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The aim of this work was to determine the changes in the chemical and physical-mechanical properties of gauze compresses under the influence of various sterilizations. Gauze compresses are made of cotton; therefore, all methods used focused on cotton. The methods used to test possible damage to cotton materials (pH value (pH paper, KI starch paper), yellowing test, Fehling reaction, reaction to the formation of Turnbull blue (Berlin blue), microscopic staining with methylene blue and swelling reaction with Na-zincate) did not show that the sterilizations affected the cotton compresses. The morphological characteristics were examined with a scanning electron microscope (SEM). The SEM images showed that there were no morphological changes in the cotton fibers. FTIR-ATR spectroscopy revealed that the sterilization processes did not alter the characteristic bands of the cotton. The length of the macromolecules was increased (DP), showing that the sterilization processes had affected the cotton. The results of the wet strength test followed. The samples showed values below 100%, with the exception of two samples. It is known from theory that the relative wet strength is less than 100% when the material is damaged. The t-test performed on the strength results showed that the p-value was greater than 0.05 for all samples tested, with the exception of one sample. The degree of swelling capacity was determined, with non-sterilized samples having the highest capacity, followed by samples sterilized with ethylene oxide and then samples sterilized by steam sterilization. The results obtained are a contribution to the innovation of the topic of this work and a scientific confirmation for manufacturers and anyone interested in the influence of the sterilization process on natural fibers (cotton). [ABSTRACT FROM AUTHOR]

Polyamide materials are widely used for medical device coating. However, despite the fragile area at the interface, these devices must conserve their physical and mechanical performance after the sterilization process. In this work, the impact of steam sterilization, widely used in the medical sector, on the adhesion properties of biocompatible and biosourced polyamide-11-coated copper substrates was assessed. The adhesion strength, a quantitative indicator of the coating performance, was assessed thanks to a laboratory-made bench test. The surface of metal substrates was microstructured with laser engraving to enhance the coating adhesion. The Ra roughness value was varied to verify if the depth of valleys induced with the femtosecond laser could favor the interfacial anchoring. Scanning electron microscopy analyses highlighted the physical surface evolution of the polymer analyzed at the interface, across the various texturing parameter values, Ra. Fourier transform infrared spectroscopy was used to monitor the bands specific to polyamide thermo-oxidative degradation. Elemental composition deduced from X-ray photoelectron spectroscopy carried out on the coating after mechanical debonding clearly revealed that the chemical stability of the copper substrates was affected rather than the polyamide coating. Also, we discussed the impact of the chosen sterilization parameters (steam and pressure) on the formation of copper-based species detected with this technique. [ABSTRACT FROM AUTHOR]

This study conducted sterilization testing under different conditions using different strains for sterilization and crushing, the intermediate healthcare waste treatment phase, and proposed strategies for diversifying corresponding facilities in addition to promoting their installation. Five indicator microorganisms were selected to test the sterilization efficiency of steam, microwave, and chemical methods. Steam sterilization testing was conducted in accordance with legal and technological standards, microwave testing was carried out according to the legal standard, and chemical sterilization employed three typical compounds. Steam and microwave sterilization achieved 99.9999 % inactivation rates for all five strains under both conditions used; whereas under the chemical sterilization analyses, sodium hypochlorite (1000 ppm) failed to meet the inactivation requirement of the fungal strain Candida albicans, requiring further investigation. Based on these findings, this study presents strategies for diversifying sterilization·crushing facilities and promoting their installation.

The aim of this work was to determine the changes in the chemical and physical-mechanical properties of gauze compresses under the influence of various sterilizations. Gauze compresses are made of cotton; therefore, all methods used focused on cotton. The methods used to test possible damage to cotton materials (pH value (pH paper, KI starch paper), yellowing test, Fehling reaction, reaction to the formation of Turnbull blue (Berlin blue), microscopic staining with methylene blue and swelling reaction with Na-zincate) did not show that the sterilizations affected the cotton compresses. The morphological characteristics were examined with a scanning electron microscope (SEM). The SEM images showed that there were no morphological changes in the cotton fibers. FTIR-ATR spectroscopy revealed that the sterilization processes did not alter the characteristic bands of the cotton. The length of the macromolecules was increased (DP), showing that the sterilization processes had affected the cotton. The results of the wet strength test followed. The samples showed values below 100%, with the exception of two samples. It is known from theory that the relative wet strength is less than 100% when the material is damaged. The t-test performed on the strength results showed that the p-value was greater than 0.05 for all samples tested, with the exception of one sample. The degree of swelling capacity was determined, with non-sterilized samples having the highest capacity, followed by samples sterilized with ethylene oxide and then samples sterilized by steam sterilization. The results obtained are a contribution to the innovation of the topic of this work and a scientific confirmation for manufacturers and anyone interested in the influence of the sterilization process on natural fibers (cotton).

Gellan gum, a polysaccharide with structural similarities to glycosaminoglycans, is gaining attention in cartilage tissue engineering. It can be chemically modified with methacrylic moieties to produce a photo-crosslinkable formulation, called methacrylated gellan gum (GGMA), envisaging the injection and the in situ cross-linking through light on the cartilage surface.This study aimed to investigate the visible light cross-linking of GGMA, underlying the impact of steam sterilization on its chemical and rheological properties and cross-linking efficiency. After an initial assessment of the sterilization effects, we evaluated a combination of hydrogel concentrations (1 and 2 % w/v), ruthenium/sodium persulfate concentrations (0.1/1, 0.2/2 and 0.5/5 mM ratios), and light exposure times (30, 60 and, 120 s). The formulations with the lowest sol fraction were characterized for mechanical and showed self-healing properties. Biological characterization on encapsulated chondrocytes in hydrogels showed high cell viability with increased metabolic activity over two weeks. The expression of genes encoding collagen type II and cartilage oligomeric matrix protein was upregulated in the softer formulation (E = 0.95 ± 0.48 kPa) composed of 2 % w/v GGMA, 0.1/1 mM Ru/SPS, and photo-crosslinked for 60 s. These findings represent an interesting overview of the potential application of visible-light crosslinked GGMA in the clinical scenario to treat cartilage defects.

