The application of high hydrostatic pressure is an effective tool to promote dissolution and refolding of protein from aggregates and inclusion bodies while minimizing reaggregation. In this study we ...explored the mechanism of high-pressure protein refolding by quantitatively assessing the magnitude of the protein-protein interactions both at atmospheric and elevated pressures for T4 lysozyme, in solutions containing various amounts of guanidinium hydrochloride. At atmospheric pressure, the protein- protein interactions are most attractive at moderate guanidinium hydrochloride concentrations (1-2 molar), as indicated by a minimum in B22 values. In contrast, at a pressure of 1,000 bar no minimum in B22 values is observed, indicating that high pressures colloidally stabilize protein against aggregation. Finally, experimental values of refractive index increments as a function of pressure indicate that at high pressures, wetting of the hydrophobic surfaces is favored, resulting in a reduction of the hydrophobic effect. This reduction in the hydrophobic effect reduces the driving force for aggregation of (partially) unfolded protein. Biotechnol. Bioeng. 2009; 102: 483-492.
Geopolymer recycled aggregate concrete (GPRAC) is a new type of green material with broad application prospects by replacing ordinary Portland cement with geopolymer and natural aggregates with ...recycled aggregates. This paper summarizes the research about the mechanical properties, durability, and microscopic aspects of GPRAC. The reviewed contents include compressive strength, elastic modulus, flexural strength, splitting tensile strength, freeze-thaw resistance, abrasion resistance, sulfate corrosion resistance, and chloride penetration resistance. It is found that GPRAC can be made to work better by changing the curing temperature, using different precursor materials, adding fibers and nanoparticles, and setting optimal mix ratios. Among them, using multiple precursor materials in synergy tended to show better performance compared to a single precursor material. In addition, using modified recycled aggregates, the porosity and water absorption decreased by 18.97% and 25.33%, respectively, and the apparent density was similar to that of natural aggregates. The current results show that the performance of GPRAC can meet engineering requirements. In addition, compared with traditional concrete, the use of GPRAC can effectively reduce carbon emissions, energy loss, and environmental pollution, which is in line with the concept of green and low-carbon development in modern society. In general, GPRAC has good prospects and development space. This paper reviews the effects of factors such as recycled aggregate admixture and curing temperature on the performance of GPRAC, which helps to optimize the ratio design and curing conditions, as well as provide guidance for the application of recycled aggregate in geopolymer concrete, and also supply theoretical support for the subsequent application of GPRAC in practical engineering.
ABSTRACT
Protein aggregation occurs as a consequence of perturbations in protein homeostasis that can be triggered by environmental and cellular stresses. The accumulation of protein aggregates has ...been associated with aging and other pathologies in eukaryotes, and in bacteria with changes in growth rate, stress resistance and virulence. Numerous past studies, mostly performed in Escherichia coli, have led to a detailed understanding of the functions of the bacterial protein quality control machinery in preventing and reversing protein aggregation. However, more recent research points toward unexpected diversity in how phylogenetically different bacteria utilize components of this machinery to cope with protein aggregation. Furthermore, how persistent protein aggregates localize and are passed on to progeny during cell division and how their presence impacts reproduction and the fitness of bacterial populations remains a controversial field of research. Finally, although protein aggregation is generally seen as a symptom of stress, recent work suggests that aggregation of specific proteins under certain conditions can regulate gene expression and cellular resource allocation. This review discusses recent advances in understanding the consequences of protein aggregation and how this process is dealt with in bacteria, with focus on highlighting the differences and similarities observed between phylogenetically different groups of bacteria.
This review discusses recent advances in understanding the consequences of protein aggregation and how this process is dealt with in bacteria, with focus on highlighting the differences and similarities observed between phylogenetically different groups of bacteria.
