1,683 research outputs found
New high-performance liquid chromatography-dad method for analytical determination of arbutin and hydroquinone in rat plasma
Natural substances present in herbal preparations should be carefully used because they can give toxic or therapeutic effects despite of their amount or the way of administration. The safety of products of vegetable origin must be assessed before commercialisation by monitoring the active ingredients and their metabolites. This study was therefore designed to identify and quantify arbutin and its metabolite hydroquinone, naturally present in Arctostaphylos uva-ursi (L.) Spreng plant in rat plasma, after an acute and subacute administration of aqueous arbutin solution in Wistar rats. For this purpose a reversed-phase high-performance liquid chromatography coupled with photodiode array detection was developed to assess the pharmacokinetic of arbutin and hydroquinone in plasma of female rats treated with aqueous arbutin solutions. The detection (arbutin: 0.0617 µg/ml and hydroquinone 0.0120 µg/ml) and quantification (arbutin: 0.2060 µg/ml and hydroquinone: 0.0400 µg/ml) limits were determined. At the arbutin concentration level of 10.7 µg/ml repeatability was 13.33% and its recovery 93.4±6.93%, while at the hydroquinone concentration level of 10.6 µg/ml repeatability was 11.66% and its recovery 92.9±7.75%. Furthermore the method was fully validated and the obtained data indicate that the new method provides good performances
New XMM-Newton observation of the Phoenix cluster: properties of the cool core
(Abridged) We present a spectral analysis of a deep (220 ks) XMM-Newton
observation of the Phoenix cluster (SPT-CL J2344-4243), which we also combine
with Chandra archival ACIS-I data. We extract CCD and RGS X-ray spectra from
the core region to search for the signature of cold gas, and constrain the mass
deposition rate in the cooling flow which is thought to be responsible of the
massive star formation episode observed in the BCG. We find an average mass
deposition rate of /yr in the temperature range 0.3-3.0 keV from MOS data. A
temperature-resolved analysis shows that a significant amount of gas is
deposited only above 1.8 keV, while upper limits of the order of hundreds of
/yr can be put in the 0.3-1.8 keV temperature range. From pn data we
obtain /yr, and the
upper limits from the temperature-resolved analysis are typically a factor of 3
lower than MOS data. In the RGS spectrum, no line emission from ionization
states below Fe XXIII is seen above , and the amount of gas cooling
below keV has a best-fit value
/yr. In addition, our analysis of the FIR SED of the BCG based on
Herschel data provides /yr, significantly lower
than previous estimates by a factor 1.5. Current data are able to firmly
identify substantial amount of cooling gas only above 1.8 keV in the core of
the Phoenix cluster. While MOS data analysis is consistent with values as high
as within , pn data provide
yr at c.l. at temperature below 1.8 keV. At present, this
discrepancy cannot be explained on the basis of known calibration uncertainties
or other sources of statistical noise.Comment: A&A in press, typos corrected, revised text according to published
versio
Garlic (Allium spp.) viruses: detection, distribution and remediation attempts in a European garlic collection
Garlic is an important vegetable crop in numerous countries used as food and natural based medicine. Similar to the majority of vegetatively propagated plants, garlic may be affected by several viruses that can cause severe crop losses. The present study aimed to screen 105 garlic accessions (mother plants) from 5 European countries (Germany, Czech Republic, Poland, Italy, and France) for possible presence of Onion yellow dwarf virus (OYDV), Leek yellow stripe virus (LYSV), Garlic common latent virus (GCLV) and Shallot latent virus (SLV). The occurrence of three Allexiviruses (GarV-A, GarV-B and GarV-C) in mixed assays was also investigated. Meristem-tip culture assays were performed in order to attempt eradication of the studied viruses. Garlic viruses identification was made by ELISA and RT-PCR. ELISA outcomes showed that all 105 garlic accessions were infected by different virus combinations. The OYDV and LYSV were identified, by ELISA, in all countries at 96% and 88,6% respectively and by RT-PCR at 99% and 96%. Furthermore, GCLV and SLV were detected by ELISA in about 88% and by RT-PCR at 89% and 90%, respectively with the exception of the studied Allexiviruses which were not amplified by RT-PCR with ALLEX1/ALLEX2 primers. Smaller meristem size (0,3-1,5 mm) led to better virus elimination efficiency (29%) compared to 8% obtained for the larger size (2-2,5 mm). The outcomes were opposite (16% vs. 90%) for plants regeneration. Virus elimination efficiency was linked to the virus type, e.g., OYDV and LYSV were eradicated at 90% while GCLV and Allexiviruses were difficult to eliminate (57,4% and 55,6% of eradication). Given the economic relevance of garlic crops worldwide and the frequently reported incidence of viral infections, it is important to make virusfree germplasm available. Therefore, investigating the garlic germplasm sanitary status and constantly improving it is of crucial importance aiming to increase the overall garlic production
