hammad khan - Academia.edu (original) (raw)

Papers by hammad khan

Research paper thumbnail of Grid Pricing: An Empirical Investigation of Market Signal Clarity

The ability of the grid marketing system for fed cattle to provide an efficient price transmissio... more The ability of the grid marketing system for fed cattle to provide an efficient price transmission mechanism is investigated. Nerlove's (1958) adaptive expectations approach is adopted to model the relationship between grid premiums (discounts) and the weekly relative supply of carcass quality attributes. Linear regression techniques are used to estimate Nerlove's supply response function. Granger Causality tests are conducted to investigate the relationship between grid premiums (discounts) and the relative supply of carcass quality attributes. Regression estimates and the Granger Causality tests provide empirical support for the 2005 National Beef Quality Audit call for clearer market signals.

Research paper thumbnail of Knowledge Discovery Through Text Mining in the United States Data Science

Presented at the 2017 International Conference on Knowledge Management. This presentation examine... more Presented at the 2017 International Conference on Knowledge Management. This presentation examines uses knowledge discovery and text mining to identify patterns and trends in the data science discipline by examining core course titles of the Data Science curriculum offered in the United States.

Research paper thumbnail of Coexistence of sickle cell disease and systemic lupus erythematosus is associated with quantitative and qualitative impairments in circulating regulatory B cells

Research paper thumbnail of Glycemic control and awareness of foot care in diabetic foot syndrome

INTERNATIONAL JOURNAL OF ENDOCRINOLOGY (Ukraine), 2021

Background. The chronic complications of diabetes mellitus (DM) result from a wide variety of eff... more Background. The chronic complications of diabetes mellitus (DM) result from a wide variety of effects of disease. The correlation between blood sugar level and chronic complications has been demonstrated in various studies. Patient education, risk factor management, and other preventative measures are critical elements in reducing the incidence of diabetes complications such as Diabetic Foot Syndrome (DFS). We purposed to evaluate knowledge and attitudes towards foot care amongst patients with diabetes mellitus; in addition, we investigated the correlation between glycemic control and DFS. Materials and methods. This was a descriptive cross-sectional evaluation of patients who were diagnosed with diabetes mellitus seeking outpatient medical care with data being collected through patient surveys, clinical evaluation, specialty consultation, and biochemical analysis of glycated haemoglobin (HbA1c) serum levels. The population of the study was composed of 90 patients diagnosed with DM....

Research paper thumbnail of A smarter energy management system for the realization of virtual power plants

In the current era there is a global concern about the economic downturn and a greener earth whic... more In the current era there is a global concern about the economic downturn and a greener earth which is related to a better and efficient method to generate and transmit electric power. With the advent of the plug-in electric vehicles and renewable energy generators, a smarter, more efficient and customer-friendly power grid is essential. Problems of increased carbon emissions and shortage of energy production are answered by the inclusion of the dispersed/renewable energy generation network in the current centralized grid structure, thus leading towards a decentralized grid structure. This decentralized grid structure establishes the basis of the tomorrow's "Smart Grid". The Smart Grid concept pioneers the two most researched subsystems for managing generation and loads. The first being Micro Grid, the second Virtual Power Plants. The principal difference between these two subsystems is their voltage levels, where Micro Grids deal primarily with low voltage generation sources and loads; Virtual Power Plants operate both on medium and low voltage generation sources and loads. The Virtual Power Plant concept was introduced back in 2002 and has a broader definition of control and dispatch management of generation sources and load as compared to Micro Grid. Energy management is an integral part of the power system stability, therefore in this dissertation Virtual Power Plant system is chosen as the principle model for the control and management of energy flow throughout the network. This thesis presents a smarter energy management system for Virtual Power Plants by monitoring, controlling and optimizing the generation, transmission and distribution system. The forthcoming earlier chapters of this dissertation describe the considered approach towards the design and planning of the Virtual Power Plant structure. During the design phase all the three types of distributed generation sources namely Synchronous Generators, Induction Generators and Electronically interfaced renewable energy sources are considered. Based on these generation sources, the Virtual Power Plant structure is 7

Research paper thumbnail of Understanding the knowledge, skills, and abilities (KSA) of data professionals in United States academic libraries

Research paper thumbnail of Electrochemical preparation of Nb2O5 nanochannel photoelectrodes for enhanced photoelectrocatalytic performance in removal of RR120 dye

Chemosphere, 2020

The present work describes the synthesis of niobium oxide nanochannels (Nb2O5NCs) with high surfa... more The present work describes the synthesis of niobium oxide nanochannels (Nb2O5NCs) with high surface area, porosity, photocurrent density, and photoelectrochemical stability as photocatalyst. The Nb2O5NCs were prepared by electrochemical anodization of niobium foil in different electrolytes: 1 M H2SO4 containing 0.4 wt% HF (S1); glycerol containing 0.4 M NH4F (S2); 0.25 g NH4F with 4 vol% water in glycol at 50 °C (S3); and glycerol containing 10 wt% K2HPO4, at 130 °C (S4, annealed in air; S5, annealed in N2). All the Nb2O5NCs showed well-organized arrays of nanochannels grown on the Nb foil, with tube diameters in the order S4<S2<S1<S3 and film thicknesses in the order S1<S2<S3<S4, as determined using FEG-SEM analyses. The samples were also characterized using XRD, EDX, DRS, XPS, EIS, Mott-Schottky analysis, and LSV curves. But, best results were obtained only when phosphorus (about 1% doping) was incorporated into the electrodes samples prepared in glycerol containing 10 wt% K2HPO4 at 130 °C (i.e. S4 and S5). This procedure enhances the absorption intensity in the UV-Vis regions, the conductivity, the charge carrier density, and the photocurrent density. The Nb2O5NC sample S5 was tested for the degradation of Procion Red HE-3B (RR120) dye, as a model pollutant, achieving efficient photoelectrodegradation with nearly 2 times higher mineralization efficiency compared to photolysis (PT) and photocatalysis (PC). Thus, the results indicate that the modification of Nb2O5NC thin film photoelectrodes by phosphorous doping can be a powerful and efficient alternative to usual approaches applied to the treatment of complex reactive dyes.

