Further studies concerning chemoattraction among fry of arctic charr [Salvelinus alpinus (L.)] to water conditioned by conspecifics

Chemoattraction of fry of Arctic charr [Salvelinus alpinus (L.)] to water scented by conspecifics of the same age was studied in a Y-maze fluviarium. The fry were offspring of two sympatric populations. Specimens of one of the two populations were indifferent to conspecific odor during the two-month experimental period. Specimens of the other population showed significant attraction to water scented by either population when their mean fresh weight was higher than 0.09 g. A significant difference in rheotactic response also was observed. Offspring of the population spawning in an inlet stream showed less motivation for upstream swimming, although they were significantly attracted to conspecific odor.     

Mineral elements in mate herb (Ilex paraguariensis St. H.)]

The importance of the research works on mate rests on the fact that this is greatly consumed in many South American countries. Our interest in this subject has increased because, in Europe, it use as an infusion seems to be increasing. The Na, K, Ca, Mg, Cu, Fe, Mn and Zn contents were determined by atomic absorption spectrometry techniques. Prior to this, samples were incinerated and dissolved in an acid mixture (HCl/HNO3). Results apparently show a high content of mineral elements, especially K. Mg and Mn, in mate, findings which we consider to be of great relevance.     

Chemoattraction between fry of Arctic char [Salvelinus alpinus (L.)] studied in a Y-maze fluviarium

Attraction of fry of Arctic char [Salvelinus alpinus (L.)] to water conditioned by conspecifics of the same age was studied in a Y-maze fluviarium. Two types of experiments were run. In up-swimming tests (1), starting from the common leg of the Y-maze, a single fish was given the choice of entering one of the two upstream arms. In gradient tests (2), the momentary positions of a single char were time-lapse photographed in a test yard of this common shank. Strong attraction to conditioned water was observed in both types of tests.     

Squash leaf glandular trichome volatiles: Identification and influence on behavior of female pickleworm moth [Diaphania nitidalis (Stoll.)] (Lepidoptera: Pyralidae)

Fourteen volatile compounds occurring in leaf trichomes of yellow squash (Cucurbita pepo L. cv. Early Prolific Straightneck) were identified. These compounds accounted for 83.5% of the volatile matrix. Ubiquitous constituents of the epidermis (myristic, palmitic, and stearic acids,n-tricosane, andn-pentacosane) accounted for 73.7%; these compounds were not bioassayed. The volatileso-,m-, andp-xylene, toluene, 2-heptanone, (R)-(+)- and (S)-(–)-limonene, and germacrene D were tested for their influence on attraction and oviposition by the pickleworm moth (Diaphania nitidalis Stoll.). No single compound, except germacrene D, was attractive. (R)-(+)-Limonene and 2-heptanone were weakly repellent. Mixtures of the highly volatile fractions were as attractive as volatiles emanating from whole, intact leaves. Oviposition levels on treated artificial sites corresponded with levels of visitation. Oviposition was significantly stimulated by whole-leaf volatiles, and (S)-(–)-limonene caused a slight but significant reduction.Mention of a trade name or proprietary product does not constitute a warranty or guarantee by the U.S. Department of Agriculture, nor does it imply exclusion of other products that may also be suitable.     

Behavior of neonate diamondback moth larvae [Plutella xylostella (L.)] on leaves and on extracted leaf waxes of resistant and susceptible cabbages

NeonatePlutella xylostella moved more rapidly, spent more time walking, and engaged in searching behaviors more often on leaves of NY 8329, a resistant cabbage with glossy leaves, than on Round-Up, a susceptible variety with normal wax bloom. The neonates also spent significantly more time palpating and more time biting and spinning silk on the susceptible cabbage (although the latter two differences were not significant). Very similar differences in neonate behavior occurred on leaf surface wax extracts (hexane and dichloromethane) of the two cabbage genotypes. Leaf surface waxes are thus strongly implicated in eliciting reduced acceptance of the glossy cabbage by neonateP. xylostella. The chemical compositions of the leaf wax extracts were markedly different. Several compounds, including the triterpenols- and-amyrin, were found only in the glossy waxes. The percentages of some major wax constituents differed between wax extracts of the two cabbage types. These differences in wax composition may condition the plant resistance in glossy types.     

Physiological,Agronomical, and Proteomic Studies Reveal Crucial Players in Rice Nitrogen Use Efficiency under Low Nitrogen Supply

Excessive use of nitrogenous fertilizers to enhance rice productivity has become a significant source of nitrogen (N) pollution and reduced sustainable agriculture. However, little information about the physiology of different growth stages, agronomic traits, and associated genetic bases of N use efficiency (NUE) are available at low-N supply. Two rice (Oryza sativa L.) cultivars were grown with optimum N (120 kg ha⁻¹) and low N (60 kg ha⁻¹) supply. Six growth stages were analyzed to measure the growth and physiological traits, as well as the differential proteomic profiles, of the rice cultivars. Cultivar Panvel outclassed Nagina 22 at low-N supply and exhibited improved growth and physiology at most of the growth stages and agronomic efficiency due to higher N uptake and utilization at low-N supply. On average, photosynthetic rate, chlorophyll content, plant biomass, leaf N content, and grain yield were decreased in cultivar Nagina 22 than Panvel was 8%, 11%, 21%, 19%, and 22%, respectively, under low-N supply. Furthermore, proteome analyses revealed that many proteins were upregulated and downregulated at the different growth stages under low-N supply. These proteins are associated with N and carbon metabolism and other physiological processes. This supports the genotypic differences in photosynthesis, N assimilation, energy stabilization, and rice-protein yield. Our study suggests that enhancing NUE at low-N supply demands distinct modifications in N metabolism and physiological assimilation. The NUE may be regulated by key identified differentially expressed proteins. These proteins might be the targets for improving crop NUE at low-N supply.     

Transport studies in poly(methyl methacryalate-g-urethane)

Transport studies of two organic liquids, toluene and n-hexane, have been performed in polyurethane and poly (methyl methacrylate-g-urethane). A high degree of selectivity in the permeation of these two liquids has been achieved by MMA grafting. A near perfect separation has been realized by grafting of MMA to 28%.     

Infrared and Raman spectral studies in cement and concrete (review)

Applications of infrared and Raman spectroscopy in the field of cement and concrete as reported over the years are quite significant. Specific applications in areas such as, identification of cement phases including different polymorphic and crystal forms, estimation of phases in cement, cement hydration, admixture, concrete-polymer, alkali-aggregate reactions, etc, have been recognised with various degree of success. More application of these techniques is envisaged with further advancement in instrumentation and in sample preparation, especially in newer products where organic substances play dominant role.     

Synthesis of pungenin,a foliar constituent of some spruce species,and investigation of its efficacy as a feeding deterrent for spruce budworm [Choristoneura fumiferana (Clem.)]

Pungenin was synthesized from 3,4-dihydroxyacetophenone by a short sequence involving manipulation of protecting groups on the 3 and 4 hydroxyl functions. Bioassays indicated that the glucoside is a modest feeding deterrent for sixth-instar spruce budworm larvae, but it does not appear to retard the development of small larvae or lead to increased mortality.     

Miscibility studies in blends of polybenzimidazoles and poly(4-vinyl pyridine)

Poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (PBI) is shown to be miscible with poly(4-vinyl pyridine) over the entire composition range. Experiments were performed with commercial PBI as well as a lower molecular weight material synthesized by us. Blend miscibility is evidenced by single glass transition temperature intermediate between the pure polymers. Hydrogen bonding between the components was detected by infrared spectroscopy.     

Ultrasonic relaxation studies of poly(isobutylene) in m-xylene

Ultrasonic measurements are reported on solutions of two different samples of poly(isobutylene), one relatively regularCH₂C(CH₃)₂(Vistanex L80) and one with considerable structural irregularity such as chain branching (Vistanex L140). Measurements were carried out from 303–353K in m-xylene over a frequency range 1–100 MHz. A low frequency normal mode (viscoelastic) and a higher frequency conformational absorption are observed. The temperature dependence of the conformational absorption reveals a pseudo helix-coil transition at around 323K. Above this temperature, the two polymers show temperature coefficients of different sign. This phenomenon is explained in terms of a lower energy difference between conformational states in the branched chain polymer.     

Electrochemical and in situ FTIR studies of biferrocene platinum(II) complex

Electron transfer mechanism during redox process of Pt(LSB)₂, a derivative of S-benzyl-N-(ferrocenyl-1-methyl-metylidene)-dithiocarbazate (HLSB), is studied by cyclic voltammetry, differential pulse voltammetry, digitally simulation and in situ FTIR spectroelectrochemistry. Electrochemistry results indicated the redox process of Pt(LSB)₂ involves two consecutive one-electron steps. Coordination of Pt to HLSB resulted in the increase of electron-withdrawing of the dithiocarbazate group, which is demonstrated by the positive shift of redox potentials of Pt(LSB)₂ compared with those of HLSB. The peak-peak separation of 129 mV revealed a strong degree of electronic communication between the two-ferrocene moieties in Pt(LSB)₂. The results of in situ FTIR indicated that electronic communication takes place through the skeleton chain of HLSB due to the extensive electron delocalization in the whole molecule.     

Infrared studies of cryogenic transitions in poly(ethylene terephthalate) and polystyrene

Infrared absorbance measurements as a function of temperature down to 13°K have been made on poly(ethylene terephthalate) and polystyrene. Transition temperatures are assigned to the temperatures where there are abrupt changes in the absorbance or integrated band intensities. Bands of known structural origin arising from either crystal-line or amorphous phases are studied to probe the structure basis and environment effect for each transition. Transitions are found around 50, 120, 180, and 220°K for PET and around 50° and 235°K for polystyrene.     

Dielectric and mechanical-dynamical studies on poly(cyclohexyl methacrylate)

The relaxation processes in poly(cyclohexyl methacrylate) have been studied by transient and dynamic dielectric means as well as by viscoelastic techniques. The study embraces also the effect of the thermal treatment on the α and β relaxations. The α relaxation has been fitted into the empirical model of Havriliak and Negami, and the functional relation between the mean relaxation times and the temperature has been adjusted to the equation of Vogel. The β relaxation is strongly hindered, so it is scarcely perceivable. The secondary γ relaxation was studied mainly by dielectric means. Its apparent activation energy does not depend on the temperature and amounts to 11.2 ± 0.2 kcal mol^?1. It allows an application of the time-temperature superposition principle and its behaviour is thermorheologically simple. A δ relaxation with a temperature-independent apparent activation energy of 8.5 kcal mol^?1 has been obtained     

FTIR-microspectroscopy and DSC studies of poly(vinylidene fluoride)

Poly(vinylidene fluoride) (PVDF) samples, obtained by casting from tetrahydrofuran solutions and submitted to various thermal treatments, have been examined by Fourier transform–infrared microspectroscopy (FTIR-M) and differential scanning calorimetry (DSC). This kind of analysis allowed us to examine microdomains of samples with different morphological characteristics and to obtain an indication of the polymorphism of PVDF. In some cases the simultaneous presence of two or three forms has been evidenced thanks to the comparison of FTIR-M spectra and DSC traces. Vibrational spectra of single crystalline forms can be recorded by FTIR-M on phase homogeneous microdomains.     

Enantiospecific synthesis fromd-fructose of (2S,5R)- and (2R,5R)-2-methyl-1,6-dioxaspiro[4.5]decane [the odor bouquet minor components ofParavespula vulgaris (L.)]

The synthesis of (2S,5R)-(1) and (2R,5R)-2-methyl-1,6-dioxaspiro [4.5]decane (2) from (2RS,5R,8R,9R,10S)-8,9,10-trihydroxy-2-methyl-1, 6-dioxaspiro[4.5]decane (8), obtained in five steps fromd-fructose using Wittig's methodology, reduction, and spiroketalation, has been accomplished by a Corey dideoxygenation at C-8,9, followed by a Barton deoxygenation at C-10, of the appropriately protected derivatives.Enantiospecific synthesis of spirocetals. Part V. For Part IV, see Izquierdo et al. (1992).     

Microstructural and corrosion studies of Ti alloy (IMI 834) in acidic solutions

The electrochemical polarization behaviour of a titanium alloy (IMI 834) was studied in different concentrations of aqueous and ethylene glycolic solutions of hydrochloric and phosphoric acid at 30 °C. The influence of furnace cooled (FC), air cooled (AC) and water quenched (WQ) heat treatments and microstructure on polarization behaviour was also studied. An active passive transition and a large range of passivity potential were observed in aqueous and glycolic solutions of the acids. The magnitudes of the critical current density (i _c) and passive current density (i _p) were higher for hydrochloric acid in comparison to phosphoric acid. Values of i _c and i _p were lower in ethylene glycol–hydrochloric acid up to 7 M and were higher above 7 M hydrochloric acid–ethylene glycol solutions as compared to the corresponding hydrochloric acid concentrations. However, these values were always lower in ethylene glycol–phosphoric acid than in phosphoric acid solutions. The microstructure of the alloy after solution treatment (1080 °C, 30 min; FC, AC and WQ) showed single phase transformed structure. The increase in the cooling rate enhances the fineness of the laths. The working electrode surface was examined by scanning electron microscopy (SEM) and scanning tunnelling microscopy (STM).