Effect of Alkali-Silica Reaction on Confined Reinforced Concrete

Alkali-silica reaction (ASR), which was recently discovered in nuclear power plant structures commonly without shear reinforcement, has previously been shown to induce anisotropic expansion in confined concrete. A large-scale testing program on alkali silica reaction (ASR)-affected concrete structural members without shear reinforcement representative of structural members found in nuclear power plants is presented. Three large concrete specimens with ASR and varying levels of confinement were monitored in accelerated testing conditions.Strong anisotropic expansion and oriented ASR-induced cracking resulting from the confinement effect caused by the reinforcement layout and additional structural boundary conditions were observed. Surface cracking is not indicative of internal ASR-induced damage/expansion.The fracture properties (strength, stiffness, and specific fracture energy) of ASR-induced anisotropically-damaged concrete specimens were quantified by varying both the damage level and relative direction of the ASR-induced cracking orientation against the loading direction corresponding to the fracture propagation. The effect of different orientations (0, 45, and 90 degrees relative to the notch of the specimen) of expected ASR-induced cracks on the fracture properties was investigated using a wedge-splitting test (WST). Specimens without ASR expansion generally showed the highest fracture properties; however, the specific fracture energy was highest for ASR-affected specimens in which the expected orientation of ASR-induced cracks was perpendicular to the WST specimen notch. Specimens in which the ASR-induced cracks were parallel to the notch exhibited the lowest strength and fracture energy.A new model was developed for predicting the expansion of concrete structures affected by alkali-silica reaction. The model includes a novel combination of existing models as a alkali-silica reaction advancement model, a novel casting direction anisotropic expansion model, a novel stress-dependent anisotropic expansion model, and a novel material property evolution model dependent on the degree of ASR expansion. The calibrated model was validated in predicting the ASR-expansion of the large-scale reinforced concrete specimens with confinement of this study. The results of this study highlight the need for additional research to be conducted to investigate a possible size effect for very-large concrete specimens affected by ASR and the need for additional research on multi-axially loaded concrete specimens with ASR

Assessing Heat Management Practices in High Tunnels to Improve the Production of Romaine Lettuce

A three-year experiment evaluated the beneficial effects of independent and combined practices on thermal conditions inside high tunnels (HTs), and further investigated the temperature impacts on lettuce production. Specific practices included mulching (polyethylene and biodegradable plastic films, and vegetative), row covers, cover crops, and irrigation with collected rainwater or city water. The study conducted in eastern Tennessee was a randomized complete block split-split plot design (RCBD) with three HTs used as replicates to determine fall lettuce weight (g/plant) and lettuce survival (#/plot), and the changes in soil and air temperature. The black and clear plastic mulches worked best for increasing plant weight, but when compared to the bare ground, the higher soil temperature from the plastics may have caused a significant reduction in lettuce plants per plot. Moreover, the biodegradable mulch did not generate as much soil warming as black polyethylene, yet total lettuce marketable yield was statistically similar to that for the latter mulch treatment; while the white spunbond reduced plant weight when compared with black plastic. Also, row covers provided an increased nighttime air temperature that increased soil temperature, hence significantly increased lettuce production. Cover crops reduced lettuce yield, but increased soil temperatures. Additionally, irrigation using city water warmed the soil and provided more nutrients for increased lettuce production over rainwater irrigation

Burosumab in management of X-linked hypophosphataemia: a retrospective cohort study of growth and serum phosphate levels

BACKGROUND: Burosumab, an antifibroblast growth factor 23 monoclonal antibody, improves rickets severity, symptoms and growth in children with X-linked hypophosphataemia (XLH) followed up to 64 weeks in clinical trials. International dosing guidance recommends targeting normal serum phosphate concentration; however, some children may not achieve this despite maximal dosing. This study compares clinical outcomes in children with XLH on long-term burosumab treatment who achieved normal phosphate versus those who did not. METHODS: Single-centre retrospective review of a large paediatric cohort with XLH treated with burosumab. We evaluated growth and biochemical markers of bone health in those who did compared with those who did not achieve normal plasma phosphate concentration. RESULTS: Fifty-five children with XLH with median age of 11.7 (IQR 6.8-15.5) years were included. 27 (49%) had low plasma phosphate concentration, and 27 (49%) had normal phosphate after a median burosumab treatment duration of 3.3 (IQR 2.6-3.7) years. 1 (2%) did not have a recent phosphate level recorded. No difference in growth was found between normal and abnormal phosphate groups (p=0.9). CONCLUSIONS: Young children with XLH experience sustained growth on long-term burosumab treatment, although without normal plasma phosphate concentration in many. Consideration should be made to changing burosumab dosing recommendations to target normalisation of alkaline phosphatase, as opposed to plasma phosphate concentration

Damage Mechanism Evaluation of Large-Scale Concrete Structures Affected by Alkali-Silica Reaction Using Pattern Recognition

Alkali-silica reaction has caused damage to concrete structures, endangering structural serviceability and integrity. This is of concern in sensitive structures such as nuclear power plants. In this study, acoustic emission (AE) was employed as a structural health monitoring strategy in large-scale, reinforced concrete specimens affected by alkali-silica reaction with differing boundary conditions resembling the common conditions found in nuclear containments. An agglomerative hierarchical algorithm was utilized to classify the AE data based on energy-frequency based features. The AE signals were transferred into the frequency domain and the energies in several frequency bands were calculated and normalized to the total energy of signals. Principle component analysis was used to reduce feature redundancy. Then the selected principal components were considered as features in an input of the pattern recognition algorithm. The sensor located in the center of the confined specimen registered the largest portion of AE energy release, while in the unconfined specimen the energy is distributed more uniformly. This confirms the results of the volumetric strain, which shows that the expansion in the confined specimen is oriented along the thickness of the specimen

Perioperative fluid management and associated complications in children receiving kidney transplants in the UK

Background: Intravenous fluid administration is an essential part of perioperative care for children receiving a kidney transplant. There is a paucity of evidence to guide optimal perioperative fluid management. This study aimed to identify the volume of perioperative fluids administered across 5 UK paediatric kidney transplant centres and explore associations between fluid volume administered, graft function, and fluid-related adverse events. Methods: Data were collected from five UK paediatric kidney transplant centres on perioperative fluid volumes administered, and incidence of pulmonary oedema, systemic hypertension, and requirement for intensive care support. Children < 18 years of age who received a kidney-only transplant between 1st January 2020 and 31st December 2021 were included. Results: Complete data from 102 children were analysed. The median total volume of fluid administered in 72 h was 377 ml/kg (IQR 149 ml/kg) with a high degree of variability. A negative relationship between total fluid volume administered and day 7 eGFR was noted (p < 0.001). Association between urine volume post-transplant and day 7 eGFR was also negative (p < 0.001). Adverse events were frequent but no significant difference was found in the fluid volume administered to those who developed an adverse event, vs those who did not. Conclusions: This study describes a high degree of variability in perioperative fluid volumes administered to children receiving kidney transplants. Both fluid volume and urine output were negatively associated with short-term graft function. These data contrast traditional interpretation of high urine output as a marker of graft health, and highlight the need for prospective clinical trials to optimise perioperative fluid administration for this group. Graphical Abstract: A higher resolution version of the Graphical abstract is available as Supplementary information [Figure not available: see fulltext.]