Bias-drift insensitive full-field frequency response characterization of a thin-film lithium niobate-based intensity modulator.

We propose a rapid and precise scheme for characterizing the full-field frequency response of a thin-film lithium niobate-based intensity modulator (TFLN-IM) via a specially designed multi-tone microwave signal. Our proposed scheme remains insensitive to the bias-drift of IM. Experimental verification is implemented with a self-packaged TFLN-IM with a 3 dB bandwidth of 30 GHz. In comparison with the vector network analyzer (VNA) characterization results, the deviation values of the amplitude-frequency response (AFR) and phase-frequency response (PFR) within the 50 GHz bandwidth are below 0.3 dB and 0.15 rad, respectively. When the bias is drifted within 90% of the Vπ range, the deviation fluctuation values of AFR and PFR are less than 0.3 dB and 0.05 rad, respectively. With the help of the full-field response results, we can pre-compensate the TFLN-IM for the 64 Gbaud PAM-4 signals under the back-to-back (B2B) transmission, achieving a received optical power (ROP) gain of 2.3 dB. The versatility of our proposed full-field response characterization scheme can extend to various optical transceivers, offering the advantage of low cost, robust operation, and flexible implementation.

Direct Work Function Measurement Using in-situ Ambient Pressure X-ray Photoemission Spectroscopy and Its Application on Copper Oxidation Process.

The work function (WF) measurement plays a critical role in engineering energy materials and energy devices. However, the ultra-high vacuum (UHV) environments of photoemission method limit the practical application for absolute work function measurements of materials, especially under complex working conditions. To understand the energy level of materials under complex chemical environments, the in-situ measurements of work function is necessary in complex metal/semiconductor system for various application. In this paper, we describe the utilization of ambient pressure X-ray photoemission spectroscopy (APXPS) with utilization of low photon energy X-ray for absolute WF measurements at BL02B of the Shanghai Synchrotron Radiation Facility. We herein present the WF measurement during oxygen adsorption on Pt(111) and oxidation of Cu(111) in ambient oxygen environment as demonstration of the APXPS capability for WF measurement. After oxygen chemisorption on Pt and formation of Cu2O, the WF will increase. This is due to charge transfer from metal to chemisorbed oxygen atoms. After the formation of bulk Cu2O and CuO, the WF value almost remain at ~5.5 eV. We believe the direct measurement of absolute work function via APXPS could help bridge the gap between the physical properties and the surface chemical species for metal/semiconductor materials.

Tunable Li-ion diffusion properties in MoSSe bilayer anodes by strain gradient.

Layered MoSSe nanostructures have been shown as potential candidates for the anode of lithium ion (Li-ion) batteries. The diffusion properties are generally critical to the performance of ionic batteries. The possible migration paths and associated diffusion energy barriers of Li-ions are systematically explored in MoSSe bilayer anodes with different stacking patterns by means of first-principles simulations. It is found that the diffusion properties strongly depend on interfaces and stacking patterns. Furthermore, the simulation results show that the diffusion energy barrier (and thus the diffusion coefficient) can be significantly reduced (enlarged) by applying a positive strain gradient, while increased (reduced) by applying a negative one. For example, the diffusion coefficient is increased roughly by 100 times relative to that of the pristine one when subjected to a strain gradient of 0.02 Å-1. In particular, it is found that less maximum strain is required in the strain-gradient than the uniform strain in order to achieve the same diffusion energy barrier. By careful analysis, the underlying mechanism can be attributed to the flexo-diffusion coupling effect. The coupling strength is characterized by the so-called flexo-diffusion coupling constant which is also calculated for each simulation model. The results of this work may provide valuable insights into the design and optimization of the anodes of ionic batteries.

Reciprocal longitudinal relations between self-efficacy and coping style: The explanatory mechanism of future self-continuity.

