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Tang, Wenxiu, Xintong Zhu i Yangyi Qian. "APPLYING FACTOR ANALYSIS FOR ASSESSING KNOWLEDGE STRUCTURE OF STUDENTS IN GRADE 10: THE SUBJECT OF REDOX REACTION". Journal of Baltic Science Education 21, nr 4 (25.08.2022): 680–93. http://dx.doi.org/10.33225/jbse/22.21.680.
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Redox reaction is an important concept in chemistry, and a well-organized knowledge structure of redox reaction is beneficial for concept learning. This study investigated the knowledge structure regarding redox reaction from 459 Grade 10 students. The pool of 15 redox reaction concepts was developed by content analysis, questionnaire survey, and interview. Six initial competing models with 15 concepts were identified via exploratory factor analysis (EFA) and paper-pencil test. Confirmatory factor analysis (CFA) was conducted to test and modify the six competing models according to the rating data of the students. As a result, six modified models fit the data well. However, the high inter-factor correlations indicate that the two- and three-factor models are the students' knowledge structures of redox reaction. The two-factor model is comprised of two distinct but correlated factors: the process of redox reaction and metrology. The three-factor model is comprised of three factors: the process of redox reaction, reaction ability, and metrology. The finding inflects the abstract relationships between the concepts related to redox reaction in students' minds. Keywords: redox reaction, chemistry education, knowledge structure, factor analysis
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Dessie, Yabibal Getahun, Qi Hong, Bachirou Guene Lougou, Juqi Zhang, Boshu Jiang, Junaid Anees i Eyale Bayable Tegegne. "Thermochemical Energy Storage Performance Analysis of (Fe,Co,Mn)Ox Mixed Metal Oxides". Catalysts 11, nr 3 (10.03.2021): 362. http://dx.doi.org/10.3390/catal11030362.
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Metal oxide materials are known for their ability to store thermochemical energy through reversible redox reactions. Metal oxides provide a new category of materials with exceptional performance in terms of thermochemical energy storage, reaction stability and oxygen-exchange and uptake capabilities. However, these characteristics are predicated on the right combination of the metal oxide candidates. In this study, metal oxide materials consisting of pure oxides, like cobalt(II) oxide, manganese(II) oxide, and iron(II, III) oxide (Fe3O4), and mixed oxides, such as (100 wt.% CoO, 100 wt.% Fe3O4, 100 wt.% CoO, 25 wt.% MnO + 75 wt.% CoO, 75 wt.% MnO + 25 wt.% CoO) and 50 wt.% MnO + 50.wt.% CoO), which was subjected to a two-cycle redox reaction, was proposed. The various mixtures of metal oxide catalysts proposed were investigated through the thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), energy dispersive X-ray (EDS), and scanning electron microscopy (SEM) analyses. The effect of argon (Ar) and oxygen (O2) at different gas flow rates (20, 30, and 50 mL/min) and temperature at thermal charging step and thermal discharging step (30–1400 °C) during the redox reaction were investigated. It was revealed that on the overall, 50 wt.% MnO + 50 wt.% CoO oxide had the most stable thermal stability and oxygen exchange to uptake ratio (0.83 and 0.99 at first and second redox reaction cycles, respectively). In addition, 30 mL/min Ar–20 mL/min O2 gas flow rate further increased the proposed (Fe,Co,Mn)Ox mixed oxide catalyst’s cyclic stability and oxygen uptake ratio. SEM revealed that the proposed (Fe,Co,Mn)Ox material had a smooth surface and consisted of polygonal-shaped structures. Thus, the proposed metallic oxide material can effectively be utilized for high-density thermochemical energy storage purposes. This study is of relevance to the power engineering industry and academia.
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Chumakov, Anton A., Valentina N. Batalova, Yuriy G. Slizhov i Tamara S. Minakova. "VERIFICATION OF NON-CATALYTIC HYDROGEN PEROXIDE DISPROPORTIONATION MECHANISM BY THERMODYNAMIC ANALYSIS OF ONE-ELECTRON REDOX REACTIONS". IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, nr 6 (19.07.2017): 40. http://dx.doi.org/10.6060/tcct.2017606.5529.
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There is two-electron transfer during the process of hydrogen peroxide decomposition into water and oxygen. The detailed mechanism of non-catalytic hydrogen peroxide disproportionation is not verified until now. We assumed that any poly-electron redox process is a complex and consists of one-electron redox reactions. We have formulated equations of possible one-electron transfers during hydrogen peroxide disproportionation. Based on known laws and equations of thermochemistry we calculated standard thermodynamic functions for a total reaction and each one-elect-ron redox reaction using reference values of standard thermodynamic functions of reagents and products of reactions. Results show that the total reaction leads to significant decrease in Gibbs free energy -246.0 kJ/mol in gas phase but there is increase +39.9 kJ/mol in Gibbs free energy during the first proposed step. It is substantiation for known dependence of hydrogen peroxide dismutation kinetics at thermal, photochemical or catalytic activation. The first proposed step of non-catalytic process is one-electron plus one-proton transfer in thermally or photochemically activated dimeric hydrogen peroxide associate (H2O2)2 with simultaneous generation of hydroperoxyl HO2• and hydroxyl HO• free radicals and water molecule. There is thermodynamic argumentation for radical chain mechanism of hydrogen peroxide disproportionation after the activation. We made the graphic illustration of thermodynamically supported scheme of non-catalytic hydrogen peroxide decomposition. There is a cyclic alternation of two radical-molecular interactions during the hydrogen peroxide chain decomposition. The hydroxyl radical generates the hydroperoxyl radi-cal from a hydrogen peroxide molecule and then the hydroperoxyl radical interacts with a next hydrogen peroxide molecule followed by the hydroxyl radical generation. Interactions between the homonymic or heteronymic free radicals are the reactions of chain breaking.Forcitation:Chumakov A.A., Batalova V.N., Slizhov Yu.G., Minakova T.S. Verification of non-catalytic hydrogen peroxide disproportionation mechanism by thermodynamic analysis of one-electron redox reactions. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 6. P. 40-44.
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Palisoa, Napsin. "PERBANDINGAN HASIL BELAJAR DAN MOTIVASI BELAJAR PESERTA DIDIK PADA MATERI REAKSI REDOKS KELAS X MA AL-FATAH AMBON SEBELUM DAN SELAMA MASA PANDEMI COVID-19". Molluca Journal of Chemistry Education (MJoCE) 11, nr 2 (30.09.2021): 106–20. http://dx.doi.org/10.30598/mjocevol11iss2pp106-120.
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This study aims to determine the differences in learning outcomes and students' learning motivation on redox reaction material for class X IPA MA Al-Fatah Ambon before and during the covid-19 pandemic. The sample in this study consisted of 22 students who studied redox reaction material in class X offline and 22 students who studied redox reactions online. This study uses a quantitative experimental research method with a comparative study research design. Collecting data in this study using a questionnaire, documentation and observation. Questionnaires were used to measure students' learning motivation, documentation was used to measure learning outcomes (cognitive, affective, and psychomotor) of students in class X before the pandemic and cognitive learning outcomes in class X during the pandemic, while observation was used to measure affective and psychomotor learning outcomes. Class X students during the COVID-19 pandemic. The documentation used is the value of students in the redox reaction material for the even semester 2019/2020 and even semester 2020/2021, then observations are made by participating in live online learning. The data obtained were then analyzed using descriptive and inferential data analysis methods. Based on the results of descriptive data analysis of learning motivation and student learning outcomes on redox reaction material for class X before and during the pandemic period, it was in the moderate category, while based on the results of inferential data analysis using Mann-Whitney analysis for learning motivation, the Asymp sig value was obtained. (2-tailed) 0.646 and 0.000 learning outcomes. The results show that there are no differences in students' learning motivation before and during the COVID-19 pandemic, so H0 is accepted, and there are differences in student learning outcomes before and during the COVID-19 pandemic, so H0 is rejected.
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Hadinugrahaningsih, Tritiyatma, Yuli Rahmawati i Elma Suryani. "An analysis of preservice Chemistry teachers’ misconceptions of reduction-oxidation reaction concepts". Journal of Technology and Science Education 12, nr 2 (7.07.2022): 448. http://dx.doi.org/10.3926/jotse.1566.
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This article describes a study of 149 of preservice chemistry teachers’ misconceptions of concepts related to an reduction-oxidation reaction. A mixed-method approach was used to obtain data through the ROXCI (Redox Concept Inventory) instrument and interviews. Results indicated that the highest misconceptions were for item number 10 (4.03% or only 6 of 149 students answered correctly) and the lowest misconception occurred on item number 1 (94.63% or 141 of 149 students answered correctly). These results were supported by the analysis of the interviews where the respondents produced misconceptions when explaining the process of electron transfer in redox reactions. The highest percentage of consistent answers in the six ROXCI categories was obtained in the surface feature concept category (6.71% or 10 out of 149 respondents consistently answered correctly). This shows that preservice chemistry teachers are not able to connect the three levels of chemical representation, macroscopic, microscopic, and symbolic in studying chemistry, especially for the redox concept. Analysis of the relationships between misconceptions and average student confidence shows that every distractor chosen by the respondents at every level was followed by a degree of confidence of between 50%-70%, indicating that misconceptions became stronger because the preservice chemistry teachers did not realize that a concept believed to be true is wrong.
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Kulys, J., i Ž. Dapkūnas. "The Effectiveness of Synergistic Enzymatic Reaction with Limited Mediator". Nonlinear Analysis: Modelling and Control 12, nr 4 (25.10.2007): 495–501. http://dx.doi.org/10.15388/na.2007.12.4.14680.
