Contamination Processes Research Articles

Compressor fouling detection by image analysis

Gas turbine fouling is commonly known as responsible for performance degradation in terms of compression ratio and efficiency. The adhesion of micro-sized particles (soil, soot, salt, etc.) caused the modification of the blade shapes and the surface roughness. Both of these two effects determine the modification of the compressor performance over the unit operation. Due to the lack of capability to forecast the fouling intensity, it could be useful to estimate the fouling intensity during the machine overhaul, collecting strategical data by which a specific characterization of a given machine in a given operating site can be done. The present paper proposes and validates a helpful methodology for estimating the deposit intensity by an image analysis procedure. An image-detection technique has been carried out before and after the contamination process, and, using a subtraction process, a quantitative analysis of the fouled regions can be developed. The results show that, with a careful light and camera setup, the intensity of the deposits can be estimated with an acceptable tolerance band, which allows the possibility of collecting quantitative data on compressor deposits during overhaul operations. This generates a valuable starting point for predicting the overtime degradation of the unit and/or estimating the filtration section efficiency.

Contaminant back-diffusion from layered aquitards subjected to barrier-controlled source zones

Low-permeability aquitards may serve as secondary sources of slow-releasing contaminants into the adjacent aquifer system, creating considerable obstacles to groundwater cleanup. Accurately capturing the exchange of contaminant mass between aquitards and aquifers can facilitate site management and remediation. Previous simulation studies were mainly limited to one-dimensional (1D) back diffusion from aquitards during the remediation of the source zone. In this study, a novel two-dimensional (2D) back-diffusion model is developed to investigate the storage and release of contaminants in aquitards after source isolation. This model coupled the dynamical decay of isolated sources and the diffusion-sorption process of contaminants in the layered aquitards. Exact analytical solutions for the present 2D multilayer model were derived using the finite cosine transform, Duhamel Theorem, separation of variables, and transfer matrix method. Results indicated that the previous 1D model would overestimate the contaminant concentration in the aquitard and the back-diffusion risk when the source zone was isolated. The proposed 2D back-diffusion model enables quantitative prediction of how source zone width, source concentration, and aquitard heterogeneity impact plume trailing time, thus aiding in understanding the mechanisms of aquifer contamination beyond barrier-controlled source zones.

Density Differences Affect the Mixing Process of Pollutants in The River Confluence Area

AbstractThe influence of density differences on the mixing process of pollutants in the confluence area of the Yellow River (YR) and Fen River (FR) is unclear. This study conducts several field experiments on the hydrodynamic and pollution concentrations in a large asymmetric confluence. The mixing rate and deviation from complete mixing (δ) for the pollutant concentrations are used to describe the mixing process and intensity of contaminants. The results show that the density differences caused by the sediment concentration are an essential factor affecting the pollutant mixing process in the confluence area. After ≈14.7 dimensionless river lengths, the δ of the pollutants in the confluence area, under the strong density difference, drops below 10%. In comparison, the maximum δ under the other density differences still exceeds 10% after 27.5 dimensionless river lengths. The strong density difference in the confluence area enhances the pollutant mixing process and shortens the mixing distance. The flow velocity distribution and shear layer changes under different density differences are important driving forces that affect the mixing process of pollutants. This study is of great scientific significance, as it helps gain insight into the mixing pattern of pollutants in river confluence areas.

Remediation processes of hexavalent chromium from groundwater: a short review

Abstract Understanding the sources and controlling processes of various groundwater contaminants and their removal methods is extremely important, as groundwater contamination is intricately linked to human health. Chromium (Cr) is a common groundwater contaminant with both natural and anthropogenic origins. Dissolved Cr exists in hexavalent and trivalent forms – while the former is carcinogenic and more soluble – the latter is a micronutrient at low levels and is less soluble. Therefore, most chromium removal methods rely on reducing the hexavalent chromium to its trivalent state to decrease the Cr-toxicity. In recent years, several experimental methods have been attempted for hexavalent chromium removal from aqueous media/groundwater. This paper reviews the recent findings on Cr removal by important, effective, and widely used methods such as adsorption by nanoscale zero-valent Fe-based and conventional materials, electrocoagulation (EC), and bioremediation. The reaction pathways, mechanisms, and effectiveness of each method are also highlighted. The role of parameters such as solution pH and temperature, initial Cr(VI) concentration, contact time with the reducing agent, adsorbent dose, and the presence of competing ions on Cr removal was evaluated. Many of the methods exhibit high (>90%) Cr removal efficiency; the main challenge would be to apply these methods for large-scale water treatment.

