Monofilament composites with carbon nanotubes for textile sensor applications

The aim of this work was to develop polymer matrix/carbon nanotube composite monofilaments to incorporate in textile products, to be used as sensors. The carbon nanotube polymer composite (CPC) monofilaments were produced with the required electrical and mechanical properties for the development of a textile sensor of water vapor. The monofilaments selected were formed by polylactic acid (PLA), and were incorporated directly into the fabrics. The presence of water induced a variation on the electrical conductivity of the filaments. A textile prototype, incorporating sensors and connectors, was produced with the CPC monofilaments developed.Fundação para a Ciência e Tecnologia (FCT) - Inteltex Project, FP

{\it Ab initio} 27Al^{27}Al NMR chemical shifts and quadrupolar parameters for Al2O3Al_2O_3 phases and their precursors

The Gauge-Including Projector Augmented Wave (GIPAW) method, within the Density Functional Theory (DFT) Generalized Gradient Approximation (GGA) framework, is applied to compute solid state NMR parameters for $^{27}Al$ in the $\alpha$, $\theta$, and $\kappa$ aluminium oxide phases and their gibbsite and boehmite precursors. The results for well-established crystalline phases compare very well with available experimental data and provide confidence in the accuracy of the method. For $\gamma$-alumina, four structural models proposed in the literature are discussed in terms of their ability to reproduce the experimental spectra also reported in the literature. Among the considered models, the $Fd\bar{3}m$ structure proposed by Paglia {\it et al.} [Phys. Rev. B {\bf 71}, 224115 (2005)] shows the best agreement. We attempt to link the theoretical NMR parameters to the local geometry. Chemical shifts depend on coordination number but no further correlation is found with geometrical parameters. Instead our calculations reveal that, within a given coordination number, a linear correlation exists between chemical shifts and Born effective charges

Solubilities of some new refrigerants in water

Solubility data for the refrigerants HFC23 (CHF3), HFC32 (CH2F2) and HFC125 (C2HF5) in water have been determined as a function of the temperature in the range of temperatures 288-303 K at atmospheric pressure. These hydrofluorocarbons (HFCs) are good substitutes of the chlorofluorocarbons (CFCs), which have significant impact to stratospheric ozone depletion.http://www.sciencedirect.com/science/article/B6TG2-4177PK4-7/1/12019e8daebba6ccc7515753953406a

Impact of swordfish fisheries on sea turtles in the Azores.

The surface longline fishery around the Azores targets swordfish (Xiphias gladius). Bycatch from this fishery includes loggerhead sea turtles (Caretta caretta) and occasionally leatherback sea turtles (Dermochelys coriacea) that are either hooked or entangled in the lines. Hooks are generally set at depths of 15-50 m and baited with squid, mackerel, or sometimes with shark meat. The size classes of loggerhead sea turtles caught ranged from 41.3 to 65.4 cm curved carapace length and constitutes the largest size class of loggerheads occurring in the Azores. The impact on this size class affects the survival of the southeastern United States (SEUS) population of loggerheads because the loggerheads from the Azores are primarily from SEUS rookeries. For one commercial longline boat, we observed that the mean capture of turtles per 1000 hooks by month ranged between a minimum of 0.04 in May and a maximum of 0.79 in July with a weighted mean catch of 0.27. October and November also registered high catch rates. Of 60 turtles recorded, 54 were hooked in the mouth, 3 in the esophagus, 1 in the eye, 1 in the flipper, and one was undetermined. The turtles that were caught were physically strong, except one that was weak and another dead. Total capture of loggerhead sea turtles is estimated to be 4190 for the entire fleet fishing in the Exclusive Economic Zone of the Azores during the swordfish season (May to December) of 1998. We strongly recommend that observer programs be continued because capture rates may vary among years and among fishing boats

Evidences of exopolysaccharide production by Helicobacter pylori submitted to hydrodynamic stress

Helicobacter pylori is a widespread Gram-negative bacterium that infects the stomach of humans leading to the onset of several gastric disorders, such as gastritis, gastric ulcers, and cancers. The transmission of H. pylori remains unclear but two different pathways have been suggested: faecal-oral and oraloral. It has been reported that H. pylori has the ability to incorporate in biofilms formed on water-exposed surfaces thus providing a route of infection. On the other hand, a polysaccharide-containing biofilm has been observed at the air-liquid interface when H. pylori is grown in a glass fermenter1. Because exopolysaccharides (EPS) play a determinant role in bacterial adhesion by conferring protection against adverse conditions such as starvation and environmental aggressions, EPS production would be expected to be higher if the bacterium is exposed to water. In this work the capability of H. pylori to produce EPS when exposed to water and under hydrodynamic stress has been evaluated. H. pylori was inoculated in autoclaved distilled water and allowed to stand under gentle stirring at room temperature. The significant and continuous increase in the sugar content 192 hours after inoculation suggests the production of exopolysaccharides. This evidence is reinforced by epiflourescence microscopical observation of the bacteria stained with DAPI (4,6-diamidino-2-phenylindole) that revealed the presence of bacterial aggregates 318 hours after inoculation

