Characterization of pellets from industrial tomato residues

Large volumes of residual biomass (mainly peels and seeds) are generated by tomato industrial processing plants. After adequate drying and densification operations, those biomass wastes might be used for livestock food production, for lycopene extraction or even as fuel supply for thermal applications.The process described in the present paper is the manufacturing of 6 mm diameter pellets from tomato waste samples obtained from industrial processing plants. As a previous step, the samples were dehydrated to five different values of moisture content (20, 25, 29, 34 and 38 wt% w.b. approximately). Bulk and particle densities, hardness and durability of pellets were significantly influenced by the initial moisture content of the biomass raw materials, as well as by the subsequent reductions of such moisture content after pelletizing operations and storage periods. Increases of 21%, 41% and 67% in moisture content of the feeding biomass material – with respect to the lower value of the operating range, i.e. 20 wt% w.b. – were observed to yield the following percentage increments in a series of physical properties of pellets, respectively: 14%, 25% and 50% in bulk density; 6%, 16% and 18% in particle density; 225%, 1737% and 3575% in hardness; 8%, 44% and 88% in durability. Nevertheless, higher increments in moisture content of feeding material led to significantly lower values of the aforementioned properties – not to mention technical operating problems due to roller skidding in the pelletizing device.Pellets obtained from raw biomass (peels and seeds) with 34 wt% initial moisture content (9% final moisture content of pellets) were regarded as those with the most suitable configuration: durability 91.2%, hardness up to 88 N and energy density approaching 8 GJ/m³.     

An energy efficient middleware for an ad-hoc AAL wireless sensor network

DIA (Dispositivo Inteligente de Alarma, in Spanish) is an AAL (Ambient Assisted Living) system that allows to infer a potential dangerous action of an elderly person living alone at home. This inference is obtained by a specific sensorisation with sensor nodes (portables and fixes) and a reasoning layer embedded in a PC that learns of the users behaviour patterns and advices when actual one differs significantly of the normal patterns. In AAL systems, energy is a limited resource therefore sensor devices need to be properly managed to conserve energy. In this paper, we introduce the design and implementation of innovative and specific mechanisms at the sensory layer middleware which is capable of, first to discriminate spurious motion detections assuming that these signals do not resemble the patterns of real motion detections and, second to reduce the dynamics of messages by a sensor signal processing in order to compress the whole information in one single event. The middleware achieves power saving by modifying the raw information from sensors and adapting it to the predefined semantic of the reasoning layer. It manages the important task of data processing from sensors (raw information), and transfers the pre-processed information into the top layer of reasoning in a more energy efficient way. We also address the trade-off between reducing power consumption and reducing delay for incoming data. We present results from experiments using our implementation of these mechanisms at the middleware that comprises from node firmware to the PC driver. The number of messages of the proposed method with respect to the raw data is reduced by approximately 98.5%. The resources used in the PIR signal processing is reduced by approximately 85%. The resulting delay introduced is small (10–19 s) but system dynamics is slow enough to avoid contextualisation errors or reduction of system performance. We consider these results as very satisfactory.     

Crude oil aggregation by microscopy and dynamic light scattering

This research is focused on establishing a methodology to evaluate the aggregation state of Mexican crude oil solutions from two different sources and SARA compositions, by using Dynamic Light Scattering (DLS). Different crude oil concentrations were established and monitored through time in order to determine their effects on the aggregation state. DLS results indicate that the aggregation state of the studied solutions is influenced by crude oil composition, specifically by the amount of resins. Particle size and elemental analysis of the aggregates were performed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX), respectively. Results from these techniques reveal particulated low-porosity smooth surfaces due to the presence of resin, as well as the determination of the characteristic elements found in asphaltenes. High-Resolution Transmission Electron Microscopy (HTEM) indicated the presence of asphaltene aggregates constituted by nanometric particles and asphaltene stacking as well as ultrafine nanocrystalline-oriented structures.     

Impact of N on the atomic-scale Sb distribution in quaternary GaAsSbN-capped InAs quantum dots

The use of GaAsSbN capping layers on InAs/GaAs quantum dots (QDs) has recently been proposed for micro- and optoelectronic applications for their ability to independently tailor electron and hole confinement potentials. However, there is a lack of knowledge about the structural and compositional changes associated with the process of simultaneous Sb and N incorporation. In the present work, we have characterized using transmission electron microscopy techniques the effects of adding N in the GaAsSb/InAs/GaAs QD system. Firstly, strain maps of the regions away from the InAs QDs had revealed a huge reduction of the strain fields with the N incorporation but a higher inhomogeneity, which points to a composition modulation enhancement with the presence of Sb-rich and Sb-poor regions in the range of a few nanometers. On the other hand, the average strain in the QDs and surroundings is also similar in both cases. It could be explained by the accumulation of Sb above the QDs, compensating the tensile strain induced by the N incorporation together with an In-Ga intermixing inhibition. Indeed, compositional maps of column resolution from aberration-corrected Z-contrast images confirmed that the addition of N enhances the preferential deposition of Sb above the InAs QD, giving rise to an undulation of the growth front. As an outcome, the strong redshift in the photoluminescence spectrum of the GaAsSbN sample cannot be attributed only to the N-related reduction of the conduction band offset but also to an enhancement of the effect of Sb on the QD band structure.     

