bluuebunny/crossref_metadata_2025 huggingface dataset:
Primary intraosseous meningioma in a skull of the medieval period of Southwestern Germany
Authors: Weber Jochen , Czarnetzki Alfred
Published: December 2002

Primary intraosseous calvarial meningiomas are very rare entities in recent times. We present the first case in antiquity of a primary intraosseous meningioma in the frontoparietal bone associated with the coronal suture, and discuss its pathology. The skull derives from southwestern Germany and is dated to the 12th–14th centuries AD. The lesion is interpreted as a solitary osteoblastic neoplasm with hyperostosis on the outside, and osteolysis and radial spiculation in the central part of the lesion with an area of irregularity along the inner table. In cases of solitary osteoblastic skull lesions the differential diagnosis comprises: fibrous dysplasia, osteoma, osteoblastic metastasis, Pagets disease and meningioma with sheet‐like growth along the dural surface with marked hyperostosis (called meningioma en plaque). We believe that a differentiation between hyperostotic meningioma en plaque and intraosseous meningioma cannot be made in skulls from antiquity. Copyright © 2002 John Wiley & Sons, Ltd.
Confirmation of the presence of Mycobacterium tuberculosis complex‐specific DNA in three archaeological specimens
Authors: Spigelman Mark , Matheson Carney , Lev Galit , Greenblatt Charles , Donoghue Helen D.
Published: December 2002

This journal published the first reported identification of Mycobacterium tuberculosis complex (MTB) DNA in ancient human remains but concerns were raised about the article two years after publication. These were based on methodology which, in the field of ancient DNA, was still developing. Here we present a re‐examination of the 1993 research conducted on three specimens which exhibited palaeopathologies indicative of tuberculosis. The specimens were: an ulna from pre‐European‐contact Borneo, a spine from Byzantine Turkey, and a lumbar‐sacral spine from 17th century Scotland. There was insufficient material to permit re‐examination of all of the original samples. The earlier results were confirmed in two independent laboratories using different methodologies. MTB DNA complex‐specific DNA amplicons were obtained, and sequenced in both laboratories, in a re‐analysis of samples which supported the earlier findings. Copyright © 2002 John Wiley & Sons, Ltd.
Bone remodelling following a lower leg fracture in the 11,000‐year‐old hunter‐gatherer from Vado all' Arancio (Italy)
Authors: Holt B. M. , Fornaciari G. , Formicola V.
Published: December 2002

The Upper Palaeolithic skeleton from Vado all'Arancio (Italy), dated to about 11,330 BP, exhibits a severe ankle fracture healed with residual deformation. Following recovery, this young hunter‐gatherer continued to walk for an extended period of time, albeit in a mechanically altered manner. While right‐left differences in external lower limb bone measurements are relatively low, biomechanical analysis of femur and tibia indicates unusually pronounced asymmetry in all cross‐sectional measures of diaphyseal strength. Asymmetry results primarily from normal side endosteal hypertrophy, and not from hypotrophy of the injured limb, suggesting that this individual resumed active life following recovery. This pattern of asymmetry underscores the role of physical activity in maintaining bone mass. Copyright © 2002 John Wiley & Sons, Ltd.
Sub‐micron spongiform porosity is the major ultra‐structural alteration occurring in archaeological bone
Authors: Turner‐Walker G. , Nielsen‐Marsh C. M. , Syversen U. , Kars H. , Collins M. J.
Published: December 2002

Total pore volume and pore size distribution are indicators of the degree of post‐mortem modification of bone. Direct measurements of pore size distribution in archaeological bones using mercury intrusion porosimetry (HgIP) and back scattered scanning electron microscopy (BSE‐SEM) reveal a common pattern in the changes seen in degraded bone as compared to modern samples. The estimates of pore size distribution from HgIP and direct measurement from the BSE‐SEM images show remarkable correspondence. The coupling of these two independent approaches has allowed the diagenetic porosity changes in human archaeological bone in the >0.01 µm range to be directly imaged, and their relationship to pre‐existing physiological pores to be explored. The increase in porosity in the archaeological bones is restricted to two discrete pore ranges. The smaller of these two ranges (0.007–0.1 µm) lies in the range of the collagen fibril (0.1 µm diameter) and is presumably formed by the loss of collagen, whereas the larger pore size distribution is evidence of direct microbial alteration of the bone. HgIP has great potential for the characterization of microbial and chemical alteration of bone. Copyright © 2002 John Wiley & Sons, Ltd.
A case of ‘butterfly’ vertebra from Sardinia
Authors: Brasili Patricia , Bonfiglioli Benedetta , Ventrella Angela R.
Published: December 2002

We describe a rare congenital malformation of the spine known as ‘butterfly’ vertebra, which is classified as a congenital developmental anomaly in the early embryonic period, resulting in a sagittally cleft vertebral body. In our case, the anomaly affects an adult female and involves the fifth lumbar vertebra and first sacral vertebra; it is not associated with other anomalies of the spine. Copyright © 2002 John Wiley & Sons, Ltd.
An identification key for dermal denticles of Rajidae from the North Sea
Authors: Gravendeel Ronald , Van Neer Wim , Brinkhuizen Dick
Published: December 2002

As a result of more systematic fine sieving on archaeological sites, dermal denticles and isolated teeth of rays are now more frequently recovered than before. A detailed description of the teeth is available in the literature, but no comparative study of the morphology of the dermal denticles exists that allows the identification of such elements issued from archaeological sites. A key and illustrations are provided for the identification of the dermal denticles of 10 ray species from the North Sea. In addition, the ray denticles have been analysed from seven medieval and postmedieval sites showing their potential for the interpretation of ichthyo‐archaeological assemblages. Copyright © 2002 John Wiley & Sons, Ltd.
Infant osteosarcoma
Authors: Alt K. W. , Adler C. P. , Buitrago‐Téllez C. H. , Lohrke B.
Published: December 2002

