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Articles de revues sur le sujet "Coppie redox"
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Allen, John F. « Why chloroplasts and mitochondria retain their own genomes and genetic systems : Colocation for redox regulation of gene expression ». Proceedings of the National Academy of Sciences 112, no 33 (18 mai 2015) : 10231–38. http://dx.doi.org/10.1073/pnas.1500012112.
Texte intégralRésumé :
Chloroplasts and mitochondria are subcellular bioenergetic organelles with their own genomes and genetic systems. DNA replication and transmission to daughter organelles produces cytoplasmic inheritance of characters associated with primary events in photosynthesis and respiration. The prokaryotic ancestors of chloroplasts and mitochondria were endosymbionts whose genes became copied to the genomes of their cellular hosts. These copies gave rise to nuclear chromosomal genes that encode cytosolic proteins and precursor proteins that are synthesized in the cytosol for import into the organelle into which the endosymbiont evolved. What accounts for the retention of genes for the complete synthesis within chloroplasts and mitochondria of a tiny minority of their protein subunits? One hypothesis is that expression of genes for protein subunits of energy-transducing enzymes must respond to physical environmental change by means of a direct and unconditional regulatory control—control exerted by change in the redox state of the corresponding gene product. This hypothesis proposes that, to preserve function, an entire redox regulatory system has to be retained within its original membrane-bound compartment. Colocation of gene and gene product for redox regulation of gene expression (CoRR) is a hypothesis in agreement with the results of a variety of experiments designed to test it and which seem to have no other satisfactory explanation. Here, I review evidence relating to CoRR and discuss its development, conclusions, and implications. This overview also identifies predictions concerning the results of experiments that may yet prove the hypothesis to be incorrect.
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McTernan, Patrick M., Paige S. Katz, Constance Porretta, David A. Welsh et Robert W. Siggins. « A Novel FACS-Based Workflow for Simultaneous Assessment of RedOx Status, Cellular Phenotype, and Mitochondrial Genome Stability ». BioChem 1, no 1 (2 avril 2021) : 1–18. http://dx.doi.org/10.3390/biochem1010001.
Texte intégralRésumé :
Intracellular reduction-oxidation (RedOx) status mediates a myriad of critical biological processes. Importantly, RedOx status regulates the differentiation of hematopoietic stem and progenitor cells (HSPCs), mesenchymal stromal cells (MSCs) and maturation of CD8+ T Lymphocytes. In most cells, mitochondria are the greatest contributors of intracellular reactive oxygen species (ROS). Excess ROS leads to mitochondrial DNA (mtDNA) damage and protein depletion. We have developed a fluorescence-activated cell sorting (FACS)-based protocol to simultaneously analyze RedOx status and mtDNA integrity. This simultaneous analysis includes measurements of ROS (reduced glutathione (GSH)), ATP5H (nuclear encoded protein), MTCO1 (mitochondrial DNA encoded protein), and cell surface markers to allow discrimination of different cell populations. Using the ratio of MTCO1 to ATP5H median fluorescence intensity (MFI), we can gain an understanding of mtDNA genomic stability, since MTCO1 levels are decreased when mtDNA becomes significantly damaged. Furthermore, this workflow can be optimized for sorting cells, using any of the above parameters, allowing for downstream quantification of mtDNA genome copies/nucleus by quantitative PCR (qPCR). This unique methodology can be used to enhance analyses of the impacts of pharmacological interventions, as well as physiological and pathophysiological processes on RedOx status along with mitochondrial dynamics in most cell types.
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Spezia, Pietro Giorgio, Andreina Baj, Francesca Drago Ferrante, Sara Boutahar, Lorenzo Azzi, Angelo Genoni, Daniela Dalla Gasperina et al. « Detection of Torquetenovirus and Redondovirus DNA in Saliva Samples from SARS-CoV-2-Positive and -Negative Subjects ». Viruses 14, no 11 (9 novembre 2022) : 2482. http://dx.doi.org/10.3390/v14112482.
Texte intégralRésumé :
Objectives: Torquetenovirus (TTV) and Redondovirus (ReDoV) are the most prevalent viruses found in the human respiratory virome in viral metagenomics studies. A large-scale epidemiological study was performed to investigate their prevalence and loads in saliva samples according to SARS-CoV-2 status. Methods: Saliva samples from 448 individuals (73% SARS-CoV-2 negative and 27% SARS-CoV-2 positive) aged 23–88 years were tested. SARS-CoV-2 and TTV were determined in saliva by specific qualitative and quantitative real-time PCRs, respectively. A sub-cohort of 377 subjects was additionally tested for the presence and load of ReDoV in saliva, and a different sub-cohort of 120 subjects for which paired saliva and plasma samples were available was tested for TTV and ReDoV viremia at the same timepoints as saliva. Results: TTV in saliva was 72% prevalent in the entire cohort, at a mean DNA load of 4.6 log copies/mL, with no difference regardless of SARS-CoV-2 status. ReDoV was found in saliva from 61% of the entire cohort and was more prevalent in the SARS-CoV-2-negative subgroup (65% vs. 52%, respectively). In saliva, the total mean load of ReDoV was very similar to the one of TTV, with a value of 4.4 log copies/mL. The mean viral loads in subjects infected with a single virus, namely, those infected with TTV or ReDoV alone, was lower than in dually infected samples, and Tukey’s multiple-comparison test showed that ReDoV single-infected samples resulted in the only true outlier (p = 0.004). Differently from TTV, ReDoV was not detected in any blood samples. Conclusions: This study establishes the prevalence and mean value of TTV and ReDoV in saliva samples and demonstrates the existence of differences between these two components of the human virome.
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Carlisle, Ricarda, Carol Ann Rhoads, Tak Yee Aw et Lynn Harrison. « Endothelial cells maintain a reduced redox environment even as mitochondrial function declines ». American Journal of Physiology-Cell Physiology 283, no 6 (1 décembre 2002) : C1675—C1686. http://dx.doi.org/10.1152/ajpcell.00092.2002.
