Separation of Cholesterol from other Steroids Using Molecularly Imprinted Polymer Prepared by Seeded Suspension Polymerization

Micron-sized particles of cholesterol-imprinted polymers were synthesized by seeded suspension polymerization in a mixture of 2-propanol and water using polystyrene microbeads as the seeds. Methacrylic acid was employed as the functional monomer to form complexes with template (cholesterol), along with ethylene glycol dimethacrylate as the crosslinker. After removal of template molecules, the columns ( H=15 cm, Di= 0.46 cm ) packed with cholesterol-imprinted polymers were effective for the chromatographic separation of cholesterol from other steroids. When the sample of steroids was eluted isocratically at a flow-rate of Q = 0.5 mL min-1, using a mixture of acetonitrile and water (Ψ= 95:5) as the mobile phase, the retention times for estrone, -estradiol and cholesterol were respectively τ = 5.3, 12.3 and 17.2 min. The average retention times were = 5.3, 10.9 and 16.7 min respectively for estrone, progesterone and cholesterol in samples. The separation was based on the specific binding of cholesterol to recognition sites formed on the imprinted polymers. A separation factor of 1.6 for cholesterol and -estradiol was obtained. The chromatographic efficiency was dependent on the mobile phase composition. Reducing the water content in the non-polar mobile phase to zero could significantly enhance the separation. Compared with particles from bulk polymerization, the column packed with cholesterol-imprinted particles from seeded suspension polymerization had a higher chromatographic efficiency and the advantage of microanalysi

The relative efficacy of different strain combinations of lactic acid bacteria in the reduction of populations of Salmonella enterica Typhimurium in the livers and spleens of mice

Multispecies probiotics have been reported to be more effective than monostrain probiotics in health promoting for the host. In this study, 12 lactic acid bacteria (LAB) strains were selected based on the level of induction of tumor necrosis factor (TNF)-alpha in RAW 264.7 macrophage cells. Their adherence to Caco-2 cells and inhibitory effects on Salmonella invasion of Caco-2 cells were compared. Strains with different probiotic properties were then combined and BALB/c mice were fed with LAB strains for 63 days; then the mice were challenged with Salmonella on day 64. For Salmonella-unchallenged mice that received a multistrain combination of LAB strains that have greater TNF-alpha production in macrophages, greater adherence and inhibit Salmonella invasion of Caco-2 cells to a greater extent, their peritoneal macrophages had greater phagocytic activity. For Salmonella-challenged mice, a significant reduction of Salmonella cells in the livers and spleens of the mice was observed 8 days post challenge. The addition of 12% skim milk powder together with LAB strain combinations significantly enhanced the reduction of Salmonella cells in the mice livers and spleens. In conclusion, we have shown that LAB strain combinations with particular probiotic properties when fed to mice can inhibit Salmonella invasion of the liver and spleen

Marginal Fermi liquid analysis of 300 K reflectance of Bi2Sr2CaCu2O8+x

We use 300 K reflectance data to investigate the normal-state electrodynamics of the high temperature superconductor Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ over a wide range of doping levels. The data show that at this temperature the free carriers are coupled to a continuous spectrum of fluctuations. Assuming the Marginal Fermi Liquid (MFL) form as a first approximation for the fluctuation spectrum, the doping-dependent coupling constant $\lambda (p)$ can be estimated directly from the slope of the reflectance spectrum. We find that $\lambda (p)$ decreases smoothly with the hole doping level, from underdoped samples with $p=0.103$ ($T_c = 67$ K) where $\lambda (p)= 0.93$ to overdoped samples with $p=0.226$, ($T_c= 60$ K) where $\lambda(p)= 0.53$. An analysis of the intercept and curvature of the reflectance spectrum shows deviations from the MFL spectrum symmetrically placed at the optimal doping point $p=0.16$. The Kubo formula for the conductivity gives a better fit to the experiments with the MFL spectrum up to 2000 cm$^{-1}$ and with an additional Drude component or an additional Lorentz component up to 7000 cm$^{-1}$. By comparing three different model fits we conclude that the MFL channel is necessary for a good fit to the reflectance data. Finally, we note that the monotonic variation of the reflectance slope with doping provides us with an independent measure of the doping level for the Bi-2212 system.Comment: 11 pages, 11 figure