Malignant tumours have long been thought to be rare in prehistoric skeletal samples. Numerous recent findings have contradicted this view. Well‐documented cases are of great importance in palaeopathological research. We report a malignant tumour in a medieval skeleton (Sulzburg, southwest Germany) of a child, briefly review palaeopathological research on tumours and include clinical description of the illness. The macroscopic and radiological results leave no doubt about the validity of the diagnosis of osteosarcoma. The osteosarcoma had attacked the proximal femur and extensively invaded the soft tissues. The histological appearance of the tumour is typical of osteosarcoma. Diagnosis, differential diagnoses, the possible aetiology of the tumour and the fate of the afflicted individual are discussed. It is possible that the development of this osteosarcoma was affected by the proximity of the community to a lead‐silver mine. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and properties of some novel, soluble and light‐coloured, aromatic poly(amide–imide) copolymers
Authors: Yang Chin‐Ping , Chen Ruei‐Shin , Wei Chi‐Shu
Published: December 2002

A new type of tetraimide‐dicarboxylic acid (I) was synthesized starting from the ring‐opening addition of m‐aminobenzoic acid (m‐ABA), 4,4′‐oxydiphthalic anhydride (ODPA) and 4,4′‐methylenedianiline (MDA) at a 2:2:1 molar ratio in N‐methyl‐2‐pyrrolidone (NMP), followed by cyclodehydration to the diacid I. A series of soluble and light‐coloured poly(amide–imide–imide)s (IIIa–j) was prepared by triphenyl phosphite‐activated polycondensation from the tetraimide‐diacid I with various aromatic diamines (IIa–j). All films cast from DMAc had cutoff wavelengths shorter than 400 nm (376–393 nm) and had b* values between 20.46 and 40.67; these polymers were much lighter in colour than those of the corresponding trimellitimide series. All polymers were readily soluble in a variety of organic solvents such as NMP, N,N‐dimethylacetamide, dimethyl sulfoxide, and even in the less polar m‐cresol and pyridine. Compared with those of corresponding ODPA–MDA polyimide, the solubilities of poly(amide–imide–imide)s IIIa–j were greatly improved. Polymers IIIa–j afforded tough, transparent, and flexible films, which had tensile strengths ranging from 82 to 105 MPa, elongations at break from 8 to 14%, and initial moduli from 2.0 to 2.2 GPa. The glass transition temperature of polymers were recorded at 255–288 °C. They had 10% weight loss at a temperature above 540 °C and left more than 60% residue even at 800 °C in nitrogen.

© 2002 Society of Chemical Industry
Synthesis of diblock and triblock copolymers containing dendrons via ‘living’ controlled radical polymerization
Authors: Zhao You‐Liang , Jiang Jing , Chen Chuan‐Fu , Xi Fu
Published: December 2002

The dendritic Fréchet‐type polyarylether 2‐bromoisobutyrates (Gn‐Br, n = 1–3) as macroinitiators for the ‘living’/controlled radical polymerization of styrene (St) and methyl methacrylate (MMA) were investigated. The atom transfer radical polymerization of St and MMA carried out with CuBr/bpy (2,2′‐bipyridine) catalyst in bulk yielded well‐defined dendritic–linear diblock copolymers (Gn–PSt and Gn–PMMA). The use of G3–PSt for the block copolymerization of MMA and G3–PMMA for the chain extension polymerization of MMA in the presence of CuBr/bpy catalyst is also described. The triblock copolymers obtained were of predetermined molecular weights and relatively low polydispersities, which indicates the living nature of the reaction system.

© 2002 Society of Chemical Industry
Poly(ethylene‐co‐vinyl acetate)‐graft‐poly(methyl methacrylate) (EVA‐graft‐PMMA) as a modifier of epoxy resins
Authors: García Filiberto González , Soares Bluma G , Williams Roberto J J
Published: December 2002

Conventional approaches to toughen thermosets are: (1) the polymerization‐induced phase separation of a rubber or a thermoplastic, or (2) the use of a dispersion of preformed particles in the initial formulation. In the present study it is shown that it is possible to combine both techniques by using graft copolymers with one of the blocks being initially immiscible and the other that phase separates during polymerization. This is illustrated by the use of poly(ethylene‐co‐vinyl acetate)‐graft‐poly(methyl methacrylate) (EVA‐graft‐PMMA) as modifier of an epoxy resin. EVA is initially immiscible and PMMA phase separates during polymerization. Blends of an epoxy monomer based on diglycidylether of bisphenol A (DGEBA, 100 parts by weight), piperidine (5 parts by weight), and PMMA (5 parts by weight), showed the typical polymerization‐induced phase separation of PMMA‐rich domains before gelation of the epoxy network. Replacing PMMA by EVA‐graft‐PMMA (5 parts by weight), yielded stable dispersions of EVA blocks, favoured by the initial solubility of PMMA blocks. Phase separation of PMMA blocks in the course of polymerization led to a dispersion of in situ generated biphasic particles (plausibly composed of EVA cores surrounded by PMMA shells), with average diameters varying from 0.3 to 0.6 µm with the cure temperature. This procedure may be used to generate stable dispersions of biphasic particles for toughening purposes.