Texte intégralRésumé :
Human umbilical vein endothelial cells (HUVECs) are an endothelial model of replicative senescence. Oxidative stress, possibly due to dysfunctional mitochondria, is believed to play a key role in replicative senescence and atherosclerosis, an age-related vascular disease. In this study, we determined the effect of cell division on genomic instability, mitochondrial function, and redox status in HUVECs that were able to replicate for ∼60 cumulative population doublings (CPD). After 20 CPD, the nuclear genome deteriorated and the protein content of the cell population increased. This indicated an increase in cell size, which was accompanied by an increase in oxygen consumption, ATP production, and mitochondrial genome copy number and ∼10% increase in mitochondrial mass. The antioxidant capacity increased, as seen by an increase in reduced glutathione, glutathione peroxidase, GSSG reductase, and glucose-6-phosphate dehydrogenase. However, by CPD 52, the latter two enzymes decreased, as well as the ratio of mitochondrial-to-nuclear genome copies, the mitochondrial mass, and the oxygen consumption per milligram of protein. Our results signify that HUVECs maintain a highly reducing (GSH) environment as they replicate despite genomic instability and loss of mitochondrial function.
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Kim, Yeo, Lim, Song, Chun et Kim. « APEX1 Expression as a Potential Diagnostic Biomarker of Clear Cell Renal Cell Carcinoma and Hepatobiliary Carcinomas ». Journal of Clinical Medicine 8, no 8 (1 août 2019) : 1151. http://dx.doi.org/10.3390/jcm8081151.
Texte intégralRésumé :
Apurinic/apyrimidinic endonuclease 1/redox effector factor 1 (APEX1) has been known to play key roles in DNA repair, the regulation of diverse transcriptional activity, and cellular responses to redox activity. This study aimed to examine serum APEX1 (s-APEX1) expression as a possible screening biomarker for clear cell renal cell carcinoma (ccRCC), hepatocellular carcinoma (HCC), and proximal and distal cholangiocarcinoma (CC). A total of 216 frozen serum samples were collected from 39 healthy control cases, 32 patients with ≥58 copies/mL of hepatitis B viral DNA (HBV DNA (+)), 40 ccRCC cases, 59 HCC cases, and 46 CC cases. The serum samples were examined for s-APEX1 concentration by enzyme-linked immunosorbent assay. The association of APEX1 expression with clinicopathological characteristics was also studied by immunohistochemical staining in 106 ccRCC, 131 HCC, and 32 intrahepatic CC cases. The median s-APEX1 concentrations of the HCC, CC, ccRCC, healthy control, and HBV DNA (+) groups were 0.294, 0.710, 0.474, 0.038, and 2.384 ng/mL, respectively (p < 0.001). Univariate and multivariate analyses revealed that increased cytoplasmic APEX1 expression led to a shorter disease-free survival period in HCC and CC cases. We suggest that the s-APEX1 level could be a potential diagnostic biomarker of ccRCC, HCC, and CC. Additionally, cytoplasmic APEX1 expression in cancer cells could be used to predict relapses in patients with HCC or CC.
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Lin, Xueju, David Kennedy, Aaron Peacock, James McKinley, Charles T. Resch, James Fredrickson et Allan Konopka. « Distribution of Microbial Biomass and Potential for Anaerobic Respiration in Hanford Site 300 Area Subsurface Sediment ». Applied and Environmental Microbiology 78, no 3 (2 décembre 2011) : 759–67. http://dx.doi.org/10.1128/aem.07404-11.
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ABSTRACTSubsurface sediments were recovered from a 52-m-deep borehole cored in the 300 Area of the Hanford Site in southeastern Washington State to assess the potential for biogeochemical transformation of radionuclide contaminants. Microbial analyses were made on 17 sediment samples traversing multiple geological units: the oxic coarse-grained Hanford formation (9 to 17.4 m), the oxic fine-grained upper Ringold formation (17.7 to 18.1 m), and the reduced Ringold formation (18.3 to 52 m). Microbial biomass (measured as phospholipid fatty acids) ranged from 7 to 974 pmols per g in discrete samples, with the highest numbers found in the Hanford formation. On average, strata below 17.4 m had 13-fold less biomass than those from shallower strata. ThenosZgene that encodes nitrous oxide reductase (measured by quantitative real-time PCR) had an abundance of 5 to 17 relative to that of total 16S rRNA genes below 18.3 m and <5 above 18.1 m. MostnosZsequences were affiliated withOchrobactrum anthropi(97 sequence similarity) or had a nearest neighbor ofAchromobacter xylosoxidans(90 similarity). Passive multilevel sampling of groundwater geochemistry demonstrated a redox gradient in the 1.5-m region between the Hanford-Ringold formation contact and the Ringold oxic-anoxic interface. Within this zone, copies of thedsrAgene andGeobacteraceaehad the highest relative abundance. The majority ofdsrAgenes detected near the interface were related toDesulfotomaculumspp. These analyses indicate that the region just below the contact between the Hanford and Ringold formations is a zone of active biogeochemical redox cycling.
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Jun, Daniel, Adrian Grzedowski, J. Thomas Beatty et Dan Bizzotto. « Photosynthetic Reaction Centres Assembled on a Gold Electrode and the Photocurrent - Potential Response ». ECS Meeting Abstracts MA2022-01, no 45 (7 juillet 2022) : 1892. http://dx.doi.org/10.1149/ma2022-01451892mtgabs.
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The photosynthetic reaction centre (RC) from Rhodobacter sphaeroides has been studied for use in biohybrid solar cells. Much of the previous work has focussed on improving photocurrent generation by loading the electrode surface with many copies of the protein resulting in multilayers. The primary disadvantage with this approach is the random orientation of proteins, with some supposedly oriented properly. We used RCs with Cys for covalent attachment to a gold electrode and for proper orientation. Areas of bare electrode surface and RCs bound non-specifically (i.e. not bound via the Cys) were competitively displaced by an insulating, non-redox layer of mercaptohexanol (MCH). The adsorbed monolayer of RCs was imaged using atomic force microscopy to detail the distribution of RCs on the gold surface for surfaces prepared with different RC deposition concentrations. Photocurrents were measured for all RC modified surfaces using a LED modulation method which enabled measurement of photocurrent in the presence of large faradaic currents from the sacrificial reactant (hydroquinone) at a variety of applied potentials.[1] The photocurrents generated from a monolayer composed of RCs and MCH resulted in consistent photocurrent currents. which enabled modeling of the photocurrent generation using the Marcus-Hush-Chidsey theory to extract a reorganization energy for this process. Multilayers of adsorbed RCs were distinctly different and revealed that the local environment in which the RCs are embedded significantly influenced photocurrent generation. [1] Jun, D.; Beatty, J. T.; Bizzotto, D. Highly Sensitive Method to Isolate Photocurrent Signals From Large Background Redox Currents on Protein‐Modified Electrodes. ChemElectroChem 2019, 6 (11), 2870–2875.
