Precise nanoscale characterisation of novel Heusler thermoelectrics via analytical electron microscopy

Thermoelectric power generation presents an opportunity to `scavenge' energy that would otherwise be wasted as heat. Heusler alloys, a class of materials often comprising inexpensive, non-toxic elements, are promising for practical use in a new generation of thermoelectric devices. Recently, efficient thermoelectric Heusler alloys have overcome a performance-limiting thermal conductivity through the introduction of nanostructures that scatter phonons and impede thermal transport. However, the nature and stability of nanostructures can be difficult to discern, especially the minor compositional variations that derive from inhomogeneous phase segregation. Throughout this thesis TiNiSn, which forms the basis for some of the most promising n-type half-Heusler thermoelectrics, is studied through a unique combination of elemental and diffractive analysis in the scanning transmission electron microscope (STEM). Epitaxial thin films of TiNiSn are grown by pulsed laser deposition and FIB-prepared cross-sections of these are characterised in STEM with a focus on aberration-corrected STEM-EELS spectrum imaging and scanning precession electron diffraction (SPED), yielding precise chemical and structural quantification with nanoscale spatial resolution. The results throughout this thesis demonstrate the importance of STEM for quantitative studies of thermoelectric materials, as it can provide the analytical precision required for accurate identification of minority phases in TiNiSn specimens that would otherwise be overlooked in bulk analytical techniques. Sensitivity to very small elemental concentrations is a cornerstone of the use of STEM-EELS for chemical characterisation. Precisions of 0.3 % were achieved through adoption and development of refined, reference-based, absolute elemental quantification protocols which were essential in overcoming difficulties with large uncertainties posed by conventional methods. The success of this approach, in part, is due to advances made in characterisation of experimental conditions including, for the first time, an automated, standard-less approach to the measurement and correction of energy dispersion non-uniformities. Dispersion correction enables reliable, absolute calibration of energy-loss in spectra to yield a precision better than 0.1 eV. These developments in STEM-EELS were then used in three investigations of TiNiSn thin films exploring aspects of nanostructuring, phase segregation and crystrallographic strain and coherency. We discovered the spontaneous formation of nanostructures during thin film growth, gaining some insight into the phase segregation mechanisms that lead to their nucleation. Novel in situ STEM studies of phase segregation facilitated direct observations of the thermal evolution of nanoscale phases and results enabled characterisation of diffusion rates of Ni migration between full- and half-Heusler phases, for which the activation energy was calculated as 0.3~eV. Combining SPED with advances in detector technology, STEM structural investigations highlighted an interesting strain texture associated with nanostructuring of the half-Heusler thin films. Finally, combining SPED results with STEM-EELS measurements is proposed as a route to `correlative-STEM' analysis, which unifies nanoscale chemical and structural information for greater insights into the impact of nanostructures in thermoelectrics

Retrieving Decadal Climate Change from Satellite Radiance Observations-A 100-year CO2 Doubling OSSE Demonstration.

Preparing for climate change depends on the observation and prediction of decadal trends of the environmental variables, which have a direct impact on the sustainability of resources affecting the quality of life on our planet. The NASA Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission is proposed to provide climate quality benchmark spectral radiance observations for the purpose of determining the decadal trends of climate variables, and validating and improving the long-range climate model forecasts needed to prepare for the changing climate of the Earth. The CLARREO will serve as an in-orbit, absolute, radiometric standard for the cross-calibration of hyperspectral radiance spectra observed by the international system of polar operational satellite sounding sensors. Here, we demonstrate that the resulting accurately cross-calibrated polar satellite global infrared spectral radiance trends (e.g., from the Metop IASI instrument considered here) can be interpreted in terms of temperature and water vapor profile trends. This demonstration is performed using atmospheric state data generated for a 100-year period from 2000-2099, produced by a numerical climate model prediction that was forced by the doubling of the global average atmospheric CO2 over the 100-year period. The vertical profiles and spatial distribution of temperature decadal trends were successfully diagnosed by applying a linear regression profile retrieval algorithm to the simulated hyperspectral radiance spectra for the 100-year period. These results indicate that it is possible to detect decadal trends in atmospheric climate variables from high accuracy all-sky satellite infrared radiance spectra using the linear regression retrieval technique

Lucio Parenzan: an appreciation

n/

Desirable Qualities, Attributes, and Characteristics of Successful Athletic Trainers -- A National Study

