bluuebunny/crossref_metadata_2025 huggingface dataset:
Conversion of plastic/cellulose waste into composites. I. Model of the interphase
Authors: Hedenberg Peter , Gatenholm Paul
Published: April 2003

This article proposes a mechanism for a significant improvement in the mechanical performance of a simulated waste fraction, composed of an immiscible low‐density polyethylene (LDPE) and high‐impact polystyrene (HIPS) blend (70:30 proportion), when chemithermomechanical pulp (CTMP) fibers and maleic acid anhydride grafted styrene–ethylene/butylene–styrene block copolymer (MAH‐SEBS) were added. SEM micrographs of composites showed an increased contact between the continuous LDPE phase and CTMP fibers when the functionalized compatibilizer (MAH‐SEBS) was used. By employing a model study using LDPE and regenerated cellulose, we investigated the interphase properties between the plastic phase and the cellulosic component. The model study utilized ESCA, FTIR, and contact angle analysis to follow the reaction between the cellulose surface and the functionalized compatibilizer. All three methods showed that MAH‐SEBS was bonded to the surface of the cellulose. The single‐fiber fragmentation test showed that the adhesion between cellulose fibers and the plastic matrix was significantly improved for MAH‐SEBS–modified samples. The effect of enhanced adhesion on increased mechanical properties of cellulose composites is also discussed, and a prediction of composite strength given, based on interfacial adhesion promotion and fiber properties. © 1995 John Wiley & Sons, Inc.
Effect of addition of saccharose on gelation of aqueous poly(vinyl alcohol) solutions
Authors: Yamaura Kazuo , Mitsuishi Masami , Fukuda Mari , Tanigami Tetsuya , Hoei Yoshio , Matsuzawa Shuiji
Published: April 2003

The properties of poly(vinyl alcohol) (PVA) hydrogels containing saccharose were examined. The effect of the addition of saccharose to atactic PVA (α‐PVA) gels on their melting temperatures was larger than that for syndiotacticity‐rich PVA (s‐PVA) gels and the melting temperature was above 100°C for α‐PVA gels with saccharose contents of 60 wt %. However, the fusion enthalpy (ΔH) of the α‐PVA gels was at most 100 kJ/mol. The release of solvent (water/saccharose) from gels in air decreased with an increase in the saccharose content and the equilibrium was achieved after standing for 20 days for the α‐PVA and s‐PVA gels with saccharose contents above 40 and 20 wt %, respectively. © 1995 John Wiley & Sons, Inc.
Characterization of Nafion solutions and films and observation of the casting process using basic dyes as optical probes
Authors: Otsuki Soichi , Adachi Kimihiro
Published: April 2003

The absorption spectrum of methylene blue and crystal violet (CV) in ethanol–water in the presence of Nafion exhibited metachromasy, but a little or no formation of the large aggregates of the dye was observed. This indicates that the dye molecules are bound to the surface of the miceller particles of the polymer, but the ability of Nafion to induce the aggregation of the dye is weak. The absorption spectrum of malachite green (MG) and CV was measured in a cast film of Nafion at varying ambient humidity. The spectral change with humidity indicates that the decrease in the water content of the film causes the increase of H+‐ion concentration in the hydrophilic cluster of Nafion and, hence, leads to the protonation of the dyes. The absorption spectrum of a Nafion solution containing MG or CV was recorded in the process of casting. The dyes changed to the protonated form right after evaporation of most solvent from the solution. This suggests that the phase inversion occurs in the casting process. © 1995 John Wiley & Sons, Inc.
Thermal degradation of aliphatic–aromatic polyamides: Kinetics ofN,N′‐Dihexylisophthalamide neat and in presence of copper lodide
Authors: Broadbelt Linda J. , Klein Michael T. , Dean Barry D. , Andrews Stephen M.
Published: April 2003

An experimental study to determine the effect of copper (I) iodide (Cul) on the rate and product distribution of degradation of a model of an aliphatic–aromatic polyamide was carried out.N,N′‐Dihexylisophthalamide (DHI) was reacted in both an inert argon atmosphere and a pure oxygen environment at 350°C with CuI added in amounts ranging from 0 to 20% by weight. The rate of disappearance of DHI was enhanced by an order of magnitude when 0.5% by weight of CuI was added and was an increasing function of increasing CuI loading. Reaction in pure O2increased the rate of DHI degradation by two orders of magnitude over that for neat DHI pyrolysis. The rate of disappearance of DHI in O2was relatively unchanged when 5% CuI by weight was added. The transformations of DHI and its products are organized in terms of a set of reaction rules. This “reaction operator” formalism allowed computer generation of the reaction network and facilitated estimation of kinetic parameters. © 1995 John Wiley & Sons, Inc.
A paradoxical flame‐retardant effect of nitrates in ATH‐filled ethylene–vinyl acetate copolymer
Authors: Zhu Weiming , Weil Edward D.
Published: April 2003

