Selectivity enhancement in the catalytic heterogeneous hydrogenation of limonene in supercritical carbon dioxide by an ionic liquid

Ionic liquids as coated catalysts or additives tremendously alter the selectivity pattern of the heterogeneous solid catalyst in the selective hydrogenation of limonene. The conventional monometallic ruthenium over alumina catalyst combined with an ionic liquid enables the one-pot synthesis of the intermediate p-menthene through limonene hydrogenation in supercritical carbon dioxide. Among eight screened imidazolium ILs, [C₁₀mim]NTf₂ was employed as additive, or as the coating agent of ruthenium catalyst in the reaction under supercritical conditions.The coating of the heterogeneous catalyst allows the selective production of p-menthene and increases the conversion level of limonene (>99%) compared to the conversion of limonene in the reaction carried out in the presence of an ionic liquid as an additive. Results of the catalyst recycling indicate that there is no depletion of catalyst reactivity even after four successive cycles of operation under the studied reaction conditions. Further hydrogenation of p-menthene is strongly inhibited by employing an ionic liquid. The solubility of limonene or p-menthene in an ionic liquid governs the selective hydrogenation of limonene towards p-menthene.     

Path-following control of mobile robots in presence of uncertainties

This paper presents, in detail, the implementation of a new control strategy, Kalman-based active observer controller (AOB), for the path following of wheeled mobile robots (WMRs) subject to nonholonomic constraints. This control strategy presents some particularities as being used in discrete mode, and being robust against uncertainties and disturbances such as the ones due to the use of the input-output feedback-linearization method in discrete mode, while it was developed to be used in continuous mode. The performance of the proposed control algorithm is verified via computer simulation, and is compared with other control strategies, such as pole placement controller (PPC) and PPC with a Kalman filter observer (CKF).     

Tenderisation of the dog cockle (Glycymeris glycymeris) meat by polyphosphates

Clams are widely used in the preparation of several seafood dishes but there are still a few bivalve species which have not been extensively used. Among these species is dog cockle (Glycymeris glycymeris), which is a major by-catch of surf clam (Spisula solida) fishing. However, dog cockle has a low commercial value because its texture is too tough after cooking. This study was initiated to find the best way of tenderising the meat of this species to make it suitable for human consumption. Based on preliminary trials using different tenderising products, a mixture of sodium tripolyphosphate and sodium chloride (3% and 1.5% respectively) was considered the most effective. The optimization of the processing parameters (time and temperature) was done by response surface methodology. According to the sensory analysis, objective texture evaluation and phosphate determinations the optimum conditions for the tenderisation process were an immersion time of 3 h at a temperature of 20  °C. The tenderised meat was used in the preparation of two types of canned products (light brine and a pickling sauce known as "escabeche"), which were evaluated by a taste panel and judged satisfactory.     

Awareness of language in children who have reading difficulties: historical comparisons in a longitudinal study

The purpose of this study was to assess factors associated with the use of family planning at first sexual intercourse among young adults aged 15 to 24 in urban Ecuador. The study population consisted of 1443 young adults (494 females and 949 males) in the cities of Quito and Guayaquil, interviewed by the 1988 Ecuador Young Adult Reproductive Health Survey, who reported having experienced consensual sexual intercourse. Approximately 11% of females and 15% of males reported using contraception at first intercourse. Binary logistic regression was performed to assess jointly the effect of multiple factors on contraceptive use at first intercourse. The regression model was first run on the entire study population and then separately for males and females. In the overall population, the following variables were significantly related to using family planning at first sex: being male; being from Guayaquil; older age; father's completion of secondary school. Having lost one's virginity to a prostitute was significantly associated with non-use of family planning. Males were 3.6 times more likely than females to use family planning during their first sexual intercourse. For each year older a young adult was at first sex, his or her odds of using family planning was multiplied by a factor of 1.3. Twenty-eight per cent of males in this study experienced their first sexual intercourse with a prostitute, and these young men were highly unlikely to use family planning. A male who experienced first intercourse with his girlfriend was more than five times as likely to use contraception than a male who lost his virginity to a prostitute.     

Theory on long time delays, Q-switching and related phenomena in GaAs junction lasers

We present a theory that explains long time delays. Q-switching and related phenomena in GaAs junction lasers, based only on processes known to occur in these lasers.     

Volatile organic compounds in rural atmospheres of central Portugal

Atmospheric concentrations of volatile organic compounds were measured at two rural sites in central Portugal. The sites were chosen to be in line with the summer northwesterly sea breezes in order to study the evolution of the chemical composition of air masses during transport to inland areas. The most abundant non-oxygenated hydrocarbon in the ambient air was isoprene and the monoterpenes alpha-pinene, beta-pinene and 1,8 cineol. The maximum isoprene levels (6-7 ppb) were recorded at the most inland site, suggesting an enrichment of coastal air masses with biogenic emissions during transport over eucalyptus forests. Formaldehyde was the most prominent carbonyl compound in the atmosphere but acetaldehyde and acrolein were also abundant. Concentrations of carbonyl compounds had a tendency to be higher inland, particularly for glyoxal, methyl glyoxal, methyl vinyl ketone, metacrolein and pentanal. The observed increases indicate that carbonyls were produced by photochemical oxidation of biogenic hydrocarbons in aged air masses with coastal origin. Isoprene, monoterpenes and various carbonyls exhibited pronounced diurnal variations, which are explained on the basis of emissions from vegetation, oxidation pathways of biogenic hydrocarbons and meteorological conditions.     

Towards useful and usable interaction design tools: CanonSketch

Despite all the effort dedicated to bringing better User-Centered Design (UCD) tools to market, current studies show that the industry is still dominated by tools that do not support the activities and workstyles of designers. Also, there is a growing need for interaction design tools aimed at software engineers, a problem related to bringing usability into the software engineering processes.

We propose a new workstyle model that can be effectively used to envision, design and evaluate a new generation of innovative interaction and software design tools, aimed at integrating usability and software engineering.

We illustrate the effectiveness of our model by describing a new tool, called CanonSketch, that was built in order to support UCD in terms of the dimensions in our workstyle model. We also describe an evaluation study aimed at contrasting paper prototyping with our tool as well as the level of workstyle support.     

Assisted navigation for a brain-actuated intelligent wheelchair

This paper presents an Assistive Navigation System (ANS) for a Robotic Wheelchair (RW) relying on a Brain–Computer Interface (BCI), as the Human–Machine Interface (HMI). A two-layer collaborative control approach is proposed to steer the RW, taking into account both user and machine commands. The first layer, a virtual-constraint layer, is responsible for enabling/disabling the user commands, based on context. More specifically, user commands are enabled for a set of situations requiring user decision, namely, bifurcations, multiple-directions caused by new obstacles in the environment, and deadlocks. The second layer is a user-intent matching responsible for determining the suitable steering command that better fits the user selection, taking into account the user competence to steer the wheelchair, and situation awareness of potential directions at a given location. A P300-based BCI allows the selection of commands to steer the RW. Experimental results using RobChair (Pires and Nunes (2002) [7], Lopes et al. (2007) [42]) are presented, showing the effectiveness of the proposed methodologies. The ANS was validated with ten able-bodied participants, and one participant with cerebral palsy, in two different scenarios: a structured known environment, and a structured unknown environment with moving objects. The overall result was that all participants were able to successfully operate the device, showing a high level of robustness of both, the BCI system, and the navigation system.