bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of double bubble tubular film extrusion of polyamide 6 and film structural characteristics
Authors: Rhee Sangkeun , White James L.
Published: April 2004

Biaxially oriented polyamide 6 films were made by double bubble tubular film extrusion. The crystalline character and biaxial orientation of the films were investigated by measuring (in plane and out of plane) birefringences, IR (infrared) spectroscopy, and wide angle X‐ray diffraction (WAXS) flat film patterns and pole figures. The samples were also examined by tensile stretching tests in different sampling directions.
Integrated numerical modeling of the blow molding process
Authors: Laroche D. , Kabanemi K. K. , Pecora L. , Diraddo R. W.
Published: April 2004

The numerical modeling of the extrusion blow molding of a fuel tank is considered in this work. The integrated process phases are consecutively simulated, namely, parison formation, clamping, and inflation, as well as part solidification, part deformation (warpage), and the buildup of residual stresses. The parison formation is modeled with an integral type viscoelastic constitutive equation for the sag behavior and a semi‐empirical equation for the swell behavior. A nonisothermal viscoelastic formulation is employed for the clamping and inflation simulation, since parison cooling during extrusion strongly affects the inflation behavior. Once the parison is inflated, it solidifies while in the mold and after part ejection. Warpage and residual stress development of the part are modeled with a linear viscoelastic solid model. Numerical predictions are compared with experimental results obtained on an industrial scale blow molding machine. Good agreement is observed. A process optimization based on a desired objective function, such as uniform part thickness distribution and/or minimal part weight, is performed. The integrated clamping, inflation, and cooling stages of the process are considered. The optimization is done by the systematic manipulation of the parison thickness distribution. Iterations are performed employing a gradient based updating scheme for the parison thickness programming, until the desired objective of uniform part thickness is obtained.
Interfacial tension of polypropylene/polystyrene: Degradation of polypropylene
Authors: Visscher E. J. , Willemse R. C.
Published: April 2004

The coefficient of the decrease of the interfacial tension of polypropylene/polystyrene with temperature is considerably higher than the value of other polymer pairs. This coefficient can be estimated by considering the change of the interaction parameters with temperature, but this approach fails for polypropylene/polystyrene, and other mechanisms are expected to play a role. In this paper it is shown that polypropylene starts to degrade at higher temperatures, leading to smaller polymer chains, which decrease the interfacial tension. Besides the change of the interaction parameters with temperature, these smaller molecules also contribute to the temperature coefficient, leading to an apparently high coefficient. The smaller molecules, however, lead to a permanent lower interfacial tension, e.g. the interfacial tension of polypropylene/polystyrene at 200°C is 4.9, 3.9, and 3.0 mN/m, if the polypropylene is first processed at 200, 250, and 300°C, respectively.
A study on the effects of chaotic mixer design and operating conditions on morphology development in immiscible polymer systems
Authors: Sau Madhusudan , Jana Sadhan C.
Published: April 2004

Self‐similar mixing structures, a novel feature of chaotic mixing, were generated in this study as precursor to an array of mixing microstructures, such as nested layers, elongated fibrils, droplets and their combinations in the blending of two immiscible polymers, polypropylene (PP) and polyamide‐6 (PA6). Simulations based on Newtonian flow model were used to compute Poincaré maps and stretching distribution as the tools for investigation of the effect of shear gap and chaotic mixing parameter, such as angular displacement per period (θ) of rotors, on the degree of mixing and morphology development in a batch chaotic mixing device. It was found that a value of θ = 1440° provided the conditions for fastest conversion of the PP‐phase into droplets for the same total strain. A 25% reduction in shear gap from 0.0127 m to 0.0095 m gave rise to much more uniform mixing of the components and led to faster conversion of the PP‐phase into droplets for the same value of θ and the same total strain. A very large fraction (>90%) of the droplets generated fell below the equilibrium size and were found to be much smaller than those produced by twin‐screw extrusion method. Polym. Eng. Sci. 44:407–422, 2004. © 2004 Society of Plastics Engineers.
Heat transfer behavior of melting polymers in laminar flow field
Authors: Sato Sadao , Oka Kenichiro , Murakami Akihiko
Published: April 2004

Heat transfer coefficients were investigated by insertion of a probe into melting polymers under laminar flow at 200–240°C and a flow velocity of 0.5–2.7 mm/sec. The average heat transfer coefficients of melting polypropylene (PP) and polystyrene (PS) were found to be 160–220 W/m·°C and 180–270 W/m·°C, respectively. These coefficients show remarkable dependence on flow velocity, and the average heat transfer coefficient of PS is about 13%–23% higher than that of PP. When the flow velocity of flowing melting PP and PS exceeds about 0.078mm/sec, heat transfer by convection becomes dominant, whereas under lower flow velocities, since the equivalent conduction layer thickness δ′ in which the quiescent state without flow approaches infinity, heat transfer by conduction becomes dominant. The Prandtl number (Pr) and Nusselt number (Nu) of melting PP are 125–133 × 106 and 38.6–51.4, respectively, and those of melting PS are 63–64 × 106 and 42.3–61.3. In the case of constant flow velocity, the Peclet number (Pe) and Stanton number (St) are dependent on the specific heat of melting polymer. Polym. Eng. Sci. 44:423–432, 2004. © 2004 Society of Plastics Engineers.
Model filled polymers: The effect of particle size on the rheology of filled poly(methyl methacrylate) composites
Authors: Li Joshua Qingsong , Salovey Ronald
Published: April 2004