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Kinetics of biocatalytical synergistic reactions has been analyzed with special emphasis on stability and reactivity of mediators. The application to the model of kinetic constants taken from the experiments showed that the quasi steady state (QSS) for reduced and oxidized enzyme was achieved in 0.001 s. However, the QSS for the mediator was not established during measurable time. For this reason the kinetics of biocatalytical synergistic reactions was modeled by solving the ordinary differential equations using software package KinFitSim©.
The calculations showed the increase of an apparent life-time of the mediator in the synergistic reaction. The apparent life-time was most affected by reactivity of mediator. The change of the mediator reactivity from 1 M−1s−1 to 105 M−1s−1 increased the apparent life-time from 19 s to 1538 s. This mediator reactivity can be achieved even for strongly endothermic reaction when difference of redox potential of substrate and mediator is 0.35 V. The increase of mediator life-time increased product yield.
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Tripathi, Anand Kumar, Miji E. Joy, Debittree Choudhury, Rubul Das i Manoj Neergat. "Kinetics of V5+/V4+ Redox Reaction—Butler-Volmer and Marcus Models". Journal of The Electrochemical Society 168, nr 11 (1.11.2021): 110548. http://dx.doi.org/10.1149/1945-7111/ac39d9.
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Kinetics of the V5+/V4+ redox reaction on Vulcan XC-72 modified glassy carbon disk electrode is investigated in a three-electrode configuration. Cyclic voltammograms of V5+/V4+ redox couple suggest that the overpotential range for the kinetic analysis is limited to ±300 mV, after excluding V4+/V3+ redox reaction at the negative overpotential and the oxygen evolution reaction at the positive overpotential. The linear sweep-voltammograms (LSVs) are corrected for potential drop due to solution resistance (iR s ), mass-transfer resistance, and most importantly, for the back reaction current. These corrections are imperative to estimate the Tafel slope in the limited range of overpotential for V5+/V4+ redox reaction. The charge-transfer coefficient (α) estimated from the Tafel slope deviates significantly from the expected value of 0.5 for the single electron-transfer reaction. Moreover, the instantaneous slope of the Tafel plot suggests that the α is overpotential dependent. Therefore, Marcus theory of electrochemical kinetics is applied to estimate the α. The reorganization energy (λ) calculated from the Arrhenius plots is in the range of values reported in the literature for the other redox couples.
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Fitriyah, Isnanik Juni, Muhammad Fajar Marsuki i Yessi Affriyenni. "Development of E-learning Based on Augmented Reality (AR) on Reduction-Oxidation Reaction Topic". International Journal of Interactive Mobile Technologies (iJIM) 16, nr 03 (10.02.2022): 151–58. http://dx.doi.org/10.3991/ijim.v16i03.28977.
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The concept of electrochemistry is based on reduction-oxidation (redox) reactions and electrolyte solutions. Where this material is difficult to understand because the aspects studied include submicroscopic aspects. It takes teaching materials that are able to display animations of redox reactions. This study aims to develop teaching materials based on Augmented Reality on Redox Reaction material. This type of research includes research and development (R&D) using the ADDIE model with the stages of analysis, design, develop and evaluation. The product will be tested for validity through expert testing and field testing. The validation test of material, media and readability experts to students resulted in a percentage of 92.5%, 94.39% and 91.6% respectively or declared very feasible and very good for use in lectures with several revisions. It can be concluded that AR-based media is stated to be very feasible and very good for use in learning. It is hoped that further testing of the effectiveness of this media will be carried out.
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Bao, Qi, Shu Fang Zhang i Dun Zhang. "Synthesis and Electrochemical Behavior of Two Microporous Polyoxomolybdates". Advanced Materials Research 79-82 (sierpień 2009): 1479–82. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1479.
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Two new microporous polyoxomolybdates of (NH4)2[γ-Mo8O26] (Compound I) and (NH4)2[Mo4O13] (Compound II) were synthesized hydrothermally and characterized by elemental analysis, infra-red, TG analysis and single-crystal X-ray diffraction. In the synthesis process, we found that both organic template and transition metal salt play crucial roles in the formation of crystals. Cyclic voltammetry was used to study their electrochemical properties. The results reveal that the two compounds possess electrochemical activity in 0.2M H2SO4+Na2SO4 ( pH=1 ) solution and three multi-electron transferred redox reaction (I-I´, II-II´ and III-III´) processes were obtained. The first two redox reactions (I-I´, II-II´) are reversible reaction processes but another one (III-III´) is not. The electrochemical properties of the two compounds indicate their great potential applications in electroanalysis and electrocatalysis.
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Ohura, Hiroki, i Toshihiko Imato. "Rapid and Automated Analytical Methods for Redox Species Based on Potentiometric Flow Injection Analysis Using Potential Buffers". Journal of Automated Methods and Management in Chemistry 2011 (2011): 1–14. http://dx.doi.org/10.1155/2011/516165.
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Two analytical methods, which prove the utility of a potentiometric flow injection technique for determining various redox species, based on the use of some redox potential buffers, are reviewed. The first is a potentiometric flow injection method in which a redox couple such as Fe(III)-Fe(II), Fe-Fe(CN), and bromide-bromine and a redox electrode or a combined platinum-bromide ion selective electrode are used. The analytical principle and advantages of the method are discussed, and several examples of its application are reported. Another example is a highly sensitive potentiometric flow injection method, in which a large transient potential change due to bromine or chlorine as an intermediate, generated during the reaction of the oxidative species with an Fe(III)-Fe(II) potential buffer containing bromide or chloride, is utilized. The analytical principle and details of the proposed method are described, and examples of several applications are described. The determination of trace amounts of hydrazine, based on the detection of a transient change in potential caused by the reaction with a Ce(IV)-Ce(III) potential buffer, is also described.
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Jannah, Riza Raudatul, i Lisa Utami. "Identifikasi Miskonsepsi Siswa Pada Materi Reaksi Redoks Menggunakan Certainty Of Respond Indeks". Journal of The Indonesian Society of Integrated Chemistry 10, nr 2 (6.04.2019): 50–60. http://dx.doi.org/10.22437/jisic.v10i2.5849.
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This Research aimed at identifying student misconception on Redox Reaction lesson at the tenth grade of State Vocational High School 5 Pekanbaru. It was Descriptive. Purposive sampling technique was used, and the sample were the tenth grade students of class TAV 2. Multiple choice with reasoning diagnostic test with CRI (Certainty of Response Index) column was the instrument used. Based on the research findings, it showed that there was a student misconception on Redox Reaction lesson. Sub concept was the highest misconception. The concept development of Redox Reaction lesson was 22.23%, sub concept of oxidation number was 19.05%, and sub concept of reducing and oxidation agents was 12.7%. Misconception happened because of the learning method that was teacher center, the lack of textbook reference, and the low of student learning interest. Based on the data analysis, it revealed that CRI was effective to be used to identify student misconception.
Keywords: Misconception, Multiple Choice Test Reasoned Open, CRI (Certainty of Response Index), Redox Reaction Concept
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Hasniyah, Fatayatul, i Zainuddin Muchtar. "Pengembangan Uji Instrumen Tiga Tingkat dengan CRI untuk Mendeteksi Miskonsepsi dalam Pembelajaran Reaksi Redoks". Jurnal Inovasi Pembelajaran Kimia 3, nr 2 (30.10.2021): 123. http://dx.doi.org/10.24114/jipk.v3i2.26503.
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Research has been carried out to develop a Three Tier Instrument Test with Certainty of Response Index (CRI) with the aims to find out (1) analysis of teaching learning chemistry, (2) the eligibility categories in terms of expert validation, (3) the percentage of misconceptions in each sub-concepts of redox reaction, and (4) the causes of students’ misconceptions about redox reaction material. The instrument is prepared with 10 items validated contains each sub concepts. Research results show that: (1) teaching learning chemistry using curriculum 2013, various student textbooks and methods so research develop many aspects of question instruments that needed in research by interviewing the teacher of each schools, (2) the test instrument has very decent criteria with the assessment of material, language, and construction aspect, (3) the lowest percentages of students’ misconception in redox reaction’s sub-concept is oxidizing and reducing agent in reaction (54.09%) and the highest percentages is in sub-concept of autoredox concept (69.98%) with all categories of misconceptions are enough, (4) the causes of students’ misconceptions in learning redox reaction found in the material, learning source, teachers aspect. It because students were taught by different teacher, different method, and different source in learning redox reaction.
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Tada, Shotaro, Shota Saito, Akito Mori, Hideki Mizuno, Shiori Ando, Toru Asaka, Yusuke Daiko, Sawao Honda, Samuel Bernard i Yuji Iwamoto. "Reversible Redox Property of Co(III) in Amorphous Co-doped SiO2/γ-Al2O3 Layered Composites". Materials 13, nr 23 (25.11.2020): 5345. http://dx.doi.org/10.3390/ma13235345.