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Huang, S. T., S. S. Tzean, B. Y. Tsai et H. J. Hsieh. « Cloning and heterologous expression of a novel ligninolytic peroxidase gene from poroid brown-rot fungus Antrodia cinnamomea ». Microbiology 155, no 2 (1 février 2009) : 424–33. http://dx.doi.org/10.1099/mic.0.022459-0.
Texte intégralRésumé :
A novel ligninolytic peroxidase gene (ACLnP) was cloned and characterized from a poroid brown-rot fungus, Antrodia cinnamomea. The genomic DNA of the fungus harboured two copies of ACLnP, with a length of 2111 bp, interlaced with 12 introns, while the full-length cDNA was 1183 bp, with a 66 bp signal peptide and an ORF of 990 bp. The three-dimensional molecular structure model was comparable to that of the versatile peroxidase of Pleurotus eryngii. ACLnP was cloned into vector pQE31, successfully expressed in Escherichia coli strain M15 under the control of the T5 promoter and produced a non-glycosylated protein of about 38 kDa, pI 5.42. The native and recombinant ACLnP was capable of oxidizing the redox mediator veratryl alcohol, and also decolorized bromophenol blue and 2,6-dimethoxyphenol dyes, implicating a functional extracellular peroxidase activity. The significance of discovering a functional ACLnP gene in A. cinnamomea in terms of wood degradation and colonization capacity in its unique niche is discussed.
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Cramm, R., A. Büsch et K. Strube. « NO-dependent transcriptional activation of gene expression in Ralstonia eutropha H16 ». Biochemical Society Transactions 34, no 1 (20 janvier 2006) : 182–84. http://dx.doi.org/10.1042/bst0340182.
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The σ54-dependent transcriptional regulator NorR of Ralstonia eutropha H16 activates gene expression in response to nitric oxide (NO). The N-terminal domain of NorR is thought to be involved in signal perception. A C112S exchange within this domain abolished promoter activation by the mutated protein, indicating that Cys112 is essential for the signalling mechanism of NorR. The DNA region recognized by NorR contains three copies of a conserved element termed the NorR-box. Alteration of bases within any of the NorR-boxes resulted in a significant decrease in promoter activation. Therefore all three boxes have to be recognized by NorR to activate its target promoter. NorR controls expression of an operon that encodes a redox-active non-haem-iron protein NorA and an NO reductase NorB. NorA exerts a negative effect on signal-dependent promoter activation by NorR. Optical spectroscopy of purified NorA indicates that the reduced protein can react with NO to form a ferrous nitrosyl adduct. Hence, NO binding by NorA opens up the possibility that NorA and NorR compete for NO in the cytoplasm.
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Allen, John F. « Why Chloroplasts and Mitochondria Contain Genomes ». Comparative and Functional Genomics 4, no 1 (2003) : 31–36. http://dx.doi.org/10.1002/cfg.245.
Texte intégralRésumé :
Chloroplasts and mitochondria originated as bacterial symbionts. The larger, host cells acquired genetic information from their prokaryotic guests by lateral gene transfer. The prokaryotically-derived genes of the eukaryotic cell nucleus now function to encode the great majority of chloroplast and mitochondrial proteins, as well as many proteins of the nucleus and cytosol. Genes are copied and moved between cellular compartments with relative ease, and there is no established obstacle to successful import of any protein precursor from the cytosol. Yet chloroplasts and mitochondria have not abdicated all genes and gene expression to the nucleus and to cytosolic translation. What, then, do chloroplast- and mitochondrially-encoded proteins have in common that confers a selective advantage on the cytoplasmic location of their genes? The proposal advanced here is that co-location of chloroplast and mitochondrial genes with their gene products is required for rapid and direct regulatory coupling. Redox control of gene expression is suggested as the common feature of those chloroplast and mitochondrial proteins that are encodedin situ. Recent evidence is consistent with this hypothesis, and its underlying assumptions and predictions are described.
Thèses sur le sujet "Coppie redox"
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FACCHINETTI, IRENE. « Thermally Regenerable Redox-Flow Batteries ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/308694.
Texte intégralRésumé :
Il calore a bassa temperatura (LTH), inferiore a 100°C, è una forma di energia largamente disponibile che viene dispersa nell’ambiente, senza alcun utilizzo. La conversione di questo tipo di energia in elettricità aprirebbe le porte allo sfruttamento di fonti energetiche come il calore solare, geotermico e di scarto industriale.
La conversione di LTH in elettricità non è però un processo efficiente a causa dei limiti posti dalla termodinamica, con la cosiddetta legge di Carnot, oltre che ai limiti tecnologici che riducono ulteriormente la conversione di questa forma di energia.
I dispositivi preposti per convertire LTH in elettricità devono poter operare con alte efficienze e potenze, e devono essere facilmente scalabili ed economici. Purtroppo, attualmente nessun dispositivo è in grado di effettuare questa conversione con potenze ed efficienze abbastanza elevate da giustificare gli alti costi (materiali, operazionali e manutenzione) e la complessità dei dispositivi stessi ed è per questo motivo che LTH non trova tutt’ora alcuna applicazione
Questo progetto di ricerca si è focalizzato sullo sviluppo di un dispositivo in grado di convertire LTH in maniera efficiente e con alte potenze. Tale dispositivo, chiamato Thermally Regnerable Redox-Flow Battery, TRB, è una batteria a flusso ricaricabile termicamente. Il dispositivo conta due diverse processi: la produzione energetica, che avviene in una cella elettrochimica in grado di produrre elettricità alle spese dell’energia libera di mescolamento di due soluzioni acquose dello stesso sale ma a diversa concentrazione. Quando le due soluzioni raggiungono la stessa concentrazione, la soluzione esausta viene mandata al secondo processo: un distillatore sottovuoto che rigenera il gradiente di concentrazione tra le due soluzioni sfruttando risorse di LTH. L’efficienza totale del dispositivo è quindi data dal prodotto tra l’efficienza della cella elettrochimica e l’efficienza del distillatore.
Studi termodinamici dimostrano che per incrementare tale efficienza è fondamentale lavorare sull’efficienza del distillatore, il cui valore dipende dalla scelta del soluto e del solvente. In particolare, per questo lavoro di ricerca si è scelto di operare con soluzioni acquose di NaI/I2 e LiBr/Br2.
I risultati raggiunti e le principali attività di ricerca vengono riportate brevemente in questo abstract:
Con la determinazione dei coefficienti di attività, si è calcolato l’energia libera di mescolamento e il potenziale a circuito aperto per entrambi i set di soluzioni (NaI e LiBr).
