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Selected Works

2005

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Articles 1 - 30 of 36

Full-Text Articles in Chemical Engineering

Quantitative Elucidation Of A Distinct Spatial Gradient-Sensing Mechanism In Fibroblasts, Ian C. Schneider, Jason M. Haugh Dec 2005

Quantitative Elucidation Of A Distinct Spatial Gradient-Sensing Mechanism In Fibroblasts, Ian C. Schneider, Jason M. Haugh

Ian C. Schneider

Migration of eukaryotic cells toward a chemoattractant often relies on their ability to distinguish receptor-mediated signaling at different subcellular locations, a phenomenon known as spatial sensing. A prominent example that is seen during wound healing is fibroblast migration in platelet-derived growth factor (PDGF) gradients. As in the well-characterized chemotactic cells Dictyostelium discoideum and neutrophils, signaling to the cytoskeleton via the phosphoinositide 3-kinase pathway in fibroblasts is spatially polarized by a PDGF gradient; however, the sensitivity of this process and how it is regulated are unknown. Through a quantitative analysis of mathematical models and live cell total internal reflection fluorescence microscopy …

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54th Spsj Annual Meeting Yokohama, Japan, May 25-27, 2005, Jane C. Vogl, Hiroyuki Ohno Dec 2005

54th Spsj Annual Meeting Yokohama, Japan, May 25-27, 2005, Jane C. Vogl, Hiroyuki Ohno

Otto Vogl

No abstract provided.

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Macromolecules In Graz, Austria, December 3, 2004, Otto Vogl, Volker Ribitsch Nov 2005

Macromolecules In Graz, Austria, December 3, 2004, Otto Vogl, Volker Ribitsch

Otto Vogl

No abstract provided.

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Controllability Of Lumped Parameter Chemical Reactors, Rafael Maya-Yescas Sep 2005

Controllability Of Lumped Parameter Chemical Reactors, Rafael Maya-Yescas

Rafael Maya-Yescas

Although there have been several attempts to develop systematic evaluation of control schemes, the choosing and pairing of control variables in chemical reactors is not an easy task. Intrinsic nonlinearities of this kind of systems provoke dynamic responses that are difficult to predict. In this paper, a simple proposition for the evaluation of pairs of control and manipulated variables is developed for nonlinear control affine systems. It compliments the RGA analysis for nonlinear systems because is based on the relationship between zero dynamics and control stability. The resulting strategy is simple, easy to understand and easy to apply for the …

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Co-Generation Of C2 Hydrocarbons And Synthesis Gases From Methane And Carbon Dioxide: A Thermodynamic Analysis, Istadi Istadi, Nor Aishah Saidina Amin Aug 2005

Co-Generation Of C2 Hydrocarbons And Synthesis Gases From Methane And Carbon Dioxide: A Thermodynamic Analysis, Istadi Istadi, Nor Aishah Saidina Amin

Istadi

This paper deals with thermodynamic chemical equilibrium analysis using the method of direct minimization of Gibbs free energy for all possible CH4 and CO2 reactions. The effects of CO2/CH4 feed ratio, reaction temperature, and system pressure on equilibrium composition, conversion, selectivity and yield were studied. In addition, carbon and no carbon formation regions were also considered at various reaction temperatures and CO2/CH4 feed ratios in the reaction system at equilibrium. It was found that the reaction temperature above 1100 K and CO2/CH4 ratio=1 were favourable for synthesis gas production with H2/CO ratio unity, while carbon dioxide oxidative coupling of methane …

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A Hybrid Numerical Approach For Multi-Responses Optimization Of Process Parameters And Catalyst Compositions In Co2 Ocm Process Over Cao-Mno/Ceo2 Catalyst, Istadi Istadi Aug 2005

A Hybrid Numerical Approach For Multi-Responses Optimization Of Process Parameters And Catalyst Compositions In Co2 Ocm Process Over Cao-Mno/Ceo2 Catalyst, Istadi Istadi