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This paper reports on a unique reversible reducing and oxidizing (redox) property of Co(III) in Co-doped amorphous SiO2/γ-Al2O3 composites. The Fenton reaction during the H2O2-catalyzed sol–gel synthesis utilized in this study lead to the partial formation of Co(III) in addition to Co(II) within the composites. High-resolution transmission electron microscopy (HRTEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analyses for the composite powder sample with a composition of Al:Si:Co = 85:10:5 showed the amorphous state of the Co-doped SiO2 that modified γ-Al2O3 nanocrystalline surfaces. In situ X-ray absorption fine structure (XAFS) spectroscopic analysis suggested reversible redox reactions of Co species in the composite powder sample during heat-treatment under H2 at 500 °C followed by subsequent cooling to RT under Ar. Further analyses by in situ IR spectroscopy combined with cyclic temperature programmed reduction/desorption (TPR/TPD) measurements and X-ray photoelectron spectroscopic (XPS) analysis revealed that the alternating Co(III)/(II) redox reactions were associated with OH formation (hydrogenation)-deformation (dehydrogenation) of the amorphous aluminosilicate matrix formed in situ at the SiO2/γ-Al2O3 hetero interface, and the redox reactions were governed by the H2 partial pressure at 250–500 °C. As a result, a supported mesoporous γ-Al2O3/Co-doped amorphous SiO2/mesoporous γ-Al2O3 three-layered composite membrane exhibited an H2-triggered chemical valve property: mesopores under H2 flow (open) and micropores under He flow (closure) at 300–500 °C.
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GUO, WEI, YA-XIA YIN, HUI-JUAN YAN i YU-GUO GUO. "SYNTHESIS AND ELECTROCHEMICAL PROPERTIES OF POLY-[2, 5-DI-N-(2, 2, 6, 6-TETRAMETHYL-4-PIPERIDINE–N-OXYL) BENZAMIDE] ANILINE AS A CATHODE MATERIAL FOR LITHIUM-ION BATTERIES". Journal of Molecular and Engineering Materials 01, nr 04 (grudzień 2013): 1340019. http://dx.doi.org/10.1142/s2251237313400194.
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Novel TEMPO radical grafted PANI [polymer (3)] was synthesized from 2,5-dicarboxyaniline by two-step process, and investigated with Fourier transform infrared spectroscopy, electron spin resonance spectra, thermogravimetric analysis, scanning electron microscopy, cyclic voltammograms, and galvanostatic charge–discharge techniques. The polymer (3) shows six-electron redox reaction process in the voltage ranges of 2.0–4.0 V versus Li +/ Li . A high specific capacity of 156 mA h g−1 is obtained in the experiment, close to half of the theoretical capacity of the polymer based on six-electron redox reaction (330 mA h g−1. The polymer (3) also exhibits good rate capability and cycle life. The excellent electrochemical properties benefit from fast redox reaction of nitroxy radical and conductive polyaniline nanotubes structure.
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Apsari, Nurul. "KORELASI PEMBELAJARAN DARING TERHADAP PEMAHAMAN KONSEP REAKSI REDOKS". Bestari: Jurnal Pendidikan dan Kebudayaan 2, nr 1 (26.04.2021): 1–6. http://dx.doi.org/10.46368/bjpd.v2i1.301.
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Abstract: The research objective was to identify correlations of online learning and understanding of the concept of redox reactions. This type of research is quantitative research. The research subjects were 60 students of class X SMAN 1 Nanga Pinoh. The research instrument was a description test to determine the understanding of the concept of redox reactions and a questionnaire sheet to determine the effectiveness of online learning. The data analysis technique uses the Pearson product moment correlation. The results of the analysis showed that rcount = 0.86 9 rtable = 0.254 (5%) and 0.330 (1%). The significance value is 0.001 and the coefficient of determination is 0.96 (96%). Based on the results of the analysis, it is concluded that there is a positive correlation between online learning and understanding the concept of redox reactions. The more effective online learning is, the better your understanding of the redox reaction concept will be.Keywords: Correlation, Online Learning, Redox Reactions Abstrak : Tujuan penelitian adalah mengindentifikasi korelasi pembelajaran daring dan pemahaman konsep reaksi redoks. Jenis penelitian adalah penelitian kuantitatif. Subjek penelitian yaitu siswa kelas X SMAN 1 Nanga Pinoh sebanyak 60 orang. Instrumen penelitian yaitu tes uraian untuk mengetahui pemahaman konsep terhadap reaksi redoks dan lembar angket digunakan untuk mengetahui keefektifan pembelajaran daring. Teknik analisis data menggunakan pearson product moment corellatio. Hasil analisis diperoleh bahwa rhitung = 0,869 rtabel = 0,254 (5%) dan 0,330 (1%). Nilai signifikansi 0,001 dan nilai koefisien determinasi 0,96 (96%). Berdasarkan hasil analisis disimpulkan bahwa terdapat korelasi positif antara pembelajaran daring dengan pemahaman konsep reaksi redoks. Semakin efektif pembelajaran daring maka pemahaman konsep reaksi redoks juga akan semakin baik.Kata Kunci : Korelasi, Pembelajaran daring, Reaksi Redoks
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G.O., Dayo-Olagbende,, Ogunleye B.A i Unabor E. "EFFECT OF SOIL OXIDO-REDUCTION STATUS ON AGRONOMIC PERFORMANCE OF RICE ON TWO TEXTURALLY DIFFERENT SOILS". Tropical Agrobiodiversity 1, nr 1 (17.06.2020): 13–17. http://dx.doi.org/10.26480/trab.01.2020.13.17.
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The production of rice has its own requirements like other crops, among these requirements include the various soil reactions like acid-base reaction and redox reaction. The experient was set up to determine the effect of different oxido-reduction status of soil on rice performance. The trial was a 3x2x2 factorial experiment laid out in a completely randomized design (CRD) and replicated three times. The variables included 3 levels of organic matter from poultry source (0t/ha, 6t/ha and 8t/ha), two levels of NPK 15-15-15 fertilizers (0kg/ha and 200kg/ha) and two watering regimes (Field capacity and waterlogged) this gave rise to twelve treatments and four redox status (oxidized, moderately reduced, reduced and highly reduced). Redox potential was measured using a redox potential meter, growth parameters of rice collected included plant height measured with tape rule, number of leaves and number of tillers which were counted. Yield parameters collected includes 1000 grain weight and grain yield measured with a electrical weighing balance. Data collected were subjected to analysis of variance using SPSS version 17 and means were separated using Tukey HSD. Results from the result indicated that rice performance was best under highly reduce and moderately reduced soils.
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Banerjee, Shibdas, Shyam Sathyamoorthi, J. Du Bois i Richard N. Zare. "Mechanistic analysis of a copper-catalyzed C–H oxidative cyclization of carboxylic acids". Chemical Science 8, nr 10 (2017): 7003–8. http://dx.doi.org/10.1039/c7sc02240a.
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Experimental evidence supports a mechanism for oxidative conversion of carboxylic acids to lactones that initiates with C–H abstraction by sulfate radical anion. The reaction is found to proceed through a carbocationic intermediate with redox cycling of copper ion.
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Elen, Ken, An Hardy i Marlies K. Van Bael. "Kinetic Analysis of the Redox Reaction in an Aqueous Vanadium–Oxalate System". Journal of Chemical Education 97, nr 6 (8.05.2020): 1650–54. http://dx.doi.org/10.1021/acs.jchemed.0c00010.
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Clark, Morgan J., Jan S. Borchers, Savanah B. Van Scoy i Robbyn Kimberly Anand. "Array of Interdigitated Bipolar Electrodes for the Selective Capture and Analysis of Melanoma Cells". ECS Meeting Abstracts MA2022-01, nr 53 (7.07.2022): 2225. http://dx.doi.org/10.1149/ma2022-01532225mtgabs.
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In this work, we develop an array of biosensors for the selective dielectrophoretic capture and electrochemical detection of single to few melanoma cells. Each biosensor in the array consists of a gold thin film interdigitated bipolar electrode (IDBPE) patterned on a glass substrate. Microwells are patterned over the interdigitated end of each IDBPE to restrict the number of cells captured and to retain cells on the electrodes for subsequent analysis. An overlying microfluidic channel controls delivery of the cell sample to the microwells. Cells are attracted to the interdigitated electrode by a positive dielectrophoretic force, thereby pulling them into the microwells, where they remain trapped during the next step – introduction of reagents for electrochemical enzyme-linked immunosorbent assay (eELISA). The dimensions of the wells, solution flow rate, and AC voltage applied all support the retention of the cells on the electrodes once they are captured. A bipolar electrode (BPE) is a conductor, which in the presence of an externally applied electric field, facilitates electrically coupled faradaic reactions at its opposing ends. In the context of analysis, a sensing reaction at one pole of the BPE is coupled to a reporting reaction, which produces a visual signal at the opposite pole. Because of their wireless operation, arrays of tens to thousands of BPEs can be operated in parallel with a single power supply – an advantageous feature for parallel analysis of few or single cells. However, traditional BPEs with electrogenerated chemiluminescence (ECL) as the reporting reaction do not provide sufficient sensitivity for biologically relevant detection limits, and therefore, require a means of signal amplification for such applications. To address this issue, we previously developed IDBPEs, which facilitate redox cycling by interdigitation of the sensing pole of each BPE of an array with a shared driving electrode, thereby yielding more intense ECL at the reporting pole.1 In the present study, the interdigitated end of the IDBPE is utilized for eELISA to quantify the expression of a cell surface antigen, melanoma cell adhesion marker (MCAM). Cells are labelled with biotinylated anti-human MCAM and alkaline phosphatase (ALP) conjugated streptavidin. Once cells are captured, the redox inactive substrate, para-aminophenyl phosphate (PAPP), is flowed through the microchannels and ALP catalyzes its conversion to the redox active species para-aminophenol (PAP). The amplified current obtained at each IDBPE by the redox cycling of PAP and its oxidized form, quinone imine (QI), is reported by an ECL reaction on its opposing pole. The ECL signal obtained at each IDBPE is correlated to the expression level of MCAM on the melanoma cells isolated in the corresponding well. This work is significant because it allows for the sensitive detection of melanoma cells in a device amenable to point-of-care application by combining selective enrichment of malignant cells by dielectrophoresis with the amplification and facile arraying afforded by IDBPEs. Borchers, J.S., Campbell, C.R., Van Scoy, S.B., Clark, M.J. and Anand, R.K. (2021), Redox Cycling at an Array of Interdigitated Bipolar Electrodes for Enhanced Sensitivity in Biosensing. ChemElectroChem. https://doi.org/10.1002/celc.202100523
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Sonderegger, Marco, Marie Jeppsson, Bärbel Hahn-Hägerdal i Uwe Sauer. "Molecular Basis for Anaerobic Growth of Saccharomyces cerevisiae on Xylose, Investigated by Global Gene Expression and Metabolic Flux Analysis". Applied and Environmental Microbiology 70, nr 4 (kwiecień 2004): 2307–17. http://dx.doi.org/10.1128/aem.70.4.2307-2317.2004.