The effect of size of crosslinked monodisperse spherical polymer particles on the steady shear and dynamic rheology of filled poly(methyl methacrylate) (PMMA) composites was studied for PMMA and polystyrene (PS) particles in the range from 0.1 to 1.3 micron particle size. For PMMA matrices filled with crosslinked PS particles, reduction in filler size increases non‐Newtonian behavior. Particle size effects on the rheology of filled PMMA were much less pronounced for PMMA filler. The rate of growth of steady shear viscosity with aging time was much larger for PMMA filled with PS particles than with PMMA particles. The apparent yield stress of filled PMMA composites was estimated from Casson plots. The yield stress was negligible for PMMA filler but increased with decreasing particle size for PS filler. We suggest that PS particles are rejected by the PMMA matrix and form clusters, causing large enhancements in viscosity and moduli. Polym. Eng. Sci. 44:452–462, 2004. © 2004 Society of Plastics Engineers.
A phenomenological constitutive model for foams under large deformations
Authors: Liu Qunli , Subhash Ghatu
Published: April 2004

A nonlinear phenomenological constitutive model applicable to structural foams subjected to large deformations is proposed. The five‐parameter model can fully capture the three fundamental features of stress‐strain response, i.e., linearity, plasticity‐like stress plateau, and densification phases, when subjected to compressive loads. Moreover, the parameters of the model can be systematically varied to capture the influence of initial density of foams that may be responsible for changes in yield stress and hardening‐like or softening‐like behavior under various confinement conditions. The model was successfully applied to capture the stress‐strain response of two structural foams of different initial densities when subjected to uniaxial compression without lateral confinement and unixial compression under rigid confinement. Polym. Eng. Sci. 44:463–473, 2004. © 2004 Society of Plastics Engineers.
Structural changes of PVC in PVC/LDPE melt‐blends: Effects of LDPE content and number of extrusions
Authors: Sombatsompop N. , Sungsanit K. , Thongpin C.
Published: April 2004

This paper investigates the structural changes of polyvinyl chloride (PVC) in melt‐blends of a low‐density polyethylene (LDPE) and polyvinyl chloride (PVC), and the effects of LDPE content and number of extrusion passes. These effects were examined in terms of changes in weight average molecular weight and number average molecular weight, polyene and carbonyl indices, color changes of the blend, and the variations in glass transition and decomposition temperatures. It was found that loading LDPE into PVC led to the formation of short‐chain LDPE grafted PVC (s‐LDPE‐g‐PVC) copolymers, via a macro‐radical cross‐recombination reaction, which had greater weight average molecular weight with unchanged number average molecular weight, increased decomposition temperature, lower glass transition temperature, as compared to the pure PVC sample. The dehydrochlorination reaction of PVC was suppressed by the macro‐radical cross‐recombination reaction with addition of LDPE, the effect being more pronounced at 13.0 wt% LDPE. For a given LDPE content, the macro‐radical cross‐recombination and dehydrochlorination reactions competed with one another, thus causing the increases in molecular weight average and molecular weight number up to the 4th extrusion pass. At the 5th extrusion pass, the dehydrochlorination reaction was predominant owing to a depletion of LDPE content to be grafted onto PVC molecular chains. The glass transition and decomposition temperature decreased with increasing number of extrusion passes. Polym. Eng. Sci. 44:487–495, 2004. © 2004 Society of Plastics Engineers.
Improvement of the processability of poly(ether ketone ketone) by the addition of a thermotropic liquid crystalline polymer
Authors: Son Younggon , Chun Yong Sung , Weiss R. A.
Published: April 2004

The addition of a thermotropic liquid crystalline, wholly aromatic copolyester, TLCP, improved the melt processability of poly(ether ketone ketone), PEKK. The tensile strength and modulus of the blends also improved with increasing TLCP, but the elongation at break decreased significantly. The blends were phase‐separated, but the polymers were partially miscible as evident from shifts of the glass transition temperature (Tg) of each component towards that of the other component in the blend. Similarly, the melting points (Tm) of both components were depressed by blending. When the crystallization temperature was above Tm of the TLCP, the PEKK crystallization rate in the blend was slower than for the pure material, while crystallization was faster when the temperature was below Tm of the TLCP. Polym. Eng. Sci. 44:541–547, 2004. © 2004 Society of Plastics Engineers.
Achieving diversity among fundraising professionals
Authors: Wagner Lilya , Ryan J. Patrick
Published: April 2004

Fundraising still lags behind in the universal push toward representation by diverse populations in the United States. Lack of diversity in the profession presents both problems and opportunities.
Gender differences in giving: Going, going, gone?
Authors: Hall Holly
Published: April 2004

Some researchers question whether commonly assumed sex differences in charitable giving exist. The author takes a look at the evidence.
Recycling PET beverage bottles and improving properties
Authors: Oromiehie Abdulrasoul , Mamizadeh Alireza
Published: April 2004

