Jetting-based bioprinting:process,dispense physics,and applications

Jetting-based bioprinting facilitates contactless drop-on-demand deposition of subnanoliter droplets at well-defined positions to control the spatial arrangement of cells,growth factors,drugs,and biomaterials in a highly automated layer-by-layer fabrication approach.Due to its immense versatility,jetting-based bioprinting has been used for various applications,including tissue engineering and regenerative medicine,wound healing,and drug development.A lack of in-depth understanding exists in the processes that occur during jetting-based bioprinting.This review paper will comprehensively discuss the physical considerations for bioinks and printing conditions used in jetting-based bioprinting.We first present an overview of different jetting-based bioprinting techniques such as inkjet bioprinting,laser-induced forward transfer bioprinting,electrohydrodynamic jet bioprinting,acoustic bioprinting and microvalve bioprinting.Next,we provide an in-depth discussion of various considerations for bioink formulation relating to cell deposition,print chamber design,droplet formation and droplet impact.Finally,we highlight recent accomplishments in jetting-based bioprinting.We present the advantages and challenges of each method,discuss considerations relating to cell viability and protein stability,and conclude by providing insights into future directions of jetting-based bioprinting.

A novel encoding mechanism for particle physics

This study proposes a novel particle encoding mechanism that seamlessly incorporates the quantum properties of particles,with a specific emphasis on constituent quarks.The primary objective of this mechanism is to facilitate the digital registration and identification of a wide range of particle information.Its design ensures easy integration with different event generators and digital simulations commonly used in high-energy experiments.Moreover,this innovative framework can be easily expanded to encode complex multi-quark states comprising up to nine valence quarks and accommodating an angular momentum of up to 99/2.This versatility and scalability make it a valuable tool.

Exploring device physics of perovskite solar cell via machine learning with limited samples

Perovskite solar cells(PsCs)have developed tremendously over the past decade.However,the key factors influencing the power conversion efficiency(PCE)of PSCs remain incompletely understood,due to the complexity and coupling of these structural and compositional parameters.In this research,we demon-strate an effective approach to optimize PSCs performance via machine learning(ML).To address chal-lenges posed by limited samples,we propose a feature mask(FM)method,which augments training samples through feature transformation rather than synthetic data.Using this approach,squeeze-and-excitation residual network(SEResNet)model achieves an accuracy with a root-mean-square-error(RMSE)of 0.833%and a Pearson's correlation coefficient(r)of 0.980.Furthermore,we employ the permu-tation importance(PI)algorithm to investigate key features for PCE.Subsequently,we predict PCE through high-throughput screenings,in which we study the relationship between PCE and chemical com-positions.After that,we conduct experiments to validate the consistency between predicted results by ML and experimental results.In this work,ML demonstrates the capability to predict device performance,extract key parameters from complex systems,and accelerate the transition from laboratory findings to commercialapplications.

Ultrafast photoemission electron microscopy:A multidimensional probe of nonequilibrium physics

Exploring the realms of physics that extend beyond thermal equilibrium has emerged as a crucial branch of condensed matter physics research.It aims to unravel the intricate processes involving the excitations,interactions,and annihilations of quasi-and many-body particles,and ultimately to achieve the manipulation and engineering of exotic non-equilibrium quantum phases on the ultrasmall and ultrafast spatiotemporal scales.Given the inherent complexities arising from many-body dynamics,it therefore seeks a technique that has efficient and diverse detection degrees of freedom to study the underlying physics.By combining high-power femtosecond lasers with real-or momentum-space photoemission electron microscopy(PEEM),imaging excited state phenomena from multiple perspectives,including time,real space,energy,momentum,and spin,can be conveniently achieved,making it a unique technique in studying physics out of equilibrium.In this context,we overview the working principle and technical advances of the PEEM apparatus and the related laser systems,and survey key excited-state phenomena probed through this surface-sensitive methodology,including the ultrafast dynamics of electrons,excitons,plasmons,spins,etc.,in materials ranging from bulk and nano-structured metals and semiconductors to low-dimensional quantum materials.Through this review,one can further envision that time-resolved PEEM will open new avenues for investigating a variety of classical and quantum phenomena in a multidimensional parameter space,offering unprecedented and comprehensive insights into important questions in the field of condensed matter physics.

