Статті в журналах: "Redox of particles"

1

McWhinney, R. D., S. Zhou, and J. P. D. Abbatt. "Redox activity of naphthalene secondary organic aerosol." Atmospheric Chemistry and Physics Discussions 13, no. 4 (April 5, 2013): 9107–49. http://dx.doi.org/10.5194/acpd-13-9107-2013.

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Abstract. Chamber secondary organic aerosol (SOA) from low-NOx photooxidation of naphthalene by hydroxyl radical was examined with respect to its redox cycling behaviour using the dithiothreitol (DTT) assay. Naphthalene SOA was highly redox active, consuming DTT at an average rate of 118 &pm; 14 pmol per minute per μg of SOA material. Measured particle-phase masses of the major previously identified redox active products, 1,2- and 1,4-naphthoquinone, accounted for only 21 &pm; 3% of the observed redox cycling activity. The redox-active 5-hydroxy-1,4-naphthoquinone was identified as a new minor product of naphthalene oxidation, and including this species in redox activity predictions increased the predicted DTT reactivity to 30 &pm; 5% of observations. Similar attempts to predict redox behaviour of oxidised two-stroke engine exhaust particles by measuring 1,2-naphthoquinone, 1,4-naphthoquinone and 9,10-phenanthrenequinone predicted DTT decay rates only 4.9 &pm; 2.5% of those observed. Together, these results suggest that there are substantial unidentified redox-active SOA constituents beyond the small quinones that may be important toxic components of these particles. A gas-to-SOA particle partitioning coefficient was calculated to be (7.0 &pm; 2.5) × 10−4 m3 μg−1 for 1,4-naphthoquinone at 25 °C. This value suggests that under typical warm conditions, 1,4-naphthoquinone is unlikely to contribute strongly to redox behaviour of ambient particles, although further work is needed to determine the potential impact under conditions such as low temperatures where partitioning to the particle is more favourable. As well, higher order oxidation products that likely account for a substantial fraction of the redox cycling capability of the naphthalene SOA are likely to partition much more strongly to the particle phase.

2

Wei, Chenxi, Yanshuai Hong, Yangchao Tian, Xiqian Yu, Yijin Liu, and Piero Pianetta. "Quantifying redox heterogeneity in single-crystalline LiCoO2 cathode particles." Journal of Synchrotron Radiation 27, no. 3 (March 13, 2020): 713–19. http://dx.doi.org/10.1107/s1600577520002076.

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Active cathode particles are fundamental architectural units for the composite electrode of Li-ion batteries. The microstructure of the particles has a profound impact on their behavior and, consequently, on the cell-level electrochemical performance. LiCoO2 (LCO, a dominant cathode material) is often in the form of well-shaped particles, a few micrometres in size, with good crystallinity. In contrast to secondary particles (an agglomeration of many fine primary grains), which are the other common form of battery particles populated with structural and chemical defects, it is often anticipated that good particle crystallinity leads to superior mechanical robustness and suppressed charge heterogeneity. Yet, sub-particle level charge inhomogeneity in LCO particles has been widely reported in the literature, posing a frontier challenge in this field. Herein, this topic is revisited and it is demonstrated that X-ray absorption spectra on single-crystalline particles with highly anisotropic lattice structures are sensitive to the polarization configuration of the incident X-rays, causing some degree of ambiguity in analyzing the local spectroscopic fingerprint. To tackle this issue, a methodology is developed that extracts the white-line peak energy in the X-ray absorption near-edge structure spectra as a key data attribute for representing the local state of charge in the LCO crystal. This method demonstrates significantly improved accuracy and reveals the mesoscale chemical complexity in LCO particles with better fidelity. In addition to the implications on the importance of particle engineering for LCO cathodes, the method developed herein also has significant impact on spectro-microscopic studies of single-crystalline materials at synchrotron facilities, which is broadly applicable to a wide range of scientific disciplines well beyond battery research.

3

McWhinney, R. D., S. Zhou, and J. P. D. Abbatt. "Naphthalene SOA: redox activity and naphthoquinone gas–particle partitioning." Atmospheric Chemistry and Physics 13, no. 19 (October 2, 2013): 9731–44. http://dx.doi.org/10.5194/acp-13-9731-2013.

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Abstract. Chamber secondary organic aerosol (SOA) from low-NOx photooxidation of naphthalene by hydroxyl radical was examined with respect to its redox cycling behaviour using the dithiothreitol (DTT) assay. Naphthalene SOA was highly redox-active, consuming DTT at an average rate of 118 ± 14 pmol per minute per μg of SOA material. Measured particle-phase masses of the major previously identified redox active products, 1,2- and 1,4-naphthoquinone, accounted for only 21 ± 3% of the observed redox cycling activity. The redox-active 5-hydroxy-1,4-naphthoquinone was identified as a new minor product of naphthalene oxidation, and including this species in redox activity predictions increased the predicted DTT reactivity to 30 ± 5% of observations. These results suggest that there are substantial unidentified redox-active SOA constituents beyond the small quinones that may be important toxic components of these particles. A gas-to-SOA particle partitioning coefficient was calculated to be (7.0 ± 2.5) × 10−4 m3 μg−1 for 1,4-naphthoquinone at 25 °C. This value suggests that under typical warm conditions, 1,4-naphthoquinone is unlikely to contribute strongly to redox behaviour of ambient particles, although further work is needed to determine the potential impact under conditions such as low temperatures where partitioning to the particle is more favourable. Also, higher order oxidation products that likely account for a substantial fraction of the redox cycling capability of the naphthalene SOA are likely to partition much more strongly to the particle phase.

4

Frey, H., A. Beck, X. Huang, J. A. van Bokhoven, and M. G. Willinger. "Dynamic interplay between metal nanoparticles and oxide support under redox conditions." Science 376, no. 6596 (May 27, 2022): 982–87. http://dx.doi.org/10.1126/science.abm3371.

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The dynamic interactions between noble metal particles and reducible metal-oxide supports can depend on redox reactions with ambient gases. Transmission electron microscopy revealed that the strong metal-support interaction (SMSI)–induced encapsulation of platinum particles on titania observed under reducing conditions is lost once the system is exposed to a redox-reactive environment containing oxygen and hydrogen at a total pressure of ~1 bar. Destabilization of the metal–oxide interface and redox-mediated reconstructions of titania lead to particle dynamics and directed particle migration that depend on nanoparticle orientation. A static encapsulated SMSI state was reestablished when switching back to purely oxidizing conditions. This work highlights the difference between reactive and nonreactive states and demonstrates that manifestations of the metal-support interaction strongly depend on the chemical environment.

5

Lu, Senlin, Teng Ma, Lu Zhang, Yule Feng, Shumin Zhou, Wei Zhang, Shinichi Yonemochi, et al. "Relationships between Mass Level of Allergenic Platanus acerifolia Protein 3 (Pla a3) and Redox Trace Elements in the Size-Resolved Particles in Shanghai Atmosphere." Atmosphere 13, no. 10 (September 21, 2022): 1541. http://dx.doi.org/10.3390/atmos13101541.

