Flower-like tin oxide membranes with robust three-dimensional channels for efficient removal of iron ions from hydrogen peroxide

Membrane technology has become the mainstream process for the production of electronic grade hydrogen peroxide(H_(2)O_(2)).But due to the oxidation degradation of the organic membranes(e.g.polyamide)by the strong oxidative radicals(e.g.OH)generated via the activation of H_(2)O_(2)by iron ions(Fe^(3+)),the short effective lifetime of membranes remains a challenge.Inorganic nano tin oxide(SnO_(2))has great potential for the removal of Fe^(3+)in strongly oxidative H_(2)O_(2)because of its ability to stabilize H2O_(2)and preferentially adsorb Fe^(3+).Herein,we have designed for the first time a flower-like robust SnO_(2)membrane on the ceramic support by in situ template-free one-step hydrothermal method.The three-dimensional loose pore structure in the membrane built by interlacing SnO_(2)nanosheets endows the SnO_(2)membrane with a high specific surface area and abundant adsorption sites(AOH).Based on the coordination complexation and electrostatic attraction between the SnO_(2)surface and Fe^(3+),the membrane shows a high Fe3+removal efficiency(83%)and permeability(24 L·m^(-2)·h^(-1)·MPa^(-1))in H_(2)O_(2).This study provides an innovative and simple approach to designing robust SnO_(2)membranes for highly efficient removal of Fe^(3+)in harsh environments,such as strong oxidation conditions.

Preparation of PrFe_(x)Co_(1-x)O_(3)/Mt catalyst and study on degradation of 2-hydroxybenzoic acid wastewater by catalytic wet peroxide oxidation

In this study,the perovskite nanocomposite PrFe_(x)Co_(1-x)O_(3)(Pr(S))was successfully synthesized by the sol-gel method;PrFe_(x)Co_(1-x)O_(3)/Al-pillared montmorillonite(Pr(S)/Mt)catalysts were prepared by impregnation(D)method and solid-melting(G)method,respectively,with Pr(S)as the active component and Al-pillared montmorillonite as the carrier.The catalysts were applied to treat the 2-hydroxybenzoic acid(2-HA)-simulated wastewater by catalytic wet peroxide oxidation(CWPO)technique,and the chemical oxygen demand(COD)removal rate and the 2-HA degradation rate were used as indicators to evaluate the catalytic performance.The results of the experiment indicated that the solid-melting method was more conducive to preparing the catalyst when the Co/Fe molar ratio of 7:3 and the optimal structural properties of the catalysts were achieved.The influence of operating parameters,including reaction temperature,catalyst dosage,H_(2)O_(2)dosage,pH,and initial 2-HA concentration,were optimized for the degradation of 2-HA by CWPO.The results showed that 97.64%of 2-HA degradation and 75.23%of COD removal rate were achieved under more suitable experimental conditions.In addition,after the catalyst was used five times,the degradation rate of 2-HA could still reach 76.93%,which implied the high stability and reusability of the catalyst.The high catalytic activity of the catalyst was due to the doping of Co into PrFeO_(3),which could promote the generation of HO·,and the high stability could be attributed to the loading of Pr(S)onto Al-Mt,which reduced the leaching of reactive metals.The study of reaction mechanism and kinetics showed that the whole degradation process conformed to the pseudo-firstorder kinetic equation,and the Langmuir-Hinshelwood method was applied to demonstrate that catalysis was dominant in the degradation process.

One stone two birds:electrochemical and colorimetric dual-mode biosensor based on copper peroxide/covalent organic framework nanocomposite for ultrasensentive norovirus detection

Norovirus(NoV)is regarded as one of the most common causes of foodborne diarrhea in the world.It is urgent to identify the pathogenic microorganism of the diarrhea in short time.In this work,we developed an electrochemical and colorimetric dual-mode detection for NoV based on the excellent dual catalytic properties of copper peroxide/COF-NH_(2)nanocomposite(CuO_(2)@COF-NH_(2)).For the colorimetric detection,NoV can be directly detected by the naked eye based on CuO_(2)@COF-NH_(2)as a laccase-like nonazyme using“peptide-NoV-antibody”recognition mode.The colorimetric assay displayed a wide and quality linear detection range from 1 copy/mL to 5000 copies/mL of NoV with a low limit of detection(LOD)of 0.125 copy/mL.For the electrochemical detection of NoV,CuO_(2)@COF-NH_(2)showed an oxidation peak of copper ion from Cu^(+)to Cu^(2+)using“peptide-NoV-antibody”recognition mode.The electrochemical assay showed a linear detection range was 1-5000 copies/mL with a LOD of 0.152 copy/mL.It's worthy to note that this assay does not need other electrical signal molecule,which provide the stable and sensitive electrochemial detection for NoV.The electrochemical and colorimetric dual-mode detection was used to detect NoV in foods and faceal samples,which has the potential for improving food safety and diagnosing of NoV-infected diarrhea.

