Release Of Metals Research Articles

Effects of Setaria viridis on heavy metal enrichment tolerance and bacterial community establishment in high-sulfur coal gangue

Plant enrichment and tolerance to heavy metals are crucial for the phytoremediation of coal gangue mountain. However, understanding of how plants mobilize and tolerate heavy metals in coal gangue is limited. This study conducted potted experiments using Setaria viridis as a pioneer remediation plant to evaluate its tolerance to coal gangue, its mobilization and enrichment of metals, and its impact on the soil environment. Results showed that the addition of 40% gangue enhanced plant metal and oxidative stress resistance, thereby promoting plant growth. However, over 80% of the gangue inhibited the chlorophyll content, photoelectron conduction rate, and biomass of S. viridis, leading to cellular peroxidative stress. An analysis of metal resistance showed that endogenous S in coal gangue promoted the accumulation of glutathione, plant metal chelators, and non-protein thiols, thereby enhancing its resistance to metal stress. Setaria viridis cultivation affected soil properties by decreasing nitrogen, phosphorus, conductivity, and urease and increasing sucrase and acid phosphatase in the rhizosphere soil. In addition, S. viridis planting increased V, Cr, Ni, As, and Zn in the exchangeable and carbonate-bound states within the gangue, effectively enriching Cd, Cr, Fe, S, U, Cu, and V. The increased mobility of Cd and Pb was correlated with a higher abundance of Proteobacteria and Acidobacteria. Heavy metals, such as As, Fe, V, Mn, Ni, and Cu, along with environmental factors, including total nitrogen, total phosphorus, urease, and acid phosphatase, were the primary regulatory factors for Sphingomonas, Gemmatimonas, and Bryobacter. In summary, S. viridis adapted to gangue stress by modulating antioxidant and elemental enrichment systems and regulating the release and uptake of heavy metals through enhanced bacterial abundance and the recruitment of gangue-tolerant bacteria. These findings highlight the potential of S. viridis for plant enrichment in coal gangue areas and will aid the restoration and remediation of these environments.

Surface sediment erosion characteristics and influencing factors in the subaqueous delta of the abandoned Yellow River Estuary

Estuarine deltas play a critical role in the interaction between the ocean and land and serve as the primary location for the deposition of terrestrial organic carbon and pollutants. However, many deltas are increasingly at risk of erosion due to natural processes and human activities. In particular, abandoned estuarine deltas are extremely prone to erosion in the absence of sediment replenishment. The erosion of sediment in these deltas is crucial in comprehending the evolution of delta erosion as it directly impacts coastal geomorphology, ecological environments, geochemical cycling, and carbon sequestration dynamics. Therefore, determining accurately the erosion characteristics of estuarine deltaic sediments is essential for assessing and managing these evolving coastal systems. Therefore, this study conducted erosion experiments on undisturbed sediment samples collected from the subaqueous delta of the abandoned Yellow River Estuary (Old Qingshuigou Estuary) utilizing the UMCES-Gust Erosion Microcosm System. The aim was to reveal the spatial distribution characteristics of sediment erodibility and explore the erosion process, characteristics, and influencing factors of the surface sediments in the area. Erosion characteristics exhibited a spatial distribution pattern of increased erodibility in nearshore sediment and reduced erodibility in offshore sediments. The critical erosion shear stress of surface sediments ranged from 0.2 to 0.68 N/m2, while the erosion rate increased linearly with an increase in erosion shear stress and reached a maximum value of 2.119 g/m2 s, suggesting that nearshore sediments exhibited strong erodibility. Furthermore, the erosion characteristics exhibited a strong correlation with the type of sediment. Silt exhibited surface erosion and Type I erosion (depth-limited erosion), whereas silty sand primarily underwent volume erosion and Type II erosion (steady-state erosion). Particle size characteristics played a crucial role in influencing erosion. Additionally, our results revealed that the effective particle size of sediment aggregates and the scale effect of turbulence were also important factors that affected sediment erosion characteristics. These findings not only enhance our understanding of the erosion characteristics of silty sediments but also provide valuable parameters for sediment transport models in large river deltas such as the Yellow River Delta, thus facilitating the release of buried organic carbon and heavy metals from estuaries.

Influence of Physical Activity and Cup Orientation on Metal Ion Release and Oxidative Stress in Metal-on-Metal and Ceramic-on-Metal Total Hip Arthroplasty.

