A simulation study on the abatement of CO2 emissions by de-absorption with monoethanolamine

Because of the adverse effect of CO2 from fossil fuel combustion on the earth's ecosystems, the most cost-effective method for CO2 capture is an important area of research. The predominant process for CO2 capture currently employed by industry is chemical absorption in amine solutions. A dynamic model for the de-absorption process was developed with monoethanolamine (MEA) solution. Henry's law was used for modelling the vapour phase equilibrium of the CO2, and fugacity ratios calculated by the Peng-Robinson equation of state (EOS) were used for H2O, MEA, N-2 and O-2. Chemical reactions between CO2 and MEA were included in the model along with the enhancement factor for chemical absorption. Liquid and vapour energy balances were developed to calculate the liquid and vapour temperature, respectively.

Colour filtering in a-SiC : H based p-i-n-p-i-n cells: A trade-off between bias polarity and absorption regions

A large area colour imager optically addressed is presented. The colour imager consists of a thin wide band gap p-i-n a-SiC:H filtering element deposited on the top of a thick large area a-SiC:H(-p)/a-Si:H(-i)/a-SiC:H(-n) image sensor, which reveals itself an intrinsic colour filter. In order to tune the external applied voltage for full colour discrimination the photocurrent generated by a modulated red light is measured under different optical and electrical bias. Results reveal that the integrated device behaves itself as an imager and a filter giving information not only on the position where the optical image is absorbed but also on it wavelength and intensity. The amplitude and sign of the image signals are electrically tuneable. In a wide range of incident fluxes and under reverse bias, the red and blue image signals are opposite in sign and the green signal is suppressed allowing blue and red colour recognition. The green information is obtained under forward bias, where the blue signal goes down to zero and the red and green remain constant. Combining the information obtained at this two applied voltages a RGB colour image picture can be acquired without the need of the usual colour filters or pixel architecture. A numerical simulation supports the colour filter analysis.

Effect of oxidative stress upon absorption of glucose by the human placenta: in vitro studies with BeWo cells

Pregnancy is a dynamic state and the placenta is a temporary organ that, among other important functions, plays a crucial role in the transport of nutrients and metabolites between the mother and the fetus, which is essential for a successful pregnancy. Among these nutrients, glucose is considered a primary source of energy and, therefore, fundamental to insure proper fetus development. Several studies have shown that glucose uptake is dependent on several morphological and biochemical placental conditions. Oxidative stress results from the unbalance between reactive oxygen species (ROS) and antioxidants, in favor of the first. During pregnancy, ROS, and therefore oxidative stress, increase, due to increased tissue oxygenation. Moreover, the relation between ROS and some pathological conditions during pregnancy has been well established. For these reasons, it becomes essential to understand if oxidative stress can compromise the uptake of glucose by the placenta. To make this study possible, a trophoblastic cell line, the BeWo cell line, was used. Experiments regarding glucose uptake, either under normal or oxidative stress conditions, were conducted using tert-butylhydroperoxide (tBOOH) as an oxidative stress inducer, and 3H-2-deoxy-D-glucose (3H-DG) as a glucose analogue. Afterwards, studies regarding the involvement of glucose facilitative transporters (GLUT) and the phosphatidylinositol 3-kinases (PI3K) and protein kinase C (PKC) pathways were conducted, also under normal and oxidative stress conditions. A few antioxidants, endogenous and from diet, were also tested in order to study their possible reversible effect of the oxidative effect of tBOOH upon apical 3H-DG uptake. Finally, transepithelial studies gave interesting insights regarding the apical-to-basolateral transport of 3H-DG. Results showed that 3H-DG uptake, in BeWo cells, is roughly 50% GLUT-mediated and that tBOOH (100 μM; 24h) decreases apical 3H-DG uptake in BeWo cells by about 33%, by reducing both GLUT- (by 28%) and non-GLUT-mediated (by 40%) 3H-DG uptake. Uptake of 3H-DG and the effect of tBOOH upon 3H-DG uptake are not dependent on PKC and PI3K. Moreover, the effect of tBOOH is not associated with a reduction in GLUT1 mRNA levels. Resveratrol, quercetin and epigallocatechin-3-gallate, at 50 μM, reversed, by at least 45%, the effect of tBOOH upon 3H-DG uptake. Transwell studies show that the apical-to-basolateral transepithelial transport of 3H-DG is increased by tBOOH.In conclusion, our results show that tBOOH caused a marked decrease in both GLUT and non-GLUT-mediated apical uptake of 3H-DG by BeWo cells. Given the association of increased oxidative stress levels with several important pregnancy pathologies, and the important role of glucose for fetal development, the results of this study appear very interesting.

