1
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Prasad A, Varshney V, Nepal D, Frank GJ. Bioinspired Design Rules from Highly Mineralized Natural Composites for Two-Dimensional Composite Design. Biomimetics (Basel) 2023; 8:500. [PMID: 37887631 PMCID: PMC10604232 DOI: 10.3390/biomimetics8060500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 10/12/2023] [Accepted: 10/17/2023] [Indexed: 10/28/2023] Open
Abstract
Discoveries of two-dimensional (2D) materials, exemplified by the recent entry of MXene, have ushered in a new era of multifunctional materials for applications from electronics to biomedical sensors due to their superior combination of mechanical, chemical, and electrical properties. MXene, for example, can be designed for specialized applications using a plethora of element combinations and surface termination layers, making them attractive for highly optimized multifunctional composites. Although multiple critical engineering applications demand that such composites balance specialized functions with mechanical demands, the current knowledge of the mechanical performance and optimized traits necessary for such composite design is severely limited. In response to this pressing need, this paper critically reviews structure-function connections for highly mineralized 2D natural composites, such as nacre and exoskeletal of windowpane oysters, to extract fundamental bioinspired design principles that provide pathways for multifunctional 2D-based engineered systems. This paper highlights key bioinspired design features, including controlling flake geometry, enhancing interface interlocks, and utilizing polymer interphases, to address the limitations of the current design. Challenges in processing, such as flake size control and incorporating interlocking mechanisms of tablet stitching and nanotube forest, are discussed along with alternative potential solutions, such as roughened interfaces and surface waviness. Finally, this paper discusses future perspectives and opportunities, including bridging the gap between theory and practice with multiscale modeling and machine learning design approaches. Overall, this review underscores the potential of bioinspired design for engineered 2D composites while acknowledging the complexities involved and providing valuable insights for researchers and engineers in this rapidly evolving field.
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Affiliation(s)
- Anamika Prasad
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, USA
- Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174, USA
| | - Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH 45433, USA; (V.V.); (D.N.); (G.J.F.)
| | - Dhriti Nepal
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH 45433, USA; (V.V.); (D.N.); (G.J.F.)
| | - Geoffrey J. Frank
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH 45433, USA; (V.V.); (D.N.); (G.J.F.)
- University of Dayton Research Institute, Dayton, OH 45469, USA
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2
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Tao L, Arbaugh T, Byrnes J, Varshney V, Li Y. Unified machine learning protocol for copolymer structure-property predictions. STAR Protoc 2022; 3:101875. [PMID: 36595914 PMCID: PMC9700038 DOI: 10.1016/j.xpro.2022.101875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 10/06/2022] [Accepted: 11/01/2022] [Indexed: 11/23/2022] Open
Abstract
Structure-property relationships are extremely valuable when predicting the properties of polymers. This protocol demonstrates a step-by-step approach, based on multiple machine learning (ML) architectures, which is capable of processing copolymer types such as alternating, random, block, and gradient copolymers. We detail steps for necessary software installation and construction of datasets. We further describe training and optimization steps for four neural network models and subsequent model visualization and comparison using training and test values. For complete details on the use and execution of this protocol, please refer to Tao et al. (2022).1.
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Affiliation(s)
- Lei Tao
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - Tom Arbaugh
- Department of Physics, Wesleyan University, Middletown, CT 06459, USA
| | | | - Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH 45433, USA
| | - Ying Li
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269, USA,Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706-1572, USA,Corresponding author
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3
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Hubbard AM, Ren Y, Sarvestani A, Konkolewicz D, Picu CR, Roy AK, Varshney V, Nepal D. Recyclability of Vitrimer Materials: Impact of Catalyst and Processing Conditions. ACS Omega 2022; 7:29125-29134. [PMID: 36033717 PMCID: PMC9404514 DOI: 10.1021/acsomega.2c02677] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
With sustainability at the forefront of material research, recyclable polymers, such as vitrimers, have garnered increasing attention since their introduction in 2011. In addition to a traditional glass-transition temperature (T g), vitrimers have a second topology freezing temperature (T v) above which dynamic covalent bonds allow for rapid stress relaxation, self-healing, and shape reprogramming. Herein, we demonstrate the self-healing, shape memory, and shape reconfigurability properties as a function of experimental conditions, aiming toward recyclability and increased useful lifetime of the material. Of interest, we report the influence of processing conditions, which makes the material vulnerable to degradation. We report a decreased crosslink density with increased thermal cycling and compressive stress. Furthermore, we demonstrate that shape reconfigurability and self-healing are enhanced with increasing compressive stress and catalyst concentration, while their performance as a shape memory material remains unchanged. Though increasing the catalyst concentration, temperature, and compressive stress clearly enhances the recovery performance of vitrimers, we must emphasize its trade-off when considering the material degradation reported here. While vitrimers hold great promise as structural materials, it is vital to understand how experimental parameters impact their properties, stability, and reprocessability before vitrimers reach their true potential.
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Affiliation(s)
- Amber M. Hubbard
- Materials
and Manufacturing Directorate, Air Force
Research Laboratory, Wright Patterson
Air Force Base, Ohio 45433, United States
- National
Research Council Research Associate, Air
Force Research Laboratory, Wright
Patterson Air Force Base, Ohio 45433, United States
| | - Yixin Ren
- Materials
and Manufacturing Directorate, Air Force
Research Laboratory, Wright Patterson
Air Force Base, Ohio 45433, United States
- ARCTOS, Beavercreek, Ohio 45432, United States
| | - Alireza Sarvestani
- Department
of Mechanical Engineering, Mercer University, Macon, Georgia 31207, United States
| | - Dominik Konkolewicz
- Department
of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, United States
| | - Catalin R. Picu
- Department
of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Ajit K. Roy
- Materials
and Manufacturing Directorate, Air Force
Research Laboratory, Wright Patterson
Air Force Base, Ohio 45433, United States
| | - Vikas Varshney
- Materials
and Manufacturing Directorate, Air Force
Research Laboratory, Wright Patterson
Air Force Base, Ohio 45433, United States
| | - Dhriti Nepal
- Materials
and Manufacturing Directorate, Air Force
Research Laboratory, Wright Patterson
Air Force Base, Ohio 45433, United States
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4
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Tao L, Byrnes J, Varshney V, Li Y. Machine learning strategies for the structure-property relationship of copolymers. iScience 2022; 25:104585. [PMID: 35789847 PMCID: PMC9249671 DOI: 10.1016/j.isci.2022.104585] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/26/2022] [Accepted: 06/07/2022] [Indexed: 11/15/2022] Open
Abstract
