Chemical Decontamination Research Articles

Catalytic Hydrolysis of Paraoxon by Immobilized Copper(II) Complexes of 1,4,7-Triazacyclononane Derivatives.

Organophosphate neuroactive agents represent severe security threats in various scenarios, including military conflicts, terrorist activities and industrial accidents. Addressing these threats necessitates effective protective measures, with a focus on decontamination strategies. Adsorbents such as bentonite have been explored as a preliminary method for chemical warfare agent immobilization, albeit lacking chemical destruction capabilities. Chemical decontamination, on the other hand, involves converting these agents into non-toxic or less toxic forms. In this study, we investigated the hydrolytic activity of a Cu(II) complex, previously studied for phosphate ester hydrolysis, as a potential agent for chemical warfare decontamination. Specifically, we focused on a ligand featuring a thiophene anchor bound through an aliphatic spacer, which exhibited high hydrolytic activity in its Cu(II) complex form in our previous studies. Paraoxon, an efficient insecticide, was selected as a model substrate for hydrolytic studies due to its structural resemblance to specific chemical warfare agents and due to the presence of a chromogenic 4-nitrophenolate moiety. Our findings clearly show the hydrolytic activity of the studied Cu(II) complexes. Additionally, we demonstrate the immobilization of the studied complex onto a solid substrate of Amberlite XAD4 via copolymerization of its thiophene side group with dithiophene. The hydrolytic activity of the resultant material towards paraoxon was studied, indicating its potential utilization in organophosphate neuroactive agent decontamination under mild conditions and the key importance of surface adsorption of paraoxon on the polymer surface.

Decontamination of Bacterial Spores Using a Bio-reaction System

This report describes the test results of decontamination of Bacillus atrophaeus spores. The spore solution at 109 cfu/mL concentration was treated with chemical decontaminants, hydrogen peroxide, DF-200, sodium dichloroisocyanurate(NaDCC), and perasasfe. DF-200 was not suitable for decontamination of the spore solution. Among them, the optimal decontamination reaction conditions of perasafe and NaDCC were established from test tube experiments in a mL-scale, and they were validated in a bio-reaction system in a L-scale. The optimal conditions of perasafe and NaDCC were 1.0 % of concentration with 5 minutes of reaction time and 0.3 % of concentration with 10 minutes of reaction time, respectively. Also, both decontaminants required adequate agitation for decontamination. The results in the bio-reaction system were similar with the results from the smaller scale using test tubes, showing that the optimal conditions from the smaller scale experiments can be applied to the larger scale.

A Study on the Efficacy of Four Chemical Decontaminants against High-concentration Surrogates of Bacteria, Toxin, and Virus Biological Agents

If a nation or a terrorist organization produced biological agents, they are likely stored in a form of liquid concentrate. In the present study, four chemical reagents, hydrogen peroxide, sodium dichloroisocyanurate (NaDCC), Perasafe, and DF200, were investigated on their potentials as safe, efficient and eco-friendly decontaminants for biological agents. <i>Escherichia coli</i>, α-amylase, and bacteriophage T4 were used as surrogate strains for biological agents. Hydrogen peroxide and DF200 showed drawbacks of a rapid heat evolution upon neutralization and thick foam building up, respectively. Perasafe was effective against <i>E. coli</i> and T4, but it did not inactivate α-amylase while the others were able to inactivate all three types of the surrogates. NaDCC was the most suitable decontaminant for its effectiveness against all three types of surrogates at low concentrations and being able to be neutralized without aforementioned problems.

Long-term inflammatory outcome after placement of a novel two-piece dental implant in a dog model experimental peri-implantitis.

