Thermodynamic, Economic and Emissions Analysis of a Micro Gas Turbine Cogeneration System operating on Biofuels

Pós-graduação em Engenharia Mecânica - FEG

Robust isothermal electric control of exchange bias at room temperature

Voltage-controlled spin electronics is crucial for continued progress in information technology. It aims at reduced power consumption, increased integration density and enhanced functionality where non-volatile memory is combined with highspeed logical processing. Promising spintronic device concepts use the electric control of interface and surface magnetization. From the combination of magnetometry, spin-polarized photoemission spectroscopy, symmetry arguments and first-principles calculations, we show that the (0001) surface of magnetoelectric Cr2O3 has a roughness-insensitive, electrically switchable magnetization. Using a ferromagnetic Pd/Co multilayer deposited on the (0001) surface of a Cr2O3 single crystal, we achieve reversible, room-temperature isothermal switching of the exchange-bias field between positive and negative values by reversing the electric field while maintaining a permanent magnetic field. This effect reflects the switching of the bulk antiferromagnetic domain state and the interface magnetization coupled to it. The switchable exchange bias sets in exactly at the bulk Néel temperature.

AcMus: an Open, Integrated Platform for Room Acoustics Research

This article describes the design, implementation, and experiences with AcMus, an open and integrated software platform for room acoustics research, which comprises tools for measurement, analysis, and simulation of rooms for music listening and production. Through use of affordable hardware, such as laptops, consumer audio interfaces and microphones, the software allows evaluation of relevant acoustical parameters with stable and consistent results, thus providing valuable information in the diagnosis of acoustical problems, as well as the possibility of simulating modifications in the room through analytical models. The system is open-source and based on a flexible and extensible Java plug-in framework, allowing for cross-platform portability, accessibility and experimentation, thus fostering collaboration of users, developers and researchers in the field of room acoustics.

Investigation of a Pt3Sn/C Electro-Catalyst in a Direct Ethanol Fuel Cell Operating at Low Temperatures for Portable Applications

A 20% Pt3Sn/C catalyst was prepared by reduction with formic acid and used in a direct ethanol fuel cell at low temperatures. The electro-catalytic activity of this bimetallic catalyst was compared to that of a commercial 20% Pt/C catalyst. The PtSn catalyst showed better results in the investigated temperature range (30 degrees-70 degrees C). Generally, Sn promotes ethanol oxidation by adsorption of OH species at considerably lower potentials compared to Pt, allowing the occurrence of a bifunctional mechanism. The bimetallic catalyst was physico-chemically characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. The presence of SnO2 in the bulk and surface of the catalyst was observed. It appears that SnO2 can enhance the ethanol electro-oxidation activity at low potentials due to the supply of oxygen-containing species for the oxidative removal of CO and CH3CO species adsorbed on adjacent Pt active sites.

Job satisfaction among control room operators of electrical systems

Shift workers from control centers of electrical systems are a group that has received little attention in Brazil. This study aimed to compare workers' job satisfaction at five control centers of a Brazilian company electrical system, and according to their job titles. Method: The Organization Satisfaction Index (OSI) questionnaire to assess job satisfaction was used. ANOVA was used to compare OSI means, according to job title and control center. The results showed that there is no difference in job satisfaction among job titles, but a significant difference was found according to the control center. A single organizational culture cannot be applied to several branches. It is required to implement actions that would result in job satisfaction improvements among workers of all studied control rooms centers. The high level of education of operators working in all centers might have contributed to the similar values of perceived satisfaction among distinct job titles.

