In this study, ex-situ experiments performed with a point injection device are conducted to evaluate water distributions in gas diffusion layer (GDL) materials which serve as porous transport media ...in polymer electrolyte membrane fuel cells (PEMFCs). In this regard, GDL samples manufactured by SGL Group are placed into the point injection device and visualized by means of synchrotron X-ray radiographic and tomographic imaging. The resulting image data undergoes a coordinate transformation that ascertains water agglomerations in GDL pores with regard to their radial displacements from the injection point. In this way, water transport in two different GDL samples possessing the same structural characteristics, but with unique compression rates, are investigated in terms of in-plane water distribution. The radial displacement analysis indicated that the pore saturation of the compressed GDL is higher in both the micro porous layer (MPL) region and the carbon fiber substrate region than that of the uncompressed GDL. The water agglomerations in the uncompressed GDL are predominantly observed in the vicinity of the injection point, indicating a limited in-plane transport. Conversely, in the compressed case water accumulations are detected far from the injection point, even at the edge of the GDL, pointing out that compression promotes the in-plane transport. Prior to the ex-situ experiments, both GDL samples have undergone an ageing procedure to mimic realistic cell operating conditions.
•In-plane water transport in GDL is revealed by radial displacement analysis.•GDL compression increases in-plane water transport.•Gas-phase geometric tortuosity correlates with in-plane water transport.•Artificial accelerated degradation of GDL mimics realistic cell conditions.
A clinical course ranging from mild local findings to life-threatening systemic findings may occur after scorpion stings. The purpose of this study was to identify priority markers indicating ...scorpion sting–related cardiac involvement.
Our study was performed between July 2014, and September 2015 in the Çukurova University medical faculty pediatric emergency department, in Adana, Turkey. Patients admitted with scorpion sting–related cardiac involvement and a control group consisting of patients with no scorpion sting–related cardiac involvement were included in the study. Troponin I at time of presentation and at 6 and 24 h, N-terminal prohormone of brain natriuretic peptide (NTproBNP), ejection fraction as determined by echocardiography at 24 h, and peak and end of T wave (Tp-e) and Tp-e/QTc ratios with echocardiography at 24 h were evaluated.
A patient group consisting of 7 cases of scorpion envenomation–related myocarditis and a control group of 30 cases of scorpion intoxication without myocarditis findings were enrolled. Statistically significantly high glucose, white blood cell values, creatine kinase MB, troponin I, and NTproBNP values were identified in the scorpion sting–related myocarditis group (P<0.05). Ejection fractions determined by echocardiography at time of presentation were significantly lower in the patients with myocarditis compared with the control group (P<0.05). A statistically significant difference was identified between Tp-e/corrected QT interval (QTc) ratios investigated in DI and V2 derivations in patient and control group echocardiograms (P<0.05).
We think that use can be made of NTproBNP in addition to echocardiography and troponin I in the early diagnosis of scorpion sting–related myocarditis and that Tp-e and Tp-e/QTc ratios identified via echocardiography can be used as early markers; however, further studies with larger numbers are needed to confirm this.
Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy. Many factors such as diabetes mellitus, hypothyroidism, hormonal replacement therapy, corticosteroid use, rheumatoid arthritis ...and wrist fractures may cause CTS. Metabolic syndrome includes abdominal obesity, dyslipidemia, hyperglycemia, and hypertension that may cause CTS. In this study, we aimed to evaluate the relation between CTS and metabolic syndrome. We studied 107 (96 female and 11 male) right‐handed patients who had a clinical and electrophysiologically confirmed diagnosis of CTS. We then divided the patients into two groups (patients with and without metabolic syndrome) according to the criteria of ATP III definition. Eighty (75%) of the patients with CTS had metabolic syndrome. Among the 80 patients with metabolic syndrome, CTS was found in 150 hands (43 mild, 58 moderate and 49 severe cases). Among the 27 patients without metabolic syndrome, CTS was found in 43 hands (27 mild, 14 moderate and 2 severe cases). The electrophysiological parameters (median nerve distal motor latency, median nerve motor amplitude, median nerve motor conduction velocity, median nerve sensory onset latency, median nerve sensory amplitude and median nerve sensory conduction velocity) were worse in patients with metabolic syndrome (P < 0.05). In conclusion, metabolic syndrome was found to be three times more common in patients with CTS and CTS was more severe in patients with metabolic syndrome when compared with those without metabolic syndrome.
Although surgical decompression of large hemispheric infarction is often a life-saving procedure, many patients remain functionally dependent. The aims of this study were to identify specific factors ...that can be used to predict functional outcome, thus establish predictive criteria to reduce poor surgical results.
In this non-randomized prospective study, we performed decompressive craniectomy in 32 patients (age range, 27 to 77 years) with large hemispheric infarctions. Based on their modified Rankin Score (RS), which was calculated 6 months postoperatively, patients were divided into two functional groups: good (RS 0-3, n = 7) and poor (RS 4-6, n = 25). The characteristics of the two groups were compared using statistical analysis.
