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  • 1
    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: An Folien (Dicke 100 pm) aus isotaktischem Polypropylen mit verschiedenen Antioxidansgehalten (0,0% bis 0,1%) wird die thermooxidative Alterunq mit der isothermen Langzeit-Differential-Thermo-Analyse (ILDTA) bis zu Temperaturen weit unter dem Kristallitschmelzbereich verfolqt und die Messwerte mit Ergebnissen aus dem Zeitstand-Zugversuch korreliert. Dabei zeigt sich, daß aus Messunqen mit der ILDTA bereits vor Einsetzen der autokatalytischen Zersetzunq sreaktion Ruckschlüsse auf die thermische Vorqeschichte der Proben und Aussagen auf das rnit einem Abfall der mechanischen Eigenschaften verbundene Ende der thermo-oxidativen Stabilität des Polymeren getroffen werden können.Weiters bietet die ILDTA die Moglichkeit, durch den direkten Zusamenhang zwischen Oxidationszeit und Antioxidansögehalt die örtliche Stabilisatorverteilung in Platten und in Folien zu bestimmen und damit Diffusionsvorqange zu verfolgen.
    Notes: Thermo-oxidative ageing processes were investigated in films (100 μm thick) made from isotactic polypropylene with different antioxidant concentrations between 0% and 0.1% using isothermal long-term differential thermal analysis (ILDTA). The end of the oven life of polypropylene coincided with the loss of mechanical properties which was confirmed by tensile tests at temperatures far below the crystallite melting range. Already prior to the beginning of autocatalytic decomposition, ILDTA experiments permits conclusions to be drawn on the thermal history of the specimens and statements made regarding the end of thermo-oxidative stability of the polymer, which is accompanied by a deterioration in the mechanical properties.In consequence of the correlation between oxidation time and antioxidant concentration the local antioxidant concentration in sheets or films can be measured by ILDTA. Thus, investigating the diffusion of an antioxidant in polypropylene using ILDTA is possible.
    Additional Material: 9 Ill.
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  • 2
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of the carbocyanine dye Stains-all with the Ca2+-binding proteins calmodulin, troponin C, and parvalbumin has been monitored by means of absorption spectra and CD. In the absence of Ca2+, complexes with Stains-all of all three proteins exhibit at high dye: protein mole ratios an intense J absorption band at 600-650 nm, which is associated with a characteristic CD spectrum. In the cases of calmodulin and troponin C, the J-band is progressively lost as the dye: protein ratio decreases and is replaced by bands of the γ and β types at 450-550 nm, which likewise give rise to characteristic CD spectra. For parvalbumin, only the J-band is observed; its intensity is undiminished at the lowest dye: protein ratios examined. In the presence of excess Ca2+ the J-band is lost for all three proteins. For calmodulin and troponin C it is replaced by σ- and β-bands; in the case of parvalbumin the bound dye is released. A tentative model has been proposed to account for these observations.
    Additional Material: 11 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 365-369 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New Access to 2,6,6-Trimethylcyclohexa-2,4-dienone from 4-Oxoisophorone2,6,6-Trimethylcyclohexa-2,4-dienone (1), a versatile starting material for the preparation of some carotenoids and several natural products, was efficiently (73% yield) prepared from oxoisophorone 3. After conversion of 3 to the alcohol 4 or the acetate 5, H2O was eliminated (4→1) under acidic distillative conditions, whereas AcOH could be eliminated (5→l) under Pd(O) catalysis.
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  • 4
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Complexes with Biologically Important Ligands, XLIV. - Platinum(II) and Palladium(II) as Amino Protecting Groups. Metal Complexes with Silyl Esters and Acid Chlorides as Ligands and Peptide Synthesis at the ComplexThe cleavage of the chelate ring of platinum(II) and palladium(II) glycinate, cis-, trans-M(NH2CH2COO)2 (M = Pt, Pd), by trialkylchlorosilanes results in the formation of the complexes cis-, trans-MCl2(NH2CH2CO2SiR3)2 (1). Treatment of 1 or of cis-, trans-MCl2(NH2CHRCO2H)2, respectively, with oxalyl chloride and DMF gives the α-amino acid chloride complexes cis-, trans-MCl2(NH2CHRCOCl)2 (2) from which - using N-(trimethylsilyl)-α-amino acid esters - a series of dipeptide complexes cis-, trans-MCl2(dipeptideOR)2 (R = H, alkyl, SiMe3) (3) has been obtained. trans-Palladium complexes of type 3 and of type cis-Pd-Cl2(HisNHCHRCO2Et) (4) are also formed form the corresponding α-amino acid complexes and α-amino acid ester with a watersoluble carbodiimide.