Most of the diseases affecting plant nurseries are soil borne and to eradicate the pathogens from growing media different sterilization (chemical, solar and steam) techniques are used. Steam sterilization is more efficient and environmentally friendly technology. To test the effectiveness of steam sterilization in controlling growth of fungal pathogens, different fungal species were isolated from various potting media (soil, sand, silt, FYM and coconut coir) pre and post steam sterilization and the isolates were characterized. Pre-sterilization fungal isolation was performed using serial dilution method which revealed different fungal species i.e., Aspergillus flavus, A. niger, Fussarium solani, Penicillium spp, Rhizoctonia spp, Curvularia spp, and Pythium spp. After sterilization, one group of potting media was kept open and the other one was tightly packed and placed at ambient temperature. These open and covered media types were evaluated for fungal regrowth by isolation after 7 days, 15 days and 30 days intervals. Different fungal contaminants were found in the potting media that was kept opened after sterilization. However, interestingly no soil related fungal pathogens were observed in the packed potting media 30 days post sterilization. These findings extended the current knowledge of steam sterilization of potting media and suggest that steam sterilization can effectively eliminate the fungal pathogens from the media. Further, it could be effectively used to produce sanitated plant nurseries and minimize the spread of soil borne diseases. [ABSTRACT FROM AUTHOR]

The concept of the presented research was to assess the applicability of natural colorants in dyeing biocomposites filled with natural fillers. As dyes, ground coffee, turmeric, couscous and ground paprika were used. Additionally, wood flour and walnut shell flour were added to improve strength parameters. The fillers were not dyed prior to processing, but the pigments were processed with the matrix and the filler. The optical observation and the influence of steam sterilization on mechanical properties were carried out, taking into consideration esthetics and performance of the product. The results showed that natural colorants can be successfully used to dye composites. Low-density biocomposites with increased rigidity were obtained. Composites were characterized by lower tensile strength than neat green polyethylene which was approximately 18 MPa. The high result for tensile modulus was obtained for composition with coffee – it increased to 2045 MPa.

The amount of the toxic waste generated in the hospitals and medical facilities is steadily increasing. Although, the centralized disposal or waste management service solutions for the removal of toxic waste are available in highly developed industrialized countries; this does not, however, apply to the developing and emerging countries. For this reason, a compact sterilization and shredding machine was developed. The steam sterilization used (temperatures of 134 °C + 4 K and pressures of 480 to 3500 mbar) complies with the recognized procedure of the Robert Koch Institute (without chemical substances). Thus, it was possible to transform the infectious or toxic waste into non-hazardous household waste. The microbiological and physical test results show that the machine meets the requirements for sterilization of class C solid and liquid clinical wastes. The capacity of the machine is maximum 400 liters of waste per cycle, with an average cycle time of about 1 hour. It is possible to process contaminated materials both loose and in sealed disposal containers (C-boxes).

Background: Experts in Steam Sterilization recognize the importance of configuring the vacuum system to control wet loads, but the impact has not been quantitatively demonstrated. This pilot study aims to analyse the impact of different vacuum configurations on the final volume of condensate in steam sterilized loads. Methods: Several vacuum configurations have been tested: number of vacuum pulses in the conditioning phase, vacuum depth in the conditioning phase, time delay when reaching the vacuum set in the conditioning phase, vacuum speed in the conditioning phase, and vacuum depth in the drying phase. Results: The findings showed a strong relationship with condensate formation, confirmed by Pearson Correlation Coefficients: number of pulses (-0.962), vacuum depth (0.89), time delay when reaching the vacuum set in the conditioning phase (-0.949), vacuum speed (0.969) and vacuum depth in the drying phase (0.989). The best-case scenario was characterized by 4 vacuum pulses, 50mbar vacuum depth in conditioning, 180 seconds of vacuum delay before steam injection, 283seconds (3mbar/sec) vacuum speed and 50mbar of vacuum depth in drying; resulting in an average volume of 8.7mL. All the vacuum measurements are absolute terms (0mbar means the theoretical complete absence of air). Conclusion: The configuration of the vacuum system can potentially impact the control of wet loads. [ABSTRACT FROM AUTHOR]

Current standards and procedures for parametric load release are based on technologies from the 1960s, are consensus based and are often not supported by scientific evidence. In the literature, however, methods are reported which can fairly easily be implemented and improve current parametric load release for steam sterilization. To implement an improved parametric load release procedure, exceeding the current standards and methods for monitoring steam sterilization processes. Implementation of the procedure should be feasible for all interested end-users. The steam sterilization criteria specified in the literature were used to define a set of steam sterilization conditions. A search for commercially available devices and methods which can assess these conditions parametrically was performed. After selecting a method, a field study was carried out. Two devices were identified which could be used to improve parametric load release after a steam sterilization process. A comparison showed that a permanently installed device which – independent from the sterilizer – measures the temperature, the steam composition in the chamber and the time for every steam sterilization process, offers the most advantages. The selected method has been implemented and tested on 51 steam sterilizers. The selected method makes steam sterilization safer, more sustainable, and more cost effective. It can be implemented by all interested end-users. [ABSTRACT FROM AUTHOR]

Background: Prions are renowned for their distinct resistance to chemical or physical inactivation, including steam sterilization. Impaired efficacy of inactivation poses a risk to patients for iatrogenic transmission of Creutzfeldt-Jakob disease (CJD) via contaminated surgical instruments.Aims: Most established prion inactivation methods were validated against scrapie agents, although those were found to be generally less thermostable than human prions. Thus, knowledge gaps regarding steam-sterilization kinetics of CJD prions should be filled and current guidelines reviewed accordingly.Methods: Prion inactivation through widely recommended steam sterilization at 134°C was assessed for several holding times by analysing the residual prion seeding activity using protein misfolding cyclic amplification (PMCA).Findings: Scrapie 263K was found to be the least thermoresistant prion strain showing no seeding activity after 1.5 min at 134°C, while variant CJD was the most stable one demonstrating some seeding activity even after 18 min of steam sterilization. Sporadic CJD subtype VV2 exhibited residual seeding activity after 3 min, but no detectable activity after 5 min at 134°C.Conclusion: Validated steam sterilization for 5 min at 134°C as previously recommended for the routine reprocessing of surgical instruments in contact with high-risk tissues is able to substantially reduce the seeding activity of CJD agents, provided that no fixating chemical disinfection has been performed prior to sterilization and that thorough cleaning has reduced the protein load on the surface to less than 100 μg per instrument. [ABSTRACT FROM AUTHOR]