Research paper thumbnail of Development and characterization of regenerable chitosan-coated nickel selenide nano-photocatalytic system for decontamination of toxic azo dyes

International Journal of Biological Macromolecules, 2021

In this investigation, chitosan-coated nickel selenide nano-photocatalyst (CS-NiSe) were successf... more In this investigation, chitosan-coated nickel selenide nano-photocatalyst (CS-NiSe) were successfully prepared through the chemical reduction method. FTIR spectroscopy confirmed the synthesis of CS-NiSe nano-photocatalyst. Further, XRD analysis exhibited a monoclinic crystalline phase of photocatalyst with a crystallite size of 32 nm based on Scherer's equation. The SEM micrographs showed that the photocatalyst has an average particle size of 60 nm. The bandgap of CS-NiSe was 2.85 eV in the visible region of the spectrum. Due to this reason, the CS-NiSe was applied under solar light illumination for the photocatalytic activity of Erythrosine and Allura red dyes. The CS-NiSe presented the highest degradation efficiency of 99.53% for Erythrosine dye in optimized experimental conditions of 100 min at 30 °C, 30 ppm concentration, pH 5.0, and 0.14 g catalyst dose. For Allura red dye, a high degradation of 96.12% was attained in 120 min at pH 4.0, 100 ppm initial dye concentration, 35 °C temperature, and 0.1 g catalyst dose. The CS-NiSe showed excellent degradation efficiency and reduced to (95% for Erythrosine and 91% for Allura red dye) after five consecutive batches. Moreover, the statistical and neural network modelling analysis showed the significant influence of all studied variables on dyes degradation performance. The results demonstrated that CS-NiSe exhibited excellent photocatalytic performances for Erythrosine and Allura red dyes and could be a better photocatalyst for removing these dyes from industrial effluents.

Research paper thumbnail of Degradation of Congo red dye using ternary metal selenide-chitosan microspheres as robust and reusable catalysts

Environmental Technology & Innovation, 2021

Abstract Water pollution is a threatening environmental concern these days, which requires seriou... more Abstract Water pollution is a threatening environmental concern these days, which requires serious attention. Water is contaminated by the heavy discharge of industrial effluents containing organic wastes. Herein, this research work focused on the demand for overcoming water pollution utilizing clean and renewable energy (solar light irradiations) sources for photocatalytic degradation of Congo red (CR) dye with the help of ternary metal selenide-chitosan microspheres (ZBiSe-CM). First, zinc-bismuth-selenide nanoparticles (ZBiSe-NPs) were successfully synthesized via the solvothermal process and then supported with chitosan to prevent leaching of the catalyst. SEM micrographs showed the average size of newly synthesized nanocomposites catalysts was 30.9 nm. The average size of the ZBiSe-CM microspheres was calculated as 812 um with a spherical shape and a porous surface. The presence of prominent peaks in the EDX spectrum for bismuth, selenium, and zinc confirmed the synthesis of the nanoparticles. XRD analysis demonstrated the calculated crystallite size of ZBiSe-NPs was 27.04 nm. The photocatalytic behavior of the catalyst was studied at optimized experimental conditions. The ZBiSe-NPs showed high photocatalytic degradation efficiency (up to 99.63%) for 40 ppm concentration of CR at catalyst dosage 0.225 g, pH 8.0, and temperature 36-38 °C for 2 h of solar light illumination. Photodegradation of CR dye in the presence of ZBiSe-CM follows pseudo-first-order kinetics and the ZBiSe-CM degraded CR dye in five consecutive cycles with high decontamination efficiency. The newly synthesized ternary metal selenide-chitosan microspheres could be used for the decontamination of dyes from industrial wastewater.

Research paper thumbnail of Acute otitis externa: Consensus definition, diagnostic criteria and core outcome set development

PLOS ONE, 2021

Objective Evidence for the management of acute otitis externa (AOE) is limited, with unclear diag... more Objective Evidence for the management of acute otitis externa (AOE) is limited, with unclear diagnostic criteria and variably reported outcome measures that may not reflect key stakeholder priorities. We aimed to develop 1) a definition, 2) diagnostic criteria and 3) a core outcome set (COS) for AOE. Study design COS development according to Core Outcome Measures in Effectiveness Trials (COMET) methodology and parallel consensus selection of diagnostic criteria/definition. Setting Stakeholders from the United Kingdom. Subjects and methods Comprehensive literature review identified candidate items for the COS, definition and diagnostic criteria. Nine individuals with past AOE generated further patient-centred candidate items. Candidate items were rated for importance by patient and professional (ENT doctors, general practitioners, microbiologists, nurses, audiologists) stakeholders in a three-round online Delphi exercise. Consensus items were grouped to form the COS, diagnostic crite...

Research paper thumbnail of Self-doping of Nb2O5NC by cathodic polarization for enhanced conductivity properties and photoelectrocatalytic performance

Chemosphere, 2021

A simple novel electrochemical reduction approach was developed for the self-doping of Nb4+ in ni... more A simple novel electrochemical reduction approach was developed for the self-doping of Nb4+ in niobium oxide nanochannels (Nb2O5NC), changing the conductivity, optical properties, and photocatalytic properties of the material. Nb2O5NC was synthesized using different electrolytes: 0.4 wt% HF in 1 M H2SO4 (EI), 0.4 M NH4F in glycerol (EII), and 0.25 g NH4F with 4 vol% water in glycol at 50 °C (EIII). Field emission scanning electron microscopy (FEG-SEM) analysis showed well-organized arrays of Nb2O5 nanochannels produced on Nb foil, with varying tube diameters in the order EII < EI < EIII and film thickness in the order EI < EII < EIII, which drastically affected the photocurrent vs. potential curves. In order to self-dope the Nb2O5, the samples were electrochemically reduced in 0.1 M KH2PO4 buffer solution (pH 10) for 5 min, at -2.5 V vs. Ag/AgCl, resulting in the doped samples denoted P-EI, P-EII, and P-EIII. The results showed that reduction of Nb5+ to Nb4+ occurred for all the Nb2O5NC samples, leading to decreased surface charge transfer resistance between the Nb2O5NC and the electrolyte, as well as increases of the charge carrier density and photocurrent for all the self-doped samples, compared to undoped samples. Sample P-EI was also tested for the degradation of reactive red 120 (RR120) dye, achieving efficient photoelectrocatalytic degradation of a 10 mg L-1 dye solution. These results reveal that the self-doping approach can enhance the photoelectrocatalytic properties of Nb2O5 photoanode, offering an alternative way for the removal of reactive dyes.

Research paper thumbnail of Modeling of photolytic degradation of sulfamethoxazole using boosted regression tree (BRT), artificial neural network (ANN) and response surface methodology (RSM); energy consumption and intermediates study

Chemosphere, 2021

This study explores the boosted regression trees (BRT), artificial neural network (ANN) and respo... more This study explores the boosted regression trees (BRT), artificial neural network (ANN) and response surface methodology (RSM) to model and optimize the operational variables for the simulation of the Photolytic degradation of Sulfamethoxazole (SMX) and concurrent total organic carbon (TOC) removal, based on the experimental data set. Four candidate variables involving initial pH (2-11), initial SMX concentration (50-200 mg L-1), temperature (15-45 °C) and time (6-120 min) were considered for simultaneous optimization of SMX and TOC degradation. The result revealed that all the three models are statistically considerable as the values of R, R2, adj-R2 are >0.85, thus be deemed to work well in data fitting, prediction, and optimization, nevertheless, the values of R, R2, adj-R2, RMSE, MAE and AAD are far better for ANN and BRT than RSM method. The ∼100% SMX degradation conditions were found to be as follows: treatment time: 25 min, pH: 2.0, temperature: 35 °C and SMX concentration: 50 mg L-1, while the maximum possible removal of TOC under the given conditions was ∼25%. The percentage contribution (PC) of each variable was deduced by ANOVA analysis of proposed quadratic models which indicated that time and pH are important factors than temperature and SMX concentration. The photolytic intermediates and inorganic ions of SMX, were identified and a potential route of transformation was also proposed.

Research paper thumbnail of Regenerable chitosan-bismuth cobalt selenide hybrid microspheres for mitigation of organic pollutants in an aqueous environment

International Journal of Biological Macromolecules, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Research paper thumbnail of Design and Analysis of a Wearable Monopole Antenna on Jeans Substrate for RFID Applications

International Journal of Wireless and Microwave Technologies, 2016

In this paper a novel rectangular C-shaped planar monopole antenna is designed and analyzed for R... more In this paper a novel rectangular C-shaped planar monopole antenna is designed and analyzed for Radio Frequency Identification (RFID) application in the licensed-free Industrial Scientific and Medical (ISM) band of 2.45 GHz. The proposed antenna uses a 1 mm thicker wearable Jeans fabric {relative permittivity, ε r =1.68 and Loss Tangent of δ=0.025} as a substrate material. For better bandwidth, and radiation efficiency the substrate is backed by a truncated copper ground plane. The antenna operate efficiently (92.85%), giving an adequate bandwidth, return-loss, gain and directivity of 12 %,-35.57 dB, 3.144 dB and 3.465 dBi, respectively. The nominated antenna is compact, low profile, and provides a better impedance matching (50.25 ohms) which results in a Voltage Standing Wave Ratio (VSWR) of 1.03. The far-field analysis is carried out via Finite Integration Technique (FIT) in CST Microwave studio.

Research paper thumbnail of Not Just a Pretty Face: Three-Dimensional Printed Custom Airway Management Devices

3D Printing and Additive Manufacturing, 2016

Three-dimensional (3D) printing, also known as additive manufacturing, is a fascinating technolog... more Three-dimensional (3D) printing, also known as additive manufacturing, is a fascinating technology that is poised to transform the practice of medicine in the 21st century. The Society for Technology in Anesthesia hosted an engineering challenge to use a 3D printer to create a customized oral airway based on a patient's anatomy. We approached this challenge in two parts. First, we identified a model for an oral airway to base our prototype. We created a 3D rendering of the customizable oral airway and designed a user interface that would accept specific measurements to create a customized oral airway. We then rendered a 3D model of the patient's airway and surrounding structures using Mimics (Materialise, Leuven, Belgium). The model was optimized for an Object Connex (Stratasys, Eden Prairie, MN), which has the capability of printing in various materials. We specified softer materials for the flexible tissues such as the tongue, palate, vocal cords, and epiglottis; a more rigid material was utilized for the supporting structures such as the mandible, nose, and bony structures. Furthermore, we printed the model in various parts, consisting of the tongue, jaw, trachea, and head/neck, that would articulate to make up the head and neck. The head and neck was one continuous part, divided sagittally at the midline, and the trachea was divided in the coronal plane. The printing process took *30 h of printing time and resulted in an anatomically correct model that included the nasopharynx, oropharynx, and trachea with an articulating mandible. We describe the process of designing and producing anatomic models for medical device prototype design. We propose a methodology of evaluating medical device prototypes using anatomically accurate models manufactured with 3D printers.

