bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical copolymerization and characterization of aniline and isoprene in aqueous p‐toluene sulfonic acid solution
Authors: Iroh Jude O. , Rajagopalan Ramakrishnan
Published: August 2002

Uniform and adherent copolymer coating of poly(aniline‐co‐isoprene) was successfully formed on low‐carbon‐steel electrodes by potentiostatic electropolymerization. Electropolymerization was performed by using aqueous p‐toluene sulfonic acid solution as electrolyte. Applied potential and feed ratios of monomers (aniline and isoprene) were systematically varied and the reactions were done under aqueous conditions. The copolymer coatings were characterized by infrared spectroscopy and the formation of copolymer was confirmed by the presence of aliphatic secondary amine, aromatic secondary amine, and aliphatic CH stretch groups. The electronic structure of the copolymers was further investigated by using UV/Vis absorption spectroscopy. The electrochemistry of the formation of copolymers was studied by using cyclic voltammetry. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 184–192, 2002; DOI 10.1002/app.10298
Preparation for graft copolymers of sawdust/vinyl monomers and their application for removal of dye
Authors: Wang Gehui , Song Zhanqian , Lin Zhifeng , Wang Liansheng
Published: August 2002

A kind of cationic exchanging resin of carboxyl sawdust (CSD) was fabricated through the hydrolysis of graft copolymers of sawdust with acrylonitrile (SAN) and sawdust with acrylamide (SAA) that were made by initiator Fe2+/H2O2. A study of the graft copolymerization was conducted for initiator usage, vinyl monomer usage, and reaction temperature. The hydrolysis under basic/acid conditions was also studied for the yield and acid value of CSD followed to adsorb Basic Pink dye (BPD). Our results show the following: (1) graft copolymers (SAN and SAA) with a high rate of graft copolymerization are readily prepared by suitable usages of initiator and vinyl monomer under a certain temperature; (2) adsorption capacity of CSD is relative to pH of BPD solution and reaches the most adsorption capacity at pH ≈ 6; (3) adsorption capacity of CSD increases along with the augment of its acid value; and (4) the adsorption capacity of the CSD toward BPD increases along with augment of initial concentration of the adsorbate and reaches about 500 mg/g. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2390–2396, 2002
Metal ion adsorption behavior of poly[3‐(dimethylamine)propyl acrylate] and poly[3‐(dimethylamine)propylacrylate‐co‐acrylic acid] resins
Authors: Rivas Bernabé L. , Pooley S. Amalia , Aceitón Evelyn
Published: August 2002

Two resins were synthesized by radical polymerization using N,N′‐methylene‐bis‐acrylamide and ammonium persulfate as the crosslinking reagent and initiator, respectively. The yields were 98%. The resins were characterized by FTIR and UV‐Vis spectroscopy. Sorption behavior of resins toward Hg(II), Cd(II), Zn(II), Pb(II), and Cr(III) ions was studied at different pHs depending on the metal ion. Both resins showed selective sorption to Hg(II) ions at pH 2 from a mixture of all ions.The elution of Hg(II) bound to the resins was also investigated using perchloric acid at different concentrations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1251–1256, 2002; DOI 10.1002/app.10455
Membrane formation via thermally induced phase separation in polypropylene/polybutene/diluent system
Authors: Matsuyama Hideto , Okafuji Hajime , Maki Taisuke , Teramoto Masaaki , Tsujioka Norio
Published: August 2002

Porous membranes were prepared from a polymer blend system by the thermally induced phase separation (TIPS) process. The polymer blend system was isotactic polypropylene (iPP)/polybutene (PB) and the diluent was diphenyl ether (DPE). Two types of porous membranes were prepared by the extractions of DPE alone and both DPE and PB after the phase separation. The effect of the addition of PB to the iPP solution on the phase diagram was investigated and the phase separation kinetics was measured by the light scattering method. The addition of PB resulted in the higher solute rejection property and lower water permeance. By the further extraction of PB from the porous iPP/PB membrane prepared by the extraction of DPE, the water permeance was approximately doubled, maintaining almost the same rejection property. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1701–1708, 2002; DOI 10.1002/app.10550
Surface modification of tetrafluoroethylene–perfluoroalkyl vinylether copolymer (PFA) by plasmas for copper metallization
Authors: Inagaki N. , Narushima K. , Yamamoto T.
Published: August 2002

Tetrafluoroethylene–perfluoroalkyl vinylether copolymer (PFA) sheet surfaces were modified with argon, helium, oxygen, and hydrogen plasmas. How the four plasmas modified the PFA sheet surfaces was investigated. All plasmas modified the PFA surfaces and at the same time initiated degradation of the PFA polymer chains. The balance between modification and degradation was strongly influenced by the magnitude of the discharge current in the plasmas. Efficiency of the plasmas in modification was hydrogen plasma > oxygen plasma > argon plasma > helium plasma. The modification involved defluorination of CF2 carbons into CHF and CH2 carbons and oxidation into OCH2, OCHF, and OCF2 groups. The surface‐modification technique (a combination of hydrogen plasma treatment and silane coupling treatment) proposed in this study was applied for copper metallization of the PFA surface. The utility of the technique was confirmed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1087–1097, 2002
The effect of syndiotacticity on the gelation of aqueous poly(vinyl alcohol) solutions with Congo red
Authors: Kiuchi Masayuki , Uchikawa Akimoto , Tanigami Tetsuya , Matsuzawa Shuji , Yamaura Kazuo
Published: August 2002

