Relativistic photoionization cross sections for C II

High resolution measurements of photoionization cross sections for atomic ions are now being made on synchrotron radiation sources. The recent measurements by Kjeldsen etal. (1999) showed good agreement between the observed resonance features and the the theoretical calculations in the close coupling approximation (Nahar 1995). However, there were several observed resonances that were missing in the theoretical predictions. The earlier theoretical calculation was carried out in LS coupling where the relativistic effects were not included. Present work reports photoionization cross sections including the relativistic effects in Breit-Pauli R-matrix (BPRM) approximation. The configuration interaction eigenfunction expansion for the core ion C III consists of 20 fine structure levels dominated by the configurations from 1s^22s^2 to 1s^22s3d. Detailed features in the calculated cross sections exhibit the missing resonances due to fine structure. The results benchmark the accuracy of BPRM photoionization cross sections as needed for recent and ongoing experiments.Comment: 13 pages, 3 figure

Enhancement-mode PEDOT:PSS organic electrochemical transistors using molecular de-doping

Organic electrochemical transistors (OECTs) show great promise for flexible, low-cost, and low-voltage sensors for aqueous solutions. The majority of OECT devices are made using the polymer blend poly(ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), in which PEDOT is intrinsically doped due to inclusion of PSS. Because of this intrinsic doping, PEDOT:PSS OECTs generally operate in depletion mode, which results in a higher power consumption and limits stability. Here, a straightforward method to de-dope PEDOT:PSS using commercially available amine-based molecular de-dopants to achieve stable enhancement-mode OECTs is presented. The enhancement-mode OECTs show mobilities near that of pristine PEDOT:PSS (≈2 cm2 V−1 s−1) with stable operation over 1000 on/off cycles. The electron and proton exchange among PEDOT, PSS, and the molecular de-dopants are characterized to reveal the underlying chemical mechanism of the threshold voltage shift to negative voltages. Finally, the effect of the de-doping on the microstructure of the spin-cast PEDOT:PSS films is investigated.</p

Biobased economy : state-of-the-art assessment

The interest in the biobased economy stems from the possibility to substitute biologically derived materials and processes for the production of goods that will, therefore, result in a reduced use of petroleum and petro-chemistry. Other reasons are the reduction in the energy required in production processes or the more environmentally benign waste treatment channels for the production residues or discarded products at the end of their life cycle. The Ministry of Agriculture, Nature and Food Quality of The Netherlands has asked Wageningen UR (AFSG and LEI) to examine the contemporary market for biobased products and the potential growth of the biobased economy. This report is based on an analysis of the bio-based composition, actual and possible, as well as the market value of 780 non-food, non-feed products within the PRODCOM listing, which represent the potential for biobased production in NL and the EU25

Finite Element Convergence for the Joule Heating Problem with Mixed Boundary Conditions

We prove strong convergence of conforming finite element approximations to the stationary Joule heating problem with mixed boundary conditions on Lipschitz domains in three spatial dimensions. We show optimal global regularity estimates on creased domains and prove a priori and a posteriori bounds for shape regular meshes.Comment: Keywords: Joule heating problem, thermistors, a posteriori error analysis, a priori error analysis, finite element metho

Relativistic close coupling calculations for photoionization and recombination of Ne-like Fe XVII

Relativistic and channel coupling effects in photoionization and unified electronic recombination of Fe XVII are demonstrated with an extensive 60-level close coupling calculation using the Breit-Pauli R-matrix method. Photoionization and (e + ion) recombination calculations are carried out for the total and the level-specific cross sections, including the ground and several hundred excited bound levels of Fe XVII (up to fine structure levels with n = 10). The unified (e + ion) recombination calculations for (e + Fe XVIII --> Fe XVII) include both the non-resonant and resonant recombination (`radiative' and `dielectronic recombination' -- RR and DR). The low-energy and the high energy cross sections are compared from: (i) a 3-level calculation with 2s^2p^5 (^2P^o_{1/2,3/2}) and 2s2p^6 (^2S_{1/2}), and (ii) the first 60-level calculation with \Delta n > 0 coupled channels with spectroscopic 2s^2p^5, 2s2p^6, 2s^22p^4 3s, 3p, 3d, configurations, and a number of correlation configurations. Strong channel coupling effects are demonstrated throughout the energy ranges considered, in particular via giant photoexcitation-of-core (PEC) resonances due to L-M shell dipole transition arrays 2p^5 --> 2p^4 3s, 3d in Fe XIII that enhance effective cross sections by orders of magnitude. Comparison is made with previous theoretical and experimental works on photoionization and recombination that considered the relatively small low-energy region (i), and the weaker \Delta n = 0 couplings. While the 3-level results are inadequate, the present 60-level results should provide reasonably complete and accurate datasets for both photoionization and (e + ion) recombination of Fe~XVII in laboratory and astrophysical plasmas.Comment: 19 pages, 8 figures, Phys. Rev. A (submitted

Peptide-Induced Lipid Flip-Flop in Asymmetric Liposomes Measured by Small Angle Neutron Scattering

© 2019 American Chemical Society. Despite the prevalence of lipid transbilayer asymmetry in natural plasma membranes, most biomimetic model membranes studied are symmetric. Recent advances have helped to overcome the difficulties in preparing asymmetric liposomes in vitro, allowing for the examination of a larger set of relevant biophysical questions. Here, we investigate the stability of asymmetric bilayers by measuring lipid flip-flop with time-resolved small-angle neutron scattering (SANS). Asymmetric large unilamellar vesicles with inner bilayer leaflets containing predominantly 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and outer leaflets composed mainly of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) displayed slow spontaneous flip-flop at 37 -C (half-time, t1/2 = 140 h). However, inclusion of peptides, namely, gramicidin, alamethicin, melittin, or pHLIP (i.e., pH-low insertion peptide), accelerated lipid flip-flop. For three of these peptides (i.e., pHLIP, alamethicin, and melittin), each of which was added externally to preformed asymmetric vesicles, we observed a completely scrambled bilayer in less than 2 h. Gramicidin, on the other hand, was preincorporated during the formation of the asymmetric liposomes and showed a time resolvable 8-fold increase in the rate of lipid asymmetry loss. These results point to a membrane surface-related (e.g., adsorption/insertion) event as the primary driver of lipid scrambling in the asymmetric model membranes of this study. We discuss the implications of membrane peptide binding, conformation, and insertion on lipid asymmetry

Roadwork:Expertise at work building roads in the Maldives

This article engages critically with concepts of ‘skill’, ‘expertise’, and ‘capacity’ as they operate as markers of distinction and domination and shape migratory labour relations among road construction workers from across South Asia in the Maldives archipelago. The article examines roadwork at three levels: the professional biographies leading to ‘flexible specialization’ rather than technical expertise amongst Maldivian managers; the technical expertise and social incorporation of ‘skilled’ Sri Lankan supervisors; and the key material expertise of ‘non-skilled’ Bangladeshi labourers in precarious employment. Whilst discussions of South Asian labour migration have been dominated by caste and class, this article argues that it is important to consider how the cultural production and understanding of concepts such as ‘expertise’, ‘capacity’, and ‘exposure’ at worksites can (also) become distinguishing factors in (hierarchical) migratory labour relations

Abundances of the elements in the solar system

A review of the abundances and condensation temperatures of the elements and their nuclides in the solar nebula and in chondritic meteorites. Abundances of the elements in some neighboring stars are also discussed.Comment: 42 pages, 11 tables, 8 figures, chapter, In Landolt- B\"ornstein, New Series, Vol. VI/4B, Chap. 4.4, J.E. Tr\"umper (ed.), Berlin, Heidelberg, New York: Springer-Verlag, p. 560-63

A Conflict Model for Strategists and Managers

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67210/2/10.1177_000276427201500604.pd

PREDICTING THE SUMMER TEMPERATURE OF SMALL STREAMS IN SOUTHWESTERN WISCONSIN 1

One of the biggest challenges in managing cold water streams in the Midwest is understanding how stream temperature is controlled by the complex interactions among meteorologic processes, channel geometry, and ground water inflow. Inflow of cold ground water, shade provided by riparian vegetation, and channel width are the most important factors controlling summer stream temperatures. A simple screening model was used to quantitatively evaluate the importance of these factors and guide management decisions. The model uses an analytical solution to the heat transport equation to predict steady-state temperature throughout a stream reach. The model matches field data from four streams in southwestern Wisconsin quite well (typically within 1°C) and helps explain the observed warming and cooling trends along each stream reach. The distribution of ground water inflow throughout a stream reach has an important influence on stream temperature, and springs are especially effective at providing thermal refuge for fish. Although simple, this model provides insight into the importance of ground water and the impact different management strategies, such as planting trees to increase shade, may have on summer stream temperature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74032/1/j.1752-1688.2005.tb03714.x.pd