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Piezoelectric electrostatic superlattices in monolayer MoS2

Physical Review materials 2024年第1期8卷 014002-014002页

作者： Ashwin Ramasubramaniam Doron Naveh Department of Mechanical and Industrial Engineering University of Massachusetts Amherst 01003 MA United States Materials Science and Engineering Graduate Program University of Massachusetts Amherst 01003 MA United States Faculty of Engineering Bar-Ilan University Ramat Gan 52900 Israel Institute for Nanotechnology and Advanced Materials Bar-Ilan University Ramat Gan 52900 Israel

Modulation of electronic properties of materials by electric fields is central to the operation of modern semiconductor devices, providing access to complex electronic behaviors and greater freedom in tuning the energy bands of materials. Here, we explore one-dimensional superlattices induced by a confining electrostatic potential in monolayer MoS2, a prototypical two-dimensional semiconductor. Using first-principles calculations, we show that periodic potentials applied to monolayer MoS2 induce electrostatic superlattices in which the response is dominated by structural distortions relative to purely electronic effects. These structural distortions reduce the intrinsic band gap of the monolayer substantially while also polarizing the monolayer through piezoelectric coupling, resulting in spatial separation of charge carriers as well as Stark shifts that produce dispersive minibands. Importantly, these minibands inherit the valley-selective magnetic properties of monolayer MoS2, enabling fine control over spin-valley coupling in MoS2 and similar transition-metal dichalcogenides.

关键词： Electronic structure Piezoelectricity Valley degrees of freedom

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engineering H2O2 Self-Supplying Platform for Xdynamic Therapies via Ru-Cu Peroxide Nanocarrier: Tumor Microenvironment-Mediated Synergistic Therapy

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ACS Applied materials and Interfaces 2024年第19期16卷 24172-24190页

作者： Dirersa, Worku Batu Kan, Tzu-Chun Chang, Jungshan Getachew, Girum Ochirbat, Sonjid Kizhepat, Shamsa Wibrianto, Aswandi Rasal, Akash Chen, Hung-An Ghule, Anil Vithal Chou, Tzung-Han Chang, Jia-Yaw Department of Chemical Engineering National Taiwan University of Science and Technology Taipei106335 Taiwan Graduate Institute of Medical Sciences College of Medicine Taipei Medical University Taipei11031 Taiwan International Master/Ph.D. Program in Medicine College of Medicine Taipei Medical University Taipei11031 Taiwan International Ph.D. Program for Cell Therapy and Regeneration Medicine College of Medicine Taipei Medical University Taipei11031 Taiwan Green Nanotechnology Laboratory Department of Chemistry Shivaji University Kolhapur416004 India Department of Chemical and Materials Engineering National Yunlin University of Science and Technology Yunlin64002 Taiwan

Of the most common, hypoxia, overexpressed glutathione (GSH), and insufficient H2O2 concentration in the tumor microenvironment (TME) are the main barriers to the advancment of reactive oxygen species (ROS) mediated Xdynamic therapies (X = photo, chemodynamic, chemo). Maximizing Fenton catalytic efficiency is crucial in chemodynamic therapy (CDT), yet endogenous H2O2 levels are not sufficient to attain better anticancer efficacy. Specifically, there is a need to amplify Fenton reactivity within tumors, leveraging the unique attributes of the TME. Herein, for the first time, we design RuxCu1-xO2-Ce6/CPT (RCpCCPT) anticancer nanoagent for TME-mediated synergistic therapy based on heterogeneous Ru-Cu peroxide nanodots (RuxCu1-xO2 NDs) and chlorine e6 (Ce6), loaded with ROS-responsive thioketal (TK) linked-camptothecin (CPT). The Ru-Cu peroxide NDs (RCp NDs, x = 0.50) possess the highest oxygen vacancy (OV) density, which grants them the potential to form massive Lewis’s acid sites for peroxide adsorption, while the dispersibility and targetability of the NDs were improved via surface modification using hyaluronic acid (HA). In TME, RCpCCPT degrades, releasing H2O2, Ru2+/3+, and Cu+/2+ ions, which cooperatively facilitate hydroxyl radical (•OH) formation and deactivate antioxidant GSH enzymes through a cocatalytic loop, resulting in excellent tumor therapeutic efficacy. Furthermore, when combined with laser treatment, RCpCCPT produces singlet oxygen (1O2) for PDT, which induces cell apoptosis at tumor sites. Following ROS generation, the TK linkage is disrupted, releasing up to 92% of the CPT within 48 h. In vitro investigations showed that laser-treated RCpCCPT caused 81.5% cell death from PDT/CDT and chemotherapy (CT). RCpCCPT in cancer cells produces red-blue emission in images of cells taking them in, which allows for fluorescence image-guided Xdynamic treatment. The overall results show that RCp NDs and RCpCCPT are more biocompatible and have excellent Xdynamic the

