bluuebunny/crossref_metadata_2025 huggingface dataset:
Venous thromboembolism prophylaxis in emergency department admissions
Authors: Levine Robert L. , Hergenroeder Georgene W. , Miller Charles C. , Davies Al
Published: April 2007

BACKGROUND

Guidelines for venous thromboembolism prophylaxis exist, yet prophylaxis is underutilized and inadequately studied in the context of emergency department admissions.

OBJECTIVE

This study aimed to measure the rate of venous thromboembolism prophylaxis in emergency department hospitalizations.

DESIGN

Prospective observational study.

SETTING

Urban, teaching hospital.

PATIENTS

Adult emergency department admissions

INTERVENTION

Alternating admissions through the emergency department over 1 month were reviewed. Exclusion criteria were: requiring full anticoagulation, hemodialysis, length of stay less than 2 days, psychiatric admission, and primary physician declined review. An established risk assessment tool classified thromboembolism risk. Appropriate prophylaxis was defined as currently accepted medical or mechanical prophylaxis if in need or no prophylaxis if not indicated.

MEASUREMENTS

Factors associated with prophylaxis were considered significant if P < .05.

RESULTS

Of 254 patients, 201 (79%) had indications for prophylaxis, of whom 65 (32%) received it. Seventy‐eight percent of prophylaxis orders were written in the first day of hospitalization. Factors related to increased use of prophylaxis included use of standard order sets (OR = 3, P < .009) and increased risk of venous thromboembolism (P < .0001). Factors related to underuse included primary cardiovascular diagnosis (OR = 0.18, P < .0001) and age (OR = 0.97, P < .0001). Eighteen of 26 patients admitted for whom standard order sets were used (69%) received appropriate prophylaxis (P = .01).

CONCLUSIONS

Patients admitted through the emergency department are at high risk of venous thromboembolism. Despite this, venous thromboembolism prophylaxis is underutilized and rarely started after the first day of hospitalization. Use of admission standard order sets on admission from the emergency department may increase thromboembolic prophylaxis. Journal of Hospital Medicine 2007;2:79–85. © 2007 of Hospital Medicine.
The effects of deforestation on the hydrological cycle in Amazonia: a review on scale and resolution
Authors: D'Almeida Cassiano , Vörösmarty Charles J. , Hurtt George C. , Marengo José A. , Dingman S. Lawrence , Keim Barry D.
Published: April 2007

This paper reviews the effects of deforestation on the hydrological cycle in Amazonia according to recent modeling and observational studies performed within different spatial scales and resolutions. The predictions that follow from future scenarios of a complete deforestation in the region point to a restrained water cycle, while the simulated effects of small, disturbed areas show a contrasting tendency. Differences between coarsely spatially averaged observations and finely sampled data sets have also been encountered. These contrasts are only partially explained by the different spatial resolutions among models and observations, since they seem to be further associated with the weakening of precipitation recycling under scenarios of extensive deforestation and with the potential intensification of convection over areas of land‐surface heterogeneity. Therefore, intrinsic and interrelated scale and heterogeneity dependencies on the impact of deforestation in Amazonia on the hydrological cycle are revealed and the acknowledgement of the relevance of these dependencies sets a few challenges for the future. Copyright © 2007 Royal Meteorological Society
Rheological properties of batter systems containing different combinations of flours and hydrocolloids
Authors: Xue Jun , Ngadi Michael
Published: April 2007

The rheological properties of batters formulated using different combinations of wheat, corn, and rice flours with two types of hydrocolloids, namely methylcellulose (0.5%, 1% and 1.5%) or xanthan gum (0.2%), were studied. Control samples were formulated with combinations of flours without the added hydrocolloids. The effects of hydrocolloids on rheological characteristics of the batter systems were measured using a controlled stress rheometer at a temperature of 15 °C. The effects of hydrocolloids on dynamic viscoelastic parameters as functions of temperatures were evaluated. All the batters showed shear thinning behaviour with flow behaviour indices in the range 0.34–0.67. Addition of xanthan gum lowered the flow index values, imparting a higher degree of pseudoplasticity to the batter samples compared to methylcellulose. The consistency index of the control batter samples varied from 0.46 to 69.2 Pa sn. Addition of xanthan gum or methylcellulose significantly increased the batter consistency index value. The gums changed the onset temperature of structure development, and the storage (G′max) and loss moduli (G″max) of the batter systems. However, no statistically significant effects were observed on the peak temperature of batter systems in which the G′ reached a maximum value. Xanthan gum increased both G′max and G″max, whereas at higher concentrations methylcellulose increased G′max but lowered G″max. Copyright © 2007 Society of Chemical Industry
Vacuum ultraviolet laser‐induced fluorescence kinetic study of the reactions of Cl atoms with fluoroalkenes (CxF2x+1CHCH2, x = 1,2,4, 6, and 8) at low pressures
Authors: Takahashi Kenshi , Iwasaki Erika , Nakayama Tomoki , Matsumi Yutaka , Wallington Timothy J.
Published: April 2007

Pulsed laser photolysis/vacuum ultraviolet laser‐induced fluorescence techniques were used to measure rate coefficients for Cl atom reactions with a series of fluoroalkenes (CxF2x+1CHCH2, x = 1,2,4,6,8) in 6–10 Torr of CF4 diluent at 295 ± 2 K. Rate coefficients (units of 10−11 cm3 molecule−1s−1) of 4.49 ± 0.64, 6.58 ± 0.59, 8.91 ± 0.58, 9.27 ± 0.64, and 9.00 ± 0.87 were determined for CxF2x+1CHCH2 with x = 1,2,4,6, and 8, respectively. In 6–10 Torr of CF4 diluent, the kinetics of the title reactions are at, or near, the high‐pressure limit for x = 4, 6, and 8, approximately 30% below the high‐pressure limit for x = 2, and approximately 50% below the high‐pressure limit for x = 1. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 328–332, 2007
Analysis of the combustion reaction of carbon and lignite char with ignition and extinction phenomena: Shrinking sphere model
Authors: Gupta Parthapratim , Sadhukhan Anup Kumar , Saha Ranajit Kumar
Published: April 2007

