bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gibt es eine Universalkerbkontur nach dem Vorbild der Natur?
Authors: Mattheck C. , Bethge K. , Tesari I. , Scherrer M. , Kraft O. 
Published: August 2004

AbstractKerbspannungen sind Biegespannungen, die sich als Folge der Deformation der Kerbkontur den Nennspannungen überlagern (Abb. 1 u. 2). Diese duale Natur der Gesamtspannung macht es möglich Kerben so auszuformen, dass die überlagerten Biegespannungen so ansteigen wie die Nennspannungen abfallen. Damit ist die Gesamtspannung entlang der Kontur konstant, keine Spannungskonzentration, keine Sollbruchstellen, lange Lebensdauer ohne Ermüdungsbruch! Was bisher durch Computersimulation des lastgesteuerten Wachstums der Bäume mittels der CAO‐Methode (Computer Aided Optimization) [1,2] nur auf Finite‐Elemente‐Basis möglich war, geht jetzt mit Taschenrechner, ja sogar mit einem Handy das Tabellenkalkulation kann!Wem auch das zuviel Aufwand ist, der nehme einen Zirkel und ein 45°‐Zeichendreieck.Die optimierten Kurven ähneln sich für viele Fälle verblüffend, fast könnte man meinen, es gäbe für bestimmte Bedingungen eine Universalkerbkontur. Schwingversuche mit drastisch höheren Versagenslastspielzahlen lassen uns hoffen!
Neuronal differentiation‐induced change in expression of neurotrophic factor genes in adrenal chromaffin cell line tsAM5D expressing temperature‐sensitive SV40 T‐antigen
Authors: Murata Tomiyasu , Tsuboi Masaru , Hikita Kiyomi , Kaneda Norio 
Published: August 2004

AbstractWe recently established adrenal medullary cell line tsAM5D, immortalized with a temperature‐sensitive mutant of the oncogene simian virus 40 large T‐antigen. When cultured with basic fibroblast growth factor (bFGF) and ciliary neurotrophic factor (CNTF), tsAM5D cells proliferated at the permissive temperature (33°C) for the expression of the oncogene and differentiated into neuron‐like cells at the nonpermissive temperature (39°C). In the present study, we investigated the gene expression of several neurotrophic factors associated with the neuronal differentiation induced by the temperature shift. Using real‐time RT‐PCR analysis on bFGF and CNTF‐treated cells, we found up‐regulated expression of mRNAs for bFGF, leukemia inhibitory factor, transforming growth factor (TGF)‐β2, persephin, acidic fibroblast growth factor, neurotrophin‐3, preproenkephalin, and TGF‐β1 and down‐regulated expression of the mRNAs for interleukin‐6, neurturin, and CNTF. No apparent differences were observed in the mRNA level of insulin‐like growth factor‐2, TGF‐β3, and neurotrophin‐4/5. These results suggest that the regulated expression of neurotrophic factor genes play an important role in the neuronal differentiation of tsAM5D cells.
Calexcitin‐like immunoreactivity in the pond snail Lymnaea stagnalis
Authors: Hatakeyama Dai , Inamura Satoko , Ito Etsuro , Sakakibara Manabu , Nelson Thomas J. , Alkon Daniel L. 
Published: August 2004

AbstractCalexcitin (CE) is a low molecular weight Ca2+‐ and guanosine triphosphate‐ binding protein, which is phosphorylated during associative learning in both vertebrates and invertebrates. The purpose of this study was to determine the presence of CE in the central nervous system (CNS) of the pond snail Lymnaea stagnalis, which can acquire classical and operant conditioning. Immunoblotting of CE showed that the anti‐CE antibody prepared from squid can detect Lymnaea CE. In the cerebral ganglia, CE‐like immunoreactivity was exhibited in two pairs of cell clusters that receive taste signals from the superior or median lip nerves. In both pedal ganglia, CE‐like immunoreactivity was detected in 1‐4 cell of the PeA clusters, which are involved in the withdrawal response. Our results therefore showed that CE is involved in the feeding and withdrawal neural networks, suggesting that CE may function in associative learning of feeding and withdrawal behavior in L. stagnalis.
Attenuated noradrenaline release in the paraventricular nucleus are induced by electrical and angiotensin II activation of the subfornical organ in estrogen‐treated rats
Authors: Tanaka Junichi , Miyakubo Hiroko , Fujisawa Shigeko , Nomura Masahiko 
Published: August 2004

AbstractPrevious studies have demonstrated that estrogen alters the responsiveness of subfornical organ (SFO) neurons projecting to the hypothalamic paraventricular nucleus (PVN) to angiotensin II (ANG II) and activation of the SFO facilitates noradrenaline (NA) release in the PVN area. The present study was carried out to investigate whether estrogen elicits alterations in the NA release in the PVN area induced by electrical and chemical activation of the SFO. Intracerebral microdialysis techniques were utilized to quantify the extracellular content of NA in the region of the PVN in ovariectomized (OVX) female rats that were treated with either propylene glycol (PG) vehicle or estradiol benzoate (EB). In both groups, electrical stimulation (5–20 Hz, 600 μA) of the SFO significantly increased the NA concentration in the PVN area. Injections of ANG II (10–8 M, 0.2 μl) into the stimulation site significantly enhanced the release of NA in the PVN area. The NA release to either electrical or chemical stimulation of the SFO was much greater in the PG‐treated than in the EB‐treated rats. These results suggest that estrogen may decrease the NA release in the PVN area caused by ANG II acting at the SFO.
Risk of venous thromboembolism in pediatric patients with brain tumors
Authors: Tabori Uri , Beni‐Adani Liana , Dvir Rina , Burstein Yoav , Feldman Zeev , Pessach Itai , Rechavi Gideon , Constantini Shlomi , Toren Amos 
Published: August 2004

AbstractBackgroundVenous thromboembolism (VTE) is a common event in adults with malignant brain tumors approaching 24% throughout the course of the disease. The high morbidity and mortality of this complication yielded several protocols for prevention of the disease in adults undergoing neurosurgery for brain tumors and possible primary prevention afterwards. We investigated the incidence and complications of VTE in pediatric neuro‐oncology patients.ProcedureWe analyzed, retrospectively, the files of all consecutive patients under the age of 18 years who were hospitalized for the treatment of brain tumors between the years 1990 and 2003 in two leading, closely related, Israeli neuro‐oncology centers.ResultsA total of 462 children were analyzed. Three hundred eighty‐four patients underwent surgery and 78 were treated medically. Only three (0.64%) of the patients developed clinical episodes of VTE that were treated conservatively. Two of these patients developed intracranial bleeding while on secondary prevention for the disease.ConclusionsAlthough this study has considerable limitations in terms of retrospective design, heterogeneous group of patients and diagnoses, the changing awareness for thrombosis over the last 14 years and the inclusion of symptomatic VTE events only, our surprising data suggest that, as opposed to adults, the risk of clinically significant VTE in children with brain tumors may be exceedingly low. These findings set the stage for future forthcoming evaluations in view of the prospective studies that were done in adults and the possible significant implications for the prevention and possible etiologies of the disease. © 2004 Wiley‐Liss, Inc.
Nonadherence as a predictor of antidiabetic drug therapy intensification (augmentation)
Authors: Kogut Stephen J. , Andrade Susan E. , Willey Cynthia , Larrat E. Paul 
Published: August 2004

AbstractPurposeTo determine if nonadherence with antidiabetic drug therapy is predictive of subsequent antidiabetic drug therapy intensification.MethodsWe conducted a retrospective cohort study examining retail pharmacy dispensings of sulfonylureas or metformin to 1067 patients having diabetes. Patients that did not receive a sufficient quantity of medication to cover at least 80% of days during the evaluation period were classified as nonadherent. Outcomes identified were increase in the dose of antidiabetic medication utilized, the addition of a second antidiabetic agent to the regimen or either.ResultsAmong users of sulfonylurea monotherapy, those classified as nonadherent were 45% more likely to intensify therapy in subsequent months as compared with those classified as adherent (age‐adjusted odds ratio (OR) 1.45; 95% confidence interval (CI) 1.06–2.00). This finding was largely driven by observed increases in dosage, which were more likely among patients classified as nonadherent (age‐adjusted OR 1.48, 95%CI 1.07–2.05). Nonadherence was not found to be predictive of the subsequent addition of a second antidiabetic agent (OR 1.02; 95%CI 0.64–1.63). Overall findings were similar for the smaller sample of patients receiving metformin monotherapy, though observed differences did not achieve statistical significance.ConclusionsPatients who were poorly adherent to oral antidiabetic drug therapy more frequently experienced an increase in the dose of medication prescribed, as compared to patients that were classified as adherent. This finding underscores the need for prescribers to consider nonadherence as a root cause when patients fail to achieve therapeutic goals. Copyright © 2004 John Wiley & Sons, Ltd.
Indentation of poly(formaldehyde), reinforced nylons and poly(ethyl terephthalate)
Authors: Benabdallah H. S. , Bui V. T. 
Published: August 2004

