Redox Treatment Research Articles

Unveiling therapeutic avenues targeting xCT in head and neck cancer.

Head and neck cancer (HNC) remains a major global health burden, prompting the need for innovative therapeutic strategies. This review examines the role of the cystine/glutamate antiporter (xCT) in HNC, specifically focusing on how xCT contributes to cancer progression through mechanisms such as redox imbalance, ferroptosis, and treatment resistance. The central questions addressed include how xCT dysregulation affects tumor biology and the potential for targeting xCT to enhance treatment outcomes. We explore recent developments in xCT-targeted current and emerging therapies, including xCT inhibitors and novel treatment modalities, and their role in addressing therapeutic challenges. This review aims to provide a comprehensive analysis of xCT as a therapeutic target and to outline future directions for research and clinical application.

Metal redispersion strategy for regeneration of sepiolite derived Co-phyllosilicate catalyst during glycerol steam reforming

Metal sintering and coke deposition have become main and irreversible obstacles for catalyst deactivation during H2 production from glycerol steam reforming (GSR). The regenerability of 15Co/SEP catalyst with a phyllosilicate derived strong metal-support interaction (SMSI) was probed by five successive GSR/regeneration cycles in order to evaluate the deactivation process and initial reactivity recovery. Two different regeneration methods were selected for the cycles: redox regeneration and combined regeneration. After the combined regeneration, reproducible GSR behaviors were obtained among the whole cycles. An almost recovery of initial activity (∼94 % of conversion and ∼ 73 % of H2 yield) and 50 h stability was noticed at 15Co/SEP-5 catalyst. By various characterizations analysis of fresh and spent catalysts, it was observed that irreversible metal sintering was aggravated by the redox regeneration, thus provoked initial activity loss and accelerated coking deactivation tendency. The combined regeneration achieved phyllosilicate recrystallization and metal exsolution/redispersion by a combination of NH4F-HNO3 assisted recrystallization and redox treatments, which ensured a small increase in Co0 nanoparticle size (13.2 nm vs. 15.3 nm) and coke deposition (23.9 wt% vs. 27.3 wt%) and inconspicuous change in the C1 species selectivity. The results suggested that 15Co/SEP catalyst is a promising candidate for commercialized GSR due to the favorable regenerability.

Catalytic particles formation from thin nickel films for the synthesis of multi-walled carbon nanotubes

We have investigated the formation of a catalyst for the synthesis of multi-walled carbon nanotubes (MWCNT) using nickel-on-titanium thin films. Nickel decomposes into nanoparticles in the synthesis setup prior to MWCNT growing through the plasma enhanced chemical vapor deposition method. Oxidation and reduction of the catalyst are conducted to control the morphology of the formed nanoparticles array. In this case, the redox treatments required preventing the formation of silicides and Ti–Ni alloys are combined with the well-known effect of low-temperature disintegration (dewetting) of thin films. Detailed studies using a combination of Auger, atomic force, scanning (SEM), and transmission electron microscopy (TEM) show the interaction of metals on a silicon substrate, the influence of treatments parameters on the catalyst's state. The features and morphology of MWCNT synthesized on the obtained catalysts were studied via Raman spectroscopy, SEM and TEM. Overall, showing a link between the catalyst formation process and MWCNT growth, we demonstrate a technological and versatile method for controlling of nanotube growth for various applications.

Solid-State Electrochemical Thermal Switches with Large Thermal Conductivity Switching Widths.