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Allergenic pollen protein can be released from pollen grains and suspended in the air to cause allergenic reactions. However, the allergenic protein and its relationship with redox trace elements in ambient size-resolved particles has not been reported. Ambient size-resolved particles in Shanghai’s atmosphere were sampled during the Platanus pollen season in the spring season of 2017. Planatus pollen protein 3 (Pla a3) and redox trace elements in the ambient particles were investigated and their relationship was analyzed. Our data demonstrated that the mass level of the Pla a3 in the size-resolved particles ranged from 0.41 ± 0.28 to 7.46 ± 2.23 pg/m3, and decreased with the size range. Mass concentrations (ppb) of crustal elements (Fe, Al, Ca, Mg, Na) in the size-resolved particles ranged from 20.11 ± 9.87 to 1126.22 ± 659.51, while trace elements (V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Cd, Cs, Ba, Pb) varied from 0.05 ± 0.03 to 57.53 ± 19.7. Mass levels of these trace elements decreased according to particle size. The Abundance of redox trace elements, including Fe (R2 = 0.82), Mn (R2 = 0.54), Cu (R2 = 0.61), Ba (R2 = 0.82), and Pb (R2 = 0.82) in the size-resolved particles was significantly related to that of Pla a3, and our data implied redox trace elements might take syngenetic effects on the allergenicity induced by Pla a3 protein.

6

Gulin-Sarfraz, Tina, Jawad Sarfraz, Didem Şen Karaman Didem Şen Karaman, Jixi Zhang, Christina Oetken-Lindholm, Alain Duchanoy, Jessica M. Rosenholm, and Daniel Abankwa. "FRET-reporter nanoparticles to monitor redox-induced intracellular delivery of active compounds." RSC Adv. 4, no. 32 (2014): 16429–37. http://dx.doi.org/10.1039/c4ra00270a.

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FRET-reporter particles for redox-induced release of active compounds in cells were developed. This particle system allowed following the intracellular cleavage of delivered compounds after particle internalization.

7

Su, Yangxin, Xinrong Zhang, Shun Zhang, Shi Fang, Xiuli Fu, and Hongjun Shao. "Relationship between the size composition observed from the photosedimention technique and chromaticity of the fine-grained surface sediments from the modern lakes, Songnen Plain." IOP Conference Series: Earth and Environmental Science 1087, no. 1 (October 1, 2022): 012081. http://dx.doi.org/10.1088/1755-1315/1087/1/012081.

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Abstract The relationship between clay particle size in fine-grained sediments and the enrichment of organic matter and the redox degree of their environment is conducive to the judgment and evaluation of the hydrocarbon generation potential of fine-grained sediments. The grain size characteristics of clay particles in the surface fine-grained sediments of Chaersen lake, Delong lake, Hongyuan lake, Lamasi lake, and Zhongnei lake in Songnen Plain are revealed by light sedimentation method. On the basis of the test, the relationship between the particle size of clay particles and the sediment chromaticity is analyzed, and the directivity of chromaticity to the content of organic matter and redox degree of fine-grained sediments is used for the organic content estimation. It is confirmed that the particle size of clay is negatively correlated with its organic matter content and positively correlated with its redox degree. This has important reference significance for discussing the hydrocarbon generation potential and evaluation of Cretaceous lacustrine fine-grained source rocks in the Songliao Basin.

8

Zhang, Fen, Qian Yao, Yanling Niu, Yantao Li, Haijun Zhou, Xiaoqi Chen, and Lu Bai. "Preparation of polymeric vesicles via redox-initiated RAFT dispersion polymerization." E3S Web of Conferences 438 (2023): 01020. http://dx.doi.org/10.1051/e3sconf/202343801020.

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2-(diisopropylamino) ethyl methacrylate (DIPEMA) and glycidyl methacrylate (GlyMA) were used for the investigation of the redox-initiated reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization, by using poly (ethylene oxide)-4-(4-Cyanopentanoic acid) dithiobenzoate (mPEG-CPADB) as the macro-chain-transfer agent (macro-CTA). The particle growth process study indicated that the particles changed from spheres to worms, and then to vesicles during the polymerization process. The degree of polymerization (DP) of the hydrophobic block P(DIPEMA-co-GlyMA) affected the particle morphology, particle diameter and molecular weight significantly. Pure polymeric vesicles could be obtained when DP was equal to or higher than 60, and with increasing of the DP of the hydrophobic block, the diameter and the molecular weight of the particles both increased.

9

Tantra, Ratna, Alex Cackett, Roger Peck, Dipak Gohil, and Jacqueline Snowden. "Measurement of Redox Potential in Nanoecotoxicological Investigations." Journal of Toxicology 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/270651.

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Redox potential has been identified by the Organisation for Economic Co-operation and Development (OECD) as one of the parameters that should be investigated for the testing of manufactured nanomaterials. There is still some ambiguity concerning this parameter, i.e., as to what and how to measure, particularly when in a nanoecotoxicological context. In this study the redox potentials of six nanomaterials (either zinc oxide (ZnO) or cerium oxide (CeO2)) dispersions were measured using an oxidation-reduction potential (ORP) electrode probe. The particles under testing differed in terms of their particle size and dispersion stability in deionised water and in various ecotox media. The ORP values of the various dispersions and how they fluctuate relative to each other are discussed. Results show that the ORP values are mainly governed by the type of liquid media employed, with little contributions from the nanoparticles. Seawater was shown to have reduced the ORP value, which was attributed to an increase in the concentration of reducing agents such as sulphites or the reduction of dissolved oxygen concentration. The lack of redox potential value contribution from the particles themselves is thought to be due to insufficient interaction of the particles at the Pt electrode of the ORP probe.

10

Liver, Naomi, and Abraham Nitzan. "Redox properties of small semiconductor particles." Journal of Physical Chemistry 96, no. 8 (April 1992): 3366–73. http://dx.doi.org/10.1021/j100187a035.

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11

Gu, Wen Juan, Xiao Hui Zhang, and Jie Li. "Preparation of PVAc Particles by Dispersion Polymerization." Applied Mechanics and Materials 184-185 (June 2012): 1134–37. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.1134.

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Highly uniform polyvinylacetate particles of submicron size were prepared by dispersion polymerization in mixed media of isopropanol and water initiated by redox initiator of NaHSO3 and K2S2O8 using poly(N-vinylpyrrolidone) as stabilizer. Monomer conversion was studied gravimetrically. Both the morphology and the size of the particles were measured by TEM. The influences of various polymerization parameters, such as monomer concentration, stabilizer content, on the particle properties were systematically investigated. The PVAc particles synthesized in this research were mono-disperse spheres with the diameter between 100-1000 nm.

12

Zimmermann, Ralf, Johannes Passig, Robert Irsig, Hendryk Czech, Patrick Martens, Thomas Adam, Julian Schade, and Sven Ehlert. "150 Keynote: A New Aerosol Mass-Spectrometer for Simultaneous Detection of Health-Relevant Polycyclic Aromatic Hydrocarbons, Soot and Inorganic Components from Individual Airborne Particles." Annals of Work Exposures and Health 67, Supplement_1 (May 1, 2023): i2—i3. http://dx.doi.org/10.1093/annweh/wxac087.006.

