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Researchers have been driven to investigate sustainable alternatives to cement production, such as geopolymers, due to the impact of global warming and climate change resulting from greenhouse gas emissions. Currently, they are exploring different methods and waste materials to enhance the mechanical and physical properties of geopolymer and expand its application range. This review paper offers a thorough analysis of the utilization of various waste materials in geopolymer manufacturing and shows the creative contribution of this research to the development of environmentally friendly cement substitutes. The article covers the properties, durability, and practical applications of geopolymer composites made from various waste binders. It includes a microstructure and chemical analysis. The research findings indicate that geopolymers are an effective cementitious binder substitute for cement in various applications. Additionally, the ecological and carbon footprint analysis highlights the sustainability of geopolymers compared to cement.

Healthcare systems have reached a critical point regarding the question of whether biosimilar substitution should become common practice. To move the discussion forward, the study objective was to investigate the views of experts from medicines agencies and the pharmaceutical industry on the science underpinning interchangeability of biosimilars. We conducted an empirical qualitative study using semi-structured interviews informed by a cross-disciplinary approach encompassing regulatory science, law, and pharmaceutical policy. In total 25 individuals with experience within biologics participated during September 2018–August 2019. Eight participants were EU national medicines authority regulators, and 17 had pharmaceutical industry background: five from two originator-only companies, four from two companies with both biosimilar and originator products, and eight from seven biosimilar-only companies. Two analysts independently conducted inductive content analysis, resulting in data-driven themes capturing the meaning of the data. The participants reported that interchangeability was more than a scientific question of likeness between biosimilar and reference products: it also pertained to regulatory practices and trust. Participants were overall confident in the science behind exchanging biosimilar products for the reference products via switching, i.e., with physician involvement. However, their opinions differed regarding the scientific risk associated with biosimilar substitution, i.e., without physician involvement. Almost all participants saw no need for additional scientific data to support substitution. Moreover, the participants did not believe that switching studies, as required in the US, were appropriate for obtaining scientific certainty due to their small size. It is unclear why biosimilar switching is viewed as scientifically safer than substitution; therefore, we expect greater policy debate on biosimilar substitution in the near future. We urge European and UK policymakers and regulators to clarify their visions for biosimilar substitution; the positions of these two frontrunners are likely to influence other jurisdictions on the future of biosimilar use.

It is not uncommon that supply chain partners carry out cooperative advertising in green production involving green and dirty products (i.e., substitute products). Besides the advertising decisions, they need to jointly make many other decisions, such as substitute products’ production quantities, wholesale prices, and retail prices. Practice and literature have shown that manufacturers-retailers’ joint decision-making is of paramount importance yet challenging. This decision-making difficulty is compounded by governments’ carbon tax policies and financial subsidies. To facilitate firms in making decisions, this study examines the joint decision-making mechanism involving local governments’ carbon taxes and subsidies. To overcome the limitations of the relevant literature addressing one product and relatively fewer decisions, we include both dirty and green products and consider diverse decisions, including technology selection, production quantities, wholesale prices, and retail prices for both products. Additionally, we consider the retailers’ advertising investment decisions for both products and the manufacturers’ ratios of advertising investment paid to retailers. Capitalizing on decision interactions, we develop a Stackelberg game-based bilevel optimization model. Caused by the large number of decisions and their interactions, solving the game model analytically is barely possible. Consequently, we propose an algorithm of nested particle swarm optimization (NPSO). We perform numerical examples to show how the game model and the NPSO can help firms make complex joint decisions with many interactions. We also carry out sensitivity analysis based on which managerial insights are drawn.