Istadi

A new hybrid numerical approach, using Weighted Sum of Squared Objective Functions (WSSOF) algorithm, was developed for multiresponses optimization of carbon dioxide oxidative coupling of methane (CO2 OCM). The optimization was aimed to obtain optimal process parameters and catalyst compositions with high catalytic performances. The hybrid numerical approach combined the single-response modeling and optimization using Response Surface Methodology (RSM) and WSSOF technique of multi-responses optimization. The hybrid algorithm resulted in Pareto-optimal solutions and an additional criterion was proposed over the solutions to obtain a final unique optimal solution. The simultaneous maximum responses of C2 selectivity and yield were obtained at …

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Synthesis And Characterization Of Highly Amine Functionalized Mesoporous Organosilicas By An “All-In-One” Approach, Rebecca Voss, Arne Thomas, Markus Antonietti, Geoffrey A. Ozin Aug 2005

Synthesis And Characterization Of Highly Amine Functionalized Mesoporous Organosilicas By An “All-In-One” Approach, Rebecca Voss, Arne Thomas, Markus Antonietti, Geoffrey A. Ozin

Rebecca Cademartiri

Mesoporous organosilicas (MOs) represent a promising class of organic–inorganic nanocomposites for a broad range of applications like catalysis, sensing, separation, or microelectronics. Their distinct feature is the presence of organic groups incorporated into the channel walls of a mesoporous structure. Here, we present a convenient “all-in-one” approach using silsesquioxane surfactant precursors for the functionalization of the channel walls with primary amine groups. The monomer is made by a hydroboration/aminolysis sequence on the base of a commercial monomer, with the template bound to the functionalization site by hydroboration and released after silica condensation and aminolysis. This combination ensures both the placement …

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Spatial Analysis Of 3′ Phosphoinositide Signaling In Living Fibroblasts, Iii: Influence Of Cell Morphology And Morphological Polarity, Ian C. Schneider, Elizabeth M. Parrish, Jason M. Haugh Aug 2005

Spatial Analysis Of 3′ Phosphoinositide Signaling In Living Fibroblasts, Iii: Influence Of Cell Morphology And Morphological Polarity, Ian C. Schneider, Elizabeth M. Parrish, Jason M. Haugh

Ian C. Schneider

Activation of phosphoinositide (PI) 3-kinase is a required signaling pathway in fibroblast migration directed by platelet-derived growth factor. The pattern of 3′ PI lipids in the plasma membrane, integrating local Pl 3-kinase activity as well as 3′ PI diffusion and turnover, influences the spatiotemporal regulation of the cytoskeleton. In fibroblasts stimulated uniformly with platelet-derived growth factor, visualized using total internal reflection fluorescence microscopy, we consistently observed localized regions with significantly higher or lower 3′ PI levels than adjacent regions (hot and cold spots, respectively). A typical cell contained multiple hot spots, coinciding with apparent leading edge structures, and at most …

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Elastic Waves Push Organic Fluids From Reservoir Rock, Igor A. Beresnev, R. Dennis Vigil, Wenqing Li, Wayne D. Pennington, Roger M. Turpening, Pavel P. Iassonov, Robert P. Ewing Jul 2005

Elastic Waves Push Organic Fluids From Reservoir Rock, Igor A. Beresnev, R. Dennis Vigil, Wenqing Li, Wayne D. Pennington, Roger M. Turpening, Pavel P. Iassonov, Robert P. Ewing

R. Dennis Vigil

Elastic waves have been observed to increase productivity of oil wells, although the reason for the vibratory mobilization of the residual organic fluids has remained unclear. Residual oil is entrapped as ganglia in pore constrictions because of resisting capillary forces. An external pressure gradient exceeding an ‘‘unplugging’’ threshold is needed to carry the ganglia through. The vibrations help overcome this resistance by adding an oscillatory inertial forcing to the external gradient; when the vibratory forcing acts along the gradient and the threshold is exceeded, instant ‘‘unplugging’’ occurs. The mobilization effect is proportional to the amplitude and inversely proportional to the …