Research paper thumbnail of Accuracy of Platelet Counting by Optical and Impedance Methods in Patients with Thrombocytopaenia and Microcytosis

Sultan Qaboos University Medical Journal, 2015

Objectives: Obtaining accurate platelet counts in microcytic blood samples is challenging, even w... more Objectives: Obtaining accurate platelet counts in microcytic blood samples is challenging, even with the most reliable automated haematology analysers. The CELL-DYN ™ Sapphire (Abbott Laboratories, Chicago, Illinois, USA) analyser uses both optical density and electronic impedance methods for platelet counting. This study aimed to evaluate the accuracy of optical density and electrical impedance methods in determining true platelet counts in thrombocytopaenic samples with microcytosis as defined by low mean corpuscular volume (MCV) of red blood cells. Additionally, the impact of microcytosis on platelet count accuracy was evaluated. Methods: This study was carried out between February and December 2014 at the Haematology Laboratory of the Sultan Qaboos University Hospital in Muscat, Oman. Blood samples were collected and analysed from 189 patients with thrombocytopaenia and MCV values of <76 femtolitres. Platelet counts were tested using both optical and impedance methods. Stained peripheral blood films for each sample were then reviewed as a reference method to confirm platelet counts. Results: The platelet counts estimated by the impedance method were on average 30% higher than those estimated by the optical method (P <0.001). The estimated intraclass correlation coefficient was 0.52 (95% confidence interval: 0.41-0.62), indicating moderate reliability between the methods. The degree of agreement between methods ranged from-85.5 to 24.3 with an estimated bias of-30, suggesting that these methods generate different platelet results. Conclusion: The impedance method significantly overestimated platelet counts in microcytic and thrombocytopaenic blood samples. Further attention is therefore needed to improve the accuracy of platelet counts, particularly for patients with conditions associated with microcytosis.

Research paper thumbnail of Risk and Drawdowns

A Quantitative Approach to Building Trading Strategies, 2015

Research paper thumbnail of Case of fatal toxic epidermal necrolysis due to cardiac catheterization dye

Journal of drugs in dermatology : JDD, 2010

Cardiac catheterization is a very common procedure carried out for diagnostic as well as therapeu... more Cardiac catheterization is a very common procedure carried out for diagnostic as well as therapeutic reasons. Complications are not surprising due to the invasive nature of the procedure. Most of these complications have been seen numerous times by cardiologists who frequent the catheterization laboratory. Unfortunately, this patient experienced an extremely rare complication that ultimately resulted in his death. Here, the authors report a case of toxic epidermal necrolysis (TEN) resulting from the nonionic radiocontrast agent used in cardiac catheterization.

Research paper thumbnail of Non-invasive haemoglobin estimation in patients with thalassaemia major

Sultan Qaboos University medical journal, 2014

This study aimed to validate pulse CO-oximetry-based haemoglobin (Hb) estimation in children and ... more This study aimed to validate pulse CO-oximetry-based haemoglobin (Hb) estimation in children and adults with thalassaemia major (TM) and to determine the impact of different baseline variables on the accuracy of the estimation. This observational study was conducted over a five-week period from March to April 2012. A total of 108 patients with TM attending the daycare thalassaemia centre of a tertiary care hospital in Muscat, Oman, were enrolled. Spot (Sp) Hb measurements were estimated using a Pronto-7(®) pulse CO-oximetry device (Masimo Corp., Irvine, California, USA). These were compared to venous samples of Hb using the CELL-DYN Sapphire Hematology Analyzer (Abbott Diagnostics, Abbott Park, Illinois, USA) to determine the reference (Ref) Hb levels. A multivariable linear regression model was used to assess the impact of baseline variables such as age, gender, weight, height, Ref Hb and blood pressure on the Hb estimations. Of the 108 enrolled patients, there were 54 males and 54...

Research paper thumbnail of Rapid start-up and efficient long-term nitritation of low strength ammonium wastewater with a sequencing batch reactor containing immobilized cells

Water Science & Technology, 2014

Major concerns about nitritation of low-strength ammonium wastewaters include low ammonium loadin... more Major concerns about nitritation of low-strength ammonium wastewaters include low ammonium loading rates (ALRs) (usually below 0.2 kg/m3-d) and uncertainty with the long-term stability of the process. The purpose of this study was to test a sequencing batch reactor filled with cell-immobilized polyethylene glycol (PEG) pellets (∼2 mm in size) to see if it could achieve efficient and stable nitritation under various environmental conditions. The sequencing batch reactor (SBR) was fed with synthetic ammonium wastewater of 30 ± 2 mg-N/L and pH 8 ± 0.05, maintaining the dissolved oxygen (DO) concentration at 1.7 ± 0.2 mg/L and the temperature at 30 ± 1 °C. The reaction was easily converted to partial nitrification mode within a month by feeding a relatively high ammonium substrate (∼100 mg-N/L) in the beginning. We observed stable nitritation over 300 days with high ALRs (as high as ∼1.1 kg-N/m3-d), nitrite accumulation rates (mostly over 97%), and ammonium removal rates (mostly over 95...