Single‐particle combustion of carbon and lignite char is analyzed in the present work using a generalized shrinking sphere model. Finite volume method (FVM), which was earlier employed by the authors in solving such moving boundary problems involving single particle analysis of general fluid–solid noncatalytic reactions, has been used in this work to solve the transient mass and energy balance equations. The computed results are compared with published experimental data of fluidized‐bed combustion of lignite char. The effects of various parameters like bulk temperature, initial particle temperature, initial particle radius, etc. are examined on the dynamics of combustion of carbon and lignite char. The phenomena of ignition and extinction are also investigated. The importance of nonequimolar diffusion in the combustion reaction has also been analyzed. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 307–319, 2007
Synthesis of porphyrins bearing uracyl groups and their assembly induced by melamine derivatives
Authors: Arai Satoshi , Ohshiro Hiroki , Nishide Hiroyuki , Takeoka Shinji
Published: April 2007

Self‐assembled porphyrins via noncovalent bonding have attracted wide‐ranging researchers in material science. We reported herein the synthesis of the tetraphenyl porphyrin derivatives bearing uracyl groups as acceptor–donor–acceptor (ADA) type hydrogen bonding units, through the condensation of 5,10‐ or 5,15‐bis (3‐amino‐4‐ethylhexylphenyl) porphyrin derivatives with 6‐carboxyuracyl derivatives. When two porphyrins having uracyl groups at the different substituted positions were respectively mixed with a melamine derivative in benzene, 1H NMR spectra showed that the 5,15 substituted uracyl porphyrin formed a hydrogen‐bonded suprastructure with the melamine derivative as a complementary molecule to the uracyl moiety, although the other 5,10‐substituted uracylporphyrin could not form such a structure. The SEM observation indicated that the mixture with the 5,15‐substituted uracyl porphyrin and the melamine with long alkyl chains formed a sheet‐like structure. Copyright © 2007 John Wiley & Sons, Ltd.
Use of RNA interference to elucidate the effect of MYCN on cell cycle in neuroblastoma
Authors: Woo Chan‐Wook , Tan Fei , Cassano Hope , Lee JungHwa , Lee Kwang Chul , Thiele Carol J.
Published: April 2007

Background

MYCN amplification marks poor prognosis in neuroblastoma (NB) tumors. In evaluating the mechanisms by which retinoic acid (RA) or nerve growth factor (NGF) decrease cell number in MYCN amplified NB cells, we have identified a number of proteins whose expression either decreases (E2F, CDC2, CDK6, cyclin dependent kinase activity) or increases (p27) in association with a decrease in MYCN expression. However, it was still unclear which were MYCN dependent effects or not.

Procedure

This study aimed to determine which changes in cell cycle gene expression are modulated as a consequence of the decrease in MYCN. We silenced MYCN expression using siRNA targeted to the coding region of MYCN. Then, by using siRNA transient transfections, we analyzed the change of cell cycle related genes and cell cycle in MYCN amplified NB cell lines.

Results

We demonstrate that expression of MYCN can be suppressed by almost 60% in MYCN amplified NB cell using siRNAs targeted to MYCN. Functionally, the decrease in MYCN leads to a decrease in cells in the S‐phase of the cell cycle. Decreases in MYCN are associated with decreases in E2F1‐2 and ID2 along with increases in p27 protein levels by post‐transcriptional modification. Moreover, we find that a decrease in MYCN is accompanied by a decrease in cdk6 mRNA and protein expression.

Conclusions

These results show that E2F and ID2 expression is associated with MYCN regulation and that cdk6 is a possible new transcriptional target of MYCN. Pediatr Blood Cancer 2008;50:208–212. © 2007 Wiley‐Liss, Inc.
Initial testing (stage 1) of the proteasome inhibitor bortezomib by the pediatric preclinical testing program
Authors: Houghton Peter J. , Morton Christopher L. , Kolb E. Anders , Lock Richard , Carol Hernan , Reynolds C. Patrick , Keshelava Nino , Maris John M. , Keir Stephen T. , Wu Jianrong , Smith Malcolm A.
Published: April 2007

Background

Bortezomib is a proteasome inhibitor that has been approved by FDA for the treatment of multiple myeloma and that has completed phase 1 testing in children. The purpose of the current study was to evaluate the antitumor activity of bortezomib against the in vitro and in vivo childhood cancer preclinical models of the Pediatric Preclinical Testing Program (PPTP).

Procedures

Bortezomib was tested against the PPTP in vitro panel at concentrations ranging from 0.1 nM to 1.0 µM and was tested in vivo at a dose of 1 mg/kg for a planned duration of 6 weeks.

Results

Bortezomib was uniformly active against the PPTP's in vitro panel, with a median IC50 of 23 nM and with a steep dose–response curve. The four acute lymphoblastic leukemia (ALL) cell lines had significantly lower IC50 values compared to the remaining lines of the in vitro panel. Limited in vivo activity was observed for bortezomib against the solid tumor xenografts tested, with one line meeting criteria for intermediate activity for the time to event measure and with the remaining lines showing low activity for this measure. Bortezomib demonstrated in vivo activity against the ALL panel, inducing two complete and two partial responses among seven evaluable lines.

