Strain derivative of thermoelectric properties as a sensitive probe for nematicity

The nematic instability is an undebatable ingredient of the physics of iron-based superconductors. Yet, its origin remains enigmatic as it involves a fermiology with an intricate interplay of lattice-, orbital-, and spin degrees of freedom. It is well known that thermoelectric transport is an excellent probe for revealing even subtle signatures of instabilities and pertinent fluctuations. In this paper, we report a strong response of the thermoelectric transport properties of two underdoped 1111 iron-based superconductors to a vanishingly small strain. By introducing the strain derivative of the Seebeck and the Nernst coefficients, we provide a description of the nematic order parameter, proving the existence of an anisotropic Peltier-tensor beside an anisotropic conductivity tensor. Our measurements reveal that the transport nematic phenomenology is the result of the combined effect of both an anisotropic scattering time and Fermi surface distortions, pointing out that in a realistic description, abreast of the spin fluctuations also the orbital character is a fundamental ingredient. In addition, we show that nematic fluctuations universally relax in a Curie–Weiss fashion above TS in all the elasto-transport measurements and we provide evidences that nematicity must be band selective.

591 Comparison of two oHSV Vectors for the treatment of glioblastoma

BackgroundGlioblastoma multiforme (GBM) is the most common human brain cancer. Despite a well-established standard of care, the 5-year mortality rate of GBM patients is 95%, highlighting the need for innovative therapeutic interventions. A variety of oncolytic viruses, including those derived from herpes simplex virus (oHSV), have been designed for GBM therapy, but early-phase clinical trials have reported few complete responses and no evidence of durable anti-tumor immunity. Potential reasons for the lack of efficacy are limited vector potency (i.e., virulence) and the presence of a highly immunosuppressive tumor microenvironment (TME) comprised of few activated lymphocytes, large numbers of immunosuppressive myeloid cells (macrophages, myeloid derived suppressor cells [MDSCs], microglia), and an agglomerate of immunosuppressive cytokines (IL-10, VEGF, MIF, etc.).1 Herein we explore these obstacles by comparing the anti-tumor activity two different oHSV designs, an HSV-1 KOS strain derivative designated KG4:T124, and an F strain derivative designated rQNestin34.5v.1 (a similar oHSV, rQNestin34.5v.2, is currently in a phase I clinical trial for GBM).2MethodsUsing the murine syngeneic GBM models, GL261N4 and CT2A, we compared the anti-tumor activity of KG4:T124 and rQNestin34.5v1. In vitro, we evaluated the viral entry, replication capacity, and cytotoxicity of both oHSVs. In vivo, we measured the impact of both vectors on tumor progression, TME immune cell composition, and animal survival.ResultsVirus entry into cancer cells of KG4:T124 or rQNestin34.5v1 was relatively similar, but rQNestin34.5v.1 replicated more effectively and generally induced greater viral mediated cytotoxicity. In syngeneic mice, rQNestin34.5v.1 reduced orthotopic GL261N4 tumor burden and enhanced animal survival compared to KG4:T124. However, preliminary data indicate that multiple injections of KG4:T124 but not rQNestin34.5 enhance GL261N4 survival outcome. Neither oHSV impacted survival outcomes in the more pernicious CT2A model. Analysis, of either the GL261N4 or CT2A TME two days post virus administration revealed that both viruses had reduced microglia cell frequency, induced the influx of tumor associated macrophages and polymorphonuclear cells, but did not alter the frequency of monocytic MDSCs, natural killer cells, CD8+ or CD4+ T-cells.ConclusionsrQNestin34.5 had greater oncolytic activity In vivo and in vitro, but did not benefit from multiple oHSV injections. Both viruses induced similar changes in the TME immune cell composition. However, the presence of vital adaptive immune cell types within the TME was not observed at 2 days post oHSV treatment.AcknowledgementsResearch reported in this abstract was supported by the National Institutes of Health grants P01CA163205 (EAC & JCG) and 5T32CA082084-19 (JWJ).ReferencesMuller S, Kohanbash G, Liu SJ, Alvarado B, Carrera D, Bhaduri A, Watchmaker PB, Yagnik G, Di Lullo E, Malatesta M, Amankulor NM, Kriegstein AR, Lim DA, Aghi M, Okada H, Diaz A. Single-cell profiling of human gliomas reveals macrophage ontogeny as a basis for regional differences in macrophage activation in the tumor microenvironment. Genome Biol. 2017;18(1):234. Epub 2017/12/22. doi: 10.1186/s13059-017-1362-4. PubMed PMID: 29262845; PMCID: PMC5738907.Chiocca EA, Nakashima H, Kasai K, Fernandez SA, Oglesbee M. Preclinical Toxicology of rQNestin34.5v.2: An Oncolytic Herpes Virus with Transcriptional Regulation of the ICP34.5 Neurovirulence Gene. Mol Ther Methods Clin Dev 2020;17:871–93. Epub 2020/05/07. doi: 10.1016/j.omtm.2020.03.028. PubMed PMID: 32373649; PMCID: PMC7195500.

Study of the magnetic properties of Zn doped Cobalt ferrite (CoZnxFe2-xO4)

Zinc substitution is proposed as an efficient way to improve the performance of the ferrite. In this work, Zinc doped cobalt ferrite with the generic formula CoZnxFe2-xO4, with x = 0.0, 0.1, 0.3 and 0.4 were prepared by conventional ceramic technique, sintered at 1000ο C for 4 hours in air. The effect of zinc concentration on the initial permeability, Curie temperature, saturation magnetization, magnetic moment, coercivity and magnetic susceptibility was investigated. Contrary to most of the work in this subject, here Co is maintained fixed and Fe is progressively varied along with Zn. Curie temperature is found to increase initially up to 459 0C for Zn content of x = 0.1 and then decreased to 1480C for further increase of Zn content (x = 0.4). Effect of Zn on the frequency dependent initial permeability, loss factor and relative quality factor was studied. The maximum value of saturation magnetization (51.37emu/gm) was found for the sample x = 0.1 and then decreases with the increase of Zn content. Morphological and magnetic properties of the samples were studied using scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) respectively. The Zn-doped cobalt-ferrite (x = 0.1) having a high strain derivative could be a potential material for stress sensor application.

Effect of Uniaxial Strain on the Superconducting Transition Temperature in thin YBa2Cu3O7 Film

ABSTRACTThe effect of uniaxial strain e on superconducting transition temperature Tc of thin YBa2Cu3O7 film is presented. The value of TC increases linearly with compressional strain with a slope of -275K/e. Under tensile strain, Tc initially decreases to a value ∼ 0.3K below the zero-strain value and then remains constant with additional strain. In compression, the logarithmic strain derivative of Tc, (1/Tc)(dTc/de), is -3 per unit strain which is slightly less than 4–6 per unit strain observed in conventional superconductors.