Influence of Surface Roughness, Nanostructure, and Wetting on Bacterial Adhesion.

Bacterial fouling is a persistent problem causing the deterioration and failure of functional surfaces for industrial equipment/components; numerous human, animal, and plant infections/diseases; and energy waste due to the inefficiencies at internal and external geometries of transport systems. This work gains new insights into the effect of surface roughness on bacterial fouling by systematically studying bacterial adhesion on model hydrophobic (methyl-terminated) surfaces with roughness scales spanning from ∼2 nm to ∼390 nm. Additionally, a surface energy integration framework is developed to elucidate the role of surface roughness on the energetics of bacteria and substrate interactions. For a given bacteria type and surface chemistry; the extent of bacterial fouling was found to demonstrate up to a 75-fold variation with surface roughness. For the cases showing hydrophobic wetting behavior, both increased effective surface area with increasing roughness and decreased activation energy with increased surface roughness was concluded to enhance the extent of bacterial adhesion. For the cases of superhydrophobic surfaces, the combination of factors including (i) the surpassing of Laplace pressure force of interstitial air over bacterial adhesive force, (ii) the reduced effective substrate area for bacteria wall due to air gaps to have direct/solid contact, and (iii) the reduction of attractive van der Waals force that holds adhering bacteria on the substrate were summarized to weaken the bacterial adhesion. Overall, this study is significant in the context of designing antifouling coatings and systems as well as explaining variations in bacterial contamination and biofilm formation processes on functional surfaces.

Numerical Research on Migration Law of Typical Chlorinated Organic Matter in Shallow Groundwater of Yangtze Delta Region

With the reform of China’s urbanization increasing in popularity, the security issues posed by urban groundwater, especially groundwater in industrial areas, have attracted scholars’ attention. This research aimed to predict and quantify the migration process of contaminants in a microconfined aquifer by conducting a groundwater contamination investigation in an abandoned chemical plant in the Jiangsu Province of China. First, data such as regional hydrogeological parameters and types of contaminants were obtained via hydrogeological drilling, groundwater well monitoring, pumping tests, and laboratory permeability tests, which helped identify the most serious pollution factor: chloroform. Then, a groundwater flow model was built using the Groundwater Modeling System (GMS) and verified using the general-purpose parameter estimation (PEST) package. In addition, based on the three-dimensional multi-species model for transport (MT3DMS) in GMS, a transport model was established. The results illustrate that the plume range of chloroform diffuses with water flow, but, because of its slow diffusion rate and inability to degrade naturally, the concentration of the contaminant has remained several times higher than the safety standard for a long time. The contaminant spread vertically to the soil layer above the microconfined aquifer under pressure, resulting in direct pollution. In addition, the contaminant in the microconfined aquifer is anticipated to migrate down to the clay layer and become enriched. However, the first confined aquifer has not been seriously polluted in the past 20 years. Finally, a sensitivity analysis of the parameters shows that groundwater contamination in the Yangtze delta region is greatly affected by precipitation recharge and hydraulic conductivity.

On scalar transport in an oscillatory Couette–Poiseuille flow under the effects of heterogeneous and bulk chemical reactions: A multi-scale approach

This research presents an analytical solution to explore a two-dimensional concentration transport of solute in an oscillatory Couette–Poiseuille flow between two parallel plates in the presence of homogeneous and heterogeneous reactions. Mei's homogenization method up to second order approximation is used to find the multi-dimensional concentration distributions, namely, transverse concentration distribution, longitudinal concentration distribution, mean concentration distribution, Taylor dispersion coefficient, and the transverse uniformity simultaneously for three different flow conditions: steady, periodic, and the joint effect of steady and periodic Couette–Poiseuille flow for the first time. The distribution of transverse concentration of solute is studied due to its importance in oil lubrication and industrial applications. The transverse variation rate shows that the introduction of heterogeneous reactions cause transverse non-uniformity, but it is significant to note that homogeneous reaction has no effect on it. Furthermore, the maximum variation rate of the concentration cloud is obtained along the upstream and downstream directions when the boundary absorption is considered at steady and moving plates, respectively. To validate the present analytical model, a comparison is performed with the numerical solution and has achieved an excellent agreement. The outcomes of the present study may be helpful to develop a better understanding of the process of contamination and to prevent the pollution in the flow.

