251 research outputs found
Biological Activity of Hydrophilic Extract of Chlorella vulgaris Grown on Post-Fermentation Leachate from a Biogas Plant Supplied with Stillage and Maize Silage
Algae are employed commonly in cosmetics, food and pharmaceuticals, as well as in feed
production and biorefinery processes. In this study, post-fermentation leachate from a biogas plant
which exploits stillage and maize silage was utilized as a culture medium forChlorella vulgaris. The content
of polyphenols in hydrophilic extracts of the Chlorella vulgaris biomass was determined, and the extracts
were evaluated for their antioxidant activity (DPPH assay), antibacterial activity (against Escherichia coli,
Lactobacillus plantarum, Staphylococcus aureus, Staphylococcus epidermidis) and antifungal activity (against
Aspergillus niger, Candida albicans, Saccharomyces cerevisiae). The use of the post-fermentation leachate was
not found to affect the biological activity of the microalgae. The aqueous extract of Chlorella vulgaris
biomass was also observed to exhibit activity against nematodes. The results of this study suggest that
Chlorella vulgaris biomass cultured on post-fermentation leachate from a biogas plant can be successfully
employed as a source of natural antioxidants, food supplements, feed, natural antibacterial and antifungal
compounds, as well as in natural methods of plant protection
Subthreshold K+ production in deuteron and alpha induced nuclear reactions
Double differential cross sections have been measured for pi+ and K+ emitted
around midraidity in d+A and He+A collisions at a beam kinetic energy of 1.15
GeV/nucleon. The total pi+ yield increases by a factor of about 2 when using an
alpha projectile instead of a deuteron whereas the K+ yield increases by a
factor of about 4. According to transport calculations, the K+ enhancement
depends both on the number of hadron-hadron collisions and on the energy
available in those collisions: their center-of-mass energy increases with
increasing number of projectile nucleons
Production of Charged Pions, Kaons and Antikaons in Relativistic C+C and C+Au Collisions
Production cross sections of charged pions, kaons and antikaons have been
measured in C+C and C+Au collisions at beam energies of 1.0 and 1.8 AGeV for
different polar emission angles. The kaon and antikaon energy spectra can be
described by Boltzmann distributions whereas the pion spectra exhibit an
additional enhancement at low energies. The pion multiplicity per participating
nucleon M(pi+)/A_part is a factor of about 3 smaller in C+Au than in C+C
collisions at 1.0 AGeV whereas it differs only little for the C and the Au
target at a beam energy of 1.8 AGeV. The K+ multiplicities per participating
nucleon M(K+)/A_part are independent of the target size at 1 AGeV and at 1.8
AGeV. The K- multiplicity per participating nucleon M(K-)/A_part is reduced by
a factor of about 2 in C+Au as compared to C+C collisions at 1.8 AGeV. This
effect might be caused by the absorption of antikaons in the heavy target
nucleus. Transport model calculations underestimate the K-/K+ ratio for C+C
collisions at 1.8 AGeV by a factor of about 4 if in-medium modifications of K
mesons are neglected.Comment: 19 pages, 14 figures, accepted for publication in Eur. Phys. J.
Evidence for a Soft Nuclear Equation-of-State from Kaon Production in Heavy Ion Collisions
The production of pions and kaons has been measured in Au+Au collisions at
beam energies from 0.6 to 1.5 AGeV with the Kaon Spectrometer at SIS/GSI. The
K+ meson multiplicity per nucleon is enhanced in Au+Au collisions by factors up
to 6 relative to C+C reactions whereas the corresponding pion ratio is reduced.
The ratio of the K+ meson excitation functions for Au+Au and C+C collisions
increases with decreasing beam energy. This behavior is expected for a soft
nuclear equation-of-state.Comment: 14 pages, 2 figures, accepted for publication in Phys. Rev. Let
Enhanced Out-of-plane Emission of K+ Mesons observed in Au+Au Collisions at 1 AGeV
The azimuthal angular distribution of K+ mesons has been measured in Au + Au
collisions at 1 AGeV. In peripheral and semi-central collisions, K+ mesons
preferentially are emitted perpendicular to the reaction plane. The strength of
the azimuthal anisotropy of K+ emission is comparable to the one of pions. No
in-plane flow was found for K+ mesons near projectile and target rapidity.Comment: Accepted for publication in Phys. Rev.Let
Phenomenological analysis of K+ meson production in proton-nucleus collisions
Total and differential cross sections from literature, on the production of
K+ mesons in pA interactions at projectile energies between T=0.8 and 2.9 GeV,
covering the transition across the free nucleon-nucleon threshold at 1.58 GeV,
have been investigated. From the target-mass dependence of the production cross
sections no evidence for the expected change of the dominant reaction mechanism
from two-step to direct kaon production was found. At T=1.0 GeV the A
dependences of the total cross sections and of the most recent data from
COSY-Juelich, differential cross sections measured under forward angles, are
strongly different. The invariant K+ production cross sections show an overall
exponential scaling behavior with the squared four-momentum transfer between
the beam proton and the produced K+ meson for t< -0.05 GeV^2 independent of the
beam energy and emission angle. The data from COSY-Juelich reveal a strongly
different t dependence in the region of t>0 GeV^2. Further data at forward
angles and different beam energies should be taken in order to explore this
region of kinematically extreme conditions.Comment: 9 Pages, 11 Figure
Transnational higher education partnerships and the role of operational faculty members: developing an alternative theoretical approach for empirical research
For too long, transnational higher education (TNE) has been linked to discourse predominately focused upon strategic implementation, quality assurance and pedagogy. Whilst these aspects are important when designing and managing overseas provisions, there is a lack of research focusing on the social interactions that influence the pace and development of TNE partnerships. This gap is particularly evident at the operational phase of TNE partnerships. This conceptual article therefore offers an alternative way in which to research TNE partnerships, in relation to the interactions of faculty members delivering at the operational level. It provides an integrated theoretical framework, comprising of three different theoretical approaches in order to provide a conceptual tool in which to investigate and evaluate TNE partnership development. The article concludes that by understanding how relationships develop between faculty members tasked with delivering TNE, international partnerships can be significantly strengthened in terms of their progression and value
K Meson Production in the Proton-Proton Reaction at 3.67 GeV/c
The total cross section of the reaction has been determined
for proton--proton reactions with . This represents the
first cross section measurement of the channel near
threshold, and is equivalent to the inclusive cross section at
this beam momentum. The cross section determined at this beam momentum is about
a factor 20 lower than that for inclusive meson production at
the same CM energy above the corresponding threshold. This large difference in
the and meson inclusive production cross sections in proton-proton
reactions is in strong contrast to cross sections measured in sub-threshold
heavy ion collisions, which are similar in magnitude at the same energy per
nucleon below the respective thresholds.Comment: 12 pages, 3 figures Phys. Lett. B in prin
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