AbstractIndentation tests were performed on flat coupons of poly(formaldehyde), three types of reinforced nylon and reinforced poly(ethyl terephthalate) using a device developed for a typical universal tensile testing machine. Spherical, conical and cylindrical indenters were selected for this study and the effects of indenter shape combined with the rate of indentation on the behavior of these materials were examined. The load‐depth relationship during the indentation process revealed the emergence of step‐like transitions at high indentation rates. The effects of the assessed parameters on the indentation resistance, as defined in this study, were analyzed. Interest was also focused on the investigation of the deformation work as well as the plastic work taking place for a total depth that incorporated both the skin and part of the bulk of the material. The modeling of the data was based on a previously developed approach and the introduction of a modified parameter that took not only the geometrical characteristics of the indenter into account but also the indentation depth. The proposed method has proven to be useful since a steady state of the indentation pressure was observed for all materials after a certain depth of indentation. This was valid for the results obtained using both conical and cylindrical indenters. Polym. Eng. Sci. 44:1439–1447, 2004. © 2004 Society of Plastics Engineers.
Mechanical and erosion properties of CaCO3‐EMAA thermal sprayed coatings
Authors: Yan F. Y. , Gross K. A. , Simon G. P. , Berndt C. C. 
Published: August 2004

AbstractPolymer‐ceramic composite coatings manufactured from calcium carbonate and ethylene‐methacrylic acid copolymer (EMAA) were prepared via a thermal spray process employing different CaCO3 filler sizes (average size of 2.8, 9 or 36 μm) and loading levels from about 2.5 to 7 wt%. The optimum filler feeding characteristics, deposition efficiency and deposition rate were obtained with a 36 μm sized CaCO3. Tensile properties, peel strength, and the erosion resistance of a pure EMAA and CaCO3‐EMAA composite coatings were investigated. It was found that the tensile strain at fracture of the composite coating decreased with the addition of filler to a greater degree than that observed in compression‐molded polymer composites. This is attributed to an inhomogenous distribution of the filler, with more being concentrated at the boundaries of the deposited polymer particles, thereby establishing a rigid framework within the coating. Only a small filler content is necessary to establish large changes in the mechanical properties of the coating. The peel strength of a composite coating decreases with filler content, both on a mild steel substrate and a previously sprayed polymer coating. Bonding to the latter is significantly higher and offers a possibility as a bonding layer between substrates and composite coatings. The coefficient of friction is lowered with the addition of a filler. Erosion testing has shown that the erosion resistance of PF111 is little improved overall with filler addition, although some increase is found for filler contents less than 5 vol%. Polym. Eng. Sci. 44:1448–1459, 2004. © 2004 Society of Plastics Engineers.
An axisymmetric model for thread forming in polycarbonate and polypropylene screw and boss fasteners
Authors: Ellwood Kevin R. J. , Fesko Don , Bauer David R. 
Published: August 2004

AbstractPlastic boss and screw fasteners are an economical means of securing automotive components, such as instrument or body panels. However, new materials and/or suboptimal design present challenges to the boss/screw effectiveness. Failure of a boss/screw can result is loss of functional performance or increased squeak and rattle. Failure is often controlled by what occurs during the initial thread‐forming process. Thus, the goal of this paper is to develop an FEA model to elucidate the thread‐forming process so that we can facilitate subsequent design and/or process optimization, and understand potential failure modes. The FEA must accommodate nonlinear couplings, such as large strain and heat transfer. Heat generation is present in the forms of interfacial shear heating and plastic work associated with the large deformation of the interface between the boss and screw. Strain rate‐dependent materials are included using the Eyring theory for plastic flow of polymeric materials. Results of the model are presented and compared to experimentally determined torque curves and temperatures. Polym. Eng. Sci. 44:1498–1508, 2004. © 2004 Society of Plastics Engineers.
Effect of ultrasound on extrusion of PP/EPDM blends: Structure and mechanical properties
Authors: Chen Yingzi , Li Huilin 
Published: August 2004

