bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron microscopy and plastic processing I. Effect of lubricants in formulation
Authors: Yu A. J. , Boulier P. , Sandhu A. 
Published: December 2004

AbstractScanning electron microscopy was used to follow the fusion process of rigid PVC formulations. The results suggest that fusion involves chain entanglement across the resin grain boundary brought about by shear and heat. Heat comes from the processing machine as well as from friction when the resin particle are made to rub against each other during processing. The mechanism of lubricants, therefore, is to control the frictional heat build‐up. The level of lubricants should be just enough to prevent thermal degradation from frictional heat build‐up but not so much as to retard the chain entanglement process. Since this heat balance encompasses the total system, including the machine, the formulation and the articles being shaped, an optimum formulation has to be evolved for each case with all the system variables taken into consideration.
Chlorinated poly(vinyl chloride) (CPVC) engineering thermoplastic now a viable alternative
Authors: Dalal Girish T. 
Published: December 2004

AbstractIn the economic environment of today, as well as in the foreseeable future, the consumer and industry alike have to use critical value judgement on any purchase or investment made. Basically this requires stringent evaluation of cost and performance value of the selection made. In the field of engineering thermoplastics, the new generation of CPVC compounds offer a very unique and previously unattainable alternative to the plastics processor and consumer. Plastics processors can now use their expertise to develop the capability to successfully use these advanced CPVC compounds and gain the benefit of their cost/‐performance values.This paper provides background on what CPVC is, what its rheological and thermal stability characteristics are, and describes its compounding, processing, and applications. It also describes the advances made over the past couple of years.
Co‐rotating twin screw compounding studies of PVC formulations
Authors: Karian Harutun G. 
Published: December 2004

AbstractA 50 mm twin screw extruder was used to study the melting profiles of various PVC formulations. Melt temperature and degree of flux are measured axially along various mixing paddle arrangements.The viscous work is correlated with the rheology of the PVC mass and effective shear rate of the intermeshing co‐rotating screws. The results of this investigation are used to develop a conceptual model of compounding PVC formulations.The radial mixing patterns in paddle segments down the barrel length are analyzed by introduction of trace quantities of pigment added to the dry blend. The resulting residence time distributions coupled with localized shear rate distributions give a numerical evaluation of shear strain required to flux PVC particles into a continuous fluid mass.By proper agitator design, compounding of PVC formulations can be accomplished with minimal thermal history.
Thermodynamics of PVC—plasticizer interaction: A review
Authors: Foss P. H. , Shaw M. T. 
Published: December 2004

AbstractIn this review we evaluate many of the experimental techniques for measurement of polymer solvent interaction thermodynamics, placing special emphasis on the interaction between plasticizers and semicrystalline materials. Methods are reviewed for measurement of heat and volume of mixing, Flory‐Higgins interaction parameter (chi), virial coefficients, and empirical compatibility measurements.
Solvent recycling of rigid poly(vinyl chloride) bottles
Authors: Kampouris E. M. , Diakoulaki D. C. , Papaspyrides C. D. 
Published: December 2004

AbstractA solvent recycling technique is studied for treatment of waste poly(vinyl chloride) (PVC) bottles. The process proposed basically comprises dissolution of the collected material, reprecipitation, through washing of the polymer obtained, and drying. On the other hand, solvent mixtures involved are separated by distillation for further reuse. Cyclohexanone/n‐hexane proved to be the most satisfactory solvent/non‐solvent system due to the high yields attained in polymer of small grain size while recovering most of the solvents employed. Excellent molecular weight and mechanical property retention characterizes the polymer grade recycled.
Effect of precipitated silica on plate‐out of poly(vinyl chloride) compounds
Authors: Maisel J. William 
Published: December 2004

