Heat Sterilization Research Articles

Evaluation of the accuracy of cone beam computed tomography (CBCT) generated tooth replicas with application in autotransplantation

ObjectivesThe primary aim of this study was to assess the linear and geometric accuracy of 3-dimensional (3D) printed tooth replicas when compared to the actual tooth. The secondary aims were to compare the accuracy of three different 3D printers and to evaluate dimensional changes of tooth replicas after sterilization. MethodsA sample of 16 teeth were selected from recruited patients. Segmentation was carried out to generate files from the patient's cone beam computed tomography (CBCT) data, Tooth replicas were then printed using three printers making use of Polyjet, laser stereolithography (SLA) and digital light processing (DLP) technology respectively. These replicas, along with the actual tooth, were scanned by an optical scanner. Replicas were sent for sterilization and scanned again. Paired superimposition of the scans was performed. ResultsA mean length difference of 0.36 mm and mean geometric (root mean square [RMS]) difference of 0.56 mm was found. Qualitative analysis showed that the replicas were generally larger in size. Repeated ANOVA tests showed that the Polyjet printer had the highest accuracy (p<0.0001). After sterilization, there was an overall mean length difference of 0.10 mm and RMS deviation of 0.02 mm. ConclusionThis study found that there was a significant difference in linear and geometric measurements of the tooth replicas when compared to the actual tooth. This study also provides evidence that the printer which made use of Polyjet technology was able to produce more accurate models than SLA or DLP printers. Printed tooth models demonstrated clinically insignificant changes after heat sterilization. Clinical significance3D printed tooth replicas derived from the patient's CBCT data may be used in autotransplantation to increase predictability of the procedure. In order for this novel digital approach to realize its potential, it is critical to address questions as to how accurate the various printing technologies are in fabricating replicas.

Dynamic tracing of bacterial community distribution and biofilm control of dominant species in milk powder processing

Thermophilic spore-forming bacteria are common contaminations in milk powder processing lines. In this study, a remarkable change of bacterial community structure was observed after heat sterilization, and thermophilic bacteria took significant advantages after high temperature treatment. Some culturable thermophilic spores survived from pasteurization and even ultra-high temperature sterilization. Feed tank before spraying drying proved to be a key point for controlling thermophilic bacteria. Benzalkonium chloride (BAC) is an effective disinfectant to remove biofilms formed by the isolated dominant species, Bacillus licheniformis. The synergistic reduction of B. licheniformis biofilm on stainless steel in skimmed milk was 3.89 log CFU/cm2 after combined treatment by 0.0625% (v/v) BAC and cleaning-in-place (CIP). This research provided meaningful proposals on determinations of critical control points in a milk powder processing line and removal strategies of B. licheniformis biofilm, which are of valuable significance on quality guarantees for dairy industry.

Heat Sterilization Effects on Polymeric, FDM-Optimized Orthopedic Cutting Guide for Surgical Procedures.

Improvements in software for image analysis have enabled advances in both medical and engineering industries, including the use of medical analysis tools to recreate internal parts of the human body accurately. A research analysis found that FDM-sourced elements have shown viability for a customized and reliable approach in the orthopedics field. Three-dimensional printing has allowed enhanced accuracy of preoperative planning, leading to reduced surgery times, fewer unnecessary tissue perforations, and fewer healing complications. Furthermore, using custom tools chosen for each procedure has shown the best results. Bone correction-related surgeries require customized cutting guides for a greater outcome. This study aims to assess the biopolymer-based tools for surgical operations and their ability to sustain a regular heat-sterilization cycle without compromising the geometry and fit characteristics for a proper procedure. To achieve this, a DICOM and FDM methodology is proposed for fast prototyping of the cutting guide by means of 3D engineering. A sterilization test was performed on HTPLA, PLA, and nylon polymers. As a result, the unique characteristics within the regular autoclave sterilization process allowed regular supplied PLA to show there were no significant deformations, whilst annealed HTPLA proved this material’s capability of sustaining repeated heat cycles due to its crystallization properties. Both of these proved that the sterilization procedures do not compromise the reliability of the part, nor the safety of the procedure. Therefore, prototypes made with a similar process as this proposal could be safely used in actual surgery practices, while nylon performed poorly because of its hygroscopic properties.

Influence of Fresh Palm Fruit Sterilization in the Production of Carotenoid-Rich Virgin Palm Oil.