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Abstract Air pollution by fine particles represents a severe environmental health-risk. The particle’s content of toxic compounds, such as polycyclic aromatic hydrocarbons (PAH), elemental carbon/soot or redox-active transition metals (e.g. Fe), is highly relevant for their toxicity. The particulate matter (PM) composition can be determined by chemical analysis of PM-loaded filter samples but no information on the mixing state of toxicants, i.e. the distribution of toxicants within the particle ensemble, is obtainable by this approach. The mixing state, however, is a crucial parameter to assess health effects as the toxicants may either be equally distributed over many particles (internally mixed) or could be highly concentrated within a small particle sub-population (externally mixed). In the latter case, the few particles with a very high concentration of toxicants can induce stronger cellular effects at the lung-deposition site. A new approach is based on single particle mass spectrometry (SPMS) but introduces a novel, tailored laser ionisation process. Aerosol particles are on-line sampled from the air and size-characterized by laser velocimetry. The organic coating of individual particles is desorbed by intense IR-laser pulses and subsequently the relevant toxicants (transition metals, PAH and soot) are ionized and MS-detected particle-by-particle, using a novel combined UV-laser ionization scheme (Schade et al. Anal., Chem. 2019; Passig et al. ACP 2022). The novel SPMS system offers the characterisation of the most relevant PM-toxicants (soot, metals, PAH) on a sized-resolved, single particle-basis and gives insight into their mixing state. First SPMS-ambient air monitoring results for PAH or metals show that, depending on conditions, the toxicants indeed either are concentrated on a very small fraction of the particle-ensemble or are rather uniformly distributed over all particles. Future application concepts of the new SPMS-technology in air monitoring and environmental health research are discussed.

13

Lin, Feng. "(Battery Division Early Career Award Sponsored by Neware Technology Limited) Design, Synthesis, and Characterization of Cathode Microstructures in Lithium Batteries." ECS Meeting Abstracts MA2022-02, no. 3 (October 9, 2022): 210. http://dx.doi.org/10.1149/ma2022-023210mtgabs.

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The propagation of redox reactions governs the electrochemical properties of battery materials and their critical performance metrics in battery cells. The recent research progress, especially aided by advanced analytical techniques, has revealed that incomplete and heterogeneous redox reactions prevail in many electrode materials. Advanced high-capacity cathode materials are mostly polycrystalline materials that exhibit complex charge distribution (the valence state distribution of the redox-active cations) due to the presence of numerous constituting grains and grain boundaries. The redox reactions in individual grains typically do not proceed concurrently due to their distinct geometric locations in polycrystalline particles. As a result, these unsynchronized local redox events collectively induce heterogeneous and anisotropic charge distribution, building up intergranular and intragranular stress. Therefore, these polycrystalline materials may exhibit weak mechanical stability, leading to undesired chemomechanical breakdown during battery operation. Grain engineering in polycrystalline materials provides a large playground to modulate the materials properties beyond controlling the chemical composition, and electronic and crystal structures. In particular, the anisotropic ion-conducting pathways in layered oxides make the grain crystallographic orientation a critical factor in determining the modality of the redox reactions in these materials. This presentation will discuss our recent progress in the design, synthesis, and characterization of cathode microstructures in lithium batteries. First, we will discuss how the charge distribution is guided by grain crystallographic orientations in polycrystalline battery materials. We elucidate the spatially resolved charge distribution in lithium layered oxides with different grain crystallographic arrangements and establish a model to quantify their charge distributions. While the holistic “surface-to-bulk” charge distribution prevails in polycrystalline particles, the crystallographic orientation-guided redox reaction governs the charge distribution in the local charged nanodomains. Compared to the randomly oriented grains, the radially aligned grains exhibit a lower cell polarization and higher capacity retention upon battery cycling. The radially aligned grains create less tortuous lithium-ion pathways, thus improving the charge homogeneity as statistically quantified from over 20 million nanodomains in polycrystalline particles. This study provides an improved understanding of the charge distribution and chemomechanical properties of polycrystalline battery materials. Second, we will discuss how the grain arrangement affects the thermal stability of polycrystalline cathode materials in rechargeable batteries. We performed a systematic in situ study on the Ni-rich polycrystalline cathode materials to investigate the fundamental degradation mechanism of charged cathodes at elevated temperatures, which is essential for tailoring material properties and improving performance. Using multiple microscopy, scattering, thermal, and electrochemical probes, we decoupled the major contributors to the thermal instability from intertwined factors. Based on our findings, the cathode grain microstructure has a forgotten yet important role in the thermal stability of polycrystalline rechargeable batteries. Oxygen release, as an important process during the thermal runaway, can be regulated through engineering grain arrangements. The grain arrangement can modulate the macroscopic crystallographic transformation pattern and oxygen diffusion length in layered cathodes to offer more possibilities for cathode material design and synthesis. Third, we will discuss our new understanding of particle behaviors in composite cathodes. We capture and quantify the particle motion during the solidification of battery electrodes and reveal the statistics of the dynamically evolving motion in the drying process, which has been challenging to resolve. We discover that the particle motion exhibits a strong dependence on its geometric location within a drying electrode. Our results also imply that the final electrode quality can be controlled by balancing the solvent evaporation rate and the particle mobility in the region close to the drying surface. We formulate a network evolution model to interpret the regulation and equilibration between electrochemical activity and mechanical damage of these particles. Through statistical analysis of thousands of particles using x-ray phase-contrast holotomography in a Ni-rich cathode, we found that the local network heterogeneity results in asynchronous activities in the early cycles, and subsequently the particle assemblies move toward a synchronous behavior. Our study pinpoints the chemomechanical behavior of individual particles and enables better designs of the conductive network to optimize the utility of all the particles during operation.

14

Gambim, MH, AO Carmo, L. Marti, S. Veríssimo-Filho, LR Lopes, and M. Janiszewski. "Platelet-derived exosomes are redox signaling particles." Critical Care 11, Suppl 3 (2007): P1. http://dx.doi.org/10.1186/cc5788.

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15

Aoki, Koichi, and Ting Lei. "Electrochemical Event of Single Redox Latex Particles." Langmuir 16, no. 26 (December 2000): 10069–75. http://dx.doi.org/10.1021/la000739m.

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16

Kliewer, C. E. "Understanding Redox Effects on Supported Bimetallic Particles." Microscopy and Microanalysis 23, S1 (July 2017): 968–69. http://dx.doi.org/10.1017/s1431927617005505.

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17

Liang, Yu. "Preparation of Nanometer Sized Cuprous Oxide and its Photocatalytic Performance over Four Nitrophenol." Applied Mechanics and Materials 333-335 (July 2013): 1853–56. http://dx.doi.org/10.4028/www.scientific.net/amm.333-335.1853.

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Nanometer sized Cu2O is synthesised by nucleation crystallization separation and redox methods, with NaBH4 as reducing agent. It takes several researching methods, such as XRD,SEM,EDS and UV-vis, etc, to study the structure, composition and spectral features of the product. The results show that, comparing with traditional methods, the Cu2O particles produced by nucleation crystallization separation and redox methods have following features: similar appearances, small particle size, and narrow distribution, etc. The photocatalytic experiment shows that, this kind of Cu2O has excellent photocatalytic activity over four nitrophenol.

18

Yang, Jixing. "Application of Nano Drug Carrier in the Detection of Human Hemoglobin Content." Nanoscience and Nanotechnology Letters 12, no. 2 (February 1, 2020): 125–31. http://dx.doi.org/10.1166/nnl.2020.3089.

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This paper studies the application of nano drug carrier in the detection of human hemoglobin content. Taking nano modified electrode as nano drug carrier, the application of nano silver particle modified silver electrode and nano poly thionine modified electrode in the detection of human hemoglobin content is studied. Atomic force microscope, UV-Vis and FT-IR are used to characterize the nano poly(thionine), and the electrochemical properties of nano poly(thionine) modified electrode. The silver electrode decorated with nano silver particles is made. The electrochemical behavior of hemoglobin on the modified electrode is studied. The experimental results show that a pair of redox peaks appear in the silver electrode modified by nano silver particles. With the increase of Hb concentration, the redox peak current in the cyclic voltammogram of the silver electrode modified by nano silver particles increases correspondingly, and the hemoglobin has a good current response on the silver electrode modified by nano silver particles, which is a kind of adsorption current. The electrochemical activity of nano poly thionine shows a decreasing tendency with pH value. After adding hemoglobin, there is a significant reduction peak near –0.4 V. With the increase of hemoglobin concentration, the reduction peak current increases accordingly. The nano poly thionine modified electrode has a catalytic effect on the reduction of hemoglobin. The results show that the two nano drug carriers, nano poly thionine modified electrode and nano silver particle modified silver electrode, can effectively analyze and determine human hemoglobin.