Continuous-wave watt-level Nd:YLF/KGW Raman laser operating at near-IR, yellow and lime-green wavelengths

A Nd:YLF/KGW Raman laser has been investigated in this work. We have demonstrated CW output powers at six different wavelengths, 1147 nm (0.70 W), 1163 nm (0.95 W), 549 nm (0.65 W), 552 nm (1.90 W), 573 nm (0.60 W) and 581 nm (1.10 W), with higher peak powers achieved under quasi-CW operation. Raman conversion of the 1053 nm fundamental emission is reported for the first time, enabling two new wavelengths in crystalline Raman lasers, 549 nm and 552 nm. The weak thermal lensing associated with Nd:YLF has enabled to achieve good beam quality, M-2 <= 2.0, and stable operation in relatively long cavities. (C) 2012 Optical Society of America

Performance of rest myocardial perfusion imaging in the management of acute chest pain in the emergency room in developing nations (PREMIER trial)

Background. Rest myocardial perfusion imaging (MPI) is effective in managing patients with acute chest pain in developed countries. We aimed to define the role and feasibility of rest MPI in low-to-middle income countries. Methods and Results. Low-to-intermediate risk patients (n = 356) presenting with chest pain to ten centers in eight developing countries were injected with a Tc-99m-based tracer, and standard imaging was performed. The primary outcome was a composite of death, non-fatal myocardial infarction (MI), recurrent angina, and coronary revascularization at 30 days. Sixty-nine patients had a positive MPI (19.4%), and 52 patients (14.6%) had a primary outcome event. An abnormal rest-MPI result was the only variable which independently predicted the primary outcome [adjusted odds ratio (OR) 8.19, 95% confidence interval 4.10-16.40, P = .0001]. The association of MPI result and the primary outcome was stronger (adjusted OR 17.35) when only the patients injected during pain were considered. Rest-MPI had a negative predictive value of 92.7% for the primary outcome, improving to 99.3% for the hard event composite of death or MI. Conclusions. Our study demonstrates that rest-MPI is a reliable test for ruling out MI when applied to patients in developing countries. (J Nucl Cardiol 2012;19:1146-53.)

Measurement of the concentration and size of aerosol particles and identification of the sources in orthopedic surgeries

In this study, the measurement of the concentration and size of particles and the identification of their sources were carried out at five orthopedic surgeries. The aerosol concentration and particle size distribution, ranging from 0.3 mu m 10 mu m, were measured and related to the type of indoor activity. The handling of surgical linen and gowns, handling of the patient, use of electrosurgical apparatus, use of a bone saw, handling of equipment, and cleaning of the room were identified as the most important sources of particles, with each of these activities posing different risks to the health of the patients and workers. The results showed that most of the particles were above 0.5 mu m and that there was a strong correlation among all particles of sizes above 1 mu m. Particles with diameters in the range of 0.3 mu m-0.5 mu m had a good correlation only with particles in the ranges of 0.5 mu m-1.0 mu m and 1.0 mu m-3.0 mu m in three of the surgeries analyzed. Findings led to the conclusion that most of the events responsible for generating aerosol particles in an orthopedic surgery room are brief, intermittent, and highly variable, thus requiring the use of specific instrumentation for their continuous identification and characterization.

Observation of vinylidene emission in mixed phosphine/diimine complexes of Ru(II) at room temperature in solution

The mixed ruthenium(II) complexes trans-[RuCl(2)(PPh(3))(2)(bipy)] (1), trans-[RuCl(2)(PPh(3))(2)(Me(2)bipy)](2), cis-[RuCl(2)(dcype)(bipy)](3), cis-[RuCl(2)(dcype)(Me(2)bipy)](4) (PPh(3) = triphenylphosphine, dcype = 1,2-bis(dicyclohexylphosphino)ethane, bipy = 2,2'-bipyridine, Me(2)bipy = 4,4'-dimethyl-2,2'-bipyridine) were used as precursors to synthesize the associated vinylidene complexes. The complexes [RuCl(=C=CHPh)(PPh(3))(2)(bipy)]PF(6) (5), [RuCl(=C=CHPh)(PPh(3))(2)(Me(2)bipy)]PF(6) (6), [RuCl(=C=CHPh)(dcype)(bipy)]PF(6) (7), [RuCl(=C=CHPh)(dcype)(bipy)]PF(6) (8) were characterized and their spectral, electrochemical, photochemical and photophysical properties were examined. The emission assigned to the pi-pi* excited state from the vinylidene ligand is irradiation wavelength (340, 400, 430 nm) and solvent (CH(2)Cl(2), CH(3)CN, EtOH/MeOH) dependent. The cyclic voltammograms of (6) and (7) show a reversible metal oxidation peak and two successive ligand reductions in the +1.5-(-0.64) V range. The reduction of the vinylidene leads to the formation of the acetylide complex, but due the hydrogen abstraction the process is irreversible. The studies described here suggest that for practical applications such as functional materials, nonlinear optics, building blocks and supramolecular photochemistry. (C) 2011 Elsevier B.V. All rights reserved.