Palm oil is known to be rich in carotenoids and other phytonutrients. However, the carotenoids and phytonutrients degrade due to high heat sterilization of oil palm fruits. The present study was conducted to produce carotenoid-rich virgin palm oil (VPO) using cold-press extraction. Herein, the influence of sterilization of oil palm fresh fruits in the production of cold-pressed VPO was determined with varying sterilization temperatures, times, and amounts of palm fruits in sterilization. The experimental sterilization conditions were optimized using response surface methodology (RSM) based on the maximum VPO yield and minimum FFAs in cold-pressed VPO. The optimal sterilization experimental conditions of oil palm fruits were determined to be a sterilization temperature of 62 °C, a time of 90 min, and an amount of oil palm fruits of 8 kg. Under these experimental conditions, the maximum cold-pressed VPO yield and the minimal content of free fatty acids (FFAs) obtained were 27.94 wt.% and 1.32 wt.%, respectively. Several analytic methods were employed to determine cold-pressed VPO quality and fatty acids compositions and compared with the crude palm oil. It was found that cold-pressed VPO contains higher carotenoids (708 mg/g) and unsaturated fatty acids compared with the carotenoid (343 mg/g) and fatty acid compositions in CPO. The findings of the present study reveal that the sterilization temperature potentially influences the carotenoid and nutrient contents in VPO; therefore, the optimization of the sterilization conditions is crucial to producing carotenoid- and phytonutrient-rich VPO.

Quantification of Degradation Products Formed during Heat Sterilization of Glucose Solutions by LC-MS/MS: Impact of Autoclaving Temperature and Duration on Degradation.

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 <0.078 μg/mL, and the limit of quantification was <0.236 μg/mL. The autoclaving time of 121 °C and 15 min resulted in the lowest levels of 3-DG/3-DGal and 5-HMF, but in the highest levels of GO and 2-KDG. The proposed LC-MS/MS method is rapid and sensitive. So far, only 5-HMF concentrations are limited by the regulatory authorities. Our results suggest reconsidering the impurity limits of various GDPs, especially the more toxic ones such as GO and MGO, by the Pharmacopoeias.

On-Slide Heat Sterilization Enables Mass Spectrometry Imaging of Tissue Infected with High-Threat Pathogens Outside of Biocontainment: A Study Directed at Mycobacterium tuberculosis.

Mass spectrometry imaging investigations of tissues infected with agents that require high-security biocontainment, such as Mycobacterium tuberculosis, have been limited due to incompatible sterilization techniques. Here we describe an on-slide heat sterilization method that enables mass spectrometry imaging investigations of pharmaceuticals, lipids, and metabolites in infected tissue samples outside of biocontainment. An evaluation of different temperatures and incubation times determined that 100 °C for 1 h was essential to sterilize 5 times the bacterial burden observed in tuberculosis (TB) cavity sections. Laser-capture microdissection combined with liquid chromatography with tandem mass spectrometry quantitation, in addition to mass spectrometry imaging, showed that no degradation was observed following the on-slide heat sterilization protocol for a variety of drug classes covering a range of physicochemical properties. Utilizing the tissue mimetic model, we demonstrated that the detection of lipid and metabolite ions was not impacted by heat sterilization and that, for several metabolites, the on-slide heat sterilization method improved the sensitivity when compared to control samples. An application of the on-slide heat sterilization to M. tuberculosis infected tissue enabled the first detection and spatial distribution of lipids indicative of a lysosomal storage disease phenotype within TB granuloma macrophages, in addition to the differential distribution of metabolites central to the fatty acid oxidation pathway. These initial investigations detected a pronounced heterogeneity within the cellular regions and necrotic cores of individual TB granulomas and across different evolving granulomas. This study provides the framework for mass spectrometry imaging investigations of high-threat pathogens outside of biocontainment.

Transparent Air Filters with Active Thermal Sterilization.

The worldwide proliferation of COVID-19 poses the urgent need for sterilizable and transparent air filters to inhibit virus transmission while retaining ease of communication. Here, we introduce copper nanowires to fabricate transparent and self-sterilizable air filters. Copper nanowire air filter (CNAF) allowed visible light penetration, thereby can exhibit facial expressions, helpful for better communication. CNAF effectively captured particulate matter (PM) by mechanical and electrostatic filtration mechanisms. The temperature of CNAF could be controlled by Joule-heating up to 100 °C with thermal stability. CNAF successfully inhibited the growth of E. coli because of the oligodynamic effect of copper. With heat sterilization, the antibacterial efficiency against G. anodireducens was greatly improved up to 99.3% within 10 min. CNAF showed high reusability with stable filtration efficiency and thermal antibacterial efficacy after five repeated uses. Our result suggests an alternative form of active antimicrobial air filter in preparation for the current and future pandemic situations.

