bluuebunny/crossref_metadata_2025 huggingface dataset:
A five‐year evaluation of reports of overdose with indinavir sulfate
Authors: Lehman Heidi P. , Benson Joan O. , Beninger Paul R. , Anderson Charles A. , Blumenthal Steven J. , Sharrar Robert G.
Published: September 2003

Methods

Analysis of indinavir overdose reports in Merck & Co., Inc.'s safety database through the first 5 years following US licensure of indinavir. Reports were classified as acute (single high dose in excess of 2400 mg), chronic (multiple extra doses, not exceeding 2400 mg per dose), single extra dose (not exceeding 2400 mg) and dose not reported.

Results

Seventy‐nine reports of indinavir overdose were reviewed (15 acute, 43 chronic, 13 single extra dose and 8 dose not reported). A total of 52/79 (66%) reports were associated with adverse events. For acute overdose reports with adverse events, indinavir doses ranged from 2.8 g to 48 g (median 6 g; mean 13 g); for acute overdose reports without adverse events, indinavir doses ranged from 4 g to 80 g (median 56 g; mean 45 g). Adverse events following acute and chronic exposures were similar; the most commonly reported adverse events included nausea, vomiting, abdominal pain and nephrolithiasis. Of the 52 patients with adverse events, 39 recovered, 6 had not recovered at the time of reporting and no information regarding outcome was provided in 7 reports.

Conclusions

Overdose with indinavir was associated with adverse events in the majority of reports. These were most commonly gastrointestinal and renal events, and were generally consistent with the known safety profile of indinavir. The majority of patients recovered. Copyright © 2003 John Wiley & Sons, Ltd.
Surface topography and surface chemistry of radiation‐patterned P(tBuMA)—analysis by atomic force microscopy
Authors: Watson Gregory S , Blach Jolanta A , Nicolau Dan V , Pham Duy K , Wright Jon , Myhra Sverre
Published: September 2003

Poly‐(tert‐butyl methacrylate) (P(tBuMA)) thin‐film surfaces were patterned by UV radiation at doses in the range 10–100 mJ cm−2, in order to induce laterally differentiated surface chemistry with µm resolution. The most likely pathway for the radiation chemistry predicts a transition from hydrophobicity to hydrophilicity. Outcomes of analysis by atomic force microscopy under air ambient conditions were consistent with that prediction. Topographic and lateral force imaging, in combination with friction loop analysis, revealed shrinkage and increased friction arising from exposure. Force versus distance analysis revealed greater adhesion in hydrophilic regions, due to greater meniscus force acting on the tip. The thickness of adsorbed moisture, increased by a factor of 2.5 from ca 0.8 nm for the unirradiated surface, as a result of greater hydrophilicity induced by radiation. The latter observation shows that the increased friction was due principally to the greater normal force on the tip from an additional meniscus force. Copyright © 2003 Society of Chemical Industry
Oligo(ethylene oxide) side‐chain steric screening effects on conductimetric properties of grafted poly(4‐vinylpyridinium) salts in aqueous solutions
Authors: Benmansour K , Mansri A , François J
Published: September 2003

A set of poly[N‐oligo(ethylene oxide)yl 4‐vinylpyridinium tosylate] (P4VOEOOTs) has been prepared by spontaneous polymerization of 4‐vinylpyridine. This method gives a grafted polyelectrolyte having a positive charge on every backbone pyridinic moiety. The P4VP15Ts, P4VP164Ts, P4VP350Ts and P4VP750Ts aqueous solution conductivities were determined in the concentration range from 6 × 10−4 to 10−2 M at 25 °C. The variation of the conductivity versus concentration of the investigated system exhibits typical polyelectrolyte behaviour. The polyelectrolyte mobility was found to be dependent on the oligo(ethylene oxide) (OEO) side‐chain length. Manning's rod‐like model fails to describe these results. A simple steric effect is proposed to explain the influence of the OEO length. Copyright © 2003 Society of Chemical Industry
Clay‐reinforced epoxy nanocomposites
Authors: Ratna D , Manoj N R , Varley R , Singh Raman R K , Simon G P
Published: September 2003

Epoxy/clay nanocomposites were prepared using a conventional diglycidyl ether of bisphenol A (DGEBA) epoxy, cured with diethyltoluene diamine (DETDA). The nanocomposites were characterized by dynamic mechanical analysis. A modest increase in glass transition temperature and significant increase in storage modulus were achieved as a result of incorporation of clay. The formation of nanocomposite was confirmed by wide‐angle X‐ray analysis. The higher impact strength of the nanocomposite compared the DGEBA matrix was explained in terms of with the morphology observed by SEM.

© 2003 Society of Chemical Industry
Control of morphologies and mechanical properties of thermoplastic‐modified epoxy matrices by addition of a second thermoplastic
Authors: Peña G , Eceiza A , Valea A , Remiro P , Oyanguren P , Mondragon I
Published: September 2003

Ternary mixtures based on stoichiometric mixtures of the diglycidyl ether of bisphenol‐A (DGEBA) and 4,4′‐diaminodiphenyl sulfone (DDS) and two miscible thermoplastics, poly(methyl methacrylate) (PMMA) and the poly(hydroxy ether of bisphenol‐A) (phenoxy), were investigated by optical microscopy (OM), atomic force microscopy (AFM) and dynamic mechanical analysis (DMA). Mechanical testing was used to study the ultimate behavior. All the modified epoxy mixtures were heterogeneous. DMA has been shown to be an excellent technique for detecting the morphologies generated after curing when the loss modulus is used for analysis. Morphology varied with the thermoplastic content on the mixtures. The addition of a second thermoplastic in small amounts changed the morphological features from particulated to co‐continuous and from that to phase‐inverted morphologies. A significant increase in fracture toughness was observed above all for the mixtures with some level of co‐continuity within the epoxy‐rich matrix. Phase inversion led to poor strength and also fracture toughness. Copyright © 2003 Society of Chemical Industry
Dilute solution viscosity properties of high molar mass poly(acrylonitrile‐co‐itaconic acid)
Authors: Devasia Renjith , Reghunadhan Nair CP , Ninan KN
Published: September 2003

