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Oxygen plasma irradiation-induced surface modifications on HDPE and PET polymeric films
Atta A.,Althubiti N. A.,Althubiti S. 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.4
Nowadays, plasma treatments are one of the powerful techniques usually accomplished to change the surface characteristics of polymeric films. This study presents the influence of oxygen plasma irradiation on the structural and the optical properties of high-density polyethylene (HDPE) and polyethylene terephthalate (PET) films that will be used in optoelectronic devices. The films were irradiated with an oxygen plasma for duration of 3, 4.5, and 6 min. The surface structure of the films was investigated utilizing X-ray diffraction (XRD). For an irradiation time of 6 min, the crystallite size changes from 13.9 to 19.7 nm and from 5.7 to 6.5 nm for pristine HDPE and PET, respectively. The UV–Vis optical absorption spectrum demonstrates a slight shift in the absorption edge towards the visible region caused by the oxygen irradiation time for both the HDPE and the PET films. Increasing the irradiation time leads to a slight decrease in the optical energy band gap Eg and to an improvement in the carbon cluster number N. The results show clear improvements in the optical properties of HDPE and PET due to plasma irradiation that make them good candidates for use in optoelectronics applications.
Influence of Nano-silica on the Leaching Attack upon Photocatalytic Cement Mortars
Atta ur rehman,Abdul Qudoos,Sadam Hussain Jakhrani,김홍기,류재석 한국콘크리트학회 2019 International Journal of Concrete Structures and M Vol.13 No.5
Photocatalytic cementitious materials are used in the exterior of the buildings and infrastructure for self-cleaning and air-purifying purposes. These materials are exposed to the aggressive exposure conditions like acid rain, runoff water and are subjected to the deterioration due to the leaching of calcium. The knowledge of leaching attack upon photocatalytic cementitious materials after the addition of nano-materials is necessary. In the current study, the influ-ence of nano-silica addition on the leaching attack upon photocatalytic cement mortars was thoroughly investigated. For this purpose, photocatalytic mortars were made by adding 3% TiO2 and variable amount (0–2%) of nano-silica. Accelerated leaching environment was created by immersing mortars in 6 M ammonium nitrate (NH4NO3) solution. The progressive development of the leaching depth in mortars was measured. The loss of hardened properties was monitored by evaluating the compressive strength, flexural strength, porosity, and dynamic modulus of elasticity. X-ray diffraction, thermogravimetry, Fourier transform infrared spectroscopy, scanning electron microscopy tests were conducted to know the microstructural deteriorations. Results indicated that the leaching attack induced mechanical and microstructural damages in the mortars, but the addition of nano-silica decreased mechanical and microstruc-tural damages in the photocatalytic mortars and increased the resistance of photocatalytic mortars to leaching attack.
Current Advances in the Fire Retardancy of Natural Fiber and Bio-Based Composites – A Review
Atta Ur Rehman Shah,송정일,M. N. Prabhakar 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.4 No.2
Natural fibers and bio-based composites are competitive to conventional materials in structural and transportation industry. Natural fibers reinforced polymer matrix composites are familiar/common materials currently. Various properties of these composites have been explored in the already available literature, and has been continuing with new developments. They have a risk of flammability in most of the applications which is undesirable. Fire retardant natural fiber and bio-based composite materials have recently gained researchers’ interest. This paper summarizes recent progress regarding flammability of natural fiber and bio-based composites. The mechanism of fire retardancy has been explained. The factors affecting flammability of such composites and characterization techniques required for evaluating fire retardancy have also been described in detail. The reported effects of fire retardant include practices on the other properties of composites.
Atta Heidari,Abdollah Moossavi,Fariba Yadegari,Enayatollah Bakhshi,Mohsen Ahadi 대한청각학회 2018 Journal of Audiology & Otology Vol.22 No.3
Numerous studies have indicated deterioration of speechperception in noisy conditions among the elderly even those with normal hearing capabilities. The aim of this study was to investigate the effects of age on the speech-in-noise identificationby speech-in-noise (SIN) test, subjective ratings of hearing difficulties by speech,spatial, and qualities of hearing scale (SSQ) questionnaire and encoding of fundamental frequency(F0) by Speech auditory brainstem response (ABR) in the elderly and comparing theresults with young people. Subjects and Methods: The present study was conducted on32 elderly people aged over 60 years old (17 male and 15 female) with the mean age of68.9 (standard deviation=6.33) possessing normal peripheral hearing and 32 young subjects(16 male and 16 female) aged 18-25 years old. Results: Findings showed that thescore of SIN test is lower among the elderly people as compared with young people in signal-to-noise ratios of 0 and -10 based on Iranian version of SSQ questionnaire (p<0.001). The range of F0 amplitude in the elderly people is also lower than young people (p<0.001) inSpeech ABR. Conclusions: It seems that speech processing in older people is deterioratedcomparing with young people regardless of their normal peripheral auditory thresholds. Thisdecrease will result in weaker perception and improper segregation of speech from othercompeting sources.
