Mixture Of Peroxide Research Articles

Solvent‐deficient method lowers grain‐boundary resistivity of doped ceria

AbstractNanoparticles of gadolinium‐doped cerium oxide (GDC) were synthesized using solvent‐deficient method and their sinterability and electrical properties were investigated using the powder and cold sintering process. The GDC powder was uniaxially pressed into cylindrically‐shaped pellets with a mixture of nitric acid and hydrogen peroxide at 200°C to encourage particle arrangement during forming process. These bulk samples were annealed using two different temperature profiles: at 800°C for 5 hours and at 1300°C for 1 minute—800°C for 5 hours. The samples produced using HNO3/H2O2 mixture showed higher relative density than ones without it. Ionic conductivity of the sample sintered through the two‐step profile was obtained from electrochemical impedance spectroscopy. Although the grain conductivity for the samples (8.0 × 10−3 S cm−1 at 500°C, and 3.3 × 10−2 S cm−1 at 700°C) is on par with a conventionally sintered sample, the measured total conductivity (3.9 × 10−3 S cm−1 at 500°C, and 2.5 × 10−2 S cm−1 at 700°C) is about 10 times higher than the conventionally sintered one and is comparable to the values seen in the previous studies for GDC which employed higher sintering temperature, pointing to the effectively lower grain‐boundary impedance. This result could be attributed to no significant phase segregation along grain boundaries due to the low‐temperature processing.

Microwave and open vessel digestion methods for biochar

Digestion of biomass derived carbonaceous materials such as biochar (BC) can be challenging due to their high chemical recalcitrance and vast variations in composition. Reports on the development of specific sample digestion methods for such materials remain inadequate and thus require considerable attention. Nine different carbonaceous materials; slow-pyrolyzed tea-waste and king coconut BC produced at 300 °C, 500 °C and 700 °C, sludge waste BC produced at 700 °C, wet fast-pyrolyzed Douglas-Fir BC and steam activated coconut shell BC have been tested to evaluate a relatively fast and convenient open-vessel digestion method using seven digestion reagents including nitric acid (NA), fuming nitric acid (FNA), sulfuric acid (SA), NA/SA, FNA/SA, NA/H2O2 and SA/H2O2 mixtures. From the tested digestion reagents, SA/H2O2 mixture dissolved low temperature produced BC (LTBC) within 2 h with occasional shaking and no external heating. Except peroxide mixtures, the other reagents were used to evaluate microwave digestion (MWD) efficiency. Nitric acid mixture was capable of only completely digesting LTBC in the MWD procedure whereas FNA, NA/SA and FNA/SA mixtures resulted in the successful dissolution of all tested carbonaceous materials. Amongst them, FNA provided the least matrix effect in the quantification of the four metals tested using flame atomic absorption spectrophotometry. Tested recoveries for FNA were satisfactory as well. It was concluded that FNA is a preferable reagent for microwave digestion of BC.

THE EFFECT OF 25% BAY LEAF EXTRACT AND 75% SMALL WHITE GINGER EXTRACT IMMERSION IN THE COLOR CHANGE OF ACRYLIC BASE

B ackground: The most widely used denture is made from heat cured acrylic type. Acrylic resin has some disadvantages, one of which is easy to absorb liquid like water or chemical that affect color change. Alkaline peroxide is a denture cleanser that mostly sold on the market. A mixture of 25% bay leaf and 70% small white ginger extract can be used as natural denture cleanser. Objective: This study aimed to know the color change of heat cured resin base that immersed in a mixture of 25% bay leaf and 70% small white ginger extract. Method: This study was true experimental study with pretest and posttest with control group design, using simple random sampling. The sample wa s round with a diameter of 15mm and thickness 2mm. The samples were 18 heat cured acrylic resins which were divided into 3 groups, the mixture of 25% bay leaf and 70% small white ginger extract, alkaline peroxide, and aquades . The color change of the sample wa s tested using digital analysis tools set . Results: The mean value of color change of heat cured acrylic resin base after immersion in a group of mixed extracts, alkaline peroxide, and aquades w ere (5.22), (3.45) and (2.46). Data were analyzed using the One Way ANOVA parametric test and Bonferroni Post Hoc test. Conclusion: There is a difference in color change on the heat cured resin after immersion in a mixture of extract and alkaline peroxide. The value of a cr ylic resin that immeresed in mix ed extract has the higher color change.

