The incorporation of fly ash (FA) and wood ash (WA) in concrete as supplementary cementitious materials (SCM) was studied. The chemical composition of ordinary Portland cement, FA and WA was determined according to ASTM C-114. SEM and optical microscopy were used for the analysis of concrete. Setting time, compressive strength, water absorption and acid resistance of the concrete with different percentages of SCM ranging from 0 to 60% were evaluated. The results obtained showed that setting time and rate of water absorption increased with the increase in percentage of SCM. After 7 and 28 days, the compressive strength of concrete with 20% FA as SCM was higher than that with substitution with 20% WA. Resistance of concrete against sulphate attack increased with an increase in the percentage of FA. It was found that incorporating more than 20% WA resulted in a decrease in sulphate attack resistance.
ABSTRACT:To evaluate the asthenopic symptoms in smartphone users, a study was carried out in the College of Ophthalmology and Allied Vision Sciences (Mayo Hospital) Lahore from May to July 2018. This Cross-Sectional study was done with 250 people both from medical and non-medical backgrounds. In the study, out of 250 cases 138 (55.2%) were related to non-medical (university students of different disciplines) and the rest 112 individuals (44.8%) belonged to the medical field. Individuals of the average age of 26.91 ± 3.90 years were considered that had been using the smartphone for the last one year. Eye-problems like headaches, eye strain, double vision, redness, watery eyes, and blurred vision were recorded in 202 (80.8%) cases. Data were analyzed using Chisquare and Fisher's exact test methods. SPSS (version 21) was used and significant (p < 0.05) differences were found in symptoms that were significantly associated with age and smartphone usage time. It was concluded by the study that asthenopic symptoms were mostly found in adults who were using smartphones for more than 3-4 hours per day without any break, whether they belonged to the medical or non-medical field.
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