Metal-on-metal (M-M) total hip arthroplasty (THA) has shown adverse reactions to metal debris, abnormal soft-tissue reactions, and high blood metal ion levels. This study aims to: (1) assess whether the toxicity of high levels of ions is related to altered oxidative stress and (2) evaluate tribological factors related to increased blood levels of chromium (Cr) and cobalt (Co) ions. A cross-sectional analytical descriptive study was conducted on 75 patients. A total of 25 underwent M-M THA, 25 ceramic-on-metal (C-M) THA, and 25 were on the THA waiting list. Ion metallic levels in blood, oxidative stress, physical activity, and implant position were compared. In the M-M group, Co and Cr levels were significantly higher than those found in the C-M group and the control group (p < 0.01). We found no differences in terms of oxidative stress between the groups. Also, we did not find a correlation between metal blood levels and oxidative stress indicators, the physical activity of the patients or the position of the implants between groups. The use of M-M bearing surfaces in THA raises the levels of metals in the blood without modifying oxidative stress regardless of the physical activity levels of the patients. Therefore, although patients with M-M bearings require close monitoring, it does not seem necessary to recommend the restriction of physical activity in patients with M-M or C-M arthroplasties.

FE Investigation of Design and Quality Control-Related Issues Contributing to Metal-On-Metal Hip Implant Failures

High levels of cobalt and chromium ions were detected in the bodies of multiple recipients of modular cobalt chrome molybdenum metal-on-metal hip implants, necessitating the revision of their implants. A forensic engineering investigation of provided discovery documents and existing literature regarding the design, manufacturing, and clinical testing of these modular hip implants was performed. The investigation revealed that the modular interfaces of the implant allowed for micromotion to induce mechanically assisted crevice corrosion at these surfaces. The debris from this corrosion resulted in the release of metal ions into the bodies of the users, forming pseudotumors and compromising the user’s health and wellbeing. The effect of this corrosion was enhanced by the galvanic couple that existed between the modular components of the implant. In addition, scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS) analysis identified silicon carbide (SiC) and aluminum oxide (AL2O3 ) particles left behind from polishing, which were embedded in the ball and liners. These particles accelerated the wear of the hip implant and further exacerbated the release of metal ions. The designers of future hip implants should take care in preventing the occurrence of the above-stated factors.

An all‐green cellulose acetate/corn cob composite membrane filter: A critical evaluation of its morphology and adsorption characteristics for dyes and heavy metals

AbstractIndustrial wastewater from various manufacturing sectors poses a significant environmental concern due to the release of dyes, heavy metals, and pollutants into natural water streams. Effective treatment of large volumes of industrial wastewater is crucial to mitigate this issue. Conventional industrial wastewater filtration systems often prove to be inefficient, necessitating the exploration of alternative and cost‐effective water filtration methods. In this study, we drew inspiration from the natural adsorption and purification properties of corncob to develop a novel green composite membrane filter. The composite membrane filters, named MCAPCB and MCATPCB, were formulated by incorporating powdered corncob (PCB) and alkali/hydrogen peroxide‐treated powdered corncob (TPCB) into cellulose acetate. The adsorption properties of the composite filters were evaluated using UV–Vis spectrophotometry for dye adsorption and inductively coupled plasma optical emission spectroscopy (ICP‐OES) and atomic absorption spectroscopy (AAS) for heavy metal adsorption. The results demonstrated that MCATPCB20, incorporating 20 wt% TPCB, exhibited remarkable performance in the removal of methylene blue dye, with an adsorption efficiency of 97.46%. In comparison, MCAPCB20, incorporating 20 wt% PCB, achieved a dye adsorption efficiency of 80.15%. Moreover, MCATPCB20 displayed exceptional heavy metal removal capabilities, effectively rejecting 98% and 95% of cadmium and lead, respectively, from water samples containing 1 ppm of each metal. The composite filter membranes containing 20 wt% TPCB exhibited superior adsorption efficiency, flexibility, and stability. This enhanced performance can be attributed to the higher carboxyl content in TPCB, achieved through alkali treatment, which significantly increased the adsorption capacity of MCATPCB20. Characterization studies employing XRD, SEM, contact angle, BET, ICP‐OES, and UV measurements further supported the efficacy of MCATPCB as an effective filter system for water purification.

