6^th International Conference and Exhibition on Materials Science and Engineering September 12-14, 2016 Atlanta, Georgia, USA

Dr. Zain M. Al-Amoudi, Doctor of Philosophy in Science, (Experimental Physics) from King Abdulaziz University (KAU), Faculty of Science, Physics Department, Associate Professor. She has Head of physics department 4 years. She has published more than 15 papers in reputed journals, She has attended and participated in many National and International conferences.

In this study, the natural radio activities of ⁴⁰K, ²²⁶Ra,and ²³²Th and the man- made of ¹³⁷Cs in samples of solid wastes of (TIG) welding process, collected from the welding workshops in different locations of Saudi Arabia (Jeddah, Asfan and Tabuk). The concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs were determined by gamma-ray spectrometer using HPGe detector. The results show that the average concentrations were 44.8, 50.23, 431.82 and 1.5 Bq /Kg, respectively. Radium equivalent activities of the samples under consideration were calculated with an average value of 127 Bq/Kg .The total absorbed dose in the study samples ranged between the lower value (0.027) mGy/h (sample No.4) to the higher value (0.628) mGy/h (sample No.5), with an average value of (0.19) mGy/h which is lower than the limits as recommended by (UNSCEAR 2000). Also, heavy metals analyses were done by atomic absorption spectrophotometer. The concentration’s average values of Ca, Fe, K, Mg, Bi, Pb and Th elements in the samples of welding workshops waste were 1.02%, 63.18%, 0.25%, 0.25%, 76.99 ppm, 62.87 ppm and 17.63 ppm respectively.
The data were discussed and compared with limits given by United Nations Scientific Committee for the effects of Atomic Radiation (UNSCEAR).

Cr₂O₃ nanoparticles were synthesized by biological method using neem plant extract. The synthesized nanoparticles are characterized by SEM, UV-Vis, FT-IR and XRD methods. The size of the nanoparticles were shown to be 35.5nm. This synthesized Cr₂O₃ nanoparticles were embedded in PVA polymert. The strustural, electrical and optical properties of nanocomposite films were studied experimentally. The effect of concentration of PVA on PVA films and concentration of Cr₂O₃ nanoparticles were studied. The structural properties are studied using X-ray diffraction, SEM and FT-IR spectra. Optical property is studied using UV-Vis spectroscopy. Results showed number of Braggs planes in the structure of polymer and its crystallinity are increased notiecbly. The ℷ max of Cr₂O₃ nanoparticles undergoes a blue shift toward the lower wavelength after embedding. Scanning electron microscopy shows that the prepared Cr₂O₃ nanoparticles were despersed and nearly uniform in diameter within the polymeric matrix. Frequency dependent conductivity, photo-voltaic activity and viscosity measurements of PVA and PVA/Cr₂O₃ nanocomposites films/ solutions are also compared. The induced structural changes are revealed through XRD and FT-IR spectroscopy. The synthesized Cr₂O₃ nanoparticles showed very good biological activity and acts as a catalyst for KMnO₄ decomposition with the evolution of O₂, which plays an important role in renewable source of energy.

Amit Bhalla is pursuing his Ph.D from University of Witwatersrand under supervision Prof R. Hurman Eric.

A high carbon ferrochromium alloy containing 6.8% C was subjected to solid state decarburization process conducted under a gaseous mixture of CO and CO₂ at temperatures between 800℃ and 1100℃. The carbide phases present in the initial alloy was identified in the form of (Fe,Cr)₇C₃. The degree of decarburisation increased with increasing temperature and decreasing particle size. A maximum of 58% decarburization was achieved with (-1.00 + 0.50) µm size fraction group reacted at 1100℃ under pure CO₂ which yielded 2.82% C content in the final decarburized alloy. The carbide phases present in the final alloy was identified by XRD analysis in the form of Fe₃C and Cr₂₃C₆. The carbon analysis were based on the SEM-EDS results and verified according to the mass balance calculations. The final carbon content which depends upon temperature and particle size is in the range of carbon content of a medium carbon ferrochromium alloy.

