A computational study of high pressure polymorphic transformations in monazite-type LaPO4

Polymorphic transformations in LaPO₄ are investigated as a function of pressure using density functional theory (DFT) based calculations under the generalized gradient approximation. The monazite-type (P2₁/n) → barite-type (Pbnm) structural transformation is identified at 16.2 GPa and experimentally, no transformation is observed near this pressure. A discontinuity in the pressure-volume relation (of 4.16% volume discontinuity compared to the monazite structure at the same pressure) and unit-cell dimensions is observed around 28 GPa, which matches well with the previous experimental results. The pressure of discontinuity matches the DFT calculated monazite-type (P2₁/n) → post barite-type (P2₁2₁2₁) structural transformation pressure. The equation of state, single crystal elastic constants and phonon dispersion curves of the different polymorphs as a function of pressure are determined. Both the barite-type (Pbnm) and post barite-type (P2₁2₁2₁) structures are mechanically and dynamically stable at 27 GPa indicating that the monazite-type (P2₁/n) → barite-type (Pbnm) phase transformation may be hindered by a kinetic barrier. The phase transformation in monazite-type LaPO₄ is driven by a softening of the C₂₅ single crystal elastic constant. Moreover, a small displacement and tilting of PO₄ tetrahedra as a function of pressure leads to a change in the La chemical environment and creates space for the construction of LaO₁₂ polyhedra from LaO₉ due to a phase transformation.

Phase transition in metal–organic complex trans-PtCl2(PEt3)2 under pressure: insights into the molecular and crystal structure

Molecular reorientations result in structural phase transition in trans-PtCl₂(PEt₃)₂ under pressure, leading to a hydrogen bond assisted supramolecular architecture.

Phase stability, electronic structures and elastic properties of (U,Np)O2 and (Th,Np)O2 mixed oxides

Mixing enthalpies (ΔH_mix) of U_1−xNp_xO₂ and Th_1−xNp_xO₂ solid solutions are derived from atomic scale simulations based on density functional theory (DFT) employing the generalised gradient approximation corrected with an effective Hubbard parameter (U_eff).

Liquid like nucleation in free-standing nanoscale films

The concept of a critical nucleus size (r*) is of pivotal importance in phase transformations involving nucleation and growth. The current investigation pertains to crystallization in nanoscale thin films and study of the same using high resolution lattice fringe imaging (HRLFI) and finite element simulations. Using the CuZrAl bulk metallic glass system as a model system for this study, we demonstrate a liquid like nucleation behaviour in nanoscale free-standing films upon heating. The r* for the formation of the Cu₁₀Zr₇ phase in thin films (of decreasing thickness) approaches that of the r* for the formation of the crystal from a liquid (i.e.). Working in the nucleation dominant regime, we introduce the concept of 'depth sensitive lattice fringe imaging'. The thickness of the film is determined by electron energy loss spectroscopy and the strain energy of the system is computed using finite element computations.

Giant Rashba effect at the topological surface of PrGe revealing antiferromagnetic spintronics

Rashba spin-orbit splitting in the magnetic materials opens up a new perspective in the field of spintronics. Here, we report a giant Rashba spin-orbit splitting on the PrGe [010] surface in the paramagnetic phase with Rashba coefficient α R  = 5 eVÅ. We find that α R can be tuned in this system as a function of temperature at different magnetic phases. Rashba type spin polarized surface states originates due to the strong hybridization between Pr 4f states with the conduction electrons. Significant changes observed in the spin polarized surface states across the magnetic transitions are due to the competition between Dzyaloshinsky-Moriya interaction and exchange interaction present in this system. Presence of Dzyaloshinsky-Moriya interaction on the topological surface give rise to Saddle point singularity which leads to electron-like and hole-like Rashba spin split bands in the [Formula: see text] and [Formula: see text] directions, respectively. Supporting evidences of Dzyaloshinsky-Moriya interaction have been obtained as anisotropic magnetoresistance with respect to field direction and first-order type hysteresis in the X-ray diffraction measurements. A giant negative magnetoresistance of 43% in the antiferromagnetic phase and tunable Rashba parameter with temperature makes this material a suitable candidate for application in the antiferromagnetic spintronic devices.

Excess of exercise increases the risk of atrial fibrillation

An interesting and still not well-understood example for old medical wisdom "Sola dosis facit venenum" is the increased prevalence of atrial fibrillation (AF) in athletes. Numerous studies have shown a fourfold to eightfold increased risk of AF in athletes compared to the normal population. Analysis of the existing data suggests a dose-dependent effect of exercise. Moderate exercise seems to have a protective effect and decreases the risk of AF, whereas excessive exercise seems to increase the risk of AF. The described cases illustrate clinical manifestations within the spectrum of AF in elderly athletes, that is, exercise-induced AF, vagal AF, chronic AF, and atrial flutter. As the arrhythmia worsened quality of life and exercise capacity in all patients, recovery of sinus rhythm was desired in all described cases. As the atrial disease was advanced on different levels, different treatment regimes were applied. Lifestyle modification and temporary anti-arrhythmic drug therapy could stabilize sinus rhythm in one patient, whereas others needed radiofrequency ablation to achieve a stable sinus rhythm. The patient with the most advanced atrial disease necessitated anti-arrhythmic drug therapy and another left atrial ablation. All described patients remained in sinus rhythm during the long-term follow-up.

