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  • 1
    Electronic Resource
    Electronic Resource
    Aggregation Pheromone of Palm Weevil, Dynamis borassi (1997)
    Springer
    Journal of chemical ecology 23 (1997), S. 2287-2297 
    Details
    ISSN: 1573-1561
    Keywords: Aggregation pheromone ; Bursaphelenchus cocophilus ; coconut ; Cocos nucifera ; Coleoptera ; Curculionidae ; Dynamis borassi ; 4-methyl-5-nonanol ; palm weevils ; red ring disease ; red ring nematode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract 4-Methyl-5-nonanol (1) is the male-produced aggregation pheromone of the palm weevil, Dynamis borassi (F.) from Colombia. The pheromone was identified by coupled gas chromatographic–electroantennographic detection (GC-EAD) analysis of male- and female-produced volatiles, and comparative GC–mass spectrometry (MS) of weevil-produced 1. In field experiments in Colombia, traps baited with a stereoisomeric mixture of synthetic 1 (3 mg/day) plus sugarcane captured more weevils than traps baited with 1 or sugarcane alone, suggesting that pheromone and plant volatiles are synergistically attractive. Use of a chiral, stereoisomer-separating Cyclodex-B column in GC-EAD and GC-MS analyses revealed that D. borassi males produce, and antennae of males and females respond to (4S,5S)-1. Previously identified palm weevil (Rhynchophorus spp.) aggregation pheromones 5-methyl-4-octanol (cruentol) and 6-methyl-2-hepten-4-ol (rhynchophorol) also elicited antennal responses by D. borassi. In field experiments, D. borassi females were captured equally well in traps baited with sugarcane plus either 1, cruentol or rhynchophorol. In contrast, D. borassi males were captured most often in traps baited with sugarcane plus 1. Because D. borassi is a potential vector of the red ring nematode that causes the lethal red ring disease of palms, pheromone-based trapping of D. borassi could aid in monitoring or management of red ring disease in commercial palm plantations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:JOEC.0000006674.64858.f2
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  • 2
    Electronic Resource
    Electronic Resource
    Development of a computerized electrochemical system for stripping voltammetry (1990)
    Weinheim : Wiley-Blackwell
    Electroanalysis 2 (1990), S. 401-408 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A computer-controlled electrochemical system has been developed to determine heavy metal using stripping voltammetry. The system consists of a potentiostat (which we have designed and developed), a polarographic static mercury electrode (303A, PAR), an analog-digital conversion board (DT2801-A), a personal computer, and an HP7440 plotter. The potentiostat runs between -2.0 to +2.0 V with multirange current selection between ±50 nA and ±100 μA. There are various outlet channels with different time constants and noise levels. The fastest channel can detect processes on the order of 200 μs with a noise level of ±2.0 nA, while for 30 ms processes the noise is ±100 pA. The software developed controls the sequences of potentials, acquires and stores the currents, and plots them at its convenience. The system has been tested successfully in the determination of different metals using anodic and cathodic stripping voltammetry with different types of waveforms.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140020512
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  • 3
    Electronic Resource
    Electronic Resource
    The observation of a sub(gel-sol) transition in PVC/DOP gels (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 26 (1988), S. 1871-1880 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dynamic viscoelastic measurements on poly(vinyl chloride)/dioctyl phthalate gels have been carried out in parallel-plate shear mode. Two transitions are observed: the well-known gel-sol transition at temperature Tf, which probably corresponds to the beginning of fusion of crystalities, and a transition, at a temperature below Tf, denoted as Ts and corresponding to phase separation. The sub(gel-sol) Ts temperature is manifested as the transition from the first plateau zone to a second plateau in log G' versus temperature plots. Other techniques like polarizing microscopy and DSC measurements are not adequate for the detection of Ts.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1988.090260905
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  • 4
    Electronic Resource
    Electronic Resource
    Rheological and thermal properties of a commercial liquid-crystalline polyesteramide (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 1533-1550 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A commercial main-chain liquid-crystalline, naphthalene-based polyesteramide, was studied by three experimental techniques: extrusion capillary rheometry, dynamic viscoelasticity, and differential scanning calorimetry (DSC). From capillary rheometry a maximum at 360°C was observed in viscosity temperature curve. This result is compared with literature data for other thermotropics, and the possibility of a transition from a nematic to an isotropic phase is considered. The results obtained from dynamic viscoelasticity and DSC agree, and reveal the existence of a glass transition at 128°C (by DSC) and 137-147°C (by viscoelastic measurements, depending on frequency) as well as melting at 282°C. Annealing below 230°C produces two types of crystals, whereas annealing above this temperature gives rise to only one type of crystal, the melting temperature of which can be, depending on annealing time, as high as 340°C. The results are compiled in a phase diagram with six regions, four of them corresponding to the solid state, one to a liquid mesophase, and one to an isotropic phase.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1990.090280909
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  • 5
    Electronic Resource
    Electronic Resource
    Melt rheology of polyarylate/polybutylene terephthalate blends (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 529-534 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The viscosity, the activation energy of flow, and the exchange reactions of bisphenol A 50/50 isophthalic/terephthalic acid and poly(butylene terephthalate) blends are studied by means of an extrusion capillary rheometer, covering a range of 10 s-1 to 300 s-1 shear rate and 280°C to 300°C temperature. The results are interpreted in terms of compatibility and free volume additivity. The decrease in viscosity with time is explained as a result of transesterification rather than degradation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270709
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  • 6
    Electronic Resource
    Electronic Resource
    A comparison of some rheological properties of concentrated solutions of chlorinated polyethylene and polyvinyl chloride in dioctyl phthalate (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 31 (1986), S. 911-917 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Steady-state and transient shear flow properties of poly(vinyl chloride) and chlorinated polyethylene dissolved in dioctyl phthalate were studied at different temperatures and polymer concentrations. In the case of poly(vinyl chloride)/dioctyl phthalate systems the presence of a sol-gel transition temperature was observed, whereas for chlorinated polyethylene/dioctyl phthalate systems the mechanism of flow was the same in the whole range of temperatures and concentrations. On the basis of the data obtained for both polymer/solution systems, we conclude that the presence of crystallites, rather than hydrogen bonds, determines the rheological behavior of poly(vinyl chloride)/dioctyl phthalate systems.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070310314
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  • 7
    Electronic Resource
    Electronic Resource
    A high-speed computerized polarographic system for cathodic stripping voltammetry in seawater (1994)
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 1141-1146 
    Details
    ISSN: 1040-0397
    Keywords: Stripping voltammetry ; Computer control ; Seawater ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A low-cost computer-controlled high-speed polarographic system has been devised to determine heavy metals in seawater using adsorptive stripping voltammetry. The system consists of a potentiostat that has been developed in our Department, a 303A PAR polarographic cell, a personal computer with an I/O digital board PIO-96, and a hp7440 plotter. The potentiostat operates between -2.5 and +2.5 V, with a multirange selection current between ±100 nA and ±1000 μA. There are various outlet channels with different time constants and noise levels. The quickest channel can detect processes in a 10 μs range with a noise level of ±4 nA (seawater matrix), while for a range of 30 ms, the noise is ±100 pA. The software controls different signal patterns, techniques, and a complete set of operations and has been developed in the C language to accelerate the data acquisition. The system has been successfully applied to high-speed cathodic stripping voltammetry (HSCSV) on seawater samples, showing promising results in that there is an increase in the sensitivity over standard methods in the presence of oxygen and in stirred solutions. The analysis time can be reduced significantly at a high speed, and also, determinations aboard a ship are improved.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140061138
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  • 8
    Electronic Resource
    Electronic Resource
    High-Performance adsorptive cathodic stripping voltammetry of nickel and cobalt in seawater (1994)
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 1069-1076 
    Details
    ISSN: 1040-0397
    Keywords: Nickel ; Cobalt ; Stripping voltammetry ; Seawater ; Staircase modulation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The voltammetric determination of trace metals in seawater suffers from the interference of dissolved oxygen and engine vibrations onboard ship. It is here attempted to overcome these interferences using a high-frequency (1 to 20 kHz) staircase modulation during the voltammetric scan (high-performance adsorptive cathodic stripping voltammetry, HPACSV). Comparative experiments using the square-wave modulation showed that this modulation was not effective at such a high frequency. A comparison between various complexing agents (DMG and nioxime) and pH buffers (HEPES/NH4OH, borate/NaOH, and TEA/NH4OH) showed that the determination of nickel and cobalt was similarly improved by the high-speed potential scan in all conditions. Fast potential scans cause a large increase of the peak area and peak heights using staircase modulation. The peaks are wider, and the peak potentials are shifted toward negative values due to the ohmic drop, but the analytical determination is not disturbed. Optimal sensitivity for the determination of cobalt and nickel in seawater was obtained using TEA buffer and DMG as the adsorptive ligand. The nioxime wave was found to interfere in the cobalt peak at high scan rates so that this ligand is not recommended for HPACSV. Comparative tests showed that the sensitivity for nickel and cobalt determinations was highly improved by the fast scan rates. Furthermore, the reduction current of dissolved oxygen was partially masked so that measurements could be taken without a previous purge of the sample. Finally, the scans were insensitive to the solution turbulence so measurements could be readily carried out onboard of an oceanographic vessel or without switching off the stirrer. Low levels of nickel (2 nM) could be determined in seawater by using a deposition time of 20 seconds and of 120 seconds for 0.05 nM cobalt from turbulent and unpurged solutions. A fast determination method for labile nickel and cobalt is proposed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140061126
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  • 9
    Electronic Resource
    Electronic Resource
    Viscoelastic behaviour of molten polypropylene/polyethylene blends (1985)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 134 (1985), S. 63-71 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Einige Aspekte des viskoelastischen Verhaltens von 10 Blends von Polypropylen und langverzweigtem Polyethylen wurden untersucht. Messungen der Scherviskosität sind bei Temperaturen von 180-220°C und bei Scherraten von 1 - 1 000 s-1 durchgeführt worden. Die Elastizität wurde in Form der Strangaufweitung, des Anfangsdruckverlustes und der Schrumpfeffekte untersucht. Die auffallendsten Ergebnisse sind die enormen Schrumpfeffekte, die an Extrudaten bei 180°C beobachtet wurden; für einige Blendzusammensetzungen erreicht die Abnahme der Anfangslänge der Probe einen Wert von 800%.
    Notes: Some aspects of the viscoelastic behaviour of 10 blends of polypropylene and long branched polyethylene have been studied. Shear viscosity measurements have been carried out at temperatures from 180 to 220°C and shear rates from 1 s-1 to 1 000 s-1. The elasticity has been studied in terms of the extrudate swell, entrance pressure losses, and shrinkage effects. The most striking results are the enormous shrinkage effects observed on the extrudates at 180°C: for some blend compositions the reduction of the initial length of the sample attains a value of 800%.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1985.051340105
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  • 10
    Electronic Resource
    Electronic Resource
    TiO2-polymer composites for biomedical applications (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 35 (1997), S. 129-134 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Composite hydrogels of poly(acrylic acid) (PAA) and poly-(methyl metacrylate) (PMMA) reinforced with a bioceramic, TiO2, have been prepared by reactive moulding from a mixture of the bioceramic with PMMA beads and acrylic acid. Cylindrical specimens with various TiO2-polymer compositions, but a constant 3:1 PAA/PMMA ratio were obtained, and their corresponding swelling behavior was followed at pH = 7.0 and pH = 8.0 in buffered solution at 37°C. The composition and structure of the composites prepared was studied by thermogravimetry, 1H-NMR spectroscopy and scanning electron microscopy. The composites prepared present a considerable consistency, even in hydrated media, since their swelling behavior is rather sensitive to the pH of the media. Specific polar interactions of the carboxylic groups of the hydrophilic polymer component PAA with the surface of TiO2 particles, modulate the behavior of the composites against the hydration processes at different pH. © 1997 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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