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Temperature Dependence Of Order, Disorder, And Defects In Laterally Confined Diblock Copolymer Cylinder Monolayers, Matthew R. Hammond, Eric W. Cochran, Glenn H. Fredrickson, Edward J. Kramer Jul 2005

Temperature Dependence Of Order, Disorder, And Defects In Laterally Confined Diblock Copolymer Cylinder Monolayers, Matthew R. Hammond, Eric W. Cochran, Glenn H. Fredrickson, Edward J. Kramer

Eric W. Cochran

Monolayer arrays of polystyrene-poly(2-vinylpyridine) diblock copolymer cylinders with excellent orientational order and a very low density of dislocations are prepared by cooling slowly from above the bulk order - disorder temperature (ODT) ∼212°C within silicon oxide channels one cylinder spacing a in depth and 2 μm in width. The translational order of this array, however, is short range with a correlation length of ∼12a. If such an array is heated to a temperature above the glass transition temperature of the block copolymer (100°C) but well below the ODT, a finite density of thermally generated dislocations is observed, which leads to …

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Inverse Density Functional Theory As An Interpretive Tool For Measuring Colloid-Surface Interactions In Dense Systems, David M. Ford, Mingqing Lu, Michael A. Bevan Apr 2005

Inverse Density Functional Theory As An Interpretive Tool For Measuring Colloid-Surface Interactions In Dense Systems, David M. Ford, Mingqing Lu, Michael A. Bevan

David M Ford

Recent advances in optical microscopy, such as total internal reflection and confocal scanning laser techniques, now permit the direct three-dimensional tracking of large numbers of colloidal particles both near and far from interfaces. A novel application of this technology, currently being developed by one of the authors under the name of diffusing colloidal probe microscopy (DCPM), is to use colloidal particles as probes of the energetic characteristics of a surface. A major theoretical challenge in implementing DCPM is to obtain the potential energy of a single particle in the external field created by the surface, from the measured particle trajectories …

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Ethane Oxidation And Pyrolysis From 5 Bar To 1000 Bar: Experiments And Simulation, Abdul Aziz Abdul Raman Mar 2005

Ethane Oxidation And Pyrolysis From 5 Bar To 1000 Bar: Experiments And Simulation, Abdul Aziz Abdul Raman

Abdul Aziz Abdul Raman

An extensive experimental study of ethane oxidation and pyrolysis has been conducted in the high pressure shock tube at UIC covering reflected shock pressures from 5-1000 bar, reaction temperatures up to 1550 K and stoichiometric (Φ = 1 ), fuel rich (Φ = 5), and pyrolytic mixtures. The experimental data has been used to develop a single model that can simulate the whole dataset very well and is the first ethane model capable of simulating experimental results over such an extensive range of pressure, temperature, and stoichiometry. © 2005 Wiley Periodicals, Inc.

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Jump Condition At The Boundary Between A Porous Catalyst And A Homogeneous Fluid, Francisco J. Valdes-Parada, J. Alberto Ochoa-Tapia Jan 2005

Jump Condition At The Boundary Between A Porous Catalyst And A Homogeneous Fluid, Francisco J. Valdes-Parada, J. Alberto Ochoa-Tapia

Francisco J. Valdes-Parada

The method of volume averaging (Whitaker, 1999) is used to derive the jump conditions between a porous catalyst and a homogeneous fluid. To simplify the analysis a first order kinetics is used and the convective transport is neglected. The statement for the derivation is in terms of the spatially smoothed equations obtained by Wood et al. (2000). We have followed a similar procedure to the one used by those authors to derive, besides a jump boundary condition that couples the two media transport, a closure problem to predict the effective reaction rate coefficient at the interregion dividing surface as a …

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Aplicación Del Método De Optimización De Recocido Simulado En La Regresión De Isotermas De Adsorción, Adrian Bonilla-Petriciolet, María Guadalupe Lira-Padilla, Carlos A. Soto-Becerra Jan 2005

