Basis set convergence in Hartree-Fock calculations of some diatomic molecules containing first and second-row atoms

Investiga-se a converg��ncia de conjuntos de bases em dire����o ao limite num��rico da energia Hartree-Fock (HF) total para as seq����ncias hier��rquicas dos conjuntos de bases XZP e ccpVXZ. Para as duas hierarquias, melhoramentos significativos s��o obtidos com cada incremento em X. Para estimar o limite do conjunto de base completo, uma forma exponencial foi usada. Entre as v��rias aproxima����es consideradas aqui, uma extrapola����o exponencial de tr��s par��metros aplicada aos resultados TZP, QZP e 5ZP deu os limites do conjunto de bases mais precisos. Em adi����o, energias HF dos orbitais moleculares ocupados mais altos de algumas mol��culas diat��micas foram calculadas com o conjunto 5ZP e comparadas com as correspondentes obtidas com o conjunto cc-pV5Z e com um m��todo num��rico HF.

"Second Life": quando o cinema abdica de ser o lugar que nos habita por dentro

O projecto ���Principais tend��ncias no cinema portugu��s contempor��neo��� nasceu no Departamento de Cinema da ESTC, com o objectivo de desenvolver investiga����o especializada a partir de um n��cleo formado por alunos da Licenciatura em Cinema e do Mestrado em Desenvolvimento de Projecto Cinematogr��fico, a que se juntaram professores-investigadores membros do CIAC e convidados. O que agora se divulga corresponde a dois anos e meio de trabalho desenvolvido pela equipa de investiga����o, entre Abril de 2009 e Novembro de 2011. Dada a forma que ele foi adquirindo, preferimos renome��-lo, para efeitos de divulga����o, ���Novas & velhas tend��ncias no cinema portugu��s contempor��neo���.

Solutions of second-order and fourth-order ODEs on the half-line

We start by studying the existence of positive solutions for the differential equation u '' = a(x)u - g(u), with u ''(0) = u(+infinity) = 0, where a is a positive function, and g is a power or a bounded function. In other words, we are concerned with even positive homoclinics of the differential equation. The main motivation is to check that some well-known results concerning the existence of homoclinics for the autonomous case (where a is constant) are also true for the non-autonomous equation. This also motivates us to study the analogous fourth-order boundary value problem {u((4)) - cu '' + a(x)u = vertical bar u vertical bar(p-1)u u'(0) = u'''(0) = 0, u(+infinity) = u'(+infinity) = 0 for which we also find nontrivial (and, in some instances, positive) solutions.

Modeling, control and simulation of full-power converter wind turbines equipped with permanent magnet synchronous generator

In this paper, two wind turbines equipped with a permanent magnet synchronous generator (PMSG) and respectively with a two-level or a multilevel converter are simulated in order to access the malfunction transient performance. Three different drive train mass models, respectively, one, two and three mass models, are considered in order to model the bending flexibility of the blades. Moreover, a fractional-order control strategy is studied comparatively to a classical integer-order control strategy. Computer simulations are carried out, and conclusions about the total harmonic distortion (THD) of the electric current injected into the electric grid are in favor of the fractional-order control strategy.

A Pitch Control Malfunction Analysis for Wind Turbines with Permanent Magnet Synchronous Generator and Full-power Converters: Proportional Integral Versus Fractional-order Controllers

A transient analysis for two full-power converter wind turbines equipped with a permanent magnet synchronous generator is studied in this article, taking into consideration, as a new contribution to earlier studies, a pitch control malfunction. The two full-power converters considered are, respectively, a two-level and a multi-level converter. Moreover, a novel control strategy based on fractional-order controllers for wind turbines is studied. Simulation results are presented; conclusions are in favor of the novel control strategy, improving the quality of the energy injected into the electric grid.

In permanent transit: discourses and maps of the intercultural experience

Instituto Polit��cnico do Porto. Instituto Superior de Contabilidade e Administra����o do Porto

Study on the use of MgAl hydrotalcites as solid heterogeneous catalysts for biodiesel production

This paper, reports experimental work on the use of new heterogeneous solid basic catalysts for biodiesel production: double oxides of Mg and Al, produced by calcination, at high temperature, of MgAl lamellar structures, the hydrotalcites (HT). The most suitable catalyst system studied are hydrotalcite Mg:Al 2:1 calcinated at 507 degrees C and 700 degrees C, leading to higher values of FAME also in the second reaction stage. One of the prepared catalysts resulted in 97.1% Fatty acids methyl esters (FAME) in the 1st reaction step, 92.2% FAME in the 2nd reaction step and 34% FAME in the 3rd reaction step. The biodiesel obtained in the transesterification reaction showed composition and quality parameters within the limits specified by the European Standard EN 14214. 2.5% wt catalyst/oil and a molar ratio methanol:oil of 9:1 or 12:1 at 60 -65 degrees C and 4 h of reaction time are the best operating conditions achieved in this study. This study showed the potential of Mg/Al hydrotalcites as heterogeneous catalysts for biodiesel production. (C) 2011 Elsevier Ltd. All rights reserved.

