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  • 1
    Electronic Resource
    Electronic Resource
    Donor tissue and culture condition effects on mesophyll protoplasts of Medicago sativa (1987)
    Springer
    Plant cell, tissue and organ culture 9 (1987), S. 217-228 
    Details
    ISSN: 1573-5044
    Keywords: alfalfa ; pretreatment ; culture medium ; direct embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mesophyll protoplasts were produced from clones of two cultivars of Medicago sativa, ‘Rangelander’ and ‘Regen S’. Protoplasts from the ‘Regen S’ clone generally gave rise to calli while those from the ‘Rangelander’ clone would undergo direct embryogenesis. Effects of plant growth conditions, donor tissue pretreatment and protoplast culture conditions on mesophyll protoplast production and subsequent development patterns were investigated. The major factor determining whether or not mesophyll protoplasts would be produced from either of the clones was the pretreatment in water of shoots excised from the donor plants. Pretreatment in water containing growth regulators did not alter protoplast production or development in the ‘Regen S’ clone. Pretreatment of the ‘Rangelander’ clone shoots with abscisic acid or naphthaleneacetic acid was slightly beneficial to embryo production while pretreatment with benzylaminopurine was detrimental. Altered leaf morphology induced by growth condition changes did not affect mesophyll protoplast production or subsequent development patterns when shoots were pretreated in water. Culture of protoplasts in liquid droplets or solid agar medium increased low density protoplast survival and subsequent embryo production in the ‘Rangelander’ clone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040807
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  • 2
    Electronic Resource
    Electronic Resource
    Role of genetic background in somatic embryogenesis in Medicago (1985)
    Springer
    Plant cell, tissue and organ culture 4 (1985), S. 111-122 
    Details
    ISSN: 1573-5044
    Keywords: alfalfa ; somatic embryogenesis ; germplasm ; genotypic variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seventy-six cultivars of alfalfa (Medicago sativa L., M. falcata L. and M. varia Martyn) were tested in vitro for their capacity to produce callus and somatic embryos. A three-step media protocol was used to survey the response of the cotyledons and hypocotyl of each genotype while the epicotyl region was conserved in order to recover highly responding genotypes. The best regeneration response was observed in creepingrooted cultivars which contained a strong genetic contribution of two landrace germplasm sources, defined as M. falcata and Ladak, in their ancestry. The callus and embryogenesis responses showed a high degree of variation both between cultivars and among the plants of many of the 76 cultivars tested. A higher number of plants produced somatic embryos in the high regenerating cultivars compared to the low regenerating cultivars regardless of the media protocol or explant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042269
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  • 3
    Electronic Resource
    Electronic Resource
    Development of a simple particle bombardment device for gene transfer into plant cells (1994)
    Springer
    Plant cell, tissue and organ culture 37 (1994), S. 47-53 
    Details
    ISSN: 1573-5044
    Keywords: transient gene expression ; β-glucuronidase ; alfalfa ; soybean ; DNA transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A simple particle bombardment device was designed, constructed and shown to be efficient for the delivery of DNA into plant cells. High levels of transient β-glucuronidase expression were observed in alfalfa suspension-cultured cells and embryogenic soybean suspension-cultured cells. Expression of β-glucuronidase in alfalfa suspension-cultured cells was used to optimize the bombardment conditions for the device. Transient gene expression in alfalfa was found to be dependent on the state of the target tissue, the size of particles employed, the helium pressure used to accelerate the particles and the distance travel led by the tungsten particles carrying DNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048116
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  • 4
    Electronic Resource
    Electronic Resource
    Plant regeneration from suspension culture and mesophyll protoplasts of Medicago sativa L. (1984)
    Springer
    Plant cell, tissue and organ culture 3 (1984), S. 149-162 
    Details
    ISSN: 1573-5044
    Keywords: alfalfa ; somatic embryogenesis ; protoplast ; cell suspensions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A system was established for achieving plant regeneration from mesophyll protoplasts and cotyledon-derived cell suspension cultures of alfalfa, Medicago sativa L. Peeled leaflets or cells from 6-day-old cell suspensions were incubated in an enzyme mixture containing 1% Driselase, 1% Rhozyme, 0.1% Cellulase and 72 gl-1 mannitol at pH 5.8 for 2–16 h to liberate protoplasts. A complex Kao medium supported cell division and colony formation, whereas a high auxin/low cytokinin treatment on Schenk and Hildebrandt medium followed by culture on growth regulator-free Blaydes or Linsmaier and Skoog medium resulted in somatic embryo formation. Of the three varieties tested. Citation, Answer and Regen S, the latter two produced embryos from which plants could be regenerated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00033736
