Autoclave Studies of Lignite Liquefaction

The effect of time at reaction temperature on the liquefaction of lignite using hydrogen or synthesis gas was studied. A slurry contain ing 200 grams of moisture-ash-free (MAF) lignite, 100 grams of water, and 400 grams of hydrogenated anthracene oil solvent was fed into the University of North Dakota Time-Sampling Hot-Charge Batch Autoclave System with the gas at an initial pressure of 400 psig. Oil yields and conversions ranged from 0.9 percent to 35.7 percent and 66.7 percent to 90.6 percent, respectively, increasing as the time at or near the reaction temperature (380-420°C) increased. Higher con versions and greater oil and gas yields were obtained when using synthesis gas as compared to pure hydrogen. The increase in gas yield for the synthesis gas runs can be attributed to increased carbon dioxide production

Activation of type II calcium/calmodulin-dependent protein kinase by Ca^(2+)/calmodulin is inhibited by autophosphorylation of threonine within the calmodulin-binding domain

It is now well established that autophosphorylation of a threonine residue located next to each calmodulin-binding domain in the subunits of type II Ca^(2+)/calmodulin-dependent protein kinase causes the kinase to remain active, although at a reduced rate, after Ca^(2+) is removed from the reaction. This autophosphorylated form of the kinase is still sensitive to Ca2+/calmodulin, which is required for a maximum catalytic rate. After removal of Ca^(2+), new sites are autophosphorylated by the partially active kinase. Autophosphorylation of these sites abolishes sensitivity of the kinase to Ca^(2+)/calmodulin (Hashimoto, Y., Schworer, C. M., Colbran, R. J., and Soderling, T. R. (1987) J. Biol. Chem. 262, 8051-8055). We have identified two pairs of homologous residues, Thr^(305) and Ser^(314) in the alpha subunit and Thr^(306) and Ser^(315) in the beta subunit, that are autophosphorylated only after removal of Ca^(2+) from an autophosphorylation reaction. The sites were identified by direct sequencing of labeled tryptic phosphopeptides isolated by reverse-phase high pressure liquid chromatography. Thr^(305-306) is rapidly dephosphorylated by purified protein phosphatases 1 and 2A, whereas Ser^(314-315) is resistant to dephosphorylation. We have shown by selective dephosphorylation that the presence of phosphate on Thr^(305-306) blocks sensitivity of the kinase to Ca^(2+)/calmodulin. In contrast, the presence of phosphate on Ser^(314-315) is associated with an increase in the Kact for Ca^(2+)/calmodulin of only about 2-fold, producing a relatively small decrease in sensitivity to Ca^(2+)/calmodulin

Very high-current-density Nb/AlN/Nb tunnel junctions for low-noise submillimeter mixers

We have fabricated and tested submillimeter-wave superconductor–insulator–superconductor (SIS) mixers using very high-current-density Nb/AlN/Nb tunnel junctions (Jc[approximate]30 kA cm–2). The junctions have low-resistance-area products (RNA[approximate]5.6 Omega µm2), good subgap-to-normal resistance ratios Rsg/RN[approximate]10, and good run-to-run reproducibility. From Fourier transform spectrometer measurements, we infer that omegaRNC = 1 at 270 GHz. This is a factor of 2.5 improvement over what is generally available with Nb/AlOx/Nb junctions suitable for low-noise mixers. The AlN-barrier junctions are indeed capable of low-noise operation: we measure an uncorrected double-sideband receiver noise temperature of TRX = 110 K at 533 GHz for an unoptimized device. In addition to providing wider bandwidth operation at lower frequencies, the AlN-barrier junctions will considerably improve the performance of THz SIS mixers by reducing rf loss in the tuning circuits

Targeted free energy perturbation

A generalization of the free energy perturbation identity is derived, and a computational strategy based on this result is presented. A simple example illustrates the efficiency gains that can be achieved with this method.Comment: 8 pages + 1 color figur

14C-Cobalamin Absorption from Endogenously Labeled Chicken Eggs Assessed in Humans Using Accelerator Mass Spectrometry.