Thermal switches that switch the thermal conductivity (κ) of the active layers are attracting increasing attention as thermal management devices. For electrochemical thermal switches, several transition metal oxides (TMOs) are proposed as active layers. After electrochemical redox treatment, the crystal structure of the TMO is modulated, which results in the κ switching. However, the κ switching width is still small (<4W m-1 K-1). In this study, it demonstrates that LaNiOx-based solid-state electrochemical thermal switches have a κ switching width of 4.3W m-1 K-1. Fully oxidized LaNiO3 (on state) has a κ of 6.0W m-1 K-1 due to the large contribution of electron thermal conductivity (κele, 3.1W m-1 K-1). In contrast, reduced LaNiO2.72 (off state) has a κ of 1.7W m-1 K-1 because the phonons are scattered by the oxygen vacancies. The LaNiOx-based electrochemical thermal switch is cyclable of κ and the crystalline lattice of LaNiOx. This electrochemical thermal switch may be a promising platform for next-generation devices such as thermal displays.

Influence of redox treatments on the low-temperature water gas shift reaction over Pt/CeO2 catalysts

H2 reducing pretreatment at 500 °C promotes the activity of low-Pt-content Pt/CeO2 catalysts by increasing the number of active Pt0 NPs. A 12 h oxidative post-treatment at 500 °C which forms PtOx species easily activated also leads to improvement.

Generation of Subnanometer Metal Clusters in Silicoaluminate Zeolites as Bifunctional Catalysts.

Zeolite-encapsulated subnanometer metal catalysts are an emerging class of solid catalysts with superior performances in comparison to metal catalysts supported on open-structure solid carriers. Currently, there is no general synthesis methodology for the encapsulation of subnanometer metal catalysts in different zeolite structures. In this work, we will show a general synthesis method for the encapsulation of subnanometer metal clusters (Pt, Pd, and Rh) within various silicoaluminate zeolites with different topologies (MFI, CHA, TON, MOR). The successful generation of subnanometer metal species in silicoaluminate zeolites relies on the introduction of Sn, which can suppress the migration of subnanometer metal species during high-temperature oxidation-reduction treatments according to advanced electron microscopy and spectroscopy characterizations. The advantage of encapsulated subnanometer Pt catalysts in silicoaluminate zeolites is reflected in the direct coupling of ethane and benzene for production of ethylbenzene, in which the Pt and the acid sites work in a synergistic way.

Unveiling the self-activation of exsolved LaFe0.9Ru0.1O3 perovskite during the catalytic total oxidation of propane

The exsolution process enables to produce and control the formation of stable and catalytically active nano particles via reductive extraction of uniformly incorporated precious metal ions from a solid oxide solution. Here we consider the simple and stable perovskite LaFeO3 (LFO) where 10% of Fe on B sites are substituted by ruthenium (LFRO). Hydrogen reduction of LFRO at 800 °C leads to the formation of socketed ruthenium particles whose low-temperature activity in the total propane oxidation reaction at 210 °C is substantially lower than that of the original LFRO. Upon increasing the reaction temperature once to 400 °C, the exsolved catalyst undergoes self-activation so that the activity at 210 °C turns out to be five times higher than that of the original LFRO. High-resolution transmission electron microscopy and nanometer-resolved element mapping, together with averaging characterization methods, including X-ray diffraction and X-ray photoelectron spectroscopy, Raman spectroscopy, and diffuse infrared spectroscopy, unveil that after reduction at 800 °C the exsolved Ru particles are slightly alloyed with Fe and encapsulated by an inert and protecting LaOx layer. Mild oxidative treatment at 400 °C leads to the removal of the conforming LaOx layer, while the uncovered RuFe alloy particle transforms to catalytically active oxidic Ru species, with no indication of a separate FeOx phase. We exemplify with our case study of LaFe0.9Ru0.1O3 that careful redox treatment enables to control the exsolution process and to avoid deactivation. This may be of importance for the whole class of exsolvable materials.

