XPS characterization of silver electrodes and catalyst for oxygen reduction

The combined analysis of the silver GDE using an ex-situ surface sensitive technique (XPS) and in-situ electrochemical measurements (EIS, CV) show that the performance of the silver GDE is significantly influenced by the degree of degradation of the electrodes, e. g., the reduction of the active surface due to the decomposition of the PTFE. These findings indicate a different degree of decomposition of the PTFE on the on the GDE

Optimization of enzyme immobilization on magnetic microparticles using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) as a crosslinking agent

Enzyme immobilization is a versatile tool in biotransformation processes to enhance enzyme activity and to secure an easy separation of catalysts and products and the reusability of enzymes. A simple and commonly used method for crosslinking enzymes to a solid support is the zero-length crosslinking agent 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). This work shows the optimization of the EDC-crosslinking protocol for two enzymes, glucose oxidase (GOx) and horseradish peroxidase (HRP), to functionalized magnetic microparticles. For GOx the optimization of the immobilization parameters pH-value and the enzyme to particle ratio results in activity yields of up to 36%, which is in the usual range for undirected enzyme immobilisations. In contrast, for HRP the activity yield does not exceed 6% even after optimization of the protocols. The main reasons for this unusually low activity yield are the presence of multiple HRP isoforms in the enzyme solution used for immobilisation and the observed tendency of HRP to be inactive even in the case of simple physisorption to the particle surface. © 2015 The Royal Society of Chemistry

Combined FUS+ basophilic inclusion body disease and atypical tauopathy presenting with an ALS/MND-plus phenotype

AIMS: Amyotrophic lateral sclerosis / motor neurone disease (ALS/MND) is characterised by the presence of inclusions containing TDP-43 within motor neurones. In rare cases, ALS/MND may be associated with inclusions containing other proteins, such as fused in sarcoma (FUS), whilst motor system pathology may rarely be a feature of other neurodegenerative disorders. We here have investigated the association of FUS and tau pathology. METHODS: We report a case with an ALS/MND-plus clinical syndrome which pathologically demonstrated both FUS pathology and an atypical tauopathy. RESULTS: Clinical motor involvement was predominantly upper motor neurone, and was accompanied by extrapyramidal features and sensory involvement, but with only minimal cognitive impairment. The presentation was sporadic and gene mutation screening was negative. Post-mortem study demonstrated inclusions positive for FUS, including basophilic inclusion bodies. This was associated with 4R-tauopathy, largely as non-fibrillary diffuse phospho-tau in neurones, with granulovacuolar degeneration in a more restricted distribution. Double-staining revealed that neurones contained both types of protein pathology. CONCLUSION: FUS-positive basophilic inclusion body disease is a rare cause of ALS/MND, but in this case was associated with an unusual atypical tauopathy. The coexistence of two such rare neuropathologies raises the question of a pathogenic interaction

Bilateral Ocular Myositis Associated with Whipple's Disease

Purpose: To describe the clinical features of a Caucasian female patient with a history of treated gastrointestinal Whipple's disease (WD) who developed new-onset diplopia, with a description of the histopathological features of the extraocular muscle biopsies. Methods: A previously fit 38-year-old Caucasian female presented with acute-onset diplopia after being on a sustained medication regime for biopsy-proven gastrointestinal WD. A magnetic resonance imaging scan of her orbits with gadolinium revealed diffuse enhancement of the bellies of the extraocular muscles bilaterally, particularly the medial rectus, superior rectus, and superior oblique muscles, consistent with an infiltrative myositis. She underwent unilateral extraocular muscle biopsies. Results: The extraocular muscle biopsies contained macrophages between the muscle fibres. These contained periodic acid-Schiff-positive cytoplasmic granules. Immunohistochemistry with an antibody raised to Tropheryma whipplei showed positive staining of the same macrophages. Transmission electron microscopy confirmed the presence of effete T. whipplei cell membranes in lysosomes. Conclusion: This case describes bilateral WD-associated extraocular muscle myositis. The exact mechanism for this unusual presentation is unclear, but both a WD-associated immune reconstitution inflammatory syndrome and treatment failure are possibilities, with a good response observed to antibiotic therapy and adjunctive corticosteroids

Electron spin coherence in semiconductors: Considerations for a spin-based solid state quantum computer architecture

We theoretically consider coherence times for spins in two quantum computer architectures, where the qubit is the spin of an electron bound to a P donor impurity in Si or within a GaAs quantum dot. We show that low temperature decoherence is dominated by spin-spin interactions, through spectral diffusion and dipolar flip-flop mechanisms. These contributions lead to 1-100 $\mu$s calculated spin coherence times for a wide range of parameters, much higher than former estimates based on $T_{2}^{*}$ measurements.Comment: Role of the dipolar interaction clarified; Included discussion on the approximations employed in the spectral diffusion calculation. Final version to appear in Phys. Rev.

