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In pharmaceutical discovery, the "magic methyl" effect describes a substantial improvement in the pharmacological properties of a drug candidate with the incorporation of methyl groups. Therefore, to expedite the synthesis of methylated drug analogs, late-stage, undirected methylations of C(sp3)-H bonds in complex molecules would be valuable. However, current methods for site-selective methylations are limited to activated C(sp3)-H bonds. Here we describe a site-selective, undirected methylation of unactivated C(sp3)-H bonds, enabled by photochemically activated peroxides and a nickel(II) complex whose turnover is enhanced by an ancillary ligand. The methodology displays compatibility with a wide range of functional groups and a high selectivity for tertiary C-H bonds, making it suitable for the late-stage methylation of complex organic compounds that contain multiple alkyl C-H bonds, such as terpene natural products, peptides, and active pharmaceutical ingredients. Overall, this method provides a synthetic tool to explore the "magic methyl" effect in drug discovery.

OBJECTIVE: The study objective was to evaluate intraoperative experience with newly developed high-spatial-resolution microelectrode grids composed of poly(3,4-ethylenedioxythiophene) with polystyrene sulfonate (PEDOT:PSS), and those composed of platinum nanorods (PtNRs). METHODS: A cohort of patients who underwent craniotomy for pathological tissue resection and who had high-spatial-resolution microelectrode grids placed intraoperatively were evaluated. Patient demographic and baseline clinical variables as well as relevant microelectrode grid characteristic data were collected. The primary and secondary outcome measures of interest were successful microelectrode grid utilization with usable resting-state or task-related data, and grid-related adverse intraoperative events and/or grid dysfunction. RESULTS: Included in the analysis were 89 cases of patients who underwent a craniotomy for resection of neoplasms (n = 58) or epileptogenic tissue (n = 31). These cases accounted for 94 grids: 58 PEDOT:PSS and 36 PtNR grids. Of these 94 grids, 86 were functional and used successfully to obtain cortical recordings from 82 patients. The mean cortical grid recording duration was 15.3 ± 1.15 minutes. Most recordings in patients were obtained during experimental tasks (n = 52, 58.4%), involving language and sensorimotor testing paradigms, or were obtained passively during resting state (n = 32, 36.0%). There were no intraoperative adverse events related to grid placement. However, there were instances of PtNR grid dysfunction (n = 8) related to damage incurred by suboptimal preoperative sterilization (n = 7) and improper handling (n = 1); intraoperative recordings were not performed. Vaporized peroxide sterilization was the most optimal sterilization method for PtNR grids, providing a significantly greater number of usable channels poststerilization than did steam-based sterilization techniques (median 905.0 [IQR 650.8-935.5] vs 356.0 [IQR 18.0-597.8], p = 0.0031). CONCLUSIONS: High-spatial-resolution microelectrode grids can be readily incorporated into appropriately selected craniotomy cases for clinical and research purposes. Grids are reliable when preoperative handling and sterilization considerations are accounted for. Future investigations should compare the diagnostic utility of these high-resolution grids to commercially available counterparts and assess whether diagnostic discrepancies relate to clinical outcomes.

This study aimed to clinically evaluate the effectiveness of two different at-home whitening protocols and to determine which is more effective: applying the whitening gel (16% carbamide peroxide) every 24 hours (Group A) or every 48 hours (Group B) for 2 weeks. Group C received a placebo gel (glycerin) without peroxide, which was applied every 24 hours for 2 weeks. The differences in terms of tooth sensitivity were also analyzed. A sample of 60 patients was divided into three groups of 20 patients. To compare the groups, color measurements were made using a spectrophotometer, and Student t test was used for independent samples. The confidence level was set at 95% (P ≤ .05). No statistically significant differences were found between Groups A and B (P > .05). The study concluded that 16% carbamide peroxide was equally effective when applied with either protocol and obtained the same results, but the 48-hour application protocol produced less sensitivity than the 24-hour application protocol. [ABSTRACT FROM AUTHOR]

The α-oxyalkylation of aryl chlorides with ethers and alcohols using a small amount of a peroxide was found to be induced by photoirradiation. The reaction proceeds through a homolytic aromatic substitution (HAS) mechanism consisting of addition of an α-oxyalkyl radical to an aryl chloride and elimination of the chlorine atom to give the α-oxyalkylation product, where photoirradiation is considered to effect not only the initiation step to facilitate homolysis of a peroxide, but also the propagating radical chain. [ABSTRACT FROM AUTHOR]

[Display omitted] Hydrogen peroxide (H 2 O 2) emerges as a viable oxidant for fuel cells, necessitating the development of an efficient and cost-effective electrocatalyst for the hydrogen peroxide reduction reaction (HPRR). In this study, we synthesized a self-supporting, highly active HPRR electrocatalyst comprising two morphologically distinct components: CeO 2 -NiCo 2 O 4 nanowires and CeO 2 -NiCo 2 O 4 metal organic framework derivatives, via a two-step hydrothermal process followed by air calcination. X-ray diffraction and transmission electron microscopy analysis confirmed the presence of CeO 2 and NiCo 2 O 4 , revealing the amalgamated interface between them. CeO 2 exhibits multifunctionality in regulating the surface electronic configuration of NiCo 2 O 4 , fostering synergistic connections, and introducing oxygen deficiencies to enhance the catalytic efficacy in HPRR. Electrochemical measurements demonstrate a reduction current density of 789.9 mA·cm−2 at −0.8 V vs. Ag/AgCl. The assembly of direct borohydride-hydrogen peroxide fuel cell (DBHPFC) exhibits a peak power density of 45.2 mW·cm−2, demonstrating durable stability over a continuous operation period of 120 h. This investigation providing evidence that the fabrication of heterostructured catalysts based on CeO 2 for HPRR is a viable approach for the development of high-efficiency electrocatalysts in fuel cell technology. [ABSTRACT FROM AUTHOR]

Background: Although important information concerning COVID-19 vaccination is available, the effects of the CoronaVac and ChadOx-1 vaccines on immunity and the redox balance in the upper airway mucosa of the aged population are not fully understood. Therefore, the aim of this study was to investigate the impacts of two doses of the CoronaVac or ChadOx-1 vaccine on immune/inflammatory responses and oxidative stress in the airway mucosa of older adults. Methods: Seventy-six older adults of both sexes, with a mean age of 75.1 ± 6.4 years, were separated according to vaccination status into the CoronaVac (n = 52) and ChadOx-1 (n = 24) groups. Saliva samples were collected before (pre) and 30 days after (post) the administration of the second dose of the CoronaVac or ChadOx-1 vaccine to assess the levels of antibodies (sIgA and IgG), antimicrobial peptides, cytokines, and oxidant/antioxidant agents. Results: The immunogenicity in the ChadOx-1 group was 37.5% for sIgA and 25% for IgG, while that in the CoronaVac group was 18.9% for sIgA and 13.2% for IgG. Intergroup analysis revealed that (1) lower levels of IFN-α, IFN-γ, and IL-10 and a greater IFN-γ/IL-10 ratio, in addition to a greater IL-6/IL-10 ratio, were found in both the pre- and postvaccination periods, and (2) lower levels of total sIgA, IL-12p70, IL-17A, TNF-α, and the IL-12p70/IL-10 ratio, in addition to higher levels of specific sIgA for SARS-CoV-2 antigens and lysozyme, were observed only in the postvaccination period in the ChadOx-1 group than in the CoronaVac group. Intragroup analysis revealed (1) a significant increase in the salivary levels of total peroxides in the postvaccination period compared to those in the prevaccination period in both volunteer groups; (2) a decrease in the levels of lysozyme and the ratio between total antioxidant capacity (TAC) and total peroxides in the postvaccination period in the CoronaVac group compared with those in the prevaccination period; and (3) decreases in the TNF-α, IL-6, and IL-12p70 levels, and the IL-12p70/IL-10 ratio in the ChadoX-1 group, as well as a higher lactoferrin concentration in the postvaccination period than in the prevaccination period. Several positive and negative correlations between the parameters assessed here were found. Conclusions: In general, the ChadOx-1 group exhibited improvements in both immune/inflammatory responses and redox balance and greater immunogenicity than did the CoronaVac group. [ABSTRACT FROM AUTHOR]

