Methodological approach to identify chemical oviposition stimulants from maize for European corn borer

The noncontingent distribution ofO. nubilalis Hbn. eggs on various corn varieties has allowed their classification as either favorable or nonfavorable hybrids. This classification is based on a chemical communication system using volatile compounds active at a distance from the insect or active when in contact with the insect as soluble sugar components. Under this hypothesis, gas chromatography is the best way of investigating for the chemical differences between corn silk extracts from the two types of hybrids. A first experiment, using a desorption-trapping system on Tenax coupled to a gas chromatograph showed a quantitative difference between two compounds from the two hybrids. A second experiment showed the advantages and disadvantages of this method and allowed the development of two complementary techniques: (1) direct extraction of corn silk with trichlorofluo-romethane and direct injection into a capillary column with an apolar stationary phase using an on-column system; and (2) extraction under vacuum of volatile compounds from corn silk and their trapping on Tenax, followed by a second desorption. This allows a direct injection on the same capillary column. The first technique allows identification by mass spectrometry of many alkanes with high molecular weights. The second technique seems to confirm the presence of phenylacetaldehyde. Both techniques show quantitative differences in the composition of corn silk extracts from favorable and nonfavorable hybrids; however, the biologically active chemicals remain unknown.     

Specific features of the phase transformations occurring during the sintering process of the beta-alumina based ceramics and their properties

Conclusions During the sintering process of beta-alumina obtained using the method of plasmochemical synthesis, the structural transformation occurs and it is accompanied by the separation of the excess Na₂O and the formation of an intergranular meltlike phase that is saturated with sodium and is characterized by high dielectric properties.The quantity of the meltlike phase and the magnitude of the /( + ) ratio determine the degree of stabilization (stability) and the final resistivity of the material and depend on the initial chemical composition and the heating rate maintained during the sintering process.It was shown that when the duration of residence of the material in the hot zone of the furnace is increased or when the specimens sintered maintaining high heating rates are subjected to additional heat treatment, one observes the occurrance of the reverse structural transformation that is characterized by an increase of the phase ratio /( + ) 1, a reduction in the quantity of the meltlike phase right up to its complete disappearance, and a decrease of the electrical resistivity of the material.In the materials having a large excess quantity of sodium oxide, the process of crystallization of the intergranular NaAlO₂ phase occurs simultaneously with the second phase transformation.The best ceramic and electrophysical parameters were obtained when sintering the material contained 7.9% Na₂O.Translated from Ogneupory, No. 3, pp. 13–18, March, 1990.     

Field test of the pheromone hypothesis for homing by pacific salmon

Experimental groups of juvenile coho salmon (Oncorhynchus kisutch) were released to elucidate the relative importance of site-specific (imprinted) odors and intraspecific odors (pheromones) in homing. Adult salmon returned to their release site rather than a hatchery containing both adult and juvenile salmon of their population. Furthermore, salmon sharing the same parents returned to different sites, suggesting that local movements are not strongly influenced by siblings or other conspecifics.     

Electrochemical behaviour of viologen-cyclodextrin inclusion complexes. The case of non-alkyl group substituted viologen

The electrochemical behavior of non-alkyl substituted viologen, 4,4-dibenzyl bipyridinium (BzV), 4,4-dicyanophenyl bipyridinium (CyV) and -,-,-cyclodextrin (, , -CD) was studied using cyclic voltammetry and a spectroelectrochemical method. It was found that BzV and Fe(CN) ₆ ^4– formed a charge-transfer (CT) complex with a ratio of 21 and the colour of the solution faded with the addition of an electrolyte. This behaviour is the same as in then-heptyl viologen and ferrocyanide system [1]. BzV, -CD and -CD formed an inclusion complex only in the reduced state, whilst BzV and -CD formed an inclusion complex in both the oxidized and the reduced state. An EC scheme in which a chemical reaction follows an electrochemical reaction was considered to predominate in the BzV and -, -CD systems, while a CE scheme in which a chemical reaction preceded an electrochemical reaction predominated in the BzV and -CD system. On the other hand, CyV was found to form an inclusion complex with -, -, -CD in both the oxidized and the reduced states. therefore a CE scheme was considered to predominate in the CyV--, -, -CD systems.     

