629 research outputs found
Surface magnetism in ZnO/Co3O4 mixtures
We recently reported the observation of room temperature ferromagnetism in
mixtures of ZnO and Co3O4 despite the diamagnetic and antiferromagnetic
character of these oxides respectively. Here we present a detailed study on the
electronic structure of this material in order to account for this unexpected
ferromagnetism. Electrostatic interactions between both oxides lead to a
dispersion of Co3O4 particles over the surface of ZnO larger ones. As a
consequence, the reduction of Co+3 to Co2+ at the particle surface takes place
as evidenced by XAS measurements and optical spectrocopy. This reduction allows
to xplain the observed ferromagnetic signal within the well established
theories of magnetism.Comment: Accepted in Journal of Applied Physic
Wide-Field Multi-Parameter FLIM: Long-Term Minimal Invasive Observation of Proteins in Living Cells.
Time-domain Fluorescence Lifetime Imaging Microscopy (FLIM) is a remarkable tool to monitor the dynamics of fluorophore-tagged protein domains inside living cells. We propose a Wide-Field Multi-Parameter FLIM method (WFMP-FLIM) aimed to monitor continuously living cells under minimum light intensity at a given illumination energy dose. A powerful data analysis technique applied to the WFMP-FLIM data sets allows to optimize the estimation accuracy of physical parameters at very low fluorescence signal levels approaching the lower bound theoretical limit. We demonstrate the efficiency of WFMP-FLIM by presenting two independent and relevant long-term experiments in cell biology: 1) FRET analysis of simultaneously recorded donor and acceptor fluorescence in living HeLa cells and 2) tracking of mitochondrial transport combined with fluorescence lifetime analysis in neuronal processes
When are active Brownian particles and run-and-tumble particles equivalent? Consequences for motility-induced phase separation
Active Brownian particles (ABPs, such as self-phoretic colloids) swim at
fixed speed along a body-axis that rotates by slow angular
diffusion. Run-and-tumble particles (RTPs, such as motile bacteria) swim with
constant \u until a random tumble event suddenly decorrelates the
orientation. We show that when the motility parameters depend on density
but not on , the coarse-grained fluctuating hydrodynamics of
interacting ABPs and RTPs can be mapped onto each other and are thus strictly
equivalent. In both cases, a steeply enough decreasing causes phase
separation in dimensions , even when no attractive forces act between
the particles. This points to a generic role for motility-induced phase
separation in active matter. However, we show that the ABP/RTP equivalence does
not automatically extend to the more general case of \u-dependent motilities
Radiation-Induced Leiomyosarcoma after Breast Cancer Treatment and TRAM Flap Reconstruction
The development of a radiation-induced sarcoma (RIS) in the post mastectomy thoracic treatment volume is an infrequent, but recognized, event. Its frequency is rising in relation with increasing survival of breast cancer patients treated with adjuvant radiation therapy, and is associated with poor prognosis despite treatment.
We present a case of leiomyosarcoma in a patient who underwent mastectomy followed by radiotherapy for invasive ductal carcinoma. A delayed TRAM flap reconstruction was performed 10 years after and a rapid growing mass under the reconstructed flap appeared, on routine follow-up, twenty years later. This report analyzes the diagnostic and therapeutic approach of patients with RIS
Periodic and Quasiperiodic Motion of an Elongated Microswimmer in Poiseuille Flow
We study the dynamics of a prolate spheroidal microswimmer in Poiseuille flow
for different flow geometries. When moving between two parallel plates or in a
cylindrical microchannel, the swimmer performs either periodic swinging or
periodic tumbling motion. Although the trajectories of spherical and elongated
swimmers are qualitatively similar, the swinging and tumbling frequency
strongly depends on the aspect ratio of the swimmer. In channels with reduced
symmetry the swimmers perform quasiperiodic motion which we demonstrate
explicitely for swimming in a channel with elliptical cross section
Cobalt (II) environment characterization in sol-gel thermochromic sensors
Optical absorption and magnetic properties of silica sol-gel monoliths doped with cobalt starting from different precursors and water/1-propanol molar ratios are investigated. Structural characterization of the sol-gel by X-ray absorption near-edge structure (XANES) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy corroborate, that oxidising state of cobalt is Co^(2+). Furthermore, the Co^(2+) first neighbors are O atoms displaying a temperature transition from octahedral to tetrahedral coordination. The doped monoliths show thermochromic sensor activity ranging from 10 to 50⁰ C, which is related to the environment of Co^(2+) ions. The magnetic susceptibility also varies with Co^(2+) ions environment due to changes in the orbital contribution to the magnetic moment. Thus, we achieve a better understanding about environment of the Co^(2+) ions in the gel matrix and explain their reversible temperature behaviour in spite of the rigid state of the host matrix
Estudio detallado de los efectos del acetato de hidrocortisona durante la gestación sobre el número de fetos y abortos en la rata
Se estudia la evolución del efecto de la administración de acetato de hidrocortisona (4mg/100 g. peso/día) a ratas sobre el número de fetos y abortos de la camada en los días 6, 9, 12, 14, 16, 18 y 21 de gestación. Se observa que el acetato de hidrocortisona disminuye el número de fetos vivos a partir del día 17 de tratamiento siendo la disminución más acusada en el día 21, en el que la diferencia respecto al grupo control es de un 25%. El acetato de hidrocortisona incrementa el porcentaje de ratas que presentan abortos en cualquiera de los periodos estudiados. Además en el día 14 el 22,2% de ratas inyectadas con acetato de hidrocortisona presentan abortos de la totalidad de sus fetos, hecho que nunca sucede en las ratas control. En el día 21 es más acusado el efecto de la hormona ya que mientras que las ratas testigo mantienen todos los fetos vivos, un 66% de ratas tratadas con cortisona siguen presentando abortos.The evolution of the effect of the administration of hydrocortisone aceta te (HA) (4mg/l00g weightlday) to the pregnant rat on the number of viable
and nonviable fetuses was studied on days 6, 9, 12, 14, 16, 18 and 21 of gesta tion .
