High pressure study of a Zr-based bulk metallic glass and its composite

Energy dispersive X-ray diffraction was used to study the structural evolution of a bulk metallic glass (BMG) alloy and its composite with W particles under hydrostatic pressure. The diffraction data, especially the pair distribution function (PDF) of the BMG allowed the direct measurement of its elastic strain. The results suggest that PDF patterns of BMGs can be used to deducetheir strain evolution in composites as well as in monolithic form. Although the PDF method of strain measurement in amorphous alloys offers lower resolution compared to the analysis of Bragg reflections from crystalline materials, the PDF techique yields valuable information about the deformation of BMGs

The low temperature interface between the gas and solid phases of hard spheres with a short-ranged attraction

At low temperature, spheres with a very short-ranged attraction exist as a close-packed solid coexisting with an infinitely dilute gas. We find that the ratio of the interfacial tension between these two phases to the thermal energy diverges as the range of the attraction goes to zero. The large tensions when the interparticle attractions are short-ranged may be why globular proteins only crystallise over a narrow range of conditions.Comment: 6 pages, no figures (v2 has change of notation to agree with that of Stell

Homogeneous nucleation of a non-critical phase near a continuous phase transition

Homogeneous nucleation of a new phase near a second, continuous, transition, is considered. The continuous transition is in the metastable region associated with the first-order phase transition, one of whose coexisting phases is nucleating. Mean-field calculations show that as the continuous transition is approached, the size of the nucleus varies as the response function of the order parameter of the continuous transition. This response function diverges at the continuous transition, as does the temperature derivative of the free energy barrier to nucleation. This rapid drop of the barrier as the continuous transition is approached means that the continuous transition acts to reduce the barrier to nucleation at the first-order transition. This may be useful in the crystallisation of globular proteins.Comment: 6 pages, 1 figur

DNA variation and brain region-specific expression profiles exhibit different relationships between inbred mouse strains: implications for eQTL mapping studies

BACKGROUND: Expression quantitative trait locus (eQTL) mapping is used to find loci that are responsible for the transcriptional activity of a particular gene. In recent eQTL studies, expression profiles were derived from either homogenized whole brain or collections of large brain regions. However, the brain is a very heterogeneous organ, and expression profiles of different brain regions vary significantly. Because of the importance and potential power of eQTL studies in identifying regulatory networks, we analyzed gene expression patterns in different brain regions from multiple inbred mouse strains and investigated the implications for the design and analysis of eQTL studies. RESULTS: Gene expression profiles of five brain regions in six inbred mouse strains were studied. Few genes exhibited a significant strain-specific expression pattern, whereas a large number of genes exhibited brain region-specific patterns. We constructed phylogenetic trees based on the expression relationships between the strains and compared them with a DNA-level relationship tree. The trees based on the expression of strain-specific genes were constant across brain regions and mirrored DNA-level variation. However, the trees based on region-specific genes exhibited a different set of strain relationships, depending on the brain region. An eQTL analysis showed enrichment of cis-acting regulators among strain-specific genes, whereas brain region-specific genes appear to be mainly regulated by trans-acting elements. CONCLUSION: Our results suggest that many regulatory networks are highly brain region specific and indicate the importance of conducting eQTL mapping studies using data from brain regions or tissues that are physiologically and phenotypically relevant to the trait of interest

Local therapy with CpG motifs in a murine model of allergic airway inflammation in IFN-β knock-out mice

BACKGROUND: CpG oligodeoxynucleotides (CpG-ODN) are capable of inducing high amounts of type I IFNs with many immunomodulatory properties. Furthermore, type-I IFNs have been proposed to play a key role in mediating effects of CpG-ODN. The precise role of IFN-β in the immunomodulatory effects of CpG-ODN is not known. OBJECTIVE: Here, we aimed to elucidate the role of IFN-β in the anti-allergic effect of CpG motifs. METHODS: We assessed the immune response in OVA-primed/OVA-challenged IFN-β knockout (-/-) mice compared to wild type (WT) control, after intranasal and systemic treatment with synthetic CpG motifs. RESULTS: Vaccination with CpG-ODN reduced the number of cells in airways of OVA-sensitized WT but not IFN-β-/- mice. Although airway eosinophilia was reduced in both treated groups, they were significantly higher in IFN-β(-)/- mice. Other inflammatory cells, such as lymphocytes and macrophages were enhanced in airways by CpG treatment in IFN-β-/- mice. The ratio of IFN-γ/IL-4 cytokines in airways was significantly skewed to a Th1 response in WT compared to IFN-β(-)/- group. In contrast, IL-4 and IgE were reduced with no differences between groups. Ag-specific T-cell proliferation, Th1-cytokines such as IFN-γ, IL-2 and also IL-12 were significantly lower in IFN-β-/- mice. Surprisingly, we discovered that intranasal treatment of mice with CpG-ODN results in mild synovitis particularly in IFN-β-/- mice. CONCLUSION: Our results indicate that induction of Th1 response by therapy with CpG-ODN is only slightly and partially dependent on IFN-β, while IFN-β is not an absolute requirement for suppression of airway eosinophilia and IgE. Furthermore, our finding of mild synovitis is a warning for possible negative effects of CpG-ODN vaccination

High pressure study of a Zr-based bulk metallic glass and its composite

Energy dispersive X-ray diffraction was used to study the structural evolution of a bulk metallic glass (BMG) alloy and its composite with W particles under hydrostatic pressure. The diffraction data, especially the pair distribution function (PDF) of the BMG allowed the direct measurement of its elastic strain. The results suggest that PDF patterns of BMGs can be used to deducetheir strain evolution in composites as well as in monolithic form. Although the PDF method of strain measurement in amorphous alloys offers lower resolution compared to the analysis of Bragg reflections from crystalline materials, the PDF techique yields valuable information about the deformation of BMGs

Theory and simulation of short-range models of globular protein solutions

We report theoretical and simulation studies of phase coexistence in model globular protein solutions, based on short-range, central, pair potential representations of the interaction among macro-particles. After reviewing our previous investigations of hard-core Yukawa and generalised Lennard-Jones potentials, we report more recent results obtained within a DLVO-like description of lysozyme solutions in water and added salt. We show that a one-parameter fit of this model based on Static Light Scattering and Self-Interaction Chromatography data in the dilute protein regime, yields demixing and crystallization curves in good agreement with experimental protein-rich/protein-poor and solubility envelopes. The dependence of cloud and solubility points temperature of the model on the ionic strength is also investigated. Our findings highlight the minimal assumptions on the properties of the microscopic interaction sufficient for a satisfactory reproduction of the phase diagram topology of globular protein solutions.Comment: 17 pages, 8 figures, Proc. of Conference "Structural Arrest Transitions in Colloidal Systems with Short-Range Attractions", Messina (ITALY) 17-20 December 200