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Radiative coupling of objects with outer space, through the atmospheric spectral transparency window, allows passive cooling below ambient temperature. Such passively created cold sinks can be used for converting ambient heat into other useful forms of energy. Using this approach, conversion of ambient heat to electricity has been demonstrated in macroscopic settings, where the radiatively cooled heat sink is a macroscopic object coupled with ambient heat through a heterogeneously attached, standalone, thermoelectric generator. In contrast, miniaturization and on-chip integration of such heat engines has not been demonstrated, although it could be useful in portable remote technological applications. Such integration would first require that both the radiatively cooled heat sink and the hot (ambient temperature) side of the engine are monolithically integrated on a single chip. This first step is the focus of our work: we demonstrate the creation of a local thermal gradient on-chip by radiative cooling of a 90 nm thick freestanding silicon nitride nanomechanical resonator integrated on a silicon substrate that remains at ambient temperature. The reduction in temperature of the thin film is inferred by tracking its mechanical resonance frequency, under high vacuum, using an optical fiber interferometer. Experiments were conducted on 15 different days during fall and summer months, under various solar illumination, resulting in successful radiative cooling of the membrane in each case. Maximum temperature drops of 9.3 K and 7.1 K are demonstrated during the day and night, respectively, in close correspondence with our heat transfer model. Future improvements to the experimental setup could improve the temperature reduction to 48 K for the same membrane, while emissivity engineering potentially yields a maximum theoretical cooling of 67 K with an ideal emitter.

The particle filtration efficiency (PFE) of a respirator or face mask is one of its key properties. While the physics of particle filtration results in the PFE being size-dependent, measurement standards are specified using a single, integrated PFE, for simplicity. This integrated PFE is commonly defined with respect to either the number (NBFE) or mass (MBFE) distribution of particles as a function of size. This relationship is non-trivial; it is influenced by both the shape of the particle distribution and the fact that multiple practical definitions of particle size are used. This manuscript discusses the relationship between NBFE and MBFE in detail, providing a guide to practitioners. Our discussion begins with a theoretical discussion of the underlying principles. We then present experimental results for a database of size-resolved PFE (SPFE) measurements for over 900 candidate respirators and filter media, including filter media with systematically varied properties and commercial samples that span the 20%-99.8% MBFE. The observed relationships between NBFE and MBFE are discussed in terms of the most-penetrating particle size (MPPS) and charge state of the media. For the NaCl particles used here, we observed that MBFEs were greater than NBFEs for charged materials and vice versa for uncharged materials. This relationship is observed because a shift from NBFE to MBFE weights the distribution towards larger sizes, while charged materials shift the MPPS to smaller sizes. Results are validated by comparing the output of a pair of TSI 8130As, a common instrument used in gauging standards compliance, to that of MBFEs computed from a system capable of measuring SPFE., 20 pages, 6 figures

We present a summary of the Planck constant determinations using the NRC watt balance, now referred to as the NRC Kibble balance. The summary includes a reanalysis of the four determinations performed in late 2013, as well as three new determinations performed in 2016. We also present a number of improvements and modifications to the experiment resulting in lower noise and an improved uncertainty analysis. As well, we present a systematic error that had been previously unrecognized and we have quantified its correction. The seven determinations, using three different nominal masses and two different materials, are reanalysed in a manner consistent with that used by the CODATA Task Group on Fundamental Constants (TGFC) and includes a comprehensive assessment of correlations. The result is a Planck constant of 6.626 070 133(60) ×10−34 Js and an inferred value of the Avogadro constant of 6.022 140 772(55) ×1023 mol−1. These fractional uncertainties of less than 10−8 are the smallest published to date.

The redefinition of the kilogram, along with another four of the base SI units, is scheduled for 2018. The current definition of the Si unit of mass is via the International Prototype Kilogram which is maintained and dissemination in air. The new definition, which will be from the Planck constant, involve the realisation of the mass unit in vacuum by the watt balance or Avogadro experiments. Thus, for the effective dissemination of the mass unit from the primary realisation experiments to end users, traceability of mass standards transferred between vacuum and air needs to be established and the associated uncertainties well understood. This paper describes means of achieving the link between a unit realised in vacuum and standards used in air and the ways in which their use can be optimised. It also investigates the likely uncertainty contribution introduced by the vacuum-air transfer process.

The redefinition of the kilogram is scheduled for 2018. This will be achieved by fixing the numerical value of the Planck constant with relation to the current unit of mass, as realized by the International Prototype Kilogram (IPK). The Consultative Committee for Mass and Related Quantities (CCM) has requested that, as one of the essential steps before the redefinition, a comparison of realizations based on watt balance and X-ray crystal density experiments be carried out, since these will become the primary realization experiments in the new SI. This comparison will be undertaken as a 'Pilot Study' and will be carried out during 2016. The aim of the study is to compare the future primary realizations to check their equivalence with each other and with the IPK and to develop and evaluate the protocol which will be used for future comparisons of the realization experiments after the redefinition. This will ensure the continuity of the mass unit across the redefinition and the validity of its dissemination following the redefinition. This paper outlines the basis for the comparison protocol taking into account the results of previous work evaluating transfer methods for primary mass standards. Possible future traceability routes for the kilogram from watt balance or XRCD experiments to end user requirements are also presented.

This report describes the first CCM key comparison of realizations of the kilogram definition based on the fixed numerical value of the Planck constant, which came into force on 20 May 2019. The objectives were to determine the level of agreement between realizations of the kilogram using Kibble and joule balances and the X-ray crystal density (XRCD) method and to provide input for the calculation of the first "consensus value" of the kilogram. The consensus value will serve as the basis for an internationally coordinated dissemination of the kilogram which will continue until sufficient agreement between realization experiments has been achieved. The comparison was organized by the BIPM and had seven participants. The BIPM, KRISS, NIST and NRC operated Kibble balances, the NIM used a joule balance and the NMIJ and the PTB participated using 28Si spheres, the masses of which were determined with the XRCD method. These realization methods were used to calibrate 1 kg mass standards under vacuum. The standards were sent (in air) to the BIPM where they were compared under vacuum with each other and with BIPM Pt-Ir working standards. The latter were calibrated (in air) traceable to the International Prototype of the Kilogram (IPK), the mass of which served as the definition of the kilogram until 20 May 2019. The results of the weighings at the BIPM together with the measurement results communicated by the participants allowed comparison of the values attributed to mass standards of 1 kg using the participating realization experiments. The level of agreement between mass determinations with the realization experiments and the BIPM as-maintained mass unit, traceable to the Planck constant through the mass of the International Prototype of the Kilogram can also be deduced. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

We have measured Planck's constant and have obtained a value of 6.626 070 34(12) × 10-34 J s. To our knowledge this measurement of h has the lowest uncertainty reported to date. This result has been obtained from measurements of four masses of different material and nominal values varying from 1 kg to 250 g. The experimental procedures and the measurement uncertainties are described in detail.

In March of 2012 an endstation dedicated to ambient pressure photoelectron spectroscopy (APPES) was installed at the Swiss Light Source (SLS) synchrotron radiation facility on the campus of the Paul Scherrer Institute (PSI). The endstation is mobile and operated at the vacuum ultraviolet (VUV), Surfaces/Interfaces: Microscopy (SIM) and Phoenix beamlines, which together afford a nearly continuous photon energy range from 5−8000 eV. This broad energy range is by far the widest available to a single currently operational APPES endstation. During its first five years of operation this endstation has been used to address challenging fundamental problems in the areas of soft-matter colloidal nanoscience, environmental science and energy storage—research that encompasses the liquid-nanoparticle, liquid-vapor (or vacuum) and solid-vapor interfaces. Here we present select highlights of these results and offer an outlook to the next five years of APPES research at the SLS.

Ozone is known to readily oxidize the heavier alkali halides in the form of sea salt aerosols, and this chemistry is thought to be a probable candidate for the formation of reactive gas-phase halogens in the troposphere. Water that becomes adsorbed at the interface following the oxidation process is believed to play a vital role in the mechanisms that release these gas-phase halogens. We have carried out studies that utilize X-ray photoemission spectroscopy and atomic force microscopy to follow the surface chemistry and topography of KIO3 films as they are exposed to water vapor at room temperature. The KIO3 films were grown under dry conditions by the heterogeneous reaction of ozone with a model low defect density KI(100) single crystal. As the water vapor pressure is increased above the surface dissolution point, the KIO3 layer becomes solvated and ionic mobility at the surface increases. This mobility results in a ripening process that creates large crystallites of KIO3. The inhomogeneous KIO3 layer co...

