Coupled magnetic-ferroelectric metal-insulator transitions in epitaxially-strained SrCoO3_{3} from first principles

First-principles calculations of the epitaxial-strain phase diagram of perovskite SrCoO$_{3}$ are presented. Through combination of the large spin-phonon coupling with polarization-strain coupling and coupling of the band gap to the polar distortion, both tensile and compressive epitaxial strain are seen to drive the bulk ferromagnetic-metallic (FM-M) phase to antiferromagnetic-insulating-ferroelectric (AFM-I-FE) phases, the latter having unusually low elastic energy. At these coupled magnetic-ferroelectric metal-insulator phase boundaries, cross responses to applied electric and magnetic fields and stresses are expected. In particular, a magnetic field or compressive uniaxial stress applied to the AFM phases could induce an insulator-metal transition, and an electric field applied to the FM-M phase could induce a metal-insulator transition.Comment: 2 figures and 1 tabl

What Inspires Leisure Time Invention?

This paper seeks to understand the intriguing but only sparsely explored phenomenon of “leisure time invention,” where the main underlying idea for the new product or process occurs when the inventor is away from the workplace. We add to previous research by focussing on the inventive creativity of the individual researcher, and reassessing the image of researchers inventing during unpaid time – who have often been dispatched as “hobbyists”. Based on the responses from a survey of over 3,000 German inventors, we tested hypotheses on the conditions under which leisure time invention is likely to arise. Results suggest that the incidence of leisure time invention is positively related to exposure to a variety of knowledge inputs – but, surprisingly, not to the quality of prior inventive output. Leisure time inventions are more frequently observed in conceptual-based technologies than in science-based technologies, in smaller R&D projects, and in externally financed R&D projects

Epitaxial-strain-induced multiferroicity in SrMnO3_{3} from first principles

First-principles density-functional calculations reveal a large spin-phonon coupling in cubic SrMnO$_{3}$, with ferromagnetic ordering producing a polar instability. Through combination of this coupling with the strain-polarization coupling characteristic of perovskites, the bulk antiferromagnetic paraelectric ground state of SrMnO$_3$ is shown to be driven to a previously unreported multiferroic ferroelectric-ferromagnetic state by increasing epitaxial strain, both tensile and compressive. This state has a computed polarization and estimated Curie temperature above 54 $\mu$C/cm$^2$ and 92 K. Large mixed magnetic-electric-elastic responses are predicted in the vicinity of the phase boundaries.Comment: 5 pages, 2 figures, 1 tabl

What Inspires Leisure Time Invention?

This paper seeks to understand the intriguing but only sparsely explored phenomenon of “leisure time invention,” where the main underlying idea for the new product or process occurs when the inventor is away from the workplace. We add to previous research by focussing on the inventive creativity of the individual researcher, and reassessing the image of researchers inventing during unpaid time – who have often been dispatched as “hobbyists”. Based on the responses from a survey of over 3,000 German inventors, we tested hypotheses on the conditions under which leisure time invention is likely to arise. Results suggest that the incidence of leisure time invention is positively related to exposure to a variety of knowledge inputs – but, surprisingly, not to the quality of prior inventive output. Leisure time inventions are more frequently observed in conceptual-based technologies than in science-based technologies, in smaller R&D projects, and in externally financed R&D projects.Leisure Time; Inventiveness; Organizational Creativity

Stabilization of highly polar BiFeO3_3-like structure: a new interface design route for enhanced ferroelectricity in artificial perovskite superlattices

In ABO3 perovskites, oxygen octahedron rotations are common structural distortions that can promote large ferroelectricity in BiFeO3 with an R3c structure [1], but suppress ferroelectricity in CaTiO3 with a Pbnm symmetry [2]. For many CaTiO3-like perovskites, the BiFeO3 structure is a metastable phase. Here, we report the stabilization of the highly-polar BiFeO3-like phase of CaTiO3 in a BaTiO3/CaTiO3 superlattice grown on a SrTiO3 substrate. The stabilization is realized by a reconstruction of oxygen octahedron rotations at the interface from the pattern of nonpolar bulk CaTiO3 to a different pattern that is characteristic of a BiFeO3 phase. The reconstruction is interpreted through a combination of amplitude-contrast sub 0.1nm high-resolution transmission electron microscopy and first-principles theories of the structure, energetics, and polarization of the superlattice and its constituents. We further predict a number of new artificial ferroelectric materials demonstrating that nonpolar perovskites can be turned into ferroelectrics via this interface mechanism. Therefore, a large number of perovskites with the CaTiO3 structure type, which include many magnetic representatives, are now good candidates as novel highly-polar multiferroic materials [3].Comment: Phys. Rev. X, in productio