The gelation of aqueous solutions containing syndiotacticity rich poly(vinyl alcohol) (s‐PVA) and Congo red was studied. The gelation occurred even at 40°C, different from aqueous solutions containing atactic PVA (a‐PVA) and Congo red. The melting point of gels, which were prepared from the solutions of s‐PVA concentration of 2.5% and Congo red concentration of 0.1%, was around 90°C. The size of the junction points in s‐PVA/Congo red hydrogels is larger than that of a‐PVA/Congo red hydrogels at each fixed Congo red concentration. Syndiotactic sequence length plays an important role in gelation. The melting points and shear moduli of the gels prepared from dilute polymer solution at 0–40°C changed through a maximum at around 0.1–0.3% of Congo red concentration and also a maximum at around 1.5%, identical to results reported already for a‐PVA/Congo red hydrogel prepared at 20°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 632–637, 2002
Soapless emulsion polymerization of butyl methacrylate through microwave heating
Authors: He Wei‐Dong , Pan Cai‐Yuan , Lu Tao
Published: August 2002

Soapless emulsion polymerization of n‐butyl methacrylate (BMA) was carried out through microwave heating with potassium persulfate (KPS) as an initiator at 73 ± 2°C. The influence of the monomer amount, the initiator amount, and the addition of ethanol on the monomer conversion, the particle size, and its distribution were studied. The results indicate that microwave polymerization had a much higher rate and produced smaller particles with a slightly broader size distribution compared with normal polymerization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2455–2459, 2001
Blends of poly(vinyl butyral‐co‐vinyl alcohol) and poly(ethylene terephthalate‐co‐ethylene naphthalate): thermal, mechanical, and morphological properties
Authors: Chang Jin‐Hae , Park Kwang Min , Kang Chung‐Seock , Jeong Hwan‐Kyeong
Published: August 2002

The miscibility behavior and morphology of a series of poly(vinyl butyral‐co‐vinyl alcohol) (PVBA) copolymers containing 29, 52, 76, and 88 mol % of vinyl alcohol units with poly(ethylene terephthalate‐co‐ethylene naphthalate) (PETN) was investigated by DSC and SEM. Blends of the PETN with PVBA were prepared by coprecipitation from a chloroform/o‐chlorophenol (20/80 wt %) mixture solvent. It was found that PVBAs with different vinyl alcohol content will form an immiscible phase with the amorphous PETN in the solution‐cast films. Also, PETN and PVBA with 29 mol % vinyl alcohol (PVBA‐29) are not miscible within the whole composition range. The glass‐transition temperatures of the blends were higher than those of the two‐component polymers. The values of the tensile properties of the blend films were also better than those of the original copolymer films. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2746–2751, 2001
Monitoring polyolefin modification along the axis of a twin screw extruder. I. Effect of peroxide concentration
Authors: Machado A. V. , Covas J. A. , Van Duin M.
Published: August 2002

The evolution of the structure of polyolefins with different ethene/propene ratios in the absence or in presence of peroxide was monitored along a twin screw extruder. Small samples were quickly collected from the melt at specific barrel locations and characterized by rheological measurements. The rheological properties of the polyolefins are hardly affected when processing is carried out in the absence of peroxide. In the presence of peroxide both branching/crosslinking and degradation occur along the extruder, until the peroxide is fully converted. The degree of branching/crosslinking and/or degradation depends on the ethene/propene ratio, on the original molecular weight of the polymer and on the amount of peroxide added. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 58–68, 2001
X‐ray diffraction studies on reverse‐annealed polyethylenes
Authors: Cser F. , Hopewell J. L. , Shanks R. A.
Published: August 2002

Linear low and high density polyethylene sheets were compression molded and crystallized at a 5–10°C/min cooling rate. Parts of the sheets were annealed at different temperatures up to 2°C below the melting temperature. The small angle X‐ray scattering (SAXS) and the wide angle X‐ray scattering intensities of the annealed samples were studied. SAXS intensities showed particle scattering with a bimodal size distribution. The estimated radii of gyration were 15–17 nm and 5–7 nm, respectively. The crystallinity and the radius of gyration increased slightly with increasing annealing temperature for some samples; others did not show any change. No peaks characteristic of intercorrelated lamellar crystallinity in the SAXS intensities developed during the annealing. The original broad peak of high density polyethylene disappeared from the SAXS recordings on annealing. The length of the perfect chain versus melting temperature was calculated by the Thomson‐Gibbs formula and Flory's concept of melting temperature depression where methyl groups and tertiary carbon atoms at the branches were regarded as second components (solvent). Linear relationships were found for both cases. Experimental data for a linear low density polyethylene obtained from the literature were in between the two functions. A lamellar model of crystallization corresponding to the data is proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 340–349, 2001
Synthesis and characterization of polyarylureas. I. Potentially semiconducting polymers
Authors: Díaz F. R. , Godoy A. , Moreno J. , Bernède J. C. , Sánchez C. O. , Opazo A. , Gargallo L.
Published: August 2002

