bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of liquid propylene with a fourth‐generation Ziegler–Natta catalyst: Influence of temperature, hydrogen, monomer concentration, and prepolymerization method on powder morphology
Authors: Pater Jochem T. M. , Weickert Günter , Swaaij Wim P. M. Van 
Published: December 2002

AbstractLiquid propylene was polymerized in a 5‐L autoclave batch reactor using a commercially available TiCl4/MgCl2/Al(ethyl)3/DCPDMS Ziegler–Natta catalyst, with a phthalate ester as internal electron donor. The powders from these polymerizations were characterized using laser diffraction particle size distribution (PSD) analysis, scanning electron microscopy (SEM), and bulk density measurements. These characteristics were analyzed as a function of the process conditions, including hydrogen and monomer concentration, polymerization temperature, and the prepolymerization method. It was shown that polymerization temperature influences the powder morphology to a large extent. At low temperatures, high‐density particles were obtained, showing regular shaped particle surfaces and low porosities. With increasing temperature, the morphology gradually was transferred into a more open structure, with irregular surfaces and poor replication of the shape of the catalyst particle. When using a prepolymerization step at a relatively low temperature, the morphology obtained was determined by this prepolymerization step and was independent from conditions in main polymerization. The morphology obtained was the same as that observed after a full polymerization at temperature. Even when using a short polymerization at an increasing temperature, the morphology was strongly influenced by the initial conditions. The effect of variation in hydrogen concentration supported the conclusion that the initial polymerization rate determines the powder morphology. In the absence of hydrogen, high bulk densities, and regularly shaped particles were obtained, even at high temperatures. With increasing hydrogen concentration, the reaction rates increased rapidly, and with that changed the morphology. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1421–1435, 2003
Relation of swelling and Tg depression to the apparent free volume of a particle‐filled, epoxy‐based adhesive
Authors: Chiang Martin Y. M. , Fernandez‐Garcia Marta 
Published: December 2002

AbstractThe effect of hygrothermal aging on a particle‐filled, epoxy‐based adhesive was studied using a gravimetric sorption technique. This study has explored moisture sorption characteristics as well as the associated behaviors of swelling and the depression of the glass transition temperature (Tg). We observed that the diffusion of water in this adhesive has a non‐Fickian behavior, and the depression of Tg proceeds to a definite value that is independent of the final equilibrium water content of the system. Our observations suggest that water diffuses into the polymer in a dual‐sorption mode, in which water resides in two populations. In one population, water is considered to occupy apparent free volume of the adhesive, and the second population water infiltrates polymer structure and forms hydrogen‐bonded clusters. Our results show that hygrothermal aging temperature and swelling do not alter the apparent free volume of this adhesive. We conclude that the constant value of Tg depression at saturation implies that only water in the apparent free volume is responsible for the Tg depression, whereas the swelling proceeds through the formation of hydrogen bonds in the adhesive. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1436–1444, 2003
Network crown ether resin with pendent sulfur ether group: Preparation, thermodegradation, and adsorption behavior
Authors: Meng Ling‐Zhi , Gong Shu‐Ling , Yin Yi‐Hua , Chen Yuan‐Yin , Wang You‐Wei 
Published: December 2002

AbstractNetwork crown ether resin with the pendent sulfur ether group was prepared by ring‐opening copolymerization of 3‐thiopentyl glycidyl ether and diethylene glycol bisglycidyl ether with Na, NaOCH2CH2OCH2CH2OH, or BuLi as catalyst, respectively. The yield of network polymer and the conversion of functional monoepoxy monomer are varied from catalyst to catalyst, and the thermostability of the resin is related to the content of the sulfur ether group. The resins show high adsorption capacity toward Cu(II), Pb(II), especially, Hg(II) ions, but poor adsorption capacity toward Mg(II) ions. Corresponding thermodynamic parameter of Hg(II) ion was deduced, and could be expressed approximately with the Freundlich equation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1445–1451, 2003
Sorption and desorption of tetrachloroethylene in fluoropolymers: Effects of the chemical structure and crystallinity
Authors: Hedenqvist M. S. , Ritums J. E. , Condé‐Brana M. , Bergman G. 
Published: December 2002