In the course of a study of metal salts as flame retardants, it was surprisingly found that metal nitrates reduced the flammability of ATH‐filled ethylene–vinyl acetate copolymer (EVA). The limiting oxygen index (LOI) of ATH‐filled EVA was increased by the nitrates in the order of Cu(NO3)2·3H2O > (NH4)2Ce(NO3)6 > Zn(NO3)2·6H2O > Fe(NO3)3·9H2O > Al(NO3)3·9H2O > NaNO3. The effects were not caused by the water of hydration. All metal nitrates except NaNO3 reached a UL 94 V‐2 rating at 3 phr. Based on TGA, DSC, FTIR, and gas detection, the proposed mechanism of the flame‐retardant effect of nitrates is the oxidative degradation of the polymer to produce noncombustible products (CO2 and nitrogen oxides) at a rate sufficient to interfere with the normal combustion process despite the exothermicity of the oxidative degradation. It is possible that surface carboxylic acid structures also contribute to the flame‐retardant effect. © 1995 John Wiley & Sons, Inc.
Interfacial adhesion in polyethylene–kaolin composites: Improvement by maleic anhydride‐grafted polyethylene
Authors: Hindryckx F. , Dubois Ph. , Patin M. , Jérôme R. , Teyssié Ph. , Marti M. Garcia
Published: April 2003

Polyethylene–kaolin composites were investigated with a special emphasis on the control of the interfacial adhesion. Both matrix and filler were modified for this purpose. A stearic acid and maleic anhydride‐grafted polyethylene were used as potential interfacial agents and the efficiency of aminosilane‐surface‐treated kaolin was considered. Tensile strength, elongation, impact strength, and melt index were currently measured in relation to the processing conditions. Enhanced interfacial filler‐polymer adhesion progressively results in an decreased melt index. This has been clearly shown by comparing the effect of two polymeric additives to the polymer matrix, i.e., a maleic anhydride‐grafted HDPE (MAGPE) and an unmodified HDPE of a similar melt index. Compared to low molecular weight additives, such as stearic acid and aminosilane, MAGPE has proved to be a very efficient additive in improving the impact resistance of HDPE–kaolin composites even at low contents. © 1995 John Wiley & Sons, Inc.
Properties of henequen cellulosic fibers
Authors: Aguilar‐Vega Manuel , Cruz‐Ramos Carlos A.
Published: April 2003

The physical properties, thermal stability, and interaction with liquids of cellulosic fibers isolated from henequen fibers (Agave fourcroydes) by an alkaline digestion process were determined. Physical dimensions, apparent length, and diameter of henequen cellulosic fibers were determined by optical microscopy in a random sample of 125 fibers. Other properties such as crystallinity, specific gravity, and cellulose type were also determined. The sorption of several liquids in these cellulosic fibers was measured and correlated to the polar and hydrogen bonding components of the solubility parameters of the liquids. The results show that, in general, henequen cellulosic fibers have properties that are in close agreement with those found in other cellulosic materials from natural sources. © 1995 John Wiley & Sons, Inc.
β‐nucleators and β‐crystalline form of isotactic polypropylene
Authors: Huang Mei‐Rong , Li Xin‐Gui , Fang Bo‐Rong
Published: April 2003

Different levels of β‐form crystallinity in isotactic polypropylene (iPP) were produced by blending a series of additives. X‐ray diffraction analyses showed that the Kx values varied from 0 to 0.05. Indigosol Brown IRRD, Indigosol Red Violet IRH, Cibantine Orange HR, Indigosol Pink IR, Cibantine Blue 2B, Indigosol Golden Yellow IGK, and Indigosol Grey IBL were found to be effective β‐nucleators. The respective Kx values of the iPP samples containing the above seven β‐nucleators of 0.05 wt % are 0.54, 0.68, 0.82, 0.82, 0.86, 0.92, and 0.95. All the β‐nucleators possess fused benzene rings or heterocycles in their molecular structures. X‐ray diffraction studies on them revealed a mutual character in that the strongest or the second‐strongest reflections almost locate at the d‐spacing of 2.83 Å. The magnitude is about half of that of the β‐spherulites possess a bright color and that their Maltese Crosses display some concentric banding of a rather spiky, jagged character. Their lamellae exhibit a correlated and dendritic structure seen by a scanning electron microscope. © 1995 John Wiley & Sons, Inc.
Absorption of water in polyimide resins and composites
Authors: Paplham W. P. , Brown R. A. , Salin I. M. , Seferis J. C.
Published: April 2003

