Unraveling the Weave of Spider Silk
Ricki Lewis; Unraveling the weave of spider silk: One of nature's wondrous chemical structures is being dissected so that it can be used in human inventions, Bi
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Reflection Asymmetric Powder Diffraction with Flat-Plate Sample using a Curved Position-Sensitive Detector (INEL CPS 120)
The reflection flat-sample asymmetric geometry is an attractive set-up for powder diffraction measurements, as compared to either conventional Debye–Scherrer or symmetric Bragg–Brentano geometries. Combined with grazing- or fixed-incidence-angle X-rays, it is suitable for surface-structure or thin-film texture analysi…
A THREE-DIMENSIONAL SIMULATION OF BRITTLE SOLID FRACTURE
This paper describes an extension into three dimensions of an existing two-dimensional technique for simulating brittle solid fracture. The fracture occurs on a simulated solid created by "gluing" together space-filling polyhedral elements with compliant interelement joints. Such a material can be shown to have well-d…
Crystal Structure of the Pentamolybdate Complex Coordinated by Adenosine-5′-monophosphoric Acid
Abstract Na2[(Hamp)2Mo5O15]·6H2O (where amp is adenosine-5′-monophosphate) has been crystallized by acidifying a solution containing Na2MoO4·2H2O and adenosine-5′-monophosphoric acid (AMP = H2amp) to pH 3—4. A single-crystal X-ray structural analysis of a colorless crystal of Na2[(Hamp)2Mo5O15]·6H2O [space group P3121…
Runaway phenomena in low‐density polyethylene autoclave reactors
Abstract To study runaway behavior in autoclave low‐density polyethylene (LDPE) reactors, a kinetic model for a perfectly stirred tank reactor is presented. The kinetic model not only includes the standard initiation, propagation, and termination reactions for polymerization, but it also has free radical reactions tha…
Methanol as a rapid fixative for the investigation of plant surfaces by SEM
A rapid fixation/dehydration method of plant specimens for scanning electron microscopy is presented. Prior to critical‐point drying (CPD) the specimens are immersed in pure methanol. Methanol incubation instantly fixes the elastically extended cell walls. Owing to this instant fixation, shrinking of the specimens is…
Synthesis, characterization, and energetics of solid solution along the dolomite-ankerite join, and implications for the stability of ordered CaFe(CO 3 ) 2
Other| October 01, 1996 Synthesis, characterization, and energetics of solid solution along the dolomite-ankerite join, and implications for the stability of ordered CaFe(CO 3 ) 2 L. Chai; L. Chai Princeton University, Department of Geological and Geophysical Sciences, Princeton, NJ, United States Search for other wor…
The Cold Fog Test
The electrical performance of outdoor insulation degrades severely during combinations of factors that include surface contamination (C), ice (I), fog (F) and an ambient temperature that rises through 0 C (T{sub 0{degree}}). Failures at operating voltage on 115-kV, 230-kV and 500-kV systems occur with increasing proba…
The effect of external field symmetry on the antiferroelectric-ferroelectric phase transformation
The antiferroelectric (AFE)-ferroelectric (FE) phase transformation under dc bias and hydrostatic pressure conditions in tin-modified lead zirconate titanate ceramics [Pb(Zr,Sn,Ti)O3, i.e., PZST] was investigated. The shifting of transformation temperature under these conditions and an electric field induced lattice s…
Structure of the cholesteric focal conic domains at the free surface
Atomic force microscope examinations of the free surface and of microtome cuts of a cholesteric oligomer are reported. The obtained images lead to a model of the structure of cholesteric focal conic domains that appear spontaneously at the free surface. These domains develop in order to fulfill the boundary condition…
Coordination polymerization of lactides, 5. Influence of lactide structure on the transesterification processes in the copolymerization with ε‐caprolactone
Abstract The influence of lactide configuration on the chain microstructure of lactide/ε‐caprolactone copolymer was investigated. The copolymerization was carried out in the presence of Al(acac) 3 , AlEt 3 and ZnEt 2 as initiators. The chain microstructure analysis of the copolymers was performed by means of 13 C NMR…
Electrochemical Emission Spectroscopy for Monitoring Uniform and Localized Corrosion
A modified electrochemical noise (EN) technique (electrochemical emission spectroscopy [EES]) was developed for nondestructive, real-time corrosion rate measurements. Unlike conventional corrosion-rate measuring techniques that use external signals, this technique uses signals generated by the corroding system. It can…
CARBON NANOTUBE MATERIALS FOR HYDROGEN STORAGE
Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and hi…
Liquid crystalline block and graft copolymers
Abstract Since the first reports on the combination of liquid crystalline polymers in block (1985) and graft (1986) copolymers with amorphous and semi‐crystalline polymers, the scientific interest has been focused on understanding how the size and type of the mesophase displayed by the liquid crystalline part(s) affec…
Metastable Bubble Solutions for the Allen-Cahn Equation with Mass Conservation
In a multidimensional domain, the slow motion behavior of internal layer solutions with spherical interfaces, referred to as bubble solutions, is analyzed for the nonlocal Allen–Cahn equation with mass conservation. This problem represents the simplest model for the phase separation of a binary mixture in the presence…
Models for the frequency dependence of coercive field and the size dependence of remanent polarization in ferroelectric thin films
We have confirmed the theory of Ishibashi and Orihara for the frequency dependence of coercive fields in ferroelectric thin films.SrBi2NbTaO9, SrBi2Ta2O9, and PbZr1-x Ti x O3 (PZT) data from DeVilbis et al. reveal a power-law dependence of form Ec (f) = Bfd/α , where d is the dimensionality of domains (ca. unity in un…
Extensional deformation of Newtonian liquid bridges
A numerical investigation is presented of axisymmetric, static and elongating, viscous Newtonian liquid bridges confined between identical circular disks. The time-dependent interface shapes and applied forces on the end plates, which separate at a constant prescribed velocity, are calculated as functions of the capil…
Reduction of Nitrate By Fe2+ in Clay Minerals
Abstract In the 12 km 2 catchment area of Syv creek, Denmark, moderate to high concentrations of nitrate (NO 3 − ) occurred in the upper part of the oxidized zone (oxic-I), but dropped within the lower suboxic part (oxic-II), to below the detection limit in the unoxidized zone. Structural Fe 2+ in the clay minerals ma…
Implementation of a numerical needle method for thin-film design
A variant of the powerful thin-film needle design technique, which was first described by Tikhonravov and his co-workers, is described. In this method thin layers are introduced at optimum positions within the refractive-index profile of a given multilayer system. In the original method the optimum locations for the l…
Formation of Monodisperse Spherical TiO 2 Powders by Thermal Hydrolysis of Ti(SO 4 ) 2
Titania powders have been prepared by the thermal hydrolysis of titanium sulfate at 80°C in a mixed solvent of n ‐propyl alcohol ( n ‐PrOH) and water. The morphology of the powders was greatly influenced by the volume ratio in n ‐PrOH to water (RH ratio) of the solvent. An RH ratio of 1.0 was essential for the formati…