bluuebunny/crossref_metadata_2025 huggingface dataset:
Alkyl halides in conjunction with inorganic salt for the initiation of the polymerization and graft copolymerization of heterocycles
Authors: Dreyfuss P. , Kennedy J. P.
Published: June 2010

When certain alkyl halides react with suitable inorganic salts in the presence of a heterocyclic monomer, polymerization ensues. Appropriate alkyl halides include allylic, tertiary, and benzylic chlorides, bromides, and possibly iodides. If the halide is a small organic molecule, a homopolymer is formed; if it is a polymer halide, a graft copolymer results. Soluble silver salts with counterions such as SO3CF3−, BF4−, PF6−, SbF6−, and ClO4− are most suitable, but LiPF6 and NaClO4 can also be used. So far, nine heterocycles have been polymerized by this method, e.g., tetrahydrofuran, 7‐oxabicyclo[2·2·1]heptane, propylene oxide, styrene oxide, dioxolane, trioxane, ε‐caprolactone, and thietane. To date, no effort has been made to optimize conditions for each monomer, but the preliminary data suggest that many of the expected side reactions are operative. Graft copolymers have been prepared from seven backbones: poly(vinyl chloride), neoprene, chlorinated EPDM, chlorobutyl rubber, bromobutyl rubber, chlorinated butadiene, and chlorinated butadiene‐styrene copolymer. In the most thoroughly examined cases with polytetrahydrofuran as the grafted copolymer and silver triflate as the inorganic salt, current data indicate that no unreacted backbone remains and no homopolymer forms. With some of the other monomers, homopolymer is formed in addition to graft during the grafting process.
Photoinitiated and aprotonically initiated polymerization of olefins by Lewis acids
Authors: Marek M.
Published: June 2010

A survey and discussion of recent problems in interpretation of the mechanism of olefin polymerization by Lewis acids is presented from the point of view of new results obtained by study of physicochemical transformations which proceed in interaction of catalysts with olefins. Opinions related to the photo‐chemically initiated cationic polymerization have been further defined by the study of formation and composition of complexes as well as by analysis of oxidation‐reduction processes proceeding under the effect of light on the reaction mixture. The formation of radicals under the effect of visible light in the presence of Lewis acids was proved with several monomers other than isobutylene. During investigation of the role of products from the photooxidation‐reduction processes in the polymerization of isobutylene, it has been found that strongly basic reducing agents, such as butyllithium, cause the polymerization of isobutylene in the presence of halides of tetravalent transition metals.

Also analyzed are the aspects of utilization of the photochemically induced polymerization in development of new technological procedures for manufacturing of high molecular weight polyisobutylene and butyl rubber under economically advantageous conditions.
Rates of initiation of the cationic polymerization of isobutene
Authors: Russell Kenneth E. , Vail Linda G. M. C.
Published: June 2010

The substance 2,6‐di‐tert‐butylphenol acts as a strong retarder for the cationic polymerization of isobutene. Spectroscopic studies show that the growing polymer cation attacks the phenol at the basic 4‐position. Analysis of the kinetic and degree of polymerization results yields estimates of the rates of initiation of the polymerization.

The initiation reaction in the polymerization of isobutene in ethyl chloride at −78.5°C with stannic chloride and a coinitiator appears to be a first‐order process. Rate constants for the initiation reaction include 4 × 10−6sec−1 for water as coinitiator, 3.8 × 10−5sec−1 for 2,6‐dimethylphenol, 7.5 × 10−5sec−1 for 2,4,6‐trimethylphenol, 3.1 × 10−5sec−1 for 2,3,5,6‐tetramethylphenol, 7 × 10−5 sec−1 for 2,3,4,6‐tetramethylphenol, and 1.5 × 10−3sec−1 for acetic acid.
Olefin oligomerization by boron fluoride
Authors: Lachance Pierre , Eastham Arthur M.
Published: June 2010

Polymerization of 2‐butene by boron fluoride‐methanol in methylene chloride gives a mixture of olefins, primarily in the C8–C14 range. The C8 fraction consists of the equilibrium mixture of 3,4‐dimethylhexenes corresponding to the normal dimer; similarly, the C10 fraction is largely a mixture of 3,4,5‐trimethylheptenes. The major component of the C9 group seems to be a 2,3,4‐trimethylhexene, but a significant part of the nonenes remains unidentified. We now have evidence, in contradiction to our earlier report, that a C11 fraction does exist but is difficult to separate from the complex C12 mixture.

With propylene under the same reaction conditions, limited fragmentation occurs and the products are primarily oligomers in the tetramer‐to‐decamer range; therefore, the reaction is quite well suited to the study of reaction variables. It is found that the composition of the reaction product is almost independent of the degree of conversion, but that increasing the cocatalyst concentration tends to shift the molecular weight maximum to somewhat higher values. Changing the cocatalyst from methanol to acetic acid makes little difference, and the amount of fragmentation seems to be unaffected by the amount or kind of cocatalyst.
Thermal degradation of polystyrene: Effect of end groups derived from azobisisobutyronitrile
Authors: Cascaval C. N. , Straus S. , Brown D. W. , Florin R. E.
Published: June 2010

