bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of home furnishings expenditures in the USA during the 1990s
Authors: Norum Pamela S. , Lee Keum‐Kyu , Sharpe Deanna L.
Published: October 2002

The purpose of this study is to provide an updated view of the effects of selected socioeconomic and demographic factors on household expenditures for home furnishings among US households. Using consumer demand theory as the underlying theoretical framework, Tobit analysis was used to estimate expenditure equations for household textiles, floor coverings, and furniture using the 1995 Consumer Expenditure Survey. Although the home furnishings industry grew significantly during the 1980s and 1990s, the results of this study indicate that the socioeconomic and demographic factors underlying home furnishing expenditures have remained fairly stable. However, long‐run trends in the age distribution and ethnic composition of the US population suggest that the young adult market and Hispanic consumers are market segments that could provide greater opportunities for companies in the home furnishings industry. In addition, building on the fashion orientation that has developed in home fashions during the past 20 years may provide further opportunities. Finally, future research could benefit from the inclusion of more dwelling‐specific variables, such as the number of rooms in the household, and whether or not remodeling occurred.
Vibrio parahaemolyticus scrABC
, a Novel Operon Affecting Swarming and Capsular Polysaccharide Regulation
Authors: Boles Blaise R. , McCarter Linda L.
Published: October 2002

Swarming is an adaptation of many bacteria to growth on surfaces. A search for genes controlling swarmer cell differentiation of
Vibrio parahaemolyticus
identified a novel three-gene operon that potentially encodes a pyridoxal-phosphate-dependent enzyme, an extracellular solute-binding protein, and a membrane-bound GGDEF- and EAL-motif sensory protein. The functions of these motifs, which are named after conserved amino acid sequences, are unknown, although the domains are found singly and in combination in a variety of bacterial signaling proteins. Studies with translational fusions supported the predicted localization of the gene products. When the operon was overexpressed, swarmer cell gene transcription was induced in liquid culture. Mutants with defects in any of the three genes exhibited decreased swarming and lateral flagellar (
laf
) gene expression. Complementation studies confirmed an operon organization and suggested that all three genes participated in
laf
regulation. The lesions that decreased swarming increased capsular polysaccharide (CPS) production, and overexpression of the operon inhibited transcription of the CPS gene
cpsA
. Thus, the
scrABC
locus appears to inversely regulate two gene systems that are pertinent to colonization of surface swarming and CPS.
l
-Malyl-Coenzyme A Lyase/β-Methylmalyl-Coenzyme A Lyase from
Chloroflexus aurantiacus
, a Bifunctional Enzyme Involved in Autotrophic CO
2
Fixation
Authors: Herter Sylvia , Busch Andreas , Fuchs Georg
Published: October 2002

The 3-hydroxypropionate cycle is a bicyclic autotrophic CO
2
fixation pathway in the phototrophic
Chloroflexus aurantiacus
(
Bacteria
), and a similar pathway is operating in autotrophic members of the
Sulfolobaceae
(
Archaea
). The proposed pathway involves in a first cycle the conversion of acetyl-coenzyme A (acetyl-CoA) and two bicarbonates to
l
-malyl-CoA via 3-hydroxypropionate and propionyl-CoA;
l
-malyl-CoA is cleaved by
l
-malyl-CoA lyase into acetyl-CoA and glyoxylate. In a second cycle, glyoxylate and another molecule of propionyl-CoA (derived from acetyl-CoA and bicarbonate) are condensed by a putative β-methylmalyl-CoA lyase to β-methylmalyl-CoA, which is converted to acetyl-CoA and pyruvate. The putative
l
-malyl-CoA lyase gene of
C. aurantiacus
was cloned and expressed in
Escherichia coli
, and the recombinant enzyme was purified and studied. β-Methylmalyl-CoA lyase was purified from cell extracts of
C. aurantiacus
and characterized. We show that these two enzymes are identical and that both enzymatic reactions are catalyzed by one single bifunctional enzyme,
l
-malyl-CoA lyase/β-methylmalyl-CoA lyase. Interestingly, this enzyme works with two different substrates in two different directions: in the first cycle of CO
2
fixation, it cleaves
l
-malyl-CoA into acetyl-CoA and glyoxylate (lyase reaction), and in the second cycle it condenses glyoxylate with propionyl-CoA to β-methylmalyl-CoA (condensation reaction). The combination of forward and reverse directions of a reversible enzymatic reaction, using two different substrates, is rather uncommon and reduces the number of enzymes required in the pathway. In summary,
l
-malyl-CoA lyase/β-methylmalyl-CoA lyase catalyzes the interconversion of
l
-malyl-CoA plus propionyl-CoA to β-methylmalyl-CoA plus acetyl-CoA.
Significant overestimation of needle surface area estimates based on needle dimensions in Scots pine (Pinus sylvestris)
Authors: Lin Jinxing , Sampson D A , Deckmyn G , Ceulemans R
Published: October 2002