The intrinsic viscosities [η] and viscosity constants of high molar mass poly(acrylonitrile‐co‐itaconic acid) copolymer in DMF were obtained by the methods of Huggin, Fuoss, Martin and Schulz‐Blaschke. The values of [η] by averaging procedures suggested by Sakai were close to those from Huggins method. There was an abnormal positive deviation from the rectilinearity of the reduced viscosity (ηred) versus concentration (c) plot in all the cases in the dilute regime, which was attributed to the polyelectrolytic effect. This was further confirmed by the analysis by Fuoss method. The deviation from the Huggins dependence is discussed for a good solvent (DMF) alone and in the presence of a non‐solvent, methanol. The deviation cross‐over points c′ and c″ changed with molecular weight, and the concentration range greater than c″ and less than c* was taken for a more reliable determination of intrinsic viscosity. The non‐solvent played a key role in determining the polymer–polymer interactions. The Huggins coefficient increased and the cross‐over points c′ and c″ shifted to higher concentration regime as the mixed solvent became poorer. The inter‐ and intra‐polymer interactions increased in the presence of methanol. In poor solvent, the enhanced intramolecular interactions caused the polymer to shrink in size, causing a reduction in [η] and hydrodynamic volume. Copyright © 2003 Society of Chemical Industry
Investigation on the crystal structure of proteins and their complexes in solution from combined TEM techniques and solubility measurements: the case of endo‐1,3(4)‐β‐glucanase
Authors: Guyot Ferréol V , Hagnerelle X , Gaunand A , Larquet E , Caussette M , Lindet B
Published: September 2003

Endo‐1,3(4)‐β‐glucanase was crystallized from a crude extract of protein solution by addition of a salt A+, X−. Optical microscopy showed needle‐shaped polydisperse crystals with a mean size of 10 µm. Using transmission electron microscopy with specific settings allows one to characterize the ordered arrays of a thin protein crystal and to determine the parameters of the crystal lattice. The results suggest that the unit cell of a endo‐1,3(4)‐β‐glucanase crystal may consist in the association of a given number of these proteins. Such oligomers have already been seen for other proteins. The solubility of endo‐1,3(4)‐β‐glucanase in aqueous solution was determined for several X− concentrations using BCA assay (titration of the total protein in solution) and electrophoresis. The new data are in agreement with a new simple model based on equilibrium between the oligomer in solution and neutral and charged X− complexes of the protein in the monomer state. The model provides a new approach to the usual salting‐in/salting‐out description of protein solubility. Copyright © 2003 Society of Chemical Industry
1‐amino‐4,5‐8‐naphthalenetricarboxylic acid‐1,8‐lactam‐4,5‐imide‐containing macrocycles: synthesis, molecular modelling and polymerization
Authors: Ponce Patricia , Fomina Lioudmila , García Patricia , Fomine Serguei
Published: September 2003

Novel macrocycles containing 1‐amino‐4,5‐8‐naphthalenetricarboxylic acid‐1,8‐lactam‐4,5‐imide and 1,4,5‐8‐naphthalenetetracarboxylic bisimide fragments were synthesized by the high‐temperature pseudo‐high‐dilution acylation of the corresponding diols with isophthaloyl chloride, 4,4′‐ and 2,2′‐dichlorocarbonyl biphenyls with up to 60% yield. An important side‐reaction that impedes cyclization was found to be the reaction of diol OH groups with HCl during the acetylation. The ring strain in synthesized macrocyles and model cycles was estimated using the isodesmic reaction approach at the B3LYP/6–311 + G(d,p)//HF/3–21G level of theory. Lactamimide‐containing macrocycles were found to be more strained than bisimide‐containing macrocycles. The ring‐opening polymerization (ROP) of synthesized macrocycles in the molten state shows that the driving force of this process is the strain release on ring‐opening. The ROP of lactamimide‐containing macrocycles was found to be an efficient way to obtain lactamimide‐containing polymers, which are otherwise difficult to synthesize. Copyright © 2003 Society of Chemical Industry
Atom transfer radical polymerization of (R)‐2‐methacryloyloxy‐2′‐methoxy‐1,1′‐binaphthalene
Authors: Xue Hong , Xu Yong‐An , Ding Jin‐Ying , Gao Lian‐Xun , Ding Meng‐Xian
Published: September 2003

Atom transfer radical polymerization (ATRP) of (R)‐2‐methacryloyloxy‐2′‐methoxy‐1,1′‐binaphthalene ((R)‐MAMBN) mediated by different amine ligands, copper(I) chloride and ethyl 2‐bromopropionate in different solvents, and reverse ATRP of (R)‐MAMBN were studied. It was shown that optically active polymers were obtained, with poor control of the molecular weights, and low polydispersities. Specific rotation of the polymers increased with increasing molecular weights. By comparison with (R)‐MAMBN, poly((R)‐MAMBN)s exhibits higher specific rotation and a positive Cotton effect. Copyright © 2003 Society of Chemical Industry
Monomer reactivity ratios for lauryl methacrylate–isobutyl methacrylate in bulk free radical copolymerization
Authors: Habibi A , Vasheghani‐Farahani E , Semsarzadeh MA , Sadaghiani K
Published: September 2003

