Carbon Dots Derived from Non-Biomass Waste: Methods, Applications, and Future Perspectives.

Carbon dots (CDs) are luminescent carbon nanoparticles with significant potential in analytical sensing, biomedicine, and energy regeneration due to their remarkable optical, physical, biological, and catalytic properties. In light of the enduring ecological impact of non-biomass waste that persists in the environment, efforts have been made toward converting non-biomass waste, such as ash, waste plastics, textiles, and papers into CDs. This review introduces non-biomass waste carbon sources and classifies them in accordance with the 2022 Australian National Waste Report. The synthesis approaches, including pre-treatment methods, and the properties of the CDs derived from non-biomass waste are comprehensively discussed. Subsequently, we summarize the diverse applications of CDs from non-biomass waste in sensing, information encryption, LEDs, solar cells, and plant growth promotion. In the final section, we delve into the future challenges and perspectives of CDs derived from non-biomass waste, shedding light on the exciting possibilities in this emerging area of research.

Structure and Dynamics of Aqueous 2-Aminothiazole/NaCl Electrolytes at Electrified Interfaces.

A computational study was performed to investigate the dynamics of aqueous electrolytes containing organic corrosion inhibitors near electrified interfaces by using the constant-charge model in classical molecular dynamics simulations. The results showed that when inhibitors form films at the interface, the surface charge of the electrode causes displacement of the molecules, referred to as electroporation. The hydrophobicity of the inhibitor molecules affects both the stability of the films and their recovery time. This study highlights the value of computational investigations of the dynamics within inhibitor films as a complementary approach to the traditional focus on inhibitor-substrate interactions, leading to deeper insights into the mechanisms of corrosion inhibition mechanisms.

Bio-corrosion in concrete sewer systems: Mechanisms and mitigation strategies.

The deterioration of concrete sewer structures due to bio-corrosion presents critical and escalating challenges from structural, economic and environmental perspectives. Despite decades of research, this issue remains inadequately addressed, resulting in billions of dollars in maintenance costs and a shortened service life for sewer infrastructure worldwide. This challenge is exacerbated by the absence of standardized test methods and universally accepted mitigation strategies, leaving industries and stakeholders confronting an increasingly pressing problem. This paper aims to bridge this knowledge gap by providing a comprehensive review of the complex mechanisms of bio-corrosion, focusing on the formation and accumulation of hydrogen sulfide, its conversion into sulfuric acid and the subsequent deterioration of concrete materials. The paper also explores various factors affecting bio-corrosion rates, including environmental conditions, concrete properties and wastewater characteristics. The paper further highlights existing corrosion test strategies, such as chemical tests, in-situ tests and microbial simulations tests along with their general analytical parameters. The conversion of hydrogen sulfide into sulfuric acid is a primary cause of concrete decay and its progression is influenced by environmental conditions, inherent concrete characteristics, and the composition of wastewater. Through illustrative case studies, the paper assesses the practical implications and efficacy of prevailing mitigation techniques. Coating materials provide a protective barrier against corrosive agents among the discussed techniques, while optimised concrete mix designs enhance the inherent resistance and durability of the concrete matrix. Finally, this review also outlines the future prospects and challenges in bio-corrosion research with an aim to promote the creation of more resilient and cost-efficient materials for sewer systems.

Advanced flexible transvaginal mesh with high visibility under computerized tomography (CT) scan.

Pelvic floor disorders, including pelvic organ prolapse (POP) and stress urinary incontinence (SUI), are serious and very common. Surgery is commonly undertaken to restore the strength of the vaginal wall using transvaginal surgical mesh (TVM). However, up to 15% of TVM implants result in long-term complications, including pain, recurrent symptoms, and infection.Clinical Relevance- In this study, a new bioengineered TVM has been developed to address these issues. The TVM is visible using noninvasive imaging techniques such as computed tomography (CT); it has a highly similar structural profile to human tissue and potential to reduce pain and inflammation. These combined technological advances have the potential to revolutionize women's health.

A Green Synthesis Route to Derive Carbon Quantum Dots for Bioimaging Cancer Cells.