Polystyrenes containing end groups derived from azobisisobutyronitrile (AIBN) were subjected to thermal degradation at 280–350°C and the rates of volatilization compared with those of thermally and anionically prepared polystyrene. At 330–350°C the degradation of the AIBN polymer resembled that of the thermal polymer and differed from that of the anionic one. At 280–320°C its behavior was complex; infrared analysis of the degraded polymer and pyrolysis gas chromatography results suggest weak bond involvement in some cases.
Photodegradation of colored polyethylene films
Authors: Mlinac M. , Rolich J. , Bravar M.
Published: June 2010

The changes of mechanical, physical, and chemical properties of colored low‐density polyethylene films under ultraviolet light were investigated. The study was performed using commercially manufactured colored pigments: Cadmium Yellow, CdS/ZnS; Ultramarine Blue, Na7Al6‐Si6O24S3; Copper Phtalocyanine Green, C32H2N8Cl14Cu, and Chrome Orange, PbCrO4.PbO. Two series of colored film samples were subjected to artificial aging in a weatherometer. The first series contained no ultraviolet absorber and the second one contained substituted 2(2′‐hydroxyphenyl)‐benzotriazole (Tinuvin 328).

It was found that the extent of film deterioration depends on the nature of the pigment utilized. Two types of pigment influence on the rate of film properties changes were observed. When using Cadmium Yellow an enhanced process of polyethylene degradation was noted, while, in contrast to this a delay in aging of films was observed with Chrome Orange, Copper Phtalocyanine, and Ultramarine Blue.
Degradation of polyethylene in compost burial
Authors: Griffin G. J. L.
Published: June 2010

Degradation of buried low‐density polyethylene has been reported but only in the composting garbage environment. Evidence is offered linking the initial stage of the breakdown with the transfer by diffusion of unsaturated lipids from the compost to the polymer associated with the generation of peroxides by autoxidation.
New aspects in the activity of nitrogen‐containing antioxidants
Authors: Schulz Manfred , Wegwart Herbert , Stampehl Gundula , Riediger Werner
Published: June 2010

The antioxidative efficiency of amino‐methylated indoles and aminopyrazoles was examined by tetraline oxidation. Product studies were carried out. From the key intermediates isolated, conclusions capable of generalization on the mode of action as inhibitors of the compounds investigated were drawn. On this basis, the synthesis of more effective antioxidants was possible.

Tertiary amines of the general structure NCCCX are antioxidants when a) they can be easily transformed to N oxides by alkylhydroperoxides, and b) when the N oxides decompose readily yielding α, β‐unsaturated carbonyl compounds, and dialkylhydroxylamines and dialkyl nitroxyl radicals, respectively.

Aminopyrazoles act as chain‐breaking antioxidants in a multistep reaction. Pyrazolyl radicals and aminyl radicals are formed as is indicated by the subsequent products. Stable dihydrophenacines are isolated from the inhibited tetraline oxidation by aminopyrazoles. Evidence is presented that a rapid isomerization of pyrazole radicals yields aminyl radicals as precursors of dehydrophenacine.
Microindentation hardness of oriented chain‐extended polyethylene
Authors: Baltá‐Calleja F. J. , Bassett D. C.
Published: June 2010

The Knopp and Vickers microindentation hardnesses of oriented chain‐extended polyethylene (cold‐drawn, then hydrostatically annealed at 5·35 kbar) have been measured to establish correlations with some of the morphological features previously investigated (lamellar thickness, orientation). The irreversible deformation increases with time under load and tends towards a characteristic limiting value for each annealing temperature. This limiting value of microhardness is an increasing function of annealing temperature, TA, and consequently of chain extension, 1. A conspicuous feature of the investigated oriented polyethylene samples is the clear anisotropy exhibited by the indentation pattern. The Vickers microhardness is a maximum when the indenter diagonal lies parallel to the fiber direction and minimum when normal to it. The opposite occurs for the Knoop case. This contrary behavior is due to the shape difference between the two indenters coupled with the high anisotropy of the material. This behavior supports morphological experiments and is a further illustration of the value of this technique in polymer textural studies.
Observations of trimodal crystal texture in polypropylene blended with nylon 11
Authors: Seth K. K. , Kempster C. J. E.
Published: June 2010

X‐ray diffraction techniques, optical microscopy, and scanning electron microscopy have been used to study a series of melt‐spun bi‐constituent fibers containing isotactic polypropylene and nylon 11. The addition of small amounts of nylon 11 produces bimodal crystal texture in polypropylene with most crystallites having either their c‐axes or a‐axes oriented nearly parallel to the fiber axis. In blends containing about 50% nylon 11 a third polypropylene crystallite orientation is observed in which the [101] directions are oriented nearly parallel to the fiber axis. The polypropylene chain axes make an angle of about 50° to the fiber axis, and an additional set of layer lines is produced. In blends containing more than 50% nylon 11, most of the polypropylene crystallites adopt the third orientation. It is suggested that this third orientation of polypropylene crystallites is the result of epitaxy on portions of nylon 11 fold surface at the interface between the two components.
A current account of chain extension, fibrous crystallization, and fiber formation
Authors: Keller A.
Published: June 2010

