The effect of carbon nanofillers on the performance of electromechanical polyaniline-based composite actuators.

Different types of crystalline carbon nanomaterials were used to reinforce polyaniline for use in electromechanical bilayer bending actuators. The objective is to analyze how the different graphitic structures of the nanocarbons affect and improve the in situ polymerized polyaniline composites and their subsequent actuator behavior. The nanocarbons investigated were multiwalled carbon nanotubes, nitrogen-doped carbon nanotubes, helical-ribbon carbon nanofibers and graphene oxide, each one presenting different shape and structural characteristics. Films of nanocarbon-PAni composite were tested in a liquid electrolyte cell system. Experimental design was used to select the type of nanocarbon filler and composite loadings, and yielded a good balance of electromechanical properties. Raman spectroscopy suggests good interaction between PAni and the nanocarbon fillers. Electron microscopy showed that graphene oxide dispersed the best, followed by multiwall carbon nanotubes, while nitrogen-doped nanotube composites showed dispersion problems and thus poor performance. Multiwall carbon nanotube composite actuators showed the best performance based on the combination of bending angle, bending velocity and maximum working cycles, while graphene oxide attained similarly good performance due to its best dispersion. This parallel testing of a broad set of nanocarbon fillers on PAni-composite actuators is unprecedented to the best of our knowledge and shows that the type and properties of the carbon nanomaterial are critical to the performance of electromechanical devices with other conditions remaining equal.

Energy potential and alternative usages of biogas and sludge from UASB reactors: case study of the Laboreaux wastewater treatment plant.

This work assessed the energy potential and alternative usages of biogas and sludge generated in upflow anaerobic sludge blanket reactors at the Laboreaux sewage treatment plant (STP), Brazil. Two scenarios were considered: (i) priority use of biogas for the thermal drying of dehydrated sludge and the use of the excess biogas for electricity generation in an ICE (internal combustion engine); and (ii) priority use of biogas for electricity generation and the use of the heat of the engine exhaust gases for the thermal drying of the sludge. Scenario 1 showed that the electricity generated is able to supply 22.2% of the STP power demand, but the thermal drying process enables a greater reduction or even elimination of the final volume of sludge to be disposed. In Scenario 2, the electricity generated is able to supply 57.6% of the STP power demand; however, the heat in the exhaust gases is not enough to dry the total amount of dehydrated sludge.

Effect of marine ambient in the production of pollutants from the pyrolysis and combustion of a mixture of plastic materials.

A mixture of polyethylene (PE), polyethylene-terephtalate (PET), polypropylene (PP) and Nylon was submerged in marine water during 12 moths. The chlorine content of these plastics was measured through the passing time. Thermobalance was used to look for differences in the thermal decomposition of the plastics during in that time interval. Degradation of PET, PP and Nylon produced changes in the weight loss curve, but behaviour of PE is confusing. Pyrolysis and combustion at 850 °C was finally performed to get knowledge of the possible differences in the emission of main gases, volatiles and semivolatiles including polycyclic aromatic hydrocarbons (PAHs), polychlorinated benzenes (ClBzs), polychlorinated phenols (ClPhs), polybrominated phenols (BrPhs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Results show that the emission of chlorinated species is somewhat not affected by the chlorine content of the plastics mix. The production of PCBs and PCDD/Fs was very low, under 4 pg WHO-TEQ/g.

Volatile and semivolatile emissions from the pyrolysis of almond shell loaded with heavy metals.

Heavy metal-loaded almond shell was subjected to pyrolysis to understand the effect of the presence of different heavy metals on its thermal degradation. Pyrolysis behavior of native and metal-loaded samples was studied by thermogravimetric analysis. Similar shapes of thermogravimetric curves indicate that the presence of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni) and lead (Pb) did not change the main degradation pathways of almond shell. However, the temperature at which the decomposition in each stage takes place at a higher rate and char yield was considerably modified by the presence of Cr and Ni. Then, pyrolysis tests of the almond shell samples were performed in a moving tubular reactor at 700°C. Gases and volatile organic compounds were collected using Tedlar bags and semivolatile organic compounds were collected using a resin as adsorbent. Significant changes were obtained in the composition of the gaseous fraction as a result of the metal impregnation. The main changes in the composition of the gas were observed for Ni-loaded sample, which presented the highest H2 and CO yields. Also, the yields of most of the light hydrocarbons decrease in the presence of metal, while the rest remain quite similar. The total PAH yields reached 103µg/g for nickel-loaded sample (NiAS), 164µg/g for copper-loaded sample (CuAS), 172µg/g for lead-loaded sample (PbAS), 245µg/g for native sample (AS), 248µg/g for cadmium-loaded sample (CdAS) and 283µg/g for chromium-loaded sample (CrAS). Nickel is the most effective in the higher aromatic tar reduction, followed by Cu and Pb, whereas the presence of Cd does not affect the total emissions of PAHs. Finally, the carcinogenic potency of the samples was calculated. Native sample and the sample loaded with Cr presented slightly higher values associated to the presence of small amounts of benzo(a)pyrene.

Pollutant content in marine debris and characterization by thermal decomposition.

Marine debris (MDs) produces a wide variety of negative environmental, economic, safety, health and cultural impacts. Most marine litter has a very low decomposition rate (plastics), leading to a gradual accumulation in the coastal and marine environment. Characterization of the MDs has been done in terms of their pollutant content: PAHs, ClBzs, ClPhs, BrPhs, PCDD/Fs and PCBs. The results show that MDs is not a very contaminated waste. Also, thermal decomposition of MDs materials has been studied in a thermobalance at different atmospheres and heating rates. Below 400-500K, the atmosphere does not affect the thermal degradation of the mentioned waste. However, at temperatures between 500 and 800K the presence of oxygen accelerates the decomposition. Also, a kinetic model is proposed for the combustion of the MDs, and the decomposition is compared with that of their main constituents, i.e., polyethylene (PE), polystyrene (PS), polypropylene (PP), nylon and polyethylene-terephthalate (PET).

