1,300 research outputs found
Mitochondrial DNA lineages of Italian Giara and Sarcidano horses
Giara and Sarcidano are 2 of the 15 extant native Italian horse breeds with limited dispersal capability that originated from a larger number of individuals. The 2 breeds live in two distinct isolated locations on the island of Sardinia. To determine the genetic structure and evolutionary history of these 2 Sardinian breeds, the first hypervariable segment of the mitochondrial DNA (mtDNA) was sequenced and analyzed in 40 Giara and Sarcidano horses and compared with publicly available mtDNA data from 43 Old World breeds. Four different analyses, including genetic distance, analysis of molecular variance, haplotype sharing, and clustering methods, were used to study the genetic relationships between the Sardinian and other horse breeds. The analyses yielded similar results, and the FST values indicated that a high percentage of the total genetic variation was explained by between-breed differences. Consistent with their distinct phenotypes and geographic isolation, the two Sardinian breeds were shown to consist of 2 distinct gene pools that had no gene flow between them. Giara horses were clearly separated from the other breeds examined and showed traces of ancient separation from horses of other breeds that share the same mitochondrial lineage. On the other hand, the data from the Sarcidano horses fit well with variation among breeds from the Iberian Peninsula and North-West Europe: genetic relationships among Sarcidano and the other breeds are consistent with the documented history of this breed
Increasing the agricultural sustainability of closed agrivoltaic systems with the integration of vertical farming: A case study on baby-leaf lettuce
The photovoltaic (PV) greenhouses are closed agrivoltaic (CA) systems that allow the production of energy and food on the same land, but may result in a yield reduction when the shading of the PV panels is excessive. Adopting innovative cropping systems can increase the yield of the CA area, generating a more productive and sustainable agrosystem. In this case study we quantified the increase of land productivity derived from the integration of an experimental vertical farm (VF) for baby leaf lettuce inside a pre-existing commercial CA. The mixed system increased the yield by 13 times compared to the CA and the average LER was 1.31, but only 12 % of the energy consumption was covered by the CA energy. To achieve the energy self-sufficiency and avoid the related CO2 emissions, the VF area should not exceed 7–18 % of the CA area, depending on the PV energy yield and the daily light integral (DLI) of the LED lighting, meaning a land consumption from 5 to 14 times higher than the VF area. The support of the PV energy was essential for the profitability of the VFCA. Design features and solutions were proposed to increase the agronomic and economic sustainability of the VFCA. The VFs can be considered a possible answer for the reconversion of the actual underutilized CAs with high PV cover ratios into productive and efficient cropping systems, but a trade-off between energy production and land consumption should be identified to ensure an acceptable environmental sustainability of the mixed system
Catching VY Sculptoris in a low state
Context. In the context of a large campaign to determine the system
parameters of high mass transfer cataclysmic variables, we found VY Scl in a
low state in 2008. Aims. Making use of this low state, we study the stellar
components of the binary with little influence of the normally dominating
accretion disc. Methods. Time-resolved spectroscopy and photometry of VY Scl
taken during the low state are presented. We analysed the light-curve and
radial velocity curve and use time-resolved spectroscopy to calculate Doppler
maps of the dominant emission lines. Results. The spectra show narrow emission
lines of Halpha, Hbeta, HeI, NaID, and FeII, as well as faint TiO absorption
bands that trace the motion of the irradiated secondary star, and Halpha and
HeI emission line wings that trace the motion of the white dwarf. From these
radial velocities, we find an orbital period of 3.84 h, and put constraints on
binary parameters such as the mass ratio M2/M1 of 0.43 and the inclination of
15 deg. With a secondary's mass between 0.3 and 0.35 Msol, we derive the mass
for the white dwarf as M1 = 0.6-0.1 Msol.Comment: 8 pages, 9 figures, accepted for publication in A&
Formation of quantum dots in the potential fluctuations of InGaAs heterostructures probed by scanning gate microscopy
The disordered potential landscape in an InGaAs/InAlAs two-dimensional
electron gas patterned into narrow wires is investigated by means of scanning
gate microscopy. It is found that scanning a negatively charged tip above
particular sites of the wires produces conductance oscillations that are
periodic in the tip voltage. These oscillations take the shape of concentric
circles whose number and diameter increase for more negative tip voltages until
full depletion occurs in the probed region. These observations cannot be
explained by charging events in material traps, but are consistent with Coulomb
blockade in quantum dots forming when the potential fluctuations are raised
locally at the Fermi level by the gating action of the tip. This interpretation
is supported by simple electrostatic simulations in the case of a disorder
potential induced by ionized dopants. This work represents a local
investigation of the mechanisms responsible for the disorder-induced
metal-to-insulator transition observed in macroscopic two-dimensional electron
systems at low enough density
Scanning Gate Spectroscopy of transport across a Quantum Hall Nano-Island
We explore transport across an ultra-small Quantum Hall Island (QHI) formed
by closed quan- tum Hall edge states and connected to propagating edge channels
through tunnel barriers. Scanning gate microscopy and scanning gate
spectroscopy are used to first localize and then study a single QHI near a
quantum point contact. The presence of Coulomb diamonds in the spectroscopy
con- firms that Coulomb blockade governs transport across the QHI. Varying the
microscope tip bias as well as current bias across the device, we uncover the
QHI discrete energy spectrum arising from electronic confinement and we extract
estimates of the gradient of the confining potential and of the edge state
velocity.Comment: 13 pages, 3 figure
Scanning-gate microscopy of semiconductor nanostructures: an overview
This paper presents an overview of scanning-gate microscopy applied to the
imaging of electron transport through buried semiconductor nanostructures.