Statistical copolymers of isobutyl methacrylate and lauryl methacrylate were prepared by free radical bulk copolymerization at 70 °C using 2,2′‐azobisisobutyronitrile as initiator. The synthesis of these copolymers was investigated over a wide composition range at low conversion levels. Copolymer compositions were determined from the C, H and O contents obtained by elemental analysis. The monomer reactivity ratios and the 95% individual confidence intervals and 95% joint confidence intervals were calculated by the Fineman–Ross, Ezrielev–Brokhina‐Roskin, Kelen and Tüdös, Extended Kelen and Tüdös methods and a linear iterative method proposed by Mao and Huglin. The estimation process was performed by applying non‐linear techniques based on Marquardt optimization, ordinary least‐squares (OLS) and generalized least‐squares approaches and the results were compared. Monomer reactivity ratios and monomer partition coefficients were also analysed on the basis of the bootstrap models by applying the non‐linear least‐squares approach. Good agreement between experimental and calculated copolymer compositions was obtained. The results show that this copolymerization system is strictly describable by the simple bootstrap terminal model (SBTM) and accurate monomer reactivity ratios can be obtained. The monomer sequence distributions were also calculated using the monomer reactivity ratios obtained from SBTM. Copyright © 2003 Society of Chemical Industry
Microwave dielectric relaxation and molecular dynamics in binary mixtures of poly(vinyl pyrrolidone)–poly(ethylene glycol)s in non‐polar solvent
Authors: Sengwa RJ
Published: September 2003

Dielectric relaxation study of binary mixtures of poly(vinyl pyrrolidone) (PVP) (Mw = 40 000 g mol−1) and poly(ethylene glycol)s (PEGs) (Mn = 200, 400 and 600 g mol−1) with concentration variation was carried out in dilute solutions of benzene at 10.1 GHz and 35 °C. The average relaxation time τo, corresponding to segmental motion τ1 and group rotations τ2 was determined for PVP–PEGs mixtures. A comparison of these mixtures relaxation times was made with the relaxation times of PEGs in benzene solvent. The evaluated τo values of PVP–PEGs mixtures in benzene solution are assigned to the reorientation of PEG molecules. It has been observed that the τo value of PVP–PEG200 mixtures increases with increasing concentration of PVP but their values are small in comparison with the τo value of PEG200 molecules. In the case of PVP–PEG400 and PVP–PEG600 mixtures, the evaluated values of τo are greater than the corresponding τo values of PEG400 and PEG600 molecules in benzene solvent. The variation in τo values in these systems has been discussed by considering the stretching effect in the PEGs molecular chains in PVP–PEGs mixtures in benzene solutions. The high value of distribution parameter α (≈0.4 to 0.7) suggests that in these mixtures there is a large contribution of segmental motion and group rotations to the relaxation processes. The nature of the formation of hydrogen‐bonded PVP–PEG complex heterogeneous network due to hydrogen bonding between carbonyl groups of PVP monomer units and terminal hydroxyl groups of PEGs is discussed. Furthermore, the elongation behaviour of PVP–PEG complex networks in benzene solvent and the molecular dynamics in the mixture due to breaking and reforming of hydrogen bonds has been explored by comparing the evaluated relaxation times and the Kirkwood correlation factor of pure PEG molecules for their possible use in drug control release systems. The relaxation times of these mixtures are independent of their viscosity, but the elongation of the mixture network is influenced by the PEG chain length and the number of hydroxyl groups in comparison with the number of carbonyl groups in the mixtures. Copyright © 2003 Society of Chemical Industry
Synthesis and characterization of nanocomposites of silicon dioxide and polyurethane and epoxy resin interpenetrating network
Authors: Zhang Hongwen , Wang Bing , Li Hongtu , Jiang Yan , Wang Jingyuan
Published: September 2003

Nanocomposites with varying concentrations of nanosized silicon dioxide particles were prepared by adding nanosilica to interpenetrating polymer networks (IPN)s of polyurethane and epoxy resin (PU/EP). The PU/EP IPNs and nanocomposites were studied by dynamic mechanical analysis, scanning electronic microscopy, wide‐angle X‐ray diffraction and small‐angle X‐ray scattering. The result showed that adding nanosize silicon dioxide can improve the properties of compatibility, damping and phase structure of IPN matrices. Copyright © 2003 Society of Chemical Industry
Synthesis and properties of cationic polyacrylamide containing pyridine quaternary salt
Authors: Gao Baojiao , Lv Yuexian , Jiu Hongfang
Published: September 2003

The copolymer P(AM‐co‐4VP) of acrylamide (AM) and 4‐vinylpyridine (4VP) was synthesized by radical copolymerization in solution, and then the copolymer was quaternarized using dimethyl sulfate to produce cationic P(AM‐co‐4VP) (CPAV), a cationic polyacrylamide containing quaternary pyridine salt. Two series of CPAV have been synthesized. The structure and composition of the copolymer and the cationic copolymer were characterized by their FTIR, 1H NMR and ultraviolet spectra Flocculation and corrosion inhibition properties of the cationic copolymer were studied in detail and effects of cationic degree and molecular weight on the flocculation and corrosion inhibition properties were discussed. The results showed that cationic polyacrylamide containing quaternary pyridine salt possesses excellent flocculation, corrosion inhibition and other functions. The higher the degree of cationization, the better are these functions, and the molecular weight also effects the functions significantly. Copyright © 2003 Society of Chemical Industry
Studies on high density polyethylene (HDPE) functionalized by ultraviolet irradiation and its application
Authors: Wu Shishan , Zhang Jun , Xu Xi
Published: September 2003