Background Heterotrophic single-cell oils (SCOs) are one potential replacement to lipid-derived biofuels sourced from first-generation crops such as palm oil. However, despite a large experimental research effort in this area, there are only a handful of techno-economic modelling publications. As such, there is little understanding of whether SCOs are, or could ever be, a potential competitive replacement. To help address this question, we designed a detailed model that coupled a hypothetical heterotroph (using the very best possible biological lipid production) with the largest and most efficient chemical plant design possible. Results Our base case gave a lipid selling price of $1.81/kg for ~ 8,000 tonnes/year production, that could be reduced to $1.20/kg on increasing production to ~ 48,000 tonnes of lipid a year. A range of scenarios to further reduce this cost were then assessed, including using a thermotolerant strain (reducing the cost from $1.20 to $1.15/kg), zero-cost electricity ($ 1.12/kg), using non-sterile conditions ($1.19/kg), wet extraction of lipids ($1.16/kg), continuous production of extracellular lipid ($0.99/kg) and selling the whole yeast cell, including recovering value for the protein and carbohydrate ($0.81/kg). If co-products were produced alongside the lipid then the price could be effectively reduced to $0, depending on the amount of carbon funnelled away from lipid production, as long as the co-product could be sold in excess of $1/kg. Conclusions The model presented here represents an ideal case that which while not achievable in reality, importantly would not be able to be improved on, irrespective of the scientific advances in this area. From the scenarios explored, it is possible to produce lower cost SCOs, but research must start to be applied in three key areas, firstly designing products where the whole cell is used. Secondly, further work on the product systems that produce lipids extracellularly in a continuous processing methodology or finally that create an effective biorefinery designed to produce a low molecular weight, bulk chemical, alongside the lipid. All other research areas will only ever give incremental gains rather than leading towards an economically competitive, sustainable, microbial oil.

During the preparation of beer wort, significant amounts of waste raw materials, such as brewers’ spent grain (BSG), are generated. In line with the zero-waste approach, a processing technology for BSG was developed to valorize this by-product. The developed method involves obtaining a BSG extract (plant-based milk), followed by filtration to remove insoluble residues and subsequent fermentation to produce vegan BSG-based yogurt-like products, with and without the addition of sucrose, as well as pectin, guar gum, and konjac gum as stabilizers. The samples were analyzed for pH, moisture and protein content, water activity (Aw), color, viscosity, and syneresis, and were also subjected to an organoleptic evaluation. Fermentation with starter cultures yielded BSG-based yogurt-like products with an optimal pH (~4.0), which, combined with Aw values below 0.95, ensures microbiological safety by inhibiting the growth of pathogenic and spoilage microorganisms. Due to phase separation, the use of stabilizers was necessary to achieve a yogurt-like texture. Their application also contributed to a reduction in syneresis—sometimes even preventing its occurrence—and led to an increase in viscosity, which ranged from 0.162 to 0.463 Pa·s, depending on the stabilizer used. The moisture content of fermented BSG extracts ranged from 88.2% to 91.7%. All samples showed similar protein content, approximately 50% on a dry matter basis. Furthermore, organoleptic assessment (5-point scale) revealed that sensory characteristics varied depending on the stabilizer and sugar used. The yogurt-like variant formulated with 0.5% pectin and 1% sucrose received the highest acceptance score (4.0), indicating good sensory quality.

Organophosphate esters (OPEs) are a class of chemicals with a long history of use as plasticizers and flame retardants. In the latter context, they have recently become more common, whereas some legacy organohalogen flame retardants, which have different molecular structures and mechanisms of action, have been phased out over concerns about health effects. However, as is often the case, the substitute has now gained its own spotlight, and these increasingly widespread phosphorus-based chemicals are being studied for health effects of their own. Recently published research inEnvironmental Health Perspectives adds to growing concern about the potential harms of OPE flame retardants by outlining how exposure to a mixture of 13 of the chemicals in vitro affected critical human immune cells called macro-phages. The researchers, based at McGill University in Montreal, Canada, combined the substances at concentrations and ratios that were measured in samples of Canadian household dust.

Concrete manufacturing and recycling must evolve to meet sustainability and carbon reduction demands. While the focus is often on reusing coarse aggregates, fine fractions are also produced during recycling. This study explores using ground fine fractions (0/2) as a partial cement substitute. The fines were characterized for their mineralogical, chemical, and physical properties, and experiments were conducted on pastes and mortars with 0% to 30% cement substitution, including isothermal calorimetry and strength tests. Two concrete mixes—a reference mix with natural aggregates and CEM I, and a mix with 10% concrete fines replacing CEM I—using recycled sand and coarse aggregates were tested for compressive strength, carbonation, shrinkage, and freeze–thaw resistance. The results indicated that the recycled concrete had a comparable strength to the reference and a slightly reduced durability in freeze–thaw conditions. In terms of shrinkage, recycled concrete with 10% concrete fines had an increased drying shrinkage and a lower autogenous shrinkage due to the water retention capacity of the recycled aggregates.

