A new type of photoionized code required for the new era of X-ray spectroscopy

With the advent of the present and future spatial X-ray missions, it becomes crucial to model correctly the line spectrum of X-ray emitting media. We have built a photoionization code, Titan, solving the transfer of a thousand lines and of the continuum with the "Accelerated Lambda Iteration" method, which is most reliable for line transfer. In all other photoionization codes the line intensities are computed with the so-called "escape probability formalism", used in its simplest approximation. In a previous paper (Dumont et al. 2003), it was shown that this approximation leads to errors which can exceed one order of magnitude in the case a Thomson thickness of the order of unity. We show here that it also happens in the case of a Thomson thickness of 0.001 to 0.1. The errors on the line fluxes and line ratios are of the order of 30% for a column density of 10^{20} cm^{-2}, and a factor five for a column density of 10^{23} cm^{-2}, in conditions appropriate for Seyfert 2 and for the Warm Absorber of Seyfert 1.Comment: 11 pages, 7 figures. accepted by A&

Assessing the environmental potential of carbon dioxide utilization: A graphical targeting approach

Carbon Capture and Utilization (CCU) has the potential to reduce both greenhouse gas emissions and fossil fuel use. However, the conversion of CO2 is intrinsically difficult due to its low energetic state. Thus, a positive environmental effect of a CO2-consuming reaction cannot be taken for granted. In this work, we therefore present a graphical method to identify promising reaction schemes using CO2 as a feedstock. Reactant mixtures leading to minimal life-cycle greenhouse gas (GHG) emissions are determined. The optimal reaction schemes strongly depend on the reactants’ global warming potential (GWP); in the case of CCU, the future GWP values of CO2 and H2 are particularly critical and subject to major uncertainty today. The graphical method therefore provides GWP targets for CO2 capture and H2 production technologies. The method is demonstrated for the production of methanol. Five optimal reaction schemes are identified depending on the GWP values of CO2 and H2. Thus, four threshold relations for the GWP of CO2 and H2 are derived showing directly under which conditions the utilization of CO2 as a feedstock is environmentally preferential

Alien Registration- Dumont, Marie A. (Lewiston, Androscoggin County)

https://digitalmaine.com/alien_docs/29467/thumbnail.jp

Alien Registration- Dumont, Marie Anne (Auburn, Androscoggin County)

https://digitalmaine.com/alien_docs/31232/thumbnail.jp

Alien Registration- Dumont, Marie L. (Auburn, Androscoggin County)

https://digitalmaine.com/alien_docs/31233/thumbnail.jp

Systemes de numeration et fonctions fractales relatifs aux substitutions

AbstractLet A be a finite alphabet, σ a substitution over A, (un)n ϵ N a fixed point for σ, and for each a ϵ A, ƒ(a) a real number. We establish, under some assumptions, an asymptotic formula concerning the sum Sƒ (N) = Σi ⩽ N ƒ(ui), N ϵ N. This result generalizes some previous results from Coquet or Brillhart, Erdös, and Morton. Moreover, relations with self-affine functions (in a sense which generalizes a definition from Kamae) are proved. The calculi leave over systems of representation of integers and real numbers

5‐Hydroxymethylfurfural derivative based thermoplastic elastomers synthesized via thiol‐Michael addition reaction utilizing poly (lactic acid) as hard end blocks

5-Hydroxymethylfurfural derivative based thermoplastic elastomers (TPEs) are effciently synthesized via a two-step thiol-Michael addition reaction using polylactide (PLA) as the hard segments in a one-pot reaction under mild conditions. The first step involves the synthesis of prepolymers having thiolgroups as end groups. The macromolecular coupling reaction which occurred between the prepolymers and the PLA having acrylate-end groups is demonstrated via 1H NMR and GPC. Additionally, by varying the ratio of 1,3-propanedithiol and 2,5-furan diacrylate, TPEs with soft segments having different molecular weights are synthesized, and then characterized. The cyclic tensile tests demonstrate the elasticity of the synthesized TPEs. Furthermore, the Diels–Alder reaction is used to dynamically crosslink the soft segments in the TPEs, leading to the increased mechanical properties in terms of Young's modulus and tensile strength

Advances in polymer precursors and bio‐based polymers synthesized from 5‐hydroxymethylfurfural

In recent years, considerable efforts have been made regarding the synthesis of renewable chemicals from natural resources. 5-hydroxymethylfurfural (HMF) is an interesting platform chemical which has been widely exploited due to its rich chemistry and potential availability. The versatility of HMF has been demonstrated in several areas such as fine chemicals, biofuel precursors and polymers. In particular, the potential to replace petroleum-based analogues in the preparation of polymers associated with high performance has been observed owing to the structural rigidity of furan rings. This review aims at critically discuss the current research studies related to the derivatives of HMF, alongside with the synthesis and characterization of (co-) polymers derived from HMF and its derivatives