201 research outputs found
Amine-impregnated Alumina Solid Sorbents for CO2 Capture. Lessons Learned
The application of Amine-impregnated Alumina Solid Sorbent Carbon Capture is a suitable option to increase CO2 capture efficiency and to reduce by several percentage points the efficiency penalty of CCS in power plants. These sorbents require less regeneration energy due to the reduction in water content and the higher heat capacity of solids. The objective is to demonstrate that the use of amine-impregnated alumina solid sorbents is a suitable option to increase CO2 capture efficiency and to reduce several percentage points the efficiency penalty caused by the capture system in the power plant. The proposed innovative sorbent consists in amines supported on high surface area and high porosity solid materials, such as alumina and silica-alumina. Good results have been achieved. Important high porosity support makes possible to obtain high CO2 capture capacities over 50 mg CO2/g of sorbent. As a consequence, the combination of this CCS option with a coal power plant may reduce the efficiency penalty down to 7 efficiency points. This figure could make feasible the impregnated amine solid sorbent as a future and promising option for CO2 capture
On the Flexibility of Coal-fired Power Plants with Integrated Ca-looping CO2 Capture Process
The share of renewable energy production is growing quickly. The output and variability of renewable power will force to fossil fuel power plants to adapt its electricity production to variable demand. In a future scenario, with CO2 capture systems installed in power plants, the variable performance will affect not only to fossil fuel power plant but also to the CO2 capture behavior. The knowledge of part load performance of fossil fuel power plants with CO2 capture systems will be essential in a near future. This paper analyzes the integration between Ca-looping cycles and power plants to foresee the requirements derived from a flexible operation. With this goal, the performance of the integrated system under different load scenarios is studied. An integration scheme designed for nominal load is proposed under different load scenarios at steady state, to study their performance. Then, for each load scenario, the optimum integration is designed, to quantify the minimum energy penalty of each specific load level. Finally, a comparative analysis of the general integration against the optimum one for each scenario is performed
Energy Integration of High and Low Temperature Solid Sorbents for CO2 Capture
It is crucial to reduce the energy penalties related to CO2 capture processes if CCS is to be implemented at industrial scale. In this context, gas-solid sorption has become a relevant technology. The absence of large amounts of water when using dry solid sorbents and their high heat capacity reduce the energy requirements in the gas-solid sorption CO2 capture process. Depending on the sorbent composition, the gas-solid sorption process carries out at high or low temperatures. High temperature sorbents allow the utilization of waste energy while energy requirements in low temperature processes will be less demanding. This study is focused on the assessment and comparison of the final energy penalty of low-temperature (amine impregnated alumina-based solid particles) and high-temperature solid sorbents capture process (calcium oxide)
The Calcium-Looping technology for CO2 capture: On the important roles of energy integration and sorbent behavior
The Calcium Looping (CaL) technology, based on the multicyclic carbonation/calcination of CaO in gas-solid fluidized bed reactors at high temperature, has emerged in the last years as a potentially low cost technology for CO2 capture. In this manuscript a critical review is made on the important roles of energy integration and sorbent behavior in the process efficiency. Firstly, the strategies proposed to reduce the energy demand by internal integration are discussed as well as process modifications aimed at optimizing the overall efficiency by means of external integration. The most important benefit of the high temperature CaL cycles is the possibility of using high temperature streams that could reduce significantly the energy penalty associated to CO2 capture. The application of the CaL technology in precombustion capture systems and energy integration, and the coupling of the CaL technology with other industrial processes are also described. In particular, the CaL technology has a significant potential to be a feasible CO2 capture system for cement plants. A precise knowledge of the multicyclic CO2 capture behavior of the sorbent at the CaL conditions to be expected in practice is of great relevance in order to predict a realistic capture efficiency and energy penalty from process simulations. The second part of this manuscript will be devoted to this issue. Particular emphasis is put on the behavior of natural limestone and dolomite, which would be the only practical choices for the technology to meet its main goal of reducing CO2 capture costs. Under CaL calcination conditions for CO2 capture (necessarily implying high CO2 concentration in the calciner), dolomite seems to be a better alternative to limestone as CaO precursor. The proposed techniques of recarbonation and thermal/mechanical pretreatments to reactivate the sorbent and accelerate calcination will be the final subjects of this review
Psychometric properties of the Actively Open-minded Thinking scale
The Actively Open-minded Thinking scale (AOT; Stanovich & West, 2007) is a questionnaire that is used to measure the disposition towards rational thinking as a single psychological trait. Yet, despite its frequent use, also in abbreviated form, it is still unclear whether sumscores of the AOT can actually be used to order individuals on their disposition towards actively open-minded thinking and whether the questionnaire can be validly shortened. The present study aimed to obtain a valid and shorter AOT. We conducted Mokken scale analyses on the (Dutch) AOT using two samples of higher education students (N = 930; N = 509). Our analyses showed that none of the 41 items could discriminate sufficiently between respondents with varying latent trait levels. Furthermore, no item-set of the AOT could be obtained to validly order individuals on the assumed latent trait, which is a crucial assumption when using it in research. Consequently, it is questionable whether scores on the AOT provide insights into the concept it aims to measure
Dibutyl phthalate induced testicular dysgenesis originates after seminiferous cord formation in rats