BACKGROUND: It has been demonstrated that self-efficacy and coping styles are related. However, whether there is a reciprocal longitudinal relation between self-efficacy and coping styles needs to be examined. In this longitudinal study, we tested the reciprocal impacts of self-efficacy and coping styles, taking into account the role of future self-continuity (FSC) in these effects. METHODS: The sample included 346 university students in central and southwestern China (48.3% female; Mage = 21.20). Three waves of questionnaire data were collected at half-year intervals. Cross-lagged models were adopted for data analysis. RESULTS: Self-efficacy at Waves 1 and 2 positively predicted positive coping style at Waves 2 and 3, and positive coping style at Waves 1 and 2 positively predicted self-efficacy at Waves 2 and 3. Self-efficacy at Waves 1 and 2 negatively predicted negative coping style at Waves 2 and 3, while negative coping style at Waves 1 and 2 did not significantly predict self-efficacy at Waves 2 and 3. These results indicated the reciprocal causation of self-efficacy and coping styles. Additionally, the mediation analysis revealed that FSC at Wave 2 played a mediating role in the unidirectional association between self-efficacy at Wave 1 and negative coping style at Wave 3. CONCLUSIONS: These findings suggest that self-efficacy and coping style have mutual influences over time partly explained by university students' FSC. Consequently, the results offer potential applied value for promoting positive coping strategies among university students.

Analysis of dissolved oxygen influencing factors and concentration prediction using input variable selection technique: A hybrid machine learning approach.

Accurate quantification of dissolved oxygen (DO) is critically important for the protection and management of aquatic ecosystems. Successful applications have utilized mechanistic and data-driven models to simulate DO content in aquatic ecosystems. However, mechanistic models present challenges due to their complex and difficult-to-solve conditions, making them less portable. Additionally, data-driven model predictions are hindered by the challenge of numerous input variables, impacting both the running speed and prediction performance of the model. To address these challenges, water quality data and meteorological data of the Tanjiang River were obtained. The maximum information coefficient (MIC) input variable selection technique was employed to identify primary environmental factors influencing DO changes. Furthermore, coupled with support vector regression (SVR), two models (SVR and MIC-SVR) were employed to estimate the DO concentration of the Tanjiang River, and the optimal model was established. The results indicated a shift in the primary pollution factor from ammonia nitrogen to total phosphorus after recent treatment in the Tanjiang River. In comparison with the SVR model, the root mean square error (RMSE) of the MIC-SVR model was reduced by 4.46%, and the Nash-efficiency coefficient (NSE) was improved by 45.85%. In addition, study of kernel function selection revealed that considering as many kernel functions as possible is necessary for improving the performance of the SVR model. Conclusively, the proposed MIC-SVR model serves as an effective tool to analyze the relationship between DO and environmental factors, identifying the primary causes of low DO, and accurately predict the DO concentration in the Tanjiang River (especially in its middle and lower reaches), thus providing a reference for governmental decision-making on water environmental protection and water resource management.

CAC: Confidence-Aware Co-Training for Weakly Supervised Crack Segmentation.

Automatic crack segmentation plays an essential role in maintaining the structural health of buildings and infrastructure. Despite the success in fully supervised crack segmentation, the costly pixel-level annotation restricts its application, leading to increased exploration in weakly supervised crack segmentation (WSCS). However, WSCS methods inevitably bring in noisy pseudo-labels, which results in large fluctuations. To address this problem, we propose a novel confidence-aware co-training (CAC) framework for WSCS. This framework aims to iteratively refine pseudo-labels, facilitating the learning of a more robust segmentation model. Specifically, a co-training mechanism is designed and constructs two collaborative networks to learn uncertain crack pixels, from easy to hard. Moreover, the dynamic division strategy is designed to divide the pseudo-labels based on the crack confidence score. Among them, the high-confidence pseudo-labels are utilized to optimize the initialization parameters for the collaborative network, while low-confidence pseudo-labels enrich the diversity of crack samples. Extensive experiments conducted on the Crack500, DeepCrack, and CFD datasets demonstrate that the proposed CAC significantly outperforms other WSCS methods.

Zinc-Mediated Template Synthesis of Hierarchical Porous N-Doped Carbon Electrocatalysts for Efficient Oxygen Reduction.

