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Jin Y, Perez-Lemus GR, Zubieta Rico PF, de Pablo JJ. Improving Machine Learned Force Fields for Complex Fluids through Enhanced Sampling: A Liquid Crystal Case Study. J Phys Chem A 2024; 128:7257-7268. [PMID: 39150905 DOI: 10.1021/acs.jpca.4c01546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2024]
Abstract
Machine learned force fields offer the potential for faster execution times while retaining the accuracy of traditional DFT calculations, making them promising candidates for molecular simulations in cases where reliable classical force fields are not available. Some of the challenges associated with machine learned force fields include simulation stability over extended periods of time and ensuring that the statistical and dynamical properties of the underlying simulated systems are correctly captured. In this work, we propose a systematic training pipeline for such force fields that leads to improved model quality, compared to that achieved by traditional data generation and training approaches. That pipeline relies on the use of enhanced sampling techniques, and it is demonstrated here in the context of a liquid crystal, which exemplifies many of the challenges that are encountered in fluids and materials with complex free energy landscapes. Our results indicate that, whereas the majority of traditional machine learned force field training approaches lead to molecular dynamics simulations that are only stable over hundred-picosecond trajectories, our approach allows for stable simulations over tens of nanoseconds for organic molecular systems comprising thousands of atoms.
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Affiliation(s)
- Yezhi Jin
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637-1476, United States
| | - Gustavo R Perez-Lemus
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637-1476, United States
| | - Pablo F Zubieta Rico
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637-1476, United States
| | - Juan J de Pablo
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637-1476, United States
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2
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Guo JK, Wang H, Chang F, Ling J, Yuan Y, Zhang X, Wang X. Production and Reconfiguration of Double Emulsions by Temperature Control. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:13296-13302. [PMID: 37661457 DOI: 10.1021/acs.langmuir.3c01891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Double emulsions are of great importance for both science and engineering. However, the production of multicore double-emulsion droplets is challenging and normally requires sophisticated microfluidic devices, which limits their availability to broader communities. Here, we propose a simple, precise, and scalable batch method for producing double emulsions with monodispersed multicores at milliliter per minute rates, using the most common means in laboratory, temperature. By rapidly cooling liquid crystal emulsions, the introduced temperature gradient around the emulsion droplets leads to the injection of monodispersed guest droplets to form double-emulsion droplets. The number of injected water droplets can be precisely controlled by adjusting the thermally induced mechanical force through the temperature difference and the cooling rate. In contrast to conventional microfluidic fabrication, this method processes all emulsion droplets simultaneously in a noncontact and in situ manner. Therefore, it has great flexibility, allows multiple processing of double emulsions of arbitrary shape, has good capacity for mass production, and offers excellent compatibility with technologies such as microfluidics. Finally, we demonstrate that temperature changes can also be used to release the inner droplets from the double emulsion. The proposed method offers a reversible tool for processing double emulsions with minimal cost and expertise and is applicable to droplet-based microsystems in materials science, photonics, sensors, pharmaceuticals, and biotechnology.
