Alpha-acaridial a female sex pheromone from an alarm pheromone emilting mite Rhizoglyphus robini

The female sex pheromone of Rhizoglyphus robini Claparède (Astigmata: Acaridae) was identified as -acaridial [2(E)-(4-methyl-3-pentenyl)- butenedial], which stimulated males sexually and enhanced the frequency of male mounting behavior. Although a hexane extract of females manifested alarm pheromone activity against tested males due to the presence of the alarm pheromone neryl formate, silica gel column fractions containing -acaridial evoked increased mounting behavior by males at a dose of 0.1 female equivalent. Synthetic -acaridial at a dose of 10 ng showed a peak of activity as a sex pheromone, with a convex dose–response relationship. Its content was determined to be 388 ± 244 ng per female and 163 ± 97 ng per male by GC. This is the first time that two pheromones (the alarm pheromone neryl formate, and the sex pheromone -acaridial) have been demonstrated to be components of the same opisthonotal gland secretion in astigmatid mites. A mechanism for the appropriate expression of the two pheromones by the mites under different conditions is proposed.     

Effect of alloying element content on ion-nitriding behavior of Fe-Ti alloys

The ion-nitriding behavior of iron alloys with a titanium content of between 1.07 and 2.58 wt.% was investigated in the -phase region. The behavior was found to be analogous to the internal oxidation behavior of iron alloys: An internal-nitriding layer, where small TiN precipitates are dispersed, as well as a very thin surface layer of -Fe₄N were formed. A parabolic rate law holds for growth of the internal-nitriding layer. The kinetics of growth of the internalnitriding layer is discussed according to the rate equation of internal-oxidation, giving the diffusion coefficient of nitrogen, D _N ^app , in the layer. The measured D _N ^app decreases as the volume fraction of TiN, f, increases, indicating that the diffusion of nitrogen is apparently inhibited by the existence of TiN precipitates. Furthermore, the diffusion coefficient of nitrogen in -iron was evaluated by extrapolating D _N ^app to f=0, being in good agreement with that reported previously. The f-dependence of D _N ^app is discussed in terms of the effective area for diffusion of nitrogen in -iron.     

Numerical simulation of unsteady viscous flow around a circular cylinder

A finite difference solution is obtained for the time-dependent viscous incompressible 2-dimensional flow past a circular cylinder by direct integration of the Navier-Stokes equations expressed in a general curvilinear coordinate system. The solution describes the development of the vortex street developed behind the cylinder. Evolution of flow configuration is studied by means of streamlines, pressure contours, and vorticity contours for different Reynolds numbers. The time-dependent lift and drag coefficients are also obtained.     

The Photonic Technologies Impact on the Next Generation Network

This paper describes the possible impact of photonic technologies on the next-generation network. With the explosion of the Internet (IP), the capacity demand is increasing exponentially, which exceeds Moor's law. The next-generation IP network should sustain this increase. This paper shows the possible node processing bottleneck even the transmission capacity can be supported by the use of WDM technology. Based on this analysis, the paper proposes a virtual router network as a solution, which applies a logical full-mesh connection based on salient features of photonic network technology. Development of the WDM technology sets the target at 1000 wavelengths on a fiber so that a dynamic wavelength routing function is becoming available. The increase in wavelengths, transparency among wavelengths, and the wavelength routing function can provide an optical path, which forms the base of a logical full-mesh structure and also provides an easy migration scenario from the current network to the next-generation IP network. The possibility is examined by calculation using a bi-directionalloop network as an example. As the foundation of the proposal, the current statusof photonic network technologies is described with future projection.     

Parasitic Wasp, Dinarmus basalis, Utilizes Oviposition-marking Pheromone of Host Azuki Bean Weevils As Host-Recognizing Kairomone

A host-recognizing kairomone responsible for the stinging behavior of the parasitic wasp, Dinarmus basalis, was studied. Fresh azuki beans coated with an acetone extract of the azuki beans, from which both emerged wasps and their host weevils were removed, elicited stinging behavior from female wasps. The kairomone is a mixture of saturated hydrocarbons and diacylglycerols, both of which are required for activity. The kairomone is composed of normal and methyl-branched hydrocarbons with carbon numbers ranging from 25 to 35, most of which are known as the hydrocarbon constituents of an oviposition-marking pheromone of the host azuki bean weevils, Callosobruchus chinensis. This indicates that D. basalis utilizes the oviposition-marking pheromone of its host weevils as a host-recognizing kairomone.     

On-site measurement of trace-level sulfide in natural waters by vapor generation and microchannel collection

Aqueous sulfide plays an important role in the environment even at low concentrations. However, it is unstable, which means field samples cannot be transported to the laboratory for analysis without fixation. In this work, a novel method was developed to determine trace levels of sulfide on site. This method is based on vapor generation and collection in a special microchannel device followed by fluorescence measurement (VG-μGAS). The microchannel scrubber gave a high enrichment factor, and a high sensitivity was achieved, which allowed measurement of nanomolar (nM) levels of sulfide. The theoretical approach to vapor generation for several compounds is discussed to evaluate the applicability of the method to these analytes, and compounds having a low Henry's law constant (<1 M atm(-1)) are suitable to measure by VG-μGAS. Under optimized conditions, concentrations of 1.0-100 nM of sulfide could be measured. The sulfide contents of hot spring, aquarium, pond, and seawater were successfully measured by this method. Nanomolar levels of sulfide could be measured on site without loss of analyte, and results were obtained instantly in the field, both of which are advantageous for effective field surveys. The method was also applied to field measurements of aqueous sulfide in the Ariake Sea and Lake Baikal.     

Charge-carrier injection into pentacene thin film formed on Si(111) probed by STM spectroscopy

The injection of charge carriers into a pentacene thin film formed on a Si substrate was investigated by scanning tunneling microscopy (STM). Tip height versus bias voltage (z-V) spectroscopy reveals the characteristic charge transport properties of the molecular film, i.e., the conductivity and the threshold energy of charge injection. The abrupt descent of the tip into the film owing to the transition of film conductance, which depends on the degree of charge carrier injection, was observed for crystallized pentacene thin films. The lower film conductance at around zero bias voltage is still higher than that of a vacuum. This indicates that the carrier injection barrier between the pentacene and the semiconducting substrate is extremely low. The convergence of the carrier injection endpoints into a narrow range of electric-field intensity implies that the main factor contributing to barrier formation and collapse is not the bias voltage but the electric field.     

Nanoscale control of reversible chemical reaction between fullerene C60 molecules using scanning tunneling microscope

The nanoscale control of reversible chemical reactions, the polymerization and depolymerization between C60 molecules, has been investigated. Using a scanning tunneling microscope (STM), the polymerization and depolymerization can be controlled at designated positions in ultrathin films of C60 molecules. One of the two chemical reactions can be selectively induced by controlling the sample bias voltage (V(s)); the application of negative and positive values of V(s) results in polymerization and depolymerization, respectively. The selectivity between the two chemical reactions becomes extremely high when the thickness of the C60 film increases to more than three molecular layers. We conclude that STM-induced negative and positive electrostatic ionization are responsible for the control of the polymerization and depolymerization, respectively.