The development of highly active and low-cost catalysts for use in oxygen reduction reaction (ORR) is crucial to many advanced and eco-friendly energy techniques. N-doped carbons are promising ORR catalysts. However, their performance is still limited. In this work, a zinc-mediated template synthesis strategy for the development of a highly active ORR catalyst with hierarchical porous structures was presented. The optimal catalyst exhibited high ORR performance in a 0.1 M KOH solution, with a half-wave potential of 0.89 V vs. RHE. Additionally, the catalyst exhibited excellent methanol tolerance and stability. After a 20,000 s continuous operation, no obvious performance decay was observed. When used as the air-electrode catalyst in a zinc-air battery (ZAB), it delivered an outstanding discharging performance, with peak power density and specific capacity as high as 196.3 mW cm-2 and 811.5 mAh gZn-1, respectively. Its high performance and stability endow it with potential in practical and commercial applications as a highly active ORR catalyst. Additionally, it is believed that the presented strategy can be applied to the rational design and fabrication of highly active and stable ORR catalysts for use in eco-friendly and future-oriented energy techniques.

Zeylleucapenoids A-D, Highly Oxygenated Diterpenoids with Anti-Inflammatory Activity from Leucas zeylanica (L.) R. Br.

Four previously undescribed highly oxygenated diterpenoids (1-4), zeylleucapenoids A-D, characterized by halimane and labdane skeletons, were isolated from the aerial parts of Leucas zeylanica. Their structures were elucidated primarily via NMR experiments. The absolute configuration of 1 was established using theoretical ECD calculations and X-ray crystallographic analysis, whereas those for 2-4 were assigned using theoretical ORD calculations. Zeylleucapenoids A-D were tested for anti-inflammatory activity against nitric oxide (NO) production in RAW264.7 macrophages, of which only 4 showed significant efficacy with an IC50 value of 38.45 µM. Further, active compound 4 was also evaluated for the inhibition of the release of pro-inflammatory cytokines TNF-α and IL-6 and was found to have a dose-dependent inhibitory effect, while it showed nontoxic activity for zebrafish embryos. A subsequent Western blotting experiment revealed that 4 inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Furthermore, molecular docking analysis indicated that the possible mechanism of action for 4 may be bind to targets via hydrogen and hydrophobic bond interactions.

Hydrogen peroxide, sodium dichloro-s-triazinetriones and quaternary alcohols significantly inactivate the dry-surface biofilms of Staphylococcus aureus and Pseudomonas aeruginosa more than quaternary ammoniums.

Globally, healthcare-associated infections (HAI) are the most frequent adverse outcome in healthcare delivery. Although bacterial biofilms contribute significantly to the incidence of HAI, few studies have investigated the efficacy of common disinfectants against dry-surface biofilms (DSB). The objective of this study was to evaluate the bactericidal efficacy of seven Environmental Protection Agency (EPA)-registered liquid disinfectants against DSB of Staphylococcus aureus and Pseudomonas aeruginosa. We hypothesized that overall, there will be significant differences among the bactericidal efficacies of tested disinfectants by product type and active ingredient class. We also hypothesized that depending on the species, higher bactericidal efficacies against DSB will be exhibited after 24 h of dehydration compared to 72 h. Wet-surface biofilms of S. aureus and P. aeruginosa were grown following EPA-MLB-SOP-MB-19 and dehydrated for 24 and 72 h to establish DSB. Seven EPA-registered disinfectants were tested against dehydrated DSB following EPA-MLB-SOP-MB-20. Overall, quaternary ammonium plus alcohol, sodium dichloro-s-triazinetrione and hydrogen peroxide products were more efficacious against DSB than quaternary ammoniums for both tested species. While there was no significant difference in the log10 reductions between 24 and 72 h S. aureus biofilms, significantly higher log10 reductions were observed when products were challenged with 24 h P. aeruginosa DSB compared to 72 h P. aeruginosa DSB. Species type, active ingredient class and dry time significantly impact disinfectant efficacy against DSB of S. aureus or P. aeruginosa.

Polydopamine-Induced Multilevel Engineering of Regenerated Silk Fibroin Fiber for Photothermal Conversion.

