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Ministerio de Ciencia e Innovación (España), Facultad de Ciencias Exactas y Naturales, UNLPam (Argentina), Secretaría de Ciencia y Tecnología, UNS (Argentina), Waitt Foundation, Santander Universidades, Universidad Complutense de Madrid, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

The normal-state conductivity and superconducting critical temperature of oxygen-deficient YBa2Cu3O7-delta can be persistently enhanced by illumination. Strongly debated for years, the origin of those effects-termed persistent photoconductivity and photosuperconductivity (PPS)-has remained an unsolved critical problem, whose comprehension may provide key insights to harness the origin of hightemperature superconductivity itself. Here, we make essential steps toward understanding PPS. While the models proposed so far assume that it is caused by a carrier-density increase (photodoping) observed concomitantly, our experiments contradict such conventional belief: we demonstrate that it is instead linked to a photo-induced decrease of the electronic scattering rate. Furthermore, we find that the latter effect and photodoping are completely disconnected and originate from different microscopic mechanisms, since they present different wavelength and oxygen-content dependences as well as strikingly different relaxation dynamics. Besides helping disentangle photodoping, persistent photoconductivity, and PPS, our results provide new evidence for the intimate relation between critical temperature and scattering rate, a key ingredient in modern theories on high-temperature superconductivity., European Research Council, European Commission, Agence Natonale de la Recherche (France), Comunidad de Madrid, Agencia Estatal de Investigación (España), Ministerio de Ciencia e Innovación (España), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Abstract: We examined the extent to which apnoea-induced extremes of oxygen demand/carbon dioxide production impact redox regulation of cerebral bioenergetic function. Ten ultra-elite apnoeists (six men and four women) performed two maximal dry apnoeas preceded by normoxic normoventilation, resulting in severe end-apnoea hypoxaemic hypercapnia, and hyperoxic hyperventilation designed to ablate hypoxaemia, resulting in hyperoxaemic hypercapnia. Transcerebral exchange of ascorbate radicals (by electron paramagnetic resonance spectroscopy) and nitric oxide metabolites (by tri-iodide chemiluminescence) were calculated as the product of global cerebral blood flow (by duplex ultrasound) and radial arterial (a) to internal jugular venous (v) concentration gradients. Apnoea duration increased from 306 ± 62 s during hypoxaemic hypercapnia to 959 ± 201 s in hyperoxaemic hypercapnia (P ≤ 0.001). Apnoea generally increased global cerebral blood flow (all P ≤ 0.001) but was insufficient to prevent a reduction in the cerebral metabolic rates of oxygen and glucose (P = 0.015–0.044). This was associated with a general net cerebral output (v > a) of ascorbate radicals that was greater in hypoxaemic hypercapnia (P = 0.046 vs. hyperoxaemic hypercapnia) and coincided with a selective suppression in plasma nitrite uptake (a > v) and global cerebral blood flow (P = 0.034 to <0.001 vs. hyperoxaemic hypercapnia), implying reduced consumption and delivery of nitric oxide consistent with elevated cerebral oxidative–nitrosative stress. In contrast, we failed to observe equidirectional gradients consistent with S-nitrosohaemoglobin consumption and plasma S-nitrosothiol delivery during apnoea (all P ≥ 0.05). Collectively, these findings highlight a key catalytic role for hypoxaemic hypercapnia in cerebral oxidative–nitrosative stress. (Figure presented.). Key points: Local sampling of blood across the cerebral circulation in ultra-elite apnoeists determined the extent to which sever

The electron transport chain (ETC) of mitochondria, bacteria, and archaea couples electron flow to proton pumping and is adapted to diverse oxygen environments. Remarkably, in mice, neurological disease due to ETC complex I dysfunction is rescued by hypoxia through unknown mechanisms. Here, we show that hypoxia rescue and hyperoxia sensitivity of complex I deficiency are evolutionarily conserved to C. elegans and are specific to mutants that compromise the electron-conducting matrix arm. We show that hypoxia rescue does not involve the hypoxia-inducible factor pathway or attenuation of reactive oxygen species. To discover the mechanism, we use C. elegans genetic screens to identify suppressor mutations in the complex I accessory subunit NDUFA6/nuo-3 that phenocopy hypoxia rescue. We show that NDUFA6/nuo-3(G60D) or hypoxia directly restores complex I forward activity, with downstream rescue of ETC flux and, in some cases, complex I levels. Additional screens identify residues within the ubiquinone binding pocket as being required for the rescue by NDUFA6/nuo-3(G60D) or hypoxia. This reveals oxygen-sensitive coupling between an accessory subunit and the quinone binding pocket of complex I that can restore forward activity in the same manner as hypoxia., The electron transport chain (ETC) of mitochondria, bacteria, and archaea couples electron flow to proton pumping and is adapted to diverse oxygen environments. Remarkably, in mice, neurological disease due to ETC complex I dysfunction is rescued by hypoxia through unknown mechanisms. Here, we show that hypoxia rescue and hyperoxia sensitivity of complex I deficiency are evolutionarily conserved to C. elegans and are specific to mutants that compromise the electron-conducting matrix arm. We show that hypoxia rescue does not involve the hypoxia-inducible factor pathway or attenuation of reactive oxygen species. To discover the mechanism, we use C. elegans genetic screens to identify suppressor mutations in the complex I accessory subunit NDUFA6/nuo-3 that phenocopy hypoxia rescue. We show that NDUFA6/nuo-3(G60D) or hypoxia directly restores complex I forward activity, with downstream rescue of ETC flux and, in some cases, complex I levels. Additional screens identify residues within the ubiquinone binding pocket as being required for the rescue by NDUFA6/nuo-3(G60D) or hypoxia. This reveals oxygen-sensitive coupling between an accessory subunit and the quinone binding pocket of complex I that can restore forward activity in the same manner as hypoxia.

