bluuebunny/crossref_metadata_2025 huggingface dataset:
Disseminated Epithelial Tumor Cells in Bone Marrow of Patients with Esophageal Cancer: Detection and Prognostic Significance
Authors: Thorban Stefan , Roder Jürgen D. , Nekarda Hjalmar , Funk Armin , Pantel Klaus , Siewert J. Rüdiger
Published: August 2002

Minimal residual disease in patients with operable esophageal cancer is frequently missed by current noninvasive tumor staging. Here we applied an immunocytochemical cytokeratin assay that allows identification of individual esophageal carcinoma cells disseminated to bone marrow. Prior to therapy, bone marrow was aspirated from the upper iliac crest of 71 patients with esophageal cancer at various disease stages as well as an age‐matched control group of 20 noncarcinoma patients. Tumor cells in cytologic bone marrow preparations were detected with monoclonal antibodies (mAbs) CK2, KL1, and A45‐B/B3 to epithelial cytokeratins (CKs) using the alkaline phosphatase antialkaline phosphatase method. CK‐positive cells were found in 14 (36.8%) of 38 cancer patients treated with curative intent and 16 (48.5%) of 33 patients with extended disease. The overall frequency of these cells was 1 per 4 × 105 to 82 per 4 × 105 mononuclear cells with no significant differences between patients at different tumor stages. After a short median follow‐up of 9.5 months (3–24 months), 7 of 11 patients who underwent complete surgical resection but had tumor cells in bone marrow presented with tumor relapse compared to 2 of 19 corresponding patients without such cells (p < 0.01). It was concluded that although bone marrow is not a preferential site of overt metastasis of esophageal cancer, the frequent occurrence of isolated tumor cells at this distant site indicates that hematogenous dissemination of viable malignant cells occurs early in tumor progression.
Role of the Coagulation System in the Local and Systemic Inflammatory Response
Authors: McGilvray Ian D. , Rotstein Ori D.
Published: August 2002

Activation of the coagulation cascade during the inflammatory response is an essential component of the host response to infection. Coagulation represents a double‐edged sword. Necessary for hemostasis and the acute containment of an infective focus, it also amplifies the inflammatory response, decreases bacterial clearance, and in the critically ill patient contributes to end‐organ damage and death. Evidence for these concepts is found in the fact that critically ill and septic patients consistently demonstrate marked abnormalities in their biochemical indices of coagulation. Moreover, there is excellent experimental evidence to suggest that replacement or inhibition of individual coagulation factors, either consumed or up‐regulated during the inflammatory response, can attenuate both local and systemic injury and protect animals from otherwise fatal outcomes. Based on these facts, novel therapeutic approaches to the treatment of the systemic response to infection have been developed and tested in intensive care settings. Although promising results have been obtained, much work remains to be done in defining exactly which coagulation factors (or combination of factors) should be inhibited or replaced during treatment of the septic, critically ill patient. The experimental and clinical evidence linking the coagulation cascade to local and systemic inflammation is reviewed, and the status of the clinical trials performed to date is overviewed.
Comparison of the Hemodynamic Parameters of Open and Laparoscopic Adrenalectomy for Pheochromocytoma
Authors: Inabnet William B. , Pitre Joël , Bernard Denis , Chapuis Yves
Published: August 2002

Laparoscopic adrenalectomy has gained widespread popularity for treating a variety of adrenal disorders including pheochromocytoma, but the effects of pneumoperitoneum on the hemodynamics of patients with catecholamine‐secreting tumors are poorly understood. The goal of this study was to compare the effects of carbon dioxide pneumoperitoneum and tumor manipulation on the hemodynamic parameters in two groups of patients with sporadic pheochromocytomas less than 7 cm in size. Group 1 patients (n= 11) underwent lateral transabdominal laparoscopic adrenalectomy, and group 2 (n= 11) underwent adrenalectomy by the open anterior approach. The mean follow‐up was 37 months in group 1 (range 26–51 months) and 52 months in group 2 (range 27–72 months). All patients undergoing laparoscopic adrenalectomy experienced intraoperative hypertension (blood pressure ≥200/90 mmHg), as did 73% with the open approach, but the difference was not significantly different. Intraoperative hypotension (systolic blood pressure < 80 mmHg) occurred in four group 1 patients compared to six patients in group 2. Mean arterial pressure, central venous pressure, and pulmonary capillary wedge pressure were significantly higher in group 1 patients prior to tumor excision, but there was no difference in pulse, cardiac index, or left ventricle work index at any point during the procedure. There were no conversions or complications in the laparoscopic group; one patient in group 2 developed an incisional hernia. Although laparoscopic adrenalectomy for pheochromocytoma is associated with a greater increase in mean arterial pressure, central venous pressure, and pulmonary capillary wedge pressure, the creation of pneumoperitoneum does not significantly change the cardiac index or left ventricle work index. Carbon dioxide pneumoperitoneum is well tolerated in patients with pheochromocytoma.
Viability analyses with habitat‐based metapopulation models
Authors: Akçakaya H. R.
Published: August 2002

Population viability analysis (PVA) models incorporate spatial dynamics in different ways. At one extreme are the occupancy models that are based on the number of occupied populations. The simplest occupancy models ignore the location of populations. At the other extreme are individual‐based models, which describe the spatial structure with the location of each individual in the population, or the location of territories or home ranges. In between these are spatially structured metapopulation models that describe the dynamics of each population with structured demographic models and incorporate spatial dynamics by modeling dispersal and temporal correlation among populations. Both dispersal and correlation between each pair of populations depend on the location of the populations, making these models spatially structured. In this article, I describe a method that expands spatially structured metapopulation models by incorporating information about habitat relationships of the species and the characteristics of the landscape in which the metapopulation exists. This method uses a habitat suitability map to determine the spatial structure of the metapopulation, including the number, size, and location of habitat patches in which subpopulations of the metapopulation live. The habitat suitability map can be calculated in a number of different ways, including statistical analyses (such as logistic regression) that find the relationship between the occurrence (or, density) of the species and independent variables which describe its habitat requirements. The habitat suitability map is then used to calculate the spatial structure of the metapopulation, based on species‐specific characteristics such as the home range size, dispersal distance, and minimum habitat suitability for reproduction.
Endoscopic‐Assisted Disruption of Urinary Calculi using a Holmium: YAG Laser in Standing Horses
Authors: Judy Carter E. , Galuppo Larry D.
Published: August 2002

Objective—To describe a technique for endoscope‐assisted disruption and removal of urinary calculi using a holmium:YAG laser in sedated, standing horses.

Study design—Retrospective study.

Animals—Six horses with urinary calculi.

Methods—A holmium:YAG laser was used to disrupt naturally occurring urinary calculi in horses (4 geldings, 1 stallion, 1 mare). Ischial urethrotomy was performed in male horses to provide a portal for the endoscope and laser fiber. Calculus fragments were removed by a combination of lavage, transendoscopic basket snare removal, forceps, and digital manipulation. Ischial urethrotomies healed by second intention. Follow‐up was obtained by recheck examination and telephone interview of owners.

Results—No major operative or postoperative complications occurred. Two calculi (1 stallion and 1 mare) were fragmented by a combination of laser ablation and manual disruption with a lithotrite. Postoperative dysuria occurred in the mare, but resolved after 1 month. Mean (± SD) follow‐up was 306 ± 149 days; no other complications were reported.

Conclusions—Calcium carbonate urinary calculi (up to 15 cm in diameter) in horses can be effectively fragmented with a holmium:YAG laser. It is not known if this technique would be completely effective for larger calculi or extremely dense calculi.

Clinical relevance—Calculus disruption by an endoscopically assisted holmium:YAG laser offers a minimally invasive method that can be performed in standing horses and that minimizes patient risk.
Granulocyte‐colony stimulating factor enhances the expression of transforming growth factor‐β mRNA in CD4‐positive peripheral blood lymphocytes in the donors for allogeneic peripheral blood stem cell transplantation
Authors: Hirayama Yasuo , Sakamaki Sumio , Matsunaga Takuya , Kuroda Hiroyuki , Kusakabe Toshiro , Akiyama Takehide , Kato Junji , Kogawa Katsuhisa , Koyama Ryuzo , Nagai Tadanori , Ohta Hidetoshi , Niitsu Yoshiro
Published: August 2002

The degree of acute graft‐versus‐host disease (GVHD) after allogeneic peripheral blood stem cell transplantation (allo‐PBSCT) has been observed to be, unexpectedly, of an equal level to that after bone marrow transplantation. To explain this phenomenon, we hypothesized that granulocyte‐colony stimulating factor (G‐CSF) administration may induce transforming growth factor (TGF)‐β producing T cells in the donors. Five donors received 10 μg/kg G‐CSF subcutaneously for 4 days. The TGF‐β mRNA expression in CD4+ cells as measured by real time reverse transcription‐polymerase chain reaction increased after G‐CSF administration. This elevation is considered to be one additive mechanism of repression of acute GVHD after allo‐PBSCT. Am. J. Hematol. 69:138–140, 2002. © 2002 Wiley‐Liss, Inc.
Activated protein C and inflammation in human myocardium after heart surgery
Authors: Petäjä Jari , Pesonen Eero , Fernández José A. , Griffin John H. , Repo Heikki , Jansson Sten‐Erik , Vento Antti E. , Rämö O. Juhani
Published: August 2002

To assess possible interactions between inflammation and activation of the anticoagulant protein C system during post‐ischemic reperfusion protein C, APC, neutrophil L‐selectin expression and myocardial myeloperoxidase activity (MPO) were measured in 19 patients undergoing cardiopulmonary bypass. After reperfusion for 10 min, APC to protein C ratio (APC/PC) increased from pre‐reperfusion value 1.43 ± 0.12 (mean ± SEM) to 2.25 ± 0.29, p = 0.015. Negative correlations were observed between APC/PC and MPO activity (Spearman r −0.64, p = 0.007) and APC/PC and neutrophil L‐selectin expression (r = −0.7, p = 0.007, demonstrating that post‐ishemic protein C activation was associated with decreased neutrophil tissue sequestration. Thus, physiological protein C activation may be involved in regulation of the inflammatory injury during reperfusion of human ischemic coronary circulation. Am. J. Hematol. 67:210–212, 2001. © 2001 Wiley‐Liss, Inc.
Interrelationship between bone aging traits and basic anthropometric characteristics
Authors: Kalichman Leonid , Cohen Zvi , Kobyliansky Eugene , Livshits Gregory
Published: August 2002

Using plain hand radiographs, the age dependence of various bone‐aging traits (bone mineral density [BMD], cortical index [CI], osteoarthritis [OA], and osseographic [OSS] scores) was evaluated to test whether the correlation among these traits is an individual‐ or population‐based phenomenon. In addition, the effect of anthropometric features on variation of bone‐aging traits was estimated. The study included 1,295 individuals from Chuvasha, Russia, 18 to 89 years. BMD was measured from the compact compartment of the middle and distal phalanges of both 3rd fingers. The CI of the II–IV metacarpal bones and II–IV proximal phalanges was obtained. The development of OA was based on the standard Kellgren and Lawrence grading scheme for 28 hand joints. OSS score, a surrogate measure that takes into account different kinds of bone changes, was also obtained for each individual. Body weight and height, eight skinfold thicknesses on the trunk and extremities, and breadths of the long bones were measured. Sex‐based univariate analyses and multivariate statistical analysis showed the following: 1) Age dependence was defined more strongly in “OA‐linked” compared to “osteoporosis (OP)‐linked” traits; 2) While “OP‐linked” bone‐aging traits correlated with age differently between sexes, “OA‐linked” traits did not; 3) The strong interrelationship between OA‐linked and OP‐linked traits in both sexes became very weak and statistically insignificant (P > 0.10) after adjustment for age. Thus, OA and OP conditions in the same individual develop independently and probably reflect different underlying physiological mechanisms. 4) Anthropometric characteristics were significantly correlated with bone‐aging traits, but correlations were low (r < 0.20). Thus, the contribution of anthropometric characteristics to the rate and pattern of bone aging of the hand was to relatively small. Am. J. Hum. Biol. 14:380–390, 2002. © 2002 Wiley‐Liss, Inc.
Severe and mild phenotypes in Pfeiffer syndrome with splice acceptor mutations in exon IIIc of FGFR2
Authors: Teebi Ahmad S. , Kennedy Shelley , Chun Kathy , Ray Peter N.
Published: August 2002

Pfeiffer syndrome is clinically and genetically heterogeneous. Three clinical subtypes have been delineated based on the severity of acrocephalysyndactyly and associated manifestations. Severe cases are usually sporadic and caused by a number of different mutations in exons IIIa and IIIc of the fibroblast growth factor receptor 2 (FGFR2) gene. Mild cases are either sporadic or familial and are caused by mutations in FGFR2 or FGFR1, respectively. We report on two individuals with different novel de novo mutations in FGFR2. The first is a 17‐year‐old male who has a severe phenotype, within the spectrum of subtype 1 including severe ocular proptosis, elbow ankylosis, visceral anomalies, and normal intelligence. This patient was found to have a novel complex mutation at the 3′ acceptor site of exon IIIc of FGFR2, denoted as C952‐3 del10insACC. The other patient, a 2‐year‐old female, has a mild phenotype, typical of the classic subtype 1 including brachycephaly with coronal synostosis and hypertelorism. She was also found to have a mutation at the 3′ acceptor site (the same splice site) of exon IIIc of FGFR2, a point mutation designated as 952‐1G→A. Speculation on the molecular mechanisms that cause severe and mild phenotypes is presented in relation to these two cases. © 2001 Wiley‐Liss, Inc.
Tandem pore domain K+‐channel TASK‐3 (KCNK9) and idiopathic absence epilepsies
Authors: Kananura Colette , Sander Thomas , Rajan Sindhu , Preisig‐Müller Regina , Grzeschik Karl‐Heinz , Daut Jürgen , Derst Christian , Steinlein Ortrud K.
Published: August 2002

Recently, the gene coding for the tandem pore domain K+‐channel TASK‐3 (KCNK9) has been localized to the chromosomal region 8q24. Because mutations in ion channel genes have been recognized as an important factor in the etiology of abnormal neuronal excitability, TASK‐3 is an interesting candidate gene for epilepsies linked to 8q24. We therefore performed a mutation analysis of the TASK‐3 gene in 65 patients with childhood and juvenile absence epilepsy. Only one silent nucleotide exchange (636C/T) was detected in exon 2 of the TASK‐3 coding region. No evidence for an allelic association was found between the exon 2 polymorphism and absence epilepsy. Accordingly, genetic variation of the TASK‐3 coding region does not play a major role in the etiology of idiopathic absence epilepsies. © 2002 Wiley‐Liss, Inc.
Allelic and nonallelic heterogeneity in dyschondrosteosis (Leri‐Weill syndrome)
Authors: Cormier‐Daire Valérie , Huber Céline , Munnich Arnold
Published: August 2002

Dyschondrosteosis (DCS) is an autosomal dominant form of mesomelic dysplasia that has been recently ascribed to large‐scale deletions and nonsense mutations of the SHOX gene on the pseudoautosomal region of chromosome X and Y [Belin et al., 1998: Nat Genet 19:67–69; Shears et al., 1998: Nat Genet 19:70–73]. Here, we report the molecular analysis of a total of 23 DCS families including 16 previously reported pedigrees [Belin et al., 1998: Nat Genet 19:67–69; Huber et al., 2001: J Med Genet 38:281–284] and 7 novel DCS families. Linkage analyses in 21 of 23 families were consistent with linkage to the pseudoautosomal region. However, in 2 of 23 families, linkage studies excluded SHOX as the disease‐causing gene, suggesting that this condition is genetically heterogeneous. © 2002 Wiley‐Liss, Inc.
Segregation of a novel FBN1 gene mutation, G1796E, with kyphoscoliosis and radiographic evidence of vertebral dysplasia in three generations
Authors: Adès Lesley C. , Sreetharan Darshikka , Onikul Ella , Stockton Vivienne , Watson Karen C. , Holman Katherine J.
Published: August 2002

Skeletal and spinal radiographic findings are described in five individuals of a three‐generation kindred with kyphoscoliosis. The affected individuals have a novel FBN1 gene mutation, G1796E. To our knowledge, this is the first report of a family with an FBN1 gene mutation cosegregating with an unusual autosomal dominant progressive kyphoscoliosis of variable severity, together with radiological abnormalities of the spine, and some skeletal but no ocular or cardiac manifestations of Marfan syndrome. This previously undescribed phenotype represents yet another in the widening spectrum of fibrillinopathies caused by an FBN1 gene mutation. © 2002 Wiley‐Liss, Inc.
Unequal contributions of male and female gene pools from parental populations in the African descendants of the city of Melo, Uruguay
Authors: Sans Mónica , Weimer Tania A. , Franco Maria Helena L.P. , Salzano Francisco M. , Bentancor Nilo , Alvarez Inés , Bianchi Néstor O. , Chakraborty Ranajit
Published: August 2002

In admixed populations, genetic contributions from males and females of specific parental populations can be of different proportions due to past directional mating during the process of genetic admixture. In this research paper, we provide evidence of such male‐ and female‐specific differential admixture components of African, European, and American Indian origin in an admixed population from the city of Melo, in the northeastern region of Uruguay. From data on 11 autosomal markers from a sample of 41 individuals of mixed African descent, we estimated 47% African, 38% European, and 15% Amerindian contributions. In contrast, 6 mtDNA site‐specific polymorphic markers showed that the mtDNA genome of these individuals was 52% African, 19% European, and 29% Amerindian, while from 3 Y‐specific polymorphic sites, we estimated 30% African, 64% European, and 6% Amerindian contributions. We argue that this heterogeneity of admixture estimates results from disproportionate unions of European males with African and American Indian females from which this mixed African population was formed. Also, we argue that the asymmetry of the admixture estimates from the three sets of markers (autosomal, mtDNA, and Y‐linked) is a result of the changes in the direction of mating during the history of the population. Implications of such evidence of directional mating are discussed, indicating the need of further demographic data for a quantitative assessment of the impact of directional mating on genetic structure of admixed populations. Am J Phys Anthropol 118:33–44, 2002. © 2002 Wiley‐Liss, Inc.
Protein surveillance machinery in brains with spinocerebellar ataxia type 3: Redistribution and differential recruitment of 26S proteasome subunits and chaperones to neuronal intranuclear inclusions
Authors: Schmidt Thorsten , Lindenberg Katrin S. , Krebs Antje , Schöls Ludger , Laccone Franco , Herms Jochen , Rechsteiner Martin , Riess Olaf , Landwehrmeyer G. Bernhard
Published: August 2002

Intracellular aggregates commonly forming neuronal intranuclear inclusions are neuropathological hallmarks of spinocerebellar ataxia type 3 and of other disorders characterized by expanded polyglutamine‐(poly‐Q) tracts. To characterize cellular responses to these aggregates, we performed an immunohistochemical analysis of neuronal intranuclear inclusions in pontine neurons of patients affected by spinocerebellar ataxia type 3, using a panel of antibodies directed against chaperones and proteasome subunits. A subset of the neuronal intranuclear inclusions stained positively for the chaperones Hsp90α and HDJ‐2, a member of the Hsp40 family. Most neuronal intranuclear inclusions were ubiquitin positive, suggesting degradation by ubiquitin‐dependent proteasome pathways. Surprisingly, only a fraction of neuronal intranuclear inclusions were immunopositive for antibodies directed against subunits of the 20S proteolytic core, whereas most inclusions were stained by antibodies directed against subunits of the 11S and 19S regulatory particles. These results suggest that the proteosomal proteolytic machinery that actively degrades neuronal intranuclear inclusions is assembled in only a fraction of pontine neurons in end stage spinocerebellar ataxia type 3. The dissociation between regulatory subunits and the proteolytic core and the changes in subcellular subunit distribution suggest perturbations of the proteosomal machinery in spinocerebellar ataxia type 3 brains.
Activity of the hypothalamic–pituitary–adrenal axis in multiple sclerosis: Correlations with gadolinium‐enhancing lesions and ventricular volume
Authors: Schumann Erina M. , Kümpfel Tania , Then Bergh Florian , Trenkwalder Claudia , Holsboer Florian , Auer Dorothee P.
Published: August 2002

The known interaction between the immune system and the hypothalamic–pituitary–adrenal axis led us to explore the interrelation between magnetic resonance imaging findings and the hypothalamic–pituitary–adrenal axis activity in 53 multiple sclerosis patients. The cortisol release induced by the dexamethasone‐corticotropin‐releasing hormone test was negatively associated with the presence and number of gadolinium‐enhancing lesions and positively associated with ventricular size. This finding suggests a protective effect of the hypothalamic– pituitary–adrenal drive on acute lesional inflammation in multiple sclerosis, probably by limiting immune overshoot. In contrast, the nature of the correlation between hypothalamic–pituitary–adrenal hyperdrive and brain atrophy remains to be determined.
Convergence retraction nystagmus: A disorder of vergence?
Authors: Rambold Holger , Kömpf Detlef , Helmchen Christoph
Published: August 2002

The pathological mechanism of convergence retraction nystagmus (CRN) is not known. To determine whether CRN is a disorder of vergence or of the saccadic system, the scleral search coil technique was used to record binocularly the three‐dimensional components of CRN in a patient with a left mesencephalic infarction involving the nucleus of the posterior commissure and the rostral interstitial nucleus of the medial longitudinal fascicle. CRN had disconjugate horizontal and torsional components. The horizontal amplitude/velocity relationship of CRN aligned with the main sequence of vergence responses of normal control subjects but not with that of saccades. Vergence responses of the right eye and left eye were not asynchronous. The slow phases of CRN showed an exponential decay with a time constant of 70 milliseconds. Thus, CRN is probably a disorder of vergence rather than of opposing adducting saccades.
Dysautonomia in human T‐cell lymphotrophic virus type I‐associated myelopathy/tropical spastic paraparesis
Authors: Alamy Alexandre H. , Menezes Fernando B. , Leite Ana C. B. , Nascimento Osvaldo M. , Araújo Abelardo Q‐C.
Published: August 2002

The frequency and importance of dysautonomia in human T‐cell lymphotrophic virus type I–associated myelopathy/tropical spastic paraparesis (HAM/TSP) have not been fully investigated. We describe the characteristics of dysautonomia in such patients in a case‐control study. Our results indicate that autonomic disturbances are more frequent in HAM/TSP than has been previously suggested, with a predominance of sympathetic nervous system dysfunction. In some of these patients, the symptoms may be severe enough to warrant specific treatment.
Silicon quantum dots in diamond matrix: a new synthesis route
Authors: Botti S. , Terranova M. L. , Sessa V. , Piccirillo S. , Rossi M.
Published: August 2002

Light‐emitting layers of silicon quantum dots embedded in a diamond matrix have been prepared by using a new hybrid chemical vapour deposition–powder flowing technique. The polycrystalline diamond matrix is grown by thermal activation of CH4–H2 mixtures. The silicon nanoparticles used for the synthesis of the diamond‐based composites were prepared by CO2 laser pyrolysis of SiH4–He mixtures in a gas flow reactor with controlled atmosphere. During the matrix deposition, the powder‐flowing apparatus drives the silicon nanoparticles across the active area of the substrate, where diamond is growing. A strong room temperature emission is observed from composite films with characteristics dependent on the size distribution of the inserted silicon particles. We report details of the synthesis procedure and emission features of composite diamond films, whose properties promise high technological impact. Copyright © 2001 John Wiley & Sons, Ltd.
Thermal stability of SiCN ceramics studied by spectroscopy and electron microscopy
Authors: Kleebe H.‐J. , Störmer H. , Trassl S. , Ziegler G.
Published: August 2002

Processing of two precursor‐derived SiCN ceramic monoliths was performed employing different liquid polymers, which were obtained by ammonolysis of functionalized chlorosilanes. Preparation of monolithic samples was performed by mixing liquid polysilazane with cross‐linked SiCN‐powder particles, derived from the same precursors by heat treatment at 300 °C, and subsequent annealing upon pyrolysis at temperatures exceeding 1000 °C to initiate crystallization. Characterization of the polymer‐derived ceramics was performed after pyrolysis at 1000 °C and, in particular, after annealing at temperatures ranging from 1400 to 1540 °C. Transmission electron microscopy was conducted in order to study the devitrification/thermal stability of the corresponding bulk SiCN glasses. Depending on the functionalities of the SiCN precursor and the processing conditions, different microstructures were obtained. The material prepared from precursor A showed crystallization of large α‐Si3N4grains within the overall homogeneous amorphous bulk material after exposure at 1540 °C for 6 h in nitrogen atmosphere. In contrast, the ceramic monoliths derived from SiCN precursor B remained completely amorphous, with no indication of local nucleation or crystallization. It is thought that devitrification of these polymer‐derived glasses is promoted by local rearrangements of the glass network within the amorphous bulk. In addition, the role of the excess free carbon, commonly present in polymer‐derived SiCN ceramics,­on the thermal stability is discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Determination of arsenic species in a freshwater crustacean Procambarus clarkii
Authors: Devesa V. , Súñer M. A. , Lai V. W.‐M. , Granchinho S. C. R. , Martínez J. M. , Vélez D. , Cullen W. R. , Montoro R.
Published: August 2002

The arsenic species present in samples of the crayfish Procambarus clarkii caught in the area affected by the toxic mine‐tailing spill at Aznalcóllar (Seville, Southern Spain) were analyzed. The total arsenic contents ranged between 1.2 and 8.5 µg g−1 dry mass (DM). With regard to the different species of arsenic, the highest concentrations were for inorganic arsenic (0.34–5.4 µg g−1 DM), whereas arsenobetaine, unlike the situation found in marine fish products, was not the major arsenic species (0.16 ± 0.09 µg g−1 DM). Smaller concentrations were found of arsenosugars 1a (0.18 ± 0.11 µg g−1 DM), 1b (0.077 ± 0.049 µg g−1 DM), 1c (0.080 ± 0.089 µg g−1 DM), and 1d (0.14 ± 0.13 µg g−1 DM). The presence of two unknown arsenic species was revealed (U1: 0.058 ± 0.058 µg g−1 DM; U2: 0.12 ± 0.12 µg g−1 DM). No significant differences were seen with respect to the total arsenic contents between the sexes. However, significant differences in the total arsenic contents were revealed between the area affected by the spill and the area not affected, the contents being greater in the affected area. Copyright © 2002 John Wiley & Sons, Ltd.
Modeling and experimental studies of emulsion copolymerization systems. III. Acrylics
Authors: Saldívar Enrique , Araujo Odair , Giudici Reinaldo , Guerrero‐Sánchez Carlos
Published: August 2002

Using a previously published model and continuing the series of papers started with styrenic copolymers, predictions for evolution of conversion and average particle diameter in batch experiments are compared against experimental data for four emulsion copolymerizations involving at least one acrylic monomer: (1) methyl methacrylate/butyl acrylate, (2) methyl methacrylate/butadiene, (3) methyl methacrylate–vinyl acetate, and (4) butyl acrylate/vinyl acetate. For each system a fraction of factorial experiments were run covering simultaneous variations in five variables: initiator [I] and surfactant [E] concentrations, water to monomer ratio (W/M), monomer composition, and temperature. Data fitting is performed to represent the experimental data as several parameters are not available from independent experimental sources. The model is able to explain the effects of simultaneous changes in emulsifier concentration, initiator concentration, and water to monomer ratio on conversion and average particle size histories, although in some cases only qualitatively. An assessment of the degree in which a general emulsion copolymerization model is useful for practical applications is made. Physical insight is also gained by observing the trends of adjusted parameters with temperature and copolymer composition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1320–1338, 2002; DOI 10.1002/app.10003
Study of cryostructuration of polymer systems. XXI. Cryotropic gel formation of the water–maltodextrin systems
Authors: Lozinsky Vladimir I. , Damshkaln Lilija G. , Brown Rupert , Norton Ian T.
Published: August 2002

The freeze–thaw behavior of water solutions containing dissolved maltodextrin (MD; enzymatically converted potato starch derivative with MW of 8000 Da) over a wide range of MD concentration (0.1–15 g/dL) and freezing temperatures from −24 to −6°C was studied. Cryogenic treatment of these systems resulted in the formation of precipitates or gels, whose yield and thermal characteristics (fusion temperature and enthalpy) depended on the initial polymer concentration and conditions of freezing, frozen storage, and thawing. There appeared to be at least two stages to this process: (i) a rapid stage, when partial insolubilization occurred while the system was freezing, and (ii) a slower stage, the rate of which was dependent mainly on the thawing regimes used or the duration of storage at subzero temperatures. In this respect, the cryostructuration of MD was very similar to the freeze–thaw behavior of amylopectin/amylose and locust bean gum water solutions studied earlier. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1658–1667, 2002
Synthesis of liquid crystalline epoxy and its mechanical and electrical characteristics—curing reaction of LCE with diamines by DSC analysis
Authors: Lee J. Y. , Shim M. J. , Kim S. W.
Published: August 2002

An aromatic liquid crystalline epoxy monomer based on biphenyl mesogen was synthesized and cured with three different aromatic diamines. The curing reaction characteristics were analyzed by DSC, and the data were introduced to the Kissinger equation to attain the kinetic parameters. Diglycidyl ether of 4,4′‐biphenyl (DGEBP)/4,4′‐diaminobiphenyl (DABP), and DGEBP/4,4′‐methylenediamine (MDA) systems showed an exotherm curing reaction after comelting of the monomers; the DGEBP/p‐phenylenediamine (PDA) system's curing reaction took place in the solid state without melting of monomers. The activation energy and preexponential factor for the DGEBP/DABP system were 55.6 kJ/mol and 4.0 × 106 min−1, respectively. Those values for DGEBP/MDA and DGEBP/PDA systems were 55.1 kJ/mol and 1.0 × 106 min−1 and 148.8 kJ/mol and 7.7 × 1019 min−1, respectively. The rate constant at 100°C for DGEBP/PDA is 2 times higher than those for DGEBP/DABP and DGEBP/MDA, which have almost the same values. Strictly speaking, the rate constant of DGEBP/DABP is a little higher than that of DGEBP/MDA, and these results are in good agreement with the DSC curves. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2419–2425, 2002
Bifunctional coupling agents for improved mechanical properties in fiberglass/polyethylene composites
Authors: Van Dyke J. D. , Gnatowski Marek , Burczyk Andrew
Published: August 2002

Two bifunctional compounds, 12‐azido‐1‐diazo‐2‐dodecanone (A) and 1‐diazo‐17‐octadecene‐2‐one (B), show an ability to act as coupling agents in fiberglass/polyethylene composites. Under appropriate conditions the diazoketone functional groups in both A and B react with hydroxyl groups on a fiberglass surface, whereas the azide group in A and the alkene group in B form bonds with the plastic matrix during processing. FTIR and NMR spectroscopy were used to study the decomposition of each of these compounds under heat and UV light. Each treatment resulted in a relatively fast decomposition of the diazoketone functional group, along with a slower reaction of the azide and alkene groups. Thus it was possible to react the diazoketone end of these compounds with a fiberglass surface, without affecting the azide or alkene functional groups on the other ends of the molecules. In samples of treated fiberglass containing compounds A or B and mixed by extrusion with polyethylene, the mechanical properties of the composites had improved properties over composites containing untreated samples of fiberglass. With A as the coupling agent, both the tensile properties and Izod impact showed changes that indicated that a bifunctional bridge was formed between the fiberglass and polyethylene phases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2562–2578, 2002
Physical aging of poly(diethylene glycol‐p,p′bibenzoate)
Authors: Zamfirova Galina , Misheva Marijka , Kresteva Mania , Djourelov Nikolaj , Benavente Rosario , Pérez Ernesto , Pereña José M.
Published: August 2002

The structure of a quenched sample of a liquid crystalline polyester, poly(diethylene glycol‐p,p′‐bibenzoate) (PDEB), and its physical aging was studied by microhardness methods (MH), wide‐angle X‐ray scattering (WAXS), and positron annihilation lifetime spectroscopy (PALS). It was established that the smectic layers in the liquid crystalline domain are oriented parallel to the sample plane. Physical aging leads to an increase of either the Vickers microhardness, directly related to the elastic modulus of the material, or the total microhardness, which includes all the components of the overall deformation. These mechanical changes are due to a decrease in the sizes of nanopores and the consequential increase of the density of the disordered phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2363–2368, 2002
Melt fracture behavior of polypropylene‐type resins with narrow molecular weight distribution. I. Temperature dependence
Authors: Fujiyama Mitsuyoshi , Inata Hitoshi
Published: August 2002

