Perspectives on thermoelectrics: from fundamentals to device applications

This review is an update of a previous review (A. J. Minnich, et al., Energy Environ. Sci., 2009, 2, 466) published two years ago by some of the co-authors, focusing on progress made in thermoelectrics over the past two years on charge and heat carrier transport, strategies to improve the thermoelectric figure of merit, with new discussions on device physics and applications, and assessing challenges on these topics. Understanding of phonon transport in bulk materials has advanced significantly as the first-principles calculations are applied to thermoelectric materials, and experimental tools are being developed. Some new strategies have been developed to improve electron transport in thermoelectric materials. Fundamental questions on phonon and electron transport across interfaces and in thermoelectric materials remain. With thermoelectric materials reaching high ZT values well above one, the field is ready to take a step forward and go beyond the materials' figure of merit. Developing device contacts and module fabrication techniques, developing a platform for efficiency measurements, and identifying applications are becoming increasingly important for the future of thermoelectrics.MIT Energy InitiativeSolid-State Solar-Thermal Energy Conversion Center (funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-FG02-09ER46577)United States. Dept. of Energy (DOE Grant No. DE-FG02-08ER46516)Robert Bosch Gmb

Tailoring Superconductivity with Quantum Dislocations

Despite the established knowledge that crystal dislocations can affect a material’s superconducting properties, the exact mechanism of the electron-dislocation interaction in a dislocated superconductor has long been missing. Being a type of defect, dislocations are expected to decrease a material’s superconducting transition temperature (T[subscript c]) by breaking the coherence. Yet experimentally, even in isotropic type I superconductors, dislocations can either decrease, increase, or have little influence on T[subscript c]. These experimental findings have yet to be understood. Although the anisotropic pairing in dirty superconductors has explained impurity-induced T[subscript c] reduction, no quantitative agreement has been reached in the case a dislocation given its complexity. In this study, by generalizing the one-dimensional quantized dislocation field to three dimensions, we reveal that there are indeed two distinct types of electron-dislocation interactions. Besides the usual electron-dislocation potential scattering, there is another interaction driving an effective attraction between electrons that is caused by dislons, which are quantized modes of a dislocation. The role of dislocations to superconductivity is thus clarified as the competition between the classical and quantum effects, showing excellent agreement with existing experimental data. In particular, the existence of both classical and quantum effects provides a plausible explanation for the illusive origin of dislocation-induced superconductivity in semiconducting PbS/PbTe superlattice nanostructures. A quantitative criterion has been derived, in which a dislocated superconductor with low elastic moduli and small electron effective mass and in a confined environment is inclined to enhance T[subscript c]. This provides a new pathway for engineering a material’s superconducting properties by using dislocations as an additional degree of freedom. Keywords: Dislocations; disordered superconductor; effective field theory; electron-dislocation interactionUnited States. Department of Energy. Office of Basic Energy Sciences (Grant DE-SC0001299)United States. Department of Energy. Office of Basic Energy Sciences (Grant DE-FG02-09ER46577)United States. Defense Advanced Research Projects Agency (Award HR0011-16-2-0041

Exploiting endogenous fibrocartilage stem cells to regenerate cartilage and repair joint injury

Tissue regeneration using stem cell-based transplantation faces many hurdles. Alternatively, therapeutically exploiting endogenous stem cells to regenerate injured or diseased tissue may circumvent these challenges. Here we show resident fibrocartilage stem cells (FCSCs) can be used to regenerate and repair cartilage. We identify FCSCs residing within the superficial zone niche in the temporomandibular joint (TMJ) condyle. A single FCSC spontaneously generates a cartilage anlage, remodels into bone and organizes a haematopoietic microenvironment. Wnt signals deplete the reservoir of FCSCs and cause cartilage degeneration. We also show that intra-articular treatment with the Wnt inhibitor sclerostin sustains the FCSC pool and regenerates cartilage in a TMJ injury model. We demonstrate the promise of exploiting resident FCSCs as a regenerative therapeutic strategy to substitute cell transplantation that could be beneficial for patients suffering from fibrocartilage injury and disease. These data prompt the examination of utilizing this strategy for other musculoskeletal tissues

Emphysema scores predict death from COPD and lung cancer

OBJECTIVE: Our objective was to assess the usefulness of emphysema scores in predicting death from COPD and lung cancer. METHODS: Emphysema was assessed with low-dose CT scans performed on 9,047 men and women for whom age and smoking history were documented. Each scan was scored according to the presence of emphysema as follows: none, mild, moderate, or marked. Follow-up time was calculated from time of CT scan to time of death or December 31, 2007, whichever came first. Cox regression analysis was used to calculate the hazard ratio (HR) of emphysema as a predictor of death. RESULTS: Median age was 65 years, 4,433 (49%) were men, and 4,133 (46%) were currently smoking or had quit within 5 years. Emphysema was identified in 2,637 (29%) and was a significant predictor of death from COPD (HR, 9.3; 95% CI, 4.3-20.2; P < .0001) and from lung cancer (HR, 1.7; 95% CI, 1.1-2.5; P = .013), even when adjusted for age and smoking history. CONCLUSIONS: Visual assessment of emphysema on CT scan is a significant predictor of death from COPD and lung cancer

MFA13 (MFA 2013)

Catalogue of a culminating student exhibition held at the Mildred Lane Kemper Art Museum, May 3-July 29, 2013. Contents include Introduction / Buzz Spector -- The collaborative turn : new models of thinking, making, and learning / Patricia Olynyk -- [Introduction] / David Schuman -- Lyndon Barrois, Jr. / Rickey Laurentiis -- Sarah Bernhardt -- Shifting Shanghais / Hsuan Ying Chen -- Serhii Chrucky / JaNae Contag -- JaNae Contag / Emily Hanson -- Carrie DeBacker / Gabriel Feldman -- Erin M. Duhigg -- José Garza / Serhii Chrucky -- Eric Gray / Ariel Lewis -- Meghan Allynn Johnson : to or towards / Blair Allyn Johnson -- Hoa Le / Maria Xia -- Christine Eunji Lee -- Lavar Munroe : the black superhero when everyone was looking for the scapegoat / Patrick Johnson -- Jon A. Orosco : architectonics / Rickey Laurentiis -- Michael Powell / Nicholas Tamarkin -- Bridget A. Purcell : welcome home / Andy Chen -- Malahat Qureshi -- Natalie Rodgers / Katie McGinnis -- Carla Fisher Schwartz / Jennifer Padgett -- Zak Smoker -- Laurencia Strauss / Maura Pellettieri -- Lili Yang -- Vivian Zapata -- Contributors -- About the Sam Fox School.https://openscholarship.wustl.edu/books/1004/thumbnail.jp

Lattice thermal conductivity of Bi, Sb, and Bi-Sb alloy from first principles

Using first principles, we calculate the lattice thermal conductivity of Bi, Sb, and Bi-Sb alloys, which are of great importance for thermoelectric and thermomagnetic cooling applications. Our calculation reveals that the ninth-neighbor harmonic and anharmonic force constants are significant; accordingly, they largely affect the lattice thermal conductivity. Several features of the thermal transport in these materials are studied: (1) the relative contributions from phonons and electrons to the total thermal conductivity as a function of temperature are estimated by comparing the calculated lattice thermal conductivity to the measured total thermal conductivity, (2) the anisotropy of the lattice thermal conductivity is calculated and compared to that of the electronic contribution in Bi, and (3) the phonon mean free path distributions, which are useful for developing nanostructures to reduce the lattice thermal conductivity, are calculated. The phonon mean free paths are found to range from 10 to 100 nm for Bi at 100 K.United States. Dept. of Energy. Office of Science (Award DE-SC0001299/DE-FG02-09ER46577)United States. Air Force Office of Scientific Research. Multidisciplinary University Research Initiativ