Polyarylureas were synthesized from the reaction between phosgene with aromatic diamines. Depending on the pH, the polyarylureas presented different colors when the solvent used was pyridine. The polyarylureas were characterized by IR spectroscopy, elemental analysis, and X‐ray photoelectron spectroscopy (XPS). To study the thermal stability of the polymers, a thermal degradation was performed between 35 and 700°C. The polyarylureas decomposed above 350°C. Without doping, polyarylureas are considered as semiconductors [σ = 10−9 (Ωcm)− 1]; after doping with I2, their electrical conductivity increases by several orders of magnitude. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 822–830, 2001
Characterization of ionomer solutions. I. Division of the concentration region and viscosity–concentration functions
Authors: Hu Xiankui , Liu Zhenxing , Feng Kaicai , Li Tiandi , Huang Yuee
Published: August 2002

The solution behavior of metal maleate low density polyethylene graft ionomers (LDPE‐g‐MAMe) in extremely dilute and dilute solutions was investigated in this study. The concentration region was divided into three parts because of the different viscosity–concentration relations of these ionomers. The ηsp/C–C relations of zinc maleate low density polyethylene graft ionomers (LDPE‐g‐MAZn) were studied in detail and compared with those of low‐density polyethylene and low‐density polyethylene‐g‐maleic anhydride. Finally, the viscosity–concentration relations of LDPE‐g‐MAMe (Na, K, La) were also studied and compared with one another. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1481–1486, 2001
Three‐component photoresists containing thermally crosslinkable vinyl ether derivatives
Authors: Moon Seong‐Yun
Published: August 2002

Poly(4‐hydroxystyrene‐co‐4‐methoxystyrene) (MEOST) was synthesized and MEOST‐13 with the methoxystyrene content of 12.5 mol % was used as a binder polymer for a three‐component photopolymer system. The MEOST‐13 films containing a vinyl ether monomer and a photoacid generator are insolubilized in an aqueous base in a prebake step owing to the thermal crosslinking reaction between hydroxyl groups of MEOST‐13 and vinyl ether groups. Upon exposure to light and subsequent postexposure bake, the crosslinks are decomposed by photogenerated acids, leading to effective solubilization of the exposed areas. The MEOST‐13 films showed sufficient insolubilization at baking temperatures of 140°C or above. The conversion of vinyl ether groups increased rapidly with increasing baking temperature. The sensitivity of the MEOST‐13 films increased abruptly with an increase in postexposure bake temperature because of the nature of chemical amplification. The MEOST‐13 films showed a sensitivity of 33 mJ/cm2 and afforded positive‐tone images with the improved resolution of 0.30‐μm line and space at 248‐nm light. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3399–3404, 2001
Tensile properties of Attacus atlas silk submerged in liquid media
Authors: Pérez‐Rigueiro J. , Elices M. , Llorca J. , Viney C.
Published: August 2002

Tensile properties of Attacus atlas (Saturniidae) silk were measured in air, water, and ethanol. Control samples in air showed a large variability, so a normalization method was developed to enable comparison with the behavior of samples submerged in the liquid media. Amino acid analysis demonstrated that the composition of A. atlas silk is similar to that of silk produced by other members of the Saturniidae family. The tensile properties of A. atlas silk resemble those of Bombyx mori (common domesticated silkworm) silk, although the two silks have different compositions. In particular, the elastic modulus is decreased by immersion in water and increased slightly by immersion in ethanol. The behavior of A. atlas silk can be described in terms of water having a disruptive effect on proteinprotein hydrogen bonds, whereas ethanol acts as a desiccant and therefore enhances proteinprotein hydrogen bonding. There are significant differences between the tensile properties of A. atlas silk and spider (Nephila madagascarensis) drag line, even though these materials have similar amino acid compositions: the spider silk has previously been shown to exhibit a decreased elastic modulus and conspicuous supercontraction in both liquids. Primary composition is therefore not a simple indicator of mechanical function in silks. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 53–62, 2001
Relationships among blending conditions, size of dispersed phase, and oil resistance in natural rubber and nitrile rubber blends
Authors: Sirisinha Chakrit , Baulek‐Limcharoen Sauvarop , Thunyarittikorn Jarunee
Published: August 2002

The rheological properties, morphology, and oil resistance in natural rubber and nitrile‐butadiene rubber (NR/NBR) blends are investigated as functions of the blending conditions. It is found that the Mooney viscosity of the blends depends more strongly on the blending time than the rotor speed. The size of the NR dispersed phase is approximately independent of the rotor speed, but it decreases with increasing blending time up to 25 min. With a further increase in the blending time the NR dispersed phase size decreases. The results for the relative tensile strength, which is an indicator of oil resistance, are in agreement with those of the blend morphology, indicating that the oil resistance in a 20/80 NR/NBR blend strongly depends on the phase morphology of the blend. The smaller the size of NR dispersed phase, the higher the blend resistance to oil. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1232–1237, 2001
Modification of unsaturated polyester resin with bismaleimide
Authors: Gawdzik B. , Matynia T. , Chmielewska E.
Published: August 2002