Reusing Face Covering Masks: Probing the Impact of Heat Treatment.

The COVID-19 pandemic resulted in imminent shortages of personal protective equipment such as face masks. To address the shortage, new sterilization or decontamination procedures for masks are quickly being developed and employed. Dry heat and steam sterilization processes are easily scalable and allow treatment of large sample sizes, thus potentially presenting fast and efficient decontamination routes, which could significantly ease the rapidly increasing need for protective masks globally during a pandemic like COVID-19. In this study, a suite of structural and chemical characterization techniques, including scanning electron microscopy (SEM), contact angle, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman were utilized to probe the heat treatment impact on commercially available 3M 8210 N95 Particulate Respirator and VWR Advanced Protection surgical mask. Unique to this study is the use of the synchrotron-based In situ and Operando Soft X-ray Spectroscopy (IOS) beamline (23-ID-2) housed at the National Synchrotron Light Source II at Brookhaven National Laboratory for near-edge X-ray absorption spectroscopy (NEXAFS).

Development of technology for production of functional fruit drinks

The object of research is the technology of functional fruit and vegetable juice products enriched with collagen. The subject of research is various types of collagen, formulations and parameters of technological operations for the production of functional juice drinks. The research is aimed at the develop technology, recipes for a new assortment of fruit and vegetable drinks enriched with collagen. Also it is aimed at the preserve the functional properties of collagen in canned juice products after high-temperature processing and create food products for everyday consumption to solve age-related and other problems associated with human health. In the course of the study, standard methods were used to determine the organoleptic indicators of various types of collagen, juice products, as well as to determine the mass fraction of moisture, carbohydrates, fats, proteins in the developed fruit and vegetable drinks enriched with collagen. Also, to confirm the presence and preservation of collagen in finished products, the electrophoresis method was used to determine the atomic mass unit of the constituent substances after complete drying of the samples. The proposed methods make it possible to assess the quality of the developed collagen-enriched drinks, prove the presence and preservation of a biologically active additive in the finished product after using the sterilization mode parameters – temperature and time, when receiving canned products. The developed formulations and technology make it possible to consider functional fruit and vegetable juice-containing products enriched with a biologically active additive collagen as effective and useful. An easily digestible food product for everyday consumption is proposed for solving age-related and other problems related to human health, with regulation of the pH value for effective use of the beneficial properties of this additive. In contrast to existing functional juice products, the proposed formulations and technology make it possible to obtain juice-containing fruit and vegetable blended products with a biologically active additive collagen. The technology minimizes the impact of collagen on the organoleptic characteristics of the developed recipe compositions of finished products and preserves its beneficial biologically active properties in the finished canned product after heat sterilization.

Infection control in dentistry

Infection control is important in the practice of dentistry because dental healthcare workers and patients are exposed to e wide variety of microorganisms through blood and oral secretions. A long history of scientific, clinical and technological developments has led to the current recommendations for infection control in dentistry and medicine. As a result, health care workers and their patients have never been protected from occupational transmission of pathogens. Engineering and re-emerging infection control challenges will continue to confront the health profession in the 21st century. In addition, procedures aimed at preventing the spread of infectious disease are constantly being evaluated and updated. Among the important components of any infection control success, however, always will be remembering and understanding the rationale for appropriate practices. The routine applications of precautions such as multiple aseptic procedures, latex gloves, masks, protective eyewear, clinic coats, automated instrument decontamination devices, time-efficient heat sterilization modalities, chemical disinfectants, waste management procedures and single-use disposable items have created a safer environment for dental personal and patients alike. Hence the review aimed at stressing the importance of sterilization and disinfection in dental practice

Exploring Reusability of Disposable Face Masks: Effects of Disinfection Methods on Filtration Efficiency, Breathability, and Fluid Resistance.