Fatmah Bahabri has completed her PhD at the age of 33 years from King Abdulaziz University and also the postdoctoral studies. She is the member of Physics Department and has been serving as Deputy Director of the Nanotechnology Center for two years 2014 and 2015. She has published more than 25 papers in reputed journals and has been serving as a head of physics department for 16 years sporadic 1991-2012, and Vice Dean of the Girls Faculty of Science for two year 1997 and 1998 . She is a member of Graduate Studies.

The coupling of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry with 13C nuclear magnetic resonance (NMR) is a suitable method for examining the composition of hydrolysable tannins and has been applied to the investigation of valonia oak (Quercus aegylops) acorn tannin extract. Such methods can determine the extract’s structural aspects and other characteristics. It was determined that valonia oak acorn tannin extract is composed of mainly pentagalloylglucose structures; their rearrangement structures, vescalagin/castalagin (with linkages to flavogallonic acid) and vescalin/castalin; ellagic acid and vescavaloneic/castavaloneic acid; and free gallic acid and glucose. Traces of catechin gallate were also observed in this tannin extract. The tannin from acorns of valonia oak was used to substitute up to 50% of the phenol used in the preparation of phenolic resins as adhesives for wood particleboard. These phenol-tannin-formaldehyde resins showed comparable performance to phenol-formaldehyde resins.

Jonghun Yoon has completed his PhD in the Mechanical and Aerospace Engineering Department at Korea Advanced Institute of Science and Technology (KAIST) in 2008. He had worked for Univ. of Florida as a Post-doctoral Associates for three years in the fields of Yield Surface Modeling and Plasticity. He is currently an Assistant Professor in the Department of Mechanical Engineering, Hanyang University after he had worked for Korea Institute of Materials Science as a Senior Researcher from 2011 to 2013.

This paper is concerned with the strain hardening behavior of commercially pure titanium and magnesium alloys for a wide range of strain rates. Pure titanium has described as having three stages of strain hardening behavior during compressive deformation. The stress-strain curve of pure titanium can be divided into three stages according to the strain hardening rate, and the strain hardening rate can be determined by the slope of the stress-strain curve. Mg alloy undergoes the dynamic recrystallization (DRX) during hot working process, which is a restoration or softening mechanism to reduce the dislocation density and release the accumulated energy to facilitate plastic deformation. Even though there are substantial progresses on the establishment in terms of the DRX principles and evolution with the view point of the materials science, an appropriate flow curve modeling for the finite element analysis has been deficient to take into consideration of softening behavior. A novel rate-dependent hardening model is proposed by keeping trace of deformation twins and DRX with increase in the compressive strain, which induces the variation of the strain hardening rate.

Mymona Abutalib is an Associate Professor and completed her PhD at the age of 29 year from King Abulaziz University and postdoctoral studies from King Abdulaziz University School of Physics. She is the director of Material Science and Radiation. She has published more than 20 papers in reputed journals.

Samples from sheets of CR 6-2 polymeric materials have been exposed to gamma rays in the dose range 20-400 KGy. The modifications induced in CR 6-2 samples due to gamma irradiation have been studied through different characterization techniques such as X-ray diffraction XRD, intrinsic viscosity, refractive index and color difference studies. The results indicated that the crosslinking is the dominant mechanism at the dose ranges 150-400 KGy. This crosslinking destroyed the degree of ordering in the CR 6-2 samples associated with an increase in intrinsic viscosity values. This indicates an increase in the average molecular mass. Additionally, the non irradiated CR 6-2 sample showed significant color sensitivity towards gamma irradiation. The sensitivity in color change towards gamma irradiation appeared in the change in the blue color component of the non irradiated CR 6-2 film to yellow after exposure to gamma up to 400 KGy. This is accompanied by a net increase in the darkness of the samples.

Dr. Felix Jaetae Seo authored and co-authored over 350 publications and presentations in the last two decades. He is a Professor of Physics, Director of the Advanced Center for Laser Science and Spectroscopy, and Group Leader of Nanophotonics and Quantum Optics at Hampton University, USA. He is currently serving as an Associate Editor of Optics and Photonics Journal; and Editor-in-Chief for the Journal of Photonics and Optoelectronics.

