Physical Sciences and Mathematics Commons^™

The Role Of Catalytic Residue PKA On The Hydrolysis/Transglycosylation Partition In Family 3 Β-Glucosidases, Inacrist Geronimo, Christina M. Payne, Mats Sandgren

Chemical and Materials Engineering Faculty Publications

β-Glucosidases (βgls) primarily catalyze the hydrolysis of the terminal glycosidic bond at the non-reducing end of β-glucosides, although glycosidic bond synthesis (called transglycosylation) can also occur in the presence of another acceptor. In the final reaction step, the glucose product or another substrate competes with water for transfer to the glycosyl-enzyme intermediate. The factors governing the balance between the two pathways are not fully known; however, the involvement of ionizable residues in binding and catalysis suggests that their pK_a may play a role. Through constant pH molecular dynamics simulations of a glycoside hydrolase Family 3 (GH3) βgl, we …

Layer-By-Layer Assembled Membranes With Immobilized Porins, Sebastián Hernández, Cassandra Porter, Xinyi Zhang, Yinan Wei, Dibakar Bhattacharyya

Chemical and Materials Engineering Faculty Publications

New and advanced opportunities are arising for the synthesis and functionalization of membranes with selective separation, reactivity, and stimuli-responsive behavior. One such advancement is the integration of bio-based channels in membrane technologies. By a layer-by-layer (LbL) assembly of polyelectrolytes, outer membrane protein F trimers (OmpF) or “porins” from Escherichia coli with central pores ∼2 nm in diameter at their opening and ∼0.7 × 1.1 nm at their constricted region are immobilized within the pores of poly(vinylidene fluoride) microfiltration membranes, in contrast to traditional ruptured lipid bilayer or vesicle processes. These OmpF-membranes demonstrate selective rejection of non-charged organics over ionic solutes, …

Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara

Physics and Astronomy Faculty Publications

The present study examines the interaction of hydrogen and nitrogen plasmas with gallium in an effort to gain insights into the mechanisms behind the synergetic effect of plasma and a catalytic metal. Absorption/desorption experiments were performed, accompanied by theoretical-computational calculations. Experiments were carried out in a plasma-enhanced, Ga-packed, batch reactor and entailed monitoring the change in pressure at different temperatures. The results indicated a rapid adsorption/dissolution of the gas into the molten metal when gallium was exposed to plasma, even at a low temperature of 100 °C. The experimental observations, when hydrogen was used, indicate that gallium acts as a …

Synthesis And Characterization Of Thermoresponsive Hydrogels Based On N-Isopropylacrylamide Crosslinked With 4,4′-Dihydroxybiphenyl Diacrylate, Shuo Tang, Martha Floy, Rohit Bhandari, Manjula Sunkara, Andrew J. Morris, Thomas D. Dziubla, J. Zach Hilt

Chemical and Materials Engineering Faculty Publications

A novel crosslinker [4,4′-dihydroxybiphenyl diacrylate (44BDA)] was developed, and a series of temperature-responsive hydrogels were synthesized through free radical polymerization of N-isopropylacrylamide (NIPAAm) with 44BDA. The temperature-responsive behavior of the resulting gels was characterized by swelling studies, and the lower critical solution temperature (LCST) of the hydrogels was characterized through differential scanning calorimetry. Increased content of 44BDA led to a decreased swelling ratio and shifted the LCST to lower temperatures. These novel hydrogels also displayed resiliency through multiple swelling–deswelling cycles, and their temperature responsiveness was reversible. The successful synthesis of NIPAAm-based hydrogels crosslinked with 44BDA has led to a …

Resilient And Real-Time Control For The Optimum Management Of Hybrid Energy Storage Systems With Distributed Dynamic Demands, Christopher R. Lashway

FIU Electronic Theses and Dissertations

A continuous increase in demands from the utility grid and traction applications have steered public attention toward the integration of energy storage (ES) and hybrid ES (HESS) solutions. Modern technologies are no longer limited to batteries, but can include supercapacitors (SC) and flywheel electromechanical ES well. However, insufficient control and algorithms to monitor these devices can result in a wide range of operational issues. A modern day control platform must have a deep understanding of the source. In this dissertation, specialized modular Energy Storage Management Controllers (ESMC) were developed to interface with a variety of ES devices. The EMSC provides …