Sugars in Mediterranean Floral Nectars: An Ecological and Evolutionary Approach

High-pressure liquid chromatography analyses of 73 plant species showed that the nectars of phrygana (East Mediterranean garrigue) mainly contain sucrose, glucose, and fructose, and traces of 10 minor sugars. Although the sucrose/hexose ratio was not related to plant life habit, ecological constraints had a detectable effect in shaping sugar composition. This was detected by distinguishing the phryganic plant species into spring–summer and winter flowering, with the distinction made on the basis of the water deficit in the study area. Plants flowering in spring–summer had a higher rate of high sucrose (i.e., sucrose/hexose ratio 0.5; 60.8% of the plant species) vs. low hexose nectars (i.e., ratio <0.5; 39.2%). The ratio was reversed in winter flowering species (36.4% vs. 63.6% with high sucrose and high hexose, respectively). Sucrose/hexose ratios were associated with plant family. The highest values were those of Lamiaceae, which differed significantly from the low sucrose Liliaceae and Apiaceae. Based on recorded plant–pollinator interactions in the community, the present data provide evidence of a partitioning of nectar resources by the existing pollinator guilds within the community, based on the sugar profiles of nectar (all sucrose/hexose ratios for all interactions). Among all major groups, bees and wasps (aculeates) preferred high sucrose nectars, which differed significantly from syrphids, anthomyid a.o. flies, and beetles that visited low sucrose nectars. Similarly, butterflies visited lower sucrose nectars compared to bees. Within families, only Megachilidae could be clearly characterized as high sucrose consumers, differing in this respect from all the remaining insect groups including most other bee families. This confirms previous findings that Megachilidae have a key position in Mediterranean communities where they probably constitute a selective factor for high sucrose nectars.     

On the preparation and properties of CuZSM-5 catalysts for NO decomposition

Equilibrium exchange isotherms were determined for the exchange of Cu²⁺ with NaZSM-5 at varying Cu(Ac)₂ concentrations in solutions of constant volume and zeolite weight. At low Cu²⁺ levels the solid scavenged all the copper ions. When copper could be detected in the equilibrated solutions, overexchange was observed. The extent of overexchange was higher at pH 6 than at pH 4. These results were analyzed in relation to catalytic activity.On leave from the Central Institute for Chemistry, Hungarian Academy of Sciences, H1525 Budapest, Hungary.     

Prediction of Reverse Relaxation and Deformation—Recovery Processes in Synthetic Fibres

Use of force and geometric deformation variants of the nonlinear-hereditary viscoelasticity equation for prediction of complex processes by calculation is examined on the example of deformation-recovery and reverse relaxation processes in Lavsan synthetic fibres. A comparison of the calculated and measured values allows recommending the method of calculated prediction in which an elementary function — the normalized arctangent of the logarithm of the reduced time serves as the normalized relaxation or creep function.     

Lamellar Thickness of a Syndiotactic Polystyrene Determined from Small-angle X-ray Scattering and Transmission Electron Microscopy

Extensive morphological studies on a syndiotactic polystyrene (sPS) sample prepared from compression molding were carried out using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). SAXS was conducted at 25C as well as at 150C to enhance the scattering contrast in order to obtain more reliable morphological parameters. The compression-molded sample was crystallized into a orthorhombic crystal lattice characterized by wide-angle X-ray diffraction (WAXD). A similar weight fraction of crystallinity, ca. 0.37, was obtained from both WAXD and differential scanning calorimetry measurements.In addition to the scattering peak at a scattering vector of ca. 0.36 nm^–1 attributable to the presence of lamellar/amorphous layers, anomalous scattering at the zero angle was found from the SAXS intensity profiles. Based on the Debye–Bueche theory, the scattering profile of this peculiar zero-angle scattering was deduced and was subtracted from the raw intensity profile to obtain the intensity profile exclusively associated with the lamellar/amorphous structure. A consistent long period was obtained for SAXS measured either at 25 or 150C, provided that the appropriate subtraction of intensities due to the zero-angle scattering was conducted. Moreover, the lamellar thickness deduced from the one-dimensional correlation function was in good agreement with TEM results. A difference scattering pattern derived from SAXS measured at 150 and 25C was obtained and a comparison of the morphological parameters was provided as well.     