Recycling PET from bottles has been carried out by three different extrusion methods. Under optimized processing conditions, a virgin poly(ethylene terephthalate (PET), recycled PET and a mixture of virgin and recycled PET, with and without the modifier polypropylene functionalized with maleic anhydride [PP‐graft‐MA]), were processed. Different methods were used to characterize the processed products. The results showed that the intrinsic viscosity and molecular weight decreased as the blend ratio of recycled PET was increased. This was due to thermal exposure as well as shear degradation of recycled PET. Thermal cycles of the processes used for recycling PET and its blending specimens with virgin PET show the importance of the thermal treatment in the improvement of mechanical strength and increased crystallinity. Nevertheless, the properties of the functionalized blends were improved. This behaviour is attributed to a series of chemical and physico‐chemical interactions taking place between the two components. Copyright © 2004 Society of Chemical Industry
Plausible guard effect on the active sites of heterogeneous Ziegler–Natta catalyst by coordinating monomers and growing polymer chains in the initial stage of propene polymerization
Authors: Murayama Namiko , Liu Boping , Nakatani Hisayuki , Terano Minoru
Published: April 2004

Investigation of propene polymerization by a modified stopped‐flow technique using TiCl4/ethylbenzoate(EB)/MgCl2 Ziegler–Natta catalyst with or without pretreating the catalyst with triethylaluminium (TEA) within an ultra‐short period (ca 1 s) was conducted to gain new understanding of the nature of active sites related to TEA in the early stage of polymerization. When the catalyst was pretreated by a cocatalyst, deactivation behaviour was clearly observed, even within an extremely short pretreatment period. In contrast, without pretreatment, the deactivation of active sites can be neglected within the polymerization period indicating that the activated Ti species might be protected from deactivation by TEA when monomer is present in the system. A plausible guard effect on the active sites by coordinating monomer and growing polymer chains in the initial stage of polymerization is proposed to account for this phenomenon. Copyright © 2004 Society of Chemical Industry
Micellization to gelation of a triblock copolymer in water: Thermoreversibility and scaling
Authors: Lau Boon Kiak , Wang Qiqiang , Sun Wei , Li Lin
Published: April 2004

Aqueous solutions of a poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) triblock copolymer, Pluronic F108 (PEO133PPO50PEO133), ranging from 1 to 35 wt %, were studied with differential scanning microcalorimetry and rheology. The thermoreversible micellization and gelation were examined through a heating process and a subsequent cooling process at a fixed rate of 1 °C/min. The critical micellization temperature (CMT), determined by the onset temperature of the endothermic peak in the heating process, was a decreasing function of the F108 concentration. A small secondary endothermic peak appeared only when the polymer concentration was 22.5 wt % or higher, indicating that there was a sol–gel transition but that the gelation was a nearly athermic process. Upon heating, an abrupt increase was observed in both the dynamic storage modulus (G′) and dynamic loss modulus (G″) within a narrow temperature range. TG′, the temperature for the transition in G′, was a linear decreasing function of the polymer concentration and different from CMT. TG′ tended to approach CMT with an increasing F108 concentration. Beyond this transition, G′ reached a plateau, and the plateau increased in height and broadened with the polymer concentration. The value of G′ at 70 °C (G′70) could be approximately scaled with concentration c by G′70 ∝ c7.3. In addition, the definition for a gel to obey G′ > G″ was valid only when c was greater than 22.5 wt %, and this was in agreement with the secondary endothermic peak found with differential scanning calorimetry. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2014–2025, 2004
Decreased stromal expression and increased epithelial expression of WFDC1/ps20 in prostate cancer is associated with reduced recurrence‐free survival
Authors: McAlhany Stephanie J. , Ayala Gustavo E. , Frolov Anna , Ressler Steven J. , Wheeler Thomas M. , Watson J.E. Vivienne , Collins Colin , Rowley David R.
Published: April 2004

BACKGROUND

WAP‐type four disulfide core (WFDC1)/ps20 is a member of the whey acidic protein family, which includes several serine protease inhibitors. Expression of WFDC1/ps20 was previously demonstrated in the normal human prostate stromal compartment. To further current understanding of the role of WFDC1/ps20 in prostate cancer, altered expression of WFDC1/ps20 protein in prostate cancer was evaluated.

METHODS

Immunohistochemical staining for WFDC1/ps20 was performed using tissue microarrays. Quantitation was based on the percentage of positive‐staining stromal or epithelial cells and staining intensity. Resulting data was analyzed relative to the recurrence‐free survival data and additional information for this patient set.

RESULTS

Decreased stromal expression of WFDC1/ps20 predicted shorter recurrence‐free survival time by univariate analysis. Decreased stromal WFDC1/ps20 expression correlated with higher radical prostatectomy Gleason scores, positive surgical margins, extracapsular extension, higher clinical stage, and higher preoperative prostate specific antigen levels. Increased epithelial expression of WFDC1/ps20 also predicted shorter recurrence‐free survival times by univariate analysis. Increased epithelial expression of WFDC1/ps20 correlated with higher biopsy and radical prostatectomy Gleason scores, and higher clinical stage.

CONCLUSIONS

Decreased stromal WFDC1/ps20 expression reflects the evolution of a prostate cancer reactive stroma, while increased epithelial WFDC1/ps20 expression may indicate progression to a more aggressive epithelial phenotype and may indicate an epithelial mesenchymal transition (EMT) process. Further evaluation of WFDC1/ps20 biologic functions will aid in the understanding of this interesting expression profile. © 2004 Wiley‐Liss, Inc.
Fumigation toxicity of volatile natural and synthetic cyanohydrins to stored‐product pests and activity as soil fumigants
Authors: Park Dong‐Sik , Peterson Chris , Zhao Shaohan , Coats Joel R
Published: April 2004

