Electrolyte effects on polyacrylic acid-polyvinylpyrrolidone aqueous glycol mixtures for use as de-icing fluids

Rheological and wind tunnels measurements are presented for mixtures of polymers polyacrylic acid [PAA] and polyvinylpyrrolidone [PVP] polymers dispersed in water-1,2 propylene glycol mixture to examine their use as potential aircraft de-icing fluids. PAA solutions which form the basis of de-icing fluids are known to result in undesirable gelation which may lead to undesirable and catastrophic consequences in such applications. In this study, we examine the blending of PVP with PAA blends as alternative de-icing fluid formulations that can reduce the likelihood of forming such irreversible gel deposits. Through adjustment of the electrolyte concentration, the ratio of PAA to PVP as well as the molecular weight of PVP, it is possible to achieve a required viscosity profile to that exhibited by a model de-icing fluid across a range of appropriate temperatures. Wind tunnel tests indicate that the mixtures are capable of meeting the necessary requirements for boundary layer depletion as well as having sufficient capability of retaining a stable layer required during aircraft taxiing

The Solar X-ray Limb

We describe a new technique to measure the height of the X-ray limb with observations from occulted X-ray flare sources as observed by the RHESSI (the Reuven Ramaty High-Energy Spectroscopic Imager) satellite. This method has model dependencies different from those present in traditional observations at optical wavelengths, which depend upon detailed modeling involving radiative transfer in a medium with complicated geometry and flows. It thus provides an independent and more rigorous measurement of the "true" solar radius, meaning that of the mass distribution. RHESSI's measurement makes use of the flare X-ray source's spatial Fourier components (the visibilities), which are sensitive to the presence of the sharp edge at the lower boundary of the occulted source. We have found a suitable flare event for analysis, SOL2011-10-20T03:25 (M1.7), and report a first result from this novel technique here. Using a 4-minute integration over the 3-25 keV photon energy range, we find $R_{\mathrm{X-ray}} = 960.11\ \pm\ 0.15 \pm 0.29$ arcsec, at 1 AU, where the uncertainties include statistical uncertainties from the method and a systematic error. The standard VAL-C model predicts a value of 959.94 arcsec, about 1$\sigma$ below our value.Comment: 12 pages, 5 figures, accepted for publication in Ap

A Slight Excess of Large Scale Power from Moments of the Peculiar Velocity Field

The peculiar motions of galaxies can be used to infer the distribution of matter in the Universe. It has recently been shown that measurements of the peculiar velocity field indicates an anomalously high bulk flow of galaxies in our local volume. In this paper we find the implications of the high bulk flow for the power spectrum of density fluctuations. We find that analyzing only the dipole moment of the velocity field yields an average power spectrum amplitude which is indeed much higher than the LCDM value. However, by also including shear and octupole moments of the velocity field, and marginalizing over possible values for the growth rate, an average power spectrum amplitude which is consistent with LCDM is recovered. We attempt to infer the shape of the matter power spectrum from moments of the velocity field, and find a slight excess of power on scales ~ h-1 Gpc.Comment: 6 pages,6 figures, updated to match accepted versio

