bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synergistic effects of carbon fillers on tensile and impact properties in nylon 6,6 and polycarbonate based resins
Authors: Konell Jeremiah P. , King Julia A. , Miskioglu Ibrahim 
Published: April 2004

AbstractElectrically and thermally conductive resins can be produced by adding conductive fillers to insulating polymers. Mechanical properties such as tensile modulus, ultimate tensile strength, strain at ultimate tensile strength, and notched Izod impact strength are also important and cannot be ignored. This research focused on performing compounding runs followed by injection molding and tensile and impact property testing of carbon filled nylon 6,6 and polycarbonate based resins. The three carbon fillers investigated included an electrically conductive carbon black, synthetic graphite particles, and a milled pitch based carbon fiber. For each polymer, resins were produced and tested that contained varying amounts of these single carbon fillers. In addition, combinations of fillers were investigated by conducting a full 23 factorial design and a complete replicate in each polymer. The objective of this paper was to determine the effects and interactions of each filler on the tensile and impact properties. The results showed that, in many cases, combining two and three different fillers caused a statistically significant effect at the 95% confidence level. Polym. Compos. 25:172–185, 2004. © 2004 Society of Plastics Engineers.
Effect of composition on the fracture toughness and flexural strength of syntactic foams
Authors: Benderly D. , Rezek Y. , Zafran J. , Gorni D. 
Published: April 2004

AbstractSyntactic foams are strong, lightweight materials that can be useful in marine and aeronautical applications. However, these materials are brittle, which can limit their usefulness. The fracture toughness of several epoxy based syntactic foams, as affected by foam composition, was evaluated. The parameters of interest were the curing agent type (anhydride and amine) and elastomer type and level. For the anhydride curing agents studied, the addition of elastomer improved the fracture toughness, and no reduction in flexural strength was observed upon elastomer addition. Examination of the fracture surface showed that the failure mechanism varied with foam composition, from crack propagation around the microballoon filler to crack propagation through the filler, possibly explaining the strength results. For a syntactic foam cured with a cycloaliphatic amine curing agent, the addition of elastomer did not significantly affect the fracture toughness. Examination of the fracture surface showed that the failure mechanism for the syntactic foam compositions with and without added elastomer was crack propagation through the matrix rather than through the microballoon filler. Polym. Compos. 25:229–236, 2004. © 2004 Society of Plastics Engineers.
Mechanism of preparing monodispersed poly(acrylamide/methacrylic acid) microspheres in ethanol. II
Authors: Ni Henmei , Kawaguchi Haruma 
Published: April 2004

AbstractWe previously established a new mechanism of monodispersed poly(acrylamide/methacrylic acid) (PAAm/MAA) microspheres on the basis that the minimonomer droplets of AAm/MAA complexes were formed in ethanol at a polymerization temperature of 60 °C prior to the polymerization. Here, the effects of various factors such as the types and amount of initiators and crosslinking agents on the average diameters and morphologies of PAAm/MAA microspheres were qualitatively discussed on the basis of the new mechanism. The partition of reagents between the minimonomer droplets and the continuous medium was particularly emphasized in discussion because the formation of microspheres occurred in the minimonomer droplets. The new mechanism suggested that the size (number) and morphologies of the microspheres as well as the polymerization kinetics were consequently dependent on the properties and amount of initiators, crosslinking agents, and other monomers. It successfully explained the experimental phenomenon observed thus far in precipitation or dispersion polymerizations that the average diameter of microspheres is increased with the increase of the concentration of initiators, which contradicted the prediction of conventional mechanisms. As an example, the initiator dimethyl 2,2′‐azobisisobutyrate (DMAIB) was dominantly partitioned in ethanol. Thus, the diameter of the PAAm/MAA microspheres was decreased with the increase of the concentration of DMAIB because the formation of microspheres depended on the adsorption of free radicals to the minimonomer droplets. However, the initiator 4,4′‐azobis‐4‐cyanovaleric acid was dominantly partitioned within the minimonomer droplets, thereby increasing the diameter of the microspheres as the concentration of initiator was increased because of the lower efficiency of free radicals. Relative to the initiators, the crosslinking agents showed inverse effects on the diameter and morphology of the microspheres according to the different partitions. The monomer was transferred by the incorporation of minimonomer droplets with growing microspheres. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2833–2844, 2004
Release of theophylline and aminophylline from acrylic acid/n‐alkyl methacrylate hydrogels
Authors: Katime Issa , Novoa Rosa , Díaz de Apodaca E. , Rodríguez E. 
Published: April 2004