Needle length and width at midpoint are often used to make estimates of needle surface area for conifers. For these estimates, Scots pine (Pinus sylvestris L.) fascicles are assumed to be cylindrical; thus, for a two-needle pine, the cross section of a needle within the fascicle is assumed to be hemicylindrical. The objectives of this study were to determine whether these assumptions lead to a good estimate of the actual surface area and how needles vary with tree age and crown position. We used a digital scanning microscope to measure needle width, thickness, and perimeter at 11 positions along 28 needles from different crown positions in different-aged trees and found that they varied with position within the individual needle as well as with tree age and crown position. Needle shape was relatively constant: needle width and perimeter both increased from the base to the needle midpoint and then decreased slightly to the needle tip, but needles were not hemicylindrical and actual perimeters were nearly 12% larger than predicted perimeters. The predicted surface areas based on measurements of width at the needle midpoint and length need to be reduced by 9% to account for the fact that needles taper and are not cylindrical. Furthermore, tree age and crown position must be considered when crown-level estimates are made.Key words: digital image analyzer, light microscope, needle width, needle thickness, needle perimeter, Pinus sylvestris.
A HIERARCHICAL MEASUREMENT FRAMEWORK FOR THE EVALUATION OF AUTOMATED BUSINESS PROCESSES
Authors: AIELLO ROSSELLA , ESPOSITO ANTONIO , NOTA GIANCARLO
Published: October 2002

The problem of performance evaluation of business processes supported by Workflow Management Systems is a recent research issue. In this paper we propose a measurement framework in which several aspects concerning the timing and working of a business process, either as a whole or in terms of its components, can be precisely quantified.

Our approach is based on the workflow model introduced by the Workflow Management Coalition and introduces some fundamental measures from which a number of derived measures can be hierarchically obtained.

The paper describes the basic structures and the primitive operators of the framework as well as the fundamental and derived measures. Techniques for the evaluation of complex processes are also discussed. The proposed framework is quite general and can be applied to research and commercial workflow management systems with relatively little implementation effort.
APPLICATIONS OF CASCADED QUADRATIC NONLINEARITIES TO FEMTOSECOND PULSE GENERATION
Authors: WISE FRANK , QIAN LIEJIA , LIU XIANG
Published: October 2002

Useful nonlinear phase shifts can be produced in cascaded quadratic processes. The issues that arise in the extension of cascade nonlinearities to the femtosecond regime are outlined in this paper, and initial applications of the cascade phase shifts to femtosecond pulse generation and propagation are reviewed. The results demonstrate that the cascade phase shifts offer unique properties, and in some cases pulse-shaping techniques based on cascade nonlinearities have potential to offer substantial performance improvements over existing approaches.
ALL-OPTICAL REFLECTANCE CONTROL BASED ON PHOTOINDUCED COMPLEX REFRACTIVE INDEX CHANGES IN GUIDED MODE THIN FILMS CONTAINING INDIUM OR GALLIUM PHTHALOCYANINES
Authors: NAGAMURA TOSHIHIKO , NAITO ATSUSHI , YOSHIDA IORI , CHEN YU , HANACK MICHAEL
Published: October 2002

Tetrasubstituted indium or gallium phthalocyanines and their dimers bridged with various ligands were dispersed in a polymer thin film, which was spin-coated on silver thin film vacuum-evaporated on a glass slide. All-optical reflectance control was achieved by complex refractive index changes upon photoexcitation of phthalocyanines by nanosecond laser in such a guided mode geometry. They gave rise in less than ns pulse width, and a few to a few tens of microseconds decay characteristic to the lifetime of the excited triplet state. Repeated and reversible reflectance changes were achieved. Axially bridged phthalocyanine dimers showed almost the same photoresponses as monomers.
Comparison of volatile emissions and structural changes of melt reprocessed polypropylene resins
Authors: Xiang Q. , Xanthos M. , Patel S. H. , Mitra S.
Published: October 2002

Polypropylene (PP), as a commodity recyclable thermoplastic, was studied in this research to evaluate the potential environmental impact resulting from volatile organic compounds (VOCs) emitted during multiple melt reprocessing. Unstabilized PP (U‐PP) and stabilized PP (S‐PP) resins, simulating recycled materials prone to degradation, were evaluated for total VOC emissions generated during multiple melt reprocessing by injection molding and extrusion, respectively. Results show that the maximum amount of total VOCs from each cycle (up to six cycles for extrusion and up to ten for injection molding) did not significantly change, while the cumulative VOCs increased with increasing processing cycle for both materials. A good correlation between cumulative VOC increases and melt flow index increase for the U‐PP and weight‐average molecular weight Mw decrease for the S‐PP were obtained. Reprocessing in all cases was accompanied by decreases in Mw and melt viscosity as a result of thermooxidative degradation. FTIR data considering increases in carbonyl content and degree of unsaturation suggest that at equivalent cycle numbers, degradation appears to be more severe for the extruded material in spite of the longer oxidative induction time of the “as received” pellets used in extrusion. The onset and type of structural changes are shown to depend on cycle number and reprocessing method. © 2002 Wiley Periodicals, Inc. Adv Polym Techn 21: 235–242, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10027
Past asbestos exposure levels in foundries and cement‐asbestos factories
Authors: Mattioli Stefano , Nini Donatella , Mancini Gianpiero , Violante Francesco S.
Published: October 2002

To the Editor:

Rosenman and Reilly [1998] reported that in Michigan, from 1985‐1996, 115 patients were reclassified as having asbestos (and not silicosis, pneumoconiosis, or pulmonary fibrosis)related X‐ray changes. In their article, the authors also provided three case reports of asbestosis among foundry workers, underlining the entity of the asbestos exposure. The situation seems to be rather similar in Italy, where asbestos was very widely used in the local foundries for gloves, aprons, insulations, curtains. For example, we recently examined, because of a worker's claim, a man who had worked in foundry for 30 years (between 1962 and 1992) and had complained of cough since 1990: in 1993, an X‐ray examination revealed the presence of asbestosis. Other reports of asbestosis in Italian foundry workers can also be found in the literature [Scancarello et al., 1996]. This important association may actually be rather widespread [see, e.g. Corhay et al., 1990].