Methylmercury Production in Denitrifying Woodchip Bioreactors

Several operational woodchip bioreactors were installed at the outlets of agricultural drainage systems located in east central Illinois. The potential for monomethylmercury (MMHg) production and export in these bioreactors was investigated from summer 2008 to summer 2010. The basic approach was to compare the chemistry of simultaneously-collected bioreactor inlet and outlet water samples in order to assess the extent of nitrate depletion, consumption of sulfate, and production of MMHg, plus other low-charge mercury species (LCHg). In making such a comparison, we implicitly assume that the reactor is near steady state, which is a reasonable approximation given hydraulic residence times on the order of hours. All mercury (Hg) speciation measurements were made using a first-generation mercury thiourea complex ion chromatography system for Hg speciation analysis, which reliably separates MMHg and HgII (mercuric mercury), but combines MMHg and a newly-discovered, unidentified Hg species of low charge (LCHg). Due to this analytical artifact, the results reported here constitute an upper bound on true Hg methylation. In no season was MMHg ever detected in inlet samples at concentrations at much above the detection limit of ~0.1 ng/L. However, levels of MMHg+LCHg over 2 ng/L were observed in the outlets during warm seasons when nitrate had become depleted within the bioreactor. Sulfate depletion was also observed in most samples with elevated [MMHg+LCHg]. The combination of sulfate depletion and MMHg production is consistent with nitrate inhibition of iron and sulfate reduction and with MMHg concentrations observed in other highly anaerobic environments, e.g., lake hypolimnia and wetland porewaters. The maximum [MMHg+LCHg] observed in any given bioreactor followed an inverse function of the bioreactor loading density, i.e., the ratio of the area drained to the area of the bioreactor pit. The function has a form similar to that observed for bioreactor denitrification efficacy and suggests that optimal bioreactor designs that permit substantial denitrification while minimizing Hg methylation are feasible. Finally, extremely high MMHg+LCHg levels were observed when stagnant water conditions occurred within the bioreactors. Thus, it is recommended that bioreactors not be built with bottom depresssional areas where stagnant water can reside, in order to avoid developing anoxic conditions where methylation occurs. For the same reasons, bioreactors should not be used simultaneously with controlled drainage (water table management) if restricting the drainage results in keeping the bioreactors flooded for long periods of time.Illinois Sustainable Technology Center (Grant No. HWR09215)Ope

Extension of a theorem of Cauchy and Jacobi

AbstractLet q and p be prime with q = a2 + b2 ≡ 1 (mod 4), a ≡ 1 (mod 4), and p = qf + 1. In the nineteenth century Cauchy (Mém. Inst. France 17 (1840), 249–768) and Jacobi (J. für Math. 30 (1846), 166–182) generalized the work of earlier authors, who had determined certain binomial coefficients (mod p) (see H. J. S. Smith, “Report on the Theory of Numbers,” Chelsea, 1964), by determining two products of factorials given by Πk kf! (mod p = qf + 1) where k runs through the quadratic residues and the quadratic non-residues (mod q), respectively. These determinations are given in terms of parameters in representations of ph or of 4ph by binary quadratic forms. A remarkable feature of these results is the fact that the exponent h coincides with the class number of the related quadratic field. In this paper C. R. Mathews' (Invent. Math. 54 (1979), 23–52) recent explicit evaluation of the quartic Gauss sum is used to determine four products of factorials (mod p = qf + 1, q ≡ 5 (mod 8) > 5), given by Πk kf! where k runs through the quartic residues (mod q) and the three cosets which may be formed with respect to this subgroup. These determinations appear to be considerably more difficult. They are given in terms of parameters in representations of 16ph by quaternary quadratic forms. Stickelberger's theorem is required to determine the exponent h which is shown to be closely related to the class number of the imaginary quartic field Q(i√2q + 2a√q), q = a2 + b2 ≡ 5 (mod 8), a odd

Consistently Large Cosmic Flows on Scales of 100 Mpc/h: a Challenge for the Standard LCDM Cosmology

Peculiar velocity surveys have non-uniform spatial distributions of tracers, so that the bulk flow estimated from them does not correspond to that of a simple volume such as a sphere. Thus bulk flow estimates are generally not strictly comparable between surveys, even those whose effective depths are similar. In addition, the sparseness of typical surveys can lead to aliasing of small scale power into what is meant to be a probe of the largest scales. Here we introduce a new method of calculating bulk flow moments where velocities are weighted to give an optimal estimate of the bulk flow of an idealized survey, with the variance of the difference between the estimate and the actual flow being minimized. These "minimum variance" estimates can be designed to estimate the bulk flow on a particular scale with minimal sensitivity to small scale power, and are comparable between surveys. We compile all major peculiar velocity surveys and apply this new method to them. We find that most surveys we studied are highly consistent with each other. Taken together the data suggest that the bulk flow within a Gaussian window of radius 50 Mpc/h is 407 km/s toward l=287 and b=8. The large-scale bulk motion is consistent with predictions from the local density field. This indicates that there are significant density fluctuations on very large scales. A flow of this amplitude on such a large scale is not expected in the WMAP5-normalized LCDM cosmology, for which the predicted one-dimensional r.m.s. velocity is ~110 km/s. The large amplitude of the observed bulk flow favors the upper values of the WMAP5 error-ellipse, but even the point at the top of the WMAP5 95% confidence ellipse predicts a bulk flow which is too low compared to that observed at >98% confidence level.Comment: 19 Pages, 7 Figures, MNRAS in Press. Added some references and text to reflect post proofs manuscrip