AbstractThe effects of ultrasonic irradiation on the mechanical properties, morphology, and crystal structure of polypropylene (PP)/ethylene‐propylene‐diene terpolymer (EPDM) blends were examined. Results show that appropriate irradiation intensity can noticeably increase the toughness of the PP/EPDM blends without reducing rigidity. Scanning electron microscopic (SEM) observation shows that with ultrasonic irradiation, the morphology of a well‐dispersed EPDM phase is formed in the PP/EPDM blend. The glass transition temperatures of PP and EPDM phase approach each other as a result of ultrasonic irradiation. Differential Scanning Calorimetric (DSC) analysis indicates that the crystallinities of the PP and EPDM phases increase with ultrasonic irradiation, and β crystals of PP form in the PP/EPDM blend with ultrasonic irradiation, which is proven by wide angle X‐ray diffraction (WAXD) analysis. Polym. Eng. Sci. 44:1509–1513, 2004. © 2004 Society of Plastics Engineers.
Determination of the phase transition behavior of thermoplastic polyurethanes from coupled rheology/DSC measurements
Authors: Nichetti Dario , Grizzuti Nino 
Published: August 2004

AbstractThe rich behavior of thermoplastic polyurethanes (TPUs) undergoing phase transition is investigated by means of combined rheological and DSC techniques. In particular, the kinetics of micro‐phase transition of a commercial TPU are followed under both isothermal conditions (crystallization from the melt), and constant temperature rate heating ramps (melting). In rheological tests, the time evolution of the storage modulus is monitored by using a strain rate–controlled rheometer. The rheological results are compared with those obtained by more traditional calorimetric techniques (DSC) under the same thermal histories. It is shown that rheological measurements can give additional (and, in some cases, more accurate) information than that obtained from the more classical thermal analysis. Polym. Eng. Sci. 44:1514–1521, 2004. © 2004 Society of Plastics Engineers.
The thermomechanical environment and the mechanical properties of injection moldings
Authors: Viana Júlio C. , Billon Noelle , Cunha António M. 
Published: August 2004

AbstractAxisymmetric specimens were injection molded in a propylene copolymer with systematic variations of the melt and mold temperatures and the injection flow rate, in a total of 15 different processing conditions. From computer simulations of the mold filling stage using commercially available software packages, two thermomechanical indices were calculated. They aim at evaluating the level of orientation of the skin and the degree of crystallinity of the core layers. Assuming that these morphological features determine the mechanical response of the moldings, the thermomechanical indices were weighted by the relative thickness of the skin and core layers. The tensile behavior of the moldings was assessed at two velocities of 3.3 × 10−5 (2 mm/min) and 3 m/s. The mechanical properties studied were the initial modulus, the yield stress and the strain at break. The relationships between the weighted thermomechanical indices and these mechanical properties were analyzed from 3D response surfaces obtained by polynomial fittings. Globally, a marked effect of the strain rate on the mechanical response along with a distinct sensitivity on the weighted thermomechanical indices was found. At high strain rates the microstructural differences were enhanced. The dependence of the yield stress on the thermomechanical indices was not significantly affected by the strain‐rate. However, the strain‐rate dependence of the other mechanical properties was strongly influenced by the initial microstructural state. Furthermore, the maximization of different mechanical properties could not be made simultaneously due to their distinct microstructural dependences. The concept of the thermomechanical indices is evidenced as a simple, valid and valuable tool to establish straightforward relationships between the processing and the mechanical behavior. Polym. Eng. Sci. 44:1522–1533, 2004. © 2004 Society of Plastics Engineers.
Investigation of morphology formation in SBS block copolymer/homopolystyrene blends
Authors: Huy T. A. , Adhikari R. , Lüpke Th. , Michler G. H. , Knoll K. 
Published: August 2004

