bluuebunny/crossref_metadata_2025 huggingface dataset:
Baculoviral Vector-Mediated Transient and Stable Transgene Expression in Human Embryonic Stem Cells
Authors: Zeng Jieming , Du Juan , Zhao Ying , Palanisamy Nallasivam , Wang Shu
Published: April 2007

Human embryonic stem (hES) cells as a renewable cell source have great prospective applications in both developmental biology research and regenerative medicine. To realize these potentials, the development of effective and safe genetic manipulation methods in hES cells is an obvious demand. We report here that baculoviral vectors were able to transduce hES cells efficiently. In transient transduction experiments, a recombinant baculoviral vector equipped with a human elongation factor 1-α promoter and a woodchuck hepatitis post-transcriptional regulatory element transduced up to 80% of cells in hES cell clumps and embryoid bodies. For prolonged transgene expression, hybrid baculoviral vectors that have incorporated a rep gene and inverted terminal repeat sequences from adeno-associated virus were produced. These hybrid vectors yielded stable transgene expression during the prolonged undifferentiated proliferation of hES cells and after differentiation. Baculoviral transduction did not affect the normal growth, phenotype, and pluripotency of hES cells. Thus, baculoviral vectors suitable for both transient overexpression and long-term stable expression are an attractive option for genetic manipulation of hES cells.

Disclosure of potential conflicts of interest is found at the end of this article.
In situ-based effects measures: Considerations for improving methods and approaches
Authors: Liber Karsten , Goodfellow William , den Besten Pieter , Clements Will , Galloway Tamara , Gerhardt Almut , Green Andrew , Simpson Stuart
Published: April 2007

In situ-based effects measures have gained increased acceptance as a means to improve the link between cause and effect in aquatic ecotoxicological studies. These approaches have primarily been employed where more conventional laboratory tests with field collected samples and routine in-field community surveys have failed to provide reasonable answers with respect to causes of toxicity, primary routes of contaminant exposure, and what constitutes ecotoxicologically relevant contaminant levels, at least at a site-specific level. One of the main advantages provided by in situ tests compared to more conventional field-based monitoring approaches is that they provide better control over stressor exposure to a defined population of test animals under natural or near-natural field conditions. In situ techniques can also be used to avoid artifacts related to sampling, transport and storage of contaminated water and sediment intended for laboratory-based toxicity assessment. In short, they can reduce the need for laboratory to field extrapolation and, when conducted properly, in situ tests can provide improved diagnostic ability and high ecological relevance. This paper provides suggestions and considerations for designing in situ studies, choosing test species and test endpoints, avoiding or minimizing test artifacts, best addressing some of the limitations of in situ test techniques, and generally improving the overall quality of the in situ approach chosen.
Developing methods to assess and predict the population level effects of environmental contaminants
Authors: Emlen John M , Springman Kathrine R
Published: April 2007

The field of ecological toxicity seems largely to have drifted away from what its title implies—assessing and predicting the ecological consequences of environmental contaminants—moving instead toward an emphasis on individual effects and physiologic case studies. This paper elucidates how a relatively new ecological methodology, interaction assessment (INTASS), could be useful in addressing the field's initial goals. Specifically, INTASS is a model platform and methodology, applicable across a broad array of taxa and habitat types, that can be used to construct population dynamics models from field data. Information on environmental contaminants and multiple stressors can be incorporated into these models in a form that bypasses the problems inherent in assessing uptake, chemical interactions in the environment, and synergistic effects in the organism. INTASS can, therefore, be used to evaluate the effects of contaminants and other stressors at the population level and to predict how changes in stressor levels or composition of contaminant mixtures, as well as various mitigation measures, might affect population dynamics.
DESYRE: Decision support system for the rehabilitation of contaminated megasites
Authors: Carlon Claudio , Critto Andrea , Ramieri Emiliano , Marcomini Antonio
Published: April 2007

DESYRE (DEcision Support sYstem for the REqualification of contaminated sites) is a GIS-based decision support system (DSS) specifically developed to address the integrated management and remediation of contaminated megasites (i.e., large contaminated areas or impacted areas characterized by multiple site owners and multiple stakeholders). In the DESYRE conceptual design and development the main aspects pertaining to a remediation process—analysis of social and economic benefits and constrains, site characterization, risk assessment, selection of best available technologies, creation of sets of technologies to be applied, analysis of the residual risk, and comparison of different remediation scenarios—were included. The DESYRE DSS is a GIS-based software composed of 6 interconnected modules. In the characterization module, chemical and hydrogeological data are organized in a relational database and contaminants' distributions are mapped by using geostatistic tools. The socioeconomic module addresses the socioeconomic constraints though a fuzzy logic analysis to select the best land use. The risk assessment module is divided into 2 phases. In the preremediation phase, an original procedure allows assessing and representing the spatial distribution of risks posed by contaminants in soil and groundwater, providing a risk-based zoning of the site. Then, in the technology assessment module, a selection of suitable technologies and creation of different technology sets, taking into account both technical requirements and site-specific features, are performed by experts supported by multicriteria decision analysis tools. In the postremediation risk assessment, a simulation of applied technologies provides residual risk maps with related uncertainty maps. Finally, in the decision module, alternative remediation scenarios are described by a set of indices and can be compared and ranked by interested stakeholders using multicriteria decision analysis methodologies. The paper highlights original procedural steps and functionalities of DESYRE and analyzes its main points of strength and potentialities, as well as limits.
Summary and recommendations from a SETAC pellston workshop on in situ measures of ecological effects
Authors: Baird Donald J , Burton G. Allen , Culp Joseph M , Maltby Lorraine
Published: April 2007

The objective of a SETAC Pellston Workshop held in Portland, Oregon, USA, in November 2004 was to evaluate the use of field-based biological effects and exposure techniques in the hazard and risk assessment of aquatic ecosystems, thereby improving the accuracy and relevance of the decision-making process. This objective was addressed by keynote presentations outlining the state of the science and providing case studies, followed by work-group discussions focusing on 4 main areas: 1) Improving stressor-effect diagnostic capability in the assessment process; 2) maximizing efficiency, quality assurance and quality control, and broad-scale applicability of in situ field bioassays and experimental approaches; 3) determining the ecological relevance and consequences of individual and food chain-based effect measures; and 4) incorporating results from field-based effect methods into a weight-of-evidence decision-making process. Major outcomes from group discussions are highlighted, and future priorities for research in this area are recommended.
In situ-based effects measures: Determining the ecological relevance of measured responses
Authors: Baird Donald J , Brown Steven S , Lagadic Laurent , Liess Matthias , Maltby Lorraine , Moreira-Santos Matilde , Schulz Ralf , Scott Geoffrey I
Published: April 2007

The aim of this review is to examine how the choice of test species and study design employed in the use of in situ approaches in ecological risk assessment can maximize the ecological relevance of data. We provide a framework to define and assess ecological relevance that permits study designs to remain focused on the ecological question being addressed. This framework makes explicit the linkages between effects at lower levels of biological organization and higher-order ecological effects at the population, community, and ecosystem levels. The usefulness of this framework is illustrated by reference to specific examples from aquatic ecotoxicology. The use of models as both interpretive and predictive tools is discussed, with suggestions of appropriate methods for different protection goals.
Toward a Still and Quiet Conscience: A Study in Reflexive Archaeology
Authors: Moore Lawrence E.
Published: April 2007

Reflexive behaviors and discussions have become commonplace in archaeology. The first phase of their implementation has already completed, and a new phase has begun. To clarify the purpose of this second phase, we need to again consider why we are doing them, how we are going about them, and, most importantly, where are we going with them. Reflexive perspectives on archaeology are shifting from idealist implementation to realist implementation, from social advocacy to problem solving pragmatism. The completion of this second phase will lead to an expanded definition of archaeology. When the second phase is done, in about 15 years, reflexive perspectives on archaeology will cycle out of fashion. All these changes are associated with generational changes ongoing in American society.
Shadow of Doubt or Doubtful Shadows: Small-Scale Low-Density Lithic Scatters and Agrifacts
Authors: Staley David P.
Published: April 2007

The fundamental identification of flaked stone as artifact is critical to all that follows in archaeology. The identification of sites, interpretations of prehistoric behaviors, adaptations, land use patterns, settlement and subsistence studies, etc. can be distilled to the initial determination of an artifact as being “real” or the result of natural or accidental phenomena such as plow damage. In cultural resource management, artifact identification drives immediate field decisions to modify research strategies and ultimately forms the argumentative basis for research potentials and determinations of significance. Chert flakes and shatter discovered during a NYSDOT sponsored project conducted by New York State Museum-Cultural Resource Survey Program were subjected to a battery of lithic attribute analyses in an attempt to identify artifacts in an agricultural area blanketed by natural chert. With the exception of exotic material types, no single attribute can certainly identify human involvement. A cumulative score of multiple attributes affords greater levels of confidence for cultural vs. natural determinations for larger assemblages. In settings with the “background noise” of natural chert in cultivated soils, cultural genesis determinations of single pieces and very small sparse assemblages must be recognized as hunches or faith-based decisions yet worthy of measured continued investigation.
Bipolar disorder: What can psychotherapists learn from the cognitive research?
Authors: Johnson Sheri , Tran Tanya
Published: April 2007

Randomized controlled trials of psychological treatment, principally cognitive therapy, for bipolar disorder have yielded inconsistent results. Given the status of this evidentiary base, we provide a more fine‐grained analysis of the cognitive profiles associated with bipolar disorder to inform clinical practice. In this practice‐friendly review, we consider evidence that both negative and positive cognitive styles are related to bipolar disorder. Cross‐sectional and prospective evidence suggest that negative cognitive styles are related to depression within bipolar disorder, but there also is evidence that bipolar disorder is related to an elevated focus on goals as well as to increases in confidence during manic states. With such findings as backdrop, we consider the outcomes of psychological treatments for bipolar disorder and advance several suggestions for clinical practice. © 2007 Wiley Periodicals, Inc. J Clin Psychol: In Session 63: 425–432, 2007.
What psychotherapists should know about pharmacotherapies for bipolar disorder
Authors: Goldberg Joseph F.
Published: April 2007

This article provides a practice‐friendly overview of current psychotropic agents used for the treatment of bipolar disorder. The author reviews definitions and concepts about mood stabilization according to the evidence base, in turn profiling a “clinical niche” for lithium, anticonvulsant drugs, atypical antipsychotics, and antidepressants. Results from randomized clinical trials are summarized to help clinicians individualize treatment decisions and tailor them to real‐world patients. Recognition and management of common adverse effects are discussed alongside risk–benefit strategies to guide optimal treatment that balances clinical efficacy with drug safety and tolerability. © 2007 Wiley Periodicals, Inc. J Clin Psychol: In Session 63: 475–490, 2007.
An integrative formulation‐based cognitive treatment of bipolar disorders: Application and illustration
Authors: Mansell Warren
Published: April 2007