Fenugreek extracts have remarkable antioxidant properties and can be used as natural preservatives for products containing a large amount of oil, such as mayonnaise. In this study, mayonnaise was enriched with phenolic extracts of fenugreek seeds (FSE) and fenugreek leaves (FLE), and the quality attributes of the enriched mayonnaises were investigated during storage. FSE and FLE were added to mayonnaise at three different levels (0.05, 0.10, and 0.20%), and the samples were stored at 4°C for 12 weeks and at 25°C for 6 weeks. Antioxidant activity, peroxide value, titratable acidity, color change, and microbial and sensory analysis were performed. As a result, enrichment of mayonnaise with FSE and FLE improved its quality properties during storage. The antioxidant activities of the added FSE and FLE samples were preserved ∼87% and ∼47% at 4°C, and 81% and ∼27% at 25°C, respectively. Furthermore, the increase in the peroxide values of the enriched mayonnaise with extracts during storage was less than that of the added synthetic antioxidant (EDTA) samples. The highest total color change (ΔE) was observed for FLE‐added samples for all levels of addition. Multifactorial ANOVA showed significant effects (p < 0.05) of type and concentration of additives, storage time, and their interactions on antioxidant activity, peroxide value, titratable acidity, and color change at both storage temperatures (4°C and 25°C). R2 and adj‐R2 values indicated highly accurate models for all parameters. The addition of FLE and FSE at the highest level (0.20%) prevented the growth of total aerobic mesophilic bacteria by 2.1 and 3.2 logs and the growth of total yeast/mold by 1.0 and 1.3 logs at 25°C, respectively. Sensory attributes (color, odor, taste, texture, and general acceptance) of the mayonnaises added to FSE and FLE had higher scores than the control sample at the end of storage. [ABSTRACT FROM AUTHOR]

U(VI) peroxides are important within the nuclear fuel cycle, but reactive oxygen species (ROS) can form upon oxidation. Herein, we identified the spectral signatures of a U(VI) diperoxosuperoxide complex (KUPS-1) and observed that the transformation of U(VI) triperoxide (KUT-1) to superoxide forms occurred with trace-level Cr. U(VI) superoxide complexes were identified in EPR solution spectra without the use of spin-traps. [ABSTRACT FROM AUTHOR]

Simple Summary: Treatment options for patients with advanced renal cancer are limited, as one of the main methods, chemotherapy, is prone to drug resistance in the course of treatment. There have been numerous studies confirming that ferroptosis is involved in the development of renal cancer and drug resistance during treatment. In this review, we provide new insights into the resistance of classical chemotherapy drugs sorafenib and sunitinib in renal cancer and explore the mechanism of different types of ferroptosis-related drugs to treat renal cancer, such as herb extract medicine, ferroptosis inducers, natural compounds, nanomaterials, etc. We have also conducted an in-depth discussion on the application of ferroptosis-related drugs in the clinical treatment of renal cancer. Renal cancer is a common and serious malignant tumor of the urinary system. While surgery effectively treats early-stage renal cancer, advanced cases pose a significant challenge due to poor treatment outcomes and chemotherapy resistance. Therefore, there is an urgent need to develop alternative therapeutic strategies. Ferroptosis is a newly defined form of programmed cell death characterized by the accumulation of iron-dependent lipid peroxides, which plays a critical role in tumor progression and drug resistance. Recent studies have shown that ferroptosis is involved in the occurrence and development of renal cancer, and ferroptosis-related genes can induce cell apoptosis and can be used as potential biomarkers for early diagnosis of renal cancer and participate in drug resistance of renal cancer chemotherapy. With the continuous improvement of the mechanism of ferroptosis, drugs targeting ferroptosis for the treatment of renal cancer are emerging in an endless stream. Based on the theoretical basis of the occurrence of ferroptosis, this paper reviewed drug-induced ferroptosis in renal cancer cells from the aspects of herbal medicine, natural compounds, drug resistance mechanisms, and nanomaterials, and delves into the clinical application potential of ferroptosis-related drugs in the treatment of renal cancer. [ABSTRACT FROM AUTHOR]

In the present work, the calibration dependencies for the M062X (i=1),B3LYP (i=2), wB97XD (i=3), M08HX (i=4), MN15 (i=5), G3B3 (i=6) and CBS‐QB3 (i=7) and several other modeling approaches are determined using the calculated values of ΔraHo of atomization and literature based values of ΔraHo(X,TAB) of 14 reference peroxides. These calibration dependencies are used for the determination of ΔraHo(X,CORRP)i and ΔfHo(X,CORRP)i of other peroxides. The coordination of values of ΔfHo(X,CORRP)i (i=1–7) by the intersection of their 3σPi intervals is used for the determination of the most consistent values of ΔfHo(X,MEANP). These values of ΔfHo(X,MEANP) are used for the determination of BDE of peroxides. It's demonstrated that the calculated and literature values of BDE are in agreement. Among the considered modeling approaches, the lowest uncertainties (σPi) are determined for the G3B3 (3.1 kJ/mol), CBS‐QB3 (4.1 kJ/mol), and M062X/6‐311++G(d,p) (6.1 kJ/mol) approaches. [ABSTRACT FROM AUTHOR]

Background: To predict the long-term performance of restorative materials in the oral environment, it is important to evaluate their resistance to chemical and mechanical degradation and to know the toxic potential of the type and amount of ions eluted from the filling material. In this study, home bleaching was applied to dental materials with different contents and it was aimed to determine the type and amount of ions released from these materials. Methods: In this study, amalgam, posterior composite resin, anterior composite resin, bulk fill composite resin, indirect composite resin, hybrid ceramic and all-ceramic were used as restorative materials. 10 specimens of each material were prepared according to the manufacturer's instructions. Each material group was divided into two subgroups as the bleached group and the control group. After bleaching, all specimens were stored in 1 ml of 75% ethanol/water solution. Solutions were renewed after 1, 14 and 28 days. The type and amount of ions released from the materials were determined using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Data were analyzed using the Friedman, Wilcoxon Signed Ranks, and Mann-Whitney U tests (α = 0.05). Results: It was determined that the amount of ions release from the restorative materials decreased over time (p < 0.05). According to the results of the Mann-Whitney U test, there was no difference between the bleaching and control groups in most of the restorative materials (p > 0.05). Conclusion: Within the limits of this study, home bleaching system does not have a significant effect on ion release from restorative materials. [ABSTRACT FROM AUTHOR]