Cosmic Flows on 100 Mpc/h Scales: Standardized Minimum Variance Bulk Flow, Shear and Octupole Moments

The low order moments, such as the bulk flow and shear, of the large scale peculiar velocity field are sensitive probes of the matter density fluctuations on very large scales. In practice, however, peculiar velocity surveys are usually sparse and noisy, which can lead to the aliasing of small scale power into what is meant to be a probe of the largest scales. Previously, we developed an optimal ``minimum variance'' (MV) weighting scheme, designed to overcome this problem by minimizing the difference between the measured bulk flow (BF) and that which would be measured by an ideal survey. Here we extend this MV analysis to include the shear and octupole moments, which are designed to have almost no correlations between them so that they are virtually orthogonal. We apply this MV analysis to a compilation of all major peculiar velocity surveys, consisting of 4536 measurements. Our estimate of the BF on scales of ~ 100 Mpc/h has a magnitude of |v|= 416 +/- 78 km/s towards Galactic l = 282 degree +/- 11 degree and b = 6 degree +/- 6 degree. This result is in disagreement with LCDM with WMAP5 cosmological parameters at a high confidence level, but is in good agreement with our previous MV result without an orthogonality constraint, showing that the shear and octupole moments did not contaminate the previous BF measurement. The shear and octupole moments are consistent with WMAP5 power spectrum, although the measurement noise is larger for these moments than for the BF. The relatively low shear moments suggest that the sources responsible for the BF are at large distances.Comment: 13 Pages, 7 figures, 4 tables. Some changes to reflect the published versio

River sediment geochemistry and provenance following the Mount Polley mine tailings spill, Canada:The role of hydraulic sorting and sediment dilution processes in contaminant dispersal and remediation

The failure of the Mount Polley tailings storage facility (TSF) in August 2014 was one of the largest magnitude failures on record, and released approximately 25 Mm3 of material, including c. 7.3 Mm3 of tailings into Hazeltine Creek, part of the Quesnel River watershed. This study evaluates the impact of the spill on the geochemistry of river channel and floodplain sediments and utilizes Pb isotope ratios and a multi-variate mixing model to establish sediment provenance. In comparison to sediment quality guidelines and background concentrations, Cu and V were found to be most elevated. Copper in river channel sediments ranged from 88-800 mg kg-1, with concentrations in sand-rich and clay/silt-rich sediments being statistically significantly different. Concentrations in river channel were believed to be influenced by hydraulic sorting during the rising and falling limbs of the flood wave caused by the tailings spill. Results highlight the importance of erosive processes, instigated by the failure, in incorporating soils and sediments into the sediment load transported and deposited within Hazeltine Creek. In this instance, these processes diluted tailings with relatively clean material that reduced metal concentrations away from the TSF failure. This does however, highlight environmental risks in similar catchments downstream of TSFs that contain metal-rich sediment within river channels and floodplain that have been contaminated by historical mining

Epoxide tannage : a way forward

An understanding of both the reactive functions of epoxide resins and collagen, suggests that some epoxides could be effectively used in organic tannage systems. As such epoxides may be regarded as alternatives to aldehydic tanning systems, having lower toxicity combined with specific polymerization ability. The commercial and technical potential of epoxides as tanning agents are assessed in this review paper. To this end, an introduction to epoxide chemistry is provided based on the tanning chemist’s viewpoint. The literature survey describes epoxide-protein/collagen addition reaction mechanisms and their kinetics, which in turn are discussed with respect to the potential for future work, where these resins will be utilised in novel tanning technology. The potential risks associated with epoxides and modifications to conventional techniques of tanning, are also discussed