Traditionally, the bioavailability of vitamin B-12 (B12) from in vivo labeled foods was determined by labeling the vitamin with radiocobalt (57Co, 58Co or 60Co). This required use of penetrating radioactivity and sometimes used higher doses of B12 than the physiological limit of B12 absorption. The aim of this study was to determine the bioavailability and absorbed B12 from chicken eggs endogenously labeled with 14C-B12 using accelerator mass spectrometry (AMS). 14C-B12 was injected intramuscularly into hens to produce eggs enriched in vivo with the 14C labeled vitamin. The eggs, which provided 1.4 to 2.6 μg of B12 (~1.1 kBq) per serving, were scrambled, cooked and fed to 10 human volunteers. Baseline and post-ingestion blood, urine and stool samples were collected over a one-week period and assessed for 14C-B12 content using AMS. Bioavailability ranged from 13.2 to 57.7% (mean 30.2 ± 16.4%). Difference among subjects was explained by dose of B12, with percent bioavailability from 2.6 μg only half that from 1.4 μg. The total amount of B12 absorbed was limited to 0.5-0.8 μg (mean 0.55 ± 0.19 μg B12) and was relatively unaffected by the amount consumed. The use of 14C-B12 offers the only currently available method for quantifying B12 absorption in humans, including food cobalamin absorption. An egg is confirmed as a good source of B12, supplying approximately 20% of the average adult daily requirement (RDA for adults = 2.4 μg/day)

A 275–425-GHz Tunerless Waveguide Receiver Based on AlN-Barrier SIS Technology

We report on a 275–425-GHz tunerless waveguide receiver with a 3.5–8-GHz IF. As the mixing element, we employ a high-current-density Nb–AlN–Nb superconducting–insulating– superconducting (SIS) tunnel junction. Thanks to the combined use of AlN-barrier SIS technology and a broad bandwidth waveguide to thin-film microstrip transition, we are able to achieve an unprecedented 43% instantaneous bandwidth, limited by the receiver's corrugated feedhorn. The measured double-sideband (DSB) receiver noise temperature, uncorrected for optics loss, ranges from 55 K at 275 GHz, 48 K at 345 GHz, to 72 K at 425 GHz. In this frequency range, the mixer has a DSB conversion loss of 2.3 1 dB. The intrinsic mixer noise is found to vary between 17–19 K, of which 9 K is attributed to shot noise associated with leakage current below the gap. To improve reliability, the IF circuit and bias injection are entirely planar by design. The instrument was successfully installed at the Caltech Submillimeter Observatory (CSO), Mauna Kea, HI, in October 2006

The Potential Trajectory of Carbapenem-Resistant Enterobacteriaceae, an Emerging Threat to Health-Care Facilities, and the Impact of the Centers for Disease Control and Prevention Toolkit.

Carbapenem-resistant Enterobacteriaceae (CRE), a group of pathogens resistant to most antibiotics and associated with high mortality, are a rising emerging public health threat. Current approaches to infection control and prevention have not been adequate to prevent spread. An important but unproven approach is to have hospitals in a region coordinate surveillance and infection control measures. Using our Regional Healthcare Ecosystem Analyst (RHEA) simulation model and detailed Orange County, California, patient-level data on adult inpatient hospital and nursing home admissions (2011-2012), we simulated the spread of CRE throughout Orange County health-care facilities under 3 scenarios: no specific control measures, facility-level infection control efforts (uncoordinated control measures), and a coordinated regional effort. Aggressive uncoordinated and coordinated approaches were highly similar, averting 2,976 and 2,789 CRE transmission events, respectively (72.2% and 77.0% of transmission events), by year 5. With moderate control measures, coordinated regional control resulted in 21.3% more averted cases (n = 408) than did uncoordinated control at year 5. Our model suggests that without increased infection control approaches, CRE would become endemic in nearly all Orange County health-care facilities within 10 years. While implementing the interventions in the Centers for Disease Control and Prevention's CRE toolkit would not completely stop the spread of CRE, it would cut its spread substantially, by half

Line-profile tomography of exoplanet transits - I. The Doppler shadow of HD 189733b

The misalignment between the orbital plane of a transiting exoplanet and the spin axis of its host star provides important insights into the system's dynamical history. The amplitude and asymmetry of the radial-velocity distortion during a planetary transit [the Rossiter-McLaughlin (R-M) effect] depend on the projected stellar rotation rate v sin I and misalignment angle λ, where the stellar rotation axis is inclined at angle I to the line of sight. The parameters derived from modelling the R-M effect have, however, been found to be prone to systematic errors arising from the time-variable asymmetry of the stellar spectral lines during transit. Here, we present a direct method for isolating the component of the starlight blocked by a planet as it transits the host star, and apply it to spectra of the bright transiting planet HD 189733b. We model the global shape of the stellar cross-correlation function as the convolution of a limb-darkened rotation profile and a Gaussian representing the Doppler core of the average photospheric line profile. The light blocked by the planet during the transit is a Gaussian of the same intrinsic width, whose trajectory across the line profile yields a precise measure of the misalignment angle and an independent measure of v sin I. We show that even when v sin I is less than the width of the intrinsic line profile, the travelling Doppler ‘shadow' cast by the planet creates an identifiable distortion in the line profiles which is amenable to direct modelling. Direct measurement of the trajectory of the missing starlight yields self-consistent measures of the projected stellar rotation rate, the intrinsic width of the mean local photospheric line profile, the projected spin-orbit misalignment angle and the system's centre-of-mass velocity. Combined with the photometric rotation period, the results give a geometrical measure of the stellar radius which agrees closely with values obtained from high-precision transit photometry if a small amount of differential rotation is present in the stellar photospher

A new approach to generating research-quality data through citizen science: The USA National Phenology Monitoring System

Phenology is one of the most sensitive biological responses to climate change, and recent changes in phenology have the potential to shake up ecosystems. In some cases, it appears they already are. Thus, for ecological reasons it is critical that we improve our understanding of species’ phenologies and how these phenologies are responding to recent, rapid climate change. Phenological events like flowering and bird migrations are easy to observe, culturally important, and, at a fundamental level, naturally inspire human curiosity— thus providing an excellent opportunity to engage citizen scientists. The USA National Phenology Network has recently initiated a national effort to encourage people at different levels of expertise—from backyard naturalists to professional scientists—to observe phenological events and contribute to a national database that will be used to greatly improve our understanding of spatio-temporal variation in phenology and associated phenological responses to climate change.

Traditional phenological observation protocols identify specific dates at which individual phenological events are observed. The scientific usefulness of long-term phenological observations could be improved with a more carefully structured protocol. At the USA-NPN we have developed a new approach that directs observers to record each day that they observe an individual plant, and to assess and report the state of specific life stages (or phenophases) as occurring or not occurring on that plant for each observation date. Evaluation is phrased in terms of simple, easy-to-understand, questions (e.g. “Do you see open flowers?”), which makes it very appropriate for a citizen science audience. From this method, a rich dataset of phenological metrics can be extracted, including the duration of a phenophase (e.g. open flowers), the beginning and end points of a phenophase (e.g. traditional phenological events such as first flower and last flower), multiple distinct occurrences of phenophases within a single growing season (e.g multiple flowering events, common in drought-prone regions), as well as quantification of sampling frequency and observational uncertainties. These features greatly enhance the utility of the resulting data for statistical analyses addressing questions such as how phenological events vary in time and space, and in response to global change. This new protocol is an important step forward, and its widespread adoption will increase the scientific value of data collected by citizen scientists.
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