Aplicación Del Método De Optimización De Recocido Simulado En La Regresión De Isotermas De Adsorción, Adrian Bonilla-Petriciolet, María Guadalupe Lira-Padilla, Carlos A. Soto-Becerra

Adrian Bonilla-Petriciolet

The nonlinear parameter estimation of thermodynamic models, including the adsorption isotherms, is a multivariable and nonlinear problem that can present several local optimums. The conventional optimization methods used in the parameter estimation of adsorption isotherms are efficient but they are not reliable to solve such problem. In this paper, we describe the application of the stochastic global optimization method simulated annealing in the nonlinear regression of adsorption isotherms. This method has been applied with Toth and Sips models. Our results indicate that this method is a reliable optimization strategy for parameter estimation in adsorption isotherms.

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Efficiency Of Heat Recovery Versus Maximum Catalyst Temperature In A Reverse-Flow Combustion Of Methane, Krzysztof Gosiewski Jan 2005

Efficiency Of Heat Recovery Versus Maximum Catalyst Temperature In A Reverse-Flow Combustion Of Methane, Krzysztof Gosiewski

Krzysztof Gosiewski

Results of simulations are presented concerning a reverse-flow reactor for the catalytic combustion of methane that occurs in coal-mine ventilation air. The simulations were performed for two types of catalyst: 12% MnO2/-Al2O3 and 0.5% Pd/-Al2O3. A special attention is given to maximum temperature of the catalyst bed in order to minimize occurrence of homogeneous combustion. The simulations revealed that there is a visible contradiction between efficiency of heat recovery aimed to high-pressure steam production and efforts to constraint maximum temperature in the bed.

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Avoid Sulfuric Acid Corrosion In Metallic Stacks, João F. Gomes Jan 2005

Avoid Sulfuric Acid Corrosion In Metallic Stacks, João F. Gomes

João F Gomes

Acidic gaseous effluents frequently cause corrosion on metallic stacks. This paper presents a method for prevision of probability of corrosion occurrence caused by gaseous effluents containing sulphur oxides which is based on the sulphur trioxide and moisture content measured in stack

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Emissions Of Dioxin And Dibenzofuran From Electric Arc Furnaces, João F. Gomes Jan 2005

Emissions Of Dioxin And Dibenzofuran From Electric Arc Furnaces, João F. Gomes

João F Gomes

This paper describes work done in order to clarify the formation mechanism of highly toxic micropollutants, such as dioxins and dibenzofurans, from electric arc furnaces used in the production of carbon steel from scrap. The study is allowing to derive relationships between the levels of airborne micropollutants and the operational parameters of the production process so that an abatement of pollution could be achieved. By using the European standard method CEN 1948 for dioxin like compounds sampling and measurement, it was possible to determine the characteristic fingerprint of micropollutants emitted by this particular stationary source.

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Darcy's Law For Immiscible Two-Phase Flow: A Theoretical Development, Francisco J. Valdes-Parada, Gilberto Espinoza-Paredes Jan 2005

Darcy's Law For Immiscible Two-Phase Flow: A Theoretical Development, Francisco J. Valdes-Parada, Gilberto Espinoza-Paredes

Francisco J. Valdes-Parada

The aim of this paper is to show how the method of volume averaging can be used to obtain a closed set of averaged equations for bubbling flow. The Navier–Stokes equations are considered as the starting point for the volume-averaging method. The closure was formulated as an associated problem with the deviations around averaged values of the local variables. When the traditional length-scale restrictions are imposed, the volume-averaged momentum equation can be given by &#;vk k – &#;vm m = Kk⋅ (–∇ &#;pk k + ρkgk), which is equivalent to Darcy’s law. The tensor Kk is determined by closure problems …

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Experimental And Dft Studies Of The Conversion Of Ethanol And Acetic Acid On Ptsn-Based Catalysts, George W. Huber, R. Acal, J. W. Shabaker, M. A. Sanchez-Castillo, J. A. Dumesic Jan 2005

