Influence of the deposition pressure on the properties of transparent and conductive ZnO: Ga thin-film produced by r.f. sputtering at room temperature

Thin Solid Films, vol. 427, nº 1-2

Experimental assessment of pressure drop in air stripping columns

One important step in the design of air stripping operations for the removal of VOC is the choice of operating conditions, which are based in the phase ratio. This parameter sets on directly the stripping factor and the efficiency of the operation. Its value has an upper limit determined by the flooding regime, which is previewed using empirical correlations, namely the one developed by Eckert. This type of approach is not suitable for the development of algorithms. Using a pilot scale column and a convenient solution, the pressure drop was determined in different operating conditions and the experimental values were compared with the estimations. This particular research will be incorporated in a global model for simulating the dynamics of air stripping using a multi variable distributed parameter system.

Multiple Linear Regression and Artificial Neural Networks to Predict Time and Efficiency of Soil Vapor Extraction

The prediction of the time and the efficiency of the remediation of contaminated soils using soil vapor extraction remain a difficult challenge to the scientific community and consultants. This work reports the development of multiple linear regression and artificial neural network models to predict the remediation time and efficiency of soil vapor extractions performed in soils contaminated separately with benzene, toluene, ethylbenzene, xylene, trichloroethylene, and perchloroethylene. The results demonstrated that the artificial neural network approach presents better performances when compared with multiple linear regression models. The artificial neural network model allowed an accurate prediction of remediation time and efficiency based on only soil and pollutants characteristics, and consequently allowing a simple and quick previous evaluation of the process viability.

Liquid-vapor interfaces of patchy colloids

We investigate the liquid-vapor interface of a model of patchy colloids. This model consists of hard spheres decorated with short-ranged attractive sites ("patches") of different types on their surfaces. We focus on a one-component fluid with two patches of type A and nine patches of type B (2A9B colloids), which has been found to exhibit reentrant liquid-vapor coexistence curves and very low-density liquid phases. We have used the density-functional theory form of Wertheim's first-order perturbation theory of association, as implemented by Yu and Wu [J. Chem. Phys. 116, 7094 (2002)], to calculate the surface tension, and the density and degree of association profiles, at the liquid-vapor interface of our model. In reentrant systems, where AB bonds dominate, an unusual thickening of the interface is observed at low temperatures. Furthermore, the surface tension versus temperature curve reaches a maximum, in agreement with Bernardino and Telo da Gama's mesoscopic Landau-Safran theory [Phys. Rev. Lett. 109, 116103 (2012)]. If BB attractions are also present, competition between AB and BB bonds gradually restores the monotonic temperature dependence of the surface tension. Lastly, the interface is "hairy," i.e., it contains a region where the average chain length is close to that in the bulk liquid, but where the density is that of the vapor. Sufficiently strong BB attractions remove these features, and the system reverts to the behavior seen in atomic fluids.

Propagation of waves generated by a pressure disturbance moving in a channel

This paper studies the effect of ship speed and water depth on the propagation of ship generated waves. The ship is represented by a moving pressure distribution function at the free surface that is able to reproduce most of the phenomena involved in wave propagation. Results are obtained for a ship sailing along a coastal stretch made of a sloping bottom and a constant depth region. The results show that in the sloping bottom the crests of waves are bent along the slope and in the constant depth the standard Kelvin wave patterns can be found for the subcritical regime. In the critical regime the wave system is characterized by significant diverging waves and for a supercritical regime, the transverse waves disappear. © 2015 Taylor & Francis Group, London.

Development of a system to monitor surfer’s balance and plantar pressure and surfboard’s movement