While examining the literature referring to asbestos exposure among foundry workers, we were intrigued to come across a study dating from 1989 [Guillemin et al., 1989] on the presence of asbestos fibers in the urine of workers in a cement‐asbestos factory where the controls were actually represented by foundry workers! The authors concluded that their "study did not prove with a sufficient level of statistical confidence that workers exposed to low levels of chrysotile asbestos excrete more fibers in urine than do non‐exposed workers" (foundry workers). With the current state of our knowledge, it is not so hard to understand why. The study may now be interpreted as suggesting that foundry workers employed around that time suffered exposure levels not significantly dissimilar to those encountered by cement‐asbestos factory workers.
Craniosynostosis in Alagille syndrome
Authors: Kamath Binita M. , Stolle Catherine , Bason Lynn , Colliton Raymond P. , Piccoli David A. , Spinner Nancy B. , Krantz Ian D.
Published: October 2002

Alagille syndrome is a multisystem developmental disorder with primary involvement of the liver, heart, skeleton, eyes and facial structures, and demonstrates highly variable expressivity with respect to all of the involved systems. Alagille syndrome is caused by mutations in the Jagged1 gene. Jagged1 is a ligand in the Notch signaling pathway that has been shown to regulate early cell fate determination. Mutations in Jagged1 have been identified in approximately 80% of patients with Alagille syndrome. We have recently identified two patients with mutation proven Alagille syndrome who also had unilateral coronal craniosynostosis. Both individuals were screened for mutations in fibroblast growth factor receptor 1, 2, 3 and TWIST genes, all associated with various types of craniosynostosis and no mutations were identified. The finding of a conserved form of craniosynostosis in two unrelated patients with Alagille syndrome and mutations in Jagged1 may indicate that Jagged1 plays a role in cranial suture formation. © 2002 Wiley‐Liss, Inc.
Linear and whorled nevoid hypermelanosis with bilateral giant cerebral aneurysms
Authors: Mégarbané A. , Vabres P. , Slaba S. , Smahi A. , Loeys B. , Okais N.
Published: October 2002

A 24‐year‐old woman presented with bilateral giant intracavernous carotid artery aneurysms manifesting as a cavernous sinus syndrome on the left side, and anisocoria, ophthalmic pain, and oculomotor paresis on the left side. Physical examination showed mild hyperextensibility of the metacarpophalangeal joints, amelogenesis imperfecta, and hyperpigmentation following Blaschko lines. Analysis of the NEMO gene for incontinentia pigmenti syndrome and of collagen III for Ehlers‐Danlos type IV was normal. Skewed X‐inactivation patterns in blood lymphocytes were detected. To the best of our knowledge, this association of linear hyperpigmentation and cerebral aneurysms has never been previously reported. © 2002 Wiley‐Liss, Inc.
Referral for genetic counseling after the birth of a child with a congenital anomaly in the Northern Netherlands
Authors: Sikkens Ewold H. , de Walle Hermien E.K. , Reefhuis Jennita , Tintelen J. Peter van , J. van Essen Anthonie
Published: October 2002

Children/fetuses born with a congenital anomaly are recorded in a local registry of congenital anomalies in the Northern Netherlands. Parents of these children/fetuses often have questions about cause, prognosis, and recurrence risk. Referral to a genetic clinic is one way to obtain information concerning these questions. We were interested in determining to what extent parents were referred for genetic counseling, and investigated the non‐referred cases for the estimated need for referral. Furthermore, we measured whether referral rates had improved following the study carried out by Cornel et al. [1992] for the same region. We evaluated data on couples referred or not referred for 2,964 registered children/fetuses during the birth years 1992–1997. The parents of 528 cases (18%) had been referred for genetic counseling. Investigation of the 2,436 non‐referred cases showed a high number (1287/53%) of cases with a supposedly “low need for referral.” If we consider the remaining 1,149 cases with a moderate or high need for referral to the genetic clinic, the ideal uptake rate is 57% (1149 ± 528 = 1677 cases) instead of the previously mentioned 18% (528 cases). We concluded that nearly four out of 10 parents of children/fetuses with a congenital anomaly who were considered suitable for referral to the genetic clinic did not make use of this option. Despite increased familiarity with genetics over the years among the community in general and health‐care professionals in particular, the EUROCAT registry does not show an improvement in the uptake rate of cases registered with the genetic clinic.
Some chondrodysplasias with short limbs: Molecular perspectives
Authors: Cohen M. Michael
Published: October 2002

A table of molecularly defined chondrodysplasias with short limbs is provided. Several are discussed in detail, including osteogenesis imperfecta and type I collagen mutations, Jansen metaphyseal chondrodysplasia and parathyroid hormone/parathyroid hormone‐related protein receptor mutation, and chondrodysplasias caused by fibroblast growth factor receptor 3 mutations. The latter group includes achondroplasia, hypochondroplasia, thanatophoric dysplasia (types 1 and 2), San Diego platyspondylic dysplasia, and SADDAN. © 2002 Wiley‐Liss, Inc.
The Maka femur and its bearing on the antiquity of human walking: Applying contemporary concepts of morphogenesis to the human fossil record
Authors: Lovejoy C. Owen , Meindl Richard S. , Ohman James C. , Heiple Kingsbury G. , White Tim D.
Published: October 2002

MAK‐VP‐1/1, a proximal femur recovered from the Maka Sands (ca. 3.4 mya) of the Middle Awash, Ethiopia, and attributed to Australopithecus afarensis, is described in detail. It represents the oldest skeletal evidence of locomotion in this species, and is analyzed from a morphogenetic perspective. X‐ray, CT, and metric data are evaluated, using a variety of methods including discriminant function. The specimen indicates that the hip joint of A. afarensis was remarkably like that of modern humans, and that the dramatic muscle allocation shifts which distinguish living humans and African apes were already present in a highly derived form in this species. Its anatomy provides no indication of any form of locomotion save habitual terrestrial bipedality, which very probably differed only trivially from that of modern humans. Am J Phys Anthropol 119:97–133, 2002. © 2002 Wiley‐Liss, Inc.
Valproic acid treatment results in increased accumulation of prion proteins
Authors: Shaked Gideon M. , Engelstein Roni , Avraham Inbal , Rosenmann Hannah , Gabizon Ruth
Published: October 2002

PrPSc, the only identified component of the prion, is an aberrant isoform of PrPC, a glycoprotein of unknown function. In this study, it was shown that valproic acid, a widely used antiepileptic drug, can cause an increase of several orders of magnitude in the accumulation of PrPC in normal neuroblastoma cells (N2a), and of both PrP isoforms in scrapie infected neuroblastoma cells (ScN2a). Although preliminary results indicate that valproic acid administration to hamsters inoculated with prions had no significant effect on disease incubation time, it is suggested that administration of valproic acid to humans at risk of developing Creutzfeldt‐Jakob disease should be evaluated with caution.
Preserved visual function in a case of occipitoparietal microgyria
Authors: Zesiger Pascal , Kiper Daniel , Maeder Philippe , Deonna Thierry , Innocenti Giorgio M.
Published: October 2002

A 20‐year‐old man with bilateral parasagittal occipitoparietal polymicrogyria and epilepsy, from whom normal functional magnetic resonance imaging and electroencephalogram responses to visual stimuli were obtained, was found to have no visual perceptual deficits. This suggests that microgyric cortex can perform normal visual functions, despite its gross structural abnormalities.
Effect of water and hydrogen sulfide in zinc dimethyldithiocarbamate accelerated sulfur vulcanization
Authors: Shumane M. , Gradwell M. H. S. , McGill W. J.
Published: October 2002

Rubber and the model compound 2,3‐dimethyl‐2‐butene (TME) are vulcanized with zinc dimethyldithiocarbamate [Zn2(dmtc)4] accelerated sulfur formulations. When heated in dry nitrogen, Zn2(dmtc)4 is stable at vulcanization temperatures. However, it shows a mass increase when heated in moist nitrogen, indicating strong coordination with water; in a nitrogen/H2S atmosphere rapid degradation to dimethyldithiocarbamic acid (Hdmtc) and ZnS occurs. Model compound studies show that crosslinked sulfides are essentially bis(alkenyl) and confirm the absence of accelerator terminated pendant groups in the vulcanizates, while the ease with which rubber vulcanizates crystallize on cooling in a density column also suggests that pendant groups are largely absent. However, the rates of crystallization, measured as the time for the crystallization process to go to 50% completion, are slower in lightly crosslinked gels than in peroxide cures of similar crosslink density, particularly in the vulcanizates cured in a vacuum; this is interpreted as an indication that some residual pendant groups are present in Zn2(dmtc)4 vulcanizates. Water promotes the rate of crosslink formation in both rubber and TME systems, and it is suggested that the strong coordination of water with zinc in Zn2(dmtc)4 promotes its reactivity. The H2S liberated in the vulcanization process promotes decomposition of Zn2(dmtc)4 to Hdmtc, and this reaction makes an important contribution to the amount of Hdmtc that is formed in situ. The importance of Hdmtc as an accelerator and its role in providing alternative routes to crosslink formation in Zn2(dmtc)4 accelerated sulfur vulcanization are discussed. It is suggested that water, which is liberated when Hdmtc reacts with ZnO to form Zn2(dmtc)4, activates newly formed Zn2(dmtc)4 molecules; and this accounts for the beneficial influence of ZnO in Zn2(dmtc)4 formulations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1516–1531, 2002
On the thermal degradation of poly(styrene sulfone)s. V. Thermogravimetric kinetic simulation of polyacrylamide pyrolysis
Authors: Yang Mu‐Hoe
Published: October 2002

The kinetics involved in the thermal degradation of polyacrylamide under nitrogen atmosphere were studied by using consecutive reactions of a kinetic model to dynamic thermogravimetric data. The model proposed correlates the thermograms obtained at thermogravimetric and differential thermogravimetric data with the same set of kinetic parameters. The first stage of polyacrylamide decomposition, where the deamonation of the polyacrylamide and the dehydration of acrylamide units and the formation of a proportion of unvolatile imides and nitrile and aliphatic organic compounds can be fitted satisfactorily when in a model based on a single reaction. The second stage, corresponding to the breakdown of the imides formed and the polymer backbone, also can be correctly represented by a model based on a single reaction. In this article, a discussion about the applicability of the model is presented and the results obtained are compared to those obtained by Flynns's and Friedman's analytical methods, respectively. The maximum decomposition temperature, shape index for dynamic condition and lifetime, and degree of decomposition for isothermal condition of thermal behavior of polyacrylamide are predicted via mathematical simulation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1540–1548, 2002
Synthesis and light‐emitting properties of new poly(p‐phenylenevinylene) derivatives containing oxadiazole moiety
Authors: Wang Shu , Hua Wenting , Chen Xiaohong , Hou Yanbing
Published: October 2002