Comparative study of amine solutions used in CO2 absorption/desorption cycles

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química

A New Method to Determine the Density and Water Absorption of Fine Recycled Aggregates

The construction industry keeps on demanding huge quantities of natural resources, mainly minerals for mortars and concrete production. The depletion of many quarries and environmental concerns about reducing the dumping of construction and demolition waste in quarries have led to an increase in the procuring and use of recycled aggregates from this type of waste. If they are to be incorporated in concrete and mortars it is essential to know their properties to guarantee the adequate performance of the end products, in both mechanical and durability-related terms. Existing regulated tests were developed for natural aggregates, however, and several problems arise when they are applied to recycled aggregates, especially fine recycled aggregates (FRA). This paper describes the main problems encountered with these tests and proposes an alternative method to determine the density and water absorption of FRA that removes them. The use of sodium hexametaphosphate solutions in the water absorption test has proven to improve its efficiency, minimizing cohesion between particles and helping to release entrained air.

Fractional order inductive phenomena based on the skin effect

The Maxwell equations play a fundamental role in the electromagnetic theory and lead to models useful in physics and engineering. This formalism involves integer-order differential calculus, but the electromagnetic diffusion points towards the adoption of a fractional calculus approach. This study addresses the skin effect and develops a new method for implementing fractional-order inductive elements. Two genetic algorithms are adopted, one for the system numerical evaluation and another for the parameter identification, both with good results.

Cobalt complexes with pyrazole ligands as catalyst precursors for the peroxidative oxidation of cyclohexane: Z-ray absorption spectroscopy studies and biological applications

[CoCl(-Cl)(Hpz(Ph))(3)](2) (1) and [CoCl2(Hpz(Ph))(4)] (2) were obtained by reaction of CoCl2 with HC(pz(Ph))(3) and Hpz(Ph), respectively (Hpz(Ph)=3-phenylpyrazole). The compounds were isolated as air-stable solids and fully characterized by IR and far-IR spectroscopy, MS(ESI+/-), elemental analysis, cyclic voltammetry (CV), controlled potential electrolysis, and single-crystal X-ray diffraction. Electrochemical studies showed that 1 and 2 undergo single-electron irreversible (CoCoIII)-Co-II oxidations and (CoCoI)-Co-II reductions at potentials measured by CV, which also allowed, in the case of dinuclear complex 1, the detection of electronic communication between the Co centers through the chloride bridging ligands. The electrochemical behavior of models of 1 and 2 were also investigated by density functional theory (DFT) methods, which indicated that the vertical oxidation of 1 and 2 (that before structural relaxation) affects mostly the chloride and pyrazolyl ligands, whereas adiabatic oxidation (that after the geometry relaxation) and reduction are mostly metal centered. Compounds 1 and 2 and, for comparative purposes, other related scorpionate and pyrazole cobalt complexes, exhibit catalytic activity for the peroxidative oxidation of cyclohexane to cyclohexanol and cyclohexanone under mild conditions (room temperature, aqueous H2O2). Insitu X-ray absorption spectroscopy studies indicated that the species derived from complexes 1 and 2 during the oxidation of cyclohexane (i.e., Ox-1 and Ox-2, respectively) are analogous and contain a Co-III site. Complex 2 showed low invitro cytotoxicity toward the HCT116 colorectal carcinoma and MCF7 breast adenocarcinoma cell lines.

