Effect of alkalinity and calcium concentration of pore solution on the swelling and ionic exchange of superabsorbent polymers in cement paste

Swelling kinetics of superabsorbent polymers (SAP) in fresh concrete is complex, but its understanding is crucial for optimisation in practical applications. In this study, the effect of concentration of ions common in pore solution (Na+, K+, Ca2+, Cl−, OH−, SO42−) and cyclic wetting/drying on the swelling and ionic exchange of poly(AA) and poly(AA-co-AM) were investigated. Results show that swelling is not a simple function of concentration or ionic strength. In cement paste, SAP absorbs Ca2+ and releases its counterion (Na+, K+) into pore solution. Ca2+ binds with SAP and decreases initial swelling, but the bound Ca2+ can be displaced and swelling gradually recovers. Swelling increases with increase in alkalinity, but decreases with increase in calcium concentration. The higher the degree of ion exchange, the lower the swelling of SAP. Poly(AA) is more susceptible to Ca2+ complexation and therefore achieves a lower swelling ratio and slower swelling recovery compared to poly(AA-co-AM)

Dietary patterns, insulin sensitivity and inflammation in older adults.

Background/objectivesSeveral studies have linked dietary patterns to insulin sensitivity and systemic inflammation, which affect risk of multiple chronic diseases. The purpose of this study was to investigate the dietary patterns of a cohort of older adults, and to examine relationships of dietary patterns with markers of insulin sensitivity and systemic inflammation.Subjects/methodsThe Health, Aging and Body Composition (Health ABC) Study is a prospective cohort study of 3075 older adults. In Health ABC, multiple indicators of glucose metabolism and systemic inflammation were assessed. Food intake was estimated with a modified Block food frequency questionnaire. In this study, dietary patterns of 1751 participants with complete data were derived by cluster analysis.ResultsSix clusters were identified, including a 'healthy foods' cluster, characterized by higher intake of low-fat dairy products, fruit, whole grains, poultry, fish and vegetables. In the main analysis, the 'healthy foods' cluster had significantly lower fasting insulin and homeostasis model assessment of insulin resistance values than the 'breakfast cereal' and 'high-fat dairy products' clusters, and lower fasting glucose than the 'high-fat dairy products' cluster (P≤0.05). No differences were found in 2-h glucose. With respect to inflammation, the 'healthy foods' cluster had lower interleukin-6 than the 'sweets and desserts' and 'high-fat dairy products' clusters, and no differences were seen in C-reactive protein or tumor necrosis factor-α.ConclusionsA dietary pattern high in low-fat dairy products, fruit, whole grains, poultry, fish and vegetables may be associated with greater insulin sensitivity and lower systemic inflammation in older adults

Droop Control of Distributed Electric Springs for Stabilizing Future Power Grid

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GRB 180620A: Evidence for Late-time Energy Injection

The early optical emission of gamma-ray bursts (GRBs) gives an opportunity to understand the central engine and first stages of these events. About 30% of GRBs present flares whose origin is still a subject of discussion. We present optical photometry of GRB 180620A with the COATLI telescope and RATIR instrument. COATLI started to observe from the end of prompt emission at T + 39.3 s and RATIR from T + 121.4 s. We supplement the optical data with the X-ray light curve from Swift/XRT. We observe an optical flare from T + 110 s to T + 550 s, with a temporal index decay α O,decay = 1.32 ± 0.01, and Δt/t = 1.63, which we interpret as the signature of a reverse shock component. After the initial normal decay the light curves show a long plateau from T + 500 s to T + 7800 s in both X-rays and the optical before decaying again after an achromatic jet break at T + 7800 s. Fluctuations are seen during the plateau phase in the optical. Adding to the complexity of GRB afterglows, the plateau phase (typically associated with the coasting phase of the jet) is seen in this object after the "normal" decay phase (associated with the deceleration phase of the jet), and the jet break phase occurs directly after the plateau. We suggest that this sequence of events can be explained by a rapid deceleration of the jet with t d ≲ 40 s due to the high density of the environment (≈100 cm-3) followed by reactivation of the central engine, which causes the flare and powers the plateau phase

Demographic Change and R&D-Based Economic Growth: Reconciling Theory and Evidence

In recent decades, most industrialized countries experienced declining population growth rates caused by declining fertility and associated with rising life expectancy. We analyze the effect of continuing demographic change on medium- and long-run economic growth by setting forth an R&D-based growth model including an analytically tractable demographic structure. Our results show that, in response to demographic change, technological progress and economic growth accelerate in the medium run but slow down in the long run. Numerical investigation reveals that the time period during which technological progress and economic growth are faster than without demographic change can be very long. Since the theoretical predictions for the medium run are consistent with the negative association between population growth and economic growth found in the empirical literature, the present framework can reconcile R&D-based growth theory with the available empirical evidence

Intracerebral haemorrhage complicating anticoagulant therapy among Hong Kong Chinese

PosterBACKGROUND: Anticoagulation is effective to prevent cardioembolism in patients with atrial fibrillation (AF) and prosthetic heart valves, but carries risk of potentially life-threatening intracerebral haemorrhage (ICH). The ideal international normalised ratio (INR) for Chinese patients on warfarin treatment is uncertain. We aimed to study the clinical and radiological characteristics of Chinese patients who developed acute ICH while on warfarin …published_or_final_versio

The role of TcdB and TccC subunits in secretion of the photorhabdus Tcd toxin complex

The Toxin Complex (TC) is a large multi-subunit toxin encoded by a range of bacterial pathogens. The best-characterized examples are from the insect pathogens Photorhabdus, Xenorhabdus and Yersinia. They consist of three large protein subunits, designated A, B and C that assemble in a 5:1:1 stoichiometry. Oral toxicity to a range of insects means that some have the potential to be developed as pest control technology. The three subunit proteins do not encode any recognisable export sequences and as such little progress has been made in understanding their secretion. We have developed heterologous TC production and secretion models in E. coli and used them to ascribe functions to different domains of the crucial B+C sub-complex. We have determined that the B and C subunits use a secretion mechanism that is either encoded by the proteins themselves or employ an as yet undefined system common to laboratory strains of E. coli. We demonstrate that both the N-terminal domains of the B and C subunits are required for secretion of the whole complex. We propose a model whereby the N-terminus of the C-subunit toxin exports the B+C sub-complex across the inner membrane while that of the B-subunit allows passage across the outer membrane. We also demonstrate that even in the absence of the B-subunit, that the C-subunit can also facilitate secretion of the larger A-subunit. The recognition of this novel export system is likely to be of importance to future protein secretion studies. Finally, the identification of homologues of B and C subunits in diverse bacterial pathogens, including Burkholderia and Pseudomonas, suggests that these toxins are likely to be important in a range of different hosts, including man