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ABSTRACT Yeast xylose metabolism is generally considered to be restricted to respirative conditions because the two-step oxidoreductase reactions from xylose to xylulose impose an anaerobic redox imbalance. We have recently developed, however, a Saccharomyces cerevisiae strain that is at present the only known yeast capable of anaerobic growth on xylose alone. Using transcriptome analysis of aerobic chemostat cultures grown on xylose-glucose mixtures and xylose alone, as well as a combination of global gene expression and metabolic flux analysis of anaerobic chemostat cultures grown on xylose-glucose mixtures, we identified the distinguishing characteristics of this unique phenotype. First, the transcript levels and metabolic fluxes throughout central carbon metabolism were significantly higher than those in the parent strain, and they were most pronounced in the xylose-specific, pentose phosphate, and glycerol pathways. Second, differential expression of many genes involved in redox metabolism indicates that increased cytosolic NADPH formation and NADH consumption enable a higher flux through the two-step oxidoreductase reaction of xylose to xylulose in the mutant. Redox balancing is apparently still a problem in this strain, since anaerobic growth on xylose could be improved further by providing acetoin as an external NADH sink. This improved growth was accompanied by an increased ATP production rate and was not accompanied by higher rates of xylose uptake or cytosolic NADPH production. We concluded that anaerobic growth of the yeast on xylose is ultimately limited by the rate of ATP production and not by the redox balance per se, although the redox imbalance, in turn, limits ATP production.
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Avdeenko, A. P., S. A. Konovalova i I. Yu Yakymenko. "Synthesis of N-[3-(2,3-dimethyl-1H-indol-1-yl)-4-hydroxyphenyl]arylsulfon(aroyl)amides". Voprosy Khimii i Khimicheskoi Tekhnologii, nr 6 (grudzień 2020): 20–25. http://dx.doi.org/10.32434/0321-4095-2020-133-6-20-25.
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Indole derivatives are an essential elements of many natural and synthetic compounds having significant biological activity. New derivatives of 2,3-dimethylindole were synthesized in this work by the reaction of N-(4-oxocyclohexa-2,5-dien-1-ylidene)arylsulfon(aroyl)amides and 4-methyl-N-(4-oxonaphthalen-1(4H)-ylidene)benzene-1-sulfonamide with 2,3-dimethylindole. The possibility of these reactions is determined by the redox potential of the starting amides and steric factor. If there is a free C=C bond in the quinoid ring of the starting arylsulfonamides, the reaction proceeds under the 1,4-addition scheme with the formation of corresponding N-[3-(2,3-dimethyl-1H-indol-1-yl)-4-hydroxyphenyl(naphthyl-1)]arylsulfonamides which are potentially biologically active compounds. N-(4-Oxocyclohexa-2,5-diene-1-ylidene)aroylamides have a high redox potential as compared with similar arylsulfonamides and naphthalene derivatives; therefore, two processes proceed in their reaction with 2,3-dimethylindole: reduction and 1,4-addition. The 1,4-addition product was obtained only for the 2,3-dimethyl derivative, which has the lowest redox potential among the investigated aroylamides. Analysis of the potential biological activity of the synthesized compounds by using the PASS program showed that the synthesized products can exhibit the following activities: para amino benzoic acid antagonist, glutamyl endopeptidase II inhibitor, CYP3A2 substrate, insulysin inhibitor, membrane integrity agonist and phobic disorders treatment.
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Limpanuparb, Taweetham, Pakpong Roongruangsree i Cherprang Areekul. "A DFT investigation of the blue bottle experiment: E ∘ half-cell analysis of autoxidation catalysed by redox indicators". Royal Society Open Science 4, nr 11 (listopad 2017): 170708. http://dx.doi.org/10.1098/rsos.170708.
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The blue bottle experiment is a collective term for autoxidation reactions catalysed by redox indicators. The reactions are characterized by their repeatable cycle of colour changes when shaken/left to stand and intricate chemical pattern formation. The blue bottle experiment is studied based on calculated solution-phase half-cell reduction potential of related reactions. Our investigation confirms that the reaction in various versions of the blue bottle experiment published to date is mainly the oxidation of an acyloin to a 1,2-dicarbonyl structure. In the light of the calculations, we also propose new non-acyloin reducing agents for the experiment. These results can help guide future experimental studies on the blue bottle experiment.
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Volikov, Alexander, Nikita Mareev, Andrey Konstantinov, Alexandra Molodykh, Sofia Melnikova, Alina Bazhanova, Mikhail Gasanov i in. "Directed Synthesis of Humic and Fulvic Derivatives with Enhanced Antioxidant Properties". Agronomy 11, nr 10 (12.10.2021): 2047. http://dx.doi.org/10.3390/agronomy11102047.
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Redox moieties, which are present in the molecular backbone of humic substances (HS), govern their antioxidant properties. We hypothesized that a directed modification of the humic backbone via incorporation of redox moieties with known redox properties might provide an efficient tool for tuning up antioxidant properties of HS. In this work, hydroquinonoid and hydronaphthoquinonoid centres were used, which possess very different redox characteristics. They were incorporated into the structure of coal (leonardite) humic acids CHA) and peat fulvic acids (PFA). For this goal, an oxidative copolymerization of phenols was used. The latter was induced via oxidation of hydroquinones and hydroxynapjtaquinones with a use of Fenton’s reagent. The structure of the obtained products was characterized using NMR and FTIR spectroscopy. H/D labelling coupled to FT ICR mass spectrometry analysis was applied for identification of the reaction products as a tool for surmising on reaction mechanism. It was shown that covalent -C-C- bond were formed between the incorporated redox centers and aromatic core of HS. The parent humic acids and their naphthoquinonoid derivatives have demonstrated high accepting capacity. At the same time, fulvic acids and their hydroquinonoid derivatives have possessed both high donor and high antioxidant capacities. The kinetic studies have demonstrated that both humic acids and their derivatives showed much slower kinetics of antioxidant reactions as compared to fulvic acids. The obtained results show, firstly, substantial difference in redox and antioxidant properties of the humic and fulvic acids, and, secondly, they can serve as an experimental evidence that directed chemical modification of humic substances can be used to tune and control antioxidant properties of natural HS.
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Triyanto, Gatot, Ricky R. Saputro, Chepi Reynaldir, Khoirudin Khoirudin i Sukarman Sukarman. "Analysis Redox Reaction on Zinc-Coating Thickness Test in Metal Processing Industry of Small and Medium Enterprises". Jurnal Akademika Kimia 11, nr 1 (28.02.2022): 19–25. http://dx.doi.org/10.22487/j24775185.2022.v11.i1.pp19-25.
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This study discusses the implementation of redox reactions on the thickness test of the galvanized (zinc-coated) layer using the JIS-H-0401 standard to help Small and Medium Enterprises (SMEs) industries. Some of the finished products go through the galvanizing process in the metal processing industry. Quality constraints, especially related to the thickness of the galvanic (zinc-coated) layer, have become an object that is less controlled because of the limitations of the test equipment used. This research uses an experimental method applied to one of its products: a flat washer with SPCC material and a thickness of about 2.20 mm. SPCC - SD material is classified as low carbon steel based on its carbon content. 5-unit flat washers were identified with sample codes A, B, C, D, and E. Flat washers have an internal diameter of 22.65 - 22.7 mm. In comparison, the outer diameter is between 43.75 - 43.80. The redox reaction process uses HCl (hydrochloric acid) with a concentration of 1 M, which is diluted with water (H2O). The zinc thickness test results show that the flat washer has an average thickness of 10.52 microns with a minimum and maximum thickness variation of 10.66 -10.72 microns.
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Azizah*, Dewiantika, Mutiara Dwi Cahyani i Dewi Nurdiyanti. "The Implementation of Student Worksheets with Scientific Approach on Reduction Oxidation Reaction Matter to Students’ Cognitive Learning Outcome". Jurnal Pendidikan Sains Indonesia 10, nr 1 (19.01.2022): 1–10. http://dx.doi.org/10.24815/jpsi.v10i1.20349.
