45 research outputs found
Metallic ground state in an ion-gated two-dimensional superconductor
Recently emerging two-dimensional (2D) superconductors in atomically thin layers and at heterogeneous interfaces are attracting growing interest in condensed matter physics. Here, we report that an ion-gated zirconium nitride chloride surface, exhibiting a dome-shaped phase diagram with a maximum critical temperature of 14.8 kelvin, behaves as a superconductor persisting to the 2D limit. The superconducting thickness estimated from the upper critical fields is congruent to 1.8 nanometers, which is thinner than one unit-cell. The majority of the vortex phase diagram down to 2 kelvin is occupied by a metallic state with a finite resistance, owing to the quantum creep of vortices caused by extremely weak pinning and disorder. Our findings highlight the potential of electric-field-induced superconductivity, establishing a new platform for accessing quantum phases in clean 2D superconductors.</p
Superconductivity protected by spin-valley locking in ion-gated MoS2
Symmetry-breaking has been known to play a key role in noncentrosymmetric
superconductors with strong spin-orbit-interaction (SOI). The studies, however,
have been so far mainly focused on a particular type of SOI, known as Rashba
SOI, whereby the electron spin is locked to its momentum at a right-angle,
thereby leading to an in-planar helical spin texture. Here we discuss
electric-field-induced superconductivity in molybdenum disulphide (MoS2), which
exhibits a fundamentally different type of intrinsic SOI manifested by an
out-of-plane Zeeman-type spin polarization of energy valleys. We find an upper
critical field of approximately 52 T at 1.5 K, which indicates an enhancement
of the Pauli limit by a factor of four as compared to that in centrosymmetric
conventional superconductors. Using realistic tight-binding calculations, we
reveal that this unusual behaviour is due to an inter-valley pairing that is
symmetrically protected by Zeeman-type spin-valley locking against external
magnetic fields. Our study sheds a new light on the interplay of inversion
asymmetry with SOI in confined geometries, and its unprecedented role in
superconductivity.Comment: 37 pages, 11 figures,
http://meetings.aps.org/Meeting/MAR15/Session/G11.1
Randomized phase II study to determine the optimal dose of 3-week cycle nab-paclitaxel in patients with metastatic breast cancer
Background
Chemotherapy-induced peripheral neuropathy is commonly observed in patients treated with nanoparticle albumin–bound paclitaxel (nab-PTX). We conducted a multicenter randomized controlled study to evaluate the optimal dose of nab-PTX.
Methods
We compared three different doses of q3w nab-PTX (Standard: 260 mg/m2 [SD260] vs Medium: 220 mg/m2 [MD220] vs Low: 180 mg/m2 [LD180]) in patients with HER2-negative metastatic breast cancer (MBC). Primary endpoint was progression-free survival (PFS). Grade 3/4 neuropathy rates in the three doses were estimated using the logistic regression model. The optimal dose was selected in two steps. Initially, if the hazard ratio (HR) for PFS was 1.33, the inferior dose was excluded, and we proceeded with the non-inferior dose. Then, if the estimated incidence rate of grade 3/4 neurotoxicity exceeded 10%, that dose was also excluded.
Results
One hundred forty-one patients were randomly assigned to SD260 (n = 47), MD220 (n = 46), and LD180 (n = 48) groups, and their median PFS was 6.66, 7.34, and 6.82 months, respectively. The HRs were 0.73 (95% confidence interval [CI]: 0.42–1.28) in MD220 vs SD260, 0.77 (95% CI 0.47–1.28) in LD180 vs SD260, and 0.96 (95% CI 0.56–1.66) in LD180 vs MD220. SD260 was inferior to MD220 and was excluded. The estimated incidence rate of grade 3/4 neurotoxicity was 29.5% in SD260, 14.0% in MD220, and 5.9% in LD180. The final selected dose was LD180.
Conclusions
Intravenous administration of low-dose nab-PTX at 180 mg/m2 q3w may be the optimal therapy with meaningful efficacy and favorable toxicity in patients with MBC
Association of Genetic Polymorphism with Taxane-induced Peripheral Neuropathy: Sub-analysis of a Randomized Phase II Study to Determine the Optimal Dose of 3-week Cycle Nab-Paclitaxel in Metastatic Breast Cancer Patients
Chemotherapy-induced peripheral neuropathy (CIPN) is an important clinical challenge that threatens patients’ quality of life. This sub-study of the ABROAD trial investigated the influence of single nucleotide polymorphisms (SNPs) on CIPN, using genotype data from a randomized study to determine the optimal dose of a 3-week-cycle regimen of nab-paclitaxel (q3w nab-PTX) in patients with metastatic breast cancer (MBC). Patients with HER2-negative MBC were randomly assigned to three doses of q3w nab-PTX (SD: 260 mg/m2 vs. MD: 220 mg/m2 vs. LD: 180 mg/m2). Five SNPs (EPHA4-rs17348202, EPHA5-rs7349683, EPHA6-rs301927, LIMK2-rs5749248, and XKR4-rs4737264) were analyzed based on the results of a previous genome-wide association study. Per-allele SNP associations were assessed by a Cox regression to model the cumulative dose of nab-PTX up to the onset of severe or worsening sensory neuropathy. A total of 141 patients were enrolled in the parent study; 91(65%) were included in this sub-study. Worsening of CIPN was significantly greater in the cases with XKR4 AC compared to those with a homozygote AA (HR 1.86, 95%CI: 1.00001−3.46, p=0.049). There was no significant correlation of CIPN with any other SNP. A multivariate analysis showed that the cumulative dose of nab-PTX was most strongly correlated with CIPN (p<0.01)