Experimental And Dft Studies Of The Conversion Of Ethanol And Acetic Acid On Ptsn-Based Catalysts, George W. Huber, R. Acal, J. W. Shabaker, M. A. Sanchez-Castillo, J. A. Dumesic

George W. Huber

Reaction kinetics studies were conducted for the conversions of ethanol and acetic acid over silica-supported Pt and Pt/Sn catalysts at temperatures from 500 to 600 K. Addition of Sn to Pt catalysts inhibits the decomposition of ethanol to CO, CH4, and C2H6, such that PtSn-based catalysts are active for dehydrogenation of ethanol to acetaldehyde. Furthermore, PtSn-based catalysts are selective for the conversion of acetic acid to ethanol, acetaldehyde, and ethyl acetate, whereas Pt catalysts lead mainly to decomposition products such as CH4 and CO. These results are interpreted using density functional theory (DFT) calculations for various adsorbed species and transition …

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Asymptotic Analysis Of Liquid Films Dip-Coated Onto Chemically Micropatterned Surfaces, Jm Davis Jan 2005

Asymptotic Analysis Of Liquid Films Dip-Coated Onto Chemically Micropatterned Surfaces, Jm Davis

Jeffrey M. Davis

The dip coating of chemically heterogeneous surfaces is a useful technique for attaining selective material deposition. For the case of vertical, wetting stripes surrounded by nonwetting regions, experiments have demonstrated that the thickness of the entrained film on the stripes is significantly different than on homogeneous surfaces because of the lateral confinement of the liquid. In the present work, the asymptotic matching of equations based on lubrication theory is used to determine the film thickness, and necessary restrictions on the capillary and Bond numbers are provided. The predictions are in excellent agreement with the existing experimental data, and the classical …

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Surface Smoothening Mechanism Of Amorphous Silicon Thin Films, Dimitrios Maroudas, E. S. Aydil, T Bakos, M. S. Valipa Jan 2005

Surface Smoothening Mechanism Of Amorphous Silicon Thin Films, Dimitrios Maroudas, E. S. Aydil, T Bakos, M. S. Valipa

Dimitrios Maroudas

An important concern in the deposition of thin hydrogenated amorphous silicon (a-Si∶H) films is to obtain smooth surfaces. Herein, we combine molecular-dynamics simulations with first-principles density functional theory calculations to elucidate the smoothening mechanism of plasma deposited a-Si∶H thin films. We show that the deposition precursor may diffuse rapidly on the a-Si∶H film surface via overcoordinated surface Si atoms and incorporate into the film preferentially in surface valleys, with activation barriers for incorporation dependent on the local surface morphology. Experimental data on smoothening and precursor diffusion are accounted for.

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Generalized Linear Stability Of Noninertial Coating Flows Over Topographical Features, Jm Davis, Sm Troian Jan 2005

Generalized Linear Stability Of Noninertial Coating Flows Over Topographical Features, Jm Davis, Sm Troian

Jeffrey M. Davis

The transient evolution of perturbations to steady lubrication flow over a topographically patterned surface is investigated via a nonmodal linear stability analysis of the non-normal disturbance operator. In contrast to the capillary ridges that form near moving contact lines, the stationary capillary ridges near trenches or elevations have only stable eigenvalues. Minimal transient amplification of perturbations occurs, regardless of the magnitude or steepness of the topographical features. The absence of transient amplification and the stability of the ridge are explained on physical grounds. By comparison to unstable ridge formation on smooth, flat, and homogeneous surfaces, the lack of closed, recirculating …

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Inorganic Supramolecular Host Architectures:  [(M@18c6)2][Tli4]·2h2o, M = 0.5 Tl, (Nh4,Nh3), (H3o,H2o), Franziska Rieger, Anja V. Mudring Jan 2005

Inorganic Supramolecular Host Architectures:  [(M@18c6)2][Tli4]·2h2o, M = 0.5 Tl, (Nh4,Nh3), (H3o,H2o), Franziska Rieger, Anja V. Mudring

