Reexamination of the Female Sex Pheromone of the Sweet Potato Vine Borer Moth: Identification and Field Evaluation of a Tricosatriene

The sweet potato vine borer moth, Omphisa anastomosalis (Pyraloidea: Crambidae), is a serious pest in tropical and subtropical Asia-Pacific regions. In previous work using a population from Okinawa, Japan, (10E,14E)-10,14-hexadecadienal (E10,E14-16:Ald) was identified as the major pheromone component, with hexadecanal, (E)-10-hexadecenal, and (E)-14-hexadecenal as minor components. However, traps baited with the synthetic compounds were less effective at attracting males in the field than those baited with virgin females. While Pyraloidea females usually produce only Type I pheromone components (unsaturated fatty alcohols and their derivatives), the pheromones of some Pyraloidea species have been shown to involve a combination of both Type I and Type II components (unsaturated hydrocarbons and their epoxides). We examined an extract of the pheromone glands of female O. anastomosalis from Vietnam by gas chromatography coupled to mass spectrometry and detected (3Z,6Z,9Z)-3,6,9-tricosatriene (Z3,Z6,Z9-23:H) in addition to the compounds identified previously. All four isomers of 10,14–16:Ald were synthesized. A mixture of synthetic E10,E14-16:Ald and Z3,Z6,Z9-23:H in a ratio of 1:0.2–1:2 was attractive to male moths in Vietnam, indicating the strong synergistic effect of the Type II compound. Addition of the other minor pheromone components to the binary blend did not increase the number of male moths captured. Combinations of Z3,Z6,Z9-23:H with the other three geometrical isomers of E10,E14-16:Ald attracted no males, further substantiating the 10E,14E configuration of the natural diene component. E10,E14-16:Ald mixed with other polyunsaturated hydrocarbons showed that mixtures that included a C₂₁ triene, a C₂₂ triene, or a C₂₃ pentaene attracted as many males as did the mixture with Z3,Z6,Z9-23:H. The identification of a highly attractive sex pheromone will help in developing efficient strategies for monitoring and control of O. anastomosalis populations in sweet potato fields.     

用纳滤膜分离混合无机电解质溶液的性能评价方法

提出一个新的混合无机电解质溶液的纳滤膜分离性能的评价方法。该评价方法将纳滤膜分离性能表述为某种离子在膜中的透过率,其值与混合电解质总浓度、各种离子的当量分数和同号离子之间通过纳滤膜的竞争作用有关。首先根据一些双组分无机电解质溶液的纳滤膜分离实验获得离子的竞争系数,然后采用几种不同组成不同浓度的混合电解质溶液（NaCl和NaF;NaCl和KCl;NaF、NaCl和NaNO3;NaCl、NaNO3和Na2SO4;NaF、NaCl、NaNO3和Na2SO4）通过ESNA 1膜的透过实验验证该评价方法的适用性。结果表明混合电解质溶液总浓度和离子的当量分数是影响各种离子通过纳滤膜的表观透过率的主要因素,评价方法预测值与实验数据相符合。说明该方法适用于评价含有单价阳离子的混合无机电解质溶液的纳滤膜分离性能。     

Synthesis and Characterization of 2,13- and 3,13-Octadecadienals for the Identification of the Sex Pheromone Secreted by a Clearwing Moth

In addition to 2,13- and 3,13-octadecadien-1-ols and their acetates, aldehyde analogs have been identified from lepidopteran species in the family Sesiidae. To establish a reliable analytical method for determining the positions and configurations of the two double bonds in natural pheromone components, all geometric isomers of the 2,13- and 3,13-octadecadienals were synthesized by Dess-Martin oxidation of the corresponding alcohols with limited isomerization of the double bond at the 2- or 3-position. GC-MS analysis of these aldehydes showed isomerization of (Z)-2-, (Z)-3-, and (E)-3-double bonds to an (E)-2-double bond, even with a cool on-column injection. In contrast, HPLC analysis with an ODS column was accomplished without isomerization. The geometric isomers of each dienal eluted in the order ZZ → EZ → ZE → EE. The conjugated 2,13-dienals were detectable in nanogram amounts with a UV detector at 235 nm. Whereas the detection of 3,13-dienals was difficult because of the lack of a chromophore, a highly sensitive analysis was achieved after derivatization with 2,4-dinitrophenylhydrazine. LC-MS with atmospheric pressure chemical ionization showed a strong [M-1]^- at m/z 443 for the derivatives. Based on these analytical data, a pheromone extract of a sesiid moth, Macroscelesia japona, was examined by HPLC and LC-MS, and it was confirmed that the octadecadienal tentatively identified by a previous GC-MS analysis did indeed have the 2E,13Z configuration. Furthermore, field evaluation of four synthetic geometric isomers of the 2,13-dienal revealed specific attraction to a lure with the (2E,13Z)-isomer as a main component.     

Theoretical consideration of the effect of porosity on thermal conductivity of porous materials

The thermal conductivity of porous materials is theoretically studied in connection with nanoporous materials used in recent semiconductor devices. The effects of porosity and pore size on the thermal conductivity are discussed. The thermal conductivity of insulating materials is determined by the heat capacity of phonons, the average phonon velocity and the phonon mean free path. We investigate the porosity dependence of these quantities, especially by taking into account phonon scatterings by pores, and present an expression for the thermal conductivity as a function of porosity. Our model consideration predicts that the thermal conductivity of nanoporous materials depends on the ratio of the pore size R _p to the phonon mean free path for zero-porosity, l ₀. The thermal conductivity for l ₀/R _p > 1 decreases steeply with increasing porosity because of effective phonon scatterings by pores. On the other hand, the thermal conductivity for l ₀/R _p < 0.1 decreases moderately with increasing porosity because phonon scatterings by pores are no longer effective. On the basis of the present theoretical consideration, we discuss the principal factor dominating the porosity dependence of thermal conductivity in nanoporous materials. We also discuss how one can design nanoporous materials with lower or higher thermal conductivity.     

GAS-LIQUID MASS TRANSFER CHARACTERISTICS OF LARGE-SCALE IMPELLERS: EMPIRICAL CORRELATIONS OF GAS HOLDUPS AND VOLUMETRIC MASS TRANSFER COEFFICIENTS IN STIRRED TANKS

Gas dispersion with large-scale impellers consisting of modified large paddle impellers in stirred tanks, with rather large ratios of both impeller diameter and impeller height to tank diameter, was experimentally examined in transition and turbulent mixing ranges. Gas holdups and volumetric gas-liquid mass transfer coefficients with large-scale impellers, i.e., Maxblend and Fullzone impellers, were measured in 0.31 and 0.6 m I.D. stirred tanks, and the gas dispersion performance of large-scale impellers was compared with that of double conventional small-scale high-speed impeller systems, i.e., double four-flat blade disk turbine impellers and double four-flat paddle impellers.

The gas holdups of the large-scale impellers were comparable with those of the small-scale impeller systems at a given rotational speed. The volumetric gas-liquid mass transfer coefficients for large-scale impellers were also similar to those of the small-scale impeller systems. It was found that the large-scale impellers are not more energy efficient than the small-scale impellers in obtaining good gas dispersion.

Empirical correlations for gas holdups and volumetric gas-liquid mass transfer coefficients were developed. They fit the experimental data in transition and turbulent mixing ranges reasonably well, with correlation factors greater than 0.84.     

超声波共振度对铸锭内气孔生成的影响

为了弄清超声波对金属熔体除气的影响,研究了超声波共振度对Al-1．0%Cu、Al-1．0％Si及Al-1．0％Zn合金铸锭内气孔生成的影响,同时也考察了超声波共振度对铝合金铸锭细化的影响,分析了超声波共振度时铸锭内气孔生成的影响原因。结果表明,超声波处于共振状态下的铸锭密度值和细化效果均远大于非共振状态下的铸锭密度值和细化效果;超声处理过程中,声空化气泡的“表面效应”和“层效应”起着决定作用;超声波的细化作用来自于声空化气泡的膨胀和收缩期间而形成的高温、高压的反应场,因而刺激熔体内的动态形核。     