The structure and properties of high density polyethylene (HDPE) functionalized by ultraviolet irradiation at different light intensities in air were studied by electron analysis, FTIR spectroscopy, contact angle with water, differential scanning calorimetry and mechanical properties measurement. The results show that oxygen‐containing groups such as CO, C—O and C(O)O were introduced onto the molecular chain of HDPE following irradiation, and the rate and efficiency of HDPE functionalization increased with enhancement of irradiation intensity. After irradiation, the melting temperature, contact angle with water and notched impact strength of HDPE decreased, the degree of crystallinity increased, and their variation amplitude increased with irradiation intensity. Compared with HDPE, the yield strength of HDPE irradiated at lower light intensity (32 W m−2 and 45 W m−2) increases monotonically with irradiation time, and the yield strength of HDPE irradiated at higher light intensity (78 W m−2) increases up to 48 h and then decreased with further increase in irradiation time. The irradiated HDPE behaved as a compatibilizer in HDPE/polycarbonate (PC) blends, and the interface bonding between HDPE and PC was ameliorated. After adding 20 wt% HDPE irradiated at 78 W m−2 irradiation intensity for 24 h to HDPE/PC blends, the tensile yield strength and notched Izod impact strength of the blend were increased from 26.3 MPa and 51 J m−1 to 30.2 MPa and 158 J m−1, respectively. Copyright © 2003 Society of Chemical Industry
Effect of fluorene‐bisphenol ring substitution and bridge rigidity on physical and gas permeation properties of resulting polyarylates
Authors: Bhole YS , Kharul UK
Published: September 2003

This study reveals gas permeability and related physical properties of aromatic polyesters prepared from fluorenone‐based bisphenols and an equimolar mixture of isophthalic and terephthalic acids. Effects of a rigid bridge group at these bisphenols were examined. Bisphenol phenyl rings were also substituted in an asymmetric substitution manner (the two positions ortho to —OH contained different groups) in dimethylfluorene bisphenol (DMFBP) and dibromodimethylfluorene bisphenol (DBrDMFBP). Polyarylates prepared using these bisphenols were studied for gas permeation with reference to the effects of bridge rigidity and asymmetric substitution by polar bromine and non‐polar methyl groups. Glass transition temperature and estimated fractional free volume were varied by incorporation of rigid 9,9′‐fluorenylidene group. An increase in gas permeability was associated with a similar or general decrease in selectivity of various gas pairs. This behaviour was attributed mainly to the rigid but flat group situated at the bridge position of the bisphenol moiety. Copyright © 2003 Society of Chemical Industry
Investigation of compatibility of a dicyanate ester monomer and polysulfone by size‐exclusion chromatography and viscometry
Authors: Gómez Clara M , Porcar Iolanda , Recalde Ileana , Campos Agustín
Published: September 2003

The influence of solvent on the compatibility behaviour of Arocy B10, a cyanate ester monomer, and polysulfone (PSF) was investigated by means of dilute solution viscometry and of the preferential solvation parameter at 25 °C. The ternary systems under study are: tetrahydrofuran/Arocy B10/polysulfone (PSF), N,N‐dimethylformamide/Arocy B10/PSF and dichloromethane/Arocy B10/PSF. Values of the specific viscosity of PSF in a ‘binary solvent’ formed by Arocy B10 + solvent have been used to determine the compatibility of the polymer blend Arocy B10/PSF. An interaction parameter Δb that depends on concentration has been determined. The preferential solvation parameter was measured by size‐exclusion chromatography at different monomer‐to‐polymer ratios. PSF was found to be preferentially solvated by the monomer. Both techniques agree quantitatively in every system indicating maximum compatibility at the same Arocy B10 concentration. However, they differ when comparing the two parameters among the three systems. Copyright © 2003 Society of Chemical Industry
Synthesis and characterization of novel diimide–dinaphthols and resulting poly(urethane–imide)s
Authors: Mehdipour‐Ataei Shahram , Keshavarz Shahriar
Published: September 2003

Novel diols containing imide groups were prepared via condensation of aromatic dianhydrides with 5‐amino‐1‐naphthol. The diimide–dinaphthols prepared were characterized by conventional methods and used to synthesize new poly(urethane–imide)s (PUIs). All the polymers were characterized and their physical properties, such as solubility, solution viscosity, thermal stability, and thermal behaviour were studied. The polymers obtained showed more thermal stability than typical polyurethanes because of the presence of the imide groups. Copyright © 2003 Society of Chemical Industry
Synthesis and properties of novel poly(meth)‐acrylates containing tricyanocyclopropyl groups for piezoelectric applications
Authors: Lee Ju‐Yeon , Bang Han‐Bae , Choe Sang Joon
Published: September 2003

o‐(2,2,3‐Tricyano‐3‐carbomethoxycyclopropyl)phenoxyethyl acrylate (5a) and o‐(2,2,3‐tricyano‐3‐carbomethoxycyclopropyl)phenoxyethyl methacrylate (5b) were prepared by reactions of bromomalononitrile with methyl o‐(2‐acryloyloxyethoxy)benzylidenecyanoacetate and methyl o‐(2‐methacryloyloxyethoxy)benzylidenecyanoacetate respectively. The dipole moments of 5a and 5b, calculated by atom superposition and electron delocalization molecular orbital method, were 2.75–3.47 D. Monomers 5a and 5b were polymerized with free‐radical initiators to obtain the polymers with tricyanocyclopropane ring as a piezoelectric chromophore in the pendant group. The resulting polymers 6a and 6b were soluble in common organic solvents such as acetone and DMF. Polymers 6a and b showed thermal stability up to 280 °C in TGA thermograms. Tg values obtained from DSC thermograms were in the range 125–140 °C. Piezoelectric coefficients (d31) of the poled films were 1.2–1.4 pC N−1. These polymers showed good temporal and long‐term thermal stabilities which are acceptable for piezoelectric device applications. Copyright © 2003 Society of Chemical Industry
Hydrophilisation of silicone rubber for medical applications
Authors: Hron Petr
Published: September 2003

Silicone rubber is one of the biomaterials used for preparation of medical implants. The properties of silicone rubber and methods of their evaluation are surveyed with respect to the medical applications. For some applications the hydrophobic character of silicone rubber is undesirable and possibilities of its hydrophilisation are presented in this review as well. Special attention is paid to the process of preparation of hydrophilic silicone rubber–hydrogel composite materials based on acrylic and methacrylic acids derivatives and to the properties of such materials. Copyright © 2003 Society of Chemical Industry
Studies on polybenzimidazole/poly (4‐vinylpyridine) blends and their proton conductivity after doping with acid
Authors: Pu Hongting
Published: September 2003