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Redox reaction matter which seems to be abstract makes students of X science grade difficult to understand the concept. Therefore, student-centered learning using teaching matter which has analyzed students’ character or as known as scientific-based approach LKPD is necessary. This research aimed to identify the students’ cognitive results after learning redox reaction matter using a scientific-based approach LKPD. The research was done at SMAN 1 Dukupuntang, Cirebon in the 2016-2017 school year using pre-experimental method with one-shot case study research design. The sample was students of X science 2 grade. The data collection was done via a questionnaire. The analysis technique was quantifying the result percentage before and after using LKPD. This research served LKPD data which involved learning activities such as (a) observing, (b) asking, (c) collecting the data, (d) associating, and (e) communicating whichstimulatedstudents to learn redox reaction matter actively. The pretest result showed that the students’ completeness percentage was 66,67% while the protest result using LKPD showed that the percentage increased to be 86,67%. The conclusion was using a scientific-based approach LKPD on redox reaction matter was successful to enhance students’ cognitive learning outcomes and fulfill the minimum completeness criteria (KKM)
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Dvořák, Dalimil, Miloš Buděšínský, David Šaman i Zdeněk Arnold. "Benzylidenemalonaldehydes: A redox reaction during the attempted cycloaddition on nitrosobenzene". Collection of Czechoslovak Chemical Communications 50, nr 10 (1985): 2260–64. http://dx.doi.org/10.1135/cccc19852260.
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Reaction of p-chlorobenzylidenemalonaldehyde with nitrosobenzene represents a reduction-oxidation process leading to 2-formyl-3-anilino-3-(4-chlorophenyl)acrylic acid (III). The structure of the product, including two intramolecular hydrogen bonds, has been proved by analysis of the 1H and 13C NMR spectra of the acid III, its deuterated form and the methyl ester obtained by reaction with diazomethane.
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Kim, Nayeong, i Xiao Su. "Redox-Mediated Electrodialysis for Resource Recovery and Energy-Efficient Desalination". ECS Meeting Abstracts MA2022-02, nr 27 (9.10.2022): 1057. http://dx.doi.org/10.1149/ma2022-02271057mtgabs.
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In the chemical and biochemical manufacturing industry, separation processes are amongst the most energy-demanding processes. Electrochemical separations have been growing in interest as promising candidates for both downstream processing for resource recovery and producing clean water due to their energy-efficient, environmentally benign, and modular features.1 Leveraging a sustainable redox reaction, we developed a redox-mediated electrodialysis system for energy-efficient desalination coupled with resource recovery of valuable resources such as lithium, and even biomolecules.2, 3 Our proposed redox-mediated electrodialysis system utilizes a reversible redox reaction as a driving force of salt removal at a much lower voltage than a water-splitting reaction (>1.2 V). As the redox materials are reduced or oxidized, all charged species migrate across the membranes to balance the charge in the electrolyte compartment. As the redox materials circulate in the cathode and anode compartments, they sustainably regenerated without additional regeneration steps, one of the major bottlenecks for industrializing the electrosorption system. We demonstrated the redox-mediated electrochemical system for resource recoveries such as simultaneous lithium recovery from brine3 and valorization of whey proteins and lactose from whey waste.2 Especially for the valorization of whey waste, our system treated 99% of salt from the whey solution within a single step and recovered > 98% of various whey proteins (e.g., valuable protein contents such as beta-lactoglobulin, alpha-lactalbumin, and lactose). The preliminary techno-economic analysis confirmed the economic potential of redox-mediated ED with 51−73% lower energy consumption compared to conventional ED. Overall. we envision the system can become a breakthrough in tackling the environmental challenges coupled with the limited resources. Kim, N.; Jeon, J.; Chen, R.; Su, X., Electrochemical separation of organic acids and proteins for food and biomanufacturing. Chemical Engineering Research and Design 2022, 178, 267-288. Kim, N.; Jeon, J.; Elbert, J.; Kim, C.; Su, X., Redox-mediated electrochemical desalination for waste valorization in dairy production. Chemical Engineering Journal 2022, 428, 131082. Kim, N.; Su, X.; Kim, C., Electrochemical lithium recovery system through the simultaneous lithium enrichment via sustainable redox reaction. Chemical Engineering Journal 2021, 420, 127715.
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Sourav, Sagar, i Israel E. Wachs. "Cr-Free, Cu Promoted Fe Oxide-Based Catalysts for High-Temperature Water-Gas Shift (HT-WGS) Reaction". Catalysts 10, nr 3 (6.03.2020): 305. http://dx.doi.org/10.3390/catal10030305.
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Ca, Ni, Co, and Ge promoters were examined as potential candidates to substitute for the current toxic Cr in Cu-promoted Fe oxide-based catalysts for the HT-WGS reaction. The Ca and Ni promoters were found to improve catalyst performance relative to promotion with Cr. The HS-LEIS surface analysis data demonstrate that Ca and Ge tend to segregate on the surface, while Ni, Co, and Cr form solid solutions in the Fe3O4 bulk lattice. The corresponding number of catalytic active sites, redox, and WGS activity values of the catalysts were determined with CO-TPR, CO+H2O-TPSR, and SS-WGS studies, respectively. The poorer HT-WGS performances of the Ge and Co promoters are related to the presence of surface Ge and Co that inhibits catalyst redox ability, with the Co also not stabilizing the surface area of the Fe3O4 support. The Ni promoter uniformly disperses the Cu nanoparticles on the catalyst surface and increases the number of FeOx-Cu interfacial redox sites. The Ca promoter on the catalyst surface, however, enhances the activity of the FeOx-Cu interfacial redox sites. The CO+H2O TPSR results reveal that the redox ability of the active sites follows the SS-WGS performance of the catalysts and show the following trend: 3Cu8CaFe > 3Cu8NiFe ≥ 3Cu8CrFe > 3Cu8CoFe >> 3Cu8GeFe. Furthermore, all the catalysts followed a redox-type reaction mechanism for the HT-WGS reaction.
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Sugiharti*, Gulmah, i Wan Azura. "Learning Model And Logical Thinking Ability in Redox Reaction Learning". Jurnal Pendidikan Sains Indonesia 9, nr 4 (15.10.2021): 590–601. http://dx.doi.org/10.24815/jpsi.v9i4.20076.
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The implementation of the 2013 curriculum has not been fully implemented in Private High School Angkasa Medan , because teachers do not fully understand the learning model that must be used. This has an impact on the results of student chemistry learning that not all students are able to achieve the set minimum completeness score target of 75. This study is about the application of learning models and the ability to think logically in redox learning in class X Private High School Angkasa Medan. The population consisted of 6 class X students and the sample was taken purposively by setting 2 classes for the research sample. Both classes are taught with two models, with a combination of factorial 2 X 2. There are two factors tested, namely factor A in the form of a learning model consisting of Problem Based Learning (PBL) and Direct Instruction (DI) models, factor B: logical thinking ability high and low logical thinking ability. Data analysis techniques using 2-way ANOVA. Based on the hypothesis test at a significant level of α = 0.05, it shows that there is an influence of the learning model and students' logical thinking ability on the learning outcomes of topic redox chemistry, and there is an interaction between the learning model and the ability to think logically towards the redox learning outcomes. The results of the BNT advanced test indicate that the Problem Based Learning Model is better than the Direct Instruction model on topic redox chemistry learning.
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Xian, Haiyu, Lin Li, Yilei Ding, Mingjing Chu i Changqing Ye. "Preparation and Orthogonal Analysis for Dual-Responsive Electrochromic Polymer Dispersed Liquid Crystal Devices". Polymers 15, nr 8 (13.04.2023): 1860. http://dx.doi.org/10.3390/polym15081860.
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In this work, we provide a fabrication method for dual-responsive electrochromic (EC) polymer dispersed liquid crystal (PDLC) devices. The EC PDLC device was developed by combing the PDLC technique and a colored complex formed via a redox reaction without a specific EC molecule in a simple preparation method. The mesogen played dual roles in the device for scattering in the form of microdroplets and participating in the redox reactions. Orthogonal experiments were performed with the acrylate monomer concentration, the ionic salt concentration, and the cell thickness as factors to investigate the electro-optical performance for the achievement of optimized fabrication conditions. The optimized device presented four switchable states modulated by external electric fields. The light transmittance of the device was changed by an alternative current (AC) electric field while the color change was realized by a direct current (DC) electric field. Variations of mesogen and ionic salt species can modulate the color and hue of devices, which solves the disadvantage of a single color for traditional EC devices. This work lays the foundation for realizing patterned multi-colored patterned displays and anti-counterfeiting via screen printing and inkjet printing techniques.
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Le Gal, Alex, Marielle Vallès, Anne Julbe i Stéphane Abanades. "Thermochemical Properties of High Entropy Oxides Used as Redox-Active Materials in Two-Step Solar Fuel Production Cycles". Catalysts 12, nr 10 (26.09.2022): 1116. http://dx.doi.org/10.3390/catal12101116.
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The main challenges and obstacles to the development of hydrogen/carbon monoxide production from the splitting of water/carbon dioxide through two-step solar thermochemical cycles are strongly related to material concerns. Indeed, ceria is the main benchmark redox material used in such processes because it provides very good oxidation reaction kinetics, reactions reversibility and thermal cycling stability. This is at the expense of a low reduction yield (non-stoichiometry δ in CeO2-δ) at relatively high temperatures (≥1400 °C), which requires operation at low oxygen partial pressures during the reduction step. Hence, the specific fuel output per mass of redox material, i.e., the amount of H2/CO produced per cycle, remains low, thereby limiting the overall solar-to-fuel conversion efficiency. Perovskites offer larger amounts of fuel produced per cycle but the reaction kinetics are slow. This study addresses the thermochemical investigation of a new class of metal oxides, namely high entropy oxides (HEOs), with the aim of improving the specific amount of fuel generated per cycle with good kinetic rates. Different formulations of high entropy oxides were investigated and compared using thermogravimetric analysis to evaluate their redox activity and ability to split CO2 during thermochemical cycles. Among the different formulations tested, five HEOs yielded CO with a maximum specific fuel output of 154 µmol/g per cycle. These materials’ performances exceeded the production yields of ceria under similar conditions but are still far from the production yields reached with lanthanum–manganese perovskites. This new class of materials, however, opens a wide path for research into new formulations of redox-active catalysts comparing favorably with the ceria redox performance for solar thermochemical synthetic fuel production.