Labile carbon-induced soil organic matter turnover in a subtropical forest under different redox conditions

Labile organic carbon (LOC) input strongly affects soil organic matter (SOM) dynamics, including gains and losses. However, it is unclear how redox fluctuations regulate these processes of SOM decomposition and formation induced by LOC input. The objective of this study was to explore the impacts of LOC input on SOM turnover under different redox conditions. Soil samples were collected in a subtropical forest. A single pulse of 13C-labeled glucose (i.e., LOC) was applied to the soil. Soil samples were incubated for 40 days under three redox treatments, including aerobic, anoxic, and 10-day aerobic followed by 10-day anoxic conditions. Results showed that LOC input affected soil priming and 13C-SOM accumulation differently under distinct redox conditions by altering the activities of various microorganisms. 13C-PLFAs (phospholipid fatty acids) were analyzed to determine the role of microbial groups in SOM turnover. Increased activities of fungi and gram-positive bacteria (i.e., the K-strategists) by LOC input could ingest metabolites or residues of the r-strategists (e.g., gram-negative bacteria) to result in positive priming. Fungi could use gram-negative bacteria to stimulate priming intensity via microbial turnover in aerobic conditions first. Reduced activities of K-strategists as a result of the aerobic to anoxic transition decreased priming intensity. The difference in LOC retention in SOM under different redox conditions was mainly attributable to 13C-particulate organic carbon (13C-POC) accumulation. Under aerobic conditions, fungi and gram-positive bacteria used derivatives from gram-negative bacteria to reduce newly formed POC. However, anoxic conditions were not conducive to the uptake of gram-negative bacteria by fungi and gram-positive bacteria, favoring SOM retention. This work indicated that redox-regulated microbial activities can control SOM decomposition and formation induced by LOC input. It is extremely valuable for understanding the contribution of soil affected by redox fluctuations to the carbon cycle.

Reversible Transformations of Palladium–Indium Intermetallic Nanoparticles upon Repetitive Redox Treatments in H2/O2

The transformations of chemical states and structures occurring in the PdIn/Al2O3 catalyst upon redox treatments in different gaseous atmospheres at different temperatures are addressed by an assortment of in situ bulk- (XRD) and surface-sensitive (XPS and DRIFTS CO) techniques. Any desired state of the catalyst between two opposite extremes of highly dispersed oxide species and regularly ordered PdIn intermetallic compound could be set in fully controlled and reversible ways by selecting appropriate conditions for the reductive treatment starting from the fully oxidized state. Since mutual conversions of multi-atomic Pdn centers into single-site Pd1 centers are involved in these transformations, the methodology could be used to find an optimum balance between the activity and selectivity of the catalytic system.

Oxygen vacancy enhanced magnetic heating efficiency of ferrite nanoparticles for self-regulating temperature hyperthermia

Precise and controllable temperature is required for using magnetic hyperthermia in cancer therapy. Magnetic nanoparticles typically need to have a Curie temperature of 42–50 °C to self-regulate hyperthermia temperature via magnetic phase transition. For now, the most studied iron oxide nanoparticles are not suitable for self-regulating hyperthermia applications due to their high Curie temperature of several hundred Celsius degrees. Doping nonmagnetic metal ions into iron oxide nanoparticles is an effective way to decrease Curie temperature, but often leads to low saturation magnetization and poor magnetic heating efficiency, limiting its usage in hyperthermia applications. Magnetic nanoparticles with excellent magnetic heating efficiency and suitable Curie temperature are highly desirable. This paper proposes an approach for enhancing magnetic heating efficiency by regulating oxygen vacancy concentration. Mn0.46Zn0.54Al0.25Fe1.75O4 nanoparticles with Curie temperature at 44.5 °C are prepared by co-precipitation method. Effective regulation of oxygen vacancy concentrations is achieved through hydrogen peroxide oxidation and carbothermal reduction treatments. Research results suggest that increasing oxygen vacancies significantly enhance the magnetism due to the transformation of magnetic couplings on nanoparticles, while barely affecting the Curie temperature. These nanoparticles exhibit high magnetic heating efficiency under an alternating magnetic field, almost 1.5 times of clinical-grade iron oxide nanoparticles, and can self-regulate hyperthermia temperature at 48–49 °C. This work may provide some references for further research on self-regulating temperature magnetic hyperthermia.