The modification of a commercially available unsaturated polyester resin with 4,4′‐bismaleimidodiphenylmethane is presented. The properties of the modified resins were compared with those of the nonmodified resin, and the resins were characterized in the noncured state and after curing. The results indicate that the addition of bismaleimide to unsaturated polyester resin not only improves its properties but also accelerates the curing reactions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2003–2007, 2001
Toughening of crosslinked polystyrene with liquid rubber
Authors: Coelho Rogerio Soares , Cunico Cassia , Zawadzki Sonia , Akcelrud Leni
Published: August 2002

The optimum conditions for preparing poly(styrene‐co‐divinylbenzene) were determined and the variation of the mechanical properties of the networks with the crosslinking density was evaluated. The molecular weight between crosslinks was in the 800–12,000 range. The flexural modulus and flexural strength were 5000 and 110 MPa, respectively, for the more crosslinked materials. When liquid rubber (hydroxyl‐terminated polybutadiene) was incorporated into the glassy matrix, these values dropped to 2500 and 70 MPa, respectively, but the impact resistance increased to 70 J/m. These values were comparable to some commercial grade high impact polystyrene resins. The particle size of the dispersed rubber phase was on the nanometer scale, and attempts to increase its dimensions should provide further improvement in the impact properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2098–2105, 2001
Surface modification of tetrafluoroethylene–hexafluoropropylene (FEP) copolymer by remote H2, N2, O2, and Ar plasmas
Authors: Park Y. W. , Tasaka S. , Inagaki N.
Published: August 2002

Tetrafluoroethylene–hexafluoropropylene (FEP) copolymer sheets were modified by remote H2, N2, O2, and Ar plasmas, and the effects of the modification on adhesion between FEP sheets and copper metal were investigated. The four plasmas were able to modify the FEP surfaces' hydrophilicity. Defluorination and oxidation reactions on the FEP surfaces occurred with exposure to the plasma. The hydrophilic modification by H2 plasma was best, followed by modification by O2, Ar, and N2 plasmas. The surface modification of FEP by all four remote plasmas was effective in improving adhesion with copper metal. The peel strength order of the FEP/Cu adhesive joints was H2 plasma > Ar plasma > N2 plasma > O2 plasma. Mild surface modification is important for the adhesion improvement of FEP with Cu metal. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1258–1267, 2002
Development of the rat sublingual gland: A light and electron microscopic immunocytochemical study
Authors: Wolff M.S. , Mirels L. , Lagner J. , Hand A.R.
Published: August 2002

Cell differentiation in the rat sublingual gland occurs rapidly and is largely complete by birth. To study differentiation of the serous and mucous cells of the sublingual gland, we used antibodies to the secretory proteins CSP‐1, SMGB, PSP, and SMGD, and sublingual mucin as specific cell markers. Glands from rats at ages 18, 19, and 20 days in utero, and postnatal days 0, 1, 5, 9, 14, 18, 25, 40, and 60 were fixed and prepared for morphological analysis and immunocytochemical labeling. At age 18 days in utero, a few cells in the developing terminal bulbs contained mucous‐like apical granules that labeled with anti‐mucin. Other cells had mixed granules with a peripheral lucent region and a dense core of variable size that occasionally labeled with anti‐SMGD. Additionally, presumptive serous cells with small dense granules that contained CSP‐1 and SMGB were present. At age 19 days in utero, the dense granules of these cells also labeled with anti‐SMGD. By age 20 days in utero, mucous cells were filled with large, pale granules that labeled with anti‐mucin, and serous cells had numerous dense granules containing CSP‐1, SMGB, PSP, and SMGD. Fewer cells with mixed granules were seen, but dense regions present in some mucous granules (MGs) labeled with anti‐SMGD. After birth, fewer MGs had dense regions, and serous cells were organized into well‐formed demilunes. Except for PSP, which was undetectable after the fifth postnatal day, the pattern of immunoreactivity observed in glands of neonatal and adult animals was similar to that seen by age 20 days in utero. These results suggest that mucous and serous cells have separate developmental origins, mucous cells differentiate earlier than serous cells, and cells with mixed granules may become mucous cells. Anat Rec 266:30–42, 2002. © 2002 Wiley‐Liss, Inc.
Relationship between postsynaptic NK1 receptor distribution and nerve terminals innervating myenteric neurons in the guinea‐pig ileum
Authors: Portbury A.L. , Grkovic I. , Young H.M. , Furness J.B.
Published: August 2002

The amounts of neurokinin 1 (NK1) receptor immunolabelling on the membranes of myenteric cell bodies at appositions with tachykinin‐immunoreactive nerve terminals, other nerve terminals, and glial cells were compared at the ultrastructural level using pre‐embedding, double‐label immunocytochemistry. NK1 receptor immunoreactivity was revealed using silver‐intensified, 1 nm gold, and tachykinin‐immunoreactive nerve terminals were revealed using diaminobenzidine. The density of NK1 receptor immunolabelling (silver particles per length of cell membrane) on the membrane at appositions with tachykinin‐immunoreactive nerve terminals was not significantly different from that at appositions with other (nonimmunoreactive) nerve terminals or with glial cells. Synaptic specializations (“active zones”) were present at a small proportion of the appositions between NK1 receptor‐immunoreactive cell bodies and tachykinin‐immunoreactive or other nerve terminals. The density of NK1 receptor immunolabelling at synaptic specializations was lower than that at regions of appositions where no synaptic specializations were present. The presence of NK1 receptor on the cell surface in areas not directly apposed to tachykinin‐containing nerve terminals suggests that tachykinins that diffuse away from their site of release may still exert an action via NK1 receptors. Although NK1 receptors do not appear to be targetted to particular sites on the surfaces of myenteric nerve cell bodies and proximal dendrites, they are reduced in density at regions of the membrane‐forming synaptic specializations. Anat Rec 263:248–254, 2001. © 2001 Wiley‐Liss, Inc.
Epithelial cell dynamics in rabbit cecum and proximal colon P1
Authors: Grant T. Dawn , Specian Robert D.
Published: August 2002