AbstractIn 18 fluoropolymers with different repeating‐unit structures and crystallinities, the solubility, diffusivity, and permeability at 70°C of a polarizable nonpolar solute (tetrachloroethylene) were studied. The transport properties were mostly controlled by the polarity of the polymer and to a lesser degree by the polymer crystallinity. The highest permeability was observed in the dipole‐containing ethylene–chlorotrifluoroethylenes because of their high tetrachloroethylene solubility. The lowest permeability was observed in the hydrogen‐bonding poly(vinylidene fluoride) polymers because of the combination of low solute solubility and solute diffusivity. The tetrachloroethylene diffusivity was solute‐concentration‐dependent, and sorption curves were S‐shaped, indicating that the solute surface concentration was time‐dependent. The rate at which the surface concentration approached the saturation level was proportional to the product of Young's modulus, the square of the thickness of the dry polymer, and the logarithm of the solute diffusivity. Data for the water‐hyperbranched polymer and limonene–polyethylene conformed to the same relationship. Therefore, this provides a new tool for predicting the solute‐surface‐concentration time dependence from data obtained by independent measurements. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1474–1483, 2003
FIR Volterra kernel neural models and PAC learning
Authors: Najarian Kayvan 
Published: December 2002

AbstractThe probably approximately correct (PAC) learning theory creates a framework to assess the learning properties of static models for which the data are assumed to be independently and identically distributed (i.i.d.). The present article first extends the idea of PAC learning to cover the learning of modeling tasks with m‐dependent sequences of data. The data are assumed to be marginally distributed according to a fixed arbitrary probability. The resulting framework is then applied to evaluate learning of Volterra Kernel FIR models. © 2002 Wiley Periodicals, Inc.
Measurement of the distribution of red blood cell deformability using an automated rheoscope
Authors: Dobbe J. G. G. , Streekstra G. J. , Hardeman M. R. , Ince C. , Grimbergen C. A. 
Published: December 2002

AbstractBackgroundRed blood cells (RBCs) have to deform markedly to pass through the smallest capillaries of the microcirculation. Techniques for measuring RBC deformability often result in an indication of the mean value. A deformability distribution would be more useful for studying diseases that are marked by subpopulations of less deformable cells because even small fractions of rigid cells can cause circulatory problems.MethodsWe present an automated rheoscope that uses advanced image analysis techniques to determine a RBC deformability distribution (RBC‐DD) by analyzing a large number of individual cells in shear flow. The sensitivity was measured from density‐separated fractions of one blood sample and from cells rendered less deformable by heat treatment. A preliminary experiment included the RBC‐DDs of a patient with sickle cell anemia, one on dialysis and being treated with erythropoietin, and one with elliptocytosis.ResultsMeasurement of the RBC‐DD was highly reproducible. The sensitivity test showed markedly different deformability distributions of density‐separated cells and yielded distinct RBC‐DDs after each additional minute of heat treatment.ConclusionThe automated rheoscope enabled the determination of RBC‐DDs from which less deformable subpopulations can be established. The shape of an RBC‐DD may be valuable in assessing cell fractions with normal and anomalous deformability within pathologic blood samples. Cytometry (Clin. Cytometry) 50:313–325, 2002. © 2002 Wiley‐Liss, Inc.
Assessment of tumor cell repopulation after chemotherapy for advanced ovarian cancer: Pilot study
Authors: Davis A. J. , Chapman W. , Hedley D. W. , Oza A. M. , Tannock I. F. 
Published: December 2002

AbstractBackgroundRepopulation of clonogenic tumor cells appears to increase during fractionated radiation treatment and is recognized as an important factor affecting local control. Given the longer intervals between cycles and longer total duration of treatment, the impact of repopulation is likely to be greater after chemotherapy.MethodsWe assessed tumor cell repopulation with the proliferative marker Ki‐67 in 21 patients with ovarian carcinoma who received initial chemotherapy. Paraffin slides were evaluated from the diagnostic biopsy and from tumor obtained at debulking surgery after chemotherapy. Immunohistochemistry using the MIB‐1 antibody was performed on the paired samples and analyzed with a digital imaging device linked to a color camera mounted on a transmitted‐light microscope. The ratio of Ki‐67 positive to all nuclei was used as a proliferative index and compared for pre‐ and postchemotherapy specimens.ResultsAll patients received platinum‐based chemotherapy and most showed a response to treatment. The median duration between last chemotherapy and debulking surgery was 33 days (range, 22–50 days). Four (19%) of 21 patients showed an increased proliferative index after chemotherapy, and the remainder showed a decrease (n = 12) or no significant change (n = 5).ConclusionsOur results did not suggest an increase in proliferation of tumor cells after this type of chemotherapy in the majority of patients with ovarian cancer. Cytometry Part A 51A:1–6, 2003. © 2002 Wiley‐Liss, Inc.
Phagocytosis of apoptotic cells by human macrophages: Analysis by multiparameter flow cytometry
Authors: Jersmann Hubertus P. A. , Ross Katherine A. , Vivers Sharon , Brown Simon B. , Haslett Christopher , Dransfield Ian 
Published: December 2002

