Thermal degradation of Cross-Linked Polyisoprene and Polychloroprene

Polyisoprene and polychloroprene have been cross-linked either in solution or in solid state using free radical initiators. In the comparable experimental conditions higher cross-linking density was observed in the solid state process. Independent of the cross-linking method, polychloroprene tended to give a higher gel content and cross-link density than does polyisoprene. Infrared characterization of the cross-linked materials showed cis-trans isomerization occurred in the polyisoprene initiated by benzoyl peroxide, whereas no isomerization was found in the samples initiated by dicumyl peroxide. Polyisoprene does not cross-link by heating in a thermal analyzer, whereas polychloroprene easily undergoes cross-linking in such conditions. Infrared spectroscopy showed that in the case of polyisoprene, rearrangements occur upon heating which lead to the formation of terminal double bonds, while polychloroprene loses hydrogen chlorine which leads to a conjugated structure. There is apparently some enhancement of the thermal and thermal oxidative stability of polyisoprene because of the cross-linking. Cross-linked polychloroprene is less thermally stable than the virgin polymer. Cross-linking promotes polymers charring in the main step of weight loss in air, which leads to enhanced transitory char

Molecular landscapes of human hematopoietic stem cells in health and leukemia.

Blood cells are organized as a hierarchy with hematopoietic stem cells (HSCs) at the root. The advent of genomic technologies has opened the way for global characterization of the molecular landscape of HSCs and their progeny, both in mouse and human models, at the genetic, transcriptomic, epigenetic, and proteomics levels. Here, we outline our current understanding of the molecular programs that govern human HSCs and how dynamic changes occurring during HSC differentiation are necessary for well-regulated blood formation under homeostasis and upon injury. A large body of evidence is accumulating on how the programs of normal hematopoiesis are modified in acute myeloid leukemia, an aggressive adult malignancy driven by leukemic stem cells. We summarize these findings and their clinical implications.The authors would like to thank Emily Calderbank for critical review of the manuscript. Research in EL laboratory is supported by a Wellcome Trust Sir Henry Dale Fellowship and core support grant from the Wellcome Trust and MRC to the Wellcome Trust – Medical Research Council Cambridge Stem Cell Institute.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1111/nyas.1298

Recycled arc mantle recovered from the Mid-Atlantic Ridge

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Urann, B. M., Dick, H. J. B., Parnell-Turner, R., & Casey, J. F. Recycled arc mantle recovered from the Mid-Atlantic Ridge. Nature Communications, 11(1), (2020): 3887, doi:10.1038/s41467-020-17604-8.Plate tectonics and mantle dynamics necessitate mantle recycling throughout Earth’s history, yet direct geochemical evidence for mantle reprocessing remains elusive. Here we present evidence of recycled supra-subduction zone mantle wedge peridotite dredged from the Mid-Atlantic Ridge near 16°30′N. Peridotite trace-element characteristics are inconsistent with fractional anhydrous melting typically associated with a mid-ocean ridge setting. Instead, the samples are best explained by hydrous flux melting which changed the melting reactions such that clinopyroxene was not exhausted at high degrees of melting and was retained in the residuum. Based on along-axis ridge depth variations, this buoyant refractory arc mantle is likely compensated at depth by denser, likely garnet-rich, lithologies within the mantle column. Our results suggest that highly refractory arc mantle relicts are entrained in the upper mantle and may constitute >60% of the upper mantle by volume. These highly refractory mantle domains, which contribute little to mantle melting, are under-represented in compilations of mantle composition that rely on inverted basalt compositions alone.We thank the science party for their dutiful collection and description of dredge samples, and in particular chief scientist Dr. Deborah K. Smith. Analysis work for this research was supported by an internal grant from the MIT EAPS Student Research Fund to BMU. Urann was supported by the Stanley W. Watson Student Fellowship Fund based at WHOI. Dick and Urann were supported by NSF OCE-1637130 and OCE-1155650. Dr. Yongjun Gao is thanked for conducting LA-ICP-MS trace elements analyses

Determination of myocardial and serum digoxin concentrations in children by specific and nonspecific assay methods