Solid photothermal materials with favorable biocompatibility and modifiable mechanical properties demonstrate obvious superiority and growing demand. In this work, polydopamine (PDA) induced functionalization of regenerated silk fibroin (RSF) fibers has satisfactory photothermal conversion ability and flexibility. Based on multilevel engineering, RSF solution containing PDA nanoparticles is wet spun to PDA-incorporating RSF (PDA@RSF) fibers, and then the fibers are coated with PDA via oxidative self-polymerization of dopamine to form PDA@RSF-PDA (PRP) fibers. During the wet spinning process, PDA is to adjust the mechanical properties of RSF by affecting its hierarchical structure. Meanwhile, coated PDA gives the PRP fibers extensive absorption of near-infrared light and sunlight, which is further fabricated into PRP fibrous membranes. The temperature of PRP fibrous membranes can be adjusted and increases to about 50 °C within 360 s under 808 nm laser irradiation with a power density of 0.6 W cm-2 , and PRP fibrous membranes exhibit effective photothermal cytotoxicity both in vitro and in vivo. Under the simulated sunlight, the temperature of PRP fiber increases to more than 200 °C from room temperature and the material can generate 4.5 V voltage when assembled with a differential thermal battery, which means that the material also has the potential for flexible wearable electronic devices.

In situ Dispersed Nano-Au on Zr-Suboxides as Active Cathode for Direct CO2 Electroreduction in Solid Oxide Electrolysis Cells.

CO2 electrochemical reduction in solid oxide electrolysis cells is an effective way to combine CO2 conversion and renewable electricity storage. A Au layer is often used as a current collector, whereas Au nanoparticles are rarely used as a cathode because it is difficult to keep nanosized Au at high temperatures. Here we dispersed a Au layer into Au nanoparticles (down to 2 nm) at 800 °C by applying high voltages. A 75-fold decrease in the polarization resistance was observed, accompanied by a 38-fold improvement in the cell current density. Combining electronic microscopy, in situ near-ambient pressure X-ray photoelectron spectroscopy, and theoretical calculations, we found that the interface between the Au layer and the electrolyte (yttria-stabilized zirconia (YSZ)) was reconstructed into nano-Au/Zr-suboxide interfaces, which are active sites that show a much lower reaction activation energy than that of the Au/YSZ interface. The formation of Zr-suboxides promotes Au dispersion and Au nanoparticle stabilization due to the strong interaction between Au and Zr-suboxides.

Natural Product 2-Oxokolavenol Is a Novel FXR Agonist.

Acetaminophen (APAP) toxicity is a common cause of hepatic failure, and the development of effective therapy is still urgently needed. Farnesoid X receptor (FXR), a member of the nuclear receptor superfamily, has been identified as a master gene for regulating enterohepatic metabolic homeostasis and has proven to be a promising drug target for various liver diseases. Through high-throughput chemical screening, the natural product 2-oxokolavenol was identified as a novel and selective FXR agonist. Further investigations revealed that 2-oxokolavenol exerts therapeutic efficacy against APAP-induced hepatocyte damage in an FXR-dependent manner. Mechanistically, 2-oxokolavenol forms two hydrogen bonds with M265 and Y369 of human FXR to compatibly fit into the ligand binding pocket of FXR, which potently leads to the recruitment of multiple co-regulators and selectively induces the transcriptional activity of FXR. Our findings thus not only reveal the direct target of natural product 2-oxokolavenol, but also provide a promising hit compound for the design of new FXR modulators with potential clinical value.

Production of Atosiban's Key Intermediate Pentapeptide: Synthetic Approaches to the Development of a Peptide Synthesis with Less Racemization and Simplifier Purification Process.

The key intermediate NH2-Ile-Thr(Bzl)-Asn-Cys(Bzl)-Pro-COOH of Atosiban was prepared from N-Boc-S-Bzl-cysteine by the stepwise lengthening of the chain according to the repetitive N,O-bis(trimethylsilyl)acetamide/N-hydroxysuccinimide ester (BSA/NHS) strategy. This synthetic route required no chromatography purification and can be readily performed, yielding a highly pure pentapeptide compound.

HMD-Net: A Vehicle Hazmat Marker Detection Benchmark.

Vehicles carrying hazardous material (hazmat) are severe threats to the safety of highway transportation, and a model that can automatically recognize hazmat markers installed or attached on vehicles is essential for intelligent management systems. However, there is still no public dataset for benchmarking the task of hazmat marker detection. To this end, this paper releases a large-scale vehicle hazmat marker dataset named VisInt-VHM, which includes 10,000 images with a total of 20,023 hazmat markers captured under different environmental conditions from a real-world highway. Meanwhile, we provide an compact hazmat marker detection network named HMD-Net, which utilizes a revised lightweight backbone and is further compressed by channel pruning. As a consequence, the trained-model can be efficiently deployed on a resource-restricted edge device. Experimental results demonstrate that compared with some established methods such as YOLOv3, YOLOv4, their lightweight versions and popular lightweight models, HMD-Net can achieve a better trade-off between the detection accuracy and the inference speed.

