Airborne differences in odors emitted byRattus norvegicus in response to reward and nonreward

To test the hypothesis that rats (Rattus norvegicus) emit airborne, differential odors in response to reward and nonreward, donor rats received random sequences of rewarded and nonrewarded placements in small compartments and an airstream transported odors from these compartments to test rats in a separate chamber. When donors remained in the compartments during, or were removed just prior to, air transport, test rats utilized transported odors as discriminative cues signaling their own reward and nonreward for a lever-press response. When the airstream was passed through a clean compartment containing paper flooring extracted from donor compartments, test rats were not able to discriminate. Test trials to assess for control by food odors suggest that donor-produced odors, rather than food odors per se, provided the discriminative signals for test rats. Results confirm the existence of somewhat volatile, although apparently stable, odors emitted in response to reward and nonreward, and implicate a differential in amount and/or type of odor produced by donors to these two events as the source of discriminative control.     

The Pigmentation of Acrylic Resins*

Acrylic resins may be divided into two main categories—solvent-bome and water-borne systems—and these have been further subdivided into two groups, namely solutions and dispersions. Problems associated with the pigmentation of acrylic resins are discussed, and methods of assessing the wetting properties of the system are mentioned. The use of wetting and dispersing agents is examined, and the concept of the hydrophilic-lyophilic balance (HLB) value is investigated in this context. Pigmentation is one important factor that must be considered in assessing the exterior durability of acrylic resins, certain types of which are ideal media for metallic finishes because of their excellent polishing and weathering properties. The phenomenon of geometric metamerism associated with metallic finishes is discussed.     

Oxidation of Butane to Maleic Anhydride using Vanadium Phosphate Catalysts: Comparison of Operation in Aerobic and Anaerobic Conditions using a Gas-gas Periodic Flow Reactor

The use of a periodic flow reactor is described for the oxidation of butane to maleic anhydride to compare the catalytic performance of vanadium phosphate catalysts operating under aerobic and anaerobic conditions. It is found that for the catalyst prepared via a standard VPO method, operation in the absence of oxygen leads to a very small enhancement in selectivity when butane concentrations in the range 0.9–2.9% are used. Operation in the absence of oxygen leads to very small differences in conversion such that the overall yield is enhanced and this effect is maximised for reactor feeds containing 1.5% butane. However, the enhancement is negligible when the catalyst is operated at high conversion required for commercial operation, indicating that reactors operating with continuous flow with aerobic conditions are preferred. Similar experiments are conducted for a catalyst prepared by the VPD method and, in contrast, this catalyst gives lower butane conversion and maleic anhydride selectivity when operated in the absence of oxygen.     

Controller design for nonlinear systems using the Contoured Robust Controller Bode plot

In this paper, we develop the Contoured Robust Controller Bode (CRCBode) plot and demonstrate its use in the design of robust controllers for nonlinear single‐input single‐output (SISO) systems. The CRCBode plot shows contours (level sets) of a robust performance quantity on the Bode magnitude and phase plots of the controller. An iterative frequency domain loop‐shaping design approach is employed to eliminate all intersections of the controller frequency response with certain ‘forbidden regions,’ indicating that a standard SISO robust stability and performance criterion is satisfied. Nonlinearities are accounted for by avoiding the maximum forbidden regions over a structured uncertainty set consisting of linearizations of the system dynamics about several operating points. We demonstrate this technique by designing and experimentally verifying a flow‐rate controller for a butterfly‐valve based liquid cooling system, which is robust to valve nonlinearities and flow disturbances. Finally, we compare this compensator with one generated using an automated H _∞ synthesis algorithm and discuss the advantages of the CRCBode approach. Copyright © 2013 John Wiley & Sons, Ltd.     

Nonaqueous poly(methyl methacrylate) dispersions: radical dispersion polymerization in the presence of AB block copolymers of polystyrene and poly(dimethyl siloxane)

Well defined AB block copolymers of polystyrene (PS) and poly(dimethyl siloxane) (PDMS) have been prepared with PS molecular weights in the range 8 800 to 43 600 and PDMS molecular weights in the range 2 400 to 48 000. Provided the PS and PDMS molecular weights have a ratio within the range 0.5 to 4.0, these block copolymers stabilize particles of poly(methyl methacrylate) in n-alkanes. The particle size over the range 0.1 to 0.5 μm may be varied by performing dispersion polymerizations of methyl methacrylate as a function of monomer content of the seed stage and as a function of the concentration, molecular weight and composition of the block copolymer. From silicon analyses of the poly(methyl methacrylate) particles, values of the surface area stabilized per PDMS chain were established. The results indicate complete surface coverage of the particles.     