MRI-visualized PTT/CDT for breast cancer ablation and distant metastasis prevention

Chemodynamic therapy (CDT), which uses metal ions to covert endogenous hydrogen peroxide into highly reactive hydroxyl radicals, is an newly-developing strategy for cancer therapy. However, poor drug delivery efficiency and restricted catalytic performance hinder the therapeutic potential of CDT. Herein, we constructed an in situ injectable hydrogel incorporating Fe/Mn-polydopamine nanoparticles and the ferroptosis inducer piperazine erastin (PE) (FMPEG) for mediating tumor-specific magnetic resonance imaging-visualized photothermal therapy (PTT)/CDT. Upon exposure to near-infrared light irradiation, FMPEG treatment exerted a PTT effect, which further accelerated the drug release behavior from FMP nanoparticles in response to the acidic tumor microenvironment. The released metal ions and PE enhanced the CDT effect at the tumor site. Furthermore, a long-term antitumor effect was obtained via the immunostimulatory effect of CDT/PTT by producing tumor-associated antigens. These findings, along with the unique advantages of injectable hydrogels in immune activation, prove the great potential of FMPEG administration as an efficient strategy for the clinical prevention of distant tumor metastasis of breast cancer.

In situ, high-resolution evidence for the release of heavy metals from lake sediments during ice-covered and free periods

Heavy metal dynamics at the sediment-water interface (SWI) has attracted plenty of attention due to their meticulous depiction for metal sorption-release processes. However, little is known about their concentration, migration and release characteristics underneath the ice, especially at the millimeter scale. Here we investigated dynamics of labile As, Cd, Cu, Mn, Pb and Zn by the diffusive gradients in thin-films (DGT) technique during ice-covered and ice-free periods in the Lake Xingkai basin. The concentrations of metals were relatively high at the SWI and ranged for As: 0.001~13.42 μg L−1, Cd: 0.01~0.45 μg L−1, Cu: 0.001~2.75 μg L−1, Mn: 5.31~2958.29 μg L−1, Pb: 0.06~1.43 μg L−1, and Zn: 2.92~112.96 μg L−1. Particularly, concentration of Mn was extremely higher than other studies, possibly due to diagenetic process. Labile concentrations of heavy metals in January were significantly lower than those in May, suggesting that elevated temperatures lead to the release of heavy metals from the sediment to the overlying water. Based on the Fick’s first law, the diffusive fluxes as a source of Mn (413.82-1163.25 mg·m-2·d-1) and As (3.53 -8.12 mg·m-2·d-1) indicated that heavy metals were released from sediments to the overlying water. While the diffusive fluxes as a sink of Zn (-1.80-(-2.36) mg·m-2·d-1) and Pb (-0.02-(-0.46) mg·m-2·d-1) to sediments. Redundancy Analysis (RDA) revealed that the main factors influencing the heavy metal migration were dissolved oxygen (45.6% of total explanation, P=0.01) in January, and water temperature (52.9%, P=0.006) in May. This study extends theoretical scope for understanding metal migration and release process, and provides valuable suggestions for lake management during the freezing period.

Activated sodium bentonite as an adsorbent for efficient removal of hexavalent chromium: Statistical optimization using Box–Behnken design

AbstractAt present, developing countries, including Ethiopia, are undergoing a phase of industrial transformation. As a result, there has been a significant rise in the presence of harmful pollutants in groundwater. The release of deleterious heavy metals, such as Cr (VI), into the surrounding ecosystem is a result of various industrial operations. The present investigation utilized activated sodium bentonite clay as an adsorbent agent to facilitate the elimination of Cr (VI). The clay was subjected to acidification and thermal modification techniques to enhance its adsorption capacity. The investigation involved an examination of the particular surface area, capacity for cation exchange, crystalline properties, functional groups on the surface, and structural morphology. The methylene blue test method was employed to ascertain the maximum specific surface area and cation exchange capacity of the adsorbent, which were found to be 512 m2/g and 65.5 meq/100 g, respectively. The clay mineral composition was analyzed using X‐ray diffraction, which indicated that the primary constituent was montmorillonite. The presence of impurities such as quartz, feldspar, muscovite, cristobalite, and hematite was also detected. The study employed response surface methodology, Box–Benkhen design (RSM‐BBD) to investigate the impact of operational parameters, including agitation time, initial Cr (VI) concentration, and adsorbent dosage. Under the optimal conditions, a removal efficiency of 98.05% was achieved for Cr (VI) for a contact duration of 120 min, a dosage of 3.913 g/L, and an initial concentration of 50 mg/L. The sodium bentonite clay that was activated demonstrated a maximum capacity for adsorption of 22.72 mg/g in regards to the adsorption of Cr (VI). The experimental data were best fitted by the Langmuir isotherm, which exhibited a correlation coefficient of 0.9699. The adsorption kinetics were assessed and determined to adhere to a pseudo‐second‐order pattern, exhibiting a coefficient of determination (R2) value of 0.999. Furthermore, the activated sodium bentonite clay demonstrated remarkable potential for repeated utilization in the adsorption of Cr (VI) ions in aqueous solutions.

