171,818 research outputs found
Electrochemical Analysis of Proton-Coupled Electron Transfer: Fundamental Studies and Applications
No full textInternational audienceIn-depth cyclic voltammetry analysis has proven to be a powerful tool for addressing intricate reaction mechanisms involving proton-coupled electron transfer (PCET) reactions.1 We have demonstrated the use of this analytical technique to study intramolecular PCET reactions,2 molecular bond breaking coupled with PCET reactions,3 molecular catalytic reactions coupled with PCET,4 and heterogeneous electrocatalyst mechanisms involving PCET.5 These fundamental reactions are illustrated through theoretical analysis and experimental examples.Electrochemical water splitting is a clean technology with the potential for large-scale production of highly pure dihydrogen, a major energy vector for the near future. Over the years, benchmarking protocols have been proposed to evaluate the electrocatalytic water splitting activity and stability of heterogeneous hydrogen and oxygen evolution reaction electrocatalysts. However, the complexity of these multiple electron/proton transfer reactions makes it difficult to obtain reliable electrochemical measurements and gain direct insight into the HER and OER mechanisms. Herein we will discuss different aspects of PCET reactions, from electrochemical water splitting toward lignin activation.1. a) Bonin, J.; et al. C. Acc. Chem. Res. 2012, 45, 372; b) Costentin, C.; et al. Acc. Chem. Res. 2014, 47, 271.2. Costentin, C.; et al. Angew. Chem. Int. Ed. 2010, 49, 3803.3. a) Costentin, C.; et al. Proc. Natl. Acad. Sci. U. S. A. 2011, 108, 8559; b) Savéant, J.-M.; Tard, C. J. Am. Chem. Soc. 2014, 136, 8907.4. a) Savéant, J.-M.; Tard, C. J. Am. Chem. Soc. 2016, 138, 1017; b) Costentin, C.; Savéant, J.-M.; Tard, C. ACS Energy Lett. 2018, 3, 695.5. Costentin, C.; et al. C. Nat. Mat. 2017, 16, 1016.6. a) Faustini, M.; et al. Adv. Energy Mater. 2019, 9, 1802136; b) Elmaalouf, M; et al. Nat. Commun. 2021, 12, 3935. c) Elmaalouf, M.; et al. Chem. Sci. 2022, 13, 11807
Electrochemical Analysis of Proton-Coupled Electron Transfer: Fundamental Studies and Applications
No full textInternational audienceIn-depth cyclic voltammetry analysis has proven to be a powerful tool for addressing intricate reaction mechanisms involving proton-coupled electron transfer (PCET) reactions.1 We have demonstrated the use of this analytical technique to study intramolecular PCET reactions,2 molecular bond breaking coupled with PCET reactions,3 molecular catalytic reactions coupled with PCET,4 and heterogeneous electrocatalyst mechanisms involving PCET.5 These fundamental reactions are illustrated through theoretical analysis and experimental examples.Electrochemical water splitting is a clean technology with the potential for large-scale production of highly pure dihydrogen, a major energy vector for the near future. Over the years, benchmarking protocols have been proposed to evaluate the electrocatalytic water splitting activity and stability of heterogeneous hydrogen and oxygen evolution reaction electrocatalysts. However, the complexity of these multiple electron/proton transfer reactions makes it difficult to obtain reliable electrochemical measurements and gain direct insight into the HER and OER mechanisms. Herein we will discuss different aspects of PCET reactions, from electrochemical water splitting toward lignin activation.1. a) Bonin, J.; et al. C. Acc. Chem. Res. 2012, 45, 372; b) Costentin, C.; et al. Acc. Chem. Res. 2014, 47, 271.2. Costentin, C.; et al. Angew. Chem. Int. Ed. 2010, 49, 3803.3. a) Costentin, C.; et al. Proc. Natl. Acad. Sci. U. S. A. 2011, 108, 8559; b) Savéant, J.-M.; Tard, C. J. Am. Chem. Soc. 2014, 136, 8907.4. a) Savéant, J.-M.; Tard, C. J. Am. Chem. Soc. 2016, 138, 1017; b) Costentin, C.; Savéant, J.-M.; Tard, C. ACS Energy Lett. 2018, 3, 695.5. Costentin, C.; et al. C. Nat. Mat. 2017, 16, 1016.6. a) Faustini, M.; et al. Adv. Energy Mater. 2019, 9, 1802136; b) Elmaalouf, M; et al. Nat. Commun. 2021, 12, 3935. c) Elmaalouf, M.; et al. Chem. Sci. 2022, 13, 11807
Trop tard pour limiter le réchauffement à 2°C
No full textTrop tard pour limiter le réchauffement à 2°C, d’après Nature / Matthieu Auzanneau, Oil man, un blog du Monde, 6/11/2011 http://petrole.blog.lemonde.fr/2011/11/06/trop-tard-pour-limiter-le-rechauffement-a-2%C2%B0c-selon-nature/2/ La prise en compte de cette "dette carbone" (autrement dit l'impact réel sur le climat de notre mode de consommation) montre qu'en France, par exemple, les émissions n'ont pas baissé de 10 % depuis 1990, comme il est dit officiellement. Elles se sont au contraire ac..