Evaluate the inflammatory outcome of a two-piece novel titanium dental implant (test article) vs. a one- piece titanium dental implant (control article) inducing experimental peri-implantitis in a dog model. A novel, two-piece pre-assembled implant with a 0.2-thickness sleeve in its coronal 4.2mm part was developed (Test article). Ligature-induced experimental periimplantitis model was applied, followed by decontamination and bone grafting in seven dogs. Four groups were assessed according to decontamination and resurfacing protocol: E1 (Experimental 1): test article- sleeve removed, mechanical and chemical decontamination, new rough surface non-threaded sleeve was inserted; E2 (Experimental 2): test article- sleeve removed, mechanical and chemical decontamination, test article remained denuded presenting a turned non-threaded surface; C1 (Control 1): sleeve remained, mechanical and chemical decontamination in test article, original rough surface, non-threaded sleeve; C2 (Control 2): control article cleaning, mechanical and chemical decontamination of original rough surface, threaded implant. Buccolingual and mesiodistal sections were prepared for each site. Resin qualitative and semi-quantitative histopathologic inflammatory parameters were analyzed. Group C1 showed statistically significant highest signs of residual long-term inflammation, followed by groups E1, and C2. Group E2 displayed the lowest local inflammation. Mesio/Distal aspects displayed increased long-term inflammatory infiltrate albeit not statistically significant. Within the limits of the present study, it may be concluded that - (1) The decontamination procedure is more effective in a commercial one-piece vs. a two-piece dental implant. (2) Mechanical and chemical decontamination outcome is insufficient. Resurfacing improves the decontamination outcome. (3) Decontamination of the turned surface is superior to the rough surface. When choosing the most appropriate dental implant for individuals with a high risk for peri-implant disease, a one-piece dental implant with a turned crestal surface is preferable. Once occurring, the control of peri-implant disease inflammation may be more successful. Decontamination is usually not enough. Resurfacing is highly recommended if possible.

Enhancing bioethanol yield from food waste: Integrating decontamination strategies and enzyme dosage optimization for sustainable biofuel production

Amidst the global surge in energy demand, the public’s focus has shifted from fossil fuels to more sustainable and eco-friendly fuels like bioethanol. Thus, the prospect of producing bioethanol from food waste (FW) is gaining traction, offering a sustainable solution to both waste management and energy needs. However, increasing bioethanol yields during food waste fermentation requires an approach that addresses the variability of these heterogeneous feedstocks in terms of chemical composition, microbial contamination, enzyme dosage requirements, and high moisture content. Hence, this study evaluated thermal and chemical decontamination strategies for pre- and post-consumer food waste and minimised the exogenous enzyme dosage by applying an engineered, amylase-producing strain (Saccharomyces cerevisiae ERT12). Results show that thermal sterilisation at an elevated liquefaction temperature significantly improved ethanol yields (from pre-and post-consumer food waste) more than chemical decontamination methods. Also, key findings show that applying the amylase-secreting yeast reduced enzyme dosages by up to 33 %. During fed-batch fermentation with strain ER T12, the highest possible solids loading increased the final ethanol concentrations by 96 % (for pre-consumer FW) and 85 % (for post-consumer FW) compared to batch fermentation. Also, the pre-consumer to post-consumer FW fed-batch fermentation maintained acceptable volumetric production rates of 2.35 to 1.57 g/l.h and yielded 87.6 to 61.2 % of the theoretical maximum. Although the maximum solids loadings, ethanol titres and yields achievable in food waste fermentations were still limited by the inherent moisture contents of the feed, they demonstrated performances that may be appropriate for industrial implementation, considering the negative feedstock costs.

Effects of chemical & biological warfare agent decontaminants on trace survival: Impact on DNA profiling from blood and saliva

Forensic investigations following incidents involving chemical or biological agents present considerable challenges. Understanding the possibilities and limitations can aid in determining the most suitable procedures and enhancing the recovery of useful traces in these complex situations. This work complements previously published results on the effects of decontaminants on fingermarks deposited on glass. Identifying the perpetrators can be crucial, and DNA analysis remains a cornerstone in this regard. In this study, we investigated the ability to obtain usable DNA profiles from blood and saliva (pure and diluted) exposed to 16 different decontamination methods. Both DNA quantitation and DNA profiling were considered to assess the outcomes. The results revealed considerable variability but indicated that biological agents' decontaminants hindered DNA profiling post-decontamination to a greater extent than decontaminants aimed for chemical agents. Chlorine-based decontaminants also globally had a deleterious impact on DNA profiling. Powder decontaminants such as Fast-Act, CHpowder, and the liquid decontaminants GDS2000 did not affect DNA profiling.

Time-series satellite remote sensing reveals gradually increasing war damage in the Gaza Strip.