    Notes: Der Chelatring von Platin(II)- und Palladium(II)-glycinat, cis-, trans-M(NH2CH2COO)2 (M = Pt, Pd), läßt sich mit Trialkylchlorsilanen unter Bildung der Dichlorobis(glycin-silylester)-Komplexe, cis-, trans-MCl2(NH2CH2CO2SiR3)2 (1), öffnen. Aus 1 oder den Komplexen MCl2(NH2CHRCO2H)2 werden mit Oxalylchlorid und DMF die α-Aminosäurechlorid-Verbindungen cis-, trans-MCl2(NH2CHRCOCl)2 (2) erhalten, welche mit N-(Trimethylsilyl)-α-aminosäureestern die Dipeptid-Komplexe cis-, trans-MCl2(DipeptidOR)2 (R = H, Alkyl, SiMe2) (3) liefern. trans-Palladium-Komplexe vom Typ 3 und vom Typ cis-PdCl2(His-NHCHRCO2Et) (4) entstehen auch aus den entsprechenden α-Aminosäure-Komplexen und dem α-Aminosäureester mit einem wasserlöslichen Carbodiimid.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 1759-1765 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Complexes with Biologically Important Ligands, XLVII1). Copper, Nickel, Palladium, and Platinum(II) Complexes of C-Allylglycine and N-(Diphenylmethylene)-C-allylglycine EsterC-Allylglycine reacts with Ni, Cu, Pd, and Pt(II) salts - dependent on pH - to give trans-N,O-bischelate complexes M[NH2CH(CH2CH=CH2CO2]2 (M = Cu, Ni, Pd) 1 or N,η2-C,C-chelate complexes Cl2MNH2CH(CO)2R)CH2CR=CH2 (R = H, Me; M = Pd, Pt). The reactions of N-(diphenylmethylene)-C-allylglycine ester with Na2PdCl4 and PtCl2 yield ortho-metallated complexes 3, in which the ligand is bound to the ortho-C(phenyl) atom, the imino-B atom, and the olefinic double bond. 2a and 3c were characterized by X-ray structure analyses.
    Notes: C-Allylglycin reagiert - abhängig vom pH-Wert - mit Ni-, Cu-, Pd- und Pt(II)-Salzen zu den trans-N,O-Bischelat-Komplexen M[NH2CH(CH2CH=CH2CO2]2 1 (M = Cu, Ni, Pd) oder zu N,η2-C,C-Chelat-Komplexen Cl2MNH2CH(CO)2R)CH2C-(R)=CH2 2 (R = H, Me; M = Pd, Pt). N-(Diphenylmethylen)-C-allylglycinester setzen sich mit Na2PdCl4 oder PtCl2 zu den ortho-metallierten Komplexen 3 um, in denen der Ligand dreizähnig über das ortho-C(Phenyl)-Atom, das Iminostickstoff-Atom und die C = C-Doppelbindung koordiniert ist. Die Molekülstrukturen von 2a und 3c wurden röntgenographisch bestimmt.
    Additional Material: 2 Ill.
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  • 6
    ISSN: 0009-2940
    Keywords: (Cyclopentadienyl)manganese complexes ; (Cyclopentadienyl)rhodium complexes ; Perhalogenocyclopentadienyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of Complexes of Perhalogenated Cyclopentadienes and Alkynes. IV. - Preparation, Reactions, and Structures of Alkylthio- and Phenylthio-Substituted (Cyclopentadienyl)manganese and -rhodium ComplexesThe syntheses and crystal structures of (C5Cl4SPh)Rh(1,5-COD) (2b), [C5Cl3(SR)2Mn](CO)3 [R = Ph (4a), Me (4b)] and [C5Cl2-(SPh)3]Mn(CO)3(5a) as well as the syntheses of [C5Cl5-x- (SBu)x]Mn(CO)3 [x = 1 (3b), 2 (4c), 3 (5b)] and the reactions of [C5Cl2(SR)3]Mn(CO)3 and [C5(SMe)5]Mn(CO)3 with PdCl2(Ph-CN)2 are described. The cyclopentadienyl ring in 2b is not planar, and the three phenyl rings of 5a are parallel to each other.
