Strain gradient induced polarization in SrTiO3 single crystals

Piezoelectricity is inherent only in noncentrosymmetric materials, but a piezoelectric response can also be obtained in centrosymmetric crystals if subjected to inhomogeneous deformation. This phenomenon, known as flexoelectricity, affects the functional properties of insulators, particularly thin films of high permittivity materials. We have measured strain-gradient-induced polarization in single crystals of paraelectric SrTiO$_3$ as a function of temperature and orientation down to and below the 105 K phase transition. Estimates were obtained for all the components of the flexoelectric tensor, and calculations based on these indicate that local polarization around defects in SrTiO$_3$ may exceed the largest ferroelectric polarizations. A sign reversal of the flexoelectric response detected below the phase transition suggests that the ferroelastic domain walls of SrTiO$_3$ may be polar.Comment: 4 pages, 3 figures, 1 tabl

Path integral Monte Carlo simulations of silicates

We investigate the thermal expansion of crystalline SiO$_2$ in the $\beta$-- cristobalite and the $\beta$-quartz structure with path integral Monte Carlo (PIMC) techniques. This simulation method allows to treat low-temperature quantum effects properly. At temperatures below the Debye temperature, thermal properties obtained with PIMC agree better with experimental results than those obtained with classical Monte Carlo methods.Comment: 27 pages, 10 figures, Phys. Rev. B (in press

A combined X-ray scattering and simulation study of halothane in membranes at raised pressures

a b s t r a c t Using a combination of high pressure wide angle X-ray scattering experiments and molecular dynamics simulations, we probe the effect of the archetypal general anaesthetic halothane on the lipid hydrocarbon chain packing and ordering in model bilayers and the variation in these parameters with pressure. Incorporation of halothane into the membrane causes an expansion of the lipid hydrocarbon chain packing at all pressures. The effect of halothane incorporation on the hydrocarbon chain order parameter is significantly reduced at elevated pressure

Trimodality therapy for malignant pleural mesothelioma: Results from an EORTC phase II multicentre trial

The European Organisation for Research and Treatment of Cancer (EORTC; protocol 08031) phase II trial investigated the feasibility of trimodality therapy consisting of induction chemotherapy followed by extrapleural pneumonectomy and post-operative radiotherapy in patients with malignant pleural mesothelioma (with a severity of cT3N1M0 or less). Induction chemotherapy consisted of three courses of cisplatin 75 mg·m -2 and pemetrexed 500 mg·m -2. Nonprogressing patients underwent extrapleural pneumonectomy followed by postoperative radiotherapy (54 Gy, 30 fractions). Our primary end-point was "success of treatment" and our secondary end-points were toxicity, and overall and progression-free survival. 59 patients were registered, one of whom was ineligible. Subjects' median age was 57 yrs. The subjects' TNM scores were as follows: cT1, T2 and T3, 36, 16 and six patients, respectively; cN0 and N1, 57 and one patient, respectively. 55 (93%) patients received three cycles of chemotherapy with only mild toxicity. 46 (79%) patients received surgery and 42 (74%) had extrapleural pneumonectomy with a 90-day mortality of 6.5%. Post-operative radiotherapy was completed in 37 (65%) patients. Grade 3-4 toxicity persisted after 90 days in three (5.3%) patients. Median overall survival time was 18.4 months (95% CI 15.6-32.9) and median progression-free survival was 13.9 months (95% CI 10.9-17.2). Only 24 (42%) patients met the definition of success (one-sided 90% CI 0.36-1.00). Although feasible, trimodality therapy in patients with mesothelioma was not completed within the strictly defined timelines of this protocol and adjustments are necessary. Copyrigh