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2013

Chemical Engineering

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Articles 1 - 22 of 22

Full-Text Articles in Nanoscience and Nanotechnology

Adsorption And Diffusion Of Gases In Nano-Porous Materials, Nethika Sahani Suraweera Dec 2013

Adsorption And Diffusion Of Gases In Nano-Porous Materials, Nethika Sahani Suraweera

Doctoral Dissertations

In this work, a systematic computational study directed toward developing a molecular-level understanding of gas adsorption and diffusion characteristics in nano-porous materials is presented. Two different types of porous adsorbents were studied, one crystalline and the other amorphous. Physisorption and diffusion of hydrogen in ten iso-reticular metal-organic frameworks (IRMOFs) were investigated. A set of nine adsorbents taken from a class of novel, amorphous nano-porous materials composed of spherosilicate building blocks and isolated metal sites was also studied, with attention paid to the adsorptive and diffusive behavior of hydrogen, methane, carbon dioxide and their binary mixtures. Both classes of materials were ...


Structure And Energetics Of Nanoparticles And Ionomer Films In Fuel Cell Catalyst Layers, Qianping He Dec 2013

Structure And Energetics Of Nanoparticles And Ionomer Films In Fuel Cell Catalyst Layers, Qianping He

Doctoral Dissertations

Improving the durability and utilization efficiency of the platinum-on-carbon (Pt/C) catalyst is of vital importance to the commercialization of the polymer electrolyte membrane fuel cell (PEMFC). This body of work provides molecular level insights to aid the fulfillment of this goal. Chapter 1 describes the use of molecular dynamics (MD) simulation in an effort to understand the Pt/C degradation issue from the nano-adhesion point of view. The roles of catalyst nanoparticle size, shape, Pt/C surface oxidation and the extent of ionomer film hydration are investigated to study their effects on nano-particle adhesion. It is found that the ...


Dna Based Carbon Nanotube Porphyrin Nanohybrids Molecular Recognization And Regeneration, Molly M. Riccitelli, Hanyu Zhang, Jong Hyun Choi Oct 2013

Dna Based Carbon Nanotube Porphyrin Nanohybrids Molecular Recognization And Regeneration, Molly M. Riccitelli, Hanyu Zhang, Jong Hyun Choi

The Summer Undergraduate Research Fellowship (SURF) Symposium

In the search to improve solar cells, scientists are exploring new materials that will provide better current transfer. One material that has emerged as a strong contender is the single walled carbon nanotube (SWNT). Current DNA-SWNT based films combined with chromophores have poor operational lifetimes compared to commercial solar cells. Once exposed to light the chromophore begins to degrade, eventually rendering the solar cell unusable. To solve this problem, we used a method involving multiple steps. First we found which DNA sequences formed structures around the SWNT that could hold the most chromophores by using a spectrophotometer to test the ...


Optimization Of Gold Nanoparticles Synthesis By Stainless Steel For H2o2 And Glucose Detection, T. H. Han, Mohammad Mansoob Khan Dr, J. Lee, M. H. Cho Sep 2013

Optimization Of Gold Nanoparticles Synthesis By Stainless Steel For H2o2 And Glucose Detection, T. H. Han, Mohammad Mansoob Khan Dr, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

The synthesis of (+)AuNPs procedure using a stainless-steel mesh was optimized. The optimal synthetic parameters were found to be one piece of stainless-steel mesh (22.5 cm2 in surface area) in 100 mL of a 1 mM precursor, precursor solution pH 4, and reaction temperature of 30°C. Under the optimal conditions, the as-synthesized (+)AuNPs were highly positively charged (+24.2 mV). Therefore, the as-synthesized (+)AuNPs act as a peroxidase mimic and provide a simple, fast, highly sensitive and selective colorimetric method for H2O2 detection with a detection limit of 0.06 mM in the linear range from 0.06 ...


Bending, Wrinkling, And Folding Of Thin Polymer Film/Elastomer Interfaces, Yuri Ebata Sep 2013

Bending, Wrinkling, And Folding Of Thin Polymer Film/Elastomer Interfaces, Yuri Ebata

Open Access Dissertations

This work focuses on understanding the buckling deformation mechanisms of bending, wrinkling, and folding that occur on the surfaces and interfaces of polymer systems. We gained fundamental insight into the formation mechanism of these buckled structures for thin glassy films placed on an elastomeric substrate. By taking advantage of geometric confinement, we demonstrated new strategies in controlling wrinkling morphologies. We were able to achieve surfaces with controlled patterned structures which will have a broad impact in optical, adhesive, microelectronics, and microfluidics applications.