Anja V. Mudring

The compounds [(M@18c6)2][TlI4]·2H2O, M = Tl, (NH4,NH3), (H3O,H2O) (cubic, Fd3̄; a = 1481.00 pm, for M = 0.5 Tl, a = 1304.65 pm for M = (NH4,NH3), a = 1313.67 pm for M = (H3O,H2O)) can be obtained from solution in the presence of traces of transition metal halides (like copper and mercury halides). Apparently the transition metal cations work as a template in the form of tetrahedral [MX4] units during the synthesis of the supramolecular host architecture. That the compounds are versatile host lattices for tetrahedrally coordinated transition metal units becomes obvious by the large group of known host−guest …

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The Quadrupole Moment Of The 3/2+ Nuclear Ground State Of Au197 From Electric Field Gradient Relativistic Coupled Cluster And Density-Functional Theory Of Small Molecules And The Solid State, Peter Schwerdtfeger, Radovan Bast, Michael C.L. Gerry, Christoph R. Jacobs, Martin Jansen, Vladimir Kello, Anja V. Mudring, Andrzej J. Sadlej, Trond Saue, Tilo Sohnel, Friedrich E. Wagner Jan 2005

The Quadrupole Moment Of The 3/2+ Nuclear Ground State Of Au197 From Electric Field Gradient Relativistic Coupled Cluster And Density-Functional Theory Of Small Molecules And The Solid State, Peter Schwerdtfeger, Radovan Bast, Michael C.L. Gerry, Christoph R. Jacobs, Martin Jansen, Vladimir Kello, Anja V. Mudring, Andrzej J. Sadlej, Trond Saue, Tilo Sohnel, Friedrich E. Wagner

Anja V. Mudring

An attempt is made to improve the currently accepted muonic value for the Au197 nuclear quadrupole moment [+0.547(16)×10−28m2] for the 3/2+ nuclear ground state obtained by Powers et al. [Nucl. Phys.A230, 413 (1974)]. From both measured Mössbauer electric quadrupole splittings and solid-state density-functional calculations for a large number of gold compounds a nuclear quadrupole moment of +0.60×10−28m2 is obtained. Recent Fourier transform microwave measurements for gas-phase AuF, AuCl, AuBr, and AuI give accurate bond distances and nuclear quadrupole coupling constants for the Au197isotope. However, four-component relativistic density-functional calculations for these molecules yield unreliable results for the Au197 nuclear quadrupole moment. …

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Rare-Earth Iodides In Ionic Liquids:  The Crystal Structure Of [Set3]3[Lni6] (Ln = Nd, Sm), Anja V. Mudring, Arash Babai Jan 2005

Rare-Earth Iodides In Ionic Liquids:  The Crystal Structure Of [Set3]3[Lni6] (Ln = Nd, Sm), Anja V. Mudring, Arash Babai

Anja V. Mudring

Crystals of [SEt3]3[LnI6] (Ln = Nd, Sm) were obtained by the reaction of LnI2 with the ionic liquid [SEt3][Tf2N] [Tf2N = bis(trifluoromethanesulfonyl)imide]. The compounds are characterized by octahedral [LnI6]3- units that are surrounded by a distorted cube of triethylsulfonium cations.

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New Properties From Pla–Peo–Pla Hydrogels, Gregory N. Tew, Naomi Sanabria-Delong, Sarvesh K. Agrawal, Surita R. Bhatia Jan 2005

New Properties From Pla–Peo–Pla Hydrogels, Gregory N. Tew, Naomi Sanabria-Delong, Sarvesh K. Agrawal, Surita R. Bhatia

Gregory N. Tew

Polymeric materials are important in many medical applications. Regenerative medicine offers the potential to repair or replace damaged tissue and polymers are an essential component of many tissue engineering approaches. Hydrogels have many advantageous properties but, generally, lack robust mechanical properties. At the same time, mounting evidence points to the importance of the matrix modulus when constructing devices. In this context, triblock copolymers made from poly(L-lactide)–poly(ethylene glycol)–poly(L-lactide) have been prepared and formulated into hydrogels. Investigations into their mechanical properties found the elastic modulus to be greater than 10 kPa which is at least one order of magnitude stiffer than previously …