THE EFFECT OF 25% BAY LEAF EXTRACT AND 75% SMALL WHITE GINGER EXTRACT IMMERSION IN THE COLOR CHANGE OF ACRYLIC BASE

B ackground: The most widely used denture is made from heat cured acrylic type. Acrylic resin has some disadvantages, one of which is easy to absorb liquid like water or chemical that affect color change. Alkaline peroxide is a denture cleanser that mostly sold on the market. A mixture of 25% bay leaf and 70% small white ginger extract can be used as natural denture cleanser. Objective: This study aimed to know the color change of heat cured resin base that immersed in a mixture of 25% bay leaf and 70% small white ginger extract. Method: This study was true experimental study with pretest and posttest with control group design, using simple random sampling. The sample wa s round with a diameter of 15mm and thickness 2mm. The samples were 18 heat cured acrylic resins which were divided into 3 groups, the mixture of 25% bay leaf and 70% small white ginger extract, alkaline peroxide, and aquades . The color change of the sample wa s tested using digital analysis tools set . Results: The mean value of color change of heat cured acrylic resin base after immersion in a group of mixed extracts, alkaline peroxide, and aquades w ere (5.22), (3.45) and (2.46). Data were analyzed using the One Way ANOVA parametric test and Bonferroni Post Hoc test. Conclusion: There is a difference in color change on the heat cured resin after immersion in a mixture of extract and alkaline peroxide. The value of a cr ylic resin that immeresed in mix ed extract has the higher color change.

Clinical efficiency of a sodium perborate - hydrogen peroxide mixture for intracoronal non-vital teeth bleaching

Introduction/Objective. The aim was to evaluate initial efficiency of sodium perborate (tetrahydrate) and 30% hydrogen peroxide mixture for intracoronal non-vital teeth bleaching (?walking bleach? technique). Methods. Forty patients with discolored teeth were included in the study. Based on their history and clinical examination, causes of discoloration were classified as necrotic pulp, ?endo-sealer? or unknown. The ?walking bleach? technique was performed by applying sodium perborate (tetrahydrate) and 30% hydrogen peroxide mixture intracoronally to cavity dentin walls. The mixture was renewed in seven-day intervals. Tooth color was assessed visually before, during, and after the procedure using the Vita Classical shade guide (Vita Zahnfabrik, Bad Sackingen, Germany). Numerical values or shade guide units (SGU) were assigned to Vita shade tabs on a bright-dark scale. Analysis of variance, t-test, correlation and regression analysis were used to analyze the data (p < 0.05). Results. On average, 26 ? 9 days or 3?4 appointments were required for intracoronal bleaching to achieve the desired or best possible shade. Better clinical efficiency was found in the necrotic pulp group (17 ? 6 days; 8 ? 3 SGU) than in the ?endo-sealer? group (42 ? 13 days; 4 ? 2 SGU) (p < 0.05). Age significantly influenced bleaching efficiency (p < 0.05). There was no significant correlation between bleaching efficiency and initial shade (p > 0.05). Conclusion. Intracoronal, non-vital teeth bleaching (?walking bleach? technique) using sodium perborate (tetrahydrate) and 30% hydrogen peroxide mixture showed satisfactory clinical efficiency. Discoloration caused by pulp necrosis was treated more efficiently than that caused by endodontic sealers. Younger age had a positive effect and discoloration intensity had no effect on bleaching efficiency.

Dielectric ALD with Hydrogen Peroxide: Comparative Study of Growth and Film Characteristics for Anhydrous H2O2, H2O2/H2o Mixtures, H2o and Ozone