Strategies for Sustainable Production of Hydrogen Peroxide via Oxygen Reduction Reaction:From Catalyst Design to Device Setup

An environmentally benign,sustainable,and cost-effective supply of H_(2)O_(2)as a rapidly expanding consumption raw material is highly desired for chemical industries,medical treatment,and household disinfection.The electrocatalytic production route via electrochemical oxygen reduction reaction(ORR)offers a sustainable avenue for the onsite production of H_(2)O_(2)from O2 and H2O.The most crucial and innovative part of such technology lies in the availability of suitable electrocatalysts that promote two-electron(2e^(–))ORR.In recent years,tremendous progress has been achieved in designing efficient,robust,and cost-effective catalyst materials,including noble metals and their alloys,metalfree carbon-based materials,single-atom catalysts,and molecular catalysts.Meanwhile,innovative cell designs have significantly advanced electrochemical applications at the industrial level.This review summarizes fundamental basics and recent advances in H_(2)O_(2)production via 2e^(–)-ORR,including catalyst design,mechanistic explorations,theoretical computations,experimental evaluations,and electrochemical cell designs.Perspectives on addressing remaining challenges are also presented with an emphasis on the large-scale synthesis of H_(2)O_(2)via the electrochemical route.

Kinetic mechanism of copper extraction from methylchlorosilane slurry residue using hydrogen peroxide as oxidant

Copper was extracted from methylchlorosilane slurry residue by a direct hydrogen peroxide leaching method.A number of experimental parameters were analyzed to determine the extraction efficiency of copper.The extraction efficiency of copper reached 98.5%under the optimal leaching conditions,such as the hydrogen peroxide concentration of 1.875 mol·L^(-1),the leaching temperature of 323 K,the liquid–solid ratio of 20 ml·g^(-1),and the stirring speed of 300 r·min^(-1).The leaching kinetics of the copper extraction process was then described by the shrinking core model.There were two stages.The first stage was controlled by chemical reactions,while the second stage was controlled by interface transfer and product layer diffusion.The activation energy and kinetic control equations were determined,as well as an explanation of the leaching mechanism of copper extraction based on kinetic analysis and materials characterization.Copper resources can be recovered from the methylchlorosilane slurry residue efficiently and inexpensively with the methods used in this study.

Carbon Nitride Quantum Dots:A Novel Fluorescent Probe for Non-Enzymatic Hydrogen Peroxide and Mercury Detection

The mercury species in the ocean(MeHg,Hg^(2+))will be enriched in marine organisms and threaten human health through the food chain.While the excessive H_(2)O_(2)in the metabolic process will produce hydroxyl radicals and accelerate the aging of human cells,causing a series of diseases.Hence,the cost-effective and rapid detection of mercury and H_(2)O_(2)is of urgent requirement and significance.Here,we synthesized emerging graphitic carbon nitride quantum dots(g-CNQDs)with high fluorescence quantum yield(FLQY)of 42.69%via a bottom-up strategy by a facile one-step hydrothermal method.The g-CNQDs can detect the H_(2)O_(2)and Hg^(2+)through the fluorescence quenching effect between g-CNQDs and detected substances.With the presence of KI,g-CNQDs show concentration-dependent fluorescence toward H_(2)O_(2),with a wide detection range of 1–1000μmolL^(-1)and a low detection limit of 0.23μmolL^(-1).The g-CNQDs also show sensitivity toward Hg^(2+)with a detection range of 0–0.1μmolL^(-1)and a detection limit of 0.038μmolL^(-1).This dual-function detection of g-CNQDs has better practical application capability compared to other quantum dot detection.This study may provide a new strategy for g-CNQDs preparation and construct a fluorescence probe that can be used in various systems involving H_(2)O_(2)and Hg^(2+),providing better support for future bifunctional or multifunction studies.