Patients with acute brain injury are vulnerable to secondary deterioration, which may go undetected by traditional monitoring. However, multimodal neuromonitoring of brain tissue oxygen tension (PbtO2) and energy metabolism may be able to detect such episodes. We report a retrospective, observational study of 94 patients with aneurysmal subarachnoid haemorrhage (SAH) or traumatic brain injury (TBI) who underwent multimodal neuromonitoring during admission. We examined the co-occurrence of pathological neuromonitoring values: elevated intracranial pressure (ICP, > 20 mmHg), inadequate cerebral perfusion pressure (CPP, < 60 mmHg), brain hypoxia (PbtO2 < 20 mmHg), and metabolic crisis (lactate/pyruvate ratio > 40 and a glucose level < 0.2 mmol/L in cerebral microdialysate). Mixed effects linear regression demonstrated significant associations between abnormal ICP/CPP, cerebral hypoxia and metabolic crisis. However, brain hypoxia occurred in 40% and 31% of observations in patients with SAH and TBI, respectively, despite normal concurrent values of ICP. Similarly, metabolic crisis was observed in 8% and 16% of measurements for SAH and TBI, respectively, despite a normal ICP. The pattern was identical for CPP. In conclusion, although all neuromonitoring variables are interrelated, brain hypoxia and metabolic crisis are common despite an absence of abnormalities in conventional monitoring. Multimodal neuromonitoring may help identify such episodes and guide individualised treatment.

Ponds, wetlands, and shallow lakes (collectively “shallow waterbodies”) are among the most biogeochemically active freshwater ecosystems. Measurements of gross primary production (GPP), respiration (R), and net ecosystem production (NEP) are rare in shallow waterbodies compared to larger and deeper lakes, which can bias our understanding of lentic ecosystem processes. In this study, we calculated GPP, R, and NEP in 26 small, shallow waterbodies across temperate North America and Europe. We observed high rates of GPP (mean 8.4 g O2 m−3 d−1) and R (mean −9.1 g O2 m−3 d−1), while NEP varied from net heterotrophic to autotrophic. Metabolism rates were affected by depth and aquatic vegetation cover, and the shallowest waterbodies had the highest GPP, R, and the most variable NEP. The shallow waterbodies from this study had considerably higher metabolism rates compared to deeper lakes, stressing the importance of these systems as highly productive biogeochemical hotspots., Ponds, wetlands, and shallow lakes (collectively “shallow waterbodies”) are among the most biogeochemically active freshwater ecosystems. Measurements of gross primary production (GPP), respiration (R), and net ecosystem production (NEP) are rare in shallow waterbodies compared to larger and deeper lakes, which can bias our understanding of lentic ecosystem processes. In this study, we calculated GPP, R, and NEP in 26 small, shallow waterbodies across temperate North America and Europe. We observed high rates of GPP (mean 8.4 g O2 m−3 d−1) and R (mean −9.1 g O2 m−3 d−1), while NEP varied from net heterotrophic to autotrophic. Metabolism rates were affected by depth and aquatic vegetation cover, and the shallowest waterbodies had the highest GPP, R, and the most variable NEP. The shallow waterbodies from this study had considerably higher metabolism rates compared to deeper lakes, stressing the importance of these systems as highly productive biogeochemical hotspots.

Yeast is one of the co-products of ethanol plants, which can be used as a nutritional supplement in animal feed due to its high protein content. Given the importance of yeast contribution to the nutritional properties of DDG (dried distillers’ grains), the aim of this study was to assess how different levels of aeration affect the biomass production and the quality of yeast providing new insights into yeast production, offering an alternative source of income for the corn ethanol industry. For this purpose, yeasts were grown in a fed-batch process, and different concentrations of aeration in the medium were tested, namely 0.5, 1.0, and 1.5 volume of air per volume of wort per minute (v v−1 min−1). At the end of the cellular biomass production process, yeasts grown with 0.5 (v v−1 min−1) aeration in the reactor showed higher biomass formation (19.86 g L−1), cellular yield (g g−1), and a lower formation of succinic acid (0.70 g L−1) and acetic acid (0.11 g L−1). Aeration influenced an increase of 1.0% in the protein content in yeast. In conclusion, lower levels of aeration in the yeast production process enables more efficient sugar utilization for biomass formation and is a potential strategy to increase the protein content and the commercial value of DDG.

Metabolic rewiring is a defining characteristic of cancer cells, driving their ability to proliferate. Leveraging these metabolic vulnerabilities for therapeutic purposes has a long and impactful history, with the advent of antimetabolites marking a significant breakthrough in cancer treatment. Despite this, only a few in vitro metabolic discoveries have been successfully translated into effective clinical therapies. This limited translatability is partially due to the use of simplistic in vitro models that do not accurately reflect the tumor microenvironment. This Review examines the effects of current cell culture practices on cancer cell metabolism and highlights recent advancements in establishing more physiologically relevant in vitro culture conditions and technologies, such as organoids. Applying these improvements may bridge the gap between in vitro and in vivo findings, facilitating the development of innovative metabolic therapies for cancer.

Tissue engineering offers a promising alternative for oral and maxillofacial tissue defect rehabilitation; however, cells within a sizeable engineered tissue construct after transplantation inevitably face prolonged and severe hypoxic conditions, which may compromise the survivability of the transplanted cells and arouse the concern of anaerobic infection. Microalgae, which can convert carbon dioxide and water into oxygen and glucose through photosynthesis, have been studied as a source of oxygen supply for several biomedical applications, but their promise in orofacial tissue regeneration remains unexplored. Here, we demonstrated that through photosynthetic oxygenation, Chlamydomonas reinhardtii (C. reinhardtii) supported dental pulp stem cell (DPSC) energy production and survival under hypoxia. We developed a multifunctional photosynthetic hydrogel by embedding DPSCs and C. reinhardtii encapsulated alginate microspheres (CAMs) within gelatin methacryloyl hydrogel (GelMA) (CAMs@GelMA). This CAMs@GelMA hydrogel can generate a sustainable and sufficient oxygen supply, reverse intracellular hypoxic status, and enhance the metabolic activity and viability of DPSCs. Furthermore, the CAMs@GelMA hydrogel exhibited selective antibacterial activity against oral anaerobes and remarkable antibiofilm effects on multispecies biofilms by disrupting the hypoxic microenvironment and increasing reactive oxygen species generation. Our work presents an innovative photosynthetic strategy for oral tissue engineering and opens new avenues for addressing other hypoxia-related challenges. © 2024 The Authors

Herein, we have developed LaMnO3 (LMO) perovskite-based electrocatalysts of oxygen reduction and oxygen evolution reactions (ORR and OER) in a basic aqueous solution. Mechanochemical grinding and thermal annealing leads to highly-pure perovskites as shown by X-ray diffraction. This methodology also allows doping the LMO perovskite with RuO2, thus improving its catalytic activity, especially the oxygen evolution reaction. ORR have been analyzed by rotating ring-disk electrode (RRDE). Eventually, these catalysts are employed in Zn/air batteries resulting in specific capacity values of 12.76 Ahg−1 at 1 Ag−1, when LMO-RuO2 (LMO−Ru) was used as catalyst in the positive electrodes. Besides, high operational stability of Zn/air batteries for over 100 cycles was obtained, saving 1.46 mWh per cycle when LMO−Ru was used with respect to pure LMO.

