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Length-based separation of Bacillus subtilis bacterial populations by viscoelastic microfluidics

Microsystems & Nanoengineering 2022年第1期8卷 149-159页

作者： Ping Liu Hangrui Liu Lucie Semenec Dan Yuan Sheng Yan Amy K.Cain Ming Li Suqian University Suqian 223800China School of Engineering Macquarie UniversitySydneyNSW 2109Australia Department of Physics and Astronomy Macquarie UniversitySydneyNSW 2109Australia ARC Centre of Excellence in Synthetic Biology Department of Molecular ScienceMacquarie UniversitySydneyNSW 2109Australia Centre for Regional and Rural Futures Deakin UniversityGeelongVIC 3216Australia Institute for Advanced Study Shenzhen UniversityShenzhen 518060China Biomolecular Discovery Research Centre Macquarie UniversitySydneyNSW 2109Australia

In this study,we demonstrated the label-free continuous separation and enrichment of Bacillus subtilis populations based on length using viscoelastic microfluidics.B.subtilis,a gram-positive,rod-shaped bacterium,has been widely used as a model organism and an industrial workhorse.B.subtilis can be arranged in different morphological forms,such as single rods,chains,and clumps,which reflect differences in cell types,phases of growth,genetic variation,and changing environmental factors.The ability to prepare B.subtilis populations with a uniform length is important for basic biological studies and efficient industrial applications.Here,we systematically investigated how flow rate ratio,poly(ethylene oxide)(PEO)concentration,and channel length affected the length-based separation of B.subtilis cells.The lateral positions of B.subtilis cells with varying morphologies in a straight rectangular microchannel were found to be dependent on cell length under the co-flow of viscoelastic and Newtonian fluids.Finally,we evaluated the ability of the viscoelastic microfluidic device to separate the two groups of B.subtilis cells by length(i.e.,1-5μm and>5μm)in terms of extraction purity(EP),extraction yield(EY),and enrichment factor(EF)and confirmed that the device could separate heterogeneous populations of bacteria using elasto-inertial effects.

关键词： viscoelastic separation straight

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A Thermochromic, viscoelastic Nacre-like Nanocomposite for the Smart Thermal Management of Planar Electronics

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Nano-Micro Letters 2023年第10期15卷 182-196页

作者： Jiemin Wang Tairan Yang Zequn Wang Xuhui Sun Meng An Dan Liu Changsheng Zhao Gang Zhang Weiwei Lei College of Biomedical Engineering Sichuan UniversityChengdu 610064People’s Republic of China Institute for Frontier Materials Deakin UniversityWaurn Ponds CampusLocked Bag 20000GeelongVictoria 3220Australia College of Mechanical and Electrical Engineering Shaanxi University of Science and TechnologyXi’an 710021People’s Republic of China State Key Laboratory of Polymer Materials Engineering College of Polymer Science and EngineeringSichuan UniversityChengdu 610065People’s Republic of China Institute of High Performance Computing A*STAR Singapore 138632Singapore

Cutting-edge heat spreaders for soft and planar electronics require not only high thermal conductivity and a certain degree of flexibility but also remarkable self-adhesion without thermal interface materials, elasticity, arbitrary elongation along with soft devices, and smart properties involving thermal self-healing, thermochromism and so on. Nacre-like composites with excellent in-plane heat dissipation are ideal as heat spreaders for thin and planar electronics. However, the intrinsically poor viscoelasticity, i.e., adhesion and elasticity, prevents them from simultaneous self-adhesion and arbitrary elongation along with current flexible devices as well as incurring high interfacial thermal impedance. In this paper, we propose a soft thermochromic composite(STC) membrane with a layered structure, considerable stretchability, high in-plane thermal conductivity(~30 Wm^(-1) K^(-1)), low thermal contact resistance(~12 mm^2 KW^(-1), 4–5 times lower than that of silver paste), strong yet sustainable adhesion forces(~4607 Jm^(-2), 2220 Jm^(-2) greater than that of epoxy paste) and self-healing efficiency. As a self-adhesive heat spreader, it implements efficient cooling of various soft electronics with a temperature drop of 20℃ than the polyimide case. In addition to its self-healing function, the chameleon-like behavior of STC facilitates temperature monitoring by the naked eye, hence enabling smart thermal management.

关键词： Boron nitride nanosheets Nacre-inspired composites viscoelastic Thermochromic Smart thermal management

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On the Dynamics of a viscoelastic Fluid-Conveying Nanotube

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Fluid Dynamics & Materials Processing 2022年第4期18卷 1137-1151页

作者： Ola Adil Ibrahim Gunawan Widjaja Abdulhussien N.Alattabi Krishanveer Singh Yasser Fakri Mustafa P.A.Krovopuskov Mustafa M.Kadhim General Directorate of Curricula-Ministry of Education-Iraq Baghdad10020Iraq Senior Lecturer Faculty of Public Health Universitas Indonesia/Faculty of Law Universitas Krisnadwipayana Jakarta11440Indonesia College of Petroleum Engineering Al-Ayen UniversityThi-Qar64005Iraq GLA University Mathura-India MathuraChaumuhanUttar Pradesh281406India Department of Pharmaceutical Chemistry College of PharmacyUniversity of MosulMosul41002Iraq Lipetsk State Technical University Lipetsk398600Russia Department of Dentistry Kut University CollegeKutWasit52001Iraq

