Izaz Ahmad - Academia.edu (original) (raw)

Papers by Izaz Ahmad

Annals of medicine and surgery, Apr 12, 2023

Sir Syed University Research Journal of Engineering & Technology

Waste Polyvinyl Chloride (PVC) pipes from sewerage system, bottles, credit cards etc. is a non-bi... more Waste Polyvinyl Chloride (PVC) pipes from sewerage system, bottles, credit cards etc. is a non-biodegradable material and adds to the quantity of solid wastes on annual basis. This study aims at its useful deployment as an additive to the bitumen which is used to construct pavements. Waste PVC pipes when used as a modifier in bituminous mixtures, satisfied the requirements as per the standards as indicated by the results. The properties of bitumen mixed with PVC were studied and compared with those of the ordinary bitumen. The performance characteristics of the the conventional and modified bituminous mixes were investigated and comparative study was carried out. It was shown by the results that waste PVC has got no issue when utilized in road construction. Flow and Stability of the mix was found to be within the acceptable limits after the PVC waste pipes have been incorporated. On the basis of experimental work it is concluded that the asphalt mixtures with waste PVC modifier can ...

Annals of Medicine & Surgery

Science of Advanced Materials

This study investigates the resistance of concrete to Rapid Chloride ions Penetration (RCP) as an... more This study investigates the resistance of concrete to Rapid Chloride ions Penetration (RCP) as an indirect measure of the concrete’s durability. The RCP resistance of concrete is modelled in multi-expression programming approach using different input variables, such as, age of concrete, amount of binder, fine aggregate, coarse aggregate, water to binder ratio, metakaolin content and the compressive strength (CS) of concrete. The parametric investigation was carried out by varying the hyperparameters, i.e., number of subpopulations Nsub, subpopulation size Ssize, crossover probability Cprob, mutation probability Mprob, tournament size Tsize, code length Cleng, and number of generations Ngener to get an optimum model. The performance of all the 29 number of trained models were assessed by comparing mean absolute error (MAE) values. The optimum model was obtained for Nsub = 50, Ssize = 100, Cprob = 0.9, Mprob = 0.01, Tsize = 9, Cleng = 100, and Ngener = 300 with MAE of 279.17 in case o...

Materials

This study aimed to determine how radiation attenuation would change when the thickness, density,... more This study aimed to determine how radiation attenuation would change when the thickness, density, and compressive strength of clay bricks, modified with partial replacement of clay by fly ash, iron slag, and wood ash. To conduct this investigation, four distinct types of bricks—normal, fly ash-, iron slag-, and wood ash-incorporated bricks were prepared by replacing clay content with their variable percentages. Additionally, models for predicting the radiation-shielding ability of bricks were created using gene expression programming (GEP) and artificial neural networks (ANN). The addition of iron slag improved the density and compressive strength of bricks, thus increasing shielding capability against gamma radiation. In contrast, fly ash and wood ash decreased the density and compressive strength of burnt clay bricks, leading to low radiation shielding capability. Concerning the performance of the Artificial Intelligence models, the root mean square error (RMSE) was determined as ...

Materials

Concrete is an economical and efficient material for attenuating radiation. The potential of conc... more Concrete is an economical and efficient material for attenuating radiation. The potential of concrete in attenuating radiation is attributed to its density, which in turn depends on the mix design of concrete. This paper presents the findings of a study conducted to evaluate the radiation attenuation with varying water-cement ratio (w/c), thickness, density, and compressive strength of concrete. Three different types of concrete, i.e., normal concrete, barite, and magnetite containing concrete, were prepared to investigate this study. The radiation attenuation was calculated by studying the dose absorbed by the concrete and the linear attenuation coefficient. Additionally, artificial neural network (ANN) and gene expression programming (GEP) models were developed for predicting the radiation shielding capacity of concrete. A correlation coefficient (R), mean absolute error (MAE), and root mean square error (RMSE) were calculated as 0.999, 1.474 mGy, 2.154 mGy and 0.994, 5.07 mGy, 5....