Establishing the structure-property relationship is extremely valuable for the molecular design of copolymers. However, machine learning (ML) models can incorporate both chemical composition and sequence distribution of monomers, and have the generalization ability to process various copolymer types (e.g., alternating, random, block, and gradient copolymers) with a unified approach are missing. To address this challenge, we formulate four different ML models for investigation, including a feedforward neural network (FFNN) model, a convolutional neural network (CNN) model, a recurrent neural network (RNN) model, and a combined FFNN/RNN (Fusion) model. We use various copolymer types to systematically validate the performance and generalizability of different models. We find that the RNN architecture that processes the monomer sequence information both forward and backward is a more suitable ML model for copolymers with better generalizability. As a supplement to polymer informatics, our proposed approach provides an efficient way for the evaluation of copolymers. Establish structure-property relationships of copolymer with machine learning (ML) Incorporate both chemical composition and sequential distribution of copolymers Analyze various copolymer types with different models in a unified approach Differentiate the effects of random, block, and gradient patterns of copolymers
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Affiliation(s)
- Lei Tao
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269, USA
| | | | - Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA
| | - Ying Li
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269, USA
- Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA
- Corresponding author
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5
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Wang C, Kilic KI, Koerner H, Baur JW, Varshney V, Lionti K, Dauskardt RH. Polyimide Hybrid Nanocomposites with Controlled Polymer Filling and Polymer-Matrix Interaction. ACS Appl Mater Interfaces 2022; 14:28239-28246. [PMID: 35679607 DOI: 10.1021/acsami.2c02575] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Polyimide hybrid nanocomposites with the polyimide confined at molecular length scales exhibit enhanced fracture resistance with excellent thermal-oxidative stability at low density. Previously, polyimide nanocomposites were fabricated by infiltration of a polyimide precursor into a nanoporous matrix followed by sequential thermally induced imidization and cross-linking of the polyimide under nanometer-scale confinement. However, byproducts formed during imidization became volatile at the cross-linking temperature, limiting the polymer fill level and degrading the nanocomposite fracture resistance. This is solved in the present work with an easier approach where the nanoporous matrix is filled with shorter preimidized polyimide chains that are cross-linked while in the pores to eliminate the need for confined imidization reactions, which produces better results compared to the previous study. In addition, we selected a preimidized polyimide that has a higher chain mobility and a stronger interaction with the matrix pore surface. Consequently, the toughness achieved with un-cross-linked preimidized polyimide chains in this work is equivalent to that achieved with the cross-linking of the previously used polyimide chains and is doubled when preimidized polyimide chains are cross-linked. The increased chain mobility enables more efficient polymer filling and higher polymer fill levels. The higher polymer-pore surface interaction increases the energy dissipation during polyimide molecular bridging, increasing the nanocomposite fracture resistance. The combination of the higher polymer fill and the stronger polymer-surface interaction is shown to provide significant improvements to the nanocomposite fracture resistance and is validated with a molecular bridging model.
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Affiliation(s)
- Can Wang
- Department of Chemistry, Stanford University, 364 Lomita Drive, Stanford, California 94305, United States
| | - Karsu I Kilic
- Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305, United States
| | - Hilmar Koerner
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Jeffery W Baur
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Vikas Varshney
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Krystelle Lionti
- Hybrid Polymeric Materials and Science to Solutions, IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, United States
| | - Reinhold H Dauskardt
- Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305, United States
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6
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Bennett C, Hayes PJ, Thrasher CJ, Chakma P, Wanasinghe SV, Zhang B, Petit LM, Varshney V, Nepal D, Sarvestani A, Picu CR, Sparks JL, Zanjani MB, Konkolewicz D. Modeling Approach to Capture Hyperelasticity and Temporary Bonds in Soft Polymer Networks. Macromolecules 2022. [DOI: 10.1021/acs.macromol.1c02319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Camaryn Bennett
- Department of Chemistry and Biochemistry, Miami University, 651 East High Street, Oxford, Ohio 45056, United States
| | - Peter J. Hayes
- Department of Mechanical and Manufacturing Engineering, Miami University, 650 East High Street, Oxford, Ohio 45056, United States
| | - Carl J. Thrasher
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson Air Force Base, Ohio 45433, United States
- UES Inc., Dayton, Ohio 45432, United States
| | - Progyateg Chakma
- Department of Chemistry and Biochemistry, Miami University, 651 East High Street, Oxford, Ohio 45056, United States
| | - Shiwanka V. Wanasinghe
- Department of Chemistry and Biochemistry, Miami University, 651 East High Street, Oxford, Ohio 45056, United States
| | - Borui Zhang
- Department of Chemistry and Biochemistry, Miami University, 651 East High Street, Oxford, Ohio 45056, United States
| | - Leilah M. Petit
- Department of Chemistry and Biochemistry, Miami University, 651 East High Street, Oxford, Ohio 45056, United States
| | - Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson Air Force Base, Ohio 45433, United States
| | - Dhriti Nepal
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson Air Force Base, Ohio 45433, United States
| | - Alireza Sarvestani
- Department of Mechanical Engineering, Mercer University, Macon, Georgia 31207, United States
| | - Catalin R. Picu
- Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Jessica L. Sparks
- Department of Chemical, Paper, and Biomedical Engineering, Miami University, 650 East High Street, Oxford, Ohio 45056, United States
| | - Mehdi B. Zanjani
- Department of Mechanical and Manufacturing Engineering, Miami University, 650 East High Street, Oxford, Ohio 45056, United States
| | - Dominik Konkolewicz
- Department of Chemistry and Biochemistry, Miami University, 651 East High Street, Oxford, Ohio 45056, United States
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7
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Agrawal S, Garg A, Varshney V. Recent updates on applications of Lipid-based nanoparticles for site-specific drug delivery. Pharm Nanotechnol 2022; 10:24-41. [PMID: 35249522 DOI: 10.2174/2211738510666220304111848] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/07/2022] [Accepted: 01/25/2022] [Indexed: 11/22/2022]
Abstract
BACKGROUND Site-specific drug delivery is a widespread and demanding area nowadays. Lipid-based nanoparticulate drug delivery systems have shown promising effects for targeting drugs among lymphatic systems, brain tissues, lungs, and skin. Recently, lipid nanoparticles are used for targeting the brain via the mucosal route for local therapeutic effects. Lipid nanoparticles (LNPs) can help in enhancing the efficacy and lowering the toxicities of anticancer drugs to treat the tumors, particularly in lymph after metastases of tumors. LNPs contain a non-polar core that can improve the absorption of lipophilic drugs into the lymph node and treat tumors. Cellular uptake of drugs can also be enhanced using LNPs and therefore, LNPs are the ideal carrier for treating intracellular infections such as leishmaniasis, tuberculosis and parasitic infection in the brain, etc. Furthermore, specific surface modifications with molecules like mannose, or PEG could improve the macrophage uptake and hence effectively eradicate parasites hiding in macrophages. METHOD An electronic literature search was conducted to update the advancements in the field of site-specific drug delivery utilizing lipid-based nanoparticles. A search of the Scopus database (https://www.scopus.com/home.uri) was conducted using the following keywords: lipid-based nanoparticles; site specific delivery. CONCLUSION Solid lipid nanoparticles have shown site-specific targeted delivery to various organs including the liver, oral mucosa, brain, epidermis, pulmonary and lymphatic systems. These lipid-based systems showed improved bioavailability as well as reduced side effects. Therefore, the focus of this article is to review the recent research studies on LNPs for site-specific or targeting drug delivery.
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Affiliation(s)
- Shivanshu Agrawal
- Institute of Pharmaceutical Research, GLA University, Mathura-281406, U.P., India
| | - Anuj Garg
- Institute of Pharmaceutical Research, GLA University, Mathura-281406, U.P., India
| | - Vikas Varshney
- Institute of Pharmaceutical Research, GLA University, Mathura-281406, U.P., India
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8
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Abstract
In the field of polymer informatics, utilizing machine learning (ML) techniques to evaluate the glass transition temperature Tg and other properties of polymers has attracted extensive attention. This data-centric approach is much more efficient and practical than the laborious experimental measurements when encountered a daunting number of polymer structures. Various ML models are demonstrated to perform well for Tg prediction. Nevertheless, they are trained on different data sets, using different structure representations, and based on different feature engineering methods. Thus, the critical question arises on selecting a proper ML model to better handle the Tg prediction with generalization ability. To provide a fair comparison of different ML techniques and examine the key factors that affect the model performance, we carry out a systematic benchmark study by compiling 79 different ML models and training them on a large and diverse data set. The three major components in setting up an ML model are structure representations, feature representations, and ML algorithms. In terms of polymer structure representation, we consider the polymer monomer, repeat unit, and oligomer with longer chain structure. Based on that feature, representation is calculated, including Morgan fingerprinting with or without substructure frequency, RDKit descriptors, molecular embedding, molecular graph, etc. Afterward, the obtained feature input is trained using different ML algorithms, such as deep neural networks, convolutional neural networks, random forest, support vector machine, LASSO regression, and Gaussian process regression. We evaluate the performance of these ML models using a holdout test set and an extra unlabeled data set from high-throughput molecular dynamics simulation. The ML model's generalization ability on an unlabeled data set is especially focused, and the model's sensitivity to topology and the molecular weight of polymers is also taken into consideration. This benchmark study provides not only a guideline for the Tg prediction task but also a useful reference for other polymer informatics tasks.
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Affiliation(s)
- Lei Tao
- Department of Mechanical Engineering, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson Air Force Base, Ohio 45433, United States
| | - Ying Li
- Department of Mechanical Engineering, University of Connecticut, Storrs, Connecticut 06269, United States.,Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, United States
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9
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Bhusal S, Oh C, Kang Y, Varshney V, Ren Y, Nepal D, Roy A, Kedziora G. Transesterification in Vitrimer Polymers Using Bifunctional Catalysts: Modeled with Solution-Phase Experimental Rates and Theoretical Analysis of Efficiency and Mechanisms. J Phys Chem B 2021; 125:2411-2424. [PMID: 33635079 DOI: 10.1021/acs.jpcb.0c10403] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recently, thermoset vitrimer polymers have shown significant promise for structural applications because of their ability to be reshaped and remolded due to their covalent adaptive network (CAN). In these vitrimers, the transesterification reaction is responsible for the CAN, where the efficiency of the reaction is controlled either by organic or by organometallic catalysts. Understanding the mechanism of the transesterification reaction in the bulk phase using direct experimental techniques is extremely difficult due to the highly cross-linked complex structure of thermosetting vitrimers. Therefore, we use solution-phase experiments to investigate the catalytic efficiency and to guide density functional theory (DFT) simulations of the transesterification reaction mechanism with catalysts triazabicyclodecene (TBD), zinc acetate (Zn(OAc)2), 1-methylimidazole (1-MI), and dibutyltin oxide (DBTO). The estimated catalytic efficiency from the detailed DFT reaction path calculations follows the order TBD ≳ DBTO ≳ Zn(OAc)2 > 1-MI, which agrees with the experimental results. In addition to reaction path modeling, the mechanism and the relative rates of the transesterification reaction are analyzed with the assistance of Fukui indices as a measure of electrophilicity and nucleophilicity of atomic sites and with partial charges. It was found that the sum of the nucleophilicity index of the base and the electrophilicity index of the acid of the bifunctional catalysts correlates with the SN2 transition state and tetrahedral intermediate energies, which are related to the barrier of the rate-limiting step. This correlation provides a hypothesis for computational prescreening of potentially better catalysts that have an index in a range of values. These results provide a basis for understanding an important part of the mechanism of transesterification in vitrimer systems and may assist with designing new catalysts.
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Affiliation(s)
- Shusil Bhusal
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Dayton, Ohio 45433, United States.,Universal Technology Corporation, 1270 N Fairfield Rd., Beavercreek, Ohio 45432, United States
| | - Changjun Oh
- Department of Chemistry, Hanyang University, 222 Wangsimni-ro, Seongdong-Gu, Seoul 04763, Republic of Korea
| | - Youngjong Kang
- Department of Chemistry, Hanyang University, 222 Wangsimni-ro, Seongdong-Gu, Seoul 04763, Republic of Korea
| | - Vikas Varshney
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Yixin Ren
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Dayton, Ohio 45433, United States.,Universal Technology Corporation, 1270 N Fairfield Rd., Beavercreek, Ohio 45432, United States
| | - Dhriti Nepal
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Ajit Roy
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Dayton, Ohio 45433, United States
| | - Gary Kedziora
- Air Force Institute of Technology, Department of Engineering Physics, Wright Patterson Air Force Base, Dayton, Ohio 45433, United States
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10
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Seylar J, Stasiouk D, Simone DL, Varshney V, Heckler JE, McKenzie R. Breaking the bottleneck: stilbene as a model compound for optimizing 6π e − photocyclization efficiency. RSC Adv 2021; 11:6504-6508. [PMID: 35423190 PMCID: PMC8694910 DOI: 10.1039/d0ra10619d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 01/25/2021] [Indexed: 01/28/2023] Open
Abstract
TEMPO was more suitable at photocyclizing stilbene than iodine. As stilbene concentration increased, TEMPO produced a higher yield of phenanthrene at shorter times and significantly reduced the potential for undesired [2+2] cycloadditions. Iodine retarded phenanthrene formation because it promoted isomerization to (E)-stilbene which encouraged [2+2] cycloaddition. TEMPO is more effective than iodine in free-radical mediated, photochemical oxidative cyclization of stilbenes at elevated concentrations.![]()
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Affiliation(s)
- Joshua Seylar
- School of Polymer Science and Polymer Engineering
- The University of Akron
- Akron
- USA
| | | | - Davide L. Simone
- Materials and Manufacturing Directorate
- Air Force Research Laboratory
- WPAFB
- USA
| | - Vikas Varshney
- Materials and Manufacturing Directorate
- Air Force Research Laboratory
- WPAFB
- USA
| | - James E. Heckler
- Materials and Manufacturing Directorate
- Air Force Research Laboratory
- WPAFB
- USA
- ARCTOS Technology Solutions
| | - Ruel McKenzie
- School of Polymer Science and Polymer Engineering
- The University of Akron
- Akron
- USA
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11
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Glavin NR, Rao R, Varshney V, Bianco E, Apte A, Roy A, Ringe E, Ajayan PM. Emerging Applications of Elemental 2D Materials. Adv Mater 2020; 32:e1904302. [PMID: 31667920 DOI: 10.1002/adma.201904302] [Citation(s) in RCA: 144] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/08/2019] [Indexed: 05/09/2023]
Abstract
As elemental main group materials (i.e., silicon and germanium) have dominated the field of modern electronics, their monolayer 2D analogues have shown great promise for next-generation electronic materials as well as potential game-changing properties for optoelectronics, energy, and beyond. These atomically thin materials composed of single atomic variants of group III through group VI elements on the periodic table have already demonstrated exciting properties such as near-room-temperature topological insulation in bismuthene, extremely high electron mobilities in phosphorene and silicone, and substantial Li-ion storage capability in borophene. Isolation of these materials within the postgraphene era began with silicene in 2010 and quickly progressed to the experimental identification or theoretical prediction of 15 of the 18 main group elements existing as solids at standard pressure and temperatures. This review first focuses on the significance of defects/functionalization, discussion of different allotropes, and overarching structure-property relationships of 2D main group elemental materials. Then, a complete review of emerging applications in electronics, sensing, spintronics, plasmonics, photodetectors, ultrafast lasers, batteries, supercapacitors, and thermoelectrics is presented by application type, including detailed descriptions of how the material properties may be tailored toward each specific application.
