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  • 1
    Electronic Resource
    Electronic Resource
    On potentials and relevance of the use of copulatory structures in anostracan taxonomy (1997)
    Springer
    Hydrobiologia 359 (1997), S. 83-92 
    Details
    ISSN: 1573-5117
    Keywords: Branchiopoda ; Anostraca ; genital morphology ; genus concept
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper reviews and extends the knowledge of anostracan penile morphology and its taxonomic significance. Since Linder‘s pioneering classification(based partly on male genital characters), the morphology of both basal and distal penile parts has been applied repeatedly to reorganize or establish higher anostracan taxa, or to extend their diagnoses. In general, the configuration of both basal and distal penile structures follows a constant pattern in well-defined genera. Size and shape of processes and spinulation on the basal (in Linderiella and Chirocephalidae) and the distal parts (in Parartemia), however, may show inter-specific differences. Variability in penile structures in the current genus Brachinella indicates the need for a taxonomic revision of this genus. Similar intra-generic penis morphology may contribute to hybridizability of congeners and validate Dubois‘genus concept for use in anostracans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003125812020
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  • 2
    Electronic Resource
    Electronic Resource
    Large branchiopod assemblages common to Mexico and the United States (1997)
    Springer
    Hydrobiologia 359 (1997), S. 45-62 
    Details
    ISSN: 1573-5117
    Keywords: Crustacea ; Branchiopoda ; community ecology ; sympatry ; co-occurrence ; temporary pools
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We present observations on the frequency of large branchiopod associations found in north-central Mexico, and in Arizona, USA. Of a total of 25 species involved in these assemblages, 12 were common in both areas. Fifty-eight (43.3%) of the ponds in Mexico, and seventy-eight (47%) of those in Arizona had two or more species present. The combinations of species which occurred with highest frequency were Streptocephalus mackini with Thamnocephalus platyurus for Arizona, and T. platyurus, Triops sp., and Leptestheria compleximanus for Mexico. In Mexico, and Arizona, as in many parts of the world, multispecies assemblages of large branchiopods are a common phenomenon. Therefore, the ’common rule‘ of’one-phyllopod-per-habitat‘ advanced by Weise (1964) is inconsistent with field observations. Furthermore, since cases of co-occurrence of two or more congeneric species of Anostraca and Notostraca are not uncommon, generalizations about congeners not coexisting remain applicable only for the Spinicaudata and Laevicaudata. On the basis of the literature, and of observations in the field and in the laboratory, we list potential factors contributing to the co-occurrence of several species within a pond.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003102601542
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  • 3
    Electronic Resource
    Electronic Resource
    Branchinella maduraiensis Raj (Crustacea, Branchiopoda, Anostraca) shown by new evidence to be a valid species (1997)
    Springer
    Hydrobiologia 359 (1997), S. 93-99 
    Details
    ISSN: 1573-5117
    Keywords: Branchiopoda ; Branchinella ; taxonomy ; morphology ; India
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fairy shrimp Branchinella kugenumaensis (Ishikawa) was long considered a widely, though disjunctly, distributed species occurring from Japan through eastern Asia to southern India. Attempts by Raj (1951, 1961) to make the Indian populations a new variety (B. k. var. madurai) on the basis of antennal and frontal appendage morphology and on its distribution pattern, were considered unconvincing by later authors. Our new comparison of Japanese and Indian specimens has revealed several differences. The resting egg shells of B. kugenumaensis from Japan have irregular polygonal fields; whereas, the shells of the Indian taxon have lip-like units covered with spinules. Furthermore, there are lobes lateral to the basal penes in the Indian specimens that are lacking in the Japanese taxon. As well as differences in antennal and frontal appendage morphology. These differences correspond with previous illustrations of populations from both geographic regions and lead us to consider Raj's proposed subspecies as a valid species. This brings the number of accepted species in the genus Branchinella to 34. More specimens will need to be evaluated from the area between India and Japan to determine if B. maduraiensis is endemic to the Indian subcontinent or is more broadly distributed on the Asian mainland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003173727950
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  • 4
    Electronic Resource
    Electronic Resource
    Spectral narrowing in optically pumped poly (p-phenylenevinylene) FilmsWe thank Cambridge Display Technology (CDT) for supplying the PPV precursor used in this research. This work is supported by the Engineering and Physical Sciences Research Council, and is part of a collaborative program with the chemistry group of A. B. Holmes and S. C. Moratti in Cambridge. (1997)
    Weinheim : Wiley-Blackwell
    Advanced Materials 9 (1997), S. 547-551 
    Details