To curb the spread of the COVID‐19 virus, the use of face masks such as disposable surgical masks and N95 respirators is being encouraged and even enforced in some countries. The widespread use of masks has resulted in global shortages and individuals are reusing them. This calls for proper disinfection of the masks while retaining their protective capability. In this study, the killing efficiency of ultraviolet‐C (UV‐C) irradiation, dry heat, and steam sterilization against bacteria (Staphylococcus aureus), fungi (Candida albicans), and nonpathogenic virus (Salmonella virus P22) is investigated. UV‐C irradiation for 10 min in a commercial UV sterilizer effectively disinfects surgical masks. N95 respirators require dry heat at 100 °C for hours while steam treatment works within 5 min. To address the question on safe reuse of the disinfected masks, their bacteria filtration efficiency, particle filtration efficiency, breathability, and fluid resistance are assessed. These performance factors are unaffected after 5 cycles of steam (10 min per cycle) and 10 cycles of dry heat at 100 °C (40 min per cycle) for N95 respirators, and 10 cycles of UV‐C irradiation for surgical masks (10 min per side per cycle). These findings provide insights into formulating the standard procedures for reusing masks without compromising their protective ability.

A Computational Fluid Dynamics (CFD) model to simulate the inactivation of Geobacillus stearothermophilus spores in different moist heat sterilization environments

The aim of this study was to develop a Computational Fluid Dynamics (CFD) model to simulate the inactivation of bacterial spores of Geobacillus stearothermophilus inside a Peritoneal Dialysis Bag System (PDBS). The presented CFD model has three significant modifications in comparison to current state-of-the-art simulations of sterilization processes. (i) The CFD simulation can be used to consider the multiphase flow (water, steam, different dialysis solutions, non-condensable gases (NCGS)) inside the PDBS, the natural convection as well as the steam penetration. (ii) Experimentally obtained inactivation kinetics were added to the CFD code to enable simulation of the inactivation of G. stearothermophilus spores. (iii) The inactivation process of G. stearothermophilus spores was simulated in different sterilization environments which are present inside a PDBS. The CFD model was verified with measurements using Biological Indicators (BIs). Results showed that on the pre-CFD-simulated “worst case locations” CFD simulations and the BI-based verification were in well accordance.By using the presented CFD model, the simulation of a moist heat sterilization process can be performed for any given sterilization cycle. In addition, the model is a powerful tool that can be used to optimize steam sterilization processes and guarantee a high level of sterilization efficiency and product safety.

Effect of Ferrous Ion on Heat-Induced Aroma Deterioration of Green Tea Infusion.

Aroma deterioration is one of the biggest problems in processing tea beverages. The aroma of tea infusion deteriorates fast during heat sterilization and the presence of ferrous ion (Fe2+) aggravates it. The underlying mechanism remains unveiled. In this study, Fe2+ was verified to deteriorate the aroma quality of green tea infusion with heat treatment. Catechins were necessary for Fe2+-mediated aroma deterioration. By enhancing the degradation of catechins, Fe2+ dramatically increased the production of hydrogen peroxide (H2O2). Fe2+ and H2O2 together exacerbated the aroma of green tea infusion with heat treatment. GC-MS analysis revealed that the presence of Fe2+ enhanced the loss of green/grassy volatiles and promoted the formation of new volatiles with diversified aroma characteristics, resulting in a dull scent of green tea infusion. Our results revealed how Fe2+ induced aroma deterioration of green tea infusion with heat treatment and could help guide tea producers in attenuating the aroma deterioration of tea infusion during processing.

Post-treatments of polydopamine coatings influence cellular response

Polydopamine (PDA) is the final oxidation product of dopamine or other catecholamines. Since the first reports of PDA coatings starting around 2007, these coatings have been widely studied as a versatile and inexpensive one-step coating option for biomaterial functionalization. The coating attach to a wide range of materials and can subsequently be modified with biomolecules or nanoparticles. However, as a strong candidate for biomaterial research and even clinical use, it is important to unravel the changes in physico-chemical properties and the cell-PDA interaction as a function of heat sterilization procedures and shelf storage periods. Four groups were examined in this study: titanium (Ti), PDA-coated Ti samples and PDA-coated Ti samples either stored for up to two weeks at room temperature or heated at 121 °C for 24 h, respectively. We used X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Water contact angle (WCA) to characterize chemical composition and surface properties of the groups. Cell adhesion and proliferation was examined by three different cell types: human primary dermal fibroblasts (hDF), human epidermal keratinocytes (HaCaTs) and a murine preosteoblastic cell line (MC3T3-E1), respectively. Cells were cultured on PDA coated samples for 4 h, 3 days and 5 days. Both thermal treatment of PDA at 121℃ for 24 h and storage of the samples for 2 weeks increased the amount of quinone groups at the surface and decreased the amount of primary amine groups as detected by XPS and ToF-SIMS. Even though these surface reactions increased the WCA of the PDA coating, we found that the post-treatments increased cell proliferation for both hDFs, HaCaTs and MC3T3-E1 s as compared to pristine PDA. This emphasizes the importance of post-treatment and shelf-time for PDA coatings.