19

Willner, Itamar, and Bilha Willner. "Functional nanoparticle architectures for sensoric, optoelectronic, and bioelectronic applications." Pure and Applied Chemistry 74, no. 9 (January 1, 2002): 1773–83. http://dx.doi.org/10.1351/pac200274091773.

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Tailored sensoric, electronic, photoelectrochemical, and bioelectrocatalytic functions can be designed by organized molecular or biomolecular nanoparticle hybrid configurations on surfaces. Layered receptor-cross-linked Au nanoparticle assemblies on electrodes act as specific sensors of tunable sensitivities. Layered DNA-cross-linked CdS nanoparticles on electrode supports reveal organized assemblies of controlled electronic and photoelectrochemical properties. Au nanoparticle-FAD semisynthetic cofactor units are reconstituted into apo-glucose oxidase (GOx) and assembled onto electrodes. The resulting enzymes reveal effective electrical contacting with the electrodes, and exhibit bioelectrocatalytic functions toward the oxidation of glucose to gluconic acid. Magneto-switchable electrocatalysis and bioelectrocatalysis are accomplished by the surface modification of magnetic particles with redox-relay units. By the attraction of the modified magnetic particles to the electrode support, or their retraction from the electrode, by means of an external magnet, the electrochemical functions of the magnetic particle-tethered relays can be switched between "ON" and "OFF" states, respectively. The magneto-switchable redox functionalities of the modified particles activate electrocatalytic transformations, such as a biocatalytic chemoluminescence cascade that leads to magneto-switchable light emission or the activation of bioelectrocatalytic processes.

20

Mills, Andrew, and David Worsley. "Kinetics of redox dissolution of soft-centre particles." Journal of the Chemical Society, Faraday Transactions 86, no. 20 (1990): 3405. http://dx.doi.org/10.1039/ft9908603405.

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21

Zubritsky, Elizabeth. "Meeting News: Nano particles instead of redox agents?" Analytical Chemistry 76, no. 1 (January 2004): 14 A. http://dx.doi.org/10.1021/ac041496w.

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22

Shinyashiki, Masaru, Arantza Eiguren-Fernandez, Debra A. Schmitz, Emma Di Stefano, Ning Li, William P. Linak, Seung-Hyun Cho, John R. Froines, and Arthur K. Cho. "Electrophilic and redox properties of diesel exhaust particles." Environmental Research 109, no. 3 (April 2009): 239–44. http://dx.doi.org/10.1016/j.envres.2008.12.008.

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23

Li, Xuan, Thomas Lunkenbein, Jutta Kröhnert, Verena Pfeifer, Frank Girgsdies, Frank Rosowski, Robert Schlögl, and Annette Trunschke. "Hydrothermal synthesis of bi-functional nanostructured manganese tungstate catalysts for selective oxidation." Faraday Discussions 188 (2016): 99–113. http://dx.doi.org/10.1039/c5fd00191a.

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The mechanism of C–H activation in selective oxidation reactions of short-chain alkane molecules over transition metal oxides is critically affected by the balance of acid–base and redox sites at the surface of the catalyst. Using the example of manganese tungstate we discuss how the relative abundance of these sites can be controlled via synthetic techniques. Phase-pure catalysts composed of the thermodynamic stable monoclinic MnWO₄ phase have been prepared using hydrothermal synthesis. Variation of the initial pH value resulted in rod-shaped nano-crystalline MnWO₄ catalysts composed of particles with varying aspect ratio. The synthesis products have been analysed using transmission electron microscopy, X-ray diffraction, infrared, and photoelectron spectroscopy. In situ Raman spectroscopy was used to investigate the dissolution–re-crystallization processes occurring under hydrothermal conditions. Ethanol oxidation was applied to probe the surface functionalities in terms of acid–base and redox properties. Changes in the aspect ratio of the primary catalyst particles are reflected in the product distribution induced by altering the fraction of acid–base and redox sites exposed at the surface of the catalysts in agreement with the proposed mechanism of particle growth by re-crystallization during ageing under hydrothermal conditions.

24

Turner, Elizabeth A., Harald Rösner, Yining Huang, and John F. Corrigan. "Formation of group 12 [Zn, Cd] mixed-chalcogen nanoparticles from the reagent Me3Si-SeS-SiMe3." Canadian Journal of Chemistry 85, no. 10 (October 1, 2007): 747–55. http://dx.doi.org/10.1139/v07-083.

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Mixed-chalcogen metal chalcogenide nanoparticles (MSexS1-x; M = Zn, Cd) have been synthesized using Me3Si-SeS-SiMe3 as a delivery source of Se2– and S2– to the metal core. This method demonstrates the ease with which mixed-chalcogen particles can be fabricated at low temperature using colloidal techniques. Reaction with Me3Si-SeS-SiMe3 occurs via a redox pathway resulting in Se–S bond cleavage and ultimately contributing to the nonequivalent Se:S ratio observed in the isolated particles. Subsequent thermolysis of ZnSe0.57S0.43 and CdSe0.28S0.72 in hexadecylamine gives rise to controlled particle growth while maintaining the observed stoichiometry. Particles are characterized by EDX, TEM, and powder X-ray diffraction analysis in conjunction with UV–vis absorption and photoluminescence (PL) spectroscopy.Key words: nanoparticles, semiconductors, mixed-chalcogen, quantum confinement, Group 12.

25

Kappler, Andreas, Aaron Thompson, and Muammar Mansor. "Impact of Biogenic Magnetite Formation and Transformation on Biogeochemical Cycles." Elements 19, no. 4 (August 1, 2023): 222–27. http://dx.doi.org/10.2138/gselements.19.4.222.

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Magnetite is a redox-active mineral that can form from both abiotic and biotic processes, and plays an active role in different biogeochemical cycles. Biogenic magnetite particles have properties that differ from their abiogenic counterparts in a variety of ways, including their size, chemical purity, magnetic properties, and association with biomass-derived organic matter. These properties directly influence magnetite reactivity—in particular its sorbent and redox behavior—affecting its association with metals, oxyanions, and other compounds in the environment. Biogenic (and abiogenic) magnetite particles are involved in redox processes by storing electrons, functioning as biogeobatteries, and by transferring electrons between microbial cells or between cells and inorganic constituents. Thus, magnetite influences the fate of contaminants and nutrients in the environment.

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Plumeré, Nicolas, Adrian Ruff, Bernd Speiser, Verena Feldmann, and Hermann A. Mayer. "Stöber silica particles as basis for redox modifications: Particle shape, size, polydispersity, and porosity." Journal of Colloid and Interface Science 368, no. 1 (February 2012): 208–19. http://dx.doi.org/10.1016/j.jcis.2011.10.070.

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Tantisakon, Theerapab, and Kanyarat Holasut. "Prospects of Carbon Based Micro-Fluid Electrolyte for the Vanadium Redox Flow Battery (VRB)." Advanced Materials Research 931-932 (May 2014): 1083–88. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.1083.