O uso da tecnologia tem crescido nas últimas décadas nas mais diversas áreas, seja na indústria ou no dia-a-dia, e é cada vez mais evidente os benefícios que traz. No desporto não é diferente. Cada dia surgem novos desenvolvimentos objetivando a melhoria do desempenho dos praticantes de atividades físicas, possibilitando atingir resultados nunca antes pensados. Além disto, a utilização da tecnologia no desporto permite a obtenção de dados biomecânicos que podem ser utilizados tanto no treinamento quando na melhoria da qualidade de vida dos atletas auxiliando na prevenção de lesões, por exemplo. Deste modo, o presente projeto se aplica na área do desporto, nomeadamente, na modalidade do surfe, onde a ausência de trabalhos científicos ainda é elevada, aliando a tecnologia eletrônica ao desporto para quantificar informações até então desconhecidas. Três fatores básicos de desempenho foram levantados, sendo eles: equilíbrio, posicionamento dos pés e movimentação da prancha de surfe. Estes fatores levaram ao desenvolvimento de um sistema capaz de medi-los dinamicamente através da medição das forças plantares e da rotação da prancha de surfe. Além da medição dos fatores, o sistema é capaz de armazenar os dados adquiridos localmente através de um cartão de memória, para posterior análise; e também enviá-los através de uma comunicação sem fio, permitindo a visualização do centro de pressões plantares; dos ângulos de rotação da prancha de surfe; e da ativação dos sensores; em tempo real. O dispositivo consiste em um sistema eletrônico embarcado composto por um microcontrolador ATMEGA1280; um circuito de aquisição e condicionamento de sinal analógico; uma central inercial; um módulo de comunicação sem fio RN131; e um conjunto de sensores de força Flexiforce. O firmware embarcado foi desenvolvido em linguagem C. O software Matlab foi utilizado para receção de dados e visualização em tempo real. Os testes realizados demostraram que o funcionamento do sistema atende aos requisitos propostos, fornecendo informação acerca do equilíbrio, através do centro de pressões; do posicionamento dos pés, através da distribuição das pressões plantares; e do movimento da prancha nos eixos pitch e roll, através da central inercial. O erro médio de medição de força verificado foi de -0.0012 ± 0.0064 N, enquanto a mínima distância alcançada na transmissão sem fios foi de 100 m. A potência medida do sistema foi de 330 mW.

Otimização Energética na Produção de Biodiesel

Enquadrado num contexto cada vez mais marcado pela necessidade imperiosa de adoção e desenvolvimento de práticas ambientais e energeticamente sustentáveis, este trabalho visa contribuir para a caracterização e otimização do consumo de energia na produção de biodiesel. O biodiesel pode ser encarado como uma boa resposta aos graves problemas que os combustíveis fósseis estão a provocar nas sociedades modernas, pois é uma fonte de energia biodegradável, não-tóxica e sintetizada a partir de várias matérias-primas. Porém, o elevado custo de produção, como consequência do elevado preço das matérias-primas, constitui o maior problema para a sua implementação e comercialização a grande escala. A produção de biodiesel é, em sua quase totalidade, conduzida por via de reação de transesterificação, usando óleo vegetal e álcool como matérias-primas. O objetivo geral deste trabalho é otimizar energeticamente um processo de produção de biodiesel, via catálise homogênea alcalina (BCHA). Para alcançar esse objetivo, um fluxograma típico de produção foi construído e analisado, tanto do ponto de vista energético como econômico. Posteriormente oportunidades de otimização do processo foram identificadas, no sentido de reduzir o consumo de utilidades, impacto ambiental e aumentar a rentabilidade econômica. A construção do processo, a caracterização da alimentação, os critérios de operacionalidade, a obtenção de resultados e demais fatores foram efetuados com auxílio de um software de simulação Aspen Plus versão 20.0 criado pela Aspen Technology products. Os resultados do trabalho revelaram que o processo BCHA produz uma corrente com 99,9 % em biodiesel, obedecendo às normas internacionais em vigor. Na parte energética, o processo BCHA base necessitou de 21.405,1 kW em utilidades quentes e 14.886,3 kW em utilidades frias. A integração energética do processo BCHA, segundo a metodologia pinch, permitiu uma redução das necessidades quentes para 10.752,3 kW (redução de 50 %) e frias para 4.233,5 kW (redução de 72 %). A temperatura no ponto de estrangulamento (PE) foi de 157,7 ºC nas correntes quentes e 147,7 ºC nas correntes frias. Em termos econômicos, o custo total é reduzido em 35% com a integração energética proposta. Essa diminuição, deve-se sobretudo à redução do custo operacional, onde as necessidades de vapor de muita alta pressão (VMAP), vapor de alta pressão (VAP) e água de resfriamento (AR) apresentaram quebras de 2 %, 92 % e 71 %, respectivamente. Como conclusão final, salienta-se que a integração do processo BCHA estudado é energética e economicamente viável.

