A Review of Dose Rate Meters as First Responders to Ionising Radiation

Akber, Aqeel Ahmad,Wiggins, Matthew Benfield The Korean Association for Radiation Protection 2019 방사선방어학회지 Vol.44 No.3

Background: Dose rate meters are the most widely used, and perhaps one of the most important tools for the measurement of ionising radiation. They are often the first, or only, device available to a user for an instant check of radiation dose at a certain location. Throughout the world, radiation safety practices rely strongly on the output of these dose rate meters. But how well do we know the quality of their output? Materials and Methods: This review is based on the measurements 1,158 commercially available dose rate meters of 116 different makes and models. Expected versus the displayed dose patterns and consistency was checked at various dose rates between $5{\mu}Gy{\cdot}h^{-1}$ and $2mGy{\cdot}h^{-1}$. Samples of these meters were then selected for further investigation and were exposed to radiation sources covering photon energies from 50 keV to 1.5 MeV. The effect of detector orientation on its reading was also investigated. Rather than focusing on the angular response distribution that is often reported by the manufacturer of the device, this study focussed on the design ergonomics i.e. the angles that the operator will realistically use to measure a dose rate. Results and Discussion: This review shows the scope and boundaries of the ionising radiation dose rate estimations that are made using commonly available meters. Observations showed both inter and intra make and model variations, occasional cases of instrument failure, instrument walk away, and erroneous response. Conclusion: The results indicate the significance of selecting and maintaining suitable monitors for specific applications in radiation safety.

Investigation of entropy generation rate and its minimization in helical grooved tubes

Shamoon Jamshed,Shafiq R. Qureshi,Aqeel Shah,Ahmad Hussain 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.10

Surface enhancement in heat exchangers has been actively researched, but enhancements have been mainly on the tube side, involving optimization of the geometry. The effect of surface enhancement has been studied in great detail experimentally, but numerical studies are scarce and involve performance comparisons based on the friction factor and Nusselt number. However, true performance can be assessed based on entropy generation minimization. We performed a numerical study on tubes with helical groove formation to assess entropy generation minimization. The tube data were initially validated experimentally and tube performance was then examined via thermal enhancement factors and entropy generation minimization. The Reynolds number was taken as 5000 to 10000 in accordance with an experimental study. All the tubes had an enhancement factor greater than unity, meaning that they were thermally efficient. However, with regard to irreversibility, the tube with the minimum pitch-0.051 m-(GT02) produced the lowest value and hence the minimum entropy generation rate, and thus represented the optimal choice for heat exchangers.

Effect of pH and Concentration on Electrochemical Corrosion Behavior of Aluminum Al-7075 T6 Alloy in NaCl Aqueous Environment

Raza, Syed Abbas,Karim, Muhammad Ramzan Abdul,Shehbaz, Tauheed,Taimoor, Aqeel Ahmad,Ali, Rashid,Khan, Muhammad Imran The Korean Electrochemical Society 2022 Journal of electrochemical science and technology Vol.13 No.2

In the present study, the corrosion behavior of aluminum Al-7075 tempered (T-6 condition) alloy was evaluated by immersion testing and electrochemical testing in 1.75% and 3.5% NaCl environment at acidic, neutral and basic pH. The data obtained by both immersion tests and electrochemical corrosion tests (potentiodynamic polarization and electrochemical impedance spectroscopy tests) present that the corrosion rate of the alloy specimens is minimum for the pH=7 condition of the solution due to the formation of dense and well adherent thin protective oxide layer. Whereas the solutions with acidic and alkaline pH cause shift in the corrosion behavior of aluminum alloy to more active domains aggravated by the constant flux of acidic and alkaline ions (Cl^- and OH^-) in the media which anodically dissolve the Al matrix in comparison to precipitated intermetallic phases (cathodic in nature) formed due to T6 treatment. Consequently, the pitting behavior of the alloy, as observed by cyclic polarization tests, shifts to more active regions when pH of the solutions changes from neutral to alkaline environment due to localized dissolution of the matrix in alkaline environment that ingress by diffusion through the pores in the oxide film. Microscopic analysis also strengthens the results obtained by immersion corrosion testing and electrochemical corrosion testing as the study examines the corrosion behavior of this alloy under a systematic evaluation in marine environment.

Innovative method to prepare a stable emulsion liquid membrane for high CO₂ absorption and its performance evaluation for a natural gas feed in a rotating disk contactor

Bhatti, Inamullah,Qureshi, Khadija,Kamarudin, Khairul Sozana Nor,Bazmi, Aqeel Ahmed,Bhutto, Abdul Waheed,Ahmad, Faizan,Lee, Moonyong Elsevier 2016 Journal of natural gas science and engineering Vol.34 No.-

<P><B>Abstract</B></P> <P>This paper presents an innovative method to prepare a stable emulsion liquid membrane (ELM) for high CO<SUB>2</SUB> absorption in a natural gas feed. This new method achieved high throughput at low power consumption. The ELM prepared using this new method was characterized by determining the effects of the concentration of the ELM constituents, emulsification time, and speed on the emulsion droplet size (EDS) and stability. This was followed by a parametric study of the process parameters for CO<SUB>2</SUB> separation from natural gas in a rotating disk contactor (RDC)-based setup to evaluate the performance of a stable ELM. The results suggest that the retention time of the stable ELM in a RDC increases with increasing amount of absorbed CO<SUB>2</SUB>. The results support the fundamental development of the ELM process to achieve a high overall separation efficiency of CO<SUB>2</SUB> removal from natural gas with a relatively small contact time. This is the first parametric study of CO<SUB>2</SUB> absorption from a gas stream in ELM using a RDC as the contracting equipment. The results of the parametric study suggested that the factors of time, TEA concentration and RDC speed have significant effect on the CO<SUB>2</SUB> absorption from natural gas feed. It was identified that 4% TEA in ELM, 30 min operational time and 700 rpm speed of modified RDC system is suitable for maximum CO<SUB>2</SUB> absorption from gas mixture of CO<SUB>2</SUB>/CH<SUB>4</SUB>. Furthermore, the study suggested that the ELM containing 4% TEA can absorb 5.6 kmol/m<SUP>3</SUP> CO<SUB>2</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Preparation and characterization of stable emulsion liquid membrane (ELM). </LI> <LI> Parametric study of CO<SUB>2</SUB> absorption from natural gas in rotating disk contactor (RDC). </LI> <LI> Retention time of the stable ELM increases with increasing amount of absorbed CO<SUB>2</SUB>. </LI> <LI> Fundamental development of ELM process for high overall separation efficiency. </LI> </UL> </P>

Antibacterial activity of flower of Melia azedarach Linn. and identification of its metabolites

Muhammad, Munira Taj,Lubna, Lubna,Fayyaz, Nida,Tauseef, Saima,Razaq, Ummarah,Versiani, Muhammad Ali,Ahmad, Aqeel,Faizi, Shaheen,Rasheed, Munawwer The Korean Society for Applied Biological Chemistr 2015 Applied Biological Chemistry (Appl Biol Chem) Vol.58 No.2

Constituents of eight different extracts and fractions, obtained from flowers of Melia azedarach, were identified by gas chromatography-mass spectrometry and mass spectral library search. Altogether, 38 phytochemicals were identified, all for the first time from the flowers. Only 14 of these were known from parts of M. azedarach other than flowers, while 24 are reported for the first time from any part of the plant. These metabolites included branched and n-hydrocarbons, aromatics, a polyisoprenoid, fatty acids, fatty acid methyl esters, and fatty alcohols, which were found to be different from its essential oil constituents. One major constituent 4-hydroxybenzoic acid (4) was not only identified but also isolated as a pure compound from ethyl acetate extract. Extracts, compound 4 and its derivatives gallic acid and methyl gallate were tested for antimicrobial potential. Gallic acid and methyl gallate exhibited antibacterial activity against Staphylococcus saprophyticus. Methyl gallate also showed some activity against Corynebacterium diphtheriae and Corynebacterium. hofmannii. Among the extracts, only methanol extract exhibited activity against Pseudomonas sp. The extracts only inhibited the growth of dermatophytic fungi.

Antibacterial activity of flower of Melia azedarach Linn. and identification of its metabolites

Munira Taj Muhammad,Lubna,Nida Fayyaz,Saima Tauseef,Ummarah Razaq,Muhammad Ali Versiani,Aqeel Ahmad,Shaheen Faizi,Munawwer Rasheed 한국응용생명화학회 2015 Applied Biological Chemistry (Appl Biol Chem) Vol.58 No.2

Constituents of eight different extracts and fractions, obtained from flowers of Melia azedarach, were identified by gas chromatography–mass spectrometry and mass spectral library search. Altogether, 38 phytochemicals were identified, all for the first time from the flowers. Only 14 of these were known from parts of M. azedarach other than flowers, while 24 are reported for the first time from any part of the plant. These metabolites included branched and n-hydrocarbons, aromatics, a polyisoprenoid, fatty acids, fatty acid methyl esters, and fatty alcohols, which were found to be different from its essential oil constituents. One major constituent 4-hydroxybenzoic acid (4) was not only identified but also isolated as a pure compound from ethyl acetate extract. Extracts, compound 4 and its derivatives gallic acid and methyl gallate were tested for antimicrobial potential. Gallic acid and methyl gallate exhibited antibacterial activity against Staphylococcus saprophyticus. Methyl gallate also showed some activity against Corynebacterium diphtheriae and Corynebacterium. hofmannii. Among the extracts, only methanol extract exhibited activity against Pseudomonas sp. The extracts only inhibited the growth of dermatophytic fungi.