Characterization of alkali activated geopolymer mortar doped with MWCNT

Khater, H.M.,Abd el Gawaad, H.A. Techno-Press 2015 Advances in materials research Vol.4 No.1

This paper aimed to investigate the effect of MWCNTs on properties of slag Geopolymeric mortar. Geopolymeric matrices containing different MWCNTs concentrations (0.0, 0.1, 0.2, 0.3 and 0.4 % by weight of the used binder) were synthesized. The Geopolymer mortar composed of aluminosilicate slag to sand (1:2), while the alumino silicate source binder composed of 50% air cooled slag and 50%water cooled slag both passing a sieve of $90{\mu}m$, while the sand passing a sieve of 1 ml. The materials prepared at water/binder ratios in a range of 0.34-0.39% depending on the added MWCNT, whereas the Gelenium Ace-30 superplasticizer used in the ratio of 1.4-2.2% from the total dry weight for better dispersion of MWCNT under sonication for 15 min. Alkaline activation of the Geopolymer mortar was carried by using of 6% NaOH. Curing was performed under temperature of $40^{\circ}C$ and 100% R.H. Results showed that the addition of MWCNTs enhanced the resulting amorphous geopolymer structure with marked decrease in the drying shrinkage as well as water absorption specially when using 0.1% MWCNT, while further increase in MWCNTs results in agglomeration in MWCNT within the matrix and so hinder the propagation of Geopolymerization reaction and negatively affect the formed geopolymer structure.

Effect of firing temperatures on alkali activated Geopolymer mortar doped with MWCNT

Khater, H.M.,Gawwad, H.A. Abd El Techno-Press 2015 Advances in nano research Vol.3 No.4

The current investigation aims to study performance of geopolymer mortar reinforced with Multiwalled carbon nanotubes upon exposure to $200^{\circ}C$ to $1000^{\circ}C$ for 2 hrs. MWCNTs are doped into slag Geopolymer mortar matrices in the ratio of 0.0 to 0.4, % by weight of binder. Mortar composed of calcium aluminosilicate to sand (1:2), however, binder composed of 50% air cooled slag and 50% water cooled slag. Various water / binder ratios in the range of 0.114-0.129 used depending on the added MWCNT, while 6 wt., % sodium hydroxide used as an alkali activator. Results illustrate reduction in mechanical strength with temperature except specimens containing 0.1 and 0.2% MWCNT at $200^{\circ}C$, while further increase in temperature leads to decrease in strength values of the resulting geopolymer mortar. Also, decrease in firing shrinkage with MWCNT up to 0.1% at all firing temperatures up to $500^{\circ}C$ is observed, however the shrinkage values increase with temperature up to $500^{\circ}C$. Further increase on the firing temperature up to $1000^{\circ}C$ results in an increase in the volume due to expansion.

Nano-Silica effect on the physicomechanical properties of geopolymer composites

Khater, H.M. Techno-Press 2016 Advances in nano research Vol.4 No.3

Addition of nano-$SiO_2$ (NS) to geopolymer composites has been studied through measurement of compressive strengths, FTIR and XRD analysis. Alumino-silicate materials are coarse aggregate included waste concrete and demolished walls with its cementing binder, cement kiln dust (CKD) used and can possess a pronouncing activation for the geopolymer reaction resulting from the high alkali contents within. Materials prepared at water/binder ratios in a range of 0.30: 0.40 under curing of $40^{\circ}C$ and 100% Relative Humidity (R.H.), while the used activator is sodium hydroxide in the ratio of 2 wt. %. First, CKD is added in the ratio from 10 up to 50 wt., %, and the demolished walls was varied depending on the used CKD content, while using constant ratio of waste concrete (40 wt., %). Second step, depending on the optimum CKD ratio resulted from the first one (40 wt. %), so the control geopolymer mix composed of cement kiln dust, demolished walls and waste concrete in the ratio (40:20:40, wt %). Nano-silica partially replaced waste concrete by 1 up to 8%. Results indicated that, compressive strengths of geopolymer mixes incorporating nano-silica were obviously higher than those control one, especially at early ages and specially with 3%NS.

Application of Laser-ablated Plasmas to Compositional Analysis of Steel in the Vacuum Ultraviolet

Mohamed A Khater 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.6

Time-integrated spatially-resolved emission spectroscopy, in the deep vacuum ultraviolet (VUV) region, of laser-produced plasmas was employed for the quantitative determination of the carbon content in steel targets. Six prominent VUV carbon spectral lines, representing three different ionization stages, were selected and proved to be spectral interference free. Several experimental parameters and conditions, including the focusing lens type, the laser power density, the background atmosphere and the pressure, were optimized, leading to an optimum limit of detection for carbon of 1 ppm obtained with the 97.70-nm CIII spectral line. Thus article presents a summary of the overall results obtained from this study.

Rehabilitation Ecology by Revegetation: Approach and Results from Two Mediterranean Countries

Martin, Arnaud,Khater, Carla,Mineau, Herve,Puech, Suzette The Ecological Society of Korea 2002 Journal of Ecology and Environment Vol.25 No.1

Human activities greatly affect the environment causing its degradation. Urban development and road networks construction cause main impacts on ecosystems and particularly on vegetation cover: road constructions induce complete degradation of the vegetation cover and often leaves a hare land, sometimes without even a soil cover. Reconstitution of vegetation cover is necessary to limit superficial erosion and land slipping on the road, towards a reintegration of the site in the neighbouring landscape. Many approaches have been studied over the last 30 years aiming at this reconstitution of vegetation cover. At frost, the main purpose of land reclamation was to create a new ecosystem. At this time, the environment created was rather a "garden" with a new soil adapted to the plantation of "decorative" species. Then, in early 90′s many studies on the restoration ecology concept rather focused on adapting the vegetation to the existing conditions on the site, as in a side road embankment for example. Nowadays, we notice a large tendency towards the use of such adapted native species instead of industrially produced seeds. In southern France, our team have led research on the potentials of those local species for their use in revegetation processes with hydro-seeding. We therefore developed an approach combining the use of different types of species: Industrially produced, native and wild cultivated species. This method integrates the benefits of using available low costing seeds that are already used on large scale projects with better adapted species, issued form the cultivation of native species and seed production for their use on smaller scale and more costly but more effective results. The use of wild cultivated species seeds was developed in order to limit the cost and reduce harsh natural seed withdrawal in the natural environment In the case of the use of native species. Besides, the use of such seeds allowed a larger geographical scale of use than with local native seeds. In addition, our team began two years ago a research project in Lebanon aiming at the Introduction and development of the revegetation techniques in Lebanon. In fact, this country bared since 20 years the consequences of urban pressure on its environment especially by the development of quarries and road networks. Therefore, pioneer work is necessary to aim at the adaptation of these techniques to the local environment.

Factors that Influence Awareness of Breast Cancer Screening among Arab Women in Qatar: Results from a Cross Sectional Survey

Donnelly, Tam Truong,Al Khater, Al-Hareth,Al-Bader, Salha Bujassoum,Al Kuwari, Mohammed Ghaith,Malik, Mariam,Al-Meer, Nabila,Singh, Rajvir,Fung, Tak Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.23

Background: Breast cancer is the most common cancer among women in the State of Qatar. Due to low participation in breast cancer screening (BCS) activities, women in Qatar are often diagnosed with breast cancer at advanced stages of the disease. Findings indicate that low participation rates in BCS activities are significantly related to women's low level of awareness of breast cancer screening. The objectives of this study were to: (1) determine the factors that influence Qatari women's awareness of breast cancer and its screening activities: and (2) to find ways to effectively promote breast cancer screening activities among Arabic speaking women in Qatar. Materials and Methods: A multicenter, cross-sectional quantitative survey of 1,063 (87.5% response rate) female Qatari citizens and non-Qatari Arabic-speaking residents, 35 years of age or older, was conducted in Qatar from March 2011 to July 2011. Outcome measures included participant awareness levels of the most recent national recommended guidelines of BCS, participation rates in BCS activities, and factors related to awareness of BCS activities. Results: While most participants (90.7%) were aware of breast cancer, less than half had awareness of BCS practices (28.9% were aware of breast self-examination and 41.8% of clinical breast exams, while 26.4% knew that mammography was recommended by national screening guidelines. Only 7.6% had knowledge of all three BCS activities). Regarding BCS practice, less than one-third practiced BCS appropriately (13.9% of participants performed breast self-examination (BSE) monthly, 31.3% had a clinical breast exam (CBE) once a year or once every two years, and 26.9% of women 40 years of age or older had a mammogram once every year or two years). Awareness of BCS was significantly related to BCS practice, education level, and receipt of information about breast cancer and/or BCS from a variety of sources, particularly doctors and the media. Conclusions: The low levels of participation rates in BCS among Arab women in this study indicate a strong need to increase awareness of the importance of breast cancer screening in Qatari women. Without this awareness, compliance with the most recent breast cancer screening recommendations in Qatar will remain low. An increased effort to implement mass media and public health campaigns regarding the impact of breast cancer on women's health and the benefits of early detection of breast cancer must be coupled with an enhanced participation of health care providers in delivering this message to Qatar population.

THE PAINLEVE' PROPERTY, COMPLETE INTERGRABILITY AND BÄCKLUND TRANSFORMATIONS FOR A FAMILY OF LIOUVILLE EQUATIONS

El-Sabbagh, M.F.,Khater, A.H. Department of Mathematics 1989 Kyungpook mathematical journal Vol.29 No.1

Three Dimensional Simulation Dynamics for the Dilute Colloidal Suspensions of Rod-Like Polymer Particles Flowing in the Bulk and Near Solid Boundaries

Ali Atwi,Antoine Khater,Abbas Hijazi 한국고분자학회 2013 Macromolecular Research Vol.21 No.11

Numerical simulations and algorithms are developed to analyze the dynamics of rigid rod-like polymer particles. We developed a theoretical model based on the equations of Jeffrey for the dynamics of rigid polymer particles in fluids and the molecular dynamics by mechanical restitution for the diffusive collisions of the particles at the solid boundaries. The simulations are developed to calculate the dynamic equilibrium probability distribution functions (PDF) distributions for rod-like polymer particles in colloidal suspensions in a fluid under hydrodynamic flow inside pores with solid boundaries. They are carried out for idealized atomically flat and the realistic rough surface boundaries. To accomplish this, we investigate the influence of the surface roughness on the choice of the hydrodynamic boundary conditions. The simulation results for the PDF distributions for the spatial positions and orientations of rod-like polymer particles are calculated, over several orders of magnitude of the rotational Peclet number. They demonstrate the importance and significance of modeling in a three-dimensional spatial frame as compared to the simulation results over a two-dimensional spatial frame. In particular we are able to produce a complete topography for the PDF distributions segmented as a hierarchy in the depletion layer by covering a complete range of orientations in 3D spatial frames. These simulations permit to calculate the nematic order parameter over its tensorial representation for the colloidal suspensions of rod-like polymer particles locally, and throughout the pore space including the depletion layer. Our results for the nematic order parameter are hence innovating and represent a new input for these systems.

Addressing Factors Associated with Arab Women's Socioeconomic Status May Reduce Breast Cancer Mortality: Report from a Well Resourced Middle Eastern Country

Donnelly, Tam Truong,Al Khater, Al-Hareth,Al Kuwari, Mohamed Ghaith,Al-Bader, Salha Bujassoum,Abdulmalik, Mariam,Al-Meer, Nabila,Singh, Rajvir,Fung, Tak Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.15

Differences in socioeconomic status (SES) such as income levels may partly explain why breast cancer screening (BCS) disparities exist in countries where health care services are free or heavily subsidized. However, factors that contribute to such differences in SES among women living in well resourced Middle East countries are not fully understood. This quantitative study investigated factors that influence SES and BCS of Arab women. Understanding of such factors can be useful for the development of effective intervention strategies that aim to increase BCS uptake among Arab women. Using data from a cross-sectional survey among 1,063 Arabic-speaking women in Qatar, age 35+, additional data analysis was performed to determine the relationship between socioeconomic indicators such as income and other factors in relation to BCS activities. This study found that income is determined and influenced by education level, occupation, nationality, years of residence in the country, level of social activity, self-perceived health status, and living area. Financial stress, unemployment, and unfavorable social conditions may impede women's participation in BCS activities in well resourced Middle East countries.

Chemical and Biological Indicators of Soil Quality in Organic and Conventional Farming Systems

Mai Rehan,Hassan Ahmed Khater,Mohamed Abdelalim Ali,Mohamed Abdul Aziz Daif 한국농약과학회 2017 한국농약과학회 학술발표대회 논문집 Vol.2017 No.4