Physics-based seismic analysis of ancient wood structure:fault-to-structure simulation

Based on the domain reduction method,this study employs an SEM-FEM hybrid workflow which integrates the advantages of the spectral element method(SEM)for flexible and highly efficient simulation of seismic wave propagation in a three-dimensional(3D)regional-scale geophysics model and the finite element method(FEM)for fine simulation of structural response including soil-structure interaction,and performs a physics-based simulation from initial fault rupture on an ancient wood structure.After verification of the hybrid workflow,a large-scale model of an ancient wood structure in the Beijing area,The Tower of Buddhist Incense,is established and its responses under the 1665 Tongxian earthquake and the 1730 Yiheyuan earthquake are simulated.The results from the simulated ground motion and seismic response of the wood structure under the two earthquakes demonstrate that this hybrid workflow can be employed to efficiently provide insight into the relationships between geophysical parameters and the structural response,and is of great significance toward accurate input for seismic simulation of structures under specific site and fault conditions.

基于Interactive Physics的物理习题教学--以2023年高考全国乙卷25题和湖北卷15题为例

在传统高中物理教学中,多过程碰撞的物理过程很难在板书上展现出来,成为教学的一大难点。基于Interactive Physics仿真功能,以2023年高考全国乙卷25题和湖北卷15题为例,将多过程碰撞的物理过程可视化,直观展现物理模型,帮助学生理解题目的复杂情境,有效缩短学习时间,提高教学质量和教学效率,实现最优化的教学目标。

Tensile Shock Physics in Compressible Thermoviscoelastic Solid Medium

This paper addresses tensile shock physics in thermoviscoelastic (TVE) solids without memory. The mathematical model is derived using conservation and balance laws (CBL) of classical continuum mechanics (CCM), incorporating the contravariant second Piola-Kirchhoff stress tensor, the covariant Green’s strain tensor, and its rates up to order n. This mathematical model permits the study of finite deformation and finite strain compressible deformation physics with an ordered rate dissipation mechanism. Constitutive theories are derived using conjugate pairs in entropy inequality and the representation theorem. The resulting mathematical model is both thermodynamically and mathematically consistent and has closure. The solution of the initial value problems (IVPs) describing evolutions is obtained using a variationally consistent space-time coupled finite element method, derived using space-time residual functional in which the local approximations are in hpk higher-order scalar product spaces. This permits accurate description problem physics over the discretization and also permits precise a posteriori computation of the space-time residual functional, an accurate measure of the accuracy of the computed solution. Model problem studies are presented to demonstrate tensile shock formation, propagation, reflection, and interaction. A unique feature of this research is that tensile shocks can only exist in solid matter, as their existence requires a medium to be elastic (presence of strain), which is only possible in a solid medium. In tensile shock physics, a decrease in the density of the medium caused by tensile waves leads to shock formation ahead of the wave. In contrast, in compressive shocks, an increase in density and the corresponding compressive waves result in the formation of compression shocks behind of the wave. Although these are two similar phenomena, they are inherently different in nature. To our knowledge, this work has not been reported in the published literature.

Design and Research of an Intelligent Learning System for University Physics

In order to break through the limitations of traditional teaching,realize the integration of online and offline teaching,and optimize the intelligent learning experience of university physics,this paper proposes the design of an intelligent learning system for university physics based on cloud computing platforms,and applies this system to teaching environment of university physics.It successfully integrates emerging technologies such as cloud computing,machine learning,and situational awareness,integrates learning context awareness,intelligent recording and broadcasting,resource sharing,learning performance prediction,and content planning and recommendation,and comprehensively improves the quality of university physics teaching.It can optimize the teaching process and deepen intelligent teaching reform,aiming at providing references for the teaching practice of university physics.

Reform and Practice of University Physics Experimental Teaching Based on OBE Concept

Aiming at the problems of unclear teaching objectives,obsolete content,and single method in the experimental teaching of university physics at our university,we have implemented a series of reform initiatives.It mainly includes clarifying the student-centered teaching objectives,optimizing the experimental content,innovating the teaching methods,improving the assessment and evaluation system,and improving the experimental conditions[1,2].After the implementation of the reform,the learning effectiveness of students has been significantly improved,the teaching level of teachers has been significantly enhanced,the curriculum system has been optimized,the efficiency of teaching management has been enhanced,and social recognition has been strengthened.Practice shows that the teaching reform based on the outcome-based education concept effectively improves the quality of university physics experimental teaching and lays the foundation for cultivating innovative talents.

