Effects of display format on proof-reading with VDUs

Two experiments are reported which compared proof-reading performance in various VDU display formats. Experiment 1 found that displaying text one paragraph at a time improved the accuracy of performance, relative to a full screen condition, but at the expense of speed. Subjects also preferred using the paragraph format. Display contrast (positive vs negative) had no effect on performance. Experiment 2 supported the findings of Experiment 1, and found increased accuracy when text was further subdivided into sentences, but speed was again reduced. Possible explanations for the format effect are presented, and its practical implications are considered.     

Evolution of the Pore Size Distribution in Final-Stage Sintering of Alumina Measured by Small-Angle X-ray Scattering

Small-angle X-ray scattering was used to follow the evolution of the pore size distribution during final-stage sintering of alumina and of alumina doped with 0.25 wt% magnesia. The volume-weighted (Guinier) results indicate that the effective size of the largest pores increases as the body goes from 97% to more than 99% dense. The surface-area-weighted (Porod) results show that the median size of the smallest pores decreases slightly over the same density range. Taken together, these data indicate that the pore size distribution becomes broader as final-stage densification proceeds. This was confirmed by a maximum entropy analysis, which was used to derive pore size distributions directly from the data. Finally, the evolution of the pore size distributions in alumina, with and without sintering aid, were compared.     

Physical properties of model graft copolymers and their use as blend compatibilizers

The present investigation pertains to the structure–property relationships of highly structured graft copolymers. The specific model graft copolymers are based on an elastomeric backbone, i.e., poly(ethyl acrylate), and monodisperse thermoplastic grafts, i.e., polystyrene. The synthesis of these graft copolymers is based on the free-radical polymerization of ethyl acrylate and an anionically polymerized polystyrene macromonomer. It is clearly demonstrated that grafts significantly enhance tensile properties. The level of improvement is directly related to the graft level, i.e., number of grafts/chain, and graft molecular weight. In addition, blending these graft copolymers into their respective homopolymer mixture results in a mechanical performance strikingly dependent on the molecular characteristics of the graft copolymer. For example, tensile strength is maximized at a level between one and two grafts per chain. This result parallels observations noted in blend compatibilization using diblock and triblock copolymers. It is also demonstrated that using mutually grafted copolymers produces an interesting variety of compatibilized ternary (or higher) component blends. © 1994 John Wiley & Sons, Inc.     

LIQUID PHASE OXIDATION OF THIOPHENOL AND INDENE BY t-BUTYL HYDROPEROXIDE AND OXYGEN

The tert-butyl hydroperoxide (tBHP) or oxygen initiated oxidation of thiophenol in the presence of the active olefin indene was examined in benzene at 120C. The reaction is kinetically complex, but it was possible to relate the product distribution to a few competing reactions. The product mix was determined for several reaction time periods. The product slate was similar for all time periods, but yields of the individual components varied significantly with increasing reaction time. Gaseous products included isobutylene and a trace of methane. The major product from tBHP was t-butanol. The major product observed from thiophenol was phenyl disulfide. Addition products included the major product 2-phenylthiyl indan. Oxidation products included: indanols, indanones, and the sulfoxide and sulfone of the major product 2-phenylthiyl indan. Solvent participtation was noted by trace amounts of toluene.     

Congenital defects of the bovine musculoskeletal system and joints

A variety of structural and functional congenital defects affecting the central nervous system of cattle have been identified. This article discusses specific defects of the central nervous system. Spastic and paralytic, metabolic, and storage diseases are reviewed.