Decontamination Procedures Research Articles

Evaluation of Different Procedures for Titanium Dental Implant Surface Decontamination-In Vitro Study.

Polymicrobial biofilm removal and decontamination of the implant surface is the most important goal in the treatment of periimplantitis. The aim of this study is to evaluate the efficacy of four different decontamination methods for removing Acinetobacter baumannii and Staphylococcus aureus biofilms in vitro. Seventy-five dental implants were contaminated with a bacterial suspension and randomly divided into five groups (n = 15): the negative control group, which received no treatment; the positive control group, treated with 0.2% chlorhexidine; group 1, treated with a chitosan brush (Labrida BioCleanTM, Labrida AS, Oslo, Norway); group 2, treated with a chitosan brush and 0.2% chlorhexidine; and group 3, treated with a device based on the electrolytic cleaning method (GalvoSurge, GalvoSurge Dental AG, Widnau, Switzerland). The colony-forming unit (CFU) count was used to assess the number of viable bacteria in each sample, and statistical analyses were performed. When compared to the negative control group, all the decontamination methods reduced the CFU count. The electrolytic cleaning method decontaminated the implant surface more effectively than the other three procedures, while the chitosan brush was the least effective. Further research in more realistic settings is required to assess the efficacy of the decontamination procedures described in this study.

Analysis of per- and polyfluoroalkyl substances (PFAS) extraction from contaminated firefighting materials: Effects of cleaning agent, temperature, and chain-length dependencies

This investigation delves into the extraction dynamics of 22 per- and polyfluoroalkyl substances from PFAS contaminated firefighting materials. Two distinct test sets were executed: one contrasting a commercial product with water following an elaborate decontamination procedure, and the other assessing seven washing agents on materials from firefighting installations, with one agent examined at 22 °C and 50 °C. A general tendency for improved desorption at the higher temperature was observed. Furthermore, a discernible influence of the cleaning agent's pH on the extraction of specific PFAS species was observed, elucidating the role of chemical environment in the extraction process. PFAS rebound was studied for a period of up to 157 days, this unveiled a gradual escalation in PFAS22 levels, indicative of a protracted desorption mechanism. Intriguingly, PFAS with abbreviated carbon chains (C4–C6) exhibit superior desorption efficiency compared to their elongated congeners, suggesting a chain-length-dependent decontamination potential. A comparative scrutiny between a commercially available cleaning product, featuring multiple washing and flushing steps, and a water-only treatment regimen underscores the potential efficacy of the former. This exhaustive investigation furnishes nuanced insights into PFAS extraction complexities, offering a foundation for informed decontamination strategies.

Comparative Evaluation of the Osteogenic Potential of Titanium Discs Subjected to Argon Plasma Surface Treatment: An in vitro Study

Abstract Introduction: Titanium is the most widely used material for dental implants; however, its biological aging can lead to a decreased rate of osseointegration. Titanium surfaces on exposure to argon plasma possess a hydrophilic surface that increases the biological activity of osteoblasts on the implant surface. Hence, this in vitro study was undertaken to assess and compare the osteogenic potential and proliferative nature of osteoblast-like cells on titanium when subjected to argon plasma surface treatment. Materials and Methods: A total of 108 titanium discs (10 mm × 2 mm ASTM B348) were included in the study, and their surface topography was characterized. The test specimens were divided into two subgroups based on surface treatments used, i.e. the study group (n = 54): titanium discs treated with argon plasma and the control group (n = 54): sandblasted titanium discs. The osteogenic potential of the specimens was evaluated by assessing the cell attachment using a hemocytometer and cell proliferation using an MTT assay on MG-63 cell lines at three different time intervals of 24, 48, and 72 h. Results: The cell attachment and cell proliferation values were statistically significant (P = 0.001*). In comparison to the control group, these two parameters were considerably greater in the plasma-treated group. The total effect size of the study group was 85% as opposed to 35% of the control group. Conclusion: Argon plasma surface treatment had a positive effect on the cellular events of MG-63 cells which can be thought of as an added advantage along with the decontamination procedure for titanium to help in the process of osseointegration.