Food process engineering represents a rapidly evolving discipline traditionally focussing on thermal treatments including objectives such as preservation and stabilization. Innovative and gentle preservation techniques such as high‐pressure processing (HPP) may potentially improve or replace conventional methods by enhancing nutritional and health aspects, flavor and taste, sustainability, and more consumer‐targeted, minimally processed food items. As information about the impact of HPP (600 MPa, 5–40 min) on lipophilic food ingredients (e.g., carotenoids, vitamin E) in kale is limited, a comparison to heat sterilization (20 min, 121°C) may result in new insights related to lipophilic, antioxidant capacity (L‐AOC), extractability and storage stability (8 weeks, 5°C). HPP of chopped kale resulted in significantly increased (p < 0.05) total carotenoid and chlorophyll contents in contrast to declined concentrations of vitamin E. Significantly decreased extractabilities were observed for total carotenoids and chlorophylls in heat sterilized kale, showing no significant change (p > 0.05) in vitamin E content. Moreover, 2 months of storage of HP‐treated kale resulted in a major loss of vitamin E and total carotenoid contents compared to thermally treated samples. Elevated α‐tocopherol equivalent antioxidant capacities (αTEAC) and lipophilic oxygen radical antioxidant capacities (L‐ORAC) correlated with an increased pressure holding time. [ABSTRACT FROM AUTHOR]

The concept of the presented research was to assess the applicability of natural colorants in dyeing biocomposites filled with natural fillers. As dyes, ground coffee, turmeric, couscous and ground paprika were used. Additionally, wood flour and walnut shell flour were added to improve strength parameters. The fillers were not dyed prior to processing, but the pigments were processed with the matrix and the filler. The optical observation and the influence of steam sterilization on mechanical properties were carried out, taking into consideration esthetics and performance of the product. The results showed that natural colorants can be successfully used to dye composites. Low-density biocomposites with increased rigidity were obtained. Composites were characterized by lower tensile strength than neat green polyethylene which was approximately 18 MPa. The high result for tensile modulus was obtained for composition with coffee – it increased to 2045 MPa. [ABSTRACT FROM AUTHOR]

The aim of this study was to explore the possibility to re-use disposable masks in order to prevent excessive waste generation during the pandemic period. The COVID-19 pandemic has caused rapidly increasing waste production resulting from the necessity of common usage of disposable personal protective equipment. This research covers the evaluation of the structure of surgical masks subjected to a threefold steam, gas or plasma sterilization process in order to verify the possibility of their re-use. The results of the study showed that gas sterilization even after three cycles did not cause significant changes in mask structure or air permeability. Hydrogen peroxide plasma sterilization caused significant changes in the structure of layer A after the third cycle of sterilization; nonetheless, it did not influence the air permeability of the mask. A significant reduction in the cover ratio of layers composing surgical masks causes an increase of air permeability in the case of steam sterilization, leading to a reduction of the mechanical ability to prevent the penetration of microorganisms. The reduction in cover ratio limits the filtration efficiency. Surgical masks subjected to threefold gas sterilization can be recommended for re-use. This allows one to use the mask thrice, ensuring safety for users and limiting the mask-waste production to one-third of the volume compared with when the mask is used once. The volume of mask-waste can be reduced with the application of the sterilization process for used masks during the pandemic period. Currently, it is not possible to sterilize all one-use masks, but implementation of this method in hospitals and medical centers is a step in the pro-environmental direction. [ABSTRACT FROM AUTHOR]

Egg white is considered as one of the best food proteins and hydrolysis can be applied to increase its nutritional value and reveal antioxidant activity. Low molecular weight of egg white hydrolysate was also beneficial for the chronic kidney disease (CKD) sufferers. However, hydrolysis of egg white protein typically results in relatively low yield. Thus, pre-treatment methods to increase yield of hydrolysate should be sought. The objective of this research was to compare the use of ultrasound, microwave, and steam sterilization (121°C) prior to hydrolysis of egg white by 10% (w/w protein) Alcalase on degree of hydrolysis (DH) and antioxidant activity of the hydrolysate. Ultrasound at intensity of 41.5 W/cm² applied to boiled egg white was found to produce hydrolysate with the highest DH of 45.4%. Antioxidant activities of egg white hydrolysate were examined by 2, 2'-azinobis- (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activity, ferric reducing antioxidant power (FRAP), and ferrous ion chelating capacity (FICC) assays. Raw egg white subjected to sterilization for 5 min resulted in the hydrolysate exhibiting the strongest ABTS radical scavenging activity with approximately 64% inhibition. In addition, 30-min steam sterilization the most powerful pre-treatment yielding peptides with FRAP of 22 µM Trolox equivalence. Boiled egg white subjected to ultrasound at intensity of 41.5 W/cm² obtained hydrolysate with FICC of 1800 µM EDTA equivalence. Since there were several measured parameters, and pre-treatment methods affected these parameters differently. [ABSTRACT FROM AUTHOR]

• Thermal and ɣ-irradiation treatments were effective against microorganisms in oregano. • Thermal treatment resulted in increased levels of pyrrolizidine alkaloids. • First report on the degradation of pyrrolizidine alkaloids by ozone treatment. • Thermal, UV and ozone treatments caused significant changes in volatile compounds. Effects of steam sterilization, gamma-irradiation, UV-irradiation and ozonation on microbial inactivation, pyrrolizidine alkaloid degradation and volatile compound profile in oregano were investigated. Steam sterilization and gamma-irradiation were the most effective treatments in inactivating microorganisms. These treatments resulted in 0.87–2.15 log reductions in total aerobic mesophilic bacteria counts and reduced yeast-mold and Enterobacteriaceae counts below the detectable level. Steam sterilization caused increased levels of pyrrolizidine alkaloids (PAs) and decreased levels of their N -oxide forms (PANOs) demonstrating a simultaneous conversion of PANOs into the corresponding PAs. Ozone treatment caused significant decreases in the levels of individual and total PAs/PANOs. After ozone treatment, decreases of 54.4, 53.9, 61.6 and 61.4% were observed in the levels of europine- N -oxide, europine, lasiocarpine- N -oxide and lasiocarpine, respectively. Steam sterilization, UV-irradiation and ozone treatments significantly altered the composition of the volatile compounds of oregano as evidenced by decreased levels of major components and the formation of some new compounds. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the influence of sterilization methods on conventional and bulk‐fill resin composites' (BFRCs) surface properties in an attempt to preview bias in laboratory bacterial adhesion tests. Two regular viscosity conventional resin composites [Filtek Z350 XT™ (Z350) and IPS Empress Direct™ (ED)] and two regular viscosity BFRCs [Filtek Bulk Fill™ (FILT) and Tetric N‐Ceram Bulk Fill IVA™ (TBF)] were used. The materials were characterized by Scanning Electron Microscopy (SEM), surface roughness (SR), and wettability (W) after sterilization with hydrogen peroxide gas plasma (HPGP) and steam sterilization (SS). Nonsterilized samples served as a control group (n = 5). Statistical analysis was performed using two‐way analysis of variance (ANOVA) and Tukey post hoc test (p < 0.05). For SR, there were no statistically significant differences among the groups (p >.05). SS method decreased the contact angle for FILT and Z350 (p <.01). The SS promoted more exposition of filler particles, while the HPGP method did not alter the tested materials' morphology. Therefore, sterilization methods affected the resin composites tested selectively. HPGP seems to be the most recommended method to sterilize the tested resin composites before laboratory bacterial adhesion tests. [ABSTRACT FROM AUTHOR]

