Possibility to realize spin-orbit-induced correlated physics in iridium fluorides

Recent theoretical predictions of "unprecedented proximity" of the electronic ground state of iridium fluorides to the SU(2) symmetric $j_{\mathrm{eff}}=1/2$ limit, relevant for superconductivity in iridates, motivated us to investigate their crystal and electronic structure. To this aim, we performed high-resolution x-ray powder diffraction, Ir L$_3$-edge resonant inelastic x-ray scattering, and quantum chemical calculations on Rb$_2$[IrF$_6$] and other iridium fluorides. Our results are consistent with the Mott insulating scenario predicted by Birol and Haule [Phys. Rev. Lett. 114, 096403 (2015)], but we observe a sizable deviation of the $j_{\mathrm{eff}}=1/2$ state from the SU(2) symmetric limit. Interactions beyond the first coordination shell of iridium are negligible, hence the iridium fluorides do not show any magnetic ordering down to at least 20 K. A larger spin-orbit coupling in iridium fluorides compared to oxides is ascribed to a reduction of the degree of covalency, with consequences on the possibility to realize spin-orbit-induced strongly correlated physics in iridium fluorides

Electronic signature of the vacancy ordering in NbO (Nb3O3)

We investigated the electronic structure of the vacancy-ordered 4d-transition metal monoxide NbO (Nb3O3) using angle-integrated soft- and hard-x-ray photoelectron spectroscopy as well as ultra-violet angle-resolved photoelectron spectroscopy. We found that density-functional-based band structure calculations can describe the spectral features accurately provided that self-interaction effects are taken into account. In the angle-resolved spectra we were able to identify the so-called vacancy band that characterizes the ordering of the vacancies. This together with the band structure results indicates the important role of the very large inter-Nb-4d hybridization for the formation of the ordered vacancies and the high thermal stability of the ordered structure of niobium monoxide

Origin of magnetic moments and presence of a resonating valence bond state in Ba2_2YIrO6_6

While it was speculated that 5$d^4$ systems would possess non-magnetic $J$~=~0 ground state due to strong Spin-Orbit Coupling (SOC), all such systems have invariably shown presence of magnetic moments so far. A puzzling case is that of Ba$_2$YIrO$_6$, which in spite of having a perfectly cubic structure with largely separated Ir$^{5+}$ ($d^4$) ions, has consistently shown presence of weak magnetic moments. Moreover, we clearly show from Muon Spin Relaxation ($\mu$SR) measurements that a change in the magnetic environment of the implanted muons in Ba$_2$YIrO$_6$ occurs as temperature is lowered below 10~K. This observation becomes counterintuitive, as the estimated value of SOC obtained by fitting the RIXS spectrum of Ba$_2$YIrO$_6$ with an atomic $j-j$ model is found to be as high as 0.39~eV, meaning that the system within this model is neither expected to possess moments nor exhibit temperature dependent magnetic response. Therefore we argue that the atomic $j-j$ coupling description is not sufficient to explain the ground state of such systems, where despite having strong SOC, presence of hopping triggers delocalisation of holes, resulting in spontaneous generation of magnetic moments. Our theoretical calculations further indicate that these moments favour formation of spin-orbital singlets in the case of Ba$_2$YIrO$_6$, which is manifested in $\mu$SR experiments measured down to 60~mK.Comment: 20 Pages, 7 Figure

Increasing and decreasing droplets velocity in micro channels

This paper deals with a specific aspect of non miscible liquid-liquid systems in microfluidic. For Chemical Engineering applications, the main constraints of functioning lies in the droplets velocity and frequency. Furthermore, the material used and the composition of the fluids is often imposed by the chemistry of the system (material resistance, fluids composition) and there is no possibility of adding other compound (surfactants for example). A technique under evaluation is presented: by using secondary channels and pumps, it is possible to increase or decrease at will the droplets velocity after they have been generated. Some experimental results are presented and discussed, including the possible limits of such an approach

Live Birth of a Healthy Child in a Couple with Identical mtDNA Carrying a Pathogenic c.471_477delTTTAAAAinsG Variant in the MOCS2 Gene.

Molybdenum cofactor deficiency type B (MOCODB; #252160) is an autosomal recessive metabolic disorder that has only been described in 37 affected patients. In this report, we describe the presence of an in-frame homozygous variant (c.471_477delTTTAAAAinsG) in the MOCS2 gene in an affected child, diagnosed with Ohtahara syndrome according to the clinical manifestations. The analysis of the three-dimensional structure of the protein and the amino acid substitutions suggested the pathogenicity of this mutation. To prevent transmitting this mutation to the next generation, we used preimplantation genetic testing for the monogenic disorders (PGT-M) protocol to select MOCS2 gene mutant-free embryos for transfer in an in vitro fertilization (IVF) program. As a result, a healthy child was born. Interestingly, both parents of the proband shared an identical mitochondrial (mt) DNA control region, assuming their close relationship and thus suggesting that both copies of the nuclear rare variant c.471_477delTTTAAAAinsG may have been transmitted from the same female ancestor. Our estimation of the a priori probability of meeting individuals with the same mtDNA haplotype confirms the assumption of a possible distant maternal relationship among the proband's direct relatives