Administration of dibutyl phthalate (DBP) to pregnant rats causes reproductive disorders in male offspring, resulting from suppression of intratesticular testosterone, and is used as a model for human testicular dysgenesis syndrome (TDS). DBP exposure in pregnancy induces focal dysgenetic areas in fetal testes that appear between e19.5-e21.5, manifesting as focal aggregation of Leydig cells and ectopic Sertoli cells (SC). Our aim was to identify the origins of the ectopic SC. Time-mated female rats were administered 750 mg/kg/day DBP in three different time windows: full window (FW; e13.5-e20.5), masculinisation programming window (MPW; e15.5-e18.5), late window (LW; e19.5-e20.5). We show that DBP-MPW treatment produces more extensive and severe dysgenetic areas, with more ectopic SC and germ cells (GC) than DBP-FW treatment; DBP-LW induces no dysgenesis. Our findings demonstrate that ectopic SC do not differentiate de novo, but result from rupture of normally formed seminiferous cords beyond e20.5. The more severe testis dysgenesis in DBP-MPW animals may result from the presence of basally migrating GC and a weakened basal lamina, whereas GC migration was minimal in DBP-FW animals. Our findings provide the first evidence for how testicular dysgenesis can result after normal testis differentiation/development and may be relevant to understanding TDS in human patients. © 2017 The Author(s)
Genetic and environmental influences on structure of the social brain in childhood
Prosocial behavior and empathy are important aspects of developing social relations in childhood. Prior studies showed protracted structural development of social brain regions associated with prosocial behavior. However, it remains unknown how structure of the social brain is influenced by genetic or environmental factors, and whether overlapping heritability factors explain covariance in structure of the social brain and behavior. The current study examined this hypothesis in a twin sample (aged 7–9-year; N = 512). Bilateral measures of surface area and cortical thickness of the medial prefrontal cortex (mPFC), temporo-parietal junction (TPJ), posterior superior temporal sulcus (pSTS), and precuneus were analyzed. Results showed genetic contributions to surface area and cortical thickness for all brain regions. We f
The <i>Castalia</i> mission to Main Belt Comet 133P/Elst-Pizarro
We describe Castalia, a proposed mission to rendezvous with a Main Belt Comet (MBC), 133P/Elst-Pizarro. MBCs are a recently discovered population of apparently icy bodies within the main asteroid belt between Mars and Jupiter, which may represent the remnants of the population which supplied the early Earth with water. Castalia will perform the first exploration of this population by characterising 133P in detail, solving the puzzle of the MBC’s activity, and making the first in situ measurements of water in the asteroid belt. In many ways a successor to ESA’s highly successful Rosetta mission, Castalia will allow direct comparison between very different classes of comet, including measuring critical isotope ratios, plasma and dust properties. It will also feature the first radar system to visit a minor body, mapping the ice in the interior. Castalia was proposed, in slightly different versions, to the ESA M4 and M5 calls within the Cosmic Vision programme. We describe the science motivation for the mission, the measurements required to achieve the scientific goals, and the proposed instrument payload and spacecraft to achieve these
Beyond the Average Brain: Individual Differences in Social Brain Development are Associated with Friendship Quality
We tested whether adolescents differ from each other in the structural development of the
social brain, and whether individual differences in social brain development predicted
variability in friendship quality development. Adolescents (N = 299, Mage T1 = 13.98 years)
were followed across three bi-annual waves. We analysed self-reported friendship quality
with the best friend at T1 and T3, and bilateral measures of surface area and cortical
thickness of the medial prefrontal cortex (mPFC), posterior superior temporal sulcus (pSTS),
temporo-parietal junction (TPJ), and precuneus across all waves. At the group level, growth
curve models confirmed non-linear decreases of surface area and cortical thickness in social
brain regions. We identified substantial individual differences in levels and change rates of
social brain regions, especially for surface area of the mPFC, pSTS, and TPJ. Change rates of
cortical thickness varied less between persons. Higher levels of mPFC surface area and
cortical thickness predicted stronger increases in friendship quality over time. Moreover,
faster cortical thinning of mPFC surface area predicted a stronger increase in friendship
quality. Higher levels of TPJ cortical thickness predicted lower friendship quality. Together,
our results indicate heterogeneity in social brain development and how this variability
uniquely predicts friendship quality development
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Validation of the NANA (Novel Assessment of Nutrition and Ageing) touch screen system for use at home by older adults
Prospective measurement of nutrition, cognition, and physical activity in later life would facilitate early detection of detrimental change and early intervention but is hard to achieve in community settings. Technology can simplify the task and facilitate daily data collection. The Novel Assessment of Nutrition and Ageing (NANA) toolkit was developed to provide a holistic picture of an individual's function including diet, cognition and activity levels. This study aimed to validate the NANA toolkit for data collection in the community. Forty participants aged 65 years and over trialled the NANA toolkit in their homes for three 7-day periods at four-week intervals. Data collected using the NANA toolkit were compared with standard measures of diet (four-day food diary), cognitive ability (processing speed) and physical activity (self-report). Bland–Altman analysis of dietary intake (energy, carbohydrates, protein fat) found a good relationship with the food diary and cognitive processing speed and physical activity (hours) were significantly correlated with their standard counterparts. The NANA toolkit enables daily reporting of data that would otherwise be collected sporadically while reducing demands on participants;
older adults can complete the daily reporting at home without a researcher being present; and it enables prospective investigation of several domains at onc
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