Angle-resolved photoemission in doped charge-transfer Mott insulators

A theory of angle-resolved photoemission (ARPES) in doped cuprates and other charge-transfer Mott insulators is developed taking into account the realistic (LDA+U) band structure, (bi)polaron formation due to the strong electron-phonon interaction, and a random field potential. In most of these materials the first band to be doped is the oxygen band inside the Mott-Hubbard gap. We derive the coherent part of the ARPES spectra with the oxygen hole spectral function calculated in the non-crossing (ladder) approximation and with the exact spectral function of a one-dimensional hole in a random potential. Some unusual features of ARPES including the polarisation dependence and spectral shape in YBa2Cu3O7 and YBa2Cu4O8 are described without any Fermi-surface, large or small. The theory is compatible with the doping dependence of kinetic and thermodynamic properties of cuprates as well as with the d-wave symmetry of the superconducting order parameter.Comment: 8 pages (RevTeX), 10 figures, submitted to Phys. Rev.

Structural optimisation of random discontinuous fibre composites: Part 2 - case study

This is the second paper in a two part series presenting the development of a stiffness optimisation algorithm to intelligently optimise the fibre architecture of discontinuous fibre composites. A Multi-Criteria Decision Making (MCDM) strategy is used to select parameters associated with the fibre architecture, to produce components that satisfy stiffness, cost and mass criteria. The model has been successfully demonstrated using an automotive spare wheel well geometry, which shows that a highly optimised discontinuous fibre composite solution can compete against a continuous fabric counterpart in terms of specific stiffness, whilst presenting an opportunity for significant cost reduction. This could potentially lead to the application of composite materials into new areas where cost has previously been prohibitive

Acetogenin and Prenylated Flavonoids from Helminthostachys zeylanica with Inhibitory Activity on Superoxide Generation and Elastase Release by Neutrophils

One new acetogenin, 6-hydroxy-8-pentadecyloxocane-2,7-dione (1), and four new prenylated flavonoids, 4 '' a,5 '',6 '',7 '',8 '',8 '' a-hexahydro-5,3',4'-trihydroxy-5 '',5 '',8 '' a-trimethyl-4H-chromeno[2 '',3 '': 7,6] flavone (2), 4 '' a,5 '',6 '',7 '',8 '',8 '' a-hexahydro5,3', 4',-trihydroxy-5 '',5 '',8 '' a-trimethyl-4Hchromeno[2 '', 3 '': 7,8] flavone (3), 2-(3,4-dihydroxyphenyl)6-((2,2-dimethyl-6-methylenecyclohexyl) methyl)-5,7-dihydroxy-chroman-4-one (4), and 2-(3,4-dihydroxy-2-[(2,6,6-trimethylcyclohex-2-enyl) methyl] phenyl)-3,5,7-trihydroxy-4H-chromen-4-one (5), together with six known compounds, were isolated and purified from the rhizomes of Helminthostachys zeylanica by column chromatography and high performance liquid chromatography (HPLC) via bioactivity-guided fractionation isolation. The structures of the new isolates were elucidated by spectroscopic methods. Compounds 1, 3, and 5 showed inhibitory activities on either superoxide anion generation or elastase release by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine/cytochalasin B (FMLP/CB)

Role of Inter-Electron Interaction in the Pseudo-Gap Opening in High T c_c Tunneling Experiments

