Materials Literature
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The catalytic activity of mesoporous silica (MCM-41) for the acetalization of cyclohexanone shows a volcano-shaped dependence on the pore diameter. The diameter of the cyclohexanone molecule is ca. 0.75 nm, while its acetalization with methanol was well accelerated on MCM-41 with a pore diameter of approximately 1.9 n…
The thicknesses of polyelectrolyte multilayer thin films (PEMs) are reported as a function of deposition temperature and ionic strength. PEMs fabricated at high salt and elevated temperatures are significantly thicker than similar films deposited at room temperature. These trends in the multilayer films are not observ…
A structure formed by combined lattices of infinitely long wires and split-ring resonators is studied. A dispersion equation is derived and then used to calculate the effective permittivity and permeability in the frequency band where the lattice can be homogenized. The backward wave region in which both the effective…
A novel semidiscrete Peierls–Nabarro model is introduced which can be used to study dislocation spreading at more than one slip plane, such as dislocation cross-slip and junctions. Within this essentially continuum model, the nonlinearity which arises from the atomic interaction across the slip plane is dealt with ato…
Eleven bis-ureas have been synthesized, and some of their properties are reported. Several of these compounds form supramolecular polymers in organic solvents. The self-association is shown by FTIR spectroscopy to display cooperativity at two levels. The first level of cooperativity is due to the synergistic associati…
Abstract This introductory review paper summarizes shortly the research on metal dusting, conducted in the MPI for Iron Research during the last dozen years. Metal dusting is a disintegration of metals and alloys to a dust of graphite and metal particles, occurring in carburizing atmospheres at a C > 1 and caused b…
In a superlattice containing a finite number of periods, the allowed values of the Bloch wave number form a discrete set, and the dynamics of an electron through k-space under the influence of an external force is necessarily that of a superposition wave packet composed of multiple Bloch waves. The present paper inves…
It is well known that the Poiseuille flow of a visco-elastic polymer fluid between plates or through a tube is linearly stable in the zero Reynolds number limit, although the stability is weak for large Weissenberg numbers. In this paper we argue that recent experimental and theoretical work on the instability of visc…
The propagation characteristics of a two-dimensional (2-D) negative refractive index (NRI) transmission line (TL) structure are explained using Bloch theory. Bloch analysis of a generalized 2-D periodic electrical network is performed and the results are applied to the NRI TL structure. A 2-D Brillouin diagram of the…
ABSTRACT Dated sediment cores from five alpine lakes (>3200 m asl) in Rocky Mountain National Park (Colorado Front Range, USA) record near‐synchronous stratigraphic changes that are believed to reflect ecological and biogeochemical responses to enhanced nitrogen deposition from anthropogenic sources. Changes in sed…
“Drogenschmuggel”: Präpariert wurden Micellen aus Blockcopolymeren und dem Tumortherapeutikum Adriamycin (ADR), das über einen pH-sensitiven Linker an das Polymer gebunden ist (siehe Bild). Die Micellen gelangen durch Endocytose, unter Umgehung der Zellmembrantransporter, in die Krebszelle. Innerhalb der Zelle löst ei…
Abstract The conversion of processed discarded material into valuable by‐products and alternative specialty materials has been identified as a timely challenge for food research and development associated with numerous applications of chitinous products. Chitin, chitosan, calcareous chitin, and chitosan, N ‐acetylated…
Composite materials with thermoplastic matrices and a reinforcement of natural fibers are increasingly regarded as an alternative to glass fiber-reinforced composites. The substitution of the traditionally used reinforcing glass fibers by natural fibers such as flax, kenaf, or cotton can lead to a reduction of the com…
Small and attractive: The proligand citric acid has been used to assemble a new anionic hexanuclear cobalt(II) cluster (see picture). The complex displays single-molecule magnet (SMM) behavior, with an energy barrier to the reorientation of magnetization of 26 K, the highest value to have been recorded for a non-manga…
This paper is primarily focused in studying the effects of nanoclay particles such as montmorillonite on improving mechanical and thermal properties of fiber reinforced polymer matrix composite materials. Basic correlations between polymer morphology, strength, modulus, toughness, and thermal stability of thermoset na…
The subunit interfaces of 122 homodimers of known three-dimensional structure are analyzed and dissected into sets of surface patches by clustering atoms at the interface; 70 interfaces are single-patch, the others have up to six patches, often contributed by different structural domains. The average interface buries…
We present the design and implementation of a periodically loaded transmission line, which simultaneously exhibits negative refractive index (NRI) and negative group delay (and, hence, negative group velocity). This is achieved by loading the transmission line in series with capacitors and RLC resonators and in shunt…
Magnetostrictive Terfenol-D (Tb(x)Dy(1-x)Fe2) and piezoelectric (Pb(Zr(1-x)Ti(x))O3) magnetoelectric (ME) laminate composites have been investigated experimentally for various modes of operation: longitudinal magnetized/longitudinal polarized (L-L mode), transverse magnetized/longitudinal polarized (T-L mode), and tra…
We study a composite medium consisting of insulating magnetodielectric spherical particles embedded in a background matrix. Using results from the literature going back as far as Lewin (1947), we show that the effective permeability and permittivity of the mixture can be simultaneously negative for wavelengths where t…
Here, we analyze the transverse-magnetic (TM) wave interaction with a pair of slabs, one being an epsilon-negative (ENG) layer in which the real part of permittivity is assumed to be negative while its permeability has positive real part, and the other being a mu-negative (MNG) layer that has the real part of its perm…