Glassy Polymers—Diffusion, Sorption, Ageing and Applications

For the past few decades, researchers have been intrigued by glassy polymers, which have applications ranging from gas separations to corrosion protection to drug delivery systems. The techniques employed to examine the sorption and diffusion of small molecules in glassy polymers are the subject of this review. Diffusion models in glassy polymers are regulated by Fickian and non-Fickian diffusion, with non-Fickian diffusion being more prevalent. The characteristics of glassy polymers are determined by sorption isotherms, and different models have been proposed in the literature to explain sorption in glassy polymers over the last few years. This review also includes the applications of glassy polymers. Despite having many applications, current researchers still have difficulty in implementing coating challenges due to issues such as physical ageing, brittleness, etc., which are briefly discussed in the review.

Quantify each Dendritic Cell Subsets along with Normal Thymus Tissues in Different Ages

BackgroundDendritic cells (DCs) in the thymus are involved in central tolerance formation, but they also play other roles in the thymus. In this study, thymuses of different ages were collected for observation after tissue sectioning and staining. The area of cortex and medulla parts of the thymus in the sections and the density of different subsets of DCs in the thymus were also calculated. ResultsWe found that, along with the increasing age, the thymic cortex atrophies faster, leading to a gradual rise in the medullary's surface area ratio to that of the cortex with an increase in age. The medullary's surface area ratio to cortex can be used as an indirect reference to reflect the thymus hyperplasia. The density of DCs in the thymus showed different changes with the increasing age, and the density of plasmacytoid DCs (pDCs) in the thymus gradually increased with aging, suggesting that pDCs may play an essential role in the thymus in addition to central tolerance.ConclusionsThese findings complement our knowledge about the DCs’ subsets in the thymus along with physical ageing and help us understand the full function of DCs in the thymus beyond central tolerance.

Physical Ageing of Amorphous Indapamide Characterised by Differential Scanning Calorimetry

The objective of this study was to characterise amorphous indapamide (IND) subjected to the physical ageing process by differential scanning calorimetry (DSC). The amorphous indapamide was annealed at different temperatures below the glass transition, i.e., 35, 40, 45, 65, 75 and 85 °C for different lengths of time, from 30 min up to a maximum of 32 h. DSC was used to characterise both the crystalline and the freshly prepared glass and to monitor the extent of relaxation at temperatures below the glass transition (Tg). No ageing occurred at 35, 40 and 45 °C at the measured lengths of times. Molecular relaxation time constants (τKWW) for samples aged at 65, 75 and 85 °C were determined by the Kohlrausch-Williams-Watts (KWW) equation. The fragility parameter m (a measure of the stability below the glass transition) was determined from the Tg dependence from the cooling and heating rates, and IND was found to be relatively stable (“moderately fragile”) in the amorphous state. Temperature-modulated DSC was used to separate reversing and nonreversing processes for unaged amorphous IND. The enthalpy relaxation peak was clearly observed as a part of the nonreversing signal. Heat capacities data for unaged and physically aged IND were fitted to Cp baselines of solid and liquid states of IND, were integrated and enthalpy was presented as a function of temperature.

Effect of biochar addition to compost on biological stability of the mixture

<p>Application of biochar, a solid product produced from biomass pyrolysis under low oxygen conditions, has been suggested as a low emission technology capable of increasing soil C sequestration to mitigate climate change. Its combined application with compost may be a promising avenue to ameliorate soil quality while increasing C sequestration. We hypothesized that biochar addition to compost reduces the mineralization of the mixture compared to compost alone. The study aimed to compare the mineralization rate of six biochar-compost mixtures differentiated by biochar feedstocks. Biochars were produced at temperatures ranging from 450 to 650°C for 10 minutes. Our conceptual approach included incubation of fresh and artificially aged biochar-compost mixtures. Physical ageing of the mixtures was performed with successive cycles of humidification/drying and freezing/thawing. We evaluated elemental composition and biological stability of the fresh and aged mixtures after incubation with a soil inoculum for 1 year. We monitored components of biochar-compost mixtures decomposition when biochar were produced from C4 feedstock by determination of the <sup>13</sup>C signature of emitted CO<sub>2</sub>.</p><p>Combination of compost with biochar induced synergistic effects in terms of the mixtures stability. Isotopic analyses showed that carbon mineralization from compost was greatly reduced, while biochar mineralization was increased. Physical ageing induced a strong leaching of water-soluble compounds of both substrates. Carbon mineralization of aged material was however not reduced as much as expected when comparing with mineralization rates of single compounds of the mixture. Furthermore, isotopic signatures showed that compost, when amended with biochar, mineralized better after ageing. We thus suggest that the water-soluble fraction of biochar may induce an inhibitive effect on the mineralization of compost. The intensity of this effect seems to be dependent upon the feedstock of the biochar in the mixture.</p><p>We conclude that biochar addition to compost may reduce the mineralization of the mixture depending on biochar feedstock and that this effect may be alleviated after ageing.</p>

Reconstructing dependency: precarity, precariousness and care in old age

This chapter explores the potential for the development of critical approach to care based on the concepts of precarity and precariousness. Applying those concepts at the level of both theory and analysis, it is argued, serves to draw attention to both the socially constructed uncertainties of care provision conditioned by the labour market and corporate practices on the one hand, and the uncertainties of physical ageing and the ontological vulnerabilities that arise from our bodily existence on the other. Uncertainty also confronts those who provide care in either a paid or unpaid/informal capacity. The precarious conditions of work reflect the financial fragility of the economic supports and the changing and unequal markets that increasingly underpin the way care is provided to the increasing numbers of people who live extended lives today.