Mechanical characterisation of oocytes - The influence of sample geometry on parameter identification.

The present study focused on the material characterisation of porcine oocytes by experiments combined with an inverse finite-element method (iFEM) approach. In doing so, two different deformation states, compression and indentation, were realised to enable the validation of the numerical model. In addition to classical force-strain relations, geometrical information on the oocyte's surface and volume changes during deformation were collected.

Changes in three-dimensional muscle structure of rabbit gastrocnemius, flexor digitorum longus, and tibialis anterior during growth.

Muscular contraction dynamics depends on active and passive muscle properties (e.g., the force-velocity relation) as well as on the three-dimensional (3D) muscle structure (e.

Thermal management of micro-scale inorganic light-emittng diodes on an orthotropic substrate for biointegrated applications.

The orthotropic material with the in-plane thermal conductivity much larger than the off-plane one can control the heat flow direction. This feature provides unique benefits in thermal management of micro-scale inorganic light-emitting diodes (μ-ILEDs) device for biointegrated applications by helping the heat dissipation from μ-ILEDs along the in-plane directions to lower the μ-ILED temperature and prevent the heat dissipation to the tissue along the off-plane direction to ensure a low tissue temperature. Three-dimensional analytical models, accounting for the coupling between the Fourier heat conduction in the μ-ILED device and the Pennes bioheat transfer in the human skin, are established to investigate the thermal behaviors of μ-ILEDs on an orthotropic substrate integrated with the human skin.

Three-dimensional mechano-electrochemical model for smooth muscle contraction of the urinary bladder.

The urinary bladder is a central organ of vertebrates and imposes, based on its extreme deformation (volume changes up to several 100%), special requirements on the overall bladder tissue. However, studies focusing on three-dimensional modelling of bladder deformation and bladder function during micturition are rare. Based on three fields, namely, the membrane potential, calcium concentration, and placement, a mechano-electrochemical-coupled, three-dimensional model describing the contractile behaviour of urinary bladder smooth muscle is presented using a strain energy function.

Fully implantable, battery-free wireless optoelectronic devices for spinal optogenetics.

The advent of optogenetic tools has allowed unprecedented insights into the organization of neuronal networks. Although recently developed technologies have enabled implementation of optogenetics for studies of brain function in freely moving, untethered animals, wireless powering and device durability pose challenges in studies of spinal cord circuits where dynamic, multidimensional motions against hard and soft surrounding tissues can lead to device degradation. We demonstrate here a fully implantable optoelectronic device powered by near-field wireless communication technology, with a thin and flexible open architecture that provides excellent mechanical durability, robust sealing against biofluid penetration and fidelity in wireless activation, thereby allowing for long-term optical stimulation of the spinal cord without constraint on the natural behaviors of the animals.

Finite element analysis of 6 large PMMA skull reconstructions: A multi-criteria evaluation approach.

In this study 6 pre-operative designs for PMMA based reconstructions of cranial defects were evaluated for their mechanical robustness using finite element modeling. Clinical experience and engineering principles were employed to create multiple plan options, which were subsequently computationally analyzed for mechanically relevant parameters under 50N loads: stress, strain and deformation in various components of the assembly. The factors assessed were: defect size, location and shape.

In Situ Observation of Twin Boundary Sliding in Single Crystalline Cu Nanowires.

Using a homemade, novel, in situ transmission electron microscopy (TEM) double tilt tensile device, plastic behavior of single crystalline Cu nanowires of around 150 nm are studied. Deformation twins occur during the tests as predesigned before the experiments. In situ observation of twin boundary sliding (TBS) caused by full dislocation (extended dislocation) is first revealed at the atomic scale which is confirmed by molecular dynamics (MD) simulation results.

Theoretical models for magneto-sensitive elastomers: A comparison between continuum and dipole approaches.

In the literature, different theoretical models have been proposed to describe the properties of systems which consist of magnetizable particles that are embedded into an elastomer matrix. It is well known that such magneto-sensitive elastomers display a strong magneto-mechanical coupling when subjected to an external magnetic field. Nevertheless, the predictions of available models often vary significantly since they are based on different assumptions and approximations.

