Aggregation Behavior And Chromonic Liquid Crystal Properties Of An Anionic Monoazo Dye

X-ray scattering and various optical techniques are utilized to study the aggregation process and chromonic liquid crystal phase of the anionic monoazo dye Sunset Yellow FCF. The x-ray results demonstrate that aggregation involves pi-pi stacking of the molecules into columns, with the columns undergoing a phase transition to an orientationally ordered chromonic liquid crystal phase at high dye concentration. Optical absorption measurements on dilute solutions reveal that the aggregation takes place at all concentrations, with the average aggregation number increasing with concentration. A simple theory based on the law of mass action and an isodesmic aggregation process is in excellent agreement with the experimental data and yields a value for the bond energy between molecules in an aggregate. Measurements of the birefringence and order parameter are also performed as a function of temperature in the chromonic liquid crystal phase. The agreement between these results and a more complicated theory of aggregation is quite reasonable. Overall, these results both confirm that the aggregation process for some dyes is isodesmic and provide a second example of a well-characterized chromonic system

Structural behavior of Pby_yBi1.95−y_{1.95-y}Sr1.49_{1.49}La0.4_{0.4}Cu1.15_{1.15}O6+δ_{6+\delta} for 0<y<0.53

In the Bi cuprates, the presence of a near 1$\times$5 superstructure is well known. Usually, this superstructure is suppressed by the substitution of lead, but there have been reports of a phase separation in so called {\alpha} and {\beta} phases. This paper shows in high detail time how and why the phase separation develops and what happens to the quasi-1$\times$5 superstructure upon lead substitution. For this purpose, the lanthanum- and lead-substituted single-layered superconductor Bi$_{2+z}$Sr$_{2-z}$CuO$_{6+\delta}$ has been investigated by scanning tunneling microscopy and low-energy electron diffraction. The La content was kept constant at slightly under-doped concentration while the Pb content was changed systematically. Thermodynamic considerations show that a phase mixture of {\alpha} and {\beta} phases is inevitable.Comment: 17 pages, 4 figure

Quasiparticles and Energy Scaling in Bi2_2Sr2_2Can−1_{n-1}Cun_nO2n+4_{2n+4} (n\it{n}=1-3): Angle-Resolved Photoemission Spectroscopy

Angle-resolved photoemission spectroscopy (ARPES) has been performed on the single- to triple-layered Bi-family high-{\it T$_c$} superconductors (Bi$_2$Sr$_2$Ca$_{n-1}$Cu$_n$O$_{2n+4}$, $\it{n}$=1-3). We found a sharp quasiparticle peak as well as a pseudogap at the Fermi level in the triple-layered compound. Comparison among three compounds has revealed a universal rule that the characteristic energies of superconducting and pseudogap behaviors are scaled with the maximum {\it T$_c$}.Comment: 4 pages, 4 figure

Domestic Queensware in Kensington-Fishtown: Excavating Philadelphia\u27s Waterfront Neighborhoods

Ongoing archaeological excavation undertaken by URS/AECOM along the I-95 corridor in Kensington-Fishtown in Philadelphia have brought to light 18th and 19th century domestic and industrial life along a three-mile section of the Delaware River waterfront. Excavation has revealed over 400 shaft features, yard deposits, and industrial foundations yielding over one million artifacts from a three mile section of the Delaware River waterfront. A small quantity of domestic queensware has been recovered from barrel and wood-lined box privies and from an early 19th century drain feature. The recovery of domestic queensware in Kensington-Fishtown has revealed that this ware had become part of the domestic fabric of early 19th century consumers in this part of the city

The Rise and Fall of American Queensware 1807-1822

. This article examines the history of several manufacturers of American queensware in Philadelphia, Pennsylvania, and beyond. Our research reveals that efforts to produce queensware were more extensive and widespread than previously thought. This survey expanded as we discovered references to contemporary queensware potteries in other parts of the United States during the first two decades of the 19th century. In all, 14 queensware-manufacturing ventures are identified and described from Pennsylvania, New Jersey, Ohio, what is now West Virginia, Vermont, and New Hampshire. Much of this research is drawn from period newspaper notices, advertisements, and surviving personal correspondence. The period sources provide a view of the experimental nature of this industry, document the search for raw materials, and describe various aspects of the manufacturing process

Developments in the negative-U modelling of the cuprate HTSC systems

The paper deals with the many stands that go into creating the unique and complex nature of the HTSC cuprates above Tc as below. Like its predecessors it treats charge, not spin or lattice, as prime mover, but thus taken in the context of the chemical bonding relevant to these copper oxides. The crucial shell filling, negative-U, double-loading fluctuations possible there require accessing at high valent local environment as prevails within the mixed valent, inhomogeneous two sub-system circumstance of the HTSC materials. Close attention is paid to the recent results from Corson, Demsar, Li, Johnson, Norman, Varma, Gyorffy and colleagues.Comment: 44 pages:200+ references. Submitted to J.Phys.:Condensed Matter, Sept 7 200