Effect of hydrogen peroxide on selective flotation of chalcocite and enargite

Enargite is typically associated with chalcocite.Owing to the similarity in the flotation behaviors of these minerals,both minerals are reported to concentrate in the conventional flotation circuit.However,inorganic arsenic in enargite can decrease the copper concentrate quality and increase the operating cost of processing this concentrate.Separating these minerals is important for cleaner copper production to avoid these effects.In this context,this study investigated the effect of hydrogen peroxide(H_(2)O_(2))treatment on the flotation behavior of chalcocite and enargite.Flotation tests of pure and mixed minerals indicated that H_(2)O_(2)treatment reduced the floatability of chalcocite and enargite by forming sulfate and copper hydroxide on their surfaces.Despite the detrimental effect of the H_(2)O_(2)treatment,there was a narrow window of H_(2)O_(2)concentration for separating both minerals,in which enargite floated and chalcocite was depressed.This selective flotation behavior was caused by the rapid adsorption of potassium amyl xanthate(KAX)and lower surface oxidation of enargite compared with that of chalcocite.

Cryotherapy versus Hydrogen Peroxide in the Treatment of Seborrheic Keratosis

Seborrheic keratosis has a varying degree of pigmentation. In pigmented seborrheic keratosis, the proliferating keratinocytes trigger the activation of neighboring melanocytes by secreting melanocyte-stimulating cytokines. The etiology of seborrheic keratosis is not known. Epidermal growth factors or their receptors have been implicated in the development of seborrheic keratosis. Seborrheic keratoses can safely be left alone, but ugly or easily traumatized ones can be removed with cryotherapy, electrodesiccation, curettage, or shave excision. The present work aims to compare two modalities of treatment for seborrheic keratosis, namely cryotherapy and hydrogen peroxide (30%). Methods: 30 patients with seborrheic keratosis were included in this study. They were divided into two groups, each with 15 patients. The treatment modalities that have been used include cryotherapy and hydrogen peroxide in three different concentrations (30%, 35%, and 40%). Result: The cryotherapy group consisted of 15 patients, 7 males and 8 females. Their ages ranged from 38 to 80 years, with a mean of 56.1 ± 11.4. Clinical and photographic assessments showed complete removal in all 15 patients in this group (100%). As regards the hydrogen peroxide group, this group included 15 patients, distributed among 7 males and 8 females. Their ages ranged from 39 to 90 years, with a mean of 53.9 ± 14.4. Clinical and photographic assessments showed response in only one small superficial lesion in one patient (6.7%) and no response in 14 patients (93.3%). Conclusion: Cryotherapy is an effective, easy, and relatively cheap method for treating seborrheic keratosis.

Efficient hydrogen peroxide production enabled by exploring layered metal telluride as two electron oxygen reduction reaction electrocatalyst

It is of great interest to develop the novel transition metal-based electrocatalysts with high selectivity and activity for two electron oxygen reduction reaction(2e^(-) ORR).Herein,the nickel ditelluride(NiTe_(2)) with layered structure was explored as the 2e^(-) ORR electrocatalyst,which not only showed the highest 2e^(-) selectivity more than 97%,but also delivered a slight activity decay after 5000 cycles in alkaline media.Moreover,when NiTe_(2) was assembled as the electrocatalyst in H-type electrolyzer,the on-site yield of H_(2)O_(2) could reach up to 672 mmol h^(-1)g^(-1) under 0.45 V vs.RHE.Further in situ Raman spectra,theoretical calculation and post microstructural analysis synergistically unveiled that such a good 2e^(-) ORR performance could be credited to the intrinsic layered crystal structure,the high compositional stability,as well as the electron modulation on the active site Ni atoms by neighboring Te atoms,leading to the exposure of active sites as well as the optimized adsorption free energy of Ni to –OOH.More inspiringly,such telluride electrocatalyst has also been demonstrated to exhibit high activity and selectivity towards 2e^(-) ORR in neutral media.

Direct production of hydrogen peroxide over bimetallic CoPd catalysts:Investigation of the effect of Co addition and calcination temperature

A series of CoPd/KIT-6 bimetallic catalysts with various Co:Pd molar ratios at different calcination temperatures were prepared and used for the direct synthesis of H_(2)O_(2) from H_(2) and O_(2).These catalysts were characterized by nitrogen adsorption-desorption,low and wide-angle X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),scanning electron microscopy(SEM),elemental mapping and energy-dispersive X-ray(EDX)methods.It was found that the particle size,electronic interactions,morphology,and textural properties of these catalysts as well as their catalytic activity in the reaction of H_(2) with O_(2) were affected by Co addition and different calcination temperatures.Also,the results showed that while the H_(2)O_(2) selectivity depends on Pd^(2+) species,the H_(2) conversion is related to Pd0 active sites.Among these catalysts,CoPd/KIT-6 calcined at 350℃(CoPd/KIT-350 catalyst)showed the best catalytic activity with 50%of H_(2)O_(2) selectivity and 51%conversion of H_(2).