Monitoring of in-situ chemical oxidation for remediation of diesel-contaminated soil with electrical resistivity tomography

In-situ chemical oxidation (ISCO) with persulfate, an electrically conductive oxidant, provides a powerful signal for noninvasive geophysical techniques to characterize the remediation process of hydrocarbon contaminants. In this study, remediation with ISCO is conducted in laboratory sandboxes to evaluate the ability of electrical resistivity tomography (ERT) for monitoring the base-activated persulfate remediation process of diesel-contaminated soil. It was found that the resistivity of contaminated sand significantly decreased from 846 Ω·m to below 10 Ω·m after persulfate injection, and all measured chemical parameters showed a noticeable increase. Natural degradation and contamination plume migration were not evident in a reference sandbox without treatment. The area with a resistivity ratio < 0.95 based on imaging before and after injection indicated downward migration of the oxidation plume due to density-driven flow. A comparison between remediation and reference sandboxes showed that the observed resistivity decrease can be due to both contaminant degradation as well as the oxidation plume itself in the contaminated source zone. In contrast, the resistivity decrease in the area with low contamination concentration is attributed to the oxidation plume alone. The derived relationships between resistivity and contaminant indicators further emphasize that the contribution of contaminant consumption to resistivity change in the source area is 25.6%, while it is <16% in the low or non-contaminated area. Although this study showed that resistivity is not solely affected by the chemical transformation of diesel components, it can be combined with sampling data to allow an assessment of the effectiveness of ISCO treatment and to identify target areas for subsequent treatment.

Geochemical and thermodynamic constraints on Archean comagmatic volcanic and cumulate rocks from southern West Greenland

The extensive exposure of the Archean continental crust in southern West Greenland makes it an important window into the tectonic evolution of early Earth. Here, we provide a comprehensive geochemical data set for tholeiitic amphibolites (meta-basalts), calc-alkaline leucoamphibolites (meta-andesites), and ultramafic rocks (meta-cumulates) for the Mesoarchean Bjørneøen Supracrustal Belt, Nuuk region, SW Greenland. This data helps constrain the geodynamic setting in which these rocks formed. The volcanic rocks display two distinct geochemical trends in terms of their La/Sm ratios. Nonetheless, both tholeiitic amphibolites and leucoamphibolites have negative Nb-Ta-Ti anomalies and thus geochemical features associated with apparent island arc or crust contamination processes. Uranium-lead zircon dating of a leucoamphibolite yields an age of 3077 ± 6 Ma, which is older than regional orthogneisses. A series of models for both major element variation (thermodynamics-based) and trace element variation (partition coefficient-based) implies that fractional crystallization of tholeiitic basalt can effectively produce the observed ultramafic rocks. Such ultramafic cumulates had low degrees of crystallinity, reflecting open system magmatic process at shallow depths likely representing magma conduits in a volcanic pile. The geochemical features of the andesites are distinct from the basalts and our modeling excludes a connection via fractional crystallization or crustal assimilation of the two suites. Instead, the andesites formed via high degrees of mixing between basaltic and felsic endmember magmas, requiring elevated temperatures in the mid- to lower-crust. The introduction of felsic components could be derived from partial melting of mafic lower crust, for example by mafic underplating or via some other process that achieves such anatexis, or alternatively by the addition of rhyolitic melt from extensive fractional crystallization. Mixing and homogenization of basaltic and felsic endmembers to produce andesites may occur in modern-style subduction environments, although this could also be feasible in other geodynamic settings in a hotter early Earth.