Wrinkles and strain localized features, such as delaminations and folds, are observed in many natural systems and are ...


Discriminatory Bio-Adhesion Over Nano-Patterned Polymer Brushes, Saugata Gon Sep 2013

Discriminatory Bio-Adhesion Over Nano-Patterned Polymer Brushes, Saugata Gon

Open Access Dissertations

Surfaces functionalized with bio-molecular targeting agents are conventionally used for highly-specific protein and cell adhesion. This thesis explores an alternative approach: Small non-biological adhesive elements are placed on a surface randomly, with the rest of the surface rendered repulsive towards biomolecules and cells. While the adhesive elements themselves, for instance in solution, typically exhibit no selectivity for various compounds within an analyte suspension, selective adhesion of targeted objects or molecules results from their placement on the repulsive surface. The mechanism of selectivity relies on recognition of length scales of the surface distribution of adhesive elements relative to species in the ...


Oxygen Vacancy Induced Band Gap Narrowing Of Zno Nanostructure By Electrochemically Active Biofilm, Mohammad Mansoob Khan Dr, A. A. Ansari, S. Kalathil, A. Nisar, J. Lee, M. H. Cho Jul 2013

Oxygen Vacancy Induced Band Gap Narrowing Of Zno Nanostructure By Electrochemically Active Biofilm, Mohammad Mansoob Khan Dr, A. A. Ansari, S. Kalathil, A. Nisar, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

Band gap narrowing is important and advantageous for potential visible light photocatalytic applications involving metal oxide nanostructures. This paper reports simple biogenic approach for the promotion of oxygen vacancies in pure zinc oxide (p-ZnO) nanostructures using an electrochemically active biofilm (EAB), which is different from traditional techniques for narrowing the band gap of nanomaterials. The novel protocol improved the visible photocatalytic activity of modified ZnO (m-ZnO) nanostructures through the promotion of oxygen vacancies, which resulted in band gap narrowing of the ZnO nanostructure (Eg = 3.05 eV) without dopants. X-ray diffraction, UV-visible diffuse reflectance spectroscopy, x-ray photoelectron spectroscopy, electron paramagnetic ...


Novel Ag@Tio2 Nanocomposite Synthesized By Electrochemically Active Biofilm For Nonenzymatic Hydrogen Peroxide Sensor, Mohammad Mansoob Khan Dr, S. A. Ansari, J. Lee, M. H. Cho Jul 2013

Novel Ag@Tio2 Nanocomposite Synthesized By Electrochemically Active Biofilm For Nonenzymatic Hydrogen Peroxide Sensor, Mohammad Mansoob Khan Dr, S. A. Ansari, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

A novel nonenzymatic sensor for H2O2 was developed based on an Ag@TiO2 nanocomposite synthesized using a simple and cost effective approach with an electrochemically active biofilm. The optical, structural, morphological and electrochemical properties of the as-prepared Ag@TiO2 nanocomposite were examined by UV-vis spectroscopy, x-ray diffraction, transmission electron microscopy and cyclic voltammetry (CV). The Ag@TiO2 nanocomposite was fabricated on a glassy carbon electrode (GCE) and their electrochemical performance was analyzed by CV, differential pulse voltammetry and electrochemical impedance spectroscopy. The Ag@TiO2 nanocomposite modified GCE (Ag@TiO2/GCE) displayed excellent performance towards H2O2 sensing at −0.73 V ...


Simultaneous Enhancement Of The Methylene Blue Degradation And Power Generation In Microbial Fuel Cell By Gold Nanoparticles, Mohammad Mansoob Khan Dr, T. H. Han, S. Kalathil, J. Lee, M. H. Cho May 2013

Simultaneous Enhancement Of The Methylene Blue Degradation And Power Generation In Microbial Fuel Cell By Gold Nanoparticles, Mohammad Mansoob Khan Dr, T. H. Han, S. Kalathil, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

This study examined the effect of positively charged gold nanoparticles ((+)AuNPs) on the enhancement of methylene blue (MB) degradation in microbial fuel cell (MFC) cathode. The maximum electricity production of 36.56 mW/m2 and complete MB degradation were achieved simultaneously. The MFC performance and MB degradation are strictly dependent on cathodic conditions, such as N2 bubbling, air bubbling and addition of H2O2. MB was reduced rapidly under anaerobic condition, whereas complete oxidative mineralization of MB occurred in the presence of dissolved oxygen (DO) or H2O2. (+)AuNPs enhanced the electricity generation in the MFCs involving MB degradation owing to its ...


Production Of Bioelectricity, Bio-Hydrogen, High Value Chemicals And 3 Bioinspired Nanomaterials By Electrochemically Active Biofilms, S. Kalathil, Mohammad Mansoob Khan Dr, M. H. Cho, J. Lee May 2013

Production Of Bioelectricity, Bio-Hydrogen, High Value Chemicals And 3 Bioinspired Nanomaterials By Electrochemically Active Biofilms, S. Kalathil, Mohammad Mansoob Khan Dr, M. H. Cho, J. Lee

Dr. Mohammad Mansoob Khan

Microorganisms naturally form biofilms on solid surfaces for their mutual benefits including protection from environmental stresses caused by contaminants, nutritional depletion or imbalances. The biofilms are normally dangerous to human health due to their inherited robustness. On the other hand, a recent study suggested that electrochemically active biofilms (EABs) generated by electrically active microorganisms have properties that can be used to catalyze or control the electrochemical reactions in a range of fields, such as bioenergy production, bioremediation, chemical/biological synthesis, bio-corrosion mitigation and biosensor development. EABs have attracted considerable attraction in bioelectrochemical systems (BESs), such as microbial fuel cells and ...


Enhanced Optical, Visible Light Catalytic And Electrochemical Properties Of Au@Tio2 Nanocomposites, Mohammad Mansoob Khan Dr, Sajid A. Ansari Mar 2013

Enhanced Optical, Visible Light Catalytic And Electrochemical Properties Of Au@Tio2 Nanocomposites, Mohammad Mansoob Khan Dr, Sajid A. Ansari

Dr. Mohammad Mansoob Khan

Au@TiO2 nanocomposites and pure TiO2 were successfully used to know the effect of Au on TiO2 and their comparative optical, visible light catalytic andelectrochemical activities were investigated. Optical parameters such as band gap energy (Eg = 2.4 eV), absorption coefficient (a), refractive index (n) and dielectric constants (s) have been determined using different methods. Visible light (590 nm) catalytic activity of Au@TiO2 nanocomposites was performed for reducing methyl orange (MO) under visible light irradiation. CV, EIS and DPV studies demonstrate that Au@TiO2 nanocomposites exhibit redox behavior, charged its surface by accumulating electrons, store and release the electrons.


Biodiesel Production From Waste Trying Oils Over Lime Catalysts, João F. Gomes Jan 2013

Biodiesel Production From Waste Trying Oils Over Lime Catalysts, João F. Gomes

João F Gomes

No abstract provided.


Phase And Morphology Selective Interface-Assisted Synthesis Of Highly Luminescent Ln3+-Doped Nagdf4 Nanorods, Anja V. Mudring, Qiang Ju Jan 2013

Phase And Morphology Selective Interface-Assisted Synthesis Of Highly Luminescent Ln3+-Doped Nagdf4 Nanorods, Anja V. Mudring, Qiang Ju

Anja V. Mudring

Making use of the multifunctional properties of ionic liquids by employing them as a fluoride resource and hydrophilic phase, we have grown small, monodisperse, highly luminescent Ln3+-doped NaGdF4 nanorods at the interface between octadecene and the reactive ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate. The obtained nanocrystals could further be endowed with functional groups and rendered water dispersible, which allows them to be used for biodetection.


