Infrared spectroscopic study of absorption and separation of CO using copper(I)-containing ionic liquids

Absorption of carbon monoxide by copper(I)-containing ionic liquids, [Cnmim][CuX2] (Cnmim = 1-alkyl-3-methylimidazolium, n = 2, 4, 6, X = Cl, Br, I) has been investigated using in situ high pressure infrared spectroscopy. For each liquid, observation of a ν(CO) band in the region 2075–2090 cm−1 indicates the formation of copper(I) monocarbonyl complexes, assigned as [Cu(CO)X2]−. The rate of growth and equilibrium intensity of the ν(CO) absorption is dependent on applied CO pressure. Binding of CO is reversible such that complete desorption occurs rapidly on heating above 100 °C and the liquids are robust over multiple gas absorption/desorption cycles. For the series of [C6mim][CuX2] salts the CO absorption ability follows the order Cl ≥ Br ≫ I. Selective absorption of CO from CO/H2 and CO/N2 gas mixtures is demonstrated by measuring the changes in headspace CO content upon absorption and desorption of gas. For [C6mim][CuCl2], a single absorb–vent–desorb cycle yields product gas containing ∼95% CO starting from a 1 : 1 CO/N2 mixture, increasing to ∼98% CO starting from a 4 : 1 CO/N2 mixture. This is particularly promising in view of the similar boiling points of CO and N2 that hinders their separation by cryogenic distillation

Continuation-Passing C: compiling threads to events through continuations

In this paper, we introduce Continuation Passing C (CPC), a programming language for concurrent systems in which native and cooperative threads are unified and presented to the programmer as a single abstraction. The CPC compiler uses a compilation technique, based on the CPS transform, that yields efficient code and an extremely lightweight representation for contexts. We provide a proof of the correctness of our compilation scheme. We show in particular that lambda-lifting, a common compilation technique for functional languages, is also correct in an imperative language like C, under some conditions enforced by the CPC compiler. The current CPC compiler is mature enough to write substantial programs such as Hekate, a highly concurrent BitTorrent seeder. Our benchmark results show that CPC is as efficient, while using significantly less space, as the most efficient thread libraries available.Comment: Higher-Order and Symbolic Computation (2012). arXiv admin note: substantial text overlap with arXiv:1202.324

Perceived barriers and facilitators to participating in the North Carolina Healthy Food Small Retailer Program: a mixed-methods examination considering investment effectiveness

Objective: The North Carolina Legislature appropriated funds in 2016-2019 for the Healthy Food Small Retailer Program (HFSRP), providing small retailers located in food deserts with equipment to stock nutrient-dense foods and beverages. The study aimed to: (1) examine factors facilitating and constraining implementation of, and participation in, the HFSRP from the perspective of storeowners and (2) measure and evaluate the impact and effectiveness of investment in the HFSRP. Design: The current analysis uses both qualitative and quantitative assessments of storeowner perceptions and store outcomes, as well as two innovative measures of policy investment effectiveness. Qualitative semi-structured interviews and descriptive quantitative approaches, including monthly financial reports and activity forms, and end-of-programme evaluations were collected from participating HFSRP storeowners. Setting: Eight corner stores in North Carolina that participated in the two cohorts (2016-2018; 2017-2019) of the HFSRP. Participants: Owners of corner stores participating in the HFSRP. Results: All storeowners reported that the HFSRP benefitted their stores. In addition, the HFSRP had a positive impact on sales across each category of healthy food products. Storeowners reported that benefits would be enhanced with adjustments to programme administration and support. Specific suggestions included additional information regarding which healthy foods and beverages to stock; inventory management; handling of perishable produce; product display; modified reporting requirements and a more efficient process of delivering and maintaining equipment. Conclusions: All storeowners reported several benefits of the HFSRP and would recommend that other storeowners participate. The barriers and challenges they reported inform potential approaches to ensuring success and sustainability of the HFSRP and similar initiatives underway in other jurisdictions