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Affiliation(s)
- Nicholas R Glavin
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH, 45433, USA
| | - Rahul Rao
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH, 45433, USA
- UES Inc., Beavercreek, OH, 45431, USA
| | - Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH, 45433, USA
| | - Elisabeth Bianco
- Department of Chemistry, Rice University, Houston, TX, 77005, USA
- Materials Science and Nano Engineering, Rice University, Houston, TX, 77005, USA
| | - Amey Apte
- Materials Science and Nano Engineering, Rice University, Houston, TX, 77005, USA
| | - Ajit Roy
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH, 45433, USA
| | - Emilie Ringe
- Department of Chemistry, Rice University, Houston, TX, 77005, USA
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK
- Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UK
| | - Pulickel M Ajayan
- Materials Science and Nano Engineering, Rice University, Houston, TX, 77005, USA
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12
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13
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Kennedy WJ, Izor S, Anderson BD, Frank G, Varshney V, Ehlert GJ. Thermal Reshaping Dynamics of Gold Nanorods: Influence of Size, Shape, and Local Environment. ACS Appl Mater Interfaces 2018; 10:43865-43873. [PMID: 30480429 DOI: 10.1021/acsami.8b12965] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The thermal reshaping of gold nanorods in a polymer matrix is an important phenomenon for many potential applications. However, a fundamental understanding of the various mechanisms that govern the nanorod reshaping dynamics is still lacking. Here, we provide evidence for a phenomenological model of the gold nanorod shape transformation based on the measurements and detailed analysis of the time-resolved thermal reshaping for a variety of gold nanorods having different geometries (aspect ratio, volume, diameter) in a cross-linked epoxy matrix at application relevant temperatures (120-220 °C). Our analysis suggests that (a) the nanorod reshaping dynamics consist of two temporal regimes that are governed by different phenomena and (b) the ultimate amount of reshaping at a given temperature depends strongly on the initial particle geometry and the mechanical stiffness of its surroundings. At short times, the shape transformation is dominated by a curvature-induced surface diffusion process, in which the activation energy for diffusion depends on curvature. At long times, however, the surrounding environment plays a key role in slowing the diffusion and stabilizing the nanorod shape. We show that the long-time behavior can be well described using a modified surface diffusion model that takes into account the slowing of atomic diffusivity as a result of external forces arising from mechanical constraints. The ability to tune both the final shape and the reshaping dynamics in nanocomposites opens up new possibilities in tailoring the optical properties of these materials.
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Affiliation(s)
- William J Kennedy
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | - Sarah Izor
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
- UES Inc. , 4401 Dayton Xenia Road , Beavercreek , Ohio 45432 , United States
| | - Bryan D Anderson
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
- Unimin Corporation , 2241 HWY 197N , Bakersville , North Carolina 28705 , United States
| | - Geoffrey Frank
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
- University of Dayton Research Institute , 300 College Park , Dayton , Ohio 45469 , United States
| | - Vikas Varshney
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
- Universal Technology Corporation , 1270 North Fairfield Road , Beavercreek , Ohio 45432 , United States
| | - Gregory J Ehlert
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
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Radue MS, Varshney V, Baur JW, Roy AK, Odegard GM. Molecular Modeling of Cross-Linked Polymers with Complex Cure Pathways: A Case Study of Bismaleimide Resins. Macromolecules 2018. [DOI: 10.1021/acs.macromol.7b01979] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Matthew S. Radue
- Michigan Technological University, Houghton, Michigan 49931, United States
| | - Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Technology, Wright-Patterson Air Force Base, Ohio 45433, United States
- Universal Technology Corporation, Dayton, Ohio 45432, United States
| | - Jeffery W. Baur
- Materials and Manufacturing Directorate, Air Force Research Technology, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Ajit K. Roy
- Materials and Manufacturing Directorate, Air Force Research Technology, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Gregory M. Odegard
- Michigan Technological University, Houghton, Michigan 49931, United States
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Abstract
Experimentally synthesized carbon nanotube (CNTs) junctions (either single or with 2D/3D CNT network topology) are expected to have random orientation of defect sites (non-hexagonal rings) around the junction. This random and irregular nature of the junction topology and defect characteristics is expected to affect their strength and durability as well as impact the associated mesoscopic and macroscopic properties. On the contrary, theoretical and computational studies often investigate structure-property relationships of pristine and regular junctions of carbon nanostructures. In this study, we developed a computational framework to model a variety of junction structures between CNTs with arbitrary spatial (orientation and degree of overlap) and intrinsic (chirality) specifications. The developed computational model also has the ability to tune the degree of topological defects around the junction via a variety of defect annihilation approaches. Our method makes use of the primal/dual meshing concept, where the development and manipulation of the junction nodes occur using triangular meshes (primal mesh), which is eventually converted to its dual mesh (honeycomb mesh) to render a fully covalently bonded CNT junction. Here each carbon atom has 3 bonded neighbors (mimicking sp2 hybridization). Under a given set of CNT orientation, overlap and chirality specifications, the approach creates a number of CNT junction configurations with varying degrees of energetic stability, offering an opportunity to investigate the effect of topological arrangement of defects around the junction on mechanical, electrical and thermal properties. In addition, it is shown via few examples that the discussed methodology can easily be extended to create multi-junction nanotube clusters, multi-wall nanotube junctions, as well as true 3D random network structures.
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Affiliation(s)
- Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433, USA.
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Yang Y, Kim ND, Varshney V, Sihn S, Li Y, Roy AK, Tour JM, Lou J. In situ mechanical investigation of carbon nanotube-graphene junction in three-dimensional carbon nanostructures. Nanoscale 2017; 9:2916-2924. [PMID: 28181613 DOI: 10.1039/c6nr09897e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Hierarchically organized three-dimensional (3D) carbon nanotubes/graphene (CNTs/graphene) hybrid nanostructures hold great promises in composite and battery applications. Understanding the junction strength between CNTs and graphene is crucial for utilizing such special nanostructures. Here, in situ pulling an individual CNT bundle out of graphene is carried out for the first time using a nanomechanical tester developed in-house, and the measured junction strength of CNTs/graphene is 2.23 ± 0.56 GPa. The post transmission electron microscopy (TEM) analysis of remained graphene after peeling off CNT forest confirms that the failure during pull-out test occurs at the CNT-graphene junction. Such a carefully designed study makes it possible to better understand the interfacial interactions between CNTs and graphene in the 3D CNTs/graphene nanostructures. The coupled experimental and computational effort suggests that the junction between the CNTs and the graphene layer is likely to be chemically bonded, or at least consisting of a mixture of chemical bonding and van der Waals interactions.
