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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.
하립개,Akber Idhayadhulla,이용록,김성홍,위영중 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.22 No.-
Diverse 3,5,6,7-tetrahydrobenzofuran-4-one derivatives (3a–3n) were synthesized in high yields byruthenium complex or rhodium complex catalyzed [3 + 2] cycloaddition. The antibacterial activities ofthese 3,5,6,7-tetrahydrobenzofuran-4-ones were evaluated against Gram-negative bacteria (Escherichiacoli, Pseudomonas aeruginosa, and Enterobacter aerogenes) and Gram-positive bacteria (Bacillus cereus andStaphylococcus aureus). In particular, compound 3b showed the highest antibacterial activity against P. aeruginosa and S. aureus (both MICs: 2 mg/mL). Compound 3l, which has the 2H-pyrano[2,3-b]benzofuran skeleton, exhibited excellent inhibitory activity against B. cereus (MIC: 0.5 mg/mL) ascompared with ciprofloxacin (MIC: 2 mg/mL) and ampicillin (MIC: 1 mg/mL).
Jian-ping Yong,Haji Akber Aisa 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.4
To improve the biological activities of rupestonic acid, 21 new rupestonic acid fatty ester derivatives (2a-2h)and aromatic ester derivatives (2i-2u) were synthesized and preliminarily evaluated for their anti-influenza activity in vitro by the national center for drug screening of China, using the Oseltamivir and Ribavirin as reference drugs. The results showed that 2l (IC_50 = 0.5 μmol/L) exhibited potent anti-influenza A_3 viral activity among the synthesized compounds and was 10-fold more potent than that of the reference drug Oseltamivir (IC_50 = 5.1 μmol/L).
Xia, Likai,Idhayadhulla, Akber,Lee, Yong Rok,Kim, Sung Hong,Wee, Young-Jung American Chemical Society 2014 ACS Combinatorial Science Vol.16 No.7
<P>With the aim of developing a general and practical method for library production, a novel and efficient two-phase microwave-assisted cascade reaction between isatins and beta-ketoamides in [Bmim]BF4/toluene was developed for the synthesis of pyrrolo[3,4-c]quinoline-1,3-diones. The features of this methodology are, the use of microwave-assisted rapid synthesis, mild reaction conditions, high yields, operational simplicity, facile product separation, and recyclability. Furthermore, the antibacterial activities of the pyrrolo[3,4-c]quinoline-1,3-dione derivatives produced were evaluated against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Enterobacter aerogenes) and Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus). These derivatives showed antibacterial activities against Gram-positive strains that were at least equivalent to that against Gram-negative strains. Compound 7{3,5} displayed the most potent antibacterial activity against P. aeruginosa (MIC = 0.5 mu g/mL) and greater activity than standard ampicillin (MIC = 1 mu g/mL). Compound 7{4,7} exhibited the best inhibitory activity against E. coli and E. aerogenes (MIC = 1 and 0.5 mu g/mL), compared with the standard ampicillin (both MICs = 1 mu g/mL). The synthesized pyrrolo[3,4-c]quinoline-1,3-diones are expected to be widely used as lead compounds for the development of new antibacterial agents.</P>
Rana, Anwar Manzoor,Ismail, Muhammad,Akber, Tahira,Younus Nadeem, M.,Kim, Sungjun Elsevier 2019 Materials research bulletin Vol.117 No.-
<P><B>Abstract</B></P> <P>We report the transition from unipolar to bipolar switching, multilevel resistive switching, abrupt and gradual reset phenomena in a TaN/CeO<SUB>2</SUB>/Ti: /Pt memory devices. Multilevel resistive switching can be successfully obtained by varying the current compliance in the set process. It was observed that increasing the value of current compliance during the set process decreases the set voltages of the devices and as well as deceases the low and high resistance states, respectively. In addition, we have also observed coexistence of abrupt and gradual reset transition in a Ta/CeO<SUB>2</SUB>/Ti: /Pt memory cell. The device exhibits the excellent bipolar resistive switching characteristics such as endurance performance, device-to-device variability (D2D) and good retention time 10<SUP>4</SUP> s. The oxidation of the TaN top electrode creates an Ohmic contact with CeO<SUB>2</SUB> film and hence injects positively charged oxygen vacancies into the switching layer which looks to be responsible for resistive switching.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Transition from unipolar to bipolar switching in a Ta/CeO<SUB>2</SUB>/Ti: /Pt memory device was investigated. </LI> <LI> Multilevel resistive switching can be successfully obtained by varying the current compliance in the set process. </LI> <LI> Increasing the value of current compliance during the set process deceases the low and high resistance states. </LI> <LI> Electrical conduction mechanism is dominated by Schottky emission at high field regions of abrupt and gradual modes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>