable-robot applications. Interestingly, the proposed method is only mildly sensitive to the number of suspending cables, which is shown by solving an example with 1000 cables in two hours.     

pH-responsive drug delivery system based on hollow silicon dioxide micropillars coated with polyelectrolyte multilayers

We report on the fabrication of polyelectrolyte multilayer-coated hollow silicon dioxide micropillars as pH-responsive drug delivery systems. Silicon dioxide micropillars are based on macroporous silicon formed by electrochemical etching. Due to their hollow core capable of being loaded with chemically active agents, silicon dioxide micropillars provide additional function such as drug delivery system. The polyelectrolyte multilayer was assembled by the layer-by-layer technique based on the alternative deposition of cationic and anionic polyelectrolytes. The polyelectrolyte pair poly(allylamine hydrochloride) and sodium poly(styrene sulfonate) exhibited pH-responsive properties for the loading and release of a positively charged drug doxorubicin. The drug release rate was observed to be higher at pH 5.2 compared to that at pH 7.4. Furthermore, we assessed the effect of the number of polyelectrolyte bilayers on the drug release loading and release rate. Thus, this hybrid composite could be potentially applicable as a pH-controlled system for localized drug release.     

Airborne hyperspectral mapping of trees in an urban area

The management of trees in urban areas requires accurate maps, which are difficult to build in the dense patchwork of numerous material properties. Remote sensing is a useful technique that measures the response of all vegetation occurrences, including trees, when high spatial resolution is available. The continuous narrow spectral bands of hyperspectral images enable the detection of the oxygen and water content, which ensures a perfect correction of the atmospheric effect. When calibrated, sunlight reflectance images can be used to map surface chemical compositions by the detection of diagnostic and sharp absorption features. In the visible and near- infrared, the vegetation is detected by chlorophyll-a absorption features that are characteristic of the pigment content. The reflectance intensities due to the texture of leaves occur between 450 and 920 nm while the water content imprint is detectable beyond 920 nm. The sharp spectral feature intensities of the main associated pigments, not only chlorophylls, are well quantified by indices measuring a normalized difference of reflectance in a spectral interval between two bounding wavelengths. A regression line calculated on all bands within that interval ensures a low sensitivity of the indices to the smaller variations in reflectance intensity. Such unbiased indices may be combined, using successive index thresholds deduced from a training spectral library, to divide the spectra into subsets, minimizing the confusion between the numerous vegetation types with almost identical compositions. Therefore, for each subset of the spectra, a classic spectral angle mapping (SAM) method can be used on the corresponding sub-selection of the spectral library to measure angles at full spectral resolution and map tree types with great accuracy, grouped according to their spectral similarity. In this study, chemical and physical information is carefully separated. The tree crown physical properties are studied by comparing the local juxtaposition of pixel sets to a characteristic texture identifiable by image segmentation into objects. Instead of looking for objects in the reflectance image or any statistical compression of its information, a 25 channel co-image, built from 11 information layers of chemical sharp spectral feature indices and 14 information layers of SAM indices matching a spectral library of reference vegetation groups, was used. Tree canopies also present wide internal variations due to (i) a complex mixture with a background in the case of sparse foliage, or (ii) pigment content adaptation to light exposure intensity from one side to another. Both effects are minimized by using the mean spectrum of each object, assuming that less significant spectra, being at plus or minus one or two standard deviations from an object mean spectrum, would be less affected by anomalous pixel data. Thus, two overlapping hierarchic layers at the pixel scale and the object scale are available to describe the main chemistry or pigment content that identifies the vegetation types. The final classification is given by the upper layer at the object scale but in such an organization, the pixel scale layers can be used to analyse the data further and reorder them to obtain other parameters potentially useful for management purposes.     

Investigation of the Thermal Behavior of Polypyrrole/Carbon Nanotube Composites and Utilization as Capacitive Material or Support for Catalysts

In this study, polypyrrole (PPy)/carbon nanotube (CNT) composites were synthesized by in situ chemical oxidative polymerization of a pyrrole monomer on CNT. Two different types of CNT having different structural properties were used. The composites were characterized using BET surface area analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) techniques. Thermal decomposition kinetics of PPy/CNT composites was studied by thermal gravimetric analysis techniques (TG/DTG (differential thermal gravimetric)) at different heating rates (2.5, 5, 7.5, and 10?K min^?1). Kinetic parameters of the composites were obtained from the TG and DTG curves using the Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO) models. The electrochemical capacitive properties of the composites were investigated by the cyclic voltammetry (CV) technique. Pt nanoparticles were decorated on the plain CNTs and composite materials via the microwave irradiation method.