    Notes: Die Darstellung und die Kristallstrukturen von (C5Cl4SPh)Rh-(1,5-COD)(2b), [C5Cl3(SR)2Mn](CO)3 [R = Ph (4a), Me (4b)] und [C5Cl2(SPh)3]Mn(CO)3 (5a) sowie die Darstellung von [C5Cl5-x (SBu)x]Mn(CO)3 [x = 1 (3b), 2 (4c), 3 (5b)], ferner Reaktionen von [C5Cl2(SR)3]Mn(CO)3 und [C5(SMe)5]Mn(CO)3 mit PdCl2-(PhCN)2 werden beschrieben. In 2b ist der Cyclopentadienylring nicht planar, und in 5a stehen die drei Phenylringe nahezu parallel.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 32 (1988), S. 853-865 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The adsorption of cellulase from Trichoderma reesei MCG 77 on Avicel was measured at varying cellulase (2-8 g/L) and Avicel (10-200 g/L) concentrations at pH 4.8 and 50°C. Different mathematical equations were derived for the evaluation of the experimental data. The fraction of cellulase protein that can maximally be adsorbed is 0.96, and 1 g Avicel can bind maximally 0.092 g cellulase protein. The Michaelis constant for the adsorption equilibrium [cellulase] + [Avicel] ⇌ [cellulase Avicel] complex is between 2.0 and 2.3 · 10-5 mol/L. This value is based on the assumption that cellulase has an average molecular weight of 48.000. The apparent molecular weight of Avicel, i.e., that amount in grams that can bind 1 mol cellulase, is 520,000. Under maximum binding the enzyme covers on Avicel a surface of 42 m2/g, and the occupied volume is 0.186 cm3/g Avicel.
    Additional Material: 14 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 1221-1234 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The relationship among extent of hydrolysis, reaction time, and enzyme dosage was investigated. For this, Sigmacell 50 and pretreated poplar wood (20 g/L) was hydrolyzed with varying dosages of cellulases from three different sources (5 to 100 FPU/g) for time periods ranging from 2 to 94 h. It was found that the formation of glucose can be described by summation of two parallel first order reactions. The extent of hydrolysis at fixed time increases with increasing enzyme dosage in a hyperbolic function. From the empirical data it is possible to calculate the fractions of easily and difficult hydrolyzable cellulose and the digestability which could maximally be obtained at infinite enzyme loadings. In the system Sigmacell 50 and Celluclast the easily and difficult hydrolyzable components are 43.0 and 57.0%, respectively, and the maximum digestability at 94 h is 82.6%. Poplar wood, steam treated at 200°, 220°, and 240°C, showed with Celluclast at 24 h a maximum digestability (weight percentage of wood degraded to glucose) of 43.9, 64.9, and 68.0%. The relationships derived from experimental data allow one to compare objectively the effectiveness of different cellulase enzymes and different pretreatments.
    Additional Material: 11 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 30 (1987), S. 169-178 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A wild strain of schizophyllum commune (Fr:Fr:) isolated in Bangladesh produced cellulase and xyianase in high yields as well as the exobiopolymer schizophyllan. It was found experimentally that concentrations of 4% Avicel, 3.5% peptone, and 0.5% Ca(NO3)2·4H2O were optimal for growth and product formation. Bacto-peptone was found to be the most suitable substrate of a number of casein, mycological, and meat peptone preparations for enzyme production. Young plate-culture inocula (4 days) were found to be better than comparatively aged fungal cultures (14 days). With the optimized medium, 5 units filter paper (FP) cellulase, 1244 units xylanase, 108 units β-glucosidase, and 65 units of carboxymethyl (CM) cellulase per mL culture filtrate were obtained in shake flasks. In a laboratory fermentor the respective enzyme activities were 4.5 units FP-cellulase, 1200 units xylanase, 100 units β-glucosidase, and 60 units CM-cellulase per mL culture filtrate. A biopolymer, reported to be active against can cerous cells, was an additional product in addition to the enzymes.
    Additional Material: 12 Ill.
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  • 10
    ISSN: 0935-6304
    Keywords: Solvents and GC detectors ; Coupled HPLC-GC ; Column effluent splitter ; Di-(2-ethylhexyl) phthalate ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Introduction of solutions of up to several milliliters by on-column injection of large volumes or by coupled HPLC-GC may cause problems with GC detectors (FID, AFID, MS). For instance, dichloromethane forms large amounts of hydrochloric acid and carbon black in FIDs.A column effluent splitter was developed for keeping the major portion of the solvent vapors away from the detector; approximately 99% of the vapor is vented while the remaining 1% of vapor is used for detecting the widths of the solvent peaks. During analysis, the split ratio is reversed by a strong increase of the resistance to the gas flow through the split exit line.The system was used for the determination of di-(2-ethylhexyl)-phthalate (DEHP) in triglyceride matrices of various foods. Direct determination by HPLC is not sufficiently sensitive, whereas direct analysis by GC is hindered by the triglycerides. Solutions of fats or oils were pre-separated on a silica column using dichloro-methanelcyclohexane 1:l with addition of 0.05 % acetonitrile as eluent. The HPLC fraction containing the DEHP was transferred to GC through a loop-type interface using concurrent solvent evaporation. Detection limits were around 0.1 ppm.
    Additional Material: 4 Ill.
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