Research paper thumbnail of Grid Pricing: An Empirical Investigation of Market Signal Clarity

The ability of the grid marketing system for fed cattle to provide an efficient price transmissio... more The ability of the grid marketing system for fed cattle to provide an efficient price transmission mechanism is investigated. Nerlove's (1958) adaptive expectations approach is adopted to model the relationship between grid premiums (discounts) and the weekly relative supply of carcass quality attributes. Linear regression techniques are used to estimate Nerlove's supply response function. Granger Causality tests are conducted to investigate the relationship between grid premiums (discounts) and the relative supply of carcass quality attributes. Regression estimates and the Granger Causality tests provide empirical support for the 2005 National Beef Quality Audit call for clearer market signals.

Research paper thumbnail of Knowledge Discovery Through Text Mining in the United States Data Science

Presented at the 2017 International Conference on Knowledge Management. This presentation examine... more Presented at the 2017 International Conference on Knowledge Management. This presentation examines uses knowledge discovery and text mining to identify patterns and trends in the data science discipline by examining core course titles of the Data Science curriculum offered in the United States.

Research paper thumbnail of Coexistence of sickle cell disease and systemic lupus erythematosus is associated with quantitative and qualitative impairments in circulating regulatory B cells

Research paper thumbnail of Glycemic control and awareness of foot care in diabetic foot syndrome

INTERNATIONAL JOURNAL OF ENDOCRINOLOGY (Ukraine), 2021

Background. The chronic complications of diabetes mellitus (DM) result from a wide variety of eff... more Background. The chronic complications of diabetes mellitus (DM) result from a wide variety of effects of disease. The correlation between blood sugar level and chronic complications has been demonstrated in various studies. Patient education, risk factor management, and other preventative measures are critical elements in reducing the incidence of diabetes complications such as Diabetic Foot Syndrome (DFS). We purposed to evaluate knowledge and attitudes towards foot care amongst patients with diabetes mellitus; in addition, we investigated the correlation between glycemic control and DFS. Materials and methods. This was a descriptive cross-sectional evaluation of patients who were diagnosed with diabetes mellitus seeking outpatient medical care with data being collected through patient surveys, clinical evaluation, specialty consultation, and biochemical analysis of glycated haemoglobin (HbA1c) serum levels. The population of the study was composed of 90 patients diagnosed with DM....

Research paper thumbnail of A smarter energy management system for the realization of virtual power plants

In the current era there is a global concern about the economic downturn and a greener earth whic... more In the current era there is a global concern about the economic downturn and a greener earth which is related to a better and efficient method to generate and transmit electric power. With the advent of the plug-in electric vehicles and renewable energy generators, a smarter, more efficient and customer-friendly power grid is essential. Problems of increased carbon emissions and shortage of energy production are answered by the inclusion of the dispersed/renewable energy generation network in the current centralized grid structure, thus leading towards a decentralized grid structure. This decentralized grid structure establishes the basis of the tomorrow's "Smart Grid". The Smart Grid concept pioneers the two most researched subsystems for managing generation and loads. The first being Micro Grid, the second Virtual Power Plants. The principal difference between these two subsystems is their voltage levels, where Micro Grids deal primarily with low voltage generation sources and loads; Virtual Power Plants operate both on medium and low voltage generation sources and loads. The Virtual Power Plant concept was introduced back in 2002 and has a broader definition of control and dispatch management of generation sources and load as compared to Micro Grid. Energy management is an integral part of the power system stability, therefore in this dissertation Virtual Power Plant system is chosen as the principle model for the control and management of energy flow throughout the network. This thesis presents a smarter energy management system for Virtual Power Plants by monitoring, controlling and optimizing the generation, transmission and distribution system. The forthcoming earlier chapters of this dissertation describe the considered approach towards the design and planning of the Virtual Power Plant structure. During the design phase all the three types of distributed generation sources namely Synchronous Generators, Induction Generators and Electronically interfaced renewable energy sources are considered. Based on these generation sources, the Virtual Power Plant structure is 7

Research paper thumbnail of Understanding the knowledge, skills, and abilities (KSA) of data professionals in United States academic libraries

Research paper thumbnail of Electrochemical preparation of Nb2O5 nanochannel photoelectrodes for enhanced photoelectrocatalytic performance in removal of RR120 dye

Chemosphere, 2020

The present work describes the synthesis of niobium oxide nanochannels (Nb2O5NCs) with high surfa... more The present work describes the synthesis of niobium oxide nanochannels (Nb2O5NCs) with high surface area, porosity, photocurrent density, and photoelectrochemical stability as photocatalyst. The Nb2O5NCs were prepared by electrochemical anodization of niobium foil in different electrolytes: 1 M H2SO4 containing 0.4 wt% HF (S1); glycerol containing 0.4 M NH4F (S2); 0.25 g NH4F with 4 vol% water in glycol at 50 °C (S3); and glycerol containing 10 wt% K2HPO4, at 130 °C (S4, annealed in air; S5, annealed in N2). All the Nb2O5NCs showed well-organized arrays of nanochannels grown on the Nb foil, with tube diameters in the order S4<S2<S1<S3 and film thicknesses in the order S1<S2<S3<S4, as determined using FEG-SEM analyses. The samples were also characterized using XRD, EDX, DRS, XPS, EIS, Mott-Schottky analysis, and LSV curves. But, best results were obtained only when phosphorus (about 1% doping) was incorporated into the electrodes samples prepared in glycerol containing 10 wt% K2HPO4 at 130 °C (i.e. S4 and S5). This procedure enhances the absorption intensity in the UV-Vis regions, the conductivity, the charge carrier density, and the photocurrent density. The Nb2O5NC sample S5 was tested for the degradation of Procion Red HE-3B (RR120) dye, as a model pollutant, achieving efficient photoelectrodegradation with nearly 2 times higher mineralization efficiency compared to photolysis (PT) and photocatalysis (PC). Thus, the results indicate that the modification of Nb2O5NC thin film photoelectrodes by phosphorous doping can be a powerful and efficient alternative to usual approaches applied to the treatment of complex reactive dyes.

