Krishna Shah

The effect of erythropoietin on autologous stem cell-mediated bone regeneration.

Mesenchymal stem cells (MSCs) although used for bone tissue engineering are limited by the requirement of isolation and culture prior to transplantation. Our recent studies have shown that biomaterial implants can be engineered to facilitate the recruitment of MSCs. In this study, we explore the ability of these implants to direct the recruitment and the differentiation of MSCs in the setting of a bone defect. We initially determined that both stromal derived factor-1alpha (SDF-1α) and erythropoietin (Epo) prompted different degrees of MSC recruitment. Additionally, we found that Epo and bone morphogenetic protein-2 (BMP-2), but not SDF-1α, triggered the osteogenic differentiation of MSCs in vitro. We then investigated the possibility of directing autologous MSC-mediated bone regeneration using a murine calvaria model. Consistent with our in vitro observations, Epo-releasing scaffolds were found to be more potent in bridging the defect than BMP-2 loaded scaffolds, as determined by computed tomography (CT) scanning, fluorescent imaging and histological analyses. These results demonstrate the tremendous potential, directing the recruitment and differentiation of autologous MSCs has in the field of tissue regeneration.

Measurement of Multiscale Thermal Transport Phenomena in Li-Ion Cells: A Review

The performance, safety, and reliability of electrochemical energy storage and conversion systems based on Li-ion cells depend critically on the nature of heat transfer in Liion cells, which occurs over multiple length scales, ranging from thin material layers all the way to large battery packs. Thermal phenomena in Li-ion cells are also closely coupled with other transport phenomena such as ionic and charge transport, making this a challenging, multidisciplinary problem. This review paper presents a critical analysis of recent research literature related to experimental measurement of multiscale thermal transport in Li-ion cells. Recent research on several topics related to thermal transport is summarized, including temperature and thermal property measurements, heat generation measurements, thermal management, and thermal runaway measurements on Li-ion materials, cells, and battery packs. Key measurement techniques and challenges in each of these fields are discussed. Critical directions for future research in these fields are identified. [DOI: 10.1115/1.4034413]

State-of-the-art and Future Research Needs for Multiscale Analysis of Li-ion Cells

Author(s): Shah, K; Balsara, N; Banerjee, S; Chintapalli, M; Cocco, AP; Chiu, WKS; Lahiri, I; Martha, S; Mistry, A; Mukherjee, PP; Ramadesigan, V; Sharma, CS; Subramanian, VR; Mitra, S; Jain, A | Abstract: The performance, safety, and reliability of Li-ion batteries are determined by a complex set of multiphysics, multiscale phenomena that must be holistically studied and optimized. This paper provides a summary of the state of the art in a variety of research fields related to Li-ion battery materials, processes, and systems. The material presented here is based on a series of discussions at a recently concluded bilateral workshop in which researchers and students from India and the U.S. participated. It is expected that this summary will help understand the complex nature of Li-ion batteries and help highlight the critical directions for future research.

Conjugate Heat Transfer Analysis of Thermal Management of a Li-Ion Battery Pack

Author(s): Chalise, D; Shah, K; Prasher, R; Jain, A | Abstract:

Measurement Sensitivity Analysis of the Transient Hot Source Technique Applied to Flat and Cylindrical Samples

The transient source measurement technique is a nonintrusive, nondestructive method of measuring the thermal properties of a given sample. The transient source technique has been implemented using a wide variety of sensor shapes or configurations. The modern transient plane source (TPS) sensor is a spiral-shaped sensor element which evolved from transient line and transient hot strip (THS) source techniques. Commercially available sensors employ a flat interface that works well when test samples have a smooth, flat surface. The present work provides the basis for a new, cylindrical strip (CS) sensor configuration to be applied to cylindrical surfaces. Specifically, this work uses parameter estimation theory to compare the performance of CS sensor configurations with a variety of existing flat sensor geometries, including TPS and THS. A single-parameter model for identifying thermal conductivity and a two-parameter model for identifying both thermal conductivity as well as volumetric heat capacity are considered. Results indicate that thermal property measurements may be carried out with greater measurement sensitivity using the CS sensor configuration than similar configurations for flat geometries. In addition, this paper shows how the CS sensor may be modified to adjust the characteristic time scale of the experiment, if needed. [DOI: 10.1115/1.4034178]