A computational study on the superionic behaviour of ThO2

This study reports the density functional theory (DFT) and classical molecular dynamics (MD) study of the lattice dynamical, mechanical and anionic transport behaviours of ThO₂ in the superionic state. DFT calculations of phonon frequencies were performed at different levels of approximation as a function of isotropic dilation (ε) in the lattice parameter. With the expansion of the lattice parameter, there is a softening of B_1u and E_u phonon modes at the X symmetry point of the Brillouin zone. As a result of the nonlinear decrease at the X point, the B_1u and E_u phonon modes cross each other at ε = 0.03, which is associated with a sharp increase in the narrow peak of the phonon density of states, signifying a higher occupation and hence a higher coupling of these modes at high temperatures. The mode crossing also indicates anionic conductivity in the 〈001〉 direction leading to occupation of interstitial sites. Moreover, MD and nudged elastic band calculated diffusion barriers indicate that 〈001〉 is the easy direction for anion migration in the normal and superionic states. With a further increase in the lattice parameter, the B_1u mode continues to soften and becomes imaginary at a strain (ε) of 0.036 corresponding to a temperature of 3430 K. The calculated temperature variation of single crystal elastic constants shows that the fluorite phase of ThO₂ remains elastically stable up to the superionic regime, though the B_1u phonon mode is imaginary in that state. This leads to anionic disorder at elevated temperatures. Tracking of anion positions in the superionic state as a function of time in MD simulations suggests a hopping model in which the oxygen ions migrate from one tetrahedral site to another via octahedral interstitial sites.

Luminescence of undoped and Eu3+ doped nanocrystalline SrWO4 scheelite: time resolved fluorescence complimented by DFT and positron annihilation spectroscopic studies

Effect of annealing temperature on photophysical characteristics of pure and SrWO₄:Eu³⁺ nanoparticles were investigated and the changes observed correlated with density function theory (DFT) and positron annihilation lifetime spectroscopy (PALS).

Characterization and validation of point mutation in exon 19 of CACNA2D1 gene in Karan Fries (Bos taurus x Bos indicus) cattle

The objective of this study was to characterize and validate the candidate point mutation in Calcium channel, voltage-dependent, alpha-2/ delta subunit 1 (CACNA2D1) gene in Karan Fries (Bos taurus x Bos indicus) cattle. The CACNA2D1 gene reported as one of the potential candidate gene influencing Somatic cell Score and Mastitis. A PCR product of 249 bp amplifying the exon 19 and partial 18 and 19 intronic region of CACNA2D1 gene was digested with Hae III restriction enzyme to screen the reported point mutation. A monomorphic banding pattern with genotype AA was found in Karan Fries cattle. Sequencing was also carried out to characterize and explore insilico screened mutation in the nucleotide sequence of a particular region. The result indicates highly conserved sequence in Karan Fries cattle. The Phylogenetic tree revealed that Karan Fries cattle were closer to Bos taurus cattle, Bos mutus (Yak), and Bison bison (American buffalo) compared to other species.

Anticancer Effects of Extracts from the Fruit of Morinda Citrifolia (Noni) in Breast Cancer Cell Lines

Morinda citrifolia L. (NONI) fruits have been used for thousands of years for the treatment of many health problems including cancer, cold, diabetes, flu, hypertension, and pain. Plant extracts have reported several therapeutic benefits, but extraction of individual compound from the extract often exhibits limited clinical utility as the synergistic effect of various natural ingredients gets lost. They generally constitute polyphenols and flavonoids. Studies have suggested that these phytochemicals, especially polyphenols, display high antioxidant properties, which help to reduce the risk of degenerative diseases, such as cancer and cardiovascular diseases. Several in-vitro and in-vivo studies have shown that Noni fruits have antioxidant, anti-inflammatory, anti-dementia, liver-protective, anticancer, analgesic, and immunomodulatory effects. Till date about 7 in vitro cancer studies have been done, but a detailed in vitro study including cell cycle and caspase activation assay on breast cancer cell line has not been done. In the present study different Noni fruit fractions have tested on cancer cell lines MCF-7, MDA-MB-231 (breast adenocarcinoma) and one non-cancer cell line HEK-293 (Human embryonic kidney). Out of which ethylacetate extract showed a higher order of in vitro anticancer activity profile. The ethylacetate extract strongly inhibited the proliferation of MCF-7, MDA-MB-231 and HEK-293 cell lines with IC50 values of 25, 35, 60 µg/ml respectively. The extract showed increase in apoptotic cells in MCF-7 and MDA-MB-231 cells and arrested the cell cycle in the G1/S phase in MCF-7 and G0/G1 phase in MDA-MB-231 cells. Noni extract also decreases the intracellular ROS generation and mitochondrial membrane potential.