Working hours, work-life conflict and health in precarious and "permanent" employment

OBJECTIVE: The expansion of precarious employment in OECD countries has been widely associated with negative health and safety effects. Although many shiftworkers are precariously employed, shiftwork research has concentrated on full-time workers in continuing employment. This paper examines the impact of precarious employment on working hours, work-life conflict and health by comparing casual employees to full-time, "permanent" employees working in the same occupations and workplaces. METHODS: Thirty-nine convergent interviews were conducted in two five-star hotels. The participants included 26 full-time and 13 casual (temporary) employees. They ranged in age from 19 to 61 years and included 17 females and 22 males. Working hours ranged from zero to 73 hours per week. RESULTS: Marked differences emerged between the reports of casual and full-time employees about working hours, work-life conflict and health. Casuals were more likely to work highly irregular hours over which they had little control. Their daily and weekly working hours ranged from very long to very short according to organisational requirements. Long working hours, combined with low predictability and control, produced greater disruption to family and social lives and poorer work-life balance for casuals. Uncoordinated hours across multiple jobs exacerbated these problems in some cases. Health-related issues reported to arise from work-life conflict included sleep disturbance, fatigue and disrupted exercise and dietary regimes. CONCLUSIONS:This study identified significant disadvantages of casual employment. In the same hotels, and doing largely the same jobs, casual employees had less desirable and predictable work schedules, greater work-life conflict and more associated health complaints than "permanent" workers.

Brazilian doctors' perspective on the second opinion strategy before a C-section

OBJECTIVE: To describe the opinion of doctors who participated in the Latin American Study on Cesarean section in Brazil regarding the second opinion strategy when faced with the decision of performing a C-section. METHODS: Seventy-two doctors from the hospitals where the study took place (where the second opinion was routinely sought) and 70 from the control group answered a pre-tested self-administered structured questionnaire. Descriptive tables were prepared based on the frequency of relevant variables on opinion of physicians regarding: effectiveness of the application of the second opinion strategy; on whether they would recommend implementation of this strategy and reasons for not recommending it in private institutions; feasibility of the strategy implementation and reasons for not considering this implementation feasible in private institutions. RESULTS: Half of the doctors from the intervention hospitals (50%) and about two thirds of those in the control group (65%) evaluated the second opinion as being or having the potential of being effective/very effective in their institutions. The great majority of those interviewed from both intervention and control hospitals considered this strategy feasible in public (87% and 95% respectively) but not in private hospitals (64% and 70% respectively), mainly because in the latter the doctors would not accept interference from a colleague in their decision-making process. CONCLUSION: Although the second opinion strategy was perceived as effective in reducing C-section rates, doctors did not regard it feasible outside the public health system in Brazil.

A cellulose liquid crystal motor: a steam engine of the second kind

The salient feature of liquid crystal elastomers and networks is strong coupling between orientational order and mechanical strain. Orientational order can be changed by a wide variety of stimuli, including the presence of moisture. Changes in the orientation of constituents give rise to stresses and strains, which result in changes in sample shape. We have utilized this effect to build soft cellulose-based motor driven by humidity. The motor consists of a circular loop of cellulose film, which passes over two wheels. When humid air is present near one of the wheels on one side of the film, with drier air elsewhere, rotation of the wheels results. As the wheels rotate, the humid film dries. The motor runs so long as the difference in humidity is maintained. Our cellulose liquid crystal motor thus extracts mechanical work from a difference in humidity.

Synthesis of new Fe(II) and Ru(II) eta(5)-monocyclopentadienyl compounds showing significant second order NLO properties