Responsive Nanogel Probe For Ratiometric Fluorescent Sensing Of Ph And Strain In Hydrogels, Mingning Zhu, Dongdong Lu, Shanglin Wu, Qing Lian, Wenkai Wang, Amir H. Milani, Zhengxing Cui, Nam T. Nguyen, Mu Chen, L. Andrew Lyon, Daman J. Adlam, Anthony J. Freemont, Judith A. Hoyland, Brian R. Saunders

Engineering Faculty Articles and Research

In this study a new pH-responsive nanogel probe containing a complementary nonradiative resonance energy transfer (NRET) fluorophore pair is investigated and its ability to act as a versatile probe of network-related changes in three hydrogels demonstrated. Fluorescent sensing using NRET is a powerful method for studying relationships between Angstrom length-scale structure and macroscopic properties of soft matter. Unfortunately, inclusion of NRET fluorophores into such materials requires material-specific chemistry. Here, low concentrations of preformed nanogel probes were included into hydrogel hosts. Ratiometric photoluminescence (PL) data for the gels labeled with the nanogel probes enabled pH-triggered swelling and deswelling to be studied …

Thermodynamics Of Concentrated Solid Solution Alloys, Michael C. Gao, Chuan Zhang, Pan Gao, Fan Zhang, Lizhi Ouyang, Michael Widom, Jeffrey A. Hawk

Mathematical Sciences Faculty Research

This paper reviews the three main approaches for predicting the formation of concentrated solid solution alloys (CSSA) and for modeling their thermodynamic properties, in particular, utilizing the methodologies of empirical thermo-physical parameters, CALPHAD method, and first-principles calculations combined with hybrid Monte Carlo/Molecular Dynamics (MC/MD) simulations. In order to speed up CSSA development, a variety of empirical parameters based on Hume-Rothery rules have been developed. Herein, these parameters have been systematically and critically evaluated for their efficiency in predicting solid solution formation. The phase stability of representative CSSA systems is then illustrated from the perspectives of phase diagrams and nucleation driving …

Hybrid Polymer Electrolyte For Lithium-Oxygen Battery Application, Amir Chamaani

FIU Electronic Theses and Dissertations

The transition from fossil fuels to renewable resources has created more demand for energy storage devices. Lithium-oxygen (Li-O₂) batteries have attracted much attention due to their high theoretical energy densities. They, however, are still in their infancy and several fundamental challenges remain to be addressed. Advanced analytical techniques have revealed that all components of a Li-O₂ battery undergo undesirable degradation during discharge/charge cycling, contributing to reduced cyclability. Despite many attempts to minimize the anode and cathode degradation, the electrolyte remains as the leading cause for rapid capacity fading and poor cyclability in Li-O₂ batteries. In this …

A Hierarchical Approach For Creating Electrically Conductive Network Structure In Polyurethane Nanocomposites Using A Hybrid Of Graphene Nanoplatelets, Carbon Black And Multi-Walled Carbon Nanotubes, Pashupati Pokharel, Dequan Xiao, Folarin Erogbogbo, Ozgur Keles, Dai Soo Lee

Chemistry and Chemical Engineering Faculty Publications

Hierarchical organization of carbon nanomaterials is the best strategy to combine desirable factors and synergistically impart mechanical and electrical properties to polymers. Here, we investigate the relaxation behavior of carbon nanofillers filled polyurethane (PU) with special reference to particle size and aspect ratio, filler morphology, filler loading to understand the conductive network formation of fillers in the PU matrix. Typically, an addition of 2 wt% hybrid fillers of graphene nanoplatelets (GNPs), conductive carbon black (CB) and multiwalled carbon nanotubes (MWCNTs) in PU at 1:1:2 mass ratio (GCM112-PU2) showed lowest surface resistivity ~10^6.8 ohm/sq along with highest improved mechanical properties. …

Catalytic Oxidation And Depolymerization Of Lignin In Aqueous Ionic Liquid, Lalitendu Das, Siquan Xu, Jian Shi

Biosystems and Agricultural Engineering Faculty Publications

Lignin is an integral part of the plant cell wall, which provides rigidity to plants, also contributes to the recalcitrance of the lignocellulosic biomass to biochemical and biological deconstruction. Lignin is a promising renewable feedstock for aromatic chemicals; however, an efficient and economic lignin depolymerization method needs to be developed to enable the conversion. In this study, we investigated the depolymerization of alkaline lignin in aqueous 1-ethyl-3-methylimidazolium acetate [C₂C₁Im][OAc] under oxidizing conditions. Seven different transition metal catalysts were screened in presence of H₂O₂ as oxidizing agent in a batch reactor. CoCl₂ and …