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109866/1/cptclpt198378.pd

The Ursinus Weekly, May 2, 1974

Two faculty members receive promotions • Committee of USGA proposes rule changes • Henry and Perreten get study grants • Dr. Parsons and Dr. Snyder to run Pa. Dutch course • Japanese will join U.C. summer school • U.C. to honor Rep. Ware at commencement • Dave Liscom to attend St. Andrews • Editorial: So what else is new?; Say something good • Italian philosopher is reborn • Alumni corner: The Ruby in debt • The ghost of Ursinus past • Ursinus students view unicorns • New 3-plus-3 plan: Degree in 3 years • Pi Gamma Mu names 10 to membership • Brazilians say “Saudade!” • U.C. students plan summers in Europe • Review: Springsteen’s rock rocks U.C. campus • ‘Chap’ resigns his U.C posts • Lacrosse trials select players • Bear runners looking good • Faculty focus: Georgia Ferrell leads winning gymnasts • Baseball squad facing tough competition • Two Ursinus basketball stars honoredhttps://digitalcommons.ursinus.edu/weekly/1015/thumbnail.jp

Nonvolcanic seafloor spreading and corner-flow rotation accommodated by extensional faulting at 15°N on the Mid-Atlantic Ridge : a structural synthesis of ODP Leg 209

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 8 (2007): Q06015, doi:10.1029/2006GC001567.Drilling during ODP Leg 209, dredging, and submersible dives have delineated an anomalous stretch of the Mid-Atlantic Ridge north and south of the 15°20′N Fracture Zone. The seafloor here consists dominantly of mantle peridotite with gabbroic intrusions that in places is covered by a thin, discontinuous extrusive volcanic layer. Thick lithosphere (10–20 km) in this region inhibits magma from reaching shallow levels beneath the ridge axis, thereby causing plate accretion to be accommodated by extensional faulting rather than magmatism. The bathymetry and complex fault relations in the drill-core suggest that mantle denudation and spreading are accommodated by a combination of high-displacement, rolling-hinge normal faults and secondary lower-displacement normal faults. These extensional faults must also accommodate corner flow rotation (up to 90°) of the upwelling mantle within the shallow lithosphere, consistent with remnant magnetic inclinations in denuded peridotite and gabbro from Leg 209 core that indicate up to 90° of sub-Curie-temperature rotation.This work was funded by a grant from the Joint Oceanographic Institutions

Meeting report : Ocean ‘omics science, technology and cyberinfrastructure : current challenges and future requirements (August 20-23, 2013)

© The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Standards in Genomic Sciences 9 (2014): 1251-1258, doi:10.4056/sigs.5749944.The National Science Foundation’s EarthCube End User Workshop was held at USC’s Wrigley Marine Science Center on Catalina Island, California in August 2013. The workshop was designed to explore and characterise the needs and tools available to the community focusing on microbial and physical oceanography research with a particular focus on ‘omic research. The assembled researchers outlined the existing concerns regarding the vast data resources that are being generated, and how we will deal with these resources as their volume and diversity increases. Particular attention was focused on the tools for handling and analysing the existing data, and on the need for the construction and curation of diverse federated databases, as well as development of shared interoperable, “big-data capable” analytical tools. The key outputs from this workshop include (i) critical scientific challenges and cyberinfrastructure constraints, (ii) the current and future ocean ‘omics science grand challenges and questions, and (iii) data management, analytical and associated and cyber-infrastructure capabilities required to meet critical current and future scientific challenges. The main thrust of the meeting and the outcome of this report is a definition of the ‘omics tools, technologies and infrastructures that facilitate continued advance in ocean science biology, marine biogeochemistry, and biological oceanography.We gratefully acknowledge support for the Ocean ‘Omics EarthCube end-user workshop by the Geo-sciences Division of the U.S. National Science Foundation