Steam reforming of biomass gasification gas for hydrogen production: From thermodynamic analysis to experimental validation

ABSTRACT: Biomass gasification produces syngas composed mainly of hydrogen, carbon monoxide, carbon dioxide, methane, water, and higher hydrocarbons, till C4, mainly ethane. The hydrocarbon content can be upgraded into richer hydrogen streams through the steam reforming reaction. This study assessed the steam reforming process at the thermodynamic equilibrium of five streams, with different compositions, from the gasification of three different biomass sources (Lignin, Miscanthus, and Eucalyptus). The simulations were performed on Aspen Plus V12 software using the Gibbs energy minimization method. The influence of the operating conditions on the hydrogen yield was assessed: temperature in the range of 200 to 1100 degrees C, pressures of 1 to 20 bar, and steam-to-carbon (S/C) molar ratios from 0 (only dry reforming) to 10. It was observed that operating conditions of 725 to 850 degrees C, 1 bar, and an S/C ratio of 3 enhanced the streams' hydrogen content and led to nearly complete hydrocarbon conversion (>99%). Regarding hydrogen purity, the stream obtained from the gasification of Lignin and followed by a conditioning phase (stream 5) has the highest hydrogen purity, 52.7%, and an hydrogen yield of 48.7%. In contrast, the stream obtained from the gasification of Lignin without any conditioning (stream 1) led to the greatest increase in hydrogen purity, from 19% to 51.2% and a hydrogen yield of 61.8%. Concerning coke formation, it can be mitigated for S/C molar ratios and temperatures >2 and 700 degrees C, respectively. Experimental tests with stream 1 were carried out, which show a similar trend to the simulation results, particularly at high temperatures (700-800 degrees C).info:eu-repo/semantics/publishedVersio

Cryogenic pressure temperature swing adsorption process for natural gas upgrade

The energy and chemical sectors are suffering remarkable changes. In this way, producing abundant quantity of energy with high quality, economic and environmental viability and sustainability is the main concern of the present times. One of such vital components of the world’s energy supply that fulfills the abovementioned requirements is natural gas [1]. Natural gas consists of 85–95% methane, but it also contains considerable amounts of heavier hydrocarbons as well as other compounds (CO2, N2, Hg, He, H2S) [1]. In order to meet the pipeline quality standard specifications or Liquefied Natural Gas (LNG) production, impurities must be removed. Carbon dioxide is one of the major contaminants in natural gas, reducing its energy content and becoming acidic and corrosive in the presence of water, damaging pipelines and equipment. In LNG processing plants CO2 can solidify, blocking the pipeline systems and causing transportation drawbacks [1]. In order to meet the pipeline quality standard specifications an upper limit for nitrogen and carbon dioxide of 4 and 2% is necessary, respectively. While, to inhibit the formation of dry ice in the liquefaction step, CO2 content must be reduced to 50 ppm level [2, 3]. Among the several separation technologies available for natural gas upgrade, such as chemical absorption, physical absorption, cryogenic distillation and membrane processes, adsorption processes are considered a competitive solution. Removal of carbon dioxide from natural gas for LNG production, can be carried out by cryogenic distillation using a multicolumn sequence to obtain a product stream with less than 50 ppm of CO2 [4]. Cryogenic adsorption-based processes, particularly pressure thermal swing adsorption, arise as a reliable and innovative alternative to replace the distillation columns, in particular the last one. Please click Additional Files below to see the full abstract

Experimental characterization of the out-of-plane performance of regular stone masonry walls, including test setups and axial load influence

Stone masonry is one of the oldest and most worldwide used building techniques. Nevertheless, the structural response of masonry structures is complex and the effective knowledge about their mechanical behaviour is still limited. This fact is particularly notorious when dealing with the description of their out-of-plane behaviour under horizontal loadings, as is the case of the earthquake action. In this context, this paper describes an experimental program, conducted in laboratory environment, aiming at characterizing the out-of-plane behaviour of traditional unreinforced stone masonry walls. In the scope of this campaign, six full-scale sacco stone masonry specimens were fully characterised regarding their most important mechanic, geometric and dynamic features and were tested resorting to two different loading techniques under three distinct vertical pre-compression states; three of the specimens were subjected to an out-of-plane surface load by means of a system of airbags and the remaining were subjected to an out-of-plane horizontal line-load at the top. From the experiments it was possible to observe that both test setups were able to globally mobilize the out-of-plane response of the walls, which presented substantial displacement capacity, with ratios of ultimate displacement to the wall thickness ranging between 26 and 45 %, as well as good energy dissipation capacity. Finally, very interesting results were also obtained from a simple analytical model used herein to compute a set of experimental-based ratios, namely between the maximum stability displacement and the wall thickness for which a mean value of about 60 % was found