© 2002 Society of Chemical Industry
Preparation and characterization of star polymers with polyurethane cores using polycaprolactone triol
Authors: Wang Tzong‐Liu , Huang Fang‐Jung , Lee Swu‐Wen
Published: December 2002

Star‐shaped polymers with two different core sizes were prepared by step polymerization. Their structures were confirmed by FTIR and 1H NMR studies. X‐ray diffraction studies showed highly crystallized patterns for this type of star polymer. Thermogravimetric analysis curves displayed an excellent thermal stability and a two‐step degradation mechanism for these materials. In addition, it indicated that if the length of the triol segment were longer, the degradation temperature at 10% weight loss would be higher.

© 2002 Society of Chemical Industry
Characterization of cure reactions of anhydride/epoxy/polyetherimide blends
Authors: Kim Minyoung , Kim Wonho , Choe Youngson , Park Joung‐Man , Park In‐Seo
Published: December 2002

The cure kinetics of blends of epoxy (diglycidyl ether of bisphenol A)/anhydride (nadic methyl anhydride) resin with polyetherimide (PEI) were studied using differential scanning calorimetry under isothermal conditions to determine the reaction parameters such as activation energy and reaction constants. By increasing the amount of PEI in the blends, the final cure conversion was decreased. Lower values of final cure conversions in the epoxy/PEI blends indicate that PEI hinders the cure reaction between the epoxy and the curing agent. The value of the reaction order, m, for the initial autocatalytic reaction was not affected by blending PEI with epoxy resin, and the value was approximately 1.0. The value of n for the nth order component in the autocatalytic analysis was increased by increasing the amount of PEI in the blends, and the value increased from 1.6 to 4.0. A diffusion‐controlled reaction was observed as the cure conversion increased and the rate equation was successfully analyzed by incorporating the diffusion control term for the epoxy/anhydride/PEI blends. Complete miscibility was observed in the uncured blends of epoxy/PEI at elevated temperatures up to 120 °C, but phase separations occurred in the early stages of the curing process.

© 2002 Society of Chemical Industry
Biologically active polymer: controlled‐release formulations based on Hymexazol
Authors: Tai Limin , Liu Dongxue , Shen Yongjia , Si Naiguo
Published: December 2002

3‐(2‐Hydroxyethoxy)‐5‐methylisoxazole (2) was prepared by the reaction of 3‐hydroxy‐5‐methylisoxazole (1) with 2‐ethylene chlorohydrin. It reacted with methacryloyl chloride to afford 2‐[3‐(5‐methylisoxazolyl)oxy]ethyl methacrylate (4). The compounds 2 and 4 were confirmed structurally by IR, MASS and 1H NMR spectroscopy and MS. The fungicidal effects of 2 and 4 were investigated. Compound 4 was subjected to radical copolymerization with acrylamide and formed a copolymer 5. It would release the active agent 2 in a reasonable amount by a hydrolysis process. The release rates of the compound 2 were determined by high performance liquid chromatography (HPLC) under different pH conditions. The results indicate that the copolymer 5 is potentially useful for the development of the chemically controlled‐released formulations of Hymexazol.

© 2002 Society of Chemical Industry
Near infrared (NIR) spectroscopy compared with thermogravimetric analysis as a tool for on‐line prediction of water diffusion in polyamide 6,6
Authors: Camacho Walker , Hedenqvist M S , Karlsson Sigbritt
Published: December 2002

NIR spectroscopy in the transmission mode and thermogravimetric analysis were used to predict diffusion of water into polyamide 6,6 samples immersed in water at 40, 60, 75 and 90 °C for different periods of time. The sorption curves between 40 and 75 were sigmoidal indicating that the surface concentration was time dependent. The sorption curves were readily fitted by the use of a time‐dependent surface concentration and a water‐concentration‐dependent diffusivity. The zero‐concentration water diffusivity decreased non‐linearly and the activation energy of diffusion increased from 24 to 58 kJ mol−1, with decreasing temperature. The surface concentration relaxation time decreased rapidly. The sorption of water in thick polyamide samples was readily characterized by FT‐NIR spectroscopy. The accuracy and feasibility of this method was similar to conventional thermogravimetric methods. The greatest advantage of FT‐NIR, however, is the possibility of detecting and monitoring the moisture concentration on‐line and in a non‐destructive way.

© 2002 Society of Chemical Industry
Polypyrrole/polyaniline conductive films obtained electrochemically on polycarbonate‐coated platinum electrodes
Authors: Karakışla Meral , Aksu Levent , Saçak Mehmet
Published: December 2002

In this study, two‐component free‐standing films were obtained by coating a polycarbonate (PC)‐coated Pt electrode first with polypyrrole (PPy) in an organic medium and then polyaniline (PAn) in an aqueous medium using an electrochemical technique. The amount of PPy and PAn contained in the films was controlled by varying the electrolysis time. The PC/PPy/PAn films were characterized by cyclic voltammetry, conductivity, FTIR and UV–visible spectrophotometry, and thermogravimetric analysis. The resistance change of the films was determined in the temperature range of −15 to 120 °C and their temperature sensor properties were investigated.