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Ma, Shanshan, i Qing Huang. "A SERS study of oxidation of glutathione under plasma irradiation". RSC Advances 5, nr 71 (2015): 57847–52. http://dx.doi.org/10.1039/c5ra07440a.
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This paper reports a new application of surface enhanced Raman scattering (SERS) in analysis of oxidation of glutathione to oxidized glutathione, an important biochemical redox reaction in biological systems.
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McGlashan, N. R. "Chemical-looping combustion — a thermodynamic study". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, nr 6 (1.06.2008): 1005–19. http://dx.doi.org/10.1243/09544062jmes790.
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The poor performance of internal combustion (IC) engines can be attributed to the departure from equilibrium in the combustion process. This departure is expressed numerically, as the difference between the working fluid's temperature and an ideal ‘combustion temperature’, calculated using a simple expression. It is shown that for combustion of hydrocarbons to be performed reversibly in a single reaction, impractically high working fluid temperatures are required — typically at least 3500 K. Chemical-looping combustion (CLC) is an alternative to traditional, single-stage combustion that performs the oxidation of fuels using two reactions, in separate vessels: the oxidizer and reducer. An additional species circulates between the oxidizer and reducer carrying oxygen atoms. Careful selection of this oxygen carrier can reduce the equilibrium temperature of the two redox reactions to below current metallurgical limits. Consequently, using CLC it is theoretically possible to approach a reversible IC engine without resorting to impractical temperatures. CLC also lends itself to carbon capture, as at no point is N2 from the air allowed to mix with the CO2 produced in the reduction process and therefore a post-combustion scrubbing plant is not required. Two thermodynamic criteria for selecting the oxygen carrier are established: the equilibrium temperature of both redox reactions should lie below present metallurgical limits. Equally, both reactions must be sufficiently hot to ensure that their reaction velocity is high. The key parameter determining the two reaction temperatures is the change in standard state entropy for each reaction. An analysis is conducted for an irreversible CLC system using two Rankine cycles to produce shaft work, giving an overall efficiency of 86.5 per cent. The analysis allows for irreversibilites in turbine, boiler, and condensers, but assumes reactions take place at equilibrium. However, using Rankine cycles in a CLC system is considered impractical because of the need for high-temperature, indirect heat exchange. An alternative arrangement, avoiding indirect heat exchange, is discussed briefly.
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Arava, Leela. "(Invited, Digital Presentation) Fundamental Understanding and Challenges in Cathode Materials for Next Generation Li-Ion Batteries". ECS Meeting Abstracts MA2022-01, nr 38 (7.07.2022): 1658. http://dx.doi.org/10.1149/ma2022-01381658mtgabs.
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Introducing high-performance Li-ion batteries in current energy storage technologies has great hope in achieving decarbonization goals for sustainable future. The impact of Li-ion batteries in current energy sector is huge, especially portable electronics to electric vehicles. With this energy demand, recently, researchers have been exploring the so-called “Li-rich anion redox” cathode chemistry, in which electrons stored on oxide anions are reversibly utilized during redox reaction along with conventional transition metal redox to obtain high energy storage capability.1-2 Compared to conventional cathodes, the anion redox cathode chemistry is not straightforward as it goes through a complex redox reaction pathway, leading to fundamental issues such as voltage fade, voltage hysteresis and irreversible oxygen release. However, these anionic redox reactions in transition metal oxide-based cathodes attained by extracting excess lithium ions have resulted in stability issues due to weak metal (M) – oxygen(O) ligand covalency.1 In order to increase the tightness between metal–ligand, an alternative strategy was investigated by replacing M–O framework with M–X (X- S, Se) ligands. Based on the experimental studies, it is found that the metal-ligand tunability is the key to achieve highly reversible chalcogen anion redox reactions in various Li based chalcogen cathode materials.3 Further, the lithiation delithiation reactions of cathodes are investigated using in-depth electrochemical analysis and the electronic as well as structural changes during electrochemical reactions are understood using detailed spectroscopy and microscopy characterization. Findings from this research will inspire Ni and Co free chalcogen cathode design and various functional materials in the pursuit of next-generation cathode materials. In parallel, this presentation will also focus on fundamental understanding and importance of fabricating rechargeable high-temperature Li-ion batteries for various demanding applications such as military applications, sensor applications, oil and gas industry drilling applications. In this work, high temperature compatible electrode materials are identified, and their electrode/electrolyte interfacial stability issues at different depth levels are understood using energy tunable X-ray photon electron spectroscopy and further visualized with advanced microscopy imaging. This proof-of-concept study will lead to a new paradigm for transforming ambient temperature Li-ion battery technology to high-temperature applications. References: Assat, G.; Tarascon, J.-M., Fundamental understanding and practical challenges of anionic redox activity in Li-ion batteries. Nature Energy 2018, 3 (5), 373-386. Croy, J. R.; Balasubramanian, M.; Gallagher, K. G.; Burrell, A. K., Review of the US Department of Energy’s “Deep Dive” effort to understand voltage fade in Li-and Mn-rich cathodes. Accounts of chemical research 2015, 48 (11), 2813-2821. Nagarajan, S.; Hwang, S.; Balasubramanian, M.; Thangavel, N. K.; Arava, L. M. R., Mixed Cationic and Anionic Redox in Ni and Co Free Chalcogen-Based Cathode Chemistry for Li-Ion Batteries. Journal of the American Chemical Society 2021, 143 (38), 15732-15744.
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Hu, Chang Sheng, Jun Zhang, Hong Fei Yan i Jin Xin He. "Thermodynamic Analysis of a Brown Glass Containing Fe, C and S". Advanced Materials Research 591-593 (listopad 2012): 973–76. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.973.
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The ground state geometrical of cyclic sulfur molecules S8 has been studied with RHF/6-311G* of ab initio methods. Gibbs free energy of CO, SO2, S8 and CO2 from 300 to 1673K has been calculated using ab initio method. Besides, the reaction free enthalpies were calculated. The results show that resultants of reaction of CO and SO2 are S8 and CO2 below 1451K and the reaction is spontaneous.Fe2O3 in glass can is reduced into FeO whose redox number is negative. The Gibbs free energy of FeO is smaller than that of FeS while chemical stability of FeO is higher than that of FeS. Structures of cycle sulfur are versatile. Bond energy of S8, S12 and S18 is broken, which need high energy. When small sulfur ring molecules be formed, the chemical and heat stability of S8 are improved.
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Morisako, Shogo, Kohsuke Noro i Takahiro Sasamori. "Facile Synthesis and Redox Behavior of an Overcrowded Spirogermabifluorene". Inorganics 9, nr 10 (6.10.2021): 75. http://dx.doi.org/10.3390/inorganics9100075.
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A spirogermabifluorene that bears sterically demanding 3,3′,5,5′-tetra(t-butyl)-2,2′-biphenylene groups (1) was obtained from the reaction of in-situ-generated 2,2′-dilithiobiphenylene with GeCl2·(dioxane). The solid-state structure and the redox behavior of 1 were examined by single-crystal X-ray diffraction analysis and electrochemical measurements, respectively. The sterically hindered biphenyl ligands endow 1 with high redox stability and increased electron affinity. The experimental observations were corroborated by theoretical DFT calculations.
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Baronas, R., F. Ivanauskas, J. Kulys, M. Sapagovas i A. Survila. "The Influence of the Diffusion Space Geometry on Behavior of some Processes in Biochemistry and Electrochemistry". Nonlinear Analysis: Modelling and Control 5 (5.12.2000): 3–38. http://dx.doi.org/10.15388/na.2000.5.0.15238.
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The reaction-diffusion and diffusion equations were applied for modelling of some processes in biochemistry and electrochemistry. Modelling of the amperometric biosensors based on carbon paste electrodes encrusted with a single nonhomogeneous microreactor is analyzed. The mathematical model of the biosensor operation is based on nonstationary reaction-diffusion equations containing a non-linear term given by Michaelis-Menten function. Modelling of a simple redox-electrode reaction, involving two soluble species, is also considered. The model of the electrode behavior, taking into account the resist layer of the partially blocked electrodes, was expressed as a system of differential equations of the diffusion type with initial and boundary conditions. The mathematical model generalizing both processes: biochemical and electrochemical is presented in this paper. The generalized problem was solved numerically. The finite-difference technique was used for discretisation of the model. Using the numerical solution of the generalized problem, the influence of the size, shape and position of a microreactor as well as the thickness of the resist layer on the current dynamics was investigated.
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Song, Zilong, Chengwu Fan, Jintao Zhao, Lei Wang, Dongzhu Duan, Tong Shen i Xinming Li. "Fluorescent Probes for Mammalian Thioredoxin Reductase: Mechanistic Analysis, Construction Strategies, and Future Perspectives". Biosensors 13, nr 8 (13.08.2023): 811. http://dx.doi.org/10.3390/bios13080811.
