183 research outputs found

    Impact of Chlorine on the Internal Transition Rates and Excited States of the Thermally Delayed Activated Fluorescence Molecule 3CzClIPN

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    We analyze internal transition rates and the singlet-triplet energy gap of the thermally activated delayed fluorescence (TADF) molecule 3CzClIPN, which recently was introduced as an efficient photocatalyst. Distribution and origin of the non-monoexponential decays, which are commonly observed in TADF films, are revealed by analysis of transient fluorescence with an inverse Laplace transform. A numerically robust global rate fit routine, which extracts all relevant TADF parameters by modeling the complete set of data, is introduced. To compare and verify the results, all methods are also applied to the well-known 4CzIPN. The influence of the molecular matrix is discussed by embedding low concentrations of TADF molecules in polystyrene films. Finally, quantum chemical calculations are compared to the experimental results to demonstrate that the chlorine atom increases the charge transfer character of the relevant states, resulting in a reduction of the singlet-triplet energy gap

    Evolution of Relativistic Pair Beams: Implications for Laboratory and TeV Astrophysics

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    Missing cascades from TeV blazar beams indicate that collective plasma effects may play a significant role in their energy loss. It is possible to mimic the evolution of such highly energetic pair beams in laboratory experiments using modern accelerators. The fate of the beam is governed by two different processes, energy loss through the unstable mode and energetic broadening of the pair beam through diffusion in momentum space. We chalk out this evolution using a Fokker-Planck approach in which the drift and the diffusion terms respectively describe these phenomena in a compact form. We present particle-in-cell simulations to trace the complete evolution of the unstable beam-plasma system for a generic narrow Gaussian pair beam for which the growth rate is reactive. We show that the instability leads to an energetic broadening of the pair beam, slowing down the instability growth in the linear phase, in line with the analytical and numerical solutions of the Fokker-Planck equation. Whereas in a laboratory experiment the change in the momentum distribution is an easily measured observable as a feedback of the instability, the consequence of diffusive broadening in an astrophysical scenario can be translated to an increase in the opening angle of the pair beam.Comment: 20 pages, 10 figure

    Self-esteem instability and affective instability in everyday life after remission from borderline personality disorder

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    Background: Borderline personality disorder (BPD) is defined by a pervasive pattern of instability. According to prior findings and clinical theories, self-esteem instability and affective instability are key features of BPD. Previous e-diary studies showed that instability in self-esteem is heightened and that it is highly intertwined with affective instability in BPD in comparison to healthy controls (HC). The present study sought to extend these findings by adding symptomatologically remitted BPD patients (BPD-REM), i.e. former patients with BPD who met four or fewer BPD criteria within the past year, as a comparison group. Methods: To examine differences regarding self-esteem instability and affective instability, we used e-diaries for repeatedly collecting data on self-esteem, valence, and tense arousal 12 times a day for four consecutive days while participants underwent their daily life activities. Determining three different state-of-the-art instability indices and applying multilevel analyses, we compared 35 BPD-REM participants with previously reported 60 acute BPD patients (BPD-ACU) and 60 HC. Results: Our results revealed that self-esteem instability was significantly lower in the BPD-REM compared to the BPD-ACU group, irrespective of the instability index. In contrast, there were no significant differences regarding affective instability between the BPD-REM participants and those in the BPD-ACU group. The comparison between the BPD-REM with the HC indicated both a significantly higher instability in self-esteem as well as significantly heightened affective instability in the BPD-REM participants. Moreover, even though the associations were not significant, we found tentative support for the assumption that affective changes that are accompanied by changes in self-esteem are experienced as more burdensome and negatively impact the quality of life of remitted BPD participants. Conclusions: This study builds on growing evidence for the importance of self-esteem instability in BPD. Whereas affective instability has been reported in various psychiatric disorders and might indeed constitute a transdiagnostic marker of affective dysregulation, our results indicate that self-esteem instability might be a specific symptom that construes the unique pathology in BPD

    Thermodynamic qualification of knitted spacer fabrics for use as insulation box insert in the context of refrigerated transport containers in the logistics sector

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    Temperature-sensitive products such as refrigerated and frozen goods pose particular challenges for logistics. Against the background of the mobility shift towards electric vehicles and the current challenges of temperature-stable transport in the field of pharmaceutical, esp. vaccine logistics in the context of the SARS-CoV-2 pandemic, new, energy-efficient vehicle equipment is needed to maintain cold chains. Known refrigeration concepts are designed to cool the entire cargo hold. In addition, the goods cannot be removed from the vehicle while maintaining the cold chain. An insulating effect of containers is typically achieved by using foamed polystyrene (Styrofoam). On the one hand, these structures have a very good insulating effect, but on the other hand, they cannot be reduced in volume during recirculation and are problematic with regard to recycling. The aim of the research presented here is therefore to develop a knitted box that is designed as a volume-reducible, rigid but foldable box. This can be used as a supplement to existing transport container systems and therefore can be inserted in the transport container. The knitted box performs as insulation when the transported goods are actively cooled inside the box, which is more sustainable and flexible than recent insulation solutions. Knitted fabrics, especially spacer fabrics, have advantageous thermo-physical properties for this application due to their structural design. In the course of a research project, various spacer fabrics were tested for their thermo-physical suitability as insulation materials. It was found that knitted predetermined folding lines represent an insulation gap. Based on this, a new structure was developed which, due to its structural design, compensates for cold or thermal bridges at vertices and edges of the box. The results show that the knitted corrugated structure insulates better than the knitted spacer fabrics with predetermined folding lines. A thermal imaging camera was used to identify critical points for heat transfer