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Affiliation(s)
- Yingchao Yang
- Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, TX 77005, USA.
| | - Nam Dong Kim
- Department of Chemistry, Rice University, 6100 Main Street, Houston, TX 77005, USA
| | - Vikas Varshney
- Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/RXAN, Wright-Patterson AFB, OH 45433, USA. and Universal Technology Corporation, 1270 N. Fairfield Road, Dayton, OH 45432, USA
| | - Sangwook Sihn
- Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/RXAN, Wright-Patterson AFB, OH 45433, USA. and University of Dayton Research Institute, 300 College Park, Dayton, OH 45469, USA
| | - Yilun Li
- Department of Chemistry, Rice University, 6100 Main Street, Houston, TX 77005, USA
| | - Ajit K Roy
- Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/RXAN, Wright-Patterson AFB, OH 45433, USA.
| | - James M Tour
- Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, TX 77005, USA. and Department of Chemistry, Rice University, 6100 Main Street, Houston, TX 77005, USA and NanoCarbon Center, Rice University, 6100 Main Street, Houston, TX 77005, USA
| | - Jun Lou
- Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, TX 77005, USA.
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Wu X, Varshney V, Lee J, Zhang T, Wohlwend JL, Roy AK, Luo T. Hydrogenation of Penta-Graphene Leads to Unexpected Large Improvement in Thermal Conductivity. Nano Lett 2016; 16:3925-3935. [PMID: 27152879 DOI: 10.1021/acs.nanolett.6b01536] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Penta-graphene (PG) has been identified as a novel two-dimensional (2D) material with an intrinsic bandgap, which makes it especially promising for electronics applications. In this work, we use first-principles lattice dynamics and iterative solution of the phonon Boltzmann transport equation (BTE) to determine the thermal conductivity of PG and its more stable derivative, hydrogenated penta-graphene (HPG). As a comparison, we also studied the effect of hydrogenation on graphene thermal conductivity. In contrast to hydrogenation of graphene, which leads to a dramatic decrease in thermal conductivity, HPG shows a notable increase in thermal conductivity, which is much higher than that of PG. Considering the necessity of using the same thickness when comparing thermal conductivity values of different 2D materials, hydrogenation leads to a 63% reduction in thermal conductivity for graphene, while it results in a 76% increase for PG. The high thermal conductivity of HPG makes it more thermally conductive than most other semiconducting 2D materials, such as the transition metal chalcogenides. Our detailed analyses show that the primary reason for the counterintuitive hydrogenation-induced thermal conductivity enhancement is the weaker bond anharmonicity in HPG than PG. This leads to weaker phonon scattering after hydrogenation, despite the increase in the phonon scattering phase space. The high thermal conductivity of HPG may inspire intensive research around HPG and other derivatives of PG as potential materials for future nanoelectronic devices. The fundamental physics understood from this study may open up a new strategy to engineer thermal transport properties of other 2D materials by controlling bond anharmonicity via functionalization.
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Affiliation(s)
- Xufei Wu
- Aerospace and Mechanical Engineering, University of Notre Dame , Notre Dame, Indiana 46530, United States
| | - Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433, United States
- Universal Technology Corporation , Dayton, Ohio 45342, United States
| | - Jonghoon Lee
- Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433, United States
- Universal Technology Corporation , Dayton, Ohio 45342, United States
| | - Teng Zhang
- Aerospace and Mechanical Engineering, University of Notre Dame , Notre Dame, Indiana 46530, United States
| | - Jennifer L Wohlwend
- Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433, United States
- Universal Technology Corporation , Dayton, Ohio 45342, United States
| | - Ajit K Roy
- Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Tengfei Luo
- Aerospace and Mechanical Engineering, University of Notre Dame , Notre Dame, Indiana 46530, United States
- Center for Sustainable Energy at Notre Dame , Notre Dame, Indiana 46530, United States
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Lee J, Varshney V, Park J, Farmer BL, Roy AK. In silico carbon molecular beam epitaxial growth of graphene on the h-BN substrate: carbon source effect on van der Waals epitaxy. Nanoscale 2016; 8:9704-9713. [PMID: 27108606 DOI: 10.1039/c6nr01396a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon molecular beam epitaxy (CMBE) techniques using solid carbon sublimation have reported relatively poor quality of the graphene. In this article, the CMBE growth of graphene on the h-BN substrate is numerically studied in order to identify the effect of the carbon source on the quality of the graphene film. The carbon molecular beam generated by the sublimation of solid carbon source materials such as graphite and glassy carbon is mostly composed of atomic carbon, carbon dimers and carbon trimers. Therefore, the graphene film growth becomes a complex process involving various deposition characteristics of a multitude of carbon entities. Based on the study of surface adsorption and film growth characteristics of these three major carbon entities comprising graphite vapour, we report that carbon trimers convey strong traits of vdW epitaxy prone to high quality graphene growth, while atomic carbon deposition is a surface-reaction limited process accompanied by strong chemisorption. The vdW epitaxial behaviour of carbon trimers is found to be substantial enough to nucleate and develop into graphene like planar films within a nanosecond of high flux growth simulation, while reactive atomic carbons tend to impair the structural integrity of the crystalline h-BN substrate upon deposition to form an amorphous interface between the substrate and the growing carbon film. The content of reactive atomic carbons in the molecular beam is suspected to be the primary cause of low quality graphene reported in the literature. A possible optimization of the molecular beam composition towards the synthesis of better quality graphene films is suggested.
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Affiliation(s)
- Jonghoon Lee
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA and Universal Technology Corporation, 1270 N. Fairfield Rd., Dayton, Ohio 45432, USA.
| | - Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA and Universal Technology Corporation, 1270 N. Fairfield Rd., Dayton, Ohio 45432, USA.
| | - Jeongho Park
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA and Universal Technology Corporation, 1270 N. Fairfield Rd., Dayton, Ohio 45432, USA.
| | - Barry L Farmer
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA
| | - Ajit K Roy
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA
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Wu X, Lee J, Varshney V, Wohlwend JL, Roy AK, Luo T. Thermal Conductivity of Wurtzite Zinc-Oxide from First-Principles Lattice Dynamics--a Comparative Study with Gallium Nitride. Sci Rep 2016; 6:22504. [PMID: 26928396 PMCID: PMC4772549 DOI: 10.1038/srep22504] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/16/2016] [Indexed: 01/31/2023] Open
Abstract
Wurtzite Zinc-Oxide (w-ZnO) is a wide bandgap semiconductor that holds promise in power electronics applications, where heat dissipation is of critical importance. However, large discrepancies exist in the literature on the thermal conductivity of w-ZnO. In this paper, we determine the thermal conductivity of w-ZnO using first-principles lattice dynamics and compare it to that of wurtzite Gallium-Nitride (w-GaN) – another important wide bandgap semiconductor with the same crystal structure and similar atomic masses as w-ZnO. However, the thermal conductivity values show large differences (400 W/mK of w-GaN vs. 50 W/mK of w-ZnO at room temperature). It is found that the much lower thermal conductivity of ZnO originates from the smaller phonon group velocities, larger three-phonon scattering phase space and larger anharmonicity. Compared to w-GaN, w-ZnO has a smaller frequency gap in phonon dispersion, which is responsible for the stronger anharmonic phonon scattering, and the weaker interatomic bonds in w-ZnO leads to smaller phonon group velocities. The thermal conductivity of w-ZnO also shows strong size effect with nano-sized grains or structures. The results from this work help identify the cause of large discrepancies in w-ZnO thermal conductivity and will provide in-depth understanding of phonon dynamics for the design of w-ZnO-based electronics.