. The administration of HA to pregnant rats reduced the number of live fe tuses starting on day 17 of treatment representing a loss of approximately
25% of the fetuses when they are compared with the control rats. High doses
of cortisone acetate were seen to increase the percentage of rats whose uterus
contained dead fetuses at any given period of study. On day 14 more over the
entire litter was found to have died in utero in 22,2% of all cortisol injected rats, a finding which never occurred in controls. The effects of cortisol were
most in evidence on day 21, when all fetuses were viable in controls as opposed to hormone-treated rats, 66% of which were found to contain nonviable
fetuses
Estudio detallado de los efectos del acetato de hidrocortisona durante la gestación sobre el número de fetos y abortos en la rata
The evolution of the effect of the administration of hydrocortisone acetate (HA) (4mg/100g weightlday) to the pregnant rat on the number of viable and nonviable fetuses was studied on days 6, 9, 12, 14, 16, 18 and 21 of gestation. The administration of HA to pregnant rats reduced the number of live fetuses starting on day 17 of treatment representing a loss of approximately 25% of the fetuses when they are compared with the control rats. High doses of cortisone acetate were seen to increase the percentage of rats whose uterus contained dead fetuses at any given period of study. On day 14 more over the entire litter was found to have died in utero in 22,2% of all cortisol injected rats, a finding which never occurred in controls. The effects of cortisol were most in evidence on day 21, when all fetuses were viable in controls as opposed to hormone-treated rats, 66% of which were found to contain nonviable fetuses.Se estudia la evolución del efecto de la administración de acetato de hidrocortisona (4mg/100 g. peso/día) a ratas sobre el número de fetos y abortos de la camada en los días 6, 9, 12, 14, 16, 18 y 21 de gestación. Se observa que el acetato de hidrocortisona disminuye el número de fetos vivos a partir del día 17 de tratamiento siendo la disminución más acusada en el día 21, en el que la diferencia respecto al grupo control es de un 25%. El acetato de hidrocortisona incrementa el porcentaje de ratas que presentan abortos en cualquiera de los periodos estudiados. Además en el día 14 el 22,2% de ratas inyectadas con acetato de hidrocortisona presentan abortos de la totalidad de sus fetos, hecho que nunca sucede en las ratas control. En el día 21 es más acusado el efecto de la hormona ya que mientras que las ratas testigo mantienen todos los fetos vivos, un 66% de ratas tratadas con cortisona siguen presentando abortos
Role of small Rhizaria and diatoms in the pelagic silica production of the Sourther Ocean
We examined biogenic silica production and elementary composition (biogenic Si, particulate organic carbon and particulate organic nitrogen) of Rhizaria and diatoms in the upper 200 m along a transect in the Southwest Pacific sector of the Southern Ocean during austral summer (January–February 2019). From incubations using the 32Si radioisotope, silicic acid uptake rates were measured at 15 stations distributed in the Polar Front Zone, the Southern Antarctic Circumpolar Current and the Ross Sea Gyre. Rhizaria cells are heavily silicified (up to 7.6 nmol Si cell−1), displaying higher biogenic Si content than similar size specimens found in other areas of the global ocean, suggesting a higher degree of silicification of these organisms in the silicic acid rich Southern Ocean. Despite their high biogenic Si and carbon content, the Si/C molar ratio (average of 0.05 ± 0.03) is quite low compared to that of diatoms and relatively constant regardless of the environmental conditions. The direct measurements of Rhizaria's biogenic Si production (0.8–36.8 μmol Si m−2 d−1) are of the same order of magnitude than previous indirect estimations, confirming the importance of the Southern Ocean for the global Rhizaria silica production. However, diatoms largely dominated the biogenic Si standing stock and production of the euphotic layer, with low rhizarians' abundances and biogenic Si production (no more than 1%). In this manuscript, we discuss the Antarctic paradox of Rhizaria, that is, the potential high accumulation rates of biogenic Si due to Rhizaria in siliceous sediments despite their low production rates in surface waters.Versión del editor3,38
- …