Materials Science and Engineering Commons^™

Hydrometallurgical Process For Extraction Of Metals From Electronic Waste-Part I: Material Characterization And Process Option Selection, Zeljko J. Kamberovic

Zeljko J Kamberovic

Used electronic equipment became one of the fastest growing waste streams in the world. In the past two decades recycling of printed circuit boards (PCBs) has been based on pyrometallurgy, higly polluting recycling technology whic causes a variety of environmental problems. The most of the contemporary research activities on recovery of base and precious metals from waste PCBs are focused on hydrometallurgical techniques as more exact, predictable and easily controlled. In this paper mechanically pretrated PCBs are leached with nitric acid. Pouring density, percentage of magnetic fraction, particle size distribution, metal content and leachability are determined using optical microscopy, atomic …

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mikhail Khenner

A mathematical model for the evolution of pulsed laser-irradiated, molten metallic films has been developed using the lubrication theory. The heat transfer problem that incorporates the absorbed heat from a single laser beam or the interfering laser beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the reflectivity, the peak laser beam …

Effect Of Superconsciousness External Energy On Atomic, Crystalline And Powder Characteristics Of Carbon Allotrope Powders, Mahendra Kumar Trivedi, Rama Mohan Tallapragada

Mahendra Kumar Trivedi

Analysis Of Nonequilibrium Hcp Precipitate Growth In Fcc Matrices: Application To Al–Ag, Daniel Finkenstadt, Duane D. Johnson

Duane D. Johnson

Hexagonal-close-packed (hcp) γ-precipitates with large aspect ratios form rapidly in some face-centered cubic (fcc) solid-solutions. No model explains the observed time-dependent increase in aspect ratio, nor irregular intermediate growth shapes. We propose a nonequilibrium process involving trapezoidal offshoots (controlled only by energetics) that governs the growth behavior (kinetics) and yields nonequilibrium structures in agreement with observation. Then, combining nucleation theory and diffusion-limited growth both of secondary nuclei and ledges, we derive a general growth equation for γ-precipitates due to solute-segregation to precipitate–matrix interfaces that includes our modification of the Jones–Trivedi model for thickening to account for the slow growth of …

Effect Of External Energy On Atomic, Crystalline And Powder Characteristics Of Antimony And Bismuth Powders, Mahendra Kumar Trivedi, Vikram V. Dabhade, Rama Mohan Tallapragada

Mahendra Kumar Trivedi

Optimal Site-Centered Electronic Structure Basis Set From A Displaced-Center Expansion: Improved Results Via A Priori Estimates Of Saddle Points In The Density, Aftab Alam, Duane D. Johnson

Duane D. Johnson

Site-centered, electronic-structure methods use an expansion inside nonoverlapping “muffin-tin” (MT) spheres plus an interstitial basis set. As the boundary separating the more spherical from nonspherical density between atoms, the “saddle-point” radii (SPR) in the density provide an optimal spherical region for expanding in spherical harmonics, as used in augmented plane wave, muffin-tin orbital, and multiple-scattering [Korringa, Kohn, and Rostoker (KKR)] methods. These MT-SPR guarantee unique, convex Voronoi polyhedra at each site, in distinction to Bader topological cells. We present a numerically fast, two-center expansion to find SPR a priori from overlapping atomic charge densities, valid also for disordered alloys. We …

Surface Geometry Of C60 On Ag(111), H. I. Li, K. Pussi, K. J. Hanna, Lin-Lin Wang, Duane D. Johnson, H.-P. Cheng, H. Shin, S. Curtarolo, W. Moritz, J. A. Smerdon, R. Mcgrath, R. D. Diehl

Duane D. Johnson

The geometry of adsorbed C60 influences its collective properties. We report the first dynamical low-energy electron diffraction study to determine the geometry of a C60 monolayer, Ag(111)−(23√×23√)30°−C60, and related density functional theory calculations. The stable monolayer has C60 molecules in vacancies that result from the displacement of surface atoms. C60 bonds with hexagons down, with their mirror planes parallel to that of the substrate. The results indicate that vacancy structures are the rule rather than the exception for C60 monolayers on close-packed metal surfaces.

Production Of Meso-And Giga-Porous Zirconia Particles—An Improved Multi-Step Particle Aggregation Process, Abhinandan Pattanayak

Abhinandan Pattanayak

No abstract provided.