Synergistic antibacterial mechanism of silver-copper bimetallic nanoparticles.

The excessive use of antibiotics in clinical settings has resulted in the rapid expansion, evolution, and development of bacterial and microorganism resistance. It causes a significant challenge to the medical community. Therefore, it is important to develop new antibacterial materials that could replace traditional antibiotics. With the advancements in nanotechnology, it has become evident that metallic and metal oxide nanoparticles (MeO NPs) exhibit stronger antibacterial properties than their bulk and micron-sized counterparts. The antibacterial properties of silver nanoparticles (Ag NPs) and copper nanoparticles (Cu NPs) have been extensively studied, including the release of metal ions, oxidative stress responses, damages to cell integrity, and immunostimulatory effects. However, it is crucial to consider the potential cytotoxicity and genotoxicity of Ag NPs and Cu NPs. Numerous experimental studies have demonstrated that bimetallic nanoparticles (BNPs) composed of Ag NPs and Cu NPs exhibit strong antibacterial effects while maintaining low cytotoxicity. Bimetallic nanoparticles offer an effective means to mitigate the genotoxicity associated with individual nanoparticles while considerably enhancing their antibacterial efficacy. In this paper, we presented on various synthesis methods for Ag-Cu NPs, emphasizing their synergistic effects, processes of reactive oxygen species (ROS) generation, photocatalytic properties, antibacterial mechanisms, and the factors influencing their performance. These materials have the potential to enhance efficacy, reduce toxicity, and find broader applications in combating antibiotic resistance while promoting public health.

Effects of chloride on corrosion scale compositions and heavy metal release in drinking water distribution systems

Variations in water chemistry may lead to the release of harmful heavy metals in drinking water distribution systems (DWDSs). In this study, the effects of chloride on the release of heavy metals such as Fe, Mn, As, Cr, Mo, V, Sr, and Co were examined using steel and cast iron pipe loops. After chloride was added, the relative contents of goethite (α-FeOOH), lepidocrocite (γ-FeOOH), and siderite (FeCO3) in pipe scales increased, but the contents of magnetite (Fe3O4) decreased. The most prevalent compounds were α-FeOOH and γ-FeOOH. When the chloride levels were increased, the effluent concentrations of Fe, Mn, As, Cr, Mo, V, Sr, and Co significantly increased. These heavy metals were released presumably because of the destabilization and dissolution of corrosion scales induced by chloride and adsorption site competition. Strong positive correlations were also observed between Fe&Mn, Fe/Mn&As, Fe/Mn&Cr, Fe/Mn&Mo, Fe/Mn&V, Fe/Mn&Sr, and Fe/Mn&Co, indicating the co-release of Fe, Mn, and other metals. This study may be helpful for the potential strategies on avoidance of heavy metal release and improvement of water supply security.

NEW HIGH-THROUGHPUT METHODS FOR ANTIBACTERIAL VALIDATION OF METALLIC THIN FILMS: DIFFERENT METALS FOR DIFFERENT MICROBIAL COMMUNITIES