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Affiliation(s)
- Xufei Wu
- Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46530
| | - Jonghoon Lee
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433.,Universal Technology Corporation, Dayton, OH, 45342
| | - Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433.,Universal Technology Corporation, Dayton, OH, 45342
| | - Jennifer L Wohlwend
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433.,Universal Technology Corporation, Dayton, OH, 45342
| | - Ajit K Roy
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433
| | - Tengfei Luo
- Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46530.,Center for Sustainable Energy at Notre Dame, Notre Dame, IN 46530
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Varshney G, Kanel SR, Kempisty DM, Varshney V, Agrawal A, Sahle-Demessie E, Varma RS, Nadagouda MN. Nanoscale TiO2 films and their application in remediation of organic pollutants. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2015.06.011] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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21
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Varshney V, Roy AK, Baur JW. Modeling the Role of Bulk and Surface Characteristics of Carbon Fiber on Thermal Conductance across the Carbon-Fiber/Matrix Interface. ACS Appl Mater Interfaces 2015; 7:26674-26683. [PMID: 26551435 DOI: 10.1021/acsami.5b08591] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The rapid heating of carbon-fiber-reinforced polymer matrix composites leads to complex thermophysical interactions which not only are dependent on the thermal properties of the constituents and microstructure but are also dependent on the thermal transport between the fiber and resin interfaces. Using atomistic molecular dynamics simulations, the thermal conductance across the interface between a carbon-fiber near-surface region and bismaleimide monomer matrix is calculated as a function of the interface and bulk features of the carbon fiber. The surface of the carbon fiber is modeled as sheets of graphitic carbon with (a) varying degrees of surface functionality, (b) varying defect concentrations in the surface-carbon model (pure graphitic vs partially graphitic), (c) varying orientation of graphitic carbon at the interface, (d) varying interface saturation (dangling vs saturated bonds), (e) varying degrees of surface roughness, and (f) incorporating high conductive fillers (carbon nanotubes) at the interface. After combining separately equilibrated matrix system and different surface-carbon models, thermal energy exchange is investigated in terms of interface thermal conductance across the carbon fiber and the matrix. It is observed that modifications in the studied parameters (a-f) often lead to significant modulation of thermal conductance across the interface and, thus, showcases the role of interface tailoring and surface-carbon morphology toward thermal energy exchange. More importantly, the results provide key bounds and a realistic degree of variation to the interface thermal conductance values at fiber/matrix interfaces as a function of different surface-carbon features.
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Affiliation(s)
- Vikas Varshney
- Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433-7749, United States
- Universal Technology Corporation , Dayton, Ohio 45432-2636, United States
| | - Ajit K Roy
- Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433-7749, United States
| | - Jeffery W Baur
- Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433-7749, United States
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Muratore C, Varshney V, Gengler JJ, Hu J, Bultman JE, Roy AK, Farmer BL, Voevodin AA. Thermal anisotropy in nano-crystalline MoS2 thin films. Phys Chem Chem Phys 2013; 16:1008-14. [PMID: 24281390 DOI: 10.1039/c3cp53746c] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, we grow thin MoS2 films (50-150 nm) uniformly over large areas (>1 cm(2)) with strong basal plane (002) or edge plane (100) orientations to characterize thermal anisotropy. Measurement results are correlated with molecular dynamics simulations of thermal transport for perfect and defective MoS2 crystals. The correlation between predicted (simulations) and measured (experimental) thermal conductivity are attributed to factors such as crystalline domain orientation and size, thereby demonstrating the importance of thermal boundary scattering in limiting thermal conductivity in nano-crystalline MoS2 thin films. Furthermore, we demonstrate that the cross-plane thermal conductivity of the films is strongly impacted by exposure to ambient humidity.
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Affiliation(s)
- Chris Muratore
- Department of Chemical and Materials Engineering, University of Dayton, Dayton, OH 45469, USA.
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Abstract
In this paper, we studied the effect of microscopic surface roughness on heat transfer between aluminum and water by molecular dynamic (MD) simulations and macroscopic surface roughness on heat transfer between aluminum and water by finite element (FE) method. It was observed that as the microscopic scale surface roughness increases, the thermal boundary conductance increases. At the macroscopic scale, different degrees of surface roughness were studied by finite element method. The heat transfer was observed to enhance as the surface roughness increases. Based on the studies of thermal boundary conductance as a function of system size at the molecular level, a procedure was proposed to obtain the thermal boundary conductance at the mesoscopic scale. The thermal boundary resistance at the microscopic scale obtained by MD simulations and the thermal boundary resistance at the mesoscopic scale obtained by the extrapolation procedure can be included and implemented at the interfacial elements in the finite element method at the macroscopic scale. This provides us a useful model, in which different scales of surface roughness can be included, for heat transfer analysis.
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Affiliation(s)
| | | | - Jennifer L. Wohlwend
- Thermal Sciences and Materials Branch, Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson AFB, OH 45433; Universal Technology Corporation, 1270 North Fairfield Road, Dayton, OH 45432
| | - Ajit K. Roy
- Thermal Sciences and Materials Branch, Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson AFB, OH 45433
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Varshney V, Roy AK, Dudis DS, Lee J, Farmer BL. A novel nano-configuration for thermoelectrics: helicity induced thermal conductivity reduction in nanowires. Nanoscale 2012; 4:5009-5016. [PMID: 22767206 DOI: 10.1039/c2nr30602f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In this article, we propose a novel helical nano-configuration towards the designing of high ZT thermoelectric materials. Non-equilibrium molecular dynamics (NEMD) simulations for 'model' bi-component nanowires indicate that a significant reduction in thermal conductivity, similar to that of flat superlattice nanostructures, can be achieved using a helical geometric configuration. The reduction is attributed to a plethora of transmissive and reflective phonon scattering events resulting from the steady alteration of phonon propagating direction that emerges from the continuous rotation of the helical interface. We also show that increasing the relative mass ratio of the two components lowers the phonon energy transmission at the interface due to differences in vibrational frequency spectra, thereby relatively 'easing' the phonon energy propagation along the helical pathway. While the proposed mechanisms result in a reduced lattice thermal conductivity, the continuous nature of the bi-component nanowire would not be expected to significantly reduce its electrical counterpart, as often occurs in superlattice/alloy nanostructures. Hence, we postulate that the helical configuration of atomic arrangement provides an attractive and general framework for improved thermoelectric material assemblies independent of the specific chemical composition.
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Affiliation(s)
- Vikas Varshney
- Nanoelectronics Materials Branch, Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH 45433, USA.
