Body temperatures of modern and extinct vertebrates from ^(13)C-^(18)O bond abundances in bioapatite

The stable isotope compositions of biologically precipitated apatite in bone, teeth, and scales are widely used to obtain information on the diet, behavior, and physiology of extinct organisms and to reconstruct past climate. Here we report the application of a new type of geochemical measurement to bioapatite, a “clumped-isotope” paleothermometer, based on the thermodynamically driven preference for ^(13)C and ^(18)O to bond with each other within carbonate ions in the bioapatite crystal lattice. This effect is dependent on temperature but, unlike conventional stable isotope paleothermometers, is independent from the isotopic composition of water from which the mineral formed. We show that the abundance of ^(13)C-^(18)O bonds in the carbonate component of tooth bioapatite from modern specimens decreases with increasing body temperature of the animal, following a relationship between isotope “clumping” and temperature that is statistically indistinguishable from inorganic calcite. This result is in agreement with a theoretical model of isotopic ordering in carbonate ion groups in apatite and calcite. This thermometer constrains body temperatures of bioapatite-producing organisms with an accuracy of 1–2 °C. Analyses of fossilized tooth enamel of both Pleistocene and Miocene age yielded temperatures within error of those derived from similar modern taxa. Clumped-isotope analysis of bioapatite represents a new approach in the study of the thermophysiology of extinct species, allowing the first direct measurement of their body temperatures. It will also open new avenues in the study of paleoclimate, as the measurement of clumped isotopes in phosphorites and fossils has the potential to reconstruct environmental temperatures

Investigation of the Viability of Thermographic Phosphor as a Sensing Mechanism for Structural Damage in Aerogel and PDMS

Detecting structural damage in a material before complete failure has been a challenge with respect to material access, sensing mechanism resolution, and environmental setting, among other factors. In this work, the feasibility of using thermographic phosphors as a non-contact, instantaneous, and customizable sensing mechanism for detection of structural damage was investigated. The two materials were (1) Sylgard 184 elastomer and (2) silica aerogels. Both materials were impregnated with thermographic phosphors using different methods and tested over a wide range of temperatures. The degree of fracture in either material was gradually increased to represent a complete material failure scenario and a gradual propagation of defect that has not yet led to ultimate failure. The aerogel synthesis methodology was optimized for phosphor application so that either a discrete layer of phosphor would be embedded or a homogeneous mix was created and phoshpor was distributed uniformly throughout the material. The discreteness of the phosphor layer was identified by two distinct points representing the entrance and exit points of the excitation and emission beams. The composite materials (homogeneous and otherwise) were fully characterized, and the sensitivity of the remote, non-contact sensing was evaluated. It was determined that fracture and failure in both aerogel and PDMS could be detected by phosphor thermometry and the limit of its resolution was ultimately determined by the thermal properties of the material, the choice of phosphors, and ambient temperature. In conclusion, thermogrpahic phosphor powders were successfully incorporated at discrete levels and superficially in aerogels and in PDMS materials and as a result can be used as means to interrogate the bulk of the material. Phosphor thermometry proved to be a viable option for remotely identifying structural defects in these two materials, with limitations. The changes in the thermal profile of the materials as a result of material defects were used to infer information about the structural health of the matierla

Register of hydrogen technology experts

This register presents the names of approximately 235 individuals who are considered experts, or very knowledgeable, in various fields of technology related to hydrogen. Approximately 90 organizations are represented. Each person is listed by organizational affiliation, address, and principal area of expertise. The criteria for selection of names for the register are extensive experience in a given field of work, participation in or supervision of relevant research programs, contributions to the literature, or being recognized as an expert in a particular field. The purpose of the register is to present, in easy form, sources of dependable information regarding highly technical areas of hydrogen technology, with particular emphasis on safety. The register includes two indexes: an alphabetical listing of the experts and an alphabetical listing of the organizations with which they are affiliated