The Effects of Applied Local Heat on Transdermal Drug Delivery Systems

Transdermal drug delivery systems have been developed over the past several decades and now include patches for birth control, nicotine addiction, and pain relief. The local application of heat can increase the diffusion coefficient of the drug in the skin and result in faster delivery of the drug and shorter time to reach a steady state concentration of the drug. While this procedure is desirable for some systems where a faster dose will aid in alleviating pain and/or symptoms, it can also be a cause of concern for some drugs. Fentanyl, a chronic pain relief drug, can cause accidental death by overdose. We report herein an analysis of the effects of various heating situations on transdermal fentanyl delivery based upon a model developed using COMSOL Multiphysics. The utilization of such a model allows for the determination of situations which may be potentially dangerous for fentanyl drug users, and enables the development of usage guidelines and safety mechanisms for transdermal delivery systems. Using the computer model, the following cases were simulated: no applied heat, ThermaCare heat pad, fever, and heating blanket. The heating blanket and ThermaCare heat pad simulations showed the most dangerous increases in fentanyl blood concentration above no-heat levels: about 180% and 100%, respectively, over 30 hours; by contrast, the patient fever model reported a 40% increase in fentanyl blood concentration. These simulations demonstrate the dangers of fentanyl transdermal pain patches when skin temperature is increased, and can be used to develop better patient guidelines for patch use and to improve fentanyl transdermal systems. Lastly, this computer model may be used to model other transdermal drug delivery systems for the improvement of patient guidelines and/or the development of new systems, thus decreasing the need for experimentation on subjects

Gene doctoring: a method for recombineering in laboratory and pathogenic Escherichia coli strains

Background: Homologous recombination mediated by the lambda-Red genes is a common method for making chromosomal modifications in Escherichia coli. Several protocols have been developed that differ in the mechanisms by which DNA, carrying regions homologous to the chromosome, are delivered into the cell. A common technique is to electroporate linear DNA fragments into cells. Alternatively, DNA fragments are generated in vivo by digestion of a donor plasmid with a nuclease that does not cleave the host genome. In both cases the lambda-Red gene products recombine homologous regions carried on the linear DNA fragments with the chromosome. We have successfully used both techniques to generate chromosomal mutations in E. coli K-12 strains. However, we have had limited success with these lambda-Red based recombination techniques in pathogenic E. coli strains, which has led us to develop an enhanced protocol for recombineering in such strains. \ud \ud Results: Our goal was to develop a high-throughput recombineering system, primarily for the coupling of genes to epitope tags, which could also be used for deletion of genes in both pathogenic and K-12 E. coli strains. To that end we have designed a series of donor plasmids for use with the lambda-Red recombination system, which when cleaved in vivo by the I-SceI meganuclease generate a discrete linear DNA fragment, allowing for C-terminal tagging of chromosomal genes with a 6xHis, 3xFLAG, 4xProteinA or GFP tag or for the deletion of chromosomal regions. We have enhanced existing protocols and technologies by inclusion of a cassette conferring kanamycin resistance and, crucially, by including the sacB gene on the donor plasmid, so that all but true recombinants are counter-selected on kanamycin and sucrose containing media, thus eliminating the need for extensive screening. This method has the added advantage of limiting the exposure of cells to the potential damaging effects of the lambda-Red system, which can lead to unwanted secondary alterations to the chromosome. \ud \ud Conclusion: We have developed a counter-selective recombineering technique for epitope tagging or for deleting genes in E. coli. We have demonstrated the versatility of the technique by modifying the chromosome of the enterohaemorrhagic O157:H7 (EHEC), uropathogenic CFT073 (UPEC), enteroaggregative O42 (EAEC) and enterotoxigenic H10407 (ETEC) E. coli strains as well as in K-12 laboratory strains

Time for change: a new training programme for morpho-molecular pathologists?

The evolution of cellular pathology as a specialty has always been driven by technological developments and the clinical relevance of incorporating novel investigations into diagnostic practice. In recent years, the molecular characterisation of cancer has become of crucial relevance in patient treatment both for predictive testing and subclassification of certain tumours. Much of this has become possible due to the availability of next-generation sequencing technologies and the whole-genome sequencing of tumours is now being rolled out into clinical practice in England via the 100 000 Genome Project. The effective integration of cellular pathology reporting and genomic characterisation is crucial to ensure the morphological and genomic data are interpreted in the relevant context, though despite this, in many UK centres molecular testing is entirely detached from cellular pathology departments. The CM-Path initiative recognises there is a genomics knowledge and skills gap within cellular pathology that needs to be bridged through an upskilling of the current workforce and a redesign of pathology training. Bridging this gap will allow the development of an integrated 'morphomolecular pathology' specialty, which can maintain the relevance of cellular pathology at the centre of cancer patient management and allow the pathology community to continue to be a major influence in cancer discovery as well as playing a driving role in the delivery of precision medicine approaches. Here, several alternative models of pathology training, designed to address this challenge, are presented and appraised