Microstructure and superconducting properties of hot isostatically pressed MgB2

Bulk samples of MgB2 have been formed by hot isostatic pressing (HIPping) of commercial powder at 100MPa and 950=B0C. The resulting material is 100% dense with a sharp superconducting transition at 37.5K. Microstructural studies have indicated the presence of small amounts of second phases within the material, namely MgO and B rich compositions, probably MgB4. Magnetisation measurements performed at 20K have revealed values of Jc=1.3 x 106A/cm2 at zero field, and 9.3 x 105A/cm2 at 1T. Magneto optical (MO) studies have shown direct evidence for the superconducting homogeneity and strong intergranular current flow in the material.Comment: 3 pages, 6 figures, text updated, new references included and discussed. Submitted to Superconductor Science and Technolog

Evidence for high inter-granular current flow in single-phase polycrystalline MgB2 superconductor

The distribution of magnetic field in single-phase polycrystalline bulk MgB2 has been measured using a Magneto-Optical (MO) technique for an external magnetic field applied perpendicular to the sample surface. The MO studies indicate that an inter-granular current network is readily established in this material and the current is not limited by weak-linked grain boundaries. The grain boundaries are observed to resist preferential magnetic field penetration, with the inter-grain mechanism dominating the current flow in the sample at temperatures up to 30K. The results provide clear evidence that the intra-granular current flow is isotropic. A critical current density of ~10^4 Acm-2 was estimated at 30K in a field of 150mT from the MO measurements. These results provide further evidence of the considerable potential for MgB2 for engineering applications.Comment: 3 pages, 3 figure

Effect of DMSO on Protein Structure and Interactions Assessed by Collision-Induced Dissociation and Unfolding

Given the frequent use of DMSO in biochemical and biophysical assays, it is desirable to understand the influence of DMSO concentration on the dissociation or unfolding behavior of proteins. In this study, the effects of DMSO on the structure and interactions of avidin and Mycobacterium tuberculosis (Mtb) CYP142A1 were assessed through collision-induced dissociation (CID) and collision-induced unfolding (CIU) as monitored by nanoelectrospray ionization–ion mobility–mass spectrometry (nESI-IM-MS). DMSO concentrations higher than 4% (v/v) destabilize the avidin tetramer toward dissociation and unfolding, via both its effects on charge state distribution (CSD) as well as at the level of individual charge states. In contrast, DMSO both protects against heme loss and increases the stability of CYP142A1 toward unfolding even up to 40% DMSO. Tandem MS/MS experiments showed that DMSO could modify the dissociation pathway of CYP142A1, while CIU revealed the protective effect of the heme group on the structure of CYP142A1.D.S.-H.C. acknowledges the Croucher Foundation and the Cambridge Commonwealth, European and International Trust for receipt of a Croucher Cambridge International Scholarship. M.E.K. was supported by a Commonwealth (University of Cambridge) Scholarship awarded in conjunc-tion with the Cambridge Commonwealth Trust and Cam-bridge Overseas Trust. K.J.M. and A.G.C. were supported by grants from the UK BBSRC (Biotechnology and Biological Sciences Research Council (BB/I019669/1 and BB/I019227/1)

Genetic relationship between purebred and crossbred sow longevity

Background The overall breeding objective for a nucleus swine selection program is to improve crossbred commercial performance. Most genetic improvement programs are based on an assumed high degree of positive relationship between purebred performance in a nucleus herd and their relatives’ crossbred performance in a commercial herd. The objective of this study was to examine the relationship between purebred and crossbred sow longevity performance. Sow longevity was defined as a binary trait with a success occurring if a sow remained in the herd for a certain number of parities and including the cumulative number born alive as a measure of reproductive success. Heritabilities, genetic correlations, and phenotypic correlations were estimated using THRGIBBS1F90. Results Results indicated little to no genetic correlations between crossbred and purebred reproductive traits. This indicates that selection for longevity or lifetime performance at the nucleus level may not result in improved longevity and lifetime performance at the crossbred level. Early parity performance was highly correlated with lifetime performance indicating that an indicator trait at an early parity could be used to predict lifetime performance. This would allow a sow to have her own record for the selection trait before she has been removed from the herd. Conclusions Results from this study aid in quantifying the relationship between purebred and crossbred performance and provide information for genetic companies to consider when developing a selection program where the objective is to improve crossbred sow performance. Utilizing crossbred records in a selection program would be the best way to improve crossbred sow productivity