Ultra‐low single‐atom Pt on g‐C_(3)N_(4)for electrochemical hydrogen peroxide production

Platinum-based materials show excellent electrocatalytic performance and have good potential for use in fuel cells.However,the high cost and scarce reserves have restricted their wide application.Therefore,it is a challenging task to reduce the amount of Pt as well as ensure good catalytic performance.Herein,anchoring of Pt single atoms(0.21 wt‰)with ultra-low content on g-C_(3)N_(4)nanosheets(Pt_(0.21)/CN)has been successfully achieved.The obtained Pt_(0.21)/CN catalyst shows excellent two-electron oxygen reduction(2e-ORR)capability for hydrogen peroxide(H_(2)O_(2)).Compared with CN,its H_(2)O_(2)selectivity increased from 80%to 98%in 0.1M KOH,surpassing those in most of the reported studies.Besides,the H_(2)O_(2)production rate of Pt_(0.21)/CN is 767 mmol gcat^(-1)h-1,which is 11.1 times that of CN.This work may pave the way toward the development of an effective method for the design of noblemetal electrocatalysts with low metal loading and high catalytic activity.

Potential role and therapeutic implications of glutathione peroxidase 4 in the treatment of Alzheimer's disease

Alzheimer's disease is an age-related neurodegenerative disorder with a complex and incompletely understood pathogenesis. Despite extensive research, a cure for Alzheimer's disease has not yet been found. Oxidative stress mediates excessive oxidative responses, and its involvement in Alzheimer's disease pathogenesis as a primary or secondary pathological event is widely accepted. As a member of the selenium-containing antioxidant enzyme family, glutathione peroxidase 4 reduces esterified phospholipid hydroperoxides to maintain cellular redox homeostasis. With the discovery of ferroptosis, the central role of glutathione peroxidase 4 in anti-lipid peroxidation in several diseases, including Alzheimer's disease, has received widespread attention. Increasing evidence suggests that glutathione peroxidase 4 expression is inhibited in the Alzheimer's disease brain, resulting in oxidative stress, inflammation, ferroptosis, and apoptosis, which are closely associated with pathological damage in Alzheimer's disease. Several therapeutic approaches, such as small molecule drugs, natural plant products, and non-pharmacological treatments, ameliorate pathological damage and cognitive function in Alzheimer's disease by promoting glutathione peroxidase 4 expression and enhancing glutathione peroxidase 4 activity. Therefore, glutathione peroxidase 4 upregulation may be a promising strategy for the treatment of Alzheimer's disease. This review provides an overview of the gene structure, biological functions, and regulatory mechanisms of glutathione peroxidase 4, a discussion on the important role of glutathione peroxidase 4 in pathological events closely related to Alzheimer's disease, and a summary of the advances in small-molecule drugs, natural plant products, and non-pharmacological therapies targeting glutathione peroxidase 4 for the treatment of Alzheimer's disease. Most prior studies on this subject used animal models, and relevant clinical studies are lacking. Future clinical trials are required to validate the therapeutic effects of strategies targeting glutathione peroxidase 4 in the treatment of Alzheimer's disease.

Degradation of 2,4-dichlorophenoxyacetic acid in water by ozonehydrogen peroxide process

This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O2/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation of 2,4-dichlorophenoxyacetic acid was studied under different H202/O3 molar ratio and pH value. Meanwhile, TOC removal was investigated both in distilled water and tap water. The influences of ozone transfer and consumed hydrogen peroxide were also discussed. The degradation products and oxidation intermediates were identified by GC-MS and LC-MS. A possible reaction mechanism was thus proposed.