Carbon quantum dots (CQDs) are known for their biocompatibility and versatile applications in the biomedical sector. These CQDs retain high solubility, robust chemical inertness, facile modification, and good resistance to photobleaching, which makes them ideal for cell bioimaging. Many fabrication processes produce CQDs, but most require expensive equipment, toxic chemicals, and a long processing time. This study developed a facile and rapid toasting method to prepare CQDs using various slices of bread as precursors without any additional chemicals. This fast and cost-effective toasting method could produce CQDs within 2 h, compared with the 10 h process in the commonly used hydrothermal method. The CQDs derived from the toasting method could be used to bioimage two types of colon cancer cells, namely, CT-26 and HT-29, derived from mice and humans, respectively. Significantly, these CQDs from the rapid toasting method produced equally bright images as CQDs derived from the hydrothermal method.

Aerosol exchange between pressure-equilibrium rooms induced by door motion and human movement.

It is now widely recognised that aerosol transport is major vector for transmission of diseases such as COVID-19, and quantification of aerosol transport in the built environment is critical to risk analysis and management. Understanding the effects of door motion and human movement on the dispersion of virus-laden aerosols under pressure-equilibrium conditions is of great significance to the evaluation of infection risks and development of mitigation strategies. This study uses novel numerical simulation techniques to quantify the impact of these motions upon aerosol transport and provides valuable insights into the wake dynamics of swinging doors and human movement. The results show that the wake flow of an opening swinging door delays aerosol escape, while that of a person walking out entrains aerosol out of the room. Aerosol escape caused by door motion mainly happens during the closing sequence which pushes the aerosols out. Parametric studies show that while an increased door swinging speed or human movement speed can enhance air exchange across the doorway, the cumulative aerosol exchange across the doorway is not clearly affected by the speeds.

Rapid and selective screening of organic peroxide explosives using acid-hydrolysis induced chemiluminescence.

Organic peroxide explosives (OPEs) are unstable, non-military, contemporary security threats often found in improvised explosive devices. Chemiluminescence (CL) can be used to detect OPEs, via radical formation consisting of peroxide moieties (-O-O-) under acidic conditions. However, selectivity for specific OPEs is hampered by the ubiquitous background of H2O2. Herein, we report the differentiation of hexamethylene triperoxide diamine (HMTD), triacetone triperoxide (TATP), and methyl ethyl ketone peroxide (MEKP) by specific flow injection analysis-CL (FIA-CL) signal profiles, after H2SO4 treatment. The radical degradation pathway of each structure, and its corresponding FIA-CL profile, was explored using mass spectrometry to reveal the rapid loss of -O-O- from TATP and HMTD structures, while MEKP formed CL signal-sustaining oligomers, as opposed to the immediate attenuation of H2O2. The CL response for OPEs in an aqueous media, measured via the described FIA-CL method, enabled ultra-trace limits of detection down to 0.40 µM for MEKP, 0.43 µM for HMTD, and 0.40 µM for TATP (combined linear range 1-83 µM with 95% confidence limit, n = 12). Expanded uncertainties of measurement (UM) of MEKP = ±0.98, HMTD = ±1.03, and TATP = ±1.1 (UM included probabilities of false positive and false negative as well as standard deviations of % recoveries and limit of detections of OPEs). Direct aqueous sample introduction via FIA-CL thus offers the prospect of rapid and selective screening of OPEs in security-heightened settings (e.g., airports), averting false positives from more ubiquitous H2O2.

Fast and Effective Removal of Congo Red by Doped ZnO Nanoparticles.