War-related urban destruction is a significant global concern, impacting national security, social stability, people's survival and economic development. The effects of urban geomorphology and complex geological contexts during conflicts, characterized by different levels of structural damage, are not yet fully understood globally. Here we report how integrating deep learning with data from the independently developed LuoJia3-01 satellite enables near real-time detection of explosions and assessment of different building damage levels in the Israel-Palestine conflict. We found that the damage continually increased from 17 October 2023 to 2 March 2024. We found 3747 missile craters with precision positions and sizes, and timing on vital infrastructure across five governorates in the Gaza Strip on 2 March 2024, providing accurate estimates of potential unexploded ordnance locations and assisting in demining and chemical decontamination. Our findings reveal a significant increase in damage to residential and educational structures, accounting for 58.4% of the total-15.4% destroyed, 18.7% severely damaged, 11.8% moderately damaged and 12.5% slightly damaged-which exacerbates the housing crisis and potential population displacement. Additionally, there is a 34.1% decline in the cultivated area of agricultural land, posing a risk to food security. The LuoJia3-01 satellite data are crucial for impartial conflict monitoring, and our innovative methodology offers a cost-effective, scalable approach to assess future conflicts in various global contexts. These first-time findings highlight the urgent need for an immediate ceasefire to prevent further damage and support the release of hostages and subsequent reconstruction efforts.

Tuning FeO covalency boosts catalytic ozonation over spinel oxide for chemical industrial wastewater decontamination

AbstractHeterogeneous catalytic ozonation (HCO) emerges as a promising chemical industrial wastewater treatment solution, offering enhanced ozone utilization and reduced secondary pollutants. However, challenges in scaling HCO arise from a limited understanding of the catalytic mechanisms of metal oxides, particularly in generating active ozone sites. Here, we demonstrated the improvement of catalytic ozonation efficiency by enhancing the covalent bonding between FeO in Fe/Co spinel oxides. This alteration exploits the stronger electron‐donating capacity of Fe (II), enhancing FeOM bonds and electron enrichment at iron sites, leading to a significant reduction in the activation energy for ozone. Pilot experiments demonstrated a 75.3% COD removal efficiency and a threefold increase in ozone utilization efficiency compared to pure ozone system for chemical industrial wastewater treatment. This study not only advances our understanding of spinel oxides in ozone catalysis but also opens new avenues for practical HCO applications in water treatment.

Prevention of the Growth of Fungi and Aflatoxins in Bread Leftovers Used as Animal Feed

Background: Aflatoxin contamination poses a significant threat to food safety, particularly in bread products used as animal feed. This review explores various strategies for preventing fungal growth and aflatoxin production. Objective: To assess the efficacy of traditional and emerging decontamination methods for managing aflatoxin contamination in food commodities, with a focus on bread products. Methods: A systematic review of literature from databases such as PubMed and ScienceDirect was conducted, focusing on studies published in the last two decades. The review included chemical, physical, and biological decontamination methods, as well as natural antifungal agents derived from medicinal plants. Results: Chemical methods such as sodium hypochlorite and sodium bisulfite showed varying degrees of efficacy in reducing aflatoxin levels. Natural antifungal agents like garlic, neem leaves, and eucalyptus leaves demonstrated significant antifungal properties. The prevalence of aflatoxins in bread samples varied across different countries, highlighting the global challenge of aflatoxin contamination. Conclusion: Emerging decontamination methods offer promising alternatives to traditional techniques for managing aflatoxin contamination. Further research is needed to optimize these methods and ensure their safety for human consumption.

Optimized precipitation process for the treatment of radioactive effluents from Ni-alloy decontamination using a chemical oxidation reduction process