A broad, rather personal survey is presented on chain alignment and fibrous crystallization. First, attention is drawn to the fact that fibrous crystal entities can be of fundamentally different origin and certain methods for their identification are proposed. Following this, the largest part of the survey is concerned with fibrous crystallization from pre‐extended molecules. As a first step, methods for extending chains and for observing their extension are outlined. Elongational flow is receiving special attention: conditions by which it can lead to ultrahigh chain extension are briefly defined as high‐lighted both by a priori considerations and by most recent experiments, methods of realizing these conditions being indicated both in solutions and melts. Following this, attention is given to the mode of crystallization of extended chains and to the structures which arise. Amongst the many factors involved, the part played by the local flow field arising from the presence of the growing crystal entity within the general flow field is outlined, leading up to the basic mechanism by which fibrous crystals grow. It is shown how the recognition of these principles can be utilized for producing crystalline fibers. The unusual thermal and mechanical properties of the products with special emphasis on melting behavior and modulus are indicated. A short section is devoted to the achievement of very high chain extensions by means of deforming material crystalline to begin with and the resulting products are contrasted with those obtained by means of crystallizing pre‐extended chains as regards thermal and mechanical behavior.
Problems and theories of polymer crystallization
Authors: Sanchez Isaac C.
Published: June 2010

This paper discusses four general problem areas and their associated theories: the relationship between crystal growth and nucleation; the concentration dependence of crystal growth rates; the crystallization of random copolymers, and the annealing (thickening) behavior of polymer crystals.
Small‐angle light scattering (SALS) from helically twisted fibers
Authors: Gałeski A. , Pakuła T. , Kryszewski M.
Published: June 2010

The small‐angle light scattering patterns for fibers with helical orientation were evaluated. The experimental results of the light scattering were obtained from two kinds of helically twisted fibers and compared with the theoretical prediction considering the refraction correction. The agreement with the theory was satisfactory.
Method of direct registration of the binary function of particles distributed in volume
Authors: Poltoratzkiy B. F. , Sachkov K. N.
Published: June 2010

A new method of registering the full binary distribution function of light‐scattering particles in volume is suggested. This method is based on a statistic analysis of space distribution for the intensity of coherent light scattering by particles in a volume. Theory and block diagrams illustrating the method are presented.
Influence of electric reorientation of molecules on the rotational broadening of the spectra of rayleigh light scattering by small macromolecules in solution
Authors: Alexiewicz W. , Buchert J. , Kielich S.
Published: June 2010

Spectral line broadening of Rayleigh scattered light in the presence of weak molecular reorientation is calculated by Racah algebra using the Debye rotational diffusion approximation. It is shown that if the incident beam is linearly polarized, the polarized and depolarized scattered components are superpositions of the well known Lorentzian, typical for free rotational diffusion, and non‐Lorentzian lines with intensities dependent on the reorientation parameters of the permanent and induced electric dipoles of the macromolecules. The measurement of electrically induced changes in peak intensity is proposed as a method for determining the sign of the optical polarizability anisotropy.
Adsorption of macromolecules on the solid adsorbents surfaces
Authors: Eltekov Yu. A. , Kiselev A. V.
Published: June 2010

A study has been made of polymer adsorption from dilute solutions by porous and nonporous adsorbents of different natures. Adsorption of linear polymer–elastomers from dilute solutions can be approximately described by the equation of monolayer adsorption. The positive adsorption of polymers on oxide adsorbents is observed in those cases where macromolecules have polar functional groups while the solvent molecules are nonpolar. Use of strongly polar solvents (alcohols and ketones), substantially decreases the adsorption of polymers on these adsorbents and, in some cases, leads to negative adsorption values. Chemical modification of the surface of oxide adsorbents also strongly affects the adsorption values, resulting in a change of their sign. In the case of porous adsorbents, the value of adsorption of macromolecules depends on the pore sizes; the negative one being due to a steric effect. It was possible, using a set of nonswelling adsorbents with a narrow pore‐size distribution, to estimate the molecular mass distribution for a polydisperse polymer.
X‐ray and optical studies of the morphology of polymer blends
Authors: Stein R. S. , Khambatta F. B. , Warner F. P. , Russell T. , Escala A. , Balizer E.
Published: June 2010

Blends may be made of pairs of polymers where neither, one, or both components are crystalline. The state of compatibility for such blends may be deduced by x‐ray and light scattering. A survey of recent studies in this laboratory of several binary blends of crystalline and amorphous polymers is presented.
Developments in radical polymerization
Authors: Vogl O.
Published: June 2010

Developments in the field of radical polymerization including co‐ and graft polymerization are evaluated from a personal viewpoint. A number of important advances have been made in the last few years which present the opportunity of opening new ways for further scientific and technological progress. Also included in this critical evaluation of developments in co‐ and graft polymerization primarily by radical initiators is work that is peripheral to the subject but constitutes possible important new directions of development.
Synthesis and characterization of rigid‐chain polyacenaphthylene
Authors: Chen Chi‐Yu , Piirma Irja
Published: June 2010