The large intestine of mammals has long been viewed as an osmoregulatory organ, and evidence suggests that fluid and solute transport mechanisms within the intestine are heterogenous, varying depending on the particular segment involved. Variations in function are often matched by morphological correlates, but despite the widespread use of rabbit large intestine as an experimental model, there is a lack of knowledge about the cellular makeup and dynamics in the colonic mucosal epithelium. The presence of mitotic figures and immunohistochemical localization of proliferating cell nuclear antigen (PCNA) were used to identify the proliferative zone(s). Cellular migration patterns were determined through the use of the thymidine analog 5‐bromo‐2‐deoxyuridine (BrdU) over a 24‐, 48‐, and 72‐hr period. Apoptotic nuclei were identified utilizing terminal deoxynucleotidyl transferase d‐UTP nick‐end labeling (TUNEL). Both cecum and the initial portion of the proximal colon (P1) exhibited a proliferative zone at or near the crypt base, and migration proceeded upwards toward the surface epithelium lining the intestinal lumen, where apoptosis occurred Turnover time of crypt columnar cells was determined to be about 3 days; that of mucous cells was estimated to be about 5 weeks. Rabbit cecum and proximal colon P1 are similar in their cellular morphology and epithelial cell kinetics. In both, the major proliferative zone is located at or near the crypt base, from which crypt columnar cells migrate toward the lumenal surface epithelium over a period of 3 days. Goblet cell turnover rate is much slower than that of columnar cells. Anat Rec 264:427–437, 2001. © 2001 Wiley‐Liss, Inc.
Vitamin requirements of the cultured flesh fly cells, Sarcophaga peregrina (Diptera, Sarcophagidae)
Authors: Mitsuhashi Jun
Published: August 2002

Essential vitamins for the growth of a cell line derived from the flesh fly, Sarcophaga peregrina, were determined. By examining the survivability of continuous passages of the cells in the chemically defined medium lacking one vitamin, thiamine, riboflavin, pantothenate and either niacin or niacinamide were found to be essential for the continuous growth of the flesh fly cells in vitro. Arch. Insect Biochem. Physiol. 37:283–286, 1998. © 1998 Wiley‐Liss, Inc.
Endocrine mechanisms controlling body‐color polymorphism in locusts
Authors: Tanaka Seiji
Published: August 2002

The present article reviews recent published and unpublished findings on the hormonal mechanisms for the control of body‐color polymorphism in locusts. Emphasis is placed on the dark color–inducing factors and their role in the induction of various types of body coloration observed under different environmental conditions. Implantation of corpora cardiaca (CC) taken from normal nymphs of Locusta migratoria induced dark color in nymphs of an albino strain. Using the albino strain for the bioassay, a neuropeptide, [His7]‐corazonin, was identified as a dark color–inducing factor for L. migratoria and Schistocerca gregaria. In the former, depending upon the dose and timing of the injection, this peptide and juvenile hormone developed various body colors looking like those found in nature. The body coloration characteristic of gregarious forms was also induced in isolated albino nymphs and field‐collected solitary nymphs. In S. gregaria, on the other hand, the peptide induced black patterns, but the orange or yellow background color observed in gregarious forms was not induced when the peptide was injected into solitary individuals. [His7]‐corazonin also induced darkening in other grasshoppers and locusts, but not in katydids. Albino L. migratoria developed dark color when implanted with brains or CC taken from other insects belonging to 10 major insect orders, but not with those from Coleoptera. [His7]‐corazonin or a similar compound is widespread among insects and plays a pivotal role in controlling body color in some species and presumably other physiological roles in other species. Arch. Insect Biochem. Physiol. 47:139–149, 2001. © 2001 Wiley‐Liss, Inc.
DNA‐binding properties of the ecdysteroid receptor‐complex (EcR/USP) of the epithelial cell line from Chironomus tentans
Authors: Elke Carsten , Rauch Peter , Spindler‐Barth Margarethe , Spindler Klaus‐Dieter
Published: August 2002

DNA‐binding features of EcR and USP were investigated using a 0.4 M NaCl extract of the epithelial cell line of Chironomus tentans by means of electrophoretic mobility shift assays (EMSAs). It is shown that the DNA‐binding is enhanced by hormone administration and that in the hormone dependent shift, both EcR and USP, are present. Furthermore, we demonstrate that under these conditions, EcR/USP form a unique complex on inverted repeat elements (PAL1 and hsp27‐EcRE), while on direct repeat elements (DR1‐5), a second complex with higher mobility is formed. In this second complex, neither EcR nor USP are present. Thus, an additional difference between PAL1 and DR‐elements is the competition of other factors for DR‐elements, modulating its function as an EcRE. A competition EMSA, using PAL1 as radiolabeled probe, reveals the following order of binding strength: PAL1>DR4/5>DR1>DR2/3/hsp27. Surprisingly, using DR1 as radiolabeled probe, shows a different order of binding strength: DR1>DR2>DR3/4/5/PAL1>hsp27. This indicates that the complexes formed on PAL1 are not identical to the ones formed on DR1 and that both are not easily convertible. Furthermore, the affinity of the EcR/USP complex may be altered under various conditions or by interaction with cofactors.

