393 research outputs found

    TOLERANCE OF PHYSICAL EFFORT IN PATIENTS WITH SURGICALLY TREATED SCOLIOSIS

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    Fourty-eight patients were treated operatively for idiopathic scoliosis by means of CotrelDubousset technique heaving pre-operative angle values of 50¬į_70¬į. Exercise test was performed using cycle ergometer both in pre-and postoperative period. Cardiorespiratory parameters were constantly measured throughout the test to estimate ventilation threshold. Following parameters were included: heart rate, oxygen intake, lung ventilation per minute, rate and volume of ventilation, as well as power and work performed. Test was terminated when ventilation threshold was achieved. This is considered noninvasive method to calculate threshold of anaerobic metabolism. Maximal oxygen intake was indicated by means of Astrand-Ryhming nomogram. Body weight and height were also measured. Operative treatment of scoliosis using Cotrel-Dubousset method enhances physical efficiency moderately most probably due to improvement of respiratory mechanics, increase in ventilation per minute during exercise test through deepening of breaths rather than increase in ventilation rate

    EVALUATION OF PROPRIOCEPTION AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION IN PROFESSIONAL FOOTBALL PLAYERS

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    Rehabilitation after the anterior cruciate ligament reconstruction is an essential element to treat knee instability. Proprioception improvement is one of the most important goals of the rehabilitation program (Rehm, A. et. all 1997). The aim of this paper is to evaluate proprioception of professional football players 6 months after the ACL reconstruction in comparison to proprioception of healthy football players using the Dynamic Riva Test

    Organic thin film photofaradaic pixels for on-demand electrochemistry in physiological conditions

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    We report ultrathin organic photovoltaic elements optimized to run photofaradaic reactions in biological conditions. We demonstrate concurrent oxygen reduction to hydrogen peroxide and glucose oxidation. The devices are powered by deep-red irradiation in the tissue transparency window. We utilize bilayers of phthalocyanine, acting as the light absorber, and perylene diimide, functioning as both electron-acceptor and the hydrogen peroxide evolution electrocatalyst. These heterojunction bilayers are stable when irradiated in simulated physiological conditions, producing photovoltages sufficient to simultaneously drive cathodic oxygen reduction to H2O2 and anodic oxidation of glucose. We find that optimization of the anode metal is critical for sustained photofaradaic reactivity. Our results demonstrate a robust "wet" thin film photovoltaic with potential for physiological applications where localized electrochemical manipulation is desired, in particular the delivery of reactive oxygen species.Funding Agencies|Knut and Alice Wallenberg Foundation of the Wallenberg Centre for Molecular Medicine at Linkoping University; Knut and Alice Wallenberg Foundation of the Wallenberg Wood Science Centre 2.0; Swedish Research Council (Vetenskapsradet)Swedish Research Council [2018-04505]</p

    Photochemical evolution of hydrogen peroxide on lignins

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    Means of sustainable on-demand hydrogen peroxide production are sought after for numerous industrial, agricultural, and environmental applications. Herein we present the capacity of lignin and lignin sulfonate to behave as photocatalysts that upon irradiation reduce oxygen to hydrogen peroxide. Water-soluble lignin sulfonate acts as a homogeneous photocatalyst in solution, while lignin in thin-film form behaves as a heterogenous photocatalyst. In both cases, the photochemical cycle is closed via the oxidation of electron donors in solution, a process which competes with the autooxidation of lignin. Therefore, lignins can be destructively photooxidized to produce hydrogen peroxide as well as photochemically oxidizing low-oxidation potential species. These findings enable new photochemistry applications with abundant biopolymers and inform the growing body of knowledge on photochemical evolution of hydrogen peroxide.Funding Agencies|Knut and Alice Wallenberg FoundationKnut &amp; Alice Wallenberg Foundation; Wallenberg Wood Science Centre 2.0; Wallenberg Centre for Molecular Medicine at Linkoping University; VinnovaVinnova</p

    Tuning photoelectrochemical performance of poly(3-hexylthiophene) electrodesviasurface structuring