An NMR-based nanostructure switch for quantum logic

We propose a nanostructure switch based on nuclear magnetic resonance (NMR) which offers reliable quantum gate operation, an essential ingredient for building a quantum computer. The nuclear resonance is controlled by the magic number transitions of a few-electron quantum dot in an external magnetic field.Comment: 4 pages, 2 separate PostScript figures. Minor changes included. One reference adde

Voltage-tunable singlet-triplet transition in lateral quantum dots

Results of calculations and high source-drain transport measurements are presented which demonstrate voltage-tunable entanglement of electron pairs in lateral quantum dots. At a fixed magnetic field, the application of a judiciously-chosen gate voltage alters the ground-state of an electron pair from an entagled spin singlet to a spin triplet.Comment: 8.2 double-column pages, 10 eps figure

Specific Heat Study of the Magnetic Superconductor HoNi2B2C

The complex magnetic transitions and superconductivity of HoNi2B2C were studied via the dependence of the heat capacity on temperature and in-plane field angle. We provide an extended, comprehensive magnetic phase diagram for B // [100] and B // [110] based on the thermodynamic measurements. Three magnetic transitions and the superconducting transition were clearly observed. The 5.2 K transition (T_{N}) shows a hysteresis with temperature, indicating the first order nature of the transition at B=0 T. The 6 K transition (T_{M}), namely the onset of the long-range ordering, displays a dramatic in-plane anisotropy: T_{M} increases with increasing magnetic field for B // [100] while it decreases with increasing field for B // [110]. The anomalous anisotropy in T_{M} indicates that the transition is related to the a-axis spiral structure. The 5.5 K transition (T^{*}) shows similar behavior to the 5.2 K transition, i.e., a small in-plane anisotropy and scaling with Ising model. This last transition is ascribed to the change from a^{*} dominant phase to c^{*} dominant phase.Comment: 9 pages, 11 figure

How Many CMEs Have Flux Ropes? Deciphering the Signatures of Shocks, Flux Ropes, and Prominences in Coronagraph Observations of CMEs

We intend to provide a comprehensive answer to the question on whether all Coronal Mass Ejections (CMEs) have flux rope structure. To achieve this, we present a synthesis of the LASCO CME observations over the last sixteen years, assisted by 3D MHD simulations of the breakout model, EUV and coronagraphic observations from STEREO and SDO, and statistics from a revised LASCO CME database. We argue that the bright loop often seen as the CME leading edge is the result of pileup at the boundary of the erupting flux rope irrespective of whether a cavity or, more generally, a 3-part CME can be identified. Based on our previous work on white light shock detection and supported by the MHD simulations, we identify a new type of morphology, the `two-front' morphology. It consists of a faint front followed by diffuse emission and the bright loop-like CME leading edge. We show that the faint front is caused by density compression at a wave (or possibly shock) front driven by the CME. We also present high-detailed multi-wavelength EUV observations that clarify the relative positioning of the prominence at the bottom of a coronal cavity with clear flux rope structure. Finally, we visually check the full LASCO CME database for flux rope structures. In the process, we classify the events into two clear flux rope classes (`3-part', `Loop'), jets and outflows (no clear structure). We find that at least 40% of the observed CMEs have clear flux rope structures. We propose a new definition for flux rope CMEs (FR-CMEs) as a coherent magnetic, twist-carrying coronal structure with angular width of at least 40 deg and able to reach beyond 10 Rsun which erupts on a time scale of a few minutes to several hours. We conclude that flux ropes are a common occurrence in CMEs and pose a challenge for future studies to identify CMEs that are clearly not FR-CMEs.Comment: 26 pages, 9 figs, to be published in Solar Physics Topical Issue "Flux Rope Structure of CMEs

Sorting Nexin 24 is required for α-granule biogenesis and cargo delivery in megakaryocytes

Germline defects affecting the DNA-binding domain of the transcription factor FLI1 are associated with a bleeding disorder that is characterised by the presence of large, fused α-granules in platelets. We investigated whether the genes showing abnormal expression in FLI1-deficient platelets could be involved in platelet α-granule biogenesis by undertaking transcriptome analysis of control platelets and platelets harbouring a DNA-binding variant of FLI1. Our analysis identified 2276 transcripts that were differentially expressed in FLI1- deficient platelets. Functional annotation clustering of the coding transcripts revealed significant enrichment for gene annotations relating to protein transport, and identified Sorting nexin 24 (SNX24) as a candidate for further investigation. Using an iPSC-derived megakaryocyte model, SNX24 expression was found to be increased during the early stages of megakaryocyte differentiation and downregulated during proplatelet formation, indicating tight regulatory control during megakaryopoiesis. CRISPR-Cas9 mediated knockout (KO) of SNX24 led to decreased expression of immature megakaryocyte markers, CD41 and CD61, and increased expression of the mature megakaryocyte marker CD42b (p=0.0001), without affecting megakaryocyte polyploidisation, or proplatelet formation. Electron microscopic analysis revealed an increase in empty membrane-bound organelles in SNX24 KO megakaryocytes, a reduction in α-granules and an absence of immature and mature multivesicular bodies, consistent with a defect in the intermediate stage of α-granule maturation. Co-localisation studies showed that SNX24 associates with each compartment of α-granule maturation. Reduced expression of CD62P and VWF was observed in SNX24 KO megakaryocytes. We conclude that SNX24 is required for α-granule biogenesis and intracellular trafficking of α-granule cargo within megakaryocytes