Effects of substituted aromatic heterocyclic phosphate salts on properties,crystallization, and melting behaviors of isotactic polypropylene

Nucleation effects of 2,2′‐methylene‐bis (4,6‐di‐tert‐butylphenyl) phosphate metal salts as a nucleating agent for isotactic polypropylene (iPP) were investigated with differential scanning calorimeter and polarized optical microscope, and their effects on mechanical, optical, and heat resistance properties of iPP were also studied. The results showed that monovalent metal salts of substituted aromatic heterocyclic phosphate such as sodium salt, lithium salt, and potassium salt had a good performance. With 0.2 wt % of sodium salt, lithium salt, or potassium salt incorporated into iPP, the crystallization peak temperature of iPP could be increased by 13.5, 13.6, and 15.0°C, respectively; the mass fraction of crystallinity of iPP could be increased by about 5%; and crystallization rate was enhanced increasingly. Meanwhile the tensile strength and flexural modulus of iPP could be increased by about 10 and 30%, respectively, and the clarity and heat distortion temperature of iPP could also be improved significantly. But bivalent and trivalent metal salts of substituted aromatic heterocyclic phosphate had little effect on properties of iPP. Meanwhile the morphology study showed that the addition of monovalent sodium salt could decrease the spherulite size of iPP significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4868–4874, 2006     

Different feeding and gustatory responses to ecdysone and 20-hydroxyecdysone by larvae of the silkworm,Bombyx mori

The feeding and gustatory responses to ecdysone and 20-hydroxyecdysone were investigated in the silkworm,Bombyx mori. 20-Hydroxyecdysone reduced feeding response strongly in fourth- and fifth-instar larvae, whereas ecdysone had no effect on feeding response. 20-Hydroxyecdysone stimulated the R receptor, the receptor to feeding deterrents, to a great degree. By contrast, ecdysone was much less effective for stimulating the R receptor. These results indicate that ecdysone and 20-hydroxyecdysone have different effects on feeding response due to different interactions with mouthpart chemoreceptors.     

Insect antifeedant activity associated with compounds isolated from species ofLonchocarpus andTephrosia

The antifeedant activity of a series of 21 chalcones, flavanes, and flavanones isolated from the generaLonchocarpus andTephrosia (Leguminosae) was assessed by behavioral and electrophysiological bioassays against larvae ofSpodoptera littoralis andS. exempta. The antifeedant activity is related to the molecular structure of the compounds, and possible modes of interaction with the insect taste receptors are discussed.     

Spinose carbon nanotubes grown on graphitized DLC film by low frequency r.f. plasma-enhanced chemical vapor deposition

Spinose carbon nanotubes (SCNTs) are grown on silicon substrates covered with diamond-like carbon film and iron catalyst film (Fe/DLC/Si structure) by low frequency r.f. plasma-enhanced chemical vapor deposition (LFRF-PECVD). During the pre-treatment of the Fe/DLC/Si substrate, there are three processes happened, namely, iron film spalled to small islands, the DLC film graphitized, and the iron island reacted partially with the graphitized DLC (GDLC), which can be deduced from the Raman spectroscopy and SEM pictures. SCNTs film grew from C₂H₂---H₂ mixture under low plasma density. The good contact of carbon nanotube with GDLC film was acquired by the accumulation of the graphite sheets and the reaction between the iron particles and GDLC film. The homogeneous spines with the length of approximately 15 nm and the thickness of <5 nm burgeoned from the defects at the wall of carbon nanotube and distributed uniformly, which were in fact thin bent or rolled-up graphite sheets.     

0.91Pb(Zn1/3Nb2/3)O3-0.09PbTiO3的析晶行为及助溶剂法生长

研究了0.91Pb(znl/3Nb2/3)O3-0.09PbTiO3(PZNT91/9,摩尔分数)在不同组分和配比熔盐中的析晶行为及其对晶体生长的影响。发现B2O3,PbF2等助溶剂不利于钙钛矿相的析出;而BaTiO3-PbO复合体系虽然能够促进钙钛矿相析出,但晶体析出量很少;只有适当比例的。PbO助溶剂比较适合于生长具有铁电性的钙钛矿相PZNT91/9单晶。助溶剂法生长的工艺参数为:溶质与PbO助溶剂的摩尔比为l:l,泡料温度1 150-1 200℃,泡料时间10 h,晶体生长时降温速度0.8-2℃/h,当温度降到900℃时停止生长,以50℃/h快速冷却至室温。所得晶体为琥珀色,最大尺寸达φ30 mm×15 mm,其压电系数和机电偶合系数分别为2000 pc/N和0.92。     

Binary phase behavior of 1,3-distearoyl-2-oleoyl-sn-glycerol (SOS) and 1,3-distearoyl-2-linoleoyl-sn-glycerol (SLS)

The binary phase behavior of SOS (1,3-distearoyl-2-oleoyl-sn-glycerol) and SLS (1,3-distearoyl-2-linoleoyl-sn-glycerol) was examined by using DSC and conventional and synchrotron radiation X-ray diffraction. The solid-solution phases were observed in the metastable α and γ forms in all concentration ranges. Results indicated that the miscible γ form did not transform to the β′ form when the mixtures were subjected to simple cooling from a high-temperature liquid to a low-temperature solid phase. However, and α-melt-mediated transformation into β′ and β₂ resulted in the formation of immiscible phases in concentration ranges of SLS below 30%. By contrast, at SLS concentration ranges above 30%, the α-melt-mediated transformation caused crystallization of only the γ form, and β′ and β₂ crystals did not appear. These results show that the specific interactions between SOS and SLS are operative in the phase behavior of the mixture states of SOS and SLS.     