关键词： Oxidation

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The effects of growth environments on WS2 in electrocatalytic hydrogen evolution reaction

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Journal of Physics and Chemistry of Solids 2024年 185卷

作者： Chang, Yung-Huang Huang, Chien-Sheng Chen, Yuan-Tsung Chiang, Chia-Yu Bachelor Program in Industrial Technology National Yunlin University of Science and Technology Yunlin Taiwan Department of Electronic Engineering National Yunlin University of Science and Technology Yunlin Taiwan Graduate School of Materials Science National Yunlin University of Science and Technology Yunlin Taiwan

Transition metal dichalcogenides (TMDs) recently have attracted much attention because of their outstanding catalytic activity, low cost, and earth abundance in the hydrogen evolution reaction (HER). Among these TMDs, MoS2 and WS2 are recognized as promising HER electrocatalysts and have been explored to be one of the candidates for replacing precious metals. In this work, the electrocatalytic activity of WS2 grown in Ar-only, Ar + H2, and ambient environments were studied, where the WS2 was synthesized by thermolysis from (NH4)2WS4 precursor. Different surface morphologies are shown under the different growth atmospheres. The structures of pure WS2, WS2 and WO3 mixed, and almost WO3 were prepared in different growth atmospheres of Ar-only, Ar + H2, and ambient environment, respectively. All the materials prepared in these different environments exhibit high crystalline characteristic. Especially, the pure WS2 grown in an Ar-only environment presents the preferred (103) lattice plane. The pure WS2 performs the best H2 evolution efficiency, indicating that high crystallinity and preferred (103) lattice plane could be relative to the electrocatalytic activity. The studies provide fundamental insight for further design and preparation of electrocatalysts, useful in the development of clean energy. © 2023 Elsevier Ltd

关键词： Electrocatalysts

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Multi-hole defect photonic crystals with enhanced surface area for biosensing applications

Multi-hole defect photonic crystals with enhanced surface ar...

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Laser science, LS 2013

作者： Hu, S. Kang, C. Zhao, Y. Mares, J.W. Vlasov, Y.A. Assefa, S. Weiss, S.M. Department of Physics and Astronomy Vanderbilt University Nashville TN 37235 United States Interdisciplinary Graduate Program in Materials Science Vanderbilt University Nashville TN 37235 United States Department of Electrical Engineering and Computer Science Vanderbilt University Nashville TN 37235 United States IBM T.J. Watson Research Center Yorktown Heights NY 10536 United States

Multi-hole defect (MHD) photonic crystal cavities functionalized with in situ synthesized DNA bioreceptors are demonstrated for biosensing applications. By significantly increasing light interaction with target biomol... 详细信息

ISBN: (纸本)9781557529879

关键词： Photonic crystals

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Bacterial Mobility and Motility in Porous Media Mimicked By Microspheres

SSRN

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SSRN 2022年

作者： Shrestha, Diksha Ou, Jun Rogers, Ariel Jereb, Amani Wang, Yong Department of Physics Cell and Molecular Graduate Program Materials Science and Engineering Program University of Arkansas FayettevilleAR72701 United States Department of Environmental Resources Engineering Mechanical Engineering Program California State Polytechnic University Humboldt ArcataCA95521 United States

