Characterization of patterns of food packaging usage in Portuguese homes

This study aimed to further refine the exposure assessment of migrants from food-contact materials by characterizing, at the household level, food packaging usage (amount and type) in Portuguese urban families. Packages from domestic use were collected from a sample of 105 consumers from 34 households over a 30-day period. Collected packages (more than 6000 items) were characterized in the laboratory and data were used to estimate: (i) global packaging usage and food intake; (ii) the consumption factors (CF) that describe the fraction of the daily diet expected to be in contact with specific packaging materials and (iii) the food-type factors (FTF) that reflect the fraction of all food contacting each material which differ in nature according to six major types: aqueous, acidic, alcoholic, milky, fatty and dry. The daily intake of packaged food and beverages consumed at home ranged from 5–50 g kg^?1 bw. Considering all materials, total package usage ranged from 0.1 to 0.6 dm² day^?1 kg^?1 bw. The ratio between package surface area in contact and the quantity of food was determined for all packaging items collected and an average value of 25 dm² kg^?1 food was recorded. Data were gathered and presented in a manner compatible with current probabilistic approaches to exposure assessment. In this way, relevant consumption patterns from this type of population can be best represented in exposure assessments and subsequent risk assessments.     

A ‘context-aware’ and agent-centric perspective for the alignment between individuals and organizations

The enterprise modeling field aims at representing organizations from several, inter-related perspectives. A number of enterprise modeling frameworks have been developed providing models, methods and tools that enable to communicate the structure and processes of organizations. These frameworks have been used both for systems development and organizational analysis ends, where the latter mainly focuses process (re)design efforts. We argue that enterprise modeling frameworks can be used for other kinds of organizational analysis. In particular, they can be used to capture and model work practices, human multitasking at work, and to compare models describing pre-defined behavior with actual execution.     

Ostwald Ripening of precipitates and self similarity of size distributions in reaction controlled growth

We present a mathematical model to describe competitive growth of spherical precipitates in reaction-controlled systems. In this model the flux of solute atoms through the interface depends on the interface migration velocity and on the differences of chemical potential at the interface. The growth-rate obtained is dependent on the precipitate radius, much like in the diffusion-controlled case. Numerical simulations were performed using a modified finite-difference approach where the time-step increase changes during evolution to avoid dissolution of more than one precipitate each step. By using the continuity equation we obtained an analytical function that represents the self-similar shape of the precipitate-size distribution dependent of the growth-parameter ν. The effect of ν on the coarsening evolution was investigated. Our results show that the precipitate size distribution obtained from the numerical simulations agrees well with the analytical solution. As predicted by the theory, we obtained the growth parameter (ν = 4) and the temporal dependence of the mean-radius (t ^1/2) different of the diffusion case, ν = 6.75 and t ^1/3. We also show that the self-similarity of the PSD is independent of the initial PSD. Presented at the V Symposium of the Brazil-MRS. Florianópolis, 8–12 October 2006.     

SOFC-APU systems for aircraft: A review

This review brings together publications in the form of articles, reports, theses and patents related to the use of solid oxide fuel cells in aircraft with a focus on replacing the current auxiliary units with a hybrid system. The potential advantages and main challenges of the new technology are reported, indicating some possible trends in this technology. However, even after many studies, some initial challenges remain. For example, the hybrid system did not achieve the necessary weight-efficiency-ratio, and there seems to be no consensus on the choice of the best fuel. We conclude that the most viable short-term applications appear to be unmanned units, particularly because of security issues and low technology maturity. Smaller power applications, in which the new system is responsible for peripheral services such as a power supply for air conditioning, toilets, and heating up food, are candidates to enter the market in the short or medium term. In the long term, applications for fully electric aircraft and clean fuels will certainly be the focus of larger aircraft manufacturers.     

Degradation profiles of poly(methylene oxide) and poly(glycolic acid) for inflow control devices in oil wells

The viability of the application of hydrolysable polymers, such as poly(methylene oxide) (PMO) and poly(glycolic acid) (PGA), in formation treatments in oil wells, was studied; we examined their addition to inflow control devices (ICDs), which are instruments used to control the oil‐flow profile along production intervals. Thereby, the structural and morphological changes of PMO and PGA samples exposed to common chemicals, such as hydrochloric acid (HCl) and sodium chloride (NaCl) solutions and xylene, used in the procedure were evaluated under conditions similar to those observed in southeastern Brazilian offshore oil fields (temperature range = 50–130 °C, 41.4 MPa). The aim of this study was to verify whether the polymers hydrolyzed and could be further removed from the ICDs. Techniques including high‐pressure liquid chromatography, ion chromatography, ¹³C‐NMR, differential scanning calorimetry, scanning electron microscopy, and optical microscopy were applied in this study. Xylene did not produce expressive effects in the samples. PMO was significantly affected by 15% HCl at 75 °C but was not completely dissolved after 24 h of exposure; this counter indicates its use. The PGA hydrolysis profile in NaCl brine was suitable for application around 75 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43786.     

