36,021 research outputs found

    Nitrite and insulin lower the oxygen cost of ATP synthesis in skeletal muscle cells by pleiotropic stimulation of glycolysis

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    Dietary nitrate lowers the oxygen cost of submaximal exercise, but precise mechanistic insight into how this occurs is lacking. Research suggests that dietary nitrate may render oxidative ATP synthesis more efficient, but evidence is inconclusive at present. This thesis aimed to establish how nitrite (a reduced form of nitrate) affects the bioenergetics of cultured skeletal muscle cells. Comparison between the acute effects of nitrite and insulin, a hormonal regulator of muscle function that increases mitochondrial efficiency, was explored to assess possible mechanistic overlap. Calculation of real-time intracellular ATP synthesis rates from simultaneous oxygen consumption and medium acidification measurements revealed the effects of sodium nitrite and insulin on intact rat (L6) myoblasts and myotubes. These extracellular flux data were also used to determine how mitochondrial and glycolytic ATP supply is used to fuel ATP-demanding processes. The data presented in this thesis revealed that both nitrite and insulin acutely stimulate glycolytic ATP synthesis. This stimulation occurs without significant mitochondrial ATP supply changes, thus increasing the glycolytic index of myocytes. Consequently, nitrite and insulin lower the oxygen cost of cellular ATP supply. Notably, insulin lowers oxygen consumption linked to mitochondrial proton leak, thus increasing mitochondrial efficiency. Nitrite does not improve coupling efficiency in myoblasts or myotubes. Further investigations revealed that stimulation of glycolytic ATP supply is not secondary to increased glucose availability. In myotubes, glycolytic stimulation persists in the presence of a mitochondrial uncoupler, suggesting that glycolysis is increased directly. In myoblasts, stimulation is annulled by uncoupler, suggesting that glycolysis increases indirectly, via increased ATP consumption. The molecular targets of nitrite and insulin remain unclear, but the data exclude stimulation of protein synthesis. Together, the data demonstrate that nitrite and insulin lower the oxygen cost of ATP synthesis in skeletal muscle cells by pleiotropic stimulation of glycolysis. The data inform the ongoing debate regarding the mechanism by which dietary nitrate lowers the oxygen cost of exercise, suggesting a push toward a more glycolytic phenotype. Such mechanistic insight is crucial for achieving the full translational potential of dietary nitrate

    Biomedical applications of polymer and ceramic coatings: a review of recent developments

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    Recent literature concerning the use of polymer and ceramic coatings for a variety of biomedical applications is surveyed in this review. Applications have been grouped into six broad categories: orthopaedic materials, cardiovascular stents, antibacterial surfaces, drug delivery, tissue engineering and biosensors. Polymer and ceramic coatings add enhanced corrosion protection, antiwear, antibacterial and biocompatibility properties to various substrates for biomedical applications. Processes favoured for polymer coating formation included dip, electrodeposition, spin (including electrospin) and spray (including electrospray and ultrasonic spray). Ceramic coatings were formed using magnetron sputtering and a combination of 3-D printing and in-situ mineralisation, among others. The review period is from 2017 to the present (mid-2021)

    Increased lifetime of Organic Photovoltaics (OPVs) and the impact of degradation, efficiency and costs in the LCOE of Emerging PVs

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    Emerging photovoltaic (PV) technologies such as organic photovoltaics (OPVs) and perovskites (PVKs) have the potential to disrupt the PV market due to their ease of fabrication (compatible with cheap roll-to-roll processing) and installation, as well as their significant efficiency improvements in recent years. However, rapid degradation is still an issue present in many emerging PVs, which must be addressed to enable their commercialisation. This thesis shows an OPV lifetime enhancing technique by adding the insulating polymer PMMA to the active layer, and a novel model for quantifying the impact of degradation (alongside efficiency and cost) upon levelized cost of energy (LCOE) in real world emerging PV installations. The effect of PMMA morphology on the success of a ternary strategy was investigated, leading to device design guidelines. It was found that either increasing the weight percent (wt%) or molecular weight (MW) of PMMA resulted in an increase in the volume of PMMA-rich islands, which provided the OPV protection against water and oxygen ingress. It was also found that adding PMMA can be effective in enhancing the lifetime of different active material combinations, although not to the same extent, and that processing additives can have a negative impact in the devices lifetime. A novel model was developed taking into account realistic degradation profile sourced from a literature review of state-of-the-art OPV and PVK devices. It was found that optimal strategies to improve LCOE depend on the present characteristics of a device, and that panels with a good balance of efficiency and degradation were better than panels with higher efficiency but higher degradation as well. Further, it was found that low-cost locations were more favoured from reductions in the degradation rate and module cost, whilst high-cost locations were more benefited from improvements in initial efficiency, lower discount rates and reductions in install costs

