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Your search keyword '"Mahdi, E. M."' showing total 23 results
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23 results on '"Mahdi, E. M."'

2. Dielectric Properties of Metal-Organic Frameworks Probed via Synchrotron Infrared Reflectivity

Author

Ryder, Matthew R., Zeng, Zhixin, Sun, Yueting, Flyagina, Irina, Titov, Kirill, Mahdi, E. M., Bennett, Thomas D., Civalleri, Bartolomeo, Kelley, Chris S., Frogley, Mark D., Cinque, Gianfelice, and Tan, Jin-Chong

Subjects
Condensed Matter - Materials Science
Abstract

We present the frequency-dependant (dynamic) dielectric response of a group of topical polycrystalline zeolitic imidazolate-based metal-organic framework (MOF) materials in the extended infrared spectral region. Using synchrotron-based FTIR spectroscopy in specular reflectance, in conjunction with density functional theory (DFT) calculations, we have revealed detailed structure-property trends linking the THz region dielectric response to framework porosity and structural density. The work demonstrates that MOFs are promising candidate materials not only for low-\k{appa} electronics applications but could also be pioneering for terahertz (THz) applications, such as next-generation broadband communications technologies., Comment: 6 pages, 5 figures

Published
2018

3. Quantum tunneling rotor as a sensitive atomistic probe of guests in a metal-organic framework

Author

Titov, Kirill, primary, Ryder, Matthew R., additional, Lamaire, Aran, additional, Zeng, Zhixin, additional, Chaudhari, Abhijeet K., additional, Taylor, James, additional, Mahdi, E. M., additional, Rogge, Sven M. J., additional, Mukhopadhyay, Sanghamitra, additional, Rudić, Svemir, additional, Van Speybroeck, Veronique, additional, Fernandez-Alonso, Felix, additional, and Tan, Jin-Chong, additional

Published
2023
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4. Quantum tunneling rotor as a sensitive atomistic probe of guests in a metal-organic framework

Author

European Commission, European Research Council, Engineering and Physical Sciences Research Council (UK), Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), Department of Energy (US), Research Foundation - Flanders, Eusko Jaurlaritza, Ikerbasque Basque Foundation for Science, Titov, Kirill, Ryder, Matthew R., Lamaire, Aran, Zeng, Zhixin, Chaudhari, Abhijeet K., Taylor, James, Mahdi, E. M., Rogge, Sven M. J., Mukhopadhyay, Sanghamitra, Rudić, Svemir, Van Speybroeck, Veronique, Fernández-Alonso, Félix, Tan, Jin-Chong, European Commission, European Research Council, Engineering and Physical Sciences Research Council (UK), Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), Department of Energy (US), Research Foundation - Flanders, Eusko Jaurlaritza, Ikerbasque Basque Foundation for Science, Titov, Kirill, Ryder, Matthew R., Lamaire, Aran, Zeng, Zhixin, Chaudhari, Abhijeet K., Taylor, James, Mahdi, E. M., Rogge, Sven M. J., Mukhopadhyay, Sanghamitra, Rudić, Svemir, Van Speybroeck, Veronique, Fernández-Alonso, Félix, and Tan, Jin-Chong

Abstract

Quantum tunneling rotors in a zeolitic imidazolate framework ZIF-8 can provide insights into local gas adsorption sites and local dynamics of porous structure, which are inaccessible to standard physisorption or x-ray diffraction sensitive primarily to long-range order. Using in situ high-resolution inelastic neutron scattering at 3 K, we follow the evolution of methyl tunneling with respect to the number of dosed gas molecules. While nitrogen adsorption decreases the energy of the tunneling peak, and ultimately hinders it completely (0.33 meV to zero), argon substantially increases the energy to 0.42 meV. Ab initio calculations of the rotational barrier of ZIF-8 show an exception to the reported adsorption sites hierarchy, resulting in anomalous adsorption behavior and linker dynamics at subatmospheric pressure. The findings reveal quantum tunneling rotors in metal-organic frameworks as a sensitive atomistic probe of local physicochemical phenomena.

Published
2023

5. The effect of green diode laser on white ant (Psammotermes hypostoma).

Author

Rashid, S. N., Mahdi, E. M., Sabri, T. Y., and Hamad, A. M.