Conclusions

Administered at its MTD in mice, bortezomib demonstrated activity against selected lines of the PPTP's ALL in vivo panel. Further studies are indicated to determine the activity of bortezomib when combined with standard agents to treat childhood ALL. Pediatr Blood Cancer 2008;50:37–45. © 2007 Wiley‐Liss, Inc.
Study on change in the degree of polymerisation of bacterial cellulose produced by Acetobacter xylinum during its cultivation
Authors: Okajima Kunihiko , Matsuda Yukiko , Kamide Kenji
Published: April 2007

An attempt was made to clarify the change in the viscosity‐average degree of polymerisation (Pv) of a bacterial cellulose within a cell cycle using the technique of synchronous static culture conditions of an acetic acid bacterium (Acetobacter xylinum), formerly established by us (British Polymer J., 22 (1990) 167). Under these conditions the yield of bacterial cellulose and its Pv were found to increase stepwise within a cell cycle. Furthermore, Pv of the cellulose increased rapidly in the cultivation stage where the production rate of cellulose is quite low. As soon as the cultivation went into the first stage where Pv of the bacterial cellulose increased very slowly, its infrared absorbance for C—O stretching with parallel infrared dichroism strongly increased. The maximum Pv attainable for cellulose obtained under the synchronous culture conditions used here was c. 1500. The time length of a cell cycle for the synchronous culture was controlled by adjusting the air supply.
On the nature of junction zones in gelatin gels
Authors: Mel'Nichenko Yu. B. , Gomza Yu. P. , Shilov V. V. , Osipov S. I.
Published: April 2007

The structural modifications and the phase state of the gelatin matrix during the sol‐gel transition and gelatin gel deswelling were studied by optical rotation and wide‐angle X‐ray scattering (WAXS) methods. It is shown that the quenching of a solution results in rapid renaturation of macromolecular fragments of gelatin and in collagen‐like structures forming junction zones in the polymer network. Microcrystallites in the polymer matrix of gelatin gels were not revealed which shows that the aggregation of renaturated helices and the formation of collagen‐like fibrillar crystals do not occur. However, the crystalline phase appears upon gel drying or its deswelling in a nonsolvent.
Radical polymerization of methyl acrylate initiated by styrene‐arsenic sulphide complex
Authors: Shukla Prerna , Srivastava A. K.
Published: April 2007

A styrene‐arsenic sulphide complex in DMSO at 85 ± 0.1°C initiates radical polymerization of methyl acrylate over 90 min under a N2 blanket. Conversion reaches 83% without gelation and results in the formation of polymer having average degree of polymerization 710. Analysis of the kinetic data (up to 29% conversion) indicates that the system follows ideal kinetics. The reaction is retarded by hydroquinone. The overall activation energy and value of k2p/kt are 96 kJ mol−1 and 6.9 × 10−3 litre mol−1 s−1, respectively.
A simple procedure for assessing the protective effect of transparent polymer films used for packaging foods containing light‐sensitive nutrients
Authors: Korman N. , Orbey N. , Özilgen M.
Published: April 2007

Sensitive components of foods may undergo degradation reactions when subjected to light. The packaging of the food may slow down such reactions by absorbing and reflecting a fraction of the incident light. Riboflavin is a typical lightsensitive nutrient and undergoes first‐order degradation when subjected to light. Rate constants of this reaction were evaluated under 25W, 60W, 100W and 200W white light bulbs at pH = 8, at 20±1°C, with no light shielding or by shielding the light with a single fold of high density polyethylene or two folds of low density polyethylene films. Numerical values of the reaction rate constants were proportional to the light source power and varied with the number of polymer films. The proportionality constant was regarded as the ‘protection index’ of the specific film. The results implied that the smaller the protection index of the film the smaller was the degradation reaction rate constant. Although this study was done by employing two different kinds of polymer films and one light‐sensitive chemical only, this approach may be employed for comparing the packaging efficiency of polymers used for wrapping foods containing light‐sensitive components.
Electron conduction in fe‐doped polystyrene films
Authors: Sharma A. K. , Adinarayana V. , Sagar D. S.
Published: April 2007

The DC electrical conductivity of pure and Fe3+‐doped polystyrene films has been studied at various bias field strengths in the temperature range 304–392K. Doped films showed increased conductivity compared with undoped films up to 0.5% dopant concentration; beyond this concentration there was a decrease in the conductivity. The increase in conductivity for lower doping concentrations (0.25% and 0.5%) is attributed to the formation of charge transfer complexes. The decrease in the electrical conductivity and the increase in the activation energy at more than 0.5% dopant concentration is due to the formation of molecular aggregates. For undoped films the activation energies in the low temperature region were found to be higher than those at higher temperatures. Also, with increasing bias field strength, the activation energies showed a decrease at all temperatures studied. It is suggested, on the basis of the magnitudes of the activation energies, that electronic conduction is the dominant charge transport mechanism both at low and high temperatures.
Study of mechanical properties and morphology of interpenetrating polymer networks from castor oil based polyurethane and polystyrene
Authors: Suthar Bhikhu , Parikh Nilesh , Patel Nimish
Published: April 2007

Polyurethane‐polystyrene sequential interpenetrating polymer networks have been synthesized from castor oil, diphenylmethane diisocyanate, styrene, ethylene glycol dimethacrylate as a crosslinker and benzoyl peroxide as an activator. The interpenetrating polymer networks were obtained as tough and transparent films by a transfer moulding technique. These IPNs were characterized by mechanical properties, viz. tensile strength, Young's modulus, elongation at break and Shore A hardness, and crosslink density. The morphological behaviour was studied by dynamic mechanical analysis and scanning electron microscopy.
Modelling permeation of modified atmosphere gas mixtures through a low density polyethylene package film
Authors: Llter M. , Özilgen M. , Orbey N.
Published: April 2007