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The modulation of numerous signaling pathways is orchestrated by redox regulation of cellular environments. Maintaining dynamic redox homeostasis is of utmost importance for human health, given the common occurrence of altered redox status in various pathological conditions. The cardinal component of the thioredoxin system, mammalian thioredoxin reductase (TrxR) plays a vital role in supporting various physiological functions; however, its malfunction, disrupting redox balance, is intimately associated with the pathogenesis of multiple diseases. Accordingly, the dynamic monitoring of TrxR of live organisms represents a powerful direction to facilitate the comprehensive understanding and exploration of the profound significance of redox biology in cellular processes. A number of classic assays have been developed for the determination of TrxR activity in biological samples, yet their application is constrained when exploring the real-time dynamics of TrxR activity in live organisms. Fluorescent probes offer several advantages for in situ imaging and the quantification of biological targets, such as non-destructiveness, real-time analysis, and high spatiotemporal resolution. These benefits facilitate the transition from a poise to a flux understanding of cellular targets, further advancing scientific studies in related fields. This review aims to introduce the progress in the development and application of TrxR fluorescent probes in the past years, and it mainly focuses on analyzing their reaction mechanisms, construction strategies, and potential drawbacks. Finally, this study discusses the critical challenges and issues encountered during the development of selective TrxR probes and proposes future directions for their advancement. We anticipate the comprehensive analysis of the present TrxR probes will offer some glitters of enlightenment, and we also expect that this review may shed light on the design and development of novel TrxR probes.
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Arai, T., K. Shinozuka i H. Sawai. "The kinetic analysis of the redox reaction of the simplified bleomycin model Fe-complex". Journal of Inorganic Biochemistry 67, nr 1-4 (lipiec 1997): 328. http://dx.doi.org/10.1016/s0162-0134(97)80197-3.
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Chen, Wei, Jie-Jie Chen, Rui Lu, Chen Qian, Wen-Wei Li i Han-Qing Yu. "Redox reaction characteristics of riboflavin: A fluorescence spectroelectrochemical analysis and density functional theory calculation". Bioelectrochemistry 98 (sierpień 2014): 103–8. http://dx.doi.org/10.1016/j.bioelechem.2014.03.010.
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Lovrić, Milivoj, Marina Zelić i Šebojka Komorsky-Lovrić. "Theoretical Analysis of Pulse and Differential Pulse Polarography of Reversible Redox Reaction Complicated by Reactant Adsorption". Collection of Czechoslovak Chemical Communications 66, nr 3 (2001): 423–33. http://dx.doi.org/10.1135/cccc20010423.
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Pulse and differential pulse polarograms of redox reactions complicated by reactant adsorption with and without lateral attractions in the monolayer are analysed theoretically by using a stationary spherical diffusion model. The continuous shift of the post-peak potential to lower values and the decrease in its half-peak width with increasing bulk concentration of reactant indicate attractions between adsorbed ions or molecules.
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Ellison, Eric T., Lisa E. Mayhew, Hannah M. Miller i Alexis S. Templeton. "Quantitative microscale Fe redox imaging by multiple energy X-ray fluorescence mapping at the Fe K pre-edge peak". American Mineralogist 105, nr 12 (1.12.2020): 1812–29. http://dx.doi.org/10.2138/am-2020-7359.
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Abstract Fe oxidation/reduction reactions play a fundamental role in a wide variety of geological processes. In natural materials, Fe redox state commonly varies across small spatial scales at reaction interfaces, yet the approaches available for quantitatively mapping the Fe redox state at the microscale are limited. We have designed an optimized synchrotron-based X-ray spectroscopic approach that allows microscale quantitative mapping of Fe valence state by extending the Fe XANES pre-edge technique. An area of interest is mapped at nine energies between 7109–7118 eV and at 7200 eV, allowing reconstruction, baseline subtraction, and integration of the pre-edge feature to determine Fe(III)/ΣFe with 2 μm spatial resolution. By combining the Fe redox mapping approach with hyperspectral Raman mineralogy mapping, the Fe oxidation state distributions of the major mineral phases are revealed. In this work, the method is applied to a partially serpentinized peridotite with various Fe-bearing secondary mineral phases to trace the Fe transformations and redox changes that occurred during its alteration. Analysis with the Fe redox mapping technique revealed that the peridotite contained relict olivine with abundant Fe(II), while serpentine, pyroaurite, and another hydroxide phase are secondary mineral reservoirs of Fe(III). Although serpentine is not Fe-rich, it contained approximately 74% ± 14% Fe(III)/ΣFe. These analytical results are integral to interpreting the sequence of alteration reactions; serpentinization of primary olivine formed Fe(II)-rich brucite and oxidized serpentine, which could have contributed to H2 production during serpentinization. Subsequent weathering by oxidizing, CO2-bearing fluids led to the partial carbonation and oxidation of brucite, forming pyroaurite and a hydroxide phase containing dominantly Fe(III). This Fe redox imaging approach is applicable to standard petrographic thin sections or grain mounts and can be applied to various geologic and biogeochemical systems.
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Sultana, Tahmina, Chowdhury A. Waheed, SM Saiful Islam, Abu Ali Ibn Sina, Muhammad Younus, Md Abdul Jabbar i Md Riad Hossain Sabuj. "Synthesis, characterization and Electrochemical studies of Ferrocenyl-2, 4-Dinitrophenylhydrazone". Journal of Bangladesh Academy of Sciences 38, nr 2 (28.12.2014): 177–87. http://dx.doi.org/10.3329/jbas.v38i2.21342.
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A ferrocenyl imine complex, Fc-C(CH3)=N-NH-C6H3-2,4-(NO2)2 (Fc = ferrocenyl) has been synthesized by the condensation reaction between acetylferrocene and 2,4-dinitrophenyl hydrazine. The compound was synthesised previously, and characterized by IR, 1H and elemental analysis. It was further characterized by 13C {1H} NMR spectroscopy and mass spectrometry. The redox property of the complex was studied by cyclic voltammetry, differential pulse voltammetry and chronocoulometry. The redox process of the complex was found to be reversible at a platinum-disc electrode, and the redox potential of the imine complex was shifted to more anodic position with respect to ferrocene. The redox reactivity of the complex was enhanced in the presence of oxygen. DOI: http://dx.doi.org/10.3329/jbas.v38i2.21342 Journal of Bangladesh Academy of Sciences, Vol. 38, No. 2, 177-187, 2014
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Li, Xiaodong, Ailing Feng, Yanqing Zu, Peitao Liu i Fengbo Han. "Experimental and Theoretical Study on Crown Ether-Appended-Fe(III) Porphyrin Complexes and Catalytic Oxidation Cyclohexene with O2". Molecules 28, nr 8 (13.04.2023): 3452. http://dx.doi.org/10.3390/molecules28083452.
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Modifying non-precious metal porphyrins at the meso-position is sufficient to further improve the ability to activate O2 and the selectivity of the corresponding redox products. In this study, a crown ether-appended Fe(III) porphyrin complex (FeTC4PCl) was formed by replacing Fe(III) porphyrin (FeTPPCl) at the meso-position. The reactions of FeTPPCl and FeTC4PCl catalysed by O2 oxidation of cyclohexene under different conditions were studied, and three main products, 2-cyclohexen-1-ol (1), 2-cyclohexen-1-one (2), and 7-oxabicyclo[4.1.0]heptane (3), were obtained. The effects of reaction temperature, reaction time, and the addition of axial coordination compounds on the reactions were investigated. The conversion of cyclohexene reached 94% at 70 °C after 12 h, and the selectivity toward product 1 was 73%. The geometrical structure optimization, molecular orbital energy level analysis, atomic charge, spin density, and density of orbital states analysis of FeTPPCl, FeTC4PCl, as well as the oxygenated complexes (Fe-O2)TCPPCl and (Fe-O2)TC4PCl formed after adsorption of O2, were carried out using the DFT method. The results of thermodynamic quantity variation with reaction temperature and Gibbs free energy variation were also analysed. Finally, based on experimental and theoretical analysis, the mechanism of the cyclohexene oxidation reaction with FeTC4PCl as a catalyst and O2 as an oxidant was deduced, and the reaction mechanism was obtained as a free radical chain reaction process.
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Schilling, Monja, Michael Braig, Kerstin Köble i Roswitha Zeis. "Investigating Electrode Reactions in Vanadium Redox Flow Batteries - a Distribution of Relaxation Times Analysis". ECS Meeting Abstracts MA2022-01, nr 48 (7.07.2022): 2012. http://dx.doi.org/10.1149/ma2022-01482012mtgabs.
