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

Сравнительные аналитические характеристики поликапиллярных хроматографических колонок с различным диаметром капилляров

Straight gas chromatography multicapillary columns (MCC) with 40 µm diameter capillaries (hereafter – 40 µm MCC) have been known for quite a long time and are well studied; they are used in portable gas analyzers. Some chromatographic characteristics of 25 µm MCCs, which appeared relatively recently, were also studied, while commercially available 60 and 80 µm MCCs are poorly studied. In this work the main analytical characteristics of 60 and 80 µm MCCs were determined and compared with the characteristics of 25 and 40 µm MCCs. It was shown that the maximum specific efficiency of the columns decreased with increasing column capillary diameter and is approximately 24.8, 18.2, 13.7 and 9.5 thousand theoretical plates (t.p.) per meter for 25, 40, 60 and 80 µm MCCs, respectively. It was established that the height equivalent to a theoretical plate of 60 and 80 μm MCCs was not varied significantly over a wide range of carrier gas velocities (nitrogen and helium), which allowed operating MCCs at high carrier gas flows essentially without loss of their efficiency. Moreover, for all MCCs the separation rate for peaks with a retention factor over 10 exceeded 600 t.p./s, and for peaks with a lower retention factor could be several thousand t.p./s, which is significantly higher than for conventional capillary and packed columns. It was established that it was possible to create very high carrier gas flows (up to 1000 cm3/min or more) for 60 µm MCCs and especially 80 µm MCCs at a relatively low pressure drop across the column. Therefore they can work as a part of chromatographic systems that require high carrier gas flow.Keywords: fast gas chromatography, multicapillary column, column efficiency, column height equivalent to the theoretical plate, separation rate, carrier gas velocity, carrier gas pressure.Прямые газохроматографические поликапиллярные колонки (ПКК) с капиллярами диаметром 40 мкм (далее ПКК 40 мкм) известны достаточно давно и хорошо изучены, они находят применение в составе портативных газоанализаторов. Исследованы также некоторые хроматографические характеристики появившихся относительно недавно ПКК 25 мкм, между тем коммерчески доступные ПКК 60 и 80 мкм малоизучены. В данной работе определены основные аналитические характеристики ПКК 60 и 80 мкм и проведено их сравнение с характеристиками ПКК 25 и 40 мкм. Показано, что максимальная удельная эффективность колонок уменьшается с увеличением диаметра капилляров колонок и составляет примерно 24.8, 18.2, 13.7 и 9.5 тысяч теоретических тарелок (т.т.) на метр длины для ПКК 25, 40, 60 и 80 мкм соответственно. Установлено, что высота, эквивалентная т.т., ПКК 60 и 80 мкм не сильно изменяется в широком интервале скоростей газа-носителя (азот и гелий), что позволяет эксплуатировать ПКК при высоких потоках газа-носителя без существенной потери их эффективности. При этом для всех ПКК скорость разделения для пиков с фактором удерживания более 10 превышает 600 т.т./с, а для пиков с меньшим фактором удерживания может составлять несколько тысяч т.т./с, что значительно выше, чем для обычных капиллярных и наполненных колонок. Установлено, что для ПКК 60 мкм и особенно ПКК 80 мкм возможно создание очень высоких потоков газа-носителя (до 1000 см3/мин и более) при относительно низком перепаде давлений на колонке. Поэтому они могут работать в составе хроматографических систем, требующих высокий поток газа-носителя.Ключевые слова: скоростная газовая хроматография, поликапиллярные колонки, высота, эквивалентная теоретической тарелке, скорость разделения, эффективность колонки, скорость газа-носителя, давление газа-носителя

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

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

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

CHANGE OF INDICATORS CYTOKINE PROFILE IN ADOLESCENTS DEPENDING ON THE CHARACTERISTICS OF FOOD

The analysis of cytokine status indicators in adolescents indigenous and migrant populations Khabarovsk Territory has revealed differences in their content depending on the power of quantitative and qualitative composition of the daily diet. Established ethnic characteristics cytokine profile associated primarily with the content of interferon's. Significantly higher concentration of cytokines IL-1β, IL-2, IL-4 and TNF-α and IFN-α was detected in peripheral blood serum of adolescents who are inmates of the orphanage in both ethnic groups, compared with adolescents living in a family environment. Correlations were defined between the content of proteins, fats, carbohydrates, vitamin C in diet and indicators of cytokines