Effects of Steam Heat and Dry Heat Sterilization on Thermal and Mechanical Properties of Nylon and Policarbonate in Fabrication with Fused Filament

In this article presents evidence about performance of mechanical properties of polycarbonate and nylon materials, which are used in the additive manufacturing by deposition of molten material and that have been subjected to sterilization processes by moist heat at 121°C and dry heat at 140°C. This study provides useful information to consider the use of these materials in sanitary and sterile settings. Mechanical tests of tensile, flex, hardness, Izod impact, thermal tests in Differential Scanning Calorimetry DSC, Thermomechanical analysis TMA and Scanning Electron Microscopy SEM were performed. It is concluded that the mechanical and thermal properties have not been altered through the effect of temperature in sterilization processes.

Identification and quantification of glucose degradation products in heat-sterilized glucose solutions for parenteral use by thin-layer chromatography

During heat sterilization of glucose solutions, a variety of glucose degradation products (GDPs) may be formed. GDPs can cause cytotoxic effects after parenteral administration of these solutions. The aim of the current study therefore was to develop a simple and quick high-performance thin-layer chromatography (HPTLC) method by which the major GDPs can be identified and (summarily) quantified in glucose solutions for parenteral administration. All GDPs were derivatized with o-phenylenediamine (OPD). The resulting GDP derivatives (quinoxalines) were applied to an HPTLC plate. After 20 minutes of chamber saturation with the solvent, the HPTLC plate was developed in a mixture of 1,4-dioxane-toluene-glacial acetic acid (49:49:2, v/v/v), treated with thymol-sulfuric acid spray reagent, and heated at 130°C for 10 minutes. Finally, the GDPs were quantified by using a TLC scanner. For validation, the identities of the quinoxaline derivatives were confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Glyoxal (GO)/methylglyoxal (MGO) and 3-deoxyglucosone (3-DG)/3-deoxygalactosone (3-DGal) could be identified and quantified in pairs, glucosone (2-KDG), 5-hydroxymethylfurfural (5-HMF), and 3,4-dideoxyglucosone-3-ene (3,4-DGE) each individually. For 2-KDG, the linearity of the method was demonstrated in the range of 1–50 μg/mL, for 5-HMF and 3,4-DGE 1–75 μg/mL, for GO/MGO 2–150 μg/mL, and for 3-DG/3-DGal 10–150 μg/mL. All GDPs achieved a limit of detection (LOD) of 2 μg/mL or less and a limit of quantification (LOQ) of 10 μg/mL or less. R2 was 0.982 for 3.4-DGE, 0.997 for 5-HMF, and 0.999 for 2-KDG, 3-DG/3-DGal, and GO/MGO. The intraday precision was between 0.4 and 14.2% and the accuracy, reported as % recovery, between 86.4 and 112.7%. The proposed HPTLC method appears to be an inexpensive, fast, and sufficiently sensitive approach for routine quantitative analysis of GDPs in heat-sterilized glucose solutions.

Effects of dairy processing on phospholipidome, in-vitro digestion and Caco-2 cellular uptake of bovine milk

Present work investigated the effects of processing (homogenization, sterilization) and cold storage on physicochemical properties, in vitro digestion and Caco-2 cellular uptake of bovine milk. Extreme heat sterilization and low temperature storage have significant impact on particle size and phospholipidome of bovine milk. In addition, cold storage of bovine milks led to formation of β' polymorphs crystals and endothermic peak with Toffset higher than body temperature. Processing and cold storage also increased the initial digestibility but reduced the overall digestibility of bovine milk. This might be related to the decreased particle size of the milk fat globules, changed in the phospholipidome of the MFGM and formation of β' polymorphs crystals in frozen milk. It is interesting to note that PE has relatively faster digestion meanwhile SM has relatively slower digestion. HTST milk which demonstrated lesser changed in terms of phospholipidome demonstrated highest cellular uptakes of most fatty acids.

Global Dialysis Perspective: Brunei Darussalam.