    Electrochemical noise and impedance of Au electrode/electrolyte interfaces enabling extracellular detection of glioma cell populations

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    Microelectrode arrays (MEA) record extracellular local field potentials of cells adhered to the electrodes. A disadvantage is the limited signal-to-noise ratio. The state-of-the-art background noise level is about 10 mu Vpp. Furthermore, in MEAs low frequency events are filtered out. Here, we quantitatively analyze Au electrode/electrolyte interfaces with impedance spectroscopy and noise measurements. The equivalent circuit is the charge transfer resistance in parallel with a constant phase element that describes the double layer capacitance, in series with a spreading resistance. This equivalent circuit leads to a Maxwell-Wagner relaxation frequency, the value of which is determined as a function of electrode area and molarity of an aqueous KCl electrolyte solution. The electrochemical voltage and current noise is measured as a function of electrode area and frequency and follow unambiguously from the measured impedance. By using large area electrodes the noise floor can be as low as 0.3 mu Vpp. The resulting high sensitivity is demonstrated by the extracellular detection of C6 glioma cell populations. Their minute electrical activity can be clearly detected at a frequency below about 10 Hz, which shows that the methodology can be used to monitor slow cooperative biological signals in cell populations

    Quark-hadron duality in electron scattering

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    The duality between partonic and hadronic descriptions of physical phenomena is one of the most remarkable features of strong interaction physics. A classic example of this is in electron-nucleon scattering, in which low-energy cross sections, when averaged over appropriate energy intervals, are found to exhibit the scaling behavior expected from perturbative QCD. We present a comprehensive review of data on structure functions in the resonance region, from which the global and local aspects of duality are quantified, including its flavor, spin and nuclear medium dependence. To interpret the experimental findings, we discuss various theoretical approaches which have been developed to understand the microscopic origins of quark-hadron duality in QCD. Examples from other reactions are used to place duality in a broader context, and future experimental and theoretical challenges are identified.Comment: 198 pages, 80 figures, to appear in Physics Report

    Building an immune-mediated coagulopathy consensus: early recognition and evaluation to enhance post-surgical patient safety

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    Topical hemostats, fibrin sealants, and surgical adhesives are regularly used in a variety of surgical procedures involving multiple disciplines. Generally, these adjuncts to surgical hemostasis are valuable means for improving wound visualization, reducing blood loss or adding tissue adherence; however, some of these agents are responsible for under-recognized adverse reactions and outcomes. Bovine thrombin, for example, is a topical hemostat with a long history of clinical application that is widely used alone or in combination with other hemostatic agents. Hematologists and coagulation experts are aware that these agents can lead to development of an immune-mediated coagulopathy (IMC). A paucity of data on the incidence of IMC contributes to under-recognition and leaves many surgeons unaware that this clinical entity, originating from normal immune responses to foreign antigen exposure, requires enhanced post-operative vigilance and judicious clinical judgment to achieve best outcomes

    An interdisciplinary intervention to prevent falls in community-dwelling elderly persons: protocol of a cluster-randomized trial [PreFalls]

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    <p>Abstract</p> <p>Background</p> <p>Prevention of falls in the elderly is a public health target in many countries around the world. While a large number of trials have investigated the effectiveness of fall prevention programs, few focussed on interventions embedded in the general practice setting and its related network. In the Prevent Falls (PreFalls) trial we aim to investigate the effectiveness of a pre-tested multi-modal intervention compared to usual care in this setting.</p> <p>Methods/Design</p> <p>PreFalls is a controlled multicenter prospective study with cluster-randomized allocation of about 40 general practices to an experimental or a control group. We aim to include 382 community dwelling persons aged 65 and older with an increased risk of falling. All participating general practitioners are trained to systematically assess the risk of falls using a set of validated tests. Patients from intervention practices are invited to participate in a 16-weeks exercise program with focus on fall prevention delivered by specifically trained local physiotherapists. Patients from practices allocated to the control group receive usual care. Main outcome measure is the number of falls per individual in the first 12 months (analysis by negative binomial regression). Secondary outcomes include falls in the second year, the proportion of participants falling in the first and the second year, falls associated with injury, risk of falls, fear of falling, physical activity and quality of life.</p> <p>Discussion</p> <p>Reducing falls in the elderly remains a major challenge. We believe that with its strong focus on a both systematic and realistic fall prevention strategy adapted to primary care setting PreFalls will be a valuable addition to the scientific literature in the field.</p> <p>Trial registration</p> <p><a href="http://www.clinicaltrials.gov/ct2/show/NCT01032252">NCT01032252</a></p
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