In the present work, polybenzimidazole (PBI) and poly(4‐vinylpyridine) (P4VP) were chosen because they form miscible blends and both materials are suitable for acid doping as a matrix, which can eventually be used as proton conductor. The miscibility and inter‐polymer interactions were studied by infrared (IR) spectroscopy and differential scanning calorimetry (DSC). DSC and IR results suggest that PBI blended with P4VP exhibits good miscibility due to the strong hydrogen bonds formed between PBI's NH groups and P4VP's N: groups. The glass transition temperatures of the blends can be fitted to the Fox equation very well. The blends were also studied by thermogravimetry. Their thermal stability is slightly higher than that of P4VP, but is still lower than that of PBI. Temperature‐dependent conductivity of acid‐doped PBI/P4VP blends was studied. As the temperature increases, the conductivity of PBI/P4VP doped with H3PO4 increases. The temperature‐dependent conductivity of the blends follows a simple Arrhenius relationship when the P4VP content is low (less than 15%), while a non‐Arrhenius behaviour of the conductivity of the blends becomes more and more significant with increasing P4VP content. This means that the proton transport in the blends is controlled by both a hopping mechanism and the segmental motion of the polymer. The contribution of these two mechanisms depends on the P4VP content. Copyright © 2003 Society of Chemical Industry
Synthesis of linear low density polyethylene (LLDPE) by in situ copolymerization with novel cobalt and zirconium catalysts
Authors: Wang Hang , Ma Zhi , Ke Yucai , Hu Youliang
Published: September 2003

New cobalt catalysts {[2,6‐(CH3C=NAr)2C5H3N]CoCl2} (Ar=2‐methyl‐4‐methoxyphenyl, 1) and (Ar=2,4‐dimethylphenyl,2) were synthesized and found to exhibit good selectivity for α‐olefins with methylaluminoxane (MAO) as co‐catalyst. With only ethylene as the feed monomer cobalt catalysts 1 or 2 can be coupled with zirconium catalyst Dichloro [rac‐ethylenebis(indenyl)]Zirconium (IV) rac‐EtInd2ZrCl2 (3) to produce linear low density polyethylene by in situ polymerization. Spectra of resulting materials exhibit ethyl, butyl and long‐chain branches in the backbone of polyethylene. The ratio of Co/Zr and Δt, which is defined as the interval between introductions of two catalysts into the reactor, influenced catalytic activity and the resulting materials greatly. Compatibility and complementary behaviour of different catalysts proved to be two most important factors for in situ copolymerization. Copyright © 2003 Society of Chemical Industry
Connection of surface tension with multiple tribological properties in epoxy + fluoropolymer systems
Authors: Brostow Witold , Cassidy Patrick E , Macossay Javier , Pietkiewicz Dorota , Venumbaka Sreenu
Published: September 2003

Contact angles of free liquids on solid samples were measured and the van Oss–Good method was applied for evaluating surface tensions of the solids. A parachor method was used for comparison: in this case the respective values were calculated for the polymer solids from molecular and group contributions. Surface tensions were computed from the parachors and the two methods compared. Effects of varying the fluoropolymer added to the epoxy before curing are discussed. For a given fluoropolymer, effects of changing its concentration on surface tension have also been evaluated and compared to the changes in scratch resistance (scratch penetration depth, recovery depth) and in static and dynamic friction. Morphological and phase structure changes are reflected in all these properties, showing a strong connection between the surface tension and tribological properties. Copyright © 2003 Society of Chemical Industry
Intumescent char structures and flame‐retardant mechanism of expandable graphite‐based halogen‐free flame‐retardant linear low density polyethylene blends
Authors: Qu Baojun , Xie Rongcai
Published: September 2003

The structures of the intumescent charred layers formed from expandable graphite (EG)‐based intumescent halogen‐free flame retardant (HFFR) linear low‐density polyethylene (LLDPE) blends and their flame‐retardant mechanism in the condensed phase have been studied by dynamic Fourier transform infrared (FTIR), X‐ray photoelectron spectroscopy (XPS), laser Raman spectroscopy (LRS), scanning electron microscopy (SEM), differential thermal analysis (DTA) and thermal conductivity (TC) measurements. The dynamic FTIR, XPS and LRS data show that the carbonaceous structures of intumescent charred layers consist of EG and various numbers of condensed benzene rings and/or phosphocarbonaceous complexes attached by the POC and PN bonds or quaternary nitrogen products. The addition of EG can hasten the formation of these phosphocarbonaceous structures. The above results show that the flame‐retardant mechanism in the condensed phase is that the compact char structures, as observed by SEM, slow down heat and mass transfer between the gas and condensed phase and prevent the underlying polymeric substrate from further attack by heat flux in a flame. The DTA and TC data show that carbonaceous charred layers are good heat‐insulating materials, the TC value of which is only about one‐tenth of that of the corresponding blend and that they increase the oxidization temperature and decrease thermal oxidization heat of the LLDPE/EG/HFFR systems.