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Due to the increasing energy demand worldwide and the urgency of action because of climate change, new energy storage devices are needed to balance the fluctuations of renewable energy sources. The Vanadium Redox Flow Battery (VRFB) is a promising technology for large-scale energy storage but still needs to overcome significant lifetime and efficiency challenges, which are decreased by polarization losses during operation. It is essential to conduct experiments in a setup that closely mimics the cell's operating conditions to analyze the ongoing processes in a VRFB. Therefore, setups reflecting a half cell are well-suited. Thus, new insights into the reaction and transport processes in a VRFB can be gained. Electrochemical Impedance Spectroscopy (EIS) combined with Distribution of Relaxation Times (DRT) analysis is a well-suited method to investigate electrode reactions. This combination of methods is frequently used in research for lithium-ion batteries or in our group for fuel cell characterization (1-3). To the best of our knowledge, there is no study using EIS and DRT analysis to analyze processes in a model half cell in VRFB research published yet, and just very few studies on characterization in full cell-like setups are available (4). Here, we present a novel 3D printed flow cell for investigations under application-oriented conditions, designed to ensure steady-state conditions during the measurements. These studies focus on the characterization of the processes in the positive half cell by EIS to deepen the knowledge about the polarization losses in VRFBs. The vanadium-containing electrolyte is continuously pumped through the cell during the experiments to guarantee consistent conditions while EIS measurements are performed. The electrolyte flows through the carbon paper stack used as electrode material, undergoing an electrochemical reaction. Here, either the oxidation of vanadium(IV) to vanadium(V) or the reduction from vanadium(V) to vanadium(IV) occurs. The recorded data were analyzed with the DRT method, which allows the separation of physicochemical processes on different time scales. Parameters like the temperature, the flow rate, the electrolyte concentration, and the electrolyte species were varied independently to identify the individual processes in the positive half cell of a VRFB. This setup enables electrochemical impedance measurements of high quality, which is essential for a reliable DRT analysis. We could assign the peaks in the DRT spectrum to the electrochemical reaction, the convective transport through the electrode structure, and the diffusion processes of the vanadium species. Thus, we could identify the individual processes in the positive half cell of the VRFB and their contributions to the overall impedance. This information is vital in search of optimized operating conditions with reduced polarization losses. 1. M. A. Danzer, Batteries, 5(3), 53 (2019). 2. A. Weiß, S. Schindler, S. Galbiati, M. A. Danzer and R. Zeis, Electrochimica Acta, 230, 391–398 (2017). 3. N. Bevilacqua, M. A. Schmid and R. Zeis, Journal of Power Sources, 471, 228469 (2020). 4. J. Schneider, T. Tichter, P. Khadke, R. Zeis and C. Roth, Electrochimica Acta, 336, 135510 (2020). Figure 1
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WAHLSTER-YOSHIDA, RUTH, TSUKASA YOSHIDA, DERCK SCHLETTWEIN, KATSUHIKO TSUKATANI, HISAO YANAGI, MASAO KANEKO i HIDEKI MINOURA. "Electrochromic redox reactions of vapour-deposited thin films of tetrapyridotetraazaporphyrinatozinc(II)". Journal of Porphyrins and Phthalocyanines 04, nr 01 (styczeń 2000): 112–22. http://dx.doi.org/10.1002/(sici)1099-1409(200001/02)4:1<112::aid-jpp210>3.0.co;2-5.
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Electrochromic redox reactions of vacuum-evaporated thin films of tetrapyridotetraazaporphyrinatozinc(II) ( TPyTAPZn ) have been studied in aqueous KCl electrolytes by in situ spectrocyclic voltammetry, which combines cyclic voltammetry and in situ monitoring of the absorption spectrum of the film. Although the voltammetric response of TPyTAPZn thin film electrodes can hardly be understood by the conventional electrochemical approach, the spectral information linked to the voltammetric information elucidated the presence of two-step reductions and reoxidations by each electron per TPyTAPZn molecule, which, however, take place with significant overlap during the voltammetric scan. Reduction of the film turned the color of the film from blue to purple and it changed reversibly to regenerate the original spectrum upon reoxidation. These reversible electrochromic reactions could be repeated many times without causing any noticeable change in the voltammetric and spectral responses. While use of electrolytes with various cations did not affect the redox behavior of the film, the effect of electrolyte pH was clearly seen, changing the ratio of the two reduction and two reoxidation peak magnitudes in the voltammogram. XPS analysis of the reduced film indicated that charge compensation upon reduction of the film occurred by protonation of reduced TPyTAPZn molecules at their aza and/or pyrido nitrogen atoms. A reaction scheme is presented to describe the observed redox reactions of the TPyTAPZn thin film from thermodynamic and kinetic viewpoints.
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Mihara, Shoko, Hitomi Wakao, Keisuke Yoshida, Akiyoshi Higo, Kazunori Sugiura, Akihiro Tsuchiya, Jiro Nomata, Ken-ichi Wakabayashi i Toru Hisabori. "Thioredoxin regulates G6PDH activity by changing redox states of OpcA in the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120". Biochemical Journal 475, nr 6 (20.03.2018): 1091–105. http://dx.doi.org/10.1042/bcj20170869.
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Glucose 6-phosphate dehydrogenase (G6PDH) catalyzes the first reaction in the oxidative pentose phosphate pathway. In green plant chloroplasts, G6PDH is a unique redox-regulated enzyme, since it is inactivated under the reducing conditions. This regulation is accomplished using a redox-active cysteine pair, which is conserved in plant G6PDH. The inactivation of this enzyme under conditions of light must be beneficial to prevent release of CO2 from the photosynthetic carbon fixation cycle. In the filamentous, heterocyst-forming, nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 (Anabaena 7120), G6PDH plays a pivotal role in providing reducing power for nitrogenase, and its activity is also reported to be suppressed by reduction, though Anabaena G6PDH does not conserve the critical cysteines for regulation. Based on the thorough analyses of the redox regulation mechanisms of G6PDH from Anabaena 7120 and its activator protein OpcA, we found that m-type thioredoxin regulates G6PDH activity by changing the redox states of OpcA. Mass spectrometric analysis and mutagenesis studies indicate that Cys393 and Cys399 of OpcA are responsible for the redox regulation property of this protein. Moreover, in vivo analyses of the redox states of OpcA showed that more than half of the OpcA is present as an oxidized form, even under conditions of light, when cells are cultured under the nitrogen-fixing conditions. This redox regulation of OpcA might be necessary to provide reducing power for nitrogenase by G6PDH in heterocysts even during the day.
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Blackmore, R. S., T. Brittain i C. Greenwood. "An analysis of the reaction kinetics of the hexahaem nitrite reductase of the anaerobic rumen bacterium Wolinella succinogenes". Biochemical Journal 271, nr 2 (15.10.1990): 457–61. http://dx.doi.org/10.1042/bj2710457.
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The reduction kinetics of both the resting and redox-cycled forms of the nitrite reductase from the anaerobic rumen bacterium Wolinella succinogenes were studied by stopped-flow reaction techniques. Single-turnover reduction of the enzyme by dithionite occurs in two kinetic phases for both forms of the enzyme. When the resting form of the enzyme is subjected to a single-turnover reduction by dithionite, the slower of the two kinetic phases exhibits a hyperbolic dependence of the rate constant on the square root of the reductant concentration, the limiting value of which (approximately 4 s-1) is assigned to a slow internal electron-transfer process. In contrast, when the redox-cycled form of the enzyme is reduced by dithionite in a single-turnover experiment, both kinetic phases exhibit linear dependences of the rate on the square root of dithionite concentration, with associated rate constants of 150 M-1/2.s-1 and 6 M-1/2.s-1. Computer simulations of both the reduction processes shows that no unique set of rate constants can account for the kinetics of both forms, although the kinetics of the redox-cycled species is consistent with a much enhanced rate of internal electron transfer. Under turnover conditions the time course for reduction of the enzyme, in the presence of millimolar levels of nitrite and 100 mM-dithionite, is extremely complex. A working model for the mechanism of the turnover activity of the enzyme is proposed which very closely describes the reaction kinetics over a wide range of substrate concentrations, as shown by computer simulation. The similarity in the action of the nitrite reductase enzyme and mammalian cytochrome c oxidase is commented upon.
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Redel, Katarzyna, Andrzej Kulka, Katarzyna Walczak, Anna Plewa, Camelia N. Borca i Janina Molenda. "The impact of oxygen evolution and cation migration on the cycling stability of a Li-rich Li[Li0.2Mn0.6Ni0.1Co0.1]O2 positive electrode". Journal of Materials Chemistry A 8, nr 35 (2020): 18143–53. http://dx.doi.org/10.1039/d0ta05556e.
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Comprehensive analysis of the oxygen and 3d metal redox reaction in electrochemical processes clarifies the extraordinary behavior of a Li[Li0.2Mn0.6Ni0.1Co0.1]O2 cathode.
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Sandoval-González, A., i S. A. Gamboa. "Analysis of Redox Reactions on Pt-Sn based Nano-catalysts for Direct Methanol Fuel Cell Applications". Journal of New Materials for Electrochemical Systems 21, nr 1 (16.04.2018): 021–28. http://dx.doi.org/10.14447/jnmes.v21i1.517.
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Low content Pt based catalysts (Pt-Mx, Mx: SnO2, Sn) were prepared by microwave assisted-thermal synthesis. Pt-SnO2/C catalyst showed good performance for methanol oxidation reaction. Besides, Pt1Sn1/C showed good performance for catalyzing the oxygen reduction reaction. The catalysts were characterized structurally by X-ray diffraction and transmission electron microscopy techniques. It was possible to observe the presence of nanoparticles obtained by the synthesis method used in this work. The chemical composition of every material was determined by energy dispersive spectroscopy analysis. The electrochemical characterization of the electrocatalytic materials was carried out in acid medium by cyclic voltammetry and rotating disk electrode techniques. Pt-SnO2/C and Pt1Sn1/C were compared with commercial PtRu/C and Pt/C catalysts respectively. Pt-SnO2/C showed better electrochemical characteristics than commercial PtRu/C for performing the methanol oxidation reaction (MOR). Pt1Sn1/C showed an exchange current density two orders of magnitude higher than commercial Pt/C for performing the oxygen reduction reaction (ORR). The materials were evaluated in an experimental direct methanol fuel cell (DMFC) operating during 10 hours. The electric power density loss showed by the DMFC made with commercial catalysts (PtRu/C and Pt/C) was 67% while the DMFC made with Pt-SnO2/C and Pt1Sn1/C showed an electric power loss ca. 16%. It means that the catalysts synthesized in this work can be considered as good candidates for experimental direct methanol fuel cells.