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  • 5
    Electronic Resource
    Electronic Resource
    Glass transition temperatures of several fluorine-containing polymers (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 7 (1969), S. 601-608 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The glass transition temperatures Tg of several fluorine-containing polymers were determined by use of the differential scanning calorimeter. Values between -3 and 230°C were obtained. In polymers of α-olefins, Tg increases with the fluorine content of the backbone and the length of the n-perfluoroalkyl branch. In styrene polymers Tg also is higher if the backbone contains fluorine but nearly the same Tg's are found for polymers with phenyl and pentafluorophenyl groups. Saturated polymers of perfluoro-α,ω-dienes have lower Tg's than polyperfluoro-α-olefins. The Tg's of chloroperfluoropolymers are higher than those of perfluoropolymers. Polyperfluoropentadiene-1,3 has the lowest Tg of the polymers examined. Polyperfluoropentadiene-1,3 forms by 1,4-addition.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.160070402
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  • 6
    Electronic Resource
    Electronic Resource
    Equilibrium acid concentrations in hydrolyzed polyesters and polyester-polyurethane elastomersPresented in part at the 184th meeting of the American Chemical Society, Kansas City, MO, September 12-17, 1982, Ref. 1. (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 3779-3792 
    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: Equilibrium acid concentrations, [Ae], were determined in butylene adipate and caprolactone polyesters, of low molecular weight, and in thermoplastic polyurethane elastomers based on these polyesters. Values of [Ae] of the polyesters at 85°C were 0.7, 1.3, and 3-4 × 10-3 mol/g at relative humidities (RH) of 25%, 50%, and 93%, respectively. [Ae] of the thermoplastic elastomers at 85°C were about 3 and 7 × 10-4 mol/g at 10% and 25% RH, respectively. Values of [Ae] were not very dependent on temperature at constant RH. Equilibrated thermoplastic elastomers had low molecular weights and poor physical properties. Consequently, equilibration does not set a practical limit on hydrolytic degradation, even at low RH. Equations were developed that described the variation in acid content with time. Rate constants for hydrolysis and esterification increased as RH decreased. Reesterification in the elastomers in the absence of water is too slow to be a useful method of decreasing hydrolytic damage.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1983.070281218
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  • 7
    Electronic Resource
    Electronic Resource
    Glass and melting transitions of copolymers of tetrafluoroethylene with propylene and isobutylenePresented at the 165th Meeting of the American Chemical Society, Dallas, Texas, April 8-13, 1973, Leo A. Wall Memorial Symposium. (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1303-1318 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolymers of tetrafluoroethylene and propylene were prepared that contained 30-65 mole-% of the former. Reactivity ratios of tetrafluoroethylene- and propylene-ended radicals are 0.008 and 0.06, respectively, resulting in formation of highly alternating copolymers. The glass temperatures, Tg, were determined using a differential scanning calorimeter. Values ranged from 260 to 275°K. A plot of Tg versus composition has a low maximum centered about the equimolar composition. Copolymers of tetrafluoroethylene and isobutylene were prepared that contained 30-56 mole-% of the former. Reactivity ratios of tetrafluoroethylene- and isobutylene-ended radicals are 0.005 and 0.021, respectively. The glass temperatures of these copolymers range from 257 to 313°K. A higher maximum at the equimolar composition is obtained when Tg is plotted versus composition. Isobutylene-containing copolymers having 45-54 mole-% tetrafluoroethylene are crystalline. Melting temperatures range from 416 to 476°K and have their maximum value at the equimolar composition. It is thought that long sequences of alternating units behave as a third entity in these copolymers, the other two being nonalternating units of the two monomers. Unless inhibited, ionic homopolymerization of isobutylene can be appreciable, sometimes resulting in the polymer having two Tg.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120705
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  • 8
    Electronic Resource
    Electronic Resource