Rigid‐chain polyacenaphthylene (PAcN) was synthesized by a novel emulsion polymerization method that besides water and the sodium oleate emulsifier consisted of a water‐soluble initiator, K2S2O8, and the water‐insoluble (at the polymerization temperature 50°), crystalline monomer acenaphthylene. The molecular weight of the emulsion PAcN was 150, 000 by gel permeation chromatography (gpc). With the exception of a C13nuclear magnetic resonance study, the PAcN was characterized in the bulk state by infrared spectroscopy and x‐ray and electron diffraction. The C13nmr spectrum in solution suggests a macromolecular association. The infrared spectra indicate that the PAcN can be either paracrystalline or amorphous. An amorphous infrared band at 670 cm−1was identified. The emulsion PAcN is predominantly threo‐disyndiotactic, and it is possible, therefore, to have a mesophase of nematic type in the bulk state. The paracrystallinity or ordered structure of PAcN is supported by wide‐angle x‐ray and electron diffraction patterns.
Nematic polymers
Authors: Pincus P. , De Gennes P. G.
Published: June 2010

We present a primitive model that describes a cooperative helix‐coil liquid–crystal phase transition. Consider a solution of macromolecules that individually undergo a helix‐coil “transition” as a function of some external parameter such as temperature or pH. At some given value of the parameter, the chain is composed of a statistical distribution of rigid (helical) segments and flexible coiled segments. We then suppose that there exists an intermolecular Maier‐Saupe type of quadrupole‐quadrupole interaction between the rigid sections that derives from excluded volume and van der Waals forces. In terms of a mean‐field approximation, we investigate the possible phase transitions as a function of polymer concentration. In particular, we show that the intermolecular coupling may lead to a first‐order transition in which the macromolecules make a transition from a nearly coiled to a nearly rigid conformation accompanied by the simultaneous development of a long‐range nematic type of liquid‐crystalline orientational order.
Microscopic determination of the penetration of proteins and polysaccharides into poly(hydroxyethyl methacrylate) and similar hydrogels
Authors: Refojo Miguel F. , Leong Fee‐Lai
Published: June 2010

Ultraviolet and light microscopy were used to measure the depth of penetration of fluoresce‐in‐labeled dextrans, serum albumin, and lysozyme into hydrogels. Proteins were visualized by a staining technique. Hydroxyethyl methacrylate was bulk polymerized (PHEMA, 37.7% H2O) and solution polymerized (PHEMA, 41.05–42.90% H2O); poly(glyceryl methacrylate) was solution polymerized (PGMA, 76.0–84.8% H2O); and poly(GMA‐co‐methyl methacrylate) was bulk polymerized [P(GMA/MMA), 41.5% H2O]. Dextrans of up to 150,000 mol wt and lysozyme penetrated PHEMA hydrogels; dextrans, but not proteins, penetrated P(GMA/MMA) hydrogels. Albumin penetrated only in the higher hydrated PGMA hydrogels. The porosity of PHEMA hydrogels is at least as large as 30 Å (the smaller axis of lysozyme); the porosity of P(GMA/MMA) hydrogels is at least 19 Å (the thickness of the rodlike dextran molecules of 150,000 mol wt). The PGMA hydrogels have a porosity of at least 50 Å, which is the size of the smallest axis of serum albumin.
Synthesis of polyurethanes and investigation of their hydrolytic stability
Authors: Masař B. , Čefelín P. , Lipatova T. E. , Bakalo L. A. , Lugovskaya G. G.
Published: June 2010

Polyurethane films were prepared with poly(tetramethylene oxide) prepolymer, terminated with hexamethylene diisocyanate, and a polyfunctional diester of oxalic acid and glycerol, di‐(2,3‐dihydroxypropyl) oxalate (DHPO), or its mixtures with 3,6‐dioxaoctane‐1,8‐diol (DOD) as chain extender. Some mechanical characteristics of these films were ascertained. These samples are more readily hydrolyzed than those prepared with DOD alone; the hydrolyzability can be regulated by changing the DHPO/DOD ratio. The change in structure during the hydrolysis was investigated by differential thermal analysis (DTA).
Surface characterization of poly(hydroxyethyl methacrylate) and related polymers. I. Contact angle methods in water
Authors: Andrade J. D. , King R. N. , Gregonis D. E. , Coleman D. L.
Published: June 2010

The characterization of the gel‐water interface is considered, particularly with respect to obtaining the interfacial free energy between the gel and water, γ utilizing contact angle data. The question of contact‐angle‐induced deformation of the three‐phase region is examined and visual documentation of such deformation is presented. Air in water and octane in water contact‐angle data are used to estimate γdsv γpsv γsv, and γsw for the gel‐water interface as a function of bulk water fraction in the gel. It is shown that γ °0 ± 5 erg/cm2 when the bulk water fraction is greater than 0.2. All interfacial parameters determined appear to reach a constant value at a bulk water fraction of about 0.4. These results are for poly(hydroxyethyl methacrylate), poly(methoxyethyl methacrylate), poly(dihydroxypropyl methacrylate), and selected copolymers at 25°C in distilled water.
Polyarylacetylenes: Structure and properties
Authors: Simionescu C. I. , Percec V.
Published: June 2010

Considerable confusion exists in the literature concerning the structure and properties of polyarylacetylenes. Taking into account the significant structural aspects from the literature data with our recent results on the polypentadeuterophenylacetylene isomers, we present our findings concerning this class of polymer.
Organofunctional phosphazenes and organofunctional phosphazene polymers
Authors: Allen Christopher W.
Published: June 2010

