Population growth, arable land and fresh water limits, and climate change have profound implications for the ability of agriculture to meet this century's demands for food, feed, fiber, and fuel ...while reducing the environmental impact of their production. Success depends on the acceptance and use of contemporary molecular techniques, as well as the increasing development of farming systems that use saline water and integrate nutrient flows.
Numerical Semigroups García-Sánchez, P. A; Rosales, J. C
2010, 2009, 20090821, 2009-09-01, Letnik:
20
eBook
"This monograph is the first devoted exclusively to the development of the theory of numerical semigroups. In this concise, self-contained text, graduate students and researchers will benefit from ...this broad exposition of the topic. Key features of ""Numerical Semigroups"" include: - Content ranging from the basics to open research problems and the latest advances in the field, - Exercises at the end of each chapter that expand upon and support the material, - Emphasis on the computational aspects of the theory, algorithms are presented to provide effective calculations, - Many examples that illustrate the concepts and algorithms, - Presentation of various connections between numerical semigroups and number theory, coding theory, algebraic geometry, linear programming, and commutative algebra would be of significant interest to researchers."
Mediterranean diet has been related with reduced morbidity and better well-being. The aim of this study was to assess whether the adherence to the Mediterranean diet were associated with mental and ...physical health related to quality of life.
This analysis included 11 015 participants with 4 years of follow-up in the SUN Project (a multipurpose cohort study based on university graduates from Spain). A validated 136-item food frequency questionnaire was used to assess the adherence to the Mediterranean diet at baseline, according to a nine-point score, presented in four categories (low, low-moderate, moderate-high and high). Health-related quality of life (HRQL) was measured after 4 years of follow-up with the Spanish version of the SF-36 Health Survey. Generalized Linear Models were fitted to assess adjusted mean scores, the regression coefficients (β) and their 95% confidence intervals (95% CIs) for the SF-36 domains according to categories of adherence to Mediterranean diet.
Multivariate-adjusted models revealed a significant direct association between adherence to Mediterranean diet and all the physical and most mental health domains (vitality, social functioning and role emotional). Vitality (β=0.50, 95% CI=0.32-0.68) and general health (β=0.45, 95% CI=0.26-0.62) showed the highest coefficients. Mean values for physical functioning, role physical, bodily pain, general health and vitality domains were significantly better with increasing adherence to the Mediterranean diet. Those having improved their initial high diet scores have better scores in physical functioning, general health and vitality.
Adherence to the Mediterranean diet seems to be a factor importantly associated with a better HRQL.
•Aspen Plus® was used to simulate the gasification process in a BFB reactor.•Two kinetic models have been developed based on two literature kinetic models.•A large number of experimental data were ...used for the calibration and validation.•These models have also considered and evaluated the tar formation.•The model developed in Aspen Plus® give accurate predictions of experimental data.
The direct (with air) gasification process of biomass in bubbling fluidized bed reactor was simulated using Aspen Plus®. The reactor was divided in three parts: the pyrolysis zone, combustion zone and reduction zone. The pyrolysis process simulation was supported by an external MS-Excel® subroutine to define the yield and composition of the main components, namely, char, gas and tar. Whereas the combustion and reduction processes were simulated using a kinetic model. These models were calibrated and thereafter validated with a set of distinct results from gasification of four different types of biomass using a pilot-scale bubbling fluidized bed reactor, with different equivalence ratio (from 0.17 to 0.35) and temperature (from 709 °C to 859 °C). The results obtained from the simulation, namely the concentration of CO, CO2, H2, CH4, C2H4 in the producer gas, were in good agreement with the experimental ones for a set of biomass types and operating conditions. Amongst the gases analysed, H2 gas was predicted with the lowest accuracy, always being overestimated; despite that, the highest absolute error obtained for H2 was only 4.4%. Finally, the tar concentration predicted was between 20 and 42 g/Nm3 and it decreased with the increase of equivalence ratio, temperature and biomass particle size.