UV-Induced Spectral and Morphological Changes in Bacterial Spores for Inactivation Assessment.

The ability to detect and inactivate spore-forming bacteria is of significance within, for example, industrial, healthcare, and defense sectors. Not only are stringent protocols necessary for the inactivation of spores but robust procedures are also required to detect viable spores after an inactivation assay to evaluate the procedure's success. UV radiation is a standard procedure to inactivate spores. However, there is limited understanding regarding its impact on spores' spectral and morphological characteristics. A further insight into these UV-induced changes can significantly improve the design of spore decontamination procedures and verification assays. This work investigates the spectral and morphological changes to Bacillus thuringiensis spores after UV exposure. Using absorbance and fluorescence spectroscopy, we observe an exponential decay in the spectral intensity of amino acids and protein structures, as well as a logistic increase in dimerized DPA with increased UV exposure on bulk spore suspensions. Additionally, using micro-Raman spectroscopy, we observe DPA release and protein degradation with increased UV exposure. More specifically, the protein backbone's 1600-1700 cm-1 amide I band decays slower than other amino acid-based structures. Last, using electron microscopy and light scattering measurements, we observe shriveling of the spore bodies with increased UV radiation, alongside the leaking of core content and disruption of proteinaceous coat and exosporium layers. Overall, this work utilized spectroscopy and electron microscopy techniques to gain new understanding of UV-induced spore inactivation relating to spore degradation and CaDPA release. The study also identified spectroscopic indicators that can be used to determine spore viability after inactivation. These findings have practical applications in the development of new spore decontamination and inactivation validation methods.

N95 respirator hybrid decontamination method using Ultraviolet Germicidal Irradiation (UVGI) coupled with Microwave-Generated Steam (MGS).

The Coronavirus Disease 2019 (COVID-19) pandemic has induced a critical supply of personal protective equipment (PPE) especially N95 respirators. Utilizing respirator decontamination procedures to reduce the pathogen load of a contaminated N95 respirator can be a viable solution for reuse purposes. In this study, the efficiency of a novel hybrid respirator decontamination method of ultraviolet germicidal irradiation (UVGI) which utilizes ultraviolet-C (UV-C) rays coupled with microwave-generated steam (MGS) against feline coronavirus (FCoV) was evaluated. The contaminated 3M 1860 respirator pieces were treated with three treatments (UVGI-only, MGS-only, and Hybrid-UVGI + MGS) with variable time. The virucidal activity was evaluated using the TCID50 method. The comparison of decontamination efficiency of the treatments indicated that the hybrid method achieved at least a pathogen log reduction of 4 logs, faster than MGS and UVGI. These data recommend that the proposed hybrid decontamination system is more effective comparatively in achieving pathogen log reduction of 4 logs.

NONTUBERCULOUS MYCOBACTERIA DIVERSITY IN KARST WATERS AND BIOFILMS IN BULGARIAN CAVES

Background: Nontuberculous Mycobacteria (NTM) are emerging pathogens causing opportunistic infections in humans and animals. Their distribution in the waters and caves of Bulgaria is poorly studied. Climatic changes are associated with changes in the amplitudes of ambient and water temperature, as well as changes in the amount of precipitation which play an essential role in the creation of reservoirs of some types of NTM in the environment. Material and Methods: We optimized the methods for successful isolation of environmental NTM and then used molecular genetic methods for identification. Results: A total of 235 samples (karst water, sediments, soil, bat guano) were collected in some caves of the following karst regions: 203 in Vratsa Karst area, 204 in Ponor Karst area, 205 in Bezdenski area and 303 in Karst and caves of Bosnek region. Primary isolation of mycobacteria by Löwenstein–Jensen at room temperature was more successful than on liquid media at 37°C. We identified NTM in 10% (n=24) from these materials. Diverse NTM included: M. chelonae (n=3), M. gordonae (n=2), M. intermedium (n=3), M. scrofulaceum (n=1), M. szulgai (n=4), M. fortuitum group (n=4), NTM mix culture (n=5), M. terrae complex (n=1), Mycobacterium sp. (n=1). Rapidly growing NTM (M. chelonae, M. fortuitum group) were the most common. The isolates belonged to group of environmental saprophytes (Risk group 1) and potential pathogens (Risk group 2). Conclusions: We successfully implemented a procedure for decontamination and isolation of NTM from the environment. For the first time in the country, NTM species were identified in biofilms, karst waters, soil and bat guano within caves. The presence of NTM in cave ecosystems represents a potential source for human infection.

