Thin film growth by pulsed laser deposition and properties of 122-type iron-based superconductor AE(Fe1--xCox)2As2 (AE = alkaline earth)

This paper reports comprehensive results on thin-film growth of 122-type iron-pnictide superconductors, AE(Fe1-xCox)2As2 (AE = Ca, Sr, and Ba, AEFe2As2:Co) by a pulsed laser deposition method using a neodymium-doped yttrium aluminum garnet laser as an excitation source. The most critical parameter to produce the SrFe2As2:Co and BaFe2As2:Co phases is the substrate temperature (Ts). It is difficult to produce highly-pure CaFe2As2:Co phase thin film at any Ts. For BaFe2As2:Co epitaxial films, controlling Ts at 800-850 {\deg}C and growth rate to 2.8-3.3 {\AA}/s produced high-quality films with good crystallinity, flat surfaces, and high critical current densities > 1 MA/cm2, which were obtained for film thicknesses from 100 to 500 nm. The doping concentration x was optimized for Ba(Fe1-xCox)2As2 epitaxial films, leading to the highest critical temperature of 25.5 K in the epitaxial films with the nominal x = 0.075.Comment: will be published in the special issue of Superconductor Science and Technology, `Iron12

Effect of the ionic liquid [bmim]Cl and high pressure on the activity of cellulase

The effect of the ionic liquid 1-butyl-3-methylimidazolium chloride ([bmim]Cl) and of high pressure on the activity of cellulase from Aspergillus niger were studied separately and in combination. The enzyme activity decreased with increasing concentrations of [bmim]Cl, reaching 50% the value in aqueous buffer with 20% [bmim]Cl. However, when the enzyme is held in 10% [bmim]Cl and is then assayed in 1% [bmim]Cl, it showed only 8% reduction of activity. These results can be explained by the fact that the activity of the enzyme in [bmim]Cl is linearly correlated with the decrease of the thermodynamic water activity (aw). Under pressure the enzyme activity varied from less 60% (at 200MPa) to equal (at 400 MPa), compared to atmospheric pressure. In 10% [bmim]Cl under pressure, cellulase activity is improved compared to atmospheric pressure, varying from equal (at 600 MPa) to 1.7-fold higher (at 100 MPa). This opens the possibility to improve cellulase activity in ionic liquids, and possibly of other enzymes, by carrying out the reaction under pressure

Secondary-Structure Design of Proteins by a Backbone Torsion Energy

We propose a new backbone-torsion-energy term in the force field for protein systems. This torsion-energy term is represented by a double Fourier series in two variables, the backbone dihedral angles phi and psi. It gives a natural representation of the torsion energy in the Ramachandran space in the sense that any two-dimensional energy surface periodic in both phi and psi can be expanded by the double Fourier series. We can then easily control secondary-structure-forming tendencies by modifying the torsion-energy surface. For instance, we can increase/decrease the alpha-helix-forming-tendencies by lowering/raising the torsion-energy surface in the alpha-helix region and likewise increase/decrease the beta-sheet-forming tendencies by lowering/raising the surface in the beta-sheet region in the Ramachandran space. We applied our approach to AMBER parm94 and AMBER parm96 force fields and demonstrated that our modifications of the torsion-energy terms resulted in the expected changes of secondary-structure-forming-tendencies by performing folding simulations of alpha-helical and beta-hairpin peptides.Comment: 13 pages, (Revtex4), 5 figure

Increased levels of RNA oxidation enhance the reversion frequency in aging pro-apoptotic yeast mutants

Despite recent advances in understanding the complexity of RNA processes, regulation of the metabolism of oxidized cellular RNAs and the mechanisms through which oxidized ribonucleotides affect mRNA translation, and consequently cell viability, are not well characterized. We show here that the level of oxidized RNAs is markedly increased in a yeast decapping Kllsm4Δ1 mutant, which accumulates mRNAs, ages much faster that the wild type strain and undergoes regulated-cell-death. We also found that in Kllsm4Δ1 cells the mutation rate increases during chronological life span indicating that the capacity to han- dle oxidized RNAs in yeast declines with aging. Lowering intracellular ROS levels by antioxidants recovers the wild- type phenotype of mutant cells, including reduced amount of oxidized RNAs and lower mutation rate. Since mRNA oxidation was reported to occur in different neurodegen- erative diseases, decapping-deficient cells may represent a useful tool for deciphering molecular mechanisms of cell response to such conditions, providing new insights into RNA modification-based pathogenesis