The broadband spontaneous emission of excitons in CdSe quantum dots (QDs) is of great interest for optical applications in the visible and near infrared spectral region. Typical semiconductor QDs near the bulk Bohr radius exhibit wide spectral tunability and high color purity due to quantum confinement of excitons within the dot boundary, however, QDs which have an increased role from the surface due to the increased surface-to-volume ratio with decreasing size can be utilized for white light optical applications. The surface-trapped state transition facilitates the broadband emission and therefore was characterized through temperature dependent and time-resolved spectroscopy in relation the bandedge transition. The photoluminescence (PL) was observed to have a ~3.5-fold contribution from the band edge transition compared to the surface-trapped state with a combined spectral coverage of ~400 nm (~550 nm - ~950 nm) at room temperature. The time-resolved spectroscopy confirmed the average lifetime of the band edge transition to be ~30 times faster than that of the surface trapped state transition. This result indicates that unconventional CdSe QDs are capable of being used for white light emitting diodes (LEDs) due to their broad, tunable spectral nature and fast lifetimes. Acknowledgement: This work at HU is supported by ARO W911NF-15-1-0535, NSF HRD-1137747and NASA NNX15AQ03A

Haoyang Wu is currently reading a doctorate in materials science and engineering in university of Science and Technology Beijing. Her research areas include research on preparation of vanadium based materials by low temperature combustion synthesis and their applications. She has published almost 6 papers in reputed journals.

Uniform VN nanoparticles encapsulated in carbon sheets (VN@C) for a stable high energy lithium ion anode have been successfully synthesized by a facile solution combustion method combined with a thermal treatment at 600 oC under ammonia atmosphere.The as-synthesized VN@C sheets display high performance as an anode material for lithium ion batteries, including high reversible lithium storage capacity (640 mAhg-1 at 1 Ag-1 after 500 cycles), high Coulombic efficiency (~99%), excellent cycling stability and good rate capability due to their unique structure. VN nanoparticles encapsulated in conductive carbon sheets not only provide a large quantity of accessible active sites for lithium ion insertion/extraction along with good conductivity and short transport path for both electrons and lithium ions, but also can effectively circumvent the volume expansion/contraction associated with lithium insertion/extraction. In addition, the approach reported in this work is also applicable to other metal nitride nanoparticles encapsulated in carbon sheets, which may find important applications as electrodes, catalysts, adsorbents, and sensors in many disciplines.

Srivas M C, Srivas M.C is a student of the undergraduate programme in Telecommunications at B.M.S College of engineering, Bangalore, Visvesvaraya technological university, India.. Has keen interest in the field of electronics and has worked on several projects.

In any urban area with public amenities like schools, hospitals, parks, etc. which see a lot of footfall during all parts of the year, there are innumerable cases of accidents happening due to speeding vehicles. Now, despite traffic signs highlighting the need for caution in school and hospital-zones, it is apparent that motorists are willing to sacrifice their own safety and others’ just to get to their destination on time. The problem which we face is that vehicles in sensitive public zones do not limit their speed, thereby endangering the lives of pedestrians and fellow motorists. The scope for the use of embedded systems in automobiles has increased manifold over the last decade. Problems like over speeding, rash driving can be solved by an Electronic Control Unit i.e. ECU that is meant solely for the purpose of reducing the speed of the car when connected to a Wi-Fi network. The systems that use radio frequency and infrared system technology need more number of sensors and installations for its operation, whereas this problem is overcome by using a Wi-Fi installation that provides a network for a wider range. Hence, an effective solution would be, to have an efficient speed limiter technology that requires the least amount of set up area and is preferably intended for a hospital or school environment. Since it is challenging to provide manual services for enforcing the speed limit on vehicles at all times, we have come up with a solution which will automatically detects, notifies and reduces the speed of the vehicles and maintains it under a limit in the specified zone. This is done by providing a Wi-Fi network which is detected by the Electronic Control Unit i.e. ECU of the vehicle when in the sensitive zone. This ECU, along with its usual operations like airbag system, anti-lock braking system, black box, adaptive cruise control, drive by wire, heads up display, back up collision sensors, navigational systems, tyre pressure monitor would slightly increase its complexity and sophistication by having a Wi-Fi receiver module which in turn is linked to the throttle valve, thereby reducing the speed of the vehicle. Installing this device in various zones will not only minimize the chance of accidents to a great extent but also reduces the liability of the driver as safety is automatically monitored by restricting the speed. Thereby, making use of the range of Wi-Fi signal we can minimize the number of substations owing to lesser set up area. This will help a long way in improvising the technology and benefitting the society.