© 2002 Society of Chemical Industry
Effect of surface treatment on the impact behaviour of fly‐ash filled polymer composites
Authors: Kishore  , Kulkarni S M , Sunil D , Sharathchandra S
Published: December 2002

The impact behaviour of epoxy specimens containing 10% by volume of fly‐ash particles with their surface treated for improving or decreasing adhesion is studied. The resulting behavioural patterns are listed and compared to those of composites containing untreated fly‐ash particles and unreinforced (ie neat) epoxy. It was noticed that samples involving adhesion‐increasing (ie acetone and silane) treatments show greater absorption of energy and maximum load compared to untreated samples and those subjected to adhesion‐reducing treatments. Ductility index, however, showed a reversed trend with adhesion‐reducing treatment yielding the highest value. In contrast, the energy absorbed was highest for neat resin and lowest for oil surface bearing ash particulate composites. Scanning electron microscope examination of the failed samples was carried out to obtain information on the fracture features with the aim of correlating microstructure to impact response. Thus, the higher ductility indices cases are shown to be distinct and different from composites containing other surface treatments for fillers.

© 2002 Society of Chemical Industry
Melt strength of calcium carbonate filled polypropylene melts
Authors: Kao Nhol , Chandra Arnab , Bhattacharya Sati
Published: December 2002

This paper investigates the extensional rheology (through melt strength measurement) of calcium carbonate (CaCO3) filled polypropylene (PP) melts. Different concentrations of CaCO3 filled PP were produced by mixing two master batches of pure PP and 70 wt% CaCO3 filled PP in required proportions in a counter‐rotating twin‐screw extruder. It was found that the melt strength of the CaCO3–PP melts was independent of CaCO3 concentrations up to 25 vol%. Further increase in CaCO3 concentration led to a severe reduction of melt strength.

© 2002 Society of Chemical Industry
Properties of hydrogels of atactic poly(vinyl alcohol)/NaCl/H2O system and their application to drug release
Authors: Shaheen Sharif Mohammad , Ukai Kohsuke , Dai Lixing , Yamaura Kazuo
Published: December 2002

In order to prepare cost‐effective physically cross‐linked hydrogels including food salt sodium chloride, samples, were prepared with various concentrations of NaCl and respective atactic poly(vinyl alcohol) (a‐PVA), and were evaluated. It had been observed that hydrogels containing NaCl concentration (9–11 wt%) along with a‐PVA concentration 9–5% respectively exhibited higher melting points (91.5–95.1 °C). A higher melting point characterizes the hydrogel composition of a system like a‐PVA(7%)/NaCl(11%)/H2O. The swelling degree of this hydrogel was found to be comparatively better at 37 °C than at any other temperature studied here. However, irregular Fickian swelling was found at this temperature. The UV light absorption maximum at 362–364 nm and minimum at 351 nm for this hydrogel had been found as evidence of physical cross‐linking. A drug, theophylline was loaded by solvent‐sorption and feed‐mixture dissolving methods. The feed‐mixture dissolving method is better than solvent sorption because of high drug loading, comparatively low fraction release rate and more sustained‐release of drug than that of solvent‐sorption. Theophylline was released twice as fast from the hydrogel after solvent‐sorption drug loading (3 h) than from that which used the feed‐mixture dissolving method (6.5 h). Theophylline‐loaded hydrogels of this system (feed‐mixture dissolving) were then prepared at high temperature (60 °C) thawing for 6 h followed by chilling at 0.4 °C for 3 h as one cycle. And the drug release behaviour and mass transfer were found almost the same as for chilling (24 h at 0.4 °C)–thawing (48 h at room temperature). Drug release behaviour was studied as apparently irregular Fickian diffusion (Higuchi Matrix Dissolution Model).

© 2002 Society of Chemical Industry
Synthesis of hydrogel for drug delivery studies utilizing photoinitiator‐free photopolymerization based on the donor/acceptor pair, N‐vinylpyrrolidinone and hydroxypentyl maleimide
Authors: Ng Loo‐Teck , Jönsson Sonny , Swami Salesh , Lindgren Karin
Published: December 2002

Photo‐differential scanning calorimetry (photo‐DSC) was used to study the rate of photoinitiator‐free copolymerization of a donor/acceptor pair involving N‐vinylpyrrolidinone (NVP), and a water‐soluble N‐substituted maleimide, hydroxypentyl maleimide (HPMI). Glucose, 1,1‐diethoxy ethane (DEE) and isopropyl alcohol (IPA) were included for the evaluation of their efficiencies as hydrogen donors, and glucose was shown to be the most efficient in enhancing the rate of polymerization. This photoinitiator (PI)‐free system was extended to hydrogel preparation using the radiation method with UV as the radiation source based on the same donor/acceptor pair, ie NVP/HPMI, in the presence of glucose as the hydrogen donor. Swelling and drug release tests showed that this hydrogel exhibited high swelling ability and a rather fast drug release rate when using theophylline as the model drug. These tests also revealed that the drug release kinetics and the water diffusion into this hydrogel did not adhere to the Fickian model. Cytotoxicity testing showed no evidence of this hydrogel being cytotoxic.

© 2002 Society of Chemical Industry
Synthesis and characterization of poly(N‐vinyl imidazole) hydrogels crosslinked by gamma irradiation
Authors: Pekel Nursel , Güven Olgun
Published: December 2002

Crosslinked poly(N‐vinyl imidazole) (PVIm) hydrogels in the form of rods have been prepared by 60Co γ‐radiation initiated simultaneous polymerization and crosslinking of N‐vinyl imidazole in bulk and water. In binary aqueous systems, the percentage gelation decreased with increasing water content. The PVIm hydrogels synthesized were further protonated in HCl solutions of different concentration. PVIm and protonated PVIm (H‐PVIm) hydrogels have been characterized using spectroscopic and thermal methods, and the swelling behaviour of these two types of hydrogel has been investigated. PVIm hydrogels originally swelled to 600% (by volume) but in their protonated form at pH 7.0 reached 4000% swelling.