Host odor and visual stimulus interaction during intratree host finding behavior ofRhagoletis pomonella flies

Responses ofRhagoletis pomonella (Walsh) (Diptera: Tephritidae) flies to host fruit visual stimuli (apples or models of apples) and chemical stimuli (synthetic apple volatile blend) were studied in semidwarf field-caged apple trees. Three different fruit or model densities (1, 4, or 16 fruit or models/ tree) and two odor release rates [ca. 0.7g/hr (close to the natural release rate of a ripe apple) and ca. 500g/hr (amount of odor released by commercially sold apple maggot traps)] were tested. Individually released flies were followed as they moved within a tree for a maximum of 20 min. We recorded three-dimensional search paths followed by foraging flies and computed such variables as total relative distance traveled before alighting on a fruit or model, track length between individual alightment sites, and directness of flight to fruits or models. Effect of odor on propensity to alight on fruit or models and host-searching behavior prior to alighting on fruit or on models varied according to fruit or model color and density. If the fruit visual stimulus was strong (e.g., red color), odor did not increase the probability of finding fruit or fruit models. As the visual stimulus became progressively weaker (red to green to clear), odor (irrespective of concentration) appeared to aid flies during the fruit-finding process. As density of fruit or models increased, the probability of flies finding a fruit or model also increased (e.g., 50% of flies found a red fruit model at 1 model/tree while 90% found a red model at 16 models/tree; 4% of flies found a clear model with odor at 1 model/tree while 35% found a clear model with odor at 16 models/tree). Findings reported elsewhere indicate thatR. pomonella flies are able to discover a point source of odor (an odor-bearing tree in a patch of trees) by flying upwind (in the tree patch) in response to intermittent exposure to odor. Findings here indicate that after arrival on a host tree (point source), flies discover individual apparent and abundant host fruit on the basis of vision. If fruit are less apparent or scarce, odor appears to interact with vision during the fruit-finding process.     

Effect of miscibility and forced compatibility on damping properties of CIIR/PAc blend

In this study, a kind of novel damping materials was prepared based on the blend of chlorinated butyl rubber (CIIR) and polyacrylate (PAc) synthesized by different molar ratio of butyl methacrylate and ethyl acrylate. Research results from experiments and analyses by employing DMA, TEM, and FTIR show that whether at a cocured system or noncocured system, it can be achieved to shift a loss peak of CIIR towards a higher temperature region and to keep the damping value from markedlly decreasing, which broadens the effective damping function area of CIIR to the vicinity of ambient temperature. In the former system, the thermodynamical miscibility of CIIR and PAc, to some extent, is predominated by the molecular design of PAc, while in the latter system, covulcanized networks play a more significant role in improving compatibility and abating the peak split, though the suppression effect of thermal stress on the transition of CIIR T_ll transition still can not be neglected. Furthermore, transition state derived from the cocuring CIIR and PAc cannot make the phase separation completely take place, and consequently results in the deformation of phase morphology of the cocured CIIR/PAc blend. It is the influence of thermodynamics miscibility and forced compatibility in different size that makes the suppression effect of foreign PAc on CIIR T_ll transition be controllable. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3127–3133, 2006     

An adaptive single-point algorithm for global numerical optimization

This paper describes a novel algorithm for numerical optimization, called Simple Adaptive Climbing (SAC). SAC is a simple efficient single-point approach that does not require a careful fine-tunning of its two parameters. SAC algorithm shares many similarities with local optimization heuristics, such as random walk, gradient descent, and hill-climbing. SAC has a restarting mechanism, and a powerful adaptive mutation process that resembles the one used in Differential Evolution. The algorithms SAC is capable of performing global unconstrained optimization efficiently in high dimensional test functions. This paper shows results on 15 well-known unconstrained problems. Test results confirm that SAC is competitive against state-of-the-art approaches such as micro-Particle Swarm Optimization, CMA-ES or Simple Adaptive Differential Evolution.     

The factors of speeds and loads on the tribological properties of PVA‐H/HA composites

Poly (vinyl alcohol) (PVA)/Hydroxy apatite (HA) composite prepared from aqueous solution of the polymer and dimethylsulfoxide (DMSO) by freezing and thawing method are developing to repair or replace articular cartilage. In the present study, the tribological behaviors of this composite were investigated in a three‐factor, three‐level designed experiment using an improved four‐ball tester. Factors include sliding velocity, applied load, and HA content of composite. Friction coefficient of the PVA‐H/HA was found to depend significantly on load and sliding velocity, while HA content had small effects on the friction coefficient of PVA‐HA composite. We also found that wear loss of PVA‐H/HA increased sharply with the increasing loads and HA content of specimen. Increased HA content from 0.5% to 1.5% resulted in an increasing of 355% in wear loss, while increasing sliding velocity slightly decreases wear loss of specimen. We also found some correlation between friction coefficient and wear loss of specimen under the given condition. These results may be useful in the tribological design of PVA‐H/HA composite for both low wear and low friction using as artificial cartilage substitutes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007