Crystal structure and morphology of electrodeposited zinc-iron binary alloys

Deposits of zinc-iron alloy have been prepared galvanostatically from a sulphate bath and the crystal structure has been determined by X-ray diffraction and transmission electron microscopy measurements. The electrodeposited zinc-iron alloys have metastable structures and the individual phases coexist over wide composition ranges. The phases are identified as (10073 at % zinc), (8748 at % zinc), ₁(7862 at % zinc) and (620 at % zinc). Thec andc/a in the h.c.p. lattice of the -phase decrease continuously with decrease of zinc concentrations, and the latter changes from 1.86 to 1.60 (a andc are the lattice constants of the -phase in the direction of thea- andc-axes, respectively). The -phase particles exhibit a hexagonal plate-like morphology which is thin in the direction of thec-axis. The morphology of the electrodeposits changes from plate-like to pyramidal shape when fine -phase particles (100 nm) start to form surrounding the -phase platelets, and then to lenticular or granular in the /₁ duplex region. The -phase forms in the low zinc concentration region and changes the electrodeposits to a fine cuboidal morphology.     

Application of carbon materials in traumatology and orthopedics

Conclusions Carbon fibrous materials of the Ural type, prepared from hydrocellulose fibre, satisfy all the medical and technical requirements for use in medical practice. They have optimum physicomechanical characteristics, do not become torn off by the organism, and do not require a repeated operation for removal.The Ural-LM assortment of carbon tapes which has been developed is recommended for use in traumatology and orthopedics.Translated from Khimicheskie Volokna, No. 2, pp. 30–31, March–April, 1989.     

Mechanistic role of enolate ions in “group transfer polymerization”

Summary A new dissociative mechanism involving enolate anion intermediates is proposed for the process currently categorized as nucleophile-catalyzed group transfer polymerization (GTP). A rapid, reversible complexation of small concentrations of enolate anions with silyl ketene acetals (reversible termination) is proposed to explain the living nature of these polymerizations and the role of the silyl ketene acetals in GTP. It is proposed that these polymerizations do not involve group transfer in the chain-propagating step. These mechanistic conclusions are based on studies of the tetrabutylammonium 9-methyl-fluorenide- and methyllithium-initiated polymerizations of methyl methacrylate at ambient temperatures in the presence and absence of silyl ketene acetal.     

Heterogeneous asymmetric reactions. 23. Enantioselective hydrogenation of ethyl pyruvate over cinchonine- and α-isocinchonine-modified platinum catalysts

The enantioselective hydrogenation of ethyl pyruvate to (S)-ethyl lactate over cinchonine- and -isocinchonine-modified Pt/Al₂O₃ catalysts was studied as a function of modifier concentration and reaction temperature. The maximum enantioselectivities obtained under the applied mild conditions were 89% ee using cinchonine (0.014 mmoldm^–3, 1 bar H₂, 23°C, 6% AcOH in toluene), and 76% ee in the case of -isocinchonine (0.14 mmoldm^–3, 1 bar H₂, –10°C, 6% AcOH in toluene). Since -isocinchonine of rigid structure exists only in anti-open conformation these data provide additional experimental evidence to support the former suggestion concerning the dominating role of anti-open conformation in these cinchona-modified enantioselective hydrogenations.     

Stress relaxation during the orientation stretch of synthetics fibres

Conclusions Results of investigating structural changes during the process of orientation stretching above the glass point (hot stretching) for a number of thermoplastic fibres have been examined: polyethylene, polypropylene, polyvinyl chloride, chlorine, kapron, nitron, lavsan, vinol, and acetate yarns, plus results of heat-treatments under tension and in the free state. The possibility of describing the relaxation of internal stresses in these fibres in terms of the concept of operating volume has been shown.A correlative determination of the dependence of fibre stress dispersion during the process of orientation stretch and setting the structure of polyester yarn on the dispersion in yarn heat treatments has been established, as well as a dependence of the dispersion of physicomechanical properties on dispersion in fibre tension by steps in the technological process.Translated from Khimicheskie Volokna, No. 3, pp. 29–32, May–June, 1993.     

Preparation of crimped synthetic fibres directly in the spinning process

Conclusions In the preparation of crimped polyamide yarns without the use of texturing devices, it has been found that in yarns of complex profile, of the head-tail type, the two parts of the yarn cross-section interact in accordance with the bimetallic plate rule. The crimp can be described satisfactorily by the Brand-Backer equation.Dependences of the degree of crimp on the ratio of the head and tail lengths, birefringence, and spinning speed have been obtained for selected variants of yarn profile; this makes it possible to find an optimum regime for yarn preparation.Translated from Khimicheskie Volokna, No. 3, pp. 32–33, May–June, 1985.     