Infrastructure development and urbanization have created a demand for the prime construction material—"Concrete." The manufacture of concrete has pressurized the aggregate supply chain for ...over-exploitation of natural resources leading to eco-detrimental impacts besides environmental regulations. The auxiliary sectors of the construction industry are creating a vast quantum of by-products and waste, causing environmental degradation, which concerns governing bodies. Developing aggregates artificially using these by-products and waste materials would be an eco-friendly and economical solution. This article provides an overview of the ingredients, production methods, and factors influencing the characteristics of such sustainable building materials, which can substitute conventional aggregates in the near future.
Display omitted
Protein aggregation has been recognized as one of the major challenges in the development and commercialization of successful protein-based drug products because of the inherent and ...high aggregation tendency during various manufacturing processes, storage, and administration. Protein aggregates may impact significantly the product quality, safety and/or efficacy. This review is intended to summarize four major aspects of protein aggregation – (1) aggregation mechanisms, (2) aggregation-influencing factors, (3) detection of protein aggregates, and (4) control of protein aggregation based on recent literature in this area.
As the demand for nonrenewable natural resources, such as aggregate, is increasing worldwide, new production of artificial aggregate should be developed. Artificial lightweight aggregate can bring ...advantages to the construction field due to its lower density, thus reducing the dead load applied to the structural elements. In addition, application of artificial lightweight aggregate in lightweight concrete will produce lower thermal conductivity. However, the production of artificial lightweight aggregate is still limited. Production of artificial lightweight aggregate incorporating waste materials or pozzolanic materials is advantageous and beneficial in terms of being environmentally friendly, as well as lowering carbon dioxide emissions. Moreover, additives, such as geopolymer, have been introduced as one of the alternative construction materials that have been proven to have excellent properties. Thus, this paper will review the production of artificial lightweight aggregate through various methods, including sintering, cold bonding, and autoclaving. The significant properties of artificial lightweight aggregate, including physical and mechanical properties, such as water absorption, crushing strength, and impact value, are reviewed. The properties of concrete, including thermal properties, that utilized artificial lightweight aggregate were also briefly reviewed to highlight the advantages of artificial lightweight aggregate.
•Analysis of aggregates’ management and supply chain.•Valorization of C&DW into RA allows environmental impacts’ saving.•Savings can be achieved in terms of natural resources consumption ...avoidance.•Transportation-related impacts affect substantially aggregates’ impacts.•Compensation in terms of aggregates delivery distance can be evaluated.
The consumption of natural aggregates in civil engineering applications can cause severe environmental impacts on a regional scale, depleting the stock of bulk resources within a territory. Several methods can improve the environmental sustainability of the whole aggregates’ supply process, including natural and recycled aggregates’ productive chains, for instance promoting the use of recycled aggregates (RA). However, when quarrying and recycling activities are considered as stand-alone processes, also the RA supply chain may not be as sustainable as expected, due to the high environmental loads associated to transportation, if high distances from the production to the use sites are involved. This work gives some insights on the environmental impact assessment of the aggregates’ industry in the Italian context, through a comparative assessment of the environmental loads of natural and recycled aggregates’ productive chains. An integrated plant for the extraction of virgin aggregates and recycling of construction and demolition waste (C&DW) was analyzed as significant case study, with the aim to identify the influence of sustainable solutions on the overall emissions of the facility. A Life Cycle Assessment (LCA) approach was used, using site-specific data and paying particular attention on transportation-related impacts, land use, avoided landfill and non-renewable resources preservation. From this work it was possible to evaluate the influence of transportation and PV energy use on the overall environmental emissions of natural and recycled aggregates’ productive chains.