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The effects of carbon black particle dispersed in the electrolyte and used in a modified VRB which was traditionally used of carbon felt as electrode has been removed were studied. The adding of the carbon black particle reduced both activation overpotential and ohmic overpotential especially at low OCV. The functional group on the surface of the carbon black particle helps to increase the rate of reaction which results in the reduction of activation overpotential. When the electrolyte with the carbon black particle dispersed flows into the cell, it is possible that some of carbon particles settle on the surface of current collectors and this effectively increases the surface area of current collectors. Hence, it reduces the ohmic overpotential.

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Abbott, Andrew P., Salih Cihangir, and Karl S. Ryder. "Redox fusion of metal particles using deep eutectic solvents." Chemical Communications 54, no. 24 (2018): 3049–52. http://dx.doi.org/10.1039/c8cc00360b.

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Alternating anodic and cathodic current pulses have been applied to a metal powder on an electrode surface to fuse the particles together. It is shown that homogeneous films can be electroformed with different morphologies depending on the size of the powder and the experimental conditions.

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Suhawati, Ibrahim, and Asrul Mustafa. "Chemical Depolymerisation of Natural Rubber in Biphasic Medium." Advanced Materials Research 1024 (August 2014): 193–96. http://dx.doi.org/10.4028/www.scientific.net/amr.1024.193.

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The molecular weight of natural rubber (NR) can be reduced via depolymerization reaction to produce liquid natural rubber (LNR) with a molecular weight less than 50 000 g/mol. In the reaction, hydrogen peroxide and sodium nitrite were added to natural rubber latex to initiate a redox type reaction which then breaks the NR chain. Low permeation of reagents into latex particles allows the degradation to occur greater at the latex particle surface relative to the inner core contributes to high molecular weight distribution (MWD) or polydispersity of the LNR obtained. In this recent works, the reaction was carried out in a biphasic medium consisting of water and toluene phases. Toluene swells latex particles as indicated by the SEM micrographs showing changes in the size of latex particles. This occurrence is suggested to increase the influx of reagents into the latex particles. Consequently, with higher permeation of reagents into the latex particles resulted in the decrease of molecular weight and lower polydispersity of the LNR obtained. Chemical structure analysize showed that the LNRs obtained were attached with hydroxyl and carbonyl groups.

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Majji, Madhu V., and Fikile R. Brushett. "Modeling Charge Transport in Flowable Suspension Electrolytes." ECS Meeting Abstracts MA2023-01, no. 25 (August 28, 2023): 1687. http://dx.doi.org/10.1149/ma2023-01251687mtgabs.

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Abstract Flowable suspension electrolytes (FSEs) consist of electrically conductive, redox-active, and/or energy-storing particles suspended in aqueous or non-aqueous electrolyte solutions (supporting salt + solvent). These particles, which can range in size from nanometers to micrometers, are subjected to Brownian forces, hydrodynamic forces, hydrophobic interactions, and van der Walls interactions among others. FSEs may enable electrochemical processes where solid reactants can be integrate with flow cells potentially unlocking new approaches to materials processing (e.g., synthesis, extraction/recovery). For example, FSEs has been demonstrated in redox flow batteries, facilitating higher energy densities without sacrificing independent power and energy scaling However, understanding and controlling charge transport through the deformable particle microstructures, especially under shear, is key to enable desirable current distributions and thus effective electrode utilization. In this presentation, we investigate the impact of interparticle interactions, particle volume fractions, and applied shear rate on charge transport through FSEs. At sufficiently large volume fractions above the percolation threshold and stationary conditions, particle interactions in an FSE can drive the formation of networks that span the cell dimensions and provide electronic transport similar to stationary freestanding porous electrodes. However, under flowing conditions, shear forces can break these networks, hampering charge transport. Conversely, increasing attractive particle interactions or particle concentration can strengthen the particle networks and fortifying charge transport, albeit at the expense of fluid viscosity. To better understand these processes, we model the charge transport through these dynamic particle networks, using a combination of local charge transport models and discrete particle simulations, considering the Peclet number (ratio of shearing to Brownian forces) and Mason number (ratio of shearing to attractive forces). Our results contribute to the development of continuum models for charge transport in FSEs, which, in turn, can facilitate efficient and accurate system-level analysis. Acknowledgments This work was funded by the Skoltech – MIT Next Generation Program.

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Conway, Michael J., Samina Alam, Eric J. Ryndock, Linda Cruz, Neil D. Christensen, Richard B. S. Roden, and Craig Meyers. "Tissue-Spanning Redox Gradient-Dependent Assembly of Native Human Papillomavirus Type 16 Virions." Journal of Virology 83, no. 20 (August 5, 2009): 10515–26. http://dx.doi.org/10.1128/jvi.00731-09.

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ABSTRACT Papillomavirus capsids are composed of 72 pentamers reinforced through inter- and intrapentameric disulfide bonds. Recent research suggests that virus-like particles and pseudovirions (PsV) can undergo a redox-dependent conformational change involving disulfide interactions. We present here evidence that native virions exploit a tissue-spanning redox gradient that facilitates assembly events in the context of the complete papillomavirus life cycle. DNA encapsidation and infectivity titers are redox dependent in that they can be temporally modulated via treatment of organotypic cultures with oxidized glutathione. These data provide evidence that papillomavirus assembly and maturation is redox-dependent, utilizing multiple steps within both suprabasal and cornified layers.

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Yamaguchi, Akinobu, Ikuo Okada, Takao Fukuoka, Mari Ishihara, Ikuya Sakurai, and Yuichi Utsumi. "One-Step Synthesis of Copper and Cupric Oxide Particles from the Liquid Phase by X-Ray Radiolysis Using Synchrotron Radiation." Journal of Nanomaterials 2016 (2016): 1–16. http://dx.doi.org/10.1155/2016/8584304.

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The deposition of copper (Cu) and cupric oxide (Cu4O3, Cu2O, and CuO) particles in an aqueous copper sulfate (CuSO4) solution with additive alcohol such as methanol, ethanol, 2-propanol, and ethylene glycol has been studied by X-ray exposure from synchrotron radiation. An attenuated X-ray radiation time of 5 min allows for the synthesis of Cu, Cu4O3, Cu2O, and CuO nano/microscale particles and their aggregation into clusters. The morphology and composition of the synthesized Cu/cupric oxide particle clusters were characterized by scanning electron microscopy, scanning transmission electron microscopy, and high-resolution transmission electron microscopy with energy dispersive X-ray spectroscopy. Micro-Raman spectroscopy revealed that the clusters comprised cupric oxide core particles covered with Cu particles. Neither Cu/cupric oxide particles nor their clusters were formed without any alcohol additives. The effect of alcohol additives is attributed to the following sequential steps: photochemical reaction due to X-ray irradiation induces nucleation of the particles accompanying redox reaction and forms a cluster or aggregates by LaMer process and DLVO interactions. The procedure offers a novel route to synthesize the Cu/cupric oxide particles and aggregates. It also provides a novel additive manufacturing process or lithography of composite materials such as metal, oxide, and resin.

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Chen, Xiongbo, Penglu Wang, Ping Fang, Haiqiang Wang, Chaoping Cen, Wenhao Zeng, and Zhongbiao Wu. "Design strategies for SCR catalysts with improved N2 selectivity: the significance of nano-confining effects by titanate nanotubes." Environmental Science: Nano 4, no. 2 (2017): 437–47. http://dx.doi.org/10.1039/c6en00627b.

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Park, Heekyung, and Jun Hui Park. "Electrochemical Characterization of Neurotransmitters in a Single Submicron Droplet." Biosensors 14, no. 2 (February 17, 2024): 102. http://dx.doi.org/10.3390/bios14020102.