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Uncertain Future of the European Union The End of European Integration – Anti-Europeanism Examined by Paul Taylor
No full textMitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Molecular electrochemistry: the avant-garde contribution of Jean-Michel Savéant
No full textInternational audienceDefining molecular electrochemistry as a “segment of electrochemistry where attention is primarily focused on the molecular changes brought about by electron transfer to or from an electrode”, it is evident that this analytical tool is an exceptional way to investigate molecular reactivity and establish concepts in chemistry and biochemistry. Prof. J.-M. Savéant, who sadly passed away in August 2020, dedicated his long career to developing, conceptualizing and using molecular electrochemistry with cyclic voltammetry as a guideline. From electron transfer reactions to molecular and enzymatic catalysis of electrochemical reactions, his contributions were indubitably key to the development of the field of molecular electrochemistry as well as found applications in photochemistry, material science, biochemistry, radical chemistry and synthetic chemistry.Herein we will try to review some of his essential pieces of work, spanning from molecular catalysis to his unique contributions to dissociative electron transfers and proton-coupled electron transfers. [1] Savéant, J.-M.; Costentin, C., Elements of molecular and biomolecular electrochemistry: an electrochemical approach to electron transfer chemistry. 2nd ed.; John Wiley & Sons, 2019. [2] Costentin, C.; Limoges, B.; Robert, M.; Tard, C., A pioneering career in electrochemistry: Jean-Michel Savéant. ACS Catal. 2021, 11 (6), 3224-3238. [3] Amatore, C.; Savéant, J.-M., ECE and disproportionation. VI. General resolution. Application to potential step chronoamperometry. J. Electroanal. Chem. Interfacial Electrochem. 1979, 102 (1), 21-40
Molecular electrochemistry: the avant-garde contribution of Jean-Michel Savéant
No full textInternational audienceDefining molecular electrochemistry as a “segment of electrochemistry where attention is primarily focused on the molecular changes brought about by electron transfer to or from an electrode”, it is evident that this analytical tool is an exceptional way to investigate molecular reactivity and establish concepts in chemistry and biochemistry. Prof. J.-M. Savéant, who sadly passed away in August 2020, dedicated his long career to developing, conceptualizing and using molecular electrochemistry with cyclic voltammetry as a guideline. From electron transfer reactions to molecular and enzymatic catalysis of electrochemical reactions, his contributions were indubitably key to the development of the field of molecular electrochemistry as well as found applications in photochemistry, material science, biochemistry, radical chemistry and synthetic chemistry.Herein we will try to review some of his essential pieces of work, spanning from molecular catalysis to his unique contributions to dissociative electron transfers and proton-coupled electron transfers. [1] Savéant, J.-M.; Costentin, C., Elements of molecular and biomolecular electrochemistry: an electrochemical approach to electron transfer chemistry. 2nd ed.; John Wiley & Sons, 2019. [2] Costentin, C.; Limoges, B.; Robert, M.; Tard, C., A pioneering career in electrochemistry: Jean-Michel Savéant. ACS Catal. 2021, 11 (6), 3224-3238. [3] Amatore, C.; Savéant, J.-M., ECE and disproportionation. VI. General resolution. Application to potential step chronoamperometry. J. Electroanal. Chem. Interfacial Electrochem. 1979, 102 (1), 21-40
Molecular electrochemistry: the avant-garde contribution of Jean-Michel Savéant
No full textInternational audienceDefining molecular electrochemistry as a “segment of electrochemistry where attention is primarily focused on the molecular changes brought about by electron transfer to or from an electrode”, it is evident that this analytical tool is an exceptional way to investigate molecular reactivity and establish concepts in chemistry and biochemistry. Prof. J.-M. Savéant, who sadly passed away in August 2020, dedicated his long career to developing, conceptualizing and using molecular electrochemistry with cyclic voltammetry as a guideline. From electron transfer reactions to molecular and enzymatic catalysis of electrochemical reactions, his contributions were indubitably key to the development of the field of molecular electrochemistry as well as found applications in photochemistry, material science, biochemistry, radical chemistry and synthetic chemistry.Herein we will try to review some of his essential pieces of work, spanning from molecular catalysis to his unique contributions to dissociative electron transfers and proton-coupled electron transfers. [1] Savéant, J.-M.; Costentin, C., Elements of molecular and biomolecular electrochemistry: an electrochemical approach to electron transfer chemistry. 2nd ed.; John Wiley & Sons, 2019. [2] Costentin, C.; Limoges, B.; Robert, M.; Tard, C., A pioneering career in electrochemistry: Jean-Michel Savéant. ACS Catal. 2021, 11 (6), 3224-3238. [3] Amatore, C.; Savéant, J.-M., ECE and disproportionation. VI. General resolution. Application to potential step chronoamperometry. J. Electroanal. Chem. Interfacial Electrochem. 1979, 102 (1), 21-40
- …