In an effort to determine the importance of desirable qualities, attributes and characteristics necessary for the success of interscholastic athletic trainers a Likert-type scale survey was mailed to all head athletic trainers of NCAA Division III institutions in the United States. The survey consisted of 24 statements allowing for the following responses: essential, very important, important, not very important, and irrelevant. The qualities that were deemed the most desirable by head athletic trainers were trustworthiness (76.2%), honesty (73.5%), dependability (66.4%), and possessing high ethical standards (66.4%). The two characteristics that were found to be the least essential were being a risk-taker (2.1%) and being a visionary (6.4%

Knowledge Areas Necessary for Successful NCAA Division III Certified Athletic Trainers: NCAA Division III Certified Athletic Trainers’ Perceptions

NCAA Division III head certified athletic trainers (ATCs) (n=185) were surveyed to determine knowledge areas needed by ATCs to be successful as Division III ATCs. A Likert-like scale survey consisted of 12 athletic training related knowledge areas and included the following five point scale: essential, very important, important, not very important, and irrelevant. Findings indicated that it is important that Division III ATCs have all 12 knowledge areas to be successful. Although injury-related knowledge areas were considered essential, all of the knowledge areas were at least considered important to the success of ATCs, and none were considered irrelevant. Those involved in athletic training curricular issues should place or continue to place the most emphasis on areas related to injuries

BOSTON (Reino Unido) (Inglaterra). Planos de población. 1742 (1741). 1:3000

Dedicatoria : "To the Reverend Bernard Wilson DD of West Real in the County of Lincoln Prebendary of Worcester this Plan is with all due Respect Inscribed by his most Humble servts. Wm. Nichols & Rt. Hall"Escala gráfica de 20 chains de Gunter [= 13,6 cm]. Coordenadas de Boston referidas al meridiano de Londres (E 0°05'00''/N 53°02'00''). Orientado con lis en rosa de treinta y dos vientosRelación de las calles, callejuelas y principales edificios civiles y religiosos de la ciudad, indicados por clave numéricaTítulo enmarcado en cartela rococó, Dedicatoria de cartela del mismo estilo decorada con guirnaldas y coronado por escudo, probablemente de Bernard Wilson. Figura además el escudo de la ciudad y símbolos de los poderes civil y religiosoConsta el vendedor : "Sold by Thos. Grounds at the White Hart Boston"Forma parte de la Colección MendozaInserta dos perspectivas de edificios : "The Market Cross". "The South View of the Church". Cartucho con leyenda explicativa de la situación de la ciudad, sus mercados y ferias, riqueza pesquera y órganos de gobierno, así como una descripción de la iglesi

Briefing Paper on the Demand for U.S. Commodity Exports and the Mississippi River: Past and Future

As part of the decision in evaluating the lock and dam upgrade on the Mississippi River, the U.S. Army Corps of Engineers (Corps) has contracted with various agricultural forecasting companies (most recently Sparks Companies, Inc.) to produce long range projections of agricultural exports and the implied demand for Mississippi River transportation services. The future demand for barge transportation services is a key component in evaluating the value of lock and dam upgrades. In this context, it is important to understand the volume of U.S. exports that utilize the river versus other modes of transportation

Technology Directions for the 21st Century, volume 1

For several decades, semiconductor device density and performance have been doubling about every 18 months (Moore's Law). With present photolithography techniques, this rate can continue for only about another 10 years. Continued improvement will need to rely on newer technologies. Transition from the current micron range for transistor size to the nanometer range will permit Moore's Law to operate well beyond 10 years. The technologies that will enable this extension include: single-electron transistors; quantum well devices; spin transistors; and nanotechnology and molecular engineering. Continuation of Moore's Law will rely on huge capital investments for manufacture as well as on new technologies. Much will depend on the fortunes of Intel, the premier chip manufacturer, which, in turn, depend on the development of mass-market applications and volume sales for chips of higher and higher density. The technology drivers are seen by different forecasters to include video/multimedia applications, digital signal processing, and business automation. Moore's Law will affect NASA in the areas of communications and space technology by reducing size and power requirements for data processing and data fusion functions to be performed onboard spacecraft. In addition, NASA will have the opportunity to be a pioneering contributor to nanotechnology research without incurring huge expenses