Intergalactic Photon Spectra from the Far IR to the UV Lyman Limit for and the Optical Depth of the Universe to High Energy Gamma-Rays
We calculate the intergalactic photon density as a function of both energy
and redshift for 0 < z < 6 for photon energies from .003 eV to the Lyman limit
cutoff at 13.6 eV in a Lambda-CDM universe with and
. Our galaxy evolution model gives results which are
consistent with Spitzer deep number counts and the spectral energy distribution
of the extragalactic background radiation. We use our photon density results to
extend previous work on the absorption of high energy gamma-rays in
intergalactic space owing to interactions with low energy photons and the 2.7 K
cosmic background radiation. We calculate the optical depth of the universe,
tau, for gamma-rays having energies from 4 GeV to 100 TeV emitted by sources at
redshifts from ~0 to 5. We also give an analytic fit with numerical
coefficients for approximating . As an example of the
application of our results, we calculate the absorbed spectrum of the blazar
PKS 2155-304 at z = 0.117 and compare it with the spectrum observed by the
H.E.S.S. air Cherenkov gamma-ray telescope array.Comment: final version to be published in Ap
Short-term effects of focal muscle vibration on motor recovery after acute stroke: a pilot randomized sham-controlled study
Repetitive focal muscle vibration (rMV) is known to promote neural plasticity and long-lasting motor recovery in chronic stroke patients. Those structural and functional changes within the motor network underlying motor recovery occur in the very first hours after stroke. Nonetheless, to our knowledge, no rMV-based studies have been carried out in acute stroke patients so far, and the clinical benefit of rMV in this phase of stroke is yet to be determined. The aim of this randomized double-blind sham-controlled study is to investigate the short-term effect of rMV on motor recovery in acute stroke patients. Out of 22 acute stroke patients, 10 were treated with the rMV (vibration group–VG), while 12 underwent the sham treatment (control group–CG). Both treatments were carried out for 3 consecutive days, starting within 72 h of stroke onset; each daily session consisted of three 10-min treatments (for each treated limb), interspersed with a 1-min interval. rMV was delivered using a specific device (Cro®System, NEMOCO srl, Italy). The transducer was applied perpendicular to the target muscle's belly, near its distal tendon insertion, generating a 0.2–0.5 mm peak-to-peak sinusoidal displacement at a frequency of 100 Hz. All participants also underwent a daily standard rehabilitation program. The study protocol underwent local ethics committee approval (ClinicalTrial.gov NCT03697525) and written informed consent was obtained from all of the participants. With regard to the different pre-treatment clinical statuses, VG patients showed significant clinical improvement with respect to CG-treated patients among the NIHSS (p < 0.001), Fugl-Meyer (p = 0.001), and Motricity Index (p < 0.001) scores. In addition, when the upper and lower limb scales scores were compared between the two groups, VG patients were found to have a better clinical improvement at all the clinical end points. This study provides the first evidence that rMV is able to improve the motor outcome in a cohort of acute stroke patients, regardless of the pretreatment clinical status. Being a safe and well-tolerated intervention, which is easy to perform at the bedside, rMV may represent a valid complementary non-pharmacological therapy to promote motor recovery in acute stroke patients
Star formation in the massive cluster merger Abell 2744
We present a comprehensive study of star-forming (SF) galaxies in the HST
Frontier Field recent cluster merger A2744 (z=0.308). Wide-field,
ultraviolet-infrared (UV-IR) imaging enables a direct constraint of the total
star formation rate (SFR) for 53 cluster galaxies, with SFR{UV+IR}=343+/-10
Msun/yr. Within the central 4 arcmin (1.1 Mpc) radius, the integrated SFR is
complete, yielding a total SFR{UV+IR}=201+/-9 Msun/yr. Focussing on obscured