ZnO nanoparticles (NPs) show remarkable efficiency in removing various contaminants from aqueous systems. Doping ZnO NPs with a second metal element can dramatically change the physicochemical properties of the pristine nanoparticles. However, there have been limited reports on the absorption of doped ZnO NPs, especially comparing the performance of ZnO NPs with different doping elements. Herein, ZnO NPs were doped with three transitional metals (Co, Fe, and Mn) at a nominal 2 wt.%. The particle surface had a higher dopant concentration than the interior for all NPs, implying the migration of the dopants to the surface. Because doping atoms inhibited grain growth, the doped ZnO NPs had a small particle size and a large surface area. The adsorption performance followed the order of Fe-doped < undoped < Mn-doped < Co-doped ZnO. Co-doped ZnO had an increased surface area and less tendency to agglomerate in an aqueous solution, showing the best adsorption performance. The adsorption of Congo red (CR) on Co-doped ZnO followed the pseudo-second-order model and the Langmuir isotherm. The adsorption process was spontaneous through monolayer chemisorption, and the maximum adsorption capacity was 230 mg/g. Finally, the Co-doped ZnO was successfully incorporated into an alginate membrane by electrospinning. The membrane demonstrated excellent adsorption performance and had great potential as an innovative and low-cost adsorbent (inexpensive raw materials and simple processing) for wastewater purification.

Remediation of groundwater contaminated with dye using carbon dots technology: Ecotoxicological and microbial community responses.

Groundwater pollution poses a serious threat to the main source of clean water globally. Nanoparticles have the potential for remediation of polluted aquifers; however, environmental safety concerns associated with in situ deployments of such technology include potential detrimental effects on microorganisms in terms of toxicity and functional disruptions. In this work, we evaluated a new and ecofriendly approach using carbon dots (CDs) as Fenton-like catalysts to catalyse the degradation of dye-containing groundwater samples. This investigation aimed at evaluating the efficacy of a novel remediation technology in terms of dye degradation and toxicity reduction while assessing its impacts on aquatic microorganisms. Uncontaminated Australian groundwater samples were spiked with methylene blue and incubated in the dark, at 18 °C, under slow agitation, using CDs at 0.5 mg mL-1 and H2O2 at 73.5 mM for 25 h. The dye degradation rate was determined as well as the toxicity of the treated solutions using the Microtox® bioassay. Further, to determine the changes in the groundwater microbial community, 16 S rRNA sequencing was used and evenness and diversity indices were analysed using Pielou's evenness and Simpson index, respectively. This study revealed that dye-containing groundwater were effectively treated by CDs showing a degradation rate of 78-82% and a significant 4-fold reduction in the toxicity. Characterisation of the groundwater microbiota revealed a predominance of at least 60% Proteobacteria phylum in all samples where diversity and evenness were maintained throughout the remediation process. The results showed that CDs could be an efficient approach to treat polluted groundwater and potentially have minimum impact on the environmental microbiome.

Gallium-Strontium Phosphate Conversion Coatings for Promoting Infection Prevention and Biocompatibility of Magnesium for Orthopedic Applications.

Device-associated infections remain a clinical challenge. The common strategies to prevent bacterial infection are either toxic to healthy mammalian cells and tissue or involve high doses of antibiotics that can prompt long-term negative consequences. An antibiotic-free coating strategy to suppress bacterial growth is presented herein, which concurrently promotes bone cell growth and moderates the dissolution kinetics of resorbable magnesium (Mg) biomaterials. Pure Mg as a model biodegradable material was coated with gallium-doped strontium-phosphate through a chemical conversion process. Gallium was distributed in a gradual manner throughout the strontium-phosphate coating, with a compact structure and a gallium-rich surface. It was demonstrated that the coating protected the underlying Mg parts from significant degradation in minimal essential media at physiological conditions over 9 days. In terms of bacteria culture, the liberated gallium ions from the coatings upon Mg specimens, even though in minute quantities, inhibited the growth of Gram-positiveStaphylococcus aureus, Gram-negative Escherichia coli, andPseudomonas aeruginosa ─ key pathogens causing infection and early failure of the surgical implantations in orthopedics and trauma. More importantly, the gallium dopants displayed minimal interferences with the strontium-phosphate-based coating which boosted osteoblasts and undermined osteoclasts in in vitro co-cultures. This work provides a new strategy to prevent bacterial infection and control the degradation behavior of Mg-based orthopedic implants, while preserving osteogenic features of the devices.

Hazard profiling of a combinatorial library of zinc oxide nanoparticles: Ameliorating light and dark toxicity through surface passivation.