Insight into the photodegradation and universal interactive products of 2,2',4,4'-tetrabromodiphenyl ether on three microplastics.

The transformation process of contaminants on microplastics (MPs) exposed to sunlight has attracted increasing attention. However, the interactions between them are typically disregarded; therefore, this work investigated the photodegradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on three MPs (polystyrene (PS), polypropylene (PP) and polyethylene (PE)) and the interactions between these two. The inhibition of aged PS on the elimination of BDE-47 was due to light shielding, while aged PP and PE increased the degradation rate. More hydroxyl radicals (HO•) was detected in the PS system, which resulted in the higher degradation rate of BDE-47 on PS. A total of 33 different products were identified and four reaction pathways were presented, and the reaction mechanisms mainly included debromination, hydroxylation, carbon-oxygen-bond breaking and interactive reactions. The Ecological Structure Activity Relationship (ECOSAR) and Toxicity Estimation Software Tool (TEST) programs were used to evaluate the toxicity of reaction products, and the results indicated that even though BDE-47 was the most toxic, the interaction products were still toxic or harmful to aquatic organisms. This study provides significant information on the photodegradation of contaminants on common microplastics and their interaction, which cannot be ignored.

Quantification of Floc Growth for Sediment with Mixing Intensity

Pollutants related to water quality often exist in rivers and form clusters. These pollutants adversely affect river environments and ecosystems. In Korea, the public’s interest in water quality has been increasing for decades. Many studies on water quality and pollutants in sewage treatment plants have been conducted; however, studies on the formation of flocs based on the flow characteristics of rivers are insufficient. In general, it is known that floc formation is influenced by hydraulic characteristics, such as velocity and turbulence, and that it combines them with contaminants in the river. However, studies that quantitatively analyze this topic are also insufficient. An analysis of floc formation between sediments must be conducted to understand the formation process of sediments and contaminants. Therefore, in this study, kaolin, which is a cohesive sediment, was used to quantify the floc formation process according to the mixing intensity. Turbidity was analyzed to observe the amount of floc formation, and samples were collected to confirm the concentration. Additionally, the turbidity concentration relationship according to the mixing intensity was quantified using an optical microscope. Regarding the mixing intensity, when the rotation speed was 200 rpm or more, the separation of the flocs was dominant. In contrast, when the rotation speed was 100 rpm or less, turbidity changes due to sedimentation and floc formation were dominant. Analyzing mixing intensities and their association with the flow characteristics of rivers may be useful for the management of contaminants in rivers.

Metrologically sound comparison of trace-metal levels in sea cucumber tissues from different species and habitats

Sea cucumbers are indicators of metal contamination in sea bottoms due to their low mobility and feeding behaviour. Comparing contaminations of specimens from different locations, habitats, and/or organs allows understanding of contamination processes and differences. However, the interpretation of these data is affected by the variability of contamination levels in specimens, the uncertainty of tissue analyses, and the complex correlation of mass fractions estimated by using the same calibration of the used instrumental method of analysis. This work presents a novel tool for the sound comparison of contamination levels of biota where all mentioned factors are considered to produce reliable and undisputable information on the studied system. The Monte Carlo simulation of uncertainty components, affecting the determination of mean contamination levels observed in selected types of tissues, allowed simulating mean contamination differences and determining if these are meaningful. This tool was used to assess the levels of Cd, Cu, Ni and Pb of animals collected in different locations of Sesimbra-Portugal. It was concluded that specimens that selectively consume macroalgae have larger contamination levels than animals feeding on sediment. The gut is the most contaminated organ suggesting intake from feeding is dominant. Three of the analysed animals have Pb mass fractions larger than a maximum admissible value for human consumption of 3 mg kg−1 with a probability larger than 2.5%.