Nuclear power plays a major role in the generation of electricity with low carbon emissions. However, it generates significant amounts of radioactive waste, mainly from contaminated metallic components such as steam generators. Decontamination is essential for the safe handling and eventual recycling or disposal of these materials. Various decontamination techniques can be utilized but chemical processes are recommended for complex geometries such as the tubular parts of steam generators. COREMIX (Chemical Oxidation REduction using nitric permanganate and oxalic acid MIXture) is a process that is similar to the CORD (Chemical Oxidation Reduction Decontamination) process currently utilized in the industry which involves dissolving the contaminated oxide layers from metallic surfaces. This process generates a large quantity of radioactive effluent that requires appropriate treatment. The objective is to reduce metallic concentration and the radioactivity by precipitating metals in solution as hydroxides M(m-n)(OH)n (with m the oxidation number of the metal M). The optimization of a two-step precipitation protocol is presented here, with a study of the contact time (1–24 h) and the reagents used (NaOH and KOH). The resulting precipitates from this process are characterized using several techniques (FTIR, TGA and XRD). Tests were conducted on surrogate samples to demonstrate the viability of the process on more complex samples. Finally, the optimized protocols were implemented on radioactive Ni-alloy samples. Decontamination factors were calculated portraying the efficiency of both the COREMIX and the subsequent two-stage precipitation process. Characterization of the sludge produced during the process shows that the precipitate obtained at pH 8.5 consists mainly of iron (III) oxide-hydroxides, whereas the precipitate obtained at pH 12 is mainly composed of manganese (II,III) oxide. The optimization steps show that the contact time during the first precipitation and the choice of precipitants does not influence the efficiency of the protocol while the destruction of oxalic acid proves to be critical to quantitatively precipitate chromium. Ultimately, the COREMIX process can effectively decontaminate contaminated Ni-alloy samples, removing between 12% and 14% of the contamination in each cycle. Decontamination of effluent using the precipitation protocol results in a very high decontamination factor of between 3000 and 6000.

Isolation and identification of fungal biodeteriogens from the wall of a cultural heritage church and potential applicability of antifungal proteins in protection

Fungi are able to permanently damage cultural heritage buildings and stone monuments. Protection against these biodeteriogen fungi is challenging because it may require the use of drastic techniques to remove fungal colonies and chemicals, which can cause further damage, especially on mural paintings. Natural biocides are less damaging, greener, and safer and mainly include essential oils and plant-derived substances. Studies on the applicability of purified antifungal proteins in the conservation of cultural heritage buildings are lacking. In this study, we isolated mold mycoflora from the biodeteriorated inner walls of the Calvinist church of Kézdialbis (Kézdialbis, Romania) and investigated the in vitro antifungal efficacy of Neosartorya (Aspergillus) fischeri antifungal proteins, NFAP and NFAP2 against them. Antifungal susceptibility testing revealed that these proteins inhibited the growth of the most commonly isolated indoor biodeteriogen fungi from the site (Aspergillus creber, Aureobasidium pullulans, Cladosporium sp., Penicillium chrysogenum, and Parengyodontium album) and not common ones (Mucor hiemalis, Sarocladium kiliense) with different spectra and efficacies. A phytopathogen and an entomopathogen species (Pseudopithomyces chartarum and Beauveria pseudobassiana, respectively) were also isolated and described first as fungal biodeteriogens of the inner walls. Among them, P. chartarum was susceptible to NFAP2. Next, we tested the applicability of NFAP and NFAP2 in protecting cultural heritage buildings in a wall model experiment against A. creber. Topical application of both antifungal proteins significantly decreased the area infected by fungi. Scanning electron microscopy of the wall models showed that A. creber had reduced growth and conidiation in the presence of NFAP and NFAP2. This inhibitory activity was maintained for a long time. Strong UV irradiation decreased the protective effect of both proteins in the wall model. Taking into account these results, the high stability of NFAP and NFAP2 in harsh environments, and their bulk recombinant producibility, we suggest that both can be used in the protection and posttreatment of painted walls of cultural heritage buildings to clean up mural painting or to inhibit mold recolonization after mechanical, physical, or chemical decontamination.

Preliminary insights on the development of a continuous-flow solar system for the photocatalytic degradation of contaminants of emerging concern in water.

The ubiquity and impact of pharmaceuticals and pesticides, as well as their residues in environmental compartments, particularly in water, have raised human and environmental health concerns. This emphasizes the need of developing sustainable methods for their removal. Solar-driven photocatalytic degradation has emerged as a promising approach for the chemical decontamination of water, sparking intensive scientific research in this field. Advancements in photocatalytic materials have driven the need for solar reactors that efficiently integrate photocatalysts for real-world water treatment. This study reports preliminary results from the development and evaluation of a solar system for TiO2-based photocatalytic degradation of intermittently flowing water contaminated with doxycycline (DXC), sulfamethoxazole (SMX), dexamethasone (DXM), and carbendazim (CBZ). The system consisted of a Fresnel-type UV solar concentrator that focused on the opening and focal point of a parabolic trough concentrator, within which tubular quartz glass reactors were fixed. Concentric springs coated with TiO2, arranged one inside the other, were fixed inside the quartz reactors. The reactors are connected to a raw water tank at the inlet and a check valve at the outlet. Rotating wheels at the collector base enable solar tracking in two axes. The substances (SMX, DXC, and CBZ) were dissolved in dechlorinated tap water at a concentration of 1.0mg/L, except DXM (0.8mg/L). The water underwent sequential batch (~ 3 L each, without recirculation) processing with retention times of 15, 30, 60, 90, and 120min. After 15min, the degradation rates were as follows: DXC 87%, SMX 35.5%, DXM 32%, and CBZ 31.8%. The system processed 101 L of water daily, simultaneously removing 870, 355, 256, and 318µg/L of DXC, SMX, DXM, and CBZ, respectively, showcasing its potential for real-world chemical water decontamination application. Further enhancements that enable continuous-flow operation and integrate highly effective adsorbents and photocatalytic materials can significantly enhance system performance.