Integration of Ideological and Political Education in College Physics Courses Under the Reform of Smart Teaching

The development of the times has prompted China to enhance the quality of education and the value of talent.As guides for students,teachers should conscientiously implement ideological and political education,create college physics courses that are more in line with modern talent cultivation,eliminate the fixed and singular nature of traditional teaching,and find the integration points of ideological and political education.Teachers need to use the textbook itself,the expansion of resources in smart classrooms,and current technological progress to implement ideological and political education in order to cultivate more high-quality and high-level comprehensive talents for society.

Rock physics modeling of heterogeneous carbonatereservoirs： porosity estimation and hydrocarbon detection

In heterogeneous natural gas reservoirs, gas is generally present as small patchlike pockets embedded in the water-saturated host matrix. This type of heterogeneity, also called "patchy saturation", causes significant seismic velocity dispersion and attenuation. To establish the relation between seismic response and type of fluids, we designed a rock physics model for carbonates. First, we performed CT scanning and analysis of the fluid distribution in the partially saturated rocks. Then, we predicted the quantitative relation between the wave response at different frequency ranges and the basic lithological properties and pore fluids. A rock physics template was constructed based on thin section analysis of pore structures and seismic inversion. This approach was applied to the limestone gas reservoirs of the right bank block of the Amu Darya River. Based on poststack wave impedance and prestack elastic parameter inversions, the seismic data were used to estimate rock porosity and gas saturation. The model results were in good agreement with the production regime of the wells.

Research on anisotropy of shale oil reservoir based on rock physics model

Rock physics modeling is implemented for shales in the Luojia area of the Zhanhua topographic depression. In the rock physics model, the clay lamination parameter is introduced into the Backus averaging theory for the description of anisotropy related to the preferred alignment of clay particles, and the Chapman multi-scale fracture theory is used to calculate anisotropy relating to the fracture system. In accordance with geological features of shales in the study area, horizontal fractures are regarded as the dominant factor in the prediction of fracture density and anisotropy parameters for the inversion scheme. Results indicate that the horizontal fracture density obtained has good agreement with horizontal permeability measured from cores, and thus confirms the applicability of the proposed rock physics model and inversion method. Fracture density can thus be regarded as an indicator of reservoir permeability. In addition, the anisotropy parameter of the P-wave is higher than that of the S-wave due to the presence of horizontal fractures. Fracture density has an obvious positive correlation with P-wave anisotropy, and the clay content shows a positive correlation with S-wave anisotropy, which fully shows that fracture density has a negative correlation with clay and quartz contents and a positive relation with carbonate contents.

Anisotropy rock physics model for the Longmaxi shale gas reservoir,Sichuan Basin,China

The preferred orientation of clay minerals dominates the intrinsic anisotropy of shale. We introduce the clay lamination （CL） parameter to the Backus averaging method to describe the intrinsic shale anisotropy induced by the alignment of clay minerals. Then, we perform the inversion of CL and the Thomsen anisotropy parameters. The direct measurement of anisotropy is difficult because of the inability to measure the acoustic velocity in the vertical direction in boreholes and instrument limitations. By introducing the parameter CL, the inversion method provides reasonable estimates of the elastic anisotropy in the Longmaxi shale. The clay content is weakly correlated with the CL parameter. Moreover, the parameter CL is abnormally high at the bottom of the Longmaxi and Wufeng Formations, which are the target reservoirs. Finally, we construct rock physics templates to interpret well logging and reservoir properties.

工作室课堂与大学物理教育——介绍美国Studio Physics教学模式

详细介绍了美国工作室物理(Studio Physics)教学模式.这一教学模式已经在包括麻省理工学院(MIT)等美国大学广泛使用.工作室物理完全整合了理论和实验课堂,充分发挥学生自主学习的积极性.实践证明,工作室物理不仅培养了学生探索物理知识的能力,还全面培养了学生在集体环境中自我学习、自我成长、自我完善的能力.由于工作室物理的成功,美国一些大学已经开始在化学、工程类课程中实施工作室教学模式.