[Chemical constituents with α-glucosidase inhibitory activities from seeds of Morinda citrifolia (Noni)].

The present study investigated the chemical constituents and inhibitory activities against α-glucosidase from the seeds of Morinda citrifolia(Noni) by the chromatographic technique and semi-preparative HPLC.Fifteen compounds were isolated from the ethyl acetate extract of the seeds, and their structures were identified on the basis of physiochemical characteristics and spectroscopic data as(9S,2E,4Z,7Z)-9-hydroxydeca-2,4,7-trienoic acid(1), azelaic acid(2), scopoletin(3), ursolic acid(4), quercetin(5), cyclo-(L-Leu-L-Ile)(6), cyclo-(L-Phe-L-Ile)(7), cyclo-(L-Phe-L-Val)(8), cyclo-(L-Leu-L-Val)(9), cyclo-(L-Phe-L-Leu)(10), caffeic acid(11), 3,4-dihydroxycinnamaldehyde(12), p-hydroxybenzoic acid(13), p-hydroxy-cinnamic acid(14), and p-hydroxyphenethyl alcohol(15).Among them, compound 1 was a new fatty acid and compounds 7-10 and 12 were isolated from Morinda plant in the Rubiaceae family for the first time.Compounds 1, 2 and 4-15 were isolated from the seeds of M.citrifolia(Noni) for the first time.All isolated compounds were evaluated for the inhibitory activities against α-glucosidase and compounds 3-5 showed potential inhibitory activity with IC_(50) values of 160, 133, and 120 µmol·L~(-1), respectively.

Ba3Sb2(PO4)4 and Cd3Sb2(PO4)4(H2O)2: Two New Antimonous Phosphates with Distinct [Sb(PO4)2] Structure Types and Enhanced Birefringence.

Two new antimonous phosphates, namely Ba3Sb2(PO4)4 and Cd3Sb2(PO4)4(H2O)2, have been successfully prepared through mild hydrothermal reactions. Ba3Sb2(PO4)4 features a 1D [Sb(PO4)2]3- chain structure separated by Ba2+ cations while Cd3Sb2(PO4)4(H2O)2 presents a 2D [Sb(PO4)2]3- layered structure with Cd2+ located at the interlayer space. The [Sb(PO4)2]3- chain in Ba3Sb2(PO4)4 is the first example of 1D antimonous phosphate structure, and Cd3Sb2(PO4)4(H2O)2 represents the first d10 transition metal antimonous phosphate. Based on UV-vis-NIR spectra, both Ba3Sb2(PO4)4 and Cd3Sb2(PO4)4(H2O)2 can display large optical band gaps (4.30 and 4.36 eV, respectively). But their transparent ranges are quite different because of the coordination water of Cd3Sb2(PO4)4(H2O)2 (500-2000 and 500-1300 nm for Ba and Cd compounds). The anhydrous Ba3Sb2(PO4)4 shows high thermal stability in the nitrogen atmosphere (900 °C). Because of the incorporation of the lone pair cation of Sb(III), the birefringence of Ba3Sb2(PO4)4 and Cd3Sb2(PO4)4(H2O)2 has been enhanced to 0.086 and 0.053 at 532 nm, respectively.

Trait self-control and disinhibited eating in COVID-19: The mediating role of perceived mortality threat and negative affect.

As the coronavirus disease 2019 (COVID-19) spreads globally, people are at risk of developing disinhibited eating behaviors. This study aimed to examine whether perceived mortality threat and negative affect mediate the relationship between trait self-control and disinhibited eating during the pandemic. A longitudinal survey was administered to a sample of college students (N = 634) before the outbreak (September 2019, T1), during the mid-term (February 2020, T2), and in the later stage of the pandemic (April 2020, T3). Self-report measures of trait self-control (T1), perceived mortality threat (T2, T3), negative affect (T2, T3), and disinhibited eating (T2, T3) were successively completed. Trait self-control was found to be negatively associated with negative affect, perceived mortality threat, and disinhibited eating during the mid-term and later stage of the pandemic. Disinhibited eating was positively associated with negative affect and perceived mortality threat. The longitudinal mediation results demonstrated that trait self-control (T1) could negatively predict disinhibited eating (T3) through negative affect (T2) rather than through perceived mortality threat. These findings suggest that trait self-control is of great importance in regulating psychological discomfort and disinhibited eating during stressful periods and that negative affect might be the main psychological mechanism underlying the relationship between self-control ability and disinhibited eating.