Le celle elettrochimiche sono state sviluppate specificamente per entrambi I sistemi studiati e test elettrochimici hanno permesso di valutare le performance dei due dispositivi, come potenza ed efficienza elettrochimica. La distillazione è stata modellizzata in modo da definire le condizioni ottimali di lavoro e determinare l’efficienza del processo.Low-Temperature Heat (LTH), below of 100°C, has elicited great interest among the scientific community, as a source of energy since it does not see any form of utilization as it is currently simply released into the environment. Its conversion would open the doors to the exploitation of a huge amount of energy as well, such as geothermal, solar, and industrial waste heat. The conversion efficiencies of LTH are low because of the limitations imposed by Carnot law, as well as the existence of technological limits which further reduce the efficiency of the conversion of LTH. In order to be suitable for extensive industrial production, LTH converters should show high power densities, scalable and efficient whilst being cost-effective; to this point, the devices proposed for this afore mentioned application all failed to achieve suitable efficiencies and power density, making the LTH conversion unfeasible. This PhD project was focused on the design of a device called Thermally Regenerable Redox-Flow Battery (TRB) consisting of a redox-flow battery that can be recharged by a thermal process. The device is based upon a two-stages technology composed by a “power production” stage and a “thermal” stage: power production happens in an electrochemical cell which release electricity at the expenses of the mixing free energy of two water solutions of the same salt at different concentrations, referred to as a concentration cell. When the two solutions reach the same concentration, the exhausted fluid is sent to the second stage, the thermal process, which regenerates the initial mixing free energy, by exploiting LTH sources, through vacuum distillation. The efficiency of the technology is the product between the efficiencies of the units in the device where both stages happen: the electrochemical cell, engineered for power production, and a distillation unit, designed to be responsible for thermal conversion. NaI/I2 and LiBr/Br2 water solutions will be the most discussed redox couple in this thesis, as result of thermodynamic analysis that have shown the importance related to the solvent and salt choice to ensure high energy conversion efficiencies. The achieved results, as well as the main research activities, are briefly reported here: starting from the determination of the activity coefficients, mixing free energy of the initial solutions, and the open circuit voltage of the electrochemical are calculated. Electrochemical cells are specifically designed for both systems while electrochemical tests are performed to evaluate the main performances of the devices, such as power density and electrochemical efficiency. Modeling of the operational conditions of the thermal stage allows to determine the distillation efficiency for both the solutions. The initial experiments prove an unprecedented heat-to-electricity efficiency for both the systems: 3% for TRB-NaI and 4-5% for TRB based on LiBr, depending on the thickness of the membrane with a power density output of almost 10 W m-2 for both technologies, which opens various possibilities to implement further improvements into this new class of energy storage/converter devices.
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Pernechele, Rebecca. « Copper-based Redox Systems for Dye-sensitized Solar Celles ». Thesis, KTH, Skolan för kemivetenskap (CHE), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-216402.
Texte intégralRésumé :
In order to take on the challenge of the world energy issues, there is a necessity to identify alternative energy sources to the fossil fuels. The sun represents the most abundant source of energy, and one way to harvest it is by photovoltaic devices directly converting sunlight into electricity. Among all photovoltaic devices, the dye-sensitized solar cells have attracted much interest because of the potential to be commercialized thanks to the cheap materials and the low-cost production processes. However, there are still issues to overcome, mainly related to the stability of the devices relating to the electrolyte components. In this project, a new type of electrolyte systems based on copper complex redox couples were synthetized and applied to DSSCs. Different monodentate ligands were investigated, in particular 2-mpy, 3-mpy and 4-mpy were coordinated by the copper metal centre. Several experimental techniques were used to characterized the products of synthesis, such as 1H NMR spectroscopy, mass spectrometry, powder X-ray diffraction and elemental analysis. The electrolyte properties were studied by UV-Vis spectrophotometry and cyclic voltammetry. The performance of the resulting solar cells was investigated by photocurrent density/photovoltage and incident photon-to-current conversion efficiency measurements and the recombination loss processes were studied by impedance spectroscopy and electron lifetime determinations. The redox couples based on 2-mpy and 3-mpy as ligands gave DSSC devices with very high open-circuit voltage up to 0.94 V and overall conversion efficiency up to 9.1% at 1 sun illumination. This is one of the highest conversion efficiencies recorded for copper based DSSC electrolytes and much higher than the solar cells containing the reference [Co(bpy)3]2+/3+ redox system. The high photo voltage, was attributed to the large resistance to electron recombination losses, which lead to a higher charge in the conduction band of the TiO2 moving it to more negative energies. This was also confirmed by the longer electron lifetime in the presence of the copper redox couples than the reference cobalt one. The TBP Lewis base additive was replaced by the methylpyridine ligands to mitigate ligand exchange problems. The replacement was successful using 3-mpy as additive as well as ligand to the copper ions. In continuation of this work, the other components of the device and the assembly process should be optimized. Moreover, single crystals of the copper systems should be grown to determine the exact structure and thus offer a better understanding of the processes that might take place in the device. An interesting project would be to try a one-pot electrolyte formulation, i.e. where all the reactants, solvent and additives are mixed and directly injected into the device. This is a good strategy to avoid the pre-syntheses and all the problems related to those.För att kunna ta sig an utmaningen med världens energiförsörjning, så måste alternativa energikällor till fossila bränslen identifieras. Ljus från solen utgör den mest tillgängliga källan till energi, och ett sätt att direkt omvandla denna energi till elektricitet är genom solceller. Bland olika typer av solceller, så har färgämnessensiterade solceller (DSSC) fått mycket uppmärksamhet pga deras kommersialiseringspotential med utgångspunkt i låg tillverkningskostnad. Det finns dock utmaningar som måste hanteras, huvudsakligen rörande stabilitet ssk avseende cellernas elektrolyt. Det här projektet omfattar studier av elektrolyter baserade på kopparkomplex som redoxsystem för DSSC. Särskilt kopparkomplex baserade på monodentata ligander, såsom 2- mpy, 3-mpy och 4-mpy, har studerats. Karaktärisering har baserats på flera olika tekniker, såsom 1H-NMR-spektroskopi, masspektrometri, pulverdiffraktion och elementaranalys. Elektroyuternas egenskaper har studerats genom UV-Vis-spektrofotometri och cyklisk voltametri. De resulterande solcellernas prestanda har undersökts genom fotoström/forospänningsstudier och IPCE-spektroskopi, samt rekombinationsförluster har kartlagts genom impedansspektroskopi och bestämning av fotoelektronernas livslängd. Redoxsystem baserade på 2-mpy och 3-mpy som ligander gav solceller som uppvisade mycket höga fotospänningar upp till 0,94 V och omvandlingseffektiviteter upp till 9,1% vis 1 sols bestrålning. Dessa prestanda är bland de högst uppmätta för DSSC baserade på kopparinnehållande elektrolyter och betydligt bättre än för referenssystem baserade på elektrolyter med [Co(bpy)3]2+/3+ som redoxpar. De höga fotospänningar som uppmätts tillskrivs en hög resistens mot rekombinationsförluster, vilket leder till högre laddning i ledningsbandet för TiO2 som i sin tur ger mer negativa energinivåer. Detta stöds även av de längre elektronlivslängder som uppmätts för system med kopparbaserade redoxsystem. Lewis-basen TBP, en vanlig additive till DSSC-elektrolyter, ersattes I dessa system med metylpyridinliganderna för att motverka problem med ligandutbyte. Detta utbyte var mest framgångsrikt för 3-mpy som additiv och samtidig ligand till kopparjonerna. Framtida studier bör omfatta en optimering av komponenter och konstruktion av DSSC baserade på kopparsystemen. Enkristaller av kopparsystemen bör syntetiseras för detaljerad strukturbestämning och därmed en bättre insikt i processer som sker i elektrolytsystemen. En intressant utveckling av projektet omfatta s k 'one-pot'-formulering av elektrolyter, där alla reaktander, lösningsmedel och additiver blandas och direkt injiceras i solcellen. Detta utgör en god startegi för att undvika för-synteser och alla problem relaterade till dessa.