ALD of dielectrics requires new precursor chemistries. Recent development efforts have focused on new Organometallic, Organosilicon and Organoaluminum precursors. Our research focus has been on oxidants, and specifically hydrogen peroxide reactivity. Due to this reactivity, hydrogen peroxide use may allow lower deposition temperatures and achieve distinct properties in the resulting film when compared to other oxidants. Our research study uses: Gas-phase hydrogen peroxide, delivered from an anhydrous, ampoule-based formulation by use of a membrane delivery system.High concentration H2O2/H2O delivery by in situ concentration methods and use of a membrane vaporizer as a gas generator. Initial results for ALD growth of ZrO2 from anhydrous H2O2 and CpZr(N(CH3)3) exhibit high quality growth of film at 260° C. Minimal saturation delay and a linear growth curve were observed. XPS and XRR were used to characterize ZrO2 composition, showing significant similarities to films grown using ozone. Subsequently, films grown using ALD and H2O2 were placed into MIMCAP structures, which had high k values measured at 35. This was a slight improvement over films grown with 20% ozone concentration which had high k values of 32. Novel Gas Generator Our approach involved development of a novel gas generator that delivers H2O2/H2O mixtures. A carrier gas is connected to this generator, which delivers up to 5% H2O2/21% H2O gas by volume from 30wt% H2O2 liquid solution (H2O/H2O2=4.2). This gas mixture enables SiO2 films to be grown at highly reduced temperature compared to water. Initial testing was done with tris(dimethylaminosilane) (N(CH3) 2) 3SiH and H2O2/H2O. SiO2 was deposited at temperatures at least 200° C lower with the hydrogen peroxide mixture than with water. Titanium dioxide ALD is of interest for several applications. The unique properties of this material make it an attractive candidate for advanced patterning applications. Here, low temperature deposition is required (100-250° C). Key required properties of the resultant film include film density and wet etch rate, where low wet etch rates are needed for selective etching of SiO2 vs TiO2. Moreover, high growth per ald cycle (GPC) is needed for increased manufacturing throughput. For TiO2 ALD, we began our study with tetrakis(dimethylamino)titanium (TDMAT) precursor. Our initial goal was to compare the growth and film properties of Ozone (O3) vs Water (H2O) vs H2O2/H2O mixtures. Initial results show that H2O2/H2O mixtures can be grown at growth rates (GPC) 10-20% higher than H2O and 20-50% higher than O3. More significantly, the H2O2/H2O mixtures generate films with wet etch rates (WER) much lower than the traditional oxidants. At 125° C , over 50% reduction in WER was observed for H2O2/H2O vs H2O and over 70% reduction was observed for H2O2/H2O vs O3. Additional comparision data will be reported on wet etch rates, refractive index and composition. Initial composition results by XPS show that residual carbon and nitrogen for the H2O2/H2O film grown at 125° C are non-detectable vs 1.1% carbon and 1.1% nitrogen for Ozone at 125° C. Compositional correlations will be made with respect to wet etch rates. Figure 1

Ion-Implanted Photoresist Stripping by Using Organic Solvents

In the ion implantation process, accelerated ions attack not only target materials but also photoresist, causing deformation of the molecular structure of the photoresist. It is difficult to remove crust layer formed by ion implantation in the standard photoresist removal methods. A typical method of removing high-dose ion-implanted photoresist is to use plasma ashing followed by the treatment in the mixture of hot sulfuric acid and hydrogen peroxide [1]. However, this process etches III-V semiconductors and dielectric materials [2]. Therefore, in this study, organic solvent-based mixtures were developed to remove high-dose ion-implanted photoresist without damaging the substrate. Trench-patterned GaAs was used as a substrate and KrF photoresist was coated on trench patterned GaAs. Then, P+ ion implantation with a dose of 5×1015 ions/cm2 was conducted on the photoresist. A mixed solution of dimethyl sulfoxide (DMSO) and acetonitrile (AcN) (DMSO: AcN = 6: 4) was used to remove the ion-implanted photoresist and 1 vol% HCl or HF was used as an additive. Photoresist removal was measured using an optical microscope and in-situ MIR-FTIR. When a mixed solvent of DMSO and AcN was used to remove ion-implanted photoresist, the photoresist was not completely removed and the residue and crust remained on the trench-pattern (Fig. 1). In order to improve the removal efficiency of ion-implanted photoresist, 1 % HCl or HF was added to DMSO+AcN solution. When 1 % HCl was added to the DMSO+AcN solution, the ion-implanted photoresist with an implantation energy of 30 and 50 keV was completely removed without residue. However, when the ion implantation energy was 70 keV, the photoresist crust was not removed in DMSO+AcN+HCl solution. When 1 % HF was added to DMSO+AcN solution, the ion-implanted photoresists was completely removed regardless of the ion implantation energy. Removal performance was quantitatively analyzed by in-situ MIR-FTIR as shown in Fig. 2. First, the ion-implanted photoresist was not removed more than 40 % for 10 min in DMSO. In DMSO+AcN solution, most of the photoresist was removed in 6 min, and all photoresist was removed in 4 min when DMSO+AcN+HCl was used. In the case of DMSO+AcN+HF, all of the ion-implanted photoresists were completely removed in 2 min and 30 s. Therefore, it is confirmed that DMSO+AcN+HF solution removes ion-implanted photoresist more quickly and effectively than other solutions used in this study. In addition, it is suggested that the largest interaction energy between DMSO+AcN+HF and the ion-implanted photoresist resulted in improvement of the removal efficiency of the photoresist.