Single cell solid oxide fuel cells using Ni-YSZ and Co-YSZ anodes were tested in H2, CH4, H2S/H2 and H2S/CH4 fuel mixtures. Their performance was found to quickly degrade in dry CH4 due to carbon deposition and lifting of the anode from the electrolyte. In contrast, hydrogen or methane containing H2S showed an increase in exchange current densities when compared to H2,M/YSZ/LSM,air systems (M = Ni or Co) despite having less optimal anode microstructure. Conversion from metal to metal-sulfide in the presence of H2S produced large, dense metal-sulfide particles surrounded by YSZ, thus decreasing the triple-phase boundary. Furthermore, CoS-based anodes showed phase segregation and densification toward the electrolyte. Despite this, long-term testing at ηa = 0.5 V of the H2S/CH4,CoS-YSZ/YSZ/LSM,air system showed no signs of degradation of the anode over a 6-day period. Only after removal of H2S from the H2S/CH4 stream did the CoS-anode reduce back to Co, signifying H2S is required to maintain the metal-sulfide active anode.

Non-oxidative dehydrogenation of ethane into ethylene at 700 °C over reductively pretreated Cr–Mg–Al and Cr–Mg mixed oxide catalysts has been studied. The catalysts were prepared from layered double hydroxide (LDH) precursors that contained various species of chromium (i.e., cationic Cr(III), complex of Cr(III) with an anionic chelating agent, and chromate anion). Synthesized materials were characterized with powder X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy techniques. It was shown that the surface area of the LDH-derived mixed oxides, their catalytic performance, coking ability, and susceptibility to sintering were highly dependent on the method used for introducing chromium into the LDH precursors of the catalysts.

The surface morphology of yttria stabilized zirconia (YSZ)(1 0 0) single crystals are examined by AFM and XPS before and after thermal annealing in air to 1000 °C. The surfaces show a large variability in topography which can be categorized in three types: (1) surfaces with well defined terraces, (2) surfaces with etch pits and no visible terraces, (3) surfaces with large square or rectangular holes with flat bottoms. All three types of surfaces show a large number of defects (pits, adatoms, steps) originating from the manufacturing process, and certain samples show large nano-structured arrays of self-organized lines at step edges. The evolution of the surfaces with time at 1000 °C and with higher temperatures was studied. Terraces are ultimately obtained for all sample types at 1300 °C, but the terrace shape is affected by the original defect structure. This history dependence is attributed to defect interactions modifying the annealing process. This is true even for UHV samples prepared using sputter–anneal cycles. The surface type is found to affect the nucleation, growth and sintering behaviour of palladium deposited by electron beam evaporation. For type 3 samples the metal nucleates at step edges outside the holes to particles 6 A in height, following heating to 135 °C the particles move inside the holes forming agglomerates up to 20 A.

Preparation of mixed metal oxide precursors for solid oxide fuel cells represents a very complex chemical process in which a metal may form oxides, hydroxides and various complex basic salts as intermediates. A detailed study to determine the relationship between synthesis strategies, morphology, sinteractivity and SOFC performance is a necessity. In this work, a direct relationship has been established between the precipitation agent, the calcination process, the final composition, particle sizes, sinterability and solid oxide fuel cell (SOFC) performance for nickel, copper and cobalt based anode materials. Nickel, copper and cobalt yttria stabilized zirconia (NiYSZ, CuYSZ and CoYSZ) anode materials were synthesized via hydrolysis of the corresponding chloride solutions with NH3, NH3 + NaOH and NaOH as precipitation agents. The formation pathway was established for the various products by the direct observation of intermediate species throughout the synthesis process. A comparison of the powders indicates that the choice of precipitation agent greatly influences the final characteristics. The cobalt anodes offered the highest SOFC performance, while within each metal system, the anodes with a crystalline precursor resulted in higher exchange current densities for the charge transfer portion of the impedance spectra.

Nickel oxide yttria-stabilized zirconia (NiO–YSZ) anode materials were synthesized via hydrolysis of the corresponding chloride solutions with NH3, NH3+NaOH, and NaOH as precipitation agents. Powder properties such as crystallite size, morphology, and sintering behavior of the final NiO–YSZ materials were also studied. The mechanism of the formation of NiO–YSZ was established for the different co-precipitation techniques by the direct observation of Ni(NH3)n+2 complexes, Ni(OH)2 and NiO at different stages of the synthesis process. A direct relationship between the precipitation agent, the order of calcination from dry sample to final product, the final composition, the crystallite sizes and particle sizes of NiO, and the sinterability of the final products was established. A comparison of the powder and individual component properties indicate that the choice of precipitation agent greatly influences the final characteristics. Ni/YSZ materials prepared by NH3+NaOH precipitation offer higher Ni dispersion and nanocrystallinity of both the Ni and YSZ phases. The conductivity of both prepared materials compares well with mixed-oxide materials of higher Ni content.

We report preparations underway at the National Institute of Standards and Technology (NIST) in the United States and at the National Research Council (NRC) in Canada to support the redefinition of the international system of units (SI) and the development of a Mise en pratique for the unit of mass. NIST and the NRC possess two of the world's most precise moving coil watt balances and are developing a collaborative plan to reconcile differences between the respective measurement platforms by testing their ability to mutually realize the kilogram from the Planck constant. The important role to be played by mass metrology and new facilities, such as the NIST magnetic levitation balance and the NRC vacuum comparator, to establish the necessary link between a mass as measured in vacuum and its value in air will be considered., 2012 Conference on Precision Electromagnetic Measurements (CPEM 2012), 2012-07-1 - 2012-07-6, Washington, DC, USA

A system for quantitative measurements based on electrochemiluminescence (ECL) has recently been developed. ECL is the generation of light through a series of chemical reactions at an electrode surface using a label that is a chelate of ruthenium(II) tris(2,2′-bipyridine) (Rubpy). ECL is ideally suited for analytic procedures involving antigens or nucleic acids because of the precision, sensitivity, and accuracy of the system. In addition, assay formats which eliminate wash steps and have rapid kinetics have been developed.

This article explores the response of the probation service to the emergence of black people in the offender population. The service has a key role in the sentencing of offenders by offering courts alternatives to custody. In doing so it claims to treat all offenders alike. The article examines this contention, using evidence from interviews with probation officers. Fewer recommendations for community supervision are made by probation officers on black offenders, resulting in a disproportionate number being imprisoned. It is suggested that this discrimination against black people in sentence recommendations is due to the colour‐blind organisational response to deviance developed by the service. This response explains crime in terms of family and individual pathology, ignoring the influence of the social structure. Consequently, attempts to reintegrate offenders ignore racial disadvantage as a factor in crime. It is concluded that the probation service needs to restructure its own institutional pr...

Magnetic effects due to the passage of the Geminid meteors through the ionosphere were computed using an equation derived by Chapman and Ashour. The observed micropulsation activity at Jicamarca, Peru, and Kingston, Rhode Island, was compared with the predicted value. No striking similarity was found either in magnitude or phase. An amplitude comparison shows an observed result 150 times greater than predicted for Jicamarca and five times greater than predicted for Kingston. The best comparison of predictions with data was restricted to a phase maxima at 2300 and 0530 LT.

A theory for the rheological behavior of dilatant (shear‐thickening) fluids was developed. The theory based on physical‐chemical principles was shown to overcome the shortcomings of existing theories. In addition, it was found that the theory predicted the rheological behavior of dilatant (shear‐thickening) fluids as affected by particle size, suspending medium characteristics, temperature, and concentration.

The conduit laminar flow of dilatant (shear-thickening) fluids was investigated. It was found that such flow agreed with the Metzner-Reed (friction factor-modified Reynolds number) correlation previously verified only for pseudoplastic fluids. The agreement was found to hold even for cases where the flow behavior index was 2.0 or greater, which caused the velocity term V in the modified Reynolds number Dn′ V2−n′/gc8n−1K′ to be raised to the zero or a negative power. It was also demonstrated that conduit laminar flow for dilatant (shear-thickening) fluids could be described solely with the Metzner-Reed correlation and rheological data taken with a small-scale laboratory viscometer. Studies of flow through fittings (90-deg. elbows, globe valves, and couplings) showed a definite effect for non-Newtonian fluids contrary to previous reports for pseudoplastics which indicated essentially Newtonian behavior.

O CENTRAL IS the theme of restored spiritual beatitude to the cosmic vision of both William Blake and Dante Alighieri that it is surprising that little attempt has been made to compare their conceptions of Eternity and Paradise.' This essay will be such an attempt. Although Blake read the Divine Comedy and designed numerous illustrations for Dante's poem shortly before his death, his recorded statements do little to suggest that the two poets have much in common. Blake is reported by Henry Crabb Robinson, one of his contemporaries, as believing that Dante was "inspired by the Holy Ghost" and lives "now with God,"2 but most of his other remarks about the Italian poet indicate only antipathy.3 The illustrations themselves also make it clear