Criteria of excitation of explosive decomposition of silver azide by pulsed radiation

The process of explosive decomposition of silver azide in a pulsed electron radiation field was studied by the method of high-speed time-resolution optical spectroscopy. The criteria of excitation of explosive decomposition were determined. It is shown that in the case of short pulses, the critical parameter is the integral energy of the exciting pulse, whereas with the use of long pulses it is the pulse energy flux density.Published for purposes of discussionKemorovo. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 4, pp. 87–90, July–August, 1992.     

Use of white irons for lining press molds

Summary In production conditions during the pressing of chrome-magnesite brick KhM-1 it was shown that the wear resistance of white iron with HRC- 51 is 2.5 times higher than plates of 20Kh steel after cementation and hardening with HRC=60–62.Gray and mottled irons are poorly resistant to abrasion.White iron of e composition is recommended, for press plates (see table).Alloying iron with chromium, as in the case of composition e is easily ensured by using naturally alloyed iron mark LKhCh-6 in amounts of 25% of the batch.     

Role of plant volatiles in resistance of selected rice varieties to brown planthopper,Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

Rice plant volatiles extracted as steam distillates significantly affected the behavior and biology of the brown planthopper,Nilaparvata lugens (Stål). In a multichoice test, more females settled and fed on tillers of a susceptible rice variety Taichung Native 1 (TN1), sprayed with its own extract or acetone than on TN1 tillers sprayed with the extract of the resistant variety ARC6650 or Ptb33. In another test,N. lugens females ingested significantly more of a 10% sucrose solution mixed with TN1 steam distillate extract than of plain sucrose solution or that mixed with extracts of resistant varieties. Topical application of the extracts of resistant varieties Mudgo, ASD7, Rathu Heenati, Babawee, Ptb33, and ARC6650 caused significantly higher mortality of females than did the TN1 extract. Likewise, significantly more first-instar nymphs died when they were caged on susceptible TN1 plants sprayed with the extracts of resistant varieties than on plants sprayed with TN1 extract. The extract of 60-day-old resistant plants was more toxic than the extract of 30-, 45-, or 100-day-old plants. However, toxicity of the extract from susceptible TN1 remained low at all plant growth stages.Principal Research Scientist (ICIPE), based at International Rice Research Institute (IRRI), P.O. Box 933, Manila, Philippines.     

Convective Regime of Filtration Combustion of Energetic Materials in a Cocurrent Flow of Their Combustion Products

The convective regime of filtration combustion of energetic materials in a cocurrent flow of their combustion products is studied using a model with extremely simplified kinetics and heat transfer, which shows instability of the process. It is shown that the more accurate twotemperature model describes a steadystate regime. In this regime, the gas temperature on the hot boundary of the heating zone is well below the combustion temperature, and the solidphase temperature is well below the temperature proposed in recent studies on this topic. It is pointed out that the twotemperature approach is unjustified and intragranular nonisothermicity must be taken into account for convective regimes. It is shown that the threetemperature model, which takes into account this effect, does not give a stable steadystate solution.     

Effect of grain size on the synthesis of active alumina from gibbsite by flash calcination and rehydration

Two series of alumina have been prepared by flash calcination (FCAL) and subsequent rehydration of coarse (> 50 m) and fine grain size gibbsite (< 50 m). The initial grain size of the gibbsite was found to determine the degree of amorphization, water content, rehydration ability, composition and pore structure of FCAL products. Active alumina materials having pore structure parameters similar to those of commercial alumina adsorbents and catalyst supports were obtained by FCAL and subsequent rehydration of fine grain size gibbsite.     

Synthesis of statistical polydiene networks by reaction of liquid polyenes with telechelic siloxanes

The present investigation concerns the synthesis of statistical networks similar to vulcanized rubber. We have used liquid precursor polymers: polybutadiene (PB) and polyisoprene (PI) with telechelic siloxanes. The reactivity of the polydienes can be classified as follows: PB units 1,2 PI units 3,4 PI units 1,4 0. The network formation is a function of the ratio R = nb, of pendent double bonds/nb. of SiH. For R 1 the networks are rather hard and brittle, for 8 R 10 they are soft and elastic, whereas for R 16 the gels obtained are very soft and sticky.