This report describes an environmentally benign synthesis of 1,2,3‐benzotriazines through an iodide‐catalyzed electro‐oxidative N‐centered [1,2]‐rearrangement of 3‐aminoindazoles. The developed method demonstrates the activation of heteroatoms via electrochemically generated reactive iodide species without using any metal catalysts and peroxides. The protocol features practical and mild reaction conditions and displays a wide substrate scope. Various mechanistic experiments and cyclic voltammetric studies have been instrumental in elucidating the reaction mechanism, operating via a skeletal rearrangement of 3‐aminoindazoles. [ABSTRACT FROM AUTHOR]

The literature data on the use of triphenylphosphine in determining peroxide functional groups and individual oxygen-containing compounds in the composition of the products of oxidation reactions of organic compounds with molecular oxygen and/or peroxides were systematized and discussed. The causes and mechanisms of distortions of the results of analytical determinations were identified and possible ways of their elimination were suggested. [ABSTRACT FROM AUTHOR]

The increasingly severe antibiotic pollution has become one of the most critical issues. In this study, a zinc peroxide/peroxymonosulfate (ZnO2/PMS) double-oxidation system was developed for tetracycline (TC) degradation. A small amount of ZnO2 (10 mg) and PMS (30 mg) could effectively degrade 82.8% of TC (100 mL, 50 mg/L), and the degradation process could be well described by the pseudo-second-order kinetic model. Meanwhile, the ZnO2/PMS double-oxidation system showed high adaptability in terms of reaction temperature (2–40 °C), initial pH value (4–12), common inorganic anions (Cl−, NO3−, SO42− and HCO3−), natural water source and organic pollutant type. The quenching experiment and electron paramagnetic resonance (EPR) characterization results confirmed that the main reactive oxygen species (ROS) was singlet oxygen (1O2). Moreover, three possible pathways of TC degradation were deduced according to the analyses of intermediates. On the basis of comparative characterization and experiment results, a synergistic activation mechanism was further proposed for the ZnO2/PMS double-oxidation system, accounting for the superior degradation performance. The released OH− and H2O2 from ZnO2 could activate PMS to produce major 1O2 and minor superoxide radicals (•O2−), respectively. [ABSTRACT FROM AUTHOR]

Malaria is a life‐threatening disease that affects tropical and subtropical regions worldwide. Various drugs were used to treat malaria, including artemisinin and derivatives, antibiotics (tetracycline, doxycycline), quinolines (chloroquine, amodiaquine), and folate antagonists (sulfadoxine and pyrimethamine). Since the malarial parasites developed drug resistance, there is a need to develop new chemical entities with high efficacy and low toxicity. In this context, 1,2,4,5‐tetraoxanes emerged as an essential scaffold and have shown promising antimalarial activity. To improve activity and overcome resistance to various antimalarial drugs; 1,2,4,5‐tetraoxanes were fused with various aryl/heteroaryl/alicyclic/spiro moieties (steroid‐based 1,2,4,5‐tetraoxanes, triazine‐based 1,2,4,5‐tetraoxanes, aminoquinoline‐based 1,2,4,5‐tetraoxanes, dispiro‐based 1,2,4,5‐tetraoxanes, piperidine‐based 1,2,4,5‐tetraoxanes and diaryl‐based 1,2,4,5‐tetraoxanes). The present review aims to focus on covering the relevant literature published during the past 30 years (1992–2022). We summarize the most significant in vitro, in vivo results and structure–activity relationship studies of 1,2,4,5‐tetraoxane‐based hybrids as antimalarial agents. The structural evolution of different hybrids can provide the framework for the future development of 1,2,4,5‐tetraoxane‐based hybrids to treat malaria. [ABSTRACT FROM AUTHOR]

Abstract Background Although important information concerning COVID-19 vaccination is available, the effects of the CoronaVac and ChadOx-1 vaccines on immunity and the redox balance in the upper airway mucosa of the aged population are not fully understood. Therefore, the aim of this study was to investigate the impacts of two doses of the CoronaVac or ChadOx-1 vaccine on immune/inflammatory responses and oxidative stress in the airway mucosa of older adults. Methods Seventy-six older adults of both sexes, with a mean age of 75.1 ± 6.4 years, were separated according to vaccination status into the CoronaVac (n = 52) and ChadOx-1 (n = 24) groups. Saliva samples were collected before (pre) and 30 days after (post) the administration of the second dose of the CoronaVac or ChadOx-1 vaccine to assess the levels of antibodies (sIgA and IgG), antimicrobial peptides, cytokines, and oxidant/antioxidant agents. Results The immunogenicity in the ChadOx-1 group was 37.5% for sIgA and 25% for IgG, while that in the CoronaVac group was 18.9% for sIgA and 13.2% for IgG. Intergroup analysis revealed that (1) lower levels of IFN-α, IFN-γ, and IL-10 and a greater IFN-γ/IL-10 ratio, in addition to a greater IL-6/IL-10 ratio, were found in both the pre- and postvaccination periods, and (2) lower levels of total sIgA, IL-12p70, IL-17A, TNF-α, and the IL-12p70/IL-10 ratio, in addition to higher levels of specific sIgA for SARS-CoV-2 antigens and lysozyme, were observed only in the postvaccination period in the ChadOx-1 group than in the CoronaVac group. Intragroup analysis revealed (1) a significant increase in the salivary levels of total peroxides in the postvaccination period compared to those in the prevaccination period in both volunteer groups; (2) a decrease in the levels of lysozyme and the ratio between total antioxidant capacity (TAC) and total peroxides in the postvaccination period in the CoronaVac group compared with those in the prevaccination period; and (3) decreases in the TNF-α, IL-6, and IL-12p70 levels, and the IL-12p70/IL-10 ratio in the ChadoX-1 group, as well as a higher lactoferrin concentration in the postvaccination period than in the prevaccination period. Several positive and negative correlations between the parameters assessed here were found. Conclusions In general, the ChadOx-1 group exhibited improvements in both immune/inflammatory responses and redox balance and greater immunogenicity than did the CoronaVac group.

The P450 enzyme CYP121 from Mycobacterium tuberculosis catalyzes a carbon-carbon (C-C) bond coupling cyclization of the dityrosine substrate containing a diketopiperazine ring, cyclo(l-tyrosine-l-tyrosine) (cYY). An unusual high-spin (S = 5/2) ferric intermediate maximizes its population in less than 5 ms in the rapid freeze-quenching study of CYP121 during the shunt reaction with peracetic acid or hydrogen peroxide in acetic acid solution. We show that this intermediate can also be observed in the crystalline state by EPR spectroscopy. By developing an on-demand-rapid-mixing method for time-resolved serial femtosecond crystallography with X-ray free-electron laser (tr-SFX-XFEL) technology covering the millisecond time domain and without freezing, we structurally monitored the reaction in situ at room temperature. After a 200 ms peracetic acid reaction with the cocrystallized enzyme-substrate microcrystal slurry, a ferric-hydroperoxo intermediate is observed, and its structure is determined at 1.85 Å resolution. The structure shows a hydroperoxyl ligand between the heme and the native substrate, cYY. The oxygen atoms of the hydroperoxo are 2.5 and 3.2 Å from the iron ion. The end-on binding ligand adopts a near-side-on geometry and is weakly associated with the iron ion, causing the unusual high-spin state. This compound 0 intermediate, spectroscopically and structurally observed during the catalytic shunt pathway, reveals a unique binding mode that deviates from the end-on compound 0 intermediates in other heme enzymes. The hydroperoxyl ligand is only 2.9 Å from the bound cYY, suggesting an active oxidant role of the intermediate for direct substrate oxidation in the nonhydroxylation C-C bond coupling chemistry.