Ultracold Neutron Production in a Pulsed Neutron Beam Line

We present the results of an Ultracold neutron (UCN) production experiment in a pulsed neutron beam line at the Los Alamos Neutron Scattering Center. The experimental apparatus allows for a comprehensive set of measurements of UCN production as a function of target temperature, incident neutron energy, target volume, and applied magnetic field. However, the low counting statistics of the UCN signal expected can be overwhelmed by the large background associated with the scattering of the primary cold neutron flux that is required for UCN production. We have developed a background subtraction technique that takes advantage of the very different time-of-flight profiles between the UCN and the cold neutrons, in the pulsed beam. Using the unique timing structure, we can reliably extract the UCN signal. Solid ortho-D$_2$ is used to calibrate UCN transmission through the apparatus, which is designed primarily for studies of UCN production in solid O$_2$. In addition to setting the overall detection efficiency in the apparatus, UCN production data using solid D$_2$ suggest that the UCN upscattering cross-section is smaller than previous estimates, indicating the deficiency of the incoherent approximation widely used to estimate inelastic cross-sections in the thermal and cold regimes

Review of industrial temperature measurement technologies and research priorities for the thermal characterisation of the factories of the future

As the largest source of dimensional measurement uncertainty, addressing the challenges of thermal variation is vital to ensure product and equipment integrity in the factories of the future. While it is possible to closely control room temperature, this is often not practical or economical to realise in all cases where inspection is required. This article reviews recent progress and trends in seven key commercially available industrial temperature measurement sensor technologies primarily in the range of 0 °C–50 °C for invasive, semi-invasive and non-invasive measurement. These sensors will ultimately be used to measure and model thermal variation in the assembly, test and integration environment. The intended applications for these technologies are presented alongside some consideration of measurement uncertainty requirements with regard to the thermal expansion of common materials. Research priorities are identified and discussed for each of the technologies as well as temperature measurement at large. Future developments are briefly discussed to provide some insight into which direction the development and application of temperature measurement technologies are likely to head

Use of Clumped-Isotope Thermometry To Constrain the Crystallization Temperature of Diagenetic Calcite

We describe an approach to estimating the crystallization temperatures of diagenetic calcites using clumped-isotope thermometry, a paleothermometer based on the ^(13)C–^(18)O-bond enrichment in carbonates. Application of this thermometer to calcified gastropod shells and calcite cements in an early Eocene limestone from the Colorado Plateau reveals a record of calcite precipitation and replacement at temperatures varying from 14 to 123°C. The early Eocene host sediments were never deeply buried, but they experienced a significant thermal pulse associated with the emplacement of a late Miocene basalt flow. The combination of independent constraints on thermal history with clumped-isotope thermometry, petrographic (including cathodoluminescence) observations, and oxygen isotopic data provides an improved basis for estimation of the temperature and timing of diagenetic events and fluid sources. The petrography and calcite δ^(18)O values, taken alone, suggest that the aragonite-to-calcite transformation of gastropod shell material occurred simultaneously with early formation of cements and lithification of the matrix in the same sample. However, addition of clumped-isotope thermometry demonstrates that this phase transformation of shell material occurred at temperatures of 94–123°C in a highly rock-buffered microenvironment (i.e., with the isotopic composition of fluid buffered by coexisting carbonate), millions of years after lithification of the matrix and formation of initial low-temperature (14–19°C) calcite cements within shell body cavities. Clumped-isotope temperatures in excess of reasonable Earth-surface conditions recorded by later-formed cements demand that cement growth occurred in association with the lava emplacement. Our results illustrate the potential for clumped-isotope thermometry to constrain conditions of diagenesis and guide interpretations that would not be possible on the basis of conventional stable-isotopic and petrographic data alone, and demonstrate how petrographic characterization of clumped-isotope thermometry samples can benefit paleoclimate studies

NASA's Microgravity Technology Report, 1996: Summary of Activities

This report covers technology development and technology transfer activities within the Microgravity Science Research Programs during FY 1996. It also describes the recent major tasks under the Advanced Technology Development (ATD) Program and identifies current technology requirements. This document is consistent with NASA,s Enteprise for the Human Exploration and development of Space (HEDS) Strategic Plan. This annual update reflects changes in the Microgravity Science Research Program's new technology activities and requirements. Appendix A. FY 1996 Advanced Technology Development. Program and Project Descriptions. Appendix B. Technology Development