AbstractThe swelling capacity and release rate of two homologous drugs, theophylline and aminophylline, from acrylic acid/n‐alkyl methacrylate hydrogels have been studied. The maximum equilibrium swelling increases as the molar fraction of acrylic acid or the chain length of the methacrylate in the hydrogels increases. Water diffusion to the hydrogels is non‐Fickian. Both drugs are released from the fully swollen hydrogels according to Fick's law. However, the drug release from xerogels deviates from Fick's law, especially for aminophylline. As expected because of its larger size, aminophylline diffuses more slowly than theophylline under similar experimental conditions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2756–2765, 2004
Synthesis and bulk assembly behavior of linear–dendritic rod diblock copolymers
Authors: Santini Catherine M. B. , Johnson Mark A. , Boedicker James Q. , Alan Hatton T. , Hammond Paula T. 
Published: April 2004

AbstractDendritic rod structures can be formed via the branching of dendritic elements from a primary polymer backbone; such systems present an opportunity to create nanoscale material structures with highly functional exterior regions. In this work, we report for the first time the synthesis of a hybrid diblock copolymer possessing a linear–dendritic rod architecture. These block copolymers consist of a linear poly(ethylene oxide)–poly(ethylene imine) diblock copolymer around which poly(amido amine) branches have been divergently synthesized from the poly(ethylene imine) block. The dendritic branches are terminated with amine or ester groups for the full generations and half‐generations, respectively; however, the methyl ester terminal groups can also be readily converted into alkyl groups of various lengths, and this allows us to tune the hydrophilic/hydrophobic nature of the dendritic block and, therefore, the amphiphilic properties of the diblock copolymer and its tendencies toward microphase separation. The block copolymers exhibit semicrystallinity due to the presence of the poly(ethylene oxide) block; however, as the polymer fraction consisting of poly(ethylene oxide) decreases, the overall crystallinity also decreases, and it approaches zero at generation 2.0 and higher. The unfunctionalized block copolymers show weak phase segregation in transmission electron microscopy and differential scanning calorimetry at all generations. The addition of n‐alkyl chains increases phase segregation, particularly at high alkyl lengths. The generation 3.5 polymer with n‐dodecyl alkyl substitution has a rodlike or wormlike morphology consisting of domains of 4.1 nm, equivalent to the estimated cross section of the individual polymer chains. In this case, the nanometer scale of the polymer chains can be directly observed with transmission electron microscopy. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2784–2814, 2004
A method for simultaneous alignment of multiple protein structures
Authors: Shatsky Maxim , Nussinov Ruth , Wolfson Haim J. 
Published: April 2004

AbstractHere, we present MultiProt, a fully automated highly efficient technique to detect multiple structural alignments of protein structures. MultiProt finds the common geometrical cores between input molecules. To date, most methods for multiple alignment start from the pairwise alignment solutions. This may lead to a small overall alignment. In contrast, our method derives multiple alignments from simultaneous superpositions of input molecules. Further, our method does not require that all input molecules participate in the alignment. Actually, it efficiently detects high scoring partial multiple alignments for all possible number of molecules in the input. To demonstrate the power of MultiProt, we provide a number of case studies. First, we demonstrate known multiple alignments of protein structures to illustrate the performance of MultiProt. Next, we present various biological applications. These include: (1) a partial alignment of hinge‐bent domains; (2) identification of functional groups of G‐proteins; (3) analysis of binding sites; and (4) protein‐protein interface alignment. Some applications preserve the sequence order of the residues in the alignment, whereas others are order‐independent. It is their residue sequence order‐independence that allows application of MultiProt to derive multiple alignments of binding sites and of protein‐protein interfaces, making MultiProt an extremely useful structural tool. Proteins 2004;55:000–000. © 2004 Wiley‐Liss, Inc.
DPANN: Improved sequence to structure alignments following fold recognition
Authors: Reinhardt Astrid , Eisenberg David 
Published: April 2004