Hazardous and Toxic Material Decontamination Facility Training in Virtual Reality

Patient decontamination is the act of removing or neutralising hazardous substances from an affected individual. To ensure adequate emergency preparedness, regulations require hospitals to train personnel in decontamination procedures regularly. To supplement in-person training, a virtual reality (VR) system is being developed for the training of hospital staff members in the mass decontamination of hazardous and toxic materials (HAZMAT) and/or radioactively contaminated casualties. As a demonstration of the concept, a primary VR prototype is designed to help users familiarize themselves with a chemical scanner tool, intended for examining victims for residual chemical hazards. This initial prototype showcases the benefits of using VR to create training simulations, complementing existing decontamination training methods in a secure and cost-effective manner. The proposed approach features a modularized user-centric design, a novel scanning simulation, and a high-realism virtual environment and workflow to enhance training effectiveness. A pilot user study and assessment suggest that new users were able to achieve a significant level of competency with VR, compared to users who underwent traditional training.

Evaluation of Truck Cab Decontamination Procedures following Inoculation with Porcine Epidemic Diarrhea Virus and Porcine Reproductive and Respiratory Syndrome Virus.

This experiment aimed to evaluate commercially available disinfectants and their application methods against porcine epidemic diarrhea virus (PEDV) and porcine reproductive and respiratory syndrome virus (PRRSV) on truck cab surfaces. Plastic, fabric, and rubber surfaces inoculated with PEDV or PRRSV were placed in a full-scale truck cab and then treated with one of eight randomly assigned disinfectant treatments. After application, surfaces were environmentally sampled with cotton gauze and tested for PEDV and PRRSV using qPCR duplex analysis. There was a disinfectant × surface interaction (p < 0.0001), indicating a detectable amount of PEDV or PRRSV RNA was impacted by disinfectant treatment and surface material. For rubber surfaces, 10% bleach application had lower detectable amounts of RNA compared to all other treatments (p < 0.05) except Intervention via misting fumigation, which was intermediate. In both fabric and plastic surfaces, there was no evidence (p > 0.05) of a difference in detectable RNA between disinfectant treatments. For disinfectant treatments, fabric surfaces with no chemical treatment had less detectable viral RNA compared to the corresponding plastic and rubber (p < 0.05). Intervention applied via pump sprayer to fabric surfaces had less detectable viral RNA than plastic (p < 0.05). Furthermore, 10% bleach applied via pump sprayer to fabric and rubber surfaces had less detectable viral RNA than plastic (p < 0.05). Also, a 10 h downtime, with no chemical application or gaseous fumigation for 10 h, applied to fabric surfaces had less detectable viral RNA than other surfaces (p < 0.05). Sixteen treatments were evaluated via swine bioassay, but all samples failed to produce infectivity. In summary, commercially available disinfectants successfully reduced detectable viral RNA on surfaces but did not eliminate viral genetic material, highlighting the importance of bioexclusion of pathogens of interest.

Bond Strength to Lithium-Disilicate Ceramic after Different Surface Cleaning Approaches.