RETRACTED: The Effect of Treatment Temperature on Microstructure and Mechanical Behavior of a Fine-Grained YSZ–NiO(Ni) Anode Material

Reduction–oxidation (redox) cycling of a solid oxide fuel cell (SOFC) due to leakage of a fuel or standby and shutdown cycling is an issue that has attracted the attention of many research groups for a long time. The researchers mainly note the harmful effects of redox cycling on the microstructure of SOFC constituents and search for ways to mitigate or diminish them. The purpose of this study was to use reduction and oxidation stages in an appropriate mode as a positive preconditioning to improve redox cycling stability of Ni-containing SOFC anode materials. The redox treatment was applied to YSZ–NiO(Ni) anode substrate specimens at 600 °C and 800 °C. The mechanical tests (flexural strength, microhardness, and fracture toughness) were performed on these specimens and the results were compared to those for as-sintered and one-time reduced specimens. Microstructure and fracture surface morphology of material in corresponding modes were analyzed. The main findings were summarized as follows: (i) Redox treatment at 600 °C provides an increase in flexural strength and electrical conductivity of YSZ–NiO(Ni) anode cermets; (ii) the treatment at 800 °C causes formation of a gradient microstructure with lateral cracks that result in a significant decrease in flexural strength; (iii) the mode of redox treatment at 600 °C for 4 h in Ar–5% H2/air atmosphere provides an increase in flexural strength of YSZ–NiO(Ni) anode cermets (up to 127 ± 4 MPa), while electrical conductivity was provided at a comparatively high level (7 × 105 S/m).

Solid‐State Electrochemical Thermal Transistors (Adv. Funct. Mater. 19/2023)

Thermal Transistors In article number 2214939, Hiromichi Ohta and co-workers demonstrate solid-state thermal transistors that control the thermal conductivity (κ) of strontium cobaltite by electrochemical redox treatment. Oxidized SrCoO3 shows a higher κ of 3.8 W m−1 K−1 while reduced SrCoO2 shows a lower κ of 0.95 W m−1 K−1. The on/off ratio is 4, and it plays like the shutter of heat flow.

Trace to the Source: Self‐Tuning of MOF Photocatalysts

AbstractBenefitting from ultra‐high porosity, large specific surface area (SSA), and rich active sites, metal–organic frameworks (MOFs) have emerged as a star material in energy and environment related applications, especially in photocatalysis. In comparison with conventional photocatalysts, MOFs can be customized in terms of electronic structure, photo‐responsiveness, and morphological dimensions by rational design, which means that MOFs eliminate the need for other species to achieve enhanced photocatalytic performance, such as metals, compounds, and polymers, which may introduce extra costs, be time‐consuming, be multi‐phase, or have an unclear mechanism. Most previous review works related to MOF photocatalysis have mixed self‐tuning and assisted‐tuning, which often gives an incomplete understanding. In this work, the self‐tunning of MOFs by analyzing component (as clusters, ligands, and inclusions), defect (defect engineering, as linkers, clusters, and oxygen vacancies (OVs), and crystal (as facets, dimensions, and amorphization) is summarized. Then, outstanding examples of these strategies applied to water redox, CO2/N2 reduction, organic conversion, and environmental treatment are discussed. Finally, the opportunities and challenges faced in the self‐tuning of MOFs are analyzed from different perspectives. This paper is a comprehensive and systematic review on the self‐tuning of MOFs to enhance photocatalytic activity.

Structure Micro- and Nanomodification by Cyclic Oxidation-Reduction Treatment of Porous Nickel Sintered Using a Space Holder

Structure Micro- and Nanomodification by Cyclic Oxidation-Reduction Treatment of Porous Nickel Sintered Using a Space Holder

AJICAP Second Generation: Improved Chemical Site-Specific Conjugation Technology for Antibody-Drug Conjugate Production.

