Quantized conductance and its correlation to the supercurrent in a nanowire connected to superconductors

We report conductance and supercurrent of InAs nanowires coupled to Al-superconducting electrodes with short channel lengths and good Ohmic contacts. The nanowires are suspended 15\,nm above a local gate electrode. The charge density in the nanowires can be controlled by a small change in the gate voltage. For large negative gate voltages, the number of conducting channels is reduced gradually and we observe a stepwise decrease of both conductance and critical current before the conductance vanishes completely

Charge transport in InAs nanowire Josephson junctions

We present an extensive experimental and theoretical study of the proximity effect in InAs nanowires connected to superconducting electrodes. We fabricate and investigate devices with suspended gate-controlled nanowires and nonsuspended nanowires, with a broad range of lengths and normal-state resistances. We analyze the main features of the current-voltage characteristics: the Josephson current, excess current, and subgap current as functions of length, temperature, magnetic field, and gate voltage, and compare them with theory. The Josephson critical current for a short-length device, L = 30 nm, exhibits a record high magnitude of 800 nA at low temperature that comes close to the theoretically expected value. The critical current in all other devices is typically reduced compared to the theoretical values. The excess current is consistent with the normal resistance data and agrees well with the theory. The subgap current shows a large number of structures; some of them are identified as subharmonic gap structures generated by multiple Andreev reflection. The other structures, detected in both suspended and nonsuspended devices, have the form of voltage steps at voltages that are independent of either the superconducting gap or length of the wire. By varying the gate voltage in suspended devices, we are able to observe a crossover from typical tunneling transport at large negative gate voltage, with suppressed subgap current and negative excess current, to pronounced proximity junction behavior at large positive gate voltage, with enhanced Josephson current and subgap conductance as well as a large positive excess current.Comment: 12 pages, 15 figure

A Novel Approach to Reduction of Frictional Losses in a Heavy-Duty Diesel Engine by Reducing the Hydrodynamic Frictional Losses

An important parameter in the reduction of fuel consumption of heavy-duty diesel engines is the Power Cylinder Unit (PCU); the PCU is the single largest contributor to engine frictional losses. Much attention, from both academia and industry, has been paid to reducing the frictional losses of the PCU in the boundary and mixed lubrication regime. However, previous studies have shown that a large portion of frictional losses in the PCU occur in the hydrodynamic lubrication regime. A novel texturing design with large types of surface features was experimentally analyzed using a tribometer setup. The experimental result shows a significant reduction of friction loss for the textured surfaces. Additionally, the textured surface did not exhibit wear. On the contrary, it was shown that the textured surfaces exhibited a smaller amount of abrasive scratches on the plateaus (compared to the reference plateau honed surface) due to entrapment of wear particles within the textures. The decrease in hydrodynamic friction for the textured surfaces relates to the relative increase of oil film thickness within the textures. A tentative example is given which describes a method of decreasing hydrodynamic frictional losses in the full-scale application

Investigating psychometric properties and dimensional structure of an educational environment measure (DREEM) using Mokken scale analysis - A pragmatic approach

© 2018 The Author(s). Background: Questionnaires and surveys are used throughout medical education. Nevertheless, measuring psychological attributes such as perceptions of a phenomenon among individuals may be difficult. The aim of this paper is to introduce the basic principles of Mokken scale analysis (MSA) as a method for the analysis of questionnaire data and to empirically apply MSA to a real-data example. Methods: MSA provides a set of statistical tools for exploring the relationship between items and latent traits. MSA is a scaling method of item selection algorithms used to partition an array of items into scales. It employs various methods to probe the assumptions of two nonparametric item response theory models: the monotone homogeneity model and the double monotonicity model. The background and theoretical framework underlying MSA are outlined in the paper. MSA for polytomous items was applied to a real-life data example of 222 undergraduate students who had completed a 50-item self-administered inventory measuring the educational environment, the Dundee Ready Educational Measure (DREEM). Results: A pragmatic and parsimonious approach to exploring questionnaires and surveys from an item response theory (IRT) perspective is outlined. The use of MSA to explore the psychometric properties of the Swedish version of the DREEM failed to yield strong support for the scalability and dimensional structure of the instrument. Conclusions: MSA, a class of simple nonparametric IRT models - for which estimates can be easily obtained and whose fit to data is relatively easily investigated - was introduced, presented, and tested. Our real-data example suggests that the psychometric properties of DREEM are not adequately supported. Thus, the empirical application depicted a potential and feasible approach whereby MSA could be used as a valuable method for exploring the behavior of scaled items in response to varying levels of a latent trait in medical education research