Joint Estimation of Adsorptive Contaminant Source and Hydraulic Conductivity Using an Iterative Local Updating Ensemble Smoother with Geometric Inflation Selection

The joint estimation of groundwater contaminant source characteristics and hydraulic conductivity is of great significance for reactive contaminant transport models in heterogeneous subsurface media. The accurate determination of the sorption parameters of such contaminants is also a key prerequisite for estimating the parameters of the groundwater system. In this study, to investigate the impact of the sorption parameter field on the accuracy of hydraulic conductivity and source characteristics estimation, numerical experiments were conducted in a synthetic aquifer considering the contaminant sorption process in groundwater models with varying sorption parameter settings. Iterative local updating ensemble smoother with geometric inflation selection (ILUES-GEO) was employed to assimilate hydraulic head and contaminant concentration data to jointly estimate the contaminant source information and hydraulic conductivity in a heterogeneous aquifer. The results indicated that the ILUES-GEO successfully recovers contaminant source information simultaneously with hydraulic conductivity, and its performance improves as more accurate sorption parameters are introduced. Furthermore, the influence of the ILUES algorithm parameters and ensemble size is investigated to improve the estimation accuracy. Additionally, the characterization of contaminant sources and hydraulic conductivity fields is influenced by the number and locations of measurements. This study can help to understand the significance of sorption parameter setting for the joint estimation of reactive contaminant source and hydraulic parameters.

Groundwater Vulnerability and Delineation of Protection Zones in the Discharge Area of a Karstic Aquifer—Application in Agyia’s Karst System (Crete, Greece)

This work represents a contribution to the protection techniques of karst aquifers against groundwater pollution. The paper sets out the methodology being introduced for the protection of the karstic system that gives rise to five (5) major groups of springs and supplies fourteen (14) pumping wells near Agyia Chania (Crete, Greece). Starting from a geological and hydrogeological survey of the area, the work presents a vulnerability assessment of the karstic aquifer based on the application of three index-based methods (EPIK, PRESK and DRISTPI). The protection zones for the discharge area of the aquifer were delineated through an integrated geomorphological approach and groundwater flow modeling. At first, the risk of polluting substances migration from ground surface to groundwater was considered based on the spatial distribution of vulnerability. Following this, the vulnerability was evaluated in the saturated zone, where the attenuation mechanisms of contaminants were reducing due to the raised flow velocity. The groundwater flow and contaminant transport processes was considered using the MODFLOW code. Next, the data from the vulnerability mapping and the groundwater flow simulation were merged into an integrated assessment to delimit the protection zones for the water abstraction points. The vulnerability assessment outlines zones of high vulnerability in the SE part of the area, far away from the discharge zone of the aquifer and the water abstraction points. These zones are associated with an intensive infiltration process via carbonate formations. Protection Zone I was delineated 20 m around the water abstraction points, and it should be excluded from any anthropogenic activity. Protection Zone II coves part of the very high and high vulnerability zones defined by the DRISTPI method (located upwards of the water abstraction points), as well as an area downwards of springs and wells, where the flow path lines which demonstrate the subsurface travelling time of 50 days are projected to the ground surface. Protection Zone III extends outside Zone Ι and Zone ΙΙ, up to the limits of the hydrogeological or hydrological basin, whichever is larger. It includes the entire capture zone (i.e., the surface and underground catchment area) that feeds the water abstraction points. In this manner the protection zones include the entire contributing area to water abstraction points, not just the ground surface recharge zone.

Stromatolitic carbonates from the Middle Miocene of the western Pannonian Basin reflect trace metal availability in microbial habitats during the Badenian Salinity Crisis