Permeation of individual gases through a low density polyethylene package film with CO2‐N2 and CO2‐O2‐N2 mixtures was simulated with a simple mathematical model. Permeabilities of carbon dioxide were of the order of 10 −12 m3/s m2atm/m with CO2‐N2 systems. Including oxygen in the system did not change carbon dioxide permeabilities. Permeabilities of oxygen were of the order of magnitude of 10−9m3/sm2atm/m with this system. When a CO2‐O2‐N2 mixture was humidified no substantial change was observed in CO2 permeability, but the O2 permeability decreased almost 10 times. These results and the mathematical model presented may help in the modified atmosphere package design to increase the shelf life of produce.
Preparation and anti‐microbial properties of friedel—crafts resins
Authors: Patel N. Z. , Patel J. N. , Ray R. M. , Patel R. M.
Published: April 2007

Friedel‐Crafts resins were prepared by reacting chloroacetyl chloride, 1,2‐dichloroethane and dichloromethane with m‐xylene using carbon disulfide as solvent and anhydrous AlCl3 as catalyst. The resins were characterized by IR spectra and number average molecular weight measured by vapour pressure osmometry. The thermal properties were studied by thermogravimetry and differential scanning calorimetry. All the resins were tested for their microbial activity against Pseudomonas fluorescens, Bacillus subtilis and Aspergillus niger. The results show that most of the resins can be used as biocides.
An inverse gas chromatographic study of compatibility of food grade PVdC copolymer and low volatility plasticizers
Authors: Demertzis Panagiotis G. , Riganakos Kyriakos A. , Akrida‐Demertzi Konstantoula
Published: April 2007

The compatibilities of the systems poly(vinylidene chloride‐vinyl chloride 80:20)/polyadipate ester and poly(vinylidene chloride‐vinyl chloride 80:20)/tri‐isononyl trimellitate have been studied in the range 90–110°C using inverse gas chromatography (IGC). The retention behaviour of the polymer/plasticizer mixtures covering the entire composition range for each component was characterized for 10 probes of different chemical nature. In agreement with previous work, the IGC‐derived interaction parameters (X+23) showed an apparent dependence on the chemical nature of the probe, blend composition and temperature. The results predict good polymer/plasticizer compatibility up to c. 0–40 weight fraction of plasticizer for poly(vinylidene chloride‐vinyl chloride 80:20)/polyadipate ester blends and to c. 0.50 for poly(vinylidene chloride‐vinyl chloride 80:20)/tri‐iso‐nonyl trimellitate blends.
Radical polymerization of itaconic anhydride and reactions of the resulting polymers with amines and alcohols
Authors: Otsu Takayuki , Yang Jian‐Zhong
Published: April 2007

Itaconic anhydride was polymerized in the presence of a radical initiator under various conditions. The bulk polymerization at 75°C yielded polymer with molecular weight of more than 20000.

The reactions of the resulting polymer with water and alcohols gave poly(itaconic acid) and its esters, respectively. The polymers prepared by such reactions were found to have similar thermal properties to those prepared by homopolymerizations of the respective itaconic acid derivatives.

Poly(N‐substituted itaconomic acid)s, which are difficult to obtain by direct polymerization of their monomers, were prepared by the reactions of poly(itacononic anhydride) with amines.

Copolymerizations of itaconic anhydride with electron‐donating monomers, styrene and isobutyl vinyl ether, gave alternating copolymers which were then converted by esterification to the respective copolymers of dialkyl itaconates with such electron‐donating monomers.
Chain‐extended polyurethanes—Synthesis and characterization
Authors: Ramesh S. , Rajalingam P. , Radhakrishnan Ganga
Published: April 2007

Thermoset polyurethane (PU) elastomers were prepared using hydroxyl‐terminated polybutadiene (HTPB), toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI). The effects of various diamines and diols on the mechanical and thermal properties of polyurethanes are discussed. The average molecular weight between crosslinks (M̄/c) was determined by swelling studies. The properties imparted by the extenders are explained on the basis of the groups present in the diamines and the number of methylene carbons in the diols.
Toughening of epoxy resins with thermoplastics. Ii. Tetrafunctional epoxy resin‐polyetherimide blends
Authors: Hourston Douglas J. , Lane Jaqueline M. , Macbeath Nigel A.
Published: April 2007

A series of blends has been prepared by adding a polyetherimide (PEI), in varying proportions, to a tetrafunctional epoxy resin, tetraglycidyl‐diaminodiphenylmethane (TGDDM), cured with 4,4′‐diaminodiphenylsulphone (DDS). All the materials exhibited two‐phase morphologies which were characterised by dynamic mechanical thermal analysis and scanning electron microscopy. Addition of the thermoplastic gave a modest improvement in fracture properties (K1c and G1c), as determined by three‐point bending experiments, although no obvious correlation with the marked morphological changes was observed.
Recent developments in the gpc characterisation of polymeric materials
Authors: Meehan Elizabeth , McConville John A. , Warner Frank P.
Published: April 2007

Mixed gel GPC columns are specifically designed for the determination of polymer molecular weight distribution. The choice of column pore size distribution and particle size significantly affects resolution. Although optimum resolution is deirable, 5 μm particle size columns are not ideal for the analysis of polymers containing significant quantities of material above 1 million molecular weight as shear degradation of the polymer is likely to occur.

