Measurement of polarization observables T, P, and H in π0 and η photoproduction off quasi-free nucleons.

The target asymmetry T, recoil asymmetry P, and beam-target double polarization observable H were determined in exclusive π0 and η photoproduction off quasi-free protons and, for the first time, off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass. A comparison of the data obtained on the proton and on the neutron provides new insight into the isospin structure of the electromagnetic excitation of the nucleon. Earlier measurements of polarization observables in the γp→π0p and γp→ηp reactions are confirmed. The data obtained on the neutron are of particular relevance for clarifying the origin of the narrow structure in the ηn system at W=1.68GeV. A comparison with recent partial wave analyses favors the interpretation of this structure as arising from interference of the S11(1535) and S11(1650) resonances within the S11-partial wave.

Measurement of the helicity asymmetry E for the reaction γ p → π 0 p : The CBELSA/TAPS Collaboration.

A measurement of the double-polarization observable E for the reaction γ p → π 0 p is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C 4 H 9 OH) target, which provided longitudinally-polarized protons. Circularly-polarized photons were produced via bremsstrahlung of longitudinally-polarized electrons. The data cover the photon energy range from E γ = 600 to 2310 MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses.

Observation of the pη

Data on the beam asymmetry Σ in the photoproduction of η mesons off protons are reported for tagged photon energies from 1130 to 1790 MeV (mass range from W=1748 MeV to W=2045 MeV). The data cover the full solid angle that allows for a precise moment analysis. For the first time, a strong cusp effect in a polarization observable has been observed that is an effect of a branch-point singularity at the pη^{'} threshold [E_{γ}=1447 MeV (W=1896 MeV)]. The latest BnGa partial wave analysis includes the new beam asymmetry data and yields a strong indication for the N(1895)1/2^{-} nucleon resonance, demonstrating the importance of including all singularities for a correct determination of partial waves and resonance parameters.

Modulations in martensitic Heusler alloys originate from nanotwin ordering.

Heusler alloys exhibiting magnetic and martensitic transitions enable applications like magnetocaloric refrigeration and actuation based on the magnetic shape memory effect. Their outstanding functional properties depend on low hysteresis losses and low actuation fields. These are only achieved if the atomic positions deviate from a tetragonal lattice by periodic displacements. The origin of the so-called modulated structures is the subject of much controversy: They are either explained by phonon softening or adaptive nanotwinning. Here we used large-scale density functional theory calculations on the Ni2MnGa prototype system to demonstrate interaction energy between twin boundaries. Minimizing the interaction energy resulted in the experimentally observed ordered modulations at the atomic scale, it explained that a/b twin boundaries are stacking faults at the mesoscale, and contributed to the macroscopic hysteresis losses. Furthermore, we found that phonon softening paves the transformation path towards the nanotwinned martensite state. This unified both opposing concepts to explain modulated martensite.

The dynamics of multimer formation of the amphiphilic hydrophobin protein HFBII.

Hydrophobins are surface-active proteins produced by filamentous fungi. They have amphiphilic structures and form multimers in aqueous solution to shield their hydrophobic regions. The proteins rearrange at interfaces and self-assemble into films that can show a very high degree of structural order. Little is known on dynamics of multimer interactions in solution and how this is affected by other components. In this work we examine the multimer dynamics by stopped-flow fluorescence measurements and Förster Resonance Energy Transfer (FRET) using the class II hydrophobin HFBII. The half-life of exchange in the multimer state was 0.9s at 22°C with an activation energy of 92kJ/mol. The multimer exchange process of HFBII was shown to be significantly affected by the closely related HFBI hydrophobin, lowering both activation energy and half-life for exchange. Lower molecular weight surfactants interacted in very selective ways, but other surface active proteins did not influence the rates of exchange. The results indicate that the multimer formation is driven by specific molecular interactions that distinguish different hydrophobins from each other.

Mastering hysteresis in magnetocaloric materials.