To evaluate the effect of different lithium-disilicate (LiSi) glass-ceramic surface decontamination procedures on the shear bond strength (SBS) to resin cement. Seventy CAD/CAM LiSi ceramic specimens (IPS e.max CAD, Ivoclar) were cut and sintered. Fifty specimens were treated with 5% hydrofluoric acid (HF) for 20 s, while 20 were left untreated. All 70 specimens were then contaminated with human saliva and try-in silicone paste. The following surface cleaning methods were investigated (n = 10): C: water rinsing (control); PA: 37% H3PO4 etching for 20 s; E: 70% ethanol applied for 20 s; CP: cleaning paste (Ivoclean, Ivoclar) brushed for 20 s; HFSEP: self-etching ceramic primer (Monobond Etch&Prime, Ivoclar) rubbed for 20 s; HF: 5% HF applied for 20 s or no HF etching prior to contamination; SEP: self-etching ceramic primer rubbed for 20 s and no HF etching prior to contamination. Composite cylinders were created and luted with an adhesive resin cement to the decontaminated surfaces. After storage for 24 h at 37°C, the SBS test was conducted. Two fractured specimens per group were observed under SEM to perform fractographic analysis. The data were statistically analyzed with p set at <0.05. The type of surface cleaning approach influenced bond strength (p < 0.001). HFSEP, SEP, and HF attained higher SBS (p < 0.001) compared to other groups. None of the approaches were able to completely remove contaminants from the ceramic surfaces. SEM images showed residual traces of contaminants on CP-treated surfaces. The self-etching ceramic primer enhanced bond strength to contaminated LiSi ceramic surfaces, irrespective of previous treatment with hydrofluoric acid.

APDI meets PPE: photochemical decontamination in healthcare using methylene blue-where are we now, where will we go?

Personal protective equipment (PPE) reuse, first recommended in the context of the SARS-CoV-2 pandemic, can mitigate shortages in crisis situations and can greatly reduce the environmental impact of typically single-use PPE. Prior to safe reuse, PPE must be sanitized and contaminating pathogens-in current circumstances viruses in particular-must be inactivated. However, many established decontamination procedures are not equitable and remain unavailable in low-resource settings. In mid-2020, an interdisciplinary consortium of researchers first studied the potential of implementing cheap and easy-to-use antimicrobial photodynamic inactivation (aPDI) using methylene blue as photosensitizer to decontaminate face masks and filtering facepiece respirators. In this perspective piece, we describe the development of this novel method, discuss recent advances, and offer insights into how equitable PPE decontamination via methylene blue-based aPDI may be integrated into circular economy policies in the healthcare sector.

How to Defeat Multidrug-Resistant Bacteria in Intensive Care Units. A Lesson from the COVID-19 Pandemic. Prevention, Reservoirs, and Implications for Clinical Practice.

Background: Intensive care unit (ICU) patients are at high risk of infection due to multiple invasive procedures, malnutrition, or immunosuppression. The rapid increase in infections with multidrug-resistant organisms (MDRO) during the COVID-19 pandemic caused a dilemma, as the rules of the sanitary regime in ICU rooms were strictly adhered to in the prevailing epidemiological situation. The combat to reduce the number of infections and pathogen transmission became a priority for ICU staff. This study aimed to assess whether eliminating environmental reservoirs and implementing improved procedures for patient care and decontamination and washing equipment in the ICU reduced the incidence of infections caused by MDR strains. Material and methods: The study retrospectively analyzed data in the ICU during the COVID-19 pandemic. The samples were collected based on microbiological culture and medical records in the newly opened ICU (10 stations) and hospital wards where COVID-19 patients were hospitalized. Environmental inoculations were performed during the COVID-19 pandemic every 4-6 weeks unless an increase in the incidence of infections caused by MDR strains was observed. Through microbiological analysis, environmental reservoirs of MDR pathogens were identified. The observation time was divided into two periods, before and after the revised procedures. The relationship between isolated strains of Klebsiella pneumoniae NDM from patients and potential reservoirs within the ICU using ERIC-PCR and dice methods was analyzed. Results: An increased frequency of infections and colonization caused by MDRO was observed compared to the preceding years. A total of 23,167 microbiological tests and 6,985 screening tests for CPE and MRSA bacilli were collected. The pathogen spread was analyzed, and the findings indicated procedural errors. Assuming that the transmission of infections through the staff hands was significantly limited by the restrictive use of personal protective equipment, the search for a reservoir of microorganisms in the environment began. MDR strains were grown from the inoculations collected from the hand-wash basins in the wards and from inside the air conditioner on the ceiling outside the patient rooms. New types of decontamination mats were used in high-risk areas with a disinfectant based on Glucoprotamine. Active chlorine-containing substances were widely used to clean and disinfect surfaces. Conclusions: Infections with MDR strains pose a challenge for health care. Identification of bacterial reservoirs and comprehensive nursing care significantly reduce the number of nosocomial infections.