Measurements of the isothermal, power and temperature reactivity coefficients of the IPR-R1 TRIGA reactor

The aim of this paper is to present the experimental results of the isothermal, power and temperature coefficients of reactivity of the IPR-R1 TRIGA reactor at the Nuclear Technology Development Center - CDTN in Brazil. The measured isothermal reactivity coefficient, in the temperature range measured, was −0.5 ¢/°C, and the reactivity measurements were performed at 10 W to eliminate nuclear heating. The reactor forced cooling system was turned off during the measurements. When the reactor is at zero power there is no sensible heat being released in the fuel, and the entire reactor core can be characterized by a single temperature. The power coefficient of reactivity obtained was approximately −0.63 ¢/kW, and the temperature reactivity coefficient of the reactor was −0.8 ¢/°C. It was noted that the rise in the coolant temperature has contributed only with a small fraction to the observed negative effect of the reactivity. The power defect, which is the change in reactivity taking place between zero power and full power (250 kW), was 1.6 $. Because of the prompt negative temperature coefficient, a significant amount of reactivity is needed to overcome temperature and allow the reactor to operate at the higher power levels in steady state.     

Reactivity balance in the IPR-R1 TRIGA reactor

Considering that the power of the IPR-R1 TRIGA reactor, located at the Nuclear Technology Development Center, Brazil, will be increased from 100 kW to 250 kW, some experiments were done in order to evaluate the magnitude of the reactivity effects associated with the reactor operation. The core excess of reactivity obtained was 1.99 $, and the shutdown margin was 1.33 $. The reactivity needed to operate the IPR-R1 reactor at 100 kW was 0.72 $, mainly due to the prompt negative temperature coefficient. A significant amount of reactivity is needed to overcome temperature and allow the reactor to operate at the higher power levels. The loss of reactivity due to xenon poisoning after 8 h of operation at 100 kW was around 0.20 $, and the highest reactivity loss value caused by a void inserted in the central thimble was 0.22 $. From the results obtained, it was possible to balance all the determined reactivity losses with the reactivity excess available in the reactor, considering the present and the future reactor power operation.     

Thermal power calibrations of the IPR-R1 TRIGA reactor by the calorimetric and the heat balance methods

Since the first nuclear reactor was built, a number of methodological variations have been evolved for the calibration of the reactor thermal power. Power monitoring of reactors is done by means of neutronic instruments, but its calibration is always done by thermal procedures. The purpose of this paper is to present the results of the thermal power calibration carried out on March 5th, 2009 in the IPR-R TRIGA reactor. It was used two procedures: the calorimetric and heat balance methods. The calorimetric procedure was done with the reactor operating at a constant power, with primary cooling system switched off. The rate of temperature rise of the water was recorded. The reactor power is calculated as a function of the temperature-rise rate and the system heat capacity constant. The heat balance procedure consists in the steady-state energy balance of the primary cooling loop of the reactor. For this balance, the inlet and outlet temperatures and the water flow in the primary cooling loop were measured. The heat transferred through the primary loop was added to the heat leakage from the reactor pool. The calorimetric method calibration presented a large uncertainty. The main source of error was the determination of the heat content of the system, due to a large uncertainty in the volume of the water in the system and a lack of homogenization of the water temperature. The heat balance calibration in the primary loop is the standard procedure for calibrating the power of the IPR-R1 TRIGA nuclear reactor.     

Evaluation of Nuclear Fuel Centerline Temperature Using New UO2 Thermal Conductivity Models

The nuclear industry needs of prediction of behavior and life-time, for a wide range of normal, off-normal and accident conditions for safe and economic operation. Among different thermo-mechanical properties that can be predictable, the knowledge on the radial temperature distribution of the UO2 （uranium dioxide） nuclear fuel during the operation of nuclear reactors is essential for safety as different mechanical and thermal-hydraulic thresholds should be respected. One of the attributes of the Brazilian CNEN （Nuclear Energy Commission） is to assess the performance of the fuel rods used in these reactors in high-bumup regimes. The effective removal of the heat generated in the fuel rods constitutes one of the primary points to consider in the design of nuclear reactors. One of the important physical parameters in the study of heat conduction from the nuclear fuel to the coolant in a PWR （pressurized water reactor） is its thermal conductivity. It is therefore desirable that the empirical models, updated for the calculation of thermal conductivity in the fuel region be developed from new sets of experimental data from the irradiated fuel rods in controlled environments This paper presents the obtained results of implementing of a new model for thermal conductivity of the UO2 in the FRAPCON code.     

Structural effects of the hydrolysis of poly(methylene oxide) and poly(glycolic acid) exposed to completion and acidizing fluids in an oil well environment

Two hydrolyzable polymers, poly(methylene oxide) (PMO) and poly(glycolic acid) (PGA), were tested for association with mechanical systems to promote diversion of formation acid treatments in oil wells. Samples were confined to chemical products commonly employed in oil well completion processes, HCl 15% w/w and NaCl 23% w/w aqueous solutions, in separate metallic cylindrical cells, under conditions observed in southeastern Brazilian offshore fields (50 and 75°C and pressure of 41.4 MPa). Pristine samples were characterized by ¹³C-NMR. Hydrolytic influences were evaluated by differential scanning calorimetry, scanning electron microscopy, wide angle X-ray diffraction, and computerized microtomography. The intense effects observed showed a specific correspondence with each tested polymer and were evidenced by postexposure analysis. The results indicate that both polymers can be used in association with mechanical diverting systems to promote chemical treatment distribution and, therefore, improve oil well productivity. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47362.