Materials

Steel fibers are widely extracted from scrap tyres, causing environmental concerns. This paper pr... more Steel fibers are widely extracted from scrap tyres, causing environmental concerns. This paper presents the use of steel fibers in variable proportions extracted from scrap tyres. The enhancement of the confinement was envisaged through the addition of steel fibers obtained from scrap tyres. The study included an experimental program for the development of constitutive material models for ordinary Portland cement (OPC) concrete and concrete with added steel fibers. A mix design was carried out for OPC, targeting a compressive strength of 3000 psi. Steel fibers were added to OPC in ratios of 1.0% to 3.0%, with an increment of 0.5%. Concrete columns, with cross-sectional dimensions of 6 × 6 inches and a length of 30 inches, were cast with both OPC and fiber-reinforced concrete. The column confinement was evaluated with a different spacing of ties (3- and 4-inch center-to-center). Compression tests on the concrete columns indicate that the addition of steel fibers to a concrete matrix ...

BMC Infectious Diseases, 2022

Background There was a lack of information about prognostic accuracy of time to sputum culture co... more Background There was a lack of information about prognostic accuracy of time to sputum culture conversion (SCC) in forecasting cure among extensively drug-resistant tuberculosis (XDR-TB) patients. Therefore, this study evaluated the prognostic accuracy of SCC at various time points in forecasting cure among XDR-TB patients. Methods This retrospective observational study included 355 eligible pulmonary XDR-TB patients treated at 27 centers in Pakistan between 01-05-2010 and 30-06-2017. The baseline and follow-up information of patients from treatment initiation until the end of treatment were retrieved from electronic nominal recording and reporting system. Time to SCC was analyzed by Kaplan–Meier method, and differences between groups were compared through log-rank test. Predictors of time to SCC and cure were respectively evaluated by multivariate Cox proportional hazards and binary logistic regression analyses. A p-value < 0.05 was considered statistically significant. Results ...

BMC Infectious Diseases, 2021

Background There was a complete lack of information about the treatment outcomes of rifampicin/mu... more Background There was a complete lack of information about the treatment outcomes of rifampicin/multidrug resistant (RR/MDR) childhood TB patients (age ≤ 14 years) from Pakistan, an MDR-TB 5th high burden country. Therefore, this study evaluated the socio-demographic characteristics, drug resistance pattern, treatment outcomes and factors associated with unsuccessful outcomes among childhood RR/MDR-TB patients in Pakistan. Methods This was a multicentre retrospective record review of all microbiologically confirmed childhood RR/MDR-TB patients (age ≤ 14 years) enrolled for treatment at seven units of programmatic management of drug-resistant TB (PMDT) in Pakistan. The baseline and follow-up information of enrolled participants from treatment initiation until the end of treatment were retrieved from electronic nominal recording and reporting system. World Health Organization (WHO) defined criterion was used for deciding treatment outcomes. The outcomes of “cured” and “treatment comple...

Civil Engineering Journal, 2021

Impacts of climate change on streamflow have long been an issue of concern for water experts. The... more Impacts of climate change on streamflow have long been an issue of concern for water experts. The main aim of this study is to assess the response of streamflow to precipitation and air temperature. In this study elasticity model was used to compute the precipitation and air temperature elasticity of 6 major rivers in Khyber-Pakhtunkhwa (KP) Province, Pakistan. In contrast to temperature elasticity estimator, box plots of precipitation elasticity estimator have low range and standard deviation leading to greater central affinity which produces valid, appropriate, and statistically significant elasticity results. Precipitation is positively correlated with streamflow while the air temperature is both positively and negatively linked with streamflow. 10% variation in precipitation and air temperature produces 12 to 20% and 8 to 18% change in streamflow, respectively. The sensitivity of streamflow to air temperature is higher as compared to precipitation. This research work shows that ...