Water Decontamination Products for Wound Irrigation in Austere Environments: Benchtop Evaluation and Recommendations.

Irrigation is used to minimize infection of open wounds. Sterile saline is preferred, but potable water is becoming more widely accepted. However, the large volumes of water that are recommended are usually not available in austere environments. This study determined the long-term antimicrobial effectiveness of military purification powder compared with currently available civilian methods. The study also compared the physical characteristics and outcomes under the logistical constraints. Six commercially available water decontamination procedures were used to decontaminate five different sources of water (pond water, river water, inoculated saline, tap water, and sterile saline). Each product was evaluated based on six different parameters: bacterial culture, pH, turbidity, cost, flow rate, and size. All methods of treatment decreased the bacterial count below the limit of detection. However, they had variable effects on pH and turbidity of the five water sources. Prices ranged from $7.95 to $350, yielding 10-10,000L of water, and weighing between 18 and 500g. In austere settings, where all equipment is carried manually, no single decontamination device is available to optimize all the measured parameters. Since all products effectively reduced microbial levels, their size, cost, and production capability should be evaluated for the intended application.

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.

Next-Generation Sequencing to Elucidate the Semen Microbiome in Male Reproductive Disorders.

Mean sperm counts are declining at an accelerated rate and infertility is increasingly becoming a public health concern. It is now understood that human semen, previously considered to be sterile, harbours its own specific microbiome. Via activated leucocytes and the generation of reactive oxygen species, bacteria have the capability of evoking an immune response which may lead to sperm damage. Men with infertility have higher rates of both reactive oxygen species and sperm DNA damage. Due to the lack of sensitivity of routine culture and PCR-based methods, next-generation sequencing technology is being employed to characterise the seminal microbiome. There is a mounting body of studies that share a number of similarities but also a great range of conflicting findings. A lack of stringent decontamination procedures, small sample sizes and heterogeneity in other aspects of methodology makes it difficult to draw firm conclusions from these studies. However, various themes have emerged and evidence of highly conserved clusters of common bacteria can be seen. Depletion or over-representation of specific bacteria may be associated with aberrations in traditional and functional seminal parameters. Currently, the evidence is too limited to inform clinical practice and larger studies are needed.

Proteome of spores from biological indicators in sterilization processes: Bacillus pumilus and Bacillus atrophaeus.

Bacillus atrophaeus and Bacillus pumilus spores are widely used as biological indicators to assess the effectiveness of decontamination procedures. Spores are intricate, multi-layered cellular structures primarily composed of proteins, which significantly contribute to their extreme resistance. Therefore, conducting a comprehensive proteome analysis of spores is crucial to identify the specific proteins conferring spore resistance. Here, we employed a high-throughput shotgun proteomic approach to compare the spore proteomes of B. atrophaeus DSM675 and B. pumilus DSM492, identifying 1312 and 1264 proteins, respectively. While the overall number of proteins found in both strains is roughly equivalent, a closer examination of a subset of 54 spore-specific proteins revealed noteworthy distinctions. Among these 54 proteins, 23 were exclusively detected in one strain, while others were shared between both. Notably, of the 31 proteins detected in both strains, 10 exhibited differential abundance levels, including key coat layer morphogenetic proteins. The exploration of these 54 proteins, considering their presence, absence, and differential abundance, provides a unique molecular signature that may elucidate the differences in sensitivity/resistance profiles between the two strains.