Separating the BL Lac and Cluster X-ray Emissions in Abell 689 with Chandra

We present the results of a Chandra observation of the galaxy cluster Abell 689 (z=0.279). Abell 689 is one of the most luminous clusters detected in the ROSAT All Sky Survey (RASS), but was flagged as possibly including significant point source contamination. The small PSF of the Chandra telescope allows us to confirm this and separate the point source from the extended cluster X-ray emission. For the cluster we determine a bolometric luminosity of L_{bol}=(3.3+/-0.3)x10^{44} erg s-1 and a temperature of kT=5.1^{+2.2}_{-1.3} keV when including a physically motivated background model. We compare our measured luminosity for A689 to that quoted in the Rosat All Sky Survey (RASS) and find L_{0.1-2.4,keV}=2.8x10^{44} erg s-1, a value \sim10 times lower than the ROSAT measurement. Our analysis of the point source shows evidence for significant pileup, with a pile-up fraction of ~60%. SDSS spectra and HST images lead us to the conclusion that the point source within Abell 689 is a BL Lac object. Using radio and optical observations from the VLA and HST archives, we determine {\alpha}_{ro}=0.50, {\alpha}_{ox}=0.77 and {\alpha}_{rx}=0.58 for the BL Lac, which would classify it as being of 'High-energy peak BL Lac' (HBL) type. Spectra extracted of A689 show a hard X-ray excess at energies above 6 keV that we interpret as inverse Compton emission from aged electrons that may have been transported into the cluster from the BL Lac.Comment: 11 pages, 15 figures, MNRAS in pres

Bis(1-tosyl-2-pyrrol­yl)ethyne

The title mol­ecule, C24H20N2O4S2, has crystallographic inversion symmetry with a triple-bond distance of 1.206 (2) Å. The alkyne is not quite linear, with a C—C C angle of 175.78 (16)°. The planar pyrrole rings are parallel but offset from coplanarity by 0.318 (1) Å. The conformation of the sulfonyl group with respect to the pyrrole ring is such that an O atom is nearly eclipsed with this ring, having an O—S—N—C torsion angle of 3.48 (11)°. C—H⋯O inter­actions [C⋯O 3.278 (2) Å, 136° about H] between pyrrole H and sulfonyl O atoms lead to the formation of ladder-like chains

Peculiar Motions in the Region of the Ursa Major Supercluster of Galaxies

We have investigated the peculiar motions of clusters of galaxies in the Ursa Major (UMa) supercluster and its neighborhood. Based on SDSS (Sloan Digital Sky Survey) data, we have compiled a sample of early-type galaxies and used their fundamental plane to determine the cluster distances and peculiar velocities. The samples of early-type galaxies in the central regions (within R_200) of 12 UMa clusters of galaxies, in three main subsystems of the supercluster -- the filamentary structures connecting the clusters, and in nine clusters from the nearest UMa neighborhood have similar parameters. The fairly high overdensity (3 by the galaxy number and 15 by the cluster number) suggests that the supercluster as a whole is gravitationally bound, while no significant peculiar motions have been found: the peculiar velocities do not exceed the measurement errors by more than a factor of 1.5-2. The mean random peculiar velocities of clusters and the systematic deviations from the overall Hubble expansion in the supercluster are consistent with theoretical estimates. For the possible approach of the three UMa subsystems to be confirmed, the measurement accuracy must be increased by a factor of 2-3.Comment: 21 pages, 4 tables, 7 figure

Embedded Micro-Computer Base Force Plate as an Objective Tool to Measure Hoof Lameness Phases in Multiparous Sows

The objective of this study was to compare differences in weight placed on each hoof from sows in differing lameness phases. Twelve, clinically healthy, mixed-parity, crossbred sows (228.89±19.17 kg) were used. The sow was the experimental unit and a cross-over design with a 2 (hind left and hind right hoof) x 3 (days: D-1, D+1 and D+6) factorial arrangement of treatments were compared. On induction day, 10 mg of amphotericin B were injected in the distal interphalangeal joint space in both claws of one hind hoof. All sows served as their own control and treatment. After completion of the first round, sows were given a 7-day rest period and then the round procedures were repeated with the opposite hind hoof induced. Sows stood individually on an embedded force plate for 15 minutes, and weight on each hoof was measured independently. All data were statistically analyzed using the PROC MIXED procedure in SAS. On the D+1, sows exhibited less weight bearing on the induced lame hoof compared to D-1 (P \u3c 0.0001). Regardless of which hoof was injected, sow weight distribution did not vary between the injected left or right hind hooves (P = 0.99) or between rounds (P = 0.64). Findings from our study indicate that the embedded force plate exhibited differences between sound and most lame phases indicating the potential as an objective tool for detecting differences in weight distribution when sows are sound and lame

Time Required for Lameness Detection on an Embedded Microcomputer Based Force Plate in a Lab Based Setting

The objective of this study was to determine the minimum time required for the embedded microcomputer based force plate (force plate) to detect lameness. The force plate can be placed under an electronic sow feeder or a gestation stall to routinely assess lameness. Previous work with the force plate has required sows to remain standing in a gestation stall for longer than a typical feeding time allotment of 9 minutes to measure the force applied to each foot. Comparing sows’ weight distribution across time showed that an adjustment period is required before force distribution measurements are consistent, as the sows adapts to the force plate. When using a 30 second adjustment period, sows only needed to stand on the force plate for 210 seconds in order to have a consistent reading across time. This could create a labor reduction during research trials, and allow more data to be used from a commercial setting, than when using the previous times