Improving the Mechanical, Corrosion Resistance, Microstructural and Environmental Performance of Recycled Aggregate Concrete Using Ceramic Waste Powder as an Alternative to Cement

This study investigates the effectiveness of replacing the cement with 0, 5, 10, 15, and 20 wt.% of ceramic waste powder (HCCP) to improve the performance of recycled aggregate concrete (RCA) prepared using 25 wt.% wall tile ceramic coarse aggregates. The slump, initial and final setting time, compressive strength, splitting tensile strength, flexural strength, electrical resistivity, bulk density, porosity, total and surface water absorption, pH level, ultrasonic pulse velocity, dynamic elastic modulus, chloride ion diffusion coefficient, chloride penetration depth, microstructure analysis, and environmental assessment properties were investigated. The results showed that replacing cement with HCCP by 5 to 20 wt.% prolonged the setting time and improved all hardened properties. The highest improvements in mechanical properties were observed at 5 wt.% HCCP, with increasing rates of 26.5%, 22%, and 22.4% at 90 days for compressive strength, tensile strength, and flexural strength, respectively. On the other hand, the optimum enhancement for the durability, microstructural, and environmental efficiency properties was recorded at a 20 wt.% HCCP replacement rate. However, the strength at this ratio tended to decrease but remained higher than that of the control RAC. For instance, the total water absorption, surface water absorption, void ratio, chloride penetration depth, and migration coefficient were reduced by 47%, 45%, 38%, 62.3%, and 55.52%, respectively, compared to the reference sample

Fresh and hardened properties of self-compacting high performance concrete containing nano-metakaolin as a partial replacement

Abstract In this study, the effect of partial substitution of cement material with nano-materials represented by nano-metakaolin(NMK) has been studied on the fresh and hardening properties of High-Performance Self-Compacting concrete (SCHPC), where the substitution was made in different proportions, namely (1.25, 2.5 and 3.75). Four mixtures were made, the first reference and the remaining three mixtures in which the cement was partially replaced by the above mentioned proportions. Fresh characteristics represented by the Slump flow, T5 0 c m, the L- box and the V- funnel were studied. As for the hardening properties, the compression and tensile strengths were examined. We observed through practical results that the Slump flow and L- box values decrease as the percentage of partial substitution of cement to nano-metakaolin increases. Whereas, T5 0 cm and T v It increases with the increase in the partial substitution rate for cement with nanometakaolin. As for compressive strength and tensile strength, it increases with the increase in the percentage of partial replacement of cement with nano-metakaolin.</jats:p

The effect of changing the wavelength on some of the optical properties of copper nitrate water

Abstract In this work, some of optical properties for ( Cu(NO3)2.6H2O), such as (transmission, reflectance, absorbance, damping coefficient, refractive index, Brewster angle and critical angle ) have been calculated with (0.1-0.9)gm/ml concentration at (242,449,631,978) nm wave length at 250c. the results showed the optical properties were increased with concentration and wave length have been used, except transmission and critical angle which decreased with the same concentration and wave length when as, the same optical properties have higher values, while the transmission and critical angle were decreased at the case wave length.</jats:p

Pancreatic surgery outcomes: multicentre prospective snapshot study in 67 countries

Background: Pancreatic surgery remains associated with high morbidity rates. Although postoperative mortality appears to have improved with specialization, the outcomes reported in the literature reflect the activity of highly specialized centres. The aim of this study was to evaluate the outcomes following pancreatic surgery worldwide. Methods: This was an international, prospective, multicentre, cross-sectional snapshot study of consecutive patients undergoing pancreatic operations worldwide in a 3-month interval in 2021. The primary outcome was postoperative mortality within 90 days of surgery. Multivariable logistic regression was used to explore relationships with Human Development Index (HDI) and other parameters. Results: A total of 4223 patients from 67 countries were analysed. A complication of any severity was detected in 68.7 per cent of patients (2901 of 4223). Major complication rates (Clavien–Dindo grade at least IIIa) were 24, 18, and 27 per cent, and mortality rates were 10, 5, and 5 per cent in low-to-middle-, high-, and very high-HDI countries respectively. The 90-day postoperative mortality rate was 5.4 per cent (229 of 4223) overall, but was significantly higher in the low-to-middle-HDI group (adjusted OR 2.88, 95 per cent c.i. 1.80 to 4.48). The overall failure-to-rescue rate was 21 per cent; however, it was 41 per cent in low-to-middle- compared with 19 per cent in very high-HDI countries. Conclusion: Excess mortality in low-to-middle-HDI countries could be attributable to failure to rescue of patients from severe complications. The authors call for a collaborative response from international and regional associations of pancreatic surgeons to address management related to death from postoperative complications to tackle the global disparities in the outcomes of pancreatic surgery (NCT04652271; ISRCTN95140761)

Pancreatic surgery outcomes: multicentre prospective snapshot study in 67 countries

Background: Pancreatic surgery remains associated with high morbidity rates. Although postoperative mortality appears to have improved with specialization, the outcomes reported in the literature reflect the activity of highly specialized centres. The aim of this study was to evaluate the outcomes following pancreatic surgery worldwide.Methods: This was an international, prospective, multicentre, cross-sectional snapshot study of consecutive patients undergoing pancreatic operations worldwide in a 3-month interval in 2021. The primary outcome was postoperative mortality within 90 days of surgery. Multivariable logistic regression was used to explore relationships with Human Development Index (HDI) and other parameters.Results: A total of 4223 patients from 67 countries were analysed. A complication of any severity was detected in 68.7 percent of patients (2901 of 4223). Major complication rates (Clavien-Dindo grade at least IIIa) were 24, 18, and 27 percent, and mortality rates were 10, 5, and 5 per cent in low-to-middle-, high-, and very high-HDI countries respectively. The 90-day postoperative mortality rate was 5.4 per cent (229 of 4223) overall, but was significantly higher in the low-to-middle-HDI group (adjusted OR 2.88, 95 per cent c.i. 1.80 to 4.48). The overall failure-to-rescue rate was 21 percent; however, it was 41 per cent in low-to-middle-compared with 19 per cent in very high-HDI countries.Conclusion: Excess mortality in low-to-middle-HDI countries could be attributable to failure to rescue of patients from severe complications. The authors call for a collaborative response from international and regional associations of pancreatic surgeons to address management related to death from postoperative complications to tackle the global disparities in the outcomes of pancreatic surgery (NCT04652271; ISRCTN95140761)