Controlled growth and shape formation of platinum nanoparticles and their electrochemical properties

Cubic Pt nanoparticles were prepared from a solution of K₂PtCl₄ containing sodium polyacrylate as a capping reagent. The effects of the Pt/polymer molar ratio, the average molecular weight (M_w) of the polymer, and reaction temperature on the shape and size were investigated. When the polymer of M_w = 5100 was added at a molar ratio of Pt/polymer = 1/12, cubic platinum nanoparticles of an average size of 10.3 nm were predominantly formed (ca. 50% in number) at 25 °C. The electron diffraction pattern of the cubic nanoparticles revealed that they are single crystals with Pt {1 0 0} faces on the surface.The cubic nanoparticles were electrochemically active, and showed strong features of Pt {1 0 0} faces on cyclic voltammogram under argon atmosphere. After repeated potential cycling in the range 0.05-1.4 V, the features of Pt {1 0 0} were gradually lost, and changed to those of polycrystalline Pt. Rotating ring disk electrode measurements in O₂-saturated H₂SO₄ solution revealed that the cubic nanoparticles had a high catalytic activity for oxygen reduction reaction (ORR). After polycrystallization by repeated potential cycling, the activity for ORR and hydrogen peroxide formation decreased slightly, which were attributed to the surface structural change from Pt {1 0 0} to polycrystalline.     

Using FIB-processed AFM cantilevers to determine microtribology characteristics

Microtribology characteristics were determined by using a combination of single asperities and three types of FIB (focused ion beam)-processed cantilevers for AFM (atomic force microscope). First, single gold asperities were rubbed with single and parallel leaf springs. For the parallel leaf spring, the pull-off force was proportional to the worn area of the gold asperity peak. The total volume of the gold asperity only slightly changed with rubbing. Second, the friction force on a worn asperity was measured by using a double parallel leaf spring, and the results showed that the friction force was proportional to the sum of the normal load and the pull-off force.     

A DSP line equalizer VLSI for TCM digital subscriber-linetransmission

The architecture of a line equalizer using digital-signal-processing (DSP) techniques is described. The equalizer is utilized in 320-kb/s time-compression multiplexing (TCM) subscriber-line transmission systems in the integrated services digital network (ISDN). It consists of two digital filter blocks, called the √f equalizer and the bridged-tap equalizer, and gain- and timing-control blocks. The √f equalizer achieves the processing speed of 20 MOPS by a powerful arithmetic unit composed of multipliers and adders. It provides an FIR filter with nine taps which satisfies an accurate equalization for the 1.92-Msample/s data. The bridged-tap equalizer performs both the adaptation algorithm of the √f equalizer and the decision-feedback algorithm. The microprogram control enables the hardware to be shared between these functions and assures flexibility. Algorithm-oriented instructions implemented in the ALU realize high-speed execution of the decision-feedback algorithm with a simple architecture. The 11.3-mm×8.5-mm chip with 61 K transistors has been implemented using 1.5-μm double-metal-layer CMOS technology     

Characteristics in InGaAs/InP avalanche photodiodes with separated absorption and multiplication regions

Improved characteristics of compound semiconductor avalanche photodiodes with separated absorption and multiplication regions (SAM) are discussed. Temperature dependences of dark current and breakdown voltage show that the tunneling current in the narrow energy gap layer can be suppressed in InGaAs/InP APD's with the SAM structure. Dark currents above punch-through voltages, at which the depletion layer reaches the InP-InGaAs heterointerface, are caused by the generation-recombination process in the InGaAs and at the heterointerface. Dark currents near breakdown depend on the n-layer thickness and are strongly affected by the electric field strength in the ternary layer. Tunneling currents are dominant in diodes with thin n-InP layers, while the generation-recombination processes in the InGaAs layers are dominant in those with a thick n-InP layer. The dark current was as low as7.8 times 10^{4}A/cm²atM = 10when the interface electric field strength is reduced. A maximum multiplication factor of 60 was observed for the6 times 10^{-7}A initial photocurrent. Rise time and full width at half maximum in a pulse response waveform were 100 and 136 ps, respectively, atM = 10.