Insecticidal fumigation toxicity of natural and synthetic cyanohydrins was evaluated with four stored‐product pests: the lesser grain borer,Rhyzopertha dominica(F), the red flour beetle,Tribolium castaneumHerbst, the saw‐toothed grain beetleOryzaephilus surinamensisL, the maize weevil,Sitophilus zeamais(Motsch) and the house fly,Musca domesticaL. The fumigation LC50values were calculated by probit analysis. For house flies, all but one of the cyanohydrins tested were more potent than 1,3‐dichloropropene (Telone®). Three were as efficacious as chloropicrin. For the lesser grain borer, all cyanohydrins tested were more insecticidal than dichloropropene, and all but one were more potent than chloropicrin. Four were as insecticidal as dichlorvos. The acetate of 1‐cyano‐1‐hydroxy‐2‐propene (CHP‐ace) was also tested in soil for antifungal and antibacterial activity, and inhibition of weed seed germination. CHP‐ace reduced the total soil bacterial and fungal counts significantly, and was effective in inhibiting the germination of weed seeds in soil, indicating a broad spectrum of activity as a soil fumigant. Copyright © 2004 Society of Chemical Industry
Exposure to sulfosulfuron in agricultural drainage ditches: field monitoring and scenario‐based modelling
Authors: Brown Colin D , Dubus Igor G , Fogg Paul , Spirlet Marie , Gustin Christophe
Published: April 2004

Field monitoring and scenario‐based modelling were used to assess exposure of small ditches in the UK to the herbicide sulfosulfuron following transport via field drains. A site in central England on a high pH, clay soil was treated with sulfosulfuron, and concentrations were monitored in the single drain outfall and in the receiving ditch 1 km downstream. Drainflow in the nine months following application totalled 283 mm. Pesticide lost in the first 12.5 mm of flow was 99% of the total loading to drains (0.5% of applied). Significant dilution was observed in the receiving ditch and quantifiable residues were only detected in one sample (0.06 µg litre−1). The MACRO model was evaluated against the field data with minimal calibration. The parameterisation over‐estimated the importance of macropore flow at the site. As a consequence, the maximum concentration in drainflow (2.3 µg litre−1) and the total loading to drains (0.76 g) were over‐estimated by factors of 2.4 and 5, respectively. MACRO was then used to simulate long‐term fate of the herbicide for each of 20 environmental scenarios. Resulting estimates for concentrations of sulfosulfuron in a receiving ditch were weighted according to the prevalence of each scenario to produce a probability distribution of daily exposure. Copyright © 2004 Society of Chemical Industry
Effects of insecticides and defoliants applied alone and in combination for control of overwintering boll weevil (Anthonomus grandis; Coleoptera: Curculionidae)—laboratory and field studies
Authors: Greenberg Shoil M , Sappington Thomas W , Elzen Gary W , Norman John W , Sparks Alton N
Published: April 2004

In laboratory, greenhouse and field tests, we determined the effects of combining full rates of the defoliants tribufos and thidiazuron and the herbicide thifensulfuron‐methyl with half rates of the insecticides lambda‐cyhalothrin or azinphos‐methyl, and the combination of tribufos and thidiazuron, both in half rates, on mortality of the boll weevil, Anthonomus grandis grandis Boheman and on the quality of defoliation. Tribufos, 0.47 kg ha−1 and tribufos, 0.235 kg ha−1 + thidiazuron, 0.125 kg ha−1 exhibited a slightly toxic effect to boll weevil, while tribufos, 0.47 kg ha−1 + lambda − cyhalothrin, 0.019 kg ha−1, tribufos, 0.47 kg ha−1 + azinphos − methyl, 0.14 kg ha−1, and tribufos, 0.235 kg ha−1 + thidiazuron, 0.125 kg ha−1 + azinphos − methyl, 0.14 kg ha−1, provided control of boll weevil as good as or better than full‐rate azinphos‐methyl or lambda‐cyhalothrin alone owing to synergistic effects. Thidiazuron or thifensulfuron‐methyl alone or in combination with insecticides did not affect boll weevil mortality. Treatment with tribufos + thidiazuron, both at half rate, significantly increased defoliation compared to full rates of tribufos or thidiazuron alone, and provided adequate defoliation for approximately the same cost per hectare. Copyright © 2004 Society of Chemical Industry
C60Cl24 molecule in crystalline toluene matrix
Authors: Smirnov V. P. , Razbirin B. S. , Starukhin A. N. , Chugreev A. V. , Grushko Yu. S. , Kolesnik S. , Konstantinov B. P.
Published: April 2004

The absorption spectra of the molecules C60Cl24 embedded in a solid matrix of toluene, C6H5(CH3), consist of three groups of lines, A, B, and C, situated at 1.6–1.8, 2.3–2.5, and 2.6–2.8 eV. We assign the groups of lines to purely electronic and electron‐vibrational (vibronic) transitions So → Sn in C60Cl24 molecules in different positions with respect to the crystalline matrix (Shpol'skii effect). The molecules C60Cl24 are known to have three isomers: a Th‐symmetric and two D2h‐symmetric (1 and 2). The D2h‐symmetric isomer 1 has the most appropriate value of the first electronic transition and is probably responsible for the observed absorption spectra. We report the results of calculations made to find the most appropriate cavities in a toluene crystal and the most advantageous positions of D2h‐symmetric isomers 1 of the C60Cl24 molecule in these cavities. The most appropriate three cavities in the toluene crystal for the D2h‐symmetric isomers 1 of the C60Cl24 molecule are found to be centered in the inversion center rc = 0.5 a (a, b, c being primitive translation vectors) and formed by moving away 14 somewhat different toluene molecules. The very fact that there exists a relatively small number of energetically preferred ways to embed the molecule C60Cl24 in the crystal matrix of toluene is encouraging and correlates with the small number of Shpol'skii lines in the spectra of pure electronic transitions in the system under consideration. Taking into account toluene molecule relaxation around the embedded molecule C60Cl24 will permit a closer comparison of the theoretical and experimental results. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Dried‐droplet probe preparation on AnchorChip™ targets for navigating the acquisition of matrix‐assisted laser desorption/ionization time‐of‐flight spectra by fluorescence of matrix/analyte crystals
Authors: Thomas Henrik , Havliš Jan , Peychl Jan , Shevchenko Andrej
Published: April 2004