Two new poly(p‐phenylenevinylene) (PPV) derivatives containing the oxadiazole moiety (OXA–PPV1 and OXA–PPV2) were synthesized by the Wittig condensation polymerization reaction and their thermal and light‐emitting properties were investigated. The single‐layer and triple‐layer electroluminescent (EL) devices with configurations of ITO/OXA–PPV1/Al and ITO/OXA–PPV1/OXD/Alq3/Al were fabricated. They both exhibited blue emission at 460 nm. For comparison, the PPV derivative containing the oxadiazole moiety only in the side chains (OXA–PPV2) was also synthesized. Both single‐layer and triple‐layer EL devices with OXA–PPV2 as the emissive layer emitted green‐light at 560 nm. The turn‐on voltages of the triple‐layer device was 11 V for OXA–PPV1 and 8 V for OXA–PPV2. The triple‐layer EL devices showed much better performance than that of the single‐layer devices. The spectra indicated that energy or electron transfer occurred from the side‐chain oxadiazole to the main‐chain styrene unit. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2424–2428, 2002
Modeling of “living” free‐radical polymerization processes. I. Batch, semibatch, and continuous tank reactors
Authors: Zhang Min , Ray W. Harmon
Published: October 2002

A comprehensive mathematical model is developed for “living” free‐radical polymerization carried out in tank reactors and provides a tool for the study of process development and design issues. The model is validated using experimental data for nitroxide‐mediated styrene polymerization and atom transfer radical copolymerization of styrene and n‐butyl acrylate. Simulations show that the presence of reversible capping reactions between growing and dormant polymer chains should boost initiation efficiency when using free nitroxide in conjunction with conventional initiator and also increase the effectiveness of thermal initiation. A study shows the effects of the value of the capping equilibrium constant and capping reaction rate constants for both nitroxide‐mediated styrene polymerization (using alkoxyamine as polymer chain seeds) and atom transfer radical polymerization of n‐butyl acrylate (using methyl 2‐bromopropionate as chain extension seeds). Also the effect of introducing additional conventional initiator into atom transfer radical polymerization of n‐butyl acrylate is studied. It is found that the characteristics of long chain growth are determined by the fast exchange of radicals between growing and dormant polymer chains. Polymerization results in batch, semibatch, and a series of continuous tank reactors are analyzed. The simulations also show that a semibatch reactor is most flexible for the preparation of polymers with controlled architecture. For continuous tank reactors, the residence time distribution has a significant effect on the development of chain architecture. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1630–1662, 2002
Adsorption studies of fatty acids on montmorillonite‐based filler clay
Authors: Khalil Hanaa S. A. , Abdelhakim A. A.
Published: October 2002

Surface coating of montmorillonite‐based filler clay with stearic and oleic (9‐octadecenoic acid) acids was presented. Sedimentation measurements showed that the sedimentation rate and the sediment volume decreased sharply with the adsorbed amount of the acid up to a certain concentration and then became constant. The chemical analysis showed that the adsorbed amount of either acid by montmorillonite clay increased with the equilibrium concentration of the acid in the solution. The adsorption isotherm indicated the formation of a monolayer on the clay surface at a lower concentration of the acids followed by formation of multilayers of the acids on the clay surfaces at higher concentrations. XRD analysis indicated no intercalation of either acid in the lamella of the clay. We concluded the possibility of surface coating of montmorillonite clay with a monolayer of fatty acids that render the clay organophilic. The adsorption of either acid improved the dispersibility of the clay particles in organic or polymeric media. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2574–2580, 2002
Gas‐transport properties through cation‐exchanged sulfonated polysulfone membranes
Authors: Bum Park Ho , Yong Nam Sang , Won Rhim Ji , Min Lee Jung , Kim Sun E. , Ran Kim Jung , Moo Lee Young
Published: October 2002

Sulfonated polysulfone (SPS) membranes were prepared, and the gas‐transport properties of the resulting ionic polymers were examined. Gas‐transport measurements were made on dense films of these polymers with a continuous flow technique. The sulfonation of polysulfone and the metal‐cation exchange of SPS were confirmed with Fourier transform infrared spectroscopy and electron spectroscopy for chemical analysis. The SPS membranes exchanged with the monovalent metal ions showed higher permeability coefficients than the SPS membranes exchanged with the multivalent metal ions, whereas the selectivities of all the metal‐cation‐exchanged sulfonated polysulfone (MeSPS) membranes for O2/N2 and CO2/N2 gas pairs were higher than those of SPS membranes. When the MeSPS membranes with metal cations of similar ionic radii were compared, the ideal selectivities of O2/N2 and CO2/N2 through MeSPS with divalent cations were higher than those through MeSPS with monovalent cations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2611–2617, 2002
A convenient procedure for preparation of a novel allylphenoxytriazine monomer and the properties of its copolymer with bismaleimide (BMI)
Authors: Fang Qiang , Jiang Biao , Yu Yi‐Hua , Zhang Xiao‐Bing , Jiang Lu‐Xia
Published: October 2002