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Davies, Paul. « The metallochemistry of the prion protein ». Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512372.
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The Prion protein (PrP) is a cell surface glycoprotein that has been directly implicated in the pathogenesis of a range of neurological disorders referred to as the transmissible spongiform encephalopathies (TSE’s). The protein has been shown to bind copper within its unstructured N-terminus but the affinity and stoichiometry of the association is a matter of some debate. In addition, the functional significance of this copper binding has yet to be elucidated. This study aimed to determine accurate metal binding parameters for PrP through the use of calorimetry and to provide insight into the potential redox implications of metal once bound. A method of analysis for complex binding to proteins is thoroughly assessed and found to be suitable. The study also aimed to qualify the involvement of metals in the proteins remarkable ability to survive in the environment. This study confirms that PrP binds copper with an affinity relative to the amount of copper available to the protein. A high nanomolar affinity is reported within two regions on the protein, the octarepeat and the 5th site. Binding within the octarepeat region is found to be highest at low copper concentrations, reducing to micromolar affinity when copper levels exceed equivalents of 1. There is also strong evidence of a complex and cooperative binding mechanism. The 5th site also displays high nanomolar affinity for a single atom of copper. These two regions on the protein also interact in the coordination of copper (II). The copper bound protein is highly redox active and is capable of fully reversible cycling of electrons that are dependent mainly on the octarepeat. The protein does bind other divalent cations but none appear to be physiologically relevant considering the amount of these free metal ions in the body. When adsorbed to model clays, PrP is able to survive for long periods at room temperature. This longevity is increased significantly by the presence of metals in the soil, especially manganese. These data provide confirmation of the precise parameters of divalent cation binding to PrP. It also confirms that the copper bound protein is capable of a physiological redox role.
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Harrington, Glynn. « An EPR investigation of copper-peroxide reactions in suspension systems ». Thesis, University of York, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337656.
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Hammond, Roger C. « Kinetic studies directed towards the improvement of Sandmeyer reactions ». Thesis, University of York, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296294.
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Walli, Adam. « Biomimetic Copper(I)-Mediated Activation of Dioxygen and Redox Non-Innocence in Copper(II) Complexes of Bis(oxazoline)s ». Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2014. http://hdl.handle.net/11858/00-1735-0000-0023-9636-9.
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Shi, Kaige. « New Polynuclear Copper-Pyrazolate Complexes : Towards the Synthesis of Photo- and Redox-Active Metal Organic Frameworks ». FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3859.
Texte intégralRésumé :
The main objectives of this project are the synthesis and redox- or photo-active modification and CO2 adsorption studies of metal-organic frameworks (MOFs) based on Cu3-pyrazolate secondary building units (SBUs). Trinuclear copper(II) complexes of the formula [Cu3(µ3-O)(µ-4-R-pz)3X3]z have been studied extensively due to their redox, magnetic and catalytic properties. In earlier work, we have shown that trinuclear copper(II) complexes of the formula [Cu3(µ3-O)(µ-4-R-pz)3X3]z pz = pyrazolato anion; R = H, CH(O), Cl, Br and NO2; X = Cl, NCS, CH3COO, CF3COO and pyridine – can be oxidized to the corresponding z+1, formally CuII2CuIII, species. In this project, fourteen (14) new copper-pyrazolate complexes of varying nuclearities (Cu3, Cu6, Cu7 and Cu12), terminal ligands (-NO2, py, -N3, -Cl) and bridging ligands (4-Cl-pzH and 4-Ph-pzH) have been synthesized. Efforts have been made to prepare MOFs based on the Cu3(µ3-O)-SBUs. While attempting to design the most suitable SBU for redox-active MOF construction, it was found that the one-electron oxidation of the all-CuII complex [Cu3(µ3-O)(µ-pz)3(NO2)3]2–, [8]2-, was achieved at redox potential more cathodic than any other Cu3(µ3-O)-complexes studied in our laboratory. The mixed-valent compound, [Cu3(µ3-O)(µ-pz)3(NO2)3]–, [8]-, the easiest accessible CuII2CuIII species known to date, was characterized spectroscopically. Compound [8] and analogous [11] release NO almost quantitatively upon the addition of PhSH or acetic acid. The system is catalytic in the presence of excess nitrite.
Before embarking on the study of photo-active MOFs, a simpler model compound – a dimer of trimer [{Cu3(µ3-OH)(µ-4-Cl-pz)3(py)2}2(µ-abp)](ClO4)4 [21], where abp = 4,4’-azopyridine, was synthesized and its photochemistry was studied. The absorption spectra recorded before and after irradiation indicated a structural change. Two dimensional (2D) and three dimensional (3D) materials with {[Cu3(µ3-OH)(µ-4-R-pz)3]2+}n SBUs where R = Ph or Cl , which can potentially undergo cis/trans-isomerization, have been prepared during this project. A Phenyl substituent at 4-position on the pyrazole ligand leads to the formation of new class of 2D sheets. Three new 3D porous MOFs based on {[Cu3(µ3-OH)(µ-4-Cl-pz)3]2+}n SBUs have interpenetrated- lattice structures and are capable of adsorbing CO2 selectively. Compounds FIU-1 and FIU-3 also exhibit hysteretic sorption-desorption profiles indicating the flexibility of the MOFs upon adsorption. Compound FIU-1 demonstrates the usefulness of a hexanuclear CuII -pyrazolate moiety as an SBU for generating 3-fold interpenetrated 3D polymeric network. Complexes FIU-2 and FIU-3 have novel 3-fold interpenetrating 3D hexagonal framework structures. Compound FIU-2 crystallizes in the monoclinic crystal system with the P21/c space group, whereas FIU-3 crystallizes in triclinic space group P . Both structures contain Cu3-SBUs connected by the linkers through the Cu-termini.