Decontamination of spent ion-exchange resins from the nuclear fuel cycle using chemical decontamination and direct current

The study presents the results of deep decontamination of the spent ion-exchange resin from the Kursk NPP, where the task of processing and conditioning of the resin is still not solved. The article shows that decontamination of the resin under dynamic conditions with a solution of the composition NaOH – 0.75 mol L−1, NaNO3 – 2.25 mol L−1 reduces its activity by 1 order of magnitude due to removal of Cs-137 (by washing). The subsequent washing of the resin with a solution of H2SO4 – 1.0 mol L−1, FeSO4 – 0.5 mol L−1 results in a decrease of its activity by another 1 order of magnitude due to removal of Eu-152-154 (100%) and partial removal of Co-60 (90%) and Am-241 (92%).It was found that further attempts to reduce the activity of the resin were ineffective due to the presence of insoluble precipitates, whose activity was mainly (more than 98%) accounted for by Co-60 (30.2%) and Nb-94 (68.1%) radionuclides. To remove these poorly soluble precipitates, we suggested decontamination by direct current through placing the resin between an anode and a cathode. A solution of H2SO4 of a concentration of 0.1 mol L−1 was used as an electrolyte. It has been found that an addition of FeSO4 (0.009 mol L−1) increases the rate of precipitate removal more than 1.5-fold. During the treatment by electric current, particles are mechanically removed, whereas insignificant amounts of Cs-137 and Co-60 (no more than 2.6%) enter the electrolyte. After the treatment and washing the resin with a NaNO3 solution, its activity decreases by another three orders of magnitude. The resulting activity of the resin was 350 Bq kg−1, which made it possible to classify it as industrial waste.

Effectiveness of mechanical and chemical decontamination methods for the treatment of dental implant surfaces affected by peri-implantitis: A systematic review and meta-analysis.

To assess which decontamination method(s) used for the debridement of titanium surfaces (disks and dental implants) contaminated with bacterial, most efficiently eliminate bacterial biofilms. A systematic search was conducted in four electronic databases between January 1, 2010and October 31, 2022. The search strategy followed the PICOS format and included only in vitro studies completed on either dental implant or titanium disk samples. The assessed outcome variable consisted of the most effective method(s)-chemical or mechanical- removing bacterial biofilm from titanium surfaces. A meta-analysis was conducted, and data was summarized through single- and multi-level random effects model (p < .05). The initial search resulted in 5260 articles after the removal of duplicates. After assessment by title, abstract, and full-text review, a total of 13 articles met the inclusion criteria for this review. Different decontamination methods were assessed, including both mechanical and chemical, with the most common method across studies being chlorhexidine (CHX). Significant heterogeneity was noted across the included studies. The meta-analyses only identified a significant difference in biofilm reduction when CHX treatment was compared against PBS. The remaining comparisons did not identify significant differences between the various decontamination methods. The present results do not demonstrate that one method of decontamination is superior in eliminating bacterial biofilm from titanium disk and implant surfaces.

Anatomical three-dimensional model with peri-implant defect for in vitro assessment of dental implant decontamination.