© 2002 Society of Chemical Industry
Effect of polymer characteristics on Beckmann rearrangement of polymer supported ketoximes
Authors: Baby Shiney , Devaky K S
Published: December 2002

Beckmann rearrangement has been carried out in polymeric oximes synthesised from rigid styrene–divinylbenzene copolymer and flexible styrene–hexanediol diacrylate (HDODA) copolymer. Oxime functions were incorporated into these polymers through a series of polymer‐analogous reactions. First the polymers were subjected to Friedel‐Crafts acylation reactions with low molecular weight acid chlorides to give a set of polymeric ketones. These polymeric ketones were converted to oximes by treating with hydroxylamine hydrochloride in the presence of pyridine. The oximes were subjected to rearrangement under acidic conditions into substituted amides. The polymeric amides obtained were characterised by IR spectroscopy and chemical degradative analysis. The rearrangement in the macromolecular matrices were found to follow the same mechanistic path as in the low molecular weight analogues. The rate of rearrangement was found to be faster in the HDODA crosslinked polystyrene system.

© 2002 Society of Chemical Industry
Morphology of poly(butyl acrylate)/poly(styrene‐co‐methyl methacrylate) latex prepared by starved emulsion polymerization: II. Development of particle morphology
Authors: Huo Dongxia , Liu Dazhuang , Sun Peiqin
Published: December 2002

Heterogeneous latexes were prepared by a two‐stage seeded emulsion polymerization process under monomer starved conditions at 80 °C using potassium persulfate as the initiator and sodium dodecyl sulfate as the emulsifier. Poly(butyl acrylate) latexes were used as seeds. The second‐stage polymer was poly(styrene‐co‐methyl methacrylate). By varying the amount of methyl methacrylate (MMA) in the second‐stage copolymer, the polarity of the copolymer phase could be controlled. It was found that the latex particles displayed different morphologies depending on the monomer ratio. The amount of MMA had a significant effect on the evolution of morphology. The morphologies were observed by transmission electron microscopy. In addition, the evolution of the particle morphology was predicted by the mathmatical model for cluster migration. The model gave the same trends as the experimental results.

© 2002 Society of Chemical Industry
Curing kinetics and thermal property characterization of the bisphenol‐F epoxy resin and phthalic anhydride system
Authors: Gao Jungang , Zhao Hongchi , Li Yanfang
Published: December 2002

The curing kinetics of bisphenol‐F epoxy resin (BPFER) and curing agent phthalic anhydride, with N,N‐dimethylbenzylamine as an accelerator, were studied by differential scanning calorimetry (DSC). Analysis of DSC data indicated autocatalytic behaviour in the first stages of the cure for the system, and that this, could be well described by the model proposed by Kamal, which includes two rate constants, k1 and k2, and two reaction orders, m and n. The curing reaction in the later stages was practically diffusion‐controlled. To consider the diffusion effect more precisely, a diffusion factor, 𝒻(α), was introduced into Kamal's equation. The glass transition temperatures (Tgs) of the BPFER/phthalic anhydride samples were determined by means of torsional braid analysis. The thermal degradation kinetics of cured BPFER were investigated by thermogravimetric analysis.

© 2002 Society of Chemical Industry
Particle nucleation and growth mechanisms in miniemulsion polymerization of styrene
Authors: Chern Chorng‐Shyan , Chang Hung‐Te
Published: December 2002

Styrene miniemulsion polymerizations stabilized by sodium lauryl sulfate in combination with a reactive costabilizer, lauryl methacrylate (LMA) or stearyl methacrylate (SMA), were studied. A small amount of extremely hydrophobic dye was incorporated into monomer droplets (102 nm in diameter) to investigate particle nucleation and growth mechanisms. In addition to monomer droplet nucleation, particle nuclei generated in the aqueous phase (homogeneous nucleation) also play an important role in both LMA‐ and SMA‐containing polymerization systems. The way that these two nucleation mechanisms compete with each other is closely related to the water solubility of the costabilizer (LMA > SMA). The fraction of latex particles originating from homogeneous nucleation increases with decreasing hydrophobicity of the costabilizer. Zeta potential data of latex particles and the molecular weight and molecular weight distribution of emulsion polymers provide supporting evidence for the proposed competitive particle nucleation and growth mechanisms.

© 2002 Society of Chemical Industry
Study on the microstructures and mechanical behaviour of compatibilized polypropylene/polyamide‐6 blends
Authors: Zeng N , Bai S L , G'Sell C , Hiver J‐M , Mai Y W
Published: December 2002

A series of blends of polypropylene (PP)–polyamide‐6 (PA6) with either reactive polyethylene–octene elastomer (POE) grafted with maleic anhydride (POE‐g‐MA) or with maleated PP (PP‐g‐MA) as compatibilizers were prepared. The microstructures and mechanical properties of the blends were investigated by means of tensile and impact testing and by scanning electron microscopy and transmission electron microscopy. The results indicated that the miscibility of PP–PA6 blends was improved with the addition of POE‐g‐MA and PP‐g‐MA. For the PP/PA6/POE‐g‐MA system, an elastic interfacial POE layer was formed around PA6 particles and the dispersed POE phases were also observed in the PP matrix. Its Izod impact strength was four times that of pure PP matrix, whilst the tensile strength and Young's modulus were almost unchanged. The greatest tensile strength was obtained for PP/PA6/PP‐g‐MA blend, but its Izod impact strength was reduced in comparison with the pure PP matrix.