Background: The sterilization cycle is one of the most important parts of infection control. Accordingly, the present study was conducted to assess the quality of steam sterilization and compare the knowledge, attitude, and practice of clinical directors in dental clinics, based on the experimental work in one of the most important and famous dental departments and clinics in the Northeast of Iran. Methods: This cross-sectional study was conducted from June to September 2017 in 84 dental outpatient clinics of Mashhad, Iran. The status of sterilization quality was evaluated using biological (BI) and chemical indicators (CI) and the results of a questionnaire. The participants include the technical manager and operator of the Autoclave, who were included in this study according to the inclusion criteria by stratified cluster sampling. Information on their knowledge, practices, and attitudes were evaluated. Also, BI and CI were used to evaluate the autoclave accuracy. The data were analyzed by Mann-Whitney U, Wilcoxon signed-rank, and Fisher’s exact tests using SPSS (Version 19, SPSS Inc., Chicago, IL, USA). Results: In this study, the results of 69 (82.1%) biological test were negative. Based on the questionnaire results, 64 (76%) clinics used CI, and only 4 (5%) clinics used CI and BI to evaluate the sterilization quality. The mean scores of attitude (P = 0.001), knowledge (P = 0.001), and practice (P < 0.001) of the technical manager in dental clinics were significantly higher than those in outpatient clinics. Also, there was a significant association between the knowledge and practice of the clinics’ technical managers (P < 0.001). Conclusion: According to the results, 93.3% of the clinics that had a positive biological test were outpatient clinics. Also, it was revealed that insufficient knowledge, attitude, and practice lead to imperfect sterilization. Also, the mean score of dentists was higher than that of general practitioners, therefore, in addition to suggesting training programs for managers, it is recommended that employ a dental practitioner as the technical manager of outpatient clinics. In order to control infection in clinics, it is recommended to monitor the sterilization process in clinics according to the instructions of the monitoring units.

Abstract Background Reusable medical devices in healthcare facilities are decontaminated and reprocessed following standard practices before each clinical procedure. Reprocessing of critical medical devices (those used for invasive clinical procedures) comprises several processes including sterilization, which provides the highest level of decontamination. Steam sterilization is the most used sterilization procedure across the globe. Noncompliance with standards addressing reprocessing of medical devices may lead to inadequate sterilization and thus increase the risk of person-to-person or environmental transmission of pathogens in healthcare facilities. We conducted nationwide multicenter clustered audits to understand the compliance of primary- and secondary-care public hospitals in Nepal with the standard practices for medical device reprocessing, including steam sterilization. Methods We developed an audit tool to assess compliance of hospitals with the standard practices for medical device reprocessing including steam sterilization. Altogether, 189 medical device reprocessing cycles which included steam sterilization were assessed in 13 primary and secondary care public hospitals in Nepal using the audit tool. Percentage compliance was calculated for each standard practice. Mean percentage compliances were obtained for overall primary and secondary care hospitals and for each hospital type, specific hospital and process involved. Results For all primary and secondary care hospitals in Nepal, the mean percentage compliance with the standard practices for medical device reprocessing including steam sterilization was 25.9% (95% CI 21.0–30.8%). The lower the level of care provided by the hospitals, the lower was the mean percentage compliance, and the difference in the means across the hospital types was statistically significant (p

This study conducted sterilization testing under different conditions using different strains for sterilization and crushing, the intermediate healthcare waste treatment phase, and proposed strategies for diversifying corresponding facilities in addition to promoting their installation. Five indicator microorganisms were selected to test the sterilization efficiency of steam, microwave, and chemical methods. Steam sterilization testing was conducted in accordance with legal and technological standards, microwave testing was carried out according to the legal standard, and chemical sterilization employed three typical compounds. Steam and microwave sterilization achieved 99.9999 % inactivation rates for all five strains under both conditions used; whereas under the chemical sterilization analyses, sodium hypochlorite (1000 ppm) failed to meet the inactivation requirement of the fungal strain Candida albicans , requiring further investigation. Based on these findings, this study presents strategies for diversifying sterilization·crushing facilities and promoting their installation., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 Published by Elsevier Ltd.)

Different printing technologies can be used for prosthetically oriented implant placement, however the influence of different printing orientations and steam sterilization remains unclear. In particular, no data is available for the novel technology Continuous Liquid Interface Production. The objective was to evaluate the dimensional accuracy of surgical guides manufactured with different printing techniques in vertical and horizontal printing orientation before and after steam sterilization. A total of 80 surgical guides were manufactured by means of continuous liquid interface production (CLIP; material: Keyguide, Keyprint), digital light processing (DLP; material: Luxaprint Ortho, DMG), stereolithography (SLA; Surgical guide, Formlabs), and fused filament fabrication (FFF; material: Clear Base Support, Arfona) in vertical and horizontal printing orientation (n = 10 per subgroup). Spheres were included in the design to determine the coordinates of 17 reference points. Each specimen was digitized with a laboratory scanner after additive manufacturing (AM) and after steam sterilization (134 °C). To determine the accuracy, root mean square values (RMS) were calculated and coordinates of the reference points were recorded. Based on the measured coordinates, deviations of the reference points and relevant distances were calculated. Paired t-tests and one-way ANOVA were applied for statistical analysis (significance p < 0.05). After AM, all printing technologies showed comparable high accuracy, with an increased deviation in z-axis when printed horizontally. After sterilization, FFF printed surgical guides showed distinct warpage. The other subgroups showed no significant differences regarding the RMS of the corpus after steam sterilization (p > 0.05). Regarding reference points and distances, CLIP showed larger deviations compared to SLA in both printing orientations after steam sterilization, while DLP manufactured guides were the most dimensionally stable. In conclusion, the different printing technologies and orientations had little effect on the manufacturing accuracy of the surgical guides before sterilization. However, after sterilization, FFF surgical guides exhibited significant deformation making their clinical use impossible. CLIP showed larger deformations due to steam sterilization than the other photopolymerizing techniques, however, discrepancies may be considered within the range of clinical acceptance. The influence on the implant position remains to be evaluated. [ABSTRACT FROM AUTHOR]