3,4- seco-Norclerodane Diterpenoids from the Roots of Polyalthia laui.

Ten new clerodane diterpenoids, polylauioids A-J (1-10), and five known analogues (11-15) were isolated from the roots of Polyalthia laui. Among the new compounds, 3 and 8 are artifacts. The structures were elucidated using spectroscopic methods and by comparison with published NMR spectroscopic data. The absolute configurations of 4, 5, and 7 were defined based on single-crystal X-ray diffraction and electronic circular dichroism data. Compounds 1 and 2 represent the first examples of rearranged 3,4- seco-norclerodane diterpenoids, and a putative biosynthesis pathway for these compounds is proposed. Compounds 1, 4, 6, 7, 9, and 10 showed anti-HIV activities with EC50 values ranging from 12.2 to 35.2 µM.

A biomass-derived porous carbon-based nanocomposite for voltammetric determination of quercetin.

Porous carbon was prepared from wheat flour by alkali treatment and carbonization. The resulting biomass-derived porous carbon (BPC) was employed to prepare a Pt-Au-BPC nanocomposite by a hydrothermal method. The material was then placed on the surface of a carbon ionic liquid electrode (CILE). The Pt-Au-BPC was characterized by SEM, XPS, and the modified CILE by electrochemical methods. They revealed a porous structure, a large specific surface with high conductivity. Pt-Au-BPC/CILE was applied to the sensitive determination of quercetin. Electrochemical response was studied by cyclic voltammetry and differential pulse voltammetry (DPV). Under optimized experimental conditions, the oxidation peak current (measured at 0.48 V vs. Ag/AgCl by DPV) increases linearly in the 0.15 to 6.0 µM and in the 10.0 to 25.0 µM quercetin concentration range. The detection limit is 50.0 nM (at 3σ). The Pt-Au-BPC/CILE was applied to the direct determination of quercetin in ginkgo tablets sample and gave satisfactory results. Graphical abstract A Pt-Au-BPC nanocomposite modified carbon ionic liquid electrode was applied to differential pulse voltammetric determination of quercetin. BPC: biomass-derived porous carbon.

Voltammetric sensing performances of a carbon ionic liquid electrode modified with black phosphorene and hemin.

A black phosphorene (BPE) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) hybrid was used for the immobilization of hemin on a carbon ionic liquid electrode (CILE). BPE inside the PEDOT:PSS film was stable without adverse effects of water and oxygen. The hemin-modified electrode facilitates electrochemical communication with a couple of well-shaped and enhanced redox waves. Therefore BPE exhibits an accelerating function to the electron movement. This sensor exhibits excellent electrocatalytic effects on the reduction of various substrates including trichloroacetic acid (TCA), nitrite and H2O2. As for TCA, the reduction current at -0.36 V (vs. Ag/AgCl) increases linearly in the concentration range from 2.0 to 180 mmol·L-1 with a detection limit of 0.67 mmol·L-1 (at 3σ). As for nitrite, the reduction current at -0.59 Vis linear in the 1.0 to 10.5 mmol·L-1 concentration range, and the detection limit is 0.33 mmol·L-1 (at 3σ). As for H2O2, the reduction current at -0.033 V (vs. Ag/AgCl) is linear in the concentration range from 4.0 to 35.0 mmol·L-1 and the detection limit is 1.3 mmol·L-1 (at 3σ). The real sample was analyzed with satisfactory results, which indicated that BPE had potential applications in the field of electrochemical biosensor. Graphical abstract Photos of (a) black phosphorene (BPE) solution, (b) poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), (c) BPE-PEDOT:PSS (1:5) dispersion, and the fabrication procedure of this electrochemical sensor. It was applied to the determination of trichloroacetic acid, nitrite and hydrogen peroxide.