BACKGROUND: Osteosarcoma (OS) survival rates and outcome have not improved in 50 years since the advent of modern chemotherapeutics. Thus, there is a critical need for an improved understanding of the tumor microenvironment to identify better therapies. Extracellular matrix (ECM) deposition and hypoxia are known to abrogate the efficacy of various chemical and cell-based therapeutics. Here, we aim to mechanistically investigate the combinatorial effects of hypoxia and matrix deposition with the use of OS spheroids. METHODS: We use two murine OS cell lines with differential metastatic potential to form spheroids. We form spheroids of two sizes, use ascorbate-2-phosphate supplementation to enhance ECM deposition, and study cell response under standard (21% O2) and physiologic (5% O2) oxygen tensions. Finally, we examine chemotherapeutic responses to doxorubicin treatment. RESULTS: ECM production and oxygen tension are key determinants of spheroid size through cell organization based on nutrient and oxygen distribution. Interestingly, highly metastatic OS is more susceptible to chemotherapeutics compared to less metastatic OS when matrix production increases. Together, these data suggest that dynamic interactions between ECM production and oxygen diffusion may result in distinct chemotherapeutic responses despite inherent tumor aggressiveness. CONCLUSION: This work establishes OS spheroids as a valuable tool for early OS tumor formation investigation and holds potential for novel therapeutic target and prognostic indicator discovery.

This document presents relevant information regarding the exposure of wine to oxygen in the different processes during winemaking. CHAPTER 1 presents the main moments of winemaking in which oxygen is incorporated into the wine. An experimental work has been developed, presented in CHAPTER 2, where the optimization of a method of reconstitution of grape extracts is carried out to predict the oxygen consumption capacity of a wine made from a grape variety. The influence of certain characteristics on its composition has been studied to evaluate the kinetics of oxygen consumption, to know the differentiating characteristics of a wine that is exposed to saturation conditions and to predict the oxygen consumption capacity and, therefore, the aging capacity of the future wine. This information proves to be a great tool to assist in decision making during the winemaking process and allow the winemaker to manage the winemaking in the best possible way. Next, CHAPTER 3 presents the study of the effect that saturation with different levels of oxygen has on a wine and how this exposure influences its color, antioxidant capacity and phenolic content. Color is one of the main attributes of wine; however, despite the large number of studies that have been conducted to look at the effect of oxygen on wine, information on chromatic changes as oxygen is consumed is scarce. CHAPTER 4 presents a SpectrO2 equipment designed and developed by the UVaMOX group that allows to evaluate the modifications in the color of wine while it is consuming oxygen, a very important possibility, since, although there are many studies focused on the influence of oxygen on the color of wine, all of them present the result. This development turns out to be a very useful tool, not only to know how much oxygen a wine is capable of consuming, but simultaneously also to know how this consumption is altering its characteristics and chromatic properties, an attribute that is related to the quality of the wine and, El presente trabajo presenta información relevante con respecto a la exposición del vino al oxígeno en los diferentes procesos durante la vinificación. El CAPÍTULO 1 presenta los principales momentos de la elaboración del vino en los que el oxígeno se incorpora al vino, así como los principales factores que determinan el consumo de oxígeno y la medida de este proceso. Para comprender el rol del oxígeno en el vino y los cambios que se provocan, se ha realizado una exhaustiva búsqueda de información de los estudios realizados por diversos investigadores y que tienen relación con el consumo de oxígeno en el vino. Se ha desarrollado un trabajo experimental, recogido en el CAPÍTULO 2, donde se realiza la optimización de un método de reconstitución de extractos de uva para predecir la capacidad de consumo de oxígeno de un vino elaborado desde un tipo uva. Se ha estudiado la influencia de determinadas características en su composición, con el fin de evaluar la cinética de consumo, conocer las características diferenciadoras de un vino que es expuesto a condiciones de saturación y predecir la capacidad de consumo de oxígeno y, por lo tanto, la capacidad de envejecimiento del futuro vino. Esta información resulta ser una gran herramienta para ayudar en la toma de decisiones durante el proceso de vinificación y permitir al enólogo gestionar la vinificación de la mejor forma posible. A continuación, en el CAPÍTULO 3 se presenta el estudio del efecto que tiene en un vino la saturación con diferentes niveles de oxígeno y cómo influye dicha exposición en su color, su capacidad antioxidante y su contenido fenólico. El color es uno de los principales atributos del vino, sin embargo, a pesar de la gran cantidad de estudios que se han realizado para ver el efecto del oxígeno en el vino, la información sobre los cambios cromáticos a medida que se consume el oxígeno es escasa. El CAPÍTULO 4 presenta un equipo SpectrO2 diseñado y desarrollado por el grupo UVaMOX que permite evaluar las, Escuela de Doctorado, Doctorado en Enología, Viticultura y Sostenibilidad

Climate changes significantly impact greenhouse gas emissions from wetland soil. Specifically, wetland soil may be exposed to oxygen (O2) during droughts, or to sulfate (SO42-) as a result of sea level rise. How these stressors - separately and together - impact microbial food webs driving carbon cycling in the wetlands is still not understood. To investigate this, we integrated geochemical analysis, proteogenomics, and stoichiometric modeling to characterize the impact of elevated SO42- and O2 levels on microbial methane (CH4) and carbon dioxide (CO2) emissions. The results uncovered the adaptive responses of this community to changes in SO42- and O2 availability and identified altered microbial guilds and metabolic processes driving CH4 and CO2 emissions. Elevated SO42- reduced CH4 emissions, with hydrogenotrophic methanogenesis more suppressed than acetoclastic. Elevated O2 shifted the greenhouse gas emissions from CH4 to CO2. The metabolic effects of combined SO42- and O2 exposures on CH4 and CO2 emissions were similar to those of O2 exposure alone. The reduction in CH4 emission by increased SO42- and O2 was much greater than the concomitant increase in CO2 emission. Thus, greater SO42- and O2 exposure in wetlands is expected to reduce the aggregate warming effect of CH4 and CO2. Metaproteomics and stoichiometric modeling revealed a unique subnetwork involving carbon metabolism that converts lactate and SO42- to produce acetate, H2S, and CO2 when SO42- is elevated under oxic conditions. This study provides greater quantitative resolution of key metabolic processes necessary for the prediction of CH4 and CO2 emissions from wetlands under future climate scenarios.