Pattern formation of reaction-diffusion system having self-determined flow in the amoeboid organism of Physarum plasmodium

The amoeboid organism, the plasmodium of Physarum polycephalum, behaves on the basis of spatio-temporal pattern formation by local contraction-oscillators. This biological system can be regarded as a reaction-diffusion system which has spatial interaction by active flow of protoplasmic sol in the cell. Paying attention to the physiological evidence that the flow is determined by contraction pattern in the plasmodium, a reaction-diffusion system having self-determined flow arises. Such a coupling of reaction-diffusion-advection is a characteristic of the biological system, and is expected to relate with control mechanism of amoeboid behaviours. Hence, we have studied effects of the self-determined flow on pattern formation of simple reaction-diffusion systems. By weakly nonlinear analysis near a trivial solution, the envelope dynamics follows the complex Ginzburg-Landau type equation just after bifurcation occurs at finite wave number. The flow term affects the nonlinear term of the equation through the critical wave number squared. Contrary to this, wave number isn't explicitly effective with lack of flow or constant flow. Thus, spatial size of pattern is especially important for regulating pattern formation in the plasmodium. On the other hand, the flow term is negligible in the vicinity of bifurcation at infinitely small wave number, and therefore the pattern formation by simple reaction-diffusion will also hold. A physiological role of pattern formation as above is discussed.Comment: REVTeX, one column, 7 pages, no figur

Loss of AP-3 function affects spontaneous and evoked release at hippocampal mossy fiber synapses

Synaptic vesicle (SV) exocytosis mediating neurotransmitter release occurs spontaneously at low intraterminal calcium concentrations and is stimulated by a rise in intracellular calcium. Exocytosis is compensated for by the reformation of vesicles at plasma membrane and endosomes. Although the adaptor complex AP-3 was proposed to be involved in the formation of SVs from endosomes, whether its function has an indirect effect on exocytosis remains unknown. Using mocha mice, which are deficient in functional AP-3, we identify an AP-3-dependent tetanus neurotoxin-resistant asynchronous release that can be evoked at hippocampal mossy fiber (MF) synapses. Presynaptic targeting of the tetanus neurotoxin-resistant vesicle soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) tetanus neurotoxin-insensitive vesicle-associated membrane protein (TI-VAMP) is lost in mocha hippocampal MF terminals, whereas the localization of synaptobrevin 2 is unaffected. In addition, quantal release in mocha cultures is more frequent and more sensitive to sucrose. We conclude that lack of AP-3 results in more constitutive secretion and loss of an asynchronous evoked release component, suggesting an important function of AP-3 in regulating SV exocytosis at MF terminals

Elucidating the relationship between DISC1, NDEL1 and NDE1 and the risk for schizophrenia: Evidence of epistasis and competitive binding

DISC1 influences susceptibility to psychiatric disease and related phenotypes. Intact functions of DISC1 and its binding partners, NDEL1 and NDE1, are critical to neurodevelopmental processes aberrant in schizophrenia (SZ). Despite evidence of an NDEL1–DISC1 protein interaction, there have been no investigations of the NDEL1 gene or the relationship between NDEL1 and DISC1 in SZ. We genotyped six NDEL1 single-nucleotide polymorphisms (SNPs) in 275 Caucasian SZ patients and 200 controls and tested for association and interaction between the functional SNP Ser704Cys in DISC1 and NDEL1. We also evaluated the relationship between NDE1 and DISC1 genotype and SZ. Finally, in a series of in vitro assays, we determined the binding profiles of NDEL1 and NDE1, in relation to DISC1 Ser704Cys. We observed a single haplotype block within NDEL1; the majority of variation was captured by NDEL1 rs1391768. We observed a significant interaction between rs1391768 and DISC1 Ser704Cys, with the effect of NDEL1 on SZ evident only against the background of DISC1 Ser704 homozygosity. Secondary analyses revealed no direct relationship between NDE1 genotype and SZ; however, there was an opposite pattern of risk for NDE1 genotype when conditioned on DISC1 Ser704Cys, with NDE1 rs3784859 imparting a significant effect but only in the context of a Cys-carrying background. In addition, we report opposing binding patterns of NDEL1 and NDE1 to Ser704 versus Cys704, at the same DISC1 binding domain. These data suggest that NDEL1 significantly influences risk for SZ via an interaction with DISC1. We propose a model where NDEL1 and NDE1 compete for binding with DISC1