Multiple skin neoplasms in subjects under 40 years of age in Goiania, Brazil

OBJECTIVE To describe the trend for malignant skin neoplasms in subjects under 40 years of age in a region with high ultraviolet radiation indices.METHODS A descriptive epidemiological study on melanoma and nonmelanoma skin cancers that was conducted in Goiania, Midwest Brazil, with 1,688 people under 40 years of age, between 1988 and 2009. Cases were obtained fromRegistro de Câncer de Base Populacional de Goiânia(Goiania’s Population-Based Cancer File). Frequency, trends, and incidence of cases with single and multiple lesions were analyzed; transplants and genetic skin diseases were found in cases with multiple lesions.RESULTS Over the period, 1,995 skin cancer cases were observed to found, of which 1,524 (90.3%) cases had single lesions and 164 (9.7%) had multiple lesions. Regarding single lesions, incidence on men was observed to have risen from 2.4 to 3.1/100,000 inhabitants; it differed significantly for women, shifting from 2.3 to 5.3/100,000 (Annual percentage change – [APC] 3.0%, p = 0.006). Regarding multiple lesions, incidence on men was observed to have risen from 0.30 to 0.98/100,000 inhabitants; for women, it rose from 0.43 to 1.16/100,000 (APC 8.6%, p = 0.003). Genetic skin diseases or transplants were found to have been correlated with 10.0% of cases with multiple lesions – an average of 5.1 lesions per patient. The average was 2.5 in cases without that correlation.CONCLUSIONS Skin cancer on women under 40 years of age has been observed to be increasing for both cases with single and multiple lesions. It is not unusual to find multiple tumors in young people – in most cases, they are not associated with genetic skin diseases or transplants. It is necessary to avoid excessive exposure to ultraviolet radiation from childhood.

Electrical skin phenomena: a fractional calculus analysis

The internal impedance of a wire is the function of the frequency. In a conductor, where the conductivity is sufficiently high, the displacement current density can be neglected. In this case, the conduction current density is given by the product of the electric field and the conductance. One of the aspects of the high-frequency effects is the skin effect (SE). The fundamental problem with SE is it attenuates the higher frequency components of a signal.

Schistosoma mansoni: importance of skin and pulmonary phases to concomitant immunity in albino mice

Fourteen-day-old schistosomula obtained from mice previously infected were surgically transferred to the portal vein of receptor mice. Another group of mice was infected with cercariae by transcutaneous route. After 90 days, those groups were challenged with 100 cercariae, transcutaneously, as well as a control group. Two weeks later the animals were perfused and mature and immature worms counted separately. Statistically significant differences were observed in the recovery of immature worms, when the control group was compared with those twice infected. No statistical difference was detected between the group infected transcutaneously, and that infected by worm inoculation in portal vein. Results demonstrated that suppression of skin and lung migration of the parasite does not interfere with the development of the so called concomitant immunity.

Numerical 3D modeling of heat transfer in human tissues for microwave radiometry monitoring of Brown fat metabolismo

Background: Brown adipose tissue (BAT) plays an important role in whole body metabolism and could potentially mediate weight gain and insulin sensitivity. Although some imaging techniques allow BAT detection, there are currently no viable methods for continuous acquisition of BAT energy expenditure. We present a non-invasive technique for long term monitoring of BAT metabolism using microwave radiometry. Methods: A multilayer 3D computational model was created in HFSS™ with 1.5 mm skin, 3-10 mm subcutaneous fat, 200 mm muscle and a BAT region (2-6 cm3) located between fat and muscle. Based on this model, a log-spiral antenna was designed and optimized to maximize reception of thermal emissions from the target (BAT). The power absorption patterns calculated in HFSS™ were combined with simulated thermal distributions computed in COMSOL® to predict radiometric signal measured from an ultra-low-noise microwave radiometer. The power received by the antenna was characterized as a function of different levels of BAT metabolism under cold and noradrenergic stimulation. Results: The optimized frequency band was 1.5-2.2 GHz, with averaged antenna efficiency of 19%. The simulated power received by the radiometric antenna increased 2-9 mdBm (noradrenergic stimulus) and 4-15 mdBm (cold stimulus) corresponding to increased 15-fold BAT metabolism. Conclusions: Results demonstrated the ability to detect thermal radiation from small volumes (2-6 cm3) of BAT located up to 12 mm deep and to monitor small changes (0.5°C) in BAT metabolism. As such, the developed miniature radiometric antenna sensor appears suitable for non-invasive long term monitoring of BAT metabolism.

