From Mott insulator to ferromagnetic metal: a pressure study of Ca2_{2}RuO4_{4}

We show that the pressure-temperature phase diagram of the Mott insulator Ca$_{2}$RuO$_{4}$ features a metal-insulator transition at 0.5GPa: at 300K from paramagnetic insulator to paramagnetic quasi-two-dimensional metal; at $T \leq$ 12K from antiferromagnetic insulator to ferromagnetic, highly anisotropic, three-dimensional metal. % We compare the metallic state to that of the structurally related p-wave superconductor Sr$_{2}$RuO$_{4}$, and discuss the importance of structural distortions, which are expected to couple strongly to pressure.Comment: 4 pages, 4figure

TRPV6 as a putative genomic susceptibility locus influencing racial disparities in cancer

It is well established that African Americans exhibit higher incidence, higher mortality, and more aggressive forms of some cancers, including those of breast, prostate, colon, stomach, and cervix. Here we examine the ancestral haplotype of the TRPV6 calcium channel as a putative genomic factor in this racial divide. The minor (ancestral) allele frequency is 60% in people of African ancestry, but between 1 and 11% in all other populations. Research on TRPV6 structure/function, its association with specific cancers, and the evolutionary-ecological conditions which impacted selection of its haplotypes are synthesized to provide evidence for TRPV6 as a germline susceptibility locus in cancer. Recently elucidated mechanisms of TRPV6 channel deactivation are discussed in relation to the location of the allele favored in selection, suggesting a reduced capacity to inactivate the channel in those who have the ancestral haplotype. This could result in an excessively high cellular Ca2+, which has been implicated in cancer, for those in settings where calcium intake is far higher than in their ancestral environment. A recent report associating increasing calcium intake with a pattern of increase in aggressive prostate cancer in African-American but not European-American men may be related. If TRPV6 is found to be associated with cancer, further research would be warranted to improve risk assessment and examine interventions with the aim of improving cancer outcomes for people of African ancestr

Superconductivity up to 29 K in SrFe2As2 and BaFe2As2 at high pressures

We report the discovery of superconductivity at high pressure in SrFe2As2 and BaFe2As2. The superconducting transition temperatures are up to 27 K in SrFe2As2 and 29 K in BaFe2As2, making these the highest pressure-induced superconducting materials discovered thus far.Comment: Accepted in Journal of Physics: Condensed Matte

Pressure-induced and Composition-induced Structural Quantum Phase Transition in the Cubic Superconductor (Sr/Ca)_3Ir_4Sn_{13}

We show that the quasi-skutterudite superconductor Sr_3Ir_4Sn_{13} undergoes a structural transition from a simple cubic parent structure, the I-phase, to a superlattice variant, the I'-phase, which has a lattice parameter twice that of the high temperature phase. We argue that the superlattice distortion is associated with a charge density wave transition of the conduction electron system and demonstrate that the superlattice transition temperature T* can be suppressed to zero by combining chemical and physical pressure. This enables the first comprehensive investigation of a superlattice quantum phase transition and its interplay with superconductivity in a cubic charge density wave system.Comment: 4 figures, 5 pages (excluding supplementary material). To be published in Phys. Rev. Let

Long‐term effects of pallidal and thalamic deep brain stimulation in myoclonus dystonia