A mixture of hydrogen peroxide and tetraglyme as a green energetic monopropellant

An effort is presented to seek a promising candidate for a green energetic monopropellant based on hydrogen peroxide. The novel premixed monopropellant is composed of 90 wt.% H2O2 as the oxidizer and tetraglyme (C10H22O5) as the fuel. Different mixture ratios were prepared by varying the weight percentage of the fuel in the mixture, and the mixtures were named HPM-08 (8 wt.% of fuel), HPM-12 (12 wt.% of fuel), and HPM-20 (20 wt.% of fuel). The theoretical performance of the mixtures was estimated, and their thermostability in air was evaluated via thermogravimetric analysis. A small-scale packed-bed catalytic reactor was utilized to assess the feasibility of the catalytic ignition of HPM-08 with a lanthanum-doped manganese oxide catalyst. Ground hot-firing tests were implemented with an engineering model monopropellant thruster on the scale of 10 N. The demonstrations of the thruster operation using HPM-08 and HPM-12 were successful, but an explosion was caused in the case of HPM-20. A technical speculation suggested that the explosion could be closely related to the phenomenon of detonation. In this study, the configuration of the catalyst bed was regarded as the principal factor in the triggering of detonation in the thruster module. The packed-bed-type catalyst bed containing millimeter-scale pellets may accelerate the phenomenon of deflagration-to-detonation transition, resulting from the rapid compressive heating process based on the superposition of the pressure waves. These results should be taken into account during the design of the catalyst bed in order to utilize particular types of this premixed monopropellant. In addition, a new ignition technique may be applied to prevent the explosion.

Initiated chemical vapor deposition of poly(Hydroxypropyl methacrylate) thin films

Initiated chemical vapor deposition (iCVD) was used to deposit poly(hydroxypropyl methacrylate) (PHPMA) thin films from a reactive mixture of hydroxypropyl methacrylate and tert-butyl peroxide (TBPO) vapors. During iCVD, TBPO served as initiator, which allowed fast depositions on cooled substrate surfaces at low filament temperatures. In the presence of initiator, deposition rates up to 83.3 nm/min, were observed. In the studies performed at different substrate temperatures, a direct relation between the deposition rate and the substrate temperature was observed which indicated a surface-kinetics limited regime. Fourier-transform infrared and X-ray photoelectron spectroscopy analyses showed high structural retention of iCVD PHPMA.

Peroxide impact on the fate of veterinary drugs in fertilizers

The presence of veterinary medicines in organic manure causes soil contamination which contributes to increasing resistance of indigenous microflora to drugs and results in greater susceptibility of people to allergies. The main aim of the study was to assess the efficiency of inorganic peroxide mixtures (PM) with calcium peroxide content (CaO2) in the stabilization process of manure contaminated with antiparasitic agents: albendazole (ALB) and levamisole (LEV). As a solid, CaO2 is relatively stable against decomposition. In contact with water, however, it hydrolyzes with release of oxygen. The hydrolyzation of CaO2 proceeds very slowly in soil, which guarantees the constant release of hydrogen peroxide that subsequently becomes the source of free radicals (chemical oxidation) and oxygen (aerobic conditions for the microbes). It may contribute to continuous elimination of drugs from manure. The study has demonstrated that there were significant differences in ALB and LEV conversion stimulated by the PM addition. PM supplementation increased the drug availability (on average 15% and 25% increase in the initial concentration for ALB and for LEV, respectively), thereby increasing the initial rate of reaction. Elimination of ALB and LEV from the manure sorption complex is followed by Ca2+ saturation. The initial degradation rate was affected by PM for both drugs, but the mechanisms of decomposition have been modified only for ALB. The loss of ALB in the peroxide supplemented samples was 92%, and in the samples, without the PM, it did not exceed 61%. Loss of LEV was over 90% irrespective of PM supplementation.Graphic abstract

Identification of Intermediates in Peroxidase Catalytic Cycle of a DNAzyme Possessing Heme