Solvent-free oxidation of benzyl alcohol using titania-supported gold–palladium catalysts: Effect of Au–Pd ratio on catalytic performance

The oxidation of benzyl alcohol with molecular oxygen under solvent-free conditions has been investigated using a range of titania-supported Au–Pd alloy catalysts to examine the effect of the Au–Pd ratio on the conversion and selectivity. The catalysts have been compared at high reaction temperature (160 °C) as well as at 100 °C, to determine the effect on selectivity since at lower reaction temperature the range of by-products that are formed are limited. Under these conditions the 2.5 wt.% Au–2.5 wt.% Pd/TiO₂ was found to be the most active catalyst, whereas the Au/TiO₂ catalyst demonstrated the highest selectivity to benzaldehyde. Toluene, formed via either a hydrogen transfer process or an oxygen transfer process, was observed as a major by-product under these forcing conditions.     

Water as a Promoter of the Complete Oxidation of Volatile Organic Compounds over Uranium Oxide Catalysts

The effect of water addition on the complete oxidation of benzene and propane VOCs by uranium oxide catalysts has been investigated. Benzene oxidation was studied using a silica supported U₃O₈ catalyst. Complete oxidation is promoted by the addition of 2.6% water compared with the reactivity when no water is added to the reactant feed. Increasing the water concentration to 12.1% resulted in a suppression of oxidation activity. Investigation of propane oxidation using U₃O₈ shows a dramatic promotion of activity. Propane conversion was ca. 50% at 600 °C without added water, whilst it increased to 100% at 400 °C with the addition of 2.6% water. A comparison of oxidation activity has been made with Mn₂O₃, an oxide recognised for complete oxidation. In contrast to the U₃O₈ catalysts the addition of 2.6% water suppresses the activity of Mn₂O₃. In situ powder X-ray diffraction studies showed that the bulk U₃O₈ structure was stable under all the reaction conditions. The origin of the increased activity is not clear but may be due to modification of the catalyst surface and the contribution from new reaction pathways such as steam reforming.     

Mandibular gland components of european and africanized honey bee queens (Apis mellifera L.)

The composition of the five-component honey bee queen mandibular gland pheromone (QMP) of mated European honey bee queens was compared to those of virgin and drone-laying (i.e., laying only haploid unfertilized eggs that develop into males), European queens and Africanized mated queens. QMP of mated European queens showed significantly greater quantities of individual components than all queen types compared, except for a significantly greater quantity of 9-hydroxy-(E)-2-decenoic acid (9-HDA) found in Africanized queens. Glands of European drone-laying queens contained quantities intermediate between virgin and mated queens, reflecting their intermediate reproductive state and age. QMP ontogeny shifts from a high proportion of 9-keto-(E)-2-decenoic acid (ODA) in young unmated queens to roughly equal proportions of ODA and 9-HDA in mated queens. A biosynthetic shift occurs after mating that results in a greater proportion of 9-HDA, methylp-hydroxybenzoate (HOB), and 4-hydroxy-3-methoxyphenylethanol (HVA) production, accompanied by a decreased proportion of ODA. Africanized QMP proportions of ODA and 9-HDA were significantly different from European queens. A quantitative definition of a queen equivalent of QMP is proposed for the various queen types, and a standard queen equivalent for mated European honeybee queen mandibular gland pheromone is adopted as 200µg ODA, 80µg 9-HDA, 20µg HOB, and 2 µg HVA.     

Transparent,methacrylate-based polymer networks with controlled crosslinker ductility

A series of transparent methacrylate-based crosslinked polymer networks are prepared in which the crosslinker length is controlled as a means to investigate the effects of network ductility on mechanical and ballistic properties. In each network the optical clarity of pure poly(methyl methacrylate) (PMMA) is retained, as well as a low value of haze. Both the glass transition temperature (T_g) and the tensile modulus of the networks are highly tunable, with network values both above and well below that of pure PMMA or the pure crosslinker network. The ballistic performance is likewise affected, with performance values of up to 400% greater than neat PMMA. We examine the effects of the crosslinker molecular weight on the impact performance, finding that, in these systems, the molecular weight between crosslinks is not a driving factor for the impact performance, and this may broadly translate to polymer networks in general. We find that improvements in ballistic performance can be realized at low molecular weight between crosslinks, provided the crosslinking agent is of sufficient ductility.     

Location of steel reinforcement in concrete using ground penetrating radar and neural networks

Ground-penetrating radar is becoming increasingly popular for use as a non-destructive assessment method for investigating reinforced concrete structures. The amount of data collected however can be very large and take a significant level of subjective experience to interpret. This study focuses upon the use of a neural network approach to automate and facilitate the post-processing of ground penetrating radar results. The radar data is reduced to a simplified data set by using an edge detection routine. Signal reflections from reinforcing bars displaying a hyperbolic image format are detected using a multi-layer perceptron (MLP) network with a single hidden layer containing 8 nodes to recognise a simplified hyperbolic shape. Training and testing of the network was carried out making use of an emulsion analogue tank, simulating the properties of concrete, and using real concrete specimens. The results showed that the use of a MLP neural network approach could be quite effective in automating the identification and location of embedded steel reinforcing bars from a radar investigation. Accurate estimation of depth, or cover, requires a reliable knowledge of the dielectric properties of the concrete, and recent work using a specially-developed wideband horn antenna for direct determination of in situ properties is also outlined.