Thermogravimetric kinetic analysis and pollutant evolution during the pyrolysis and combustion of mobile phone case.

The increase in electronic waste, including cellular telephones, worldwide is a worrying reality. For this reason, urgent action on the management of these wastes is necessary within a framework that respects the environment and human health. Mobile phone components can be physically segregated through grinding at the dismantling sites, in order to reuse or reprocess (via chemical or physical recycling) the recovered plastics and valuable metals. A kinetic study of the thermal decomposition of a mobile phone case has been carried out under different conditions by thermogravimetry. Several experiments were performed in a nitrogen atmosphere (pyrolysis runs) and also in an oxidative atmosphere with two different oxygen concentrations (10% and 20% oxygen in nitrogen). Dynamic runs and dynamic+isothermal runs have been carried out to obtain much decomposition data under different operating conditions. Moreover some TG-MS runs were performed in order to better understand the thermal decomposition of a mobile phone case and identify some compounds emitted during the controlled heating of this material. A scheme of two independent reactions for pseudocomponents has been proposed for the pyrolysis process. For the combustion runs, the scheme proposed includes two pyrolytic reactions competing with other two reactions with formation of an intermediate residue, and finally the reaction of oxidation/burning of the intermediate residue. Furthermore, pyrolysis and combustion runs at 500 °C in a horizontal laboratory furnace were carried out. More than 50 compounds, including carbon oxides, light hydrocarbons, and polycyclic aromatic hydrocarbons (PAHs) have been identified and quantified. The main semivolatile compounds detected were phenol and styrene. Furthermore, polychlorodibenzo-p-dioxin and polychlorodibenzofurans (PCDD/Fs) and dioxin-like PCBs produced were analyzed. In the combustion run, PCDDs were obtained in higher amounts than PCDFs and HxCDD was the most emitted homologue.

De novo synthesis of PCDD/F by thermogravimetry.

On the basis of laboratory experiments with model mixtures, the steps in the de novo synthesis of halogenated compounds were studied. The study was performed using a thermobalance to evaluate the temperature of the maximum rate and the kinetics of the decomposition of the materials in the presence of air. The effect of the presence of CuCl2 and CuO with an atmosphere of HCl was studied. Analysis of the volatiles and solids after combustion in a horizontal furnace confirms the presence of organochloride compounds (including PCDD/F) at various temperatures. With the procedure that we followed, combustion is separated from pyrolysis, and it is possible to analyze the essential factors involved in the combustion process.

Idiopathic infantile arterial calcification: unusual features.

Idiopathic infantile arterial calcification (IIAC) is a rare disease of unknown etiology, which causes widespread arterial calcification and usually leads to early death from coronary arterial occlusion. Periarticular calcification has been reported in some cases. Two new cases are reported. In addition to the usual features of the disease, one was found to have ear-lobe calcification and the other an aortic aneurysm and coarctation of the aorta. Therapy with diphosphonate was apparently successful in one patient.

Pulmonary sequestration associated with unilateral pulmonary hypoplasia and massive pleural effusion. A case report and review of the literature.

Pulmonary sequestration associated with pulmonary hypoplasia and pleural effusion is very uncommon. Only three cases have been previously reported in the literature. We add one more case and describe its interesting clinical, radiological and pathological findings.

[Jeune syndrome and fungal bronchial asthma]. / Síndrome de Jeune y asma bronquial fúngico.

A young girl suffering from asphyxiating thoracic dystrophy secondary to bronchial asthma was submitted to an allergologic evaluation. We have not found these processes associated in what some authors have called the "minor forms" of the Jeune syndrome. Osteochondrodysplasia, called in recent papers thoracic-pelvic-phalangeal dysplasia, is characterised by marked retraction of the thoracic cage associated with changes in the bones of the pelvis and extremities. We placed special emphasis on the classification of the different forms of presentation as being of greater or lesser severity from a clinical point of view, and stressed the importance of associated abnormalities (such as renal complications, as in the case of our patient) with respect to the eventual prognosis. The diagnosis of allergy is based on a detailed clinical history, positive results to cutaneous testing and the presence of specific IgE, together with the results of nasal provocation. The recording by rhinomanometre, of the temperature and pressure, and the assessment of the nasal mucosa following contact with the suspected allergen was also of help. Finally, having established the diagnosis, we advised the corresponding treatment, both from the allergic and renal viewpoints and concluded with an evaluation of the prognosis as conditioned by the renal pathology.

CT of congenital malformations of the lung.

We reviewed 40 cases of congenital malformations of the lung that were studied with both plain radiography and computed tomography (CT). We compared the CT findings with those of radiography. We found that CT was helpful in the management of these cases because it helped confirm the diagnosis, demonstrated unsuspected findings, and better depicted anatomic extent of anomalies, thus allowing better planning for surgery. We believe that CT is the method of choice for the study of congenital lung malformations and that it should be used before more invasive procedures such as bronchography or aortography.

The Coffin-Siris syndrome. A report of four cases and review of the literature.

Four additional cases of the Coffin-Siris syndrome bring the number of reported cases to 16. This disorder is characterized by the absence or hypoplasia of the nails, especially those of the fifth fingers and toes, growth retardation and mental deficiency, microcephaly, coarse facial appearance, sparse scalp hair and lax joints. Feeding difficulties and respiratory problems are common in infancy. Absence or hypoplasia of the distal and middle phalanges, especially those of the fifth finger and toes and retarded bone maturation are the most common radiological features.