With ascent to high altitude (HA), compensatory increases in cerebral blood flow and oxygen delivery must occur to preserve cerebral metabolism and consciousness. We hypothesized that this compensation in cerebral blood flow and oxygen delivery preserves tolerance to simulated hemorrhage (via lower body negative pressure, LBNP), such that tolerance is similar during sustained exposure to HA vs. low altitude (LA). Healthy humans (4F/4 M) participated in LBNP protocols to presyncope at LA (1130 m) and 5-7 days following ascent to HA (3800 m). Internal carotid artery (ICA) blood flow, cerebral delivery of oxygen (CDO2) through the ICA, and cerebral tissue oxygen saturation (ScO2) were determined. LBNP tolerance was similar between conditions (LA: 1276 ± 304 s vs. HA: 1208 ± 306 s; P = 0.58). Overall, ICA blood flow and CDO2 were elevated at HA vs. LA (P ≤ 0.01) and decreased with LBNP under both conditions (P < 0.0001), but there was no effect of altitude on ScO2 responses (P = 0.59). Thus, sustained exposure to hypobaric hypoxia did not negatively impact tolerance to simulated hemorrhage. These data demonstrate the robustness of compensatory physiological mechanisms that preserve human cerebral blood flow and oxygen delivery during sustained hypoxia, ensuring cerebral tissue metabolism and neuronal function is maintained.

En aquest treball de final de grau s'ha dut a terme una anàlisi detallada de la relació entre la puresa del nitrogen utilitzat com a atmosfera en el procés de sinterització i les propietats físiques, mecàniques i químiques resultants de les peces elaborades. L'estudi inclou la realització de diversos assaigs de sinterització sota una atmosfera controlada, composta en un 95% del volum de nitrogen i un 5% d'hidrogen. Per avaluar l'impacte de la puresa del nitrogen, s'han portat a terme dos tipus de sinterització. La primera es va realitzar mitjançant nitrogen de puresa 99,995%, mentre que la segona sinterització va fer servir nitrogen amb una puresa del 99,9%. En tots dos casos, les provetes estaven compostes per materials a base de ferro, coure i carboni. Els resultats van mostrar que una menor puresa de nitrogen provoca la formació d'òxids a les peces sinteritzades, afectant lleument les seves propietats. Per tant, es conclou que l'ús de nitrogen amb una puresa de 99,9% no és viable per a aquest procés. No obstant això, aquest estudi destaca la importància de progressar amb la investigació per tal de minimitzar els efectes causats per un contingut d'impureses més gran en la sinterització., En este trabajo de fin de grado se ha llevado a cabo un análisis detallado de la relación entre la pureza del nitrógeno utilizado como atmósfera en el proceso de sinterización y las propiedades físicas, mecánicas y químicas resultantes de las piezas elaboradas. El estudio incluye la realización de diversos ensayos de sinterización bajo una atmósfera controlada, compuesta en un 95% de su volumen de nitrógeno y un 5% de hidrógeno. Para evaluar el impacto de la pureza del nitrógeno, se han llevado a cabo dos tipos de sinterización. La primera se realizó mediante nitrógeno de pureza 99.995%, mientras que la segunda sinterización empleó nitrógeno con una pureza del 99.9%. En ambos casos, las probetas estaban compuestas por materiales a base de hierro, cobre y carbono. Los resultados mostraron que una menor pureza de nitrógeno provoca la formación de óxidos en las piezas sinterizadas, afectando levemente a sus propiedades. Por lo tanto, se concluye que el uso de nitrógeno con una pureza de 99.9% no es viable para este proceso. No obstante, este estudio destaca la importancia de progresar con la investigación con tal de minimizar los efectos causados por un mayor contenido de impurezas en la sinterización., In this final degree project, a detailed analysis of the relationship between the purity of the nitrogen used as an atmosphere in the sintering process and the resulting physical, mechanical and chemical properties of the manufactured parts has been carried out. The study includes conducting various sintering tests under a controlled atmosphere, composed of 95% of its volume of nitrogen and 5% of hydrogen. To evaluate the impact of nitrogen purity, two types of sintering have been carried out. The first was conducted using nitrogen of 99.995% purity, while the second sintering used nitrogen with a purity of 99.9%. In both cases, the specimens were composed of materials based on iron, copper and carbon. The results showed that a lower purity of nitrogen causes the formation of oxides in the sintered parts, slightly affecting their properties. Therefore, it is concluded that the use of nitrogen with a purity of 99.9% is not viable for this process. However, this study highlights the importance of progressing research in order to minimize the effects caused by a higher content of impurities in sintering.

The steady increase in atmospheric CO2 since the industrial revolution is well established as the major driver of global climate change but its direct impacts on biochemical processes like photosynthesis are also of major concern. Some crop plant species have been shown to be less effective at assimilating nitrate, the most abundant form of nitrogen available to plants in most agricultural soils, when grown under elevated CO2. This indicates that rising CO2 concentrations could negatively impact the nitrogen use efficiency of many important crop species and may explain why protein content in some plant species decreases with CO2 enrichment. Improved techniques to measure nitrogen metabolism in plants are needed to further study the underlying cause of this phenomenon and mitigate the impact of rising atmospheric CO2 on our food supply. The three projects described here are a part of this effort. Chapter 1 describes a rosette area measurement tool that was developed as part of a larger study investigating the genetic basis of plant response to different nitrogen forms and concentrations. This tool was able to accurately estimate rosette area from photographs of Arabidopsis seedlings grown on agar plates even when the photographs did not provide a scale. We present a general-purpose ultra-high-resolution data acquisition system in chapter 2. The system interfaces a 32-bit analog to digital converter with a Raspberry Pi single board computer. We provide a simple open-source hardware design and easy to use software libraries enabling this system to be easily built and adapted for any purpose. Finally, we demonstrate the high performance of the system by making precise temperature measurements. Many elements of this data acquisition system were used in the Oxygen analyzer described in chapter 3. Chapter 3 documents the design and characterization of a novel high-resolution oxygen analyzer designed to measure small O2 fluxes against the large ambient background. The origi