Research paper thumbnail of Development and characterization of regenerable chitosan-coated nickel selenide nano-photocatalytic system for decontamination of toxic azo dyes

International Journal of Biological Macromolecules, 2021

In this investigation, chitosan-coated nickel selenide nano-photocatalyst (CS-NiSe) were successf... more In this investigation, chitosan-coated nickel selenide nano-photocatalyst (CS-NiSe) were successfully prepared through the chemical reduction method. FTIR spectroscopy confirmed the synthesis of CS-NiSe nano-photocatalyst. Further, XRD analysis exhibited a monoclinic crystalline phase of photocatalyst with a crystallite size of 32 nm based on Scherer's equation. The SEM micrographs showed that the photocatalyst has an average particle size of 60 nm. The bandgap of CS-NiSe was 2.85 eV in the visible region of the spectrum. Due to this reason, the CS-NiSe was applied under solar light illumination for the photocatalytic activity of Erythrosine and Allura red dyes. The CS-NiSe presented the highest degradation efficiency of 99.53% for Erythrosine dye in optimized experimental conditions of 100 min at 30 °C, 30 ppm concentration, pH 5.0, and 0.14 g catalyst dose. For Allura red dye, a high degradation of 96.12% was attained in 120 min at pH 4.0, 100 ppm initial dye concentration, 35 °C temperature, and 0.1 g catalyst dose. The CS-NiSe showed excellent degradation efficiency and reduced to (95% for Erythrosine and 91% for Allura red dye) after five consecutive batches. Moreover, the statistical and neural network modelling analysis showed the significant influence of all studied variables on dyes degradation performance. The results demonstrated that CS-NiSe exhibited excellent photocatalytic performances for Erythrosine and Allura red dyes and could be a better photocatalyst for removing these dyes from industrial effluents.

Research paper thumbnail of Degradation of Congo red dye using ternary metal selenide-chitosan microspheres as robust and reusable catalysts

Environmental Technology & Innovation, 2021

Abstract Water pollution is a threatening environmental concern these days, which requires seriou... more Abstract Water pollution is a threatening environmental concern these days, which requires serious attention. Water is contaminated by the heavy discharge of industrial effluents containing organic wastes. Herein, this research work focused on the demand for overcoming water pollution utilizing clean and renewable energy (solar light irradiations) sources for photocatalytic degradation of Congo red (CR) dye with the help of ternary metal selenide-chitosan microspheres (ZBiSe-CM). First, zinc-bismuth-selenide nanoparticles (ZBiSe-NPs) were successfully synthesized via the solvothermal process and then supported with chitosan to prevent leaching of the catalyst. SEM micrographs showed the average size of newly synthesized nanocomposites catalysts was 30.9 nm. The average size of the ZBiSe-CM microspheres was calculated as 812 um with a spherical shape and a porous surface. The presence of prominent peaks in the EDX spectrum for bismuth, selenium, and zinc confirmed the synthesis of the nanoparticles. XRD analysis demonstrated the calculated crystallite size of ZBiSe-NPs was 27.04 nm. The photocatalytic behavior of the catalyst was studied at optimized experimental conditions. The ZBiSe-NPs showed high photocatalytic degradation efficiency (up to 99.63%) for 40 ppm concentration of CR at catalyst dosage 0.225 g, pH 8.0, and temperature 36-38 °C for 2 h of solar light illumination. Photodegradation of CR dye in the presence of ZBiSe-CM follows pseudo-first-order kinetics and the ZBiSe-CM degraded CR dye in five consecutive cycles with high decontamination efficiency. The newly synthesized ternary metal selenide-chitosan microspheres could be used for the decontamination of dyes from industrial wastewater.

Research paper thumbnail of Acute otitis externa: Consensus definition, diagnostic criteria and core outcome set development

PLOS ONE, 2021

Objective Evidence for the management of acute otitis externa (AOE) is limited, with unclear diag... more Objective Evidence for the management of acute otitis externa (AOE) is limited, with unclear diagnostic criteria and variably reported outcome measures that may not reflect key stakeholder priorities. We aimed to develop 1) a definition, 2) diagnostic criteria and 3) a core outcome set (COS) for AOE. Study design COS development according to Core Outcome Measures in Effectiveness Trials (COMET) methodology and parallel consensus selection of diagnostic criteria/definition. Setting Stakeholders from the United Kingdom. Subjects and methods Comprehensive literature review identified candidate items for the COS, definition and diagnostic criteria. Nine individuals with past AOE generated further patient-centred candidate items. Candidate items were rated for importance by patient and professional (ENT doctors, general practitioners, microbiologists, nurses, audiologists) stakeholders in a three-round online Delphi exercise. Consensus items were grouped to form the COS, diagnostic crite...