Civil Engineering Journal, 2021

Understanding the influence of various variables on surface water quality is extremely important ... more Understanding the influence of various variables on surface water quality is extremely important for protecting ecosystem health. The principal aim of this study is to assess the direct (DE), indirect (IE) and total effects (TE) of socio-economic, terrestrial and hydrological factors on surface water quality via path analysis through the lens of 15 sub-basins located on Indus basin, Pakistan. Four path models were selected based on Comparative Fit Index (CFI) = 0.999 value. First path model showed that rangelands having low population density decline river runoff which decreases instream Electrical Conductivity (EC) because of lower anthropogenic activities. Second path model depicted that croplands having higher population density enhance river runoff due to irrigation tail water discharge which decline instream EC because of dilution. Third path model showed that croplands with higher population density enhance river runoff which increases instream NO3 concentration because of uns...

SSRN Electronic Journal, 2021

Journal of Infection and Public Health, 2019

The American journal of tropical medicine and hygiene, Jan 2, 2018

To evaluate the predictive value of time to sputum culture conversion (SCC) in predicting cure an... more To evaluate the predictive value of time to sputum culture conversion (SCC) in predicting cure and factors associated with time to SCC and cure in multidrug-resistant tuberculosis (MDR-TB) patients, a retrospective study was conducted at programmatic management unit of drug resistant tuberculosis (TB), Peshawar. A total of 428 pulmonary MDR-TB patients enrolled at the study site from January 1, 2012 to August 31, 2014 were followed until treatment outcome was recorded. Survival analysis using Cox proportional hazards model and multivariate binary logistic regression were, respectively, used to identify factors associated with time to SCC and cure. A value < 0.05 was considered statistically significant. Overall, 90.9% patients achieved SCC, and 76.9% were cured. Previous use of second-line drugs (SLDs) (hazard ratio [HR] = 0.637; 95% confidence interval [CI] = 0.429-0.947), ofloxacin resistance (HR = 0.656; 95% CI = 0.522-0.825) and lung cavitation (HR = 0.744; 95% CI = 0.595-0.9...

Annals of medicine and surgery, Apr 12, 2023

Sir Syed University Research Journal of Engineering & Technology

Waste Polyvinyl Chloride (PVC) pipes from sewerage system, bottles, credit cards etc. is a non-bi... more Waste Polyvinyl Chloride (PVC) pipes from sewerage system, bottles, credit cards etc. is a non-biodegradable material and adds to the quantity of solid wastes on annual basis. This study aims at its useful deployment as an additive to the bitumen which is used to construct pavements. Waste PVC pipes when used as a modifier in bituminous mixtures, satisfied the requirements as per the standards as indicated by the results. The properties of bitumen mixed with PVC were studied and compared with those of the ordinary bitumen. The performance characteristics of the the conventional and modified bituminous mixes were investigated and comparative study was carried out. It was shown by the results that waste PVC has got no issue when utilized in road construction. Flow and Stability of the mix was found to be within the acceptable limits after the PVC waste pipes have been incorporated. On the basis of experimental work it is concluded that the asphalt mixtures with waste PVC modifier can ...

Annals of Medicine & Surgery

Science of Advanced Materials

This study investigates the resistance of concrete to Rapid Chloride ions Penetration (RCP) as an... more This study investigates the resistance of concrete to Rapid Chloride ions Penetration (RCP) as an indirect measure of the concrete’s durability. The RCP resistance of concrete is modelled in multi-expression programming approach using different input variables, such as, age of concrete, amount of binder, fine aggregate, coarse aggregate, water to binder ratio, metakaolin content and the compressive strength (CS) of concrete. The parametric investigation was carried out by varying the hyperparameters, i.e., number of subpopulations Nsub, subpopulation size Ssize, crossover probability Cprob, mutation probability Mprob, tournament size Tsize, code length Cleng, and number of generations Ngener to get an optimum model. The performance of all the 29 number of trained models were assessed by comparing mean absolute error (MAE) values. The optimum model was obtained for Nsub = 50, Ssize = 100, Cprob = 0.9, Mprob = 0.01, Tsize = 9, Cleng = 100, and Ngener = 300 with MAE of 279.17 in case o...