Organic peroxides are key intermediates in the atmosphere but are challenging to detect, especially in the particle phase, due to their instability, which has led to substantial gaps in the understanding of their environmental effects. We demonstrate that matrix-assisted ionization in vacuum (MAIV) mass spectrometry (MS), which does not require an ionization source, enables in situ characterization of peroxides and other products in the surface layers of organic particles. Hydroxyl radical oxidation of glutaric acid particles yields hydroperoxides and organic peroxides, which were detected with signals of the same order of magnitude as the major, more stable products. Product identification is supported by MS/MS analysis, peroxide standards, and offline high-resolution MS. The peroxide signals relative to the stable carbonyl and alcohol products are significantly larger using MAIV compared to those in the offline bulk analysis. This is also the case for analysis using fast, online easy ambient sonic-spray ionization mass spectrometry. These studies demonstrate the advantage of MAIV for the real-time characterization of labile peroxides in the surface layers of solid particles. The presence of peroxides on the surface may be important for surface oxidation processes as well as for the toxicity of inhaled particles.

Taking iodine-peroxide and diphenyldiselelen ether as raw materials, dimethyl sulfoxide as solvent, ammonium iodide and potassium tert-butoxide as catalysts, C Se bond coupling was formed at room temperature, and 11 selenium aryl peroxides were synthesized. By using HNMR spectroscopy, CNMR spectroscopy and mass spectrometry, the products were characterized and analyzed separately. Through a series of control experiments, the reaction was determined to be ionic and the corresponding reaction mechanism was inferred. The results show that 11 selenium aryl peroxides are all yellow liquid. The yield is 68%~85%. [ABSTRACT FROM AUTHOR]

DOX/ZnO 2 @Zr-Ce6/Pt/PEG nanocomposites show excellent performance of amplifying the 1O 2 reaction through the dual channels of ZnO 2 and Pt nanoenymes, thus improving the antitumor effect of PDT. Furthermore, the generated O 2 can further enhance the sensitivity of tumor cells to chemotherapy by down-regulating the expression of hypoxia-inducible factor α. [Display omitted] • Successful construction of multifunctional DOX/ZnO 2 @Zr-Ce6/Pt/PEG nanoplatforms. • Significant H 2 O 2 and O 2 generation abilities through the dual channels of ZnO 2 and Pt nanoenymes and improved 1O 2 generation ability. • Obvious inhibition of tumor due to combined PDT/chemotherapy. Nanotheranostic platforms, which can respond to tumor microenvironments (TME, such as low pH and hypoxia), are immensely appealing for photodynamic therapy (PDT). However, hypoxia in solid tumors harms the treatment outcome of PDT which depends on oxygen molecules to generate cytotoxic singlet oxygen (1O 2). Herein, we report the design of TME-responsive smart nanotheranostic platform (DOX/ZnO 2 @Zr-Ce6/Pt/PEG) which can generate endogenously hydrogen peroxide (H 2 O 2) and oxygen (O 2) to alleviate hypoxia for improving photodynamic-chemo combination therapy of tumors. DOX/ZnO 2 @Zr-Ce6/Pt/PEG nanocomposite was prepared by the synthesis of ZnO 2 nanoparticles, in-situ assembly of Zr-Ce6 as typical metal–organic framework (MOF) on ZnO 2 surface, in-situ reduction of Pt nanozymes, amphiphilic lipids surface coating and then doxorubicin (DOX) loading. DOX/ZnO 2 @Zr-Ce6/Pt/PEG nanocomposite exhibits average sizes of ∼78 nm and possesses a good loading capacity (48.8 %) for DOX. When DOX/ZnO 2 @Zr-Ce6/Pt/PEG dispersions are intratumorally injected into mice, the weak acidic TEM induces the decomposition of ZnO 2 core to generate endogenously H 2 O 2 , then Pt nanozymes catalyze H 2 O 2 to produce O 2 for alleviating tumor hypoxia. Upon laser (630 nm) irradiation, the Zr-Ce6 component in DOX/ZnO 2 @Zr-Ce6/Pt/PEG can produce cytotoxic 1O 2 , and 1O 2 generation rate can be enhanced by 2.94 times due to the cascaded generation of endogenous H 2 O 2 /O 2. Furthermore, the generated O 2 can suppress the expression of hypoxia-inducible factor α , and further enable tumor cells to become more sensitive to chemotherapy, thereby leading to an increased effectiveness of chemotherapy treatment. The photodynamic-chemo combination therapy from DOX/ZnO 2 @Zr-Ce6/Pt/PEG nanoplatform exhibits remarkable tumor growth inhibition compared to chemotherapy or PDT. Thus, the present study is a good demonstration of a TME-responsive nanoplatform in a multimodal approach for cancer therapy. [ABSTRACT FROM AUTHOR]

Aim: This study compared the effectiveness of several techniques in restoring compromised bonding to recently bleached enamel. Methods: Seventy-five healthy bovine incisors were divided into five groups (n = 15). Fifteen teeth (Group 1) remained intact, whereas 60 (Groups 2 to 5) underwent at-home bleaching with 16% carbamide peroxide. The bonding procedures were as follows: Group 1: Bonding of resin composite to unbleached enamel; Group 2: Bonding immediately after bleaching; Group 3: Application of a 10% sodium ascorbate solution for 10 min before bonding; Group 4: Enamel removal to the depth of 0.5 mm; and Group 5: Increased curing time of the bonding agent to 80 instead of 20 s. After 24 h, the specimens were subjected to micro-shear testing, and the failure mode was determined. Results: ANOVA revealed a significant difference in bond strength among the groups (P < 0.001). The mean bond strength was significantly lower in group 2 than in other groups (P < 0.05), which showed comparable bond strength to each other (P > 0.05). Adhesive failure was the most predominant failure type in all groups. The mixed failure occurred with a frequency of 26.7% in groups 3 and 5. The Fisher's exact test revealed a significant difference in failure modes among the groups (P = 0.047). Conclusions: The three experimental procedures used in this study, including the application of 10% sodium ascorbate before bonding, enamel removal to the depth of 0.5 mm, and increasing the curing time of the bonding agent to 80 s, were effective in restoring the compromised bonding to recently bleached enamel. [ABSTRACT FROM AUTHOR]

The adsorption of oligomeric peroxide of sebacic acid on aerosols was studied. The parameters of the adsorption process were found. The effect of aerosil on the polymerization of styrene (ST), methyl acrylate (MA), butyl acrylate (BA), methyl methacrylate (MMA) and butyl methacrylate (BMA) was studied. The initiators used were oligomeric sebacic acid peroxide (OPSA), benzoyl peroxide (BP), lauryl peroxide (PL) and didecanoyl diperoxy adipinate (DP). The mineral filler increases the polymerization rate of MMA, BMA, MA, BA initiated by OPSA. Under the same conditions, the polymerization rate of ST decreases with an increase in the aerosil content in the polymerization system. BP practically does not affect the polymerization rate of vinyl monomers in the presence of aerosil. The reaction of thermal decomposition of OPSA, DP, PL and BP in styrene in the presence of aerosol was studied. An increase in the content of aerosil leads to an increase in the effective decomposition constant of OPSA, DP, PL. in the case of BP, aerosil has practically no effect on the decomposition rate. [ABSTRACT FROM AUTHOR]