Ultrasound-assisted synthesis of aliphatic acid esters at room temperature

This work describes the ultrasound-assisted synthesis of saturated aliphatic esters from synthetic aliphatic acids and either methanol or ethanol. The products were isolated in good yields after short reaction times under mild conditions. (C) 2011 Elsevier BM. All rights reserved.

An electrochemical gas sensor based on paper supported room temperature ionic liquids

A sensitive and fast-responding membrane-free amperometric gas sensor is described, consisting of a small filter paper foil soaked with a room temperature ionic liquid (RTIL), upon which three electrodes are screen printed with carbon ink, using a suitable mask. It takes advantage of the high electrical conductivity and negligible vapour pressure of RTILs as well as their easy immobilization into a porous and inexpensive supporting material such as paper. Moreover, thanks to a careful control of the preparation procedure, a very close contact between the RTIL and electrode material can be achieved so as to allow gaseous analytes to undergo charge transfer just as soon as they reach the three-phase sites where the electrode material, paper supported RTIL and gas phase meet. Thus, the adverse effect on recorded currents of slow steps such as analyte diffusion and dissolution in a solvent is avoided. To evaluate the performance of this device, it was used as a wall-jet amperometric detector for flow injection analysis of 1-butanethiol vapours, adopted as the model gaseous analyte, present in headspace samples in equilibrium with aqueous solutions at controlled concentrations. With this purpose, the RTIL soaked paper electrochemical detector (RTIL-PED) was assembled by using 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide as the wicking RTIL and printing the working electrode with carbon ink doped with cobalt(II) phthalocyanine, to profit from its ability to electrocatalyze thiol oxidation. The results obtained were quite satisfactory (detection limit: 0.5 mu M; dynamic range: 2-200 mu M, both referring to solution concentrations; correlation coefficient: 0.998; repeatability: +/- 7% RSD; long-term stability: 9%), thus suggesting the possible use of this device for manifold applications.

The role of pneumonia scores in the emergency room in patients infected by 2009 H1N1 infection

Despite the severity of pneumonia in patients with pandemic influenza A infection (H1N1), no validated risk scores associated with H1N1 pneumonia were tested. In this prospective observational study, we analyzed data of consecutive patients in our emergency room, hospitalized because of pneumonia between July and August 2009 in a public hospital in Brazil. The following pneumonia scoring systems were applied: the SMART-COP rule; the Pneumonia Severity Index; and the CURB-65 rule. Of 105 patients with pneumonia, 53 had H1N1 infection. Among them, only 9.5% that had a low risk according to SMART-COP were admitted to ICU, compared with 36.8% of those with the Pneumonia Severity Index score of 1-2 and 49% of those with CURB-65 score of 0-1. The SMART-COP had an accuracy of 83% to predict ICU admission. The SMART-COP rule presented the best performance to indicate ICU admission in patients with H1N1 pneumonia. European Journal of Emergency Medicine 19: 200-202 (C) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

Current practices in the management of patients with ureteral calculi in the emergency room of a university hospital