Long range transport of ultra cold atoms in a far-detuned 1D optical lattice

We present a novel method to transport ultra cold atoms in a focused optical lattice over macroscopic distances of many Rayleigh ranges. With this method ultra cold atoms were transported over 5 cm in 250 ms without significant atom loss or heating. By translating the interference pattern together with the beam geometry the trap parameters are maintained over the full transport range. Thus, the presented method is well suited for tightly focused optical lattices that have sufficient trap depth only close to the focus. Tight focusing is usually required for far-detuned optical traps or traps that require high laser intensity for other reasons. The transport time is short and thus compatible with the operation of an optical lattice clock in which atoms are probed in a well designed environment spatially separated from the preparation and detection region.Comment: 14 pages, 6 figure

Mechanisms of Alcohol Addiction: Bridging Human and Animal Studies

Aim: The purpose of this brief narrative review is to address the complexities and benefits of extending animal alcohol addiction research to the human domain, emphasizing Allostasis and Incentive Sensitization, two models that inform many pre-clinical and clinical studies. Methods: The work reviewed includes a range of approaches, including: a) animal and human studies that target the biology of craving and compulsive consumption; b) human investigations that utilize alcohol self-administration and alcohol challenge paradigms, in some cases across 10 years; c) questionnaires that document changes in the positive and negative reinforcing effects of alcohol with increasing severity of addiction; and d) genomic structural equation modeling based on data from animal and human studies. Results: Several general themes emerge from specific study findings. First, positive reinforcement is characteristic of early stage addiction and sometimes diminishes with increasing severity, consistent with both Allostasis and Incentive Sensitization. Second, evidence is less consistent for the predominance of negative reinforcement in later stages of addiction, a key tenant of Allostasis. Finally, there are important individual differences in motivation to drink at a given point in time as well as person-specific change patterns across time. Conclusions: Key constructs of addiction, like stage and reinforcement, are by necessity operationalized differently in animal and human studies. Similarly, testing the validity of addiction models requires different strategies by the two research domains. Although such differences are challenging, they are not insurmountable, and there is much to be gained in understanding and treating addiction by combining pre-clinical and clinical approaches.Fil: Kramer, John. University of Iowa; Estados UnidosFil: Dick, Danielle M.. University of Virginia; Estados UnidosFil: King, Andrea. University of Chicago; Estados UnidosFil: Ray, Lara A.. University of California at Los Angeles; Estados UnidosFil: Sher, Kenneth J.. University of Missouri; Estados UnidosFil: Vena, Ashley. University of Chicago; Estados UnidosFil: Vendruscolo, Leandro F.. National Institutes of Health; Estados UnidosFil: Acion, Laura. University of Iowa; Estados Unidos. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Calculo. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Calculo; Argentin

Improved spacecraft radio science using an on-board atomic clock: application to gravitational wave searches

Recent advances in space-qualified atomic clocks (low-mass, low power-consumption, frequency stability comparable to that of ground-based clocks) can enable interplanetary spacecraft radio science experiments at unprecedented Doppler sensitivities. The addition of an on-board digital receiver would allow the up- and down-link Doppler frequencies to be measured separately. Such separate, high-quality measurements allow optimal data combinations that suppress the currently-leading noise sources: phase scintillation noise from the Earth's atmosphere and Doppler noise caused by mechanical vibrations of the ground antenna. Here we provide a general expression for the optimal combination of ground and on-board Doppler data and compute the sensitivity such a system would have to low-frequency gravitational waves (GWs). Assuming a plasma scintillation noise calibration comparable to that already demonstrated with the multi-link CASSINI radio system, the space-clock/digital-receiver instrumentation enhancements would give GW strain sensitivity of $2.0 \times 10^{-17}$ for randomly polarized, monochromatic GW signals over a two-decade ($\sim0.0001-0.01$ Hz) region of the low-frequency band. This is about an order of magnitude better than currently achieved with traditional two-way coherent Doppler experiments. The utility of optimally combining simultaneous up- and down-link observations is not limited to GW searches. The Doppler tracking technique discussed here could be performed at minimal incremental cost to also improve other radio science experiments (i.e. tests of relativistic gravity, planetary and satellite gravity field measurements, atmospheric and ring occultations) on future interplanetary missions.Comment: 21 pages, 5 figures. Submitted to Phys. Rev.