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Single-entity electrochemistry, which employs electrolysis during the collision of single particles on ultramicroelectrodes, has witnessed significant advancements in recent years, enabling the observation and characterization of individual particles. Information on a single aqueous droplet (e.g., size) can also be studied based on the redox species contained therein. Dopamine, a redox-active neurotransmitter, is usually present in intracellular vesicles. Similarly, in the current study, the electrochemical properties of neurotransmitters in submicron droplets were investigated. Because dopamine oxidation is accompanied by proton transfer, unique electrochemical properties of dopamine were observed in the droplet. We also investigated the electrochemical properties of the adsorbed droplets containing DA and the detection of oxidized dopamine by the recollision phenomenon.

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Sergeyeva, Olga V. "SMALL PARTICLES WITH LARGE PERSPECTIVES: II. HOW TO OBTAIN?" GAMTAMOKSLINIS UGDYMAS / NATURAL SCIENCE EDUCATION 5, no. 1 (April 1, 2008): 51–60. http://dx.doi.org/10.48127/gu-nse/08.5.51.

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The second article of the series deals with the main trends in the development of the methods to obtain nanoparticles – so called “bottom-up” and “up-bottom”. In the first case small particles are formed as a result of combination of the smaller ones (atoms as a limit), in the second – as a result of dispergation of the bulk matter. The electronic structure and the properties of the particles therewith could be different in the dependence on the way they were obtained (by means of dispergation or the atomic aggregation). Atoms and very small clusters can be stabilized by methods of cryochemistry discussed in the article. Nanoparticles formation by means of chemical and radiochemical synthesis, synthesis in the heterophase systems, providing the effective control of particle size and shape, the ways to obtain core-shell and hollow particles are considered next as well as the principles of the mechanical and chemical (redox) dispergation of the solids, leading to the ultradispersive and nanosized particles formation. Key words: nanoparticles, formation, chemical, cryochemical and radiochemical synthesis, dispergation.

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Cai, R., R. Baba, K. Hashimoto, Y. Kubota, and A. Fujishima. "Photoelectrochemistry of TiO2 particles: efficient electron transfer from the TiO2 particles to a redox enzyme." Journal of Electroanalytical Chemistry 360, no. 1-2 (November 1993): 237–45. http://dx.doi.org/10.1016/0022-0728(93)87016-o.

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Lei, Ting, and Koichi Aoki. "Monodispersed redox submicrometer particles created by polyaniline-coated polystyrene latex." Journal of Electroanalytical Chemistry 482, no. 2 (March 2000): 149–55. http://dx.doi.org/10.1016/s0022-0728(00)00041-3.

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38

Nalawati, Ara Nugrahayu, Nugraha Edhi Suyatma, and Danu Indra Wardhana. "SINTESIS NANOPARTIKEL PERAK (NPAg) DENGAN BIOREDUKTOR EKSTRAK BIJI JARAK PAGAR DAN KAJIAN AKTIVITAS ANTIBAKTERINYA." Jurnal Teknologi dan Industri Pangan 32, no. 1 (December 2021): 98–106. http://dx.doi.org/10.6066/jtip.2021.32.2.98.

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The redox analysis as indicated by a change in color from yellow to reddish-brown was measured at the optimum wavelength of 405 nm with the highest redox result of 480 nm obtained in the NPAg-S sample. The optimal absorption wavelength changes according to the characteristics of the NPAg produced, but is generally in the range of 400-500 nm. Analysis of the active groups with the FTIR instrument showed active groups (OH, CH aldehyde, vibrations of CN bonds in the amine group, amide I groups from proteins, and CO double bonds in the 4000-1500 cm-1) zone. Additionally, in the identification zone 1500-600 cm-1 the formation of CN bond vibrations and the presence of an amide I group from the protein was found. Photographs at 10.000 and 15.000x magnification showed that the morphology of the distribution of NPAg in the jatropha seed extract solution was polydisperse and in the form of fibrous balls with non-uniform particles and tended to agglomerate. The distribution and size of the particles measured using the Particle Size Analyzer (PSA) instrument showed that the particle size ranged from 33-116 nm. NPAg-S samples at two concentrations (1 and 2%) showed inhibitory activity for all types of Gram positive and Gram negative bacteria. Analysis of the particle size distribution using PSA showed that the particle size of the NPAg-S sample was 33.8 nm, which was smaller than the NPAg-K sample of 44.8 nm. Antibacterial activity is strongly influenced by the particle size of a sample. Small size silver nanoparticles have a large surface area to interact with bacteria as compared to large silver nanoparticles, thus they can provide a greater antibacterial effect.

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Broczkowski, M. E., J. S. Goldik, J. J. Noël, and David Shoesmith. "Influence of Noble Metal Particles on Redox Reactions on Uranium Dioxide Surfaces." Advances in Science and Technology 45 (October 2006): 1996–2003. http://dx.doi.org/10.4028/www.scientific.net/ast.45.1996.

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The influence of rare-earth doping and noble metal inclusions (ε-particles) on H2O2 and O2 reduction and H2 oxidation on UO2 surfaces has been studied electrochemically. These reactions are important in determining the corrosion behaviour of nuclear fuel inside failed waste containers under permanent waste disposal conditions. Experiments were conducted on SIMFUEL electrodes doped with various amounts of non-radioactive elements in proportions appropriate to simulate the chemical effects of in-reactor irradiation. The results show that ε-particles catalyze all of these reactions. These results indicate that ε-particles can act as catalytic anodes and cathodes depending on the redox conditions prevailing within a failed container.

40

Hu, S., A. Polidori, M. Arhami, M. M. Shafer, J. J. Schauer, A. Cho, and C. Sioutas. "Redox activity and chemical speciation of size fractioned PM in the communities of the Los Angeles – Long Beach Harbor." Atmospheric Chemistry and Physics Discussions 8, no. 3 (June 12, 2008): 11643–72. http://dx.doi.org/10.5194/acpd-8-11643-2008.

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Abstract. In this study, two different types of assays were used to quantitatively measure the redox activity of PM and to examine its intrinsic toxicity: 1) in vitro exposure to rat alveolar macrophage (AM) cells using dichlorofluorescin diacetate (DCFH-DA) as the fluorescent probe (macrophage ROS assay), and: 2) consumption of dithiothreitol (DTT) in a cell-free system (DTT assay). Coarse (PM10–2.5), accumulation (PM2.5–0.25), and quasi-ultrafine (quasi-UF, PM0.25) mode particles were collected weekly at five sampling sites in the Los Angeles-Long Beach Harbor and at one site near the University of Southern California campus (urban site). All PM samples were analyzed for organic (total and water-soluble) and elemental carbon, organic species, inorganic ions, and total and water-soluble elements. Quasi-UF mode particles showed the highest redox activity at all Long Beach sites (on both a per-mass and per-air volume basis). A significant association (R2=0.61) was observed between the two assays, indicating that macrophage ROS and DTT levels are affected at least partially by similar PM species. Relatively small variation was observed for the DTT measurements across all size fractions and sites, whereas macrophage ROS levels showed more significant ranges across the three different particle size modes and throughout the sites (coefficients of variation, or CVs, were 0.35, 0.24 and 0.53 for quasi-UF, accumulation, and coarse mode particles, respectively). Association between the PM constituents and the redox activity was further investigated using multiple linear regression models. The results showed that OC was the most important component influencing the DTT activity of PM samples. The variability of macrophage ROS was explained by changes in OC concentrations and water-soluble vanadium (probably originating from ship emissions – bunker oil combustion). The multiple regression models were used to predict the average diurnal macrophage ROS and DTT levels as a function of the OC concentration at one of the sampling sites.

41

Hu, S., A. Polidori, M. Arhami, M. M. Shafer, J. J. Schauer, A. Cho, and C. Sioutas. "Redox activity and chemical speciation of size fractioned PM in the communities of the Los Angeles-Long Beach harbor." Atmospheric Chemistry and Physics 8, no. 21 (November 12, 2008): 6439–51. http://dx.doi.org/10.5194/acp-8-6439-2008.

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Abstract. In this study, two different types of assays were used to quantitatively measure the redox activity of PM and to examine its intrinsic toxicity: 1) in vitro exposure to rat alveolar macrophage (AM) cells using dichlorofluorescin diacetate (DCFH-DA) as the fluorescent probe (macrophage ROS assay), and: 2) consumption of dithiothreitol (DTT) in a cell-free system (DTT assay). Coarse (PM10–2.5), accumulation (PM2.5–0.25), and quasi-ultrafine (quasi-UF, PM0.25) mode particles were collected weekly at five sampling sites in the Los Angeles-Long Beach harbor and at one site near the University of Southern California campus (urban site). All PM samples were analyzed for organic (total and water-soluble) and elemental carbon, organic species, inorganic ions, and total and water-soluble elements. Quasi-UF mode particles showed the highest redox activity at all Long Beach sites (on both a per-mass and per-air volume basis). A significant association (R2=0.61) was observed between the two assays, indicating that macrophage ROS and DTT levels are affected at least partially by similar PM species. Relatively small variation was observed for the DTT measurements across all size fractions and sites, whereas macrophage ROS levels showed more significant ranges across the three different particle size modes and throughout the sites (coefficients of variation, or CVs, were 0.35, 0.24 and 0.53 for quasi-UF, accumulation, and coarse mode particles, respectively). Association between the PM constituents and the redox activity was further investigated using multiple linear regression models. The results showed that OC was the most important component influencing the DTT activity of PM samples. The variability of macrophage ROS was explained by changes in OC concentrations and water-soluble vanadium (probably originating from ship emissions – bunker oil combustion). The multiple regression models were used to predict the average diurnal DTT levels as a function of the OC concentration at one of the sampling sites.

42

Chen, Shengbin, Chuanyu Sun, Huan Zhang, Hao Yu, and Wentong Wang. "Electrochemical Deposition of Bismuth on Graphite Felt Electrodes: Influence on Negative Half-Cell Reactions in Vanadium Redox Flow Batteries." Applied Sciences 14, no. 8 (April 15, 2024): 3316. http://dx.doi.org/10.3390/app14083316.

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In this paper, bismuth (Bi) was successfully deposited on graphite felts to improve the electrochemical performances of vanadium redox flow batteries. Modified graphite felts with different Bi particle loadings were obtained through electrochemical deposition at voltages of 0.8 V, 1.2 V and 1.6 V in 0.1 M BiCl3 solution for 10 min. The optimal Bi particle loading was confirmed by scanning electron microscopy (SEM), single cells and electrochemical tests. The SEM images revealed the deposition of granular Bi particles on the fiber surface. The Bi-modified felts which were electro-chemically deposited at 1.2 V (Bi/TGF-1.2V) showed excellent electrochemical performances in cyclic voltammetry curves and impedance spectroscopy. Meanwhile, the single cells assembled with Bi/TGF-1.2V as negative electrodes exhibited higher voltage efficiencies than the others. The optimized Bi particle loading induced better catalysis of the V3+/V2+ reaction and hence significantly improved the cell performances. In addition, the prepared Bi-modified felts showed stable cell performances and slower charge–discharge capacity declines than the other electrodes at current densities between 20 mA/cm2 and 80 mA/cm2. Compared with the pristine felt, the voltage efficiency of the vanadium redox flow battery assembled with Bi/TGF-1.2V graphite felt was 9.47% higher at the current density of 80 mA/cm2. The proposed method has considerable potential and guiding significance for the future modification of graphite felt for redox flow batteries.

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Reeve, Holly A., Philip A. Ash, HyunSeo Park, Ailun Huang, Michalis Posidias, Chloe Tomlinson, Oliver Lenz, and Kylie A. Vincent. "Enzymes as modular catalysts for redox half-reactions in H2-powered chemical synthesis: from biology to technology." Biochemical Journal 474, no. 2 (January 6, 2017): 215–30. http://dx.doi.org/10.1042/bcj20160513.

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The present study considers the ways in which redox enzyme modules are coupled in living cells for linking reductive and oxidative half-reactions, and then reviews examples in which this concept can be exploited technologically in applications of coupled enzyme pairs. We discuss many examples in which enzymes are interfaced with electronically conductive particles to build up heterogeneous catalytic systems in an approach which could be termed synthetic biochemistry. We focus on reactions involving the H+/H2 redox couple catalysed by NiFe hydrogenase moieties in conjunction with other biocatalysed reactions to assemble systems directed towards synthesis of specialised chemicals, chemical building blocks or bio-derived fuel molecules. We review our work in which this approach is applied in designing enzyme-modified particles for H2-driven recycling of the nicotinamide cofactor NADH to provide a clean cofactor source for applications of NADH-dependent enzymes in chemical synthesis, presenting a combination of published and new work on these systems. We also consider related photobiocatalytic approaches for light-driven production of chemicals or H2 as a fuel. We emphasise the techniques available for understanding detailed catalytic properties of the enzymes responsible for individual redox half-reactions, and the importance of a fundamental understanding of the enzyme characteristics in enabling effective applications of redox biocatalysis.

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Lovecchio, Elisa, and Timothy M. Lenton. "BPOP-v1 model: exploring the impact of changes in the biological pump on the shelf sea and ocean nutrient and redox state." Geoscientific Model Development 13, no. 4 (April 9, 2020): 1865–83. http://dx.doi.org/10.5194/gmd-13-1865-2020.

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Abstract. The biological pump of the ocean has changed over Earth's history, from one dominated by prokaryotes to one involving a mixture of prokaryotes and eukaryotes with trophic structure. Changes in the biological pump are in turn hypothesized to have caused important changes in the nutrient and redox properties of the ocean. To explore these hypotheses, we present here a new box model including oxygen (O), phosphorus (P) and a dynamical biological pump. Our Biological Pump, Oxygen and Phosphorus (BPOP) model accounts for two – small and large – organic matter species generated by production and coagulation, respectively. Export and burial of these particles are regulated by a remineralization length (zrem) scheme. We independently vary zrem of small and large particles in order to study how changes in sinking speeds and remineralization rates affect the major biogeochemical fluxes and O and P ocean concentrations. Modeled O and P budgets and fluxes lie reasonably close to present estimates for zrem in the range of currently measured values. Our results highlight that relatively small changes in zrem of the large particles can have important impacts on the O and P ocean availability and support the idea that an early ocean dominated by small particles was nutrient rich due to the inefficient removal of P to sediments. The results also suggest that extremely low oxygen concentrations in the shelf can coexist with an oxygenated deep open ocean for realistic values of zrem, especially for large values of the small-particle zrem. This could challenge conventional interpretations that the Proterozoic deep ocean was anoxic, which are derived from shelf and slope sediment redox data. This simple and computationally inexpensive model is a promising tool to investigate the impact of changes in the organic matter sinking and remineralization rates as well as changes in physical processes coupled with the biological pump in a variety of case studies.