Zinc oxide (ZnO) is one of the high-volume production nanoparticles (NPs) currently used in a wide range of consumer and industrial goods. The inevitable seepage into environmental matrices and the photoactive nature of ZnO NPs warrants hazard profiling under environmentally related conditions. In this paper, the influence of simulated solar light (SSL) on dissolution behaviour and phototoxicity of ZnO NPs was studied using a combinatorial library of ZnO NPs with different sizes, surface coatings, dopant chemistry, and aspect ratios in a fish cell line (BF2) and zebrafish embryos. Generally, the cytotoxicity and embryo mortality increased when exposed concomitantly to SSL and ZnO NPs. The increase in toxic potential of ZnO NPs during SSL exposure concurred with release of Zn ions and ROS generation. Surface modification of NPs with poly(methacrylic acid) (PMAA), silica or serum coating decreased toxicity and ZnO with serum coating was the only NP that had no significant effect on any of the cytotoxicity parameters when tested under both dark and SSL conditions. Results from our study show that exposure to light could increase the toxic potential of ZnO NPs to environmental lifeforms and mitigation of ZnO NP toxicity is possible through modifying the surface chemistry.

Quorum sensing inhibitors applications: A new prospect for mitigation of microbiologically influenced corrosion.

Quorum sensing (QS) is a process of bacterial communication that involves the use of biochemical signals and adjusts the expression of specific genes as a response to the bacterial cell density within an environment. This process is employed by both Gram-positive and Gram-negative bacteria to regulate different physiological functions. In both cases, QS involves production, detection and responses to signalling chemicals, termed auto-inducers. Expression of virulence factors and formation of biofilms are the typical processes controlled by QS, which, therefore, inspires the exploration of QS as a plausible solution to mitigating the increasing microbial resistance to antibiotics. QS inhibitors (QSIs) from different origins have been recognised as a promising solution to biofilm related challenges in a large variety of applications. Though QSIs have demonstrated some strength in tackling biofouling, a key focus in the literature on QSIs based strategies has been to control microbially influenced corrosion. This article reviews the principles of QS, its mechanistic roles in biofilm formation and the feasibility of QSIs to mitigate biofilm related challenges in a number of commercial applications. The potential of QSIs in microbially influenced corrosion for future applications is also discussed.

Carbon Dot Therapeutic Platforms: Administration, Distribution, Metabolism, Excretion, Toxicity, and Therapeutic Potential.

Ultrasmall nanoparticles are often grouped under the broad umbrella term of "nanoparticles" when reported in the literature. However, for biomedical applications, their small sizes give them intimate interactions with biological species and endow them with unique functional physiochemical properties. Carbon quantum dots (CQDs) are an emerging class of ultrasmall nanoparticles which have demonstrated considerable biocompatibility and have been employed as potent theragnostic platforms. These particles find application for increasing drug solubility and targeting, along with facilitating the passage of drugs across impermeable membranes (i.e., blood brain barrier). Further functionality can be triggered by various environmental conditions or external stimuli (i.e., pH, temperature, near Infrared (NIR) light, ultrasound), and their intrinsic fluorescence is valuable for diagnostic applications. The focus of this review is to shed light on the therapeutic potential of CQDs and identify how they travel through the body, reach their site of action, administer therapeutic effect, and are excreted. Investigation into their toxicity and compatibility with larger nanoparticle carriers is also examined. The future of CQDs for theragnostic applications is promising due to their multifunctional attributes and documented biocompatibility. As nanomaterial platforms become more commonplace in clinical treatments, the commercialization of CQD therapeutics is anticipated.

A spatiotemporally resolved infection risk model for airborne transmission of COVID-19 variants in indoor spaces.