The effect of temperature, postcure, and fiber orientation on water absorption were examined for Kerimid® 723 bismaleimide resin. The effect of fiber orientation was also examined for Avimid® N and BASF X‐5260. Water absorption in Kerimid® 723 was found to have an Arrhenius temperature dependence, depend on degree of postcure, and be independent of fiber orientation. BASF X‐5260 water absorption was also found to be independent of fiber orientation. Avimid® N water absorption exhibited a strong dependence on fiber orientation. © 1995 John Wiley & Sons, Inc.
Preparation and viscosity behavior of hydrophobically modified poly(vinyl alcohol) (PVA)
Authors: Yahya G. O. , Ali Sk. Asrof , Al‐Naafa M. A. , Hamad E. Z.
Published: April 2003

In this study, a novel series of water‐soluble hydrophobically modified poly(vinyl alcohol) (PVA) is prepared by chemical modification of PVA, with the objective of investigating the polymer's rheological behavior for enhanced oil recovery applications. The solution viscosity of the polymer obtained is studied with respect to the polymer concentration, temperature, salinity, polymer modification, aging, shear rate, and polymer molecular weight. The solution viscosity of the PVA is greatly enhanced by the modification. The modified PVA exhibits a relatively high salt tolerance, typical of nonionic polymers, in the range of 0–7.0 wt % NaCl concentrations, and the viscosity of the polymer solution is relatively invariant with NaCl above 3.0 wt % NaCl concentration. Below 3 wt %, the viscosity shows a maximum then a minimum, an unusual behavior. Generally, the polymer exhibits an almost constant viscosity at high shear rates and a typical shear thinning behavior at low shear rates. In addition, increasing polymer concentration and molecular weight leads to an increase in the polymer solution viscosity. Moreover, the polymer exhibits smaller solution viscosity at a high temperatre, and a slight decrease in viscosity is also exhibited by the modified polymer with aging. Comparison of the viscosities of 18 polymer modifications indicates that the larger the numbers of hydrophobic groups (side chains) in the polymer structure, the smaller the viscosity. Moreover, the longer the hydrophobic groups (side chains) in the polymer structure, the greater the viscosity, if their number is small. © 1995 John Wiley & Sons, Inc.
Surface properties of EPDM, silicone rubber, and their blend during aging
Authors: Bhowmick Anil K. , Konar J. , Kole S. , Narayanan S.
Published: April 2003

Surface energy of EPDM, silicone rubber, and their 50 : 50 (by weight) blend during aging was determined by contact angle measurement using water and formamide as the probe liquids. The surface energy increases initially with aging time. The results are explained on the basis of the polar component of the surface energy. Blending offers a good degree of protection toward aging of EPDM rubber. The generation of polar groups during aging is confirmed by IR and ESCA investigations. © 1995 John Wiley & Sons, Inc.
Gas transport properties of soluble aromatic polyimides with sulfone diamine moieties
Authors: Kawakami H. , Anzai J. , Nagaoka S.
Published: April 2003

Aromatic polyimides derived from 2,2′‐bis(3,4‐dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 3,3′‐ or 4,4′‐diaminodiphenylsulfone (m‐DDS or p‐DDS) have been synthesized with a chemical imidization. The disappearance of amic acid groups and the appearance of imide groups are determined by IR and 1H‐NMR spectroscopies. The obtained polyimides are amorphous and soluble in organic solvents. The gas transport properties of the polyimide membranes to CO2, O2, N2, and CH4 have been determined at 35°C and at a pressure up to 10 atm. The (PCO2/PCH4) and (PO2/PN2) selectivities of the membranes are augmented due to their large gas diffusivity selectivities. This is considered to be due primarily to the high packing density of polymer chain. © 1995 John Wiley & Sons, Inc.
Free radical grafting of glycidyl methacrylate onto polypropylene in a co‐rotating twin screw extruder
Authors: Sun Yi‐Jun , Hu Guo‐Hua , Lambla Morand
Published: April 2003