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    Organic semiconductors are gaining increasing attention as promising active materials in aqueous electrochemical and photoelectrochemical applications. Controlling the semiconductor/electrolyte interface is a critical aspect. The aim of this work is to increase the electrochemical surface area of an archetypical polymeric semiconductor, poly(3-hexylthiophene), P3HT. Here we use a technique of blending with polystyrene, phase separation, followed by selective removal of polystyrene to obtain various nano/microstructures of P3HT. We evaluate how three-dimensional structuring of P3HT affects electrochemical capacitance, photovoltage generation, and photoelectrochemical currents. The aqueous wettability of the exposed surface is critical, and it can be significantly modified by employing oxygen plasma treatment. Structured and plasma-hydrophilized P3HT samples demonstrate higher photoelectrochemical currents for the oxygen reduction reaction. We find that regardless of structuring and photocurrent performance, the oxygen reduction on P3HT always proceeds to produce H(2)O(2)with 90%+ faradaic efficiency. The results of our efforts are demonstrations of how to tune and to increase both electrochemical capacitive and faradaic behavior of P3HT layers. Our findings indicate some limitations imposed by the P3HT itself, including low photovoltages and photochemical bleaching. Overall, these findings answer several open questions in the field of P3HT photoelectrochemical interfaces, and provide some general guidelines that can be applied to other organic semiconducting materials.Funding Agencies|Knut and Alice Wallenberg Foundation within the framework of the Wallenberg Wood Science Centre 2.0; Wallenberg Centre for Molecular Medicine at Linkoping; Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research; National Science Centre, Poland [2019/33/B/ST5/01212]</p

    Organic heterojunction photocathodes for optimized photoelectrochemical hydrogen peroxide production

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    Solar-to-chemical conversion of sunlight into hydrogen peroxide as a chemical fuel is an emerging carbon-free sustainable energy strategy. The process is based on the reduction of dissolved oxygen to hydrogen peroxide. Only limited amounts of photoelectrode materials have been successfully explored for photoelectrochemical production of hydrogen peroxide. Herein we detail approaches to produce robust organic semiconductor photocathodes for peroxide evolution. They are based on evaporated donor-acceptor heterojunctions between phthalocyanine and tetracarboxylic perylenediimide, respectively. These small molecules form nanocrystalline films with good operational stability and high surface area. We discuss critical parameters which allow fabrication of efficient devices. These photocathodes can support continuous generation of high concentrations of peroxide with faradaic efficiency remaining at around 70%. We find that an advantage of the evaporated heterojunctions is that they can be readily vertically stacked to produce tandem cells which produce higher voltages. This feature is desirable for fabricating two-electrode photoelectrochemical cells. Overall, the photocathodes presented here have the highest performance reported to date in terms of photocurrent for peroxide production. These results offer a viable method for peroxide photosynthesis and provide a roadmap of strategies that can be used to produce photoelectrodes with even higher efficiency and productivity.Funding Agencies|Knut and Alice Wallenberg Foundation; Wallenberg Centre for Molecular Medicine at Linkoping University; Vinnova within the framework of Treesearch.se</p

    Faradaic Fenton Pixel ‚Äď Reactive Oxygen Species Delivery using Au/Cr Electrochemistry

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    Reactive oxygen species (ROS) are an integral part of many anticancer therapies. Fenton-like processes involving reactions of peroxides with transition metal ions are a particularly potent and tunable subset of ROS approaches. Precise on-demand dosing of the Fenton reaction is an area of great interest. Herein, we present a concept of an electrochemical faradaic pixel which produces controlled amounts of ROS via a Fenton-like process. The pixel comprises a cathode and anode, where the cathode reduces dissolved oxygen to hydrogen peroxide. The anode is made of chromium, which is electrochemically corroded to yield chromium ions. Peroxide and chromium interact to form a highly oxidizing mixture of hydroxyl radicals and hexavalent Cr-ions. After benchmarking the electrochemical properties of this type of device, we demonstrate how it can be used under in vitro conditions with a cancer cell line. The faradaic Fenton pixel is a general and scalable concept that can be used for on-demand delivery of redox-active products for controlling a physiological outcome.Validerad;2023;Nivå 2;2023-11-09 (hanlid);Funder: Grant Agency of the Czech Republic (23-07432S); Brno City Municipality;This article also appears in "Society Volumes: Czech Republic" and "Society Volumes: Sweden";Full text license: CC BY</p
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