AbstractBackgroundPhagocytic removal of apoptotic cells is an important regulatory event in development, tissue homoeostasis, and inflammation. There are several methodologic problems with most in vitro studies of the molecular mechanisms of apoptotic cell phagocytosis. First, cell loss occurs during rigorous washing of adherent macrophages required to ensure removal of noningested particles. Second, discrimination of adherent or internalised apoptotic cells is difficult. Third, microscopic quantification is time consuming and has the potential for significant interobserver error. Fourth, subsequent analysis of phagocyte populations is difficult.MethodsWe used a flow cytometric method that allows quantification of phagocytosis of fluorescently labelled apoptotic cells with the use of multiparameter flow cytometric analysis.ResultsPhagocytosis of apoptotic cells was validated by use of inhibitors (cytochalasins) or low temperature and counterstaining with cell surface markers for the phagocytic targets to exclude binding to the phagocytic surface. Populations of phagocytic macrophages were sorted, and the presence of internalized apoptotic material was validated by microscopy.ConclusionsThe technique we used in this study allows observer‐independent analysis of phagocytosis of apoptotic cells by macrophages. Importantly, phagocytic or nonphagocytic populations could be subjected to further characterization with the use of flow cytometry with additional fluorochrome reagents and can be re‐cultured to study underlying regulatory mechanisms. Cytometry Part A 51A:7–15, 2003. © 2002 Wiley‐Liss, Inc.
Evaluation of SDF‐1/CXCR4‐induced Ca2+ signaling by fluorometric imaging plate reader (FLIPR) and flow cytometry
Authors: Princen Katrien , Hatse Sigrid , Vermeire Kurt , De Clercq Erik , Schols Dominique 
Published: December 2002

AbstractBackgroundThe chemokine receptors CXCR4 and CCR5 are the main coreceptors for human immunodeficiency virus (HIV) 1 to enter its target cells. The antiviral activity of their natural ligands (stromal cell‐derived factor 1 [SDF‐1], regulated on activation normal T‐cell expressed and secreted, (RANTES) and macrophage inflammatory proteins 1α and 1β, MIP‐1α and MIP‐1β) and the finding that individuals deficient in CCR5 are relatively resistant to HIV infection led to the concept that chemokine receptor antagonists can play an important role in anti‐HIV therapy. AMD3100, the prototype compound of the bicyclams, is one of the most potent and selective CXCR4 antagonists described to date. The search for new chemokine receptor antagonists involves the evaluation of compounds for their ability to block the specific chemokine‐induced transient intracellular Ca2+ flux. We evaluated two cell‐based‐fluorescent methods with the use of the Fluorometric Imaging Plate Reader (FLIPR) system and a flow cytometric assay to measure the SDF‐1–induced intracellular Ca2+ mobilization via CXCR4. Both assay systems were compared for their sensitivity, advantages, and system‐dependent limitations.MethodsCXCR4+ lymphocytic and monocytic cell lines commonly used in laboratories studying acquired immunodeficiency syndrome and freshly isolated peripheral blood mononuclear cells (PBMCs) were loaded with the Ca2+ indicator Fluo‐3. After washing, the cells were preincubated with the CXCR4 antagonist AMD3100. Then the increase in intracellular Ca2+ concentration after stimulation with SDF‐1 was examined by the FLIPR and the flow cytometer, which monitored the change in green fluorescence intensity of Ca2+‐bound Fluo‐3. Surface CXCR4 expression was also determined flow cytometrically.ResultsIn all five CXCR4+ cell lines, SDF‐1 elicited a transient increase in intracellular Ca2+ concentration. For each cell line, the magnitude of response was related to the level of CXCR4 expression: the cells with the highest CXCR4 level showed the strongest Ca2+ response. AMD3100 effected a dose‐dependent inhibition of the SDF‐1–induced Ca2+ flux in all cell lines examined. The FLIPR was more sensitive than the flow cytometer in detecting minor Ca2+ responses. In freshly isolated PBMCs, the Ca2+ response was due solely to the stimulation of monocytes and granulocytes, whereas the lymphocyte population, although expressing CXCR4, did not respond at all. This phenomenon could be observed with the flow cytometer and not with the FLIPR.ConclusionsThe FLIPR system is a most adequate to monitor intracellular Ca2+ mobilization and to evaluate chemokine receptor antagonists. However, flow cytometry and its multiparameter analysis allow additional characterization of the cells involved in the chemokine receptor‐mediated signal transduction. Cytometry Part A 51A:35–45, 2003. © 2002 Wiley‐Liss, Inc.
Human B cells express a CD45 isoform that is similar to murine B220 and is downregulated with acquisition of the memory B‐cell marker CD27
Authors: Bleesing Jack J. H. , Fleisher Thomas A. 
Published: December 2002