Mild Yet Phase-Selective Preparation Of Tio2 Nanoparticles From Ionic Liquids – A Critical Study, Tarek Alammar, Heshmat Noei, Yuemin Wang, Anja V. Mudring Jan 2013

Mild Yet Phase-Selective Preparation Of Tio2 Nanoparticles From Ionic Liquids – A Critical Study, Tarek Alammar, Heshmat Noei, Yuemin Wang, Anja V. Mudring

Anja V. Mudring

The phase selective synthesis of nanocrystalline TiO2, titania, in ionic liquids (ILs) is explored. The influence not only of the IL but also of the Ti-precursor, pH, and temperature is investigated. Sonochemical synthesis, microwave synthesis and conventional heating are compared. In the case of Ti(OiPr)4 (OiPr ¼ isopropyl) as the Ti-source the ILs [C4mim][Tf2N] (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide), [C3mimOH][Tf2N] (1-(3-hydroxypropyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)amide), [C4Py]- [Tf2N] (butylpyridinium bis(trifluoromethanesulfonyl)amide), [N1888][Tf2N] (methyltrioctylammonium bis- (trifluoromethanesulfonyl)amide), and [P66614][Tf2N] (tetradecyltrihexyl phosphonium bis(trifluoromethanesulfonyl) amide) led at ambient temperature to TiO2 in the form of anatase ...


Design Of Novel Nano-Carriers For Multi-Enzyme Co-Localization, Feng Jia Jan 2013

Design Of Novel Nano-Carriers For Multi-Enzyme Co-Localization, Feng Jia

Graduate Theses and Dissertations

The widely existing MECs in Nature have inspired researchers to design synthetic analogs to promote the overall catalytic efficiency in vitro by co-localizing multiple enzymes to mimic the MECs' unique functionalities. A number of efforts have been devoted to designing synthetic MECs in the past couples of decades. This thesis work has focused on developing novel strategies based on enzyme immobilization to design nano-carriers for multi-enzyme co-localization to realize kinetics enhancement and strong control of spatial arrangement of the enzymes. Three distinct approaches have been designed using different attachment methods and platforms.

First, the multifunctional polystyrene nanoparticles were designed for ...


Raft Microemulsion Polymerization With Surface-Active Chain Transfer Agent, Ibrahim Adnan El-Hedok Jan 2013

Raft Microemulsion Polymerization With Surface-Active Chain Transfer Agent, Ibrahim Adnan El-Hedok

Graduate Theses and Dissertations

The work described in this dissertation focuses on enhancing the polymer nanoparticle synthesis using RAFT (reversible-addition fragmentation chain transfer) in microemulsion polymerization in order to achieve predetermined molecular weight with narrow molecular weight polydispersity.

The hypothesis is that the use of an amphiphilic chain transfer agent (surface-active CTA) will confine the CTA to the surface of the particle and thermodynamically favor partitioning of the CTA between micelles and particles throughout the polymerization. Thus, the CTA diffusion from micelles to polymer particles would be minimized and the breadth of the CTA per particle distribution would remain low.

We report the successful ...


Application And Characterization Of Self-Assembled Monolayers In Hybrid Electronic Systems, Michael Enoch Celesin Jan 2013

Application And Characterization Of Self-Assembled Monolayers In Hybrid Electronic Systems, Michael Enoch Celesin

Graduate Theses and Dissertations

In this study, we explore ultra-thin insulators of organic and inorganic composition and their potential role as high-speed rectifiers. Typical applications for these structures include IR sensing, chemical detection, high speed logic circuits, and MEMS enhancements. While there are many elements in the functional group required to create a rectifying antenna (rectenna), the primary thrust of this work is on the rectifier element itself.

To achieve these research goals, a very good understanding of quantum tunneling was required to model the underlying phenomenon of charge conduction. The development of a multi-variable optimization routine for tunneling prediction was required. MATLAB was ...


Approaches To Mitigate Metal Catalyst Deactivation In Solid Oxide Fuel Cell (Sofc) Fuel Electrodes, Lawrence Adijanto Jan 2013

Approaches To Mitigate Metal Catalyst Deactivation In Solid Oxide Fuel Cell (Sofc) Fuel Electrodes, Lawrence Adijanto

Publicly Accessible Penn Dissertations

While Ni/YSZ cermets have been used successfully in SOFCs, they also have several limitations, thus motivating the use of highly conductive ceramics to replace the Ni components in SOFC anodes. Ceramic electrodes are promising for use in SOFC anodes because they are expected to be less susceptible to sintering and coking, be redox stable, and be more tolerant of impurities like sulfur. In this thesis, for catalytic studies, the infiltration procedure has been used to form composites which have greatly simplified the search for the best ceramics for anode applications.

In the development of ceramic fuel electrodes for SOFC ...


Multi-Scale Characterization Of Nanostructured Sodium Aluminum Hydride, Shathabish Narasegowda Jan 2013

Multi-Scale Characterization Of Nanostructured Sodium Aluminum Hydride, Shathabish Narasegowda

Doctoral Dissertations

Complex metal hydrides are the most promising candidate materials for onboard hydrogen storage. The practicality of this class of materials is counter-poised on three critical attributes: reversible hydrogen storage capacity, high hydrogen uptake/release kinetics, and favorable hydrogen uptake/release thermodynamics. While a majority of modern metallic hydrides that are being considered are those that meet the criteria of high theoretical storage capacity, the challenges lie in addressing poor kinetics, thermodynamics, and reversibility. One emerging strategy to resolve these issues is via nanostructuring or nano-confinement of complex hydrides. By down-sizing and scaffolding them to retain their nano-dimensions, these materials are ...


The Critical Role Of Mechanism-Based Models For Understanding And Predicting Liposomal Drug Loading, Binding And Release Kinetics, Sweta Modi Jan 2013

The Critical Role Of Mechanism-Based Models For Understanding And Predicting Liposomal Drug Loading, Binding And Release Kinetics, Sweta Modi

Theses and Dissertations--Pharmacy

Liposomal delivery systems hold considerable promise for improvement of cancer therapy provided that critical formulation design criteria can be met. The main objective of the current project was to enable quality by design in the formulation of liposomal delivery systems by developing comprehensive, mechanism-based mathematical models of drug loading, binding and release kinetics that take into account not only the therapeutic requirement but the physicochemical properties of the drug, the bilayer membrane, and the intraliposomal microenvironment.

Membrane binding of the drug affects both drug loading and release from liposomes. The influence of bilayer composition and phase structure on the partitioning ...


Synthesis Of Gold Nanoparticles Using A Stainless Steel Mesh, Thi Hiep Han, Mohammad Mansoob Khan Dr, S Kalathil, J Lee, M H. Cho Dec 2012

Synthesis Of Gold Nanoparticles Using A Stainless Steel Mesh, Thi Hiep Han, Mohammad Mansoob Khan Dr, S Kalathil, J Lee, M H. Cho

Dr. Mohammad Mansoob Khan

A novel, rapid, one-pot, and facile approach was developed to synthesize positively charged gold nanoparticles [(+) AuNPs] by employing an aqueous solution of HAuCl4·3H2O as a precursor at 30 °C and a stainless-steel mesh as a reducing agent. The penetration of Cl− ions into the stainless-steel surface results in corrosion on the stainless-steel surface and excretion of electrons which are used for reduction of Au3+ → Au0. As a result, (+) AuNPs 5-20 nm in size, mostly monodispersed, were synthesized within 3 h. The as-synthesized AuNPs were charaterized by UV-vis, DLS, XRD, TEM, HR-TEM, EDX and SAED. The utilization of non-toxic chemicals ...


Biophotonic Logic Devices Based On Quantum Dots And Temporally-Staggered Forster Energy Transfer Relays, Jonathan C. Claussen, W. Russ Algar, Niko Hildebrandt, Kimihiro Susumu, Mario G. Ancona, Igor L. Medintz Dec 2012

Biophotonic Logic Devices Based On Quantum Dots And Temporally-Staggered Forster Energy Transfer Relays, Jonathan C. Claussen, W. Russ Algar, Niko Hildebrandt, Kimihiro Susumu, Mario G. Ancona, Igor L. Medintz

Jonathan C. Claussen

Integrating photonic inputs/outputs into unimolecular logic devices can provide significantly increased functional complexity and the ability to expand the repertoire of available operations. Here, we build upon a system previously utilized for biosensing to assemble and prototype several increasingly sophisticated biophotonic logic devices that function based upon multistep Förster resonance energy transfer (FRET) relays. The core system combines a central semiconductor quantum dot (QD) nanoplatform with a long-lifetime Tb complex FRET donor and a near-IR organic fluorophore acceptor; the latter acts as two unique inputs for the QD-based device. The Tb complex allows for a form of temporal ...