Access to the implant surface plays a significant role in effective mechanical biofilm removal in peri-implantitis treatment. Mechanical decontamination may also alter the surface topography of the implant, potentially increasing susceptibility to bacterial recolonization. This in vitro study aimed to evaluate a newly developed, anatomically realistic, and adaptable three-dimensional (3D)printed model with a peri-implant bone defect to evaluate the accessibility and changes of dental implant surfaces after mechanical decontamination treatment. A split model of an advanced peri-implant bone defect was prepared using 3D printing. The function of the model was tested by mechanical decontamination of the exposed surface of dental implants (Standard ImplantStraumann AG) coated with a thin layer of colored occlusion spray. Two different instruments for mechanical decontamination were used. Following decontamination, the implants were removed from the split model and photographed. Image analysis and fluorescence spectroscopy were used to quantify the remaining occlusion spray both in terms of area and total amount, while scanning electron microscopy and optical profilometry were used to analyze alteration in the implant surface morphology. The 3D model allowed easy placement and removal of the dental implants without disturbing the implant surfaces. Qualitative and quantitative assessment of removal of the occlusion spray revealed differences in the mechanism of action and access to the implant surface between tested instruments. The model permitted surface topography analysis following the decontamination procedure. The developed 3D model allowed a realistic simulation of decontamination of implant surfaces with colored occlusion spray in an advanced peri-implant defect. 3D printing allows easy adaptation of the model in terms of the shape and location of the defect. The model presents a valuable tool for in vitro investigation of the accessibility and changes of the implant surface after mechanical and chemical decontamination.

Isolation and assessment of Pseudomonas aeruginosa and Bacillus cereus as PCB-degrading bacteria in environmental bioremediation

Classical methods of treatment of polychlorinated biphenyls (PCBs) in environmental matrices such as soil encapsulation, high-temperature heating, thermal desorption, and chemical decontamination, have been costly, and they leave behind problems of environmental footprints. They must therefore give way to bioremediation techniques which are less costly and result in eco-friendly products. The aim of the study was to assess the suitability of PCB degrading bacteria (using published data) from their environmental matrix for use in environmental bioremediation. Initial isolation of the bacteria was obtained by culturing ash samples taken from the combustion chamber of an MP400 Incinerator of infectious waste at Komfo Anokye Teaching hospital (KATH) in Kumasi, Ghana, and composite soil samples taken from a transformer-servicing site at an electricity substation in Sunyani, Ghana. Test for thermotolerance was carried out by the culturing of bacteria from the soil samples and exposing them to higher temperatures (55 °C and 65 °C) to assess their resilience in an incubator for 48 h. Growing cultures were sub-cultured, after which a cocktail of bacteria isolate characterization assays was carried out on the growing isolates. These included biochemical tests on the bacterial suspensions using the analytical profile index (API 20E) for examining Enterobacteriaceae and other non-fastidious bacteria. This was followed by MALDI-ToF-MS analyses of the bacterial strains to profile and image their proteins. A molecular step was needed which was the conventional polymerase chain reaction (PCR) method, using specific primer pairs, to amplify and accentuate sections of the bacterial DNA extracts. Results of the study showed a confirmed sample site in Ghana for harvesting bacteria capable of degrading polychlorinated biphenyls (PCBs). MALDI-ToF-MS analyses revealed the possible species as Pseudomonas aeruginosa and Bacillus cereus. The conventional PCR and gel electrophoresis steps confirmed the presence of bph genes encoding the 2,3-dioxygenase enzymes in bacteria with PCB-degrading ability as documented in published data. The serial dilution of the bacterial suspensions was modified from 10−7 to 10−5 which was enough for distinct colonies to be counted, and it was a novel contribution to environmental microbiology. The confirmation of Pseudomonas and Bacillus species isolated from a transformer oil-impacted soil in this study shows promise in growing these strains in various environmental media such as in a gaseous medium to mineralize gas-phase PCBs from combustion smoke or in bottom ash residues to degrade solid-phase PCBs. It can also be applied in bioremediation of waste liquid systems containing PCBs.

Biofouling on titanium implants: a novel formulation of poloxamer and peroxide for in situ removal of pellicle and multi-species oral biofilm.