Fluorinated ethylene propylene (FEP) vessels are of significant interest for therapeutic cell biomanufacturing applications due to their chemical inertness, hydrophobic surface, and high oxygen permeability. However, these properties also limit the adhesion and survival of anchorage-dependent cells. Here, we develop novel plasma polymer coatings to modify FEP surfaces, enhancing the adhesion and expansion of human mesenchymal stromal cells (hMSCs). Similar to commercially available tissue culture polystyrene vessels, oxygen-rich or nitrogen-rich surface chemistries can be achieved using this approach. While steam sterilization increased the roughness of the coatings and altered the surface chemistry, the overall wettability and oxygen or nitrogen-rich nature of the coatings were maintained. In the absence of proteins during initial cell attachment, cells adhered to surfaces even in the presence of chelators, whereas adhesion was abrogated with chelator in a protein-containing medium, suggesting that integrin-mediated adhesion predominates over physicochemical tethering in normal protein-containing cell seeding conditions. Albumin adsorption was more elevated on nitrogen-rich coatings compared to the oxygen-rich coatings, which was correlated with a higher extent of hMSC expansion after 3 days. Both the oxygen and nitrogen-rich coatings significantly improved hMSC adhesion and expansion compared to untreated FEP. FEP surfaces with nitrogen-rich coatings were practically equivalent to commercially available standard tissue culture-treated polystyrene surfaces in terms of hMSC yields. Plasma polymer coatings show significant promise in expanding the potential usage of FEP-based culture vessels for cell therapy applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Membrane processes can be integrated with fermentation for the selective separation of the products from the fermentation broth. Sterilization with saturated steam under pressure is the most widely used method; however, data concerning heat sterilization applicability to polymeric ultrafiltration (UF) membranes are scarcely available. In this study, the effect of the sterilization process on the filtration performance of a commercial polyvinylidene difluoride (PVDF) hollow fiber UF membrane was evaluated. Membrane modules were constructed and sterilized several times in an autoclave. Pure water flux tests were performed, to assess the effect of heat sterilization on the membrane’s pure water permeance. Dextran rejection tests were performed for the characterization of membrane typical pore size and its fouling propensity. Filtration performance was also assessed by conducting filtration tests with real fermentation broth. After repeated sterilization cycles, pure water permeance remained quite constant, varying between approx. 830 and 990 L·m−2·h−1·bar−1, while the molecular weight cut-off (MWCO) was estimated to be in the range of 31.5–98.0 kDa. Regarding fouling behavior, the trans-membrane pressure increase rate was stable and quite low (between 0.5 and 7.0 mbar/min). The results suggest that commercial PVDF UF membranes are a viable alternative to high-cost ceramic UF membranes for fermentation processes that require heat sterilization.

Background: Cerebral deposition of abnormally misfolded and aggregated alpha-synuclein (αSyn) is a neuropathological hallmark of Parkinson's disease (PD). Pathologically aggregated αSyn species of PD (αSynPD) can act, in a 'prion-like' manner, as proteinaceous nuclei ('seeds') which are capable of self-templated propagation. This has raised concerns that αSynPD seeds transmitted iatrogenically between humans may stimulate αSyn pathologies or clinically harmful effects in the recipients. Effective decontamination when reprocessing medical devices could significantly counteract such risks. Steam sterilization at 134°C is recommended as an essential pathogen inactivation step in many reprocessing guidelines for medical devices, and also shows effectiveness against prions, the self-propagating biological agents long thought to exhibit the highest resistance to steam sterilization.Methods: This study examined the reduction in αSynPD seeding activity in brain tissue homogenates from patients with PD after steam sterilization at 134°C using a specifically adapted real-time quaking induced conversion assay.Findings: Titres of approximately 1010 50% seeding doses per gram were detected in non-steam-sterilized caudate nucleus tissue of patients with PD by endpoint titration. Five minutes of steam sterilization reduced this titre by only 2.25 ± 0.15 decadic-logarithmic units, with an extension of the sterilization time to 90 min not causing additional inactivation. These findings reveal that αSynPD species are disease-associated biological agents with seeding activity that has higher resistance to steam sterilization than prions.Conclusion: The remarkable heat resistance of αSynPD seeds calls for thoroughly validated cleaning and disinfection methods that reliably remove or inactivate possible contaminations of seeding-active αSyn aggregates when reprocessing medical devices. [ABSTRACT FROM AUTHOR]

Introduction: 3D printing, which is becoming ever more widespread in orthopedic surgery, requires specific materials. Polylactic acid (PLA) is the most widely used in general-purpose 3D printing, but its thermosensitivity can be incompatible with sterilization. Even so, it is easy to use, inexpensive, non-toxic and biodegradable. Controversy surrounds its use. 3D printing of directly sterilizable PLA parts according to surgeons' needs would be highly advantageous, but doubts remain. We therefore performed an in vitro study to determine which PLAs resist steam sterilization regarding deformation., Hypothesis: The study hypothesis was that, depending on make and shape, 3D-printed PLA parts can retain their properties after steam sterilization., Material and Methods: We selected 4 makes of PLA and used each to print 4 simple cubes and 4 complex shapes corresponding to cuboid bones. They were subjected to steam sterilization under normal French hospital conditions. The size of the cubes was measured before and after sterilization, using a digital caliper., Results: Cuboid parts in HT-PLA and PLA-WANAO showed mean deformation of -0.02mm and -0.4mm, respectively after sterilization, the differences being non-significant (p=0.679 and p=0.241, respectively). Cuboid parts in PLA-SUNLU and PLA-G3D showed significant mean deformation: respectively, -1.37mm (p=0.026) and -35.03mm (p>0.001). Cubes in all types of PLA showed significant mean deformation: HT-PLA, -0.61mm (p=0.004); PLA-SUNLU, -2.70mm (p=0.002); PLA-G3D, -28.64mm (p>0.001); and PLA-WANAO, -1.33mm (p=0.010)., Discussion: The study confirmed recent findings that steam sterilization is feasible with certain PLA-printed parts, with deformations less than 1mm, and that choice of PLA is crucial for success. Computer-designed objects (here, cubes) did not resist sterilization without significant deformation. Analysis of resistance to various stresses was not performed, and therefore it cannot be claimed that the process could be used other than for printing anatomic parts. Use of 3D printing in French hospitals is probably a real source of innovation and improvement in care quality; however, a legal framework needs establishing for the use of 3D-printed parts, to ensure patient safety and promote research in this field., Level of Evidence: III; prospective in vitro study., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Heat sterilization of glucose solutions can lead to the formation of various glucose degradation products (GDPs) due to oxidation, hydrolysis, and dehydration. GDPs can have toxic effects after parenteral administration due to their high reactivity. In this study, the application of the F0 concept to modify specific time/temperature models during heat sterilization and their influence on the formation of GDPs in parenteral glucose solutions was investigated using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Glucose solutions (10%, w/v) were autoclaved at 111 °C, 116 °C, and 121 °C for different durations. The GDPs glyoxal, methylglyoxal, glucosone, 3-deoxyglucosone/3-deoxygalactosone, 3,4-dideoxyglucosone-3-ene, and 5-hydroxymethylfurfural were quantified after derivatization with o-phenylenediamine by an optimized LC-MS/MS method. For all GDPs, the limit of detection was