Molecular Dynamics Simulations of Cellulose and Dialcohol Cellulose under Dry and Moist Conditions

The development of wood-based thermoplastic polymers that can replace synthetic plastics is of high environmental importance, and previous studies have indicated that cellulose-rich fiber containing dialcohol cellulose (ring-opened cellulose) is a very promising candidate material. In this study, molecular dynamics simulations, complemented with experiments, were used to investigate how and why the degree of ring opening influences the properties of dialcohol cellulose, and how temperature and presence of water affect the material properties. Mechanical tensile properties, diffusion/mobility-related properties, densities, glass-transition temperatures, potential energies, hydrogen bonds, and free volumes were simulated for amorphous cellulosic materials with 0-100% ring opening, at ambient and high (150 \ub0C) temperatures, with and without water. The simulations showed that the impact of ring openings, with respect to providing molecular mobility, was higher at high temperatures. This was also observed experimentally. Hence, the ring opening had the strongest beneficial effect on “processability” (reduced stiffness and strength) above the glass-transition temperature and in wet conditions. It also had the effect of lowering the glass-transition temperature. The results here showed that molecular dynamics is a valuable tool in the development of wood-based materials with optimal thermoplastic properties

Complement C3b contributes to Escherichia coli-induced platelet aggregation in human whole blood

IntroductionPlatelets have essential functions as first responders in the immune response to pathogens. Activation and aggregation of platelets in bacterial infections can lead to life-threatening conditions such as arterial thromboembolism or sepsis-associated coagulopathy.MethodsIn this study, we investigated the role of complement in Escherichia coli (E. coli)-induced platelet aggregation in human whole blood, using Multiplate® aggregometry, flow cytometry, and confocal microscopy.Results and DiscussionWe found that compstatin, which inhibits the cleavage of complement component C3 to its components C3a and C3b, reduced the E. coli-induced platelet aggregation by 42%-76% (p = 0.0417). This C3-dependent aggregation was not C3a-mediated as neither inhibition of C3a using a blocking antibody or a C3a receptor antagonist, nor the addition of purified C3a had any effects. In contrast, a C3b-blocking antibody significantly reduced the E. coli-induced platelet aggregation by 67% (p = 0.0133). We could not detect opsonized C3b on platelets, indicating that the effect of C3 was not dependent on C3b-fragment deposition on platelets. Indeed, inhibition of glycoprotein IIb/IIIa (GPIIb/IIIa) and complement receptor 1 (CR1) showed that these receptors were involved in platelet aggregation. Furthermore, aggregation was more pronounced in hirudin whole blood than in hirudin platelet-rich plasma, indicating that E. coli-induced platelet aggregation involved other blood cells. In conclusion, the E. coli-induced platelet aggregation in human whole blood is partly C3b-dependent, and GPIIb/IIIa and CR1 are also involved in this process

In vitro evaluation of iron oxide nanoparticle-induced thromboinflammatory response using a combined human whole blood and endothelial cell model

Iron oxide nanoparticles (IONPs) are widely used in diagnostic and therapeutic settings. Upon systemic administration, however, they are rapidly recognized by components of innate immunity, which limit their therapeutic capacity and can potentially lead to adverse side effects. IONPs were previously found to induce the inflammatory response in human whole blood, including activation of the complement system and increased secretion of cytokines. Here, we investigated the thromboinflammatory response of 10-30 nm IONPs in lepirudin anticoagulated whole blood in interplay with endothelial cells and evaluated the therapeutic effect of applying complement inhibitors to limit adverse effects related to thromboinflammation. We found that IONPs induced complement activation, primarily at the C3-level, in whole blood incubated for up to four hours at 37°C with and without human microvascular endothelial cells. Furthermore, IONPs mediated a strong thromboinflammatory response, as seen by the significantly increased release of 21 of the 27 analyzed cytokines (p<0.05). IONPs also significantly increased cell-activation markers of endothelial cells [ICAM-1 (p<0.0001), P/E-selectin (p<0.05)], monocytes, and granulocytes [CD11b (p<0.001)], and platelets [CD62P (p<0.05), CD63 (p<0.05), NAP-2 (p<0.01), PF4 (p<0.05)], and showed cytotoxic effects, as seen by increased LDH (p<0.001) and heme (p<0.0001) levels. We found that inflammation and endothelial cell activation were partly complement-dependent and inhibition of complement at the level of C3 by compstatin Cp40 significantly attenuated expression of ICAM-1 (p<0.01) and selectins (p<0.05). We show that complement activation plays an important role in the IONPs-induced thromboinflammatory response and that complement inhibition is promising in improving IONPs biocompatibility