Materials

This study aimed to determine how radiation attenuation would change when the thickness, density,... more This study aimed to determine how radiation attenuation would change when the thickness, density, and compressive strength of clay bricks, modified with partial replacement of clay by fly ash, iron slag, and wood ash. To conduct this investigation, four distinct types of bricks—normal, fly ash-, iron slag-, and wood ash-incorporated bricks were prepared by replacing clay content with their variable percentages. Additionally, models for predicting the radiation-shielding ability of bricks were created using gene expression programming (GEP) and artificial neural networks (ANN). The addition of iron slag improved the density and compressive strength of bricks, thus increasing shielding capability against gamma radiation. In contrast, fly ash and wood ash decreased the density and compressive strength of burnt clay bricks, leading to low radiation shielding capability. Concerning the performance of the Artificial Intelligence models, the root mean square error (RMSE) was determined as ...

Materials

Concrete is an economical and efficient material for attenuating radiation. The potential of conc... more Concrete is an economical and efficient material for attenuating radiation. The potential of concrete in attenuating radiation is attributed to its density, which in turn depends on the mix design of concrete. This paper presents the findings of a study conducted to evaluate the radiation attenuation with varying water-cement ratio (w/c), thickness, density, and compressive strength of concrete. Three different types of concrete, i.e., normal concrete, barite, and magnetite containing concrete, were prepared to investigate this study. The radiation attenuation was calculated by studying the dose absorbed by the concrete and the linear attenuation coefficient. Additionally, artificial neural network (ANN) and gene expression programming (GEP) models were developed for predicting the radiation shielding capacity of concrete. A correlation coefficient (R), mean absolute error (MAE), and root mean square error (RMSE) were calculated as 0.999, 1.474 mGy, 2.154 mGy and 0.994, 5.07 mGy, 5....

Materials

Steel fibers are widely extracted from scrap tyres, causing environmental concerns. This paper pr... more Steel fibers are widely extracted from scrap tyres, causing environmental concerns. This paper presents the use of steel fibers in variable proportions extracted from scrap tyres. The enhancement of the confinement was envisaged through the addition of steel fibers obtained from scrap tyres. The study included an experimental program for the development of constitutive material models for ordinary Portland cement (OPC) concrete and concrete with added steel fibers. A mix design was carried out for OPC, targeting a compressive strength of 3000 psi. Steel fibers were added to OPC in ratios of 1.0% to 3.0%, with an increment of 0.5%. Concrete columns, with cross-sectional dimensions of 6 × 6 inches and a length of 30 inches, were cast with both OPC and fiber-reinforced concrete. The column confinement was evaluated with a different spacing of ties (3- and 4-inch center-to-center). Compression tests on the concrete columns indicate that the addition of steel fibers to a concrete matrix ...

BMC Infectious Diseases, 2022

Background There was a lack of information about prognostic accuracy of time to sputum culture co... more Background There was a lack of information about prognostic accuracy of time to sputum culture conversion (SCC) in forecasting cure among extensively drug-resistant tuberculosis (XDR-TB) patients. Therefore, this study evaluated the prognostic accuracy of SCC at various time points in forecasting cure among XDR-TB patients. Methods This retrospective observational study included 355 eligible pulmonary XDR-TB patients treated at 27 centers in Pakistan between 01-05-2010 and 30-06-2017. The baseline and follow-up information of patients from treatment initiation until the end of treatment were retrieved from electronic nominal recording and reporting system. Time to SCC was analyzed by Kaplan–Meier method, and differences between groups were compared through log-rank test. Predictors of time to SCC and cure were respectively evaluated by multivariate Cox proportional hazards and binary logistic regression analyses. A p-value < 0.05 was considered statistically significant. Results ...

