Evidence for gap anisotropy in CaC6 from directional point-contact spectroscopy

We present the first results of directional point-contact spectroscopy in high-quality CaC6 samples both along the ab plane and in the c-axis direction. The superconducting order parameter Delta(0), obtained by fitting the Andreev-reflection (AR) conductance curves at temperatures down to 400 mK with the single-band 3D Blonder-Tinkham-Klapwijk model, presents two different distributions in the two directions of the main current injection, peaked at 1.35 and 1.71 meV, respectively. By ab initio calculations of the AR conductance spectra, we show that the experimental results are in good agreement with the recent predictions of gap anisotropy in CaC6.     

Superconductivity in hydrogenated carbon nanostructures

We present an application of density functional theory for superconductors to superconductivity in hydrogenated carbon nanotubes and fullerane (hydrogenated fullerene). We show that these systems are chemically similar to graphane (hydrogenated graphene) and like graphane, upon hole doping, develop a strong electron phonon coupling. This could lead to superconducting states with critical temperatures approaching 100 K, however this possibility depends crucially on if and how metallization is achieved.     

Temperature and concentration gradient effects on heat and mass transfer in micropolar fluid

We report here the development of collinear laser spectroscopy (CLS) system at VECC for the study of hyperfine spectrum and isotopic shift of stable and unstable isotopes. The facility is first of its kind in the country allowing measurement of hyperfine splitting of atomic levels using atomic beams. The CLS system is installed downstream of the focal plane of the existing isotope separator online (ISOL) facility at VECC and is recently commissioned by successfully resolving the fluorescence spectrum of the hyperfine levels in \(^{85,87}\)Rb. The atomic beams of Rb were produced by charge exchange of 8 keV Rb ion beam which were produced, extracted and transported to the charge exchange cell using the ion sources, extractor and the beam-line magnets of the ISOL facility. The laser propagating opposite to the ion / atom beam direction was allowed to interact with the atom beam and fluorescence spectrum was recorded. The experimental set-up and the experiment conducted are reported in detail. The measures needed to be carried out for improving the sensitivity to a level necessary for studying short-lived exotic nuclei have also been discussed.     

Peptide-Functionalized Silk Fibers as a Platform to Stabilize Gelatin for Use in Ingestible Devices

The combination of pharmacologic and endoscopic therapies is the gold standard for treating intestinal failures. The possibility of chemical solubility in water is mandatory for intelligent capsules. Functionalised silk fibroin with peptides and covalently linking different molecular entities to its structure make this protein a platform for preparing gels dissolving in the small and large intestine for drug delivery. In the present study, we linked a peptide containing the cell-adhesive motif Arginine–Glycine–Aspartic acid (RGD) to degummed silk fibres (DSF). Regenerated silk fibroin (RS) films obtained by dissolving functionalised DSF in formic acid were used to prepare composite gelatin. We show that such composite gelatin remains stable and elastic in the simulated gastric fluid (SGF) but can dissolve in the small and large intestines’ neutral-pH simulated intestine fluid (SIF). These findings open up the possibility of designing microfabricated and physically programmable scaffolds that locally promote tissue regeneration, thanks to bio-enabled materials based on functionalised regenerated silk.     

Correlative Cellular Mass Spectrometry Imaging and Amperometry Show Dose Dependent Changes in Lipid Composition and Exocytosis

Aberrant functioning of the proteasome has been associated with crucial pathologic conditions including neurodegeneration. Yet, the complex underlying causes at the cellular level remain unclear and there are conflicting reports of neuroprotective to neurodegenerative effects of proteasomal inhibitors such as lactacystin that are utilised as models for neurodegenerative diseases. The conflicting results may be associated with different dose regimes of lactacystin and hence we have performed a dose dependent study of the effects of lactacystin to identify concurrent changes in the cell membrane lipid profile and the dynamics of exocytosis using a combination of surface sensitive mass spectrometry and single cell amperometry. Significant changes of negatively charged lipids were associated with different lactacystin doses that showed a weak correlation with exocytosis while changes in PE and PE−O lipids showed dose dependent changes correlated with initial pore formation and total release of vesicle content respectively.