Atta, Ananta Kumar,Kim, Seul-Bi,Heo, Jungseok,Cho, Dong-Gyu American Chemical Society 2013 ORGANIC LETTERS Vol.15 No.5
<P>The Hg(II)-specific intramolecular cyclization reaction of ethynyl phenols was carried out for the first time in semiaqueous media at ambient temperature. The reaction unit (ethynyl phenol) was coupled with a malononitrile derivative (signal unit), which afforded the chromogenic Hg(II) indicator <B>7</B>. The reaction of the chromogenic Hg(II) indicator <B>7</B> was further optimized in DMSO/water (3:7, v/v) (10 mM PBS buffer, pH = 7.0). Compound <B>7</B> displays a color change from blue to pale yellow in the presence of Hg(II).</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/orlef7/2013/orlef7.2013.15.issue-5/ol4000873/production/images/medium/ol-2013-000873_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ol4000873'>ACS Electronic Supporting Info</A></P>
Atta Shubhadip,Halder Monalisa,Dey Santanu,Raul Chandan Kumar,Meikap Ajit Kumar 한국물리학회 2023 Current Applied Physics Vol.47 No.-
We have reported dielectric and magnetocaloric effects in flexible Neodymium (Nd) doped nickel ferrite (NiNdxFe2-xO4) - polyvinyl-alcohol nanocomposite films. The samples are characterized by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer and broadband dielectric spectroscopy. The dielectric permittivity is enhanced in the composite for a particular filler concentration. The magnetic entropy change decreases by higher doping in the polymer chain. The magnetodielectric coefficient is enhanced in higher frequency and with the rise in doping concentration. The observed skin depth value of the polymer nanocomposite is lower than the film’s thickness which is suitable for electromagnetic shielding.
Atta ur rehman,Jeong Bae Lee,Abdul Qudoos,Sadam Hussain Jakhrani,Hong-Gi Kim,Jae-Suk Ryou 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.3
In this study, nano titanium dioxide and nano silica have been added in white Portland cement mortars. The dosage of nano-TiO2 was fixed to 3% while the dosage of nano-SiO2 was varied from 0%-3%. Water/binder ratio was 0.45% and binder/sandratio was 1:3. The workability, water absorption, compressive and flexural strengths of mortars was measured. Thepermeability of mortars was measured using Nordest test and the carbonation resistance was measured in a carbonationchamber. The degradation of rhodamine B dye on the surface of mortars was measured after exposure of the white mortarsto the ultraviolet light. Addition of nano-SiO2 increased the compressive and flexural strengths of mortars, reduced the waterabsorption of mortars and resisted the penetration of chloride ions. The self-cleaning of the white mortars was unaffected bythe addition of nano-SiO2 particles.
Finite element-based software-in-the-loop for offline post-processing and real-time simulations
Atta Oveisi,T. Arriessa Sukhairi,Tamara Nestorović 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.6
In this paper, we introduce a new framework for running the finite element (FE) packages inside an online Loop together with MATLAB. Contrary to the Hardware-in-the-Loop techniques (HiL), in the proposed Software-in-the-Loop framework (SiL), the FE package represents a simulation platform replicating the real system which can be out of access due to several strategic reasons, e.g., costs and accessibility. Practically, SiL for sophisticated structural design and multi-physical simulations provides a platform for preliminary tests before prototyping and mass production. This feature may reduce the new product’s costs significantly and may add several flexibilities in implementing different instruments with the goal of shortlisting the most cost-effective ones before moving to real-time experiments for the civil and mechanical systems. The proposed SiL interconnection is not limited to ABAQUS as long as the host FE package is capable of executing user-defined commands in FORTRAN language. The focal point of this research is on using the compiled FORTRAN subroutine as a messenger between ABAQUS/CAE kernel and MATLAB Engine. In order to show the generality of the proposed scheme, the limitations of the available SiL schemes in the literature are addressed in this paper. Additionally, all technical details for establishing the connection between FEM and MATLAB are provided for the interested reader. Finally, two numerical sub-problems are defined for offline and online post-processing, i.e., offline optimization and closed-loop system performance analysis in control theory.