Abstract Heme in the ferric state (heme(Fe3+)) binds to G-quadruplex DNAs to form stable complexes that exhibit enhanced peroxidase activities. The complexes are considered DNAzymes possessing heme as a prosthetic group (heme-DNAzymes), and have been extensively investigated as promising catalysts for a variety of applications. On ESR and stopped-flow measurements, an iron(IV)oxo porphyrin π-cation radical known as Compound I was detected in reaction mixtures of heme-DNAzymes and hydrogen peroxide. This finding not only resolved the long-standing issue of the mechanism underlying the enhancement of the peroxidase activity of heme(Fe3+) in the scaffold of a G-quadruplex DNA, but also provided new insights as to the design of novel heme-DNAzymes.

Surfactant-Assisted Selective Oxidation of Aromatic Amines to Nitro Compounds by in Situ-Formed Performic Acid.

Development of novel and greener methods for the selective oxidation of various organic compounds is a challenging task. Herein, a novel protocol for the selective oxidation of aromatic amines to nitroaromatics at room temperature is developed. The oxidation reaction was carried out using a mixture of formic acid and aqueous hydrogen peroxide, which resulted in the in situ formation of performic acid. Further, improvement of selectivity was studied using different surfactants, of which cetyltrimethylammonium bromide (CTAB) gave the highest selectivity (85%) toward nitrobenzene. The role of CTAB in achieving higher selectivity is discussed. Under optimized reaction conditions, various substituted amines were successfully oxidized to corresponding nitro compounds. It is worth mentioning that this is the first report on oxidation of amines to nitro compounds in an aqueous medium with high selectivity.

Antimicrobial effect and cytotoxic activity of vinegar-hydrogen peroxide mixture: A possible alternative for denture disinfection

Statement of problemSoaking dentures in vinegar or hydrogen peroxide does not seem to remove the microorganisms involved with prosthetic stomatitis efficiently. A mixture of these 2 substances may be effective, but studies are lacking. PurposeThe purpose of this in vitro study was to evaluate the antimicrobial effect and cytotoxic activity of vinegar-hydrogen peroxide mixtures against Candida albicans and Staphylococcus aureus. Material and methodsFor antimicrobial tests, planktonic cells and biofilms of C. albicans and S. aureus cultured on acrylic resin disks were exposed to 0.5% sodium hypochlorite; 0.2% peracetic acid; vinegar-hydrogen peroxide mixtures at concentration ratios 1:1, 1:3, and 3:1; vinegar-water mixtures at concentration ratios 1:1, 1:3, and 3:1; and hydrogen peroxide-water mixtures at concentration ratios 1:1, 1:3, and 3:1. Antimicrobial activity was evaluated by counting viable colony-forming units after disinfection. For cytotoxicity tests, the 1:1 vinegar-hydrogen peroxide mixture was serially diluted (10−1 to 10−4) and allowed to be in direct contact with HaCaT keratinocytes for 24 hours. Cytotoxicity was quantitatively and qualitatively determined by counting the number of viable cells and analyzing morphological cell changes. ResultsAll vinegar-hydrogen peroxide mixtures, sodium hypochlorite, and peracetic acid efficiently eliminated C. albicans and S. aureus (P<.05), whereas vinegar and hydrogen peroxide solutions used separately were not as efficient as the experimental mixtures. The 10−3 and 10−4 dilutions of vinegar-hydrogen peroxide solutions were considered noncytotoxic, whereas dilutions below 10−2 were strongly cytotoxic, comparable with the 10−2 dilution of 0.2% peracetic acid. ConclusionsThe vinegar-hydrogen peroxide mixture effectively eliminated C. albicans and S. aureus from acrylic resin. Dilutions equal or below 10−2 of this mixture presented strong cytotoxic effects.

