The controlled modification of superconductivity by any means is a long-standing issue in low-temperature physics. In this work, we present data on the control of the superconducting properties of conventional low critical-temperature (T-C) Nb thin films with thickness (d(Nb)) =15 and 20 nm under application of reconfigurable strain, S induced by an external electric field, and E-ex to a piezoelectric (PE) single crystal, namely (1 - x)Pb(Mg1/3Nb2/3)O-3 - x PbTiO3 (PMN-PT) with x =0.30-0.31. The experimental results (reduction of T-C and critical current (J(C)) on the order of 6% and 90-100%, respectively) are nicely reproduced with a phenomenological model that incorporates the constitutive relation S(E-ex) that describes the electro-mechanical response of the PE crystal to well-established formulas that describe T-C and J(C) of the SC thin films.

Superparamagnetic iron oxide nanoparticles with well-integrated multimodality imaging properties have generated increasing research interest in the past decade, especially when it comes to the targeted imaging of tumors. Bevacizumab (BCZM) on the other hand is a well-known and widely applied monoclonal antibody recognizing VEGF-A, which is overexpressed in angiogenesis. The aim of this proof-of-concept study was to develop a dual-modality nanoplatform for in vivo targeted single photon computed emission tomography (SPECT) and magnetic resonance imaging (MRI) of tumor vascularization. Iron oxide nanoparticles (IONPs) have been coated with dimercaptosuccinic acid (DMSA), for consequent functionalization with the monoclonal antibody BCZM radiolabeled with Tc-99m, via well-developed surface engineering. The IONPs were characterized based on their size distribution, hydrodynamic diameter and magnetic properties. In vitro cytotoxicity studies showed that our nanoconstruct does not cause toxic effects in normal and cancer cells. Fe3O4-DMSA-SMCC-BCZM-Tc-99m were successfully prepared at high radiochemical purity (> 92%) and their stability in human serum and in PBS were demonstrated. In vitro cell binding studies showed the ability of the Fe3O4-DMSA-SMCC-BCZM-Tc-99m to bind to the VEGF-165 isoform overexpressed on M-165 tumor cells. The ex vivo biodistribution studies in M165 tumor-bearing SCID mice showed high uptake in liver, spleen, kidney and lungs. The Fe3O4-DMSA-SMCC-BCZM-Tc-99m demonstrated quick tumor accumulation starting at 8.9 +/- 1.88% ID/g at 2 h p.i., slightly increasing at 4 h p.i. (16.21 +/- 2.56% ID/g) and then decreasing at 24 h p.i. (6.01 +/- 1.69% ID/g). The tumor-to-blood ratio reached a maximum at 24 h p.i. (similar to 7), which is also the case for the tumor-to- muscle ratio (similar to 18). Initial pilot imaging studies on an experimental gamma-camera and a clinical MR camera prove our hypothesis and demonstrate the potential of Fe3O4-DMSA-SMCC-BCZM-Tc-99m for targeted dual-modality imaging. Our findings indicate that Fe3O4-DMSA-SMCC-BCZM-Tc-99m IONPs could serve as an important diagnostic tool for biomedical imaging as well as a promising candidate for future theranostic applications in cancer.

Electric-field-controlled piezoelectric strain has been used, recently, to modify the superconducting properties in a new class of piezoelectric/superconducting (PE/SC) hybrids. Here, we investigate the appearance of thermomagnetic instabilities (TMIs) and the respective modification of the critical current density (J(C)) through the application of electric field (E-ex) in PE/SC hybrids. Specifically, the SC nanolayers are Nb (thickness, d(SC) = 20 nm) deposited on both surfaces of PE macroscopic crystals of (1-x)Pb(Mg-1/3 Nb-2/3)O-3-xPbTiO(3) (PMN-PT) with optimum composition x = 0.31 (thickness, d(PE) = 0.5-0.8 mm). The appearance of TMIs and the modification of J(C) by E-ex is studied for two PMN-PT crystals of drastically different surface roughness (Sa). In the case of the PMN-PT crystal with low Sa (on the order of a few tenths of nm) TMIs are absent so that J(C) does not change under the variation of E-ex. On the contrary, in the case of the PMN-PT crystal with high Sa (on the order of a few hundreds of nm) E-ex induces TMIs in the Nb nanolayers. Specifically, the number of TMIs exhibits a non-monotonic increase on E-ex, thus causing a non-monotonic degradation of J(C). These experimental data are interpreted in terms of the variation of both volume strain and surface roughness on E-ex. This work highlights practical means to control the current-carrying capability of SC nanolayers through strain provided by PE substrates. (C) 2017 Elsevier B.V. All rights reserved.

The controlled modification of superconductivity by any means, specifically in hybrid systems, has attracted much interest in the recent decades. Here, we present experimental data and phenomenological modeling on the control of T-C of superconducting (SC) Nb thin films, with thickness 3 nm <= d(Nb) <= 50 nm, under the application of in-plane strain, S(E-ex) induced by an external out-of-plane electric field, E-ex to piezoelectric (PE) single crystals, namely, (1 - x)Pb(Mg1/3Nb2/3)O-3-xPbTiO(3) (PMN-xPT), with x = 0.27 and 0.31. We report experimental modification of TC of Nb by E-ex, accurately described by a phenomenological model that incorporates the constitutive relation S(E-ex) of PMN-xPT. The systematic experimental-phenomenological modeling approach introduced here is generic and paves the way for an understanding of the underlying physical mechanisms in any SC/PE hybrid. Published by AIP Publishing.