Hysteresis is more than just an interesting oddity that occurs in materials with a first-order transition. It is a real obstacle on the path from existing laboratory-scale prototypes of magnetic refrigerators towards commercialization of this potentially disruptive cooling technology. Indeed, the reversibility of the magnetocaloric effect, being essential for magnetic heat pumps, strongly depends on the width of the thermal hysteresis and, therefore, it is necessary to understand the mechanisms causing hysteresis and to find solutions to minimize losses associated with thermal hysteresis in order to maximize the efficiency of magnetic cooling devices. In this work, we discuss the fundamental aspects that can contribute to thermal hysteresis and the strategies that we are developing to at least partially overcome the hysteresis problem in some selected classes of magnetocaloric materials with large application potential. In doing so, we refer to the most relevant classes of magnetic refrigerants La-Fe-Si-, Heusler- and Fe2P-type compounds.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.

An environmental route of exposure affects the formation of nanoparticle coronas in blood plasma.

UNLABELLED: Nanoparticles (NPs) in contact with biological fluids become covered by a tightly bound layer of proteins, the "protein corona", and it is largely accepted that this corona gives a new identity to NPs in biological milieu. We here consider the exposing scenario of NPs through an environmental route exemplified by the use of hydrophobins, highly adhesive proteins that are secreted into the environment in large quantities by fungi. HFBII of Trichoderma reesei has been used as a model protein and we have shown strong binding to polystyrene NPs of different sizes and surface groups. Hydrophobin coated NPs are shown to strongly increase the stability and the dispersion when exposed to human plasma compared to pristine ones particles. It is also shown that the presence of hydrophobin on the NPs results in an attenuated protein corona formation, in a different corona composition, and we also show that hydrophobin remained strongly associated to the NPs in competition with plasma proteins. As a conclusion we therefore suggest that the route of exposure of nanoparticles strongly affects their surface properties and their possible physiological behavior. SIGNIFICANCE: This work shows how a self-assembling protein, class II hydrophobin HFBII, with interesting biocompatible coating properties, strongly adsorbs on polystyrene NPs. HFBII is also shown to reduce aggregation of the NPs in human plasma which can increase their bioavailability with potential use in biomedical applications. The results here are also of significance for understanding possible interactions of NPs with living organisms. Hydrophobins are secreted in large quantities into the environment by fungi and this work shows how the biological environment of NPs determines the surface and colloidal properties of the particles by forming a protein corona, and that the history of the particle environment, here simulated with hydrophobin exposure, affects both plasma protein corona formation and dispersion behavior. This work thus simulates how alternative exposure routes affect nanoparticle properties, important in understanding the biological fate of NPs.

Element-resolved thermodynamics of magnetocaloric LaFe(13-x)Si(x).

By combination of two independent approaches, nuclear resonant inelastic x-ray scattering and first-principles calculations in the framework of density functional theory, we demonstrate significant changes in the element-resolved vibrational density of states across the first-order transition from the ferromagnetic low temperature to the paramagnetic high temperature phase of LaFe(13-x)Si(x). These changes originate from the itinerant electron metamagnetism associated with Fe and lead to a pronounced magneto-elastic softening despite the large volume decrease at the transition. The increase in lattice entropy associated with the Fe subsystem is significant and contributes cooperatively with the magnetic and electronic entropy changes to the excellent magneto- and barocaloric properties.

N(1520) 3/2(-) helicity amplitudes from an energy-independent multipole analysis based on new polarization data on photoproduction of neutral pions.

New data on the polarization observables T, P, and H for the reaction γp→pπ(0) are reported. The results are extracted from azimuthal asymmetries when a transversely polarized butanol target and a linearly polarized photon beam are used. The data were taken at the Bonn electron stretcher accelerator ELSA using the CBELSA/TAPS detector. These and earlier data are used to perform a truncated energy-independent partial wave analysis in sliced-energy bins. This energy-independent analysis is compared to the results from energy-dependent partial wave analyses.

First measurement of the helicity asymmetry for γp → pπ0 in the resonance region.