Upon hormone administration, DNA binding of the receptor complex is enhanced, but the difference to hormone‐free binding reactions decreases in course of time, indicating an additional hormone independent activation. Arch. Insect Biochem. Physiol. 41:124–133, 1999. © 1999 Wiley‐Liss, Inc.
Gene transfer of a fibronectin peptide inhibits leukocyte recruitment and suppresses inflammation in mouse collagen‐induced arthritis
Authors: Imagawa Tomoyuki , Watanabe Shohei , Katakura Shigeki , Boivin Gregory P. , Hirsch Raphael
Published: August 2002

Objective

Cell adhesion plays an essential role in arthritis by recruiting and retaining leukocytes in the joint. Fibronectin, a major extracellular matrix component in synovium, plays a central role in cell–cell and cell–matrix interactions through ligation of cell surface integrins. The present study was designed to determine the effects of gene transfer of a 15–amino acid peptide derived from the 33‐kd carboxy‐terminal cell and heparin‐binding domain of fibronectin (FN‐C/H‐II) on established arthritis in mice.

Methods

Plasmid DNA encoding a FN‐C/H‐II minigene under control of the cytomegalovirus promoter was injected intravenously into mice with established collagen‐induced arthritis, and the effects on leukocyte adhesion and recruitment to the joints was determined.

Results

Following injection, circulating FN‐C/H‐II could be detected for at least 5 days. Treated mice demonstrated a marked reduction in progression of arthritis. Not only was disease progression halted, but a significant improvement in joint swelling was observed within 2 days of treatment. Leukocyte adhesion and recruitment were inhibited by FN‐C/H‐II, both in vitro and in vivo. Histologic evaluation revealed a marked reduction in infiltration of both neutrophils and lymphocytes into synovium, persisting for at least 10 days.

Conclusion

These results suggest that antagonism of cell adhesion by soluble fibronectin peptides may provide an approach to attenuating chronic arthritis.
A longitudinal study of World Wide Web users' information‐searching behavior
Authors: Cothey Vivian
Published: August 2002

A study of the “real world” Web information searching behavior of 206 college students over a 10‐month period showed that, contrary to expectations, the users adopted a more passive or browsing approach to Web information searching and became more eclectic in their selection of Web hosts as they gained experience. The study used a longitudinal transaction log analysis of the URLs accessed during 5,431 user days of Web information searching to detect changes in information searching behavior associated with increased experience of using the Web. The findings have implications for the design of future Web information retrieval tools.
Socio‐economic factors in the application of information and communication technologies in Nigerian print media
Authors: Ehikhamenor Fabian A.
Published: August 2002

Information and communication technologies (ICTs) have opened up new opportunities for the Nigerian print media to improve on their products and services. This study explores the socio‐economic factors associated with the adoption and use of ICTs by the media. Of a total of 54 socio‐economic factors considered, exactly 50% were found to have significant influence on the adoption and success of ICT applications. The factors that have the greatest positive influence on adoption of ICTs include organizational goal, profitability, organizational image, communication in the organization, productivity, and openness of workers to change. They also constitute success factors in the use of these technologies. The factors that constrained adoption and also successful application include high rate of inflation, unfavourable exchange rate of the naira to the dollar, low wage level, huge costs, low gross national product, inadequate funding, and unstable political situation. These constraining factors are indicators of economic weakness and political uncertainty. It seems that the significance of such factors, which are completely external to a business organization, was often underestimated in studies of organizational performance in developing countries.
Prescreening of choice options in ‘positive’ and ‘negative’ decision‐making tasks
Authors: Levin Irwin P. , Prosansky Caryn M. , Heller Daniel , Brunick Brad M.
Published: August 2002

Research on prescreening processes in decision making was extended by manipulating task valence in a series of three experiments. In Experiments 1 and 2, half the subjects had the ‘positive’ task of screening and then selecting someone to hire for a job and half had the ‘negative’ task of screening and then selecting someone to fire, where the choice options (worker descriptions) were the same in each task. In Experiment 1 some subjects were instructed to list options they would include for further consideration and some were instructed to list options they would exclude from further consideration. More options were screened out in the inclusion condition than in the exclusion condition and in the firing task than in the hiring task. Subjects in Experiment 2 were allowed to decide for themselves whether to use inclusion or exclusion in screening options. The main results from Experiment 1 were replicated. Also, subjects in the hiring task were more likely than subjects in the firing task to select inclusion as a strategy for prescreening options. In Experiment 3 the positive task involved adding stocks to a portfolio following an unexpected financial gain and the negative task involved disposing of stocks following a financial setback. Again, more options were screened out by subjects selecting the inclusion strategy than by exclusion subjects, but differences between the positive and negative tasks were not found. Results were explained in terms of a ‘status quo’ bias for adding or deleting options that transcends task differences and a positivity bias in judging people that distinguishes judgments in different task domains. Copyright © 2001 John Wiley & Sons, Ltd.
Comparison of dose dependences for bioeffects of continuous‐wave and high‐peak power microwave emissions using gel‐suspended cell cultures†
Authors: Pakhomov Andrei G. , Gajšek Peter , Allen Lori , Stuck Bruce E. , Murphy Michael R.
Published: August 2002

