Coherent matter wave inertial sensors for precision measurements in space

We analyze the advantages of using ultra-cold coherent sources of atoms for matter-wave interferometry in space. We present a proof-of-principle experiment that is based on an analysis of the results previously published in [Richard et al., Phys. Rev. Lett., 91, 010405 (2003)] from which we extract the ratio h/m for 87Rb. This measurement shows that a limitation in accuracy arises due to atomic interactions within the Bose-Einstein condensate

Comparative cradle-to-gate energy assessment of indium phosphide and cadmium selenide quantum dot displays

Quantum dots (QDs) are semiconductor nanocrystals (2–10 nm) with tunable band gaps and desirable luminescence properties. QDs have created great interest in consumer electronics, photovoltaics, and chemical and/or biological sensor applications. For example, QDs absorb short wavelength light and emit light with a desired wavelength, making them ideal for LCD displays. QDs are just beginning to be used in mass-produced displays, including products such as televisions, tablets, and smartphones. The most widely applied QD composition—a CdSe core metalloid complex (CdQD)—faces increasing environmental and regulatory scrutiny because cadmium and selenium nanomaterials pose uncertain human health and environmental risks. As a result, some manufacturers have introduced InP-based (InQD) displays, which have been shown to be less toxic than CdQDs. However, instead of basing environmental decisions on material hazard alone, it is important to take a more holistic approach to avoid unintended consequences. This paper presents a comparative cradle-to-gate life cycle environmental assessment of CdQD- and InQD-enabled displays. In this study, we compare the cumulative energy demand (CED), also referred to as the primary energy consumption, of colloidally synthesized CdSe and InP multishell QDs, and their subsequent incorporation in different display types. Additionally, we compare the CED for the two competing commercially available QD display technologies: on-surface and on-edge. Lastly, we estimate the energy repercussion of large-scale adoption of each of the production pathways for QD display manufacture. The results show that InP QD-enabled displays are far more energy intensive than the CdSe QD displays, and this difference becomes further amplified when large-scale adoption is considered. Our study highlights that life cycle thinking is essential for recognizing opportunities to advance QD production along environmentally sustainable pathways, which is critical information for researchers, QD display manufacturers, and regulatory agencies

Comparison of NDA and DA measurement techniques for excess plutonium powders at the Hanford Site: Statistical design and heterogeneity testing

Quantitative physical measurements are a n component of the International Atomic Energy Agency (IAEA) nuclear material m&guards verification regime. In December 1994, LA.FA safeguards were initiated on an inventory of excess plutonium powder items at the Plutonium Finishing Plant, Vault 3, on the US Department of Energy`s Hanford Site. The material originl from the US nuclear weapons complex. The diversity of the chemical form and the heterogenous physical form of this inventory were anticipated to challenge the precision and accuracy of quantitative destructive analytical techniques. A sampling design was used to estimate the degree of heterogeneity of the plutonium content of a variety of inventory items. Plutonium concentration, the item net weight, and the {sup 240}Pu content were among the variables considered in the design. Samples were obtained from randomly selected location within each item. Each sample was divided into aliquots and analyzed chemically. Operator measurements by calorimetry and IAEA measurements by coincident neutron nondestructive analysis also were performed for the initial physical inventory verification materials and similar items not yet under IAEA safeguards. The heterogeneity testing has confirmed that part of the material is indeed significantly heterogeneous; this means that precautionary measures must be taken to obtain representative samples for destructive analysis. In addition, the sampling variability due to material heterogeneity was found to be comparable with, or greater than, the variability of the operator`s calorimetric measurements