Mechanical and tribological investigation of thin film coatings onto flexible polymeric substrate

Elastomers of the polydimethylsiloxane family are paramount to science and engineering due to their useful properties. Much work has gone into characterizing these polymers to optimize their performance. However, at this time there is little published literature dedicated to understanding and controlling its frictional behavior.In this study, Sylgard was characterized as a function of crosslinker ratio and curing temperature, then coated with Silastic using two different techniques resulting in a bilayer. The bilayer was characterized both in bulk and surface properties, and those results compared between techniques and uncoated Sylgard.It was demonstrated that spin coating can produce a well-bonded topcoat that possesses significantly lower frictional force than that of Sylgard alone at ambient and cryogenic temperatures. Changes in other properties were also quantified. This technique of PDMS surface modification may reduce the need of lubricants in mobile joints and extend component lifetime by shielding it from friction wear

“Vital effects" in the 13C-18O clumped isotopic composition of marine macro-invertebrates: exploring biologically mediated disequilibrium effects in echinoids and cephalopods

The stable oxygen isotopic composition of marine carbonate has historically been widely used for paleoclimate reconstruction (Emiliani 1955; Zachos 2001). This technique however applies an a priori assumption of δ18O of the seawater. Furthermore, while the stable oxygen isotopic composition of some taxa faithfully reflects both the temperature and the δ18Oseawater other taxa show specific discrepancies known as “vital effects” (Epstein et al. 1951). The carbonate clumped isotope paleothermometer examines thermodynamically dependent “clumping” of 13C and 18O within the carbonate crystal lattice. This allows calculation of carbonate formation temperature independent of the δ18O of seawater (Ghosh et al. 2006; Eiler 2007). Initially inorganic and biogenic calibrations of the clumped isotope thermometer appeared reasonably congruent (Eiler 2011, Ghosh et al. 2006; Tripati et al. 2010a). Further studies however revealed vital effects in the clumped isotopic composition of corals (Thiagarajan et al. 2011; Saenger et al. 2012) with potential vital effects indicated in molluscs (Henkes et al. 2013). In this study we assess how robust the clumped isotope thermometer is to biologically mediated non-equilibrium precipitation (vital effects) by (1) measuring the clumped isotope composition of the previously uninvestigated echinoderm group and (2) verifying and further quantifying offsets in the clumped isotope composition of modern cephalopod molluscs. This aim necessitated further refinements CO2 purification for clumped isotope analysis, also presented within this thesis. The results of this thesis indicate that non-equilibrium signatures in the clumped isotope composition of biogenic materials are more common than initially assumed (Eiler, 2011). Furthermore the manifestation of vital effects does not to occur by a single mechanism, but varies dependent on biomineralization pathway. This has significant implications for the way in which the clumped isotope composition of biogenic carbonate is used in paleoclimate reconstruction. We can no longer unreservedly assume equilibrium precipitation in the 13C-18O composition of biogenic carbonate necessitating the creation of group specific calibrations using modern genera prior to the use of previously unmeasured groups in paloeclimatic reconstruction. Small non-equilibirum offsets in the 13C-18O compositions in echinoids may be corrected. Nautili however display inter-individual variation in 13C-18O such that correction for non-equilbirum effects may be not be possible, precluding the use of the clumped isotopic composition of groups such as the ammonites in paleoclimatic reconstruction.Open Acces

Superconducting RF Technology R&D for Future Accelerator Applications

Superconducting rf technology (SRF) is evolving rapidly as are its applications. While there is active exploitation of what one may term the current state-of-the-practice, there is also rapid progress expanding in several dimensions the accessible and useful parameter space. While state-of-the-art performance sometimes outpaces thorough understanding, the improving scientific understanding from active SRF research is clarifying routes to obtain optimum performance from present materials and opening avenues beyond the standard bulk niobium. The improving technical basis understanding is enabling process engineering to both improve performance confidence and reliability and also unit implementation costs. Increasing confidence in the technology enables the engineering of new creative application designs. We attempt to survey this landscape to highlight the potential for future accelerator applications.Comment: Submitted to Reviews of Accelerator Science and Technolog