AbstractPlate‐out is the undesired deposition of materials from a compound onto the surface of processing equipment. Plate‐out causes problems with quality control and down‐time. Changes in processing conditions can help alleviate plate‐out, but adjustments in the formulation are usually needed for significant improvements in plate‐out, the deposition. The addition of precipitated silica to a PVC formulation is a simple and effective method to reduce plate‐out. This study explores the relationship between plate‐out reduction and the physical properties of precipitated silica. Silica properties such as surface area, average particle size, and oil absorption can all be controlled by a patented process developed by the Chemicals Division of J. M. Huber Corporation. Plate‐out reduction is related to the properties of precipitated silica, the loading of the silica, the order of addition, and type of PVC formulation. The effect of precipitated silica on the physical properties of the PVC compound, such as, tensile strength, tear strength, elongation and stiffness, are explored. Finally, the effectiveness of plate‐out reduction by precipitated silica as compared to fumed silica will be discussed.
Coated ultrafine precipitated CaCO3 as impact modifier extender in low molecular weight PVC
Authors: Mathur K. , Rogers L. , Tapper M. 
Published: December 2004

AbstractWork reported earlier had shown that the addition of 0.07 micron stearate coated ultrafine precipitated CaCO3 (CUPCC) in medium to high molecular weight PVC resulted in a significant improvement in notched Izod impact strength. The improvement was much more dramatic when the filler loading exceeded 10 phr. The addition of CUPCC to low molecular weight PVC had practically no effect on the notched Izod impact strength at equivalent loadings. More recent studies have demonstrated that when CUPCC is added to an impact modified low molecular weight PVC, it dramatically enhances the efficiency of impact modifier. This was found to be consistent with threee general classes of commercially available impact modifiers used in this study. The ability to extend the impact modifier with CUPCC in low molecular weight PVC, which has gained a wide acceptance in injection molding operations, will result in significant cost savings. The effect of CUPCC addition on other key properties and cost benefits will also be presented.
Effect of acrylic processing aids on PVC die swell
Authors: Pfennig Jean‐Louis G. , Dunkelberger David L. 
Published: December 2004

AbstractThe die swell behavior of PVC melts is a manifestation of melt elasticity and is of considerable commercial as well as fundamental importance. This behavior is a critical issue in extrusion blow molding application where die swell (i.e. parison thickness) needs to be controlled. Advantageously, the addition of high molecular weight acrylic processing aids to PVC provides better die swell control, thus, improving dramatically the processability of PVC. Hence, knowledge of molecular weight variables of such acrylic processing aids is important from both the commercial and rheological point of view. Various acrylic processing aids were prepared by polymerization designed to provide systematic variation of molecular parameters. Molecular weight distribution of the polymers was characterized by GPC, and their die swell behavior in a typical PVC blow molding formulation was determined at 200°C over various range of residence times using different L/D capillary dies. The results are presented showing effects of specific molecular variables.
Meaningful evaluation of plastisol gelation and fusion temperatures by dynamic mechanical analysis
Authors: Daniels Paul H. , Brofman Carl M. , Harvey Gary D. 
Published: December 2004

AbstractIn most PVC plastisol processing operations, gelation and fusion characteristics of the plastisol are critically important. For example, in chemically foamed plastisols, plastisol fusion temperature and blowing agent decomposition temperature must be carefully coordinated. In rotomolded parts, rates of gelation may determine the quality of the finished parts. For plastisol products made by any process, the final fusion temperature determines the processing temperatures required to give the finished product acceptable mechanical properties. For a variety of reasons, the methods commonly used to characterize plastisol gelation and fusion (hot bar test, resin in plasticizer clear point, torque rheometer measurements, etc.) provide comparisons between plastisols but do not provide temperatures that are easily related to actual industrial processes. With dynamic mechanical analysis (DMA), one can characterize, under low shear conditions, the temperatures at which gelation begins, gelation ends, and complete fusion occurs. Additionally, it is possible to record plastisol viscosities (and other dynamic mechanical properties) over the processing temperature range. We used a multiple linear regression program to analyze the DMA data for plastisols heated from 30 to 210°C and containing either 70, 80 or 90 phr of Jayflex dihexyl phthalate (DHP) or Jaylflex di‐isodecyl phthalate (DIDP). Further, we determined the plasticizer phr dependence and the reproducibility of gel and fusion temperatures given by data analyzed in this manner. Finally, for comparison, we analyzed the reproducibility of initial and final plastisol gel temperatures and fusion temperatures, which were determined by visually analyzing the DMA data for plastisols containing 70, 80, and 90 phr of Jyflex plasticizers DHP, Jayflex 77, diisononyl phthalate (DINP), and DIDP. Precise characterization of plastisol gelation and fusion behavior will, undoubtedly, facilitate substitution of plastisol ingredients as is often required by those who manufacture and process plastisols.
High heat applications for SMA modified PVC: Cost effective engineering performance
Authors: Bryner James G. 
Published: December 2004