《Six Ideas that Shaped Physics》以及其课程实践——以华盛顿大学“物理学导论”的教学为例

为世界各地100多所高等院校所使用的《Six Ideas》(全称《Six Ideas that Shaped Physics》)一书,以在物理学发展的历史长河中有着不可替代地位的6大物理思想为主线改变了以力学、热学、电磁学、光学等传统物理的编排模式.《Six Ideas》的每一卷均按照历史发展的故事线索展开,强调概念和定律的内在思想和应用条件,范题注重用文字或图形转译问题等框架模式;每一单元的内容编排不仅适合学生自学,同时为教师50分钟课堂教学量身定制;是适合学生"主动学习"教学模式可操作性极强的一本难得的物理学导论教材.本篇以此书为教科书的美国华盛顿大学关于E卷第九单元课堂教学案例,展示关于此书的教与学.

Analysis of rock physics response of gas-bearing volcanic reservoir based on three-phase poroelastic theory

Unlike previous theories with velocity and/or elastic modulus averaging, we use a three-phase porous rock physics model developed by Santos for analyzing the seismic response of two immiscible fluids in saturated porous media. Considering reservoir reference pressure and coupling drag of two fluids in pores, the effects of frequency, porosity, and gas saturation on the phase velocities of the P-and S-waves are discussed in detail under field conditions. The effects of porosity and gas saturation on Vp/Vs are also provided. The data for our numerical experiments are from a sample of deep volcanic rock from Daqing. The numerical results show that the frequency dispersion effect can be ignored for deep volcanic rocks with low porosity and low permeability. It is concluded that for deep volcanic rocks the effect of gas content in pores on Vp/Vs is negligible but the effect of porosity is significant when there is a certain amount of water contained in the pores. The accurate estimate of lithology and porosity in this case is relatively more important.

Gas sand distribution prediction by prestack elastic inversion based on rock physics modeling and analysis

Seismic inversion is one of the most widely used technologies for reservoir prediction. Many good results have been obtained but sometimes it fails to differentiate the lithologies and identify the fluids. However, seismic prestack elastic inversion based on rock physics modeling and analysis introduced in this paper is a significant method that can help seismic inversion and interpretation reach a new quantitative （or semi-quantitative） level from traditional qualitative interpretation. By doing rock physics modeling and forward perturbation analysis, we can quantitatively analyze the essential relationships between rock properties and seismic responses and try to find the sensitive elastic properties to the lithology, porosity, fluid type, and reservoir saturation. Finally, standard rock physics templates （RPT） can be built for specific reservoirs to guide seismic inversion interpretation results for reservoir characterization and fluids identification purpose. The gas sand distribution results of the case study in this paper proves that this method has unparalleled advantages over traditional post-stack methods, by which we can perform reservoir characterization and seismic data interpretation more quantitatively and efficiently.

Anisotropic rock physics models for interpreting pore structures in carbonate reservoirs

We developed an anisotropic effective theoretical model for modeling the elastic behavior of anisotropic carbonate reservoirs by combining the anisotropic self-consistent approximation and differential effective medium models.By analyzing the measured data from carbonate samples in the TL area,a carbonate pore-structure model for estimating the elastic parameters of carbonate rocks is proposed,which is a prerequisite in the analysis of carbonate reservoirs.A workflow for determining elastic properties of carbonate reservoirs is established in terms of the anisotropic effective theoretical model and the pore-structure model.We performed numerical experiments and compared the theoretical prediction and measured data.The result of the comparison suggests that the proposed anisotropic effective theoretical model can account for the relation between velocity and porosity in carbonate reservoirs.The model forms the basis for developing new tools for predicting and evaluating the properties of carbonate reservoirs.

原版教材Funda mentals of Physics使用体会

Halliday Resnick的基础物理学Fundamentals ofPhysics至2001年已经出了第六版.

Nonequilibrium Statistical Physics Subject to the Anomalous Langevin Equation in Liouville Space

Considering that thermodynarmic irreversibility and hydrodynamic equations can not be derived rigorously and unifiedly from the Liouville equations, the anomalous Langevin equation in the Liouville space is proposed as a fundamental equation of statistical physics. This equation reflects that the law of motion of particles obeying reversible, deterministic laws in dynamics becomes irreversible and stochastic in thermodynamics. From this the fundamental equations of nonequilibrium thermodynamics, the principle of entropy increase and the theorem of minimum entropy production have been derived. The hydrodynamic equations, such as the generalized Navier-Stokes equation and the mass drift-diffusion equation etc. have been derived rigorously from the kinetic kinetic equation which is reduced from the anomalous Langevin equation in Liouville space. All these are unified and self consistent. But it is difficult to prove that entropy production density σ can never be negative everywhere for all the isolated inhomogeneous systems far from equilibrium.