Scholarly Works, Chemical Engineering
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Browsing Scholarly Works, Chemical Engineering by Content Type "Article"
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- Algorithm-derived feature representations for explainable AI in catalysisOmidvar, Noushin; Xin, Hongliang (Elsevier, 2021-12-01)Machine learning (ML) has emerged as a critical tool in catalysis, attributed to its capability of finding complex patterns in high dimensional and heterogeneous data. A recently published article in Chem Catalysis (Esterhuizen et al.) used unsupervised ML for uncovering electronic and geometric descriptors of the surface reactivity of metal alloys and oxides.
- Fabrication and Characterization of Three Dimensional Electrospun Cortical Bone ScaffoldsAndric, Tea; Taylor, Brittany L.; Degen, Katherine E.; Whittington, Abby R.; Freeman, Joseph W. (De Gruyter Open, 2014)Bone is a composite tissue composed of an organic matrix, inorganic mineral matrix and water. Structurally, bone is organized into two distinct types: trabecular (or cancellous) and cortical (or compact) bone. Cortical bone is highly organized, dense and composed of tightly packed units or osteons whereas trabecular bone is highly porous and usually found within the confines of cortical bone. Osteons, the subunits of cortical bone, consist of concentric layers of mineralized collagen fibers. While many scaffold fabrication techniques have sought to replicate the structure and organization of trabecular bone, very little research focuses on mimicking the organization of native cortical bone. In this study we fabricated three-dimensional electrospun cortical scaffolds by heat sintering individual osteon-like scaffolds. The scaffolds contained a system of channels running parallel to the length of the scaffolds, as found naturally in the haversian systems of bone tissue. The purpose of the studies discussed in this paper was to develop a mechanically enhanced biomimetic electrospun cortical scaffold. To that end we investigated the appropriate mineralization and cross-linking methods for these structures and to evaluate the mechanical properties of scaffolds with varying fiber angles. Cross-linking the gelatin in the scaffolds prior to the mineralization of the scaffolds proved to help prevent channels of the osteons from collapsing during fabrication. Premineralization, before larger scaffold formation and mineralization, increased mineral deposition between the electrospun layers of the scaffolds. A combination of cross-linking and premineralization significantly increased the compressive moduli of the individual scaffolds. Furthermore, scaffolds with fibers orientation ranging between 15° and 45° yielded the highest compressive moduli and yield strength.
- Identifying Human Interactors of SARS-CoV-2 Proteins and Drug Targets for COVID-19 using Network-Based Label PropagationLaw, Jeffrey N.; Akers, Kyle; Tasnina, Nure; Della Santina, Catherine M.; Kshirsagar, Meghana; Klein-Seetharaman, Judith; Crovella, Mark; Rajagopalan, Padmavathy; Kasif, Simon; Murali, T. M. (Virginia Tech, 2020-06-22)Motivated by the critical need to identify new treatments for COVID- 19, we present a genome-scale, systems-level computational approach to prioritize drug targets based on their potential to regulate host- virus interactions or their downstream signaling targets. We adapt and specialize network label propagation methods to this end. We demonstrate that these techniques can predict human-SARS-CoV- 2 protein interactors with high accuracy. The top-ranked proteins that we identify are enriched in host biological processes that are potentially coopted by the virus. We present cases where our methodology generates promising insights such as the potential role of HSPA5 in viral entry. We highlight the connection between endoplasmic reticulum stress, HSPA5, and anti-clotting agents. We identify tubulin proteins involved in ciliary assembly that are targeted by anti-mitotic drugs. Drugs that we discuss are already undergoing clinical trials to test their efficacy against COVID-19. Our prioritized list of human proteins and drug targets is available as a general resource for biological and clinical researchers who are repositioning existing and approved drugs or developing novel therapeutics as anti-COVID-19 agents.
- Interpretable Machine Learning of Chemical Bonding at Solid SurfacesOmidvar, Noushin; Pillai, Hemanth Somarajan; Wang, Shih-Han; Mou, Tianyou; Wang, Siwen; Athawale, Andy; Achenie, Luke E. K.; Xin, Hongliang (American Chemical Society, 2021-11-25)Understanding the nature of chemical bonding and its variation in strength across physically tunable factors is important for the development of novel catalytic materials. One way to speed up this process is to employ machine learning (ML) algorithms with online data repositories curated from high-throughput experiments or quantum-chemical simulations. Despite the reasonable predictive performance of ML models for predicting reactivity properties of solid surfaces, the ever-growing complexity of modern algorithms, e.g., deep learning, makes them black boxes with little to no explanation. In this Perspective, we discuss recent advances of interpretable ML for opening up these black boxes from the standpoints of feature engineering, algorithm development, and post hoc analysis. We underline the pivotal role of interpretability as the foundation of next-generation ML algorithms and emerging AI platforms for driving discoveries across scientific disciplines.