© 2003 Society of Chemical Industry
Abgehoben: Schweben in elektromagnetischen Feldern
Authors: Voigt Felix , Hinsch Klaus
Published: September 2003

Statisches, stabiles, freies Schweben ist in elektrostatischen oder magnetostatischen Feldern unmöglich. Trotzdem gibt es verschiedene Möglichkeiten, Körper mit elektromagnetischen Feldern schweben zu lassen. Eine Möglichkeit bieten aktive regelungstechnische Steuerungen. Noch geschickter sind Spulenanordnungen, die den schwebenden Körper mit harmonischen Wechselfeldern in einer zentralen Gleichgewichtslage halten.
Das Erdmagnetfeld — Beobachtung und Überwachung: SPEZIAL: GEOPHYSIK
Authors: Haak Volker , Maus Stefan , Korte Monika , Lühr Hermann
Published: September 2003

Das Erdmagnetfeld umgibt unseren Planeten wie ein unsichtbarer Schutzschild. Nachweisen lässt es sich leicht mit einem Kompass. In den letzten Jahrzehnten wurde aber immer deutlicher, dass das Erdmagnetfeld aus vielen Quellen gespeist wird. Nach unserem gegenwärtigen Wissen setzt es sich aus sieben Komponenten zusammen. Mit modernen Methoden ist es mittlerweile möglich, selbst schwächste Beiträge beispielsweise von der Lithosphäre oder von den ozeanischen Gezeitenströmungen zu messen.
Kollidierende Kontinente: SPEZIAL: GEOPHYSIK
Authors: Kind Rainer , Yuan Xiaohui
Published: September 2003

Mit einer neuen seismologischen Methode, die natürliche Quellen seismischer Energie benutzt, ist es gelungen, Strukturen in der gesamten Lithosphäre und im oberen Erdmantel von Tibet abzubilden. Deren Interpretation ermöglicht es, die geologische Geschichte der Kollision des indischen Subkontinentes mit dem eurasischen Kontinent aufzuklären.
Das Märchen vom Zauberer im weißen Kittel: Mythen um berühmte Experimente und Experimentatoren
Authors: Hentschel Klaus
Published: September 2003

Um berühmte Experimentatoren und Experimente ranken sich ebenso Mythen wie um geniale Theoretiker. Sie sind in populärwissenschaftlichen Büchern, Lehrbüchern und sogar in wissenschaftshistorischen Texten verbreitet. Die durch die Aufklärung etablierte Kultur des eleganten Schauexperiments vermittelt ein schiefes Bild vom mühsamen Weg vieler Experimentatoren zum dargestellten Ergebnis. Auch der Mythos des einsamen, genialen Experimentators ohne Helfer widerspricht dem historischen Befund. Gleiches gilt für dasexperimentum crucis, das eine Theorie als entscheidendes Experiment belegen soll. Die historische Forschung zeigt, dass es eine lange, eigenständige Tradition der experimentellen und instrumentellen Arbeit gibt.
Das Schwerefeld der Erde: SPEZIAL: GEOPHYSIK
Authors: Reigber Christoph , Schwintzer Peter
Published: September 2003

Die Kenntnis des Schwerefelds der Erde erlaubt Einblicke in die Struktur und Dynamik des Erdinnern und ermöglicht das Studium von an der Erdoberfläche ablaufenden Prozessen. Sie liefert mit dem Geoid eine wichtige physikalische Bezugsfläche in der Geodäsie und Ozeanographie. Der im Gravitationsfeld der Erde fliegende Satellit CHAMP misst derzeit die Globalstruktur des Schwerefelds mit bisher unerreichter Genauigkeit. Mit der 2002 gestarteten Mission GRACE und der geplanten GOCE steht das Erdschwerefeld gegenwärtig im Zentrum des geowissenschaftlichen Interesses.
Extrem dichtes Plasma im Festkörper
Authors: Glenzer Siegfried
Published: September 2003

Am Lawrence Livermore National Laboratory (LLNL), USA, ist es gelungen, für kurze Zeit im Innern eines Festkörpers ein extrem dichtes Plasma zu erzeugen. Mit Hilfe von Röntgenstreuung konnten zudem Temperatur und Dichte mit guter Genauigkeit gemessen werden [1].
Die Sonne bringt es an den Tag
Authors: Ziegler Thomas
Published: September 2003

Die Neutrinoforschung macht weitere Fortschritte. Mit dem Sudbury Neutrino Observatory ließ sich die Oszillation von solaren Neutrinos stichhaltig belegen, und in Japan gelang es, Neutrinos aus Kernreaktoren nachzuweisen. Die Messwerte aller bisherigen Neutrinoexperimente ermöglichten es jetzt auch, den Anteil des CNO‐Zyklus an der Energieerzeugung im Innern der Sonne einzugrenzen.
Flüssige Mikroschalter
Authors: Drach Volker
Published: September 2003

Das nichtlineare Verhalten viskoelastischer Flüssigkeiten hat außergewöhnliche strömungsmechanische Effekte zur Folge. Diese lassen sich zum Bau von Schaltelementen ausnutzen, die jenen der Mikroelektronik ähneln. So realisierten jüngst Alex Groisman und Kollegen am California Institute of Technology die Funktion eines Fluss‐Stabilisators und eines Flip‐Flop‐Speichers zur Kontrolle mikroskopischer Strömung [1].
Optisch erzeugte Spinströme
Authors: Hübner Jens
Published: September 2003

Durch Absorption von zwei Laserstrahlen mit unterschiedlichen Wellenlängen können in Halbleitern makroskopische Ströme erzeugt werden. Die Ausbreitungsrichtung der Elektronen und insbesondere die Ausrichtung ihrer Spins lassen sich über die relative Phase der beiden Laserfelder kohärent kontrollieren, wie kürzlich zwei Gruppen an den Universitäten von Marburg und Iowa demonstrierten [1, 2]. Genutzt wird bei diesem Experiment der Effekt der Quanteninterferenz zur Erzeugung von elektrischen Spinströmen.
Die Anfänge des Physik‐Nobelpreises
Authors: Jacobi Manfred
Published: September 2003

Keine andere Auszeichnung in den Naturwissenschaften erfährt so viel Aufmerksamkeit wie der Nobelpreis. Viele Geehrte werden untrennbar mit der Kulturgeschichte der Menschheit verbunden bleiben, andere werden vergessen. Von der nächsten Ausgabe an werden wir nicht nur wie gewohnt im letzten Heft des Jahres die aktuellen Physik‐Nobelpreisträger und ihre Entdeckung vorstellen, sondern gleichzeitig einen Blick hundert Jahre zurück werfen. Damit der Anfang nicht fehlt, stellen wir Ihnen hier die Preisträger vor.
Das streitlustige Akademiemitglied
Authors: Loos Andreas
Published: September 2003