Both narrow standard and broad standard methodolgies are suitable for the calibration of mixed gel GPC column systems. Using well‐characterised polydisperse polystyrene test probes, no difference in accuracy was found between the two procedures.
The application of luminescence techniques in polymer science
Authors: Soutar Ian
Published: April 2007

The luminescence phenomenon represents an extremely versatile and sensitive means whereby the physical behaviour of polymers may be examined at the molecular level. This review initially describes the ‘tools of the trade’ (the parameters which, in combination, confer high degrees of selectivity upon the technique) prior to discussion of their use. The account is illustrated by examples drawn mainly from the author's laboratory and includes applications of energy transfer, excimer formation and anisotropy experiments.
Alternating copolymers from the radical copolymerization of citraconic derivatives with isobutyl vinyl ether
Authors: Yang Jian‐Zhong , Otsu Takayuki
Published: April 2007

Radical copolymerization of citraconic anhydride (CAn) with isobutyl vinyl ether (IBVE) was studied as well as the copolymerizations of N‐alkylcitraconimides, dialkyl citraconates and mesaconates with IBVE. All the copolymerizations attempted except one, incorporating N‐alkylcitraconimide, were found to give alternating copolymers with molecular weights of more than 10,000 in most cases. Of all the copolymerizations, the CAn‐IBVE system showed the highest reactivity. A charge transfer complex between these two monomers was confirmed to exist in this system. The equilibrium constant of the complex formation was determined by UV spectroscopy as 0–162 litre/mol in CHCl3 at 15°C.

The alternating copolymer obtained from CAn with IBVE was converted to the corresponding copolymer of dialkyl citraconate by esterification.
Viscosity behaviour of acrylonitrile‐acrylate copolymer solutions in dimethyl formamide
Authors: Joseph Roychen , Devi Surekha , Rakshit Animesh Kumar
Published: April 2007

The viscosities of dimethyl formamide solutions of acrylonitrile‐acrylate copolymers were determined at 30,35,40 and 45°C using an Ubbelohde viscometer. The viscosities of homopolymer solutions were also studied. The homopolymers of aerylonitrile and also of methyl, ethyl and butyl acrylates were synthesised in the laboratory. The random copolymers were synthesised by a solution polymerisation technique keeping the acrylonitrile: acrylate ratio as 1:1, 1:2 and 1:3 (w/w). The intrinsic viscosity for each system was computed as a function of temperature. The activation parameters of viscous flow were calculated using the Frenkel‐Eyring equation. Voluminosity for all systems was also computed. From intrinsic viscosity and voluminosity data it was concluded that the polymer molecules are spherical in the dimethyl formamide solutions.
Organolithium route to poly(arylsilane)s
Authors: Albizane Abderrahman , Corriu Robert J. P. , Douglas William E. , Fisch Herbert
Published: April 2007

Various poly(arylsilane)s magnified image

The poly(carbosilane)s prepared in this way are of higher molecular weight than when prepared by the Wurtz‐type condensation route previously reported. TG shows 40–50% overll weight loss attained at 500–600°C.
Unperturbed dimensions of a zwitterionic polymethacrylate
Authors: Huglin Malcom B. , Radwan Mostafa A.
Published: April 2007

Values of intrinsic viscosity [ζ] measured in 2,2,2‐trifluoroethanol (TFE) and in 1·0M aq. NaCl solution mean square radii of gyration s2z and weight‐average molecular masses Mw measured in TFE at 298 K for 12 well fractionated poly[N‐(3‐sulphopropyl)‐N‐methacrylooxyethyl‐N,N‐dimethylammonium betaine] (PSPE) samples have been used to derive the unperturbed dimensions (<r20/M)1/2 via different extrapolation procedures.

Cloud point curves for PSPE fractions in 0‐05M aq. NaCl yielded an upper critical solution temperature (0) of 308 K, which was confirmed turbidimetrically, visco‐metrically, and by light scattering, thus enabling the unperturbed dimensions to be determined directly.

The mean value of (r20/M)1/2 by all procedures was 0‐052nm g‐1/2 mol1/2 which, in conjunction with the corresponding quantity calculated on the basis of free rotation, affords a value of 2‐83 for the steric factor α.

From values of [ζ] in 2·0M aq. NaCl solution over the interval 283–343 K, the value of dlnr2o/dT was derived as −8·5 × 10−4 deg−1. The values of the long range interaction parameter β and the interaction parameter χ confirm that TFE is a thermodynamically better solvent than l·0M aq. NaCl solution for PSPE.
Anionic polymerization by tertiary amine/epoxide complex
Authors: Ikeda Isao , Mitsumoto Seiichi , Yamada Yuichi , Suzuki Kimihiro
Published: April 2007

The anionic polymerization of monomers such as acrylonitrile (AN) and ε‐caprolactone by triethylenediamine (TEM)/epoxide complex was investigated. They were not polymerized by TEM alone but polymerized easily with the addition of various epoxides. When glycidyl methacrylate (GMA) and allyl glycidyl ether (AGE) were used as the epoxide component, a double bond was introduced at the end of the polymer. Thus the macromonomers were prepared with the polymerization by TEM/GMA and TEM/AGE complexes. Macromonomers prepared with GMA were copolymerized with comonomers such as AN, styrene, acrylamide and methyl methacrylate to prepare the graft copolymers.
Effect of installation damage on the lifetime of upvc pipes subjected to cyclic pressures
Authors: Burn L. Stewart
Published: April 2007

A survey of pipe installation damage in Australia has shown that when pipes are installed in water reticulation systems, they often have significant levels of damage or notches that can be considered as sharp, i.e. less than 25 μm notch tip radius. Experimental investigations of the effect of simulated sharp notches of varying depth on uPVC pipes subjected to a representative cyclic pressure regime show that there is a relationship between the depth of the notch and the cycles to failure. With damage less than 1·2 mm deep, corresponding to a stress intensity factor of 0·2 MPa,m, a fatigue crack threshold exists, below which cracks do not grow and consequently pipe lifetimes in excess of 100 years can be expected for pipes installed under such cyclic pressure conditions.
Electrically conductive composite of polyaniline and poly (p‐phenylene/diphenyl ether‐terephthalamide)
Authors: Bi Xian‐Tong , Xue Zhe‐Jian
Published: April 2007

