bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rheo‐kinetic measurement of thermoplastic polyurethane polymerization in a measurement kneader
Authors: Verhoeven V. W. A. , Van Vondel M. P. Y. , Ganzeveld K. J. , Janssen L. P. B. M. 
Published: September 2004

AbstractThe rheo‐kinetics of thermoplastic polyurethane (TPU) formation was investigated in a measurement kneader at high temperatures. The TPU was made of a polyester polyol, methyl‐propane‐diol and a 50/50 mixture of 2,4′‐ and 4,4′‐diphenylmethane diisocyanate (MDI). The reaction proceeded according to a second order reaction for which the kinetic constants were determined by size exclusion chromatography (SEC) analysis. The activation energy was found to be equal to 61.3 kJ/mol, and the pre‐exponential factor was equal to 2.18e6 mol/kg K. For the temperature range under investigation, the flow activation energy was equal to 42.7 kJ/mol, which is comparable to that of a linear polymer. This indicates that the hard segments are completely dissolved at the temperatures investigated. The initial part of the reaction was much faster than anticipated from the kinetic measurements. Diffusion limitations at higher conversions probably cause this decrease in reaction velocity. At longer reaction times, the molecular weight leveled off because of depolymerization. Therefore, additional experiments are necessary to describe the complete polymerization of thermoplastic polyurethane. Polym. Eng. Sci. 44:1648–1655, 2004. © 2004 Society of Plastics Engineers.
Flow‐induced morphology of cast polypropylene
Authors: Yin Bo , Yang Wei , Yu Qing‐shun , Yang Ming‐bo 
Published: September 2004

AbstractThe crystal structures of different grades of cast polypropylene (CPP) extrudates were characterized by Differential Scanning Calorimetry (DSC) and Wide Angle X‐ray Diffraction (WAXD). The effects of the crystallization temperature, draw ratio, and cooling rate on crystal structure are discussed in detail. The results demonstrate that stretching cannot induce the formation of the γ crystal, but the crystallization temperature and the cooling rate do affect the formation of the γ crystal. The slower the cooling rate, the more easily the γ crystal develops. It was found that at the optimum crystallization temperature (Tc) of about 110°C, the γ crystal developed distinctly, and a slower cooling rate made the formation of γ crystal easier. Also, the crystal structures of different resins at the same conditions were discriminative, suggesting that the formation of the γ crystal was due to interruptions of comonomer units in the isotactic propylene sequences, which prevented the PP chain segment from entering the crystal lattice of the α crystal in some degree. If the length of the comonomer sequences was shorter and the distribution of the comonomer units more symmetrical, the formation of the γ crystal would be more distinct. Polym. Eng. Sci. 44:1656–1661, 2004. © 2004 Society of Plastics Engineers.
Injection moldability and properties of compatibilized PA6/LDPE blends
Authors: Canfora L. , Filippi S. , La Mantia F. P. 
Published: September 2004

AbstractAn ethylene‐acrylic acid copolymer (EAA), either alone or combined with a low molar mass bis‐oxazoline compound (PBO), has been used as a compatibilization promoter for blends of polyamide‐6 (PA6) with low‐density polyethylene (LDPE). The effect of compatibilization on blend processability in injection molding operations and on the properties of the molded specimens has been studied. In the absence of compatibilization, the injection molded articles were shown to have low‐quality surface appearance and poor mechanical properties. Both these characteristics were appreciably improved as a result of reactive compatibilization of the blends with EAA and, even more, with the EAA‐PBO couple. In fact, the finished articles prepared by injection molding of the quaternary blends were shown to possess good surface appearance, fine and stable morphology and satisfactory mechanical properties. The results confirm the conclusion of a previous study, i.e., that the PBO fourth component may promote the in situ formation of PA6‐g‐EAA copolymers, by reaction with both the functional groups of PA6 and the carboxyl groups of EAA. Polym. Eng. Sci. 44:1732–1737, 2004. © 2004 Society of Plastics Engineers.
A low‐cost, low‐fiber‐breakage, injection molding process for long sisal fiber reinforced polypropylene
Authors: Arzondo L. M. , Vazquez A. , Carella J. M. , Pastor J. M. 
Published: September 2004

