2,963 research outputs found
Synthesis and Applications of Mutimodal Hybrid Albumin Nanoparticles for Chemotherapeutic Drug Delivery and Phototherml Therapy Platforms
Progress has been made in using human serum albumin nanoparticles (HSAPs) as carrier systems for targeted treatment of cancer. Human serum albumin (HSA), the most abundant human blood protein, can form HSAPs via a desolvation and crosslinking method, with the size of the HSAPs having crucial importance for drug loading and in vivo performance. Gold nanoparticles have also gained medicinal attention due to their ability to absorb near-infrared (NIR) light. These relatively non-toxic particles offer combinational therapy via imaging and photothermal therapy (PPTT) capabilities.
A desolvation and crosslinking approach was employed to encapsulate gold nanoparticles (AuNPs), hollow gold nanoshells (AuNSs), and gold nanorods (AuNRs), into efficiently sized HSAPs for future tumor heat ablation via PPTT. The AuNR-HSAPs, AuNP-HSAPs and AuNS-HSAPs had average particle diameters of 222 ± 5, 195 ± 9 and 156 ± 15, respectively.
We simultaneously encapsulated AuNRs and the anticancer drug paclitaxel (PAC), forming PAC-AuNR-HSAPs with overall average particle size of 299 ± 6 nm. Loading of paclitaxel into PAC-AuNR-HSAPs reached 3μg PAC/mg HSA. PAC-AuNR-HSAPs experienced photothermal heating of 46 ˚C after 15 minutes of NIR laser exposure; the temperature necessary to cause severe cellular hyperthermia. There was a burst release of paclitaxel up to 188 ng caused by the irradiation session, followed by a temporal drug release.
AuNR-HSAPs were tested for ablation of renal cell carcinoma using NIR irradiation in vitro. Particles created with the same amount of AuNRs, but varying HSA (1, 5 or 20 mg) showed overall particle size diameters 409 ± 224, 294 ± 83 and 167 ± 4 nm, respectively. Increasing HSAPs causes more toxicity under non-irradiated treatment conditions: AuNR-HSAPs with 20 mg versus 5 mg HSA caused cell viability of 64.5% versus 87%, respectively. All AuNR-HSAPs batches experienced photothermal heating above 42 ˚C. Coumarin-6, was used to visualize the cellular uptake of AuNR-HSAPs via fluorescence microscopy.
Finally, camptothecin (CPT) an antineoplastic agent and BACPT (7-butyl-10-aminocamptothecin) were loaded into HSAPs to combat their aqueous insolubility. BACPT-HSAPs loaded up to 5.25 micrograms BACPT/ mg of HSA. CPT encapsulation could not be determined. BACPT-HSAPs and CPT-HSAPs showed cytotoxicity to human sarcoma cells in vitro
Gravitational radiation from pulsar glitches
The nonaxisymmetric Ekman flow excited inside a neutron star following a
rotational glitch is calculated analytically including stratification and
compressibility. For the largest glitches, the gravitational wave strain
produced by the hydrodynamic mass quadrupole moment approaches the sensitivity
range of advanced long-baseline interferometers. It is shown that the
viscosity, compressibility, and orientation of the star can be inferred in
principle from the width and amplitude ratios of the Fourier peaks (at the spin
frequency and its first harmonic) observed in the gravitational wave spectrum
in the plus and cross polarizations. These transport coefficients constrain the
equation of state of bulk nuclear matter, because they depend sensitively on
the degree of superfluidity.Comment: 28 page
Nonadiabatic charged spherical evolution in the postquasistatic approximation
We apply the postquasistatic approximation, an iterative method for the
evolution of self-gravitating spheres of matter, to study the evolution of
dissipative and electrically charged distributions in General Relativity. We
evolve nonadiabatic distributions assuming an equation of state that accounts
for the anisotropy induced by the electric charge. Dissipation is described by
streaming out or diffusion approximations. We match the interior solution, in
noncomoving coordinates, with the Vaidya-Reissner-Nordstr\"om exterior
solution. Two models are considered: i) a Schwarzschild-like shell in the
diffusion limit; ii) a Schwarzschild-like interior in the free streaming limit.
These toy models tell us something about the nature of the dissipative and
electrically charged collapse. Diffusion stabilizes the gravitational collapse
producing a spherical shell whose contraction is halted in a short
characteristic hydrodynamic time. The streaming out radiation provides a more
efficient mechanism for emission of energy, redistributing the electric charge
on the whole sphere, while the distribution collapses indefinitely with a
longer hydrodynamic time scale.Comment: 11 pages, 16 Figures. Accepted for publication in Phys Rev
Algoritmos paralelos para la resolución de ecuaciones diferenciales ordinarias mediante OpenMP
Proceeding of: XIV Jornadas de Paralelismo, Leganés, Madrid (Spain), 15-17, septiembre, 2003En los últimos años está adquiriendo un gran auge el estudio de los métodos numéricos para la resolución Ecuaciones Diferenciales Ordinarias (ODE’s). Muchos de los métodos numéricos existentes se basan en la aproximación de un modelo continuo mediante un modelo discreto y el cálculo de una solución aproximada en un conjunto finito de puntos. En [1] se presenta una nueva aproximación al cálculo de ODE’s donde la principal aportación pasa por permitir una solución del problema independientemente de que el Jacobiano sea o no invertible. En el presente trabajo se presenta un nuevo algoritmo basado en [1] que permite la resolución de ODE’s. Además, se ha llevado a cabo una implementación paralela sobre arquitecturas de memoria compartida de dicho algoritmo. Tanto el algoritmo secuencial como el algoritmo paralelo desarrollado se han implementado utilizando librerías estándar tanto en el cómputo como en la comunicación en aras de obtener portabilidad, robustez y eficiencia
Buds, main reserve of yeasts between vegetative and reproductive aerial organs of Vitis vinifera var. Malbec.
