8,716 research outputs found
Photoluminescence Stokes shift and exciton fine structure in CdTe nanocrystals
The photoluminescence spectra of spherical CdTe nanocrystals with zincblende
structure are studied by size-selective spectroscopic techniques. We observe a
resonant Stokes shift of 15 meV when the excitation laser energy is tuned to
the red side of the absorption band at 2.236 eV. The experimental data are
analyzed within a symmetry-based tight-binding theory of the exciton spectrum,
which is first shown to account for the size dependence of the fundamental gap
reported previously in the literature. The theoretical Stokes shift presented
as a function of the gap shows a good agreement with the experimental data,
indicating that the measured Stokes shift indeed arises from the electron-hole
exchange interaction.Comment: 8 pages, 4 figures, LaTe
Influence of Thermal and Magnetic History on Direct DTad Measurements of Ni49+xMn36-xIn15 Heusler Alloys
In the present work, using Heusler Ni49+xMn36-xIn15 (with x = 0 and 0.5) alloys, it is
shown that the choice of the appropriate measurement protocol (erasing the prior state of the
sample in between experiments) in DTad first shot characterization is crucial for obtaining reliable
results. Unlike indirect measurements, for which incorrect protocols produce overestimates of the
characteristics of the material, erroneous direct measurements underestimate DTad in the region close
to its first order phase transition. The error in DTad is found to be dependent on the temperature step
used, being up to ~40% underestimation, including a slight shift in its peak temperature.AEI/FEDER-UE (project MAT-2016-77265-R)US Army Research Laboratory W911NF-19-2-021
CVD of CrO2: towards a lower temperature deposition process
We report on the synthesis of highly oriented a-axis CrO2 films onto (0001)
sapphire by atmospheric pressure CVD from CrO3 precursor, at growth
temperatures down to 330 degree Celsius, i.e. close to 70 degrees lower than in
published data for the same chemical system. The films keep the high quality
magnetic behaviour as those deposited at higher temperature, which can be
looked as a promising result in view of their use with thermally sensitive
materials, e.g. narrow band gap semiconductors.Comment: 13 pages, 4 figure
Computational Modeling of Single-Cell Migration::The Leading Role of Extracellular Matrix Fibers
Cell migration is vitally important in a wide variety of biological contexts ranging from embryonic development and wound healing to malignant diseases such as cancer. It is a very complex process that is controlled by intracellular signaling pathways as well as the cell's microenvironment. Due to its importance and complexity, it has been studied for many years in the biomedical sciences, and in the last 30 years it also received an increasing amount of interest from theoretical scientists and mathematical modelers. Here we propose a force-based, individual-based modeling framework that links single-cell migration with matrix fibers and cell-matrix interactions through contact guidance and matrix remodelling. With this approach, we can highlight the effect of the cell's environment on its migration. We investigate the influence of matrix stiffness, matrix architecture, and cell speed on migration using quantitative measures that allow us to compare the results to experiments
recent developments in cancer nanomedicine
Since decades, conventional diagnosis and treatment strategies for cancer have been practiced widely despite their expensive and time-consuming process. These conventional contrast and therapeutic agents suffer from various side-effects such as low radiodensity and image resolution, rapid clearance, non-specific biodistribution, poor tumor accumulation, high-dose and multiple-dose requirements, nephrotoxicity, uncontrolled exposure of high electromagnetic radiations, whole-body scans, and so on. Therefore, nanosized imaging and therapeutic probes have been proposed recently owing to their promising efficacy and negligible side-effects. However, these nanoplatforms are struggling deeply to find their clinical translational relevance. Integrating targeting ligands with diagnostic and therapeutic agents within a single system at the nanoscale resulted in localized nanotheranostics. Furthermore, the conceptualized nanotheranostics has been recognized as a clinical ‘weapon’ for localized cancer nanomedicine. In this review, we have covered a wide spectrum of recent developments in cancer nanotheranostics. Numerous examples of functional nanohybrids and clinical relevant materials with their multimode imaging and therapeutics have been addressed here. On the other hand, the importance of combination therapies, imaging-guided tumor regression, deep tissue visualization, localized diagnosis and tumor ablation, manipulation of the tumor microenvironment, and so on have been discussed here. Overall, localized and stimuli responsive nanosized multifunctional platforms have proved their superiority over conventional diagnosis and therapies.publishersversionpublishe
Field dependence of the magnetocaloric effect in Gd and (Er 1-xDyx)Al2: Does a universal curve exist?
The field dependence of the magnetic entropy change of ferromagnetic lanthanide- based materials has been studied. The recently proposed master curve for the field dependence of the magnetocaloric effect of Fe-based amorphous alloys can also be constructed for these lanthanide-based crystalline materials, suggesting a universal behavior. The exponent n controlling the field dependence of the magnetic entropy change can be used for the interpretation of results in the case of multiple magnetic ordering phenomena
Influence of Ge addition on the magnetocaloric effect of a Co-containing Nanopermtype alloy.
The influence of the partial substitution of B by Ge on the magnetocaloric response of
Fe78Co5Zr6B10Cu1 is studied. Ge addition produces a reduction in the temperature at which the peak
entropy change takes place, as well as a slight decrease in the magnitude of the peak, SM
pk . The
refrigerant capacity, RC, and its field dependence is also analyzed: although Ge addition increases
RC of the Co-containing alloy, the largest RC value corresponds to the Co- and Ge-free alloy. This
will be discussed on the basis of the recently proposed universal curve for the magnetic entropy
change, which is also followed by the FeZrBCu Co,Ge alloy series
Multi-scale modelling of the dynamics of cell colonies:insights into cell-adhesion forces and cancer invasion from in silico simulations
Studying the biophysical interactions between cells is crucial to understanding how normal tissue develops, how it is structured and also when malfunctions occur. Traditional experiments try to infer events at the tissue level after observing the behaviour of and interactions between individual cells. This approach assumes that cells behave in the same biophysical manner in isolated experiments as they do within colonies and tissues. In this paper, we develop a multi-scale multi-compartment mathematical model that accounts for the principal biophysical interactions and adhesion pathways not only at a cell-cell level but also at the level of cell colonies (in contrast to the traditional approach). Our results suggest that adhesion/separation forces between cells may be lower in cell colonies than traditional isolated single-cell experiments infer. As a consequence, isolated single-cell experiments may be insufficient to deduce important biological processes such as single-cell invasion after detachment from a solid tumour. The simulations further show that kinetic rates and cell biophysical characteristics such as pressure-related cell-cycle arrest have a major influence on cell colony patterns and can allow for the development of protrusive cellular structures as seen in invasive cancer cell lines independent of expression levels of pro-invasion molecules.Publisher PDFPeer reviewe
- …