The functionalization of polymeric matrices through graft polymerization offers various advantages by providing new properties, allowing for additional chemical reactions that the matrix alone could not undergo or that would require drastic chemical conditions to occur. In this work, epoxy groups were incorporated through a graft polymer of poly(glycidyl methacrylate), using a prefunctionalization with peroxide groups in the polytetrafluoroethylene matrix through gamma radiation. These peroxide groups were subsequently used as radical chemical initiators in the graft polymerization reaction of glycidyl methacrylate. The graft polymerization reaction was studied based on the absorbed dose, monomer concentration, reaction time, and temperature. [ABSTRACT FROM AUTHOR]

Carbon–phosphorus bond formation is of great importance in synthetic chemistry. A versatile strategy for the formation of carbon–phosphorus bonds involves the addition of phosphorus radicals to π-systems. However, the generation methods of phosphorus radicals are primarily restricted to homolytic cleavage of phosphorus–hydrogen bonds with excess peroxides or toxic metal salts as oxidants. Herein, we introduce a photoinduced palladium-catalyzed generation of phosphorus radicals using inexpensive and readily available Cl–phosphine oxides and Cl–phosphates as the phosphorus radical precursors. The key step for this strategy lies in the reductive activation of phosphorus–chloride bonds with the excited palladium complex under visible light irradiation. The involvement of phosphorus radicals has been evidenced by EPR spectroscopy and radical trapping experiments. Based on this strategy, both phosphinyl and phosphonyl groups could be regiospecifically incorporated into simple alkenes and heteroaromatic compounds via radical mediated carbon–phosphorus bond formation. Besides, carbon–phosphorus difunctionalization of alkenes was also achieved to afford phosphorylated oxindoles. [ABSTRACT FROM AUTHOR]

Mutagenesis is responsive to many environmental factors. Evolution therefore depends on the environment not only for selection but also in determining the variation available in a population. One such environmental dependency is the inverse relationship between mutation rates and population density in many microbial species. Here, we determine the mechanism responsible for this mutation rate plasticity. Using dynamical computational modelling and in culture mutation rate estimation, we show that the negative relationship between mutation rate and population density arises from the collective ability of microbial populations to control concentrations of hydrogen peroxide. We demonstrate a loss of this density-associated mutation rate plasticity (DAMP) when Escherichia coli populations are deficient in the degradation of hydrogen peroxide. We further show that the reduction in mutation rate in denser populations is restored in peroxide degradation-deficient cells by the presence of wild-type cells in a mixed population. Together, these model-guided experiments provide a mechanistic explanation for DAMP, applicable across all domains of life, and frames mutation rate as a dynamic trait shaped by microbial community composition. In some bacteria, mutation rates depend on environmental factors such as population density. This study uses simulation-guided experiments to show that denser microbial populations detoxify their environment more efficiently, resulting in a reduced rate of mutation. [ABSTRACT FROM AUTHOR]

Rubber compounds based on acrylonitrile‐butadiene rubber were filled with biopolymer fillers, namely kraft lignin, and calcium lignosulfonate. For cross‐linking of rubber compounds, sulfur curing system, dicumyl peroxide, and combination of dicumyl peroxide with trimethylolpropane trimethacrylate were used. The main objective of the work was to investigate the influence of biopolymer fillers content and curing system composition on vulcanization process of rubber compounds, cross‐link density, morphology, and physical‐mechanical properties of vulcanizates. The results revealed that rubber compounds filled with calcium lignosulfonate can be efficiently cured with sulfur as well as peroxide curing systems. Modulus, hardness, and elongation at break were strongly dependent on cross‐link density. Vulcanizates filled with high content of lignosulfonate exhibited comparable values of tensile strength, regardless of the curing system applied. The application of kraft lignin into peroxide systems cured rubber compounds resulted in undesirable reactions between functional groups of the biopolymer and peroxide radicals. Depletion of peroxide radicals resulted in significant deceleration of curing process and decrease in cross‐link density of vulcanizates. This was reflected in typical change of physical‐mechanical characteristics, decrease in modulus and hardness, and increase in elongation at break. Very good adhesion and compatibility between the kraft lignin and the rubber matrix resulted in enhancement of tensile behavior of vulcanizates cured with sulfur system. [ABSTRACT FROM AUTHOR]

Photosensitizers that are good producers of singlet oxygen, and the photocatalytic reactions promoted by these photosensitizers, have always been of great interest. In this study, we aimed to develop new photosensitizers based on cyclotriphosphazene and evaluate their performance in photocatalytic reactions. In this context, three new cyclotriphosphazene derivatives, each bearing BODIPY and thiophene units, were synthesized, and their molecular structures were characterized using spectroscopic techniques. Both the BODIPY derivatives and their cyclotriphosphazene derivatives had absorption in the visible region, and also, the resulting cyclotriphosphazene compounds exhibited significantly better molar absorption coefficients compared to the precursor BODIPY units. Incorporation of the halogen atom into the molecules resulted in the redshift of absorption and emission maxima, as well as decrease in the fluorescence characteristics of these molecules. The singlet oxygen-producing abilities of the molecules were evaluated by the chemical trapping method using DPBF as the singlet oxygen scavenger molecule, and the change was monitored by UV-vis absorption spectroscopy. Cyclotriphosphazene compounds 7 and 8 performed significantly better than both methylene blue and their precursor units, with singlet oxygen quantum yield values of 0.85 and 0.91. Finally, the ability of these compounds to convert 1,3-cyclohexadiene into peroxides (2,3-dioxabicyclo[2.2.2]oct-5-ene and 3-hydroperoxycyclohexa-1,4-diene) was evaluated. The compounds displayed notable photocatalytic activity toward the oxidation of 1,3-cyclohexadiene compared to tetraphenyl porphyrin (TPP), a known photocatalyst. [ABSTRACT FROM AUTHOR]

Films for coffee-pod packaging usually contain aluminium as an impermeable foil that is not recyclable and has to be discharged as waste. In this study, a recyclable polypropylene multilayer film is proposed as an alternative. The performance on the chemical composition of coffee was evaluated and compared to that of film containing aluminium (standard). The oxygen in the headspace, moisture, lipidic oxidation, and volatile organic compounds were studied in coffee pods during storage for 12 months at 25 and 40 ◦C. In addition, the acidity and acceptability of extracted coffee were evaluated. In the polypropylene-packaged pods, the percentage of oxygen during storage at 25 ◦C was lower than that in the standard. Moisture was not affected by the type of packaging materials. No differences were found between the peroxide values, except in pods stored for 3, 10, and 11 months at 25 ◦C, where they were even lower than the standard. Furans and pyrazines were the main volatile organic compounds detected. No differences were found in the pH and titratable acidity of the coffee brew either. All samples were well accepted by consumers without any perceived difference related to the packaging film. The polypropylene multilayer film is a sustainable recyclable material with high performance, in particular, against oxygen permeation. [ABSTRACT FROM AUTHOR]