Corneal crosslinking (CXL) is an established treatment for progressive keratoconus (KC). In this thesis, Advanced CXL refers to a further development of conventional CXL, which aims to improve the treatment outcomes in KC and can also be used as a refractive treatment for low-grade myopia (near-sightedness). Transepithelial (epi-on) CXL with high oxygen has emerged as an approach to reduce the post-treatment inconveniences. The aim of the three prospective, randomized, intra-individually compared, single-masked studies in this thesis was to continue developing advanced CXL for KC and low-grade myopia. Studies I and II sought to assess the treatment effects and subjective ocular discomforts in epi-on photorefractive intrastromal crosslinking (PiXL) in high oxygen as a refractive treatment for low-grade myopia using three different illumination protocols. In Study I, 23 healthy subjects (46 eyes) were randomized to a central 4.0 mm homogeneous illumination zone (area) in one eye and a 4.0 mm annular zone with a central 2.0 mm sparing (ring) in the fellow eye. Both protocols improved uncorrected distance visual acuity (UDVA) and manifest refractive spherical equivalent (MRSE) at 1 month, which remained stable throughout 24 months. The ring protocol was reported to cause less ocular discomfort at 1 week. In Study II, 27 healthy subjects (54 eyes) were randomized to the previous ring protocol in one eye and a 3.5 mm annular protocol with a central 1.5 mm sparing (small ring) in the fellow eye. The small ring rendered less ocular discomfort the first day post-treatment and slightly better improvements in UDVA and MRSE, but there was a transient reduction in low-contrast visual acuity (LCVA). In both Studies I and II, no changes in endothelial cell count (ECC) and best corrected visual acuity (BCVA) were seen and no adverse events were registered. Study III aimed to compare the treatment effect and subjective ocular discomfort scores of customized topography-guided epi-on

The study addresses the measurement of Chemical Oxygen Demand (COD) to evaluate the quality of water in the residual discharges of the city of San Francisco de Milagro. The main objective is to determine the concentration of organic and inorganic matter in the water, comparing the results with the Ecuadorian regulations established in the Unified Text of Secondary Legislation of the Ministry of the Environment (TULSMA). The problem identified is that the discharge of organic matter in high concentrations reduces dissolved oxygen, negatively affecting aquatic life and, consequently, biodiversity. This parameter is crucial to monitor and protect water bodies receiving contaminants. The analysis of the case is based on COD as an indicator of water quality, measuring the amount of oxygen necessary to completely oxidize the organic matter present. Traditional methods, such as the use of dichromate and potassium permanganate, although effective, present operational challenges and risks of secondary contamination Finally, the study concludes that improving water quality is essential for the protection of the aquatic environment and public health, recommending continuous monitoring and adequate management of water resources, and raising awareness among private companies., El estudio aborda la medición de la Demanda Química de Oxígeno (DQO) para evaluar la calidad del agua en las descargas residuales de la ciudad San Francisco de Milagro. El principal objetivo es determinar la concentración de materia orgánica e inorgánica en el agua, comparando los resultados con la normativa ecuatoriana establecida en el Texto Unificado de Legislación Secundaria del Ministerio de Ambiente (TULSMA) El problema identificado es que el vertido de materia orgánica en altas concentraciones reduce el oxígeno disuelto, afectando negativamente a la vida acuática y, en consecuencia, a la biodiversidad. Este parámetro es crucial para monitorear y proteger los cuerpos de agua receptores de contaminantes. El análisis del caso se basa en la DQO como indicador de la calidad del agua, midiendo la cantidad de oxígeno necesario para oxidar completamente la materia orgánica presente. Los métodos tradicionales, como el uso de dicromato y permanganato de potasio, aunque efectivos, presentan desafíos operativos y riesgos de contaminación secundaria​. Finalmente, el estudio concluye que mejorar la calidad del agua es esencial para la protección del medio acuático y la salud pública, recomendando un monitoreo continuo y una gestión adecuada de los recursos hídricos, y hacer conciencia a la empresa privada

Catalyst passivation through carbon poisoning is a common and costly problem as it reduces the lifetime and performance of the catalyst. Adding oxygen to the feed stream could reduce poisoning but may also affect the activity negatively. We have studied the dehydrogenation, decomposition, and desorption of naphthalene co-adsorbed with oxygen on Ni(111) by combining temperature-programmed desorption (TPD), sum frequency generation spectroscopy (SFG), photoelectron spectroscopy (PES), and density functional theory (DFT). Chemisorbed oxygen reduces the sticking of naphthalene and shifts H2 production and desorption to higher temperatures by blocking active Ni sites. Oxygen increases the production of CO and reduces carbon residues on the surface. Chemisorbed oxygen is readily removed when naphthalene is decomposed. Oxide passivates the surface and reduces the sticking coefficient. But it also increases the production of CO dramatically and reduces the carbon residues. Ni2O3 is more active than NiO., QC 20240322

Liquefaction of lignocellulosic biomass through fast pyrolysis, to yield fast pyrolysis bio-oil (FPBO), is a technique that has been extensively researched in the quest for finding alternatives to fossil feedstocks to produce fuels, chemicals, etc. Properties such as high oxygen content, acidity, and poor storage stability greatly limit the direct use of this bio-oil. Furthermore, high coking tendencies make upgrading of the FPBO by hydrodeoxygenation in fixed-bed bed hydrotreaters challenging due to plugging and catalyst deactivation. This study investigates a novel two-step hydroprocessing concept; a continuous slurry-based process using a dispersed NiMo-catalyst, followed by a fixed bed process using a supported NiMo-catalyst. The oil product from the slurry-process, having a reduced oxygen content (15 wt%) compared to the FPBO and a comparatively low coking tendency (TGA residue of 1.4 wt%), was successfully processed in the downstream fixed bed process for 58 h without any noticeable decrease in catalyst activity, or increase in pressure drop. The overall process resulted in a 29 wt% yield of deoxygenated oil product (0.5 wt% oxygen) from FPBO with an overall carbon recovery of 68%., Correspondence Address: N. Bergvall; Research Institutes of Sweden AB, Borås, Box 857, SE-501 15, Sweden; This work was funded by the Swedish Energy Agency, project number 41253-2