Free radical grafting of glycidyl methacrylate (GMA) onto molten polypropylene (PP) was studied in a co‐rotating twin screw extruder. Grafting yields of GMA obtained under various experimental conditions along the screw length allowed for a good appreciation of the effects of chemical parameters (the presence of styrene and the concentrations of peroxide and monomers) and those of processing parameters (feed rate, screw speed, and specific throughput). Similar to the results obtained in a batch mixer,1 free radical grafting of GMA carried out in the extruder in the presence or absence of styrene proceeded rapidly, as it was virtually completed half‐way down stream of the extruder. Additionally, the presence of styrene as a second monomer increased the GMA grafting yield reatly with reduced PP chain degradation. The ultimate GMA grafting yield increased with increasing concentration of peroxide, 1,3‐bis(tert‐butylperoxyisopropyl)benzene. This similarity between the batch mixer and the extruder is related to the fact that in both cases it is the concentration of the peroxide and its half lifetime that determine the grafting rate and the ultimate grafting yield. On the othe hand, the GMA grafting yield decreased with increasing screw speed or feed rate. For a particular specific throughput (the ratio of throughput to screw speed), an increase in throughput with a concomitant increase in screw speed brought about a decrease in GMA grafting yield. It was concluded that the GMA grafting yield is affected primarily by the residence time in the zone in which free radicals are not depleted. The effects of screw speed, feed rate, and specific throughput manifest mainly through this local residence time distribution. Specific energy is not a good measure of the performance of the extruder with respect to the free radical rafting of GMA onto PP. © 1995 John Wiley & Sons, Inc.
The application of statistical process control to rheological measurements
Authors: Bafna Sudhir S.
Published: April 2003

This article presents data on and discusses the application of statistical process control (SPC) to rheological measurements. With the help of case studies on capillary rheometry and dynamic oscillation, it is shown how SPC, coupled with careful calibration and maintenane of rheometers, can demonstrate significant improvement in the accuracy and precision of rheological measurements. This improvement is evident on examination of the various control charts discussed and the narrowing of their control limits. Specifically, individual and moving range control charts for the apparent viscosity measured at an apparent shear rate of 100 s−1 using capillary rheometers are discussed. For the dynamic oscillatory rheometer, the charts presented are for the magnitude of the complex viscosity measured at a frequency of 1 Hz. This article shows how SPC provides quality assurance by assuring that erroneous data will not be inadvertently reported. The issues discussed are of universal interest and relevance, not only to rheologists, but to all scientists and engineers who make and/or use measurements. © 1995 John Wiley & Sons, Inc.
Recycling of sheet‐molding compounds by chemical routes
Authors: Winter H. , Mostert H. A. M. , Smeets P. J. H. M. , Paas G.
Published: April 2003

This article describes a number of chemical routes for the recycling of sheet‐molding compounds (SMC) consisting of glass fibers, filler (calcium carbonate), and an unsaturated polyester–styrene thermoset resin. Treatment of milled SMC with ethanol/potassium hydroxide at 85°C for 48 h ultimately affords a soluble polymeric fraction, consisting of styrene–fumaric acid copolymers. The excess of potassium hydroxide as well as the filler are removed via a neutralization step, which results in a large stream of waste chemicals. Treatment of SMC chips with ethanolamine at 180°C for 48 h gives a reaction mass that can be split into three fractions, viz., the glass fibers, the filler, and a methanol‐soluble polymeric residue. The excess of ethanolamine is recovered by distillation at 220°C and reduced pressure. The polymeric fraction consists of terpolymers of styrene, N,N′‐di(2‐hydroxyethyl)fumaramide and N‐2‐hydroxyethylmaleimide monomer units, the latter two bearing two and one hydroxyl groups, respectively. The terpolymer shows little solubility in unsaturated polyester, epoxy, or isocyanate resins. The glass fibers and the filler coated with the polymeric fraction can be used as constituents of bulk‐molding compounds (BMC). Replacing half of the original amount of glass fibers or filler of a standard BMC formulation by recycled materials does not significantly alter the mechanical properties. Increasing the amount of recyclate results in processing difficulties in the case of the glass fibers or a serious decline of the mechanical properties in the case of the filler/polymer. © 1995 John Wiley & Sons, Inc.
Alcell® lignin solubility in ethanol–water mixtures
Authors: Ni Y. , Hu Q.
Published: April 2003