El objetivo de esta investigación fue suministrar
nueva evidencia acerca del modelo
de permanencia de las levaduras en el ciclo
natural de la vid. Se efectuó la observación, la
medición del número de levaduras y la descripción
morfológica de los diferentes órganos
aéreos de la vid. Se procedió a la recolección
aséptica de muestras a campo, en yema en
actividad, yema en reposo, hoja joven, hoja
adulta, ritidomis, zarcillo, capullo floral, flor y
fruto. Los resultados revelaron dos momentos
de máxima población de levaduras: en yema
cerrada a fines de otoño y en yema terminal
abierta a mediados de verano. La evolución
de las levaduras en función de la superficie
del fruto mostró poca relación entre ambas
variables, por lo que el valor a considerar sería
la cantidad de levaduras por baya como
unidad. La ritidomis exhibió valores muy uniformes
a lo largo del ciclo vegetativo, asumiendo
desde esta perspectiva el papel de
reservorio de moderada importancia.The objective of this investigation was to
provide new evidence about the model of
permanence of yeasts of the grapevine in the
natural cycle. It was carried out the observation,
measurement of number and morphologic
description of different aerial organs from
the grapevine. It was come to the aseptic
harvesting from samples in field of bud in
activity, bud in rest, young leaf, adult leaf, bark,
tendril, flower bud, flower, fruit. The results
revealed two moments of maximum population
of yeasts: in closed bud by the end of autumn
and opened terminal bud in the middle of
summer. The evolution of yeasts in the fruit
referred to the surface of the berry showed
little relation between both variables, whereas
the value to consider would be the amount of
yeasts by berry as unit. Bark displayed very
uniform values throughout the vegetative
cycle, assuming from this perspective the role
of reserve of moderate importance.Fil: Lúquez Bibiloni, Claudia V..
Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias BiológicasFil: Formento, Juan Carlos.
Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Enológicas y AgroalimentariasFil: Díaz Peralta, Eduardo.
Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Enológicas y Agroalimentaria
Spin polarization induced by decoherence in a tunneling one-dimensional Rashba model
Basic questions on the nature of spin polarization in two terminal systems
and the way in which decoherence breaks Time-Reversal Symmetry (TRS) are
analyzed. We exactly solve several one-dimensional models of tunneling
electrons and show the interplay of spin precession and decay of the
wavefunction in either a U(1) magnetic field or an effective Spin-Orbit (SO)
magnetic field. Spin polarization is clearly identified as the emergence of a
spin component parallel to either magnetic field. We show that Onsager's
reciprocity is fulfilled when time reversal symmetry is present and no spin
polarization arises, no matter the barrier parameters or the SO strength.
Introducing a Buttiker's decoherence probe, that preserves unitarity of time
evolution, we show that breaking of TRS results in a strong spin polarization
for realistic SO, and barrier strengths. We discuss the significance of these
results as a very general scenario for the onset of the Chiral-Induced Spin
Selectivity effect (CISS), now possibly matching experiments in a quantitative
manner.Comment: 24 pages, 14 figure
SSTAR Users Manual
There are four objective functions available to date (11/86), these include 1) maximimize total regional groundwater withdrawl. 2) minimize total coat of satisfying regional needs. and 3) maximize the sum of selected local withdrawls. and 4) maximize the present value of total net economic return
Avalanche dynamics of radio pulsar glitches
We test statistically the hypothesis that radio pulsar glitches result from
an avalanche process, in which angular momentum is transferred erratically from
the flywheel-like superfluid in the star to the slowly decelerating, solid
crust via spatially connected chains of local, impulsive, threshold-activated
events, so that the system fluctuates around a self-organised critical state.
Analysis of the glitch population (currently 285 events from 101 pulsars)
demonstrates that the size distribution in individual pulsars is consistent
with being scale invariant, as expected for an avalanche process. The
waiting-time distribution is consistent with being exponential in seven out of
nine pulsars where it can be measured reliably, after adjusting for
observational limits on the minimum waiting time, as for a constant-rate
Poisson process. PSR J05376910 and PSR J08354510 are the exceptions;
their waiting-time distributions show evidence of quasiperiodicity. In each
object, stationarity requires that the rate equals , where is the angular acceleration of the
crust, is the mean glitch size, and is the
relative angular acceleration of the crust and superfluid. There is no evidence
that changes monotonically with spin-down age. The rate distribution
itself is fitted reasonably well by an exponential for . For , its exact form is unknown; the
exponential overestimates the number of glitching pulsars observed at low
, where the limited total observation time exercises a selection bias.Comment: Accepted for publication in the Astrophysical Journa
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