Research paper thumbnail of Self-doping of Nb2O5NC by cathodic polarization for enhanced conductivity properties and photoelectrocatalytic performance

Chemosphere, 2021

A simple novel electrochemical reduction approach was developed for the self-doping of Nb4+ in ni... more A simple novel electrochemical reduction approach was developed for the self-doping of Nb4+ in niobium oxide nanochannels (Nb2O5NC), changing the conductivity, optical properties, and photocatalytic properties of the material. Nb2O5NC was synthesized using different electrolytes: 0.4 wt% HF in 1 M H2SO4 (EI), 0.4 M NH4F in glycerol (EII), and 0.25 g NH4F with 4 vol% water in glycol at 50 °C (EIII). Field emission scanning electron microscopy (FEG-SEM) analysis showed well-organized arrays of Nb2O5 nanochannels produced on Nb foil, with varying tube diameters in the order EII < EI < EIII and film thickness in the order EI < EII < EIII, which drastically affected the photocurrent vs. potential curves. In order to self-dope the Nb2O5, the samples were electrochemically reduced in 0.1 M KH2PO4 buffer solution (pH 10) for 5 min, at -2.5 V vs. Ag/AgCl, resulting in the doped samples denoted P-EI, P-EII, and P-EIII. The results showed that reduction of Nb5+ to Nb4+ occurred for all the Nb2O5NC samples, leading to decreased surface charge transfer resistance between the Nb2O5NC and the electrolyte, as well as increases of the charge carrier density and photocurrent for all the self-doped samples, compared to undoped samples. Sample P-EI was also tested for the degradation of reactive red 120 (RR120) dye, achieving efficient photoelectrocatalytic degradation of a 10 mg L-1 dye solution. These results reveal that the self-doping approach can enhance the photoelectrocatalytic properties of Nb2O5 photoanode, offering an alternative way for the removal of reactive dyes.

Research paper thumbnail of Modeling of photolytic degradation of sulfamethoxazole using boosted regression tree (BRT), artificial neural network (ANN) and response surface methodology (RSM); energy consumption and intermediates study

Chemosphere, 2021

This study explores the boosted regression trees (BRT), artificial neural network (ANN) and respo... more This study explores the boosted regression trees (BRT), artificial neural network (ANN) and response surface methodology (RSM) to model and optimize the operational variables for the simulation of the Photolytic degradation of Sulfamethoxazole (SMX) and concurrent total organic carbon (TOC) removal, based on the experimental data set. Four candidate variables involving initial pH (2-11), initial SMX concentration (50-200 mg L-1), temperature (15-45 °C) and time (6-120 min) were considered for simultaneous optimization of SMX and TOC degradation. The result revealed that all the three models are statistically considerable as the values of R, R2, adj-R2 are >0.85, thus be deemed to work well in data fitting, prediction, and optimization, nevertheless, the values of R, R2, adj-R2, RMSE, MAE and AAD are far better for ANN and BRT than RSM method. The ∼100% SMX degradation conditions were found to be as follows: treatment time: 25 min, pH: 2.0, temperature: 35 °C and SMX concentration: 50 mg L-1, while the maximum possible removal of TOC under the given conditions was ∼25%. The percentage contribution (PC) of each variable was deduced by ANOVA analysis of proposed quadratic models which indicated that time and pH are important factors than temperature and SMX concentration. The photolytic intermediates and inorganic ions of SMX, were identified and a potential route of transformation was also proposed.

Research paper thumbnail of Regenerable chitosan-bismuth cobalt selenide hybrid microspheres for mitigation of organic pollutants in an aqueous environment

International Journal of Biological Macromolecules, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Research paper thumbnail of Design and Analysis of a Wearable Monopole Antenna on Jeans Substrate for RFID Applications

International Journal of Wireless and Microwave Technologies, 2016

In this paper a novel rectangular C-shaped planar monopole antenna is designed and analyzed for R... more In this paper a novel rectangular C-shaped planar monopole antenna is designed and analyzed for Radio Frequency Identification (RFID) application in the licensed-free Industrial Scientific and Medical (ISM) band of 2.45 GHz. The proposed antenna uses a 1 mm thicker wearable Jeans fabric {relative permittivity, ε r =1.68 and Loss Tangent of δ=0.025} as a substrate material. For better bandwidth, and radiation efficiency the substrate is backed by a truncated copper ground plane. The antenna operate efficiently (92.85%), giving an adequate bandwidth, return-loss, gain and directivity of 12 %,-35.57 dB, 3.144 dB and 3.465 dBi, respectively. The nominated antenna is compact, low profile, and provides a better impedance matching (50.25 ohms) which results in a Voltage Standing Wave Ratio (VSWR) of 1.03. The far-field analysis is carried out via Finite Integration Technique (FIT) in CST Microwave studio.

Research paper thumbnail of Not Just a Pretty Face: Three-Dimensional Printed Custom Airway Management Devices

3D Printing and Additive Manufacturing, 2016

Three-dimensional (3D) printing, also known as additive manufacturing, is a fascinating technolog... more Three-dimensional (3D) printing, also known as additive manufacturing, is a fascinating technology that is poised to transform the practice of medicine in the 21st century. The Society for Technology in Anesthesia hosted an engineering challenge to use a 3D printer to create a customized oral airway based on a patient's anatomy. We approached this challenge in two parts. First, we identified a model for an oral airway to base our prototype. We created a 3D rendering of the customizable oral airway and designed a user interface that would accept specific measurements to create a customized oral airway. We then rendered a 3D model of the patient's airway and surrounding structures using Mimics (Materialise, Leuven, Belgium). The model was optimized for an Object Connex (Stratasys, Eden Prairie, MN), which has the capability of printing in various materials. We specified softer materials for the flexible tissues such as the tongue, palate, vocal cords, and epiglottis; a more rigid material was utilized for the supporting structures such as the mandible, nose, and bony structures. Furthermore, we printed the model in various parts, consisting of the tongue, jaw, trachea, and head/neck, that would articulate to make up the head and neck. The head and neck was one continuous part, divided sagittally at the midline, and the trachea was divided in the coronal plane. The printing process took *30 h of printing time and resulted in an anatomically correct model that included the nasopharynx, oropharynx, and trachea with an articulating mandible. We describe the process of designing and producing anatomic models for medical device prototype design. We propose a methodology of evaluating medical device prototypes using anatomically accurate models manufactured with 3D printers.

