Competing Magnetic Fluctuations in Iron Pnictide Superconductors: Role of Ferromagnetic Spin Correlations Revealed by NMR

In the iron pnictide superconductors, theoretical calculations have consistently shown enhancements of the static magnetic susceptibility at both the stripe-type antiferromagnetic (AFM) and in-plane ferromagnetic (FM) wavevectors. However, the possible existence of FM fluctuations has not yet been examined from a microscopic point of view. Here, using $^{75}$As NMR data, we provide clear evidence for the existence of FM spin correlations in both the hole- and electron-doped BaFe$_2$As$_2$ families of iron-pnictide superconductors. These FM fluctuations appear to compete with superconductivity and are thus a crucial ingredient to understanding the variability of $T_{\rm c}$ and the shape of the superconducting dome in these and other iron-pnictide families.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. Let

The Volunteer Fisheries Liaison Officer (VFLO) program: an analysis of recreational fishing data from 1995 - 2007

The aim of this report was to explore the data collected by VFLOs from 1995 - 2007 in each of the state’s four marine bioregions. During this period, volunteers undertook \u3e2,000 days of activities, the majority of which were educational displays at events such as boat shows and patrols in coastal, marine and estuarine environs. Patrols focused on interviews with recreational anglers to provide information about sustainable fishing and collect data on catch and effort

Enhancing Water Removal from Whole Stillage by Enzyme Addition during Fermentation

The Removal of Water from Coproducts in the Fuel Ethanol Process Requires a Significant Energy Input. in This Study, the Addition of Commercially Available Cell-Wall-Degrading Enzymes Was Investigated to Determine Whether or Not the Enzymes Could Reduce the Amount of Water Bound within the Wet Grains. This Would Have the Effect of Allowing More Water to Be Removed during Centrifugation, Reducing the Time and Energy Needed during the Drying Process. the Experiment Screened 15 Cell-Wall-Degrading Enzyme Preparations. a Significant Reduction in Water-Binding Capacity Was Found for a Number of Enzymes Tested in the Initial Screening. the Experiment Was Repeated and Two Enzymes Were Identified to Have the Highest Whole Stillage Dewatering Effect, 15 and 14% More Water Removed for Enzyme Preparations a and G, respectively. Adding Different Enzyme Preparation Amounts to the Mash Showed Varying Effects, with the Potential to Allow for an Optimization of Enzymes Cost and Energy Savings. in Some Cases, an Enzyme Dosage of 0.5 ML Worked as Well, If Not Better, Than a Dosage of 1 ML. These Results Can Translate into Improvements in the overall Energy Efficiency of the Process Because the Wet Grains Entering the Drier Would Contain Less Moisture Than in the Conventional Process Thus Requiring a Shorter Residence Time in the Drier

Enzymatic corn wet milling: engineering process and cost model

<p>Abstract</p> <p>Background</p> <p>Enzymatic corn wet milling (E-milling) is a process derived from conventional wet milling for the recovery and purification of starch and co-products using proteases to eliminate the need for sulfites and decrease the steeping time. In 2006, the total starch production in USA by conventional wet milling equaled 23 billion kilograms, including modified starches and starches used for sweeteners and ethanol production <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>. Process engineering and cost models for an E-milling process have been developed for a processing plant with a capacity of 2.54 million kg of corn per day (100,000 bu/day). These models are based on the previously published models for a traditional wet milling plant with the same capacity. The E-milling process includes grain cleaning, pretreatment, enzymatic treatment, germ separation and recovery, fiber separation and recovery, gluten separation and recovery and starch separation. Information for the development of the conventional models was obtained from a variety of technical sources including commercial wet milling companies, industry experts and equipment suppliers. Additional information for the present models was obtained from our own experience with the development of the E-milling process and trials in the laboratory and at the pilot plant scale. The models were developed using process and cost simulation software (SuperPro Designer^®) and include processing information such as composition and flow rates of the various process streams, descriptions of the various unit operations and detailed breakdowns of the operating and capital cost of the facility.</p> <p>Results</p> <p>Based on the information from the model, we can estimate the cost of production per kilogram of starch using the input prices for corn, enzyme and other wet milling co-products. The work presented here describes the E-milling process and compares the process, the operation and costs with the conventional process.</p> <p>Conclusion</p> <p>The E-milling process was found to be cost competitive with the conventional process during periods of high corn feedstock costs since the enzymatic process enhances the yields of the products in a corn wet milling process. This model is available upon request from the authors for educational, research and non-commercial uses.</p