Multiple-length-scale elastic instability mimics parametric resonance of nonlinear oscillators

Spatially confined rigid membranes reorganize their morphology in response to the imposed constraints. A crumpled elastic sheet presents a complex pattern of random folds focusing the deformation energy while compressing a membrane resting on a soft foundation creates a regular pattern of sinusoidal wrinkles with a broad distribution of energy. Here, we study the energy distribution for highly confined membranes and show the emergence of a new morphological instability triggered by a period-doubling bifurcation. A periodic self-organized focalization of the deformation energy is observed provided an up-down symmetry breaking, induced by the intrinsic nonlinearity of the elasticity equations, occurs. The physical model, exhibiting an analogy with parametric resonance in nonlinear oscillator, is a new theoretical toolkit to understand the morphology of various confined systems, such as coated materials or living tissues, e.g., wrinkled skin, internal structure of lungs, internal elastica of an artery, brain convolutions or formation of fingerprints. Moreover, it opens the way to new kind of microfabrication design of multiperiodic or chaotic (aperiodic) surface topography via self-organization.Comment: Submitted for publicatio

Ceria nanoparticles as promoters of CO2 electroreduction on Ni YSZ An efficient preparation strategy and insights into the catalytic promotion mechanism

Since many decades nickel yttria stabilized zirconia cermet Ni YSZ has been the most frequently used fuel electrode material for high temperature solid oxide cells SOCs . However, in recent years there has been considerable effort to improve the Ni YSZ performance through surface engineering. In this work, we report a simple strategy to apply nanosized un doped CeOx and Ni doped NiCeOy ceria particles into porous Ni YSZ cermet electrodes via infiltration from hexane solution. Detailed characterization of the particles in their solution revealed differences in the ease of agglomeration, with NiCeOy nanoparticles being better dispersed and thus forming smaller aggregates. This property is critical for the effectiveness of the solution in filling the pores of Ni YSZ cermet and the consequent ceria deposition. In particular, morphological and microstructural characterization reveals that NiCeOy nanoparticles decorate uniformly the pores of Ni YSZ backbone, deep up to the interface with the electrolyte. More importantly, this can be done with relatively high ceria loading per infiltration co firing step. Electrochemical tests demonstrate that infiltrated Ni YSZ fuel electrodes have improved I V performance in CO2 electrolysis as compared to pristine Ni YSZ. Synchrotron based operando NAP XPS experiments using both soft and tender X rays revealed the formation of an ultrathin Ni Ce3 layer on the electrode surface, which can rationalize the ameliorated CO2 electrolysis performanc

Safety Study of an Original Mesenchymal Stromal Cell Secretome-Based Medicinal Product for Spermatogenesis Restoration

Currently, there are no effective and safe medicinal products for idiopathic male infertility. Previous studies in two animal models of infertility (short-term cryptorchidism in rats and doxorubicin-induced testicular injury in mice) have shown the effectiveness of an originator medicinal product based on the mesenchymal stromal cell (MSC) secretome.The aim of the study was to evaluate the toxicity profile of the MSC secretome-based medicinal product in rats after local intratesticular or intramuscular administration.Materials and methods. The MSC secretome is a combination of factors secreted by MSCs in low-glucose Dulbecco’s modified Eagle’s medium (DMEM-LG) for MSC conditioning. In the single-dose toxicity study, the MSC secretome-based medicinal product was injected under the testicular tunica albuginea of male Wistar rats (15 per group) at doses of 15 and 25 relative units (RU) per animal, which are 1.5 and 2.5 times higher than the therapeutic dose (10 RU). In the repeat-dose toxicity study, male Wistar rats (10 per group) received intramuscular thigh injections of the medicinal product on days 1, 6, and 12 at doses of 15 and 25 RU per animal. The local tolerance study involved histopathological examination of the testes and thighs at the injection site. All studies included control groups of intact animals and animals similarly injected with blank DMEM-LG. The early follow-up period was 14 days, and the late follow-up period was 42 days.Results. The rats showed no changes in the general condition after single and repeated doses of the MSC secretome-based medicinal product. Single subtunical doses induced moderate irritation; its signs included pathological changes in individual seminiferous tubules: epithelial atrophy (70% of the animals on day 14; 55% at late follow-up) and sperm stasis (70% of the animals). Similar changes were observed in the blank DMEM-LG group (up to 80% of the animals). There were no pathological changes in the tissues after repeated injections. A transient increase in alkaline phosphatase activity was detected in animals after their third intramuscular injection at a dose of 25 RU; the other biochemical parameters were normal in all study groups.Conclusions. The MSC secretome-based medicinal product has a favourable safety profile following both intratesticular and intramuscular administration, as it does not cause any permanent changes in the studied organs and tissues