Convective boiling heat transfer of methanol – Hydrogen peroxide solutions in a microchannel evaporator

To provide uniform mixture of methanol vapor, steam and oxygen in a methanol reformer, the present study investigates the boiling heat transfer performance and two-phase flow of methanol and 50 wt% hydrogen peroxide mixture in an microchannel evaporator with V-shaped micro diffusers for the entrance region and 52 parallel diverging channels. The decomposition of hydrogen peroxide may produce oxygen and significant amount of heat making the convective boiling of the mixture extraordinary. Experiments of three volume ratios (C) of hydrogen peroxide to methanol of 1/2, 1/3, 1/4 and three flow rates, 0.18, 0.36, and 0.54 ml/min are conducted and analyzed. The experimental results reveal that the addition of hydrogen peroxide can significantly enhance boiling heat transfer as well as the critical heat flux possibly due to the Marangoni convection caused by concentration gradient, but the enhancement is limited by the introduction of decomposition heat internally in the working fluid. The oxygen and enhanced evaporation due to decomposition may make the boiling two-phase flow unstable and deteriorate the heat transfer. Consequently, the mixture with C = 1/3 showing the best heat transfer coefficient may be the optimized working fluid for a microchannel evaporator to serve the purpose of this study.

Preparation of Maleic Anhydride Grafted Poly(trimethylene terephthalate) (PTT-g-MA) by Reactive Extrusion Processing

Maleic anhydride (MA) grafted with poly(trimethylene terephthalate) (PTT)—abbreviated as PTT-g-MA—can be used as a compatibilizing agent to improve the compatibility and dispersion of nanofillers and a dispersed polymer phase into PTT matrix. This work suggests the preparation of PTT-g-MA using a mixture of PTT, MA, and benzoyl peroxide (BPO) by a reactive extrusion process. PTT-g-MA was characterized to confirm the grafting reaction of maleic anhydride on PTT chains by Fourier transform infrared (FTIR) spectroscopy. Thermal properties (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)) and rheological analysis (parallel plates rheology) were used to prove the changes that occurred after the graphitization reaction. The reactive processing route allowed the production of the compatibilizing agent (PTT-g-MA) with good thermal properties and with lower viscosity compared to neat PTT, and this could be an alternative for the compatibilization of polymer blends, as example for PTT/ABS (acrylonitrile butadiene styrene) blends and nanocomposites based on PTT matrix.

Study on the impact of Fe3O4@Au magnetic nanoparticles in metal-assisted chemical etching

Metal-assisted chemical etch (MACE) has received more and more attention due to its low cost and simple process. Ag, Au, Pt and other noble metals can be used as catalyst in the MACE of silicon. In this paper, MACE on silicon in a hydrofluoric acid (HF) and hydrogen peroxide (H2O2) mixture with different HF-to-H2O2 molar ratio R (R = [HF]/([HF] + [H2O2])) with Fe3O4@Au core–shell magnetic nanoparticles (MNPs) as catalyst under an external magnetic field was investigated. Boron doped p-type (100) silicon wafers with resistivity of 20∼30 Ω · cm and 0.01∼0.03 Ω · cm were used as substrates, respectively. We observed that an average etching rate of 5.17 μm min−1 under an applied magnetic field while the average etching rate was 4 μm min−1 without magnetic field. The factors were investigated that affect the average etched depth in silicon substrate under magnetic field by using MACE. The relationship between the average etching depth and etching time, resistivity of silicon substrate, ratio R, and the concentration of Fe3O4@Au magnetic nanoparticles was also studied. This result can be applied to increase the etching rate of silicon to fabricate a variety of devices, where high aspect ratio silicon structure is demanded.

Fabrication and biological evaluation of titanium surfaces with multistage storage space for potential biomedical application

Bacterial infections are the main cause of failure in orthopedic implants, while drug delivery through a localized drug delivery platform is an effective solution. A novel hierarchical structure with multistage storage space was constructed in this study. Hole structures were firstly obtained by etching with a mixture of hydrogen peroxide and aqueous ammonia, and then the nanotube spaces were further constructed on this porous titanium surface by anodization. Results showed that holes of about 30 μm in diameter were formed on the etched surface when the volume concentration of ammonia water was 7%. These holes were homogeneously distributed and the inner walls were smooth. Importantly, titania nanotube arrays on the porous surface were still grown in order without defects. In addition, the modified surface possessed excellent hydrophilicity, and cell experiments have also shown that the platform exhibited enhancing cell proliferation, vitality and osteogenic differentiation, indicating better osseointegration. Finally, the application prospects of the constructed surfaces in the localized drug delivery platform for medical implants were discussed.