Polypropylene (PP)‐type resins with narrow molecular weight distribution, such as PP‐type thermoplastic elastomer PER and controlled‐rheology PP (CRPP) made by peroxide degradation of high molecular weight PP, have a problem of easy generation of skin roughness at extrusion. To examine the present state, the occurrence of skin roughness in PER and CRPP at extrusion was investigated with a capillary rheometer in a shear rate range of 12–6100 s−1 and a temperature range of 180–280°C. A homo‐PP (HPP) and a block‐PP (BPP) with usual molecular weight distributions were used for comparison. HPP and BPP with usual molecular weight distributions show smooth extrudates at low shear rates and abruptly generate severe skin roughness “elastic failure” originating at the die entrance at a higher shear rate. PER and CRPP with narrow molecular weight distributions easily generate “sharkskin” melt fracture originating at the die exit, from a shear rate nearly one decade lower than rates of elastic failure of HPP and BPP. The sharkskin becomes more severe, with increasing shear rate, and attains to the elastic failure. The critical shear rate at which sharkskin occurs increases with increasing extrusion temperature. The critical shear rate is about 20 s−1 at 180°C and about 120 s−1 at 280°C, which is in the range encountered by the molten resin at extrusion processing. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2111–2119, 2002
Near‐infrared spectra of polyamide 6, poly(vinyl chloride), and polychlorotrifluoroethylene
Authors: De Araújo Sérgio Carvalho , Kawano Yoshio
Published: August 2002

The near‐infrared spectra (NIR) of polyamide 6 (PA 6), poly(vinyl chloride) (PVC), and polychlorotrifluoroethylene (PCTFE) were measured. The tentative assignment of the overtone and combination frequencies was made with curve fitting calculations and local mode theory. Anharmonicity correction and mechanical frequency were determined from a Birge–Sponer plot. Tentative assignments of stretch overtone frequencies of CH2, NH, and CO functional groups of PA 6 and CH2, and CH functional groups of PVC were made. Anharmonicity corrections of 55, 61, and 20 cm−1 were obtained for CH2, NH, and CO stretch modes of PA 6, respectively, and of 60 and 66 cm−1 for CH2 and CH stretch modes of PVC, respectively. The local mode model seems to be adequate to interpret the origin of the bands observed in NIR spectra of PA 6 and PVC. Anharmonicity corrections of 33, 19, and 16 cm−1 were obtained, respectively, for CF, asymmetrical CF2, and symmetrical CF2 stretch of PCTFE functional groups. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 199–208, 2002
Compatibilization by main‐chain thermotropic liquid crystalline ionomer of blends of PBT/PP
Authors: Zhang Ailing , Zhang Baoyan , Feng Zhiliu
Published: August 2002

The miscibility and mechanical properties of the blends of polybutylene terephthalate (PBT) and polypropylene (PP) with a liquid crystalline ionomer (LCI) containing a sulfonate group on the terminal unit as a compatibilizer were assessed. SEM and optical microscopy (POM) were used to examine the morphology of blends of PBT/PP compatibilized by LCI. DSC and TGA were used to discuss the thermal properties of PBT/PP blends with LCI and without LCI. The experimental results revealed that the LCI component affect, to a great extent, the miscibility and crystallization process and mechanical property of PBT/PP blends. The fact is that increasing LCI did improve miscibility of PBT/PP blends and the addition of 1% LCI to the PBT/PP blends increased the ultimate tensile strength and the ultimate elongation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1110–1117, 2002
Synthesis and characterization of metal‐containing polyurethanes with antibacterial activity
Authors: Jayakumar R. , Rajkumar M. , Nagendran R. , Nanjundan S.
Published: August 2002

Metal salts of mono(hydroxypentyl)phthalate [M(HPP)2, where M is Ca2+, Cd2+, Pb2+, or Zn2+] were synthesized by the reaction of 1,5‐pentane diol, phthalic anhydride, and metal acetate. A new series of metal‐containing polyurethanes containing ionic links in the main chain were synthesized by the reaction of hexamethylene diisocyanate or toluylene 2,4‐diisocyanate with the M(HPP)2 salts. The structures of the monomers and polymers were confirmed with infrared, 1H‐NMR, and 13C‐NMR spectra and elemental analysis. The polymers were also characterized with thermogravimetric analysis, differential scanning calorimetry, and solubility and viscosity measurements. The antibacterial activity of these polyurethanes was investigated with the agar diffusion method. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1194–1206, 2002
Controlled‐release polyurethane created by absorbing transition‐metal acetate and benzyl carbinol
Authors: Ye Shuji , Chen Mingcai
Published: August 2002

Three kinds of the transition‐metal acetates were absorbed into polyurethane to investigate its effect on the desorption velocity of benzyl carbinol and ethyl alcohol from polyurethane. The results show that a small amount of transition‐metal acetate can enhance the absorption amount of benzyl carbinol and ethyl alcohol in polyurethane. With the existence of transition‐metal acetate, benzyl carbinol and ethyl alcohol desorb from polyurethane more slowly. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1170–1173, 2002
Blends of acrylonitrile–butadiene–styrene with an epoxy/cycloaliphatic amine resin: Phase‐separation behavior and morphologies
Authors: López J. , Ramírez C. , Abad M. J. , Barral L. , Cano J. , Díez F. J.
Published: August 2002

The phase‐separation behavior and morphologies of a commercial epoxy resin based on diglycidyl ether of bisphenol A cured with the diamine hardener 1,3‐bisaminomethylcyclohexane and blended with different amounts of acrylonitrile–butadiene–styrene thermoplastic were studied with dynamic mechanical analysis and other techniques. In comparison with the neat system, the modified systems reached before gelation and vitrification, events that were assigned to the onset and endset of the storage modulus signals in a dynamic mechanical analysis curve (storage modulus versus time). These results were explained by a phase‐separation phenomenon induced by polymerization. Scanning electron microscopy and light transmission focused on phase separation revealed a sea‐island morphology for low thermoplastic contents, a bicontinuous structure for intermediate thermoplastic contents, and an epoxy‐nodular phase‐inverted structure for high thermoplastic contents. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1277–1286, 2002
Surface photografting polymerization of vinyl acetate (VAc), maleic anhydride (MAH), and their charge transfer complex (CTC). III. VAc(3)
Authors: Deng Jian‐Ping , Yang Wan‐Tai , Rånby Bengt
Published: August 2002