    Vanadiinin talteenotto ja hyödyntäminen terästeollisuuden sivuvirroista

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    Tiivistelmä. Vanadiini on arvokas ja tärkeä metalli muun muassa teräs-, kemian- sekä energiateollisuudelle. Terästeollisuus kuluttaa tuotetusta vanadiinista yli 90 %. Vanadiini on myös erittäin kriittinen metalli, vaikka sitä on runsaasti maankuoressa. Se on levinnyt maankuoreen laajasti ja harvaan, joten sen talteenotto primaariraaka-aineesta on kallista. Yleisesti käytössä oleva vanadiinin talteenottomenetelmä koostuu kuonan pasutuksesta, liuotuksesta, liuoksen puhdistuksesta ja vanadiinin erottamisesta sekä saostamisesta. Pasutuksella vanadiini voidaan hapettaa korkeammille hapetusluvuille (+IV, +V). Pasutuksen aikana mineraalifaasit, joissa vanadiini on kuonassa, voivat hajota. Hapetus voidaan tehdä myös nestefaasihapetuksella. Liuotus voidaan tehdä happo-, emäs- tai ammoniumsuolaliuotuksella. Vanadiinin liukoisuus kasvaa hapetusluvun kasvaessa, joten vanadiini pyritään liuottamaan kuonasta vanadaattina. Liukenemiseen vaikuttavat kuonan koostumus, ympäristön olosuhteet sekä valitut liuotusolosuhteet. Tutkielmassa esitetyt tutkimustulokset osoittavat, että happoliuotus oli tehokas, mutta ei selektiivinen. Lisäksi happoliuotuksen jälkeen tarvittin ylimääräisiä reagensseja vanadiinin kiteyttämiseksi ammoniumvanadaattina. Emäsliuotus oli selektiivisempi, mutta vanadiinin saanto ei yltänyt happoliuotuksen tasolle. Erotus- ja puhdistusvaiheita sekä ylimääräisiä reagenssilisäyksiä tarvittiin usein myös emäsliuotuksen jälkeen. Ammoniumsuolaliuotus osoittautui selektiiviseksi ja ei edellyttänyt liuotusvaiheen jälkeen erityisiä puhdistusvaiheita. Ylimääräisiä reagenssilisäyksiä ei tarvittu. Lisäksi ammoniumsuolaliuotuksessa uuttoliuos voitiin kierrättää. Tutkimukset osoittivat, että vanadiini on potentiaalinen alkuaine hyödynnettäväksi uusiutuvan energian varastointiteknologiassa, kuten läpivirtausakuissa. Modifioituja vanadiiniyhdisteitä on ehdotettu myös litiumioniakkujen katodimateriaaleiksi. Esitettyjen tutkimusten pohjalta voidaan arvioida, että vanadiiniyhdisteiden käyttötarve mitä todennäköisemmin tulee nousemaan tulevaisuudessa. Tämän takia vanadiinin talteenottoa terästeollisuuden sivuvirroista on hyödyllistä tutkia

    Mapping Super-Relaxed States of Myosin Heads in Sarcomeres using Oblique Angle Fluorescent Microscopy

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    We have utilised modern methods of super-resolution fluorescent microscopy to spatially map fluorescently labelled ATP molecules in relaxed rabbit psoas skeletal muscles. For our imaging process, we have labelled ATP molecules with Rhodamine and Z-lines with Alexa488. Data from imaging these fluorophores have been collected using oblique angle fluorescent microscopy and further analysed to map super relaxed states (SRX) of myosin heads on the thick filament. Our experiments have concluded that most SRX of myosin heads were found in the C-zone of the thick filament, while other zones of thick filament had smaller populations of SRX. Further introduction of mavacamten (MAVA) to our imaging system has revealed an increase in SRX in both D and P zones, while the C zone population of SRX had remained constant. Further experiments must be conducted to establish a clear pattern and further proof our findings

    Hybrid Perovskite Thin Film

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    Hybrid perovskite thin film offers diverse advantages like low cost deposition techniques, less material consumption and superior optoelectronic properties. These merits including high voltage and high efficiency performance in a wide range of high light intensity are sufficient to distinguish perovskite thin films/devices from their contenders as a thin film technology with greater potential for industrial applications. Perovskite thin film technology demonstrates potency in a variety of applications in optoelectronic devices especially photovoltaic applications. The National Renewable Energy Laboratory (NREL) of the USA categorizes a number of thin films technologies including perovskite thin film, as emerging photovoltaics with the bulk of them yet to be commercially applied but are still in the research or developmental stage. In this chapter, various processing methods and material combinations as well as current trends in this technology are subjects of discussion

    Pharmaceutical and Therapeutic Potentials of Essential Oils

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    It is a common perspective that medicinal plants have played and continue to perform an undeniably major role in the lives of people worldwide. Essential oils are the key constituents of medicinal herbs and their biological activities have been discovered since ancient times and are enormously utilised in multiple industries. The essential oils possess important biological properties like antibacterial, antioxidant, antiviral, insecticidal, etc. Because of these unique features they are more acceptable and are utilised in various fields throughout the world. In the cosmetics industry they play an important role in the development of perfumes while in the food industry they have been used as food preservatives. Essential oil components are interestingly utilised for pharmaceutical applications. The most investigated properties are antioxidant, anti-inflammatory, antimicrobial, wound-healing, anxiolytic activities etc. The current thrust area is evaluation for aromatherapy and anti-cancer, as it is noted that essential oils reported in plants may prevent, inhibit, or even reverse formation of cancerous cells. The aim of this chapter is to provide a concise and comprehensive overview on the therapeutic and pharmaceutical potential of essential oils in the current scenario
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