Forces And Disease: Electrostatic Force Differences Caused By Mutations In Kinesin Motor Domains Can Distinguish Between Disease-Causing And Non-Disease-Causing Mutations, Lin Li, Yunhui Peng, Subash Godar, Ivan Getov, Shaolei Teng, Joshua Alper, Emil Alexov

Publications

The ability to predict if a given mutation is disease-causing or not has enormous potential to impact human health. Typically, these predictions are made by assessing the effects of mutation on macromolecular stability and amino acid conservation. Here we report a novel feature: the electrostatic component of the force acting between a kinesin motor domain and tubulin. We demonstrate that changes in the electrostatic component of the binding force are able to discriminate between disease-causing and non-disease-causing mutations found in human kinesin motor domains using the receiver operating characteristic (ROC). Because diseases may originate from multiple effects not related to …

Enhancements In Mass Transfer For Carbon Capture Solvents Part I: Homogeneous Catalyst, Leland R. Widger, Moushumi Sarma, Jonathan J. Bryant, David S. Mannel, Jesse G. Thompson, Cameron A. Lippert, Kunlei Liu

Center for Applied Energy Research Faculty and Staff Publications

The novel small molecule carbonic anhydrase (CA) mimic [Co^III(Salphen-COO⁻)Cl]HNEt₃ (1), was synthesized as an additive for increasing CO₂ absorption rates in amine-based post-combustion carbon capture processes (CCS), and its efficacy was verified. 1 was designed for use in a kinetically slow but thermally stable blended solvent, containing the primary amines 1-amino-2-propanol (A2P) and 2-amino-2-methyl-1-propanol (AMP). Together, the A2P/AMP solvent and 1 reduce the overall energy penalty associated with CO₂ capture from coal-derived flue gas, relative to the baseline solvent MEA. 1 is also effective at increasing absorption kinetics of kinetically fast solvents, such …

Shear Driven Micro-Fluidic Pump For Cardiovascular Applications, Nihad E. Daidzic

Aviation Department Publications

A valveless shear-driven micro-fluidic pump design (SDMFP) for hemodynamic applications is presented in this work. One of the possible medical and biomedical applications is in-vivo hemodynamic (human blood circulation) support/assist. One or more SDMFPs can be inserted/implanted into vascular lumens in a form of a stent/duct in series and/or in parallel (bypass duct) to support blood circulation in-vivo. A comprehensive review of various micro-pump designs up to about mid 2000’s is given in [1,2]. Many of micropump designs considered are not suitable for in-vivo or even in-vitro medical/biomedical applications.

Operating principles, design, and SDMFP features are given in [3]. A …

An Expedited, Regiospecific Para-Bromination Of Activated Aryls, Kathryn E. Dudley

Masters Theses & Specialist Projects

Electrophilic Aromatic Substitution (EAS) is one of the most frequently used aryl substitution methods. Aside from the fact that most EAS reactions require an acid and an oxidizer to proceed, the reactions involving activated aryls typically produce a mixture of ortho- and para- products as well as an ortho-/para- disubstituted product. Regiospecificity in aromatic substitution is key in the production of many compounds in a variety of disciplines. Since EAS is one of the most often used substitution methods, it is extremely important to develop an efficient method for regiospecific substitutions. Previous research developed a method of ortho-substitution by using …

Synthesis, Characterization, And Properties Of Graphene-Based Hybrids With Cobalt Oxides For Electrochemical Energy Storage And Electrocatalytic Glucose Sensing, Sara C. Botero Carrizosa

Masters Theses & Specialist Projects

A library of graphene-based hybrid materials was synthesized as novel hybrid electrochemical electrodes for electrochemical energy conversion and storage devices and electrocatalytical sensing namely enzymeless glucose sensing. The materials used were supercapacitive graphene-family nanomaterials (multilayer graphene-MLG; graphene oxide-GO, chemically reduced GO-rGO and electrochemical reduced GOErGO) and pseudocapacitive nanostructured transition metal oxides including cobalt oxide polymorphs (CoO and Co3O4) and cobalt nanoparticles (CoNP). These were combined through physisorption, electrodeposition, and hydrothermal syntheses approaches. This project was carried out to enhance electrochemical performance and to develop electrocatalytic platforms by tailoring structural properties and desired interfaces. Particularly, electrodeposition and hydrothermal synthesis facilitate chemically-bridged …

Chemically Stable Artificial Sei For Li-Ion Battery Electrodes, Qinglin Zhang, Lei Han, Jie Pan, Zhi Chen, Yang-Tse Cheng

Chemical and Materials Engineering Faculty Publications

The importance of coating's chemical stability in lithium-ion batteries has been demonstrated by this study. It is well known that the mechanical properties determine the cycle life, and chemical stability or chemical degradation rate determines the calendar life. In this study, we used HfO₂ coatings prepared by atomic layer deposition as an example to show the chemical stability of the coatings for lithium ion battery electrodes.