AbstractIn fold recognition (FR) a protein sequence of unknown structure is assigned to the closest known three‐dimensional (3D) fold. Although FR programs can often identify among all possible folds the one a sequence adopts, they frequently fail to align the sequence to the equivalent residue positions in that fold. Such failures frustrate the next step in structure prediction, protein model building. Hence it is desirable to improve the quality of the alignments between the sequence and the identified structure. We have used artificial neural networks (ANN) to derive a substitution matrix to create alignments between a protein sequence and a protein structure through dynamic programming (DPANN: Dynamic Programming meets Artificial Neural Networks). The matrix is based on the amino acid type and the secondary structure state of each residue. In a database of protein pairs that have the same fold but lack sequences‐similarity, DPANN aligns over 30% of all sequences to the paired structure, resembling closely the structural superposition of the pair. In over half of these cases the DPANN alignment is close to the structural superposition, although the initial alignment from the step of fold recognition is not close. Conversely, the alignment created during fold recognition outperforms DPANN in only 10% of all cases. Thus application of DPANN after fold recognition leads to substantial improvements in alignment accuracy, which in turn provides more useful templates for the modeling of protein structures. In the artificial case of using actual instead of predicted secondary structures for the probe protein, over 50% of the alignments are successful. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Possible involvement of collective domain movement in the catalytic reaction of soluble epoxide hydrolase
Authors: Schiøtt Birgit 
Published: April 2004

AbstractThe hydrolysis of 1S,2S‐trans‐methylstyrene oxide by soluble epoxide hydrolases is studied by a 4‐ns molecular dynamics (MD) simulation. An analysis of the extent of correlated motions in the active site was carried out. Based on the calculated cross correlation coefficients form the covariance matrix, a new correlation parameter, termed the supercorrelation coefficient, is introduced. The supercorrelation coefficient indicates the extent to which two amino acid residues move in a correlated manner with respect to all other residues in the protein. The resulting map of the supercorrelation coefficients was used to identify segments of the protein that may show collective domain movements. Interestingly, an anti‐correlated motion is located across the active site, involving the catalytic triad and the tyrosines. This may suggest that if a link exists between enzyme dynamics and catalysis, it may be through an anti‐correlated collective domain movement that compresses the active site, thus initiating the conversion of E–NAC to E–TS. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Characterisation of natural indigo and shellfish purple by mass spectrometric techniques
Authors: Andreotti Alessia , Bonaduce Ilaria , Colombini Maria Perla , Ribechini Erika 
Published: April 2004

AbstractTwo analytical methods based on mass spectrometry were used in the characterisation of constituents of natural indigo prepared from the leaves of Indigofera tinctoria, and of shellfish purple prepared from the hypobranchial glandular secretions of Murex trunculus, following old recipes. On‐line pyrolysis gas chromatography in the presence of hexamethyldisilazane followed by mass spectrometric analysis (Py‐silylation/GC/MS), and direct exposure mass spectrometry (DE‐MS), were used. Extensive fragmentation of indigoid dyes was obtained by Py‐silylation/GC/MS. The following molecular markers were highlighted, which are useful for identification purposes: 1,2‐dihydro‐3H‐indol‐3‐one for indigoid dyes, 1,3‐dihydro‐2H‐indol‐2‐one for indirubine, and 6‐bromo‐1,2‐dihydro‐3H‐indol‐3‐one for shellfish purple. Using DE‐MS, 6,6′dibromoindigotine, monobromoindigotine and indigotine were identified as the main components, and the presence of tyrindoxyl, one of the dye precursors, was also assessed. Copyright © 2004 John Wiley & Sons, Ltd.
Gas‐phase ligand loss and ligand substitution reactions of platinum(II) complexes of tridentate nitrogen donor ligands
Authors: Wee Sheena , O'Hair Richard A. J. , McFadyen W. David 
Published: April 2004