Raman spectroscopy and density functional theory (DFT) calculations were used to explore the interaction between methanol (MeOH) and hydrogen peroxide (HP). Raman spectra of MeOH–HP binary solutions with different concentrations were measured at room temperature and atmospheric pressure. Anomalous change in hydrogen bonding (H-bond) was observed when V M (volume fraction of the MeOH) was 0.1. Based on Gaussian deconvolution, the influence of MeOH on the O–H stretching mode is analyzed. The results indicate that at V M > 0.1, the symmetric and asymmetric O–H stretching vibrational modes of HP located at 3264 and 3462 cm−1, respectively, shifted to lower wave numbers, and the free O–H vibrational mode (weak shoulder peak) at 3600 cm−1 disappeared. This phenomenon showed that the Raman shifts of O–H symmetric and asymmetric stretching vibrational modes reversed when V M is 0.1, which reveals that the H-bond structure of this binary solution undergoes a phase transition from HP–HP to MeOH–HP as V M increases. Furthermore, the blueshift of the C–H symmetric and asymmetric vibrational stretching modes of MeOH and the redshift of the C–O vibrational mode of MeOH demonstrate that no H-bond formed between the methyl group of MeOH and HP molecules. Finally, the DFT calculation at the B3LYP/6–311 + G(d,p) level of theory was carried out to obtain the optimized geometry, vibrational spectra, bond length, and interaction energies of MeOH–HP complexes. This work can be used as a reference for exploring the H-bond network in systems involving alcohol and hydrogen peroxide. [ABSTRACT FROM AUTHOR]

This review gathered and discussed the available results on the thermal hazards, thermal kinetics, decomposition mechanism, autocatalytic behavior, thermal explosion, deflagration ability, and incompatibility hazards associated with the thermal decomposition of methyl ethyl ketone peroxide (MEKPO). The present review constructed a diagram showing all activation energy Ea and log A values for the thermal decomposition of MEKPO. Some disagreement exists in the values of Ea and log A (unit: s−1 M1−n) derived from differential scanning calorimetry; thus, more extensive studies must be conducted to resolve disputes. Nearly no literature exists on the thermal explosion and deflagration ability of MEKPO, and the reactions of MEKPO with incompatible contaminants remain unclear. Concerning the complex decomposition mechanism of MEKPO, experimental determination and identifications of intermediates have not been obtained. Available technology must be improved to enable the collection of accurate data on thermal hazards, thermal kinetics, decomposition mechanisms, explosion and deflagration phenomena, autocatalytic behavior, and incompatibility. This review has integrated an up‐to‐date summary of the most recent approaches and offers perspectives regarding future research. These current findings can serve as a reference for completing subsequent experimental investigations, theoretical studies, and designs of inherently safer measures for producing or handling MEKPO. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the bleaching efficacy and effects on enamel properties of experimental gels with carbamide peroxide (CP; 10%) or hydrogen peroxide (HP; 6%) containing calcium polyphosphate sub-microparticles (CaPPs). Methods: A total of 216 bovine tooth specimens were divided for microhardness and color analyses (n = 108) and block randomized into nine groups (n = 12): (G1) commercial CP (Whiteness Perfect, FGM; Brazil); (G2) experimental CP; (G3) CP-0.5%CaPPs; (G4) CP-1.5%CaPPs; (G5) commercial HP (Potenza Bianco, PHS; Brazil); (G6) experimental HP; (G7) HP-0.5%CaPPs; (G8) HP-1.5%CaPPs; (G9) artificial saliva. The gels' pH values were determined with a bench pH meter. Color (ΔE, ΔE00, ΔWID) and microhardness variation were evaluated before and after the therapy. Part of the specimens used for microhardness was submitted to the scanning electron microscopy (SEM) (n = 3) and energy-dispersive X-ray spectroscopy EDX (n = 3) analyses. Statistical analyses were performed in the R statistical software (α = 0.05). Linear mixed models for repeated measures in time were used to analyze microhardness and L* values. Generalized linear models were used to analyze the a*, b*, ΔE, ΔE00, and ΔWID, considering a group effect. The EDX data were analyzed using a one-way ANOVA with Tukey's test. Results: The gels' pH remained over 6,0. All gels effectively bleached the specimens and did not differ significantly. When compared to the control group, the hardness was significantly lower in the G1, G2, G6, and G7 groups. The G3, G4, G5, and G8 groups did not differ significantly (p > 0.05). Conclusion: The incorporation of CaPPs in low-concentration whitening gels reduces its negative effects on microhardness without interfering with their bleaching efficacy. [ABSTRACT FROM AUTHOR]

Introduction: Over the last ten years the use of teeth whitening products containing hydrogen peroxide (H2O2) has become popular. According to European legislation, it is allowed to be added to products for both professional and personal use, in concentrations from 0.1 to 6%. Ingestion of low concentrations of hydrogen peroxide in the oral cavity does not lead to adverse effects, but its long-term use can lead to health risks. Aim: Development of a method for the determination of hydrogen peroxide in teeth whitening products. Material and methods: The method is based on the oxidation of hydrogen peroxide with triphenylphosphine (TPP) to triphenylphosphine oxide (TPPO) and the subsequent reverse phase HPLC-UV analysis of TPPO at a wavelength of 255 nm. Results: The method was applied to the analysis of commercial products for personal use containing urea peroxide or sodium percarbonate. Discussion: The results of the analyzed products show compliance of the hydrogen peroxide content with the values in Regulation (EC) No. 1223/2009 of the European Parliament and of the Council of 30 November 2009 on cosmetic products (recast), especially for oral care products - teeth whitening (from 0.1 to 6%). Conclusion: The method is suitable for official control purposes in the working range 30.00 ÷ 180.00 µg of H2O2 per kg product (from 0.08 % to 10% hydrogen peroxide). [ABSTRACT FROM AUTHOR]

An ionomer strategy is introduced to deal with two major performance‐limiting issues for the proton exchange membrane fuel cells (PEMFCs) operating under low platinum (Pt) and low humidity. Specifically, the highly hydrophilic multiple‐valence Anderson‐type polyoxometalate (POM) cluster, [MnMo6O18(OH)6]3−, is chosen to covalently graft the perfluorinated polymer, substituting for sulfonate groups as proton carriers in perfluorosulfonic acid (PFSA). The structural and electrochemical characterizations indicate that this POM cluster, with large size, charges delocalization among multiple terminal oxygen atoms, and high hygroscopicity, can prevent the ionomer adsorption, which is believed to induce dense backbone crystallization to hinder O2 permeation at Pt/PFSA interface, and lead to ionomer assemblies with large and well‐connected hydrophilic domains, which are recognized as the channels for efficient oxygen transport as well as proton conduction. Besides, the involvement of redox Mn ions in POM clusters makes the ionomer have capability to scavenge peroxides, which are known as the major chemical agents to degrade the MEA components. Consequently, fuel‐cell cathodes using the POM‐grafted ionomers exhibit significantly lower local O2 transport resistance and higher proton conductivity as compared with the PFSA‐based electrodes; and accordingly, the fuel cells exhibit much‐increased output performance at 50% relative humidity and impressive performance stability. [ABSTRACT FROM AUTHOR]

Nanoporous gold (npAu) was tested as a catalyst for oxidations of various benzylic sp3‐carbon positions in 9H‐fluorene derivatives and similar hydrocarbons using tertbutyl hydroperoxide (TBHP) as an oxidant. The silver content in the npAu catalyst had a major influence on the overall conversion: Lower silver amounts (0.53 mol%) led to higher conversions, whereas higher amounts of silver increasingly resulted in the disproportionation of TBHP as a competing reaction. Because residual silver from the bulk alloy was oxidized by TBHP and leached into the solution during the reaction, the Ag content diminished over time. Therefore, the recycling of the catalyst had a positive effect on the conversion after each use. Using electron paramagnetic resonance (EPR) spectroscopy, the formation of radicals from TBHP by npAu was evidenced indicating a radical‐based reaction mechanism which was further elucidated by NMR spectroscopic and GC‐MS (trace) product analysis. Subsequent oxidations of benzylic sp3‐carbon positions gave good to excellent conversions and chemoselectivities featuring npAu as a suitable catalyst for such reactions. [ABSTRACT FROM AUTHOR]