Prosthetic joint infections represent complications connected to the implantation of biomedical devices, they have high incidence, interfere with osseointegration, and lead to a high societal burden. The microbial biofilm, which is a complex structure of microbial cells firmly attached to a surface, is one of the main issues causing infections. Biofilm- forming bacteria are acquiring more and more resistances to common clinical treatments due to the abuse of antibiotics administration. Therefore, there is increasing need to develop alternative methods exerting antibacterial activities against multidrug-resistant biofilm-forming bacteria. In this context, metal-based coatings with antimicrobial activities have been investigated and are currently used in the clinical practice. However, traditional coatings exhibit some drawbacks related to the insufficient adhesion to the substrate, scarce uniformity and scarce control over the toxic metal release reducing their efficacy. Here, we propose the use of antimicrobial silver-based nanostructured thin films to discourage bacterial infections. Coatings are obtained by Ionized Jet Deposition, a plasma-assisted technique that permits to manufacture films of submicrometric thickness having a nanostructured surface texture, allow tuning silver release, and avoid delamination. To mitigate interference with osseointegration, here silver composites with bone apatite and hydroxyapatite were explored. The antibacterial efficacy of silver films was tested in vitro against gram- positive and gram-negative species to determine the optimal coatings characteristics by assessing reduction of bacterial viability, adhesion to substrate, and biofilm formation. Efficacy was tested in an in vivo rabbit model, using a multidrug-resistant strain of Staphylococcus aureus showing significant reduction of the bacterial load on the silver prosthesis both when coated with the metal only (&gt;99% reduction) and when in combination with bone apatite (&gt;86% reduction). These studies indicate that IJD films are highly tunable and can be a promising route to overcome the main challenges in orthopedic prostheses.

Current and promising applications of MOF composites in the healing of diabetes wounds.

Diabetes mellitus is an exponentially growing chronic metabolic disease identified by prolonged hyperglycemia that leads to a plethora of health problems. It is well established that the skin of diabetic patients is more prone to injury, and hence, wound healing is an utmost critical restorative process for injured skin and other tissues. Diabetes patients have problems with wound healing at all stages, which ultimately results in delays in the healing process. Therefore, it is vital to find new medications or techniques to hasten the healing of wounds. Metal-organic frameworks (MOFs), an assorted class of porous hybrid materials comprising metal ions coordinated to organic ligands, can display great potential in accelerating diabetic wound healing due to their good physicochemical properties. The release of metal ions during the degradation of MOFs can promote the differentiation of fibroblasts into myofibroblasts and subsequently angiogenesis. Secondly, similar to enzyme-like active substances, they can eliminate reactive oxygen species (ROS) overproduction (secondary to the bio-load of wound bacteria), which is conducive to accelerating diabetic wound healing. Subsequently, MOFs can support the slow release of drugs (molecular or gas therapeutics) in diabetic wounds and promote wound healing by regulating pathological signaling pathways in the wound microenvironment or inhibiting the expression of inflammatory factors. In addition, the combination of photodynamic and photothermal therapies using photo-stimulated porphyrin-based MOF nanosystems has brought up a new idea for treating complicated diabetic wound microenvironments. In this review, recent advances affecting diabetic wound healing, current means of rapid diabetic wound healing, and the limitations of traditional approaches are discussed. Further, the diabetic wound healing applications of MOFs have been discussed followed by the future challenges and directions of MOF materials in diabetic wound healing.

Recent progress and challenges of MOF-based nanocomposites in bioimaging, biosensing and biocarriers for drug delivery.

Metal-organic frameworks (MOFs), a burgeoning class of coordination polymers, have garnered significant attention due to their outstanding structure, porosity, and stability. They have been extensively studied in catalysis, energy storage, water harvesting, selective gas separation, and electrochemical applications. Recent advancements in post-synthetic strategies, surface functionality, and biocompatibility have expanded the application scope of MOFs, particularly in various biomedical fields. Herein, we review MOF-based nanomaterials bioimaging nanoplatforms in magnetic resonance imaging, computed tomography, and fluorescence imaging. MOFs serve as the foundation for biosensors, demonstrating efficiency in sensing H2O2, tumor biomarkers, microRNA, and living cancer cells. MOF-based carriers are well designed in drug delivery systems and anticancer treatment therapies. Additionally, we examine the challenges and prospects of MOFs in surface modification, release of metal ions, and interaction with intracellular components, as well as their toxicity and long-term effects.

Antimicrobial zeolites and metal-organic frameworks.

The current surge in antibiotic resistance and the emergence of pandemics have created an urgent need for novel antimicrobial strategies. The controlled release of antimicrobial active principles remains the most viable strategy to date, and transition metal ions currently represent the main alternative to antibiotics. In this review, we explore the potential of two types of materials, zeolites and metal-organic frameworks (MOFs), for the controlled release of antimicrobial active principles, notably transition metal ions. These materials have unique crystalline microporous structures that act as reservoirs, enabling sustained bactericidal effects in various applications such as coatings, packaging, and medical devices. However, there are currently no convenient and standardised methods for evaluating their metal ion release and antimicrobial efficacy. This work discusses analytical techniques and the proposed mechanisms of action while highlighting recent advances in film, membrane, and coating technologies. By addressing the current limitations, microporous materials can revolutionise antimicrobial approaches, offering enhanced effectiveness and long-term sustainability.