AbstractThe source of protons associated with the ligand loss channel of HX(n − 1)+ from [PtII(dien)X]n+ (X = Cl, Br and I for n = 1 and X = NC5H5 for n = 2) in the gas phase was investigated by deuterium‐labelling studies. The results of these studies indicate that these protons originate from both the amino groups and the carbon backbone of the dien ligand. In some instances (e.g. X = Br and I), the protons lost from the carbon backbone can be even more abundant than the protons lost from the amino groups. The gas‐phase substitution reactions of coordinatively saturated [PtII(L3)La]2+ complexes (L3 = tpy or dien) were also examined using ion‐molecule reactions. The outcome of the ion‐molecule reactions depends on both the ancillary ligand (L3) as well as the leaving group (La). [PtII(tpy)La]2+ complexes undergo substitution reactions, with a faster rate when La is a good leaving group, while the [PtII(dien)La]2+ complex undergoes a proton transfer reaction. Copyright © 2004 John Wiley & Sons, Ltd.
Second Place—Resident Clinical Science Award 1998: Allergy increases susceptibility to otitis media with effusion in a rat model
Authors: Labadie Robert F. , Jewett Brian S. , Hart Craig F. , Prazma Jiri , Pillsbury Harold C. 
Published: April 2004

To investigate the Possible relationship between allergy and otitis media with effusion (OME), we investigated the hypothesis that allergen presentation to the middle ear causes functional disruption of the eustachian tube predisposing to the development of OME. Thirteen of 19 Brown‐Norway rats were sensitized to ovalbumin, and the remaining 6 served as nonallergic controls. To mimic subclinical exposure to allergen, we transtympanically injected ovalbumin at a dose (0.01 mg) that produced no changes detectable by otologic examination. Next, both allergic and nonallergic rats were exposed to transtympanic injection of either low‐dose (10 μg/mL) or high‐dose (100 μg/mL) lipopolysaccharide to simulate bacterial exposure. The allergic rats were found to have larger middle ear effusions when exposed to high‐dose lipopolysaccharide as compared with the nonallergic controls. This response could be inhibited by diphenhydramine. We conclude that allergen presentation to the middle ear of allergic rats causes eustachian tube dysfunction predisposing to OME.
Hearing preservation in solitary vestibular schwannoma surgery using the retrosigmoid approach
Authors: Moffat David A. , Da Cruz Melville J. , Baguley David M. , Beynon Graham J. , Hardy David G. 
Published: April 2004

The results of 50 cases of vestibular schwannoma surgery with hearing preservation performed by the retrosigmoid approach at Addenbrooke's Hospital, Cambridge, during a 10‐year period are presented. The hearing‐preservation rate, using audiometric criteria set by others as “serviceable hearing” (Wade PJ, House W. Otolaryngol Head Neck Surg 1984;92:1184‐93; Silverstein H, et al. Otolaryngol Head Neck Surg 1986;95:285‐91; Cohen NL, et al. Am J Otol 1993;14:423‐33) was 8% (4 of 50 cases). When the more stringent selection criteria of near‐normal hearing and reporting criteria of socially useful hearing preservation (pure‐tone average < 30 dB/speech discrimination score > 70%) is used, the hearing‐preservation rate is 4.8% (1 of 21 cases). The only preoperative factor that may predict a favorable hearing‐preservation outcome is normal auditory brain stem response morphology (Fisher's exact 2‐tailed test, P < 0.001). The number of suitable candidates for hearing‐preservation surgery are few. Reasonable indications for attempted vestibular schwannoma surgery with hearing preservation are discussed.
Endoscopic‐assisted Adenoidectomy
Authors: Cannon C. Ron , Replogle William H. , Schenk Michael P. 
Published: April 2004

Adenoidectomy is a commonly performed procedure. The advent of endoscopic sinus surgery has Popularized the use of endoscopes. Endoscopic‐assisted adenoidectomy (EAA) is a natural progression of this technology to allow a more complete adenoidectomy. Two hundred thirty‐six patients undergoing adenoidectomy were evaluated with an endoscopic technique. A routine transoral adenoidectomy was performed first. Then a 4‐mm 0° telescope was used transnasally, and residual adenoid tissue was removed from the anterior superior nasopharynx. Invariably, residual adenoid tissue was found after transoral adenoidectomy. The EAA technique is minimally invasive, adds less than 5 minutes to the procedure, and is not associated with excessive bleeding. Readily available telescope and endoscopic equipment is used. The EAA technique is advocated for use as an adjunct to a more complete adenoidectomy.
Schwannoma of the true vocal cord
Authors: Zbäuren Peter , Markwalder Regula 
Published: April 2004