Recent work has shown that the range of synthesis of new and useful phosphazene derivatives can be dramatically expanded by incorporation of an organofunctional substituent on the phosphazene ring. This substituent can serve as the site for various synthetic transformations leading to new monomeric and polymeric phosphazene moieties. Initial work on propenylphosphazenes and their copolymerization with organic monomers is briefly reviewed. The synthesis of new improved phosphazene monomers which lead to flame retardant copolymers is discussed. In addition to electron‐rich olefins such as alkoxylvinylphosphazenes, novel alkynlphosphazene/styrene copolymers were prepared. The vinyl alcohol derivative N3P3Cl5OCH=CH2 and related compounds were prepared and characterized. Both homopolymerization and a broad range of copolymerization reactions of N3P3Cl5OCH=CH2 are presented. The properties of these systems can be modified by reactions of the cyclophosphazene units in the polymer.
Diffusion‐limited gelation
Authors: Witten T. A.
Published: June 2010

Diffusion‐limited aggregation is a means of forming continuous random networks of low density. Recent work on diffusion‐limited aggregation is reviewed. These aggregates have universal power‐law density correlations. This implies scaling laws relating an aggregate's size to its mass when it is grown from a point, line, or surface. The mass of the growing interface scales as a power of the total mass, but not in the way suggested by simple estimates. A mean field model of the process yields a density that falls inversely as the distance from the origin. It is speculated that the mean field solution may be stable above some spatial dimension dc.
Homodinuclear f–f and Heterodinuclear f–p Lanthanide Helicates
Authors: Albrecht Markus
Published: June 2010

Lanthanide helicates are of interest due to their ability to emit either in the visible or in the NIR region. In this context it is important to prepare heterodinuclear helicates and to use them for the investigation of intramolecular communication processes between different complex units. In here we describe the ligand synthesis and self‐assembly of homo‐ and heterodinuclear helicates based on β‐diketonate, catechol‐acyl hydrazone and 2‐amido‐8‐hydroxyquinoline ligands. Strongly emitting homodinuclear europium(III) complexes are obtained in addition to heterodinuclear coordination compounds. Some of the latter exhibit intramolecular energy transfer behaviour with internal quenching of an aluminium trisquinolinate and enhancement of the NIR emission at an ytterbium(III), neodymium(III) or erbium(III) complex unit.
Transcriptional suppression of breast cancer resistance protein (BCRP) by wild‐type p53 through the NF‐κB pathway in MCF‐7 cells
Authors: Wang Xuedong , Wu Xingang , Wang Chengkun , Zhang Weijia , Ouyang Yongmei , Yu Yanhui , He Zhimin
Published: June 2010

Breast cancer resistance protein (BCRP) has been shown to confer multidrug resistance, but the mechanisms of its regulation are poorly understood. Here, we investigate the effects of wild‐type and mutant p53, and nuclear factor kappa‐B (NF‐κB) (p50) on BCRP promoter activity in MCF‐7 cells. Our results demonstrated that wild‐type p53 markedly suppressed BCRP activity and enhanced the chemosensitivity of cells to mitoxantrone, whereas mutant p53 had little inhibitory effect. After inhibition of NF‐κB, similar results were obtained. Following knockdown of endogenous p53, BCRP and p50 expressions were increased, and the chemosensitivity of the cells to mitoxantrone was decreased. We conclude that wild‐type p53 acts as a negative regulator of BCRP gene transcription.
Loss of Trx‐2 enhances oxidative stress‐dependent phenotypes in Drosophila
Authors: Tsuda Manabu , Ootaka Ryousuke , Ohkura Chiaki , Kishita Yoshihito , Seong Ki-Hyeon , Matsuo Takashi , Aigaki Toshiro
Published: June 2010

Overexpression of thioredoxin (TRX) confers oxidative stress resistance and extends lifespan in mammals and insects. However, less is known about phenotypes associated with loss of TRX. We investigated loss‐of‐function phenotypes of Trx‐2 in Drosophila, and found that the mutant flies are hyper‐susceptible to paraquat, a free radical generator, but not to hydrogen peroxide. They contain a high amount of protein carbonyl, which dramatically increases with age. Trx‐2 mutants express high levels of anti‐oxidant genes, such as superoxide dismutase, catalase, and glutathione synthetase. This is the first demonstration of biochemical and physiological consequences caused by loss of Trx‐2 in Drosophila.
The Impact of Obesity on Gynecologic Cancer Screening: An Integrative Literature Review
Authors: Aldrich Tess , Hackley Barbara
Published: June 2010

Introduction: Evidence indicates lower rates of breast and cervical cancer screening among obese compared to nonobese women. This integrative review examines the association between gynecologic cancer screening and body weight, as well as potential barriers to screening.

Methods: A literature search of standard computerized databases was conducted for peer‐reviewed articles published between 1950 and January 2009.

Results: Twenty‐three studies met the criteria for review. Of the 17 studies that evaluated rates of cervical cancer screening, 13 found obese women significantly less likely than their nonobese counterparts to have had a recent Papanicolaou test, a trend that was stronger in white women when compared to African American women. Eight of the 15 studies examining routine mammography found an inverse association between increasing body weight and recent screening, although findings generally pertained only to women who were white and/or severely obese. Possible barriers to care included embarrassment and perceived weight stigma in the clinical setting, lack of appropriately sized examination equipment, and poor patient–provider communication.