The effect of grain size distribution on the unconfined compressive strength (UCS) of bio-cemented granular columns is examined. Fine and coarse aggregates were mixed in various percentages to obtain ...five different grain size distributions. A four-phase percolation strategy was adopted where a bacterial suspension and a cementation solution (urea and calcium chloride) were percolated sequentially. The results show that a gap-graded particle size distribution can improve the UCS of bio-cemented coarser granular materials. A maximum UCS of approximately 575 kPa was achieved with a particle size distribution containing 75% coarse aggregate and 25% fine aggregate. Furthermore, the minimum UCS obtained has applications where mitigation of excessive bulging of stone/sand columns, and possible slumping that might occur during their installation, is needed. The finding also implies that the amount of biochemical treatments can be reduced by adding fine aggregate to coarse aggregate resulting in effective bio-cementation within the pore matrix of the coarse aggregate column as it could substantially reduce the cost associated with bio-cementation process. Scanning electron microscopy results confirm that adding fine aggregate to coarse aggregate provides more bridging contacts (connected by calcium carbonate precipitation) between coarse aggregate particles, and hence, the maximum UCS achieved was not necessarily associated with the maximum calcium carbonate precipitation.
•Structural health monitoring is applied on a recycled aggregate concrete structure.•Effects of the ambient environment and structural response amplitudes are analyzed.•Serviceability is evaluated ...based on the structural responses during typhoons.•Dynamic parameters are predicted by stick-slip model and artificial neural network.
To encourage the application of recycled coarse aggregates (RCA) produced from construction and demolition (C&D) waste in newly-built structures, this study investigates the dynamic behaviors of a 12-story recycled aggregate concrete (RAC) in the operational environment through structural health monitoring (SHM), and compares with an adjacent 12-story natural aggregate concrete (NAC) structure with similar arrangements of components and structural construction. The SHM has undergone 12 months, and has provided a wealth of data detailing the dynamic behaviors with the variation in the operational environment as well as significant structural responses excited by typhoons and earthquakes. Firstly, the first 5 vibration modes of both structures are identified, and the effects of the ambient temperature, hourly mean wind speed and structural response amplitude are analyzed. A lower natural frequency and a larger damping ratio of the fundamental vibration mode of the RAC structure are found than those of the NAC structure. For both the RAC and NAC structures, the fundamental frequency increases with the increasing ambient temperature, the decreasing hourly mean wind speed, and the decreasing structural response amplitude. The opposite trend of the damping ratios is identified. Secondly, the stick-slip model is used to explain the differences between the modal parameters of the RAC and the NAC structures, and to discover the mechanism of the effects of the ambient temperature, the hourly mean wind speed, and the structural response amplitude. Thirdly, the serviceability of the RAC structure is evaluated based on the full-scale measurements during typhoons. Finally, the artificial neural network (ANN) is validated to have the capacity for predicting the modal parameters precisely, and the model error of the ANN has the potential as an indicator for detecting abnormal structural performances.
Plastic products have become ubiquitous in society, and entered various ecosystems due to the massive scale of production. The United Nations Environment Program (UNEP) has listed microplastics ...(MPs), which form when plastic remnants degrade, as a global emerging pollutant, and the association between soil pollution and MPs has become a popular research topic. This paper systematically reviews research focusing on MP-related soil pollution from the past 10 years (2012−2022), with the identified papers demonstrating that interactions between MPs and soil aggregates has become a research frontier in the field. The presented research provides evidence that soil aggregates are important storage sites for MPs, and that storage patterns of MPs within soil aggregates are influenced by MP characteristics. In addition, MPs affect the formation, turnover, and stability of soil aggregates through the introduction of fracture points along with diverse physicochemical characteristics such as composition and specific surface area. The current knowledge base includes certain issues and challenges that could be addressed in future research by extending the spatial and temporal scales over which microplastic-soil aggregate interactions are studied, unifying quantitative and qualitative methods, and tracing the fates of MPs in the soil matrix. This review contributes to enriching our understanding of how terrestrial MPs interact with soil aggregates, and whether they pose a risk to soil health.
Display omitted
•Research focusing on microplastics (MPs) and soil aggregates increased over the last decade.•MPs mainly interact with soil aggregates by influencing fundamental soil properties.•MP-specific characteristics (shape, size, type and composition) affect these interactions.•The prevalence of MPs is influenced by soil organisms and organic carbon in the soil.•Long-term field studies, along with the labelling of MPs, can verify prior empirical results.
PDF