An integrative cognitive treatment for mood swings and bipolar disorders is summarized and then illustrated in a clinical case. In essence, it is proposed that multiple, extreme, and conflicting beliefs about changes in internal state, and the reciprocal impact of these beliefs on behavior, physiology, and the social environment, constitute the central mechanism that maintain and escalate bipolar symptoms. Using a case illustration with examples of therapy dialogue, several key aspects of cognitive‐behavioral therapy are explained, including the assessment of mood, beliefs, distressing imagery, and recurrent thinking; case formulation; therapeutic techniques; self‐awareness; interpersonal factors during therapy; and systemic issues. © 2007 Wiley Periodicals, Inc. J Clin Psychol: In Session 63: 447–461, 2007.
Reaction of the benzoyloxy radical with α‐methylstyrene
Authors: Barson C. Anthony , Bevington John C. , Hunt Barry J.
Published: April 2007

Benzoyl peroxide labelled with carbon‐14 and tritium has been used for study of the end‐groups in copolymers of α‐methylstyrene (MST) with methyl methacrylate, in particular determination of the relative numbers of benzoate and phenyl end‐groups derived from the initiator. MST is found to be quite reactive towards the benzoyloxy radical. It is deduced that combination is the dominant mode of termination in the copolymerization, that transfer reactions are not important and that there is little abstraction of hydrogen from MST by the benzoyloxy radical.
A microstructural study of polystyrene—polyether sulphone polymer blends
Authors: Sickafus Kurt E. , Donald Athene M.
Published: April 2007

Polystyrene (PS)‐polyether sulphone (PES) polymer blend thin films were prepared for investigation in a scanning transmission electron microscope. The microstructures of PS‐PES films (prepared by drawing from solutions at temperatures above ambient) of three different compositions were characterized: (1) 75 wt% PS‐25 wt% PES, (2) 50 wt% PS‐50 wt% PES, and (3) 25 wt% PS‐75 wt% PES. For films prepared at ∼ 40°C all three compositions exhibited microstructures consisting of spherical inclusions, ranging from ∼0.2μm to ∼ 1.2μm in diameter. The microscope used here was equipped with an energy‐dispersive X‐ray spectrometer, and this was employed to determine the chemical content of the inclusions and the matrix material. From X‐ray analysis, it was found that films (1) and (2) consisted entirely of PES‐rich inclusions, while film (3) contained both PS‐rich and PES‐rich inclusions. In addition, these analyses revealed that films (2) and (3) possessed a ‘mixed’ PS‐PES matrix phase. At the other temperatures for film preparation some significant differences in morphology were observed, reflecting the different rates of solvent evaporation.
Guest network co‐continuity in interpenetrating polymer networks: A diffusion study
Authors: McGarey Brian , McLenaghan Alan D. W. , Richards Randal W.
Published: April 2007

Interpenetrating networks have been prepared using poly(dimethylsiloxane) as the host network and polymethacrylic acid as the guest network, i.e. polymerised and crosslinked in the presence of the siloxane network. These networks were swollen to equilibrium in dilute aqueous potassium chloride solutions and used as membranes to separate a solution of potassium chloride from pure water. The concentration of potassium chloride either side of each membrane was monitored as a function of time by conductivity measurements. From these data, the diffusion coefficient of potassium chloride in the membranes was calculated as a function of polymethacrylic acid content for temperatures of 303, 318 and 333K. Values of the diffusion coefficient were between 3 x 10−7cm2s−1 and 19 x 10−5 cm2 s−1. The activation energy of the diffusive process decreased linearly with the increase in water content of the networks.
Newtonian behaviour of sheared aqueous carboxymethylcellulose solution on aging
Authors: Jayabalan M.
Published: April 2007

The effects of microbiological attack on the rheological properties of sodium carboxymethylcellulose (NaCMC) solutions are described. The effect of aging on the viscosity of aqueous NaCMC solution was studied by means of a Brookfield viscometer. An aqueous NaCMC solution was allowed to age and was subjected to shearing at different time intervals. Dilatant rheological properties were observed in contrast to the usually pseudoplastic behaviour of a normal NaCMC solution. This is attributed to the effect of shear‐induced recombination of NaCMC macromolecular crystallites produced as a result of chain scission of NaCMC molecules during aging. The recombination of the crystallites gives higher values of viscosity at higher shear rates. A five months aged sample when subjected to shearing for a period of 20 h exhibits different behaviour. After prolonged post‐shearing of this sample, the viscosity measured at shear speeds of 10 rpm and 20 rpm at 72 h and 102h approaches a common value for post‐shearing period. The approach to the Newtonian character is attributed to the shear‐stress‐induced breakdown of the crystalline aggregates. These studies reveal that the aging effects on NaCMC solution have a drastic influence on the rheological properties.
Ring‐opening polymerization of norbornene and six of its methyl derivatives by well‐defined tungsten‐carbene complex catalysts
Authors: Greene Ruth M. E. , Ivin Kenneth J. , Kress Jacky , Osborn John A. , Rooney John J.
Published: April 2007

Eight tungsten‐carbene complex catalysts of the type W(CHCMe3)L1L2L3L4, where the ligands L are various combinations of OCH2CMe3, SO3CF3, OSiPh3, Br and I, have been used, in the presence and absence of GaBr3, to polymerize norbornene and six of its methyl derivatives by ring opening. The microstructure of the polymers was determined from their 13C NMR spectra; values of cis content, cis‐trans blockiness, ring‐dyad tacticity and head‐tail bias were derived as appropriate to each system. The results are discussed in terms of electronic and steric effects in the propagating carbene complexes.
Experimental evidence for slow theory of mutual diffusion coefficients in phase separating polymer blends
Authors: Higgins J. S. , Fruitwala H. A. , Tomlins P. E.
Published: April 2007

Small Angle Neutron Scattering (SANS) is used to study the kinetics of spinodal decomposition of a blend of polymethyl methacrylate (PMMA) with solution chlorinated polyethylene. The early stages of phase separation are quantified using Cahn‐Hilliard theory. Temperature and molecular weight dependences of interdiffusion are studied and it is shown that data can be better interpreted in terms of a wave vector dependent diffusional mobility M(q).
Polyurethane from kraft lignin
Authors: Cheradame H. , Detoisien M. , Gandini A. , Pla F. , Roux G.
Published: April 2007

The condensation of lignin with hexamethylene diisocyanate (HDI) or of a mixture of lignin‐poly(ethylene oxide) (PEO) with HDI was investigated. The lignin used in this study was a kraft lignin from Pinus maritima, and was obtained from black liquor by acidification, filtration and vacuum drying. Thermogravimetric analysis was carried out to compare the weight loss against temperature of polyurethanes based on kraft lignin and hexamethylene diisocyanate, or of mixed polyurethanes lignin‐PEO‐HDI, with that of kraft lignin alone. It was shown that lignin can react with isocyanates in rather mild conditions to give polyurethanes, confirming previous results performed with model molecules. Some mechanical properties (Young's modulus and rupture strength) and glass transition temperature were also measured on the various above materials. In all cases it was concluded that lignin participates to the polycondensation reaction.

As to rigid foams, it was found that polyurethanes prepared with oxypropylated glycerol, ethylene glycol and kraft lignin, in the weight proportions of 100/30/15, and HDI had good dimensional stability, and thermal and mechanical properties comparable to those of equivalent industrial materials.
Influence of total processing history on polypropylene structure and properties
Authors: Akay M.
Published: April 2007

Two polypropylenes produced by different conversion routes were extruded as film with added amounts of sodium benzoate between 0.025% and 0.5% by weight. The resultant structures were shown to be a function of casting conditions, molecular features of the base polymer and induced degree of nucleation. At high casting temperatures and with higher percentage of nucleating agents the characteristic skin‐core structure was reversed; the film exhibiting a coarse spherulitic skin and a fine structure in the core. These conditions also gave rise to notable as‐cast orientation. Addition of the highest levels of sodium benzoate resulted in a non‐spherulitic crystalline core structure. As would be expected the elastic modulus and the yield strength of the films increased with percentage crystallinity.
Bioactive polymers LVII. A novel drug delivery system based on 5‐nitro‐2‐furaldehyde‐semicarbazone and poly(acrylic acid‐co‐vinyl alcohol)
Authors: Dumitriu Severian , Popa Marcel , Petrovan Simion , Staicu Raluca
Published: April 2007

The coupling of 5‐nitro‐2‐furaldehyde‐semicarbazone on to poly(acrylic acid‐co‐vinyl alcohol) copolymer by the use of dicyclohexylcarbodiimide as activator has been studied.

On the basis of an experimental design, the influence of different parameters is studied (activator/support, drug/support, reaction time, solvent volume) in order to determine the optimum conditions for obtaining the maximum amount of the coupled drug on the support.
Ultrasonic absorption and visco‐relaxation study of poly(vinyl alcohol) aqueous solution. (A method for the determination of molecular weight)
Authors: Hassun Subhi Kemal , Isa Suad Omran
Published: April 2007

Ultrasonic absorption and velocity measurements are reported on aqueous solutions of poly(vinyl alcohol) (PV‐OH) of different molecular weights and concentrations obtained using a pulsed ultrasonic apparatus operating at 2 MHz and 303 K. The variations in these parameters as a function of concentration are interpreted in terms of changes in the magnitude of the contribution due to relaxation of the backbone and of the side chain acetyl groups. The results show an increase in velocity, density and viscosity with increase in molecular weight and concentration of PV‐OH.

In contrast the attenuation values decrease with increase in molecular weight. This suggests that interaction is occurring between PV‐OH and water molecules. Deviation of the variation of the attenuation with concentration from the ‘ideal’ dilute solution behaviour at high concentration is ascribed to the effects of polymer‐polymer interaction. The magnitude of the volume change associated with polymer‐solvent interactions is estimated and discussed.