The first measurement of the helicity dependence of the photoproduction cross section of single neutral pions off protons is reported for photon energies from 600 to 2300 MeV, covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, and BnGa partial wave analyses. Strikingly large differences between data and predictions are observed, which are traced to differences in the helicity amplitudes of well-known and established resonances. Precise values for the helicity amplitudes of several resonances are reported.

Well-established nucleon resonances revisited by double-polarization measurements.

The first measurement is reported of the double-polarization observable G in the photoproduction of neutral pions off protons, covering the photon energy range from 620 to 1120 MeV and the full solid angle. G describes the correlation between the photon polarization plane and the scattering plane for protons polarized along the direction of the incoming photon. The observable is highly sensitive to contributions from baryon resonances. The new results are compared to the predictions from SAID, MAID, and BnGa partial wave analyses. In spite of the long-lasting efforts to understand γp→pπ(0) as the simplest photoproduction reaction, surprisingly large differences between the new data and the latest predictions are observed which are traced to different contributions of the N(1535) resonance with spin parity J(P)=1/2(-) and N(1520) with J(P)=3/2(-). In the third resonance region, where N(1680) with J(P)=5/2(+) production dominates, the new data are reasonably close to the predictions.

Complete denture displacement following open-mouth reline.

In 21 complete denture wearers, six upper and 15 lower denture relines were performed with the open-mouth technique. The centric relation (CR) was recorded with the Central-Bearing-Point (CBP) method three times before and three times after the reline. For each registration, the right and left condylar position was recorded in three dimensions using a custom-made measuring device. The average denture displacement from an initial reference position (CR) was calculated for each registration. An upper denture reline leads to a mean displacement of 2·5 mm, both in the right and left condylar area. With an average of 2·0 mm, this displacement was smaller following a lower denture reline (right and left mean, 1·6 mm). The precision of the CBP-registrations proved 0·5 mm before and 0·3 mm after reline; hence, the measured condylar displacement after reline could not attribute to a methodological bias. This clinical-experimental study demonstrates that relining complete dentures with the open-mouth technique may lead to a substantial denture shift and thus imply inevitably clinically relevant occlusal discrepancies. It is therefore important to carefully check the occlusion at denture delivery and remount the prostheses if necessary.

Alternative sputum preparation to improve polymerase chain reaction assay for Mycobacterium tuberculosis detection.

BACKGROUND: Tuberculosis (TB), one of the major airborne infectious bacterial diseases, remains an important health problem worldwide. It is estimated that there are 1700 new cases per year in Santa Catarina State, Brazil. OBJECTIVE: To improve polymerase chain reaction (PCR) sensitivity in detecting Mycobacterium tuberculosis in sputum samples. METHODS: This study proposed the use of glass beads as a modification of the routine protocol for sputum preparation used in the Laboratory of Molecular Biology and Mycobacteria at the Federal University of Santa Catarina, Florianópolis, Brazil. The study comprised 120 sputum samples, 60 of which were treated with the routine protocol, while 60 were treated with the modified protocol using glass beads. RESULTS: Samples treated with the routine protocol had a sensitivity of 56.7% (95%CI 44.1-69.2) in 16S rRNA PCR and 81.7% (95%CI 71.9-91.5) in insertion sequence (IS) 6110 PCR, compared with culture. Samples treated with the modified protocol had a sensitivity of 73.3% (95%CI 62.1-84.5) in 16S rRNA PCR and 100% in IS6110 PCR. CONCLUSION: The modified protocol using glass beads greatly improved mycobacterial detection in sputum samples compared with the routine protocol.

Early use of Xeomin neurotoxin for local anti-spasticity therapy for pes equines after acquired brain injury (ABI).

