Co-existence of magnetic phases in two-dimensional MXene

This study reports first synthesis of MXene-derived co-existing magnetic phases. New family of two-dimensional (2D) materials such as Ti₃C₂ namely MXene, having transition metal forming hexagonal structure with carbon atoms have attracted tremendous interest now a days. We have reported structural, optical and magnetic properties of un-doped and La-doped Ti₃C₂T_x MXene, synthesized using co-precipitation method. The lattice parameter (LP) calculated for La-MXene are a = 5.36 Å, c = 18.3 Å which are slightly different from the parent un-doped MXene (a = 5.35 Å, c = 19.2 Å), calculated from X-ray diffraction data. The doping of La⁺³ ions shrinks Ti₃C₂T_x layers perpendicular to the planes. The band gap for MXene is calculated to be 1.06 eV which is increased to 1.44 eV after doping of La⁺³ ion that shows its good semiconducting nature. The experimental results and density functional theory (DFT) calculations for magnetic properties of both the samples have been presented and discussed, indicating the co-existence of ferromagnetic-antiferromagnetic phases. The results presented here are novel and is first report on co-existence of magnetic properties of 2D carbides for potential applications in two-dimensional spintronics.     

Characterization of fluorescence of ANS-tear lipocalin complex: evidence for multiple-binding modes

ANS is widely used as a probe for locating binding sites of proteins and studying structural changes under various external conditions. However, the nature of ANS-binding sites in proteins and the accompanying changes in fluorescence properties are controversial. We examined the steady-state and time-resolved fluorescence of the ANS-protein complexes for tear lipocalin (TL) and its mutants in order to discern the origin of lifetime components via analysis that included the multiexponential decay and the model-free maximum entropy methods. Fluorescence lifetimes of ANS-TL complexes can be grouped into two species, 14.01-17.42 ns and 2.72-4.37 ns. The log-normal analyses of fluorescence spectral shapes reveal the heterogeneous nature of both long- and short-lifetime species. The constructed time-resolved emission, amplitude (TRES) and area normalized (TRANES), and decay-associated spectra are consistent with a model that includes heterogeneous modes of ANS binding with two separate lifetime components. The two lifetime components are not derived from solvent relaxation, but rather may represent different binding modes.     

Marine natural products of fungal origin

In the search for novel and bioactive molecules for drug discovery, marine-derived natural resources are becoming an important research area. Over 15 marine-derived secondary metabolites are currently in human clinical trials. Terrestrial fungi have produced many therapeutically significant molecules. However, the potential of marine fungi has only been investigated to a limited extent. This review article contains 103 marine-derived fungal metabolites and 77 references.     

A Simple Model-Free Method for Direct Assessment of Fluorescent Ligand Binding by Linear Spectral Summation

Fluorescent tagged ligands are commonly used to determine binding to proteins. However, bound and free ligand concentrations are not directly determined. Instead the response in a fluorescent ligand titration experiment is considered to be proportional to the extent of binding and, therefore, the maximum value of binding is scaled to the total protein concentration. Here, a simple model-free method is presented to be performed in two steps. In the first step, normalized bound and free spectra of the ligand are determined. In the second step, these spectra are used to fit composite spectra as the sum of individual components or linear spectral summation. Using linear spectral summation, free and bound 1-Anilinonaphthalene-8-Sulfonic Acid (ANS) fluorescent ligand concentrations are directly calculated to determine ANS binding to tear lipocalin (TL), an archetypical ligand binding protein. Error analysis shows that the parameters that determine bound and free ligand concentrations were recovered with high certainty. The linear spectral summation method is feasible when fluorescence intensity is accompanied by a spectral shift upon protein binding. Computer simulations of the experiments of ANS binding to TL indicate that the method is feasible when the fluorescence spectral shift between bound and free forms of the ligand is just 8 nm. Ligands tagged with environmentally sensitive fluorescent dyes, e.g., dansyl chromophore, are particularly suitable for this method.

Electrical,structural, and optical characterization of coal ash–PEO/PMMA blend composites

In the present work, indigenous coal ash taken from Sharigh, Balochistan, Pakistan was used to prepare polymer electrolyte films with PEO/PMMA/LiClO₄. Coal ash was first characterized by various techniques like Surface and Porosity Analysis, SEM/energy dispersive X-ray analysis (EDX), transmission electron microscopy, Fourier transform infrared (FTIR), and XRD. Chemical composition of ash was confirmed by EDX. Then, the utility of coal ash towards fabricating PEO/PMMA/LiClO₄/coal ash composites was studied in order to explore its use as an additive for polymeric blend composites. The ash incorporation into the polymeric blend composites was studied by X-ray diffraction and UV/Visible spectroscopy, while ionic conductivity measurements were undertaken by Impedance spectroscopy. Room temperature conductivity of polymeric blend composites was found to increase sharply with ash content and reached maximum at 3.3 wt.% of ash. Both direct and indirect band gap energies of polymeric blend decreased with coal ash incorporation. The decrease was at peak at 3.3 wt.% of ash. Coal ash has found to improve the performance of polymeric blends.     

Assembly of single-walled carbon nanotubes on patterns of Au nanoparticles

We report on the assembly of single-walled carbon nanotubes (SWNTs) and gold nanoparticles (NPs) hybrid structure without any surface modification of SWNTs on patterns of Au nanoparticles (NPs). Microscale Au NP patterns were created on composite self-assembled monolayer (SAM) templates of octadecanethiol (ODT) and octanedithiol (OD) through self-assembly of Au NPs via the thiol-Au chemical bond onto the OD region. On such templates, we observed extensive adhesion and strong affinity of SWNTs on the Au NPs and no SWNT on ODT. We also examined systematically the adhesion of SWNTs on ODT with varying coverage of vapour-deposited Au. We observed little SWNT attachment even when there are high-density of Au clusters on the ODT SAM. Extensive adhesion of SWNTs is observed only when the coverage of ODT by Au is almost complete. Dynamic contact angle measurements of dichlorobenzene on the ODT/Au substrates revealed a direct correlation between the surface wettability and the SWNT assembly on a molecular template.     

Theoretical modelling of physiologically stretched vessel in magnetisable stent assisted magnetic drug targetingapplication

The magnetisable stent assisted magnetic targeted drug delivery system in a physiologically stretched vessel is considered theoretically. The changes in the mechanical behaviour of the vessel are analysed under the influence of mechanical forces generated by blood pressure. In this 2D mathematical model a ferromagnetic, coiled wire stent is implanted to aid collection of magnetic drug carrier particles in an elastic tube, which has similar mechanical properties to the blood vessel. A cyclic mechanical force is applied to the elastic tube to mimic the mechanical stress and strain of both the stent and vessel while in the body due to pulsatile blood circulation. The magnetic dipole–dipole and hydrodynamic interactions for multiple particles are included and agglomeration of particles is also modelled. The resulting collection efficiency of the mathematical model shows that the system performance can decrease by as much as 10% due to the effects of the pulsatile blood circulation.