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Salem, Kelley. « Copper-zinc superoxide dismutase and glucose metabolism as redox targets for bortezomib resistance in multiple myeloma ». Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/1500.
Texte intégralRésumé :
Multiple myeloma (MM) is a prevalent B-cell neoplasm that remains incurable with currently available chemotherapeutic drugs. Existing drug regimens result in initial disease remission but MM often relapses with an aggressive, drug resistant phenotype with uniform mortality. Bortezomib (BTZ, proteasome inhibitor) is a frontline anti-MM drug that is used for treatment of newly diagnosed and relapsed MM. However both intrinsic and acquired BTZ resistance is observed. Hence, gaining a mechanistic understanding of BTZ-resistance can provide novel targets to increase and restore BTZ cytotoxicity in MM. Studies show that BTZ-mediated proteasome inhibition generates oxidative stress therefore, BTZ resistance can be caused by an increase in cellular antioxidant capacity of MM cells. Antioxidants like superoxide dismutases (SODs), glutathione (GSH), and glutathione peroxidases (GPxs) can maintain cellular redox homeostasis and confer resistance to oxidative stress. Additionally, an increased glucose metabolism can assist in maintaining low reactive oxygen species (ROS) levels formed as by-products of endogenous or therapy induced oxidative stress. This led us to test the hypothesis that BTZ resistance in MM is linked to redox regulation via the antioxidant network and generation of reducing equivalents. Retrospective analysis of clinically annotated MM dataset shows a correlation between SOD1 gene expression, MM progression, and poor overall and event free survival. In a MM cell line model with intrinsic or acquired BTZ resistance, our results show a correlation between half maximal inhibitory concentration (IC50) of BTZ and CuZnSOD activity. Upon inhibition of CuZnSOD activity with a clinically approved drug, disulfiram (DSF, Antabuse), BTZ cytotoxicity was increased. Furthermore, enforced overexpression of CuZnSOD conferred BTZ resistance in an otherwise BTZ sensitive MM cell line. MM cell lines with differential intrinsic BTZ cytotoxicity displayed a correlation between BTZ IC50 and GSH levels as well as GPx-1 activity. Gene expression profiling data from patients showed that poor prognosis associates with increased glycolytic gene expression in MM. Also, MM cell lines with intrinsic resistance toward BTZ exhibited increased glucose uptake, increased mRNA expression and activity of glucose-6-phosphate dehydrogenase (G6PD) with increased cytotoxicity with glucose deprivation or 2-deoxyglucose (2-DG) treatment. In conclusion, our results provide a rationale for utilizing redox-based combination protocols of clinically approved drugs (i.e. DSF and 2-DG) with BTZ to improve MM therapy responses.
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Masters, Sheldon. « Lead and Copper Contamination in Potable Water : Impacts of Redox Gradients, Water Age, Water Main Pipe Materials and Temperature ». Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/73338.
Texte intégralRésumé :
Potable water can become contaminated with lead and copper due to the corrosion of pipes, faucets, and fixtures. The US Environmental Protection Agency Lead and Copper Rule (LCR) is intended to target sampling at high-risk sites to help protect public health by minimizing lead and copper levels in drinking water. The LCR is currently under revision with a goal of better crafting sampling protocols to protect public health. This study examined an array of factors that determine the location and timing of "high-risk" in the context of sampling site selection and consumer health risks. This was done using field studies and well-controlled laboratory experiments.
A pilot-scale simulated distribution system (SDS) was used to examine the complex relationship between disinfectant type (free chlorine and chloramine), water age (0-10.2 days), and pipe main material (PVC, cement, and iron). Redox gradients developed in the distribution system as controlled by water age and pipe material, which affected the microbiology and chemistry of the water delivered to consumer homes. Free chlorine disinfectant was the most stable in the presence of PVC while chloramine was most stable in the presence of cement. At shorter water ages where disinfectant residuals were present, chlorine tended to cause as much as 4 times more iron corrosion when compared to chloramine. However, the worst localized attack on iron materials occurred at high water age in the system with chloramine. It was hypothesized that this was due to denitrification-a phenomenon relatively unexplored in drinking water distribution systems and documented in this study.
Cumulative chemical and biological changes, such as those documented in the study described above, can create "high-risk" hotspots for elevated lead and copper, with associated concerns for consumer exposure and regulatory monitoring. In both laboratory and field studies, trends in lead and copper release were site-specific and ultimately determined by the plumbing material, microbiology and chemistry. In many cases, elevated levels of lead and copper did not co-occur suggesting that, in a revised LCR, these contaminants will have to be sampled separately in order to identify worst case conditions.
Temperature was also examined as a potentially important factor in lead and copper corrosion. Several studies have attributed higher incidence of childhood lead poisoning during the summer to increased soil and dust exposure; however, drinking water may also be a significant contributing factor. In large-scale pipe rigs, total and dissolved lead release was 3-5 times higher during the summer compared to the winter. However, in bench scale studies, higher temperature could increase, decrease, or have no effect on lead release dependent on material and water chemistry. Similarly, in a distribution system served by a centralized treatment plant, lead release from pure lead service lines increased with temperature in some homes but had no correlation in other homes. It is possible that changes throughout the distribution system such as disinfectant residual, iron, or other factors can create scales on pipes at individual homes, which determines the temperature dependency of lead release.
Consumer exposure to lead can also be adversely influenced by the presence of particulate iron. In the case of Providence, RI, a well-intentioned decrease in the finished water pH from 10.3 to 9.7, resulted in an epidemic of red water complaints due to the corrosion of iron mains and a concomitant increase in water lead levels. Complementary bench scale and field studies demonstrated that higher iron in water is sometimes linked to higher lead in water, due to sorption of lead onto the iron particulates.