The classic Wells-Riley model is widely used for estimation of the transmission risk of airborne pathogens in indoor spaces. However, the predictive capability of this zero-dimensional model is limited as it does not resolve the highly heterogeneous spatiotemporal distribution of airborne pathogens, and the infection risk is poorly quantified for many pathogens. In this study we address these shortcomings by developing a novel spatiotemporally resolved Wells-Riley model for prediction of the transmission risk of different COVID-19 variants in indoor environments. This modelling framework properly accounts for airborne infection risk by incorporating the latest clinical data regarding viral shedding by COVID-19 patients and SARS-CoV-2 infecting human cells. The spatiotemporal distribution of airborne pathogens is determined via computational fluid dynamics (CFD) simulations of airflow and aerosol transport, leading to an integrated model of infection risk associated with the exposure to SARS-CoV-2, which can produce quantitative 3D infection risk map for a specific SARS-CoV-2 variant in a given indoor space. Application of this model to airborne COVID-19 transmission within a hospital ward demonstrates the impact of different virus variants and respiratory PPE upon transmission risk. With the emergence of highly contagious SARS-CoV-2 variants such as the Delta and Omicron strains, respiratory PPE alone may not provide effective protection. These findings suggest a combination of optimal ventilation and respiratory PPE must be developed to effectively control the transmission of COVID-19 in healthcare settings and indoor spaces in general. This generalised risk estimation framework has the flexibility to incorporate further clinical data as such becomes available, and can be readily applied to consider a wide range of factors that impact transmission risk, including location and movement of infectious persons, virus variant and stage of infection, level of PPE and vaccination of infectious and susceptible individuals, impacts of coughing, sneezing, talking and breathing, and natural and mechanised ventilation and filtration.

Fluorescent Magnesium Hydroxide Nanosheet Bandages with Tailored Properties for Biocompatible Antimicrobial Wound Dressings and pH Monitoring.

Magnesium hydroxide (Mg(OH)2) is hailed as a cheap and biocompatible material with antimicrobial potential; however, research aimed at instilling additional properties and functionality to this material is scarce. In this work, we synthesized novel, fluorescent magnesium hydroxide nanosheets (Mg(OH)2-NS) with a morphology that closely resembles that of graphene oxide. These multifunctional nanosheets were employed as a potent antimicrobial agent against several medically relevant bacterial and fungal species, particularly on solid surfaces. Their strong fluorescence signature correlates to their hydroxide makeup and can therefore be used to assess their degradation and functional antimicrobial capacity. Furthermore, their pH-responsive change in fluorescence can potentially act as a pH probe for wound acidification, which is characteristic of healthy wound healing. These fluorescent antimicrobial nanosheets were stably integrated into biocompatible electrospun fibers and agarose gels to add functionality to the material. This reinforces the suitability of the material to be used as antimicrobial bandages and gels. The biocompatibility of the Mg(OH)2-NS for topical medical applications was supported by its noncytotoxic action on human keratinocyte (HaCaT) cells.

Effect of inhalation on oropharynx collapse via flow visualisation.

Computational fluid dynamics (CFD) modelling has made significant contributions to the analysis and treatment of obstructive sleep apnoea (OSA). While several investigations have considered the flow field within the airway and its effect on airway collapse, the effect of breathing on the pharynx region is still poorly understood. We address this gap via a combined experimental and numerical study of the flow field within the pharynx and its impacts upon airway collapse. Two 3D experimental models of the upper airway were constructed based upon computerised tomography scans of a specific patient diagnosed with severe OSA; (i) a transparent, rigid model for flow visualisation, and (ii) a semi-flexible model for understanding the effect of flow on pharynx collapse. Validated simulation results for this geometry indicate that during inhalation, negative pressure (with respect to atmospheric pressure) caused by vortices drives significant narrowing of the pharynx. This narrowing is strongly dependent upon whether inhalation occurs through the nostrils. Thus, the methodology presented here can be used to improve OSA treatment by improving the design methodology for personalised, mandibular advancement splints (MAS) that minimise OSA during sleep.

Experimental and DFT studies of gadolinium decorated graphene oxide materials for their redox properties and as a corrosion inhibition barrier layer on Mg AZ13 alloy in a 3.5% NaCl environment.