Subthalamic deep brain stimulation improves smooth pursuit and saccade performance in patients with Parkinson’s disease

© 2013 The Authors. Published by BMC. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1186/1743-0003-10-33Deep brain stimulation (DBS) in the subthalamic nucleus (STN) significantly reduces symptoms of Parkinson’s disease (PD) such as bradykinesia, tremor and rigidity. It also reduces the need for anti-PD medication, and thereby potential side-effects of L-Dopa. Although DBS in the STN is a highly effective therapeutic intervention in PD, its mechanism and effects on oculomotor eye movement control and particularly smooth pursuit eye movements have to date rarely been investigated. Furthermore, previous reports provide conflicting information. The aim was to investigate how DBS in STN affected oculomotor performance in persons with PD using novel analysis techniques. Methods Twenty-five patients were eligible (22 males, 3 females) according to the clinical inclusion criteria: idiopathic PD responsive to L-Dopa and having had bilateral STN stimulation for at least one year to ensure stable DBS treatment. Fifteen patients were excluded due to the strict inclusion criteria applied to avoid interacting and confounding factors when determining the effects of DBS applied alone without PD medication. One patient declined participation. Nine PD patients (median age 63, range 59–69 years) were assessed after having their PD medications withdrawn overnight. They were examined with DBS ON and OFF, with the ON/OFF order individually randomized. Results DBS ON increased smooth pursuit velocity accuracy (p < 0.001) and smooth pursuit gain (p = 0.005), especially for faster smooth pursuits (p = 0.034). DBS ON generally increased saccade amplitude accuracy (p = 0.007) and tended to increase peak saccade velocity also (p = 0.087), specifically both saccade velocity and amplitude accuracy for the 20 and 40 degree saccades (p < 0.05). Smooth pursuit latency tended to be longer (p = 0.090) approaching normal with DBS ON. Saccade latency was unaffected. Conclusions STN stimulation from DBS alone significantly improved both smooth pursuit and saccade performance in patients with PD. The STN stimulation enhancement found for oculomotor performance suggests clear positive implications for patients’ ability to perform tasks that rely on visual motor control and visual feedback. The new oculomotor analysis methods provide a sensitive vehicle to detect subtle pathological modifications from PD and the functional enhancements produced by STN stimulation from DBS alone.The authors’ wish to acknowledge the financial supported from the Swedish Medical Research Council (grant nr. 17x-05693), the Medical Faculty, Lund University, Sweden, and the Swedish Parkinson Academy. This study was performed within the Strategic Research Area Multipark at Lund University and within the context of the Centre for Ageing and Supportive environments (CASE), Lund University, Sweden, funded by the Swedish Council for Working Life and Social Research.Published versio

Double blockade of CD14 and complement C5 abolishes the cytokine storm and improves morbidity and survival in polymicrobial sepsis in mice

Sepsis and septic shock, caused by an excessive systemic host-inflammatory response, are associated with high morbidity and mortality. The complement system and TLRs provide important pattern recognition receptors initiating the cytokine storm by extensive cross-talk. We hypothesized that double blockade of complement C5 and the TLR coreceptor CD14 could improve survival of experimental polymicrobial sepsis. Mice undergoing cecal ligation and puncture (CLP)–induced sepsis were treated with neutralizing anti-CD14 Ab biG 53, complement C5 inhibitor coversin (Ornithodoros moubata C inhibitor), or a combination thereof. The inflammatory study (24-h observation) revealed statistically significant increases in 22 of 24 measured plasma biomarkers in the untreated CLP group, comprising 14 pro- and anti-inflammatory cytokines and 8 chemokines, growth factors, and granulocyte activation markers. Single CD14 or C5 blockade significantly inhibited 20 and 19 of the 22 biomarkers, respectively. Combined CD14 and C5 inhibition significantly reduced all 22 biomarkers (mean reduction 85%; range 54–95%) compared with the untreated CLP group. Double blockade was more potent than single treatment and was required to significantly inhibit IL-6 and CXCL1. Combined inhibition significantly reduced morbidity (motility and eyelid movement) and mortality measured over 10 d. In the positive control CLP group, median survival was 36 h (range 24–48 h). Combined treatment increased median survival to 96 h (range 24–240 h) (p = 0.001), whereas survival in the single-treatment groups was not significantly increased (median and range for anti-CD14 and anti-C5 treatment were 36 h [24–48 h] and 48 h [24–96 h]). Combined with standard intervention therapy, specific blockade of CD14 and C5 might represent a promising new therapeutic strategy for treatment of polymicrobial sepsis