The site-directed chemical conjugation of antibodies remains an area of great interest and active efforts within the antibody-drug conjugate (ADC) community. We previously reported a unique site modification using a class of immunoglobulin-G (IgG) Fc-affinity reagents to establish a versatile, streamlined, and site-selective conjugation of native antibodies to enhance the therapeutic index of the resultant ADCs. This methodology, termed "AJICAP", successfully modified Lys248 of native antibodies to produce site-specific ADC with a wider therapeutic index than the Food and Drug Administration-approved ADC, Kadcyla. However, the long reaction sequences, including the reduction-oxidation (redox) treatment, increased the aggregation level. In this manuscript, we aimed to present an updated Fc-affinity-mediated site-specific conjugation technology named "AJICAP second generation" without redox treatment utilizing a "one-pot" antibody modification reaction. The stability of Fc affinity reagents was improved owing to structural optimization, enabling the production of various ADCs without aggregation. In addition to Lys248 conjugation, Lys288 conjugated ADCs with homogeneous drug-to-antibody ratio of 2 were produced using different Fc affinity peptide reagent possessing a proper spacer linkage. These two conjugation technologies were used to produce over 20 ADCs from several combinations of antibodies and drug linkers. The in vivo profile of Lys248 and Lys288 conjugated ADCs was also compared. Furthermore, nontraditional ADC production, such as antibody-protein conjugates and antibody-oligonucleotide conjugates, were achieved. These results strongly indicate that this Fc affinity conjugation approach is a promising strategy for manufacturing site-specific antibody conjugates without antibody engineering.

Synthesis and Characterization of Stable Cu-Pt Nanoparticles under Reductive and Oxidative Conditions.

We report a synthesis method for highly monodisperse Cu-Pt alloy nanoparticles. Small and large Cu-Pt particles with a Cu/Pt ratio of 1:1 can be obtained through colloidal synthesis at 300 °C. The fresh particles have a Pt-rich surface and a Cu-rich core and can be converted into an intermetallic phase after annealing at 800 °C under H2. First, we demonstrated the stability of fresh particles under redox conditions at 400 °C, as the Pt-rich surface prevents substantial oxidation of Cu. Then, a combination of in situ scanning transmission electron microscopy, in situ X-ray absorption spectroscopy, and CO oxidation measurements of the intermetallic CuPt phase before and after redox treatments at 800 °C showed promising activity and stability for CO oxidation. Full oxidation of Cu was prevented after exposure to O2 at 800 °C. The activity and structure of the particles were only slightly changed after exposure to O2 at 800 °C and were recovered after re-reduction at 800 °C. Additionally, the intermetallic CuPt phase showed enhanced catalytic properties compared to the fresh particles with a Pt-rich surface or pure Pt particles of the same size. Thus, the incorporation of Pt with Cu does not lead to a rapid deactivation and degradation of the material, as seen with other bimetallic systems. This work provides a synthesis route to control the design of Cu-Pt nanostructures and underlines the promising properties of these alloys (intermetallic and non-intermetallic) for heterogeneous catalysis.

Solid‐State Electrochemical Thermal Transistors

AbstractThermal transistors that electrically control heat flow have attracted growing attention as thermal management devices and phonon logic circuits. Although several thermal transistors are demonstrated, the use of liquid electrolytes may limit the application from the viewpoint of reliability or liquid leakage. Herein, a solid‐state thermal transistor that can electrochemically control the heat flow with an on‐to‐off ratio of the thermal conductivity (κ) of ≈4 without using any liquid is demonstrated. The thermal transistor is a multilayer film composed of an upper electrode, strontium cobaltite (SrCoOx), solid electrolyte, and bottom electrode. An electrochemical redox treatment at 280 °C in air repeatedly modulates the crystal structure and κ of the SrCoOx layer. The fully oxidized perovskite‐structured SrCoO3 layer shows a high κ ≈3 .8 W m−1 K−1, whereas the fully reduced defect perovskite‐structured SrCoO2 layer shows a low κ ≈ 0.95 W m−1 K−1. The present solid‐state electrochemical thermal transistor may become next‐generation devices toward future thermal management technology.