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•Mono and bimetallic perovskites are catalyst precursors for H2 production from NH3.•Co content on bimetallic perovskites and the addition of two dopant were optimized.•LaCo1-xNixO3 ...lead higher Ni crystallite size than pure LaNiO3 decreasing activity.•Ce and Mg dopants on LaNiO3 perovskites reduce Ni size and increase basicity.•Mg dopant (0.9 mol/mol) leads 72% NH3 conversion at 350 °C with admirable stability.
LaCo1-xNixO3 perovskites have been synthesized by self-combustion, characterized, and examined as catalyst precursors for the COx-free hydrogen production from catalytic ammonia decomposition at low temperatures. The influence of the cobalt content as well as the addition of two dopant in different amount was studied and optimized. Small Ni crystallite size and high total basic sites were found to remarkably enhance the catalytic activity. Moreover, bimetallic perovskites generated cobalt/nickel in higher size, higher impurities and lower active sites than pure nickel perovskite, which decreased the ammonia conversion. On the other hand, the addition of dopant in adequate amount over pure Ni perovskite (La0.1A0.9NiO3; A = Ce or Mg) generated catalyst with low nickel crystallite size and high basicity delivering superior catalytic performance. Catalysts were demonstrated to be stable for at least 40 h. In fact, 96 % and 98 % ammonia conversion were achieved at low temperature (400 °C), when La0.1Ce0.9NiO3 and La0.1Mg0.9NiO3 were employed, resulting from the synergic effect between La-Ce and Ni-Mg-La. Presenting the Mg-doped perovskite the highest catalytic activity at the mild temperature of 350 °C.
This study provides new insight in designing diverse catalyst precursors to develop economic and efficient catalysts to achieve high ammonia conversion (high hydrogen production) at low temperature and enhance the ammonia perspective as hydrogen carrier toward the ‘hydrogen economy’.
In this Paper, we describe how we use stellar dynamics information to constrain the shape of the stellar initial mass function (IMF) in a sample of 27 early-type galaxies from the CALIFA survey. We ...obtain dynamical and stellar mass-to-light ratios, ... and ..., over a homogenous aperture of 0.5 R sub( e). We use the constraint ... to test two IMF shapes within the framework of the extended MILES stellar population models. We rule out a single power-law IMF shape for 75 per cent of the galaxies in our sample. Conversely, we find that a double power-law IMF shape with a varying high-mass end slope is compatible (within ...) with 95 per cent of the galaxies. We also show that dynamical and stellar IMF mismatch factors give consistent results for the systematic variation of the IMF in these galaxies. (ProQuest: ... denotes formulae/symbols omitted.)
ABSTRACT Understanding the nature of spiral structure in disk galaxies is one of the main, and still unsolved, questions in galactic astronomy. However, theoretical works are proposing new testable ...predictions whose detection is becoming feasible with recent development in instrumentation. In particular, streaming motions along spiral arms are expected to induce azimuthal variations in the chemical composition of a galaxy at a given galactic radius. In this Letter, we analyze the gas content in NGC 6754 with VLT/MUSE data to characterize its 2D chemical composition and H line of sight velocity distribution. We find that the trailing (leading) edge of the NGC 6754 spiral arms show signatures of tangentially slower, radially outward (tangentially faster, radially inward) streaming motions of metal-rich (poor) gas over a large range of radii. These results show direct evidence of gas radial migration for the first time. We compare our results with the gas behavior in an N-body disk simulation showing spiral morphological features rotating with a similar speed as the gas at every radius, in good agreement with the observed trend. This indicates that the spiral arm features in NGC 6754 may be transient and rotate similarly as the gas does at a large range of radii.
•A new methodology for modal parameter identification of large civil structures.•It uses MUSIC-EWT algorithm and Hilbert transform.•It is applied to a 123-story highrise building structure, Lotte ...World Tower.•It is effective for modal parameter identification of superhighrise structures.•It can deal with noisy signals.