star formation, this core region exhibits a total SFR{IR}=138+/-8 Msun/yr, a
mass-normalised SFR{IR} of Sigma{SFR}=11.2+/-0.7 Msun/yr per 10^14 Msun and a
fraction of IR-detected SF galaxies f{SF}=0.080(+0.010,-0.037). Overall, the
cluster population at z~0.3 exhibits significant intrinsic scatter in IR
properties (total SFR{IR}, Tdust distribution) apparently unrelated to the
dynamical state: A2744 is noticeably different to the merging Bullet cluster,
but similar to several relaxed clusters. However, in A2744 we identify a trail
of SF sources including jellyfish galaxies with substantial unobscured SF due
to extreme stripping (SFR{UV}/SFR{IR} up to 3.3). The orientation of the trail,
and of material stripped from constituent galaxies, indicates that the passing
shock front of the cluster merger was the trigger. Constraints on star
formation from both IR and UV are crucial for understanding galaxy evolution
within the densest environments.Comment: Accepted by MNRAS. 12 pages, 7 figures (high resolution versions of
Figs. 1 & 2 are available in the published PDF
Magnetic versus crystal field linear dichroism in NiO thin films
We have detected strong dichroism in the Ni x-ray absorption
spectra of monolayer NiO films. The dichroic signal appears to be very similar
to the magnetic linear dichroism observed for thicker antiferromagnetic NiO
films. A detailed experimental and theoretical analysis reveals, however, that
the dichroism is caused by crystal field effects in the monolayer films, which
is a non trivial effect because the high spin Ni ground state is not
split by low symmetry crystal fields. We present a practical experimental
method for identifying the independent magnetic and crystal field contributions
to the linear dichroic signal in spectra of NiO films with arbitrary
thicknesses and lattice strains. Our findings are also directly relevant for
high spin and systems such as LaFeO, FeO,
VO, LaCrO, CrO, and Mn manganate thin films
The XXL Survey: XII. Optical spectroscopy of X-ray-selected clusters and the frequency of AGN in superclusters
This article belongs to the first series of XXL publications. It presents
multifibre spectroscopic observations of three 0.55 sq.deg. fields in the XXL
Survey, which were selected on the basis of their high density of
X-ray-detected clusters. The observations were obtained with the
AutoFib2+WYFFOS (AF2) wide-field fibre spectrograph mounted on the 4.2m William
Herschel Telescope. The paper first describes the scientific rationale, the
preparation, the data reduction, and the results of the observations, and then
presents a study of active galactic nuclei (AGN) within three superclusters. We
obtained redshifts for 455 galaxies in total, 56 of which are counterparts of
X-ray point-like sources. We were able to determine the redshift of the merging
supercluster XLSSC-e, which consists of six individual clusters at z~0.43, and
we confirmed the redshift of supercluster XLSSC-d at z~0.3. More importantly,
we discovered a new supercluster, XLSSC-f, that comprises three galaxy clusters
also at z~0.3. We find a significant 2D overdensity of X-ray point-like sources
only around the supercluster XLSSC-f. This result is also supported by the
spatial (3D) analysis of XLSSC-f, where we find four AGN with compatible
spectroscopic redshifts and possibly one more with compatible photometric
redshift. In addition, we find two AGN (3D analysis) at the redshift of
XLSSC-e, but no AGN in XLSSC-d. Comparing these findings with the optical
galaxy overdensity we conclude that the total number of AGN in the area of the
three superclusters significantly exceeds the field expectations. The
difference in the AGN frequency between the three superclusters cannot be
explained by the present study because of small number statistics. Further
analysis of a larger number of superclusters within the 50 sq. deg. of the XXL
is needed before any conclusions on the effect of the supercluster environment
on AGN can be reached.Comment: 11 pages, published by A&
A Compact Solid State Detector for Small Angle Particle Tracking
MIDAS (MIcrostrip Detector Array System) is a compact silicon tracking
telescope for charged particles emitted at small angles in intermediate energy
photonuclear reactions. It was realized to increase the angular acceptance of
the DAPHNE detector and used in an experimental program to check the
Gerasimov-Drell-Hearn sum rule at the Mainz electron microtron, MAMI. MIDAS
provides a trigger for charged hadrons, p/pi identification and particle
tracking in the region 7 deg < theta < 16 deg. In this paper we present the
main characteristics of MIDAS and its measured performances.Comment: 13 pages (9 figures). Submitted to NIM
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