Alkenes are highly valuable materials in organic synthesis, and their three‐component reactions offer a promising method for C−C bond formation and carbon chain elongation. This approach not only reduces the number of reaction steps but also minimizes waste generation, enabling the preparation of polysubstituted alkanes from simple starting materials. In this review, we provide an overview of recent advancements in this field from 2013 to 2023. We have classified the developments into three main categories: (1) reactions triggered by C‐radicals or heteroatom‐radicals; (2) cascades involving three‐membered ring intermediates; and (3) transformations catalyzed by metals. We will discuss a wide range of reactions that involve diazoium salts, arylhydrazines, acids, aldehydes, 1,3‐dicarbonyls, diazo compounds, amines, malononitriles, diacyl peroxides, ethers, 1,3‐dithiane, arenes, CuSCF3, selectfluor, Et3N ⋅ 3HF, TBHP, CH2Cl2, CHCl3, CO2, CO, KCl, H2O, and other reagents. These reactions lead to alkylation, arylation, or carbonylation products. We believe that this review will be helpful for future research in this area. [ABSTRACT FROM AUTHOR]

Although hydrogen peroxide (H2O2) has been highly used in nuclear chemistry for more than 75 years, the preparation and literature description of tetravalent actinide peroxides remain surprisingly scarce. A new insight is given in this topic through the synthesis and thorough structural characterization of a new peroxo compound of Pu(IV). [ABSTRACT FROM AUTHOR]

With the rise in installed capacity of photovoltaic systems, the growing generation of waste crystalline silicon solar cells has become an important issue. Silicon is one of the most valuable materials in cells; recyclable treatments with green techniques must be developed for it. A new strategy for the recovery of silicon wafers has been proposed using choline chloride and oxalic acid-based deep eutectic solvent–hydrogen peroxide (DES–H2O2) aqueous solution systems. With the synergistic effect of DES and H2O2, the leaching efficiency of silver from cells reached 89.19%, along with complete aluminum leaching. Compared with only the DES control, the leaching efficiency of silver was enhanced by as high as 97.45%. Subsequently, reusable silicon wafers were obtained with 97.47 wt% surface purity, and 99.41% of silicon retention rate (169 μm) after removing Si3N4. Favorable results were mainly attributed to the higher concentration of H+ due to a boost by oxalic acid-based DES compared to concentrations in an oxalic acid aqueous solution, which could provide stronger oxidizing power, and besides, lower oxidation activation energy for silver in H2O2. In this work, high-purity silicon wafers were obtained with high leaching efficiency of metals in a short time (2 h) at a low temperature (80 °C) without using strong acids; among solvents, the DES showed great potential for reuse. It is concluded that the DES–H2O2 aqueous solution system provides an environmentally friendly process for green and nearly lossless recovery of silicon wafers from silicon solar cells. [ABSTRACT FROM AUTHOR]

It is a crucial and current challenge to develop efficient metal sulfide bifunctional electrocatalysts for practical applications in direct borohydride-hydrogen peroxide fuel cells (DBHPFCs). In this study, a uniform nanoflower-like Ni 3 S 2 is rationally designed and hydrothermally grown on the surface of a 3D nickel foam (NF) support without the need for additional nickel sources, and Pd nanoparticles are further reduced on the surface of nanoflower-like Ni 3 S 2 with sulfur vacancies to form Pd/v-Ni 3 S 2 /NF electrode by NaBH 4 reduction. The Pd/v-Ni 3 S 2 /NF electrode delivers a NaBH 4 electrooxidation current density of 902 mA cm−2 at 0.85 V and a H 2 O 2 electroreduction current density of 298 mA cm−2 at 0.65 V in alkaline solutions. Subsequently, Pd/v-Ni 3 S 2 /NF electrodes are assembled into DBHPFCs, yielding the optimal power density of 78 mW cm−2 and demonstrating superior long-term stability. These results fully indicate that the nanoflower-like Pd/v-Ni 3 S 2 /NF self-supported electrode with abundant sulfur vacancies is a promising bifunctional electrocatalyst for DBHPFCs. [Display omitted] • Pd/v-Ni 3 S 2 /NF was rationally designed by using a simple fabrication process. • Pd/v-Ni 3 S 2 /NF electrode delivers a NaBH 4 oxidation current density of 902 mA cm−2. • Pd/v-Ni 3 S 2 /NF electrode delivers a H 2 O 2 reduction current density of 298 mA cm−2. • Pd/v-Ni 3 S 2 /NF was assembled into a DBHFC with higher power density of 78 mW cm−2. • Sulfur vacancy exposed more active sites to achieve super performances. [ABSTRACT FROM AUTHOR]

The air supply system is an essential component of a proton exchange membrane fuel cell (PEMFC), and proper control of the oxygen stoichiometry ratio(λo 2) is crucial to prevent oxygen starvation in the PEMFC while maintaining efficient and stable performance output. In response to the issues of poor dynamic performance and slow response in traditional λo2 control strategies, this study was conducted to establish a dynamic oxygen flow model of the PEMFC and proposed a λo 2 control strategy based on an immune algorithm-fuzzy PID (IAFPID). The performance of the IAFPID control strategy in λo 2 control was analyzed under different load requirements, simulated vehicle dynamic loads, and temperature disturbances. The results demonstrate that the IAFPID control strategy has advantages such as fast convergence speed, strong robustness, and good dynamic performance. The efficiency of achieving the optimal stoichiometry ratio for high power output in PEMFC under disturbances was nearly 50% higher with IAFPID control compared to traditional PID, Fuzzy-PID, Genetic Algorithm PID, and Immune Algorithm PID strategies. Furthermore, this method ensures a lower average error in maintaining stable λo 2 under dynamic disturbances compared to the IAPID and PID control strategies, with reductions of 12.93% and 37.75%, respectively. • A peroxide ratio control strategy of PEMFC system based on immune algorithm fuzzy PID was proposed. • The proposed IAFPID achieves nearly a 50% faster steady-state efficiency compared to PID, FPID, and IAPID. • The overshoot is only 1.8% under temperature disturbances, nearly 60% reduction compared to traditional methods. [ABSTRACT FROM AUTHOR]

Compared to sp2‐hybridized graphene, graphdiynes (GDYs) composed of sp and sp2 carbon are highly promising as efficient catalysts for electrocatalytic oxygen reduction into oxygen peroxide because of the high catalytic reactivity of the electron‐rich sp‐carbon atoms. The desired catalytic capacity of GDY, such as catalytic selectivity and efficiency, can theoretically be achieved by strategically steering the sp‐carbon contents or the topological arrangement of the acetylenic linkages and aromatic bonds. Herein, we successfully tuned the electrocatalytic activity of GDYs by regulating the sp‐to‐sp2 carbon ratios with different organic monomer precursors. As the active sp‐carbon atoms possess electron‐sufficient π orbitals, they can donate electrons to the lowest unoccupied molecular orbital (LUMO) orbitals of O2 molecules and initiate subsequent O2 reduction, GDY with the high sp‐carbon content of 50 at % exhibits excellent capability of catalyzing O2 reduction into H2O2. It demonstrates exceptional H2O2 selectivity of over 95.0 % and impressive performance in practical H2O2 production, Faraday efficiency (FE) exceeding 99.0 %, and a yield of 83.3 nmol s−1 cm−2. Our work holds significant importance in effectively steering the inherent properties of GDYs by purposefully adjusting the sp‐to‐sp2 carbon ratio and highlights their immense potential for research and applications in catalysis and other fields. [ABSTRACT FROM AUTHOR]