Cobalt-catalyzed Wagner–Meerwein rearrangements with concomitant nucleophilic hydrofluorination

The authors acknowledge funding from the Royal Society (University Research Fellowship URF\R1\180017 (CPJ) and associated Enhancement Award RGF\EA\181022 (CPJ and RHH)), and the EaSI-CAT Centre for Doctoral Training (RHH and NM).We report a cobalt-catalyzed Wagner-Meerwein rearrangement of gem-disubstituted allylarenes that generates fluoroalkane products with isolated yields up to 84%. Modification of the counteranion of the N-fluoropyridinium oxidant suggests the substrates undergo nucleophilic fluorination during the reaction. Subjecting the substrates to other known metal-mediated hydrofluorination procedures did not lead to observable 1,2-aryl migration. Thus, indicating the unique ability of these cobalt-catalyzed conditions to generate a sufficiently reactive electrophilic intermediate capable of promoting this Wagner-Meerwein rearrangement.Publisher PDFPeer reviewe

Tidal Streams as Probes of the Galactic Potential

We explore the use of tidal streams from Galactic satellites to recover the potential of the Milky Way. Our study is motivated both by the discovery of the first lengthy stellar stream in the halo (\cite{it98}) and by the prospect of measuring proper motions of stars brighter than 20th magnitude in such a stream with an accuracy of $\sim 4\mu as/$yr, as will be possible with the Space Interferometry Mission (SIM). We assume that the heliocentric radial velocities of these stars can be determined from supporting ground-based spectroscopic surveys, and that the mass and phase-space coordinates of the Galactic satellite with which they are associated will also be known to SIM accuracy. Using results from numerical simulations as trial data sets, we find that, if we assume the correct form for the Galactic potential, we can predict the distances to the stars as a consequence of the narrow distribution of energy expected along the streams. We develop an algorithm to evaluate the accuracy of any adopted potential by requiring that the satellite and stars recombine within a Galactic lifetime when their current phase-space coordinates are integrated backwards. When applied to a four-dimensional grid of triaxial logarithmic potentials, with varying circular velocities, axis ratios and orientation of the major-axis in the disk plane, the algorithm can recover the parameters used for the Milky Way in a simulated data set to within a few percent using only 100 stars in a tidal stream.Comment: Revised version - original algorithm generalised to be applicable to any potential shape. LaTeX, 12 pages including 3 figures. To be published in ApJ Letter

Liquid droplet formation by HP1α suggests a role for phase separation in heterochromatin.

Gene silencing by heterochromatin is proposed to occur in part as a result of the ability of heterochromatin protein 1 (HP1) proteins to spread across large regions of the genome, compact the underlying chromatin and recruit diverse ligands. Here we identify a new property of the human HP1α protein: the ability to form phase-separated droplets. While unmodified HP1α is soluble, either phosphorylation of its N-terminal extension or DNA binding promotes the formation of phase-separated droplets. Phosphorylation-driven phase separation can be promoted or reversed by specific HP1α ligands. Known components of heterochromatin such as nucleosomes and DNA preferentially partition into the HP1α droplets, but molecules such as the transcription factor TFIIB show no preference. Using a single-molecule DNA curtain assay, we find that both unmodified and phosphorylated HP1α induce rapid compaction of DNA strands into puncta, although with different characteristics. We show by direct protein delivery into mammalian cells that an HP1α mutant incapable of phase separation in vitro forms smaller and fewer nuclear puncta than phosphorylated HP1α. These findings suggest that heterochromatin-mediated gene silencing may occur in part through sequestration of compacted chromatin in phase-separated HP1 droplets, which are dissolved or formed by specific ligands on the basis of nuclear context