Dr. Felix Jaetae Seo authored and co-authored over 350 publications and presentations in the last two decades. He is a Professor of Physics, Director of the Advanced Center for Laser Science and Spectroscopy, and Group Leader of Nanophotonics and Quantum Optics at Hampton University, USA. He is currently serving as an Associate Editor of Optics and Photonics Journal; and Editor-in-Chief for the Journal of Photonics and Optoelectronics.

Time-resolved and temperature-dependent photoluminescence (PL) spectroscopy was carried out on ternary compound copper indium disulfide (CuInS₂, or CIS) core materials and CIS/ZnS coreshells which revealed spectral, temporal, and thermal characteristics associated with surface-defect and shallow- or deep-trapped states. Surface trapped state recombination can arise from the discontinuity of crystal regularity, dangling atoms, and/or any impurities on the surface of the compounds while shallow or deep defect-related donor-acceptor transitions occur due to the chalcopyrite crystal structure of the ternary compound forming through regular substitutions of I-III group atoms with the II-group lattice. The time-resolved PL studies of ternary compounds CIS and CIS/ZnS indicate the existence of short lived surface-trapped and interface defect-related states respectively, along with long lived intrinsic defect-related states. The temperature-dependent spectroscopy explains that the PL from deep-trapped donor-acceptor state has relatively large thermal quenching, due to the relative Coulomb interaction of donor-acceptor pairs, compared to the thermal quenching of PL from interface-defect states and shallow-trapped donor-acceptor states. Acknowledgement: This work at HU is supported by ARO W911NF-15-1-0535, NSF HRD-1137747and NASA NNX15AQ03A

Quinton Rice is a graduate student in the Ph.D. Physics program at Hampton University. He has published and presented around 15 papers and conference presentations. He received the Best Student Paper award at the Virginia Academy of Science in 2014.

The atomic layers of 2-dimensional transition metal dichalcogenides (TMDCs, MX₂; M=Mo or W; X=S, Se, or Te) are of great interest in the areas of optoelectronic and photonic applications due to the correlation between valley orbital, spin, and optical helicity; the compositional tuning of exciton bandgaps in visible and near-infrared spectra; the crystal symmetry changes for odd to even layers; and the bandgap modification from direct for monolayer and indirect for bilayer or multilayer. The exciton bandgap management of semiconductors is essential for optoelectronic and photonic applications. In this work, the temperature-dependent bandgap of TMDCs is analyzed using the O’Donnell and Chen relation with variable parameters including the average acoustic phonon energy involving in the electron-phonon interaction and the coupling strength between electrons and phonons. The analysis shows that the exciton band energy is decreased as the temperature is increased. For a constant acoustic phonon energy, the larger (smaller) electron-phonon coupling strength results in the wider (narrower) tunability of exciton bandgap. The bandgap was changed from 2 eV to 0.5 eV with weakly coupled electrons (S=2) and strongly coupled electrons (S=30), respectively, while the weak coupling leads to a linear decrease in the bandgap energy with temperature after ~85 K and the strong coupling after ~60 K. However, for a constant electron-phonon coupling strength, the larger (smaller) acoustic phonon energy results in narrower (wider) tunability of the bandgap. This study indicates the ability to control the exciton bandgap through the electron-phonon interaction as well as the average acoustic phonon energy at various temperatures. Acknowledgement: This work at HU is supported by ARO W911NF-15-1-0535, NSF HRD-1137747and NASA NNX15AQ03A

Mr. Tikaram Neupane is first year graduate student in Physics department at Hampton University, Hampton, VA. He has completed master’s degree in Physics from University of Wyoming, Laramie, USA. Recently, he is working in third-order nonlinear optics for the application of photonic devices.