A series of new ruthenium(II) complexes of the general formula [Ru(eta(5)-C5H5)(PP)(L)][PF6] (PP = DPPE or 2PPh(3), L = 4-butoxybenzonitrile or N-(3-cyanophenyl)formamide) and the binuclear iron(II) complex [Fe(eta(5)-C5H5)(PP)(mu-L)(PP)(eta(5)-C5H5)Fe][PF6](2) (L = (E)-2-(3-(4-nitrophenyl)allylidene)malononitrile, that has been also newly synthesized) have been prepared and studied to evaluate their potential in the second harmonic generation property. All the new compounds were fully characterized by NMR, IR and UV-Vis spectroscopies and their electrochemistry behaviour was studied by cyclic voltammetry. Quadratic hyperpolarizabilities (beta) of three of the complexes have been determined by hyper-Rayleigh scattering (HRS) measurements at fundamental wavelength of 1500 nm and the calculated static beta(0) values are found to fall in the range 65-212 x 10(-30) esu. Compound presenting beta(0) = 212 x 10(-30) esu has revealed to be 1.2 times more efficient than urea standard in the second harmonic generation (SHG) property, measured in the solid state by Kurtz powder technique, using a Nd:YAG laser (1064 nm). (C) 2013 Elsevier B.V. All rights reserved.

Influence of environmental temperature and humidity on the acute ventilatory response to exercise in asthmatic adolescents

Asthma is a chronic inflammatory disorder of the respiratory airways affecting people of all ages, and constitutes a serious public health problem worldwide (6). Such a chronic inflammation is invariably associated with injury and repair of the bronchial epithelium known as remodelling (11). Inflammation, remodelling, and altered neural control of the airways are responsible for both recurrent exacerbations of asthma and increasingly permanent airflow obstruction (11, 29, 34). Excessive airway narrowing is caused by altered smooth muscle behaviour, in close interaction with swelling of the airway walls, parenchyma retractile forces, and enhanced intraluminal secretions (29, 38). All these functional and structural changes are associated with the characteristic symptoms of asthma ��� cough, chest tightness, and wheezing ���and have a significant impact on patients��� daily lives, on their families and also on society (1, 24, 29). Recent epidemiological studies show an increase in the prevalence of asthma, mainly in industrial countries (12, 25, 37). The reasons for this increase may depend on host factors (e.g., genetic disposition) or on environmental factors like air pollution or contact with allergens (6, 22, 29). Physical exercise is probably the most common trigger for brief episodes of symptoms, and is assumed to induce airflow limitations in most asthmatic children and young adults (16, 24, 29, 33). Exercise-induced asthma (EIA) is defined as an intermittent narrowing of the airways, generally associated with respiratory symptoms (chest tightness, cough, wheezing and dyspnoea), occurring after 3 to 10 minutes of vigorous exercise with a maximal severity during 5 to 15 minutes after the end of the exercise (9, 14, 16, 24, 33). The definitive diagnosis of EIA is confirmed by the measurement of pre- and post-exercise expiratory flows documenting either a 15% fall in the forced expiratory volume in 1 second (FEV1), or a ���15 to 20% fall in peak expiratory flow (PEF) (9, 24, 29). Some types of physical exercise have been associated with the occurrence of bronchial symptoms and asthma (5, 15, 17). For instance, demanding activities such as basketball or soccer could cause more severe attacks than less vigorous ones such as baseball or jogging (33). The mechanisms of exercise-induced airflow limitations seem to be related to changes in the respiratory mucosa induced by hyperventilation (9, 29). The heat loss from the airways during exercise, and possibly its post-exercise rewarming may contribute to the exercise-induced bronchoconstriction (EIB) (27). Additionally, the concomitant dehydration from the respiratory mucosa during exercise leads to an increased interstitial osmolarity, which may also contribute to bronchoconstriction (4, 36). So, the risk of EIB in asthmatically predisposed subjects seems to be higher with greater ventilation rates and the cooler and drier the inspired air is (23). The incidence of EIA in physically demanding coldweather sports like competitive figure skating and ice hockey has been found to occur in up to 30 to 35% of the participants (32). In contrast, swimming is often recommended to asthmatic individuals, because it improves the functionality of respiratory muscles and, moreover, it seems to have a concomitant beneficial effect on the prevalence of asthma exacerbations (14, 26), supporting the idea that the risk of EIB would be smaller in warm and humid environments. This topic, however, remains controversial since the chlorified water of swimming pools has been suspected as a potential trigger factor for some asthmatic patients (7, 8, 20, 21). In fact, the higher asthma incidence observed in industrialised countries has recently been linked to the exposition to chloride (7, 8, 30). Although clinical and epidemiological data suggest an influence of humidity and temperature of the inspired air on the bronchial response of asthmatic subjects during exercise, some of those studies did not accurately control the intensity of the exercise (2, 13), raising speculation of whether the experienced exercise overload was comparable for all subjects. Additionally, most of the studies did not include a control group (2, 10, 19, 39), which may lead to doubts about whether asthma per se has conditioned the observed results. Moreover, since the main targeted age group of these studies has been adults (10, 19, 39), any extrapolation to childhood/adolescence might be questionable regarding the different lung maturation. Considering the higher incidence of asthma in youngsters (30) and the fact that only the works of Amirav and coworkers (2, 3) have focused on this age group, a scarcity of scientific data can be identified. Additionally, since the main environmental trigger factors, i.e., temperature and humidity, were tested separately (10, 28, 39) it would be useful to analyse these two variables simultaneously because of their synergic effect on water and heat loss by the airways (31, 33). It also appears important to estimate the airway responsiveness to exercise within moderate environmental ranges of temperature and humidity, trying to avoid extreme temperatures and humidity conditions used by others (2, 3). So, the aim of this study was to analyse the influence of moderate changes in air temperature and humidity simultaneously on the acute ventilatory response to exercise in asthmatic children. To overcome the above referred to methodological limitations, we used a 15 minute progressive exercise trial on a cycle ergometer at 3 different workload intensities, and we collected data related to heart rate, respiratory quotient, minute ventilation and oxygen uptake in order to ensure that physiological exercise repercussions were the same in both environments. The tests were done in a ���normal��� climatic environment (in a gymnasium) and in a hot and humid environment (swimming pool); for the latter, direct chloride exposition was avoided.