Quantitative Prediction Of Twinning Stress In Fcc Alloys: Application To Cu-Al, Sandeep A. Kibey, Lin-Lin Wang, J. B. Liu, H. T. Johnson, H. Sehitoglu, Duane D. Johnson

Duane D. Johnson

Twinning is one of most prevalent deformation mechanisms in materials. Having established a quantitative theory to predict onset twinning stress τcrit in fcc elemental metals from their generalized planar-fault-energy (GPFE) surface, we exemplify its use in alloys where the Suzuki effect (i.e., solute energetically favors residing at and near planar faults) is operative; specifically, we apply it in Cu-xAl (x is 0, 5, and 8.3 at. %) in comparison with experimental data. We compute the GPFE via density-functional theory, and we predict the solute dependence of the GPFE and τcrit, in agreement with measured values. We show that τcrit correlates …

Bcc-To-Hcp Transformation Pathways For Iron Versus Hydrostatic Pressure: Coupled Shuffle And Shear Modes, J. B. Liu, Duane D. Johnson

Duane D. Johnson

Using density-functional theory, we calculate the potential-energy surface (PES), minimum-energy pathway (MEP), and transition state (TS) versus hydrostatic pressure σhyd for the reconstructive transformation in Fe from body-centered cubic (bcc) to hexagonal closed-packed (hcp). At fixed σhyd, the PES is described by coupled shear (ϵ) and shuffle (η) modes and is determined from structurally minimized hcp-bcc energy differences at a set of (η,ϵ). We fit the PES using symmetry-adapted polynomials, permitting the MEP to be found analytically. The MEP is continuous and fully explains the transformation and its associated magnetization and volume discontinuity at TS. We show that σhyd (while …

Researches On Copper. History & Metallurgy, Fathi Habashi

Fathi Habashi

Non-Process And Chemical Free Offset Printing Plate, Bilge N. Altay, C. Koroglu, O. Yaman, C. Sahin

Bilge Nazli Altay

No abstract provided.

Gold. History, Metallurgy, Culture, Fathi Habashi

Fathi Habashi

Effect Of Salts On The Electrospinning Of Poly(Vinyl Alcohol), Jonathan J. Stanger, Nick Tucker, Mark P. Staiger, Kerry Kirwan, Stuart Coles, Daniel Jacobs, Nigel Larsen

Jonathan J Stanger

Fibres with a diameter in the nanometer range were electrospun from aqueous poly(vinyl alcohol) (PVOH). In order to improve the mass deposition rate and decrease the final fibre diameter salts (NaCl, LiCl, LiBr and LiF) were added to the solution. The aim was to increase the charge density and hence increase the electrostatic forces on the fluid. It was found that with increasing salt concentration the charge density did increase. However the mass deposition rate was found to decrease and the final fibre diameter was found to increase. The decrease in mass deposition rate is explained by considering the concept …

Effect Of Charge Density On The Taylor Cone In Electrospinning, Jonathan J. Stanger, Nick Tucker, Kerry Kirwan, Stuart Coles, Daniel Jacobs, Mark P. Staiger

Jonathan J Stanger

A detailed understanding of charge density and its origins during the electrospinning process is desirable for developing new electrospinnable polymer-solvent systems and ensuring mathematical models of the process are accurate. In this work, two different approaches were taken to alter the charge density in order to measure its effect on the Taylor cone, mass deposition rate and initial jet diameter. It was found that an increase in charge density results in a decrease in the mass deposition rate and initial jet diameter. A theory is proposed for this behaviour in that an increase in charge density leads to the tip …

The Effect Of Electrode Configuration And Substrate Material On The Mass Deposition Rate Of Electrospinning, Jonathan J. Stanger, Nick Tucker, Andrew Wallace, Nigel Larsen, Mark P. Staiger, Roger Reeves

Jonathan J Stanger

Poly(vinyl alcohol) (PVOH) was electrospun using different methods to charge the polymer solution. A positive high voltage relative to the collecting electrode significantly increased the fibre deposition rate. Electron microscopy showed that approximately half of the increase in fibre mass was due to thicker fibres being deposited. The current flowing from the grounded electrode was measured to determine the charge carried on the PVOH jet. This showed that for a positive voltage charging condition there is a much larger current and hence more charge carriers generated in the PVOH solution. As a result, more mass is ejected from the Taylor …

Preparation Of Wo3 Nanoparticles Using Cetyl Trimethyl Ammonium Bromide Supermolecular Template, Nilofar Asim, S. Radiman, M.A. Bin Yarmo

Nilofar Asim

WO3 is one of the most interested metal oxides because of its application as catalysts, sensors, electrochromic devices, ceramic, solar cell, pigments and so on. More investigation is needed to find the good and low cost method for preparation of WO3 nanoparticles with uniform morphology and narrow distribution using a surfactant mediated method. Approach: In this study, the synthesis of WO3 nanoparticles was accomplished using a cationic surfactant (cetyl trimethyl ammonium bromide) as the organic supermolecular template and WCl6 and NH4 OH as the inorganic precursor and counter ion source, respectively. The effects of reaction temperature and surfactant concentration in …

پاسخهای تشریحی سوالات کنکور کارشناسی ارشد رشته شیمی کاربردی-چاپ دوم-ویرایش جدید, A. Khataee, M. H. Rasoulifard, Mir Saeed Seyed Dorraji, V. Vatanpoor

Mir saeed Seyed Dorraji

No abstract provided.