Finally, one of the most significant emerging challenges associated with evaluating corrosion control and consumer exposure, is the variability in lead and copper during sampling due to semi-random detachment of lead particles to water, which can pose an acute health concern. Well-controlled test rigs were used to characterize the variability in lead and copper release and compared to consumer sampling during the LCR. The variability due to semi-random particulate detachment, is equal to the typical variability observed in LCR sampling, suggesting that this inherent variability is much more important than other common sources including customer error, customer failure to follow sampling instructions or long stagnation times. While instructing consumers to collect samples are low flow rates reduces variability, it will fail to detect elevated lead from many hazardous taps. Moreover, collecting a single sample to characterize health risks from a given tap, are not adequately protective to consumers in homes with lead plumbing, in an era when corrosion control has reduced the presence of soluble lead in water. Future EPA monitoring and public education should be changed to address this concern.Ph. D.
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Furamera, Tendai Attan. « A Preliminary investigation of the ferric leaching of a mixed sulphide copper concentrate at controlled redox potentials ». Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/5332.
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Bibliography: leaves 63-68.This thesis is part of the greater study and looks into understanding the ferric leaching sub-process by establishing an effective way of measuring the rate of the chemical leach process.
Chapitres de livres sur le sujet "Coppie redox"
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Likhtenshtein, Gertz I. « Copper-Containing Enzymes ». Dans Chemical Physics of Redox Metalloenzyme Catalysis, 187–98. Berlin, Heidelberg : Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-73100-6_8.
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Margerum, Dale W., William M. Scheper, Michael R. McDonald, Françoise C. Fredericks, Lihua Wang et Hsiupu D. Lee. « Redox Decomposition Reactions of Copper(III) Peptide Complexes ». Dans Bioinorganic Chemistry of Copper, 213–21. Dordrecht : Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-6875-5_17.
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Kaiser, U., G. Canters et W. MÄntele. « The Redox Reaction of Type I Blue Copper Proteins ». Dans Spectroscopy of Biological Molecules : Modern Trends, 139–40. Dordrecht : Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5622-6_63.
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Baksi, Arnab, David L. Cocke, Andrew Gomes, John Gossage, Mark Riggs, Gary Beall et Hylton McWhinney. « Characterization of Copper-Manganese-Aluminummagnesium Mixed Oxyhydroxide and Oxide Catalysts for Redox Reactions ». Dans Characterization of Minerals, Metals, and Materials 2016, 151–58. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119263722.ch18.
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Pardasani, R. T., et P. Pardasani. « Magnetic properties of copper(II) bromo complex with β-ketonimine (spectral and redox model for blue copper protein) ». Dans Magnetic Properties of Paramagnetic Compounds, 944–45. Berlin, Heidelberg : Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-53974-3_489.
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Pardasani, R. T., et P. Pardasani. « Magnetic properties of copper(II) chloro complex with β-ketonimine (spectral and redox model for blue copper protein) ». Dans Magnetic Properties of Paramagnetic Compounds, 946–47. Berlin, Heidelberg : Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-53974-3_490.
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Pardasani, R. T., et P. Pardasani. « Magnetic properties of copper(II) bromo complex with β-ketonimine (spectral and redox model for blue copper protein) ». Dans Magnetic Properties of Paramagnetic Compounds, 948–49. Berlin, Heidelberg : Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-53974-3_491.
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Pardasani, R. T., et P. Pardasani. « Magnetic properties of copper(II) chloro complex with β-ketonimine (spectral and redox model for blue copper protein) ». Dans Magnetic Properties of Paramagnetic Compounds, 950–51. Berlin, Heidelberg : Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-53974-3_492.
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Pardasani, R. T., et P. Pardasani. « Magnetic properties of copper(II) acetato complex with β-ketonimine (spectral and redox model for blue copper protein) ». Dans Magnetic Properties of Paramagnetic Compounds, 952–53. Berlin, Heidelberg : Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-53974-3_493.
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Pardasani, R. T., et P. Pardasani. « Magnetic properties of copper(II) acetato complex with β-ketonimine (spectral and redox model for blue copper protein) ». Dans Magnetic Properties of Paramagnetic Compounds, 954–55. Berlin, Heidelberg : Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-53974-3_494.
Texte intégralActes de conférences sur le sujet "Coppie redox"
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Ghosh, Sudakshina, Belinda Willard, Suzy Comhair, Weiling Xu, Sruti Shiva, Kulwant Aulak, Michael Kinter et Serpil C. Erzurum. « Redox Dependent Function Of Copper-Zinc Superoxide Dismutase In Human Asthma ». Dans American Thoracic Society 2012 International Conference, May 18-23, 2012 • San Francisco, California. American Thoracic Society, 2012. http://dx.doi.org/10.1164/ajrccm-conference.2012.185.1_meetingabstracts.a4960.
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Flores Diaz, Natalie. « Enhanced Blue Photosensitizer for Dye-Sensitized Solar Cells employing a Copper-based Redox Mediator ». Dans 13th Conference on Hybrid and Organic Photovoltaics. València : Fundació Scito, 2021. http://dx.doi.org/10.29363/nanoge.hopv.2021.098.
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Schimpf, Alina, et Alexander Rachkov. « Synthesis of Monodisperse and Size-Tunable Colloidal Copper Phosphide Nanocrystals by Redox Disproportionation of Aminophosphine ». Dans nanoGe Fall Meeting 2019. València : Fundació Scito, 2019. http://dx.doi.org/10.29363/nanoge.ngfm.2019.290.
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Schimpf, Alina, et Alexander Rachkov. « Synthesis of Monodisperse and Size-Tunable Colloidal Copper Phosphide Nanocrystals by Redox Disproportionation of Aminophosphine ». Dans nanoGe Fall Meeting 2019. València : Fundació Scito, 2019. http://dx.doi.org/10.29363/nanoge.nfm.2019.290.
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Kopp, Angela, et Sudip Chakravarty. « Universality of transition temperatures in families of copper-oxide superconductors : interlayer tunneling redux ». Dans Optics & Photonics 2005, sous la direction de Ivan Bozovic et Davor Pavuna. SPIE, 2005. http://dx.doi.org/10.1117/12.623139.
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Liang, Xianwen, Jianwen Zhou, Gang Li, Tao Zhao, Pengli Zhu, Rong Sun et Ching-ping Wong. « In-Situ Redox Nanowelding of Copper Nanowires with Surficial Oxide Layer as Solder for Flexible Transparent Electromagnetic Interference Shielding ». Dans 2019 IEEE 69th Electronic Components and Technology Conference (ECTC). IEEE, 2019. http://dx.doi.org/10.1109/ectc.2019.00118.