Treatment of Peri-implantitis: Fiction or Reality? Part 1: Non-surgical and Surgical Management

Peri-implantitis is a biological complication characterized by an inflammatory process affecting the soft and hard tissues around an osseo-integrated load-bearing implant. Clinically, it results in progressive bone loss, pocket formation, bleeding and/or suppuration and leads to implant loss. Although the main aetiological factor is bacterial biofilms, the clinical presentation and progression of peri-implantitis is exacerbated by several local, systemic and iatrogenic factors. Treatment protocols of peri-implantitis include various decontamination procedures of the exposed implant surface. In this two-part series, we will review the available evidence for the non-surgical and surgical management of peri-implantitis (Part 1), and then we will discuss various modalities for implant surface decontamination (Part 2). CPD/Clinical Relevance: The pre-operative risk identification and management at both patient and site level, early diagnosis and regular supportive peri-implant care are fundamental for long term implant success and survival.

Characterization of decontamination procedure of beef carcasses at slaughterhouses in the province of Antioquia, Colombia

BACKGROUND: Beef slaughterhouses must use a carcass decontamination procedure to control pathogens and thus prevent foodborne diseases transmitted by meat. OBJECTIVES: This study aimed to characterize beef carcass decontamination procedures at slaughterhouses located in the province of Antioquia (Colombia). All the slaughterhouses were open, registered, and approved by Invima (Instituto Nacional de Vigilancia de Medicamentos y Alimentos in Spanish) at the time of the study. METHODS: This descriptive study collected information from 23 beef slaughterhouses between July 2019 and April 2021 through documentary reviews and visits to slaughterhouses, using forms and questionnaires. RESULTS: The study allowed the characterization of the procedures used to decontaminate beef carcasses, showing that the chemical disinfection of the carcasses is used to control microorganisms in at least 73.9% of the slaughterhouses analyzed. According to secondary sources, it was found that most of the slaughterhouses are small (slaughter volume &lt;50,000 heads per year); 10 of them use citric acid, lactic acid, peracetic acid, and a mixture of organic acids in concentrations between 900 and 1,200 ppm, 1.5 and 1.7%, 180 and 190 ppm, and 900 and 1,200 ppm, respectively, as carcass disinfectants and according to the technical data sheet of the product. During the visits and through the application of the questionnaire, it was found that the 12 slaughterhouses had implemented chemical disinfection which is not scientifically based, using manual devices as an intervention method to control pathogenic microorganisms. It was found that the type of company, slaughter volume, and the lack of financial resources are the determining factors in the selection of decontamination procedures. The validation of the beef carcass decontamination procedures in the different slaughterhouses in the study was demonstrated. CONCLUSIONS:Although it was established that at least one decontamination procedure, such as chemical disinfection, is used in the slaughterhouses of study, this option is not supported by scientific or technical evidence. The findings support the need for improvements in the slaughterhouses of the province of Antioquia, including the improvement of surveillance programs to reduce pathogens in the meat chain effectively.

