1,626 research outputs found
Polarization-selective excitation of N-V centers in diamond
The nitrogen-vacancy (N-V) center in diamond is promising as an electron spin
qubit due to its long-lived coherence and optical addressability. The ground
state is a spin triplet with two levels () degenerate at zero
magnetic field. Polarization-selective microwave excitation is an attractive
method to address the spin transitions independently, since this allows
operation down to zero magnetic field. Using a resonator designed to produce
circularly polarized microwaves, we have investigated the polarization
selection rules of the N-V center. We first apply this technique to N-V
ensembles in [100] and [111]-oriented samples. Next, we demonstrate an imaging
technique, based on optical polarization dependence, that allows rapid
identification of the orientations of many single N-V centers. Finally, we test
the microwave polarization selection rules of individual N-V centers of known
orientation
Enzymatic synthesis of structured lipids from liquid and fully hydrogenated high oleic sunflower oil
sem informaçãoStructured lipids (SL) were synthesized via enzymatic (EI) and chemical interesterification of high oleic sunflower oil (SO) and fully hydrogenated high oleic SO with Lipozyme TL IM (Thermomyces lanuginose) for 3 h at 70°C, 300 rpm. Reaction showed change211702716sem informaçãosem informaçãosem informaçã
Dynamics of a Bose-Einstein condensate in a symmetric triple-well trap
We present a complete analysis of the dynamics of a Bose-Einstein condensate
trapped in a symmetric triple-well potential. Our classical analogue treatment,
based on a time-dependent variational method using SU(3) coherent states,
includes the parameter dependence analysis of the equilibrium points and their
local stability, which is closely related to the condensate collective
behaviour. We also consider the effects of off-site interactions, and how these
"cross-collisions" may become relevant for a large number of trapped bosons.
Besides, we have shown analytically, by means of a simple basis transformation
in the single-particle space, that an integrable sub-regime, known as
twin-condensate dynamics, corresponds in the classical phase space to invariant
surfaces isomorphic to the unit sphere. However, the quantum dynamics preserves
the twin-condensate defining characteristics only partially, thus breaking the
invariance of the associated quantum subspace. Moreover, the periodic geometry
of the trapping potential allowed us to investigate the dynamics of finite
angular momentum collective excitations, which can be suppressed by the
emergence of chaos. Finally, using the generalized purity associated to the
su(3) algebra, we were able to quantify the dynamical classicality of a quantum
evolved system, as compared to the corresponding classical trajectory.Comment: 22 pages, 10 figure
Multifunctional Hybrid MoS2-PEGylated/Au Nanostructures with Potential Theranostic Applications in Biomedicine
In this work, flower-like molybdenum disulfide (MoS2) microspheres were produced with polyethylene glycol (PEG) to form MoS2-PEG. Likewise, gold nanoparticles (AuNPs) were added to form MoS2-PEG/Au to investigate its potential application as a theranostic nanomaterial. These nanomaterials were fully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), photoelectron X-ray spectroscopy (XPS), Fourier-transformed infrared spectroscopy (FTIR), cyclic voltammetry and impedance spectroscopy. The produced hierarchical MoS2-PEG/Au microstructures showed an average diameter of 400 nm containing distributed gold nanoparticles, with great cellular viability on tumoral and non-tumoral cells. This aspect makes them with multifunctional characteristics with potential application for cancer diagnosis and therapy. Through the complete morphological and physicochemical characterization, it was possible to observe that both MoS2-PEG and MoS2-PEG/Au showed good chemical stability and demonstrated noninterference in the pattern of the cell nucleus, as well. Thus, our results suggest the possible application of these hybrid nanomaterials can be immensely explored for theranostic proposals in biomedicine
Climate variability and aridity modulate the role of leaf shelters for arthropods:a global experiment
Regional Brain and Spinal Cord Volume Loss in Spinocerebellar Ataxia Type 3
Background: Given that new therapeutic options for spinocerebellar ataxias are on the horizon, there is a need for markers that reflect disease-related alterations, in particular, in the preataxic stage, in which clinical scales are lacking sensitivity. Objective: The objective of this study was to quantify regional brain volumes and upper cervical spinal cord areas in spinocerebellar ataxia type 3 in vivo across the entire time course of the disease. Methods: We applied a brain segmentation approach that included a lobular subsegmentation of the cerebellum to magnetic resonance images of 210 ataxic and 48 preataxic spinocerebellar ataxia type 3 mutation carriers and 63 healthy controls. In addition, cervical cord cross-sectional areas were determined at 2 levels. Results: The metrics of cervical spinal cord segments C3 and C2, medulla oblongata, pons, and pallidum, and the cerebellar anterior lobe were reduced in preataxic mutation carriers compared with controls. Those of cervical spinal cord segments C2 and C3, medulla oblongata, pons, midbrain, cerebellar lobules crus II and X, cerebellar white matter, and pallidum were reduced in ataxic compared with nonataxic carriers. Of all metrics studied, pontine volume showed the steepest decline across the disease course. It covaried with ataxia severity, CAG repeat length, and age. The multivariate model derived from this analysis explained 46.33% of the variance of pontine volume. Conclusion: Regional brain and spinal cord tissue loss in spinocerebellar ataxia type 3 starts before ataxia onset. Pontine volume appears to be the most promising imaging biomarker candidate for interventional trials that aim at slowing the progression of spinocerebellar ataxia type 3. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society
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