    ISSN: 0935-9648
    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
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19970090705
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  • 5
    Electronic Resource
    Electronic Resource
    Identification and quantitation of urinary dicarboxylic acids as their dicyclohexyl esters in disease states by gas chromatography mass spectrometryMMA = methylmalonic acid; EMA = ethylmalonic acid. (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 6 (1979), S. 546-553 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Clinical studies were conducted by gas chromatography mass spectrometry selected ion monitoring of urinary dicarboxylic acids as dicyclohexyl esters. The dicyclohexyl esters of the dicarboxylic acids give characteristic electron impact mass spectra suitable for selected ion monitoring. The mass spectra exhibit a prominent acid + 1H ion and an (acid + 1H)- H2O ion for use as quantitating and confirming ions. The cyclohexyl esters are stable for days at room temperature and have excellent chromatographic properties. Dicarboxylic acid quantitation is performed within one hour using only 50 μl of unpurified urine. A rapid method specifically for methylmalonic acid quantitation is described which has assisted physicians in the diagnosis of pernicious anemia and methylmalonic aciduria. This procedure is applicable for screening urinary organic acids for detection of inborn errors of metabolism. The detection of a child with elevated medium length dicarboxylic acids in the terminal urine specimen is reported. This condition, previously described as an inborn error, is attributed to a terminal event. Finally, an increase in urinary succinic acid paralleling putrescine levels is described during a response to cancer chemotherapy.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200061203
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  • 6
    Electronic Resource
    Electronic Resource
    Gravimetric measurements of steady-state moisture uptake in spin-coated polyimide films (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 75-83 
    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: Polyimide (PI) is an insulating polymer that is finding increased use in the semiconductor industry as an intermetal dielectric, passivation coating, and planarization layer. It has a low dielectric constant (3.5 at audio frequencies) and can be processed at temperatures below 450°C. These features make PI attractive to the integrated circuit industry. One disadvantage of this material is that, like most polymers, it is hygroscopic. Moisture can lead to such reliability problems in integrated circuits as increased insulator conductivity, loss of adhesion, and corrosion. It is important to quantify the moisture uptake in polyimide so that the reliability implications of its use can be fully understood. In this study, the steady-state moisture uptake of the model PI pyromellitic dianhydride-oxydianiline (PMDA-ODA) is reported. The moisture uptake is measured using a Cahn 1000 Microbalance with a 1-μg resolution. The samples are prepared by spin-coating one or more layers of the precursor polyamic acid onto 2-in silicon substrates. The moisture uptake in these polymers is found to be linearly related to ambient relative humidity, and the maximum moisture uptake by weight is 3.2%. The moisture uptake in PI is also shown to be a bulk absorption rather than a surface adsorption phenomenon.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420109
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of aging on polyimide: A study of bulk and interface chemistry (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 271-280 
    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: We are investigating the bulk and interfacial chemistry of polyimide (PI) exposed to heat and relative humidity (RH) stress (85°C/85% RH) over long periods to understand the long-term reliability aspects of PI for microelectronic applications. The PI surface chemistry and the PI-Si interface chemistry was followed with electron spectroscopy for chemical analysis (ESCA). For exposure times greater than 550 h, the PI surface exhibits significant changes in emission structure and atomic concentration. The PI-Si interface indicates little change in the PI chemistry when compared to control samples. The water-contact angle at the PI surface shows no statistically significant change as a function of exposure time. Bulk and surface chemistry were followed with Fourier transform infrared spectroscopy (FTIR) in a grazing incidence reflection configuration. There were measurable differences in FTIR spectra between aged and control samples only for the case of very thin PI layers. These results suggest that for exposure times of less than 1100 h, chemical changes in PI occur primarily at the PI-air interface for samples 1 μm thick and greater. These changes represent a possible rearrangement of the imide structure and may be a form of deimidization of the polymer, but the final state is not polyamic acid. The PI surface chemistry changes observed with ESCA are reversible upon reheating to the cure temperature.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460208
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  • 8
    Electronic Resource
    Electronic Resource