Correlation between transversal and orthogonal maximal diameters of abdominal aortic aneurysms and alternative rupture risk predictors.

Purpose: There is no standard for measuring maximal diameter (Dmax) of abdominal aortic aneurysm (AAA) from computer tomography (CT) images although differences between Dmax evaluated from transversal (axialDmax) or orthogonal (orthoDmax) planes can be large especially for angulated AAAs. Therefore we investigated their correlations with alternative rupture risk indicators as peak wall stress (PWS) and peak wall rupture risk (PWRR) to decide which Dmax is more relevant in AAA rupture risk assessment.

Material And Methods: The Dmax values were measured by a trained radiologist from 70 collected CT scans, and the corresponding PWS and PWRR were evaluated using Finite Element Analysis (FEA).

Electrochemical tuning of the optical properties of nanoporous gold.

Using optical in-situ measurements in an electrochemical environment, we study the electrochemical tuning of the transmission spectrum of films from the nanoporous gold (NPG) based optical metamaterial, including the effect of the ligament size. The long wavelength part of the transmission spectrum around 800 nm can be reversibly tuned via the applied electrode potential. The NPG behaves as diluted metal with its transition from dielectric to metallic response shifted to longer wavelengths.

A High Performance Piezoelectric Sensor for Dynamic Force Monitoring of Landslide.

Due to the increasing influence of human engineering activities, it is important to monitor the transient disturbance during the evolution process of landslide. For this purpose, a high-performance piezoelectric sensor is presented in this paper. To adapt the high static and dynamic stress environment in slope engineering, two key techniques, namely, the self-structure pressure distribution method (SSPDM) and the capacitive circuit voltage distribution method (CCVDM) are employed in the design of the sensor.

Flexible Near-Field Wireless Optoelectronics as Subdermal Implants for Broad Applications in Optogenetics.

In vivo optogenetics provides unique, powerful capabilities in the dissection of neural circuits implicated in neuropsychiatric disorders. Conventional hardware for such studies, however, physically tethers the experimental animal to an external light source, limiting the range of possible experiments. Emerging wireless options offer important capabilities that avoid some of these limitations, but the current size, bulk, weight, and wireless area of coverage is often disadvantageous.

Effects of Growth on Muscle, Tendon, and Aponeurosis Tissues in Rabbit Shank Musculature.

There exist several studies using morphological analyses of skeletal muscles to obtain a better understanding of muscle structure. The structural information obtained are primarily determined from single muscle components using individual animals of discrete ages. Further, little is known about changing dimensions of the aponeurosis, which is an important load-transferring interface in muscle mechanics.

Importance of contraction history on muscle force of porcine urinary bladder smooth muscle.

Introduction: The purpose of this study was to provide a comprehensive dataset of porcine urinary bladder smooth muscle properties. Particularly, the history dependence of force production, namely force depression (FD) following shortening and force enhancement (FE) following stretch, was analysed. During active micturition, the circumference of the urinary bladder changes enormously.

One-Dimensional Thermal Analysis of the Flexible Electronic Devices Integrated with Human Skin.

A one-dimensional analytic thermal model for the flexible electronic devices integrated with human skin under a constant and pulsed power is developed. The Fourier heat conduction equation is adopted for the flexible electronics devices while the Pennes bio-heat transfer equation is adopted for the skin tissue. Finite element analysis is performed to validate the analytic model through the comparison of temperature distributions in the system.

Fluid-structure interaction analysis of the drop impact test for helicopter fuel tank.

The crashworthiness of helicopter fuel tank is vital to the survivability of the passengers and structures. In order to understand and improve the crashworthiness of the soft fuel tank of helicopter during the crash, this paper investigated the dynamic behavior of the nylon woven fabric composite fuel tank striking on the ground. A fluid-structure interaction finite element model of the fuel tank based on the arbitrary Lagrangian-Eulerian method was constructed to elucidate the dynamic failure behavior.