AbstractPolymer blends comprising a polystyrene‐block‐polybutadiene‐block‐polystyrene (SBS) block copolymer and atactic homopolystyrene (hPS) were investigated using injection molded and solution cast samples. The morphology of the materials was studied by means of transmission electron microscopy (TEM) and scanning force microscopy (SFM). Dynamic mechanical analysis (DMA) was used to characterize the phase behavior and the morphology formation of the block copolymer as well as of the SBS/hPS blends. The glass transition temperatures seem to strongly depend on the homogeneity of the corresponding phases. A distinct difference was found between the morphologies of the blends prepared by different methods. While the SBS block copolymer always shows a lamellar morphology in injection molded or as‐cast samples, the injection molded blends show a disturbance in the morphology consisting of alternating layers. In contrast, in the case of as‐cast samples, added hPS forms polystyrene domains dispersed in a matrix of the pure block copolymer. Regarding the change in the glass transition temperature, in the effective volume and in the interfacial volume obtained from DMA curves, the morphology formation of the injection molded samples (pure SBS block copolymer and the corresponding blends) was investigated. Two different structural models for the blends are proposed. Polym. Eng. Sci. 44:1534–1542, 2004. © 2004 Society of Plastics Engineers.
Injection molded automotive TPO—a multilayer composite structure of varied orientations
Authors: Strebel J. J. , Mirabella F. , Blythe C. , Pham T. 
Published: August 2004

AbstractOrientation in injection molded polypropylene tensile bars was examined by microscopic and infrared dichroism methods. These methods were then applied to tensile bars molded from TPOs. The injection molded parts were shown to have up to five distinct layers of varying orientation between the outer edge and the center of the sample. In both the polypropylene and TPO formulations, the skin thickness of the moldings increased as the polymer molecular weight increased. A unique, highly oriented region occurred in the core of TPO samples, in contrast to the reduced orientation observed in parts made of propylene homopolymer. The visual observations made from optical photomicrographs were successfully correlated with quantitative orientation data determined by infrared microspectroscopy. Polym. Eng. Sci. 44:1588–1593, 2004. © 2004 Society of Plastics Engineers.
Analysis of the creep behavior of polypropylene‐woodflour composites
Authors: Nuñez Adrián J. , Marcovich Norma E. , Aranguren Mirta I. 
Published: August 2004

AbstractThe creep behavior of composites prepared from woodflour and polypropylene has been analyzed. The woodflour content was varied from 0% to 60%. The compatibility between filler and matrix was varied by adding a non‐commercial polypropylene‐maleic anhydride copolymer (PPMAN) to the mixture. Short‐term and long‐term creep tests of woodflour/polypropylene composites at different temperatures were carried out. The effects of filler content, addition of compatibilizing agent and temperature were discussed. The creep deformation was generally reduced with woodflour addition, except at very high filler concentrations because of filler‐wetting and dispersion problems. Low temperatures and addition of PPMAN also reduced the creep deformation. The creep compliance was modeled using the Bürgers model and a power law equation. The parameters were found from the best fitting of experimental data using an optimization method. The Bürgers model was found to provide a good description of the linear viscoelastic behavior. The mathematical description obtained from the short‐term creep was utilized to predict the dynamic mechanical behavior of the composites with very good agreement between experimental and calculated values. Attempts to use the time‐temperature‐superposition principle to predict long‐term creep from high temperature results were not successful because of the aging of the samples during creep at low temperatures. However, there was a good superposition of the short‐term and long‐term data at temperatures close to 70°C–80°C. The reason for this behavior is a relaxation of the PP matrix that takes place in that temperature range and erases any previous aging of the material. Polym. Eng. Sci. 44:1594–1603, 2004. © 2004 Society of Plastics Engineers.
Influence of electronic effect on catalytic activity of salicylaldiminato nickel(II) complexes
Authors: Zhang Tianzhu , Guo Dawei , Jie Suyun , Sun Wen‐Hua , Li Ting , Yang Xiaozhen 
Published: August 2004

AbstractA means of correlation between the activity and the net charge, the metal atom net charge correlation (MANCC), which was successful in the activity prediction of the early‐transition metal catalysts, has been used to study the catalytic activities of salicylaldiminato Ni(II) complexes, the late‐transition metal catalysts, in olefin polymerization or oligomerization. A comparison with the available quantum mechanics/molecular mechanics (QM/MM) calculation data suggests that even without a detailed mechanism, MANCC results mostly agree with QM/MM calculation data regarding insertion barrier data and enthalpy change. Eight experimental complexes were further built up by modeling; their catalytic activities predominantly increased in line with the net charges on the metal atoms. The same results were obtained for the other four complexes synthesized in the present work. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4765–4774, 2004