    Radiation-induced polymerization at high pressure of cis- and trans-1,3,3,3-tetrafluoropropene in bulk and with tetrafluoroethylenePresented in part at the 164th National Meeting of the American Chemical Society, New York, August 1972. (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 1973-1984 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radiation-induced polymerization of cis- and trans-1,3,3,3-tetrafluoropropene in bulk and with tetrafluoroethylene was studied at pressures between 5000 and 15000 atm and temperatures between 21 and 100°C. At 103 rad/hr the homopolymerization rates range from about 10-4 to 1%/hr. The activation enthalpy and volume are about 8 kcal/mole (33 kJ/mole) and -10 cm3/mole, respectively, for both isomers. The cis isomer polymerizes about twice as rapidly as the trans isomer. The latter freezes in the experimental range of temperature and pressure; the polymerization rate is very low in solid phase. Polymer intrinsic viscosities increase with polymerization pressure and decrease with polymerization temperature; the largest value obtained was 0.23 dl/g. In the copolymerizations all reactivity ratios favor incorporation of tetrafluoroethylene by factors of 6-16. The preference is stronger when the trans isomer is used.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110818
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  • 9
    Electronic Resource
    Electronic Resource
    Halobenzenes as sensitizers for the radiation-induced polymerization of styrenePresented in part at the 134th meeting of the American Chemical Society, Chicago, Ill., September 1958.This work was sponsored by the Aeronautical Research Laboratory, Wright Air Development Center, United States Air Force. (1960)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 44 (1960), S. 325-340 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Halogenated benzenes, carbon tetrachloride, and other compounds have been used to sensitize the gamma-ray-induced polymerization of styrene. Benzene and fluorobenzenes are about equally effective, while the data from solutions of mono- and dihalogenated benzenes indicate that the order of increasing sensitivity to radiation is: fluorobenzenes 〈 chlorobenzenes 〈 bromobenzenes 〈 iodobenzenes. One halogen is less effective than two, and the ortho isomers are more effective than the meta and para. The relations between the G values for radical production in the solutions and the electron fractions of solvent are linear only for benzene and the monohalogenated aromatics. With very highly halogenated benzenes and carbon tetrachloride, the departure from linearity is very marked. Significant sensitization is observed at very low electron fractions with the highly halogenated materials, except with hexafluorobenzene, which appears to be very stable to radiation. The generalizations concerning the effects of the kind and number of substituents in mono- and dihalogenated benzenes are not valid for more highly halogenated benzenes. Much of the curvature observed at high concentrations of carbon tetrachloride is apparently due to changes in the rate constants as the monomer concentration is changed. At low concentrations this is not the case with carbon tetrachloride and presumably also with the other highly halogenated materials. Various reaction mechanisms are considered, and one is advanced that reproduces many of the important features of the observed data.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1960.1204414405
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  • 10
    Electronic Resource
    Electronic Resource
    Radiation-induced polymerization of tetrafluoroethylene and 1,2,3,4,5-pentafluorostyrene at high pressurePresented at the 168th Meeting, American Chemical Society, Atlantic City, N.J., September 8-13, 1974. (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 13 (1975), S. 1677-1689 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrafluoroethylene (A) and 1,2,3,4,5-pentafluorostyrene (B) were irradiated at 15°C at autogenous pressure by use of 30-92 mole-% A and at 5000 atm by use of 42-99.9 mole-% A. The high-pressure results indicate that the reactivity ratio rA for monomer addition to A-ended radicals is 0.005; the other reactivity ratio rB appears to vary from 15 to 60 generally increasing with the A content of the charge. At autogenous pressure rA is small, but a precise determination is not possible because of the very low polymerization rate when the A content of the charge is high. However, if rA is less than 0.01, then values of rB vary from 15 to 50, again generally increasing with the A content of the charge. Mixtures of A and B exhibit positive deviations from Raoult's Law. Activity coefficients were measured at autogeneous pressure and used in an attempt to correct rB for the nonideality of solution. The range of rB was reduced only slightly to 8-27, and charges with high A contents now generally gave low values of rB; consequently, this approach was not regarded as a success. Another attempt was made to account for the apparent variation in rB by ascribing influence to the penultimate units of the radicals. Improved agreement between theoretical and observed compositions resulted, but significant discrepancies remained unexplained. Rate data agreed well with those calculated from a theoretical copolymer rate equation using values of rA and rB of 0.0045 and 40, respectively. The equation predicts an almost proportional decrease in rate with increasing proportions of A in the charge from 0 to 99 mole-% A.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.170130718
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