Oxide Thermoelectric Materials for High Temperature Power Generation

Power plants, turbine engines, automobiles and air conditioning, among others, release enormous amounts of heat into the environment, thereby wasting vast amounts of thermal energy. The typical U.S. power plant is only about 33% efficient, using three units of fuel to produce one unit of electricity. The rest is released as waste heat into the atmosphere. In standard diesel-powered vehicles, up to 65% of the fuel is lost as waste heat, which is rejected through the cooling and exhaust systems at temperatures up to 900°C. A potential way to improve the sustainability of our energy infrastructure and electricity base is through waste heat recovery using solid state thermoelectric power generators, which can directly convert temperature differentials into electrical power. Oxide materials, such as newly-developed nontoxic Ca3Co 4O9, are particularly promising for thermoelectric applications because of their relatively high stability, even at high temperatures in air. The main challenge for enabling oxide thermoelectric materials is to improve their conversion efficiency, which is currently lower than that of conventional, low temperature thermoelectric materials. The conversion efficiency is usually evaluated by the dimensionless figure-of-merit ZT = S2T/rhokappa, where S, T, rho and kappa are Seebeck coefficient (or thermoelectric power), absolute temperature, electrical resistivity, and thermal conductivity, respectively.;The main purpose of this project is to optimize the synthesis condition for powder precursor and pelletizing condition for bulk ceramic, to obtain the pure Ca3Co4O9 with high energy conversion efficiency. In the meanwhile, for practical applications, it is essential to understand the thermal stability of sintered Ca3Co4O 9 materials in air, the formation of other cobaltite Ca-Co-O phases, and their property and structure evolution upon long term high temperature annealing and over-heating above the reported Ca3Co4O 9 decomposition temperature of 926°C, as indicated in the CaO-CoO phase diagram. In details, the following is studied in this thesis: (1) Effect of calcinations temperature for the precursor powders on the thermoelectric properties of Ca3Co4O9; (2) Anisotropic thermoelectric properties in a misfit-layered calcium cobaltite affected by the conditions of pellets preparation. (3) Nanostructure and thermoelectric properties evolution of polycrystal Ca3Co4O9 upon over-heating condition.;The above study will be instrumental for fabricating the polycrystal Ca3Co4O9 with optimized microstructure and enhanced thermoelectric properties. Upon the completion of the microstructure and properties optimization of pure polycrystal Ca3Co4O 9, investigation will be carried out to further improve the thermoelectric performance of Ca3Co4O9 through doping impurity and engineering the nanostructure

Développements en spectroscopie et microscopie non linéaire pour l'étude morphologique et fonctionnelle de la peau humaine

Skin is an organ that envelops the entire body, acts as a pivotal, efficient natural barrier to- wards various invaders. For the treatment of major dermatological diseases and in the cosmetic industry, topical applications on skin are widely used, thus many efforts in skin research have been aimed at understanding detailed molecular absorption and efficient penetration mechanisms. However, it remains difficult to obtain high-resolution visualization in 3D together with chemical selectivity and quantification in skin research. Nonlinear spectroscopy and microscopy, including two-photon excited fluorescence (TPEF), spontaneous Raman scattering, coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS), are introduced in this work for unambiguous skin morphological identification and topical applied molecules detection. Sev- eral quantitative methods based on nonlinear spectroscopy and microscopy are designed for 3D chemical analysis in reconstructed skin, ex vivo and in vivo on human skin. Furthermore, to adapt to forthcoming clinical applications, an endoscopic design is investigated to bring nonlin- ear imaging in flexible endoscopes.La peau est un organe qui enveloppe le corps, elle est une barrière naturelle importante et efficace contre différents envahisseurs. Pour le traitement des maladies dermatologiques ainsi que dans l'industrie cosmétique, les applications topiques sur la peau sont largement utilisées. Ainsi beaucoup d'efforts ont été investis dans la recherche sur la peau visant à comprendre l'absorption moléculaire et les mécanismes rendant efficace la pénétration. Cependant, il reste difficile d'obtenir une visualisation 3D de haute résolution combinée à une information chimique- ment spécifique et quantitative dans la recherche sur la peau. La spectroscopie et la microscopie non-linéaire, incluant la fluorescence excitée à 2-photon (TPEF), la diffusion Raman spontanée, la diffusion Raman cohérente anti-Stokes (CARS) et la diffusion Raman stimulée (SRS), sont introduits dans ce travail pour l'identification sans ambiguïté de la morphologique de la peau et la détection de molécules appliquées de façon topique. Plusieurs méthodes quantitatives basées sur la spectroscopie et la microscopie non-linéaire sont proposées pour l'analyse chimique en3D sur la peau artificielle, ex vivo et in vivo sur la peau humaine. De plus, afin de s'adapter aux applications cliniques à venir, un design endoscopique est étudié pour permettre l'imagerie non-linéaires dans les endoscopes flexibles

Genetic variation in eight Chinese cattle breeds based on the analysis of microsatellite markers