The study compared bioeffects of continuous wave (CW) microwaves and short, extremely high power pulses (EHPP) at the same carrier frequency (9.3 GHz) and average power (1.25 W). The peak transmitted power for EHPP was 250 kW (0.5‐μs pulse width, 10 p.p.s.), producing the E field of 1.57 MV/m in the waveguide. A biological endpoint was the density of yeast cells, achieved after a 6 h growth period in a solid nutrient medium (agarose gel) during EHPP or CW exposure. Owing to power losses in the medium, the specific absorption rate (SAR) ranged from 3.2 kW/kg at the exposed surface of the sample to 0.6 mW/kg at 24 mm depth. Absorption and penetration of EHPP was identical to CW, producing peak SAR values 200 000 times higher than the average SAR, as high as 650 MW/kg at the surface. CW and EHPP exposures produced highly nonuniform but identical heating patterns in exposed samples. Following the exposure, the samples were sliced in a plane perpendicular to the wave propagation, in order to separate cell masses exposed at different SAR levels. Cell density in the slices was determined by nephelometry and compared to unexposed parallel control samples. Cell density was strongly affected by irradiation, and the changes correlated well with the local temperature rise. However, the data revealed no statistically significant difference between CW and EHPP samples across the entire studied range of SAR levels (over six orders of magnitude). A trend (P < 0.1) for such a difference was observed in slices that were exposed at a time average SAR of 100 W/kg and higher, which corresponded to peak SAR above 20 MW/kg for the EHPP condition. These numbers could be indicative of a threshold for a specific (not merely thermal) exposure effect if the trend is confirmed by future studies. Bioelectromagnetics 23:158–167, 2002. Published 2002 Wiley‐Liss, Inc.
Cell proliferation and growth in C. elegans
Authors: Lambie Eric J.
Published: August 2002

The cell division and differentiation events that occur during the development of the nematode Caenorhabditis elegans are nearly identical between different individuals, a feature that distinguishes this organism from larger and more complex metazoans, such as humans and Drosophila. In view of this discrepancy, it might be expected that the regulation of cell growth, division and differentiation in C. elegans would involve mechanisms separate from those utilized in larger animals. However, the results of recent genetic, molecular and cellular studies indicate that C. elegans employs an arsenal of developmental regulatory mechanisms quite similar to those wielded by its arthropod and vertebrate relatives. Thus, the nematode system is providing both novel and complementary insights into the general problem of how growth and patterning events are integrated in development. This review offers a general perspective on the regulation of cell division and growth in C. elegans, emphasizing recent studies of these crucial aspects of development. BioEssays 24:38–53, 2002. © 2002 John Wiley & Sons, Inc.
Midline and laterality defects: Left and right meet in the middle†
Authors: Roessler Erich , Muenke Maximilian
Published: August 2002

The aim of this review is to summarize some of the recent advances in molecular embryology that help to explain the pathogenesis of holoprosencephaly (HPE), or its related malformation in model organisms, cyclopia, and laterality defects in humans, derived from detailed analysis of similar malformations in animal models. Recently, defects in several developmental pathways including those operated by the Sonic hedgehog and Nodal signaling factors have been implicated as causes of HPE or laterality defects in humans. Here we summarize the findings in animal models that indicate that both defects can be explained by mechanisms that relate to the proper development of the axial midline in vertebrates. BioEssays 23:888–900, 2001. Published 2001 John Wiley & Sons, Inc.
Active site structure and dynamics of cytochrome c3 from Desulfovibrio gigas immobilized on electrodes
Authors: Jalila A. , Daniel Simaan , Murgida H. , Hildebrandt Peter
Published: August 2002

Cytochrome c3 from Desulfovibrio gigas is electrostatically adsorbed on Ag electrodes coated with self‐assembled monolayers (SAMs) of 11‐mercaptoundecanoic acid. The redox equilibria and electron transfer dynamics of the adsorbed four‐heme protein are studied by surface enhanced resonance Raman spectroscopy. Immobilization on the coated electrodes does not cause any structural changes in the redox sites. The potential‐dependent stationary experiments distinguish the redox potential of heme IV (−0.19 V versus normal hydrogen electrode) from those of the other hemes for which an average value of −0.3 V is determined. Taking into account the interfacial potential drops, these values are in good agreement with the redox potentials of the protein in solution. The heterogenous electron transfer between the electrode and heme IV of the adsorbed cytochrome c3 is analyzed on the basis of time‐resolved experiments, leading to a formal electron transfer rate constant of 15 s−1, which is a factor of 3 smaller than that of the monoheme protein cytochrome c. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 331– 334, 2002
Spectral decomposition of intracellular complex fluorescence using multiple‐wavelength phase modulation lifetime determination: Technical approach and preliminary applications
Authors: Praus Petr , Gaskova Dana , Kocisova Eva , Chaloupka Roman , Stepanek Josef , Bok Jiri , Rejman Dominik , Rosenberg Ivan , Turpin Pierre‐Yves , Sureau Franck
Published: August 2002