AbstractSMA polymer modifiers for PVC, of the ELIX 300 type, increase the practical heat resistance of rigid PVC blends to > 100 C, allowing cost effective competition with high heat fire retardant engineering resins. The PVC/SMA blend technology, physical property characteristics, and fire retardant properties are presented. A definition of practical heat resistance and the correlation of practical heat resistance to Vicat heat resistance measurements are given with comparisons to competitive high heat fire retardant plastics. Current commercial application experience in rigid injection molding and profile extrusion is described which has confirmed the cost/performance advantage of PVC/SMA blends. Potential market opportunities for PVC/SMA blends will be presented for discussion.
Melt filtration of recycled PVC
Authors: Boo H. Khim , Mikofalvy Bela K. , Summers James W. , Sell W. Alan , Mittendorf Don H. 
Published: December 2004

AbstractThe separation of PVC from contaminants is one of the most important steps in recycling PVC. Earlier works have shown that one can separate PVC from other polymers by using the X‐ray fluorescence technique. However, in many cases, even after careful separation, there is a remaining impurity level of about 0.1% due to the limitations of the separation processes. In many applications, impurities, particularly nonmeltables, cause defects in the PVC matrix and must be removed for best performance and appearance. Melt filtration appears to be the best technique to remove the nonmeltable impurities.
FINITE DIFFERENCE MODELING OF THE ULTRASONIC FIELD RADIATED BY CIRCULAR TRANSDUCERS
Authors: ALIA AHLEM , DJELOUAH HAKIM , BOUAOUA NOUREDDINE 
Published: December 2004

In this paper, FD formulations in cylindrical coordinates are used to model the field radiated, by a circular source, in fluid and solid media.The stability of the used schemes is controlled by a proper choice of time and space steps. Absorbing boundary conditions are introduced to satisfy the assumption of a propagation in a half space medium. In order to minimize the CPU time, calculations are limited for regions disturbed by the propagating ultrasonic pulse then the calculus zone is incremented.Some numerical results are presented to illustrate the effect of the medium nature, source vibration profiles and eventually the presence of targets in the acoustic field. A spatio-temporal description of the diffraction phenomena is given. The radiated field is interpreted in terms of plane and edge waves. For solid media, this interpretation allows the determination of the arrival times which are compared with those numerically predicted. Numerical results corresponding to fluid media are compared to those obtained by the Impulse Response Method. The good agreement obtained justifies the choice of the FDM for the modeling of the wave propagation problems.
The Zonal Asymmetry of the Southern Hemisphere Winter Storm Track
Authors: Inatsu Masaru , Hoskins Brian J. 
Published: December 2004

Abstract
Atmospheric general circulation model experiments have been performed to investigate how the significant zonal asymmetry in the Southern Hemisphere (SH) winter storm track is forced by sea surface temperature (SST) and orography. An experiment with zonally symmetric tropical SSTs expands the SH upper-tropospheric storm track poleward and eastward and destroys its spiral structure. Diagnosis suggests that these aspects of the observed storm track result from Rossby wave propagation from a wave source in the Indian Ocean region associated with the monsoon there. The lower-tropospheric storm track is not sensitive to this forcing. However, an experiment with zonally symmetric midlatitude SSTs exhibits a marked reduction in the magnitude of the maximum intensity of the lower-tropospheric storm track associated with reduced SST gradients in the western Indian Ocean. Experiments without the elevation of the South African Plateau or the Andes show reductions in the intensity of the major storm track downstream of them due to reduced cyclogenesis associated with the topography. These results suggest that the zonal asymmetry of the SH winter storm track is mainly established by stationary waves excited by zonal asymmetry in tropical SST in the upper troposphere and by local SST gradients in the lower troposphere, and that it is modified through cyclogenesis associated with the topography of South Africa and South America.
Simulation of Late-Twenty-First-Century Changes in Wintertime Atmospheric Circulation over Europe Due to Anthropogenic Causes
Authors: Terray Laurent , Demory Marie-Estelle , Déqué Michel , de Coetlogon Gaelle , Maisonnave Eric 
Published: December 2004

Abstract
Evidence is presented, based on an ensemble of climate change scenarios performed with a global general circulation model of the atmosphere with high horizontal resolution over Europe, to suggest that the end-of-century anthropogenic climate change over the North Atlantic–European region strongly projects onto the positive phase of the North Atlantic Oscillation during wintertime. It is reflected in a doubling of the residence frequency of the climate system in the associated circulation regime, in agreement with the nonlinear climate perspective. The strong increase in the amplitude of the response, compared to coarse-resolution coupled model studies, suggests that improved model representation of regional climate is needed to achieve more reliable projections of anthropogenic climate change on European climate.
Detection of Liver Metastases From Endocrine Tumors: A Prospective Comparison of Somatostatin Receptor Scintigraphy, Computed Tomography, and Magnetic Resonance Imaging
Authors: Dromain Clarisse , de Baere Thierry , Lumbroso Jean , Caillet Hubert , Laplanche Agnès , Boige Valerie , Ducreux Michel , Duvillard Pierre , Elias Dominique , Schlumberger Martin , Sigal Robert , Baudin Eric 
Published: December 2004

Purpose To compare the respective sensitivity of somatostatin receptor scintigraphy (SRS), computed tomography (CT), and magnetic resonance imaging (MRI) in the detection of liver metastases from well-differentiated gastroenteropancreatic endocrine tumor (WDGEP ET) patients. To define predictive factors for “high-sensitivity SRS.” Patients and Methods Sixty-four patients with WDGEP ET underwent SRS with abdominal single-photon emission computed tomography (SPECT), spiral CT, and 1.5-T MRI within a 15-day interval, the order of which was randomized. Two readers analyzed images of each modality, blindly and independently. Results Hepatic metastases were present in 40 of the 64 patients and confirmed by pathology after liver biopsy or surgery in 32 and eight patients, respectively. SRS, CT, and MRI detected a total of 204, 325, and 394 metastases, respectively. The number of detected metastases was significantly higher with MRI than with CT (P = .02) and SRS (P < 10−4) and higher with CT than with SRS (P < 10−4). SRS was negative in seven patients with a positive CT and/or MRI. More lesions were detected in 10 patients by SPECT compared with static views. The median metastasis size was significantly correlated (P = .04) with the sensitivity of SRS. Conclusion MRI seems to have an edge over CT and SRS for the detection of liver metastases from endocrine tumors. We recommend the systematic performance of liver MRI at WDGEP ET initial staging and before major therapeutic events. The low performance of SRS was mainly explained by the impact of the metastasis size on the detection capacity of SRS.
Practitioners As Experts: The Influence of Practicing Oncologists “in-the-Field” on Evidence-Based Guideline Development
Authors: Browman George P. , Makarski Julie , Robinson Paula , Brouwers Melissa 
Published: December 2004

Purpose Panels of experts are used to develop clinical practice guidelines (CPGs) intended to be used by practitioners “in-the-field.” Therefore, oncologists’ participation in CPG development is an important strategy to promote CPG adoption. The purpose of this study was to evaluate the contributions of oncologists in-the-field to evidence-based CPG development using data from Ontario’s cancer system. Methods CPG development in Ontario includes surveys of oncologists’ opinions, using a structured questionnaire, about draft recommendations that were developed from rigorous systematic reviews of evidence prepared by expert panels. Two research assistants reviewed background documents to trace the changes in CPG recommendations from draft to final stage to determine the contribution of oncologists’ input to final recommendations. Changes to recommendations were categorized as either substantive (content or tone) or minor (ideas clarification or edits). Results From 2000 to 2003, 43 CPGs were developed. There were 87 changes to draft recommendations for 31 CPGs, of which 40 changes to 19 CPGs could be attributed to survey input from practicing oncologists. Of the 40 changes, 28 (70%) were judged to be substantive. Conclusion Despite a rigorous evidence-based process for CPG development, practicing oncologists contribute substantially to the final recommendations approved by the expert panel. It is hypothesized that the responsiveness of expert panels to input from oncologists in-the-field will facilitate adoption of CPGs.
Entwicklung und Toxinbildung von Aspergillus flavus im Festbettreaktor/Füllkörperreaktor
Authors: Kopp B. , Ehm H.‐J. 
Published: December 2004