© 2002 Society of Chemical Industry
Dielectric relaxation behaviour of poly(cyclobutyl methacrylate)s
Authors: Díaz‐Calleja Ricardo , García‐Bernabé Abel , Sánchez‐Martínez Enrique , Hormazábal Andrea , Gargallo Ligia , Radić Deodato
Published: December 2002

Dielectric behaviour of two poly(methacrylate)s with cyclobutyl groups in the side‐chains has been studied. This investigation was performed by determining the dielectric permittivity and loss in terms of frequency and temperature for poly(cyclobutyl methacrylate) (PCBuM) and poly(cyclobutylmethyl methacrylate) (PCBuMM). Dynamic dielectric measurements show sub‐glass relaxations, probably due to motions in the lateral chain, including the cyclobutyl ring. The effect of the insertion of a flexible spacer group into the side‐chain is also analyzed. The α relaxations were analyzed in terms of the Havriliak–Negami equation and the free volume theory tested according to the Vogel–Fulcher–Tamman–Hesse equation. The conductive and interfacial phenomena were studied by hopping and MacDonald–Coelho models.

© 2002 Society of Chemical Industry
Atom force microscopic characterisation of the interaction forces between bovine serum albumin and cross‐linked alkylated chitosan membranes in media of different pH
Authors: Liu Wen Guang , Li Fang , Zhao Xiao Dong , Yao Kang De , Liu Qing Gang
Published: December 2002

Butyl, octyl and hexadecyl moieties were introduced into chitosan. The adhesion of bovine serum albumin (BSA) onto glucose aldehyde‐crosslinked alkylated chitosan membranes in pH media was investigated by probing the force‐displacement curves with BSA‐coated Atom force microscope (AFM) tips. The results indicated that, at the isoelectric point (IP), the sample membranes exhibited higher adhesion forces; and deviating from IP ie at pH 2, pH 6, the adhesion forces decreased. The adhesion forces at pH 2 are less than those at pH 6 due to the presence of electrostatic repulsive and attractive interactions, respectively. Measurements of the adhesion force confirmed quantitatively that the introduction of hydrophobic side‐chains to chitosan can facilitate protein adsorption; however, longer flexible side‐chains can depress protein adsorption to a certain degree. From an analyses of the adhesion forces, it is proposed that protein adsorption can be tuned by adjusting the lengths of the introduced side‐alkyl moieties.

© 2002 Society of Chemical Industry
Biodegradable hollow fibres containing drug‐loaded nanoparticles as controlled release systems
Authors: Polacco Giovanni , Cascone Maria Grazia , Lazzeri Luigi , Ferrara Stefania , Giusti Paolo
Published: December 2002

A ‘multiple’ delivery system was studied, consisting of hollow microfibres containing drug‐loaded nanoparticles. Both fibres and nanoparticles are made of biodegradable polymers, so that the system does not need any surgical operation to be removed. The main advantage of the system is that it allows the contemporaneous release of different kinds of drugs. Copolymers of poly(lactic acid) and ϵ‐caprolactone were used for the preparation of the fibres through both wet and dry–wet spinning procedures. Two types of nanoparticles, gelatin and poly(DL‐lactide‐co‐glycolide) nanoparticles, were prepared by simple water‐in‐oil and oil‐in‐water emulsions, respectively. Drugs such as dexamethasone and methotrexate were used to load the particles. The technique employed for the preparation of the nanoparticles filled fibres was described and the drug release characteristics of this system were investigated and compared with those of the free nanoparticles.

© 2002 Society of Chemical Industry
Melt rheology of nanometre‐calcium‐carbonate‐filled acrylonitrile–butadiene–styrene (ABS) copolymer composites during capillary extrusion
Authors: Liang Ji‐Zhao
Published: December 2002

The melt flow properties during capillary extrusion of nanometre‐calcium‐carbonate‐filled acrylonitrile–butadiene–styrene (ABS) copolymer composites were measured by using a Rosand rheometer to identify the effects of the filler content and operation conditions on the rheological behaviour of the sample melts. The experiments were conducted under the following test conditions: temperature varied from 220 to 240 °C and shear rate ranged from 10 to 104 s−1. The filler volume fractions were 0, 10, 20, 30, 40 and 50%. The results showed that the shear flow did not strictly obey the power law under the test conditions, and that the entry pressure drop (ΔPen) and the extension stress (σe) in entry flow increased nonlinearly, while the melt shear viscosity (ηs) and extension viscosity (ηe) decreased with increasing the wall shear stress (τw) at constant test temperature. The dependence of the melt shear viscosity on the test temperature was approximately consistent with the Arrhenius expression at fixed τw. When τw was constant, ηs and ηe increased while ΔPen and σe decreased with the addition of the filler volume fraction.

© 2002 Society of Chemical Industry
X‐ray photoelectron spectroscopic study of silk fibroin surface
Authors: Shao Jianzhong , Liu Jinqiang , Zheng Jinhuan , Carr C M
Published: December 2002

X‐ray photoelectron spectroscopy (XPS) has been used to probe the nature of silk fibroin surface, in particular the tyrosine content and sulfur species on the surface. The iodine labelling treatment of silk, followed by XPS surface analysis, reveals that silk fibroin has a tyrosine‐enriched surface, and that there are sulfur‐containing amino acids present on the surface, mainly occurring in the S6+ component. UV/ozone treatment modifies/removes the surface tyrosine‐ and sulfur‐containing species.

© 2002 Society of Chemical Industry
Polymerisation of ethylene catalysed by mono‐imine‐2,6‐diacetylpyridine iron/methylaluminoxane (MAO) catalyst system: effect of the ligand on polymer microstructure
Authors: Fernandes Susete , Bellabarba Ronan M , Ribeiro Alejandro F G , Gomes Pedro T , Ascenso José R , Mano João F , Dias Alberto R , Marques Maria M
Published: December 2002

The complex, {1‐{6‐[(2,6‐diisopropylphenyl)‐ethaneimidoyl]‐2‐pyridinyl}‐1‐ethanone}iron(II) dichloride (2), has been synthesised and characterised. Treatment of complex 2 with methylaluminoxane resulted in a very active catalytic system for the preparation of polyethylene (PE). The system shows activities in the order of magnitude 107 g (PE) mol−1(Fe) h−1 bar−1. Characterisation by 13C NMR indicated that branched PE was obtained and that experimental conditions affect polymer microstructure. PE produced contained six to eight branches per 100 carbons.

© 2002 Society of Chemical Industry
Effect of isotacticity distribution on crystallization kinetics of polypropylene
Authors: Lu Hongbin , Qiao Jinliang , Yang Yuliang
Published: December 2002

The crystallization kinetics of isotactic polypropylene (iPP) depends not only on the undercooling but also on its microstructure characteristics. In this paper the effect of isotacticity distribution on the isothermal kinetics of iPPs in the crystallization regime III was examined by differential scanning calorimetry. The microstructure features of two commercial film grade iPPs were characterized with temperature rising elution fractionation and size exclusion chromatography. The results indicated that, although the overall isotacticities and molecular weights of two iPPs were similar, their isothermal crystallization kinetics displayed marked differences due to the disparity in isotacticity distributions. With increasing molecular weight of components containing crystallizable units, the isothermal crystallization rate exhibited a higher temperature dependence. When the isotactic defects in polypropylene chains increase with the molecular weight of components, both the fold surface free energy σe and the work of chain folding q decreases, in spite of the higher molecular weight.

© 2002 Society of Chemical Industry
Kinetic and thermodynamic studies of depolymerisation of poly(ethylene terephthalate) by saponification reaction
Authors: Mishra S , Zope V S , Goje A S
Published: December 2002

Depolymerisation reaction of polyester waste was carried out by a saponification reaction. Yields of depolymerised products were up to 85% for a 2.5‐h reaction time. Products obtained were characterized by chemical as well as instrumental analysis such as mp (sublimation), acid value and FTIR spectra. The valued obtained for terephthalic acid (TPA) agreed with those for the pure substance. Chemical kinetics of this reaction shows that it is a first‐order reaction with respect to poly(ethylene terephthalate) (PET) concentration with a velocity constant of the order of 10−2 min−1. In the light of the Yashioka modified shrinking core model, a simultaneous fragmentation and depolymerisation model was proposed for the kinetics of hydrolysis of PET. The modified model is based on change in acid value of the product obtained, which is directly related to the change in surface area of particle. The energy of activation and the Arrhenius constant (frequency factor) obtained by Arrhenius plot were 59.71 kJ g−1 and 8.325 × 106 min−1 respectively.

© 2002 Society of Chemical Industry
Poly(hydroxyethyl methacrylate‐co‐glycidyl methacrylate) reactive membrane utilised for cholesterol oxidase immobilisation
Authors: Akgöl Sinan , Bayramoğlu Gülay , Kacar Yasemin , Denizli Adil , Arıca M Yakup
Published: December 2002

Poly(2‐hydroxyethyl methacrylate‐co‐glycidyl methacrylate) p(HEMA–GMA) membrane was prepared by UV‐initiated photopolymerisation of 2‐hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) in the presence of an initiator, azobisisobutyronitrile (AIBN). Cholesterol oxidase was immobilised directly on the membrane by forming covalent bonds between its amino groups and the epoxide groups of the membrane. An average of 53 µg of enzyme was immobilised per cm2of membrane, and the bound enzyme retained about 67% of its initial activity. Immobilisation improved the pH stability of the enzyme as well as its temperature stability. The optimum temperature was 5 °C higher than that of the free enzyme and was significantly broader. The thermal inactivation rate constants for free and immobilised preparations at 70 °C were calculated aski (free)1.06 × 10−1min−1andki (imm)2.68 × 10−2min−1, respectively. The immobilised enzyme activity was found to be quite stable in the repeated experiments.

© 2002 Society of Chemical Industry
Relaxation peak broadening and polymer chain dynamics in aramid‐fiber‐reinforced nylon‐66 microcomposites
Authors: Ryabov Ya. E. , Nuriel H. , Marom G. , Feldman Yu.
Published: December 2002

The relationship between the parameter of symmetric broadening of the glass‐transition relaxation process and the structure of aramid‐fiber‐reinforced nylon‐66 microcomposites is investigated in this article. The approach is based on a previously derived model that sets a quantitative interrelation between the Cole–Cole parameter α, the relaxation time, and the fractal dimension of a mobile polymer segment. The microcomposite, the dielectric response of which reflects the transcrystallinity effects, indeed exhibits significantly different values, such as higher Kirkwood correlation factor and α exponent values, in comparison with the control materials, and this indicates its different crystalline morphology and perhaps lower order in the amorphous phase. However, at this stage, it is still difficult to establish a quantitative relationship with the polymer chain dynamics. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 217–223, 2003
Predictors of well‐structured and ill‐structured problem solving in an astronomy simulation
Authors: Shin Namsoo , Jonassen David H. , McGee Steven
Published: December 2002