Discussion: Further research is needed to clarify the challenges that obese women face in accessing care and to evaluate strategies such as ensuring the availability of appropriate equipment and supplies, the use of alternative screening methodologies, and more culturally sensitive counseling approaches that may improve screening rates in obese women.

J Midwifery Womens Health 2010;55:344–356 © 2010 by the American College of Nurse‐Midwives.
Investigation of suction for laminar flow control of three-dimensional boundary layers
Authors: MESSING RALF , KLOKER MARKUS J.
Published: June 2010

Direct numerical simulations are employed to investigate the effects of discrete suction orifices at the wall on the disturbance evolution in laminar three-dimensional boundary-layer flows with favourable pressure gradient. Suction panels with many suction orifices can excite unstable crossflow (CF) modes even if the orifice spacing is smaller than the chordwise/spanwise wavelengths of unstable modes, caused by imperfections in the orifice order or suction strength. It has been found that the most unstable steady vortex mode leads to strong CF vortices that invoke turbulence by secondary instability even on the active suction panel. The deliberate excitation and support of stabilizing vortices that have less than two-thirds of the spanwise wavelength of the most amplified ones – known from the upstream flow deformation or micrometre-sized roughness elements technique – by the orifice order on the panel can secure the desired stabilizing effect of suction and lower the necessary suction amount significantly.
Quadrant analysis of a transitional boundary layer subject to free-stream turbulence
Authors: NOLAN K. P. , WALSH E. J. , McELIGOT D. M.
Published: June 2010

This paper presents analyses of particle image velocimetry measurements from a boundary layer on a flat plate subject to grid-generated free-stream turbulence. The pre-transition region and early stages of breakdown to turbulent spots are explored by means of quadrant analysis and quadrant hole analysis. By isolating the contributors to the Reynolds shear stresses, it is possible to identify coherent structures within the flow that are responsible for the production of TKE. It is found that so called ‘ejection’ events are the most significant form of disturbance, exhibiting the largest amplitude behaviour with increased negative spanwise vorticity. Sweep events become increasingly large close to the wall with increased Reynolds number and intermittency.
Instabilities of buoyancy-driven coastal currents and their nonlinear evolution in the two-layer rotating shallow-water model. Part 1. Passive lower layer
Authors: GULA J. , ZEITLIN V.
Published: June 2010

Buoyancy-driven coastal currents, which are bounded by a coast and a surface density front, are ubiquitous and play essential role in the mesoscale variability of the ocean. Their highly unstable nature is well known from observations, laboratory and numerical experiments. In this paper, we revisit the linear stability problem for such currents in the simplest reduced-gravity model and study nonlinear evolution of the instability by direct numerical simulations. By using the collocation method, we benchmark the classical linear stability results on zero-potential-vorticity (PV) fronts, and generalize them to non-zero-PV fronts. In both cases, we find that the instabilities are due to the resonance of frontal and coastal waves trapped in the current, and identify the most unstable long-wave modes. We then study the nonlinear evolution of the unstable modes with the help of a new high-resolution well-balanced finite-volume numerical scheme for shallow-water equations. The simulations are initialized with the unstable modes obtained from the linear stability analysis. We found that the principal instability saturates in two stages. At the first stage, the Kelvin component of the unstable mode breaks, forming a Kelvin front and leading to the reorganization of the mean flow through dissipative and wave–mean flow interaction effects. At the second stage, a new, secondary unstable mode of the Rossby type develops on the background of the reorganized mean flow, and then breaks, forming coherent vortex structures. We investigate the sensitivity of this scenario to the along-current boundary and initial conditions. A study of the same problem in the framework of the fully baroclinic two-layer model will be presented in the companion paper.
Training the Next Generation of Teaching Professors: A Comparative Study of Ph.D. Programs in Political Science
Authors: Ishiyama John , Miles Tom , Balarezo Christine
Published: June 2010

In this article, we investigate the graduate curricula of political science programs and 122 Ph.D.-granting political science programs in the United States and how they seek to prepare political science teachers. We first investigate whether the department offers a dedicated political science course at the graduate level on college teaching, and whether the presence of this class correlates with the size of the department, the size of the university, the ranking of the department, and so on. We find that whether a program offers a graduate course on teaching is inversely related to the research productivity of a department, and that departments at public institutions are more likely to offer such courses than are departments at private institutions. Second, we conduct content analysis of a sample of syllabi from departments that offer such courses to ascertain the kinds of topics that are covered. Finally, we briefly describe some model programs that seek to prepare graduate students for teaching careers that integrate graduate student teacher training throughout the Ph.D. program.
Getting the Most from Classroom Simulations: Strategies for Maximizing Learning Outcomes
Authors: Wedig Timothy
Published: June 2010

Classroom simulations can make a significant contribution to learning outcomes in political science courses, provided that they are firmly linked to course content and learning objectives. This article offers a step-by-step decision framework for instructors seeking to use simulations as a core component of their courses, including selection of an exercise, pre-simulation preparation, instructor role during a simulation, and techniques for debriefing after the exercise. Options such as online and face-to-face, synchronous and asynchronous, distributed and single classroom, and individual and team formats are compared, with a focus on their associated learning outcomes.
TRIBUTES TO JOHN HOPE FRANKLIN
Authors: Holt Thomas C.
Published: June 2010

