摘要:

AbstractThe matrix polymerisation of poly(vinylacetate) was investigated. Using scanning electron microscopy and gel permeation chromatography, the morphology and molecular weight distribution of poly(vinylacetate) were determined. The experimental data prove the matrix influence upon the molecular and morphological characteristics of poly(vinylacetate) thus obtained.

ISSN:0007-1641    

DOI:10.1002/pi.4980150302

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractCyanogen bromide activated agarose is widely employed as the water‐insoluble matrix in immunoadsorption and affinity chromatography for the immobilisation of proteins. A reaction mechanism is presented for the cyanogen bromide activation of the galactan, agarose, the coupling of model amines to the activated carbohydrate matrix and the detachment of ligands. Dansyl (Dns) derivatisation of the acid hydrolysed and unhydrolysed amine derivatives resulting from the reaction of cyanogen bromide‐activated Sepharose® andN‐α‐acetyl‐L‐ornithine reveal the production of arginine, indicating that the amine‐Sepharose conjugate is anO‐substituted isourea. Thin layer chromatography of the Dns‐derivatised unhydrolysed filtrate from the reaction indicated the formation of several derivatives which suggest that the isourea bonds can be cleaved by the solvolytic attack of nucleophiles in the pH range 8–9.5. Nucleophilic attack by amino groups on the amine‐Sepharose conjugates releasesN‐monosubstituted guanidine,N1,N2disubstituted ornith

ISSN:0007-1641    

DOI:10.1002/pi.4980150303

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractUsing commercially available artificial substrates, a number of lysosomal‘acid’ hydrolases in plasma, leucocytes and cultured skin fibroblasts from normal individuals, controls and patients with inborn errors of metabolism affecting lysosomal enzymes have been investigated. The pH optima, Kmvalues and temperature‐activity profiles are reported, but some of the physiochemical parameters of the catalytic properties of the normal enzymes are not those that would be expected for mammalian system. Temperature optima of α‐L‐fucosidase, α‐L‐iduronidase, sphingomyelinase and β‐D‐glucuronidase were different in different sources and differences were seen in different enzymes from the same source. Only sphingomyelinase in leucocytes and α‐L‐iduronidase in leucocytes and fibro‐blasts showed maximum activity at 37°C, with other enzymes showing an unusually high optimum of 50°C or greater. Lysosomal enzymes from patients with inborn errors of metabolism showed maximum activity at the same temperature as observed in normal individuals with the exception of α‐L‐fucosidase, β‐D‐glucuronidase and α‐N‐acetyle‐D‐glucosaminidase in plasma from a patient with mucolipidosis II and β‐D‐glucuronidase in plasm

ISSN:0007-1641    

DOI:10.1002/pi.4980150304

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractUltrasonic attenuation and velocity measurements are reported at 2MHz over a temperature range from 293 to 353K for mixtures of polyethylene oxide and water for concentrations from 0 to 100%. The ultrasonic attenuation in the mixtures was observed to be lower than that in the ideal solution. This implies that the structural distribution in the system is changing with concentration. Studies of the compressibility of water indicate the existence of a minimum at approximately 343K. Introduction of polyethylene oxide leads to a shift of the minimum to lower temperature. These data are interpreted in terms of changes in the structure of water and the interaction of the polymer with water.

ISSN:0007-1641    

DOI:10.1002/pi.4980150305

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractA systematic dielectric study over the frequency region from 0.06 to 300kHz has been carried out on butyl rubber loaded with one of six white fillers namely talc, calcium carbonate, dolomite, barytes, kaolin and silica in increasing quantities at room temperature. A low frequency loss term whose maximum lies around 104Hz for all samples is noticed and is attributed to Maxwell‐Wagner losses arising from the interfacial polarisation due to the presence of the ingredients added stepwise to raw rubber. These losses are found to increase by the addition of filler and the cause of this increase is interprete

ISSN:0007-1641    

DOI:10.1002/pi.4980150306

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980150301

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY