Interplay between self-assembly and phase separation in a polymer-complex model

We present a theoretical model for predicting the phase behavior of polymer solutions in which phase separation competes with oligomerization. Specifically, we consider scenarios in which the assembly of polymer chains into stoichiometric complexes prevents the chains from phase-separating via attractive polymer-polymer interactions. Combining statistical associating fluid theory with a two-state description of self-assembly, we find that this model exhibits rich phase behavior, including re-entrance, and we show how system-specific phase diagrams can be derived graphically. Importantly, we discuss why these phase diagrams can resemble -- and yet are qualitatively distinct from -- phase diagrams of polymer solutions with lower critical solution temperatures

Cold-Formed Steel Framed Shear Wall Database

The objective of this paper is to provide an introduction to a recently compiled database of cold-formed steel framed shear wall tests and demonstrate the application of this database for improving the understanding and modeling of cold-formed steel framed shear walls. Over the last 20 years a substantial number of cold-formed steel framed shear walls have been tested under monotonic and cyclic conditions. These tests provide the support for the cold-formed steel framed shear wall provisions provided in the North American Standard for Cold-Formed Steel Structural Framing (AISI S240-15), the North American Standard for Seismic Design of Cold-Formed Steel Structural Systems (AISI S400-15), and the U.S. Seismic Evaluation and Retrofit of Existing Buildings standard (ASCE41- 17). The initial version of the database was assembled during the development of ASCE41-17. The database has recently been expanded to include additional tests, additional complete cyclic information from tests, additional fields regarding limit states and code predictions, and placed in a standardized format. The database consists of a central Excel spreadsheet, ordered plain text files for each individual test, and custom Matlab code for reading, processing, and plotting any desired subset of the database. As a new application of the assembled database the expected strength of cold-formed steel framed shear walls is explored. The information in the database is summarized herein, along with commentary on current code provisions, and areas of potential improvement and need

Divergence and Convergence in Scarf Cycle Environments: Experiments and Predictability in the Dynamics of General Equilibrium Systems

Previous experimental work demonstrates the power of classical theories of economic dynamics to accurately characterize equilibration in multiple market systems. Building on the literature, this study examines the behavior of experimental continuous double auction markets in convergence-challenging environments identified by Scarf (1960) and Hirota (1981). The experiments provide insight into two important economic questions: (a) do markets necessarily converge to a unique interior equilibrium? and (b) which model, among a set of classical specifications, most accurately characterizes observed price dynamics? We observe excess demand driven prices spiraling outwardly away from the interior equilibrium prices as predicted by the theory of disequilibrium price dynamics. We estimate a structural model establishing that partial equilibrium dynamics characterize price changes even in an unstable general equilibrium environment. We observe linkages between excess demand in one market and price changes in another market but the sign of expected price change in a market does not depend on the magnitude of excess demand in other markets unless disequilibrium is severe

A simple method to alter the binding specificity of DNA-coated colloids that crystallize

DNA-coated colloids can crystallize into a multitude of lattices, ranging from face-centered cubic to diamond, opening avenues to producing structures with useful photonic properties. The potential design space of DNA-coated colloids is large, but its exploration is hampered by a reliance on chemically modified DNA that is slow and expensive to commercially synthesize. Here we introduce a method to controllably tailor the sequences of DNA-coated particles by covalently appending new sequence domains onto the DNA grafted to colloidal particles. The tailored particles crystallize as readily and at the same temperature as those produced via direct chemical synthesis, making them suitable for self-assembly. Moreover, we show that particles coated with a single sequence can be converted into a variety of building blocks with differing specificities by appending different DNA sequences to them. This method will make it practical to identify optimal and complex particle sequence designs and paves the way to programming the assembly kinetics of DNA-coated colloids.</p

A simple method to alter the binding specificity of DNA-coated colloids that crystallize

DNA-coated colloids can crystallize into a multitude of lattices, ranging from face-centered cubic to diamond, opening avenues to producing structures with useful photonic properties. The potential design space of DNA-coated colloids is large, but its exploration is hampered by a reliance on chemically modified DNA that is slow and expensive to commercially synthesize. Here we introduce a method to controllably tailor the sequences of DNA-coated particles by covalently appending new sequence domains onto the DNA grafted to colloidal particles. The tailored particles crystallize as readily and at the same temperature as those produced via direct chemical synthesis, making them suitable for self-assembly. Moreover, we show that particles coated with a single sequence can be converted into a variety of building blocks with differing specificities by appending different DNA sequences to them. This method will make it practical to identify optimal and complex particle sequence designs and paves the way to programming the assembly kinetics of DNA-coated colloids.</p

The California-Kepler Survey. II. Precise Physical Properties of 2025 Kepler Planets and Their Host Stars

We present stellar and planetary properties for 1305 Kepler Objects of Interest (KOIs) hosting 2025 planet candidates observed as part of the California-Kepler Survey. We combine spectroscopic constraints, presented in Paper I, with stellar interior modeling to estimate stellar masses, radii, and ages. Stellar radii are typically constrained to 11%, compared to 40% when only photometric constraints are used. Stellar masses are constrained to 4%, and ages are constrained to 30%. We verify the integrity of the stellar parameters through comparisons with asteroseismic studies and Gaia parallaxes. We also recompute planetary radii for 2025 planet candidates. Because knowledge of planetary radii is often limited by uncertainties in stellar size, we improve the uncertainties in planet radii from typically 42% to 12%. We also leverage improved knowledge of stellar effective temperature to recompute incident stellar fluxes for the planets, now precise to 21%, compared to a factor of two when derived from photometry.Comment: 13 pages, 4 figures, 4 tables, accepted for publication in AJ; full versions of tables 3 and 4 are include

The California-Kepler Survey. I. High Resolution Spectroscopy of 1305 Stars Hosting Kepler Transiting Planets

The California-Kepler Survey (CKS) is an observational program to improve our knowledge of the properties of stars found to host transiting planets by NASA's Kepler Mission. The improvement stems from new high-resolution optical spectra obtained using HIRES at the W. M. Keck Observatory. The CKS stellar sample comprises 1305 stars classified as Kepler Objects of Interest, hosting a total of 2075 transiting planets. The primary sample is magnitude-limited (Kp < 14.2) and contains 960 stars with 1385 planets. The sample was extended to include some fainter stars that host multiple planets, ultra short period planets, or habitable zone planets. The spectroscopic parameters were determined with two different codes, one based on template matching and the other on direct spectral synthesis using radiative transfer. We demonstrate a precision of 60 K in effective temperature, 0.10 dex in surface gravity, 0.04 dex in [Fe/H], and 1.0 km/s in projected rotational velocity. In this paper we describe the CKS project and present a uniform catalog of spectroscopic parameters. Subsequent papers in this series present catalogs of derived stellar properties such as mass, radius and age; revised planet properties; and statistical explorations of the ensemble. CKS is the largest survey to determine the properties of Kepler stars using a uniform set of high-resolution, high signal-to-noise ratio spectra. The HIRES spectra are available to the community for independent analyses.Comment: 20 pages, 19 figures, accepted for publication in AJ; a full version of Table 5 is included as tab_cks.csv and tab_cks.te