The analysis of tunneling experiments showing the pseudogap type behavior is carried out based on the idea of the renormalization of density of states due to the inter-electron interaction in the Cooper channel (superconducting fluctuations contribution in tunneling current). It is demonstrated that the observed kink of the zero-bias conductance $G(0,T)$ of $YBaCuO/Pb$ junctions in the vicinity of $T_c$ can be explained in terms of fluctuation theory in a quite wide range of temperature above $T_c$, using the values of microscopic parameters of the $YBaCuO$ electron spectrum taken from independent experiments. The approach proposed also permits to explain qualitatively the shape of the tunneling anomalies in $G(V,T)$ and gives a correct estimate for the pseudogap position and amplitude observed in the experiments on $BiSrCaCuO$ junctions.Comment: 5 pages, 3 figure

Effective Actions and Phase Fluctuations in d-wave Superconductors

We study effective actions for order parameter fluctuations at low temperature in layered d-wave superconductors such as the cuprates. The order parameter lives on the bonds of a square lattice and has two amplitude and two phase modes associated with it. The low frequency spectral weights for amplitude and relative phase fluctuations is determined and found to be subdominant to quasiparticle contributions. The Goldstone phase mode and its coupling to density fluctuations in charged systems is treated in a gauge-invariant manner. The Gaussian phase action is used to study both the $c$-axis Josephson plasmon and the more conventional in-plane plasmon in the cuprates. We go beyond the Gaussian theory by deriving a coarse-grained quantum XY model, which incorporates important cutoff effects overlooked in previous studies. A variational analysis of this effective model shows that in the cuprates, quantum effects of phase fluctuations are important in reducing the zero temperature superfluid stiffness, but thermal effects are small for $T << T_c$.Comment: Some numerical estimates corrected and figures changed. to appear in PRB, Sept.1 (2000

Dynamics of multipartite quantum correlations under decoherence

Quantum discord is an optimal resource for the quantification of classical and non-classical correlations as compared to other related measures. Geometric measure of quantum discord is another measure of quantum correlations. Recently, the geometric quantum discord for multipartite states has been introduced by Jianwei Xu [arxiv:quant/ph.1205.0330]. Motivated from the recent study [Ann. Phys. 327 (2012) 851] for the bipartite systems, I have investigated global quantum discord (QD) and geometric quantum discord (GQD) under the influence of external environments for different multipartite states. Werner-GHZ type three-qubit and six-qubit states are considered in inertial and non-inertial settings. The dynamics of QD and GQD is investigated under amplitude damping, phase damping, depolarizing and flipping channels. It is seen that the quantum discord vanishes for p>0.75 in case of three-qubit GHZ states and for p>0.5 for six qubit GHZ states. This implies that multipartite states are more fragile to decoherence for higher values of N. Surprisingly, a rapid sudden death of discord occurs in case of phase flip channel. However, for bit flip channel, no sudden death happens for the six-qubit states. On the other hand, depolarizing channel heavily influences the QD and GQD as compared to the amplitude damping channel. It means that the depolarizing channel has the most destructive influence on the discords for multipartite states. From the perspective of accelerated observers, it is seen that effect of environment on QD and GQD is much stronger than that of the acceleration of non-inertial frames. The degradation of QD and GQD happens due to Unruh effect. Furthermore, QD exhibits more robustness than GQD when the multipartite systems are exposed to environment.Comment: 15 pages, 4 figures, 4 table

Twenty five years after KLS: A celebration of non-equilibrium statistical mechanics

When Lenz proposed a simple model for phase transitions in magnetism, he couldn't have imagined that the "Ising model" was to become a jewel in field of equilibrium statistical mechanics. Its role spans the spectrum, from a good pedagogical example to a universality class in critical phenomena. A quarter century ago, Katz, Lebowitz and Spohn found a similar treasure. By introducing a seemingly trivial modification to the Ising lattice gas, they took it into the vast realms of non-equilibrium statistical mechanics. An abundant variety of unexpected behavior emerged and caught many of us by surprise. We present a brief review of some of the new insights garnered and some of the outstanding puzzles, as well as speculate on the model's role in the future of non-equilibrium statistical physics.Comment: 3 figures. Proceedings of 100th Statistical Mechanics Meeting, Rutgers, NJ (December, 2008