Neurogenic tumors of the larynx are rare. Holinger and Johnston1 reported a single case in their review of 1197 benign tumors of the larynx, and Jones et al2 reported 4 neurogenic tumors in a series including 270 benign tumors of the larynx between 1955 and 1982; Stanley et al3 identified 15 neurogenic tumors of the larynx in the files of the Mayo Clinic, Rochester, MN, between 1907 and 1986. Approximately 130 cases of neurogenic neoplasms had been reported up to 1993.4
A new bacterial disease of jojoba (Simmondsia chinensis) caused by Burkholderia andropogonis
Authors: Cother E. J. , Noble D. , Peters B. J. , Albiston A. , Ash G. J. 
Published: April 2004

A leaf spot of jojoba caused by Burkholderia andropogonis is described for the first time. Symptoms ranged from necrotic flecking with comparatively large watersoaked halos to larger ‘eyespot’ lesions c. 3 mm in diameter with watersoaked halos 1–1·5 mm wide. The necrosis was light tan in colour. Isolates from jojoba displayed variable pathogenicity to other known hosts of B. andropogonis (Dianthus, Cicer, Gypsophila and sorghum), but were not pathogenic, or only weakly so, to sweetcorn, Limonium and Trifolium. Identification was confirmed by cell‐wall fatty acid composition and the bacterium's possession of a single polar flagellum.
Effect of temperature on latent period of septoria leaf blotch on winter wheat under outdoor conditions
Authors: Lovell D. J. , Hunter T. , Powers S. J. , Parker S. R. , Van den Bosch F. 
Published: April 2004

Batches of two winter wheat cultivars (Riband and Apollo) were inoculated with conidia of Mycosphaerella graminicola at weekly intervals over a 2 year period. Following 72 h incubation, plants were placed in ambient temperatures ranging between −7 and 32°C with mean batch temperatures of 2·9–20·2°C. Latent period until the first visible symptoms ranged between 11 and 42 days. The relationship between development of lesions and accumulated thermal time was described using a shifted cumulative gamma distribution model. The model provided good estimates of lesion development with r2 > 0·92 for both cultivars. Base temperatures, below which the pathogen did not develop, were estimated from the model as approximately −2·4°C for the two cultivars. Latent period was estimated as being 250 and 301 degree‐days above the estimated base temperature, when defined as time from inoculation to first lesion and time to 50% of maximal lesions, respectively, for cv. Riband. The values for cv. Apollo were similar, but with estimates of thermal time periods c. 5% higher. The relationship between mean temperature and inverse latent period, expressed as days either to first lesion or to 50% of maximal lesions, was best described by a linear regression with r2 > 0·96 for both cultivars. The opportunity for plants to outgrow disease was reduced when prolonged periods of cold temperature occurred, because the base temperature for growth of the pathogen was less than that for the crop.
Investigating resistance toBarley mild mosaic virus
Authors: McGrann G. R. D. , Adams M. J. 
Published: April 2004

There are claims that at least 11 genes confer resistance in barley (Hordeum vulgaris) to one or more components of the soilborne barley mosaic virus complex but, apart from the immunity conferred by the widely used generym4, little is known about their mode of action. This study used mechanical (sap) and plasmodiophorid vector‐inoculation techniques combined with ELISA, RT‐PCR, symptom development and virus transmission to investigate the response of different genotypes toBarley mild mosaic virus(BaMMV). Barley genotypes were grown at 20 and 12°C to test for temperature sensitivity. Plants with the genesrym3orrym6were fully susceptible to the virus, whereas those with genesrym1,Rym2,rym5orrym11appeared to be immune, as BaMMV was never detected in any tissue type nor was the virus transmitted from them to susceptible genotypes. The remaining genotypes could all be infected to some extent by BaMMV using one or both inoculation methods, and virus could be transmitted from their roots by the plasmodiophorid vectorPolymyxa graminis. Plants with therym7gene had delayed symptoms compared to susceptible controls at 12°C. Plants with therym8gene could be infected by both inoculation methods, but there was no virus in the leaves at 12°C. Plants with therym9gene could be infected only by vector inoculation, and virus remained localized in the roots. Plants with therym10gene appeared susceptible by mechanical inoculation at both temperatures, but after vector inoculation virus moved to leaves only at 20°C. This suggests the operation of translocation resistance in plants with therym8,rym9orrym10genes, which is temperature‐sensitive inrym8andrym10and perhaps tissue‐specific inrym9. No resistance toP. graminiswas observed in any of the genotypes.