Atherogenic dyslipidemia in diabetic nephropathy: lipoprotein (a), lipid ratios and atherogenic index

Background: Atherogenic lipid profile is reported to become pronounced with onset of nephropathy. Lipid ratios also indicate atherogenic dyslipidemia. Lipoprotein (a) [(Lp(a)] considered as an independent risk factor for cardiovascular diseases (CVD), may play an important role in development and progression of nephropathy in type 2 diabetes mellitus (T2DM). The present study aimed to assess atherogenic dyslipidemia in T2DM and diabetic nephropathy patients. Methods: Total cholesterol (TC), triglycerides(Tgl), high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), Lp(a), lipid ratios: TC/HDL, Tgl/HDL, LDL/HDL, non-HDL cholesterol and atherogenic index (AI) was assessed in T2DM (n=35), diabetic nephropathy (n=30) and healthy individuals (n=30). Means of biochemical parameters were compared by ANOVA (analysis of variance). Pearson correlation was performed to study the association between parameters. Receiver operating characteristics (ROC) curve analysis was done to assess the predictive ability of the variables.Results: Atherogenic dyslipidemia with elevated Lp(a), TC, Tgl, VLDL, LDL, non-HDL cholesterol, lipid ratios, AI and low HDL levels were observed in both T2DM patients with and without nephropathy when compared to controls. Significantly high Tgl/HDL, TC/HDL and AI were observed in diabetic nephropathy when compared to T2DM. Conclusion: T2DM and diabetic nephropathy are associated with dyslipidemia which was more pronounced in diabetic nephropathy. Elevated Lp(a) levels may be considered as an independent CVD risk marker in T2DM and diabetic nephropathy patients along with atherogenic lipid ratio indicators

Observation of isotropic-dipolar to isotropic-Heisenberg crossover in Co-and Ni-substituted manganites

High-precision ac susceptibility data have been taken on the La0.7Pb0.3Mn1?y (Co, Ni)yO3 (y = 0, 0.1, 0.2 and 0.3) manganite system over a wide range of amplitudes and frequencies of the ac driving field in a temperature range that embraces the critical region near the ferromagnetic (FM)?paramagnetic (PM) phase transition (occurring at the Curie point TC). Elaborate data analysis was performed that (i) enabled the first observation of a crossover from a three-dimensional (3D; d = 3) isotropic long-range dipolar asymptotic critical behavior to a d = 3 isotropic short-range Heisenberg critical regime as the temperature is raised from TC in the compositions y 6= 0 (no such crossover is observed in the parent compound, y = 0) and (ii) brought out clearly the importance of dipole?dipole interactions between the eg electron spins and/or between eg?t2g electron spins in establishing long-range FM order in the insulating state. The final charge and spin states of Co and Ni ions, substituting for the Mn3+ and/or Mn4+ ions, are arrived at by using a scenario of substitution that is consistent not only with the present results but also with the previously published structural, thermo-gravimetric, bulk magnetization, dc magnetic susceptibility and electrical resistivity data on the same system. The marked similarity seen between the magnetic behavior of the manganite system in question and the quenched random-exchange ferromagnets, within and outside the critical region, suggests that the percolation model forms an adequate description of the FM metal-to-PM insulator transition

Chiral-fluctuations mediated helical to paramagnetic phase transition and scaling study in β-Mn type Co₈Zn₈Mn₄ chiral magnet

Abstract We report detailed magnetization and ac susceptibility studies on a chiral cubic β-Mn type Co8Zn8Mn4 alloy near the onset of magnetic ordering temperature. The Co8Zn8Mn4 alloy undergoes a complex series of temperature-driven transition from paramagnetic (PM) to helimagnetic phase through an intermediate inhomogeneous chiral fluctuations phase. The Gaussian shaped peak in χ ′ ( T , H = 0 Oe) at T H M   ≅ 343.19 K is analogous to that of the zero-field transition to long-period modulated helical state. Moreover, a pronounced field-induced anomaly in χ ′ (T, H ⩾ 500 Oe) rises quickly with field above T H M like a fingerprint, evident of a field-induced crossover into a precursor region. The in-field critical behavior characterizing a ferromagnetic-PM phase transition in the vicinity of ordering temperature confirms that Co8Zn8Mn4 chiral magnet belongs to the 3D-Heisenberg universality class. The existence of precursor region and the sizable expansion in the transition temperature, T C can be explained by the Landau equation.</jats:p

Metastable skyrmion phase stabilized in wider T–H region of β-Mn type Co₇Zn₇Mn₆ chiral magnet

Abstract We report the evolution of magnetic phase diagram ( T , H ), by accounting for the successive magnetic phase transitions in β-Mn-type Co7Zn7Mn6, a chiral magnet by an elaborate AC susceptibility magnetometry, χ(T, H). The T − H phase diagram of polycrystalline Co7Zn7Mn6 helimagnet reveals two distinct equilibrium skyrmion phases driven by fluctuations; conventional skyrmion phase (SkX) with helical ordering just below T C  ∼ 215 K and disordered skyrmion phase (DSkX) just above spin-glass region. The topological nature of SkX is due to high ( ↑↑ ) spins moment and magnetic disorder driven weak pinning effect manifesting into the stabilization of robust meta-stable skyrmion phase (MSkX) by trivial field-cooling via SkX at T S k X M  = 110 K and 150 K. We performed first-principles based density functional theory based calculations, which corroborate with the experimental structural and magnetic ground state of skyrmion-host Co7Zn7Mn6 chiral magnet.</jats:p