A mathematical equation correlating the relaxation amplitude and the molecular weight of the polymer is suggested. This approach was applied to the calculation of the molecular weight of four unknown samples of PV‐OH from their measured relaxation amplitudes. The results obtained agree well with those obtained from osmometry.
Rheological behaviour of titanate coated mica‐filled polypropylene
Authors: Bajaj Pushpa , Jha Narendra K. , Jha Rajiv K.
Published: April 2007

Titanate coupling agents have been used for the surface modification of mica to improve the viscoelastic behaviour of mica‐filled polypropylene. Four titanate coupling agents, neoalkoxy tri(dioctylpyrophosphato) titanate (CA1), neoalkoxy trineodecanoyl titanate (CA2), bisacetylacetonatodistearato titanate (CA3), and bisacetylacetonatodipalmitato titanate (CA4), were used in the present investigation. Mica powder (10 μm, particle size) was coated with these coupling agents in varying concentrations (0.5‐10% based on the weight of the filler), and then blended with stabilised polypropylene powder of 10 melt flow index (MFI). The mica‐filled (10‐50 wt%) polypropylene samples were extruded and used in the granular form for studying the viscoelastic behaviour. The melt viscosity of titanate coated mica‐PP samples decreases irrespective of the nature of the coupling agent used. The activation energy of melt rheology is independent of the mica content. The die swell increases with the use of titanate coupling agent. Compatibility of mica and polypropylene has also been studied with the help of a scanning electron microscope.
Polymeric surfactants for enhanced oil recovery. Part I—critical micelle concentration of some ethoxylated alkylphenol—formaldehyde nonionics
Authors: Barakat Youssef , Gendy Tahany S. , Mohamad Attia I. , Youssef Abdel‐Fattah M.
Published: April 2007

Four low molecular weight nonionic polymeric surfactants were prepared by condensing octyl‐, dodecyl‐, tetradecyl‐ and hexadecylphenol with para‐formaldehyde, and then reacting the resulting resins with ethylene oxide to obtain products with the desired degree of ethoxylation. The molecular weights of the prepared alkylphenol‐formaldehyde resins (prior to ethoxylation) were determined by vapour pressure osmometry.

The surface tensions of aqueous solutions of these nonionic polymeric surfactants were determined by using the spinning drop method. Plotting the surface tensions obtained versus the logarithm of concentrations resulted in two lines: the pre‐CMC (CMC = critical micelle concentration) line (the linear portion below the CMC value) and the post‐CMC line (the linear portion above the CMC value). Least squares regression analysis was performed to get the best equation for each of the two lines. Solving these two equations simultaneously resulted in the value of the CMC and the corresponding surface tension (γCMC) for each surfactant of the four polymeric nonionic groups.

The CMC values obtained for these polymeric surfactants are of the same order of magnitude obtained for monomeric and other polymeric nonionic surfactants.
Thermodynamics of micellization of poly‐styrene‐block‐poly(ethylene/propylene) copolymers in decane
Authors: Price Colin , Stubbersfield Rita B. , El‐Kafrawy Salwa , Kendall Kenneth D.
Published: April 2007

Light scattering was used to establish the dependence of the critical micelle temperature, CMT, on concentration for solutions of three polystyrene‐block‐poly(ethylene/propylene) copolymers in decane. Electron microscopy studies of particles isolated from the solutions showed that the micelles had narrow size distributions and micellization could be treated thermodynamically as a closed association. The light scattering results were used to calculate the standard Gibbs energies of micellization, ΔGφ, and the standard enthalpy, ΔHφ, and entropy contributions, —TΔSφ. The values of ΔHφ were large and negative, and markedly dependent on the molecular weight of the polystyrene block. The values of ΔGφ for the three samples were on the other hand very similar to each other. The standard entropy contributions were unfavourable to micelle formation.
A calorimetric study of the interchange reactions in bisphenol a polycarbonate/nylon‐6 blends
Authors: Cortárzar Milagros , Eguiazábal José I. , Iruin Juan J.
Published: April 2007

The interchange reactions in a partially miscible blend composed of bisphenol A polycarbonate and nylon‐6 have been studied by the use of a calorimetric technique. It has been found that these reactions affect the thermal transitions of the mixtures. These effects have been interpreted to be a consequence of the progressive formation of copolymers which homogenize the mixture.
An experimental investigation of poly(vinyl chloride) emulsion polymerization: Effect of initiator and emulsifier concentrations on polymerization kinetics and product particle size
Authors: Karakaş Gürkan , Orbey Neşe
Published: April 2007

Effects of concentration changes in initiator species Na2SO3, (NH4)2S2O8 and CuSO4, and emulsifier, ammonium stearate, on poly(vinyl chloride) (PVC) emulsion polymerization kinetics and on product particle size were experimentally investigated. It was observed that to obtain industrially significant rates and overall conversions, not only an optimum concentration ratio of Na2SO3/(NH4)2S2O8/CuSO 4 must be used, but also the concentrations of these species must be above certain limits. Increasing the concentration of the emulsifier used did not influence the rate of polymerization, but led to increases in limiting conversions.

Product particle size analyses indicate that average particle size is independent of initiator concentration and rate of initiation. An increase in the emulsifier concentration on the other hand appears to lead to an increase in number of particles in the system and thus promotes smaller particle sizes.
Two‐dimensional nuclear magnetic resonance of resins
Authors: Duff Alastair J. , Kemp William , Steedman William , Boyd Alan S. F.
Published: April 2007

A group of resins was synthesised from a series of phenols and aldehydes, and their structures comprehensively deduced from two‐dimensional nuclear magnetic resonance spectroscopy (2‐D NMR). Correlation spectroscopy, in particular carbon‐proton heteronuclear chemical shift correlation spectroscopy, was shown to be especially incisive in assigning structural features to the NMR signals.

The method has permitted fuller structural characterisation of these materials than was heretofore possible, and has identified, inter alia, methylene and methyleneoxy bridges unequivocally: complex substitution patterns in the phenol‐derived aromatic rings have also been elucidated.