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Affiliation(s)
- Jin-Kun Guo
- School of Optoelectronic Engineering, Xidian University, Xìan 710071, Shaanxi Province, China
| | - Haojie Wang
- School of Physics, Xidian University, Xìan 710071, Shaanxi Province, China
| | - Fengjiao Chang
- Shaanxi University of Chinese Medicine, Xìan 712046, Shaanxi Province, China
| | - Jinzhong Ling
- School of Optoelectronic Engineering, Xidian University, Xìan 710071, Shaanxi Province, China
| | - Ying Yuan
- School of Optoelectronic Engineering, Xidian University, Xìan 710071, Shaanxi Province, China
| | - Xuantao Zhang
- Dongbei University of Finance and Ecomonics, Dalian 116025, Liaoning Province, China
| | - Xiaorui Wang
- School of Optoelectronic Engineering, Xidian University, Xìan 710071, Shaanxi Province, China
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3
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Patel M, Alvarez-Fernandez A, Fornerod MJ, Radhakrishnan ANP, Taylor A, Ten Chua S, Vignolini S, Schmidt-Hansberg B, Iles A, Guldin S. Liquid Crystal-Templated Porous Microparticles via Photopolymerization of Temperature-Induced Droplets in a Binary Liquid Mixture. ACS OMEGA 2023; 8:20404-20411. [PMID: 37323413 PMCID: PMC10268013 DOI: 10.1021/acsomega.3c00490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 05/12/2023] [Indexed: 06/17/2023]
Abstract
Porous polymeric microspheres are an emerging class of materials, offering stimuli-responsive cargo uptake and release. Herein, we describe a new approach to fabricate porous microspheres based on temperature-induced droplet formation and light-induced polymerization. Microparticles were prepared by exploiting the partial miscibility of a thermotropic liquid crystal (LC) mixture composed of 4-cyano-4'-pentylbiphenyl (5CB, unreactive mesogens) with 2-methyl-1,4-phenylene bis4-[3-(acryloyloxy)propoxy] benzoate (RM257, reactive mesogens) in methanol (MeOH). Isotropic 5CB/RM257-rich droplets were generated by cooling below the binodal curve (20 °C), and the isotropic-to-nematic transition occurred after cooling below 0 °C. The resulting 5CB/RM257-rich droplets with radial configuration were subsequently polymerized under UV light, resulting in nematic microparticles. Upon heating the mixture, the 5CB mesogens underwent a nematic-isotropic transition and eventually became homogeneous with MeOH, while the polymerized RM257 preserved its radial configuration. Repeated cycles of cooling and heating resulted in swelling and shrinking of the porous microparticles. The use of a reversible materials templating approach to obtain porous microparticles provides new insights into binary liquid manipulation and potential for microparticle production.
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Affiliation(s)
- Mehzabin Patel
- Department
of Chemical Engineering, University College
London, London, WC1E 7JE, United
Kingdom
| | | | | | | | - Alaric Taylor
- Department
of Chemical Engineering, University College
London, London, WC1E 7JE, United
Kingdom
| | - Singg Ten Chua
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge, CB2 1EW, United
Kingdom
| | - Silvia Vignolini
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge, CB2 1EW, United
Kingdom
| | - Benjamin Schmidt-Hansberg
- Chemical
& Process Engineering, Coating & Film Processing, BASF SE, 67056 Ludwigshafen am Rhein, Germany
| | - Alexander Iles
- Lab-on-a-Chip
Research Group, Department of Chemistry and Biochemistry, University of Hull, Hull, HU6 7RX, United Kingdom
| | - Stefan Guldin
- Department
of Chemical Engineering, University College
London, London, WC1E 7JE, United
Kingdom
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4
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Yoshiko T, Sato D, Yamamoto T. Fibrous self-assembly of liquid crystal made by self-organisation. LIQUID CRYSTALS TODAY 2023. [DOI: 10.1080/1358314x.2022.2179827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Affiliation(s)
- Takenaka Yoshiko
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - D. Sato
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
- Department of Applied Physics, Tokyo University of Science, Tokyo, Japan
| | - T. Yamamoto
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
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5
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Patel M, Shimizu S, Bates MA, Fernandez-Nieves A, Guldin S. Long term phase separation dynamics in liquid crystal-enriched microdroplets obtained from binary fluid mixtures. SOFT MATTER 2023; 19:1017-1024. [PMID: 36647716 DOI: 10.1039/d2sm01348g] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The dynamics of long term phase separation in binary liquid mixtures remains a subject of fundamental interest. Here, we study a binary liquid mixture, where the minority phase is confined to a liquid crystal (LC)-rich droplet, by investigating the evolution of size, defect and mesogen alignment over time. We track the binary liquid mixture evolving towards equilibrium by visualising the configuration of the liquid crystal droplet through polarisation microscopy. We compare our experimental findings with computational simulations and elucidate differences between bulk phases and confined droplets based on the respective thermodynamics of phase separation. Our work provides insights on how phase transitions on the microscale can deviate from bulk phase diagrams with relevance to other material systems, such as the liquid-liquid phase separation of polymer and protein solutions.
