138 research outputs found
Dipolar-glass-like relaxor ferroelectric behaviour in the 0.5BaTiO3-0.5Bi(Mg1/2Ti1/2)O3 electroceramic
In this study, the dielectric and ferroelectric switching behaviour of 0.5BaTiO3-0.5Bi(Mg1/2Ti1/2)O3
(BT-BMT) ceramics are investigated. The BT-BMT ceramic exhibits a typical dipolar-glass-like,
dielectric polarisation relaxation. This is attributed to the 15 distinct possible local A4B2 configurations
around the O ions and the effect this unavoidable local compositional variability has on the dipole
relaxation behaviour of inherent {1-D h111} dipole chains, arising from correlated off-centre
displacements of Bi3+ and Ti4+ ions along local {111} directions. On the other hand, switchable
polarisation under strong applied electric fields is observed on different length scales accompanied by
the appearance of strong polarisation relaxation, as observed via time-delayed piezoresponse
hysteresis loop measurements. These experimental results demonstrate that this BT-BMT ceramic
is relaxor ferroelectric in nature, although it exhibits dipolar-glass-like dielectric relaxation behaviour.The authors J.W., Y.L., and R.L.W. acknowledge the
support of the Australian Research Council (ARC) in the
form of Discovery projects. Y.L. also appreciates support
from the ARC Future Fellowships program
Mode-pairing quantum key distribution with advantage distillation
Mode-pairing quantum key distribution (MP-QKD) is an easy-to-implement scheme
that transcends the Pirandola--Laurenza--Ottaviani--Banchi bound without using
quantum repeaters. In this paper, we present an improvement of the performance
of MP-QKD using an advantage distillation method. The simulation results
demonstrate that the proposed scheme extends the transmission distance
significantly with a channel loss exceeding 7.6 dB. Moreover, the scheme
tolerates a maximum quantum bit error rate of 8.9%, which is nearly twice that
of the original MP-QKD. In particular, as the system misalignment error
increases, the expandable distance of the proposed scheme also increases. The
proposed system is expected to promote the practical implementation of MP-QKD
in a wide range of applications, particularly in scenarios involving high
channel losses and system errors
Heterologous expression and characterization of a malathion-hydrolyzing carboxylesterase from a thermophilic bacterium, Alicyclobacillus tengchongensis
A carboxylesterase gene from thermophilic bacterium, Alicyclobacillus tengchongensis, was cloned and expressed in Escherichia coli BL21 (DE3). The gene coded for a 513 amino acid protein with a calculated molecular mass of 57.82 kDa. The deduced amino acid sequence had structural features highly conserved among serine hydrolases, including Ser204, Glu325, and His415 as a catalytic triad, as well as type-B carboxylesterase serine active site (FGGDPENITIGGQSAG) and type-B carboxylesterase signature 2 (EDCLYLNIWTP). The purified enzyme exhibited optimum activity with β-naphthyl acetate at 60 °C and pH 7 as well as stability at 25 °C and pH 7. One unit of the enzyme hydrolyzed 5 mg malathion l(−1) by 50 % within 25 min and 89 % within 100 min. The enzyme strongly degraded malathion and has a potential use for the detoxification of malathion residues
Fully-inverted piezoresponse hysteresis loops mediated by charge injection in 0.29Pb(In1/2Nb1/2)O3–0.44Pb(Mg1/3Nb2/3)O3–0.27PbTiO3 single crystals
The domain structure and local switching behavior of ternary relaxor (001) 0.29Pb(In1/2Nb1/2)O3–0.44Pb(Mg1/3Nb2/3)O3–0.27PbTiO3single crystals are studied using piezoresponse force microscopy. The as-grown crystals exhibit a labyrinthine domain pattern similar to other relaxor-based ferroelectrics. Abnormally switched domains are observed for both positive and negative tip-voltages, with sign-dependent thresholds and growth rates on the poled crystals. Further piezoresponse hysteresis loop measurements show that fully inverted loops can be observed under high switching voltages, mediated by injected charge fields. The dynamic behavior of the observed abnormal switching is qualitatively analyzed and the underlying mechanisms discussed.Q.L., Y.L., and R.L.W. acknowledge financial support
from the Australian Research Council ARC in the form of
an ARC Discovery Grant No. DP0877069
Switching spectroscopic measurement of surface potentials on ferroelectric surfaces via an open-loop Kelvin probe force microscopy method
We report a method for switching spectroscopy Kelvin probe force microscopy (SS-KPFM). The method is established as a counterpart to switching spectroscopy piezoresponse force microscopy (SS-PFM) in Kelvin probe force microscopy. SS-KPFM yields quantitative information about the surface charge state during a local bias-induced polarization switching process, complementary to the electromechanical coupling properties probed via SS-PFM. Typical ferroelectric samples of a Pb-based relaxor single crystal and a BiFeO3 thin film were investigated using both methods. We briefly discuss the observed surfacecharging phenomena and their influence on the associated piezoresponse hysteresis loops.Q.L., Y.L., D.W., and R.L.W. acknowledge the support
of the Australian Research Council (ARC) in the form of
ARC Discovery Grants. Y.L. also acknowledges support
from the ARC Future Fellowships Program
Domain structure investigation of Mn-doped PIN-PMN-PT relaxor ferroelectric single crystals
Ki67 Index Changes and Tumor-Infiltrating Lymphocyte Levels Impact the Prognosis of Triple-Negative Breast Cancer Patients With Residual Disease After Neoadjuvant Chemotherapy
PurposeThe aim of this study was to assess the prognostic influence of Ki67 index changes in patients with primary triple-negative breast cancer (TNBC) treated with neoadjuvant chemotherapy (NAC), and to evaluate whether the combination of Ki67 index changes and residual disease (RD) tumor-infiltrating lymphocytes (TILs) provides additional prognostic information for this group.Materials and MethodsData from 109 patients with primary TNBC and RD after NAC were analyzed retrospectively. Ki67 changes and RD TIL levels were investigated for associations with recurrence-free survival (RFS) and overall survival (OS) using Kaplan–Meier and Cox analyses.ResultsKi67 index decreased after NAC in 53 patients (48.6%) and high RD TIL levels (≥30%) were observed in 54 patients (49.5%). In multivariate Cox analyses, no Ki67 decrease status and low RD TIL levels were significantly associated with reduced RFS (hazard ratio (HR): 2.038, 95% confidence interval (CI): 1.135–3.658, P = 0.017; HR: 2.493, 95% CI: 1.335–4.653, P = 0.004), and OS (HR: 2.187, 95% CI: 1.173–4.077, P = 0.014; HR: 2.499, 95% CI: 1.285–4.858, P = 0.007), respectively. Notably, low RD TIL levels were significantly associated with reduced RFS (HR: 3.567, 95% CI: 1.475–8.624, P = 0.005) and reduced OS (HR: 3.873, 95% CI: 1.512–9.918, P = 0.005) in only the no Ki67 decrease group. The differences in 3-year RFS and OS between patients with no Ki67 decrease and low or high RD TIL levels were 24.4% vs 79.1% (P = 0.0001) and 33.1% vs 87.5% (P = 0.0001), respectively.ConclusionKi67 index changes and RD TIL levels were associated with the prognosis of patients with primary TNBC with RD after NAC. RD TIL levels had greater prognostic significance in the no Ki67 decrease group
- …