PRIMARY OBJECTIVE: The acute management of spasticity following ABI is challenging. Contractures can occur during the acute phases of illness. The joints most affected are the shoulders and the ankles. RESEARCH DESIGN: A case study of a 48-year-old female patient who received local chemoneurolytic anti-spasticity therapy following a severe subarachnoid haemorrhage for pes equines deformity is presented to illustrate the role of focal neurotoxin therapy. METHODS AND PROCEDURES: The increasing spasticity in her legs was observed and could not be effectively treated with oral anti-spasticity agents or intensive physiotherapy. As spasticity increased (Modified Ashworth Scale 4), mobility of the right foot continued to deteriorate, leading to indication for local anti-spasticity treatment with Xeomin neurotoxin. The spastic pes equinus was injected with Xeomin® using a total dose of 150 U. MAIN OUTCOMES AND RESULTS: On the 6th day after injection, a gradual reduction in spasticity was observed in the injected muscle (Modified Ashworth Scale 1-2) and an increasing improvement in joint mobility. CONCLUSIONS: Early local anti-spasticity treatment with Xeomin is effective treatment. The cost of the intervention would appear to be high, but if one compares it with the costs of conservative treatment, it is not more expensive.

Rehabilitation intervention in animal model can improve neuromotor and cognitive functions after traumatic brain injury: pilot study.

The aim of the present study was to quantify the effect of multisensory rehabilitation on rats' cognition after an experimental brain trauma and to assess its possible clinical implications. The complex intermittent multisensory rehabilitation consisted of currently used major therapeutic procedures targeted at the improvement of cognitive functions; including multisensory and motor stimulation and enriched environment. We have confirmed this positive effect of early multisensory rehabilitation on the recovery of motor functions after traumatic brain injury. However, we have been able to prove a positive effect on the recovery of cognitive functions only with respect to the frequency of efficient search strategies in a Barnes maze test, while results for search time and travelled distance were not significantly different between study groups. We have concluded that the positive effects of an early treatment of functional deficits are comparable with the clinical results in early neurorehabilitation in human patients after brain trauma. It might therefore be reasonable to apply these experimental results to human medical neurorehabilitation care.

Understanding the phase transitions of the Ni2MnGa magnetic shape memory system from first principles.

The free energies of the austenite, the (modulated) premartensite and the unmodulated martensite of Ni2MnGa are determined using density functional theory and including quasiharmonic phonons and fixed-spin-moment magnons. This approach very well reproduces the complete phase sequence (martensite<-->premartensite<-->austenite) of stoichiometric Ni2MnGa as a function of temperature. By analyzing the relevant free energy contributions, we also understand the delicate interplay of phonons and magnons driving both phase transitions.

Large-scale ab initio simulations of binary transition metal clusters for storage media materials.

In the quest for ultra-high-density magnetic recording, new materials in the nanometre range have attracted much interest over the last decade involving intense studies of L1(0) phases of contemporary or future storage media materials like FePt or CoPt nanoparticles. Based on large-scale density functional theory calculations, we provide a systematic overview of the structural and magnetic properties of various morphologies of FePt and CoPt nanoclusters with diameters up to 3 nm. In this size range, the ordered multiply twinned morphologies are energetically favoured over the nanoclusters with the desired layer type L1(0) and high magnetocrystalline anisotropy. Other nanoparticles of interest, like FePd, also show a preference for multiply twinned structures or exhibit, as in the case of MnPt nanoclusters, a strong tendency for antiferromagnetic ordering instead of ferromagnetic order. The compositional trends of the various nanoparticles can be traced back to differences in the partial electronic density of states of the 3d element.

Side-effects of topical androgenic and anabolic substances and steroids. A short review.

UNLABELLED: There is an increasing interest, including androgenic and anabolic substances (AAS). The uncritical use may be associated with severe adverse effects. We observed five patients with different patterns of adverse reaction to AAS: two females and three males, they were identified when seeking medical help and advice. The following adverse effects from of AAS have been observed: deepening of the voice due to topical use of AAS in an anti-cellulite cream; circumscribed hypertrichosis and late onset acneiform eruptions due to testosterone replacement therapy after ovariectomy; homolateral gynecomastia and infertility, acne and striae distensae in males using injectable AAS. CONCLUSIONS: ASS can trigger significant adverse effects. An interdisciplinary approach may be necessary for evaluation. The dermatologists should be familiar with the adverse effects.