AbstractComposites of polypropylene (PP) and non‐treated sisal fiber (SF) were prepared in a non‐conventional two‐step process that offers significant advantages. Maleic anhydride–grafted polypropylene (MA‐g‐PP) was used as a coupling agent, to improve adhesion between the polar sisal fiber and the non‐polar polypropylene continuous matrix. At a first step, SF/MA‐g‐PP pellets with large aspect ratio and very high fiber content are prepared by extrusion impregnation and coating of a continuous SF yarn, followed by cooling and cutting. The composite pellets are thus dry blended with regular PP pellets in the injection machine hopper, and injected to obtain composite tensile specimens with a minimum quantity of expensive MA‐g‐PP, minimum fiber breakage and thermal degradation, and excellent mechanical properties. The SF/MA‐g‐PP pellets have a fiber content of 70% (w/w). The composite tensile specimens have final fiber contents ranging from about 3.5% to 24.5% (w/w). The PP tensile strength rises by about 44%. The tensile modulus increases by 126%, and the heat distortion temperature (HDT) is raised by about 35 K. FT‐IR spectroscopy and SEM micrographic observation show that the MA‐g‐PP is covalently bonded to SF through esterification. Besides the improvement in mechanical and thermal properties, costs are reduced because of the lower content of very expensive MA‐g‐PP, and the use of a single‐screw extruder at high production rates. Polym. Eng. Sci. 44:1766–1772, 2004. © 2004 Society of Plastics Engineers.
Impact strength and elongation‐to‐break of compatibilized ternary blends of polypropylene, nylon 66, and polystyrene
Authors: Debolt Michael A. , Robertson Richard E. 
Published: September 2004

AbstractThe Izod impact strength and tensile elongation‐to‐break were measured for blends of nylon 66 and polystyrene in a polypropylene matrix with and without compatibilization by an ionomer resin (for nylon 66) and a styrene‐block‐ethylene‐co‐butylene‐block‐styrene copolymer (for polystyrene). With 20% nylon 66 and 20% polystyrene, about 5% of each compatibilizer was optimal. When used together for the ternary blend, there seemed to be little gross interference (or synergism) between the compatibilizers. A comparison between binary blends suggests that what interaction does exists may be synergistic. Polym. Eng. Sci. 44:1800–1809, 2004. © 2004 Society of Plastics Engineers.
Convergence and computation of describing functions using a recursive Volterra series
Authors: Glass J. W. , Franchek M. A. 
Published: September 2004

AbstractPresented in this paper is a comparison of algorithms for computing an approximation to the sinusoidal input describing function (SIDF) for the nonlinear differential equation
ẏ(t)+b1y(t)+b2u2(t)y(t) = K(u̇(t)+b3u(t))
The importance of this nonlinear differential equation comes from the context of nonlinear feedback controller design. Specifically, this equation is either a linear lead or lag controller (depending on the coefficient values) augmented with a nonlinear, polynomial type term. Consequently, obtaining a SIDF representation of this nonlinear differential equation or creating a process to obtain SIDFs for other similar differential equations, will facilitate nonlinear controller design using classical loop shaping tools. The two SIDF approximations studied include the well‐established harmonic balance method and a Volterra series based algorithm. In applying the Volterra series, several theoretical issues were addressed including the development of a recursive solution that calculates high order Volterra transfer functions, and the guarantee of convergence to an arbitrary accuracy. Throughout the paper, case studies are presented. Copyright © 2004 John Wiley & Sons, Ltd.
High interannual variation in the hatching sex ratio of Tengmalm's owl broods during a vole cycle
Authors: Hipkiss Tim , Hörnfeldt Birger 
Published: September 2004

AbstractThe sex ratio at hatching in broods of Tengmalm's owl (Aegolius funereus) in northern Sweden was investigated for 3 years characterized by different phases of the vole and owl cycle. Previous work showed the sex ratio in this species to be male‐biased for 1 year with a favourable food supply, and that in feeding experiments male nestlings (but not females) suffered higher mortality when food was limited, but not otherwise. Here we present data from a complete 3‐year owl cycle, showing that mean brood sex ratio varied significantly among years, being male‐biased (65% males) in the first year of high owl breeding density, unbiased (49%) in the second year of high owl breeding density, and female‐biased (33% males) in the owls’ low year. Brood sex ratio did not vary significantly within years with laying date or parental age. Vole availability, and therefore the owls’ food supply, declined during the 3 years studied. Tengmalm's owl parents thus appear to adaptively adjust the sex ratio of their broods according to the expected annual mortality risk of sons.
Separation–individuation revisited: on the interplay of parent–adolescent relations, identity and emotional adjustment in adolescence☆
Authors: Meeus Wim , Iedema Jurjen , Maassen Gerard , Engels Rutger 
Published: September 2004