Measurement of the B-Meson Inclusive Semileptonic Branching Fraction and Electron-Energy Moments

We report a new measurement of the B-meson semileptonic decay momentum spectrum that has been made with a sample of 9.4/fb of electron-positron annihilation data collected with the CLEO II detector at the Y(4S) resonance. Electrons from primary semileptonic decays and secondary charm decays were separated by using charge and angular correlations in Y(4S) events with a high-momentum lepton and an additional electron. We determined the semileptonic branching fraction to be (10.91 +- 0.09 +- 0.24)% from the normalization of the electron-energy spectrum. We also measured the moments of the electron energy spectrum with minimum energies from 0.6 GeV to 1.5 GeV.Comment: 36 pages postscript, als available through http://w4.lns.cornell.edu/public/CLNS/, Submitted to PRD (back-to-back with preceding preprint hep-ex/0403052

Flux-rope twist in eruptive flares and CMEs : due to zipper and main-phase reconnection

Funding: UK Science and Technology Facilities CouncilThe nature of three-dimensional reconnection when a twisted flux tube erupts during an eruptive flare or coronal mass ejection is considered. The reconnection has two phases: first of all, 3D “zipper reconnection” propagates along the initial coronal arcade, parallel to the polarity inversion line (PIL); then subsequent quasi-2D “main phase reconnection” in the low corona around a flux rope during its eruption produces coronal loops and chromospheric ribbons that propagate away from the PIL in a direction normal to it. One scenario starts with a sheared arcade: the zipper reconnection creates a twisted flux rope of roughly one turn (2π radians of twist), and then main phase reconnection builds up the bulk of the erupting flux rope with a relatively uniform twist of a few turns. A second scenario starts with a pre-existing flux rope under the arcade. Here the zipper phase can create a core with many turns that depend on the ratio of the magnetic fluxes in the newly formed flare ribbons and the new flux rope. Main phase reconnection then adds a layer of roughly uniform twist to the twisted central core. Both phases and scenarios are modeled in a simple way that assumes the initial magnetic flux is fragmented along the PIL. The model uses conservation of magnetic helicity and flux, together with equipartition of magnetic helicity, to deduce the twist of the erupting flux rope in terms the geometry of the initial configuration. Interplanetary observations show some flux ropes have a fairly uniform twist, which could be produced when the zipper phase and any pre-existing flux rope possess small or moderate twist (up to one or two turns). Other interplanetary flux ropes have highly twisted cores (up to five turns), which could be produced when there is a pre-existing flux rope and an active zipper phase that creates substantial extra twist.PostprintPublisher PDFPeer reviewe

First Observation of a Upsilon(1D) State

We present the first evidence for the production of Upsilon(1D) states in the four-photon cascade, Upsilon(3S)-->gamma chib(2P), chib(2P)-->gamma Upsilon(1D), Upsilon(1D)-->gamma chib(1P), chib(1P)-->gamma Upsilon(1S), followed by the Upsilon(1S) annihilation into e+e- or mu+mu-. The signal has a significance of 10.2 standard deviations. The measured product branching ratio for these five decays, (2.5+-0.5+-0.5)x10^(-5), is consistent with the theoretical estimates. The data are dominated by the production of one Upsilon(1D) state consistent with the J=2 assignment. Its mass is determined to be (10161.1+-0.6+-1.6) MeV, which is consistent with the predictions from potential models and lattice QCD calculations. We also searched for Upsilon(3S)-->gammachib(2P), chib(2P)-->gammaUpsilon(1D), followed by either Upsilon(1D)-->eta Upsilon(1S) or Upsilon(1D)-->pi+pi- Upsilon(1S). We find no evidence for such decays and set upper limits on the product branching ratios.Comment: 12 pages postscript,also available through this http://w4.lns.cornell.edu/public/CLNS/, submitted to PR