Cell mechanics is a multidisciplinary field that bridges cell biology, fundamental mechanics, and micro and nanotechnology, which synergize to help us better understand the intricacies and the complex nature of cells in their native environment. With recent advances in nanotechnology, microfabrication methods and micro-electro-mechanical-systems (MEMS), we are now well situated to tap into the complex micro world of cells. The field that brings biology and MEMS together is known as Biological MEMS (BioMEMS). BioMEMS take advantage of systematic design and fabrication methods to create platforms that allow us to study cells like never before. These new technologies have been rapidly advancing the study of cell mechanics. This review article provides a succinct overview of cell mechanics and comprehensively surveys micro and nano-scale technologies that have been specifically developed for and are relevant to the mechanics of cells.Here we focus on micro and nano-scale technologies, and their applications in biology and medicine, including imaging, single cell analysis, cancer cell mechanics, organ-on-a-chip systems, pathogen detection, implantable devices, neuroscience and neurophysiology. We also provide a perspective on the future directions and challenges of technologies that relate to the mechanics of cells.

This paper conducts sensitivity analyses on factors affecting the performance of vertical geothermal heat pump system, aiming to formulate design and operation strategies to improve its performance. It firstly describes the development of a 3D coupled Finite Element Model (FEM), which is utilized to simulate the steady state and transient behaviors of geothermal heat exchanger (GHE). The model holistically couples the heat exchange processes between pipe fluid flow, grouting backfill material, and adjacent ground associated with GHE. The model is firstly validated by comparison with the experimental data from an in-service GHE. Base on the calibrated model, a series of sensitivity analyses are conducted on the influence of geological, design, and operational factors intermittent operation mode of GHE achieves higher such as the initial ground temperature profile, GHE pipe installation depth, circulation fluid flow velocity, inlet temperature, subsurface water flow velocity, and material thermal properties. It also assess the behaviors of GHE under continuous operation versus intermittent operation modes. The results show that both design parameter (i.e., GHE pipe installation depth) and operational parameters (i.e, circulation fluid flow velocity) have major influence on the GHE performance. For a certain design length of GHE, the GHE performance improves with higher circulation fluid flow velocity until beyond a critical velocity. For GHE working in the heating mode, the heat extraction by GHE increases with decreasing fluid temperature at the inlet. In the geological factor aspect, the thermal conductivity of the ground material plays a very important role on the GHE performance operating in the continuous operation mode, while its specific heat capacity exerts no appreciable influence. However, for intermittent operation mode, both thermal conductivity and specific heat capacity of the ground, particularly the grouting materials, affect the ground thermal energy extraction. The results also showed that the presence of subsurface ground water flow improves the heat exchange of GHE. Operation wise, the GHE achieves higher performance and Coefficient of Performance (COP) under intermittent operation mode than under continuous operation mode. These observations point to ways to improve the performance of GHE from both design and operation aspects. Introduction1 Over the past decades, the depletion of fossil energy along with the demand to reduce carbon footprint in the 2 energy sector has promoted the development of renewable energy techniques including solar, wind, geothermal energy, 3 bioenergy, hydropower, etc. The renewable energy revolution has spread worldwide, which accounted for 19% of the 4 global energy generation in 2012 and quickly increased to 23% in 2013 [1]. In the United States, the cumulative 5 installation of renewable electricity capacity has doubled since 2000. Particularly, the United States led the world in 6 energy production from geothermal and biomass in 2013 [1]. There has been adoption o...

No abstract

Snow melting system based on geothermal heat exchanger pile is an innovative technology that combines geothermal energy with structural foundation. It overcomes the problems of conventional chemical based snow melting in mitigating infrastructure corrosion and negative environmental effects. By integrating the underground heat exchanger into pile foundation that support the bridge structure, it effectively reduces the installation cost of geothermal system. This paper analyses the applicability and performance of such snow melting system for different regions. Energy demand for snow removal is firstly determined with ASHRAE criteria. A holistic 3D simulation model is developed to predict the energy extraction rate under different operation conditions. A hypothetical bridge deck (200 m length by 14.8 m (4 lanes) width) is analyzed to assess the feasibility of geothermal heat exchanger pile based snow melting system for 10 cities representing a variety of climatic regions of the United States. The number of pile foundation required for snow melting is used as indication of the technical feasibility. The results show that its feasibility and performance in bridge deck snow removal is dependent upon the geological and snow conditions of a particular region, as well as the design snow removal criteria.

The performance of a variety of geostructures, such as compacted clay liners, earth dams, and pavement embankments, is compromised by soil cracking. Experiments are set up to monitor the drying process of a clay layer under controlled temperature and humidity conditions. The gravimetric water content and images are captured automatically. Volumetric shrinkage of the bentonite sample as well as the crack patterns are determined from images. The monitored volumetric strain development is used to implement the discrete element method (DEM) to simulate the drying shrinkage and desiccation cracking. Model parameters are calibrated through unconfined compression tests on clay specimens at different water contents. This simplified calibration procedure allows characterization of the soil behaviors in the mesoscale and bypass the complex physicochemical processes involved. The initiation and propagation of cracks from the DEM model agree well with the phenomena observed in the laboratory experiments. The influence of boundary constraint and sample thickness on the crack patterns is analyzed, which includes the use of hydrophobic coating to diminish the boundary constraint. Major features of desiccation cracking can be replicated with the computational procedures. Boundary constraint, including surface roughness and strength of boundary layer, is found to significantly influence the final crack patterns.