Objective: Observational study to evaluate long-term effects of deep brain stimulation (DBS) of the globus pallidus internus (GPi) and the ventral intermediate thalamic nucleus (VIM) on patients with medically refractory myoclonus dystonia (MD). Background: More recently, pallidal as well as thalamic DBS have been applied successfully in MD but long-term data are sparse. Methods: We retrospectively analyzed a cohort of seven MD patients with either separate (n = 1, VIM) or combined GPi- DBS and VIM-DBS (n = 6). Myoclonus, dystonia and disability were rated at baseline (BL), short-term (ST-FU) and long-term follow-up (LT-FU) using the United Myoclonus Rating Scale, Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and Tsui rating scale, respectively. Quality of life (QoL) and mood were evaluated using the SF-36 and Beck Depression Inventory questionnaires, respectively. Results: Patients reached a significant reduction of myoclonus at ST-FU (62% ± 7.3%; mean ± SE) and LT-FU (68% ± 3.4%). While overall motor BFMDRS changes were not significant at LT-FU, patients with GPi-DBS alone responded better and predominant cervical dystonia ameliorated significantly up to 54% ± 9.7% at long-term. Mean disability scores significantly improved by 44% ± 11.4% at ST-FU and 58% ± 14.8% at LT-FU. Mood and QoL remained unchanged between 5 and up to 20 years postoperatively. No serious long-lasting stimulation-related adverse events were observed. Conclusions: We present a cohort of MD patients with very long follow-up of pallidal and/or thalamic DBS that supports the GPi as the favourable stimulation target in MD with safe and sustaining effects on motor symptoms (myoclonus>dystonia) and disability

Human Periodontal Ligament- and Gingiva-derived Mesenchymal Stem Cells Promote Nerve Regeneration When Encapsulated in Alginate/hyaluronic Acid 3D Scaffold

Repair or regeneration of damaged nerves is still a challenging clinical task in reconstructive surgeries and regenerative medicine. Here, we demonstrate that periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs) isolated from adult human periodontal and gingival tissues assume neuronal phenotype in vitro and in vivo via a subcutaneous transplantation model in nude mice. PDLSCs and GMSCs were encapsulated in a three-dimensional scaffold based on alginate and hyaluronic acid hydrogels capable of sustained release of human nerve growth factor (NGF). We demonstrate that, the elasticity of the hydrogels affected the proliferation and differentiation of encapsulated MSCs within scaffolds. Moreover, we observed that PDLSCs and GMSCs were stained positive for βIII-tubulin, while exhibiting high levels of gene expression related to neurogenic differentiation (βIII-tubulin and GFAP) via qPCR. Western blot analysis showed the importance of the elasticity of the matrix and the presence of NGF in the neurogenic differentiation of encapsulated MSCs. In vivo, immunofluorescence staining for neurogenic specific protein markers confirmed islands of dense positively stained structures inside transplanted hydrogels. To our knowledge, this study is the first demonstration of the application of PDLSCs and GMSCs as promising cell therapy candidates for nerve regeneration

Superconductivity beyond the Pauli limit in high-pressure CeSb2

We report the discovery of superconductivity at a pressure-induced magnetic quantum critical point in the Kondo-lattice system CeSb2, sustained up to magnetic fields that exceed the conventional Pauli limit eight-fold. Like CeRh2As2, CeSb2 is locally non-centrosymmetric around the Ce-site, but the evolution of critical fields and normal state properties as CeSb2 is tuned through the quantum critical point motivates a fundamentally different explanation for its resilience to applied field.Comment: 5 pages, 3 figure

Isostructural Mott transition in 2D honeycomb antiferromagnet V 0.9 PS 3

Abstract: The MPX3 family of magnetic van-der-Waals materials (M denotes a first row transition metal and X either S or Se) are currently the subject of broad and intense attention for low-dimensional magnetism and transport and also for novel device and technological applications, but the vanadium compounds have until this point not been studied beyond their basic properties. We present the observation of an isostructural Mott insulator–metal transition in van-der-Waals honeycomb antiferromagnet V0.9PS3 through high-pressure x-ray diffraction and transport measurements. We observe insulating variable-range-hopping type resistivity in V0.9PS3, with a gradual increase in effective dimensionality with increasing pressure, followed by a transition to a metallic resistivity temperature dependence between 112 and 124 kbar. The metallic state additionally shows a low-temperature upturn we tentatively attribute to the Kondo effect. A gradual structural distortion is seen between 26 and 80 kbar, but no structural change at higher pressures corresponding to the insulator–metal transition. We conclude that the insulator–metal transition occurs in the absence of any distortions to the lattice—an isostructural Mott transition in a new class of two-dimensional material, and in strong contrast to the behavior of the other MPX3 compounds