Single-phase powders of bismuth ferrite have been synthesized for the first time by ultrasonic spray pyrolysis from nitrate solution in the presence of tartaric acid. The produced powders consist of ...hollow spherical agglomerates with a mean diameter of ∼1 μm. The influence of tartaric acid concentration on the synthesis temperature and morphology of hollow spheres was established. The agglomerate shells have open and closed pores. The mean values of the shell thickness and the ratios of closed and open pores were estimated and their dependence on the concentration of tartaric acid was found. It was shown that the magnetic properties are determined not only by the size of nanoparticles composing the agglomerates, but also by the morphology of hollow sphere shells.
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•A new type of BiFeO3 nanostructure was discovered-hollow spheres.•Changing the concentration of TA can change the morphology of the spheres.•The effect of morphology on the magnetic properties is established.
Current genetic and genomic tests measuring homologous recombination deficiency (HRD) show limited predictive value. This study compares the performance of an immunohistology-based RAD51 test with ...genetic/genomic tests to identify patients with HRD primary triple-negative breast cancer (TNBC) and evaluates its accuracy to select patients sensitive to platinum-based neoadjuvant chemotherapy (NACT).
This is a retrospective, blinded, biomarker analysis from the GeparSixto randomized clinical trial. TNBC patients received neoadjuvant paclitaxel plus Myocet®-nonpegylated liposomal doxorubicin (PM) or PM plus carboplatin (PMCb), both arms including bevacizumab. Formalin-fixed paraffin-embedded (FFPE) tumor samples were laid on tissue microarrays. RAD51, BRCA1 and γH2AX were quantified using an immunofluorescence assay. The predictive value of RAD51 was assessed by regression models. Concordance analyses were carried out between RAD51 score and tumor BRCA (tBRCA) status or genomic HRD score (Myriad myChoice®). Associations with pathological complete response (pCR) and survival were studied. Functional HRD was predefined as a RAD51 score ≤10% (RAD51-low).
Functional HRD by RAD51-low was evidenced in 81/133 tumors (61%). RAD51 identified 93% tBRCA-mutated tumors and 45% non-tBRCA mutant cases as functional HRD. The concordance between RAD51 and genomic HRD was 87% 95% confidence interval (CI) 79% to 93%. In patients with RAD51-high tumors, pCR was similar between treatment arms PMCb 31% versus PM 39%, odds ratio (OR) 0.71, 0.23-2.24, P = 0.56. Patients with RAD51-low tumors benefited from PMCb (pCR 66% versus 33%, OR 3.96, 1.56-10.05, P = 0.004; interaction test P = 0.02). This benefit maintained statistical significance in the multivariate analysis. Carboplatin addition showed similar disease-free survival in the RAD51-high hazard ratio (HR) 0.40, log-rank P = 0.11 and RAD51-low (0.45, P = 0.11) groups.
The RAD51 test identifies tumors with functional HRD and is highly concordant with tBRCA mutation and genomic HRD. RAD51 independently predicts clinical benefit from adding Cb to NACT in TNBC. Our results support further development to incorporate RAD51 testing in clinical decision-making.
•Functional HRD by the RAD51 test identifies 93% of tBRCA-mutated TNBC tumors and shows 87% concordance with genomic HRD.•RAD51 independently predicts pCR with platinum (interaction test P = 0.02).•This study supports the use of RAD51 as a clinically relevant biomarker of HRD and platinum response.
Spin currents in a coherent exciton gas High, A A; Hammack, A T; Leonard, J R ...
Physical review letters,
06/2013, Letnik:
110, Številka:
24
Journal Article
Recenzirano
Odprti dostop
We report the observation of spin currents in a coherent gas of indirect excitons. The realized long-range spin currents originate from the formation of a coherent gas of bosonic pairs--a new ...mechanism to suppress the spin relaxation. The spin currents result in the appearance of a variety of polarization patterns, including helical patterns, four-leaf patterns, spiral patterns, bell patterns, and periodic patterns. We demonstrate control of the spin currents by a magnetic field. We also present a theory of coherent exciton spin transport that describes the observed exciton polarization patterns and indicates the trajectories of the spin currents.
Indirect excitons in coupled quantum wells are long-living quasiparticles, explored in the studies of collective quantum states. We demonstrate that, despite the extremely low oscillator strength, ...their spin and population dynamics can by addressed by time-resolved pump-probe spectroscopy. Our experiments make it possible to unravel and compare spin dynamics of direct excitons, indirect excitons, and residual free electrons in coupled quantum wells. Measured spin relaxation time of indirect excitons exceeds not only one of direct excitons but also one of free electrons by two orders of magnitude.
We report on the nondestructive measurement of nuclear magnetization in n-GaAs via cavity enhanced Faraday rotation. In contrast with the existing optical methods, this detection scheme does not ...require the presence of detrimental out-of-equilibrium electrons. Specific mechanisms of the Faraday rotation are identified for (i) nuclear spins situated within the localized electron orbits, these spins are characterized by fast dynamics, (ii) all other nuclear spins in the sample characterized by much slower dynamics. Our results suggest that even in degenerate semiconductors nuclear spin relaxation is limited by the presence of localized electron states and spin diffusion, rather than by Korringa mechanism.
We develop an improved method for tracking the nuclear flame during the deflagration phase of a Type Ia supernova and apply it in a study of the variation in outcomes expected from the ...gravitationally confined detonation (GCD) paradigm. A simplified three-stage burning model and a nonstatic ash state are integrated with an artificially thickened advection-diffusion-reaction (ADR) flame front in order to provide an accurate but highly efficient representation of the energy release and electron capture in and after the unresolvable flame. We demonstrate that neither our ADR nor our energy release methods generate significant acoustic noise, as has been a problem with previous ADR-based schemes. We proceed to model aspects of the deflagration, particularly the role of buoyancy of the hot ash, and find that our methods are reasonably well behaved with respect to numerical resolution. We show that if a detonation occurs in material swept up by the material ejected by the first rising bubble but gravitationally confined to the white dwarf (WD) surface (the GCD paradigm), the density structure of the WD at detonation is systematically correlated with the distance of the deflagration ignition point from the center of the star. Coupled to a suitably stochastic ignition process, this correlation may provide a plausible explanation for the variety of nickel masses seen in Type Ia supernovae.
Ballistic spin transport in exciton gases Kavokin, A. V.; Vladimirova, M.; Jouault, B. ...
Physical review. B, Condensed matter and materials physics,
11/2013, Letnik:
88, Številka:
19
Journal Article
Recenzirano
Odprti dostop
Traditional spintronics relies on spin transport by charge carriers, such as electrons in semiconductor crystals. The challenges for the realization of long-range electron spin transport include ...rapid spin relaxation due to electron scattering. Scattering and, in turn, spin relaxation can be effectively suppressed in excitonic devices where the spin currents are carried by electrically neutral bosonic quasiparticles: excitons or exciton-polaritons. They can form coherent quantum liquids that carry spins over macroscopic distances. The price to pay is a finite lifetime of the bosonic spin carriers. We present the theory of exciton ballistic spin transport which may be applied to a range of systems supporting bosonic spin transport, in particular to indirect excitons in coupled quantum wells. We describe the effect of spin-orbit interaction for the electron and the hole on the exciton spin, account for the Zeeman effect induced by external magnetic fields and long-range and short-range exchange splittings of the exciton resonances. We also consider exciton transport in the nonlinear regime and discuss the definitions of the exciton spin current, polarization current, and spin conductivity.
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