Evaluation of different decontamination procedures on bond strength to sound and caries affected dentin using “no-wait” universal adhesive

BackgroundCurrent study aimed to evaluate the effect of different decontamination procedures on micro-shear bond strength (μSBS) of sound (SoD) and caries-affected dentin (CAD) of two universal adhesives after blood-saliva contamination.MethodsOne hundred and eighty bovine anterior teeth were prepared and allocated into the respective groups according to tested dentin substrates [SoD, CAD], universal adhesives [Clearfil Bond Universal Quick (UBQ), All-Bond-Universal (ABU)], adhesive contamination stage [none, contamination before and after adhesives light-curing], and according to decontamination procedures [no decontamination, water rinsing, adhesive rebond, Ethylenediaminetetraacetic acid (ETDA) and chlorhexidine (CHX) application]. Universal adhesives were applied according to manufacturer instructions in self-etch (SE) bonding mode. Four composite microrods were built for each tooth. Specimens were kept in distilled water for 24 hours at 37°C before testing μSBS. Four-way ANOVA and Tukey HSD tests were used for data analysis.ResultsA statistically significant difference between contamination stages of both universal adhesives at different decontamination procedures for SoD and CAD. Highest μSBS was recorded for UBQ control group at SoD, while the least was recorded for light-cured ABU upon water rinsing decontamination procedure of CAD.ConclusionsProper cavity isolation is mandatory to avoid possible contamination which can dramatically affect μSBS. CHX is a potent cavity decontaminant that can restore different dentin substrates bond strength. EDTA presents a promising substitute. UBQ adhesive showed better bonding performance than ABU to both dentin substrates. Application of regular cavity decontamination approaches is highly advised in daily practice to avoid possible detrimental effect of accidental cavity contamination.

Removal of pesticides from fresh-cut Chinese cabbage (Brassica rapa var. chinensis L.) by sequential multi-frequency ultrasound cleaning treatments

Pesticides may remain on the surface of fresh produce due to inappropriate and inadequate cleaning. In view of the public health significance of pesticide residues in fresh produce and the long-term effects of low dose exposure of these pesticides, decontamination procedures are needed for ready-to-eat foods, especially vegetables. Ultrasound cleaning is considered to be an effective environmentally-friendly decontamination process which is unique in its ability to remove pesticides compared to other conventional methods. The reduction of dimethoate and diazinon residues from fresh Chinese cabbage by sequential multi-frequency ultrasound cleaning treatments was investigated in this study to ascertain the levels of reduction after cleaning. The ultrasonic treatment has higher efficiency on the removal of these organophosphorus pesticides compared to ordinary water cleaning. The removal rates of ultrasonic cleaning treatments for dimethoate and diazinon residues were in the range of 20.10–72.42% and 29.60–77.37% compared to the ordinary water cleaning with 13.24–19.89% and 17.32–24.16% respectively. In addition, quality parameters for the leaves treated were also assessed. The physical impairment and vitamin C loss increased with the increase in ultrasonic frequency combination and cleaning time. Application of triple frequency ultrasound and extended washing time resulted in high dimethoate (>70%) and diazinon reduction (>75%) alongside slight perceptible darkening in colour of the leaves. The use of multi-frequency ultrasound in sequential mode is an effective technique for the removal of pesticide residues from leafy vegetables. However, ultrasonic operating conditions should be considered to maintain product quality.

Temperature dependence of Cs release during oxidation of Cs-loaded graphite

As one of potential treatments for irradiated graphite (i-graphite) waste, the oxidation method has been attracting more concern due to features of high treating efficiency and significant volume reduction. The release of fission products during oxidation is of great significance for further off-gas decontamination procedures. Focusing on the release behavior of volatile cesium (Cs), Cs-loaded graphite was prepared by impregnation in this work followed by definite distribution and chemical speciation analyzing. Results showed that the increasing temperature and humidity during the oxidation were evidenced to promote the release of Cs compounds, and the chemical speciation of released compounds was prominently dependent on oxidizing temperature. When the oxidation temperature was around 700 °C, Cs2O was predominately released with the morphology of spherical particles. When the oxidation temperature was increased to 900 °C, the predominant releasing composition turned to Cs2CO3 with morphologies of both spherical particles and nanorod-like shapes. The different predominant releasing chemical compositions at different temperatures mainly resulted from the kinetics of graphite oxidization and temperature synergistically. These findings will provide theoretical foundations to the environmental evaluation of i-graphite thermal oxidation.