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Selective Etching of Semicrystalline Polymers: CF4 Gas Plasma Treatment of Poly(ethylene)
A series of poly(ethylene) (PE) films with different degrees of crystallinity was treated with a radio-frequency tetrafluoromethane (CF 4 ) gas plasma (48−49 W, 0.06−0.07 mbar, and continuous vs pulsed treatment). The etching behavior and surface chemical and structural changes of the PE films were studied by weight m…
Application of Calcium Acetylacetonate to the Polymerization of Glycolide and Copolymerization of Glycolide with ε-Caprolactone andl-Lactide
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTApplication of Calcium Acetylacetonate to the Polymerization of Glycolide and Copolymerization of Glycolide with ε-Caprolactone and l-LactidePiotr Dobrzyński, Janusz Kasperczyk, and Maciej BeroView Author Information Centre of Polym…
Depletion-Induced Crystallization in Colloidal Rod−Sphere Mixtures
We report the observation of depletion-induced phase separation in a mixture of colloidal silica spheres and colloidal silica rods with light microscopy and confocal scanning laser microscopy. We show that very low rod concentrations are sufficient to induce sphere crystallization. This qualitatively agrees with theor…
Reactive Extrusion: Toward Nanoblends
By nanoblends, it is meant that the scale of dispersion of one polymer phase in the other is below 100 nm. A novel method was developed to prepare nanostructured blends (nanoblends) of polypropylene (PP) and polyamide-6 (PA-6) directly in a screw extruder. It consisted of polymerizing a monomer of PA-6, ε-caprolactam…
Dephasing of Local Vibrations in a Planar Lattice of Adsorbed Molecules
We investigate anharmonically coupled high- and low-frequency excitations in a planar lattice of adsorbed molecules interacting with phonons of a crystal. Dephasing of high-frequency local vibrations by low-frequency resonance modes is described in terms of temperature Green's function. The equations obtained are solv…
Spinodal decomposition of an ABv model alloy: Patterns at unstable surfaces
We develop mean-field kinetic equations for a lattice gas model of a binary alloy with vacancies (ABv model) in which diffusion takes place by a vacancy mechanism. These equations are applied to the study of phase separation of finite portions of an unstable mixture immersed in a stable vapor. Due to a larger mobility…
Charge Transport through Chemically Modified Electrodes: a General Analysis for Ion Exchange and Covalently Attached Redox Polymers
The influence of physical diffusion of the electroactive species on the mechanism of charge transport in chemically modified electrodes is analyzed for ion exchange and covalently attached redox polymers with explicit consideration of vacant sites. The appropriate flux equation for charge transport is derived using ph…
Formation of adenosine 5′‐tetraphosphate from the acyl phosphate intermediate: a difference between the MurC and MurD synthetases of Escherichia coli
The mechanism of the Mur synthetases of peptidoglycan biosynthesis is thought to involve in each case the successive formation of an acyl phosphate and a tetrahedral intermediate. The existence of the acyl phosphates for the MurC and MurD enzymes from Escherichia coli was firmly established by their in situ reduction…
On the nature of the assembly trajectory
Introduction Assembly is a basic device of nature where a broad range of entities, spanning many levels of scale, interact across time and space to produce oberserved pattern. Entities such as individuals, phenotypes, populations, guilds, and higher levels of organization like hierarchical structures are all subject t…
Crystalline Regions of Bombyx mori Silk Fibroin May Exhibit β-Turn and β-Helix Conformations
Modeling of the (GSGAGA) n consensus sequence of the crystalline region of Bombyx mori silk fibroin revealed two novel conformations. One was a series of four-residue β-turns, consistent with published circular dichroic spectra and nuclear magnetic resonance data for the water-soluble silk I that is found in the abdom…
Synthesis and Characterization of Highly Cross-Linked, Monodisperse Core−Shell and Inverted Core−Shell Colloidal Particles. Polystyrene/Poly(tert-butyl Acrylate) Core−Shell and Inverse Core−Shell Particles
We report on the synthesis of nearly monodisperse phase-separated polymer latexes with a well-defined core−shell morphology. Styrene/diisopropenylbenzene and tert -butyl acrylate/ethylene glylcol-diacrylate were used for either the core or shell of the composite microgel particles. A major concern of the paper is the…
Phonon and Elastic Instabilities in MoC and MoN
We present several results related to the instability of MoC and MoN in the B1 (sodium chloride) structure. These compounds were proposed as potential superconductors with moderately high transition temperatures. We show that the elastic instability in B1-structure MoN, demonstrated several years ago, persists at elev…
Instabilities in crystal growth by atomic or molecular beams
The planar front of a growing a crystal is often destroyed by instabilities. In the case of growth from a condensed phase, the most frequent ones are diffusion instabilities, which will be but briefly discussed in simple terms in chapter II. The present review is mainly devoted to instabilities which arise in ballisti…
Application of Raman Scattering to Study the Strain Distribution in SiGe Layers
In this paper, we mainly present a new simple, efficient and nondestructive Raman scattering analysis method to study the distribution of strain in SiGe alloy films. The method can simultaneously determine both Ge fractional composition x and strain of SiGe films. We use the Ar+ laser lines (514.5, 488 and 457.9 nm) t…
Application of Ultraviolet Fluorescence in Wafer Surface Cleaning Analysis
Ultraviolet fluorescence (UVF) is introduced as a novel and versatile method for the determination of the contamination of metal impurities on silicon wafer surfaces. The results given demonstrate the usefulness of UVF for contamination control in silicon wafer processing. The experiments show some main characteristic…
Processing and Characterization of Single-Crystalline Ultrafine Bismuth Nanowires
By pressure injecting Bi liquid melt into the nanochannels of an anodic alumina template, we have successfully fabricated Bi nanowire arrays with ultrafine wire diameters and extremely high wire packing densities. Free-standing Bi nanowires with controlled wire diameters and large aspect ratios (length/diameter) were…
Study of Multiple Relaxations in Crown Ethers by Dielectric Relaxation Spectroscopy
An investigation was carried out on the dipole dynamics of low molecular weight crown ether series and related compounds by dielectric relaxation spectroscopy (DRS). An unexpected discovery regarding two main relaxations observed by DRS and calorimetric (DSC) measurements have been analyzed using neat and solvent-pres…
Surface Hardness of Pristine and Modified Polyaniline Films
The surface microhardness of conventional thermoplastics lie between 0.1 and 0.6 GPa. The as-cast emeraldine (EM-25) base film of polyaniline (PANi) exhibits a surface microhardness of about 1 GPa. The hardness is increased to about 4 GPa in the highly cross-linked EM (EM-150) film. This hardness value is further enha…
A Study of the N2 Formation Mechanism in Carbon−N2O Reaction by Using Isotope Gases
To clarify the N 2 formation mechanism during the C−N 2 O reaction, the detailed nitrogen mass balance was established. It was also attempted to reveal the role of surface nitrogen species in this reaction by using isotope gases. In contrast to the case of the C−NO reaction, the accumulation of nitrogen on the carbon…