Genetic variability and genetic relationships were investigated among eight Chinese cattle breeds using 12 microsatellite markers. Three hundred and fifty-two alleles were detected and the average number of alleles per locus ranged from 8.33 ± 1.67 in the Jiaxian breed to 21.33 ± 5.60 in the Qinchuan breed with a mean value of 13.91. The total number of alleles per microsatellite ranged from 21 (INRA005, HEL1) to 40 (HEL13), with a mean of 29.33 per locus. The fixation indices at the 12 loci in the eight breeds were very low with a mean of 0.006. A principal components analysis and the construction of a neighborjoining tree showed that these eight Chinese cattle breeds cluster into three groups i.e. the Yanbian andChineseHolstein, theNanyang and Jiaxian, and the four remaining breeds.This clustering agrees with the origin and geographical distributions of these Chinese breeds

A SIMPLE Approach to Provably Reconstruct Ising Model with Global Optimality

Reconstruction of interaction network between random events is a critical problem arising from statistical physics and politics to sociology, biology, and psychology, and beyond. The Ising model lays the foundation for this reconstruction process, but finding the underlying Ising model from the least amount of observed samples in a computationally efficient manner has been historically challenging for half a century. By using the idea of sparsity learning, we present a approach named SIMPLE that has a dominant sample complexity from theoretical limit. Furthermore, a tuning-free algorithm is developed to give a statistically consistent solution of SIMPLE in polynomial time with high probability. On extensive benchmarked cases, the SIMPLE approach provably reconstructs underlying Ising models with global optimality. The application on the U.S. senators voting in the last six congresses reveals that both the Republicans and Democrats noticeably assemble in each congresses; interestingly, the assembling of Democrats is particularly pronounced in the latest congress

Japanese Encephalitis Virus wild strain infection suppresses dendritic cells maturation and function, and causes the expansion of regulatory T cells

<p>Abstract</p> <p>Background</p> <p>Japanese encephalitis (JE) caused by Japanese encephalitis virus (JEV) accounts for acute illness and death. However, few studies have been conducted to unveil the potential pathogenesis mechanism of JEV. Dendritic cells (DCs) are the most prominent antigen-presenting cells (APCs) which induce dual humoral and cellular responses. Thus, the investigation of the interaction between JEV and DCs may be helpful for resolving the mechanism of viral escape from immune surveillance and JE pathogenesis.</p> <p>Results</p> <p>We examined the alterations of phenotype and function of DCs including bone marrow-derived DCs (bmDCs) <it>in vitro </it>and spleen-derived DCs (spDCs) <it>in vivo </it>due to JEV P3 wild strain infection. Our results showed that JEV P3 infected DCs <it>in vitro </it>and <it>in vivo</it>. The viral infection inhibited the expression of cell maturation surface markers (CD40, CD80 and CD83) and MHCⅠ, and impaired the ability of P3-infected DCs for activating allogeneic naïve T cells. In addition, P3 infection suppressed the expression of interferon (IFN)-α and tumor necrosis factor (TNF)-α but enhanced the production of chemokine (C-C motif) ligand 2 (CCL2) and interleukin (IL)-10 of DCs. The infected DCs expanded the population of CD4+ Foxp3+ regulatory T cell (Treg).</p> <p>Conclusion</p> <p>JEV P3 infection of DCs impaired cell maturation and T cell activation, modulated cytokine productions and expanded regulatory T cells, suggesting a possible mechanism of JE development.</p

Cancer burden in China: a Bayesian approach

BACKGROUND Cancer is a serious health issue in China, but accurate national counts for cancer incidence are not currently available. Knowledge of the cancer burden is necessary for national cancer control planning. In this study, national death survey data and cancer registration data were used to calculate the cancer burden in China using a Bayesian approach. METHODS Cancer mortality and incidence rates for 2004-2005 were obtained from the National Cancer Registration database. The third National Death Survey (NDS), 2004-2005 database provided nationally representative cancer mortality rates. Bayesian modeling methods were used to estimate mortality to incidence (MI) ratios from the registry data and national incidence from the NDS for specific cancer types by age, sex and urban or rural location. RESULTS The total estimated incident cancer cases in 2005 were 2,956,300 (1,762,000 males, 1,194,300 females). World age standardized incidence rates were 236.2 per 100,000 in males and 168.9 per 100,000 in females in urban areas and 203.7 per 100,000 and 121.8 per 100,000 in rural areas. CONCLUSIONS MI ratios are useful for estimating national cancer incidence in the absence of representative incidence or survival data. Bayesian methods provide a flexible framework for smoothing rates and representing statistical uncertainty in the MI ratios. Expansion of China's cancer registration network to be more representative of the country would improve the accuracy of cancer burden estimates.This study used the data from National Central Cancer Registry database. The authors acknowledge the contributions of local cancer registries providing registration data and working group of the Third National Death Survey

COVID-19 transmission within a family cluster by presymptomatic carriers in China

We report a COVID-19 family cluster caused by a presymptomatic case. There were 9 family members, including 8 laboratory-confirmed with COVID-19, and a 6-year-old child had no evidence of infection. Amongst the 8 patients, one adult and one 13-month-old infant were asymptomatic, one adult was diagnosed as having severe pneumonia