Stromatolitic carbonates of the Middle Miocene Oberpullendorf Basin (Austria) provide a great opportunity to study the evolution of microbial habitats under extreme environmental changes during the Badenian (Langhian and early Serravallian) Salinity Crisis. We here present the first geochemical data for Badenian stromatolites and show in a combined approach using major, trace element, and C – O isotope compositions obtained in individual stromatolitic carbonate laminae that short-term variations of palaeo-environmental conditions within the Oberpullendorf Basin coincide with individual microbialite morphologies.The studied carbonates were affected by both detrital contamination and post-depositional alteration processes to different degrees. While fluid-mobile elements show clear evidence for post-depositional alteration processes, the rare earth element and yttrium (REY) as well as bio-essential element (Fe, Mn, Co, Zn, Mo, W) compositions of the carbonates remained unaffected. Stromatolitic carbonates that are devoid of detrital contamination (< 300 ppm Al) show typical shale-normalized seawater-like rare earth element and yttrium (REYSN) patterns with positive LaSN, GdSN anomalies, super-chondritic Y/Ho ratios, and heavy over light REYSN enrichments in the lower stromatolite units. These features suggest an open ocean seawater influenced depositional setting at the north-western margin of the Paratethys Sea. Stratigraphically upwards, pure stromatolitic carbonates show suppressed seawater-like REYSN signatures that argue for the development of a (semi)closed lagoon with restricted access to the open sea. Seawater-like REYSN patterns in the uppermost part resemble a reappearance of open marine environmental conditions. Interestingly, geochemical data of the upper part of the section contradict the ambient fossil record, showing the urge for future interdisciplinary approaches targeting the understanding and interplay of geochemistry, palaeontology, and geomicrobiology in modern and ancient microbial habitats. Enrichment factors of bio-essential trace elements that are either used as co-factors in metalloenzymes or metal-activated enzymes in biochemical reactions can be directly linked to the reconstructed environmental conditions: Sufficient element availability is ensured during marine conditions in the lower and uppermost stratigraphic sections; in contrast, continuous decreasing element availability of these elements is directly related to the temporary development of a (semi)closed lagoon.

Evaluation and Treatment of Cement Contamination in Water Based Mud

Drilling mud is susceptible to contamination, particularly from cement, yet monitoring its characteristics and implementing control and remediation strategies is critical for its performance in safe and cost-effective drilling operations. This study presents an experimental investigation into the evaluation and treatment of cement contamination in Water Based Mud (WBM). Four mud samples were prepared and three were contaminated with 4g, 8g and 12g of cement. A chemical treatment using 6g of sodium bicarbonate was applied as a remedy for contamination. The Rheological properties, mud pH and mud densities of the contaminated and treated Water Based Mud at temperatures of 35°C, 55°C, 75°C and 95°C were determined. Furthermore, the elemental composition of samples of contaminated and treated Water Based Mud was determined using an X-Ray Fluorescence Spectrometer. From the results obtained the mud density increased with a rise in cement concentration for both contamination and treatment with the exception of 8g cement concentration at 75°C and 95°C and 12g cement concentration at 55°C and 75°C where a decrease was observed in the treatment process. The yield point and 10second gel increased for both contamination and treatment process. In contrast, the 10minute gel decreased for both contamination and treatment process. With some exceptions, increasing cement concentration resulted in a decrease in plastic viscosity, whereas treatment with sodium bicarbonate resulted in an increase with some exceptions. The mud pH for the contamination process increased as cement concentration increased, while treatment only marginally increased it with exception of 12g at 75°C and 95°C where a decrease was observed. Sodium bicarbonate treatment improves stability by decreasing excessive calcium and lime contamination from cement, reducing pollutants and enhancing the pH stability of the drilling mud. Additionally, results from the mud characterization indicates a higher percentage of 17.962% lime (CaO) for cement contamination and lower percentage of 15.710% lime (CaO) for treatment with sodium bicarbonate which agrees with literature for the treatment process.

Изучение процесса очистки сточных вод при работе биофильтра в периодическом режиме

The article presents the study results of the performance of the experimental unit with a plastic film load working in a periodic mode of wastewater supply at high initial loads. The kinetics of the process and changes in the efficiency of wastewater treatment over time are considered. As it was revealed, an increase in the load on the bio-filter caused a corresponding increase in the rate of contaminants` removal over the entire range of tested loads, while biomass saturation with the substrate was not observed. This characterizes a high adaptive capacity of the attached biomass to high salvo loads. It is shown that the process of organic contaminants` removal on bio-filter under the conditions of periodic tests has a staged character, indicating the possibility of bio-filter operation in the modes of incomplete and complete biological treatment of wastewater, as well as for nitrification processes. The beginning of the nitrification process and its speed depended on the load on the bio-filter for organic pollution and the degree of wastewater treatment, and the change in the rate of nitrification was autocatalytic. An indicator of the non-oxidizable part of organic pollutants in wastewater is taken into consideration, which can be used in the evaluation of the bio-filter performance.