After a brief description of the technique and of its possible artifacts, we
give a summary of some of its most instructive achievements found in the
literature and we present an updated review of our own research. It focuses on
the imaging of GaInAs-based quantum rings both in the low magnetic field
Aharonov-Bohm regime and in the high-field quantum Hall regime. In all of the
given examples, we emphasize how a local-probe approach is able to shed new, or
complementary, light on transport phenomena which are usually studied by means
of macroscopic conductance measurements.Comment: Invited talk by SH at 39th "Jaszowiec" International School and
Conference on the Physics of Semiconductors, Krynica-Zdroj, Poland, June 201
Introducing 12 new dyes for use with oligonucleotide functionalised silver nanoparticles for DNA detection with SERS
Oligonucleotide functionalised metallic nanoparticles (MNPs) have been shown to be an effective tool in the detection of disease-specific DNA and have been employed in a number of diagnostic assays. The MNPs are also capable of facilitating surface enhanced Raman scattering (SERS) enabling detection to become highly sensitive. Herein we demonstrate the expansion of the range of specific SERS-active oligonucleotide MNPs through the use of 12 new Raman-active monomethine and trimethine chalcogenopyrylium and benzochalcogenopyrylium derivatives. This has resulted in an increased ability to carry out multiplexed analysis beyond the current small pool of resonant and non-resonant Raman active molecules, that have been used with oligonucleotide functionalised nanoparticles. Each dye examined here contains a variation of sulphur and selenium atoms in the heterocyclic core, together with phenyl, 2-thienyl, or 2-selenophenyl substituents on the 2,2’,6, and 6’ positions of the chalcogenopyrylium dyes and 2 and 2’ positions of the benzochalcogenopyrylium dyes. The intensity of SERS obtained from each dye upon conjugate hybridisation with a complementary single stranded piece of DNA was explored. Differing concentrations of each dye (1000, 3000, 5000 and 7000 equivalents per NP-DNA conjugate) were used to understand the effects of Raman reporter coating on the overall Raman intensity. It was discovered that dye concentration did not affect the target/control ratio, which remained relatively constant throughout and that a lower concentration of Raman reporter was favourable in order to avoid NP instability. A relationship between the dye structure and SERS intensity was discovered, leaving scope for future development of specific dyes containing substituents favourable for discrimination in a multiplex by SERS. Methine dyes containing S and Se in the backbone and at least 2 phenyls as substituents give the highest SERS signal following DNA-induced aggregation. Principal component analysis (PCA) was performed on the data to show differentiation between the dye classes and highlight possible future multiplexing capabilities of the 12 investigated dyes
Characterisation and application of glycanases secreted by aspergillus terreus CCMI 498 and trichoderma viride CCMI 84 for enzymatic deinking of mixed office wastepaper
Two enzymatic extracts obtained from xylan-grown Aspergillus terreus CCMI 498 and cellulose-grown Trichoderma
viride CCMI 84 were characterised for different glycanase activities. Both strains produce extracellular endoxylanase
and endoglucanase enzymes. The enzymes optimal activity was found in the temperature range of 45-60 ºC.
Endoglucanase systems show identical activity profiles towards temperature, regardless of the strain and inducing
substrate. Conversely, the endoxylanases produced by both strains showed maximal activity at different pH values
(from 4.5 to 5.5), being the more acidic xylanase produced by T. viride grown on cellulose. The endoglucanase activities
have an optimum pH at 4.5-5.0. The endoxylanase and endoglucanase activities exhibited high stability at 50 ºC and
pH 5.0. Mannanase, β-xylosidase, and amylase activities were also found, being the first two activities only present for
T. viride extract. These two enzymatic extracts were used for mixed office wastepaper (MOW) deinking. When the
enzymatic extract from T. viride was used, a further increase of 24% in ink removal was obtained by comparison with
the control. Both enzymes contributed to the improvement of the paper strength properties and the obtained results
clearly indicate that the effective use of enzymes for deinking can also contribute to the pulp and paper properties
improvement.PRAXIS/BIO/1133/95.
BIC/3087/96, BD/3253/96
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