Magnesium alloys are broadly used worldwide in various applications; however, the serious disadvantage of these alloys are subject to corrosion and in aggressive/corrosive environments. A coating containing gadolinium-based composite materials can increase the alloy protection by strong electron transfer between the host alloy and the lanthanide-containing protective layer. This investigation aims to develop a Gd nanorod functionalised graphene oxide material as a corrosion inhibition barrier on the Mg alloy surface. The obtained functional materials were characterised by various spectroscopy techniques. The corrosion inhibition and composite material stability were studied by the electrochemical methods. The electrochemical stability was shown to increase with the applied current. The hydrogen evolution constantly increased and the corrosion inhibition significantly improved. Also, the computational studies of the material were performed, and their results support the experimental findings. Overall, the resultant composite material's corrosion resistance and cyclic stability are improved, and it could be used as a sodium-ion battery cathode material due to its high reversibility.

Synergistic Coating Strategy Combining Photodynamic Therapy and Fluoride-Free Superhydrophobicity for Eradicating Bacterial Adhesion and Reinforcing Corrosion Protection.

Device-associated infection is one of the significant challenges in the biomedical industry and clinical management. Controlling the initial attachment of microbes upon the solid surface of biomedical devices is a sound strategy to minimize the formation of biofilms and infection. A synergistic coating strategy combining superhydrophobicity and bactericidal photodynamic therapy is proposed herein to tackle infection issues for biomedical materials. A multifunctional coating is produced upon pure Mg substrate through a simple blending procedure without involvement of any fluoride-containing agents, differing from the common superhydrophobic surface preparations. Superhydrophobic features of the coating are confirmed through water contact angle measurements (152.5 ± 1.9°). In vitro experiments reveal that bacterial-adhesion repellency regarding both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) strains approaches over 96%, which is evidently ascribed to the proposed synergistic strategy, that is, superhydrophobic nature and microbicidal ability of photodynamic therapy. Electrochemical analysis indicates that the superhydrophobic coating provides pronounced protection against corrosion to underlying Mg with 80% reduction in the corrosion rate in minimum essential medium and retains the original surface features after 168 h exposure to neutral salt spray. The proof-of-concept research holds a great promise for tackling the notorious bacterial infection and poor corrosion resistance of Mg-based biodegradable materials in a simple, efficient, and environmentally benign manner.

Bioimaging of C2C12 Muscle Myoblasts Using Fluorescent Carbon Quantum Dots Synthesized from Bread.

Biocompatible carbon quantum dots (CQDs) have recently attracted increased interest in biomedical imaging owing to their advantageous photoluminescence properties. Numerous precursors of fluorescent CQDs and various fabrication procedures are also reported in the literature. However; the use of concentrated mineral acids and other corrosive chemicals during the fabrication process curtails their biocompatibility and severely limits the utilization of the products in cell bio-imaging. In this study; a facile; fast; and cost-effective synthetic route is employed to fabricate CQDs from a natural organic resource; namely bread; where the use of any toxic chemicals is eliminated. Thus; the novel chemical-free technique facilitated the production of luminescent CQDs that were endowed with low cytotoxicity and; therefore; suitable candidates for bioimaging sensors. The above mentioned amorphous CQDs also exhibited fluorescence over 360-420 nm excitation wavelengths; and with a broad emission range of 360-600 nm. We have also shown that the CQDs were well internalized by muscle myoblasts (C2C12) and differentiated myotubes; the cell lines which have not been reported before.

Exposure, assessment and health hazards of particulate matter in metal additive manufacturing: A review.

Metal additive manufacturing (AM), also known as metal three-dimensional (3D) printing, is a new technology offering design freedom to create complex structures that has found increasing applications in industrial processes. However, due to the fine metal powders and high temperatures involved, the printing process is likely to generate particulate matter (PM) that has a detrimental impact on the environment and human health. Therefore, comprehensive assessement of the exposure and health hazards of PM pollution related to this technique is urgently required. This review provides general knowledge of metal AM and its possible particle release. The health issues of metal PM are described considering the exposure routes, adverse human health outcomes and influencing factors. Methods of evaluating PM exposure and risk assessment techniques are also summarized. Lastly, future research needs are suggested. The information and knowledge presented in this review will contribute to the understanding, assessment, and control of possible risks in metal AM and benefit the wider metal 3D printing community, which includes machine operators, consumers, R&D scientists, and policymakers.