The lignin solubility in aqueous solutions of different ethanol concentrations was studied. The concept of the solubility parameter was applied to account for the effect of ethanol concentration on the lignin solubility. Experimental results showed that the lignin solubility increased strongly as the ethanol concentration increased from 9.5 to 47.5% then, it increased much more slowly until a maximum was reached at an ethanol concentration of about 70%. Further increase in the ethanol concentration resulted in a slight decrease in the lignin solubility. Based on the lignin molecular formula, the solubility parameter (δ‐value) of the ALCELL® lignin was 13.7 (cal/cm3)1/2. The δ‐value of aqueous ethanol solutions of increased ethanol concentration was calculated and was found to decrease continuously from 22.31 (cal/cm3)1/2 for pure water to 12.08 (cal/cm3)1/2 for pure ethanol. The effect of ethanol concentration on the solubility of the ALCELL lignin was then explained based on the theory that lignin exhibited the maximum solubility when the δ‐value of the solvent was close to that of the ALCELL lignin and the H‐bonding capacity of the solutions with different ethanol concentrations was similar. © 1995 John Wiley & Sons, Inc.
Phase separation, crystallization, and structure formation in immiscible polymer solutions
Authors: Zryd J. L. , Burghardt W. R.
Published: April 2003

Morphological and calorimetric studies of phase separation have been carried out in solutions of a crystallizable polymer in poor solvents. Hydrogenated polybutadiene with low branch content was investigated in solutions with diphenyl ether and diphenyl methane, in which the equilibrium phase diagram exhibits both liquid–liquid phase separation and crystallization of the polymer. Emphasis is placed on sample preparation protocols using thermal treatments at low concentrations where it is anticipated that both phase separation mechanisms may influence the resulting morphology. Samples prepared using either ramp cooling or isothermal crystallization exhibit porous structures such as those seen in membrane materials, that predominantly reflect liquid phase separation. However, the interplay between the different kinetics of liquid demixing and crystallization provides a mechanism to control, for instance, pore size. DSC studies during ramp cooling showed evidence of two discrete crystallization processes associated with the two liquid phases expected to be present under these circumstances. Finally, high concentration samples showed morphological evidence of liquid phase separation induced at the growth front of spherulites in otherwise single‐phase polymer solutions. © 1995 John Wiley & Sons, Inc.
Competition between micellization and adsorption of diblock copolymers in a colloidal system
Authors: Dewalt L. E. , Ou‐Yang H. D. , Dimonie V. L.
Published: April 2003

Significant adsorption of polystyrene‐poly(ethylene oxide) (PS‐PEO) diblock copolymers onto PS latex particles in an aqueous dispersion is accomplished through suppression of micelle formation by adding tetrahydrofuran (THF) as a cosolvent. We add THF, a good solvent for the micelle core, to weaken the micelle and allow free chains for adsorption to the colloidal particles. Choosing a PS colloidal particle as the adsorption substrate (thus the adsorbed PS block can fully wet the subsurface), we eliminate the complications which arise from micelle formation on the colloidal surface. Since the PS particles swell in the mixed solvent, the adsorbed PS block may penetrate into the swollen latex core, which is favored for entropic reasons. A subsequent water quench of the system to a low THF solution shrinks the PS particle to its original size while retaining most of the adsorbed polymers. The adsorbed chains cannot be removed by adding surfactants or raising temperature to 90°C, indicating that the adsorbed layer is tightly attached to the surface due to kinetic hinderance of the chains in a confined environment. Neutron scattering experiments is being carried out to settle whether the PS penetrates the PS particle. © 1995 John Wiley & Sons, Inc.
Blending of natural rubber with linear low‐density polyethylene
Authors: Abdullah Ibrahim , Ahmad Sahrim , Sulaiman Che Som
Published: April 2003

Blends of natural rubber (NR) with linear low‐density polyethylene (LLDPE) were prepared by melt blending of the materials in a plasticorder mixer at various temperatures around the melting point of LLDPE and at various mixing rates. The optimum processing conditions were a temperature of about 135°C and a mixing rate of 55 rpm. The tensile properties, stress and strain, of the blend had improved significantly with the addition of liquid natural rubber (LNR) into the blend. For blends with compositions around 50% NR, about 10–15% LNR produced the most significant improvement in the physical properties. Welldispersed plastic particles in a rubber matrix were strongly indicated in these samples. Scanning electron micrographs (SEM) of the samples also indicated an increase in the homogeneity of the mixes with the addition of LNR. A single glass transition temperature of about−55°C for the blend was observed via dynamic mechanical analysis (DMA). Interfacial linking between the NR and LLDPE phases was attributed to the presence of active groups on the polyisoprene chain of LNR, which induced the interphase reaction between the NR and LLDPE phases. © 1995 John Wiley & Sons, Inc.
Aromatic polyamide–imides as materials for membranes. I. Synthesis and characterization
Authors: Reddy A. V. Rami , Reddy P. Sreenivasulu
Published: April 2003