AbstractBackgroundDifferences between human and murine B cells exist at all stages of B‐cell development, including the stage of memory B‐cell formation. B cells in mice are identified with the pan–B‐cell–specific CD45 isoform, B220. In initial studies in humans, it appeared that B220 expression did not include all B cells. This study was performed to expand on those preliminary findings.MethodsMultiparameter flow cytometric detection of B220 expression on B cells was combined with a variety of B‐cell markers.ResultsIn contrast to mice, B220 was not a pan–B‐cell marker in humans but was downregulated in the majority of B cells that acquired the human memory B‐cell marker, CD27, whereas a minor memory B‐cell subset remained B220+, suggesting differences in differentiation.ConclusionsThe B220 isoform in humans is developmentally regulated in humans, tied to the acquisition of a memory phenotype, and as such can be used as a differentiation‐specific CD45 isoform, akin to the use of CD45 isoforms to distinguish between naive and memory T‐cell subsets. Patients with immunodeficiency disorders, associated with defective memory B‐cell generation and absent or reduced CD27+ B cells, showed a corresponding lack of B220 downregulation consistent with altered differentiation of B‐cell subsets. Cytometry Part B (Clin. Cytometry) 51B:1–8, 2003. Published 2002 Wiley‐Liss, Inc.
Medical drugs from humus matter: Focus on mumie
Authors: Schepetkin Igor , Khlebnikov Andrei , Kwon Byoung Se 
Published: December 2002

AbstractIn this review, we focus on the medicinal drugs from humus matter such as peat, sapropel, and mumie. The most clinically available medicines, containing peat and sapropel extracts, are Torfot, Tolpa Peat Preparation (TPP), Peloidodistillate, Humisol, Peloidin, FiBS, and Eplir. Much attention in the review is concentrated on mumie composition, its pharmacological properties, and new pharmacological drugs with mumie (Shilagen, Abana, Cystone, Diabecon 400, EveCare, Geriforte, Lukol, Pilex, Rumalava, Tentex forte, Nefrotec, Adrenotone, Siotone, La‐Tone Gold, Andro‐Surge, Solanova Libidoplex). It was concluded that therapeutic properties of crude extracts from peat, sapropel, and mumie have similarity to the ones of fulvic and humic acids. They are antibacterial, antitoxic, antiradical, antiulcerogenic, antiarthritic, immunomodulatory, and antiinflammatory properties. Possible directions for better development of new drugs from humus matter are discussed. Drug Dev. Res. 57:140–159, 2002. © 2002 Wiley‐Liss, Inc.
Paleoindian geoarchaeology and paleoenvironments of the western Killpecker Dunes, Wyoming, U.S.A.
Authors: Mayer James H. 
Published: December 2002