We have developed a dried‐droplet probe preparation method for peptide mass fingerprinting by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS), which uses AnchorChip™ targets and α‐cyano‐4‐hydroxycinnamic acid (CHCA) as a matrix. Upon drying of a matrix and analyte mixture on the AnchorChip, salts and low molecular weight contaminants were pooled at the hydrophilic metal anchor, whereas 10–50 μm matrix/peptide crystals firmly adhered at the surface of a hydrophobic polymer and the entire target could be subsequently washed by submerging it in 5% formic acid for 2–3 min. Epifluorescence microscopy suggested that peptides were completely co‐localized with CHCA crystals at the AnchorChip surface. Fluorescent images of the probes were of good contrast and were background‐free, compared with images taken by a video camera built into the ion source. CHCA/peptide crystals were easy to recognize at the surface and peptide mass maps were acquired from them without further adjustment of the position of the laser beam. These crystals were remarkably stable towards the laser depletion and almost no matrix‐related ions were typically observed in the low m/z region of peptide mass maps. The sensitivity of the peptide mass mapping was at the low‐femtomole level. Copyright © 2004 John Wiley & Sons, Ltd.
A fragmentation study of a flavone triglycoside, kaempferol‐3‐O‐robinoside‐7‐O‐rhamnoside
Authors: March Raymond E. , Miao Xiu‐Sheng , Metcalfe Chris D.
Published: April 2004

A mass spectrometric method based on the combined use of electrospray ionization, collision‐induced dissociation and tandem mass spectrometry has been applied to the structural characterization of the flavone triglycoside, robinin (3,5,7,4′‐tetrahydroxyflavone‐3‐O‐robinoside‐7‐O‐rhamnoside). The deprotonated molecule fragments by loss of the rhamnose glycan residue to yield the Y7− ion (m/z 593) and by scission of the robinose glycan residue to yield the radical anion [Y3,0‐H]−. (m/z 430). The Y7− ion fragments by scission of the robinose glycan residue to yield the radical anion of Y7[Y3,0H]−. (m/z 284). The [Y3,0H]−. radical anion fragments by loss of the rhamnose glycan residue to yield the radical anion Y7[Y3,0H]−. (m/z 284) and by scission to yield [Y7H][Y3,0H]− (m/z 283). A fragmentation mechanism has been proposed. Copyright © 2004 John Wiley & Sons, Ltd.
Multivariate approaches for efficient detection of potential metabolites from liquid chromatography/mass spectrometry data
Authors: Idborg Helena , Edlund Per‐Olof , Jacobsson Sven P.
Published: April 2004

This work describes a novel method for rapid screening of unknown metabolites in urine samples that narrows down the list of potential metabolites. Prior to analysis by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI‐MS), urine samples were prepared using solid‐phase extraction (SPE). Automatic curve resolution was used for deconvolution of the LC/MS data, followed by peak alignment. Preprocessed data were then used for metabolite pattern recognition using principal component analysis (PCA), parallel factor analysis (PARAFAC), and multilinear partial least squares (N‐PLS). This approach enabled the rapid detection of metabolites of citalopram in urine by maximizing the information extracted. The metabolites thus identified were compared with earlier studies on the metabolism of citalopram. In addition, new, unreported metabolites were found and characterized by LC/MS/MS and accurate mass measurements. A combination of data from positive and negative ionization enhanced the identification of metabolites. Copyright © 2004 John Wiley & Sons, Ltd.
Essential edges in Poisson random hypergraphs
Authors: Goldschmidt Christina , Norris James
Published: April 2004

Consider a random hypergraph on a set of N vertices in which, for 1 ≤ k ≤ N, a Poisson (Nβk) number of hyperedges is scattered randomly over all subsets of size k. We collapse the hypergraph by running the following algorithm to exhaustion: Pick a vertex having a 1‐edge and remove it; collapse the hyperedges over that vertex onto their remaining vertices; repeat until there are no 1‐edges left. We call the vertices removed in this process identifiable. Also any hyperedge all of whose vertices are removed is called identifiable. We say that a hyperedge is essential if its removal prior to collapse would have reduced the number of identifiable vertices. The limiting proportions, as N → ∞, of identifiable vertices and hyperedges were obtained in R. W. R. Darling and J. R. Norris [Structure of large random hypergraphs, Ann Appl Probab, to appear. In this paper, we establish the limiting proportion of essential hyperedges. We also discuss, in the case of a random graph, the relation of essential edges to the 2‐core of the graph, the maximal subgraph with minimal vertex degree 2. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004
Assigning people to roles in software projects
Authors: Acuña Silvia T. , Juristo Natalia
Published: April 2004