Mirror to America, the title John Hope Franklin gave his autobiography, implied that one might recognize important themes of the nation's life-story in his own. Be that as it may, it is indisputable that in his life one can find the main themes and plot lines of the professional study of African American history, both its origins and its maturation, in the twentieth century.
FORECASTING AND PREDICTING THE ELECTION OF AN AFRICAN AMERICAN PRESIDENT
Authors: Walton Hanes , Allen Josephine A. V. , Puckett Sherman C. , Deskins Donald R. , Starks Robert T.
Published: June 2010

Beginning with the 1972 presidential election and for each election thereafter Harvard University's Institute of Politics in the John F. Kennedy School of Government has held a post-election symposium where all of the campaign managers, pollsters, political consultants and media advisors for all of the primary and general election candidates come together with leading journalists, electronic and print, and political commentators and pundits to discuss and dialogue about what occurred during the election among the candidates, nominees, and the winner and losers. The symposia have allowed campaign managers to describe what happened and forecast for the forthcoming presidential election. After the multi-day symposium a book length transcript is published. In 1992 the Annenberg School of Communication at the University of Pennsylvania launched its own symposia where the campaign managers of the Democratic and Republican nominees in the general election are invited to discuss what happened and forecast for the next presidential election. The ten books in the Harvard series and the three books in the Pennsylvania series are used as data sources in this article to determine if any of the campaign managers forecasted and/or predicted an African American presidential candidate, even when such candidates had appeared in previous years. While our findings uncover some of the interests and concerns of presidential campaign managers and advisors since 1972, the overriding focus of the symposia has been on the nature, scope, and significance of the African American electorate.
Size and location of cusp diamagnetic cavities observed by Polar
Authors: Niehof Jonathan T. , Fritz Theodore A. , Friedel Reinhard H. W. , Chen Jiasheng
Published: June 2010

We examine 6 years of cusp crossings by the Polar spacecraft to determine the size and solar wind dependence of cusp diamagnetic cavities (CDCs) and energetic particle events (CEPs). Both are frequently observed (about 50% of the time spent in the cusp). Neither shows a strong statistical dependence on upstream conditions beyond variations in the cusp itself. CEPs are found throughout the cusp, peaking near the magnetopause. CDCs are primarily found near local noon and close to the magnetopause, forming an extended region against the magnetopause.
Fully coupled hydrogeophysical inversion of synthetic salt tracer experiments
Authors: Pollock Davina , Cirpka Olaf A.
Published: June 2010

We present a method for the determination of hydraulic conductivity from monitoring of salt tracer tests by electrical resistivity tomography (ERT). To ensure that the underlying principles of flow, transport, and geoelectrics are obeyed in the inversion, we perform a fully coupled hydrogeophysical analysis using temporal moments of electrical potential perturbations. In the predictive mode, we use moment‐generating equations with corresponding adjoint equations for the evaluation of sensitivities. For inversion, we apply the quasi‐linear geostatistical inversion approach. The method is tested in a synthetic case study mimicking a laboratory‐scale quasi two‐dimensional sandbox, in which 48 electrodes and 8 piezometers are used. The hydraulic conductivity field is estimated from the mean arrival times of electrical potential perturbations and hydraulic heads. The estimated hydraulic conductivity field reproduces most features with, however, a loss of variability. Even though only the temporal moments of the electrical signals are used for inversion, the transient behavior is satisfactorily recovered. Also, the spatial patterns of concentration arrival times in the true and estimated cases are in good agreement, so that the propagation of the tracer plume can be followed fairly accurately. We test the effects of large measurement errors and erroneous prior information on the performance of the inversion. While prior statistical parameters are of minor importance in detecting the major pattern of hydraulic conductivity, a large measurement error could have an important impact on the solution. Also, the choice of electrode configurations appears to be important. In particular, strictly surface‐based geoelectrical surveys do not seem to be very suitable for identifying spatial patterns of hydraulic conductivity by ERT monitoring of salt tracer tests within aquifers.
Droplet actuation on a liquid layer due to thermocapillary motion: Shape effect
Authors: Yakhshi-Tafti Ehsan , Cho Hyoung J. , Kumar Ranganathan
Published: June 2010

In the thermocapillary migration of droplets on the free surface of immiscible liquids, we observe that the lens-shaped drops move from warm toward cooler regions while spherical drops move in the opposite direction. We explain this dual behavior using an analysis of surface deformation and velocity profiles of thin liquid layers subject to a lateral thermal gradient. Liquid platforms allow thermocapillary transport of drops with higher migration speeds than solid substrates and lower internal temperature fluctuation. Such conditions may be exploited in biochemical microsystems where droplet evaporation, contamination, and surface pinning need to be avoided.
Drain current modulation in a nanoscale field-effect-transistor channel by single dopant implantation
Authors: Johnson B. C. , Tettamanzi G. C. , Alves A. D. C. , Thompson S. , Yang C. , Verduijn J. , Mol J. A. , Wacquez R. , Vinet M. , Sanquer M. , Rogge S. , Jamieson D. N.
Published: June 2010

We demonstrate single dopant implantation into the channel of a silicon nanoscale metal-oxide-semiconductor field-effect-transistor. This is achieved by monitoring the drain current modulation during ion irradiation. Deterministic doping is crucial for overcoming dopant number variability in present nanoscale devices and for exploiting single atom degrees of freedom. The two main ion stopping processes that induce drain current modulation are examined. We employ 500 keV He ions, in which electronic stopping is dominant, leading to discrete increases in drain current and 14 keV P dopants for which nuclear stopping is dominant leading to discrete decreases in drain current.
Evidence of graphene-like electronic signature in silicene nanoribbons
Authors: De Padova Paola , Quaresima Claudio , Ottaviani Carlo , Sheverdyaeva Polina M. , Moras Paolo , Carbone Carlo , Topwal Dinesh , Olivieri Bruno , Kara Abdelkader , Oughaddou Hamid , Aufray Bernard , Le Lay Guy
Published: June 2010

We report on the electronic properties of straight, 1.6 nm wide, silicene nanoribbons on Ag(110), arranged in a one-dimensional grating with a pitch of 2 nm, whose high-resolution scanning tunneling microscopy images reveal a honeycomb geometry. Angle-resolved photoemission shows quantum confined electronic states of one-dimensional character. The silicon band dispersion along the direction of the nanoribbons suggests a behavior analogous to the Dirac cones of graphene on different substrates.
Reduction in the efficiency droop effect of a light-emitting diode through surface plasmon coupling
Authors: Lu Chih-Feng , Liao Che-Hao , Chen Chih-Yen , Hsieh Chieh , Kiang Yean-Woei , Yang C. C.
Published: June 2010

The reduction in the external quantum efficiency (EQE) droop effect of an InGaN/GaN quantum-well (QW) light-emitting diode (LED) through the mechanism of surface plasmon (SP) coupling with QW is demonstrated. With a current spreading grid pattern on the mesa surface, a smaller grid period leads to more effective carrier transport into the QW regions of Ag deposition for stronger SP–QW coupling such that the droop effect is more significantly reduced, as indicated by the increase in injection current density of maximum EQE and the decrease in drooping slope. The claim of the SP–QW coupling effect in the samples of thin p-GaN is supported by the different droop behaviors of the LED samples fabricated with another epitaxial structure of thick p-GaN, in which the SP–QW coupling effect is expected to be weak.
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phase class materials with hydrogen: Ti4AlH3 and Ti3AlH2
Authors: Ramzan M. , Ahuja R.
Published: June 2010

To date more than 50 MAX phases known to exist but all of those are consist of nitrides or carbides. We present a modified type of these phases, Ti4AlH3 and Ti3AlH2, having hydrides in their composition, by our density functional theory (DFT) calculations. We study the structural stability, electronic structure, elastic, thermal, and mechanical properties of these materials which are comparable with well known phases: Ti3SiC2, Ti4AlN3, and Ti3AlC2. Moreover, these materials can also be studied for hydrogen storage purposes. We hope that our work will be helpful to discover the other types of such phases which are important from the technological and industrial point of view.
Erratum to: Who owns feral camels? Implications for managers of land and resources in central Australia
Authors: Garnett Stephen T. , Williams Greg , Ainsworth Gillian B. , O'Donnell Michael
Published: June 2010

This paper reviews the legislation relating to ownership of feral camels in Australia. We find that, as a general proposition, a feral camel is owned by neither the landowner nor the Government (the Crown), unless State or Territory legislation provides otherwise. This occurs in two limited situations and only for New South Wales and South Australia. Relevant State and Territory legislation can prescribe that feral camels cannot be taken or used without a relevant licence or permit, but only Western Australia and Queensland appear to do this. Lack of legislative certainty about ownership of camels has resulted in a clear market failure whereby there is also little or no private incentive to exercise control. This should be corrected by identifying explicitly that ownership is vested in the Crown. Legal analogues exist with respect to disease control and water management that could form the basis of an appropriate legislative framework.
Forb responses to grazing and rest management in a critically endangered Australian native grassland ecosystem
Authors: Zimmer Heidi C. , Turner Vivienne B. , Mavromihalis Jaimie , Dorrough Josh , Moxham Claire
Published: June 2010

Worldwide, temperate grasslands have been extensively cleared for agriculture and urban expansion and the ‘Natural Temperate Grassland of the Victorian Volcanic Plain’ in south-eastern Australia has recently been listed as critically endangered. Because of land clearing, these grasslands now occupy <1% of their original distribution and much of the remaining grassland continues to be grazed by livestock. Although forbs (wildflowers) constitute most of the floristic richness in natural grasslands, few experimental studies have focused on their responses to strategic livestock grazing and rest. This paper reports on the outcomes of five grazing and rest management regimes imposed for 4 years at three sites on the Victorian Volcanic Plain. Seasonal grazing and rest management regimes resulted in significantly different native and exotic forb frequencies, but not richness. Native perennial and exotic annual forb frequency was higher when management incorporated grazing and rest periods (14 and 16% deviance explained), particularly with spring rest from grazing. However, the most important influence on native perennial and exotic annual and perennial forb frequency (46, 58 and 41% deviance explained) and native perennial and exotic annual species richness (62 and 35% deviance explained) was site. Differences among the three sites included soil, rainfall, size of remnant, presence of small burrowing mammals, management history and consequent species assemblages. Despite differences among sites, the results indicate that native perennial forb frequency may be increased using management regimes that incorporate both grazing and rest. However, targeted management may be necessary to reduce exotic annual forbs, also promoted by grazing with seasonal rest.