Diamine amic acids were synthesized by reacting aromatic diamines with pyromellitic dianhydride in dimethylacetamide/dioxane. High molecular weight polyamide‐amic acids were prepared by low‐temperature solution polymerization of diamine amic acids with isophthaloyl chloride in dimethylacetamide. The cyclodehydration of polyamide‐amic acids to the corresponding polyamide–imides was accomplished by heating the cast films at 175°C for 3 h. The polyamide–imides were soluble in polar aprotic solvents like dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N‐methyl‐2‐pyrrolidone and could be cast into tough and flexible films. They were characterized by elemental analyses, inherent viscosities, IR, and 1H‐NMR spectra. The glass transition temperatures of polyamide–imides were determined by differential scanning calorimetry. The thermal stabilities of the polymers were measured by thermogravimetric analyses in air. © 1995 John Wiley & Sons, Inc.
Screening of mycelial fungi for nitrocellulose degradation
Authors: Sundaram S. T. , Zhang Y. Z. , Sharma A. , Ng Koonwing , Brodman B. W.
Published: April 2003

Several mycelial fungi were screened in liquid medium for their ability to degrade nitrocellulose. Nitrocellulose was tested as the sole source of nitrogen while starch was provided as an additional carbon source. More than 20% nitrocellulose degradation was accomplished with Acremonium persicinum ATCC 60921, Bjerkandera adusta ESF 620, Fusarium solani, IFO 31093, and Sclerotium rolfsii ATCC 24459 in a 3‐day growth period utilizing submerged cultivation. Cyathus stercoreus NRRL 6473 degraded only 8% of the nitrocellulose, while Irpex lacteus Z 212 degraded 24% of the nitrocellulose in a 7‐day growth period. © 1995 John Wiley & Sons, Inc.
Effect on the elastic modulus of high‐density polyethylene of differing thermal treatments
Authors: Daver F. , Cherry B. W.
Published: April 2003

The effect of different thermal treatments on the elastic modulus of high‐density polyethylene has been studied in order to determine which of the parameters defining the polymer morphology has the major effect on the modulus. After examination of the effects of crystallinity, spherulite size, and lamellar thickness, it is concluded that it is the spherulite size which plays the dominant role in controlling the magnitude of the modulus. © 1995 John Wiley & Sons, Inc.
Mesenchymal stem cells from rat visceral fat exhibit multipotential differentiation in vitro
Authors: Tholpady S.S. , Katz A.J. , Ogle R.C.
Published: April 2003

Human subcutaneous fat‐derived stem cells were recently shown to have the potential to differentiate in vitro into a variety of cell types, including adipocytes, osteoblasts, chondrocytes, and myoblasts (Zuk et al., Tissue Eng. 2001;7:211–228). Subcutaneous adipose tissue may therefore prove to be an easily acquired and abundant source of stem cells. Presently it is unclear whether mammals such as rats (which possess small or nonexistent subcutaneous fat pads) contain mesenchymal stem cells within the visceral fat of the abdominal cavity, or whether the visceral fat of any species contains stem cells. In this study we isolated and expanded a pool of mesenchymal cells from visceral fat of adult Sprague‐Dawley rats and induced their differentiation in vitro into adipocytes, osteoblasts, neural cells, and chondrocytes. The differentiated phenotypes were verified by morphology as well as detection and expression of tissue‐specific protein and mRNA. We conclude that despite well‐documented differences in the metabolic and biochemical properties among anatomically distinct depots of fat, the visceral fat of rats contains adult mesenchymal stem cells with developmental potential similar to those isolated from subcutaneous fat in humans. Therefore, animals such as rats provide both a source of fat‐derived stem cells and an immunocompetent, autologous host animal in which to investigate the capacity of the fat‐derived cells to differentiate and form tissues in vivo. Anat Rec Part A 272A:398–402, 2003. © 2003 Wiley‐Liss, Inc.
Effective PSA contamination in the Rotterdam section of the European Randomized Study of Screening for Prostate Cancer
Authors: Otto Suzie J. , van der Cruijsen Ingrid W. , Liem Michael K. , Korfage Ida J. , Lous Jan J. , Schröder Fritz H. , de Koning Harry J.
Published: April 2003