    The effect of radical trapping reagents upon formation of poly(α-tetrahydrothiophenio para-xylylene) polyelectrolytes by the wessling soluble precursor method (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2223-2231 
    Details
    ISSN: 0887-624X
    Keywords: poly(arylene vinylene) ; poly(1,4-phenylene vinylene) ; poly(para-phenylene vinylene) ; para-xylylene ; 1,4-benzoquinodimethane ; radical polymerization ; conducting polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular weights were studied by gel permeation chromatography of derivatized poly(α-tetrahydrothiophenio para-xylylene) chloride produced by aqueous or methanolic base-induced polymerization of 1,4-bis(tetrahydrothiopheniomethyl) benzene dichloride, both with and without a variety of added polymerization inhibiting agents. Efficient radical scavenging agents such as 2,2,6,6-tetramethylpiperidinoxyl and hydrogen atom donor 2,4,6-tri-tert-butylaniline reduced the degree of polymerization of the reactive α-(tetrahydrothiophenium chloride)-para-xylylene intermediate produced in this chemistry, and in some cases completely suppressed formation of high polymer. These two traps did not affect the equilibrium production of the para-xylylene by UV-Vis spectral analysis; hence they must affect the subsequent polymerization chain propagation steps in the mechanism. Electron spin resonance studies of polymerization in the presence of 0.00025 equiv of TEMPO showed disappearance of the spin label, a result consistent with a radical scavenging process. The results suggest that production of high molecular weight poly(α-tetrahydrothiophenio para-xylylene) chloride proceeds through a radical chain propagation sequence. © 1992 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301018
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  • 9
    Electronic Resource
    Electronic Resource
    Para-Xylylenes and analogues by base-induced elimination from 1,4-bis-(dialkylsulfoniomethyl)arene salts in poly(1,4-arylene vinylene) synthesis by the wessling soluble precursor method (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2233-2240 
    Details
    ISSN: 0887-624X
    Keywords: para-xylylenes ; 1,4-benzoquinodimethanes ; conducting polymers ; poly(arylene vinylene)s ; poly(phenylene vinylene)s ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: para-Xylylenes are generated by treatment of various 1,4-bis(dialkylsulfoniomethyl)arene dihalides with base in water, methanol, and aqueous acetonitrile, as shown by UV-Vis spectroscopy. This procedure allows the monitoring of the transient xylylene monomers that yield polyelectrolyte precursor polymers for poly(arylene vinylene)s, formed by variations of the chemistry developed originally by Wessling and co-workers. Alkoxy, alkyl, and halogen ring substituents on the sulfonium salt precursors do not greatly affect the ability to generate and observe the growth and decay of steady-state concentrations of the para-xylylene intermediates. Use of strong resonance-acceptor substituents - such as cyano or nitro - on the ring reduces production of a strong para-xylylene absorption, possibly due to reluctance of the ylides initially formed from the bis-sulfonium salts to eliminate to the xylylenes. By variation of UV-Vis conditions, it was found that use of 20% aqueous acetonitrile rather than water allowed formation of low to modest molecular weight polyelectrolytes in cyano-substituted cases (Mw = 8000-37,000). Use of UV-Vis test experiments should be useful for screening of bis sulfonium salt precursors that may be expected to give high molecular weight polyelectrolytes - in cases where para-xylylene formation is easy - as well as for finding reaction conditions that will optimize polymer formation. © 1992 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301019
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  • 10
    Electronic Resource
    Electronic Resource
    In situ FTIR investigation of MMA plasmas, plasma-polymerized films, and reaction mechanisms (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 587-602 
    Details
    ISSN: 0887-624X
    Keywords: plasma polymerization ; methyl methacrylate ; in situ FTIR/ATR diagnostic ; in situ FTIR plasma diagnostic ; analysis of variance ; regression analysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl methacrylate (MMA) plasmas and plasma-polymerized methyl methacrylate (PPMMA) films were studied in situ with FTIR and FTIR/ATR (attenuated total reflection) in an r.f. capacitively coupled glow discharge. A statistically designed experiment was conducted by varying the r.f. power, process pressure, and MMA flow rate. MMA plasma fragments were identified from the gas-phase FTIR measurements. They include the intermediate species such as dimethylketene, formaldehyde, allene, and propene; small hydrocarbons such as acetylene, methane, and ethylene; and oxygenates such as carbon dioxide, carbon monoxide, and methanol. Statistical analysis techniques (correlation analysis, analysis of variance and regression analysis) were used on both gas and film data. Gas-phase reaction mechanisms are proposed, and the relationship between the gas and film data is investigated to understand the film deposition chemistry. The deposition rate is positively correlated to the relative concentrations of MMA fragments which are identified as the major film precursors in the deposition process. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 587-602, 1998
    Additional Material: 11 Ill.
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