Postaerobic Exercise Blood Pressure Reduction in Very Old Persons With Hypertension.

BACKGROUND AND PURPOSE: A single bout of aerobic exercise acutely decreases blood pressure, even in older adults with hypertension. Nonetheless, blood pressure responses to aerobic exercise in very old adults with hypertension have not yet been documented. Therefore, this study aimed to assess the effect of a single session of aerobic exercise on postexercise blood pressure in very old adults with hypertension. METHODS: Eighteen older adults with essential hypertension were randomized into exercise (N = 9, age: 83.4 ± 3.2 years old) or control (N = 9, age: 82.7 ± 2.5 years old) groups. The exercise group performed a session of aerobic exercise constituting 2 periods of 10 minutes of walking at an intensity of 40% to 60% of the heart rate reserve. The control group rested for the same period of time. Anthropometric variables and medication status were evaluated at baseline. Heart rate and systolic and diastolic blood pressures were measured at baseline, after exercise, and at 20 and 40 minutes postexercise. RESULTS: Systolic blood pressure showed a significant interaction for group × time (F3,24 = 6.698; P = .002; ηp = 0.153). In the exercise group, the systolic blood pressure at 20 (127.3 ± 20.9 mm Hg) and 40 minutes (123.7 ± 21.0 mm Hg) postexercise was significantly lower in comparison with baseline (135.6 ± 20.6 mm Hg). Diastolic blood pressure did not change. Heart rate was significantly higher after the exercise session. In the control group, no significant differences were observed. CONCLUSIONS: A single session of aerobic exercise acutely reduces blood pressure in very old adults with hypertension and may be considered an important nonpharmacological strategy to control hypertension in this age group.

Intraocular Pressure Correlates with Optic Nerve Sheath Diameter in Patients with Normal Tension Glaucoma

PURPOSE: 1. Identify differences in optic nerve sheath diameter (ONSD) as an indirect measure of intracranial pressure (ICP) in glaucoma patients and a healthy population. 2. Identify variables that may correlate with ONSD in primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG) patients. METHODS: Patients with NTG (n = 46) and POAG (n = 61), and healthy controls (n = 42) underwent B-scan ultrasound measurement of ONSD by an observer masked to the patient diagnosis. Intraocular pressure (IOP) was measured in all groups, with additional central corneal thickness (CCT) and visual field defect measurements in glaucomatous patients. Only one eye per patient was selected. Kruskal-Wallis or Mann-Whitney were used to compare the different variables between the diagnostic groups. Spearman correlations were used to explore relationships among these variables. RESULTS: ONSD was not significantly different between healthy, NTG and POAG patients (6.09 ± 0.78, 6.03 ± 0.69, and 5.71 ± 0.83 respectively; p = 0.08). Visual field damage and CCT were not correlated with ONSD in either of the glaucoma groups (POAG, p = 0.31 and 0.44; NTG, p = 0.48 and 0.90 respectively). However, ONSD did correlate with IOP in NTG patients (r = 0.53, p < 0.001), while it did not in POAG patients and healthy controls (p = 0.86, p = 0.46 respectively). Patient's age did not relate to ONSD in any of the groups (p > 0.25 in all groups). CONCLUSIONS: Indirect measurements of ICP by ultrasound assessment of the ONSD may provide further insights into the retrolaminar pressure component in glaucoma. The correlation of ONSD with IOP solely in NTG patients suggests that the translaminar pressure gradient may be of particular importance in this type of glaucoma.