Subjects
*TERMITES, *SEMICONDUCTOR lasers, *DEATH rate, *TREATMENT effectiveness, *LASERS
Abstract

This work focused on studying the effect of the green diode laser on the external appearance of white ants (termites) (Psammotermes hypostoma) and then finding the percentage of mortality resulting from this beam of wavelength (532 nm), energy (100 mW), and exposure times (60, 70, 80, 90 & 100)sec at (5, 10)cm for each exposure time. The results recorded in this research showed a clear increase in termite death rates, In addition to an increase in deformations as laser exposure times increased and the percentages were higher at the lower distance, where the laser was used to capture the results of this therapeutic effect over periods (12, 24, 48 & 72)hours. These results in general, show green laser thermal effects resulting from its interaction with tissues, the thermal propagation leads to ravage to the structures and thus to an increase in death rates. [ABSTRACT FROM AUTHOR]

Published
2022
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18. Fine-scale tribological performance of zeolitic imidazolate framework (ZIF-8) based polymer nanocomposite membranes.

Author

Nay Win Khun, Mahdi, E. M., Siqi Ying, Tan Sui, Korsunsky, Alexander M., and Jin-Chong Tan

Subjects
METAL-organic frameworks, ZEOLITES, NANOPARTICLES, POLYMERS, ARTIFICIAL membranes, NANOCOMPOSITE materials, FRICTION, TRIBOLOGY
Abstract

We combined zeolitic imidazolate framework nanoparticles (ZIF-8: ~150 nm diameter) with Matrimid® 5218 polymer to form permeable mixed matrix membranes, featuring different weight fractions of nanoparticles (up to 30 wt.%loading).We used ball-on-disc micro-tribological method to measure the frictional coefficient of the nanocomposite membranes, as a function of nanoparticle loading and annealing heat treatment. The tribological results reveal that the friction and wear of the unannealed samples rise steadily with greater nanoparticle loading because ZIF-8 is relatively harder than the matrix, thus promoting abrasive wear mechanism. After annealing, however, we discover that the nanocomposites display an appreciably lower friction and wear damage compared with the unannealed counterparts. Evidence shows that the major improvement in tribological performance is associated with the greater amounts of wear debris derived from the annealed nanocomposite membranes. We propose that detached Matrimid-encapsulated ZIF-8 nanoparticles could function as "spacers," which are capable of not only reducing direct contact between two rubbing surfaces but also enhancing free-rolling under the action of lateral forces. [ABSTRACT FROM AUTHOR]

Published
2014
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20. Thyroid function in patients with mycetoma.

Author

Fahal AH, Omer SM, el Razig SA, Ali AB, Mahdi EM, and Mahgoub ES

Subjects
Adolescent, Adult, Case-Control Studies, Child, Depressive Disorder microbiology, Female, Humans, Hypothyroidism blood, Male, Middle Aged, Mycetoma blood, Mycetoma psychology, Prospective Studies, Thyroid Hormones blood, Hypothyroidism microbiology, Mycetoma complications
Abstract

Thyroid function was assessed in seventy two patients with various types of mycetoma. There was no evidence of clinical or biochemical thyroid dysfunction in these patients. The symptoms encountered in some of the mycetoma patients mimic those of hypothyroidism should be attributed to other factors possibly mental depression and apathy.

Published
1995

23. Pattern of diabetes mellitus in the Sudan.

Author

el Mahdi EM, Abdel Rahman Iel M, and Mukhtar Sel D

Subjects
Adolescent, Adult, Age Factors, Aged, Child, Child, Preschool, Diabetes Complications, Diabetes Mellitus therapy, Female, Humans, Incidence, Infant, Male, Middle Aged, Sex Factors, Sudan epidemiology, Time Factors, Diabetes Mellitus epidemiology
Abstract

448 Sudanese diabetics were included in this study. 30% of patients were in the age group 40-50 years and only 6.3% had childhood diabetes. The predominant sex was female (64.5%). Obesity was found in 39% of patients, a positive family history in 66.5% and a history of diabetic ketoacidosis in 25.2%. 100 patients (below the age of 40) had a plain X-ray abdomen done but none had evidence of pancreatic calcification. Percentages of diabetic complications in this study were as follows: neuropathy 28.1%, retinopathy 18.5%, cataract 14.7%, hypertension 12.9%, nephropathy 11.6%, peripheral vascular disease 6.2%, coronary heart disease 4.2% and pulmonary tuberculosis 2.7%. The majority of our patients were uncontrolled, only 16.7% had normoglycaemia (FBG less than 140 mg%).

Published
1989

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