This research undertook an extensive examination of the ramifications of integrating steel dust as a partial substitute for cement within reinforced concrete beams. The investigation encompassed an assessment of various facets, encompassing the workability of the concrete mixture, alongside crucial mechanical properties such as compressive strength, split tensile strength, flexural strength, ultrasonic pulse velocity (UPV), and elasticity modulus. The findings unveiled a notable reduction in workability as the proportion of steel dust increased within the mixture, with a consequential substantial impact on the elasticity modulus. Notably, compressive strength exhibited an enhancement at a 10% replacement of cement yet exhibited a decline with higher degrees of cement substitution. The inclusion of steel dust led to the formulation of adjusted equations pertaining to split tensile and flexural strength characteristics within the mixture. Remarkably, the incorporation of 10% steel dust yielded an increase in ductility. Conversely, at a 30% steel dust inclusion level, ductility diminished alongside a reduction in the maximum load-bearing capacity. In light of these findings, it is imperative to exercise prudence when considering the utilization of steel dust as a cement substitute, particularly when approaching or exceeding the 10% replacement level threshold. Further comprehensive research is imperative to acquire a comprehensive understanding of its implications and its susceptibility to potential corrosion concerns.

Xerostomia is frequently associated with an increased risk of oral candidiasis caused by Candida albicans . Despite its high prevalence, current therapeutic options remain limited, with management largely dependent on saliva substitutes for symptomatic relief. Objective This in vitro study aimed to evaluate the effect of various saliva substitutes on Candida albicans biofilm growth. Material and methods Six commercially available saliva substitutes were evaluated using a standardized Candida albicans biofilm growth assay in a 96-well plate format. Experimental conditions were adapted to simulate the oral environment, including the formation of a salivary pellicle. Salivary pellicle formation was characterized by measuring mass deposition and viscoelastic properties, before and after rinsing with saliva substitutes, using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D). Statistical analyses were performed using two-way ANOVA followed by Tukey’s post hoc test for biofilm data, and unpaired Student’s t-test for salivary protein content. Results Two oil-based substitutes (Aequasyal ® and Vea Oris ® ) significantly enhanced Candida albicans biofilm formation compared to control (PBS) ( p  < 0.05). QCM-D characterization of the salivary pellicle after rinsing revealed that this effect was associated with stable interactions between substitute components and the salivary pellicle, leading to structural modifications of the protein layer. Conclusion While oil-based saliva substitutes effectively alleviate xerostomia symptoms, they may unintentionally promote Candida albicans biofilm formation. Clinicians should exercise caution when recommending these products to patients with a history of oral candidiasis, favoring water-based alternatives especially in high-risk individuals.

In a sustainable approach, it is essential to reduce waste materials for improving the urban environmental performance leads to development in the livable, sustainable, and greener city. In pursuit of this goal, iron lathe waste was used in this study as a replacement of fine aggregate to produce sustainable concrete. Iron lathe waste is generally a waste material from the lathe machine, which is abundantly available to an extent. These waste materials may lead to environmental and health concerns. Therefore, the main goal of this study is to experimentally examine the physio-mechanical characteristics of sustainable concrete incorporating lathe iron waste. The lathe iron waste dusts (LIWD) were used as a partial replacement of fine aggregate in different levels by weight (5%, 10%, 15%, and 20%) to fabricate the sustainable concrete. The mechanical and physical properties of sustainable concrete were investigated by conducting tests, such as workability, ultrasonic pulse velocity, compressive strength, splitting tensile strength, and flexural strength to investigate the properties of the alternative concrete comparing with that of conventional concrete. The experimental results showed that the LIWD significantly enhanced the tensile, flexural, and compressive strength of the concrete up to 13%, 19%, and 38%, respectively. Therefore, LIWD can potentially improve the serviceability of the structural elements.