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Lee J, Varshney V, Roy AK, Ferguson JB, Farmer BL. Thermal rectification in three-dimensional asymmetric nanostructure. Nano Lett 2012; 12:3491-3496. [PMID: 22716162 DOI: 10.1021/nl301006y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Previously, thermal rectification has been reported in several low-dimensional shape-asymmetric nanomaterials. In this Letter, we demonstrate that a three-dimensional crystalline material with an asymmetric shape also displays as strong thermal rectification as low-dimensional materials do. The observed rectification is attributed to the stronger temperature dependence of vibration density of states in the narrower region of the asymmetric material, resulting from the small number of atomic degrees of freedom directly interacting with the thermostat. We also demonstrate that the often reported "device shape asymmetry" is not a sufficient condition for thermal rectification. Specifically, the size asymmetry in boundary thermal contacts is equally important toward determining the magnitude of thermal rectification. When the boundary thermal contacts retain the same size asymmetry as the nanomaterial, the overall system displays notable thermal rectification, in accordance with existing literature. However, when the wider region of the asymmetric nanomaterial is partially thermostatted by a smaller sized contact, thermal rectification decreases dramatically and even changes direction.
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Affiliation(s)
- Jonghoon Lee
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States.
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Roy AK, Farmer BL, Varshney V, Sihn S, Lee J, Ganguli S. Importance of interfaces in governing thermal transport in composite materials: modeling and experimental perspectives. ACS Appl Mater Interfaces 2012; 4:545-63. [PMID: 22295993 DOI: 10.1021/am201496z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Thermal management in polymeric composite materials has become increasingly critical in the air-vehicle industry because of the increasing thermal load in small-scale composite devices extensively used in electronics and aerospace systems. The thermal transport phenomenon in these small-scale heterogeneous systems is essentially controlled by the interface thermal resistance because of the large surface-to-volume ratio. In this review article, several modeling strategies are discussed for different length scales, complemented by our experimental efforts to tailor the thermal transport properties of polymeric composite materials. Progress in the molecular modeling of thermal transport in thermosets is reviewed along with a discussion on the interface thermal resistance between functionalized carbon nanotube and epoxy resin systems. For the thermal transport in fiber-reinforced composites, various micromechanics-based analytical and numerical modeling schemes are reviewed in predicting the transverse thermal conductivity. Numerical schemes used to realize and scale the interface thermal resistance and the finite mean free path of the energy carrier in the mesoscale are discussed in the frame of the lattice Boltzmann-Peierls-Callaway equation. Finally, guided by modeling, complementary experimental efforts are discussed for exfoliated graphite and vertically aligned nanotubes based composites toward improving their effective thermal conductivity by tailoring interface thermal resistance.
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Affiliation(s)
- Ajit K Roy
- Thermal Sciences and Materials Branch, Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433-7750, United States.
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Lee J, Varshney V, Roy AK, Farmer BL. Single mode phonon energy transmission in functionalized carbon nanotubes. J Chem Phys 2011; 135:104109. [DOI: 10.1063/1.3633514] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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28
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Varshney V, Roy AK, Froudakis G, Farmer BL. Molecular dynamics simulations of thermal transport in porous nanotube network structures. Nanoscale 2011; 3:3679-3684. [PMID: 21808788 DOI: 10.1039/c1nr10331h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Carbon nanotube based 3D nanostructures have shown a lot of promise towards designing next generation of multi-functional systems, such as nano-electronic devices. Motivated by their recent successful experimental synthesis as well as characterization, and realizing that thermal dissipation is an important concern in proposed devices because of ever-increasing power density, we have investigated the phononic thermal transport behavior in 3D porous nanotube network structures using reverse non-equilibrium molecular dynamics simulations. Based on our study, the length scale associated with the distance between nanotube junctions emerges as the most dominating parameter that governs phonon scattering (hence the characteristic mean free path) and the heat flow in these nanostructures at molecular length scales. However, because of their spatial inhomogeneity, we show that the aerial density of carbon nanotubes (normal to heat flow) is also of critical importance in determining their system-level thermal conductivity. Based on our findings, we postulate that both parameters should be considered while designing nano-devices where thermal management is relevant.
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Affiliation(s)
- Vikas Varshney
- Thermal Sciences and Materials Branch, Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH 45433, USA.
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Varshney V, Patnaik SS, Roy AK, Froudakis G, Farmer BL. Modeling of thermal transport in pillared-graphene architectures. ACS Nano 2010; 4:1153-61. [PMID: 20112924 DOI: 10.1021/nn901341r] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Carbon nanotubes (CNT) and graphene are considered as potential future candidates for many nano/microscale integrated devices due to their superior thermal properties. Both systems, however, exhibit significant anisotropy in their thermal conduction, limiting their performance as three-dimensional thermal transport materials. From thermal management perspective, one way to tailor this anisotropy is to consider designing alternative carbon-based architectures. This paper investigates the thermal transport in one such novel architecture-a pillared-graphene (PG) network nanostructure which combines graphene sheets and carbon nanotubes to create a three-dimensional network. Nonequilibrium molecular dynamics simulations have been carried out using the AIREBO potential to calculate the thermal conductivity of pillared-graphene structures along parallel (in-plane) as well as perpendicular (out-of-plane) directions with respect to the graphene plane. The resulting thermal conductivity values for PG systems are discussed and compared with simulated values for pure CNT and graphite. Our results show that in these PG structures, the thermal transport is governed by the minimum interpillar distance and the CNT-pillar length. This is primarily attributed to scattering of phonons occurring at the CNT-graphene junctions in these nanostructures. We foresee that such architecture could potentially be used as a template for designing future structurally stable microscale systems with tailorable in-plane and out-of-plane thermal transport.
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Affiliation(s)
- Vikas Varshney
- Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Dayton, Ohio, USA
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Affiliation(s)
- Veronique Lachat
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909
| | - Vikas Varshney
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Dayton, Ohio 45433, and Universal Technology Corporation, Dayton, Ohio 45432
| | - Ali Dhinojwala
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909
| | - Mohsen S. Yeganeh
- ExxonMobil Research and Engineering Company, Corporate Strategic Research, Annandale, New Jersey 08801
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31
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Varshney V, Patnaik SS, Roy AK, Farmer BL. A Molecular Dynamics Study of Epoxy-Based Networks: Cross-Linking Procedure and Prediction of Molecular and Material Properties. Macromolecules 2008. [DOI: 10.1021/ma801153e] [Citation(s) in RCA: 313] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vikas Varshney
- Universal Technology Corporation, Dayton, Ohio 45432 and Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson AFB, Dayton, Ohio 45433-7750
| | - Soumya S. Patnaik
- Universal Technology Corporation, Dayton, Ohio 45432 and Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson AFB, Dayton, Ohio 45433-7750
| | - Ajit K. Roy
- Universal Technology Corporation, Dayton, Ohio 45432 and Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson AFB, Dayton, Ohio 45433-7750
| | - Barry L. Farmer
- Universal Technology Corporation, Dayton, Ohio 45432 and Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson AFB, Dayton, Ohio 45433-7750
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33
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Mandal G, Dass R, Garg A, Varshney V, Mondal A. Effect of zinc supplementation from inorganic and
organic sources on growth and blood biochemical
profile in crossbred calves. J Anim Feed Sci 2008. [DOI: 10.22358/jafs/66478/2008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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34
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Varshney V, Carri GA. How does the coupling of secondary and tertiary interactions control the folding of helical macromolecules? J Chem Phys 2007; 126:044906. [PMID: 17286508 DOI: 10.1063/1.2428298] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The authors study how the simultaneous presence of short-range secondary and long-range tertiary interactions controls the folding and collapse behavior of a helical macromolecule. The secondary interactions stabilize the helical conformation of the chain, while the tertiary interactions govern its overall three-dimensional shape. The authors have carried out Monte Carlo simulations to study the effect of chain length on the folding and collapse behavior of the chain. They have calculated state diagrams for four chain lengths and found that the physics is very rich with a plethora of stable conformational states. In addition to the helix-coil and coil-globule transitions, their model describes the coupling between them which takes place at low temperatures. Under these conditions, their model predicts a cascade of continuous, conformational transitions between states with an increase in the strength of the tertiary interactions. During each transition the chain shrinks, i.e., collapses, in a rapid and specific manner. In addition, the number of the transitions increases with increasing chain length. They have also found that the low-temperature regions of the state diagram between the transition lines cannot be associated with specific structures of the chain, but rather, with ensembles of various configurations of the chain with similar characteristics. Based on these results the authors propose a mechanism for the folding and collapse of helical macromolecules which is further supported by the analysis of configurational, configurational, and thermodynamic properties of the chain.