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Keene, Samuel, William Gaieck, Anni Zhang, Houman Yaghoubi, Jingyuan Liu, Rohini Bala Chandran, Chengxiang("CX") Xiang, Adam Z. Weber, and Shane Ardo. "(Invited) Understanding Redox Shuttle Photocatalysis in Z-Scheme Solar Water Splitting Reactors." ECS Meeting Abstracts MA2018-01, no. 31 (April 13, 2018): 1890. http://dx.doi.org/10.1149/ma2018-01/31/1890.

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Particle suspension reactors for solar water splitting are capable of generating hydrogen at a cost that is competitive with hydrogen produced from steam methane reforming.1-3 Our team has validated a reactor design that resembles Nature’s Z-scheme where two stacked and connected photocatalyst particle suspension reactor beds together drive overall solar water splitting.3 Electron (and proton) management between the beds occurs by transport of a redox shuttle through a nanoporous separator. Efficient designs require that the redox shuttle is selectively oxidized and reduced at the particles that drive H2 evolution and O2 evolution, respectively. By device physics numerical simulations we showed that even for highly efficient reactor designs (10% STH efficiency) redox shuttle transport between the beds can be sustained with only passive diffusion.3 In my presentation I will report on our team’s recent progress on this design. Using finite-element numerical analyses we modelled and simulated the transient mass transport processes, light absorption, electrochemical kinetics, gas crossover, and thermal transport in the proposed reactor. Experimentally, we synthesized, characterized, and evaluated the photo(electro)chemical performance of the most promising photocatalyst nanocrystallites (BiVO4, WO3, and Rh-doped SrTiO3) as mesoporous thin films and as particles in model reactors, and in the presence of several different redox shuttles and at various pH values. For H2-evolving Rh-doped SrTiO3, we demonstrated that in the presence of Fe(II) the limiting rate of Fe(III) reduction decreases and the rate of H2 evolution increases; however, these desired processes occurred along with undesired Fe(III) reduction and undesired H2 oxidation. Introduction of Ru cocatalysts enhanced performance by increasing the rate of H2 evolution and to a lesser extent undesired Fe(III) reduction. For O2-evolving WO3, we showed that O2 does not interfere with collection of electrons and that selectivity toward Fe(III) reduction is possible at moderate concentrations of Fe(III). Overall, results from several studies using a series of redox shuttles and photocatalyst particles will be presented. Collectively, our efforts represent strides toward achieving a high-level of techno-economic viability in solar water splitting reactors. Acknowledgments: This work was supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies Incubator Program under Award No. DE-EE0006963 and Lawrence Berkeley National Laboratory under Contract No. DE-AC02-05CH11231. References: D. James, G. N. Baum, J. Perez and K. N. Baum, Technoeconomic Analysis of Photoelectrochemical (PEC) Hydrogen Production, Directed Technologies Inc., (US DOE Contract no. GS-10F-009J), Arlington, VA, 2009. A. Pinaud, J. D. Benck, L. C. Seitz, A. J. Forman, Z. Chen, T. G. Deutsch, B. D. James, K. N. Baum, G. N. Baum, S. Ardo, H. Wang, E. Miller, and T. F. Jaramillo, Energy & Environmental Science, 2013, 6, 1983–2002. Bala Chandran, S. Breen, Y. Shao, S. Ardo, and A. Z. Weber, Energy & Environmental Science, 2017, Accepted Manuscript, DOI: 10.1039/C7EE01360D.

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Takahashi, Kazuma, Shun Yokoyama, Takatoshi Matsumoto, Jhon L. Cuya Huaman, Hisashi Kaneko, Jean-Yves Piquemal, Hiroshi Miyamura, and Jeyadevan Balachandran. "Towards a designed synthesis of metallic nanoparticles in polyols – elucidation of the redox scheme in a cobalt–ethylene glycol system." New Journal of Chemistry 40, no. 10 (2016): 8632–42. http://dx.doi.org/10.1039/c6nj01738j.

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47

Yamashita, Yutaro, Shohei Tashiro, Yoshiki Ishii, Takayuki Uchihashi, Nobuyuki Matsushita, Ryou Kubota, and Mitsuhiko Shionoya. "Shape-selective one-step synthesis of branched gold nanoparticles on the crystal surface of redox-active Pd^II-macrocycles." Dalton Transactions 51, no. 4 (2022): 1318–24. http://dx.doi.org/10.1039/d1dt03973c.

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Redox-active PdII3-macrocycle crystals were found to provide an excellent platform for gold reduction and growth of immobilized particles, leading to the one-step synthesis of stable, monodisperse, Konpeito-shaped gold nanoparticles.

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Chen, Jingyuan, Xiangdong Zeng, Koichi Aoki, and Toyohiko Nishiumi. "Voltammetry of Suspensions of Polyaniline-coated Graphene Composites." International Journal of Chemistry 7, no. 2 (July 16, 2015): 1. http://dx.doi.org/10.5539/ijc.v7n2p1.

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Flaky particles of polyaniline (PANI)-graphene (GN) with rectangular size of 1.0-1.5 mm are dispersed in aqueous solution so that their suspension is stable for one day without aggregation. The weight fraction of PANI in the particle is 75 %, which is independent of the loaded fraction of PANI in the synthesis. The PANI-GN film made of the suspension forms a self-standing, elastic, conductive film. The PANI-GN suspension exhibits both the reduction and the oxidation waves at potentials similar to those of PANI adsorbed on an electrode, whereas the PANI-GO suspension shows only the voltammetric reduction wave. The redox peak currents are controlled by diffusion of PANI-GN flakes. The PANI-GN film cast on the electrode shows voltammetric peaks for PANI, of which redox charge is larger than that of the electrochemically polymerized PANI film with the common weight of PANI. This fact can be explained in terms of the electrochemically exhaustive oxidation of PANI through the electric conduction of GN.

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Boiko, M., and T. Boiko. "A new class of reinforcing additives for polymer composite materials." Journal of Physics: Conference Series 2131, no. 4 (December 1, 2021): 042029. http://dx.doi.org/10.1088/1742-6596/2131/4/042029.

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Abstract The work is devoted to the development of a method for obtaining new environmentally friendly reinforcing additives for polymer composite materials - xerogels of mixed oxides of transition metals. A method for obtaining nanosized particles of iron and manganese xerogels from true solutions by particle coarsening as a result of a redox reaction has been investigated. The use of sol-gel technology made it possible to obtain xerogels containing particles with a spinel structure. Cationic, anionic, and neutral water-soluble polymers were used to stabilize particle sizes during synthesis. The fractional composition of xerogel nanoparticles has been investigated. It is shown that when using cationic polymers, spinels are formed with the smallest particle sizes and a narrow dispersion of the size distribution. The obtained nanosized transition metal oxides with a spinel structure are planned to be used for reinforcing composite polymer materials in order to improve the mechanical and tribotechnical properties of the composites. Modification of phenylone with ultradispersed spinel particles makes it possible to increase the tribological characteristics of composites due to the formation of a friction film on the tribocontact as a result of the specific interaction of reinforcing additives with friction surfaces. The proposed method for the synthesis of reinforcing additives is characterized by simplicity of implementation, availability of reagents, high productivity and good repeatability of results.

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Li, Hao, Zhenming Cao, Jiayao Lin, Hui Zhao, Qiaorong Jiang, Zhiyuan Jiang, Honggang Liao, Qin Kuang, and Zhaoxiong Xie. "Synthesis of u-channelled spherical Fex(CoyNi1−y)100−x Janus colloidal particles with excellent electromagnetic wave absorption performance." Nanoscale 10, no. 4 (2018): 1930–38. http://dx.doi.org/10.1039/c7nr06956a.

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