Purpose: To analyse the temperature of the corneal surface in keratoconus during corneal customized crosslinking (CXL) with a preserved epithelium (epi-on) under oxygen flow, and epi-off CXL in room air, and to assess the effect of pre-heating the oxygen. Methods: This masked, intra-individual comparing randomized study included 14 participants with bilateral progressive keratoconus treated with bilateral CXL: one eye with epi-on CXL under a flow of 2.5 L/min oxygen; the fellow eye with epi-off CXL in room air. In a second setting involving 12 healthy participants, room-tempered oxygen was flushed over one eye and oxygen pre-heated to 37°C over the fellow eye. The corneal surface temperature was assessed with infrared photography. Results: A reduction in corneal surface temperature was seen from the pre-treatment application of topical riboflavin in the epi-off group (−1.1 ± 1.0°C, p < 0.001). The temperature increased during the first half of the CXL treatment in both groups (+0.7 ± 1.2°C, p = 0.041 for epi-on; +0.7 ± 0.9°C, p = 0.023 for epi-off CXL, respectively). In epi-on CXL an overall temperature increase was seen during the treatment (+0.8 ± 1.2°C, p = 0.016). In the second setting, pre-heating the oxygen rendered a surface temperature increase of +1.8 ± 0.2°C (p < 0.001). Conclusion: In epi-off CXL, the application of topical room-tempered riboflavin decreases the corneal surface temperature, likely due to increased evaporation. A slight temperature increase is seen during CXL with both epi-on and epi-off CXL, albeit far below the corneal safety limit. The corneal temperature can, however, be increased by applying pre-heated oxygen, a possible approach to modify or augment the treatment effect in CXL.

Candida albicans has the capacity to neutralize acidic growth environments by releasing ammonia derived from the catabolism of amino acids. The molecular components underlying alkalization and its physiological significance remain poorly understood. Here, we present an integrative model with the cytosolic NAD+-dependent glutamate dehydrogenase (Gdh2) as the principal ammonia-generating component. We show that alkalization is dependent on the SPS-sensor-regulated transcription factor STP2 and the proline-responsive activator Put3. These factors function in parallel to derepress GDH2 and the two proline catabolic enzymes PUT1 and PUT2. Consistently, a double mutant lacking STP2 and PUT3 exhibits a severe alkalization defect that nearly phenocopies that of a gdh2-/- strain. Alkalization is dependent on mitochondrial activity and in wild-type cells occurs as long as the conditions permit respiratory growth. Strikingly, Gdh2 levels decrease and cells transiently extrude glutamate as the environment becomes more alkaline. Together, these processes constitute a rudimentary regulatory system that counters and limits the negative effects associated with ammonia generation. These findings align with Gdh2 being dispensable for virulence, and based on a whole human blood virulence assay, the same is true for C. glabrata and C. auris. Using a transwell co-culture system, we observed that the growth and proliferation of Lactobacillus crispatus, a common component of the acidic vaginal microenvironment and a potent antagonist of C. albicans, is unaffected by fungal-induced alkalization. Consequently, although Candida spp. can alkalinize their growth environments, other fungal-associated processes are more critical in promoting dysbiosis and virulent fungal growth.

In the current pursuit of sustainable energy, biofuel cells are attracting considerable attention. Within biomedical engineering, the concept of harnessing energy from biological fluids, such as blood, holds significant promise, enabling both full autonomy and miniaturization. In this context, this study aims to identify the most efficient biofuel cells for miniaturised implantable biosensors and design a prototype based on the obtained results. To achieve this goal, a systematic literature review was conducted, comparing biofuel cells based on relevant parameters for powering devices, including power density and operative voltages. This categorization guided material selection, considering a cost-performance trade-off. Carbon nanotubes and Laccase were chosen to facilitate oxygen reduction at the cathode, while carbon nanotubes with Glucose Oxidase (with and without ferrocenemethanol) played a similar role at the anode—where glucose proved to be the most advantageous fuel. Electrode functionalization and assessment involved electrochemical and morphological analyses, culminating in the recording of initial results for the biofuel cell prototype. The analysis of scientific literature revealed that under physiological conditions, including pH, glucose concentration, and single-chamber biofuel cells, the maximum power density obtained was 1 mW/cm$^2$ at 0.65 V. The use of nanomaterials, such as carbon nanotubes, and enzymes proved crucial for achieving this performance by enhancing electron transfer, increasing the effective area, and introducing specificity to each electrode, enabling the biofuel cell to operate without the need for a membrane. During the design phase, the functionalisation of the cathode highlighted the critical role of oxygen, which has a limited concentration in the solution. At the anode, the attempt to achieve mediated electron transfer proved successful, in contrast to the method of direct electron transfer. Finally, the characterisation of the

In coastal waters, methane-oxidizing bacteria (MOB) can form a methane biofilter and mitigate methane emissions. The metabolism of these MOBs is versatile, and the resilience to changing oxygen concentrations is potentially high. It is still unclear how seasonal changes in oxygen availability and water column chemistry affect the functioning of the methane biofilter and MOB community composition. Here, we determined water column methane and oxygen depth profiles, the methanotrophic community structure, methane oxidation potential, and water–air methane fluxes of a eutrophic marine basin during summer stratification and in the mixed water in spring and autumn. In spring, the MOB diversity and relative abundance were low. Yet, MOB formed a methane biofilter with up to 9% relative abundance and vertical niche partitioning during summer stratification. The vertical distribution and potential methane oxidation of MOB did not follow the upward shift of the oxycline during summer, and water–air fluxes remained below 0.6 mmol m−2 d−1. Together, this suggests active methane removal by MOB in the anoxic water. Surprisingly, with a weaker stratification, and therefore potentially increased oxygen supply, methane oxidation rates decreased, and water–air methane fluxes increased. Thus, despite the potential resilience of the MOB community, seasonal water column dynamics significantly influence methane removal.