Influence of different carbon nanostructures on the electrocatalytic activity and stability of Pt supported electrocatalysts

Commercially available graphitized carbon nanofibers and multi-walled carbon nanotubes, two carbon materials with very different structure, have been functionalized in a nitric–sulfuric acid mixture. Further on, the materials have been platinized by a microwave assisted polyol method. The relative degree of graphitization has been estimated by means of Raman spectroscopy and X-ray diffraction while the relative concentration of oxygen containing groups has been estimated by X-ray photoelectron spectroscopy, which resulted in a graphitic character trend: Pt/GNF > Pt/F-GNF ? Pt/MWCNT > Pt/F-MWCNT. Transmission electron microscopy showed that the Pt particle size is around 3 nm for all samples, which was similar to the crystallite size obtained by X-ray diffraction. The activity towards electrochemical reduction of oxygen has been quantified using the thin-film rotating disk electrode, which has shown that all the samples have a better activity than the commercially available electrocatalysts. The trend obtained for the graphitic character maintained for the electrochemical activity, while the reverse trend has been obtained for the accelerated ageing test. Long-term potential cycling has demonstrated that the functionalization improves the stability for multi-walled carbon nanotubes, at the cost of decreased activity.     

Hydroxyapatite growth on cotton fibers modified chemically

We have prepared carboxymethyl cellulose fibers (CMC) by chemically modifying cotton cellulose with monochloroacetic acid and calcium chloride solution. This modification favored the growth of hydroxyapatite (HAP) on the surface of the CMC fibers in contact with simulated body fluid solutions (SBF). After soaking in SBF for periods of 7, 14 and 21 days, formation of HAP was observed. Analysis by scanning electron microscopy and X-ray diffraction showed that crystallinity, crystallite size, and growth of HAP increased with the soaking time. The amount of HAP deposited on CMC fibers increased greatly after 21 days of immersion in the SBF, while the substrate surface was totally covered with hemispherical aggregates with the size of the order of 2 microns. Elemental analysis showed the presence of calcium and phosphate, with calcium/phosphate atomic ratio of 1.54. Fourier transform infrared spectroscopy bands confirmed the presence of HAP. The results suggest that cotton modified by calcium treatment has a nucleating ability and can accelerate the nucleation of HAP crystals.     

Correlating indoor and outdoor temperature and humidity in a sample of buildings in tropical climates

The incidence of several respiratory viral infections has been shown to be related to climate. Because humans spend most of their time indoors, measures of indoor climate, rather than outdoor climate, may be better predictors of disease incidence and transmission. Therefore, understanding the relationship between indoor and outdoor climate will help illuminate their influence on the seasonality of diseases caused by respiratory viruses. Indoor-outdoor relationships between temperature and humidity have been documented in temperate regions, but little information is available for tropical regions, where seasonal patterns of respiratory viral diseases differ. We have examined indoor-outdoor correlations of temperature, relative humidity (RH), and absolute humidity (AH) over a 1-year period in each of seven tropical cities. Across all cities, the average monthly indoor temperature was 25 ± 3°C (mean ± standard deviation) with a range of 20–30°C. The average monthly indoor RH was 66 ± 9% with a range of 50–78%, and the average monthly indoor AH was 15 ± 3 g/m³ with a range of 10–23 g/m³. Indoor AH and RH were linearly correlated with outdoor AH when the air conditioning (AC) was off, suggesting that outdoor AH may be a good proxy of indoor humidity in the absence of AC. All indoor measurements were more strongly correlated with outdoor measurements as distance from the equator increased. Such correlations were weaker during the wet season, especially when AC was in operation. These correlations will provide insight for assessing the seasonality of respiratory viral infections using outdoor climate data, which is more widely available than indoor data, even though transmission of these diseases mainly occurs indoors.     

Spring-in behavior of curved composites manufactured by Flexible Injection

This paper investigates the manufacturing distortion of curved composite parts manufactured by a new Liquid Composite Molding (LCM) process called Flexible Injection (FI). This technique uses a deformable tool to speed up the fabrication but may generate manufacturing defects when strongly curved shapes are processed. The goal of the study is to evaluate the impact of such heterogeneities on the dimensional stability of the product. Curved components were first manufactured with varying processing conditions to achieve a wide range of layup quality. The shape stability of the samples was then recorded as a function of temperature to measure the thermoelastic component of distortion and experimental results were compared with predictions made by two modeling techniques. Under certain conditions, manufacturing defects can significantly affect the distortion behavior. This suggests that a robust preforming procedure is of primary importance to produce curved parts by Flexible Injection with a high level of repeatability.