BMC Infectious Diseases, 2021

Background There was a complete lack of information about the treatment outcomes of rifampicin/mu... more Background There was a complete lack of information about the treatment outcomes of rifampicin/multidrug resistant (RR/MDR) childhood TB patients (age ≤ 14 years) from Pakistan, an MDR-TB 5th high burden country. Therefore, this study evaluated the socio-demographic characteristics, drug resistance pattern, treatment outcomes and factors associated with unsuccessful outcomes among childhood RR/MDR-TB patients in Pakistan. Methods This was a multicentre retrospective record review of all microbiologically confirmed childhood RR/MDR-TB patients (age ≤ 14 years) enrolled for treatment at seven units of programmatic management of drug-resistant TB (PMDT) in Pakistan. The baseline and follow-up information of enrolled participants from treatment initiation until the end of treatment were retrieved from electronic nominal recording and reporting system. World Health Organization (WHO) defined criterion was used for deciding treatment outcomes. The outcomes of “cured” and “treatment comple...

Civil Engineering Journal, 2021

Impacts of climate change on streamflow have long been an issue of concern for water experts. The... more Impacts of climate change on streamflow have long been an issue of concern for water experts. The main aim of this study is to assess the response of streamflow to precipitation and air temperature. In this study elasticity model was used to compute the precipitation and air temperature elasticity of 6 major rivers in Khyber-Pakhtunkhwa (KP) Province, Pakistan. In contrast to temperature elasticity estimator, box plots of precipitation elasticity estimator have low range and standard deviation leading to greater central affinity which produces valid, appropriate, and statistically significant elasticity results. Precipitation is positively correlated with streamflow while the air temperature is both positively and negatively linked with streamflow. 10% variation in precipitation and air temperature produces 12 to 20% and 8 to 18% change in streamflow, respectively. The sensitivity of streamflow to air temperature is higher as compared to precipitation. This research work shows that ...

Civil Engineering Journal, 2021

Understanding the influence of various variables on surface water quality is extremely important ... more Understanding the influence of various variables on surface water quality is extremely important for protecting ecosystem health. The principal aim of this study is to assess the direct (DE), indirect (IE) and total effects (TE) of socio-economic, terrestrial and hydrological factors on surface water quality via path analysis through the lens of 15 sub-basins located on Indus basin, Pakistan. Four path models were selected based on Comparative Fit Index (CFI) = 0.999 value. First path model showed that rangelands having low population density decline river runoff which decreases instream Electrical Conductivity (EC) because of lower anthropogenic activities. Second path model depicted that croplands having higher population density enhance river runoff due to irrigation tail water discharge which decline instream EC because of dilution. Third path model showed that croplands with higher population density enhance river runoff which increases instream NO3 concentration because of uns...

SSRN Electronic Journal, 2021

Journal of Infection and Public Health, 2019

The American journal of tropical medicine and hygiene, Jan 2, 2018

To evaluate the predictive value of time to sputum culture conversion (SCC) in predicting cure an... more To evaluate the predictive value of time to sputum culture conversion (SCC) in predicting cure and factors associated with time to SCC and cure in multidrug-resistant tuberculosis (MDR-TB) patients, a retrospective study was conducted at programmatic management unit of drug resistant tuberculosis (TB), Peshawar. A total of 428 pulmonary MDR-TB patients enrolled at the study site from January 1, 2012 to August 31, 2014 were followed until treatment outcome was recorded. Survival analysis using Cox proportional hazards model and multivariate binary logistic regression were, respectively, used to identify factors associated with time to SCC and cure. A value < 0.05 was considered statistically significant. Overall, 90.9% patients achieved SCC, and 76.9% were cured. Previous use of second-line drugs (SLDs) (hazard ratio [HR] = 0.637; 95% confidence interval [CI] = 0.429-0.947), ofloxacin resistance (HR = 0.656; 95% CI = 0.522-0.825) and lung cavitation (HR = 0.744; 95% CI = 0.595-0.9...