Effects of 45S5 bioglass on surface properties of dental enamel subjected to 35% hydrogen peroxide

Tooth bleaching agents may weaken the tooth structure. Therefore, it is important to minimize any risks of tooth hard tissue damage caused by bleaching agents. The aim of this study was to evaluate the effects of applying 45S5 bioglass （BG） before, after, and during 35% hydrogen peroxide （HP） bleaching on whitening efficacy, physicochemical properties and microstructures of bovine enamel. Seventy-two bovine enamel blocks were prepared and randomly divided into six groups： distilled deionized water （DDW）, BG, HP, BG before HP, BG after HP and BG during HP. Colorimetric and microhardness tests were performed before and after the treatment procedure. Representative specimens from each group were selected for morphology investigation after the final tests. A significant color change was observed in group HP, BG before HP, BG after HP and BG during HP. The microhardness loss was in the following order： group HP〉 BG before HP, BG after HP〉 BG during HP〉DDW, BG. The most obvious morphological alteration of was observed on enamel surfaces in group HP, and a slight morphological alteration was also detected in group BG before HP and BG after HP. Our findings suggest that the combination use of BG and HP could not impede the tooth whitening efficacy. Using BG during HP brought better protective effect than pre/post-bleaching use of BG, as it could more effectively reduce the mineral loss as well as retain the surface integrity of enamel. BG may serve as a promising biomimetic adjunct for bleaching therapy to prevent/restore the enamel damage induced by bleaching agents.

Cytoprotective effects of Morinda offucinalis against hydrogen peroxide-induced oxidative stress in Leydig TM3 cells

Aim： To investigate the antioxidant effects of Morinda officinalis （Morindae radix, MR） on H2O2-induced oxidative stress in cultured mouse TM3 Leydig cells. Methods： We carried out 2,2-diphenyl-1-picrylhydrazyl free radical scavenging, 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide, lipid peroxidation, testosterone enzyme immunoassay, superoxide dismutase （SOD）, and catalase （CAT） assays in Leydig TM3 cells. Results： MR showed a 47.8% 2,2-diphenyl-1-picrylhydrazyl radical scavenging effect in TM3 cells with no significant cytotoxicity. Oxidative stress was induced in TM3 cells with 100 μmol H2O2, and treatment of the cells with 250 μg/mL MR showed the most significant protective effect （64%, P 〈 0.001） in the cell viability assay with a decreased lipid peroxidation level （1.75 nmol/mg protein, P 〈 0.05）, increased testosterone production （43.5 pg/mL）, and improvements in SOD activity （7.49 units of SOD/mg protein, P 〈 0.001） and CAT activity （74.6 units of CAT/mg protein, P 〈 0.001）. Conclusion： These findings indicate that MR, as an antioxidant, protects functions of cultured mouse TM3 Leydig cells from H2O2-induced oxidative stress.

Pretreatment of Rice Straw by Hydrogen Peroxide for Enhanced Methane Yield

A pretreatment process for hydrogen peroxide （H2O2） was optimized to enhance the biodegradation performance of rice straw and increase biogas yield. A determination experiment was conducted under predicted optimal conditions. Optimization was implemented using response surface methodology. The effects of biodegradation and the interactive effects of pretreatment time （PT）, H2O2 concentration （HC）, and substrate to inoculum ratio （S/I） on methane yield were investigated. The lignin, cellulose, and hemicellulose of rice straw were significantly degraded with increasing HC. The optimal conditions for the use of pretreated rice straw in anaerobic digestion were a 6.18-d PT, 2.68% HC （w/w total solid）, and 1.08 S/I; these conditions result in a methane yield of 288 mL g-1 volatile solids （VS）. A determination coefficient of 95.2% was obtained, indicating that the model used to predict the anabolic digestion process has a favorable fit with the experimental parameters. The determination experiment resulted in a methane yield of 290 mL g-1 VS, 88.0% higher than that of untreated rice straw. Thus, H2O2 pretreatment of rice straw can be used to improve methane yields during biogas production.

Reduction of hydrogen peroxide-induced erythrocyte damage by Carica papaya leaf extract

Objective:To investigate thein vitroantioxidant potential of Carica papaya(C. papaya) leaf extract and its effect on hydrogen peroxide-induced erythrocyte damage assessed by haemolysis and lipid peroxidation.Methods:Hydroxyl radical scavenging activities, hydrogen ion scavenging activity, metal chelating activity, and the ferrous ion reducing ability were assessed as antioxidant indices. In the other experiment, human erythrocytes were treated with hydrogen peroxide to induce erythrocyte damage. The extract(at various concentrations) was subsequently incubated with the erythrocytes and later analysed for haemolysis and lipid peroxidation as indices for erythrocyte damage.Results:Preliminary investigation of the extract showed that the leaf possessed significant antioxidant and free radical scavenging abilities usingin vitro models in a concentration dependent manner(P<0.05). The extract also reduced hydrogen peroxide induced erythrocyte haemolysis and lipid peroxidation significantly when compared with ascorbic acid(P<0.05). The IC50values were 7.33 mg/mL and 1.58 mg/mL for inhibition of haemolysis and lipid peroxidation, respectively. In all cases, ascorbic acid(the reference antioxidant) possessed higher activity than the extract.Conclusions:The findings show that C. papayaleaves possess significant bioactive potential which is attributed to the phytochemicals which act in synergy.Thus, the leaves can be exploited for pharmaceutical and nutritional purposes.

