Some Problems with Negative Refraction
J. B. Pendry's "Negative Refraction Makes a Perfect Lens" is analyzed. It appears that several statements may be understood in terms of lens design but not in terms of fundamental behavior of light.
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Postpolymerization of vinyl acetate‐containing latexes
Abstract The postpolymerization of vinyl acetate (VAc)‐containing latexes with tert ‐butyl hydroperoxide (TBH)/ascorbic acid (AsA) as a redox initiation system was investigated. Volatile organic compounds (VOCs) such as acetone and tert ‐butyl alcohol were produced in this process. The influence of the TBH/AsA ratio,…
Synthesis and characterization of biodegradable poly(ester‐urethanes) based on bacterial poly(R‐3‐hydroxybutyrate)
Abstract A series of poly(R‐3‐hydroxybutyrate)/poly(ε‐caprolactone)/1,6‐hexamethylene diisocyanate‐segmented poly(ester‐urethanes), having different compositions and different block lengths, were synthesized by one‐step solution polymerization. The molecular weight of poly(R‐3‐hydroxybutyrate)‐diol, PHB‐diol, hard seg…
Deposition of Self-Assembled Monolayers in Mesoporous Silica from Supercritical Fluids
Deposition of silane-based self-assembled monolayers onto mesoporous ceramic substrates has been found to be substantially faster from supercritical fluids than from typical condensed phase solutions. In addition, the monolayers so prepared display higher silane population density (6.5 vs 4.6 silanes/nm 2 ), fewer def…
Micro‐MR angiography of normal and intratumoral vessels in mice using dedicated intravascular MR contrast agents with high generation of polyamidoamine dendrimer core: Reference to pharmacokinetic properties of dendrimer‐based MR contrast agents
Pharmacokinetic characteristics of intravascular macromolecular magnetic resonance imaging (MRI) contrast agents with polyamidoamine dendrimer cores smaller than generation-7 were previously studied in the literature. To evaluate the effects of greater hepatic uptake on the pharmacokinetics of the larger generation de…
Chromium Corroles in Four Oxidation States
We have isolated and characterized chromium complexes of 5,10,15-tris(pentafluorophenyl)corrole [(tpfc)H(3)] (1) in four oxidation states: [(tpfc(*))CrO][SbCl(6)] (6); [(tpfc)CrO] (2); [(tpfc)CrO][Cp(2)Co] (4); and [(tpfc)Cr(py)(2)] (3). Complex 6 was prepared both by electrochemical and chemical oxidation of 2; its f…
Sugarcane bagasse reinforced phenolic and lignophenolic composites
Abstract Lignin, extracted from sugarcane bagasse by the organosolv process, was used as a partial substitute of phenol (40 w/w) in resole phenolic matrices. Short sugarcane fibers were used as reinforcement in these polymeric matrices to obtain fiber‐reinforced composites. Thermoset polymers (phenolic and lignophenol…
Nanopatterns by Free-Standing Monolayer Films of Diblock Copolymer Micelles with in Situ Core−Corona Inversion
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTNanopatterns by Free-Standing Monolayer Films of Diblock Copolymer Micelles with in Situ Core−Corona InversionByeong-Hyeok Sohn, Seong-Il Yoo, Byung-Wook Seo, Sang-Hyun Yun, and Sang-Min ParkView Author Information Department of Materials Science and Engineering Polyme…
Nanoparticle Engineering of Complex Fluid Behavior
A new mechanism for regulating the stability of colloidal suspensions has been discovered, known as nanoparticle haloing. 1 Colloidal microspheres suspended under conditions near their isoelectric point were stabilized by the addition of highly charged nanoparticles. Such species segregated to regions near negligibly…
Electric field gradients from first-principles and point-ion calculations
Point-ion models have been extensively used to determine "hole numbers" at copper and oxygen sites in high-temperature superconducting cuprate compounds from measured nuclear quadrupole frequencies. The present study assesses the reliability of point-ion models to predict electric field gradients accurately and also t…
Exciton/free-carrier plasma in GaN-based quantum wells: Scattering and screening
The degree of ionisation of a two-dimensional electron-hole plasma is calculated in the low-density (Boltzmann) limit. The electron-hole interaction is considered for all states: optically active and inactive, bound and unbound. The theory is applied to exciton/free-carrier plasma in GaN-based quantum wells at room te…
Photon recycling white light emitting diode based on InGaN multiple quantum well heterostructure
A numerical method based on the transfer matrix technique is developed to calculate the luminescence spectra of complex layered structures with photon recycling. Using this method we show a strong dependence of the emission spectra on the optical eigenmode structure of the device. The enhancement of the photon recycli…
Comment on “Negative Refraction Makes a Perfect Lens”
A Comment on the Letter by J. B. Pendry, Phys. Rev. Lett. 85, 3966 (2000). The authors of the Letter offer a Reply.Issues similar to those made in the following two Comments were also raised in a paper by N. Garcia and M. Nieto-Vesperinas, Madrid, Spain.
Selective d-state Conduction Blocking in Nickel Nanocontacts
The lowest conductance step for a Ni nanocontact is anomalously small in comparison with the large expected number of conducting channels. We present electronic structure calculations for an extremely idealized Ni nanobridge consisting of just a monatomic nanowire. Our calculations show that no less than eight single…
Preparation and Characterization of Homogeneous YBCO Single Crystals with Doping Level near the SC-AFM Boundary
High-purity and homogeneous YBa2Cu3Oy single crystals with carrier doping level near the AFM-SC boundary have been obtained in the oxygen content range between y = 6.340 and 6.370. The crystals are ortho-II phase at room temperature and undergo the orthorhombic to tetragonal transition at about 140_Degree_C. They show…
Heisenberg exchange parameters of molecular magnets from the high-temperature susceptibility expansion
We provide exact analytical expressions for the magnetic susceptibility function in the high-temperature expansion for finite Heisenberg spin systems with an arbitrary coupling matrix, arbitrary single-spin quantum number, and arbitrary number of spins. The results can be used to determine unknown exchange parameters…
Stabilization of frictional sliding by normal load modulation: A bifurcation analysis
This paper presents the stability analysis of a system sliding at low velocities ($< 100 μ$m.s$^{-1}$) under a periodically modulated normal load, preserving interfacial contact. Experiments clearly evidence that normal vibrations generally stabilize the system against stick-slip oscillations, at least for a modulatio…
Heat Transfer in Nanostructures for Solid-State Energy Conversion
Solid-state energy conversion technologies such as thermoelectric and thermionic refrigeration and power generation require materials with low thermal conductivity but good electrical conductivity and Seebeck coefficient, which are difficult to realize in bulk semiconductors. Nanostructures such as superlattices, quan…
Ghost Excitonic Insulator Transition in Layered Graphite
Some unusual properties of layered graphite, including a linear energy dependence of the quasiparticle damping and weak ferromagnetism at low doping, are explained as a result of the proximity of a single graphene sheet to the excitonic insulator phase which can be further stabilized in a doped system of many layers s…
True Microporosity and Surface Area of Mesoporous SBA-15 Silicas as a Function of Synthesis Temperature
A model based on hexagonal mesopores connected by micropores allows evaluation of the porosity of SBA-15 silicas and elucidation of the literature problems on the subject. The presence of micropores in the walls between the mesopores renders unreliable the surface area determination by the Brunauer−Emmett−Teller equat…