Field responses of the western pine beetle1 and one of its predators to host- and beetle-produced compounds

The responses of the western pine beetle (Dendroctonus brev-icomis LeConte) andTemnochila chlorodia (Mannerheim) to candidate attractants—exo- andendo-brevicomm, frontalin,trans-verbenol, ver-benone, and ponderosa pine turpentine and its major monoterpene components—were quantified by counts of beetles on traps baited with the various attractants, singly and in combinations released simultaneously. Combinations ofexo-brevicomin and frontalin plus a monoterpene or turpentine were the most attractive toD. brevicomis. The responses to these attractant combinations were reduced when verbenone plustrans-verbenol were present. All single compounds and binary mixtures, exceptexo-brevicomin plus frontalin, were much less attractive.exo-Brevicomin was most attractive toT. chlorodia, and this response appeared to decrease when verbenone plustrans-verbenol were present.Coleoptera: Scolytidae.Coleoptera: Trogositidae.This research was supported in part by the Forest Service, U.S. Department of Agriculture, and in part by grants from the Rockefeller Foundation to the University of California. Commercial enterprises and products are mentioned solely for information, and do not imply endorsement by the sponsoring agencies and organizations.     

Hierarchical structure in LCP/PET blends

The structural hierarchy in injection molded blends of poly(ethylene terephthalate) (PET) and a commercial liquid crystal polymer (LCP), two immiscible polymers, was characterized at various blend compositions. The macroscopic core and skin have a gradient structure and are subdivided into ordered and disordered layers. The sublayers consist of rodlike domains at 25% LCP. The domains become thinner, longer, and more fibril-like with increasing LCP concentration. The interconnection between the LCP domains also becomes more significant at higher LCP concentrations. The highest degree of orientation in the injection direction is at the mold surface and the lowest at the sample center. The LCP orientation reflects the elongational and fountain flow in the mold and increases with increasing LCP concentration. Schematic structural models were used to illustrate the levels of structure in these blends. A minimum exists in the tensile strength, elongation at break, and impact strength with varying blend composition at approximately 50% LCP. The tensile strength of the LCP-rich blends is significantly lowered by the presence of a weldline or an angle between the stress and orientation directions. The unique mechanical properties of the LCP depend on the formation of a highly oriented and highly connected hierarchical structure that does not exist in blends with 75% or less LCP.     

Polymerized high internal‐phase emulsions: Properties and interaction with water

The synthesis and characterization of novel polymerized high internal‐phase emulsions (polyHIPE) materials are described. Homogeneous, highly porous, low‐density, open‐cell crosslinked copolymers were prepared by polymerizing the continuous phase of HIPE containing styrene and varying amounts of 2‐ethylhexyl methacrylate. The glass transition temperatures (T_gs) of the homopolymers were similar to the literature values, but the copolymer T_gs were lower than expected. These results indicate that the copolymer composition is richer in 2‐ethylhexyl methacrylate than the feed composition. The homopolymer moduli, calculated from the foam moduli, were similar to the literature values. The influence of composition and surface treatment on the water absorbed by the foams was investigated. For example, washing a polyHIPE based on poly(ethylhexyl acrylate) in water at 70°C increased water absorption because of the removal of the residual salt. Adding a fluorinated comonomer to the HIPE reduced hydrophilicity and, thus, water absorption. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2018–2027, 2002; DOI 10.1002/app.10555     

Pheromonal attraction and allomonal interruption ofIps pini in California by the two enantiomers of ipsdienol

Air containing volatile compounds from around maleIps pini boring in ponderosa pine logs from California was condensed, fractionated by GC, and assayed in the laboratory and field. The only fraction that showed consistent activity in laboratory assays contained a single compound identified as ipsdienol (2-methyl-6-methylene-2,7-octadien-4-ol). Synthetic racemic ipsdienol showed no activity in either the laboratory or field. However, (–)-ipsdienol, the naturally occurring enantiomer, was attractive toI. pini in the laboratory and field, whereas (+)-ipsdienol interrupted the response ofI. pini to a natural source of attraction in field tests. (–)-Ipsdienol is a major component of the attractant pheromone of this species, since its level of activity in laboratory assays was quantitatively comparable to that of the condensed volatiles, and it was as attractive as maleI. pini boring in ponderosa pine in the field. (+)-Ipsdienol is a component of the pheromone of the competing species,I. paraconfusus.(C.B.R.I. Contribution No. 1043.)     