In order to improve the flexibility and the anti‐static properties of poly‐(p‐phenylene‐terephthalamide) (PPTA), the copolymer of p‐phenylene diamine, p,p′‐diaminodiphenyl ether and terephthaloyl chloride (PPDTA) was synthesized. This copolyamide PPDTA was mixed with electrically conductive polyaniline (PAn) in concentrated sulphuric acid solution, and was processed to form film, or fibre, of the new composite PAn/PPDTA with high strength and good electrical conductivity. The composite is a lyotropic liquid crystalline polymer with electrical conductivity 10−1 S/cm. The surface morphology of the PAn/PPDTA composite consists of an oriented fibre‐like texture.
Morphology of block copolymers and associated networks
Authors: Jones Jennifer J. , Burford Robert P.
Published: April 2007

Interpenetrating polymer networks (IPNs) of styrene‐butadiene‐styrene (SBS) block copolymers and polystyrene (PS) were prepared by sequential polymerisation. TEM micrographs of both the constituent block copolymers and their IPNs were obtained after staining with osmium tetroxide. It was found that images obtained after cryo‐ultramicrotoming of bulk samples were a more legitimate representation of block copolymer morphology than those obtained from solvent‐cast samples. Micrographs of both semi‐IPNs and true‐IPNs and bulk block copolymer reveal distinct microphase separation. An anisotropic domain morphology is found, with polybutadiene (PBD) being the continuous phase containing PS‐rich domains. Domain dimensions change with cross‐linking and block copolymer type. Image analysis and small angle X‐ray data were obtained to provide further quantitative information.
13C NMR spectral assignments of methacrylic acid/acrylonitrile statistical copolymers
Authors: Borbely Janos D. , Hill David J. T. , Lang Anthony P. , O'Donnell James H.
Published: April 2007

Copolymerization of methacrylic acid (M) and acrylonitrile (A) in bulk at 60°C gives a statistical copolymer. Through the use of 1H, 13C, DEPT and twodimensional NMR techniques, the observed resonances in the NMR spectra of these copolymers can be assigned, and thus provide detailed information about the microstructure of the polymer at the diad, triad and tetrad levels. Configurational effects have also been shown to play an important role, although in all cases the chemical shift differences resulting from configurational variation are smaller than those resulting from sequence variation.
Thermal decomposition of poly (1,6‐di‐n‐carbazolyl‐2,4‐hexadiyne)
Authors: Bradner F. P. , Shapiro J. S.
Published: April 2007

The kinetics of the thermal decomposition of the crystalline poly(1,6‐di‐N‐carbazolyl‐2,4‐hexadiyne) prepared by γ‐radiation induced polymerisation were studied over the temperature range 380‐450°C by means of a flow system, coupled to a gas chromatograph. Two major volatile reaction products were found: carbazole and 9‐methylcarbazole, leaving behind a carbonaceous residue. The reaction was found to be complex with two autoacceleratory regions followed by a very slow limiting rate after 65% weight loss. Whereas the magnitude of the first of these regions was found to be dependent on factors influencing the level of crystal purity and perfection, the second region was independent of these. A reaction mechanism is proposed, based on initiation by stress‐induced shearing of sidegroups, followed by concurrent molecular/radical non‐chain processes. The kinetics of the decomposition were found to be best described by the Avrami‐Erofeyev equation, and the Arrhenius parameters were determined for both autoacceleratory processes.
Dielectric properties of poly(vinyl chloride) in tetrahydrofuran and cyclohexanone
Authors: Salem M. B. , Oun A. M. , Omar M. M.
Published: April 2007

The dielectric absorption and dispersion of poly(vinyl chloride), MMv = 49 000, in THF and in cyclohexanone have been studied over a frequency range of 120 kHz to 11·0 MHz, at temperatures from −22·5 to 35°C, and at concentrations ranging from 4 to 12·0(w/v)% PVC/THF and from 2 to 8·0(w/v)% PVC/cyclohexanone. The viscosities of the two systems have also been measured at temperatures from 20 to 50°C. A single relaxation time was found (β = 0·8–1·0), which indicates that relaxation occurs by segmental rotation. The dielectric and viscous activation energies have been calculated. The dipole moment associated with the relaxation process has also been calculated. The relaxation time, dielectric and viscous activation energies and the dipole moment were found to be dependent on the type of solvent. The dipole moment also showed a molecular weight dependence. The influence of the concentration and temperature on the apparent dipole moment and on the relaxation time is discussed.
Dynamic properties of elastomers after water immersion
Authors: Oldfield David , Jackson Peter J. , Russo Sarina
Published: April 2007

Vulcanized bromobutyl, natural and nitrile rubbers were immersed in distilled water, or seawater, at 20, 40 or 60°C for up to 32 weeks and the resulting changes in weight and dynamic mechanical properties were monitored. Larger weight increases were observed for the specimens immersed in distilled water than for the equivalent specimens in seawater, and there was no sign of an equilibrium weight uptake being reached for the specimens immersed in distilled water at 60°C. Bromobutyl rubber showed increases in the magnitude of the loss tangent peak which could be related to the weight increases in both distilled water and seawater but the decreases in peak height observed for natural rubber and nitrile rubber were not well correlated with weight increases.
Thermal ageing studies of conducting polypyrroles
Authors: Moss Brett K. , Burford Robert P.
Published: April 2007