Regulatory Function of Polyamine Oxidase-Generated Hydrogen Peroxide in Ethylene-Induced Stomatal Closure in Arabidopsis thaliana

Hydrogen peroxide （H2O2） is an important signaling molecule in ethylene-induced stomatal closure in Arabidopsis thaliana. Early studies on the sources of H2O2 mainly focused on NADPH oxidases and cell-wall peroxidases. Here, we report the involvement of polyamine oxidases （PAOs） in ethylene-induced H2O2 production in guard cells. In Arabidopsis epidermal peels, application of PAO inhibitors caused the failure of ethylene to induce H2O2 production and stomatal closure. Results of quantitative RT-PCR analysis and pharmacological experiments showed that AtPAO2 and AtPAO4 transcripts and activities of PAOs were both induced by ethylene. In transgenic Arabidopsis plants over-expressing AtPAO2 and AtPAO4, stomatal movement was more sensitive to ethylene treatment and H2O2 production was also significantly induced. The increased H2O2 production in the transgenic lines compared to the wild-type plants suggests that AtPAO2 and AtPAO4 probably are involved in ethylene-induced H2O2 production. Several factors which induce stomatal closure such as dehydration and high salinity all enhanced the expression of AtPAO2 and AtPAO4 to different degrees. Moreover, GFP- AtPAOs fusion protein localized in the nucleus, cytoplasm, and cell wall of the guard cells. Therefore, our results strongly indicated that PAO is a source of H2O2 generation in Arabidopsis guard cells and plays crucial roles in stomatal movement.

Evaluation of anti-apoptotic activity of different dietary antioxidants in renal cell carcinoma against hydrogen peroxide

Objective:To evaluate the anti-apoptotic and radical scavenging activities of dietary phenolics, namely ascorbic acid,a-tocopherol acetate,citric acid,salicylic acid,and estimate H_2O_2induced apoptosis in renal cell carcinoma cells.Methods:The intracellular antioxidant potency of antioxidants was investigated.H_2O-2-induced apoptosis in RCC-26 was assayed with the following parameters:cell viability(%apoptosis),nucleosomal damage and DNA fragmentation, bcl-2 levels and flow cytometery analysis(ROS production evaluation).Results:Ine anticancer properties of antioxidants such as ascorbic acid,a- tocopherol acetate,citric acid,salicylic acid with perdurable responses were investigated.It was observed that these antioxidants had protective effect(anti-apoptotic activity) against hydrogen peroxide(H_2O_2) in renal cell carcinoma(RCC-26) cell line.Conclusions:This study reveals and proves the anticancer properties.However,in cancer cell lines anti-apoptotic activity can indirectly reflect the cancer promoter activity through radicals scavenging,and significantly protect nucleus and bcl-2.

Evaluation of Vaporized Hydrogen Peroxide Fumigation as a Method for the Bio-decontamination of the High Efficiency Particulate Air Filter Unit

Objective To evaluate the performance of vaporized hydrogen peroxide （VHP） for the bio-decontamination of the high efficiency particulate air （HEPA） filter unit. Methods Self-made or commercially available bioindicators were placed at designated locations in the HEPA filter unit under VHP fumigation. The spores on coupons were then extracted by 0.5 h submergence in eluent followed by 200- time violent knocks. Results Due to the presence of HEPA filter in the box, spore recovery from coupons placed at the bottom of the filter downstream was significantly higher than that from coupons placed at the other locations. The gap of decontamination efficiency between the top and the bottom of the filter downstream became narrower with the exposure time extended. The decontamination efficiency of the bottom of the filter downstream only improved gently with the injection rate of H202 increased and the decontamination efficiency decreased instead when the injection rate exceeded 2.5 g/min. The commercially available bioindicators were competent to indicate the disinfection efficiency of VHP for the HEPA filter unit. Conclusion The HEPA filter unit is more difficult than common enclosure to decontaminate using VHP fumigation. Complete decontamination can be achieved by extending fumigation time. VHP fumigation can be applied for in-situ biodecontamination of the HEPA filter unit as an alternative method to formaldehyde fumigation.