We investigated trends in temperature, stratification, and hypolimnetic oxygen concentration of German lakes under climate change using observational data and hydrodynamic modelling. Observations from 46 lakes revealed that annually averaged surface temperatures increased by + 0.5 °C between 1990 and 2020 while bottom temperatures remained almost constant. Modelling of 12 lakes predicted further increases in surface temperatures by 0.3 °C/decade until the year 2099 in the most pessimistic emission scenario RCP 8.5 (RCP 4.5: + 0.18 °C/decade; RCP 2.6: + 0.04 °C/decade). Again, bottom temperatures increased much less while summer stratification extended by up to 38 days. Using a simplified oxygen model, we showed that hypolimnetic oxygen concentrations decreased by 0.7–1.9 mg L−1 in response to the extended stratification period. However, model runs assuming lower productivity (e. g. through nutrient reduction) resulted in increased oxygen concentrations even in the most pessimistic emission scenario. Our results suggest that the negative effects of climate change on the oxygen budget of lakes can be efficiently mitigated by nutrient control.

BACKGROUND: Standard high-flow nasal cannula (HFNC) is a respiratory support device widely used to manage post-extubation hypoxemic acute respiratory failure (hARF) due to greater comfort, oxygenation, alveolar recruitment, humidification, and reduction of dead space, as compared to conventional oxygen therapy. On the contrary, the effects of the new asymmetrical HFNC interface (Optiflow® Duet system (Fisher & Paykel, Healthcare, Auckland, New Zealand) is still under discussion. Our aim is investigating whether the use of asymmetrical HFNC interface presents any relevant difference, compared with the standard configuration, on lung aeration (as assessed by end-expiratory lung impedance (EELI) measured by electrical impedance tomography (EIT)), diaphragm ultrasound thickening fraction (TFdi) and excursion (DE), ventilatory efficiency (estimated by corrected minute ventilation (MV)), gas exchange, dyspnea, and comfort. METHODS: Pilot physiological crossover randomized controlled study enrolling 20 adults admitted to the Intensive Care unit, invasively ventilated for at least 24 h, and developing post-extubation hARF, i.e., PaO2/set FiO2 < 300 mmHg during Venturi mask (VM) within 120 min after extubation. Each HFNC configuration was applied in a randomized 60 min sequence at a flow rate of 60 L/min. RESULTS: Global EELI, TFdi, DE, ventilatory efficiency, gas exchange and dyspnea were not significantly different, while comfort was greater during asymmetrical HFNC support, as compared to standard interface (10 [7-10] and 8 [7-9], p-value 0.044). CONCLUSIONS: In post-extubation hARF, the use of the asymmetrical HFNC, as compared to standard HFNC interface, slightly improved patient comfort without affecting lung aeration, diaphragm activity, ventilatory efficiency, dyspnea and gas exchange. CLINICAL TRIAL NUMBER: ClinicalTrial.gov. REGISTRATION NUMBER: NCT05838326 (01/05/2023). NEW & NOTEWORTHY: The asymmetrical high-flow nasal cannula oxyge

The oxygenation of Earths atmosphere represents the quintessential transformation of a planetary surface by microbial processes. In turn, atmospheric oxygenation transformed metabolic evolution; molecular clock models indicate the diversification and ecological expansion of respiratory metabolisms in the several hundred million years following atmospheric oxygenation. Across this same interval, the geological record preserves 13C enrichment in some carbonate rocks, called the Lomagundi-Jatuli excursion (LJE). By combining data from geologic and genomic records, a self-consistent metabolic evolution model emerges for the LJE. First, fermentation and methanogenesis were major processes remineralizing organic carbon before atmospheric oxygenation. Once an ozone layer formed, shallow water and exposed environments were shielded from UVB/C radiation, allowing the expansion of cyanobacterial primary productivity. High primary productivity and methanogenesis led to preferential removal of 12C into organic carbon and CH4. Extreme and variable 13C enrichments in carbonates were caused by 13C-depleted CH4 loss to the atmosphere. Through time, aerobic respiration diversified and became ecologically widespread, as did other new metabolisms. Respiration displaced fermentation and methanogenesis as the dominant organic matter remineralization processes. As CH4 loss slowed, dissolved inorganic carbon in shallow environments was no longer highly 13C enriched. Thus, the loss of extreme 13C enrichments in carbonates marks the establishment of a new microbial mat ecosystem structure, one dominated by respiratory processes distributed along steep redox gradients. These gradients allowed the exchange of metabolic by-products among metabolically diverse organisms, providing novel metabolic opportunities. Thus, the microbially induced oxygenation of Earths atmosphere led to the transformation of microbial ecosystems, an archetypal example of planetary microbiology.IMPORTANCEThe oxygenatio

There is a strong relationship between metazoan body size and extinction risk. However, the size selectivity and underlying mechanisms in foraminifera, a common marine protozoa, remain controversial. Here, we found that foraminifera exhibit size-dependent extinction selectivity, favoring larger groups (>7.4 log10 cubic micrometer) over smaller ones. Foraminifera showed significant size selectivity in the Guadalupian-Lopingian, Permian-Triassic, and Cretaceous-Paleogene extinctions where the proportion of large genera exceeded 50%. Conversely, in extinctions where the proportion of large genera was <45%, foraminifera displayed no selectivity. As most of these extinctions coincided with oceanic anoxic events, we conducted simulations to assess the effects of ocean deoxygenation on foraminifera. Our results indicate that under suboxic conditions, oxygen fails to diffuse into the cell center of large foraminifera. Consequently, we propose a hypothesis to explain size distribution-related selectivity and Lilliput effect in animals relying on diffusion for oxygen during past and future ocean deoxygenation, i.e., oxygen diffusion distance in body.

Digestate is the secondary product of the fermentation process in biogas plants. The use of digestate as a fertilizer is very common. However, this is more and more limited nowadays and therefore alternative uses for digestate are sought. The research described in this article maps the possibilities of using digestate from the wet fermentation process for the syngas generation. This work is focuses on the gasification of the digestate with spruce chips mixtures. The mixtures were prepared with a proportion of 0, 25, 50, 75 and 100% of the digestate. The experiments were carried out on a semi-operational fluidized bed gasifier at atmospheric pressure. The working temperature of the fluidized bed was 810 °C; the gasification was autothermal. The gasification was carried out with three types of gasification agents, i.e. air, air-steam, and oxygen-steam for each fuel mixture. The aim of the research was to assess the effect of the digestate with wood chips on the qualitative and quantitative properties of the syngas. The digestate can be characterized as a secondary energy source reducing the consumption of primary energy sources. The produced syngas is of high quality and the digestate can become a very desirable fuel for the syngas production., Digestát je sekundárním produktem fermentačního procesu v bioplynových stanicích. Použití digestátu jako hnojiva je velmi časté. To je však v dnešní době stále více omezeno a proto se hledají alternativní využití digestátu. Výzkum popsaný v tomto článku mapuje možnosti využití digestátu z procesu mokré fermentace pro výrobu syntetického plynu. Tato práce je zaměřena na zplyňování digestátu a smrkové štěpky. Směsi byly připraveny s podílem 0, 25, 50, 75 a 100 % digestátu. Experimenty byly prováděny na poloprovozním zplyňovači s fluidním ložem při atmosférickém tlaku. Pracovní teplota fluidního lože byla 810 °C; zplyňování bylo autotermní. Zplyňování bylo prováděno třemi typy zplyňovacích médií, tj. vzduchem, vzduchem a vodní parou a kyslíkem a párou pro každou palivovou směs. Cílem výzkumu bylo posoudit vliv digestátu s dřevní štěpkou na kvalitativní a kvantitativní vlastnosti syngasu. Digesát lze charakterizovat jako sekundární zdroj energie snižující spotřebu primárních energetických zdrojů. Produkovaný syngas má vysokou kvalitu a digestát se může stát velmi žádaným palivem pro výrobu syngasu.