Brunei Darussalam is a small country in Southeast Asia, with a population of less than half a million people. Hemodialysis (HD) first began in the country in 1968, using single-patient Dylade model B proportioning machines with heat sterilization and Kiil dialyzers (1,2). Scribner arteriovenous shunts were inserted into patients’ legs by nephrologists. Interestingly, patients were required to manage their own dialysis, which usually extended to 10 hours each session, independent of nursing staff. There were stringent criteria for patient selection. Since the open-door policy was set out in 1985, the incidence and prevalence of KRT have increased significantly (Figure 1). Figure 1. Incidence and prevalence of KRT . Brunei has some of the world’s highest KRT incidence and prevalence. In 2018, the incidence and prevalence of KRT were 380 and 1769 per million population, respectively (Table 1), placing Brunei in the top five globally for incidence and in the top nine for prevalence of patients on KRT (3). The Brunei Dialysis and Transplant Registry was created in 2011 to enable a systematic collection of KRT data. The registry has enabled our nephrology services to be benchmarked against international registries, and it is unique as it captures all patients on KRT in the country. However, in our Brunei Dialysis and Transplant Registry, patients who were incident were excluded if death happened within 2 weeks of starting KRT, rather than the more commonly defined 90 days in other national registries, which might explain the disproportionately higher incidence compared with prevalence in Brunei. In 2019, the mean and median ages of death were 61.3 and 62 years, respectively. About 25% of the mortality happened within the first year of dialysis. The top cause of mortality was infection (28%), followed by cardiovascular death (23%). Hospitalization data are not available. View this table: Table 1. Annual trend of kidney …

In-House, Fast FDM Prototyping of a Custom Cutting Guide for a Lower-Risk Pediatric Femoral Osteotomy

Three-dimensional printed custom cutting guides (CCGs) are becoming more and more investigated in medical literature, as a patient-specific approach is often desired and very much needed in today’s surgical practice. Three-dimensional printing applications and computer-aided surgical simulations (CASS) allow for meticulous preoperatory planning and substantial reductions of operating time and risk of human error. However, several limitations seem to slow the large-scale adoption of 3D printed CCGs. CAD designing and 3D printing skills are inevitably needed to develop workflow and address the study; therefore, hospitals are pushed to include third-party collaboration, from highly specialized medical centers to industrial engineering companies, thus increasing the time and cost of labor. The aim of this study was to move towards the feasibility of an in-house, low-cost CCG 3D printing methodology for pediatric orthopedic (PO) surgery. The prototype of a femoral cutting guide was developed for its application at the IOR—Rizzoli Orthopedic Institute of Bologna. The element was printed with an entry-level 3D printer with a high-temperature PLA fiber, whose thermomechanical properties can withstand common steam heat sterilization without bending or losing the original geometry. This methodology allowed for extensive preoperatory planning that would likewise reduce the overall surgery time, whilst reducing the risks related to the intervention.

Performance study of a sterilization box using a combination of heat and ultraviolet light irradiation for the prevention of COVID-19

SARS-CoV-2 virus and other pathogenic microbes are transmitted to the environment through contacting surfaces, which need to be sterilized for the prevention of COVID-19 and related diseases. In this study, a prototype of a cost-effective sterilization box is developed to disinfect small items. The box utilizes ultra violet (UV) radiation with heat. For performance assessment, two studies were performed. First, IgG (glycoprotein, a model protein similar to that of spike glycoprotein of SARS-COV-2) was incubated under UV and heat sterilization. An incubation with UV at 70 °C for 15 min was found to be effective in unfolding and aggregation of the protein. At optimized condition, the hydrodynamic size of the protein increased to ~171 nm from ~5 nm of the native protein. Similarly, the OD280 values also increased from 0.17 to 0.78 indicating the exposure of more aromatic moieties and unfolding of the protein. The unfolding and aggregation of the protein were further confirmed by the intrinsic fluorescence measurement and FTIR studies, showing a 70% increase in the β-sheets and a 22% decrease in the α-helixes of the protein. The designed box was effective in damaging the protein's native structure indicating the effective inactivation of the SARS-COV-2. Furthermore, the incubation at 70 °C for 15 min inside the chamber resulted in 100% antibacterial efficacy for the clinically relevant E.coli bacteria as well as for bacteria collected from daily use items. It is the first detailed performance study on the efficacy of using UV irradiation and heat together for disinfection from virus and bacteria.