Lifetime‐based spectral decomposition using a frequency‐domain phase/modulation technique is developed on a microspectrofluorimeter prototype. In a fluorescent mixture with strongly overlapping components, such measurements enable us to not only obtain excited state lifetimes of each fluorescent component but also determine the specific spectral contribution of each species without the use of any model spectra. Examples of such applications are first given for complex mixtures of highly overlapping fluorescent components in solution. Preliminary results concerning cellular applications are also reported. This allows us to follow the cellular uptake and intracellular stability of fluorescent labeled modified oligonucleotides in the context of antisense strategy studies. Indeed, the intracellular signal from the fluorescent label bound to oligonucleotides can be distinguished from those of the free label by its specific excited state lifetime. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 339–343, 2002
A study of conformational stability of poly(L‐alanine), poly(L‐valine), and poly(L‐alanine)/poly(L‐valine) blends in the solid state by 13C cross‐polarization/magic angle spinning NMR
Authors: Murata Katsuyoshi , Kuroki Shigeki , Kimura Hideaki , Ando Isao
Published: August 2002

13C cross‐polarization/magic angle spinning (CP/MAS) NMR and 1H T1ρ experiments of poly(L‐alanine) (PLA), poly(L‐valine) (PLV), and PLA/PLV blends have been carried out in order to elucidate the conformational stability of the polypeptides in the solid state. These were prepared by adding a trifluoroacetic acid (TFA) solution of the polymer with a 2.0 wt/wt % of sulfuric acid (H2SO4) to alkaline water. From these experimental results, it is clarified that the conformations of PLA and PLV in their blends are strongly influenced by intermolecular hydrogen‐bonding interactions that cause their miscibility at the molecular level. © 2002 Wiley Periodicals, Inc. Biopolymers 64: 26–33, 2002
Use of conserved key amino acid positions to morph protein folds
Authors: Reddy Boojala V. B. , Li Wilfred W. , Bourne Philip E.
Published: August 2002

By using three‐dimensional (3D) structure alignments and a previously published method to determine Conserved Key Amino Acid Positions (CKAAPs) we propose a theoretical method to design mutations that can be used to morph the protein folds. The original Paracelsus challenge, met by several groups, called for the engineering of a stable but different structure by modifying less than 50% of the amino acid residues. We have used the sequences from the Protein Data Bank (PDB) identifiers 1ROP, and 2CRO, which were previously used in the Paracelsus challenge by those groups, and suggest mutation to CKAAPs to morph the protein fold. The total number of mutations suggested is less than 40% of the starting sequence theoretically improving the challenge results. From secondary structure prediction experiments of the proposed mutant sequence structures, we observe that each of the suggested mutant protein sequences likely folds to a different, non‐native potentially stable target structure. These results are an early indicator that analyses using structure alignments leading to CKAAPs of a given structure are of value in protein engineering experiments. © 2002 Wiley Periodicals, Inc. Biopolymers 64: 139–145, 2002
Steam pressure disruption of municipal solid waste enhances anaerobic digestion kinetics and biogas yield
Authors: Liu H. W. , Walter H. K. , Vogt G. M. , Vogt H. S. , Holbein B. E.
Published: August 2002

Biomass waste, including municipal solid waste (MSW), contains lignocellulosic‐containing fiber components that are not readily available as substrates for anaerobic digestion due to the physical shielding of cellulose imparted by the nondigestible lignin. Consequently, a substantial portion of the potentially available carbon is not converted to methane and the incompletely digested residues from anaerobic digestion generally require additional processing prior to their return to the environment. We investigated and developed steam pressure disruption as a treatment step to render lignocellulosic‐rich biomass more digestible and as a means for increasing methane energy recovery. The rapid depressurization after steam heating (240°C, 5 min.) of the nondigested residues following a 30‐day primary digestion of MSW caused a visible disruption of fibers and release of soluble organic components. The disrupted material, after reinoculation, provided a rapid burst in methane production at rates double those observed in the initial digestion. This secondary digestion proceeded without a lag phase in gas production, provided ∼40% additional methane yields, and was accompanied by a ∼40% increase in volatile solids reduction. The secondary digestate was found to be enriched in lignin and significantly depleted in cellulose and hemi‐cellulose components when compared to primary digestate. Thus, steam pressure disruption treatment rendered lignocellulosic substrates readily accessible to anaerobic digestion bacteria and improved both the kinetics of biogas production and the overall methane yield from MSW. Steam pressure disruption is central to a new anaerobic digestion process approach including sequential digestion stages and integrated energy recovery, to improve process yields, provide cogenerated energy for process needs, and to provide effective reuse and recycling of waste biomass materials. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 121–130, 2002.