144 research outputs found

    Integrated Polyphenol-Based Hydrogel Templating Method for Functional and Structured Oxidic Nanomaterials

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    A straightforward fabrication method for tunable nanomaterials remains a key objective in the research areas of template chemistry, catalysis, and energy storage materials. A growing focus in materials chemistry is the development of structuring methods that are simple, scalable, and, at the same time, feasible with environmentally benign chemicals. We present a hydrogel-mediated templating method that yields customizable, porous transition-metal oxides. The protocol is extremely simple and includes predominately naturally occurring compounds. For example, the incorporation of sacrificial polymer latex into a polyphenolic hydrogel network produces xerogel composites with various filler contents. Voids are generated simultaneously during the pyrolysis of the dried gel, allowing for controlling the three-dimensional (3D) arrangement of titania nanocrystals. As a proof of concept, we use the produced macroporous titania as a negative electrode (anode) material in lithium-ion batteries. We demonstrate that the gel-derived macroporous anatase significantly reduces the capacity loss compared to its commercial or nonporous analogues. The modularity of this one-pot templating protocol is further demonstrated by the fabrication of titanate nanostructures and porous zirconia

    Quantitative Sensory Testing in adults with Tourette syndrome

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    INTRODUCTION: Abnormal sensory perceptions, for instance hypersensitivity to certain external stimuli or premonitory urges preceding tics, are core features in Gilles de la Tourette syndrome (GTS). Aberrant awareness of externally applied stimuli in terms of altered sensory perception thresholds might contribute to these sensory phenomena in GTS. METHODS: We used the well-established and standardized “Quantitative Sensory Testing” (QST) battery (German Research Network on Neuropathic Pain) to investigate 13 sensory parameters including thermal, mechanical/tactile and pain thresholds in 14 GTS patients without clinically significant comorbidities and 14 healthy controls matched for age and gender. RESULTS: There were no relevant group differences in any of the 13 QST parameters and no specific QST pattern in GTS patients. There was no correlation between QST parameters and “Premonitory Urge for Tics scale” (PUTS) scores. CONCLUSION: Our data show that the perceptual threshold detection of externally applied sensory stimuli is normal in adults with GTS. This indicates that other perceptual mechanisms, such as abnormal central sensorimotor processing and/or aberrant interoceptive awareness might underlie the clinically significant sensory abnormalities in GTS

    End-stage extension of the knee and its influence on tibial tuberosity-trochlear groove distance (TTTG) in asymptomatic volunteers

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    PURPOSE: Increased tibial tuberosity-trochlear groove distance (TTTG) is one potential correcting parameter in patients suffering from lateral patellar instability. It was hypothesized that end-stage extension of the knee might influence the TTTG distance on MR images. METHODS: Transverse T1-weighted MR images of the knee were acquired at full extension, 15° and 30° flexion of the knee in 30 asymptomatic volunteers. MRI parameters: slice thickness: 3 mm, matrix: 256 × 384, FOV: 150 × 150 mm. Two observers independently measured the TTTG at all positions. RESULTS: Mean TTTG for observer 1 was 15.1 ± 3.2 mm at full extension, 10.0 ± 3.5 mm at 15° flexion and 8.1 ± 3.4 mm at 30° flexion. Mean TTTG for observer 2: 14.8 ± 3.3 mm at full extension, 9.4 ± 3.0 mm at 15° flexion, 8.6 ± 3.4 mm at 30° flexion. Mean values were significantly different (p < 0.001) between full extension and 15° as well as 30° flexion for both observers. Mean values were significantly different (p < 0.001) between 15° and 30° for observer 1, but not for observer 2 (n.s.). Interobserver agreement was very good (intraclass correlation coefficient: 0.87-0.88; p < 0.001). CONCLUSIONS: The TTTG increases significantly at the end-stage extension of the knee. Therefore, the comparability of published TTTG values measured on radiographs, CT and MRI at various flexion/extension angles of the knee are limited. LEVEL OF EVIDENCE: Development of diagnostic criteria in a consecutive series of patients and a universally applied 'gold' standard, Level II

    Venous gas embolism as a predictive tool for improving CNS decompression safety

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    A key process in the pathophysiological steps leading to decompression sickness (DCS) is the formation of inert gas bubbles. The adverse effects of decompression are still not fully understood, but it seems reasonable to suggest that the formation of venous gas emboli (VGE) and their effects on the endothelium may be the central mechanism leading to central nervous system (CNS) damage. Hence, VGE might also have impact on the long-term health effects of diving. In the present review, we highlight the findings from our laboratory related to the hypothesis that VGE formation is the main mechanism behind serious decompression injuries. In recent studies, we have determined the impact of VGE on endothelial function in both laboratory animals and in humans. We observed that the damage to the endothelium due to VGE was dose dependent, and that the amount of VGE can be affected both by aerobic exercise and exogenous nitric oxide (NO) intervention prior to a dive. We observed that NO reduced VGE during decompression, and pharmacological blocking of NO production increased VGE formation following a dive. The importance of micro-nuclei for the formation of VGE and how it can be possible to manipulate the formation of VGE are discussed together with the effects of VGE on the organism. In the last part of the review we introduce our thoughts for the future, and how the enigma of DCS should be approached

    Fire and High-Elevation, Five-Needle Pine (Pinus aristata & P. flexilis) Ecosystems in the Southern Rocky Mountains: What Do We Know?

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    Rocky Mountain bristlecone pine (Pinus aristata Engelm) and limber pine (P. flexilis James) are high-elevation, five- needle pines of the southern Rocky Mountains. The pre-settlement role of fire in bristlecone and limber pine forests remains the sub- ject of considerable uncertainty; both species likely experienced a wide range of fire regimes across gradients of site productivity and connectivity of fuels and flammable landscapes. In dense stands and more continuous forests, stand history reconstructions provide evidence for infrequent, high-severity fires. Limber pine can be dispersed long distances by Clark’s nutcrackers (Nucifraga colum- biana), and in the high-elevation subalpine forests of the northern Colorado Front Range, it is an early colonist of extensive, high- severity burns. However, this relationship with fire may not be general to the southern Rockies. The degree to which high-severity fire was typical of bristlecone pine, and the spatial extent of such fires, is uncertain. Following fire, bristlecone pine regeneration tends to be constrained to burn edges or beneath surviving trees. In both five-needle pines, regeneration dynamics take decades to centuries. Where open stands border grassy openings both species frequently exhibit fire scars indicative of fairly frequent but low- intensity fire; because of the great ages attained by both species, they offer potentially very long fire history reconstructions in such settings. Whether or not fire suppression has led to declines in either species—through successional shifts to shade-tolerant com- petitors or by shifts to a stand replacing fire-regime—remains an open question that deserves further inquiry. In any case, re-estab- lishing pre-settlement fire regimes, whatever they were, may not be as important as determining appropriate disturbance regimes given current conditions and management objectives. Both species are highly susceptible to rapid declines caused by white pine blister rust (Cronartium ribicola) and mountain pine beetles (Dendroctonus ponderosae). In the face of these threats, and uncertain consequences of climate change, fire management (both prevention and applica- tion) can be a tool to promote resilient landscapes. Appropriate fire management may be used to conserve valuable stands, pro- mote regeneration and diversify age class structures, and/or alter the balance between these species and their competitors. Many of these themes and questions indicate the need for further basic and applied research
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