Conductive polymeric films have been of great interest recently, although one major drawback to their use is environmental stability. Polypyrroles doped with p‐toluenesulfonate, tetrafluoroborate and perchlorate anions were examined under elevated temperatures and environments. The use of d.c. electrical conductivity decay measurements and fitting of kinetic models allows changes in bulk properties to be examined. Surface characterisation performed by X‐ray photoelectron spectroscopy (XPS) enables detailed investigation into changes in chemical states of surface atoms. The mechanisms described for the change in electrical and structural properties may be attributed to polymer backbone oxidation through free radical oxygen insertion and electrolyte dopant degradation.
New chain transfer agents for free radical polymerizations
Authors: Meijs Gordon F. , Rizzardo Ezio , Le Tam P. T.
Published: April 2007

The palmitoyl ester of N‐hydroxypyridine‐2‐thione displayed useful chain transfer properties in free radical polymerizations of methyl methacrylate and styrene. Retardation, however, accompanied the lowering of molecular weight in methyl acrylate and vinyl acetate polymerizations.

4‐Methyl‐3‐palmitoyloxythiazol‐2(3H)‐thione had good chain transfer activity with methyl methacrylate, styrene and methyl acrylate. Although benzyl thionobenzoate exhibited virtually ‘ideal’ behaviour (chain transfer constant Cx ∼1) in styrene and methyl acrylate polymerizations, it was ineffective in lowering molecular weight of poly(methyl methacrylate). Severe retardation was observed with vinyl acetate.

Addition‐fragmentation pathways are postulated for chain transfer.
Development and characterisation of polypyrrole/metal junctions for electronic applications
Authors: Unsworth Joe , Jin Zheshi , Lunn Brett A. , Innis Peter C.
Published: April 2007

Preliminary results are presented on the fabrication and analysis of junctions formed between metals and semi‐conducting and conducting polypyrrole. Rectifying junctions were observed between aluminium and indium with semi‐conducting polypyrrole in a sandwich geometry using current‐voltage (I‐V) and capacitance‐voltage (C‐V) analysis techniques, respectively. All planar junctions analysed were non‐rectifying, while both gold and platinum were observed to form ohmic junctions in both the sandwich and planar geometries. Preliminary analysis using ideal Schottky barrier theory was attempted with various junction parameters determined, with significant deviation from the ideal theory observed. It is proposed that this deviation is due to the synthesis history of the polymer and the presence of an insulating oxide layer between the polymer and the metal.
In‐chain functionalization by alternating anionic copolymerization of styrene and 1‐(4‐dimethylaminophenyl)‐1‐phenylethylene
Authors: Quirk Roderic P. , Zhu Linfang
Published: April 2007

Anionic copolymerizations of styrene (M1) with excess 1‐(4‐dimethyl‐aminophenyl)‐1‐phenylethylene (M2) were conducted in benzene at 25°C for 24h, using sec‐butyllithium as initiator. Narrow molecular weight distribution copolymers with M̄;n = 16.1 × 103 g/mol (M̄w/M̄n = 1.04) and 38.2 × 103g/mol (M̄w/M̄n = 1.05), and 24 and 38 moles of M2 per macromolecule, respectively, were characterized by size exclusion chromatography, 1H NMR spectroscopy and DSC. The monomer reactivity ratio, r1 = 5.6, was obtained from the copolymer composition at complete consumption of M1, assuming that the rate constant k22 =0,i.e. r2 =0. The polymers exhibited Tg values of 128 and 119°C, respectively, which correspond to an estimated Tg = 217°C for the hypothetical homopolymer of M2.
Polyesters from lignin. 1. The reaction of kraft lignin with dicarboxylic acid chlorides
Authors: Guo Zhao‐Xia , Gandini Alessandro , Pla Fernand
Published: April 2007

Kraft lignin was treated with dicarboxylic aliphatic (sebacoyl) or aromatic (terephthaloyl) acid chlorides in N,N‐dimethylacetamide or N‐methyl‐2‐pyrrolidone as solvents in the presence of triethylamine or pyridine as catalysts. The polyester gels obtained were characterized by IR after specific extractions and the chemical incorporation of lignin was proved unambiguously. Their thermal behaviour was determined by DSC and TGA; they are amorphous and stable up to 200°C in a nitrogen atmosphere. The reactivities of the two types of hydroxyl group (aliphatic and phenolic) were assessed from model reactions carried out in the same conditions.
Synthesis and characterization of high molecular weight water‐soluble polymers
Authors: Hunkeler D.
Published: April 2007

The synthesis of high molecular weight acrylic water‐soluble polymers in heterophase water‐in‐oil polymerizations is discussed. A mechanism has been elucidated which includes elementary reactions in the continuous (organic) and dispersed (aqueous) phases, as well as the interfacial layer. The latter allows for the identification of interfacially active species which can concurrently enhance stability and increase the linear molecular weight of the polymer. Suitable species are found to contain multiple radically active functional groups on either the hydrophilic or hydrophobic moieties.