One of the major problems of the surgical instruments in steam sterilization is having instruments in a locked position. This is where the tips are not separated from each other and steam cannot contact all surfaces of the instruments. Although the various types of surgical stringers are used to hold the surgical instruments in an open position, they differ in locking designs and are inconvenient to lock and release stringers in the sterile containers. To overcome these limitations, this study aimed to design and develop an innovative Rotating Stringer, a new locking system, and evaluate its efficacy. The study design follows the steam sterilization guideline that the tips must be separated by using a rotating mechanism to design the new locking system. For the efficacy evaluation, purposive sampling was with 45 Thai perioperative nurses in Ramathibodi Hospital, Bangkok, Thailand who examined the Rotating Stringer in sterile instrument containers for five surgeries. At the end of the fifth use, they were asked to complete the Rotating Stringer Problem Record and the Rotating Stringer Effectiveness Scale which were used to test the structural design and function of the Rotating Stringer. The data collected from February to May 2019. Descriptive statistics were then used to analyze the data. Results indicated that there were no problems reported in the use of the Rotating Stringer in 135 different surgeries. According to all participants' opinions, the overall effectiveness of the instrument was highly rated on function, usability, and safety. The Rotating Stringer regulates the instrument tips in separation following sterilization guidelines for patient safety. It is convenient to use in a sterile container and protects wrist injury. The Rotating Stringer has now been patented for use in practice. [ABSTRACT FROM AUTHOR]

The focus of this study is to investigate different process challenge devices (PCDs) for narrow lumens used within a small steam steriliser. Prior studies were primarily focused on the application of PCDs within large steam sterilisers. The point of a PCD or medical product simulator (MPS) is to find out whether a product, in this case a steriliser, works as required or not. However, if this PCD or MPS fails at doing its job, no safe conclusions can be drawn. Ultimately, we risk patients' health on a global level. PCDs are necessary as it is impossible to test on site for the sterility of a medical product intended for immediate reuse without contaminating selfsame. The goal of this study is to identify the weak points within the PCDs which are currently available on the European market. The key questions that pose themselves are: 1) Is the informative value of a PCD for narrow lumens still valid and valuable? 2) Is there a reasonable risk of false positive indications for current devices available on the market? The advantage of PCDs is that they provide information about the performance of the steriliser, independently of the sterilisers control system. A total of four different PCDs for narrow lumens and their corresponding chemical indicators (CIs) were tested within a state-of-the-art small steam steriliser. The PCDs were investigated both in their original state as well as after being subjected to manipulations such as an extension of the lumen or plugging of the single-opening. This study revealed significant flaws in existing PCDs for narrow lumens that might lead to false positive indications of the de-aeration behaviour within a sterilisation chamber. [ABSTRACT FROM AUTHOR]

Background: Steam sterilisation conditions are not unambiguously quantified in the literature and standards. In practical situations, it would be helpful if a set of criteria to assess the actual surface steam sterilisation conditions would be available. Aim: To define numerically quantified steam sterilisation conditions based on the literature and standards. This means that the combinations of temperature, water vapour fraction, and time are specified in terms of numerical values, including their possible inaccuracies. Methodology: A review of the literature and standards is performed. Results from this review, combined with basic physical calculations, are used to determine numerically quantified steam sterilisation conditions. Results: Steam sterilisation conditions can be specified in terms of quantified physical parameters. For example, to comply with European standard EN 285:2015 these parameters are a holding time of 3 minutes or more, at measured temperatures between 134.5 and 136.5 °C, and a minimum water vapour fraction depending on load temperature and pressure. Conclusion: The standard EN 285:2015 allows parameter regions where sterilisation conditions are not met, even in the absence of non-condensable gases. If the inaccuracies in the temperature measurements are properly taken into account and the water vapour fraction is measured, sterilization conditions can be guaranteed. [ABSTRACT FROM AUTHOR]

The present study investigated the formation and fixation of silicate deposits during steam sterilization. First, transfer of silicic acid from the feed water into the sterilization steam onto the sterile supplies was analysed in theory by comparing the process parameters of all substeps of a typical steam sterilization process with a solubility diagram for silicic acid in water and in steam. Next, in furnace tests silicate deposits were selectively deposited onto test specimen made of non-rusting steel and with instrument-like surfaces. Deposit formation was visualized through digital photography and differential interference contrast (DIC) microscopy. In addition, topography images were obtained with atomic force microscopy (AFM) and the chemical composition of surfaces was determined with X-ray fluorescence analysis. Theoretical considerations supported the notion of a pressure- and temperature-dependent solubility of silicic acid in steam which, based on the steam sterilization process parameters, led to extensive entrainment of silicic acid into, and little removal from, the autoclave. Furthermore, experimental findings demonstrated that entrainment of silicic acid compounds gave rise to high, interlocking silicate margins on the test specimen, with a thin flat configuration within the dried drops. By combining the theoretical considerations and experimental findings, it was possible for the first time to add to the literature repository an explanation for the transfer of silicic acid to the sterile supplies and for the mechanism underling the transformation into visible deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • A zwitterionic copolymer containing 4-vinylpyridine propylsulfobetaine is presented. • The copolymer can efficiently trap and retain water under low humidity levels. • Bi-continuous zwitterionic membranes are formed efficiently resisting biofouling. • Stability of the antifouling properties after sterilization is demonstrated. Most antifouling membranes lose their bioinert properties after steam sterilization because common antifouling materials are sensitive to hydrolysis. Here, we synthesized a random zwitterionic copolymer containing poly(styrene), poly(ethylene glycol) methyl ether methacrylate and zwitterionic poly(4-vinylpyridine propylsulfobetaine). The resulting copolymer, poly(styrene- r -EGMA- r -4VPPS), was blended with poly(vinylidene difluoride) to form bi-continuous and bioinert PVDF membranes by vapor-induced phase inversion. The copolymer drastically enhanced the hydrophilicity of the membranes, as water could wet the porous substrate entirely (WCA 0 for the zwitterionic membrane vs. about 144° for the virgin membrane). When exposed to Escherichia coli , Stenotrophomonas maltophilia , whole blood or HT1080 cells, fouling on the non-sterilized modified membranes was reduced by 95 %, 98 %, 99 % and 99 %, respectively. After sterilization, the antifouling properties were maintained. Results of cyclic water/ Escherichia coli filtrations indicated that the non-sterilized modified membrane showed a flux recovery ratio of 57 %, against 21 % for a commercial membrane. Importantly, these performances were maintained after sterilization. The copolymer is not only efficient at mitigating biofouling in various situations, but also shows stable properties after autoclaving, which is paramount for membranes to be applied in the biomedical field. [ABSTRACT FROM AUTHOR]