The objective of the presented study is to perform a vibration analysis and investigate the stability of a viscoelastic-fluid conveying pipe with an intermediate support.The mathematical model is elaborated in the framework of the Euler-Bernoulli beam theory in combination with the Kelvin-Voight viscoelastic approach.The resulting differential equation of motion and the related boundary conditions and compatibility conditions in the mid-span support are solved analytically using a power series method.The results show that an intermediate support located atξ_(s)=0.1 andξ_(s)=0.5 increases the critical velocity up to 35%and 50.15%,respectively.Also,the non-dimensional critical velocity for an intermediate support atξ_(s)=0.1 is 4.83.

关键词： Fluid conveying carbon nanotube viscoelastic structural damping natural frequencies analytical method

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viscoelastic analysis of single-component and composite PEG and alginate hydrogels

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Acta Mechanica Sinica 2014年第1期30卷 7-14页

作者： Jenna M.Shapiro Michelle L.Oyen Cambridge University Engineering Department CambridgeUK Eunice Kennedy Shriver National Institute of Child Health and Human Development National Institutes of Health

Hydrogels, three-dimensional hydrophilic polymer networks, are appealing candidate materials for study- ing the cellular microenvironment as their substantial water content helps to better mimic soft tissue. However, hydrogels can lack mechanical stiffness, strength, and tough- ness. Composite hydrogel systems have been shown to improve upon mechanical properties compared to their single- component counterparts. Poly （ethylene glycol） dimethacrylate （PEGDMA） and alginate are polymers that have been used to form hydrogels for biological applications. Single- component and composite PEGDMA and alginate systems were fabricated with a range of total polymer concentrations. Bulk gels were mechanically characterized using spherical indentation testing and a viscoelastic analysis framework. An increase in shear modulus with increasing polymer con- centration was demonstrated for all systems. Alginate hydro- gels were shown to have a smaller viscoelastic ratio than the PEGDMA gels, indicating more extensive relaxation over time. Composite alginate and PEGDMA hydrogels exhib- ited a combination of the mechanical properties of the con- stituents, as well as a qualitative increase in toughness. Additionally, multiple hydrogel systems were produced that had similar shear moduli, but different viscoelastic behaviors. Accurate measurement of the mechanical properties of hydrogels is necessary in order to determine what parameters are key in modeling the cellular microenvironment.

关键词： Hydrogel viscoelastic Indentation Nanoin-dentation Composite

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Evolution of focused streams for viscoelastic flow in spiral microchannels

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微系统与纳米工程(英文) 2023年第3期9卷 129-143页

作者： Hua Gao Jian Zhou Mohammad Moein Naderi Zhangli Peng Ian Papautsky Department of Biomedical Engineering University of Illinois ChicagoChicagoIL 60607USA

Particle migration dynamics in viscoelastic fluids in spiral channels have attracted interest in recent years due to potential applications in the 3D focusing and label-free sorting of particles and cells.Despite a number of recent studies,the underlying mechanism of Dean-coupled elasto-inertial migration in spiral microchannels is not fully understood.In this work,for the first time,we experimentally demonstrate the evolution of particle focusing behavior along a channel downstream length at a high blockage ratio.We found that flow rate,device curvature,and medium viscosity play important roles in particle lateral migration.Our results illustrate the full focusing pattern along the downstream channel length,with side-view imaging yielding observations on the vertical migration of focused streams.Ultimately,we anticipate that these results will offer a useful guide for elasto-inertial microfluidics device design to improve the efficiency of 3D focusing in cell sorting and cytometry applications.

关键词： viscoelastic flow curvature

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Propagation characteristics of low-frequency axisymmetric waves in fluid-filled pipes embedded in the viscoelastic medium

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Chinese Journal of Acoustics 2022年第3期41卷 221-237页

作者： QIAN Jiawen HAN Qingbang SU Nana BAI Le QIAN Xintong College of IOT Engineering of Hohai University Changzhou 213022

The propagation characteristics of the low-frequency axisymmetric waves in buried fluid-filled pipes are investigated theoretically,based on the Kennard thin-walled shell equations,the Helmholtz equation,and the Kelvin-Voigt linear viscoelastic model.Analytic expressions of the phase velocity are derived for both the fluid-dominated wave and the shell-compressed wave under lubricated contact,via considering the surrounding soil as a viscoelastic medium.The dispersion and attenuation curves of the two wave types are obtained and verified numerically.The ratio of the radial pipe wall displacements is analyzed,with particular emphasis on the effects of the thickness-to-radius ratio and the quality factor on the dispersion and attenuation characteristics of the fluid-dominated wave.The results show that the viscoelastic property has slight effects on the phase velocities of the two wave types,but it influences the attenuation severely.The fluid-dominated wave influences the radial pipe wall displacement significantly and is the primary carrier of leakage noise energy;its phase velocity increases as a function of the thickness-to-radius ratio while the attenuation decreases.It also shows that the dispersion and attenuation of the fluid-dominated wave decrease as a function of the quality factor.The work will provide insights and guidance for the leakage detection of buried fluid-filled pipes.