It is demonstrably possible to apply the same techniques to similar complex resin structures, and to utilise these structural insights to determine the mechanistic processes involved in their syntheses.
Aqueous polymerization of methyl methacrylate initiated by the redox system Ce(IV)—D‐glucose. I: General features and kinetics
Authors: Fernández M. D. , Guzmán G. M.
Published: April 2007

The polymerization of methyl methacrylate initiated by the ceric ammonium nitrate‐D‐glucose redox system has been studied in aqueous nitric acid under nitrogen in the temperature range 20‐5 to 35°C. The initial rate of polymerization was determined gravimetrically whereas the initial rate of ceric ion disappearance was determined by titration of ceric ion. The relationships between conversion and D‐glucose, Ce(IV), and monomer concentrations were determined. The dependence of the rates on D‐glucose, Ce(IV), and monomer concentrations was evaluated. The effect of temperature was also examined.
Start‐up and growth mechanisms in the loop continuous reactor
Authors: Geddes Kenneth R.
Published: April 2007

Changes in physical properties during Loop continuous emulsion polymerisation reactor runs were studied, with particular reference to particle size distribution. Cycling of properties similar to those reported for continuous stirred tank reactors (CSTRs) was found.

The cycling of properties was attributed to an intermittent creation of new particles caused by changes in surface area. It was predicted that cycles would die away and an equilibrium would be established. This occurs in practice.
Polymeric surfactants for enhanced oil recovery. Part II—the hlb‐cmc relationship of ethoxylated alkylphenol‐formaldehyde polymeric surfactants
Authors: Barakat Y. , Gendy T. S. , Basily I. K. , Mohamad A. I.
Published: April 2007

The natural log of critical micelle concentration (CMC) values obtained from the natural log discontinuities in surface tension‐concentration relationships, through the least‐squares regression analysis, were plotted against the respective hydrophile‐lipophile balance (HLB) values of four groups of ethoxylated octylphenol‐, dodecylphenol‐, tetradecylphenol‐ and hexadecylphenol‐formal‐dehyde polymeric surfactants.

The obtained HLB‐CMC relationship for the investigated compounds can be represented satisfactorily by the linearized equation In (CMC) = a—b (HLB). Values of the two constants a (intercept) and b (slope) for 16 of these compounds were determined at 28, 38, 48 and 58°C, using the least‐squares regression analysis of data. The study revealed that both a and b values increase with increasing number of carbon atoms in the ethoxylates of polymeric compounds having a linear alkyl chain. The influence of branching is reflected in the values of a and b of the compounds having a branched dodecyl chain.

The most striking feature of the obtained equation is that the CMC decreases with increasing HLB (negative slope). This observation is contrary to what is generally expected for both ionic and nonionic surfactants.
Effects of synthesis conditions on radiation‐induced graft copolymerization of methacrylic acid on to poly(vinyl chloride) films
Authors: Singh Jagbir , Ray A. R. , Singh Harpal
Published: April 2007

Poly(vinyl chloride) (PVC) films were grafted with methacrylic acid (MAA) using a simultaneous‐irradiation technique. The effect of solvent ratio (methanol‐water) on grafting was studied and maximum grafting was found for an equivolume mixture of methanol and water. The graft level increased with increase of the plasticizer (dioctylphthalate) content in PVC. Grafting was found to be higher at low dose rate and increased linearly up to 0.25 Mrad for all dose rates and then levelled off. Grafting also increased continuously with increasing monomer concentrations up to 5.4mol/litre, but a linear increase in grafting was observed only up to 2.5 mol/litre. The dependences of rate of grafting on dose rate and monomer concentration were found to be 0.62 and 1.20 respectively.
Comparative effects of resorcinol and bisphenol A in non‐mesogenic units in liquid crystalline copolyesters containing a flexible spacer
Authors: Rao A. Kameswara , Lenz Robert W. , Jin Jung‐Ii
Published: April 2007

Two series of copolyesters containing both linear mesogenic and nonlinear, non‐mesogenic aromatic ester units, each with a decamethylene spacer, were prepared and characterized for the effect of the non‐mesogenic unit and the spacer on the stability of the liquid crystalline (LC) phase. The mesogenic units were formed from the reaction of 2‐chlorohydroquinone and 1,10‐bis(4‐carboxy‐phenoxy)decane while the non‐mesogenic units were derived from reacting either resorcinol (Series I) or bisphenol A (Series II) with the latter monomer. The non‐mesogenic units containing bisphenol A were found to be more efficient in destroying liquid crystallinity of the copolyesters than were resorcinol‐containing units. However, the presence of a flexible spacer in each unit allowed the copolymers to form a nematic LC phase even at contents of the resorcinol and bisphenol A non‐mesogenic units as high as 70 and 60 mol %, respectively.
Siloxanes with 1‐oxypyridin‐3‐yl groups. Part 6. synthesis of copolymers and application as transacylation catalysts
Authors: Zeldin Martel , Fife Wilmer K. , Tian Cheng‐Xian , Xin Yue
Published: April 2007

Linear end‐blocked and crosslinked siloxane copolymers containing dimethylsiloxyl and methyl(1‐oxypyridin‐3‐yl)siloxyl groups were prepared and characterized thermally (TGA) and spectroscopically. These hydrophobic copolymers were found to be highly effective transacylation catalysts in the synthesis of carboxylic anhydrides and the hydrolysis of diphenyl phosphoro‐chloridate (DPPC) under phase‐transfer catalysis (PTC) conditions, i.e. CH2Cl2‐H2O suspension. The insolubility of the copolymers in water and the preference of the intermediate, polymeric 1‐acyloxypyridinium ion for the more lipophilic carboxylate ion in anhydride formation suggest that the reaction occurs at the CH2Cl2‐H2O interphase. The rapid rate of hydrolysis of DPPC under PTC conditions and in water provides evidence for initial hydrophobic binding or association of the hydrophobic catalyst prior to reaction with a water‐insoluble substrate.
Polyorganosiloxanes containing both ester and hydride functionalities: A detailed study by 1H and 13C NMR spectroscopy
Authors: Ashworth Anthony J. , Brisdon Brian J. , Zafar Imran , England Richard
Published: April 2007