Research paper thumbnail of Accuracy of Platelet Counting by Optical and Impedance Methods in Patients with Thrombocytopaenia and Microcytosis

Sultan Qaboos University Medical Journal, 2015

Objectives: Obtaining accurate platelet counts in microcytic blood samples is challenging, even w... more Objectives: Obtaining accurate platelet counts in microcytic blood samples is challenging, even with the most reliable automated haematology analysers. The CELL-DYN ™ Sapphire (Abbott Laboratories, Chicago, Illinois, USA) analyser uses both optical density and electronic impedance methods for platelet counting. This study aimed to evaluate the accuracy of optical density and electrical impedance methods in determining true platelet counts in thrombocytopaenic samples with microcytosis as defined by low mean corpuscular volume (MCV) of red blood cells. Additionally, the impact of microcytosis on platelet count accuracy was evaluated. Methods: This study was carried out between February and December 2014 at the Haematology Laboratory of the Sultan Qaboos University Hospital in Muscat, Oman. Blood samples were collected and analysed from 189 patients with thrombocytopaenia and MCV values of <76 femtolitres. Platelet counts were tested using both optical and impedance methods. Stained peripheral blood films for each sample were then reviewed as a reference method to confirm platelet counts. Results: The platelet counts estimated by the impedance method were on average 30% higher than those estimated by the optical method (P <0.001). The estimated intraclass correlation coefficient was 0.52 (95% confidence interval: 0.41-0.62), indicating moderate reliability between the methods. The degree of agreement between methods ranged from-85.5 to 24.3 with an estimated bias of-30, suggesting that these methods generate different platelet results. Conclusion: The impedance method significantly overestimated platelet counts in microcytic and thrombocytopaenic blood samples. Further attention is therefore needed to improve the accuracy of platelet counts, particularly for patients with conditions associated with microcytosis.

Research paper thumbnail of Risk and Drawdowns

A Quantitative Approach to Building Trading Strategies, 2015

Research paper thumbnail of Case of fatal toxic epidermal necrolysis due to cardiac catheterization dye

Journal of drugs in dermatology : JDD, 2010

Cardiac catheterization is a very common procedure carried out for diagnostic as well as therapeu... more Cardiac catheterization is a very common procedure carried out for diagnostic as well as therapeutic reasons. Complications are not surprising due to the invasive nature of the procedure. Most of these complications have been seen numerous times by cardiologists who frequent the catheterization laboratory. Unfortunately, this patient experienced an extremely rare complication that ultimately resulted in his death. Here, the authors report a case of toxic epidermal necrolysis (TEN) resulting from the nonionic radiocontrast agent used in cardiac catheterization.

Research paper thumbnail of Non-invasive haemoglobin estimation in patients with thalassaemia major

Sultan Qaboos University medical journal, 2014

This study aimed to validate pulse CO-oximetry-based haemoglobin (Hb) estimation in children and ... more This study aimed to validate pulse CO-oximetry-based haemoglobin (Hb) estimation in children and adults with thalassaemia major (TM) and to determine the impact of different baseline variables on the accuracy of the estimation. This observational study was conducted over a five-week period from March to April 2012. A total of 108 patients with TM attending the daycare thalassaemia centre of a tertiary care hospital in Muscat, Oman, were enrolled. Spot (Sp) Hb measurements were estimated using a Pronto-7(®) pulse CO-oximetry device (Masimo Corp., Irvine, California, USA). These were compared to venous samples of Hb using the CELL-DYN Sapphire Hematology Analyzer (Abbott Diagnostics, Abbott Park, Illinois, USA) to determine the reference (Ref) Hb levels. A multivariable linear regression model was used to assess the impact of baseline variables such as age, gender, weight, height, Ref Hb and blood pressure on the Hb estimations. Of the 108 enrolled patients, there were 54 males and 54...

Research paper thumbnail of Rapid start-up and efficient long-term nitritation of low strength ammonium wastewater with a sequencing batch reactor containing immobilized cells

Water Science & Technology, 2014

Major concerns about nitritation of low-strength ammonium wastewaters include low ammonium loadin... more Major concerns about nitritation of low-strength ammonium wastewaters include low ammonium loading rates (ALRs) (usually below 0.2 kg/m3-d) and uncertainty with the long-term stability of the process. The purpose of this study was to test a sequencing batch reactor filled with cell-immobilized polyethylene glycol (PEG) pellets (∼2 mm in size) to see if it could achieve efficient and stable nitritation under various environmental conditions. The sequencing batch reactor (SBR) was fed with synthetic ammonium wastewater of 30 ± 2 mg-N/L and pH 8 ± 0.05, maintaining the dissolved oxygen (DO) concentration at 1.7 ± 0.2 mg/L and the temperature at 30 ± 1 °C. The reaction was easily converted to partial nitrification mode within a month by feeding a relatively high ammonium substrate (∼100 mg-N/L) in the beginning. We observed stable nitritation over 300 days with high ALRs (as high as ∼1.1 kg-N/m3-d), nitrite accumulation rates (mostly over 97%), and ammonium removal rates (mostly over 95...