Video abstract Video

The effects of frequency on fatigue crack growth behaviour have been studied in a prealloyed powder material, Udimet 720Li, at 650 °C. Fracture mode and fatigue crack growth behaviour were studied at frequencies ranging from 0.001 to 5 Hz using a balanced triangular waveform. Tests were carried out under constant ΔK control, with load ratio and temperature being held constant. A mechanism map was constructed where predominantly time, mixed and cycle‐dependent crack growth behaviour were identified. The results were verified by SEM analyses. Cycle‐dependent crack growth data were obtained at room temperature, while fully time‐dependent crack growth data were generated under sustained loads at 650 °C. It was found that mixed time/cycle‐dependent behaviour is of most significance for this material at the temperature and frequencies studied. Data for other nickel‐based superalloys from various sources in the literature were compiled and compared with those of U720Li alloy at a given stress intensity and temperature in the mixed regime. An analysis was developed to rationalize the observed effect of frequency on fatigue crack growth rate.

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Objective  To evaluate bladder function in infants and children with no apparent voiding symptoms. Subjects and methods  The study included 83 infants and children (51 boys and 32 girls, aged 3 days to 12 years) with no neurological and lower urinary tract pathology but who had undergone or were about to undergo surgery for upper urinary tract or other pathology. They were evaluated using slow‐filling cystometry, with simultaneous electromyography recorded using surface electrodes on the perineum. The voiding variables were compared among groups categorized by age, sex and body weight. Results  In boys and girls, respectively, the mean (sd) post‐void residual urine volume (PVR) was 6.3 (3.9) and 5.4 (4.8) mL, the maximum detrusor pressure during voiding was 66.1 (13.1) and 56.6 (14.7) cmH2O and the maximum voiding pressure was 73.9 (16.6) and 62.7 (16.2) cmH2O. There was no significant difference in these variables between the sexes or between infants and children (P>0.05). Detrusor instability (DI) was apparent in nine of 83 (10.8%) infants and children and occurred in the late filling phase. Bladder capacity increased with age and body weight (from 30 mL in neonates to 350 mL in 12‐year‐old children), and mean (sd) bladder compliance increased with age, from 3.6 (0.5) mL/cmH2O in infants to 13.3 (3.0) mL/cmH2O in older children, at a filling rate of 5–7 mL/min. Conclusions  In these infants and children with no apparent voiding symptoms, most bladders were stable, DI could occur in the late filling phase of cystometry, voiding was nearly complete, the PVR being usually <10 mL, and bladder capacity increased with age and body weight.

Aquaporins are integral membrane proteins that facilitate the diffusion of water and other small, uncharged solutes across the cellular membrane and are widely distributed in organisms from humans to bacteria. However, the characteristics of prokaryotic aquaporins remain largely unknown. We investigated the distribution and sequence characterization of aquaporins in prokaryotic organisms and summarized the transport characteristics, physiological functions, and regulatory mechanisms of prokaryotic aquaporins. Aquaporin homologues were identified in 3315 prokaryotic genomes retrieved from the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, but the protein clustering pattern is not completely congruent with the phylogeny of the species that carry them. Moreover, prokaryotic aquaporins display diversified aromatic/arginine constriction region (ar/R) amino acid compositions, implying multiple functions. The typical water and glycerol transport characterization, physiological functions, and regulations have been extensively studied in Escherichia coli AqpZ and GlpF. A Streptococcus aquaporin has recently been verified to facilitate the efflux of endogenous H2O2, which not only contributes to detoxification but also to species competitiveness, improving our understanding of prokaryotic aquaporins. Furthermore, recent studies revealed novel regulatory mechanisms of prokaryotic aquaporins at post-translational level. Thus, we propose that intensive investigation on prokaryotic aquaporins would extend the functional categories and working mechanisms of these ubiquitous, intrinsic membrane proteins.