Die Erde ist keine Kugel, sondern ein mehr oder minder verknautschter Ellipsoid. Vor 250 Jahren ruhte der Zweifel an der perfekten Kugelgestalt dagegen nur auf vagen Vermutungen und Theorien — und war heftig umstritten.
Käse ist Physik
Authors: Vilgis Thomas A.
Published: September 2003

Auf den ersten Blick scheinen Physik und Kochen wenig miteinander zu tun zu haben. Dass in der Küche dennoch interessante physikalische Vorgänge ablaufen, erklärt uns Thomas Vilgis in der neuen Kolumne Mol‐Gastronomie.
Manufacturers' compliance with the US Food and Drug Administration's Over‐the‐counter Human Drugs: Labeling Requirements
Authors: Sansgiry Sujit S. , Shringarpure Gauri
Published: September 2003

The use of over‐the‐counter (OTC) medications is increasing every year among consumers for symptomatic relief of ailments. Consumers have difficulties in reading and comprehending information on the OTC medication packages. A standardized format to present information on OTC medication packages was necessary; hence the FDA announced guidelines, Over‐the‐counter Human Drugs: Labeling Requirements, on 11 March 1999. Manufacturers have been given 6 years since 1999 to comply with the FDA guidelines. The objective of our study was to evaluate marketed OTC medication packages to determine the extent of adoption of the FDA guidelines by manufacturers. Packages (n ± 104) of OTC medication products from three different categories, viz. pain relievers, cough and cold remedies and stomach remedies, were evaluated for general information, written information and product claims. The Compugraphic point system scale was used to measure the font size of written information. In addition variables recommended by the FDA, such as bullets, paragraphs and hyphenations, were also evaluated. All the variables were coded in a database and analysed using the SAS (Version 8.2) statistical package. The study found that some manufacturers have adopted the FDA guidelines. However, many manufacturers did not implement several aspects of the guidelines. Although manufacturers still have a few more years to adhere to the guidelines, early implementation could benefit the consumers. Copyright © 2003 John Wiley & Sons, Ltd.
Wide‐spectrum antimicrobial packaging materials incorporating nisin and chitosan in the coating
Authors: Lee Chan Ho , An Duck Soon , Park Hyun Jin , Lee Dong Sun
Published: September 2003

Nisin and/or chitosan were coated, in 3% concentrations, onto paper with a binder medium of vinyl acetate–ethylene co‐polymer to provide antimicrobial activity for use in food packaging. The combined use of nisin and chitosan in the coating was an attempt to give a wide antimicrobial spectrum that could inhibit the growth of several food spoilage and poisonous microorganisms. The migration of the preservative from the coatings to water was evaluated at 10°C and related to the suppressed microbial growth in the water and microbial medium. After 8 days, 8.1–8.3% of nisin and 1.0–1.2% of chitosan had migrated, and the migration of each was not affected by the presence of the other. The paper coated with nisin was more effective than the chitosan‐coated paper in inhibiting the Gram‐positive bacterium, Listeria monocytogenes, whereas the latter was more effective against Escherichia coli O157:H7. Combined inclusion of nisin and chitosan in the coating gave antimicrobial activity against both bacterial strains, and could improve the microbial stability of milk and orange juice stored at 10°C. Copyright © 2003 John Wiley & Sons, Ltd.
Application of a computer model to evaluate the ability of plastics to act as functional barriers
Authors: Han Jong‐Koo , Selke Susan E. , Downes Theron W. , Harte Bruce R.
Published: September 2003

A simulation model computer program, which accounts for not only the diffusion process inside the polymer but also partitioning of the contaminant between the polymer and the contacting phase, was developed based on a numerical treatment, the finite element method, to quantify migration through multilayer structures. The accuracy of the model in predicting migration was demonstrated successfully by comparing simulated results to experimental data. For this study, three‐layer co‐extruded high density polyethylene (HDPE) film samples, having a symmetrical structure with a contaminated core layer and virgin outer layers as the functional barriers, were fabricated with varying thickness of the outer layers and with a known amount of selected contaminant simulant, 3,5‐di‐t‐butyl‐4‐hydroxytoluene (BHT), in the core layer. Migration of the contaminant simulant from the core layer to the liquid food simulants was determined experimentally as a function of the thickness of the outer layer at different temperatures. The computer program, developed as a total solution package for migration problems, can be applied not only to multilayer structures made with the same type of plastics but also to structures with different plastics, e.g. PP/PE/PP. This work might provide the potential for wider use of recycled plastic, especially polyolefins, which have lower barrier properties, in food packaging, and simplification of the task of convincing the FDA that adequate safety guarantees have been provided. Copyright © 2003 John Wiley & Sons, Ltd.
Package performance testing of dangerous goods in high‐altitude shipments
Authors: Singh S. Paul , Burgess Gary J. , Singh Jagjit
Published: September 2003

This paper discusses the impact of high‐altitude shipments on package integrity. High‐altitude shipments are encountered when trucks travel over high mountain passes or when cargo and feeder aircraft transport packages in non‐pressurized or partially‐pressurized cargo holds. Both these types of transport methods will result in severe changes in pressure as compared to packages being transported close to sea level. The testing of packages under these conditions is critical since package integrity may be compromised. The current shipping tests performed in test laboratories do not account for pressure changes and vibration together. This study showed that combination packages for dangerous goods and hazardous materials that are tested to existing UN, ICAO and US DOT requirements are limited, and can result in significant number of leaks. Testing under combined vibration and pressure changes is necessary. Copyright © 2003 John Wiley & Sons, Ltd.
Quantitation of midazolam in human plasma by automated chip‐based infusion nanoelectrospray tandem mass spectrometry
Authors: Kapron James T. , Pace Ellen , Van Pelt Colleen K. , Henion Jack
Published: September 2003