Synthesis And Catalytic Applications Of Non-Metal Doped Mesoporous Titania, Syed Z. Islam, Suraj R. Nagpure, Doo Young Kim, Stephen E. Rankin

Chemical and Materials Engineering Faculty Publications

Mesoporous titania (mp-TiO₂) has drawn tremendous attention for a diverse set of applications due to its high surface area, interfacial structure, and tunable combination of pore size, pore orientation, wall thickness, and pore connectivity. Its pore structure facilitates rapid diffusion of reactants and charge carriers to the photocatalytically active interface of TiO₂. However, because the large band gap of TiO₂ limits its ability to utilize visible light, non-metal doping has been extensively studied to tune the energy levels of TiO₂. While first-principles calculations support the efficacy of this approach, it is challenging to …

Remediating 1,4-Dioxane-Contaminated Water With Slow-Release Persulfate And Zerovalent Iron, Ann Kambhu, Megan Gren, Wei Tang, Steve D. Comfort, Clifford Harris

Nebraska Water Center: Faculty Publications

1,4-dioxane is an emerging contaminant that was used as a corrosion inhibitor with chlorinated solvents. Metal-activated persulfate can degrade dioxane but reaction kinetics have typically been characterized by a rapid decrease during the first 30 min followed by either a slower decrease or no further change (i.e., plateau). Our objective was to identify the factors responsible for this plateau and then determine if slow-release formulations of sodium persulfate and Fe⁰ could provide a more sustainable degradation treatment. We accomplished this by conducting batch experiments where Fe⁰-activated persulfate was used to treat dioxane. Treatment variables included the timing …

Geometry-Driven Folding Of A Floating Annular Sheet, Joseph Paulsen, Vincent Démery, K. Buğra Toga, Zhanlong Qiu, Thomas P. Russell, Benny Davidovitch, Narayanan Menon

Physics - All Scholarship

Predicting the large-amplitude deformations of thin elastic sheets is difficult due to the complications of self contact, geometric nonlinearities, and a multitude of low-lying energy states. We study a simple twodimensional setting where an annular polymer sheet floating on an air-water interface is subjected to different tensions on the inner and outer rims. The sheet folds and wrinkles into many distinct morphologies that break axisymmetry. These states can be understood within a recent geometric approach for determining the gross shape of extremely bendable yet inextensible sheets by extremizing an appropriate area functional. Our analysis explains the remarkable feature that the …

Sugar Versus Lipid For Sustainable Biofuels, Yaşar Demirel

Yaşar Demirel Publications

Introduction

First‐generation biofuels, namely, ethanol and biodiesel, have led to far reaching impact on the peoples’ life world‐wide.[1] However, they inter-fere with the food supply chain and may not be sustainable although some of the biomass are converted to biofuels after those biomasses have met the human needs. Still, the first‐generation–based biofuels have proved that sugar and lipid platforms can be an answer to energy security and global warming concerns without the need for new infrastructure for feedstock delivery as well as for biomass‐to‐biofuel conversion tech-nologies. At the same time, we are discovering and assessing the long‐term environmental im-plications on …

Effects Of Post Eviction Resettlement On Land-Use And Cover Change In Uganda’S Oil Exploration Areas, Joseph Ssekandi, John Mburu, Oliver Wasonga, Laban Macopiyo, Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

Evaluation of the changes in land use and land cover change (LULCC) in respect to oil exploration across the Albertine region in Uganda has been focused around the exploration areas and protected areas, with no attention to the potential impacts of evictees’ activities on resettled areas. This study used LANDSAT images to analyze the land use and land cover changes (LULCC) among the period before eviction (2002 and 2005) at the climax of eviction and resettlements (2005-2011), and during the post-resettlement period (2011-2015) to quantify the impacts of resettlements on the environment. LANDSAT images were processed using ERDAS IMAGINE software …