Bacterial motion in porous media are essential for their survival, proper functioning, and variousapplications. Here we investigated the motion of Escherichia coli bacteria in microsphere-mimicked porousmedia. We observed reduced bacterial velocity and enhanced directional changes of bacteria as the densityof microspheres increased, while such changes happened mostly around the microspheres and due to thecollisions with the microspheres. More importantly, we established and quantified the correlation betweenthe bacterial trapping in porous media and the geometric confinement imposed by the microspheres. In addition,numerical simulations showed that the active Brownian motion model in the presence of microspheresresulted in bacterial motion that are consistent with the experimental observations. Our study suggested thatit is important to distinguish the ability of bacteria to move easily – bacterial mobility – from the abilityof bacteria to move independently – bacteria motility. Our results showed that bacterial motility remainssimilar in porous media, but bacterial mobility was significantly affected by the pore-scale confinement. © 2022, The Authors. All rights reserved.

关键词： Microspheres

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Photonic crystal defects with increased surface area for improved refractive index sensing

Photonic crystal defects with increased surface area for imp...

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Conference on Lasers and Electro-Optics, CLEO 2010

作者： Kang, Christopher Christopher Phare Weiss, Sharon M. Vlasov, Yurii A. Assefa, Solomon Interdisciplinary Graduate Program in Materials Science Vanderbilt University Nashville TN 37235 United States Department of Physics and Astronomy Vanderbilt University Nashville TN 37235 United States Department of Electrical Engineering and Computer Science Vanderbilt University Tennessee 37235 United States IBM T.J. Watson Research Center Yorktown Heights NY 10536 United States

Photonic crystal cavities with tunable surface area via multiple-hole defects were investigated for increased resonance wavelength shifts upon exposure to variable-index analytes. Sensitivity was improved by 10% compa... 详细信息

ISBN: (纸本)9781557528896

关键词： Refractive index

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Third-Order Optical Properties of Ag Nanocubes and Ag-Au Hollow Nanostructures Investigated by Femtosecond Z-Scan Measurements

SSRN

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SSRN 2024年

作者： Sousa, Claudevan A. Melo, Antonio F.A.A. Silva, Nefe J.B. Silva, Tânia Patrícia Silva E. Viana, Bartolomeu C. Santos, Francisco Eroni P. Garcia, Hans Department of Physics UFPI - Universidade Federal do Piauí PI Teresina64049-550 Brazil Materials Engineering Graduate Program Federal Institute of Education Science and Technology of Piauí Central Campus PI Teresina64000-040 Brazil Interdisciplinary Laboratory for Advanced Materials BioMatLab group Materials Science & Engineering Graduate Program UFPI - Universidade Federal do Piauí PI Teresina64049-550 Brazil

In this work, we reported experimental investigations on third-order optical properties of aqueous colloidal dispersions of silver nanocubes (Ag-NCs) and Ag-Au hollow nanostructures. The hollow bimetallic are nanoboxes, that were synthesized by galvanic substitution using silver nanocubes as templates, inserting silver with gold in molar ratios of 1.5 and 3.0 mL. This process adjusted tuning the Surface Plasmon Resonance (SPR) compared to the original Ag-NCs nanocubes. Femtosecond Z-scan measurements performed at 1040 nm, 350fs and laser intensities from 99.7 - 279 GW/cm2 shows negative nonlinear refraction for both nanocube and nanoboxes colloids, attributed to hot electron generation. Solvent effects are simultaneously suppressed of the nanostructures. On the other hand, the non-linear absorption observed for bimetallic nanoboxes shows the presence of saturated absorption (SA), but the Ag-NCs do not show a non-linear absorption signal. Therefore, our experimental results provide a reliable reference for the application of these bimetallic nanostructures as active media in nonlinear photonic devices. © 2024, The Authors. All rights reserved.

关键词： Surface plasmon resonance

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DRYING OF REFRACTORY CASTABLES - HOW COMPLEX THE MODELLING NEEDS TO BE? A NUMERICAL AND EXPERIMENTAL STUDY 17

DRYING OF REFRACTORY CASTABLES - HOW COMPLEX THE MODELLING N...

