Effect of chemical substitution in Rh17S15

Rh17S15 has recently been shown to be a strongly correlated superconductor with a transition temperature of 5.4 K. In order to understand the nature of strong correlations we study the effect of substitution of some of the Rh and S atoms by other elements such as Fe, Pd, Ir and Ni on the Rh side and Se on the S side in this work. We find that while substitution of Ir and Se lower the transition temperature considerably, that of Fe, Pd and Ni destroy superconductivity down to 1.5 K. The resistivity data in these doped samples show a minimum which is presumably disorder induced. A reduction of Tc is always accompanied by a reduction of electron correlations as deduced from heat capacity and magnetization data. Interestingly, the Fe doped sample shows some possible antiferromagnetic ordering at low temperatures.Comment: Published in Journal of Physics Condensed Matte

Lifshitz transitions and quasiparticle de-renormalization in YbRh2_2Si2_2

We study the effect of magnetic fields up to 15 T on the heavy fermion state of YbRh$_2$Si$_2$ via Hall effect and magnetoresistance measurements down to 50 mK. Our data show anomalies at three different characteristic fields. We compare our data to renormalized band structure calculations through which we identify Lifshitz transitions associated with the heavy fermion bands. The Hall measurements indicate that the de-renormalization of the quasiparticles, {\it i.e} the destruction of the local Kondo singlets, occurs smoothly while the Lifshitz transitions occur within rather confined regions of the magnetic field.Comment: 7 pages, 5 figure

Strongly correlated superconductivity in Rh<SUB>17</SUB>S<SUB>15</SUB>

In this work, we show the highly correlated nature of the superconductor Rh17S15 via transport, magnetization and heat capacity measurements. In particular, we will discuss resistivity, susceptibility, heat-capacity and upper critical field studies on a polycrystalline Rh17S15 sample which exhibits superconductivity below 5.4 K. Detailed studies suggest that the superconductivity in this compound arises from strongly correlated charge carriers presumably due to the high density of states of Rh d-bands at the Fermi level. Moreover, the Hall coefficient shows a sign change and increases at low temperature before the sample becomes a superconductor below 5.4 K

Vortex phase diagram in weakly pinned Rh<SUB>17</SUB>S<SUB>15</SUB>

A vortex phase diagram of the strongly correlated superconductor Rh17S15 has been constructed via exploration of the anomalous variations in critical current density extracted from ac and dc magnetization measurements. The isofield in-phase ac susceptiblity data reveal the presence of multiple steps at different fields. The dc magnetisation hysteresis loops show the presence of a very broad fishtail commencing deep inside the mixed state and lasting upto Hc2. We have also analysed the scan rate dependence of the hysteresis width in the vibrating sample magnetometer data with a view to distinguish between the different possible order-disorder transformations in the flux line lattice

Interplay between Kondo suppression and Lifshitz transitions in YbRh2_2Si2_2 at high magnetic fields

We investigate the magnetic field dependent thermopower, thermal conductivity, resistivity and Hall effect in the heavy fermion metal YbRh2Si2. In contrast to reports on thermodynamic measurements, we find in total three transitions at high fields, rather than a single one at 10 T. Using the Mott formula together with renormalized band calculations, we identify Lifshitz transitions as their origin. The predictions of the calculations show that all experimental results rely on an interplay of a smooth suppression of the Kondo effect and the spin splitting of the flat hybridized bands.Comment: 5 pages, 4 figure