This paper is based on the premise that people's behavioural competencies or characteristics of professional conduct influence the effectiveness and efficiency with which they perform a predetermined role in the software process. We propose a capabilities‐oriented process model that includes traditional elements of the software process (activities, products, techniques, people and roles) and the original element of this paper (capabilities). With the aim of adding behavioural competencies to the process model, we define the capability–person and capability–role relationships involved in software development. Additionally, we propose two procedures that are based on each of these relationships: a procedure that can be used to determine the capabilities of the members of a development team; and a procedure that can be used to assign people to perform roles depending on their capabilities and the capabilities demanded by the roles. Finally, the person–capabilities–role relationship has been empirically validated. The results yielded by this experiment confirm the hypothesis that assigning people to roles according to their capabilities and the capabilities demanded by the role improves software development. Copyright © 2004 John Wiley & Sons, Ltd.
Xenoestrogenic effects of ethinylestradiol in zebrafish (Danio rerio)
Authors: Versonnen Bram J. , Janssen Colin R.
Published: April 2004

To assess the estrogenic effects of ethinylestradiol on zebrafish, zebrafish at different developmental stages (embryos, juveniles, and adults) were exposed to the synthetic hormone ethinylestradiol (EE2) in concentrations of 1, 10, and 100 ng/L for up to 33 days. Survival, hatching, length, weight, growth, condition, hepatosomatic index, gonadosomatic index, and vitellogenin (VTG) production were examined. Exposure of zebrafish juveniles and embryos to 100 ng EE2/L for up to 33 days had significant effects on survival, growth, and hatching. Two VTG fragments with molecular weights of approximately 140 and 170 kDa were detected with protein electrophoresis and Western blotting in the blood of exposed males and exposed and unexposed females, as well as in whole‐body homogenates of exposed and unexposed juveniles. Significantly higher VTG concentrations (compared to controls) were measured in adults exposed to 10 and 100 ng EE2/L for 14 days, but not in fish exposed to 1 ng EE2/L. This study demonstrated that (1) zebrafish juveniles, larvae, and embryos are sensitive to the toxic effects of the endocrine disrupter EE2; (2) the effects on VTG production in adults are detected after exposure to environmentally relevant concentrations of EE2; (3) unexposed juvenile zebrafish produce measurable concentrations of VTG. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 198–206, 2004.
Survey of hormone activities in municipal biosolids and animal manures
Authors: Lorenzen Angela , Hendel John G. , Conn Kenneth L. , Bittman Shabtai , Kwabiah Allan B. , Lazarovitz George , Massé Daniel , McAllister Tim A. , Topp Edward
Published: April 2004

The potential exists for natural or synthetic hormonal chemicals present in agricultural fertilizers to be transferred to adjacent aquatic environments in order to alter endocrine function in exposed wildlife. Recombinant yeast and mammalian cell line (BG1Luc4E2) assays were used to screen crude organic extracts of municipal biosolids and animal manures for estrogen‐, androgen‐, and progesterone receptor gene transcription activities. Of the biosolid extracts, those samples that had undergone aerobic digestion had no or minimal estrogen‐ and no androgen receptor gene transcription activities. In contrast, those biosolid samples that had undergone anaerobic digestion had much higher estrogen‐ and, for all but one site, androgen receptor gene transcription activities. Extracts prepared from animal manure samples had variable levels of androgen‐ and estrogen receptor gene transcription activities, which may be related to the type, sex, age, and reproductive status of the animals. The diet and treatment of animals with hormone implants also appeared to be factors influencing hormone activity in animal manure. Progesterone receptor gene transcription activity was observed for only one chicken litter sample. Overall, results of this study suggest that in vitro bioassays can be used to survey and detect hormone activity in municipal biosolids and animal manures. Furthermore, results of these assays can be used to develop practices that will minimize the potential environmental endocrine‐disrupting effects of these substances. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 216–225, 2004.
Evaluation of microbiological and physicochemical indicators for wastewater treatment
Authors: Howard I. , Espigares E. , Lardelli P. , Martín J. L. , Espigares M.
Published: April 2004

The quality control of wastewater treatments was monitored using selected novel and classical physicochemical and microbiological indicators, and the associations of the treatments with the effluents was analyzed. The microbiological indicators monitored were heterotrophic plate count (HPC), total coliforms (TC), fecal coliforms (FC), fecal streptococci (FS), sulfite‐reducing clostridia (SRC), Pseudomonas aeruginosa, and Salmonella spp. The stages of wastewater treatment also were evaluated through determination of ammonia; biological oxygen demand (BOD5); chemical oxygen demand (COD); chloride; conductivity; suspended dissolved and total solids; fats; nitrate, nitrite, and total nitrogen; pH; phosphate and total phosphorus. Additional indicators included the Escherichia coli growth inhibition (IGEC) bioassay for assessing whole effluent toxicity, spectral determinations between wavelengths (λ) 190–650 nm, and total (TP) and soluble (SP) protein contents. Of the more common physicochemical parameters, only BOD5, COD, suspended and total solids, and fats showed a statistically significant reduction between raw water and effluent; for the microbiological indicators, significant reduction was seen only for HPC, FC, and Ps. aeruginosa. We suggest that determinations of Ps. aeruginosa be commonly used as an indicator of wastewater quality. Spectral analysis—most notably the values of absorbance at 225, 255, and 295 nm—revealed a statistically significant correlation with several physicochemical parameters. Statistical analysis of SP and TP values showed them to be good indicators of contamination. The quantitative study of Salmonella spp. and the results of the IGEC bioassay show the need for close control of infectious and toxic risks in wastewater and effluents. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 241–249, 2004.
Direct and interactive effects of ecologically relevant concentrations of organic wastewater contaminants on Rana pipiens tadpoles
Authors: Fraker Stephanie L. , Smith Geoffrey R.
Published: April 2004