Effect of surface-modified silica on the thermal and mechanical behaviors of poly(lactic acid) and chemically crosslinked poly(lactic acid) composites

This work studied the properties of poly(lactic acid) (PLA) and chemically crosslinked poly(lactic acid) (CrPLA) in the presence of different types of silica (SiO2): SiO2 from rice husk ash (RhSiO2) and commercially available SiO2 (CoSiO2). A mixture of triallyl isocyanate and dicumyl peroxide was used as a chemical crosslinking agent. The rice husk was burnt in a furnace to extract RhSiO2. The thermal and mechanical properties of the PLA and CrPLA composites were investigated as a function of the SiO2 content. The presence of C–H functional groups supports the compatibility of stearic acid and RhSiO2, thereby facilitating the esterification reaction observed in the Fourier transform infrared-attenuated total reflectance spectra. This played an important role in changing the properties of the PLA-based composites. The concave fracture surfaces were consistent with the tensile results, the thermal properties, and the degree of swelling, which suggested that there was a better reaction between stearic acid and RhSiO2. However, the heat deflection temperatures of both the PLA and the CrPLA composites were not significantly affected by blending with either CoSiO2 or RhSiO2.

Development of chemical methods for individual decontamination of organophosphorus compounds

The methods of individual decontamination of organophosphorus esters of paralytic action were studied using the decontamination of paraoxon (O, O-diethyl-O-4-nitrophenylphosphate) and methyl parathion (O, O-dimethyl-O-4-nitrophenylthiophosphate) from solid surfaces (metal, fabric, plastic) as an example. The mixtures of urea hydrogen peroxide, boric acid, cetylpyridinium chloride and montmorillonite nanoclay as decontamination systems were studied. The study showed that application of the micellar system together with nanoclays significantly increases a degree of adsorption of substrates from an infected surface. At the same time, the presence of an activator (boric acid) in systems with urea hydrogen peroxide contributes to an increase in the reaction rate in micellar medium by almost 20 times comparing with systems without activation. It was established that the studied micellar systems preserved the supernucleophilicity of НОО – -anion in relation to electrophilic substrates – paraoxon and methyl parathion. It was concluded that the presence of montmorillonite (sodium- and organomodified ones) increased the magnitude of α effect, both in systems with urea hydrogen peroxide only and in systems with boric acid activator. The effect of the acceleration of decomposition of organophosphorus substrates in micellar medium by montmorillonite derivatives was established. This fact could be used for the design of «green» decontamination systems of fast action. An analysis of data on the rate of deactivation of paraoxon and methylparathion on solid surfaces in the studied micellar decontamination systems made it possible to choose the system based on urea hydrogen peroxide, boric acid, cetyl pyridinium chloride and organomodified montmorillonite as the optimal system. A comparison was performed of the periods of half-lives of paraoxon and methylparathion in the studied micellar systems with the known, and applied in NATO subdivisions, decontamination systems. It was concluded that the rates of decontamination in the proposed systems are higher or not less than the rates in the known systems. At the same time, the proposed systems based on solid source of hydrogen peroxide have advantages in terms of environmental safety, manufacturability, and stability. The parameters of the decontamination rate and the degree of decomposition of paraoxon and methyl parathion gives us possibility to recommend the micellar systems as promising for individual deactivation of organophosphorus compounds. The development of fast-acting decontamination formulations, which are mild in their effects on a human body and are environmentally friendly, is a necessary and urgent task among a number of technological solutions for neutralization of toxic organophosphorus substrates, such as pesticides, chemical weapons components and active pharmaceutical ingredients

Occupational asthma caused by peracetic acid-hydrogen peroxide mixture.

Healthcare practice in the UK has moved away from using aldehyde disinfectants for the decontamination of endoscopes, in part due to the risk of respiratory sensitization. Peracetic acid (PAA) in combination with hydrogen peroxide (HP) is a commonly used alternative. We describe a case of occupational asthma (OA) diagnosed at our specialist occupational lung disease clinic and caused by occupational exposure to PAA-HP mixture, used as a disinfectant in an endoscope washer-disinfector machine. A 48-year-old man employed as a mycologist and environmental microbiologist at a Birmingham city hospital, UK, presented following an acute exposure to PAA-HP mixture causing lacrimation, burning optic pain and headache. He had also experienced symptoms suggestive of OA for the preceding 10 months, and the diagnosis was confirmed through OASYS analysis of serial peak expiratory flow measurements. He had been exposed to PAA-HP mixture whilst working in the endoscopy department for 12 months prior to the acute episode, and a subsequent specific inhalation challenge test was positive with a late asthmatic response to PAA-HP mixture. This case provides evidence for a sensitization mechanism in OA caused by PAA-HP mixture.