AbstractThe objective of this study was to test our alternative interpretation of the separation–individuation hypothesis. This interpretation states that separation from the parents is not a precondition for individuation, but rather separation and individuation are two parallel processes of development during adolescence. We investigated our interpretation in two ways. Firstly, we looked at descriptive age differences in parental support and development of relational and societal identity. Secondly, we investigated the variation with age of the associations between parental support and emotional adjustment, and identity and emotional adjustment. Data of a representative Dutch sample of 2814 adolescents, aged 12–24 were used. In both cases, the findings supported our interpretation of the separation–individuation hypothesis and similar results were found in the descriptive analyses and the structural equation models. Parental support decreased with age, and so too did its association with emotional adjustment. In other words, as adolescents become older, they experience less parental support, while its importance for their emotional adjustment also declines. The opposite pattern was observed with respect to identity development: as adolescents become older, their relational and societal identity commitments develop, and the degree to which these commitments are developed also becomes more important for their emotional adjustment.
A Meeting with History
Authors: Carson Zosia 
Published: September 2004

In 2003 I was one of the lucky recipients to be awarded a BIALL bursary to attend the 22nd Annual Course on International Law Librarianship from the 21st to 25th September held in Cape Town, South Africa. This is my personal report of my experiences which I would like to share with LIM readers. My report will focus on four aspects:1. Robben Island2. Ahmed Kathrada3. A meeting with history4. Final impressions
Elevation of lung surfactant phosphatidylcholine in mouse models of Sandhoff and of Niemann–Pick A disease
Authors: Buccoliero R. , Ginzburg L. , Futerman> A. H. 
Published: September 2004

AbstractSummary: Sandhoff disease is caused by the defective activity of the lysosomal enzyme β‐hexosaminidase, resulting in accumulation of the glycolipids, GA2 and GM2. Niemann–Pick A/B disease is caused by the defective activity of lysosomal acid sphingomyelinase resulting in sphingomyelin accumulation. Pulmonary complications have been observed in both diseases. We now demonstrate changes in phospholipid levels in pulmonary surfactant in mouse models of these diseases. In the Hexb mouse, a model of Sandhoff disease, lipid phosphate levels were elevated in surfactant from 3‐ and 4‐month‐old mice, which was mainly due to elevated levels of phosphatidylcholine. In the ASM mouse, a model of Niemann–Pick A disease, levels of the primary storage material, sphingomyelin, were elevated as expected, and levels of phosphatidylcholine and two other phospholipids were also significantly elevated in pulmonary surfactant and in lung tissue from 5‐, 6‐ and 7‐month‐old mice. These results suggest that changes in phospholipid levels and composition in lung surfactant might be a general feature of sphingolipid storage diseases, which may be in part responsible for the increased susceptibility of these patients to respiratory infections and lung pathology, often the main reason for the death of these patients.
Severe neonatal onset of glycogenosis type IV: Clinical and laboratory findings leading to diagnosis in two siblings
Authors: Giuffrè B. , Parini R. , Rizzuti T. , Morandi L. , van Diggelen O. P. , Bruno C. , Giuffrè M. 
Published: September 2004

