The cell microenvironment has emerged as a key determinant of cell behavior and function in development, physiology, and pathophysiology. The extracellular matrix (ECM) within the cell microenvironment serves not only as a structural foundation for cells but also as a source of three-dimensional (3D) biochemical and biophysical cues that trigger and regulate cell behaviors. Increasing evidence suggests that the 3D character of the microenvironment is required for development of many critical cell responses observed in vivo, fueling a surge in the development of functional and biomimetic materials for engineering the 3D cell microenvironment. Progress in the design of such materials has improved control of cell behaviors in 3D and advanced the fields of tissue regeneration, in vitro tissue models, large-scale cell differentiation, immunotherapy, and gene therapy. However, the field is still in its infancy, and discoveries about the nature of cell–microenvironment interactions continue to overturn much earl...

Functional and Biomimetic Materials for Engineering of the Three-Dimensional Cell Microenvironment

Physical Biology of the Cell, 2nd Edition, is a textbook that focuses on the application of physical principles to understanding biological systems. The subject matter of the text is organized according to common physical principles that govern biological processes rather than in relation to the biological processes themselves, as is common for most biology and cell biology textbooks. Topics covered in the book span a broad range of interests, including electrostatics, molecular interactions, molecular motors and the cytoskeleton, and membranes. Each chapter features color figures, derived equations with relevant examples, and problem sets at the chapter’s conclusion. The problem sets at the end of the chapters are expanded from the first edition. Further, the second edition includes two new chapters, one on light and pattern formation, and another on the use of computation in exploring biological problems. Additional student and instructor resources are also available online.

The primary audience for the textbook could include advanced undergraduate students or first-year graduate students. While the textbook may be best suited for a biophysics course, it could also be used as a primary or supplementary text for teaching cellular and molecular biology. As a teaching tool for cellular and molecular biology, the many examples featured throughout the text could easily be employed to assist students in learning the principles of how a cellular or molecular system functions. A basic level of mathematical proficiency would be required of the student. While this textbook could be an excellent resource for many courses, there are several topics commonly covered in biochemistry classes, such the glycolytic pathway, that are featured in the book but in different contexts than many widely used biochemistry texts. For a biophysics course that is heavily focused on techniques, individual references that discuss the specific techniques in detail would be more suitable than this book. Of course, any instructor seeking to use this textbook should be aware of its content before making a selection.

This textbook is an excellent resource, both for a research scientist and for a teacher. The authors do a superb job of selecting the material for each chapter and explaining the material with equations and narrative in an easily digestible manner. Readers who enjoy this book may also enjoy Molecular Driving Forces by Dill and Bromberg, which gives excellent treatment of similar concepts.

Physical Biology of the Cell

Bioinspired engineering of honeycomb structure – Using nature to inspire human innovation

Porous materials for sound absorption

Phononic crystals (PCs) and metamaterials (MMs) can exhibit abnormal properties, even far beyond those found in nature, through artificial design of the topology or ordered structure of unit cells. This emerging class of materials has diverse application potentials in many fields. Recently, the concept of tunable PCs or MMs has been proposed to manipulate a variety of wave functions on demand. In this review, we survey recent developments in tunable and active PCs and MMs, including bandgap and bandgap engineering, anomalous behaviors of wave propagation, as well as tunable manipulation of waves based on different regulation mechanisms: tunable mechanical reconfiguration and materials with multifield coupling. We conclude by outlining future directions in the emerging field.

Tunable and Active Phononic Crystals and Metamaterials

A hybrid acoustic metamaterial is proposed as a new class of sound absorber, which exhibits superior broadband low-frequency sound absorption as well as excellent mechanical stiffness/strength. Based on the honeycomb-corrugation hybrid core (H-C hybrid core), we introduce perforations on both top facesheet and corrugation, forming perforated honeycomb-corrugation hybrid (PHCH) to gain super broadband low-frequency sound absorption. Applying the theory of micro-perforated panel (MPP), we establish a theoretical method to calculate the sound absorption coefficient of this new kind of metamaterial. Perfect sound absorption is found at just a few hundreds hertz with two-octave 0.5 absorption bandwidth. To verify this model, a finite element model is developed to calculate the absorption coefficient and analyze the viscous-thermal energy dissipation. It is found that viscous energy dissipation at perforation regions dominates the total energy consumed. This new kind of acoustic metamaterials show promising engineering applications, which can serve as multiple functional materials with extraordinary low-frequency sound absorption, excellent stiffness/strength and impact energy absorption.

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Hybrid acoustic metamaterial as super absorber for broadband low-frequency sound

An analytic model is developed to investigate the wave propagation and sound transmission characteristics of an infinite sandwich structure reinforced by two sets of orthogonal rib-stiffeners when subjected to convective fluid-loaded pressure. The rib-stiffeners are assumed to be identical and uniformly spaced, which can exert not only tensional forces and bending moments but also torsional moments on the facesheets. Inertial terms of the tensional forces, bending moments and torsional moments are introduced to account for inertial effects arising from the mass of the rib-stiffeners. With the surrounding acoustic fluids restricted by the acoustic wave equation, fluid–structure coupling is considered by imposing velocity continuity condition at fluid–panel interfaces. By applying the Bloch theorem for periodic structures, the structural and acoustic responses are expressed in a superposition form of space harmonics for a given wavenumber. The application of the virtual work principle for one periodic element yields two infinite sets of simultaneous algebraic coupled equations, which are numerically solved by truncating them in a finite range insofar as the solution converges. The validity and feasibility of the analytic model is qualified by comparing model predictions with existing results, in which the necessity and advantage of the exact modeling of rib-stiffener motions are also demonstrated. Specifically, the influences of inertial effects arising from rib-stiffener mass, the periodicity spacing of rib-stiffeners, and the airborne as well as structure-borne paths on the transmission of sound across the sandwich structure are quantified and conclusions of significant practical implications are drawn.

Analytical modeling of fluid loaded orthogonally rib-stiffened sandwich structures: Sound transmission

The air-borne sound insulation performance of a rectangular double-panel partition clamp mounted on an infinite acoustic rigid baffle is investigated both analytically and experimentally and compared with that of a simply supported one. With the clamped (or simply supported) boundary accounted for by using the method of modal function, a double series solution for the sound transmission loss (STL) of the structure is obtained by employing the weighted residual (Galerkin) method. Experimental measurements with Al double-panel partitions having air cavity are subsequently carried out to validate the theoretical model for both types of the boundary condition, and good overall agreement is achieved. A consistency check of the two different models (based separately on clamped modal function and simply supported modal function) is performed by extending the panel dimensions to infinite where no boundaries exist. The significant discrepancies between the two different boundary conditions are demonstrated in terms of the STL versus frequency plots as well as the panel deflection mode shapes.

Fengxian Xin

Papers

Hybrid acoustic metamaterial as super absorber for broadband low-frequency sound

Analytical modeling of fluid loaded orthogonally rib-stiffened sandwich structures: Sound transmission

Analytical and experimental investigation on transmission loss of clamped double panels: implication of boundary effects

Sound radiation of orthogonally rib-stiffened sandwich structures with cavity absorption

Heterogeneously perforated honeycomb-corrugation hybrid sandwich panel as sound absorber