The extent of effective prostate‐specific antigen (PSA) contamination in the Rotterdam section of the ongoing European Randomized Study of Screening for Prostate Cancer (ERSPC) trial was evaluated and defined as when opportunistic PSA testing of ≥ 3.0 ng/ml was followed by biopsy, similar to the regular procedure within the trial. Records of participants aged 55–74 years at entry were linked to the regional database of the general practitioner (GP) laboratory to obtain PSA tests requested by GPs in the period 1 July 1997 to 31 May 2000 (2.9 years), and to the national pathology database to quantify the number of biopsies. All men randomized were included, only those with prostate cancer screen‐detected or clinically diagnosed before July 1997 were omitted from the analyses. 2,895 out of the 14,349 men (20.2%) in the control arm and 1,981 out of the 14,052 men (14.1%) in the screening arm were PSA‐tested, at an average annual rate of 73 and 52 per 1,000 person‐years, respectively. These rates were higher than those recorded at the national and regional levels, 33 and 38 per 1,000 person‐years, respectively. Opportunistic PSA testing in the control arm reached a peak within the first months of randomization, after which it decreased to around 70 per 1,000 person‐years. An opposite pattern was observed in the screening arm, where participants already had received the scheduled screening within the trial. The proportion of men in the control arm with PSA ≥ 3.0 ng/ml followed by biopsy and prostate cancer was 7–8% and 3%, respectively (3% and 0.4–0.6% in the screening arm), over the whole study period. Over a 4‐year rescreening interval, the average PSA and effective contamination amount were approximately 28% and 10%, respectively. PSA testing in the control arm in the Rotterdam ERSPC section is high, but was not followed by a substantial increase in prostate biopsies. Although the reasons for ordering PSA test or indicating biopsy are unknown, effective PSA contamination in the Rotterdam ERSPC section is low and not likely to jeopardize the power of the trial. © 2003 Wiley‐Liss, Inc.
Plasma DNA microsatellite panel as sensitive and tumor‐specific marker in lung cancer patients
Authors: Beau‐Faller Michèle , Gaub Marie Pierre , Schneider Anne , Ducrocq Xavier , Massard Gilbert , Gasser Bernard , Chenard Marie Pierre , Kessler Romain , Anker Philippe , Stroun Maurice , Weitzenblum Emmanuel , Pauli Gabrielle , Wihlm Jean Marie , Quoix Elisabeth , Oudet Pierre
Published: April 2003

The majority of lung cancer patients have tumor‐derived genetic alterations in circulating plasma DNA that could be exploited as a diagnostic tool. We used fluorescent microsatellite analysis to detect alterations in plasma and tumor DNA in 34 patients who underwent bronchoscopy for lung cancer, including 11 small cell lung cancer (SCLC) and 23 nonsmall cell lung cancer (NSCLC) (12 adenocarcinomas, 11 squamous cell carcinomas) and 20 controls. Allelotyping was performed with a selected panel of 12 microsatellites from 9 chromosomal regions 3p21, 3p24, 5q, 9p, 9q, 13q, 17p, 17q and 20q. Plasma DNA allelic imbalance (AI) was found in 88% (30 of 34 patients), with a similar sensitivity in SCLC and NSCLC. In the 24 paired available tumor tissues, 83% (20 of 24) presented at least 1 AI. Among these patients, 85% (17 of 20) presented also at least 1 AI in paired plasma DNA, but the location of the allelic alterations in paired plasma and tumor DNA could differ, suggesting the presence of heterogeneous tumor clones. None of the 20 controls displayed plasma or bronchial DNA alteration. A reduced panel of six markers (at 3p, 5q, 9p, 9q) showed a sensitivity of 85%. Moreover, a different panel of microsatellites at 3p and 17p13 in SCLC and at 5q, 9p, 9q and 20q in NSCLC patients could be specifically used. Analysis of plasma DNA using this targeted panel could be a valuable noninvasive test and a useful tool to monitor disease progression without assessing the tumor. © 2003 Wiley‐Liss, Inc.
Glutathione peroxidase isoforms as part of the local antioxidative defense system in normal and Barrett's esophagus
Authors: Mörk Hubert , Scheurlen Michael , Al‐Taie Oliver , Zierer Annette , Kraus Michael , Schöttker Katrin , Jakob Franz , Köhrle Josef
Published: April 2003