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Sharna, Sharmin. « In-situ STEM study to understand the structural evolution of nanometric copper based oxygen carrier during high temperature redox cycling for Chemical Combustion Looping (CLC) ». Dans European Microscopy Congress 2020. Royal Microscopical Society, 2021. http://dx.doi.org/10.22443/rms.emc2020.247.
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Shaw, R. A., U. I. Tuor, T. Foniok, S. Bascaramurty, K. Ringland, E. McKenzie, M. Qiao, B. Tomanek et H. H. Mantsch. « Simultaneous Near-IR Spectroscopy and Magnetic Resonance Imaging to Assess Cerebral Oxygenation and Brain Water during Hypoxia-Ischemia in 2-week-old Rats ». Dans European Conference on Biomedical Optics. Washington, D.C. : Optica Publishing Group, 2001. http://dx.doi.org/10.1364/ecbo.2001.4432_57.
Texte intégralRésumé :
Cerebral near-infrared spectroscopy can potentially probe several parameters related to the onset of stroke and the ensuing tissue damage. One obvious marker of ischemia is cerebral oxygenation, which can be lowered sharply in stroke-affected tissue. Also commonly assessed, though less straightforward to recover, is the redox state of the cytochrome aa3 copper center. Finally, parameters that are in principle available but seldom recovered from in vivo near-IR spectra are changes in water concentration and scattering properties of the tissue. We have evaluated the potential for near-IR spectroscopy to detect relevant changes in cerebral oxygenation, blood volume, water content, and scattering properties in an infant rat stroke model that is well characterized by magnetic resonance imaging methods. The specific aim was to acquire near-IR spectra simultaneously with MR images and to correlate stroke-associated changes detected via these two modalities prior to, during and after a hypoxia-ischemia episode within this stroke model. Presented here are results from the design and testing of a near-IR illumination/detection system that is compatible with an MR imaging system, and the recovery of trends in the near-IR spectra that complement the hypoxic-ischemic changes observed in the MR images. Unexpectedly large intensity changes observed for the in vivo near-IR water absorptions are ascribed to hypoxia-induced variations in effective optical pathlength, suggesting that the water absorptions may prove generally useful as a means to track such changes.
Rapports d'organisations sur le sujet "Coppie redox"
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Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova et Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, janvier 2016. http://dx.doi.org/10.32747/2016.7604286.bard.
Texte intégralRésumé :
The overall goal of this project was to elucidate the role of dissolved organic matter (DOM) in soil retention, bioavailability and plant uptake of silver and cerium oxide NPs. The environmental risks of manufactured nanoparticles (NPs) are attracting increasing attention from both industrial and scientific communities. These NPs have shown to be taken-up, translocated and bio- accumulated in plant edible parts. However, very little is known about the behavior of NPs in soil-plant system as affected by dissolved organic matter (DOM). Thus DOM effect on NPs behavior is critical to assessing the environmental fate and risks related to NP exposure. Carbon-based nanomaterials embedded with metal NPs demonstrate a great potential to serve as catalyst and disinfectors. Hence, synthesis of novel carbon-based nanocomposites and testing them in the environmentally relevant conditions (particularly in the DOM presence) is important for their implementation in water purification. Sorption of DOM on Ag-Ag₂S NPs, CeO₂ NPs and synthesized Ag-Fe₃O₄-carbon nanotubebifunctional composite has been studied. High DOM concentration (50mg/L) decreased the adsorptive and catalytic efficiencies of all synthesized NPs. Recyclable Ag-Fe₃O₄-carbon nanotube composite exhibited excellent catalytic and anti-bacterial action, providing complete reduction of common pollutants and inactivating gram-negative and gram-positive bacteria at environmentally relevant DOM concentrations (5-10 mg/L). Our composite material may be suitable for water purification ranging from natural to the industrial waste effluents. We also examined the role of maize (Zeamays L.)-derived root exudates (a form of DOM) and their components on the aggregation and dissolution of CuONPs in the rhizosphere. Root exudates (RE) significantly inhibited the aggregation of CuONPs regardless of ionic strength and electrolyte type. With RE, the critical coagulation concentration of CuONPs in NaCl shifted from 30 to 125 mM and the value in CaCl₂ shifted from 4 to 20 mM. This inhibition was correlated with molecular weight (MW) of RE fractions. Higher MW fraction (> 10 kDa) reduced the aggregation most. RE also significantly promoted the dissolution of CuONPs and lower MW fraction (< 3 kDa) RE mainly contributed to this process. Also, Cu accumulation in plant root tissues was significantly enhanced by RE. This study provides useful insights into the interactions between RE and CuONPs, which is of significance for the safe use of CuONPs-based antimicrobial products in agricultural production. Wheat root exudates (RE) had high reducing ability to convert Ag+ to nAg under light exposure. Photo-induced reduction of Ag+ to nAg in pristine RE was mainly attributed to the 0-3 kDa fraction. Quantification of the silver species change over time suggested that Cl⁻ played an important role in photoconversion of Ag+ to nAg through the formation and redox cycling of photoreactiveAgCl. Potential electron donors for the photoreduction of Ag+ were identified to be reducing sugars and organic acids of low MW. Meanwhile, the stabilization of the formed particles was controlled by both low (0-3 kDa) and high (>3 kDa) MW molecules. This work provides new information for the formation mechanism of metal nanoparticles mediated by RE, which may further our understanding of the biogeochemical cycling and toxicity of heavy metal ions in agricultural and environmental systems. Copper sulfide nanoparticles (CuSNPs) at 1:1 and 1:4 ratios of Cu and S were synthesized, and their respective antifungal efficacy was evaluated against the pathogenic activity of Gibberellafujikuroi(Bakanae disease) in rice (Oryza sativa). In a 2-d in vitro study, CuS decreased G. fujikuroiColony- Forming Units (CFU) compared to controls. In a greenhouse study, treating with CuSNPs at 50 mg/L at the seed stage significantly decreased disease incidence on rice while the commercial Cu-based pesticide Kocide 3000 had no impact on disease. Foliar-applied CuONPs and CuS (1:1) NPs decreased disease incidence by 30.0 and 32.5%, respectively, which outperformed CuS (1:4) NPs (15%) and Kocide 3000 (12.5%). CuS (1:4) NPs also modulated the shoot salicylic acid (SA) and Jasmonic acid (JA) production to enhance the plant defense mechanisms against G. fujikuroiinfection. These results are useful for improving the delivery efficiency of agrichemicals via nano-enabled strategies while minimizing their environmental impact, and advance our understanding of the defense mechanisms triggered by the NPs presence in plants.