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      • The influence of EAF dust on resistivity of concrete and corrosion of steel bars embedded in concrete

        Almutlaq, Fahad M. Techno-Press 2014 Advances in concrete construction Vol.2 No.3

        Essentially, when electrical current flows easily in concrete that has large pores filled with highly connective pore water, this is an indication of a low resistivity concrete. In concrete, the flow of current between anodic and cathodic sites on a steel reinforcing bar surface is regulated by the concrete electrical resistance. Therefore, deterioration of any existing reinforced concrete structure due to corrosion of reinforcement steel bar is governed, to some extent, by resistivity of concrete. Resistivity of concrete can be improved by using SCMs and thus increases the concrete electrical resistance and the ability of concrete to resist chloride ingress and/or oxygen penetration resulting in prolonging the onset of corrosion. After depassivation it may slow down the corrosion rate of the steel bar. This indicates the need for further study of the effect of electric arc furnace dust (EAFD) addition on the concrete resistivity. In this study, concrete specimens rather than mortars were cast with different additions of EAFD to verify the electrochemical results obtained and to try to understand the role of EAFD addition in influencing the corrosion behaviour of reinforcing steel bar embedded in concrete and its relation to the resistivity of concrete. The results of these investigations indicated that the corrosion resistance of steel bars embedded in concrete containing EAFD was improved, which may link to the high resistivity found in EAFD-concrete. In this paper, potential measurements, corrosion rates, gravimetric corrosion weight results and resistivity measurements will be presented and their relationships will also be discussed in details.

      • KCI등재

        Synthesis, structural, TD-DFT, and optical characteristics of indole derivatives

        Almutlaq N.,Elshanawany Mahmoud M.,Sayed Mostafa,Younis Osama,Ahmed Mostafa,Wachtveitl Josef,Braun Markus,Tolba Mahmoud S.,Al-Hossainy Ahmed F.,Abozeed Amina A. 한국물리학회 2023 Current Applied Physics Vol.45 No.-

        New compounds of (E)-1-(3-chloro-1H-indol-2-yl)-N-(4-methoxyphenyl)methanimine [Indol-M] and (E)-1-(4- (((3-chloro-1H-indol-2-yl)methylene)amino)phenyl)ethan-1-one [Indol-A] were synthesized and subsequently converted to thin films via physical vapor deposition technique. Numerous characterization techniques were used including FTIR, nuclear magnetic resonance, X-ray diffraction, scanning electron microscope, and optical spectroscopy. Additionally, the optimization using TD-DFTD/Mol3 and Cambridge Serial Total Energy Bundle (TD-FDT/CASTEP) was performed. The XRD and FTIR spectra recorded experimentally were confirmed by TD-DFT calculations, proving their molecular structure. As determined by XRD, the crystallite size of [Indol-M]TF and [Indol-A]TF is 72.26 and 62.05 nm, respectively. SEM image depicts a one-dimensional morphological structure made up of tightly packed nanorods. The direct optical energy bandgaps computed using Tauc’s equation for the [Indol-M]TF and [Indol-A]TF are 4.49 eV and 3.31 eV, respectively. As predicted by CASTEP TD-DFT, the optical properties agree well with the experimental values. [Indol-M]TF and [Indol-A]TF present good candidates for optoelectronics and solar cell applications.

      • Digital Divide in Riyadh Neighborhoods: A Spatial Analysis

        Rawan, Almutlaq,Shuruq, Alshamrani,Ohoud, Alhaqbani,Fatimah, Altamimi,Ghadah, Alammaj,Omer, Alrwais International Journal of Computer ScienceNetwork S 2023 International journal of computer science and netw Vol.23 No.1

        The objective of this paper is to use Geographical Information Systems for identifying Digital Divide in Riyadh Neighborhoods, Saudi Arabia. Geo-database was created that includes Streets, Neighborhoods, ICT Access Data and Coverage Map for Riyadh. We used QGIS and overlay for analysis, intersection selected as tool for this paper. The results indicate that after analyzing the use of information communication technology in all regions of the Kingdom it turns that Riyadh, Ash Sharqiyyah and Makkah in average with percentage 50%, While Al Jawf, Al Madinah, and Najran are the least with percentage 42%. Then we focused on Riyadh to analyze the digital divide because it is the capital of Saudi Arabia and occupations the highest percent of communications towers in the KSA due to population density. Regarding coverage of the 4G, the neighborhoods at the center have recorded very high coverage score. While neighborhoods at the edges of the city have low values of coverage score. Same for 3G, it is more intense in the center and the coverage percentage is higher than 4G. For 2G we found it had the highest coverage compared to 3G or 4G

      • Investigation of high contrast and reversible luminescence thermochromism of the quantum confined Cs<sub>4</sub>PbBr<sub>6</sub> perovskite solid

        Choi, Jin Woo,Cho, Namchul,Woo, Hee Chul,Oh, Byeong M.,Almutlaq, Jawaher,Bakr, Osman M.,Kim, Sung-Hoon,Lee, Chang-Lyoul,Kim, Jong H. The Royal Society of Chemistry 2019 Nanoscale Vol.11 No.12

        <P>Thermochromism of organic/inorganic halide perovskites has attracted particular interest due to their potential applications as photoluminescence (PL)-based temperature sensors. However, despite the outstanding PL characteristics, their use as a thermochromic material in practical temperature ranges has been limited because of their poor thermal stability. In this study, we used the quantum confinement effect and exceptional PL quantum efficiency of the Cs4PbBr6 perovskite to demonstrate their high on/off ratio (20) and reversible PL thermochromism in the solid state in practical temperature ranges including room temperature (RT). Systematic photophysical and optical characterization studies, including exciton-phonon scattering, exciton binding energy, exciton decay dynamics, and crystal structure change, were performed to investigate the origin of this unique thermochromic PL property. The results showed that the efficient and highly reversible thermochromic PL emission of the Cs4PbBr6 perovskite is due to its desirable optical properties such as highly luminescent emission, efficient PL quenching at high temperatures, and thermally reversible structural changes.</P>

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