Schistosoma mansoni: acquired immunity in mice after the use of oxamniquine at the evolutive skin and pulmonary phases

Mice infected with 350 cercariae of Schistosoma mansoni (LE strain) were treated with oxamniquine, at the dose of 400 mg/kg, 24, 48, 72, and 96 h after infection. Forty days after the treatment, the animals were submitted to a challenge infection with 80 cercariae, through the abdominal and ear skins. The number of immature worms in the animal groups treated 24 and 96 h after the first infection was found to be lower than that in the control group, thus showing that the death of schisto-somes by chemotherapy, at the skin and pulmonary phases, causes an acquired resistance state.

Multi-elemental analysis of ready-to-eat “baby leaf” vegetables using microwave digestion and high-resolution continuum source atomic absorption spectrometry

The mineral content (phosphorous (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu)) of eight ready-to-eat baby leaf vegetables was determined. The samples were subjected to microwave-assisted digestion and the minerals were quantified by High-Resolution Continuum Source Atomic Absorption Spectrometry (HR-CS-AAS) with flame and electrothermal atomisation. The methods were optimised and validated producing low LOQs, good repeatability and linearity, and recoveries, ranging from 91% to 110% for the minerals analysed. Phosphorous was determined by a standard colorimetric method. The accuracy of the method was checked by analysing a certified reference material; results were in agreement with the quantified value. The samples had a high content of potassium and calcium, but the principal mineral was iron. The mineral content was stable during storage and baby leaf vegetables could represent a good source of minerals in a balanced diet. A linear discriminant analysis was performed to compare the mineral profile obtained and showed, as expected, that the mineral content was similar between samples from the same family. The Linear Discriminant Analysis was able to discriminate different samples based on their mineral profile.

Effect of skin colour and selected physical characteristics on Schistosoma mansoni dependent morbidity

The effect of the colour group on the morbidity due to Schistosoma mansoni was examined in two endemic areas situated in the State of Minas Gerais, Brazil. Of the 2773 eligible inhabitants, 1971 (71.1%) participated in the study: 545 (27.6%) were classified as white, 719 (36.5%) as intermediate and 707 (35.9%) as black. For each colour group, signs and symptoms of individuals who eliminated S.mansoni eggs (cases) were compared to those who did not present eggs in the faeces (controls). The odds ratios were adjusted by age, gender, previous treatment for schistosomiasis, endemic area and quality of the household. There was no evidence of a modifier effect of colour on diarrhea, bloody faeces or abdominal pain. A modifier effect of colour on hepatomegaly was evident among those heaviest infected (> 400 epg): the adjusted odds ratios for palpable liver at the middle clavicular and the middle sternal lines were smaller among blacks (5.4 and 6.5, respectively) and higher among whites (10.6 and 12.9) and intermediates (10.4 and 10.1, respectively). These results point out the existence of some degree of protection against hepatomegaly among blacks heaviest infected in the studied areas.

Histoplasmin and paracoccidioidin skin reactivity in infantile population of Northern Argentina

In order to estimate ages at which etiological agents of systemic mycoses initiate infection, histoplasmin and paracoccidioidin skin tests were performed in 344 children of both sexes, between 2 and 15 years old. They were selected from a statistically significant population sample Gral. San Martín city (Northeast Argentina). Tests were read 48h after injection and considered positive if a 5 mm on larger induration was present. Circulating antibodies were also evaluated by agar gel immunodiffusion. The overall infection rate for H. capsulatum was 9.2%, belonging to children from 4 to 14 years old, without significant differences among sexes. Five children from 2 to 14 years old were positive to paracoccidioidin (1.6%). None of the children had specific antibodies neither signs of active mycosis. Results show H. capsulatum infection can be found from age 4, while for P. brasiliensis the lower limit was two years old. These findings may contribute to better knowledge on infantile fungal infection in a geographical region where no previous references can be found.