An automated chip‐based infusion nanoelectrospray ionization (nanoESI) platform was used to demonstrate reproducible quantitation of drug molecules from biological matrices. Three sample preparation strategies were explored including protein precipitation of plasma with acetonitrile, de‐salting of the plasma, and a combination of protein precipitation with subsequent de‐salting of the dried and reconstituted extract. The best results were obtained when fortified human plasma samples containing midazolam were precipitated with acetonitrile containing alprazolam as the internal standard (IS). The supernatant was concentrated to dryness, reconstituted in aqueous acid, and de‐salted by automated reversed‐phase solid‐phase extraction (SPE) prior to infusion nanoESI‐MS/MS. Analyses employed a triple quadrupole mass spectrometer operated in selected reaction monitoring (SRM) mode. Each sample was infused for approximately 10 s and the resulting ion current profiles were integrated. Area ratios were used for regression analysis of standard samples (1.5–500 ng/mL). Quality control samples (3, 250, and 400 ng/mL) in five replicates from three different analysis days demonstrated intra‐assay precision (≤16%), inter‐assay precision (≤5%), and overall accuracy (±9% deviation). Infusion reproducibility of the assay was established by analyzing extracts after storage for 24 h at ambient temperature. Control plasma samples from six different sources probed the potential utility of this technique for the analysis of clinical samples. At the lower limit of quantitation (LLQ), variability and mean overall accuracy were ≤13% CV and ±3% deviation, respectively, while at the upper limit of quantitation (ULQ) variability and mean overall accuracy were ≤9% CV and ±9% deviation, respectively. Inter‐chip variability was established by determining standard sample extracts across five different chips (≤12% CV). Throughput for the assay was 55 s per sample, although this time may be shortened to 40 s per sample with recent improvements in the automated nanoESI system. No contamination or carryover was observed using this promising automated nanoESI‐MS/MS platform. Copyright © 2003 John Wiley & Sons, Ltd.
Parallel preparative high‐performance liquid chromatography with on‐line molecular mass characterization
Authors: Edwards Christine , Liu Jianbo , Smith Thomas J. , Brooke Daniel , Hunter David J. , Organ Andrew , Coffey Patrick
Published: September 2003

High‐throughput chemistry (HTC) is now an integral part of the lead discovery process in many pharmaceutical and related chemical companies. As this process becomes refined or improved, with the integration of systems with enhanced capabilities, and the requirement for quality compounds of high purity increases, purification is often considered a bottleneck. Although a wide range of purification techniques is available, high‐performance liquid chromatography (HPLC) is usually the preferred method of purification to produce high‐purity compounds. Parallel preparative HPLC with robust UV‐guided fraction collection has been shown to reduce the bottleneck and complement the parallel synthesis systems. However, despite the success of this technique, post‐purification analysis of fractions to identify the target compound adds an additional level of complexity. This paper describes the interfacing of the Biotage Parallex™ with the MUX™ interface on a single quadrupole mass spectrometer, thus combining robust UV‐guided fractionation with on‐line MS characterization. Copyright © 2003 John Wiley & Sons, Ltd.
Electrospray ionization mass spectrometry in studies of aluminium(III)–ligand solution equilibria
Authors: Di Marco Valerio B. , Bombi G. Giorgio , Tubaro Michela , Traldi Pietro
Published: September 2003

Electrospray ionization mass spectrometry (ESI‐MS) has been applied to the study of solution equilibria between Al(III) and the two ligands 4‐hydroxy‐3‐pyridinecarboxylic acid (4H3P) and 3‐hydroxy‐4‐pyridinecarboxylic acid (3H4P). The results compare well with the speciation data obtained from potentiometric, UV‐visible spectroscopy, and NMR measurements. This agreement suggests the applicability of ES‐MS to the study of more complicated aluminium–ligand systems. Copyright © 2003 John Wiley & Sons, Ltd.
Analysis of Colubroidea snake venoms by liquid chromatography with mass spectrometry: evolutionary and toxinological implications
Authors: Fry Bryan G. , Wüster Wolfgang , Ryan Ramjan Sheik Fadil , Jackson Timothy , Martelli Paolo , Kini R. Manjunatha
Published: September 2003

The evolution of the venomous function of snakes and the diversification of the toxins has been of tremendous research interest and considerable debate. It has become recently evident that the evolution of the toxins in the advanced snakes (Colubroidea) predated the evolution of the advanced, front‐fanged delivery mechanisms. Historically, the venoms of snakes lacking front‐fanged venom‐delivery systems (conventionally grouped into the paraphyletic family Colubridae) have been largely neglected. In this study we used liquid chromatography with mass spectrometry (LC/MS) to analyze a large number of venoms from a wide array of species representing the major advanced snake clades Atractaspididae, Colubrinae, Elapidae, Homalopsinae, Natricinae, Psammophiinae, Pseudoxyrhophiinae, Xenodontinae, and Viperidae. We also present the first sequences of toxins from Azemiops feae as well as additional toxin sequences from the Colubrinae. The large body of data on molecular masses and retention times thus assembled demonstrates a hitherto unsuspected diversity of toxins in all lineages, having implications ranging from clinical management of envenomings to venom evolution to the use of isolated toxins as leads for drug design and development. Although definitive assignment of a toxin to a protein family can only be done through demonstrated structural studies such as N‐terminal sequencing, the molecular mass data complemented by LC retention information, presented here, do permit formulation of reasonable hypotheses concerning snake venom evolution and potential clinical effects to a degree not possible till now, and some hypotheses of this kind are proposed here. The data will also be useful in biodiscovery. Copyright © 2003 John Wiley & Sons, Ltd.