This study compared the problem‐solving skills required for solving well‐structured problems and ill‐structured problems in the context of an open‐ended, multimedia problem‐solving environment in astronomy. Two sets of open‐ended questions assessed students' abilities for solving well‐structured and ill‐structured problems. Generalized, rubric scoring systems were developed for assessing problem‐solving skills. Instruments were also developed and administered to assess cognitive and affective predictors of problem‐solving performance. By regressing the scores on the cognitive and affective predictors onto students' scores on the well‐structured and ill‐structured problems, we concluded that solving well‐structured and ill‐structured problems require different component skills. Domain knowledge and justification skills were significant predictors of well‐structured problem‐solving scores, whereas ill‐structured problem‐solving scores were significantly predicted by domain knowledge, justification skills, science attitudes, and regulation of cognition. Implications for problem solving in science education are presented. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 6–33, 2003
Temporal and spatial variability of the surface energy balance in Dronning Maud Land, East Antarctica
Authors: Reijmer C. H. , Oerlemans J.
Published: December 2002

We present data of nine Automatic Weather Stations (AWS), which are located in Dronning Maud Land (DML), East Antarctica, since the austral summer of 1997. Potential temperature and wind speed are maximum at the sites with the steepest surface slope, i.e., at the edge of the Antarctic plateau. Specific humidity and accumulation decrease with elevation and distance from the coast. The annual average energy gain at the surface from the downward sensible heat flux varies between ∼3 W m−2 and ∼25 W m−2, with the highest values at the sites with the largest surface inclination and wind speeds. The net radiative flux is negative and largely balances this sensible heat flux and ranges from ∼−2 W m−2 to ∼−28 W m−2; maximum values can be linked to maxima in surface slope and wind speed, and suggest a strong connection between the heat budget and the katabatic flow in DML. The average latent heat flux is generally small and negative (∼−1 W m−2) indicating a slight net mass loss through sublimation.
Magnetic component of narrowband ion cyclotron waves in the auroral zone
Authors: Santolík O. , Pickett J. S. , Gurnett D. A. , Storey L. R. O.
Published: December 2002

We report observations of waves near the local proton cyclotron frequency and its lowest harmonics, made by the Plasma Wave Instrument on board the Polar spacecraft, on orbits for which the perigee (at an altitude of 1 Earth radius) was in or near the southern auroral zone. The electromagnetic nature of these waves was revealed by measuring their magnetic components simultaneously with two independent antenna systems, one a single loop and the other a set of triaxial search coils. Waves of this kind were found in the southern auroral zone on about a third of the orbits examined. Peaks in the magnetic field power spectra occurred at frequencies both below and above the fundamental cyclotron frequency. The ratio of the amplitudes of the electric and magnetic fluctuations was usually greater than the speed of light, suggesting that we observe a magnetic component related to the wave mode customarily called electrostatic ion cyclotron waves. The fluctuating vector of the wave magnetic field was in or close to the plane perpendicular to the static magnetic field. Our main result is that its polarization, which covered a broad range from left‐hand elliptic to right‐hand elliptic, can be explained by the superposition of many linearly polarized waves.
Undrained poroelastic response of sandstones to deviatoric stress change
Authors: Lockner David A. , Stanchits Sergei A.
Published: December 2002

Deformation of porous crustal rock through diagenesis, tectonic loading, or other processes can change pore volume and affect fluid pressure. The largest stress‐induced pore pressure changes occur when fluid is trapped in pores in an “undrained” condition. We have measured the undrained poroelastic response of two sandstones to changes in mean and deviatoric stress. Pore pressure was found to respond to mean stress σm in the usual manner: Δp = BΔσm (B ranging from 0.4 to 0.7), nearly independent of the ambient deviatoric stress state. However, variations in deviatoric stress (σd = (σ1 − σ3)/2) at constant mean stress were also found to induce a reversible (elastic) pore pressure response to stress levels up to and exceeding 80% failure stress (i.e., Δp = = const.). The coefficient η became more negative with increasing deviatoric stress level in sandstone and Ottawa sand samples. That is, η represents a dilatant response where increased deviatoric stress causes a decrease in pore pressure. The poroelastic response to deviatoric stress is explained in terms of anisotropic matrix stiffening due to closure of crack‐like pore space or flattening of grain contacts at high ambient stress levels and can be important in calculations of earthquake stress transfer.
Impacts of wildfire on the permafrost in the boreal forests of Interior Alaska
Authors: Yoshikawa Kenji , Bolton William R. , Romanovsky Vladimir E. , Fukuda Masami , Hinzman Larry D.
Published: December 2002

The impact to the permafrost during and after wildfire was studied using 11 boreal forest fire sites including two controlled burns. Heat transfer by conduction to the permafrost was not significant during fire. Immediately following fire, ground thermal conductivity may increase 10‐fold and the surface albedo can decrease by 50% depending on the extent of burning of the surficial organic soil. The thickness of the remaining organic layer strongly affects permafrost degradation and aggradation. If the organic layer thickness was not reduced during the burn, then the active layer (the layer of soil above permafrost that annually freezes and thaws) did not change after the burn in spite of the surface albedo decrease. Any significant disturbance to the surface organic layer will increase heat flow through the active layer into the permafrost. Approximately 3–5 years after severe disturbance and depending on site conditions, the active layer will increase to a thickness that does not completely refreeze the following winter. This results in formation of a talik (an unfrozen layer below the seasonally frozen soil and above the permafrost). A thawed layer (4.15 m thick) was observed at the 1983 burned site. Model studies suggest that if an organic layer of more than 7–12 cm remains following a wildfire then the thermal impact to the permafrost will be minimal in the boreal forests of Interior Alaska.