A one‐point light‐scattering method is also developed which improves the accuracy in molecular‐weight estimation to /pi5%. compared with /pi10% for the conventional dilution procedure. This is demonstrated for high molecular weight polyacrylamides and is found to reduce the sample measurement time fourfold, to 20 min.
Studies on polymer latex films: II. Effect of surfactants on the water vapour permeability of polymer latex films
Authors: Roulstone B. J. , Wilkinson M. C. , Hearn J.
Published: April 2007

Poly(butyl methacrylate) films have been prepared from surfactant‐free latices which had post‐added commonly used latex stabilisers. Water vapour transmission rates were used to study film permeability in relation to morphology, which was also studied by freeze fracture replication transmission electron microscopy. The extent of latex coalescence depended upon the chemical nature of the stabiliser employed and at monolayer coverage was not necessarily deleterious to the barrier properties of the films.
Chemical modification of crosslinked phenyl acrylate copolymers with monoethanolamine
Authors: Narasimhaswamy T. , Sumathi S. C. , Reddy B. S. R. , Devasagayam G. D.
Published: April 2007

Copolymerisation of phenyl methacrylate, 4‐chlorophenyl acrylate, 4‐nitrophenyl acrylate and 2,4,6‐tribromophenyl acrylate with divinyl benzene was carried out in aqueous suspension medium at 80°C using benzoyl peroxide as radical initiator. The resulting beaded copolymers were characterised by FTIR. optical and scanning electron microscopy. Polymer analogue reactions of these particulate copolymers with monoethanolamine were carried out at 60.80 and 100°C in dimethyl sulphoxide as solvent. The progress of the reactions was followed by observing the disappearance of phenyl ester carbonyl absorption at 1750 cm−1 and the appearance of 1650cm−1 vibration corresponding to the characteristic amide carbonyl. The percentage conversions were calculated, and the effect of polar substituents in the phenyl acrylates as well as temperature on the reaction are discussed.
Free radical solution copolymerization of glycidyl methacrylate with n‐vinyl pyrrolidinone
Authors: Wen Shao , Xiaonan Yin , Stevenson William T. K.
Published: April 2007

Copolymers of glycidyl methacrylate (monomer 1) with N‐vinyl pyrrolidinone (monomer 2) were prepared at 70°C in low yield by free radical initiated solution polymerizations in ethyl acetate, 1,4‐dioxane and mixtures of the two solvents. Copolymer compositions were determined by proton nuclear magnetic resonance spectroscopy. Monomer reactivity ratios were then derived using the method of Kelen & Tudos. The magnitude of r1 was relatively unaffected by solvent composition, and ranged from 4.32 to 4.53 in a random fashion. In contrast, values of r2 showed a greater relative (but still random) spread from 0.0075 to 0.0147. Copolymers prepared by batch polymerization are selectively enriched with GMA monomer.
Free radical initiation mechanisms in copolymerisation studied by the nitroxide trapping technique
Authors: Ken Busfield W. , Darren Grice I. , Jenkins Ian D.
Published: April 2007

The initiation mechanism for the radical copolymerisation of vinyl acetate, a typical electron donor monomer, and acrylonitrile, a typical electron acceptor monomer, initiated by t‐butoxy radicals, has been investigated by the nitroxide radical trapping technique: 1,1,3,3‐tetramethyl‐1,3‐dihydroisoindol‐2‐yloxyl (T) was the radical trapping agent.

Two adducts (diastereomers) containing both vinyl acetate and acryionitrile monomers were isolated. From a kinetic analysis of these and other products over a wide range of conditions, a mechanism involving separate monomer addition, which may be regarded as normal kinetic control of monomer addition, is shown to be most consistent with the observed results.
On hybrid toughened DGEBA epoxy resins
Authors: Low I. M. , Bandyopadhyay S. , Mai Y. W.
Published: April 2007

Considerable improvements in the fracture resistance of epoxy resins have recently been achieved by adding either rubbery or rigid second phase dispersions, or both, to an epoxy matrix. These multiphase epoxy systems are particularly useful as high performance adhesives and as matrix materials in advanced composites. This paper describes the development of new toughened epoxy hybrids, which contain both rubbery and rigid dispersions. The latter dispersions were either zirconia particles, short alumina fibres or glassy‐metal ribbons. Micromechanisms of toughening and failure processes in these new materials are identified and discussed in the light of microstructures.
Silicones on glass surfaces
Authors: Bennett David R. , Matisons Janis G. , Netting Angus K. O. , Smart Roger St C. , Swincer A. Geoffrey
Published: April 2007

X‐Ray photoelectron spectroscopy can be applied to the study of the bonding of highly functionalised silicones on to E‐glass fibres. The adsorption of six types of silicones (hydrido, epoxy, unsaturated imino, methacryl. ‘terminal’ amino and ‘pendant’ amino) from dilute toluene solutions were compared with that of a standard silane coupling agent. The calcium concentration was found to be an effective determinant of surface coverage by the siloxanes. as well as enabling the thicknesses of the adsorbed layers to be determined.
Properties of a semi‐crystalline and an amorphous thermotropic liquid crystalline polymer
Authors: Turek Douglas E. , Simon George P.
Published: April 2007

The physical properties, thermal stability, rheology and tensile properties of a commercial semi‐crystalline and an amorphous thermotropic liquid crystalline polymer (TLCP) have been investigated. Analysis by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) confirm the presence of a small melting endotherm and a glass transition in the former material. The as‐received amorphous TLCP exhibits no obvious melting endotherm and a strong glass transition is detected. The flow and tensile properties of the semicrystalline polymer are dominated by the presence of the crystalline to nematic transition temperature. The properties of the amorphous TLCP appear to be governed by increasing mobility afforded by increasing temperature. Based on flow behaviour and further DSC analysis it has been shown that under appropriate annealing conditions the as‐received amorphous TLCP can develop solid crystalline order.
Thermotropic Liquid Crystalline Aromatic Copolyesters with Flexible Spacers
Authors: Bao Jing‐Sheng , Fan Hong‐Ni
Published: April 2007

Two series of thermotropic liquid crystalline polymers were prepared from hydroquinone, methylhydroquinone, 2,5‐dichloroterephthaloyl chloride and four terephthalates with varying length substituents. Some of the properties of the terephthalates and polymers were characterized by IR, elementary analysis, differential scanning calorimetry (DSC), X‐ray diffraction and polarized hot‐stage microscopy.