On vectorially parameterized natural strain measures of the non-linear Cosserat continuum

AbstractThe natural Lagrangian stretch and wryness tensors of the non-linear Cosserat continuum are expressed in terms of the general finite rotation vector. These expressions are then specialized for seven particular definitions of the rotation vectors known in the literature. It is expected that some of the vectorially parameterized strain measures derived here may be more convenient than others in specific applications

Nonlinear resultant theory of shells accounting for thermodiffusion

The complete nonlinear resultant 2D model of shell thermodiffusion is developed. All 2D balance laws and the entropy imbalance are formulated by direct through-the-thickness integration of respective 3D laws of continuum thermodiffusion. This leads to a more rich thermodynamic structure of our 2D model with several additional 2D fields not present in the 3D parent model. Constitutive equations of elastic thermodiffusive shells are discussed in more detail. They are formulated from restrictions imposed by the resultant 2D entropy imbalance according to Coleman–Noll procedure extended by a set of 2D constitutive equations based on heuristic assumptions

21-(4-Methyl­phenyl­sulfon­yl)-4,7,13,16-tetra­oxa-1,10,21-triaza­bicyclo­[8.8.5]tricosane-19,23-dione: an N-tosyl­ated macrobicyclic dilactam

The macrobicyclic title compound, C23H35N3O8S, contains two tertiary amide bridgehead N atoms and a toluene­sulfonamide N atom in the center of the five-atom bridging strand. The mol­ecule has a central cavity that is defined by the 18-membered ring identified by the N2O4 donor atom set and two 15-membered rings with N3O2 donor atom sets. The toluene­sulfonamide N atom adopts an exo orientation with respect to the central cavity, and the tosyl group is oriented on one side of the aza-bridging strand that connects the bridgehead N atoms

Monothiatruxene-Based, Solution-Processed Green, Sky-Blue, and Deep-Blue Organic Light-Emitting Diodes with Efficiencies Beyond 5% Limit

The authors thank the Mazowieckie voivodeship, cofinanced with the European Union funds by the European Social Fund and European Union's Horizon 2020 Research and Innovation Programme H2020‐MSCA‐IF‐2014‐659237 for financial support. The authors thank Dr. Gary Nichol for the crystallographic data collection and refinement; The University of Edinburgh for funding the diffractometer purchase. I.D.W.S. acknowledges support from a Royal Society Wolfson Research Merit Award and from the Engineering and Physical Sciences Research Council (grant EP/J009016/1).The development of blue materials with good efficiency, even at high brightness, with excellent color purity, simple processing, and high thermal stability assuring adequate device lifetime is an important remaining challenge for organic light‐emitting didoes (OLEDs) in displays and lightning applications. Furthermore, these various features are typically mutually exclusive in practice. Herein, four novel green and blue light‐emitting materials based on a monothiatruxene core are reported together with their photophysical and thermal properties, and performance in solution‐processed OLEDs. The materials show excellent thermal properties with high glass transition temperatures ranging from 171 to 336 °C and decomposition temperatures from 352 to 442 °C. High external quantum efficiencies of 3.7% for a deep‐blue emitter with CIE color co‐ordinates (0.16, 0.09) and 7% for green emitter with color co‐ordinates (0.22, 0.40) are achieved at 100 cd m−2. The efficiencies observed are exceptionally high for fluorescent materials with photoluminescence quantum yields of 24% and 62%, respectively. The performance at higher brightness is very good with only 38% and 17% efficiency roll‐offs at 1000 cd m−2. The results indicate that utilization of this unique molecular design is promising for efficient deep‐blue highly stable and soluble light‐emitting materials.PostprintPeer reviewe

Existence theorems in the geometrically non-linear 6-parametric theory of elastic plates

In this paper we show the existence of global minimizers for the geometrically exact, non-linear equations of elastic plates, in the framework of the general 6-parametric shell theory. A characteristic feature of this model for shells is the appearance of two independent kinematic fields: the translation vector field and the rotation tensor field (representing in total 6 independent scalar kinematic variables). For isotropic plates, we prove the existence theorem by applying the direct methods of the calculus of variations. Then, we generalize our existence result to the case of anisotropic plates. We also present a detailed comparison with a previously established Cosserat plate model.Comment: 19 pages, 1 figur

Thermomechanics of shells undergoing phase transition

International audienceThe resultant, two-dimensional thermomechanics of shells undergoing diffusionless, displacive phase transitions of martensitic type of the shell material is developed. In particular, we extend the resultant surface entropy inequality by introducing two temperature fields on the shell base surface: the referential mean temperature and its deviation, with corresponding dual fields: the referential entropy and its deviation. Additionally, several extra surface fields related to the deviation fields are introduced to assure that the resultant surface entropy inequality be direct implication of the entropy inequality of continuum thermomechanics. The corresponding constitutive equations for thermoelastic and thermoviscoelastic shells of differential type are worked out. Within this formulation of shell thermomechanics, we also derive the thermodynamic continuity condition along the curvilinear phase interface and propose the kinetic equation allowing one to determine position and quasistatic motion of the interface relative to the base surface. The theoretical model is illustrated by two axisymmetric numerical examples of stretching and bending of the circular plate undergoing phase transition within the range of small deformations

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure