260 research outputs found
Measurement of nutrient leakage from organic crop rotation in Finland
Water discharge and nutrient leakage studies were conducted in an experimental field on organic farming practices for 20 years. Water discharge was measured and flow-weighted water samples were taken from mixed crop rotation
Kohn-Sham decomposition in real-time time-dependent density-functional theory: An efficient tool for analyzing plasmonic excitations
The real-time-propagation formulation of time-dependent density-functional
theory (RT-TDDFT) is an efficient method for modeling the optical response of
molecules and nanoparticles. Compared to the widely adopted linear-response
TDDFT approaches based on, e.g., the Casida equations, RT-TDDFT appears,
however, lacking efficient analysis methods. This applies in particular to a
decomposition of the response in the basis of the underlying single-electron
states. In this work, we overcome this limitation by developing an analysis
method for obtaining the Kohn-Sham electron-hole decomposition in RT-TDDFT. We
demonstrate the equivalence between the developed method and the Casida
approach by a benchmark on small benzene derivatives. Then, we use the method
for analyzing the plasmonic response of icosahedral silver nanoparticles up to
Ag. Based on the analysis, we conclude that in small nanoparticles
individual single-electron transitions can split the plasmon into multiple
resonances due to strong single-electron-plasmon coupling whereas in larger
nanoparticles a distinct plasmon resonance is formed.Comment: 11 pages, 3 figure
Hot-Carrier Generation in Plasmonic Nanoparticles: The Importance of Atomic Structure
Metal nanoparticles are attractive for plasmon-enhanced generation of hot
carriers, which may be harnessed in photochemical reactions. In this work, we
analyze the coherent femtosecond dynamics of photon absorption, plasmon
formation, and subsequent hot-carrier generation through plasmon dephasing
using first-principles simulations. We predict the energetic and spatial
hot-carrier distributions in small metal nanoparticles and show that the
distribution of hot electrons is very sensitive to the local structure. Our
results show that surface sites exhibit enhanced hot-electron generation in
comparison to the bulk of the nanoparticle. While the details of the
distribution depend on particle size and shape, as a general trend
lower-coordinated surface sites such as corners, edges, and {100} facets
exhibit a higher proportion of hot electrons than higher-coordinated surface
sites such as {111} facets or the core sites. The present results thereby
demonstrate how hot carriers could be tailored by careful design of
atomic-scale structures in nanoscale systems.Comment: 10 pages, 4 figure
Fertility of frozen-thawed stallion semen cannot be predicted by the currently used laboratory methods
The aim of the project was to use current simple and practical laboratory tests and compare results with the foaling rates of mares inseminated with commercially produced frozen semen. In Exp. 1, semen was tested from 27 and in Exp. 2 from 23 stallions; 19 stallions participated in both experiments. The mean number of mares per stallion in both experiments was 37 (min. 7, max. 121). Sperm morphology was assessed and bacterial culture performed once per stallion. In Exp. 1, progressive motility after 0, 1, 2, 3, and 4 h of incubation using light microscopy, motility characteristics measured with an automatic sperm analyzer, plasma membrane integrity using carboxyfluorescein diacetate/propidium iodide (CFDA/PI) staining and light microscopy, plasma membrane integrity using PI staining and a fluorometer, plasma membrane integrity using a resazurin reduction test, and sperm concentration were evaluated. In Exp. 2, the same tests as in Exp. 1 and a hypo-osmotic swelling test (HOST) using both light microscopy and a fluorometer were performed immediately after thawing and after a 3-h incubation. Statistical analysis was done separately to all stallions and to those having ≥ 20 mares; in addition, stallions with foaling rates < 60 or ≥ 60% were compared. In Exp. 1, progressive motility for all stallions after a 2 – 4-h incubation correlated with the foaling rate (correlation coefficients 0.39 – 0.51), (p < 0.05). In stallions with > 20 mares, the artificial insemination dose showed a correlation coefficient of -0.58 (p < 0.05). In Exp. 2, the HOST immediately after thawing showed a negative correlation with foaling rate (p < 0.05). No single test was consistently reliable for predicting the fertilizing capacity of semen, since the 2 experiments yielded conflicting results, although the same stallions sometimes participated in both. This shows the difficulty of frozen semen quality control in commercially produced stallion semen, and on the other hand, the difficulty of conducting fertility trials in horses
Baltic Ecological Recycling Agriculture and Society (BERAS project) - a case of Juva milk system
The aim of the study was to determine the potential, impact and prerequisites of localization and enhanced recycling in a rural food system, illustrated by the case of Juva milk. An interdisciplinary scenario based on the increase of local, organic milk to 50 % of milk comsumption was created and the sustainability was compared, on the basis of the statistics and data collected from the actors, with the present milk system
Dipolar coupling of nanoparticle-molecule assemblies: An efficient approach for studying strong coupling
Strong light-matter interactions facilitate not only emerging applications in quantum and non-linear optics but also modifications of properties of materials. In particular, the latter possibility has spurred the development of advanced theoretical techniques that can accurately capture both quantum optical and quantum chemical degrees of freedom. These methods are, however, computationally very demanding, which limits their application range. Here, we demonstrate that the optical spectra of nanoparticle-molecule assemblies, including strong coupling effects, can be predicted with good accuracy using a subsystem approach, in which the response functions of different units are coupled only at the dipolar level. We demonstrate this approach by comparison with previous time-dependent density functional theory calculations for fully coupled systems of Al nanoparticles and benzene molecules. While the present study only considers few-particle systems, the approach can be readily extended to much larger systems and to include explicit optical-cavity modes
Nutrient and energy potential for sustainable biorefineries based on wastes of agrifood systems: two regional cases
The aim of our study is to identify business models and opportunities with corporate social responsibility(CSR) presented by biorefineries based on wastes and return flows of agrifood systems. Two regional cases are explored and methods for generalisation are developed
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