The monolayer of TMDC has a direct bandgap, and the bilayer and multilayer have an indirect band gap. The bandgap of monolayer is wider than that of bilayer and multilayer. The change of bandgap plays an important role in the nonlinear absorption process. The Jablonski diagrams of nonlinear absorption process may include two-step absorption with one-photon for each step, two-photon absorption to the real final state through a virtual intermediate state, and two-photon excitation to the virtual final state through a virtual intermediate state. In the one-photon excitation, the electric dipole transition is allowed due to other parities between two states. Therefore, the ground-state absorption cross-section is higher than the excited-state absorption cross-section, , that implies the dominant saturable (or negative) absorption (SA). In the two-photon excitation, the electric dipole transitions and are allowed due to same parities between the initial and final states. Therefore, the excited-state absorption cross-section is higher than the ground-state absorption cross-section, , that implies the dominant reversal saturable (or positive) absorption (RSA). The atomic layers with SA are utilized for laser Q-switch and mode-locker, and the atomic layers with RSA are utilized for optical power limiter. For the excitation near bandgap, the bandgap modification due to number of layers and temperature, and the creation of trion state due to charge injection switch over RSA to SA or vice versa. Acknowledgements: This work at HU is supported by NSF HRD-1137747, ARO W911NF-11-1-0177, and NASA NNX15AQ03A.

Quinton Rice is a graduate student in the Ph.D. Physics program at Hampton University. He has published and presented around 15 papers and conference presentations. He received the Best Student Paper award at the Virginia Academy of Science in 2014.

The 2-dimensional atomic layer transition metal dichalcogenides (TMDCs, MX2; M=Mo or W; X=S, Se, or Te) are of particular significance in the areas of optoelectronic and photonic applications because of the structural tunability of exciton bandgaps in visible and near-infrared spectra and the bandgap changes from direct for monolayer and indirect for bilayer or multilayer. While managing the exciton bandgap of semiconductors is important for optoelectronic and photonic applications, the role of the acoustic phonon energy and electron-phonon coupling is critical to the formation of excitons. In this work, the temperature-dependent bandgap of TMDCs is analyzed using the derivative of the O’Donnell and Chen relation which gives the change in entropy of exciton formation when the bandgap energy is taken as the the standard Gibbs free energy. The analysis indicates the change in entropy of exciton formation with higher energy phonons (100 meV) is constant until ~90 K while lower energy phonons (10 meV) approach a constant value of -2Sk_B between ~250 K and ~300 K where S is the electron-phonon coupling strength and is Boltzmann’s constant. The less energetic phonons are highly influenced by the electron-phonon interaction which may be due to increased scattering and spontaneous decay probabilities of higher energy phonons. The change in entropy of exciton formation can be increased ~3-fold while the bandgap is managed using the electron-phonon coupling strength compared to the average acoustic phonon energy. Acknowledgement: This work at HU is supported by ARO W911NF-15-1-0535, NSF HRD-1137747and NASA NNX15AQ03A.

Mr. Tikaram Neupane is first year graduate student in Physics department at Hampton University, Hampton, VA. He has completed master’s degree in Physics from University of Wyoming, Laramie, USA. Recently, he is working in third-order nonlinear optics for the application of photonic devices.

Plasmonic coupling of CdSe quantum dots (QDs) have been extensively studied due to their advantageous application to optoelectronics. Wide optical tunability, high color purity, and large PL enhancement in the vicinity of plasmonic nanoparticles, are the most prominent features of typical CdSe QDs, while the reduced size allows for straightforward integration with electronic devices. CdSe QD fluorescence originates from exciton carrier recombination, whereas discrete energy states and blue-shift from the bulk bandgap (~712 nm) arises from quantum confinement of these carriers when the QDs are near the exciton Bohr radius (~5.8 nm). Bandegde and surface-trapped state transitions are the main emission sites and play an important role in the shape of the optical spectra which are largely the focus of this article along with plasmon-coupling of these transitions. PL enhancement and decreased exciton lifetime can occur through plasmon-exciton coupling via the Coulomb interaction however this effect has been largely studied for the band edge transition and not the surface trapped state transition. Exciton lifetimes were observed to be reduced ~2 fold for the dominant band edge transition while the surface trapped state saw minor enhancements and even increased lifetimes at longer wavelengths due to increased non-radiative energy transfer from the Au nanoparticles. The temperature dependent measurements indicated that band edge transition of plasmon-coupled CdSe were subject to thermal expansion and possibly plasmon-exciton–phonon coupling while the increased PL intensity was observed due to reduction of non-radiative decay. Acknowledgement: This work at HU is supported by ARO W911NF-15-1-0535, NSF HRD-1137747and NASA NNX15AQ03A