- Mechanically cycling gelatin bilayersHanzly, Laura E.; Chauhan, Natasha; Barone, Justin R. (2022-01-11)There is a growing interest in making stimuli-responsive polymer systems, particularly ones that are bio-inspired/biomimetic and could perform mechanical work. Here, a biological device made from gelatin is described that can mechanically cycle back and forth in response to solution pH or ionic strength changes. The gelatin bilayer has one layer of Type A gelatin and the other of Type B gelatin, which have 2 different isoelectric points and therefore ionization states at a given solution pH. The bilayer mechanically cycles back and forth when one layer swells more than the other layer, which occurs because of solution pH or ionic strength change. Maximum bilayer bending occurs at pH 10, when the Type B gelatin layer swells significantly more than the Type A layer. The results show the ability to use the unique properties of different sources of gelatin to design a simple biological machine.
- Mitigation of bidirectional solute flux in forward osmosis via membrane surface coating of zwitterion functionalized carbon nanotubesZou, Shiqiang; Smith, Ethan D.; Lin, Shihong; Martin, Stephen M.; He, Zhen (Elsevier, 2019-07-08)Forward osmosis (FO) has emerged as a promising membrane technology to yield high-quality reusable water from various water sources. A key challenge to be solved is the bidirectional solute flux (BSF), including reverse solute flux (RSF) and forward solute flux (FSF). Herein, zwitterion functionalized carbon nanotubes (Z-CNTs) have been coated onto a commercial thin film composite (TFC) membrane, resulting in BSF mitigation via both electrostatic repulsion forces induced by zwitterionic functional groups and steric interactions with CNTs. At a coating density of 0.97 gm⁻², a significantly reduced specific RSF was observed for multiple draw solutes, including NaCl (55.5% reduction), NH₄H₂PO₄(83.8%), (NH₄)₂HPO₄ (74.5%), NH₄Cl (70.8%), and NH₄HCO₃ (61.9%). When a synthetic wastewater was applied as the feed to investigate membrane rejection, FSF was notably reduced by using the coated membrane with fewer pollutants leaked to the draw solution, including NH₄⁺-N (46.3% reduction), NO₂⁻₋N (37.0%), NO₂⁻₋N (30.3%), K⁺ (56.1%), PO₄³⁻₋P (100%), and Mg²⁺ (100%). When fed with real wastewater, a consistent water flux was achieved during semi-continuous operation with enhanced fouling resistance. This study is among the earliest efforts to address BSF control via membrane modification, and the results will encourage further exploration of effective strategies to reduce BSF.
- Note: Method for overcoming ductile failure in Munstedt-type extensional rheometersMcGrady, C. D.; Baird, Donald G. (AIP Publishing, 2009-05-01)The purpose of this note is to introduce an experimental technique to overcome ductile failure in uniaxial extensional flow and show a simple illustration of its effectiveness. Ductile failure prevents the rheological measurement of transient stress growth at higher strains for certain strain-hardening materials. This reduces the accuracy of nonlinear parameters for constitutive equations fit from transient stress growth data, as well as their effectiveness in modeling extensionally driven processes such as film casting. We propose an experimental technique to overcome ductile failure called encapsulation in which the material that undergoes ductile failure is surrounded by a resin that readily deforms homogeneously at higher strains. The materials are arranged in concentric cylinders and are deformed in parallel. A simple parallel model is shown to calculate the viscosity of the core material and is tested for its robustness in a linear low-density polyethylene/low-density polyethylene system in which the viscosities of each resin are known at all strains, strain rates, and temperatures investigated. Agreement is found at each strain rate investigated across all strains studied. The method is then extended to measure the viscosity of a sparsely branched high-density polyethylene (HDPE) system that undergoes ductile failure at higher strain rates. The technique shows good agreement with experimental results up to the onset of ductile failure in the pure resin and predicts viscosity growth of the HDPE resin well beyond the critical strain for the onset of failure seen in experimental measurements of the pure HDPE. Repeatability of the technique is also illustrated. (C) 2009 The Society of Rheology. [DOI: 10.1122/1.3109574]
- The viability of SARS-CoV-2 on solid surfacesHosseini, Mohsen; Behzadinasab, Saeed; Benmamoun, Zachary; Ducker, William A. (Elsevier, 2021-10-01)The COVID-19 pandemic had a major impact on life in 2020 and 2021. One method of transmission occurs when the causative virus, SARS-CoV-2, contaminates solids. Understanding and controlling the interaction with solids is thus potentially important for limiting the spread of the disease. We review work that describes the prevalence of the virus on common objects, the longevity of the virus on solids, and surface coatings that are designed to inactivate the virus. Engineered coatings have already succeeded in producing a large reduction in viral infectivity from surfaces. We also review work describing inactivation on facemasks and clothing and discuss probable mechanisms of inactivation of the virus at surfaces.