A key issue in health monitoring of smart structures is the estimation of modal parameters such as natural frequencies and damping ratios from acquired dynamic signals. In this article, a new methodology is presented for calculating the natural frequencies (NF) and damping ratios (DR) of large civil infrastructure from acquired dynamic signals using a multiple signal classification (MUSIC) algorithm, the empirical wavelet transform (EWT), and the Hilbert transform. The effectiveness of the proposed method is validated by means of three examples: a benchmark 3D 4-story steel frame structure, a benchmark problem, subjected to dynamic loading, an 8-story steel frame subjected to white noise input on a shaking table, and a 123-story highrise building structure, Lotte World Tower (LWT), under construction in Seoul, South Korea. The results demonstrate that the new methodology is accurate for estimating the NF and DR of a superhighrise building structure using low-amplitude ambient vibrations data, a complex and challenging task since the measured vibrations signals are noisy and present non-stationary characteristics. The new methodology can deal with noisy signals without degrading its ability to estimate the NF and DR of different one-of-a kind civil structures thus is particularly suitable for health monitoring of large smart structures under dynamic loading.
A long-standing ambition in ecosystem science has been to understand the relationship between ecosystem community composition, structure and function. Differential water use and hydraulic ...redistribution have been proposed as one mechanism that might allow for the coexistence of overstory woody plants and understory grasses.
Here, we investigated how patterns of hydraulic redistribution influence overstory and understory ecophysiological function and how patterns vary across timescales of an individual precipitation event to an entire growing season. To this end, we linked measures of sap flux within lateral and tap roots, leaf-level photosynthesis, ecosystem-level carbon exchange and soil carbon dioxide efflux with local meteorology data.
The hydraulic redistribution regime was characterized predominantly by hydraulic descen relative to hydraulic lift. We found only a competitive interaction between the overstory and understory, regardless of temporal time scale. Overstory trees used nearly all water lifted by the taproot to meet their own transpirational needs.
Our work suggests that alleviating water stress is not the reason we find grasses growing in the understory of woody plants; rather, other stresses, such as excessive light and temperature, are being ameliorated. As such, both the two-layer model and stress gradient hypothesis need to be refined to account for this coexistence in drylands.
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•Lanthanum perovskites are promising catalyst precursors for H2 production from NH3.•Catalytic activity is influenced by the synthesis conditions of the perovskites.•Proper qualities ...can be obtained with citric acid/metal nitrates molar ratio of 1.•Calcination at 650 °C (Ni) and a molar ratio of 1 achieve a 99% NH3 conversion.•Selected catalysts from perovskites show excellent stability after 24 h of reaction.
LaNiO3 and LaCoO3 perovskites synthesized by self-combustion were characterised and studied in the ammonia decomposition reaction for obtaining hydrogen. Both the fuel to metal nitrates molar ratio and calcination temperature were found to be crucial to synthesize perovskites by self-combustion. Moreover, generating non-precursor species during synthesis and small metal size were two factors which significantly influenced catalytic activity. Hence, with a citric acid to metal nitrates molar ratio equal to one a LaNiO3 perovskite was obtained with suitable physicochemical properties (specific surface area, lower impurities, and basicity). In addition, a lower calcination temperature (650 °C) resulted in small and well-dispersed Ni0 crystallite size after reduction, which in turn, promoted the catalytic transformation of ammonia into hydrogen. For cobalt perovskites, calcination temperature below 900 °C did not have a significant influence on the size of the metallic cobalt crystallite size. The nickel and cobalt perovskite-derived catalysts, calcined at 650 °C and 750 °C, respectively, yielded excellent H2 production from ammonia decomposition. In particular, at 450 °C almost 100% of the ammonia was converted over the LaNiO3 under study. Furthermore, these materials displayed admirable performance and stability after one day of reaction.
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