AbstractSummary: Glycogenosis type IV is an autosomal recessive disease, exceptionally diagnosed at birth: only very few reports of the fatal perinatal neuromuscular form have been described. We report on two sibling male newborns who died at 10 and 4 weeks of age with clinical signs of a systemic storage disease. Prenatal history included polyhydramnios, reduced fetal movements and fetal hydrops, Caesarean section was performed at 36 weeks of gestational age because of fetal distress. At birth, both babies showed severe hypotonia, hyporeflexia and no spontaneous breathing activity. They never showed active movements, sucking and swallowing and were respirator‐dependent until death. A muscle biopsy revealed, in both patients, the presence of PAS‐positive and partially diastase‐resistant cytoplasmic inclusions containing granular and filamentous amylopectin‐like material. This suggested that the stored material consisted of abnormal glycogen. At autopsy, ultrastructural examination of cardiac and skeletal muscle, liver, kidney and brain showed PAS‐positive diastase‐resistant eosinophilic cytoplasmic inclusions. Determination of branching enzyme activity, in cultured fibroblasts from the second patient, showed markedly reduced enzyme activity, confirming diagnosis of glycogenosis type IV. Our patients showed the full spectrum of both prenatal signs (hydrops, polyhydramnios) and postnatal signs (hypotonia, hyporeflexia, absence of active movements, cardiomegaly), which have been reported previously. They suffered from a very severe form of glycogenosis type IV with clinical and histological involvement of many tissues and organs. Diagnosis was accomplished on the second baby and required several biochemical and histological studies, in order to rule out both neuromuscular disorders and the most common storage diseases with neonatal onset. In our experience, the correct interpretation of the histological findings was essential in the search for the diagnosis.
Assessment of an electron‐impact GC‐MS method for organic acids and glycine conjugates in amniotic fluid
Authors: Kumps A. , Vamos E. , Mardens Y. , Abramowicz M. , Genin J. , Duez P. 
Published: September 2004

AbstractSummary: We assessed the reliability of a method designed for common electron‐impact GC‐MS systems to determine in a single run most organic acids and glycine conjugates of clinical interest in amniotic fluid. Suitable sensitivity was achieved by dividing the selected‐ion chromatogram into 12 time segments during which the monitoring dwelt on specific ions. Twelve metabolites were simultaneously quantified in amniotic fluid, with performances ranging from very good to clinically acceptable. The total coefficient of variation was 2.5–14.1% and the detection limit was well below the lower value of the physiological range. For five other metabolites, the precision was lower and/or the detection limit was near the physiological range. The method was clinically assessed by the prenatal detection of three cases of tyrosinaemia type I and one case of propionic acidaemia. Analytical and clinical evaluation of the method showed that GC‐MS with electron‐impact fragmentation can be an informative analytical approach for low‐level organic acids in physiological fluids. Apart from the case of glycine conjugates, the method shows a fair reliability for amniotic fluid analysis, which might warrant its use for prenatal diagnosis of organic acidurias. However, this method cannot replace procedures using isotopic internal standards, nor GC‐MS based on chemical ionization fragmentation, which remain confirmatory analytical methods of choice.
Improvement of CDG diagnosis by combined examination of several glycoproteins
Authors: Fang J. , Peters V. , Körner C. , Hoffmann G. F. 
Published: September 2004

AbstractSummary: Congenital disorders of glycosylation (CDG) represent a family of genetic diseases with broad clinical presentation. Initial diagnosis is currently mainly based on the identification of hyposialylated serum transferrin (TF) by isoelectric focusing (IEF). To improve the diagnosis of known CDG types and to identify so far unknown CDG cases, additional glycoproteins, α1‐antitrypsin (α1‐AT) and α1‐antichymotrypsin (α1‐ACT), were studied. According to the patterns of transferrin, enzyme assays and mutation analysis, 16 patients with various clinical symptoms suspicious for CDG were divided into three groups: group A (n = 6) with confirmed CDG; group B (n = 4) with clear abnormal TF‐IEF patterns of unknown origin (all known CDG types were excluded) and group C (n = 6) with borderline TF‐IEF patterns; 164 samples served as a control group. Automated IEF of TF, α1‐AT and α1‐ACT was carried out using a PhastSystem. CDG patients with glycosylation defects of known origin (group A) and patients with abnormal TF‐IEF patterns due to glycosylation defects of as yet unknown origin (group B) showed abnormal IEF patterns of all three glycoproteins. These results confirmed generalized defects of glycosylation. Furthermore, the IEF pattern of α1‐ACT seems to allow a differentiation between CDG Ia and CDG Ic. However, patients with borderline TF‐IEF pattern (group C) showed a normal α1‐AT‐IEF pattern. Four of these six patients also showed a normal α1‐ACT‐IEF pattern; this constellation suggests that CDG can most likely be excluded. In the two remaining patients of group C with a borderline TF‐IEF pattern an abnormal pattern of α1‐ACT‐IEF was obtained which needs further investigations. We conclude that the combined investigation of three glycoproteins provides additional information in the diagnostic work‐up of patients with possible CDG. The suspicion of CDG in patients with apparent glycosylation defects of unknown origin or borderline TF‐IEF pattern can be either substantiated or weakened.
The Influence of Very Low Doses of Cisplatin on Tumor Cell Proliferation In Vitro and on Some Hematological and Enzymatic Parameters of Healthy Rats
Authors: Malarczyk Elżbieta , Kandefer-Szerszeń Martyna , Jarosz-Wilkołazka Anna 
Published: September 2004