AbstractThe behaviour of the mycelium forming mold Aspergillus flavus in packed column culture in comparison to conventional fermentation systems (surface culture and submerged culture) was investigated. The formation of aflatoxin was observed as a marker for the metabolic activity. The results demonstrated that the packed column system is situated with regard to the conditions of cultivation of mycelia forming molds between the surface culture and the submerged culture.
Immobilisierung mikrobieller Zellen und deren Nutzung zur Substratwandlung — Eine Literaturstudie
Authors: Berger R. 
Published: December 2004

AbstractA review is given of most of the literature concerning the immobilization of whole microbial cells and their testing for application in product synthesis. The review includes a discussion of adventages and disadventages of immobilized cells, methods of immobilization, pretreatments, aftertreatments, operation, recent developments, and other problems together with a table of the immobilized microbes and the tested reactions of product synthesis, with 350 references.
Einfluß extracellulärer Konzentrationen auf die spezifische Wachstumsrate von Mikroorganismen
Authors: Schneider J. D. 
Published: December 2004

AbstractThe influence of extracellular concentrations of hydrogen ion and C‐substrates on the specific growth rate of different microorganisms is investigated.A general relationship in the form

can be used to describe the inhibition effect of HPlus;‐ or substrate concentration (ci) on the growth rate. Different examples are demonstrated and the adequate specific constants K1 and K2 calculated.
Verfahrenstechnische Grundlagen der Reaktorgestaltung
Authors: Zlokarnik M. 
Published: December 2004

AbstractStarting with the definition of the process term kLa, steady state and nonsteady state measuring methods are described for its determination. Then the sorption characteristics for mixing vessels and for bubble columns are presented with respect to the coalescence behaviour of the system treated. They permit the scale‐up of these devices and the optimization of their process parameters for a required oxygen uptake. In addition to the sorption characteristics for the given system the knowledge of the flooding point and the power characteristics is necessary for the lay‐out of mixing vessels, whereas in the case of bubble columns the gas hold‐up characteristic needs to be known.
Methylglyoxal — ein toxisches Fermentationsprodukt
Authors: Hofmann K. H. , Babel W. 
Published: December 2004

AbstractMethylglyoxal (CH3COCHO) is a toxic intermediate of the carbon metabolism. Its accumulation in the growth medium of microorganisms may be an important danger for many fermentation processes. In this paper data will be presented which show the physiological effect of this compound on the living cell, the enzymes responsible for the synthesis and the turnover of methylglyoxal including the environmental conditions necessary for the accumulation of lethal concentrations in the medium.
Use of biorhythmic processes for increasing the efficiency of carbon‐compound conversion by microorganisms
Authors: Heinritz B. , Rogge G. , Stichel E. , Bley Th. 
Published: December 2004

AbstractFermentation kinetic, thermokinetic and morphological investigations of biological carbonsource conversions into microbial biomass and other reaction products can be used for improving the efficiency of biotechnical processes. In this way biorhythmic processes on a macrosocopic scale could be found in transitional stages of microorganism cultivation. These biorhythmic processes can be explained by the occurence of different cell states in the cell cycle. In order to characterize these cell states synchronized microorganism growth was investigated with the aid of the phased culture method. Two states could be observed in the case of yeast growth: the single cell state and the budding cell state. The duration and efficiency of the single cell state is dependent on the growth limitation and the carbon substrate feeding.Thus the reduction of carbon substrate feeding in states of synchronized populations which are characterized by a high percentage of single cells and by energy metabolite production which, in turn, is influenced by carbon substrate concentration can cause increased material and energetic efficiencies of biological carbon‐source conversions.