Effect Of Non-Stationary Current Regimes On The Morphology Of Silver Electrodeposits, Zeljko J. Kamberovic

Zeljko J Kamberovic

This work is concerned with the use of reverse current regimes in order to form small-grained and compact silver deposits during the electrorefining process. Several parameters were varied, i.e., i) anodic overpotential, ii) cathodic vs. anodic time ratio and iii) duration of the anodic pulse. After optimization of these parameters, phosphate ions were added and the electrolyte was stirred. The effects of a rise of the anodic overpotential on the grain sizes of the silver deposit and compactness were studied. Prolongation of the anodic time had a similar influence but with a decrease in current efficiency. An increase of the …

Effect Of Filler Incorporation On The Fracture Toughness Properties Of Denture Base Poly(Methyl Methacrylate), Nidal Elshereksi

Nidal Elshereksi

Poly(methyl methacrylate) (PMMA) is the material of choice for denture base construction. In spite of its many good qualities, the application of PMMA as an ideal dental base material is still restricted by a few limitations. One of these is the difficulty in achieving intrinsic radiopacity in the material. The aim of the present study is to investigate the possibility of using barium titanate (BaTiO3) as a radiopacifier in PMMA. The formulation used in this study composed of PMMA 89.5 wt%, BaTiO3 10 wt% and benzoyl peroxide (BPO) 0.5 wt% as an initiator, methyl methacrylate (MMA) 90 wt% as a …

Effect Of Filler Incorporation On The Fracture Toughness Properties Of Denture Base Poly(Methyl Methacrylate), Nidal Elshereksi

Nidal Elshereksi

Poly(methyl methacrylate) (PMMA) is the material of choice for denture base construction. In spite of its many good qualities, the application of PMMA as an ideal dental base material is still restricted by a few limitations. One of these is the difficulty in achieving intrinsic radiopacity in the material. The aim of the present study is to investigate the possibility of using barium titanate (BaTiO3) as a radiopacifier in PMMA. The formulation used in this study composed of PMMA 89.5 wt%, BaTiO3 10 wt% and benzoyl peroxide (BPO) 0.5 wt% as an initiator, methyl methacrylate (MMA) 90 wt% as a …

Chemistry And Metallurgy In The Great Empires, Fathi Habashi

Fathi Habashi

It is remarkable that certain countries expand to become great empires then as time goes by they gradually decline while others rise. This book attempts to briefly trace the history of chemistry and metallurgy through the different empires that became at one time great and then faded away. In 272 pages 21.5 x 28 cm, the author outlines the inter-relation of chemistry, metallurgy, mining, and medicine, the idea of the divinity of kings and the formation of nations, and finally the rise and fall of the empires. He then covers the ancient and medieval empires, followed by the empires from …

Science, Technology, And Society, Fathi Habashi

Fathi Habashi

Science, technology, and society is a vast and complex question. It is discussed here from five points: social responsibility of scientists, migration and movement of scholars, philanthropy and its role in education and culture, enlightened despots and their influence on science and culture, and finally the social aspects of mining. The book is meant for the general reader but can benefit scientists as well. It is fully illustrated with colored pictures. It is hoped that it will serve as an introduction to this field to the young generation and inspire them to serve society.

Discrete Mnalpo-5 Nanocrystals Synthesized By An Ionothermal Approach, Eng-Poh Ng, Satpal Singh Sekhon, Svetlana Mintova

Eng-Poh Ng

Discrete MnAlPO-5 nanocrystals with monomodal particle size distribution (diameter of 80 nm) were synthesized using an ionothermal technique; the pore filling effect of the ionic liquid molecules during the synthesis of microporous nanocrystals is verified.