Remote Bridge Deflection Measurement Using an Advanced Video Deflectometer and Actively Illuminated LED Targets.

An advanced video deflectometer using actively illuminated LED targets is proposed for remote, real-time measurement of bridge deflection. The system configuration, fundamental principles, and measuring procedures of the video deflectometer are first described. To address the challenge of remote and accurate deflection measurement of large engineering structures without being affected by ambient light, the novel idea of active imaging, which combines high-brightness monochromatic LED targets with coupled bandpass filter imaging, is introduced.

Intermuscular pressure between synergistic muscles correlates with muscle force.

The purpose of the study was to examine the relationship between muscle force generated during isometric contractions (i.e. at a constant muscle-tendon unit length) and the intermuscular (between adjacent muscles) pressure in synergistic muscles.

Long-term mechanical behaviour of skeletal muscle tissue in semi-confined compression experiments.

In this study, porcine skeletal muscle tissue was tested until 112 hours post mortem using a semi-confined compression device that induces fascicles to enter one of the states of compression (mode I), tension (mode II), or constant length (mode III). Based on the authors׳ previous studies (Böl et al., 2014, 2015a), the anisotropic mechanical behaviour of the tissue was analysed, with a special focus on the testing time post mortem.

Study of the Mechanical Behavior of Radially Grown Fivefold Twinned Nanowires on the Atomic Scale.

In situ bending tests and dynamic modeling simulations are for the first time revealing the mechanical behavior of copper nanowires (NW) with radially grown fivefold twin structures on the atomic scale. Combining the simulations with the experimental results it is shown that both the twin boundaries (TBs) and the twin center act as dislocation sources. TB migration and L-locks are readily observed in these types of radially grown fivefold-twin structures.

Strong Surface Orientation Dependent Thermal Transport in Si Nanowires.

Thermoelectrics, which convert waste heat to electricity, offer an attractive pathway for addressing an important niche in the globally growing landscape of energy demand. Research to date has focused on reducing the thermal conductivity relative to the bulk. Si nanowires (NWs) have received exceptional attention due to their low-dimensionality, abundance of availability, and high carrier mobility.

Identification of the mechanical parameters for the human uterus in vivo using intrauterine pressure measurements.

There are limited experimental data to characterize the mechanical response of human myometrium. A method is presented in this work to identify mechanical parameters describing the active response of human myometrium from the in vivo intrauterine pressure measurements. The human uterine contraction during labor is simulated by implementing a coupled model in a finite element scheme, and the intrauterine pressure is evaluated as the outcome.

Robustly Engineering Thermal Conductivity of Bilayer Graphene by Interlayer Bonding.

Graphene and its bilayer structure are the two-dimensional crystalline form of carbon, whose extraordinary electron mobility and other unique features hold great promise for nanoscale electronics and photonics. Their realistic applications in emerging nanoelectronics usually call for thermal transport manipulation in a controllable and precise manner. In this paper we systematically studied the effect of interlayer covalent bonding, in particular different interlay bonding arrangement, on the thermal conductivity of bilayer graphene using equilibrium molecular dynamics simulations.

[Three-dimensional finite element analysis of influence of occlusal surface height on stress distribution around posterior implant-supported single crown].

Objective: To evaluate the effect of the occlusal surface height of a mandibular posterior implant-supported single crown on stress in bone tissues.

Methods: Three-dimensional finite element models of the implant-supported single crown replacing the missing right lower second premolar, mesial and distal natural teeth, periodontal membrane, alveolar bone, loaded rigid body and analog food of almond were established. Using the Federation Dentaire International (FDI) system, the first premolar, the second premolar and the first molar were represented with 44, 45, 46.

Flexible Electronics: Theoretical and Experimental Studies of Epidermal Heat Flux Sensors for Measurements of Core Body Temperature (Adv. Healthcare Mater. 1/2016).

On page 119, J. A. Rogers and co-workers present theoretical approaches, modeling algorithms, materials, and device designs for the noninvasive measurement of core body temperature by using multiple differential temperature sensors that attach softly and intimately onto the surface of the skin.