Healthy rats had been treated for 2 or 6 weeks with 1.0 mL of 10−8 and 10−16 mg/mL of cisplatin. After 2 weeks of treatment, a significant increase in leukocyte and erythrocyte count and also in hematocrit was observed. Among leukocytes the number of neutrophils and eosinophils significantly increased. Biochemical analyses indicated a decrease in the glycogen content in the liver and kidneys after 2 weeks of treatment with low doses of cisplatin but at the end of the experiment (8th week of experiment) the stores of glycogen increased significantly. Biochemical analyses concerning the activity of some enzymes in the liver revealed a significant increase of peroxidase and acid phosphatase as well as catalase activities after 2 weeks of treatment. However, catalase was induced by a very low concentration of cisplatin, 10−16 mg/mL. After the cessation of cisplatin treatment the activity of enzymes returned to normal values. Human lung carcinoma cell line A549 (ECACC No 86012804) was also studied after treatment with the same doses of cisplatin and inhibition of its growth was observed. The results of these experiments strongly indicated that low doses of cisplatin could be stimulating for healthy cells but cytostatic for tumor cells. Possible mechanisms involved in the biological activity of very low cisplatin concentrations are discussed.
Assessment of Salivary Flow Rate: Biologic Variation and Measure Error
Authors: Jongerius Peter H. , van Limbeek Jacques , Rotteveel Jan J. 
Published: September 2004

AbstractObjective: To investigate the applicability of the swab method in the measurement of salivary flow rate in multiple‐handicap drooling children. To quantify the measurement error of the procedure and the biologic variation in the population.Study Design: Cohort study.Methods: In a repeated measurements design, a baseline series of salivary flow rates were obtained from 45 children. The within‐subject SD (SW) was calculated to express the measurements error according to a procedure introduced by Bland and Altman.Results: Two hundred twenty‐four samples (mean 0.40 mL/min, SD 0.19 mL/min) were obtained and analyzed. The results of this study indicate that consistent scores were obtained at subsequent measurements, and good parity existed between the two measurements of salivary flow rate at each session. The SW could be estimated (0.11 mL/min), which was applied to quantify the specific variation of the salivary flow rate in our population.Conclusion: According to Bland and Altman, the SW, which is a quantification of the measurement error and biologic variation, was found to be a useful tool to evaluate the obtained baseline salivary flow rate measurements. The swab method can be used to evaluate salivary flow rates in drooling children with cerebral palsy during interventional studies that aim to reduce saliva production.
OK‐432 Therapy for Cervical Lymphangioma
Authors: Sichel Jean‐Yves , Udassin Raphael , Gozal David , Koplewitz Benjamin Z. , Dano Itszhak , Eliashar Ron 
Published: September 2004

AbstractObjective: To describe our experience with sclerosing treatment of lymphangiomas in the head and neck region by intralesional injections of OK‐432.Study Design: Case series.Methods: Patients with the diagnosis of a macrocystic‐type cervical lymphangioma were treated by one to three intralesional injections of OK‐432 (0.01 mg of OK‐432/1 mL of lymphangioma fluid, up to a maximum of 0.2 mg in the first injection and 0.3 mg in the second or third injections). All injections were performed under ultrasound guidance. Children were injected under sedation.Results: Eleven patients were treated with injections of OK‐432: 7 children and 4 adults. They were followed up for a period of 5 to 68 (mean 30) months. Eight (73%) patients had complete or subcomplete resolution of the lymphangioma after one or two injections. In three (27%) cases, no response was obtained (2 cases) or the lymphangioma recurred (1 case) after two to three injections. In two cases, surgical excision was performed. There was no evidence of fibrosis around the cysts. There were no complications to OK‐432 injections.Conclusion: Intralesional injection of OK‐432 is an effective treatment modality for macrocystic‐type lymphangiomas in the head and neck region. It has no complications, and surgical excision in case of failure is not compromised by fibrosis. Sclerosing of macrocystic‐type lymphangiomas with OK‐432 should therefore be considered before surgical excision.