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

Trabalho Final de Mestrado para obten����o do grau de Mestre em Engenharia Qu��mica

Aproveitamento e valoriza����o de res��duos provenientes da produ����o de Biodiesel

Com o desenvolvimento econ��mico das ��ltimas d��cadas, a gest��o de recursos energ��ticos �� um desafio que a sociedade moderna enfrenta. Assim, actualmente h�� a necessidade da procura de novas fontes de energia, fontes de energia renov��veis. Sendo o biodiesel uma fonte de energia renov��vel, a sua crescente produ����o ir�� trazer um aumento da produ����o de res��duos, como o glicerol e ��cidos gordos. �� pois importante reduzir/valorizar estes res��duos de forma a impedir a sua acumula����o ao longo do tempo. A valoriza����o destes res��duos �� o objectivo principal deste trabalho. A primeira parte consistiu na esterifica����o de ��cidos gordos livres com glicerol, na presen��a de um catalisador ��cido, para a produ����o de monoglicer��deos. Foram utilizados diferentes tipos de mat��rias-primas: glicerol (76,3%) e res��duo de ��cidos gordos (20,8%), fornecidos pela empresa SOCIPOLE SA, glicerol puro (92,2%) e ��cido oleico puro (93,1%). Os catalisadores usados foram o cloreto de zinco comercial e o ��cido p-tolueonossulf��nico comercial. N��o foram efectuadas an��lises espec��ficas aos monoglicer��deos, o produto foi caracterizado pelo ��ndice de acidez. Aparentemente, a maior convers��o de ��cidos gordos foi obtida no ensaio de esterifica����o de ��cidos gordos com glicerol, ambos da SOCIPOLE SA. No entanto, este n��o serviu como termo de compara����o com os outros devido �� forma����o de uma fase s��lida (pol��mero). Relativamente aos outros ensaios, com raz��o molar glicerol/��cidos gordos de 1:3, o melhor resultado foi obtido na reac����o de glicerol da SOCIPOLE SA com ��cido oleico puro, na presen��a do catalisador ��cido p-toluenossulf��nico, �� temperatura de 106,3��C e tempo de reac����o de 4h30min, sendo a convers��o final de ��cido oleico 80,7%. Na segunda parte foi feito o estudo da esterifica����o de ��cidos gordos livres com metanol, na presen��a de ��cido sulf��rico, para a produ����o de biodiesel utilizando ��cidos gordos fornecidos pela empresa SOCIPOLE SA, ��cidos gordos derivados dos sab��es de um res��duo de glicerol fornecido pelo Laborat��rio de Tecnologia Qu��mica, Professora Doutora L��dia Vasconcelos do ISEP e ��cidos gordos derivados dos sab��es do glicerol bruto, fornecido pela empresa SOCIPOLE SA. Os ensaios foram efectuados a 65��C, com uma agita����o de 120rpm e uma raz��o molar ��cidos gordos/metanol de 1:3. Verificou-se que o ��ndice de acidez do produto, depois de lavado e seco, diminu��a com o tempo de reac����o e na generalidade a percentagem de ��steres aumentava, observando-se que a partir das seis horas, a reac����o se tornava muito lenta. O estudo da raz��o ��cidos gordos/metanol, n��o permitiu tirar conclus��es. O melhor resultado obtido correspondeu a um produto com 96,2% de ��steres met��licos e 8,54mgKOH/gamostra de ��ndice de acidez, pelo que n��o pode ainda ser designado de biodiesel.