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17th Unified International Technical Conference on Refractories, UNITECR 2022

作者： Moreira, M.H. Pont, S. Dal Ausas, R.F. Cunha, T.M. Luz, A.P. Pandolfelli, V.C. Federal University of Sao Carlos Graduate Program in Materials Science and Engineering SP Sao Carlos Brazil CNRS Grenoble INP 3SR Université Grenoble Alpes Grenoble38000 France Institute of Mathematical and Computer Sciences University of São Paulo SP São Carlos13566-590 Brazil

Calcium aluminate cement (CAC)bonded castables have numerous benefits when compared to monolithic refractories. Their main drawback is their long initial heating, when the physical and chemically-bonded water are released. If the mass flux of water to the ambient is lower than the vapor generation, the gas pressure can increase well above the material's strength resulting in cracks and spalling of the ceramic lining. In order to avoid this, optimized heat up curves are needed, and one promising methodology by using numerical models. Most of these calculations are based on tools used for simulating Portland cement concrete structures on fire and they vary both in complexity and their basic assumptions. Thus, the main question that remains is how complex such models need to be in order to capture the fundamental aspects of this phenomenon. The present work aimed to solve this issue by implementing multiple numerical tools reported in the literature with distinct complexity levels and fundamental assumptions and by also conducting neutron tomography tests on a CAC-bonded castable. It was possible to see that the pressure values predicted by such methodologies are equivalent and the water content predicted is qualitatively similar within the models and with the experimental values, indicating that the simplest approach might be used for predicting the castables' drying. © 2022 Unified International Technical Conference on Refractories, UNITECR 2022 - Proceedings. All rights reserved.

关键词： Portland cement

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Photonic crystal defects with increased surface area for improved refractive index sensing

Photonic crystal defects with increased surface area for imp...

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Conference on Lasers and Electro-Optics

作者： Kang, Christopher Phare, Christopher Weiss, Sharon M. Vlasov, Yurii A. Assefa, Solomon Interdisciplinary Graduate Program in Materials Science Vanderbilt University Nashville TN 37235 United States Department of Physics and Astronomy Vanderbilt University Nashville TN 37235 United States Department of Electrical Engineering and Computer Science Vanderbilt University 37235 United States IBM. T.J. Watson Research Center Yorktown Heights NY 10536 United States

Photonic crystal cavities with tunable surface area via multiple-hole defects were investigated for increased resonance wavelength shins upon exposure to variable-index analytes. Sensitivity was improved by 10% compar... 详细信息

ISBN: (纸本)9781557528902

关键词： Surface defects

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Chitosan for biofunctionalization of microsystems

Chitosan for biofunctionalization of microsystems

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2006 IEEE/NLM Life science Systems and Applications Workshop, LiSA 2006

作者： Koev, Stephan T. Powers, Michael A. Badilita, Vlad Yi, Hyunmin Bentley, William E. Payne, Gregory F. Rubloff, Gary W. Ghodssi, Reza Department of Electrical and Computer Engineering University of Maryland College Park MD 20742 Department of Materials Science and Engineering University of Maryland College Park MD 20742 Department of Chemical Engineering University of Maryland College Park MD 20742 University of Maryland College Park MD 20742 University of Maryland College Park MD 20742 Bioengineering Graduate Program University of Maryland College Park MD 20742

ISBN: (纸本)1424402786

We present the use of the polysaccharide chitosan for immobilizing biomolecules on microfabricated device surfaces. The main advantages of chitosan are its abundance of primary amine groups and its ability to be electrodeposited. Biomolecules are easily attached to chitosan's amines by standard glutaraldehyde chemistry. The electrodeposition of chitosan allows accurate spatial and temporal control of biomolecule placement. We have demonstrated this biofunctionalization method for two different BioMEMS devices: a biophotonic sensor and a micromechanical biosensor. We have successfully assembled probe DNA on each of them and detected hybridization with target DNA as a demonstration of sensor operation. Here, we briefly present the fabrication procedure and testing results for both of these BioMEMS sensing devices. © 2006 IEEE.

关键词： Microsystems

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