In-depth characterization of the hole mobility in 50-nm process-induced strained MOSFETs

This letter presents the first experimental study of the mobility in 50-nm gate length (L/sub G/) pMOSFETs highly strained by a contact etch stop layer. Thanks to an advanced characterization method, the mobility is in-depth studied versus the inversion charge density, the gate length and the temperature. The physical origin of the more than 50% mobility enhancement at L/sub G/=50 nm is proven to be the low effective mass of the top valence band rather than any scattering modification. This mobility gain is maintained even at high effective field. This explains the 30% I/sub ON/ enhancement at 50-nm gate length, which is among the best results at such a dimension.     

Influence of hydrogen on microstructure and dynamic strength of lean duplex stainless steel

In this research dynamic strength is analyzed for the first time in a lean duplex stainless steel (LDS) uncharged and charged with hydrogen. In particular, the dynamic yield stress (Hugoniot elastic limit, HEL) and the dynamic tensile strength (spall strength) of LDS are studied. We also investigate the deformation mechanism of the LDS using metallurgical analysis. LDS was chosen since it has a mixed structure of ferrite (BCC, α) and austenite (FCC, γ), which allows an attractive combination of high strength and ductility. The dynamic loading was produced by accelerating an LDS impactor in a gas gun into an LDS target (uniaxial plate impact experiments). Data collection was performed by optical diagnostics through the velocity interferometer for any reflector device. The impact produces conditions of high pressure and high strain rate (~10⁵ s^?1), which can be comparable to explosions during extreme conditions of failure. In addition, investigations of hydrogen interaction with both crystal lattices were performed by means of X-ray diffraction (XRD) measurements. Several assessments can be made based on the results of this study. Using XRD analysis, it will be shown that even after hydrogen desorption some hydrogen remained trapped in the austenitic phase causing a small lattice expansion. After impact, a brittle spall was seen, which occurred through cavitation of cracks along both phases’ grain boundaries. Hydrogen increases the dynamic yield strength and when hydrogen content is sufficiently high it will also lead to higher spall strength. The relation between microstructure and dynamic strength of the LDS in the presence of hydrogen is discussed in detail.     

Neuronal nitric-oxide synthase is regulated by the Hsp90-based chaperone system in vivo

It is established that the multiprotein heat shock protein 90 (hsp90)-based chaperone system acts on the ligand binding domain of the glucocorticoid receptor (GR) to form a GR.hsp90 heterocomplex and to convert the receptor ligand binding domain to the steroid-binding state. Treatment of cells with the hsp90 inhibitor geldanamycin inactivates steroid binding activity and increases the rate of GR turnover. We show here that a portion of neuronal nitric-oxide synthase (nNOS) exists as a molybdate-stabilized nNOS. hsp90 heterocomplex in the cytosolic fraction of human embryonic kidney 293 cells stably transfected with rat nNOS. Treatment of human embryonic kidney 293 cells with geldanamycin both decreases nNOS catalytic activity and increases the rate of nNOS turnover. Similarly, geldanamycin treatment of nNOS-expressing Sf9 cells partially inhibits nNOS activation by exogenous heme. Like the GR, purified heme-free apo-nNOS is activated by the DE52-retained fraction of rabbit reticulocyte lysate, which also assembles nNOS. hsp90 heterocomplexes. However, in contrast to the GR, heterocomplex assembly with hsp90 is not required for increased heme binding and nNOS activation in this cell-free system. We propose that, in vivo, where access by free heme is limited, the complete hsp90-based chaperone machinery is required for sustained opening of the heme binding cleft and nNOS activation, but in the heme-containing cell-free nNOS-activating system transient opening of the heme binding cleft without hsp90 is sufficient to facilitate heme binding.     

Perceiving color across scale: great and small, discrete and continuous

We generalize, to images with continuously varying colors, our previously published model for comparing color differences of spatially discrete visual fields (icons, symbols) of disparate sizes. Our model is structural, including scattering of light by the intraocular media, followed by sparse retinal cone cell sampling of each physiological color primary. We use our model to show that small subtense of less than half a degree drastically reduces the number of discriminable colors available within a color gamut. The proposed generalization predicts and explains appearance of color fields having a wide range of subtenses (from 1/8 deg to 44 deg in examples given).