Organic wastewater contaminants (OWCs) have recently been documented in several aquatic ecosystems. We examined the effects of three OWCs (caffeine, acetaminophen, and triclosan) on the activity level, startle response, survivorship, and growth of northern leopard frog (Rana pipiens) tadpoles. We conducted two experiments: one on the effects of acetaminophen and triclosan alone and in combination, and the other on the effects of caffeine and acetaminophen alone and in combination. In both experiments acetaminophen had no effect on activity, startle response, survivorship, or final mass. In experiment 1, tadpoles exposed to triclosan were less active than controls. Tadpoles exposed to the highest triclosan concentration had lower startle response and survivorship than in the other concentrations and in the control. Tadpoles exposed to the intermediate triclosan concentrations were heavier than in other treatments, but not in the control. In experiment 2, tadpoles exposed to the highest caffeine concentration were the most active. Acetaminophen increased the effect of caffeine on activity. More tadpoles exposed to caffeine exhibited a startle response than did control tadpoles. Survivorship was 100% for all caffeine treatments. There was a tendency (P = 0.06) for tadpoles exposed to higher concentrations of caffeine to be smaller. In general, the interactive effects were not important. Our results show that ecologically relevant levels of some OWCs can have both behavioral and physiological effects on R. pipiens tadpoles. Thus, amphibians may be affected by exposure to levels of OWCs that appear to be widespread in aquatic ecosystems. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 250–256, 2004.
Prediction of fetal anemia in rhesus disease by measurement of fetal middle cerebral artery peak systolic velocity
Authors: Scheier M. , Hernandez‐Andrade E. , Carmo A. , Dezerega V. , Nicolaides K. H.
Published: April 2004

Objective

In red blood cell (RBC) isoimmunized pregnancies fetal anemia is associated with a hyperdynamic circulation. The aim of the present study was to examine further the possible value of fetal middle cerebral artery peak systolic velocity (MCA‐PSV) in the management of affected pregnancies.

Methods

A reference range of fetal MCA‐PSV with gestation was constructed from the study of 813 normal singleton pregnancies at 20–40 weeks' gestation. Fetal MCA‐PSV was also measured in 58 fetuses from RBC isoimmunized pregnancies, with maternal hemolytic antibody concentration of >15 IU/mL at 19–38 weeks' gestation and within 10 days of measurement of fetal hemoglobin concentration in blood obtained either by cordocentesis (n = 43) or at delivery (n = 15). In the RBC isoimmunized pregnancies each of the measured MCA‐PSV and hemoglobin concentrations was expressed as a delta value (difference in SDs from the normal mean for gestation). Regression analysis was used to determine the significance of the association between delta MCA‐PSV and delta fetal hemoglobin concentration.

Results

In the normal pregnancies there was a significant increase in fetal MCA‐PSV with gestation (mean MCA‐PSV = 100.0223 × GA + 0.963). In RBC isoimmunized pregnancies the fetal MCA‐PSV was increased and there was a significant association between delta MCA‐PSV and delta hemoglobin concentration (delta hemoglobin = (delta MCA‐PSV + 0.093)/−0.356; R2 = 0.638, P < 0.0001). An MCA‐PSV of mean + 1.5 SDs detected 96% of severely anemic fetuses, with a hemoglobin deficit of at least 6 SDs, for a false‐positive rate of 14%.

Conclusion

Measurement of fetal MCA‐PSV is a useful method of assessing fetal anemia. In the clinical management of isoimmunized pregnancies a cut‐off in MCA‐PSV of mean + 1.5 SDs can identify nearly all severely anemic fetuses with a low false‐positive rate. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
PVC degradation during injection molding: Experimental evaluation
Authors: Garcia Jose L. , Koelling Kurt W. , Xu Guojun , Summers James W.
Published: April 2004

This paper focuses on experimental observations of poly(vinyl chloride) (PVC) degradation during injection molding. Degradation of poly(vinyl chloride) has been extensively studied. These studies have been performed in quiescent systems with very little or no strain applied to the sample. However, during processing, the polymer experiences very large deformations, in particular in the case of injection molding. This work demonstrates that the large shear during injection molding causes a significant increase of degradation as compared to studies in quiescent systems. It was also observed that degradation occurs in less than 1/10 the time required for quiescent systems. Finally, the flow geometry also affects the degradation behavior during processing. Understanding the parameters leading to degradation could lead to schemes to avoid it. J. Vinyl Addit. Technol. 10:17–40, 2004. © 2004 Society of Plastics Engineers.
Ninety‐four Appendectomies for Suspected Acute Appendicitis during Pregnancy
Authors: Ueberrueck Torsten , Koch Andreas , Meyer Lutz , Hinkel Michael , Gastinger Ingo
Published: April 2004