A total of eighteen linear polysiloxanes of general formula Me3SiO‐(MeSi(E)O)x(MeSi(H)O)ySiMe3 (E = —(CH2)nester; x+y = 40) have been prepared by the platinum catalysed addition of CH2=CH(CH2)n‐2 ‐ester to Me3SiO‐(MeSi(H)O)40SiMe3 under anhydrous conditions. Polymers containing the ester functionalities—(CH2)3CO2R(R = Me, CF3, Et, Pr, and CH2COMe),—(CH2)3‐CHMeCO2Et, —(CH2)2CH(CO2Me)2, —(CH2)3CH(CO2Et)2, ‐(CH2)3CO2CH= CHCO2CH2CH=CH2 and —(CH2)3CO2C6H4CO2 CH2CH=CH2 have been characterised by analysis and 1H and 13C NMR spectroscopies. Factors affecting Markownik off versus anti‐Markownikoff addition of allyl acetate to this polymethylsiloxane have also been explored.
Aqueous polymerization of methyl methacrylate initiated by the redox system Ce(IV)‐D‐Glucose. II: Effect of reaction conditions on polymer molecular weight
Authors: Fernández M. D. , Guzmán G. M.
Published: April 2007

The dependence of molecular weight of poly(methyl methacrylate) on reaction conditions, as polymerized in aqueous nitric acid with the redox system ceric ammonium nitrate‐glucose, has been studied. The average molecular weights and molecular weight distributions were determined by size‐exclusion chromatography. The degree of polymerization was found to increase in the course of a run and was also affected by changes of Ce(IV) and glucose concentrations in the range where the rate of polymerization increased, but not where the rate was independent of Ce(IV) concentration and decreased with glucose concentration. The average molecular weights can be controlled by variations in monomer concentration and in temperature. The polymerization rate was found to attain a maximum with nitric acid concentration whereas the rate of ceric ion consumption increased. A fall in the degree of polymerization was observed on increasing the acid concentration. The effect of nitrate ion concentration as well as of that of certain water‐miscible solvents on the above‐mentioned parameters has also been studied.
Thermal behaviour of partially neutralised ethylene‐maleic acid copolymer
Authors: Nicholson John W. , Wasson Eleanor A.
Published: April 2007

As part of continuing studies on the cure of candidate polymers for waterborne coatings, the thermal behaviour of partially neutralised ethylene‐maleic acid copolymer, EMA, has been examined. Films of EMA neutralised with a variety of bases were heated at 250°C. For this copolymer, as for poly(acrylic acid) at the same temperature, reflectance infrared spectroscopy has shown that heating led initially to anhydride formation. In the unneutralised state, or with the divalent ions calcium, magnesium, cobalt or zinc, further heating led to little or no further reaction. By contrast, the presence of univalent metal ions lithium, sodium and potassium caused a second reaction to occur, namely decarboxylation to yield keto crosslinks. This second reaction, however, did not occur to the extent that it does with poly(acrylic acid) under identical conditions. Possible reasons for this are discussed.

Unlike poly(acrylic acid), EMA when partially neutralised was found not to form continuous films on the tin‐plate substrate.
Effect of stretching temperature on proton spin‐lattice and spin‐spin relaxation times of isotactic polypropylene film
Authors: Tanaka Hiroshi , Takagi Kiyohide
Published: April 2007

Structural properties of isotactic polypropylene film during stretching were investigated mainly by the measurements of proton spin‐lattice, T1 and spin‐spin, T2, relaxation times. Both T1 and T2a, T2 of the most mobile amorphous regions, of the sample stretched at 150°C are longer than those of the sample stretched at 130°C. These results indicate that in the sample stretched at 150°C the proportion of mobile amorphous region decreases, while the amorphous region achieves enhanced molecular mobility.
Kinetic study of aqueous polymerization of methyl methacrylate initiated by Ce(IV)‐maltose redox system
Authors: Fernández M. D. , Guzmán G. M.
Published: April 2007

Polymerization of methyl methacrylate initiated by ceric ammonium nitrate‐maltose has been investigated in aqueous nitric acid under nitrogen in the temperature range 20.5‐35°C. The dependence of the initial rate of polymerization and the initial rate of ceric ion consumption on maltose, Ce(IV), and monomer concentrations has been determined. The reaction orders were found to depend on ceric ion concentration. At a moderately high Ce(IV) concentration (1 × 10−3mol litre−1) the orders were 1/2 and 3/2 with respect to maltose and monomer concentration, respectively, and independent of Ce(IV) concentration. But at a low Ce(IV) concentration (4 × 10−4mol litre−1) the orders with respect to monomer and Ce(IV) changed to 1 and 1/2, respectively. The effect of temperature was also examined. The average molecular weight, as determined by size‐exclusion chromacography, was found to depend on maltose, Ce(IV), and monomer concentrations, as well as on temperature.
Blends of polycarbonate and poly(hexamethylene sebacate): IV. Polymer blend intrinsic viscosity behavior and its relationship to solid‐state blend compatibility
Authors: Shih K. S. , Beatty C. L.
Published: April 2007