Physical Activity, Obesity Status, and Blood Pressure in Preschool Children

Objective To examine the combined effects of physical activity and weight status on blood pressure (BP) in preschool-aged children. Study design The sample included 733 preschool-aged children (49% female). Physical activity was objectively assessed on 7 consecutive days by accelerometry. Children were categorized as sufficiently active if they met the recommendation of at least 60 minutes daily of moderate-to-vigorous physical activity (MVPA). Body mass index was used to categorize children as nonoverweight or overweight/obese, according to the International Obesity Task Force benchmarks. BP was measured using an automated BP monitor and categorized as elevated or normal using BP percentile-based cut-points for age, sex, and height. Results The prevalence of elevated systolic BP (SBP) and diastolic BP was 7.7% and 3.0%, respectively. The prevalence of overweight/obese was 32%, and about 15% of children did not accomplish the recommended 60 minutes of daily MVPA. After controlling for age and sex, overweight/obese children who did not meet the daily MVPA recommendation were 3 times more likely (OR 3.8; CI 1.6-8.6) to have elevated SBP than nonoverweight children who met the daily MVPA recommendation. Conclusions Overweight or obese preschool-aged children with insufficient levels of MVPA are at significantly greater risk for elevated SBP than their non overweight and sufficiently active counterparts. (J Pediatr 2015;167:98-102).

Hereditary Neuropathy with Liability to Pressure Palsy Presenting with Hand Drop in a Young Child

Hereditary neuropathy with liability to pressure palsy (HNPP) results from the deletion of the PMP22 gene in chromosome 17p11.2. Clinically, it presents with painless pressure palsies, typically in the 2nd and 3rd decades of life, being a rare entity in childhood. We present the case study of a six-year-old male child who presented with left hand drop that he kept for over four weeks. Electrophysiological studies suggested HNPP and genetic studies confirmed it. With this paper, we pretend to create awareness to this entity as a diagnosis to be considered in a child with painless monoparesis and to emphasize the importance of electrophysiological studies in the diagnosis.

Intraocular Pressure in Eyes Receiving Intravitreal Antivascular Endothelial Growth Factor Injections

PURPOSE: The aim of the this study was to determine the effect of intravitreal antivascular endothelial growth factor injections on intraocular pressure (IOP) and identify possible risk factors for the development of increased IOP. MATERIALS AND METHODS: This prospective study included a total of 106 eyes receiving intravitreal injection of bevacizumab as treatment for macular edema or active choroidal neovascularization. IOP was measured by Goldmann applanation tonometry immediately before the intravitreal injection and 5 min, 1 h and 15 days after the procedure. The records of the study patients were reviewed for age, gender, history of glaucoma, diabetes mellitus, phakic status, systemic and topical medication and number of previous injections. Subconjunctival reflux was registered. IOP elevation was defined as IOP ≥21 mm Hg and/or a change from baseline of ≥5 mm Hg recorded at least on two or more measurements on the same visit. RESULTS: Mean preoperative IOP was 15.31 ± 3.90 mm Hg and postoperative IOP values were 27.27 ± 11.87 mm Hg (after 5 min), 17.59 ± 6.24 mm Hg (after 1 h) and 16.86 ± 3.62 mm Hg (after 15 days). The IOP variation was statistically significant between pre- and postoperative measurements (p < 0.05). Subconjunctival reflux was recorded in 11.3%, and in this subgroup the IOP at 5 min and at 1 h was lower than preoperative IOP (p < 0.05). CONCLUSIONS: More than one third of the eyes achieved IOPs >30 mm Hg 5 min after injection. Subconjunctival reflux contributed to a lower mean postoperative IOP (p < 0.05). Considerations for the management include prophylactic IOP lowering with medical therapy and/or preinjection ocular decompression for patients with a history of glaucoma or ocular hypertension and switching to an as-needed injection protocol in patients suffering a marked IOP rise in previous injections. © 2015 S. Karger AG, Basel.

Projeto de conceção e desenvolvimento de um esterilizador a vapor de equipamento médico-hospitalar

Dissertação para obtenção do Grau de Mestre em Engenharia Mecânica

Do hospitals react to random demand pressure by early discharges?

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Economics from the NOVA – School of Business and Economics

Comparing exchange market pressure in West and Southern African countries

We compare the performance of Cape Verde and Mozambique concerning financial credibility as measured by Exchange Market Pressure, an institutional feature that has often been overlooked in the literature as a relevant institution for economies. Drawing on previous research by Macedo et al. (2009), we expand their analysis and, using several definitions of “financial credibility”, all related to different angles on Exchange Market Pressure indices, we conclude that - against reasonable benchmarks in their respective regions - financial credibility has been very good for Cape Verde and fairly good for Mozambique.