Advances in the study of metal-organic frameworks and their biomolecule composites for osteoporosis therapeutic applications.

With the population aging, osteoporosis (OP) is becoming more and more common, seriously affecting patients' quality of life and their families, and how to prevent and treat osteoporosis has become a hot topic. However, the current conventional method of treating OP is oral anti-osteoporosis medication, which has drawbacks such as first-pass elimination and gastrointestinal adverse effects. At the same time, osteoporosis can lead to microbial infections and the need to promote angiogenesis for bone healing, among other needs that often cannot be met with conventional treatments, and there is a risk of resistance to oral antibiotics for microbial infections. Metal-organic frameworks (MOFs) having a high specific surface area, high porosity, controlled degradation, and variable composition; they can not only be used as a carrier to control drug release, but can also play multiple roles in the treatment of OP and microbial infections by releasing metal ions, etc., so they have inherent advantages for OP, which is a disease that requires long-term treatment. Therefore, this paper reviews the research progress of MOFs and their biomacromolecular composites in therapeutic applications for osteoporosis, categorized by MOF type, and briefly describes the mechanism of osteoporosis, and different synthesis methods of MOFs and MOF-based composites, and finally presents the main existing problems and future perspectives, aiming to make MOFs more helpful for OP treatment.

Thermodynamics of the obtained ion exchanges for the sorption of various ions in environmental wastewaters

This study focuses on investigating the thermodynamic parameters of an ion exchanger synthesized using chlorinated polypropylene with polyethylene polyamines. The ion exchanger, derived from chlorinated polypropylene, demonstrates full compliance with chemical resistance standards. The research involves the examination of isotherms governing the sorption process of Cu(II) and Ni(II) ions by the ion exchanger. These isotherms adhere to the Freundlich model, offering insights into the ion-exchange behavior of the material. Additionally, the study delves into the dynamic exchange capacity and desorption characteristics of the resulting ion exchanger in a granular state. These parameters are crucial for understanding the material's performance in practical applications, shedding light on its ability to efficiently exchange and release metal ions. By comprehensively analyzing the thermodynamic aspects and sorption behavior of the synthesized ion exchanger, this work contributes valuable knowledge to the field of ion exchange materials. The findings offer a basis for further optimization and application of such materials in various industrial processes, particularly in the removal of heavy metal ions from aqueous solutions.

Evaluation of the antibacterial properties of commonly used clays from deposits in central and southern Asia

Abstract One potential solution to the rising threat of antibacterial drug resistance is the application of therapeutic clays to treat wound infections. Clays with antibacterial activity have been identified from a range of sources with their antibacterial properties often attributed to the release of toxic metal ions such as Fe(II) and Al(III). Here, clays from Afghanistan, Azerbaijan and Bangladesh that are utilized for washing and healing purposes were examined. Their antibacterial activities were assessed in suspension and as aqueous leachates against representative Gram-negative, Escherichia coli, and Gram-positive, Bacillus subtilis, bacteria. The majority of the clays conferred no deleterious effect and, in fact, tended to promote bacterial growth, likely as a result of released organic and inorganic nutrients. However, one of the clays, obtained from the Dhaka region of Bangladesh, displayed significant bactericidal activity against E. coli and B. subtilis as a clay suspension but not as an aqueous leachate. Further experiments confirmed that contact between clay and the bacteria was necessary for most of the antibacterial effects. Detailed analysis of bulk and &lt;2 μm clay fraction mineralogy and geochemistry revealed no single defining parameter or mineral component that could be used to easily distinguish natural clays with antibacterial properties from those without. Overall, the results suggest a mechanism of antibacterial action of the Dhaka clay that arises from acidic conditions, likely enabled by the absence of calcite in the bulk clay, metal release, the presence of interstratified chlorite-smectite, and direct clay–bacteria interactions.

Compositional and surface changes of retrieved stainless-steel hardware and its effects on surrounding soft tissues: A prospective study.