Eradicating biofouling from implant surfaces is essential in treating peri-implant infections, as it directly addresses the microbial source for infection and inflammation around dental implants. This controlled laboratory study examines the effectiveness of the four commercially available debridement solutions '(EDTA (Prefgel®), NaOCl (Perisolv®), H2O2 (Sigma-Aldrich) and Chlorhexidine (GUM® Paroex®))' in removing the acquired pellicle, preventing pellicle re-formation and removing of a multi-species oral biofilm growing on a titanium implant surface, and compare the results with the effect of a novel formulation of a peroxide-activated 'Poloxamer gel (Nubone® Clean)'. Evaluation of pellicle removal and re-formation was conducted using scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy to assess the surface morphology, elemental composition and chemical surface composition. Hydrophilicity was assessed through contact angle measurements. The multi-species biofilm model included Streptococcus oralis, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans, reflecting the natural oral microbiome's complexity. Biofilm biomass was quantified using safranin staining, biofilm viability was evaluated using confocal laser scanning microscopy, and SEM was used for morphological analyses of the biofilm. Results indicated that while no single agent completely eradicated the biofilm, the 'Poloxamer gel' activated with 'H2O2' exhibited promising results. It minimized re-contamination of the pellicle by significantly lowering the contact angle, indicating enhanced hydrophilicity. This combination also showed a notable reduction in carbon contaminants, suggesting the effective removal of organic residues from the titanium surface, in addition to effectively reducing viable bacterial counts. In conclusion, the 'Poloxamer gel + H2O2' combination emerged as a promising chemical decontamination strategy for peri-implant diseases. It underlines the importance of tailoring treatment methods to the unique microbial challenges in peri-implant diseases and the necessity of combining chemical decontaminating strategies with established mechanical cleaning procedures for optimal management of peri-implant diseases.

Cobalt and zinc nanoparticles from pyrolysis of their MOF precursors exhibiting potent organophosphorus hydrolase-mimicking activities.

Cobalt and zinc nanoparticles from pyrolysis of cobalt-containing ZIF-67 and zinc-containing ZIF-90 exhibited potent organophosphorus hydrolase-mimicking activities for the hydrolysis of organophosphorus compounds within minutes at pH 9.0 and 25-40 °C. The resulting nanozymes could find potential applications in many areas such as chemical decontamination, environmental protection and defense of chemical weapons.

A Systematic Review on Microencapsulation Technique and its Application

Abstract: Micro-encapsulation is the process of encapsulating a compound in a small sphere called a microsphere / microcapsule. The diameter of the microspheres can range from 1 mm up to several hundred micrometers. Many different active materials have been successfully encapsulated in microballoons / microcapsules made from polymeric and non-polymer materials such as poly (ethylene glycol), methacrylate, poly (styrene), cellulose, poly (lactide), gelatine and acacia. The content of the microcapsules is released at the appropriate time using different release mechanisms according to the end use of the encapsulated product. This technology has been used in many industries such as pharmaceuticals, agri-food, printing, cosmetics, textiles and defence. In the defence sector, it has been used to create self-healing composite as well as chemical decontamination fabrics. This review highlights the main reasons for microencapsulation technology, important techniques for the encapsulation of products and applications of the technology in various fields of science and technology.

Reaction dynamics and early-time behaviour of chemical decontamination

Abstract When a hazardous chemical soaks into a porous material such as a concrete floor, it can be difficult to remove. One approach is chemical decontamination, where a cleanser is added to react with and neutralise the contaminating agent. The goal of this paper is to investigate the reaction dynamics and the factors that affect the efficacy of the decontamination procedure. We consider a one-dimensional porous medium initially saturated with an oil-based agent. An aqueous cleanser is applied at the surface, so the two chemicals are immiscible and a boundary forms between them. A neutralising reaction takes place at this boundary in which cleanser and agent are consumed and reaction products are created. This is a Stefan problem, and the boundary between the cleanser and agent moves as the reaction proceeds. Reaction products formed at the interface may dissolve in one or both liquids. This may temporarily prevent cleanser and/or agent from reaching the reaction site, so diffusion of the chemical species, in particular the diffusion of product from the interface, plays a key role. The scenario described above was considered previously by Dalwadi et al. (2017, Mathematical modelling of chemical agent removal by reaction with an immiscible cleanser. SIAM J. Appl. Math., 77, 1937–1961) in the limit where the depth of the porous medium is large compared to the length scale over which concentrations vary inside the medium. Here, we present results that are valid for any ratio between these length scales and an analysis of agent removal times for various dimensionless parameter regimes. We also highlight the emergence of a boundary layer associated with diffusion in the oil phase for early times, where the thickness of the boundary layer is directly proportional to the square root of the time variable.