AbstractThe Killpecker Dunes in southwestern Wyoming have long been known to contain evidence for Paleoindian occupation. This paper presents the results of geoarchaeological investigations in the western, dormant portion of the Killpecker Dunes. Five localities, including the Krmpotich Folsom and Finley Cody Complex sites, were examined in order to better understand the Paleoindian geochronology of the dune field, and to facilitate a late Quaternary paleoenvironmental reconstruction. Age control is provided by radiocarbon, optical, and artifact ages. Four late Quaternary eolian units, designated as strata 1–4, were recognized; strata 1 and 2 are relevant to the Paleoindian record. Aggradation of stratum 1 began by at least 14,690 cal yr (∼12,55014C yr B.P.), probably in the form of a sand sheet under cool, dry conditions. Redoximorphic features are ubiquitous in stratum 1, indicating a rise in the water table during the latest Pleistocene. A buried soil (Calcid) at the top of this unit indicates a period of stability between ca. 12,000 and 11,00014C yr B.P. and has the potential to yield Clovis (11,200–10,90014C yr B.P.) artifacts. Unconformably overlying stratum 1 is stratum 2, a latest Pleistocene to early Holocene sand containing Folsom (10,900–10,20014C yr B.P.) through Cody Complex (9000–850014C yr B.P.) occupations. A buried soil characterized by the accumulation of illuvial clay and sodium (Natrargid) occurs at the top of stratum 2 and probably formed in and around interdunal ponds. The association of Paleoindian material with the stratum 2 soil suggests the use of interdunal areas as natural traps for hunting extinct bison. The accumulation of soluble salts indicates increased rates of evaporation during the early Holocene, probably from an increase in summer insolation. Although conditions in the dune field during the early Holocene became increasingly dry, they were probably moister than at present. © 2003 Wiley Periodicals, Inc.
The Euro and mergers: What are the opportunities and risks?
Authors: Goldberg Stephen R. , Benet Bruce A. , Cannon David M. 
Published: December 2002

AbstractAmericans who want to play the M&A game on European soil should go in with their eyes wide open, warn the
authors. The differences between the U.S. and European environments are so great that even seasoned players can feel
the ground shifting unexpectedly beneath them. But to ignore the opportunities would be disastrous. ©
2003 Wiley Periodicals, Inc.
SPEs: What is their role in future mergers?
Authors: Munter Paul 
Published: December 2002

AbstractSpecial Purpose Entities (SPEs) have been a hot news item lately. Enron abused its SPEs to hide
debt, and now Congress and the FASB have zeroed in on the issue. How have they changed the rules? What
regulations are ahead? What is the FASB likely to do? © 2003 Wiley Periodicals,
Inc.
ICFF: A new method to incorporate implicit flexibility into an internal coordinate force field
Authors: Katritch Vsevolod , Totrov Maxim , Abagyan Ruben 
Published: December 2002

AbstractWe introduce a new method to accurately “project” a Cartesian force field onto an internal coordinate molecular model with fixed‐bond geometry. The algorithm automatically generates the Internal Coordinate Force Field (ICFF), which is a close approximation of the “source” Cartesian force field. The ICFF method reduces the number of free variables in a model by at least 10‐fold and facilitates the fast convergence of geometry optimizations, an advantage that is critical for many applications such as the docking of flexible ligands or conformational modeling of macromolecules. Although covalent geometry is fixed in an ICFF model, implicit flexibility is incorporated into the force field parameters in the following two ways. First, we formulate an empirical torsion energy term in ICFF as a sixfold Fourier series and develop a procedure to calculate the Fourier coefficients from the conformational energy profiles of the fully flexible Cartesian model. The ICFF torsion parameters thus represent not only torsion component of the source force field, but also bond bending, bond stretching, and “1‐4” van der Waals interactions. Second, we use a soft polynomial repulsion function for “1‐5” and “1‐6” interactions to mimic the flexibility of bonds, connecting these atoms. Also, we suggest a way to use a local part of the Cartesian force field to automatically generate fixed covalent geometries, compatible with the ICFF energy function. Here, we present an implementation of the ICFF algorithm, which employs the MMFF94s Cartesian force field as a “source.” Extensive benchmarking of ICFF with a representative set of organic molecules demonstrates that the implicit flexibility model accurately reproduces MMFF94s equilibrium conformational energy differences (RMSD ∼0.64 kcal) and, most importantly, detailed torsion energy profiles (RMSD ∼0.37 kcal). This accuracy is characteristic of the method, because all the ICFF parameters (except one scaling factor in the “1‐5,1‐6” repulsion term) are derived directly from the source Cartesian force field and do not depend on any particular molecular set. In contrast, the rigid geometry model with the MMFF94s energy function yields highly biased estimations in this test with the RMSD exceeding 1.2 kcal for the equilibrium energy comparisons and ∼3.4 kcal for the torsion energy profiles. © 2002 Wiley Periodicals, Inc. J Comput Chem 24: 254–265, 2003