To evaluate the surface, compositional, and histological changes in the overlying soft tissues of retrieved stainless-steel mini-plates and screws used for rigid internal fixation in the maxillofacial skeleton. A prospective study was conducted comprising 60 patients who sustained maxillofacial trauma and underwent ORIF in our unit previously and who required hardware retrieval in the post-operative phase. The retrieved hardware was evaluated for surface and compositional changes with the help of a scanning electron microscope for surface roughness and corrosion changes. Energy-dispersive X-ray study was done to know the composition and metal release from the hardware. The data obtained from these results were compared with a control unused and a sterile stainless-steel mini-plate and screw. The effects of the corrosion changes of this hardware on the adjacent soft tissues were evaluated histologically to assess the cellular changes of the soft tissue cover overlying the stainless-steel mini-plates and screws. A total of 96 stainless-steel mini-plates and 380 stainless-steel screws were retrieved from 60 patients. The control plate was smooth without any surface and corrosion defects, while the retrieved mini-plates irrespective of the reason for removal have shown surface roughness. Fe and Ni ions were found to be significantly reduced in the retrieved mini-plates. The presence of CrC in the retrieved plates indicates corrosion, which was seen only in hardware retrieved from symptomatic patients. The histological study revealed chronic inflammatory cell infiltrate with hyalinized connective tissue in all the samples irrespective of the reason for the removal of the plate. Stainless-steel mini-plates and screws act as a potent foreign body material and initiate a localized inflammatory reaction due to its corrosive products with longer duration of stay. Hence, the authors advocate the overall shift in the use of stainless-steel hardware to titanium hardware for ORIF.

Flame emission spectroscopy of single droplet micro explosions.

Nanoparticles exhibit superior physical and chemical properties, making them highly desirable for various applications. Flame spray pyrolysis (FSP) is a versatile technique for synthesizing size and composition-controlled metal oxide/sulfide nanoparticles through a gas-phase reaction. To understand the fundamental mechanisms governing nanoparticle formation in FSP, simplified single-droplet experiments have proven to unravel the physicochemical mechanisms of liquid metal precursor combustions. This work introduces a novel method using flame emission spectroscopy and high-speed imaging to analyze combustion species and metal release during metalorganic single droplet combustions, with the example of the 2-ethylhexanoci acid (EHA)-tetrahydrothiophene (THT)-mesitylcopper (MiCu) precursor system. The method enables the tracing of precursor components released from droplet into the flame by spatial and temporal resolved emission tracking from combustion species (OH*, CH*, C2*, CS*, CS2*) and atomic spectral lines (Cu I). The tracking of metal emission enables the direct observation of the particle formation route, offering novel insights into the metalorganic precursor combustions. The findings of this work show a direct correlation between micro-explosions and nanoparticle formation through the gas-to-particle route. The release of copper emissions is observed with the micro-explosion event, marking the micro-explosions as the critical mechanism for the metal release and subsequent nanoparticle formation during the combustion process. The results indicate a metalorganic viscous shell formation (THT + MiCu) leading to the micro explosion. The EHA/THT ratio significantly affects the combustion behavior. Lower ratios lead to a gradual copper release before the micro explosion; higher ratios shorten the copper release and delay the micro explosion - the highest ratio results in two distinct burning stages.

Biomedical devices surface functionalization through superfinishing processes to improve tribocorrosion

Permanent prosthesis surface conditions play a key role on the implants overall mechanical performance. Furthermore, the increased number of arthroplasty surgery represents a reason for the necessity of higher quality standards for the biomedical devices. Employing and optimizing severe plastic deformation processes represents a way to obtain implants with higher performance, therefore this work aims, through the application of burnishing process, to combine innovative machining finishing operations coupled with environmentally friendly cooling lubricant techniques to improve the surface integrity and the tribocorrosion resistance of biomedical devices in order to increase their quality, durability and reliability. Another phenomenon taken into account is the tribological behavior that could generates an irreversible transformation of the materials and the release of particles and metal ions in toxic concentrations in the biological environment in which the devices are implanted. One of the most used materials for permanent prosthetic implants is the Ti6Al4V alloy but its tribological behavior is still challenging for the application. In this work Ti6Al4V bars have undergone machining with semi-finishing parameters and burnishing processes, then the effects of sole machining and its combination with burnishing on surface quality and specific wear rate (SWR) have been assessed with respect to as received surface conditions.