Selective Capture Of Water Using Microporous Adsorbents To Increase The Lifetime Of Lubricants, Eng-Poh Ng, Luc Delmotte, Svetlana Mintova

Eng-Poh Ng

Eco-recycling towards an increase of the lifetime of lubricating mineral oil by selective capturing of water with nanosized microporous aluminophosphate and aluminosilicate materials is reported. Quantitative water measurements of oxidized lubricating oil before and after treatment with microporous materials were carried out by FT-IR spectroscopy combined with Karl Fischer titration method. The high selectivity of the nanosized aluminophosphate to water without adsorbing other additives in comparison to nanosized aluminosilicates that are adsorbing altogether polar oxidation products, ionic additives and water are revealed. A removal of nearly 98 % of moisture from the lubricating oil at ambient condition is achieved, which …

The Missing Link Crystallized From The Ionic Liquid 1-Ethyl-3-Methylimidazolium Tosylate: Bis-Aqua-(P-Toluenesulfonato-O)-Europium(Iii)-Bis-P-Toluenesulfonate Dihydrate, Si-Fu Tang, Anja V. Mudring

Anja V. Mudring

Bis-aqua-(p-toluenesulfonato-O)-europium(III)-bis-p-toluenesulfonate-dihydrate (1) was synthesized and structurally characterized. The crystal structure contains eight-coordinate europium(III) atoms. One oxygen atom from p-toluenesulfonate and seven aqua ligands form a slightly distorted square antiprism around Eu(III). A variety of O−H···O and intermolecular C−H···O hydrogen bonds link the asymmetric units into a two-dimensional layer, and these layers are further assembled into a three-dimensional supramolecular structure through intermolecular C−H···O hydrogen bonds and edge-to-face C−H···π interactions. The compound represents the structural missing link between the well-known lanthanide (Ln) tosylate (Tos) hydrates [(Ln(H2O)9](p-Tos)3(H2O) with noncoordinating tosylate and [Ln(H2O)6(p-Tos)2](p-Tos)2(H2O)3 where two tosylate groups coordinate to the lanthanide cation. It is …

Dysprosium-Based Ionic Liquid Crystals: Thermal, Structural, Photo- And Magnetophysical Properties, Anna Getsist, Benjamin Balke, Claudia Felser, Anja V. Mudring

Anja V. Mudring

[C12mim]3[DyBr6] (C12mim = 1-dodecyl-3-methylimidazolium) represents a new material with interesting luminescent behavior as well as mesomorphic and magnetic properties. The compound was found to show thermotropic liquid crystalline behavior and forms smectic mesophases which were investigated by hot-stage polarizing optical microscopy and differential scanning calorimetry. The emission color of [C12mim]3[DyBr6] can be tuned from white to orange-yellow by the choice of the excitation wavelength. Sample excitation with λex = 366 nm leads to the blue-whitish luminescence from the imidazolium cation itself. With λex = 254 nm the common Dy(III) emission is observed which mainly arises from the 4F9/2 → 6H13/2 …

Temperature-Driven Mixing-Demixing Behavior Of Binary Mixtures Of The Ionic Liquid Choline Bis(Trifluoromethylsulfonyl)Imide And Water, Peter Nockeman, Koen Binnemans, Ben Thijs, Tatjana N. Parc-Vogt, Klaus Merz, Anja V. Mudring, Preethy Chirukandath Menon, Ravindran Nair Rajesh, George Cordoyianis, Jan Thoen, Jan Leys, Christ Glorieux

Anja V. Mudring

Home Browse the Journal Articles ASAP Current Issue Submission & Review Open Access Subscribe About the Journal J. Phys. Chem. A B C Letters Pre-1997 System Maintenance: Thursday, October 22, 5pm to 9pm EDT Please be aware that pubs.acs.org will undergo maintenance from 5pm on Thursday, October 22 with all applications expected to resume normal operation by 9pm. This upgrade will impact applications that require a login or ACS ID, including the "Registration" and "MyAccount" functions. Log-in will be temporarily disabled for features including C&EN Delivery, ChemWorx and Galleys. Individual users will not be able to log-in to access their …

Facile, Environmentally Friendly Fabrication Of Porous Silver Monoliths Using The Ionic Liquid N-(2-Hydroxyethyl)Ammonium Formate, Kai Richter, Tobias Backer, Anja V. Mudring

Anja V. Mudring

The environmentally friendly ionic liquid N-(2-hydroxyethyl)ammonium formate works as a reaction medium, reducing and templating agent in the mild microwave synthesis (5 min, 80 °C) of a macroporous silver framework from AgNO3.

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Agegnehu Atena, Mikhail Khenner

Mikhail Khenner

In this paper the lubrication-type dynamical model is developed of a molten, pulsed laser-irradiated metallic film. The heat transfer problem that incorporates the absorbed heat from a single beam or interfering beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the peak laser beam intensity, the film optical thickness, the Biot and …