OBJECTIVE: Urinary lithiasis is a common disease. The aim of the present study is to assess the knowledge regarding the diagnosis, treatment and recommendations given to patients with ureteral colic by professionals of an academic hospital. MATERIALS AND METHODS: Sixty-five physicians were interviewed about previous experience with guidelines regarding ureteral colic and how they manage patients with ureteral colic in regards to diagnosis, treatment and the information provided to the patients. RESULTS: Thirty-six percent of the interviewed physicians were surgeons, and 64% were clinicians. Forty-one percent of the physicians reported experience with ureterolithiasis guidelines. Seventy-two percent indicated that they use noncontrast CT scans for the diagnosis of lithiasis. All of the respondents prescribe hydration, primarily for the improvement of stone elimination (39.3%). The average number of drugs used was 3.5. The combination of nonsteroidal anti-inflammatory drugs and opioids was reported by 54% of the physicians (i. e., 59% of surgeons and 25.6% of clinicians used this combination of drugs) (p = 0.014). Only 21.3% prescribe alpha blockers. CONCLUSION: Reported experience with guidelines had little impact on several habitual practices. For example, only 21.3% of the respondents indicated that they prescribed alpha blockers; however, alpha blockers may increase stone elimination by up to 54%. Furthermore, although a meta-analysis demonstrated that hydration had no effect on the transit time of the stone or on the pain, the majority of the physicians reported that they prescribed more than 500 ml of fluid. Dipyrone, hyoscine, nonsteroidal anti-inflammatory drugs, and opioids were identified as the most frequently prescribed drug combination. The information regarding the time for the passage of urinary stones was inconsistent. The development of continuing education programs regarding ureteral colic in the emergency room is necessary.

Accuracy of five electronic foramen locators with different operating systems: na ex vivo study

Objective: The aim of this study was to evaluate, ex vivo, the precision of five electronic root canal length measurement devices (ERCLMDs) with different operating systems: the Root ZX, Mini Apex Locator, Propex II, iPex, and RomiApex A-15, and the possible influence of the positioning of the instrument tips short of the apical foramen. Material and Methods: Forty-two mandibular bicuspids had their real canal lengths (RL) previously determined. Electronic measurements were performed 1.0 mm short of the apical foramen (-1.0), followed by measurements at the apical foramen (0.0). The data resulting from the comparison of the ERCLMD measurements and the RL were evaluated by the Wilcoxon and Friedman tests at a significance level of 5%. Results: Considering the measurements performed at 0.0 and -1.0, the precision rates for the ERCLMDs were: 73.5% and 47.1% (Root ZX), 73.5% and 55.9% (Mini Apex Locator), 67.6% and 41.1% (Propex II), 61.7% and 44.1% (iPex), and 79.4% and 44.1% (RomiApex A-15), respectively, considering ±0.5 mm of tolerance. Regarding the mean discrepancies, no differences were observed at 0.0; however, in the measurements at -1.0, the iPex, a multi-frequency ERCLMD, had significantly more discrepant readings short of the apical foramen than the other devices, except for the Propex II, which had intermediate results. When the ERCLMDs measurements at -1.0 were compared with those at 0.0, the Propex II, iPex and RomiApex A-15 presented significantly higher discrepancies in their readings. Conclusions: Under the conditions of the present study, all the ERCLMDs provided acceptable measurements at the 0.0 position. However, at the -1.0 position, the ERCLMDs had a lower precision, with statistically significant differences for the Propex II, iPex, and RomiApex A-15.

Knowledge management, market orientation, innovativeness and organizational outcomes: a study on companies operating in Brazil

This article analyzes the study of the relationship among knowledge management, the company's market orientation, innovativeness and organizational outcomes. The survey was conducted based on a survey held with executives from 241 companies in Brazil. The evidence found indicates that knowledge management directly contributes to market orientation, but it requires a clearly defined strategic direction to achieve results and innovativeness. It was also concluded that knowledge, as a resource, leverages other resources of the company, while it requires a direction in relation to the organizational goals in order to be effective.