Vinyl acetate (VAc) was grafted onto low‐density polyethylene (LDPE) substrates by UV irradiation with benzophenone (BP) as the photoinitiator. BP preabsorbed film samples and BP precoated film samples were prepared in advance and applied as the substrates onto which VAc was photografted, together with the method in which BP was dissolved in VAc directly. In addition, the efficiency of the polymerizations applying the preirradiation technology was examined. The conversion percent, grafting percent, and grafting efficiency were determined by a gravimetric method. The contact angles of the grafted films against water were also measured. The results show that BP preabsorbing and precoating were favorable to grafting polymerization, especially the BP precoating method, which was due to its simple operation and the ease of controlling the amount of BP. The diffusion of BP and VAc through the substrates proved to be an important factor for grafting polymerization. Through UV irradiation, dormant groups can be introduced onto LDPE film, which may be activated again by UV irradiation or by heating, leading to the formation of free radicals. Grafting polymerization can be initiated during the activation process in the presence of monomer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1426–1433, 2001
Novel regenerable N‐halamine polymeric biocides. I. Synthesis, characterization, and antibacterial activity of hydantoin‐containing polymers
Authors: Sun Yuyu , Sun Gang
Published: August 2002

Two novel cyclic‐amine monomers, i.e., 3‐allyl‐5,5‐dimethylhydantoin (ADMH) and 7,8‐benzo‐3 allyl‐1,3‐diazasprio[4.5]decane‐2,4‐dione (BADDD) were synthesized with good yields by reacting allyl bromide with 5,5‐dimethylhydantoin (DMH) and 7,8‐benzo‐1,3‐diazasprio[4.5]decane‐2,4‐dione (BDDD), respectively. The synthesized monomers were characterized by FTIR and 1H‐NMR spectra, and copolymerized with acrylonitrile (AN), vinyl acetate (VAC), and methyl methacrylate (MMA) in a small monomer ratio of ADMH and BDDD, respectively. The copolymers were characterized by FTIR, 1H‐NMR, and DSC studies. The N‐halamine derivatives of the corresponding copolymers were found to exhibit high antibacterial activities against Escherichia coli, and the antibacterial properties were durable and regenerable. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2460–2467, 2001
Olefin polymerization using supported metallocene catalysts: Process representation scheme and mathematical model
Authors: Estenoz Diana A. , Chiovetta Mario G.
Published: August 2002

A mathematical model, including the main morphological features of the polymerization process, is developed to study olefin polymerization with supported metallocene catalysts. Because the relatively large amount of methyl alumoxane (MAO) usually needed as a cocatalyst represents a disadvantage, the model introduces a scheme that simulates the results of the efforts being made in a supported catalyst to reduce MAO requirements to commercially acceptable levels. Critical fragmentation steps in the initial support‐catalyst particles that render all active sites effectively available to the monomer are specifically considered, on the basis of the support morphological characteristics. With the available reaction data, fragmentation representation alternatives are discussed and a scheme proposed. Then, a mathematical model is developed based on the above representation scheme, to calculate monomer‐concentration, temperature, and macroparticle‐size evolutions. The main features of the scheme are displayed and discussed. Both for laboratory and high‐productivity conditions, the model is used to predict changes in macro‐ and microparticle size, porosity, and concentration distribution. Predictions are employed to evaluate the impact of the initial support microparticle arrangement and fragmentation processes on the overall catalyst performance. Polymer yield, concentration profiles, and temperature transients predicted by the model are presented, showing the model application after verifying its accordance with the available experimental data. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 285–311, 2001
Kinetics of polyurethane formation between glycidyl azide polymer and a triisocyanate
Authors: Keskin Sema , Özkar Saim
Published: August 2002

Kinetics of the polyurethane formation between glycidyl azide polymer (GAP) and a polyisocyanate, Desmodur N‐100, were studied in the bulk state by using quantitative FTIR spectroscopy. The reaction was followed by monitoring the change in intensity of the absorption band at 2270 cm−1 for NCO stretching in the IR spectrum, and was shown to obey second‐order kinetics up to 50% conversion. The activation parameters were obtained from the evaluation of kinetic data at different temperatures in the range of 50–80°C. The enthalpy and entropy of activation were found to be ΔH‡ = 44.1 ± 0.5 kJ · mol−1 and ΔS‡ = −196 ± 2 J · mol−1l · K−1, respectively. Dibutyltin dilaurate (DBTDL) was used as the curing catalyst. The kinetic study of the polyurethane formation between GAP and Desmodur N‐100 showed that the reaction is enormously speeded up in the presence of the catalyst, and the reaction obeys second‐order kinetics, provided that the catalyst concentration is kept constant. An investigation on the rate of the catalysed reaction depending on the catalyst concentration provided the order of the reaction, with respect to the DBTDL catalyst concentration, and the rate constant for the catalytic pathway of the reaction. The rate constant for the catalytic pathway was established to be 4.37 at 60°C, while the uncatalyzed reaction has a rate constant of 3.88 × 10−6 L · mol−1 · s−1 at the same temperature. A rate enhancement factor of 23 was achieved by using 50 ppm catalyst. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 918–923, 2001