Integrating genetic and oral histories of Southwest Indian populations

India is home to thousands of ethno-linguistically distinct groups, many maintaining strong self-identities that derive from oral traditions and histories. However, these traditions and histories are only partially documented and are in danger of being lost over time. More recently, genetic studies have established the existence of ancestry gradients derived from both western and eastern Eurasia as well as evidence of practices such as endogamy and consanguinity, revealing complexity in the regional population structure with consequences for the health landscape of local populations. Despite the increase in genome-wide data from India, there is still sparse sampling across finer-scale geographic regions leading to gaps in our understanding of how and when present-day genetic structure came into existence. To address the gaps in genetic and oral histories, we analyzed whole-genome sequences of 70 individuals from Southwest India identifying as Bunt, Kodava, and Nair—populations that share unique oral histories and origin narratives—and 78 recent immigrants to the United States with Kodava ancestry as part of a community-led initiative. We additionally generated genome-wide data from 10 individuals self-identifying as Kapla, a population from the same region that is socio-culturally different to the other three study populations. We supplemented existing but limited anthropological records on these populations with oral history accounts narrated by community members and non-member contacts during sampling and subsequent community engagement. Overall, we find that components of genetic ancestry are relatively homogeneous among the Bunt, Kodava, and Nair populations and comparable to neighboring populations in India, which motivates further investigation of non-local origin narratives referenced in their oral histories. A notable exception is the Kapla population, with a higher proportion of ancestry represented in the Onge from the Andaman Islands, similar to several South Indian tribal populations. Utilizing haplotype-based methods, we find latent genetic structure across South India, including the sampled populations available under aCC-BY-NC-ND 4.0 International license.was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made bioRxiv preprint doi: https://doi.org/10.1101/2022.07.06.498959; this version posted July 7, 2022. The copyright holder for this preprint (which 2 from Southwest India, suggesting more recent population structure between geographically proximal populations in the region. This study represents an attempt for community-engaged anthropological and genetic investigations in India and presents results from both sources, underscoring the need to recognize that oral and genetic histories should not be expected to overlap. Ultimately, oral traditions and unique self-identities, such as those held close by some of the study populations, warrant more community-driven anthropological investigations to better understand how they originate and their relationship to genetic histories

Monoubiquitination of syntaxin 3 leads to retrieval from the basolateral plasma membrane and facilitates cargo recruitment to exosomes

Syntaxin 3 (Stx3), a SNARE protein located and functioning at the apical plasma membrane of epithelial cells, is required for epithelial polarity. A fraction of Stx3 is localized to late endosomes/lysosomes, although how it traffics there and its function in these organelles is unknown. Here we report that Stx3 undergoes monoubiquitination in a conserved polybasic domain. Stx3 present at the basolateral—but not the apical—plasma membrane is rapidly endocytosed, targeted to endosomes, internalized into intraluminal vesicles (ILVs), and excreted in exosomes. A nonubiquitinatable mutant of Stx3 (Stx3-5R) fails to enter this pathway and leads to the inability of the apical exosomal cargo protein GPRC5B to enter the ILV/exosomal pathway. This suggests that ubiquitination of Stx3 leads to removal from the basolateral membrane to achieve apical polarity, that Stx3 plays a role in the recruitment of cargo to exosomes, and that the Stx3-5R mutant acts as a dominant-negative inhibitor. Human cytomegalovirus (HCMV) acquires its membrane in an intracellular compartment and we show that Stx3-5R strongly reduces the number of excreted infectious viral particles. Altogether these results suggest that Stx3 functions in the transport of specific proteins to apical exosomes and that HCMV exploits this pathway for virion excretion

Role of Interaction and Nucleoside Diphosphate Kinase B in Regulation of the Cystic Fibrosis Transmembrane Conductance Regulator Function by cAMP-Dependent Protein Kinase A

Cystic fibrosis results from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-dependent protein kinase A (PKA) and ATP-regulated chloride channel. Here, we demonstrate that nucleoside diphosphate kinase B (NDPK-B, NM23-H2) forms a functional complex with CFTR. In airway epithelia forskolin/IBMX significantly increases NDPK-B co-localisation with CFTR whereas PKA inhibitors attenuate complex formation. Furthermore, an NDPK-B derived peptide (but not its NDPK-A equivalent) disrupts the NDPK-B/CFTR complex in vitro (19-mers comprising amino acids 36-54 from NDPK-B or NDPK-A). Overlay (Far-Western) and Surface Plasmon Resonance (SPR) analysis both demonstrate that NDPK-B binds CFTR within its first nucleotide binding domain (NBD1, CFTR amino acids 351-727). Analysis of chloride currents reflective of CFTR or outwardly rectifying chloride channels (ORCC, DIDS-sensitive) showed that the 19-mer NDPK-B peptide (but not its NDPK-A equivalent) reduced both chloride conductances. Additionally, the NDPK-B (but not NDPK-A) peptide also attenuated acetylcholine-induced intestinal short circuit currents. In silico analysis of the NBD1/NDPK-B complex reveals an extended interaction surface between the two proteins. This binding zone is also target of the 19-mer NDPK-B peptide, thus confirming its capability to disrupt NDPK-B/CFTR complex. We propose that NDPK-B forms part of the complex that controls chloride currents in epithelia