Achieving high-strength W/W-10Cu joints by vacuum diffusion bonding with FeCoCu interlayer

To obtain W/W-10Cu joints with reliable interface bonding, the surface of the W plate was roughened by oxidation–reduction treatment, and the treated W plate was joined to W-10Cu by vacuum diffusion bonding with FeCoCu medium-entropy alloy as an interlayer. The effects of oxidation temperature on the microstructure and properties of the W/W-10Cu joints were investigated. The stability of the obtained W/W-10Cu joints under transient thermal loads was investigated through thermal shock tests. The results show that the surface of the W plate became rough and loose after oxidation–reduction treatment. The surface roughness (Sa) of the W oxidised at 900 °C and then reduced in H2 at 850 °C was 1.833 μm. The W/W-10Cu joints prepared from this W had a maximum shear strength of 254.0 MPa, 60% higher than that of the W/W-10Cu joints prepared from untreated W (157.9 MPa). After 50 thermal shock tests at 600 °C–RT, the shear strength of the W/W-Cu joints prepared from the treated W oxidised at 900 °C was 111.6 MPa; the shear strength of the W/W-Cu joints prepared from untreated W was 42.7 MPa. This study provides an effective method for preparing high-strength W/W-10 Cu joints.

Hydroxyl adsorption derived reactive oxygen species from carbon paper-supported Cu2O for enhanced electrochemical glucose sensing

Engineered sensitive copper nanostructured superelectrode systems have become an important part of electrochemical sensing of glucose because of their high sensitivity, specificity, abundant natural reserves, and environmental friendliness. However, the factors affecting the electrochemical catalytic activity of glucose remain a challenging issue, which largely limits the overall electrochemical sensing performance of glucose. This paper reports the design of a carbon fiber loaded cuprous oxide nanoparticle (Cu2O NPs) electrochemical sensor with electrochemical catalytic properties for glucose oxidation. The copper grown on carbon nanofibers was subjected to cyclic redox treatment to obtain Cu2ONPs with good glucose detection ability. The detection range of the prepared Cu2ONPs was 0.05 mM − 3 mM with a sensitivity of 3 mA mM−1 cm−2. The differences in the properties of copper and cuprous oxide are analyzed in depth and the reasons for the variability are explored. By observing the electrocatalytic behavior and oxygen evolution reaction behavior of the glucose oxidation process, we hypothesized that the difference in the oxygen source provided by hydroxyl adsorption would lead to the difference in the properties of cuprous oxide and copper. Our proposed differences in the oxygen source generated by hydroxyl adsorption affecting the performance of glucose detection will provide new ideas for the design of glucose electrochemical microelectrodes.

Renovating phase constitution and construction of Pt nanocubes for electrocatalysis of methanol oxidation via a solvothermal-induced strong metal-support interaction

Strong metal-support interaction (SMSI) covering migration of reducible oxides from the support onto loaded metal surfaces and alloying of the guest metal with the metal component in the support displays important roles in tuning catalytic behavior. While conventional construction of SMSI involves high-temperature redox treatment and cannot ensure simultaneous appearance of oxide migration and alloying mechanisms, limiting the function and application of SMSI in electrocatlysis. Herein, a low-temperature solvothermal-induced SMSI is established in the CeCuOx/C supported Pt system, where the partial encapsulation of supported Pt by CeOx and the alloying of Cu2+ in the substrate with guest Pt occur readily and simultaneously. Such encapsulation and alloying processes completely refurbish the catalysis configuration and restructure the geometric/electronic state of interfacial Pt atoms, endowing the CeOx/PtCu/CeCuOx/C product with modulated adsorption energies toward reactive intermediates and consequently much enhanced performance for methanol oxidation reaction (MOR).