关键词： wave viscoelastic filled

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Precise Integration Method of C-integral for Linear viscoelastic Solids with Crack

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上海交通大学学报 2004年第Z2期38卷 25-31页

作者： Liu Jinghua Wu Changchun Huang Ruoyu School of Naval Arch. Ocean & Civil Engineering Shanghai Jiaotong Univ. Shanghai200030 China School of Naval Arch. Ocean & Civil Engineering Shanghai Jiaotong Univ. Shanghai200030 China School of Naval Arch. Ocean & Civil Engineering Shanghai Jiaotong Univ. Shanghai200030 China

Generally, viscoelastic solid constitutive equation can be written into differential form and integral form. From differential form of constitutive equation the mathematical representation of the state space equation can be derived. Due to the state space equation, general constitutive equation can be solved by precise integration method that can be used in many fields with the advantages of highly precision and convenience. For linear viscoelastic solids with crack, the finite elements program of the precise integration method for viscoelastic solid is developed, which appears to be efficient and precise. C-integral is used to be the characterising parameter.

关键词： precise integration C-integral viscoelastic finite element

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2D Q-compensated multi-component elastic Gaussian beam migration

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Petroleum Science 2023年第1期20卷 230-240页

作者： Chao Chen Ji-Dong Yang Xin-Ru Mu Zhen-Chun Li Jian-Ping Huang China University of Petroleum(East China) Qingdao266580ShandongChina

Elastic waves are affected by viscoelasticity during the propagation through the Earth,resulting in energy attenuation and phase distortion,in turn resulting in low seismic imaging accuracy.Therefore,viscoelasticity should be considered in seismic migration imaging.We propose a Q compensated multicomponent elastic Gaussian beam migration(Q-EGBM)method to(1)separate the elastic-wave data into longitudinal(P)and transverse(S)waves to perform PP-wave and PS-wave imaging;(2)recover the amplitude loss caused by attenuation;(3)correct phase distortions caused by dispersion;(4)improve the resolution of migration imaging.In this paper,to accomplish(2),(3),and(4),we derive complex-valued traveltimes in viscoelastic media.The results of numerical experiments using a simple five-layer model and a sophisticated BP gas model show that the method presented here has significant advantages in recovering energy decay and correcting phase distortion,as well as significantly improving imaging resolution.

关键词： Q-compensated viscoelastic Gaussian beam migration Multi-component Absorption attenuation

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Flow of a viscoelastic Fluid through a Porous Channel with Expanding or Contracting Walls

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Chinese Physics Letters 2011年第4期28卷 133-136页

作者：司新辉郑连存张欣欣司新毅阳建宏 Department of Mathematics and Mechanics University of Science and Technology BeijingBeijing 100083 Department of Mechanical Engineering University of Science and Technology BeijingBeijing 100083 College of Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098

The flow of a viscoelastic fluid in porous channels with expanding or contracting walls is investigated.Using a similar transformation,the governing equations are reduced to a nonlinear fifth-order differential equation.The homotopy analysis method is employed to obtain the expression for velocity fields.The analytical solutions are influenced by the permeation Reynolds number Re,the wall expansion ratio a and viscoelastic parameter w.Graphs are sketched and the effects of some values of parameters,especially the expansion ratio,on the velocity fields are discussed in detail.

关键词： equation viscoelastic expansion

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Identifying the viscoelastic properties of soft matter from the indentation response of a hard film-soft substrate system

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Science China(Physics,Mechanics & Astronomy) 2020年第4期63卷 108-118页

作者： YanWei Liu YueGuang Wei Hao Long Department of Mechanics and Engineering Science College of EngineeringPeking UniversityBeijing 100871China

The indentation technique is widely used in measuring the mechanical properties of soft matter at the microscale or nanoscale,but still faces challenges by these unique properties as well as the consequent strong surface adhesion, including the strong nonlinear effect, unclear judgment of the contact point, difficulties in estimating the contact area, and the risk of the indenter piercing the sample. Here we propose a two-step method to solve these problems: lay a hard film on a soft matter, and obtain the viscoelastic properties of this soft matter through the indentation response of this composite structure. We first establish a theoretical indentation model of the hard film-soft substrate system based on the theory of plates, elastic-viscoelastic correspondence principle and Boltzmann superposition principle. To verify the correctness of this method, we measure the mechanical properties of the methyl vinyl silicone rubber(MVSR) covered by a Cu nanofilm. Finally, we test the effectiveness and error sensitivity of this method with the finite element method(FEM). The results show that our method can accurately measure the mechanical properties of soft matter, while effectively circumventing the problems of the traditional indentation technique.

关键词： viscoelastic properties soft matter theoretical indentation model indentation technique finite element method

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