Concerning the relationship between clear‐sky,global and direct‐beam,solar spectra

Clear‐sky direct‐beam and normal global solar spectra were measured with a spectroradiometer with and without a collimating tube. The ratio of the two spectra was found to be well approximated by a simple two‐parameter formula suggested by Rayleigh scattering. Copyright © 2002 John Wiley & Sons, Ltd.     

A model for determining fiber reinforcement efficiencies and fiber orientation in polymer composites

Fiber length contributions to the reinforcement potential in composites have been decoupled from fiber orientation effects with the use of a fiber orientation model. Fiber length efficiency factors and fiber orientation factors are calculated based upon a procedure that requires measuring the composite properties in specified directions relative to a reference direction. The procedure is straightforward and relatively quick compared to the tedious task of actually measuring the fiber length distribution. An example illustrating the utility of the procedure is given and then followed by a discussion qualifying the significance of the factors and the results.     

Folgeprodukte halogenierter Aldehyde. XIV [1]. Synthesen mit 1,2,2,2-Tetrachlorethylisocyanat

Derivatives of Halogenated Aldehydes. XIV. Reactions of 1,2,2,2-Tetrachloroethyl Isocyanate 1,2,2,2-Tetrachloroethyl isocyanate 2 reacts with alcohols or phenols to form the N-tetrachloroethyl-O-alkyl(aryl) urethanes 3–6 . With thioalcohols and thiophenols the corresponding thiourethanes 11–12 are obtained. In these compounds the chlorine in position 1 can be substituted by treatment with a nucleophilic compound in the presence of a base by way of an elimination addition mechanism. In these reactions the compounds 7–10 and 13–14 are formed. Amines attack 2 at both active centres to give the substituted ureas 15–18 . Diphenyl amine, some carboxylic acid amides and benzazoles, however, react only with the isocyanate group to form the compounds 19–25 . Reactions of 2-amino-benzazoles, 2-amino-pyridine and amidines with 2 yield the heterocyclic compounds 26–31 .     

Debottlenecking of an In Vitro Enzyme Cascade Using a Combined Model- and Experiment-Based Approach

Designing a feasible in vitro enzyme cascade is a challenging task that is often preceded by optimization steps. Computational methods can increase the efficiency of the optimization process by providing a deeper insight into the system. In this study, bottlenecks of a farnesyl pyrophosphate-producing in vitro enzyme cascade were determined by a combination of in silico modeling and wet-lab experiments. ATP and the precursor-isomerizing enzyme isopentenyl diphosphate δ-isomerase were identified as limitations of the in vitro enzyme cascade.     

Darstellung und Eigenschaften hexasubstituierter Benzenderivate

Preparation and Properties of Hexasubstituted Benzenes Hexasubstituted benzenes are of potential interests as polypodands, host molecules and disc-like molecules. They are prepared by catalytic cyclotrimerization of disubstituted alkynes 1–8 or by nucleophilic substitution of bromine in hexakis (bromomethyl)benzene 9–17 . The different methods of preparation were compared. The new hexasubstituted benzenes were characterized by some chemical and physical properties.     

Reaction of Hexamethylphosphorus Triamide with Starch Studies on a new phosphorus starch derivative

On studying the reaction between hexamethylphosphorus triamide and starch, several reaction media were tried aiming to a medium in which derivatives with a low degree of substitution would be obtained. The greatest yield (phosphorus content up to 0.7%) was achieved by refluxing the mixture in organic solvents. The granules of the derivatives so obtained were quite modified. They swell in cold water, are insoluble in organic solvents, are strongly anionic and their gelatinization temperatures decrease with the increase in the degree of substitution. Their pastes, either when cold or hot, present similar viscosity values.     

Particulate multi‐phase polymeric nanocomposites

The present research focuses on a model system of a blend of two immiscible polymers containing an inorganic nanofiller, exploring the effect of various melt processing procedures on structuring and on the resulting properties. Binary polypropylene/alumina and ternary polypropylene/nylon/alumina composites were produced by batch compounding under various processing conditions and compositions. Several types of polypropylene and alumina grades were examined. The alumina nanoparticles vary primarily in their mean particle size (13, 50, 500 nm). The morphology of the nanocomposites produced and their thermal, and rheological properties were studied. It was found that under certain processing conditions the nanoparticles significantly affect the morphology of the polypropylene/nylon polymer blend causing compatibilization. Also, the alumina nanoparticles affect the melt viscosity of the polypropylene/nylon blends, whereas their effect on either polypropylene or nylon melts was found insignificant. POLYM. COMPOS., 27:425–430, 2006. © 2006 Society of Plastics Engineers     

Mode I interlaminar fracture toughness of Nylon 66 nanofibrilmat interleaved carbon/epoxy laminates

Carbon/epoxy laminates interleaved with laboratory scale electrospun Nylon 66 nanofibrilmat and spunbonded nonwoven mats were investigated. The effect of the nanoscale fibers on the fracture toughness of the composite under pure Mode I loading was evaluated. It was shown that the nanofibrilmat is responsible for a major interlaminar fracture toughness improvement, as high as 255–322%, compared to a noninterleaved carbon/epoxy reference laminate. We further studied the improvement mechanism of the electrospun nanofibrilmat compared to a commercial spunbonded nonwoven Nylon 66 mat. A combination of two interlayer fracture mechanisms responsible for the toughness improvement is suggested: the first is related to the high energy dissipated by bridged thermoplastic nanofibers and the second is attributed to the generation of a plastic zone near the crack tip. The interlaminar fracture mechanisms of both electrospun nanofibrilmat and the nonwoven mat interleaving was analyzed and discussed. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers