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  • 11
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Company
    Nature biotechnology 5 (1987), S. 157-160 
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] Escherichia coli cells transformed with the expression plasmid pLlec9 synthesize leucoagglutinating phytohemagglutinin (PHA–L) encoded by a nuclear gene of Phaseolus vulgaris. Pure, unglycosylated PHA–L can be isolated by affinity chromatography from lysates of these bacteria. The E. ...
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Cell biology and toxicology 4 (1988), S. 357-370 
    ISSN: 1573-6822
    Keywords: 3-aryloctahydroindolizine ; chromosome aberration ; DNA repair ; genotoxicity ; mutagenicity ; nonopiate analgesic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: McN-5195, (±)trans-3-(2-bromophenyl)octahydroindolizine, a novel analgesic, was tested for genotoxic potential in a battery of tests with endpoints of mutagenicity, chromosomal alterations and DNA damage/ repair. McN-5195 was not mutagenic when tested in the Ames test using strains TA98, TA100, TA1535, TA1537 and TA 1538, in the absence of metabolic activation and in the presence of Aroclor 1254-induced rat or hamster S-9. Negative results were also obtained in the mouse lymphoma assay in the absence of activation, but reproducible mutagenic responses were seen in this mammalian cell assay in the presence of rat S-9 at high levels of induced toxicity (reduced cell growth). Testing of the enantiomers of McN-5195 in this assay supported these findings. A predominance of small mutant colonies in the mouse lymphoma assay suggested a potential chromosomal effect of McN-5195. This was confirmed with positive findings in an in vitro cytogenetics assay using CHO cells, again at toxic exposure levels and only in the presence of S-9. McN-5195 did not induce DNA repair in the primary rat hepatocyte/DNA repair assay, nor did it induce alterations in vivo of chromosome structure or number when tested in a rat bone marrow cytogenetics assay. The findings from this battery of tests indicate that McN-5195 has modest genotoxic activity when tested in the presence of rat liver S-9 in in vitro systems sensitive to cytogenetic change. The absence of genotoxicity in vitro in Salmonella and intact liver cells and in vivo in rat bone marrow suggests that McN-5195 is unlikely to present a genotoxic risk to whole animals.
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  • 13
    ISSN: 1572-8900
    Keywords: Cellulose ester ; aliphatic polyester ; composting ; biodegradation ; blends
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A series of miscible blends consisting of cellulose acetate propionate (CAP) and poly(ethylene glutarate) (PEG) or poly(tetramethylene glutarate) (PTG) were evaluated in a static bench-scale simulated municipal compost environment. Samples were removed from the compost at different intervals, and the weight loss was determined before evaluation by gel permeation chromatography, scanning electron microscopy, and1H NMR. The type of polyester (PEG versus PTG) in the blend made no difference in composting rates. At fixed CAP degree of substitution (DS), when the content of polyester in the blend was increased, the rate of composting and the weight loss due to composting increased. When the CAP was highly substituted, little degradation was observed within 30 days and almost all of the weight loss was ascribed to loss of polyester. Although the polyester was still observed to degrade faster, when the CAP DS was below approximately 2.0, both components are observed to degrade. The data suggests that initial degradation of the polyester is by chemical hydrolysis and the rate of this hydrolysis is very dependent upon the temperature profile of the compost and upon the DS of the CAP.
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  • 14
    ISSN: 1573-5028
    Keywords: glycosylation ; immunocytochemistry ; modified storage protein ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro mutagenesis was used to supplement the sulfur amino acid codon content of a gene encoding β-phaseolin, a Phaseolus vulgaris storage protein. The number of methionine codons in the phaseolin gene was increased from three to nine by insertion of a 45 base pair (bp) synthetic duplex. Either modified or normal phaseolin genes were integrated into the genome of tobacco plants through Agrobacterium tumefaciens-mediated transformation. Although similar levels of phaseolin RNA are detected in seeds of plants transformed with either the normal or modified (himet) gene, the quantity of himet protein is consistently much lower than normal β-phaseolin. Himet phaseolin is expressed in a temporal- and organ-specific fashion, and is N-glycosylated and assembled into trimers in the manner of normal phaseolin. After germination, both types of phaseolin are hydrolyzed, but the himet protein is more quickly degraded. Electron microscopic immunocytochemical observations of developing seeds indicate that the himet protein is primarily localized in the endoplasmic reticulum (ER) and in Golgi apparatus secretion vesicles. Himet phaseolin is absent from protein storage vacuoles, termed protein bodies, where normal phaseolin is deposited in transgenic tobacco. We interpret the immunocytochemical data to indicate that himet phasolin is transported through the ER and Golgi apparatus and is then degraded in Golgi secretion vesicles or the protein bodies.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Order 3 (1986), S. 269-281 
    ISSN: 1572-9273
    Keywords: 05C75 ; 05C99 ; 06A10 ; Poset ; subposet ; m-subposet ; upper bound graph ; graph ; subgraph ; induced subgraph ; digraph
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Competition graphs of transitive acyclic digraphs are strict upper bound graphs. This paper characterizes those posets, which can be considered transitive acyclic digraphs, which have upper bound graphs that are interval graphs. The results proved here may shed some light on the open question of those digraphs which have interval competition graphs.
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  • 16
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 344-350 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction in acetonitrile solution of (Z)-O-methylbenzohydroximol chlorides [ArC (Cl)=NOCH3] with morpholine, pyrrolidine and azetidine gives the corresponding (Z)-amidoximes [ArC(NR1R2)=NOCH3] in acetonitrile. The rates of these reactions were measured under pseudo-first-order conditions (excess amine). The reactions were found to follow overall second-order kinetics (first order in amine). The Hammett ρ-value (with σ) for the reaction with pyrrolidine is +0·92. The reaction of the p-nitro compound with pyrrolidine gives a significant element effect [k(p-nitrobenzohydroximoyl bromide)/k(p)-nitrobenzohydroximoyl chloride = 10]. A Brφonsted β-value of 0·38 was estimated from the reactions of morpholine and piperidine with the p-nitrohydroximoyl chloride. The slower reaction of (E)-O-methyl-p-nitrobenzohydroximoyl chloride with azetidine gives primarily the (E)-amidoxime (E:Z ≈ 98:2) This reaction also follows second-order kinetics. The kinetic observations made in this study are compared with the corresponding results obtained in earlier work in benzene solution. It is suggested that in acetonitrile solution the reactions proceed by an addition-elimination mechanism with rate-determining loss of chloride ion (AN + DN#). It is further suggested that acetonitrile is assisting in the breakdown of the tetrahedral intermediates formed in these reactions.
    Additional Material: 3 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 1 (1988), S. 103-114 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of solvent additives on the course of TiO2 photocatalyzed oxygenation of α-methylstyrene has been studied. While the addition of small amounts of nonhalogenated alcohols to TiO2 powders suspended in acetonitrile was found to decrease the rate of photooxygenation, added halogenated alcohols increase the rate of reaction. In addition, the solvent additives affect the observed product distribution.
    Additional Material: 4 Tab.
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  • 18
    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 compatibility of poly(vinylchloride PVC) with post-chlorinated PVC (CPVC) is investigated with the purpose of relating the mechanical properties of such blends with their compatibility. The effects on compatibility of varying mixing methods, blend composition, molecular weights of components, and chlorine content of CPVC are studied. Experimental methods include comparison of the glass transition temperatures (Tgs) of blends and homopolymers using dynamic mechanical analysis, Differential Scanning Calorimetry (DSC), and comparison of the mechanical properties of blends and homopolymers. Experimental results indicate marginal compatibility between PVC and CPVC. Blends in which CPVC is the main component are indicated to be less compatible than other compositions.
    Additional Material: 16 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 36 (1997), S. 441-453 
    ISSN: 0021-9304
    Keywords: composite ; bone cement ; flexure ; fracture toughness ; gamma irradiation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Loosening remains an impediment to the long-term success of total hip replacements despite numerous improvements in the materials used. In cemented prostheses, fatigue and fracture of bone cement have been implicated in the failure of these devices. A new material, self-reinforced composite poly(methyl methacrylate) (SRC-PMMA), has been developed. SRC-PMMA is formed by a novel processing method that will be described. The composite consists of high strength, highly oriented PMMA fibers embedded in a matrix of PMMA. Using a woven form of SRC-PMMA, an in vitro physical and mechanical evaluation was performed to assess the feasibility of its use in an orthopedic prosthesis. Three different weaves of SRC-PMMA were evaluated in bending and fracture toughness in air, after immersion for 30 days in 37°C saline, and after gamma irradiation followed by immersion. Bending modulus and strength were decreased by gamma irradiation followed by saline immersion. The effect of saline immersion alone on bending strength and modulus was negligible. Saline immersion and gamma irradiation followed by saline immersion was shown to have little or no effect on the fracture toughness of woven SRC-PMMA. Differences in the fracture processes of the different weaves were found and can be related to the differing orientation of fibers to the fracture toughness pre-crack. Optimally incorporated SRC-PMMA absorbs the same amount of water as bone cement. Comparison to previous and current work with bone cement controls shows that SRC-PMMA is a material equal to or better than bone cement in all tests performed. It deserves further consideration as a candidate biomaterial. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 36, 441-453, 1997.
    Additional Material: 16 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 43 (1998), S. 153-161 
    ISSN: 0021-9304
    Keywords: bone cement ; composite ; self-reinforced composite ; interfacial properties ; poly(methyl methacrylate) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Total joint prostheses are often fixed in the bone using bone cement. The cement mantle, however, is prone to fatigue fracture that can lead to failure of the mantle, evolution of bone cement particles, and eventual loosening and failure of the prosthesis. A new material, self-reinforced composite poly(methyl methacrylate) (SRC-PMMA) was developed previously by the authors. This material has a similar chemical composition to bone cement, with the matrix and reinforcing fibers both fabricated from PMMA. One potential use for this material is as a precoat for hip prostheses or other stemmed prostheses. This study sought to examine the strength of the bonds that SRC-PMMA forms with simulated prostheses and bone cement. SRC-PMMA was woven about Co-Cr rods and push out tests were performed. Samples were tested in air as processed or after immersion in saline for 30 days at 37 °C. Three different weaves were investigated and compared to bone cement. Bone cement and SRC-PMMA formed interfacial bonds with Co-Cr rods that failed at an average load (stress) of 980 N (2.0 MPa). After saline immersion, the bone cement's interfacial bond strength was 642 N (1.23 MPa) and the tight weave SRC-PMMA was statistically stronger at 973 N (1.86 MPa). The shear strength within bone cement alone as measured by push out tests was an order of magnitude higher at 9210 N (15.2 MPa) in air and 9900 N (15.7 MPa) after saline immersion. The bond between SRC-PMMA and bone cement was 10900 N (17.9 MPa) in air and 9610 N (15.8 MPa) after immersion in saline. Woven SRC-PMMA performed as well or better than bone cement in these push out tests. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 43: 153-161, 1998
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