A novel allylphenoxytriazine monomer, 2,4‐di (2‐allylphenoxy)‐6‐N,N‐dimethylamino‐1,3,5‐triazine (DAPDMT) was prepared in one‐pot by reacting cyanuric chloride with 2‐allylphenol at first, and then by directly treating the adduct with N,N‐dimethylamine without separation. The monomer was used to modify a popular commercial bismaleimide (BMI) resin, 4,4′‐bismaleimidodiphenyl methane (BMDPM), and the results showed that the monomer could effectively improve mechanical properties of BMDPM resin without greatly decreasing heat resistance of the resin. The better results were obtained when the molar ratio of DAPDMT/BMDPM was 1 : 4. Because of more reactive sites in the monomer, the potential uses of the monomer were predicted. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2279–2284, 2002
Improvement in the water‐absorbing properties of superabsorbent polymers (acrylic acid‐co‐acrylamide) in supercritical CO2
Authors: Ma Li , Zhang Le , Yang Ji‐Chu , Xie Xu‐Ming
Published: October 2002

Superabsorbent resins prepared by ultraviolet radiation‐inducing polymerization techniques with acrylic acid/acrylamide were treated with supercritical carbon dioxide (SC‐CO2). The water‐absorbing properties of the treated resins were greatly improved. The water‐absorbing properties of resins treated with SC‐CO2 in the pressure range of 10–35 MPa and the temperature range of 40–60°C were studied. The effects of the treatment time and depressurizing speed of CO2 after treatment were also examined. Obviously, different results were found for particles of different sizes. Smaller particles were more efficient under the same treatment conditions. Samples were tested with differential scanning calorimetry. The results showed that the plasticizing effect of CO2 reduced the glass‐transition temperature of the polymer, and it was proposed that the plasticization effect might have led to polymer chain redistribution and better flexibility. Minor changes in the surface morphology of the particles were observed with scanning electron microscopy. The extraction of the unpolymerized monomers by SC‐CO2 was also studied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2272–2278, 2002
Effects of the actual diameters and diameter ratios of barrels and dies on the elastic swell and entrance pressure drop of natural rubber in capillary die flow
Authors: Sombatsompop N. , Dangtangee R.
Published: October 2002

The effects of the actual diameters and diameter ratios of barrels and dies on the elastic swell and entrance pressure drop of natural rubber compounds in an extrusion capillary rheometer were investigated. Either the barrel diameter or the die diameter was altered so that different barrel‐diameter/die‐diameter (DB/DD) ratios were obtained, both the barrel and die diameters also being varied simultaneously. The extrudate swell and entrance pressure drop were dependent not only on DB/DD but also on the actual diameters used. For fixed DB/DD ratios, the change in the extrudate swell was linearly influenced by the entrance pressure drop at low actual barrel and die diameters (DB/DD = 20/4–30/7 mm/mm) but was associated with a change in the material viscosity at high barrel and die diameters (DB/DD = 35/7–40/8 mm/mm). When the die diameter was fixed, the relationship between the entrance pressure drop and the extrudate swell was linear up to a certain value of the barrel diameter greater than 30 mm. Beyond this critical barrel value, the relationship became nonlinear and associated with the shearing stress generated by the formation of semipluglike flow patterns and the residence time of the material. For a constant barrel diameter, the smaller the die diameter was, the greater the extrudate swell was because of the increases in the extensional deformation and wall shear rate coupled with a reduction in the material residence time. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1762–1772, 2002
Functionalized multiarm poly(ϵ‐caprolactone)s: Synthesis, structure analysis, and network formation
Authors: Lang Meidong , Chu Chih‐Chang
Published: October 2002

The purpose of this research was to synthesize and characterize a novel class of four‐arm, star‐shape biodegradable polymers having double‐bond functionality as a precursor for free‐radical polymerization, with unsaturated monomers or macromers or photocrosslinking for network formation. The synthesis involved two basic steps. First, hydroxyl‐functionalized four‐arm poly(ϵ‐caprolactone)s (PPCL‐OH) were synthesized by the ring‐opening polymerization of ϵ‐caprolactone in the presence of pentaerythritol and stannous octoate. Second, double‐bond–functionalized four‐arm poly(ϵ‐caprolactone)s (PPCL‐Ma) were synthesized by reacting PPCL‐OH with maleic anhydride in the melt at 130°C. Quantitative conversion of hydroxyl functionality in PPCL‐OH to double‐bond functionality was achieved for low molecular weight PPCL‐OH. Both the PPCL‐OH and the PPCL‐Ma were characterized by FTIR, 1H‐NMR, 13C‐NMR, SEC, and DSC. The capability of the double‐bond–functionalized four‐arm poly(ϵ‐caprolactone)s (PPCL‐Ma) to form network structures was preliminarily shown by photocrosslinking PPCL‐Ma. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2296–2306, 2002
Preparation and properties of waterborne polyurethane–urea anionomers. I. The influence of the degree of neutralization and counterion
Authors: Yang Jung‐Eun , Kong Ju‐Shik , Park Sang‐Woo , Lee Dong‐Jin , Kim Han‐Do
Published: October 2002