One-month mortality was 31%. However, most of the surviving patients were severely disabled (RS 4 or 5), and 6-month total mortality reached 50%. Increased age (> or = 60 years) (P = 0.010), preoperative midline shift greater than 10 mm (P = 0.008), low preoperative Glasgow Coma Score (GCS < or = 7) (P = 0.002), presence of preoperative anisocoria (P = 0.032), early (within the first three days of the stroke) clinical deterioration (P = 0.032), and an internal carotid artery infarct (P = 0.069) were the positive predictors of a poor outcome.
We view decompressive craniectomy for space-occupying large hemispheric infarction as a life-sparing procedure that sometimes yields good functional outcomes. A dominant hemispheric infarction should not be an exclusion criterion when deciding to perform this operation. Early operation and careful patient selection based on the above-mentioned factors may improve the functional outcome of surgical management for large hemispheric infarction.
The scattering of dark matter (DM) particles with sub-GeV masses off nuclei is difficult to detect using liquid xenon-based DM search instruments because the energy transfer during nuclear recoils is ...smaller than the typical detector threshold. However, the tree-level DM-nucleus scattering diagram can be accompanied by simultaneous emission of a bremsstrahlung photon or a so-called "Migdal" electron. These provide an electron recoil component to the experimental signature at higher energies than the corresponding nuclear recoil. The presence of this signature allows liquid xenon detectors to use both the scintillation and the ionization signals in the analysis where the nuclear recoil signal would not be otherwise visible. We report constraints on spin-independent DM-nucleon scattering for DM particles with masses of 0.4-5 GeV/c^{2} using 1.4×10^{4} kg day of search exposure from the 2013 data from the Large Underground Xenon (LUX) experiment for four different classes of mediators. This analysis extends the reach of liquid xenon-based DM search instruments to lower DM masses than has been achieved previously.
Dual-phase xenon detectors, as currently used in direct detection dark matter experiments, have observed elevated rates of background electron events in the low energy region. While this background ...negatively impacts detector performance in various ways, its origins have only been partially studied. In this paper we report a systematic investigation of the electron pathologies observed in the LUX dark matter experiment. We characterize different electron populations based on their emission intensities and their correlations with preceding energy depositions in the detector. By studying the background under different experimental conditions, we identified the leading emission mechanisms, including photoionization and the photoelectric effect induced by the xenon luminescence, delayed emission of electrons trapped under the liquid surface, capture and release of drifting electrons by impurities, and grid electron emission. We discuss how these backgrounds can be mitigated in LUX and future xenon-based dark matter experiments.
To conduct simulations of transport properties within fuel cell materials 3D-data are required as input. For a functional simulation of flow and thermal characteristics the morphological features of ...the gas diffusion layer (GDL) materials must be well-defined. In this regard, the distribution of the distinct substances in the GDL, each of which is represented by a different parameter set, plays a decisive role. By means of synchrotron X-Ray computed tomography a fuel cell equipped with SGL® 28BC GDL material is recorded in 3D. The segmentation of the solid structural components and the identification of water agglomerations in the components are fulfilled by image processing techniques. This step is often realized using a lot of simplifications, like the reduction to only one or two different materials or idealized structural characteristics. In the presented work 8 different phases are defined according to the cell materials, which are the catalyst layer, the carbon fibers, the Teflon (PTFE)-binder, the micro porous layer (MPL), the flow field ribs, the pore spaces as well as the water in pore spaces of the GDL substrate and in the MPL. The image processing steps used for the classification of each voxel into these phases are described in detail in this work. Benefiting from this classification methodology, the macroscopic properties of the GDL materials such as water saturation, diffusivity, thermal and electrical conductivity can be obtained in simulations.
•Operated PEMFC recorded by synchrotron X-Ray tomography.•Described 3D image processing allows for classification of eight different phases.•Classified 3D data highly suitable for simulations of water transport properties.
Various dark matter models predict annual and diurnal modulations of dark matter interaction rates in Earth-based experiments as a result of the Earth’s motion in the halo. Observation of such ...features can provide generic evidence for detection of dark matter interactions. This paper reports a search for both annual and diurnal rate modulations in the LUX dark matter experiment using over 20 calendar months of data acquired between 2013 and 2016. This search focuses on electron recoil events at low energies, where leptophilic dark matter interactions are expected to occur and where the DAMA experiment has observed a strong rate modulation for over two decades. By using the innermost volume of the LUX detector and developing robust cuts and corrections, we obtained a stable event rate of 2.3±0.2 cpd/keVee/tonne, which is among the lowest in all dark matter experiments. No statistically significant annual modulation was observed in energy windows up to 26 keVee. Between 2 and 6 keVee, this analysis demonstrates the most sensitive annual modulation search up to date, with 9.2σ tension with the DAMA/LIBRA result. We also report no observation of diurnal modulations above 0.2 cpd/keVee/tonne amplitude between 2 and 6 keVee.
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