Medical devices are sterilized before being used for invasive clinical procedures such as surgery, to prevent pathogen transfer. Failure to sterilize medical devices properly presents a risk of healthcare-associated infections. Studies and reports have indicated that inadequately sterilized medical devices are one of the causes of a higher rate of healthcare-associated infections in developing countries. Steam sterilization (autoclaving) is the most widely used method for sterilization and is considered the most robust and cost-effective method for sterilization of medical devices. The effectiveness of steam sterilization can be measured using biological indicators. A literature search was undertaken to understand the effectiveness of autoclaving in sterilizing reusable medical devices in healthcare facilities across the globe. Studies using biological indicators for measuring the effectiveness of autoclaving were obtained. Failures of steam sterilization practices were identified and discussed as a means of identifying factors that might be associated with the ineffectiveness of steam sterilization practices between different countries. The number of studies measuring the effectiveness of steam sterilization is small, and few evaluate the effectiveness of steam sterilization specifically in developing countries. There are fewer studies on higher level healthcare facilities than dental facilities. More evidence about the effectiveness of autoclaving in healthcare facilities is needed to draw firm conclusions, but the data suggest that there are inadequacies in autoclave procedures and operator education. [ABSTRACT FROM AUTHOR]

Wet loads after steam sterilization of medical devices in healthcare facilities are unacceptable. However, little is known about their frequency in daily practice. An online survey was distributed via four national sterilization associations, in Australia (Sterilising Research Advisory Council of Australia (Vic), Inc. (VIC SRACA)), Belgium (Vereniging sterilisatie in het ziekenhuis (VSZ)), Italy (Associazione Italiana Operatori Sanitari addetti alla Sterilizzazione - Società Scientifica (AIOS)), and The Netherlands (Vereniging van Deskundigen Steriele Medische Hulpmiddelen (VDSMH)). Seventy-eight percent of 125 hospital sterilization facilities recognized wet loads, occurring at frequencies ranging from monthly to every load. Usually, wet loads were identified by the presence of water droplets; these loads were repacked and resterilized. Given the pervasiveness of wet loads, and their impact on reprocessing times and costs, strategies to reduce their frequency are needed. [ABSTRACT FROM AUTHOR]

• This research intended to evaluate the effect that multiple cycles of sterilization may have, if any, on the mechanical integrity of cannulated screws, compared to individually packages screws. • No Significant difference in flexural strength was identified between immediately out of the package and repeatedly sterilized screws. The process of repeated handling and steam sterilization of bone screws and allows debris to deposit on the surface and inside cannulated screws. Individually packaged screws could alleviate these potential problems. This research intended to evaluate the effect that multiple cycles of sterilization may have, if any, on the mechanical integrity of cannulated screws. The results indicate that the mechanical integrity of the screws tested was not compromised. [ABSTRACT FROM AUTHOR]

Sterility of bioreactors in biotherapeutic processing remains a significant challenge. Virus removal size-exclusion filtration is a robust and highly efficient approach to remove viruses. This article investigates the virus removal capacity of nanocellulose-based filter for upstream bioprocessing of chemically defined Chinese hamster ovary (CHO) cells medium containing Pluronic F-68 (PowerCHO™, Lonza) and supplemented with insulin-transferrin-selenium (ITS) at varying process parameters. Virus retention was assessed by spiking ITS-supplemented PowerCHO™ medium with small-size ΦX174 phage (28 nm) as a surrogate for mammalian parvoviruses. The nanocellulose-based size exclusion filter showed high virus retention capacity (over 4 log 10) and high flow rates (around 180 L m−2 h−1). The filter had no impact on ITS supplements during filtration. It was further shown that the filtered PowerCHO™ medium supported cell culture growth with no impact on cell viability, morphology, and confluence. The results of this work show new opportunities in developing cost-efficient virus removal filters for upstream bioprocessing. [ABSTRACT FROM AUTHOR]

This paper presents a plastic-encapsulated wireless sensor module (WSM), using commercial off-the-shelf components, which has been demonstrated to be reliable for 180 cycles in a medical steam sterilizer with an environment involving high-rate temperature, pressure, and humidity cycles up to 134 °C, 3 bar, 100% RH. The WSM continuously transmits temperature and pressure data from the sterilizer, allowing the quality of sterilization to be verified. Twelve WSMs were assembled and encapsulated with substrate material and encapsulant type as experimental variables. These samples were then stress tested over multiple sterilization cycles, with continuous wireless data collection, until failure. Scanning acoustic microscope analysis was carried out before and after the reliability testing in the steam sterilizer. The results demonstrate that, with appropriate choice of materials, the WSM can survive for 180 full-steam sterilization cycles without any electrical failure of the components or any deterioration in the package structure except for delamination between the substrate and the encapsulant that did not cause electrical failure. The overall results demonstrate the reliability of a plastic-encapsulated module in an exceptionally harsh use environment, the ability to steam sterilize a plastic-encapsulated module for medical applications, and the potential for using a plastic-encapsulated WSM for continuous, high-resolution sterilizer parameter monitoring as a replacement for the currently used color-change chemical and biological indicators. This is believed to be the first plastic-encapsulated WSM for monitoring of steam sterilizer parameters and the first plastic-encapsulated module of any sort, which is capable of surviving multiple steam sterilization cycles. [ABSTRACT FROM AUTHOR]

The aim of this work is a proof of concept, that medical Internet of Things (IoT) sterilization surveillance sensors can be powered by using the heat during a steam sterilization procedure. Hereby, the focus was on the use of thermo-electrical generators (TEG) to generate enough power for an ultra-low-power sensor application. Power generation requirement of the sensor was 1.6 mW over the single sterilization cycle. The thermal gradient across the TEG has been achieved using a highly efficient aerogel-foam-based thermal insulation, shielding a heat storage unit (HSU), connected to one side of the TEG. The evaluation of the developed system was carried out with thermal and electrical simulations based on the parameters extracted from the TEG manufacturer’s datasheet. The developed model has been validated with a real prototype using the thermal step response method. It was important for the authors to focus on rapid-prototyping and using off-the-shelf devices and materials. Based on comparison with the physical prototype, the SPICE model was adjusted. With a thermal gradient of 12 °C, the simulated model generated over 2 mW of power. The results show that a significant power generation with this system is possible and usable for sensor applications in medial IoT.