РЕНТГЕНОМОРФОЛОГИЧЕСКИЕ АСПЕКТЫ СРАЩЕНИЯ ЛУЧЕВОЙ КОСТИ СОБАК ПРИ ИСПОЛЬЗОВАНИИ ОСТЕОПЛАСТИЧЕСКОГО БИОКОМПОЗИЦИОННОГО МАТЕРИАЛА

Injuries of the musculoskeletal system of cats and dogs are determined in more than 20-30% of cases of the total number of internal non-communicable diseases of animals. In veterinary traumatology, there are unresolved problems associated with fractures, deformities, bacterial contamination, reduced osteoconductive and osteoinductive processes. Due to the possibility of using a variety of methods of osteosynthesis using a variety of implants, it is appropriate to use a biocomposite material that satisfies such given needs as: osteoinduction, osteoconduction, antibacterial action, biointegration. As a result, the process of bone tissue fusion will be accelerated. This article describes the results of research, x-ray picture, experimental groups of dogs, using the developed osteoplastic biocomposite material introduced into the bone marrow canal intraoperatively, followed by extrafocal osteosynthesis. For research, X-rays of the studied animals (n=160) were used. The purpose of the scientific study was to obtain an X-ray assessment of the skeletal system in experimental fractures of the radius of dogs and carried out extrafocal osteosynthesis, taking into account the use of the created osteoplastic biocomposite material. The team of co-authors, on the basis of radiography, found that the introduced biocomposite material provides good biocompatibility with further biointegration into the tissue structures of the regenerate, which prevents the formation of fibrillar connective tissue and cartilage. The use of this biocomposite material leads to an acceleration of fracture healing due to osteoconductive, osteoinductive and antibacterial properties, it is also absorbed and biointegrated without reaction to a foreign body.

Evaluating Aseptic Presentation of Different Medical Device Packaging Configurations.

The Medical Device Regulation (MDR) of the European Union (EU) places greater emphasis on the usability of medical devices, with the goal of eliminating or reducing the risk of infection to patients. As this goal also is applicable to sterile packaging, ANSI/AAMI/ISO 11607-1:2019 introduced a usability evaluation requirement for aseptic presentation of terminally sterilized medical devices. In an effort to reduce contamination risks, this requirement focuses specifically on the sterile barrier system (SBS). However, research is limited on evaluating the usability of SBSs and their performance, from an aseptic presentation standpoint, in clinical settings. To address this research gap, we assessed 14 sterile medical devices with five different SBS configurations to elucidate how SBS configuration (type, size, and number of SBS layers) and user satisfaction levels affect usability. A total of 40 experienced clinical nurses participated in 280 individual trials (20 per SBS configuration), which were conducted in a simulated operating room. Ultraviolet fluorescent powder was used to simulate the contamination process and to evaluate the success or failure of the aseptic presentation. Pouch and tray configurations exhibited the best overall performance, while vent bags performed poorly and were considered less acceptable. Double SBS configurations outperformed single SBS configurations. The study highlighted the importance of appropriate SBS symbols to identify SBS layers, which is another patient safety-related requirement of the EU MDR. The current work also includes an analysis of the powder contamination method used in conducting the usability evaluation.

A two-dimensional analytical model for heavy metal contaminants transport in permeable reactive barrier.

Permeable reactive barrier (PRB) remediation technology has been widely used in the remediation of groundwater contamination. In numerical simulations, neglecting the non-uniform distribution of heavy metal contamination along the depth may lead to deviations between simulation results and reality. The distribution of heavy metals in the soil layer around a non-ferrous mining area in Hezhou, Guangxi, southern China was investigated, and it was found that the standard Gaussian function could well describe the non-uniform distribution of heavy metals in the soil layer. A two-dimensional analytical model solved by the finite element method was used to simulate the migration process of heavy metal contamination in the aquifer and PRB. The results show that the uniform distribution of contaminants along the depth ignores the dilution effect, which may underestimate the service life of the PRB and lead to an overly conservative design of the PRB. The breakthrough time of the PRB decreases with the increase of the maximum initial concentration (Cin,max) and the high concentration range (σ), and increases almost linearly with the barrier thickness (Lw). An optimal design method for PRB location and thickness is proposed, which can provide a reference for the engineering application of PRB.