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Affiliation(s)
- Vikas Varshney
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, USA
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Abstract
We explore the coupling between the helix-coil and coil-globule transitions of a helical polymer using Monte Carlo simulations. A very rich state diagram is found. Each state is characterized by a specific configuration of the chain which could be a helix, a random coil, an amorphous globule, or one of various other globular states which carry residual helical strands. We study the boundaries between states and provide further insight into the physics of the system with a detailed analysis of the order parameter and other properties.
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Affiliation(s)
- Vikas Varshney
- The Maurice Morton Institute of Polymer Science, The University of Akron, Ohio 44325-3909, USA
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36
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Affiliation(s)
- Vikas Varshney
- The Maurice Morton Institute of Polymer Science, The University of Akron, Akron, Ohio 44325-3909
| | - Gustavo A. Carri
- The Maurice Morton Institute of Polymer Science, The University of Akron, Akron, Ohio 44325-3909
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Varshney V, Dirama TE, Sen TZ, Carri GA. A Minimal Model for the Helix−Coil Transition of Wormlike Polymers. Insights from Monte Carlo Simulations and Theoretical Implications. Macromolecules 2004. [DOI: 10.1021/ma049338u] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vikas Varshney
- The Maurice Morton Institute of Polymer Science, The University of Akron, Akron, Ohio 44325-3909
| | - Taner E. Dirama
- The Maurice Morton Institute of Polymer Science, The University of Akron, Akron, Ohio 44325-3909
| | - Taner Z. Sen
- The Maurice Morton Institute of Polymer Science, The University of Akron, Akron, Ohio 44325-3909
| | - Gustavo A. Carri
- The Maurice Morton Institute of Polymer Science, The University of Akron, Akron, Ohio 44325-3909
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Rao A, Rangwalla H, Varshney V, Dhinojwala A. Structure of poly(methyl methacrylate) chains adsorbed on sapphire probed using infrared-visible sum frequency generation spectroscopy. Langmuir 2004; 20:7183-7188. [PMID: 15301504 DOI: 10.1021/la049413u] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We have studied the orientation of the train segments of a poly(methyl methacrylate) (PMMA) adsorbed layer at the CCl4-sapphire interface using surface-sensitive IR-visible sum frequency generation (SFG) spectroscopy. The SFG spectra of PMMA chains adsorbed on sapphire indicate ordered ester methyl groups. In comparison, we did not observe any significant contributions from the backbone methylene and alpha methyl groups, suggesting that these groups are disordered. No change in the structure of the adsorbed layer is observed upon cooling the solvent below the theta temperature; this is consistent with the picture of flat adsorbed chains on the surface. Interestingly, the orientation of the ester methyl groups of a spin-coated PMMA film at the PMMA-sapphire interface is similar to that of the same groups in the chains adsorbed from solution.
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Affiliation(s)
- Ashwin Rao
- Department of Polymer Science, University of Akron, Akron, Ohio 44325, USA
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Lakshmi V, Kumar R, Gupta P, Varshney V, Srivastava MN, Dikshit M, Murthy PK, Misra-Bhattacharya S. The antifilarial activity of a marine red alga, Botryocladia leptopoda, against experimental infections with animal and human filariae. Parasitol Res 2004; 93:468-74. [PMID: 15243801 DOI: 10.1007/s00436-004-1159-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2004] [Accepted: 06/17/2004] [Indexed: 11/30/2022]
Abstract
The antifilarial activity of the marine red alga Botryocladia leptopoda against rodent and human lymphatic filarial parasites is described. The animal filarial species included Litomosoides sigmodontis and Acanthocheilonema viteae maintained in cotton rats and Mastomys coucha, respectively, while a subperiodic strain of the human lymphatic filarial parasite Brugia malayi was maintained in M. coucha. The crude extract and its hexane fraction brought about a marked reduction in the peripheral microfilarial level in both of the rodent filarial parasites L. sigmodontis and A. viteae. The microfilaricidal effect began slowly from day 8 or 15 after initiation of treatment and increased with time with a very high efficacy at the end of the observation period against both rodent filariids. The microfilaricidal efficacy was, however, not as prominent in the case of B. malayi. The antifilarial activity, which occurred in the hexane fraction, exerted action at a much lower dose. The product killed a significant proportion of A. viteae and L. sigmodontis adult parasites. In the case of B. malayi, although the macrofilaricidal efficacy was much less than that of the rodent parasites, it (hexane fraction) caused sterilization of a significant proportion of the surviving female parasites. The present findings indicate the possibility of developing an adulticidal and female sterilizing agent against filarial parasites from a marine red alga.
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Affiliation(s)
- V Lakshmi
- Division of Medicinal Chemistry, Central Drug Research Institute, 226001, Lucknow, India.
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Abstract
In this paper, we demonstrate the two-dimensional mapping of plasmon energies by energy-filtering transmission electron microscopy. The maps are obtained from a series of energy-filtered images in the plasmon energy region. Examples are shown for a nano-crystalline Si-B-C-N ceramic. This material contains SiC and Si(3)N(4) grains as well as intergranular regions composed of hexagonal BN (h-BN) and turbostratic carbon (t-C). The different phases can be clearly identified by their specific plasmon energies. An energy resolution of < or =0.1eV is achieved. In addition, the plasmon map of an amorphous carbon film is used to visualize the non-isochromaticity of the Corrected Omega filter (90 degrees filter) of the SESAM2. A procedure is proposed for the correction of the non-isochromaticity.
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Affiliation(s)
- W Sigle
- Max-Planck-Institut für Metallforschung, Heisenbergstrasse 3, D-70569, Stuttgart, Germany.
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41
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Saxena P, Varshney V, Saxena PN. Effect of lithium carbonate on central thermoregulation in rabbits. Indian J Med Res 1988; 88:363-70. [PMID: 3147241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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42
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Saxena P, Varshney V, Chandra O, Saxena PN. Effect of intracerebroventricularly injected copper on rectal temperature of rabbits. Indian J Med Res 1986; 84:650-6. [PMID: 3106202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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