Precision spectroscopy has been the driving force for progress of our physical understanding and still is a promising tool for the investigation of new physics. Molecules offer transitions which allow tests that are not possible in atomic systems. However, usually precision spectroscopy of molecules is challenging due to the lack of cycling transitions for state preparation and state detection. For molecular ions, this obstacle can be overcome by quantum logic spectroscopy, where dissipation for state preparation and detection is provided by a co-trapped atomic ion exploiting the shared eigenstates of motion. Here, we propose a full quantum logic spectroscopy scheme for molecular oxygen ions and theoretically investigate the feasibility of quantum logic-assisted state detection and preparation. Furthermore, we provide coupling rates for a direct single-photon quadrupole excitation of a vibrational overtone transition that can serve as a sensitive reference for tests of a possible variation of the proton-to-electron mass ratio.

The efficiency of the gasification process and product quality largely depend on the degree of fuel conversion. We present the real-time in-situ tunable diode laser measurements of main carbon and oxygen-containing species in the hot reactor core of a pilot-scale entrained flow biomass gasifier (EFG). The concentrations of CO, CO2, CH4, C2H2, H2O, soot, and gas temperature were measured during the air and oxygen-enriched gasification of stem wood at varying equivalence ratios. The experiments were made at the upper and lower optical ports inside a 4 m long, ceramic-lined, atmospheric EFG, allowing to access the degree of the fuel conversion inside the reactor. The exhaust composition was measured by micro-GC, FTIR, and low-pressure impactor. There was a good agreement between the data measured inside the reactor and at the exhaust for oxygen-enriched gasification implying that the chemical reactions are practically frozen downstream the optical ports. For air, the data indicated that the gasification reactions are still active at the measurement locations. Significant concentrations of C2H2, up to 5000 ppm, were found inside the reactor., We gratefully acknowledge financial support from the Swedish Energy Agency through 50470-1 project.

Les dommages à l’ADN induits par l’oxydation radicalaire peuvent avoir des effets gravement délétères comme la mutagenèse et la mort cellulaire. Leur formation dérive entre autres des réactions des espèces réactives de l’oxygène, notamment les radicaux hydroxyles (HO•), qui sont produits de façon endogène au cours du métabolisme normal ou, de façon exogène, par l’exposition à la radiation ionisante par exemple. La génération de radicaux dans l’ADN mène ultimement à la modification des bases azotées et du 2-désoxyribose via l’implication intermédiaire de radicaux alkylperoxyles (ROO•) qui résultent de l’addition rapide entre l’oxygène (O2) et les radicaux alkyles (R•) initiaux. S’ils ne sont pas piégés par des composés antioxydants, les ROO• de l’ADN peuvent intervenir dans des réactions complexes avec des nucléotides vicinaux menant à l’amplification des dommages et la formation concomitante de lésions en tandem. Puisque le groupement méthyle de la thymine ainsi que la position C5’ du 2-désoxyribose sont des sites d’attaque majeurs du HO• en raison de leur plus grande exposition au solvant, les ROO• centrés sur ces carbones jouent un rôle prédominant dans l’oxydation de l’ADN. Les travaux présentés dans cette thèse ont visé à évaluer en détail la réactivité de ces ROO• dans l’ADN au niveau des réactions intra et intermoléculaires. Ceux-ci ont rendu possible la découverte de plusieurs lésions en tandem ainsi qu’un nouveau type de cassure constituée d’une terminaison 5’-carboxylate. De plus, ces études ont permis d’élucider une nouvelle voie réactionnelle de piégeage des ROO• par l’ascorbate qui mène à la formation d’alcools comme produits finaux plutôt que les hydroperoxydes anticipés. Les résultats de cette thèse soulignent l’importance des études fondamentales cherchant à comprendre les mécanismes moléculaires par lesquels les systèmes biologiques se détériorent., DNA lesions induced by radical oxidation can have profoundly deleterious effects such as mutagenesis and cell death. Their formation derives notably from the reactions of reactive oxygen species, such as hydroxyl radicals (HO•), which are produced endogenously during normal metabolism, or exogenously from exposure to ionizing radiation for instance. Generation of radicals within DNA ultimately leads to nucleobase and 2-deoxyribose modifications via the intermediacy of oxidizing alkylperoxyl radicals (ROO•) that arise from rapid addition of oxygen (O2) to initial alkyl radicals (R•). If not trapped by antioxidant compounds, DNA peroxyl radicals can undergo complex reactions with vicinal nucleotides that lead to damage amplification and the concomitant formation of so-called tandem lesions. Because both the methyl group of thymine and the C5’ position of the 2-deoxyribose moiety are major sites of attack by HO• due to their greater solvent exposure, ROO• centered on these carbons play a significant role in the oxidation of DNA. This thesis work aimed at evaluating in detail the reactivity of these ROO• species in DNA in terms of intra- and intermolecular reactions and allowed the discovery of multiple tandem lesions as well as a new type of strand breaks composed of 5’-carboxylate termini. Moreover, these studies made possible the elucidation of a novel pathway of ROO• trapping by ascorbate that leads to the formation of alcohols as final reaction products rather than the expected hydroperoxides. The results of this thesis highlight the importance of fundamental studies that strive to understand the molecular underpinnings by which biological systems deteriorate.