Rubber blends based on styrene–butadiene rubber, ethylene–propylene–diene monomer rubber and a combination of both rubbers were cured with different sulfur and peroxide curing systems. In sulfur curing systems, two type of accelerators, namely tetramethylthiuram disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, and combinations of both accelerators were used. In peroxide curing systems, dicumyl peroxide, and a combination of dicumyl peroxide with zinc diacrylate or zinc dimethacrylate, respectively, were applied. The work was aimed at investigating the effect of curing systems composition as well as the type of rubber or rubber combinations on the curing process, cross-link density and physical–mechanical properties of vulcanizates. The dynamic mechanical properties of the selected vulcanizates were examined too. The results revealed a correlation between the cross-link density and physical–mechanical properties. Similarly, there was a certain correlation between the cross-linking degree and glass transition temperature. The tensile strength of vulcanizates based on rubber combinations was higher when compared to that based on pure rubbers, which points out the fact that in rubber combinations, not only are the features of both elastomers combined, but improvement in the tensile characteristics can also be achieved. When compared to vulcanizates cured with dicumyl peroxide, materials cured with a sulfur system exhibited higher tensile strength. With the application of co-agents in peroxide vulcanization, the tensile strength overcame the tensile behavior of sulfur-cured vulcanizates. [ABSTRACT FROM AUTHOR]

In this study, a pH-responsive polycaprolactone (PCL)–copper peroxide (CuO2) composite antibacterial coating was developed by suspension flame spraying. The successful synthesis of CuO2 nanoparticles and fabrication of the PCL-CuO2 composite coatings were confirmed by microstructural and chemical analysis. The composite coatings were structurally homogeneous, with the chemical properties of PCL well maintained. The acidic environment was found to effectively accelerate the dissociation of CuO2, allowing the simultaneous release of Cu2+ and H2O2. Antimicrobial tests clearly revealed the enhanced antibacterial properties of the PCL-CuO2 composite coating against both Escherichia coli and Staphylococcus aureus under acidic conditions, with a bactericidal effect of over 99.99%. This study presents a promising approach for constructing pH-responsive antimicrobial coatings for biomedical applications. [ABSTRACT FROM AUTHOR]

Synthesis of nitrogen-doped carbon dots (N-CDs) using urea and ascorbic acid as carbon sources is addressed in this study using a microwave-assisted hydrothermal technique. The samples were characterized by ultraviolet, photoluminescence (PL) and transmission electron microscopy analyses, which confirmed the formation of CDs. Besides PL properties, the peroxidase-like catalytic activity of the CDs and N-CDs was also compared. Interestingly, the N-CDs exhibit higher peroxidase-like catalytic activity than pure CDs and can be used to detect H2O2. Additionally, we synthesized several N-CD ratios and evaluated their peroxidase-like catalytic activity. [ABSTRACT FROM AUTHOR]

Plasmodium falciparum is a fast-evolving parasite responsible for the fatal disease malaria, making it crucial to renew our therapeutic arsenal. Modulating the artemisinin's endoperoxide pharmacophore is a promising route to synthesizing new antimalarial derivatives. For the first step of our 20 mmol scale synthesis, catalyzed by manganese (III) acetylacetonate, we applied the conditions previously described in the literature to one of our low-yielding asymmetrically disubstituted alkenes, (2-methylallyl)benzene. Under conditions designed for alkyl derivatives, manganese (II) and (III) acetate catalyzed its peroxycyclization with methyl 3-oxobutanoate to a 1,2-dioxane ring in the presence of oxygen from air at room temperature with a 36% yield, while an oxygen atmosphere, as described in the literature, decreased the yield to 7%. Finally, under conditions designed for aryl derivatives, the yield was reduced to 30%, showing that methylallyl derivatives have an intermediate reactivity that needs further optimization to produce 1,2-dioxane ring by manganese catalyzation in good yields. This work characterizes the product obtained and discusses the most suitable reaction conditions. [ABSTRACT FROM AUTHOR]

Imines are certainly important constituents of many biomolecules, pharmaceuticals, agrochemicals, and fine chemicals. This review article highlights the standard protocols reported so far for the selective synthesis of imines via catalyzed and non-catalyzed (i) oxidative coupling of primary amines and (ii) oxidation of secondary amines in the presence of some competent/resourceful oxidants other than molecular O2 such as tert-butyl hydroperoxide (TBHP), H2O2, hypervalent iodines, persulfate, hypochlorite, electroactive species and graphene oxide. Indeed, the use of such oxidants offers a cost-effective experimental set-up, operational simplicity and also minimization of by-products. The cooperativity between catalyst, amine substrate, and oxidant is discussed in this review to understand the proposed mechanisms. Three consolidated data tables (Table 1, 2 & 3) are prepared to provide the summary of optimized reaction conditions (type of catalyst, type of oxidant, choice of solvent, amine-to-oxidant ratio, reaction time/temperature, conversion of amine, yield/selectivity of imine) of each article published to have a comparison. [ABSTRACT FROM AUTHOR]

One previously undescribed sesquiterpene analogue, M2 (1), together with five known ones, indole-3-carboxylic acid (2), methyl 4-hydroxycinnamate (3), ergosterol peroxide (4), 6β-hydroxystigmast-4-en-3-one (5), as well as betulonic acid (6), were isolated from the EtOAc extract of the culture broth of an actinomycete Streptomyces sp. M2. The structures of all isolates were elucidated on the basis of extensive analyses of spectroscopic data and comparison with literature data. [ABSTRACT FROM AUTHOR]

In natural photosynthesis, the light-driven splitting of water into electrons, protons and molecular oxygen forms the first step of the solar-to-chemical energy conversion process. The reaction takes place in photosystem II, where the Mn4CaO5 cluster first stores four oxidizing equivalents, the S0 to S4 intermediate states in the Kok cycle, sequentially generated by photochemical charge separations in the reaction center and then catalyzes the O-O bond formation chemistry1-3. Here, we report room temperature snapshots by serial femtosecond X-ray crystallography to provide structural insights into the final reaction step of Kok's photosynthetic water oxidation cycle, the S3→[S4]→S0 transition where O2 is formed and Kok's water oxidation clock is reset. Our data reveal a complex sequence of events, which occur over micro- to milliseconds, comprising changes at the Mn4CaO5 cluster, its ligands and water pathways as well as controlled proton release through the hydrogen-bonding network of the Cl1 channel. Importantly, the extra O atom Ox, which was introduced as a bridging ligand between Ca and Mn1 during the S2→S3 transition4-6, disappears or relocates in parallel with Yz reduction starting at approximately 700 μs after the third flash. The onset of O2 evolution, as indicated by the shortening of the Mn1-Mn4 distance, occurs at around 1,200 μs, signifying the presence of a reduced intermediate, possibly a bound peroxide.