Acute appendicitis during pregnancy is a rare event, and large numbers of cases reported in the literature stem entirely from data stored in national registers. Between 1974 and 2000 relevant perioperative data on the treatment of appendicitis were collected consecutively and analyzed retrospectively. Surgical and obstetric data relating to the medical history, the clinical, intraoperative, and histologic findings, and the course of the pregnancy were recorded. Altogether, 9793 appendectomies were performed, 94 of which were in pregnant women (24.5% during the first trimester, 51% during the second trimester, and 24.5% during the third trimester). This represents 0.2% of the 46,960 deliveries during the period under observation. Fifty percent of the case histories during the second trimester were atypical. The overall perforation rate was 14.9%; it was 8.7%, 12.5%, and 26.1% during the three trimesters, respectively. Maternal mortality was 0%; the combined miscarriage/abortion rate was 8.5% (n = 8); and infant mortality was 3.2% (n = 3). The postoperative spontaneous abortion rate was 13.0% and the additional therapeutic/requested abortion rate 21.7% during the first trimester. In view of the elevated postoperative abortion rate and the facility of the clinical diagnosis during the first trimester, the indication for invasive diagnostic measures and surgery requires careful consideration. During the second and third trimesters the difficulty of establishing a clinical diagnosis makes it necessary to undertake exploratory surgery early.
Decortication for Chronic Parapneumonic Empyema: Results of a Prospective Study
Authors: Melloni Giulio , Carretta Angelo , Ciriaco Paola , Negri Giampiero , Voci Carlopietro , Augello Giuseppe , Zannini Piero
Published: April 2004

Despite advances in diagnostic methods, surgical techniques, and supportive therapy, chronic parapneumonic empyema is still associated with considerable morbidity and mortality. A prospective study was performed on a consecutive series of patients with chronic parapneumonic empyema to analyze the results of surgical treatment and identify clinical predictors of poor outcome. From 1993 to 2000 a total of 40 patients underwent decortication for chronic parapneumonic empyema. There was no mortality. All 40 patients had definitive resolution of the empyema. Altogether, 34 patients (87.5%) had an uneventful postoperative course, and 5 (12.5%) experienced complications (2 prolonged febrile syndromes, 3 cases of sepsis requiring mechanical respiratory assistance). All complications resolved well with adequate treatment without further consequences. Definitive results of the surgical procedures assessed at the 6‐month follow‐up examination were good in 21 patients and satisfactory in 19. No unsatisfactory results were observed in any of the patients. Univariate analysis showed that three variables predicted morbidity: co‐morbidities (p = 0.039), symptom duration ≥ 60 days (p = 0.009), and duration of preoperative conservative treatment ≥ 30 days (p = 0.006). Multivariate analysis showed that only symptom duration ≥ 60 days (p = 0.041) and duration of conservative treatment ≥ 30 days (p = 0.025) were associated with morbidity. Decortication is a highly effective treatment for chronic parapneumonic empyema and may be performed with low morbidity and mortality. Because prolonged duration of symptoms and conservative treatment increase morbidity, early surgical intervention seems to be the optimal modality for the treatment of chronic parapneumonic empyema.
Correlation between Radiologic and Pathologic Dimensions of Adrenal Masses
Authors: Fajardo Rafael , Montalvo Jorge , Velázquez David , Arch Jorge , Bezaury Paulina , Gamino Rosa , Herrera Miguel F.
Published: April 2004

The size of adrenal tumors has been shown to be a good predictor of malignancy. There is still some controversy about the concordance between radiologic and real pathologic measurements. The aim of this study is to determine the correlation between direct and corrected radiologic computed tomography scan dimensions and the measurements of the resected specimen. A total of 41 adrenal tumors were included. Direct and corrected measurements of the largest diameter were contrasted with the pathologic dimensions. The Linos formula was used for the corrected measurements. Proper statistics were used considering a two‐tailed significance level of 0.05. The intraclass correlations using direct and corrected measurements were 0.89 [95% confidence interval (95%CI) 0.81–0.94, p = 0.00001) and 0.90 (95%CI 0.82–0.95, p = 0.00001), respectively. The bivariate analysis using Pearson’s correlation between two‐dimensional group variables showed r = 0.82 (p < 0.0001) when direct and pathologic measurements were compared and r = 0.83 (p < 0.0001) when the corrected values were compared with the real dimensions. In this study, we demonstrate good correlation between radiologic and pathologic measurements of adrenal tumors. The Linos formula turned out to be significantly more accurate than direct radiologic measurements when means of the groups were compared, whereas when individual correlations were determined the two were similar. The Linos formula and radiologic measurements can be used to determine the proper management of adrenal incidentalomas in individual patients.
Biliopancreatic Diversion in the Surgical Treatment of Morbid Obesity
Authors: Van Hee Robrecht H.G.G.
Published: April 2004

Biliopancreatic diversion is a malabsorptive technique of bariatric surgery that has gained wide acceptance in the Western world. It is performed in one of two ways: In its classic form it consists of partial gastrectomy with a Roux‐en‐Y gastroenterostomy; in its duodenal switch form a vertical sleeve gastrectomy is combined with a duodenoenterostomy. Both techniques realize diversion of biliopancreatic juice, thereby creating a mild form of malabsorption. Weight loss has been approximately 70% of initial excess weight, exceeding that obtained with most other bariatric procedures. Iron, calcium, and vitamin deficiencies may occur, especially with classic biliopancreatic diversion, and must be prevented with adequate supplements during vigorous follow‐up. Weight loss is followed by a substantial reduction in the co‐morbidities that are present in many morbidly obese patients. Biliopancreatic diversion should be included in each obesity clinic program and be proposed for morbidly obese patients who are having difficulty with the prospect of continuous restraint of food intake or problems due to failed gastric restrictive interventions. The postoperative results in such patients have been good and have substantially improved quality of life and self‐esteem in this category of morbidly obese patients.