Two series of waterborne polyurethane–urea anionomers were prepared by a polyaddition reaction with isophorone diisocyanate, poly(tetramethylene oxide) glycol (weight‐average molecular weight = 1000), dimethylol propionic acid (DMPA), and ethylene diamine as chain extenders. Triethylamine (TEA) or 28:1 mol/mol ammonium hydroxide (NH4OH)/cupric hydroxide [Cu(OH)2] was used as a neutralization agent [NH(C2H5) or NH/Cu2+ counterion] for the pendant COOH group of DMPA. The effects of the degree of neutralization and counterion on the particle size of the dispersions, the conductivity, and the antibacterial and mechanical properties of polyurethane–urea anionomer films were investigated. The particle sizes of the two sample series dispersions decreased with an increasing degree of neutralization. Aqueous dispersions of polyurethane–urea anionomers with particle sizes of 30–120 nm were stable for about 3 months. By infrared spectroscopy, it was found that TEA‐based samples (T series) had higher fractions of hydrogen‐bonded carbonyl groups in the ordered region than NH4OH/Cu(OH)2‐based samples (S series). However, the fractions of hydrogen‐bonded carbonyl groups in the disordered region of the S‐series samples were higher than those of the T‐series samples. The conductivities of the S‐series film samples were higher than those of the T‐series samples. However, the T‐series film samples commonly had higher tensile strengths and initial moduli than the S‐series samples. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2375–2383, 2002
Antiarthritic activity of an orally active C5a receptor antagonist against antigen‐induced monarticular arthritis in the rat
Authors: Woodruff Trent M. , Strachan Anna J. , Dryburgh Nathan , Shiels Ian A. , Reid Robert C. , Fairlie David P. , Taylor Stephen M.
Published: October 2002

Objective

To determine if the new, orally active C5a receptor antagonist, the cyclic peptide AcF‐[OPdChaWR], reduces the severity of pathology in a rat model of immune‐mediated monarticular arthritis.

Methods

Arthritis was induced in the right knee of previously sensitized rats by the intraarticular injection of methylated bovine serum albumin. Rats were examined for either 14 days or 28 days, or for 49 days following a second antigen challenge at 28 days. The C5a antagonist (1 or 3 mg/kg/day) and/or ibuprofen (30 mg/kg/day) were administered orally on a daily basis either before or after arthritis induction.

Results

Rats receiving AcF‐[OPdChaWR] had significant reductions in right knee swelling, gait disturbance, lavaged joint cell numbers, and right knee histopathology, as well as in serum levels of tumor necrosis factor α (TNFα) and intraarticular levels of interleukin‐6 and TNFα on day 14. In the 14‐ and 28‐day studies, ibuprofen resulted in a similar reduction in gait abnormalities and intraarticular inflammatory cells compared with the C5a antagonist, but was less effective in reducing knee swelling over the course of the study and had no effect on knee histopathology. Combination therapy with AcF‐[OPdChaWR] and ibuprofen resulted in no greater efficacy than with the C5a antagonist alone. Rats injected twice with the antigen in the 49‐day study displayed the most severe histopathology and this, as well as knee swelling and gait abnormalities, was significantly reduced by repeated treatment with the C5a antagonist.

Conclusion

An agent that inhibits the action of C5a in this model significantly reduced joint pathology, while ibuprofen was not effective. C5a antagonists could therefore have broader therapeutic benefits than nonsteroidal antiinflammatory drugs as antiarthritic agents for rheumatoid arthritis.
Contribution of hospital characteristics to the volume–outcome relationship: Dislocation and infection following total hip replacement surgery
Authors: Solomon Daniel H. , Losina Elena , Baron John A. , Fossel Anne H. , Guadagnoli Edward , Lingard Elizabeth A. , Miner Andrew , Phillips Charlotte B. , Katz Jeffrey N.
Published: October 2002

Objective

Mortality and complication rates after total hip replacement (THR) are inversely associated with the volume of THRs performed at hospitals and by individual surgeons. It is not clear, however, why a higher volume of such procedures is associated with better outcomes. We evaluated the contribution of hospital structural characteristics to the volume–outcome relationship in THR by examining the rates and predictors of postoperative complications.

Methods

We analyzed data pertaining to 5,211 Medicare patients who underwent primary THR in 1995 or 1996 at 167 hospitals in Colorado, Pennsylvania, and Ohio. Data were derived from several sources, including Medicare Part A and Part B claims, the American Board of Medical Specialties, a hospital survey regarding institution‐specific characteristics and structural aspects of the care setting, and the American Hospital Association 1995 Annual Survey. Multivariate models were constructed to determine whether hospital structure or surgeon‐associated factors may underlie the relationship between volume of THRs and the occurrence of perioperative orthopedic adverse events, defined as deep wound infection or hip dislocation within 90 days of surgery.

Results

Of the patients studied, 2.6% experienced an orthopedic adverse event after THR. Sixty‐nine percent fewer events occurred in hospitals where >100 THRs in Medicare patients were performed annually, compared with hospitals where ≤25 THRs were performed. In univariate analyses, several hospital‐level factors were associated with a reduced (∼50%) risk of adverse events, including private (versus public) ownership, membership in the Council of Teaching Hospitals, presence of any residency training program, availability of a dedicated orthopedic nursing unit, and existence of operating rooms with laminar flow exhaust systems. However, the only hospital‐level factor associated with adverse events in multivariate models was the use of laminar flow exhaust systems. When surgeon volume was added to the models, it was the strongest predictor of adverse events, with hospital volume and hospital‐level factors having no appreciable association with adverse events.

Conclusion

Hospital‐level factors were not independent predictors of the association between hospital volume and orthopedic adverse events. The volume of THRs performed by individual surgeons is the most important determinant of orthopedic complications and should be considered in efforts to improve THR outcomes.
HLA–DRB1 genotype associations in 793 white patients from a rheumatoid arthritis inception cohort: Frequency, severity, and treatment bias
Authors: Fries James F. , Wolfe Frederick , Apple Raymond , Erlich Henry , Bugawan Teodorica , Holmes Tyson , Bruce Bonnie
Published: October 2002

Objective

The HLA–DRB1 “shared epitope” (SE) genotypes are associated with rheumatoid arthritis (RA), but it remains controversial whether the association is with incidence, severity, or both, whether there are associations in seronegative patients, and whether different DRB1 alleles that contain the SE have similar effects on RA susceptibility and/or severity. The present study was undertaken to study these issues in a large cohort of patients with RA.

Methods

White patients with RA of <6 months' duration (n = 793) were enrolled in an inception cohort. HLA–DRB1 typing was performed, and patients were categorized into 21 DRB1 genotype groups. The disability index of the Health Assessment Questionnaire was the primary outcome measure.

Results

DRB1 associations in seronegative RA patients closely resembled those in controls. Of seropositive patients, 21% had 2 copies of the epitope, 52% had 1 copy, and 27% had none. However, not all genotypes with 1 copy were associated with increased susceptibility; for example, frequencies of DRB1*0404/X and *01/X did not differ from those in controls. Absolute differences between seropositive RA patients and controls were greatest for DRB1*0401 homozygosity (3.8% versus 0.8%, respectively) and *0401/0404 heterozygosity (4.7% versus 1.0%). DRB1*0404 was increased in frequency in seropositive RA but, unlike *0401, an increased frequency was seen only with 2 epitope copies. The relatively rare DRB1*10 had an unexpected association with seropositive RA, being present in 1.7% of seropositive RA patients and 0.7% of controls, and also showed a trend toward association with greater disease severity. The presence of 2 epitope copies was associated with increased frequency of seropositivity and younger age at disease onset, not with disease severity. Treatment indication bias was substantial and may have accounted for some of these effects. HLA–DRB1*0401/0404 was found much more frequently in men and in patients with a lower age at disease onset, and there was a trend toward a higher frequency of *0404/0401 in women.

Conclusion

This large inception cohort study confirms previously identified major associations and provides additional insights. Only one dominant association was found: *0401, which differs from other SE alleles in a single Lys‐for‐Arg substitution. The association of the rare DRB1*10 allele has not previously been postulated. Sex associations were confirmed. Associations with seronegative RA were not seen. Not all genotypes containing an SE copy showed increased susceptibility to RA. The association of SE genotypes found in this study related to disease susceptibility rather than severity.
Inhibiting viral proteases: Challenges and opportunities
Authors: Bianchi Elisabetta , Pessi Antonello
Published: October 2002

Inhibitor design against viral targets must take into account the peculiar characteristics of viral biology—in particular, the plasticity of their replicative machinery. This includes maturational cleavage of the polyprotein, which is mediated by virally encoded proteases. Designing against a movable target is particularly challenging, but at the same time it offers new opportunities. Here we describe our experience with the NS3/4A (NS: nonstructural) serine protease of human hepatitis C virus (HCV). By extensive use of combinatorial peptide libraries, various inhibitor types were generated, including product inhibitors, serine traps, P–P′ inhibitors, and prime side inhibitors. The latter represent a first case for a serine protease. A key finding, derived from structural studies utilizing these inhibitors, was that NS3 is an induced‐fit protease, requiring both the NS4A cofactor protein and the substrate to fully activate its catalytic machinery. In the absence of cofactor and/or substrate, NS3 exists in solution as a large conformational ensemble, which can be matched by a correspondingly large set of peptide inhibitors, each one stabilizing a given conformer. In the perspective of inhibiting viral proteases in general, we suggest that combinatorial ligand ensembles may be a powerful tool, to contrast the adaptive potential of the viral quasispecies. © 2002 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 66: 101–114, 2002
Aggregation kinetics of well and poorly differentiated human prostate cancer cells
Authors: Enmon Richard M. , O'Connor Kim C. , Song Hong , Lacks Daniel J. , Schwartz Daniel K.
Published: October 2002

Aggregation of attachment‐dependent animal cells represents a series of motility, collision, and adhesion events applicable to such diverse fields as tissue engineering, bioseparations, and drug testing. Aggregation of human prostate cancer cells in liquid‐overlay culture was modeled using Smoluchowski's collision theory. Using well (LNCaP) and poorly differentiated (DU 145 and PC 3) cell lines, the biological relevance of the model was assessed by comparing aggregation rates with diffusive and adhesive properties. Diffusion coefficients ranged from 5 to 90 μm2/min for single LNCaP and PC 3 cells, respectively. Similar diffusivities were predicted by the persistent random walk model and Einstein relation, indicating random motion. LNCaP cells were the most adhesive in our study with reduced cell shedding, 100% adhesion probability, and enhanced expression of E‐cadherin. There was an increase in DU 145 cells staining positive for E‐cadherin from nearly 20% of single cells to uniform staining across the surface of all aggregates; under 30% of PC 3 aggregates stained positive. Aggregation rates were more consistent with adhesive properties than with motilities, suggesting that aggregation in our study was reaction‐controlled. Relative to other assays employed here, aggregation rates were more sensitive to phenotypic differences in cell lines and described size‐dependent changes in aggregation at a finer resolution. In particular, model results suggest similar aggregation rates for two‐dimensional DU 145 and PC 3 aggregates and upwards of 4‐fold higher rates for larger three‐dimensional DU 145 spheroids, consistent with expression of E‐cadherin. The kinetic model has application to spheroid production, to cell flocculation and as an adhesion assay. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 580–588, 2002.