The intrinsic viscosities of blends of bisphenol‐A polycarbonate and poly(hexamethylene sebacate) have been measured in chloroform as a function of blend composition for a variety of molecular weight species. The compatibility of the polymer blend mixtures is characterized by the parameter δb, from the Krigbaum and Wall theory. Using Tg of the blend as a measure of bulk solid‐state compatibility, a correlation is obtained with the Krigbaum and Wall parameter δb for each of the molecular weight pairs studied. Slopes of the correlation are invariant, as expected, as the chemical composition is the same for the different molecular weight pairs studied.
Kinetics of photo‐oxidative degradation and stabilization of poly(2,6‐dimethyl‐1,4‐phenylene oxide) by metal dialkyl dithio phosphate
Authors: Chandra R. , Thapliyal B. P. , Singh R. P.
Published: April 2007

The kinetics of photo‐oxidative degradation and stabilization of poly(2,6‐dimethyl‐1,4‐phenylene oxide) have been studied in the temperature range 313‐363 K using monochromatic light of 365 nm with a constant intensity flux of 8.7 × 10−9 einstein s−1 cm−2 in the absence and presence of Ni(II) O,O′‐diisopropyldithiophosphate. The course of degradation and stabilization was determined by means of light scattering and spectroscopic techniques. The extent of photodegradation was followed by carbonyl formation, gel content and activation energy. The incorporation of 1.2 wt% stabilizer in the matrix of the polymer films exercises the maximum protective influence on the photodegradation of the polymer.
Synthesis and characterisation of poly(arylene sulphides): Part 11. Preparation of poly(1,4‐phenylene sulphide) directly from bis(4‐bromophenyl) disulphide
Authors: Lovell Peter A. , Still Richard H.
Published: April 2007

Reaction conditions for the preparation of poly(1,4‐phenylene sulphide) (PPS) directly from bis(4‐bromophenyl) disulphide (BBD) have been established. Reactions were performed in a boiling quinoline/pyridine solvent mixture (91% by vol. quinoline) in the presence and absence of copper powder. Reaction products were fractionated and the fractions characterised using elemental analysis, IR and NMR spectroscopy, viscometry, hot‐stage microscopy, differential scanning calorimetry, thermogravimetry and curing studies. The yields and properties of the polymeric fractions are compared to those of similar fractions obtained from preparation of PPS by solution polymerisation of copper(I) 4‐bromobenzenethiolate under conditions which correspond to those employed in this work.

PPS was not produced, and BBD was almost quantitatively recovered when copper was absent from the reactants.

Reactions performed using an equimolar ratio of copper to BBD produced PPS of molar mass approximately 2–4 × 103 gmol−1 in 76% yield after 8h reaction. However, this PPS was contaminated with an insoluble infusible material which had a deleterious effect on the physical properties of derived cured PPS materials. The yield of PPS decreased and the quantity of contaminant increased as reaction time increased.

PPS of molar mass approximately 104g mol−1 was obtained in 50–60% yield, free from insoluble infusible material, when the molar ratio of copper: BBD was increased to 2:1; it exhibited normal properties on curing.
Electron transport in Fe‐doped polyvinyl acetate films
Authors: Sharma A. K. , Rukmini B.
Published: April 2007

The electrical conductivity and current‐voltage characteristics of pure and Fe3+‐doped polyvinyl acetate films have been studied for various temperatures and bias field strengths. The activation energy for conduction showed an increasing trend with increasing dopant concentration. This has been attributed to the formation of molecular aggregates. The variation of electrical conductivity for doped films with temperature showed three regions with different activation energies. This behaviour has been explained in terms of the type of conduction mechanism operating in the material. It has been suggested that at low temperatures the conduction is electronic while at high temperatures it appears to be ionic. As the dopant concentration increases ionic conduction tends to dominate the electronic conduction even at low temperatures. From the current‐voltage measurements it has been concluded that the conduction mechanism tends towards Schottky type with increasing dopant concentration.
An analytical method for the determination of cationic flocculants of the epichlorohydrin‐dimethylamine condensate type
Authors: Clarke Michael Cassin
Published: April 2007

A method for the analysis of epichlorohydrin‐dimethylamine flocculants is presented. The method is applicable to concentrations of flocculant of between 2 and 60 parts per million. These concentrations are used in coal and other mineral processing operations. An extension of the method may be used to give semiquantitative estimations of higher concentrations.
Kinetics of ylide‐initiated radical copolymerization of 4‐vinylpyridine and methyl methacrylate
Authors: Vasishtha Rita , Awasthi Sanjay , Srivastava A. K.
Published: April 2007

The ylide‐initiated radical copolymerization of 4‐vinylpyridine (4‐VP) with methyl methacrylate (MMA) at 60°C using carbon tetrachloride as inert solvent yields non‐alternating copolymers. The kinetic parameters, average rate of polymerization (Rp) and orders of reaction with respect to monomers and initiator, have been evaluated and the kinetic equation is found to be Rpα[ylide]0.94 [MMA]1.0 [4‐VP]1.5. The values of the energy of activation and kp2/kt are 48 kJ mol−1 and 6.6 × 10−5 litre mol−1s−1, respectively. The copolymers have been characterized by IR and NMR spectroscopy.