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Synthesis Of Urea Oligomers And Their Antibacterial Activity, Haizhong Tang, Robert J. Doerksen, Gregory N. Tew Jan 2005

Synthesis Of Urea Oligomers And Their Antibacterial Activity, Haizhong Tang, Robert J. Doerksen, Gregory N. Tew

Gregory N. Tew

Facially amphiphilic urea oligomers were successfully prepared in a one-pot reaction by carbonyl diimidazole (CDI) coupling and showed greater antibacterial activity against both Gram-negative Escherichia coli and Gram-positive Bacillus subtilis than MSI-78.

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Anhydrous Praseodymium Salts In The Ionic Liquid [Bmpyr][Tf2n]:  Structural And Optical Properties Of [Bmpyr]4[Pri6][Tf2n] And [Bmyr]2[Pr(Tf2n)5], Arash Babai, Anja V. Mudring Jan 2005

Anhydrous Praseodymium Salts In The Ionic Liquid [Bmpyr][Tf2n]:  Structural And Optical Properties Of [Bmpyr]4[Pri6][Tf2n] And [Bmyr]2[Pr(Tf2n)5], Arash Babai, Anja V. Mudring

Anja V. Mudring

Purposely designed ionic liquids can be excellent solvents for spectroscopic studies of rare earth compounds. Absorption and emission spectra of anhydrous PrI3 and Pr(Tf2N)3 in the ionic liquid 1,1-n-butyl-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide, [bmpyr][Tf2N], at room temperature are presented together with the emission spectra of solid [bmpyr]2[Pr(Tf2N)5] and [bmpyr]4[PrI6][Tf2N]. After excitation into the 3P1 level, remarkable luminescence not only from the 1D2 level but also from the 3P0 and even from the 3P1 level is observed. Amazingly in the case of the solid compounds and even more astonishing for a solution of Pr(Tf2N)3 in [bmpyr][Tf2N] the strongest luminescence transitions start from the 3P0 …

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Lone Pair Effect In Thallium(I) Macrocyclic Compounds, Anja V. Mudring, Franziska Rieger Jan 2005

Lone Pair Effect In Thallium(I) Macrocyclic Compounds, Anja V. Mudring, Franziska Rieger

Anja V. Mudring

The role of the inert (lone) pair of electrons in thallium(I) salts is studied by comparison of the compounds [Tl@18-crown-6]+X- (X = TlI4, ClO4) and [K@18-crown-6]+ClO4-. In contrast to common introductory chemistry textbook opinions, the paradigm that s−p hybridization is a prerequisite for an inert electron pair to become stereochemically active in compounds of the heavier main group elements has to be revised. Instead, an inert pair of electrons is expected to become stereochemically involved whenever it is forced to participate in antibonding orbital interactions with its surroundings, and there is the possibility for a structural distortion that minimizes these …

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The Grain Size And Microstructure Of Jet-Electroplated Damascene Copper Films, Stacy H. Gleixner, Andrew Tzanavaras, Gregory Young Jan 2005

The Grain Size And Microstructure Of Jet-Electroplated Damascene Copper Films, Stacy H. Gleixner, Andrew Tzanavaras, Gregory Young

Stacy H. Gleixner

Electroplated damascene copper is rapidly replacing aluminum-copper alloys for on-chip interconnect metallization in advanced ultralarge scale integrated (ULSI) semiconductor devices. In addition to a high degree of (111) crystallographic texture, large defect-free grains are desired to enhance the performance and reliability of copper interconnects in such devices. The brightening additive level and dc current density of electroplating baths are two parameters that affect the process gap-filling capability and the degree of additive incorporation in these copper films. Additive incorporation can inhibit grain growth during the room-temperature recrystallization process and therefore affect the final grain size in electroplated copper films. This …

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