In our efforts toward producing environmentally responsible but highly stable bioelectrodes with high electroactivities, we report here a simple, inexpensive, autoclavable high sensitivity biosensor based on enzyme-polymer nanogels. Met-hemoglobin (Hb) is stabilized by wrapping it in high molecular weight poly(acrylic acid) (PAA, MW 450k), and the resulting nanogels abbreviated as Hb-PAA-450k, withstood exposure to high temperatures for extended periods under steam sterilization conditions (122 °C, 10 min, 17–20 psi) without loss of Hb structure or its peroxidase-like activities. The bioelectrodes prepared by coating Hb-PAA-450k nanogels on glassy carbon showed well-defined quasi-reversible redox peaks at −0.279 and −0.334 V in cyclic voltammetry (CV) and retained >95% electroactivity after storing for 14 days at room temperature. Similarly, the bioelectrode showed ~90% retention in electrochemical properties after autoclaving under steam sterilization conditions. The ultra stable bioelectrode was used to detect hydrogen peroxide and demonstrated an excellent detection limit of 0.5 μM, the best among the Hb-based electrochemical biosensors. This is the first electrochemical demonstration of steam-sterilizable, storable, modular bioelectrode that undergoes reversible-thermal denaturation and retains electroactivity for protein based electrochemical applications.

In this study we report antibacterial modification of Kirschner wires (K-wires) with polyluteolin (PL) toward methicillin-resistant Staphylococcus aureus (MRSA). K-wires were modified by immersing them in the luteolin-containing aqueous solution for 24 h. Characterizations using scanning electron microscopy and electrochemical methods confirmed the presence of the PL coatings on the K-wires. The PL-coated K-wires were further found to show antibacterial activity toward MRSA and remained unimpaired antibacterial activity even after the steam sterilization treatment.

Quality of applied guide wires conditions the course of treatment and its success to a great extent. In order to simulate conditions that can be found in blood vascular system samples were exposed to artificial blood plasma (T = 37 } 1 oC) for the time of 8 h. In order to obtain information regarding physical and chemical properties of modified surface of wire made of X10CrNi 18-8 steel, electrochemical impedance spectroscopy (EIS) test and tests of chemical composition of the surface layer X-ray photoelectron spectroscopy (XPS) were made. On the ground of performed EIS and XPS tests, favourable impact of steam sterilisation process on corrosion resistance of X10CrNi 18-8 steel was observed only for the case when chemical passivation was applied prior to sterilisation.

The aim of this study was to investigate if sterilization methods would promote changes in the selected adhesion‐related surface properties of glass ionomer cements (GICs). Riva self‐cure (RSC) and Riva light‐cure (RLC) GICs were tested. Thirty samples were prepared according to the type of material (RSC and RLC) and sterilization method: hydrogen peroxide gas plasma (HPGP), steam sterilization (SS), and no sterilization (n = 5 per group). A Teflon matrix (5 × 2 mm) was filled with one of the GICs to produce the samples. For the groups with the RLC material, the samples were light cured using a light curing unit for 20 s. After 24 hr, finishing and polishing were performed in all samples and then they were sterilized. Surface roughness, wettability, and micromorphology were accessed using a profilometer, a goniometer, and a scanning electron microscopy, respectively. Data were statistically analyzed through a two‐way ANOVA and Tukey post‐hoc test (p < .05). Both sterilization methods promoted similar roughness values to the nonsterilized samples (p > .05). HPGP decreased contact angle for RSC (p < .01), and SS increased contact angle for RLC (p < .01). Samples subjected to HPGP presented similar surface micromorphology to nonsterilized ones, regardless of the material. SS promoted exposition of smaller filler particles in both materials. Although sterilization methods did not alter surface roughness and wettability, the sterilization methods selectively altered the micromorphology of the materials tested. Research highlights: This study's main finding suggests that each sterilization method altered the surface of glass ionomers in different ways. Thus, the choice of sterilization methods prior to bacterial adhesion can lead to a bias in antimicrobial studies. [ABSTRACT FROM AUTHOR]

Pleurotus ostreatus was cultivated on composted 'wawa' (Triplochiton scleroxylon) sawdust subjected to physical pretreatment techniques of moist heat sterilization and gamma irradiation to assess their comparative mycelial growth performance. Substrates were moist heat sterilized at either 95-100°C for 2.5 hours or gamma irradiated with a Cobalt 60 source at 0 kGy, 5 kGy, 10 kGy, 15 kGy, 20 kGy, 24 kGy and 32 kGy at a dose rate of 1.7 kGy/hour using the ethanol chlorobenzene (ECB) dosimetry. Sorghum grains for spawns were also irradiated at same doses (0 kGy, 5 kGy, 10 kGy, 15 kGy, 20 kGy, 24 kGy and 32 kGy) and steamed similarly and their interactive mycelia growth effects on pretreated sawdust measured. Final linear growth, colonizing time, rate of growth, primordial emergence time, density and percentage contamination were monitored for the four weeks at 28-32°C. The fastest time taken for full colonization was 22 days by irradiated (I+I) samples of the 15 kGy set up while the fastest rate of growth of 28.3 mm/day was recorded by irradiated sorghum and steamed compost bag (I+S) of the 15 kGy set up. There was no significant difference (P>0.05) in final linear growth range of 190.2- 248.8 mm recorded for all pretreated samples which also recorded very low (0- 20%) contamination. Gamma irradiation was shown to be a good substitute and more efficient for sterilizing composted sawdust for mushroom cultivation and yield in the Ghanaian tropic conditions. [ABSTRACT FROM AUTHOR]