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Affiliation(s)
- Mehzabin Patel
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
| | - Seishi Shimizu
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
| | - Martin A Bates
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
| | - Alberto Fernandez-Nieves
- Department of Condensed Matter Physics, University of Barcelona, 08028 Barcelona, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
- Institute for Complex Systems (UBICS), University of Barcelona, 08028, Barcelona, Spain
| | - Stefan Guldin
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
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Li S, Zhang H, Li W, Zhang Y, Gao X, Liu H, Li N, Hu H. Controllable Formation and Real-Time Characterization of Single Microdroplets Using Optical Tweezers. MICROMACHINES 2022; 13:1693. [PMID: 36296046 PMCID: PMC9607241 DOI: 10.3390/mi13101693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 09/24/2022] [Accepted: 10/05/2022] [Indexed: 06/16/2023]
Abstract
Existing preparation methods for microdroplets usually require offline measurements to characterize single microdroplets. Here, we report an optical method used to facilitate the controllable formation and real-time characterization of single microdroplets. The optical tweezer technique was used to capture and form a microdroplet at the center of the trap. The controllable growth and real-time characterization of the microdroplet was realized, respectively, by adjusting experimental parameters and by resolving the Raman spectra by fitting Mie scattering to the spike positions of the spectra during the controllable growth of microdroplets. The proposed method can be potentially applied in optical microlenses and virus detection.
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Affiliation(s)
- Shuai Li
- Quantum Sensing Center, Zhejiang Lab., Hangzhou 310000, China
| | - Hanlin Zhang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Wenqiang Li
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Yizhou Zhang
- Quantum Sensing Center, Zhejiang Lab., Hangzhou 310000, China
| | - Xiaowen Gao
- Quantum Sensing Center, Zhejiang Lab., Hangzhou 310000, China
| | - Haiqing Liu
- Isvision (Hangzhou) Technology Co., Ltd., Hangzhou 310052, China
| | - Nan Li
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Huizhu Hu
- Quantum Sensing Center, Zhejiang Lab., Hangzhou 310000, China
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
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7
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Dhara P, Mukherjee R. Phase separation and dewetting of polymer dispersed liquid crystal (PDLC) thin films on flat and patterned substrates. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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8
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Cao E, Radhakrishnan ANP, Hasanudin RB, Gavriilidis A. Study of Liquid-Solid Mass Transfer and Hydrodynamics in Micropacked Bed with Gas-Liquid Flow. Ind Eng Chem Res 2021; 60:10489-10501. [PMID: 34349342 PMCID: PMC8323102 DOI: 10.1021/acs.iecr.1c00089] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 11/29/2022]
Abstract
![]()
The
volumetric liquid–solid (L-S) mass transfer coefficient
under gas–liquid (G-L) two-phase flow in a silicon-chip-based
micropacked bed reactor (MPBR) was studied using the copper dissolution
method and was related to the reactor hydrodynamic behavior. Using
a high-speed camera and a robust computational image analysis method
that selectively analyzed the bed voidage around the copper particles,
the observed hydrodynamics were directly related to the L-S mass transfer
rates in the MPBR. This hydrodynamic study revealed different pulsing
structures inside the packed copper bed depending on the flow patterns
established preceding the packed bed upon increasing gas velocity.
A “liquid-dominated slug” flow regime was associated
with an upstream slug flow feed. A “sparse slug” flow
regime developed with an upstream slug-annular flow feed. At higher
gas velocity, a “gas continuous with pulsing” regime
developed with an annular flow feed, which had similar features to
the pulsing flow in macroscale packed beds, but it was sensitive and
easily destabilized by disturbances from upstream or downstream pressure
fluctuations. The volumetric L-S mass transfer coefficient decreased
with increasing gas velocity under the liquid-dominated slug flow
regime and became rather less affected under the sparse slug flow
regime. By resolving the transition from the liquid-dominated slug
flow to the sparse slug flow and capturing the onset of the gas-continuous
with pulsing regime, we gained new insights into the hydrodynamic
effects of G-L flows on the L-S mass transfer rates in a MPBR.
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Affiliation(s)
- Enhong Cao
- Department of Chemical Engineering, University College London, London WC1E 7JE United Kingdom
| | - Anand N P Radhakrishnan
- Department of Chemical Engineering, University College London, London WC1E 7JE United Kingdom
| | - Redza Bin Hasanudin
- Department of Chemical Engineering, University College London, London WC1E 7JE United Kingdom
| | - Asterios Gavriilidis
- Department of Chemical Engineering, University College London, London WC1E 7JE United Kingdom
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