The development of an oesophageal adenocarcinoma arising in Barrett's mucosa is associated with a multistep process of genetic lesions that may be triggered by persistent oxidative damage. The glutathione peroxidase isoforms pGPx and GI‐GPx, which were identified recently in the mucosa of the esophagus, may play a role as defense factors to prevent such oxidative injury. To determine alterations of the expression of pGPx and GI‐GPx in Barrett's mucosa as compared to primary and regenerative squamous epithelium. Biopsy samples of oesophageal mucosa of patients with Barrett's esophagus (n = 12), patients with squamous restoration after thermal ablation (n = 10), and healthy controls (n = 5) were analyzed for pGPx and GI‐GPx mRNA expression by Northern blot and for glutathione peroxidase activity by enzymatic assay. Squamous regeneration was induced by argon plasma coagulation (APC) combined with proton pump inhibitor therapy. In Barrett's epithelium mRNA levels of pGPx (the secreted isoform) were significantly reduced and of GI‐GPx (the intracellular isoform) significantly increased as compared to normal squamous mucosa. In squamous mucosa that had regenerated after APC, no significant differences compared to the expression pattern of primary squamous mucosa were found. Compared to squamous mucosa, Barrett's metaplasia shows a different mRNA expression of pGPx and GI‐GPx that may be associated with increased susceptibility to oxidative damage. © 2003 Wiley‐Liss, Inc.
Preferential neurotrophic activity of fibroblast growth factor‐20 for dopaminergic neurons through fibroblast growth factor receptor‐1c
Authors: Ohmachi Shigeki , Mikami Tadahisa , Konishi Morichika , Miyake Ayumi , Itoh Nobuyuki
Published: April 2003

Degeneration of dopaminergic neurons of the substantia nigra causes Parkinson's disease. Therefore, neurotrophic factors for dopaminergic neurons are of substantial clinical interest. Fibroblast growth factor (FGF)‐20 preferentially expressed in the substantia nigra pars compacta (SNPC) of the rat brain significantly enhanced the survival of midbrain dopaminergic neurons. Here we examined the mechanism of action of FGF‐20 on dopaminergic neurons. FGF‐20 slightly enhanced the survival of total neurons of the midbrain, indicating that it preferentially enhanced the survival of dopaminergic neurons. FGF receptor (FGFR)‐1c was found to be expressed abundantly in dopaminergic neurons in the SNPC but at much lower levels in neurons of other midbrain regions by in situ hybridization. FGF‐20 was also found to bind FGFR‐1c with high affinity with the BIAcore system. Furthermore, FGF‐20 activated the mitogen‐activated protein kinase (MAPK) pathway, which is the major intracellular signaling pathway of FGFs. Both the FGFR‐1 inhibitor SU5402 and the MAPK pathway inhibitor PD98059 also significantly inhibited the activation of the MAPK pathway by FGF‐20 and the neurotrophic activity of FGF‐20. The present findings indicate that the activation of the MAPK pathway by FGF‐20 signaling through FGFR‐1c plays important roles in the survival of dopaminergic neurons in the SNPC. © 2003 Wiley‐Liss, Inc.
Glycosylation of acetylcholinesterase and butyrylcholinesterase changes as a function of the duration of Alzheimer's disease
Authors: Sáez‐Valero J. , Fodero L.R. , Sjögren M. , Andreasen N. , Amici S. , Gallai V. , Vanderstichele H. , Vanmechelen E. , Parnetti L. , Blennow K. , Small D. H.
Published: April 2003

The identification of biochemical markers of Alzheimer's disease (AD) may help in the diagnosis of the disease. Previous studies have shown that Aβ1–42 is decreased, and tau and phospho‐tau are increased in AD cerebrospinal fluid (CSF). Our own studies have identified glycosylated isoforms of acetylcholinesterase (Glyc‐AChE) and butyrylcholinesterase (Glyc‐BuChE) that are increased in AD CSF. Glyc‐AChE is increased in APP (SW) Tg2576 transgenic mice prior to amyloid plaque deposition, which suggests that Glyc‐AChE may be an early marker of AD. The aim of this study was to determine whether Glyc‐AChE or Glyc‐BuChE is increased in CSF at early stages of AD and to compare the levels of these markers with those of Aβ1–42, tau and phospho‐tau. Lumbar CSF was obtained ante mortem from 106 non‐AD patients, including 15 patients with mild cognitive impairment (MCI), and 102 patients with probable AD. Glyc‐AChE, tau and phospho‐tau were significantly increased in the CSF of AD patients compared to non‐neurological disease (NND) controls. Aβ1–42 was lower in the AD patients than in NND controls. A positive correlation was found between the levels of Glyc‐AChE or Glyc‐BuChE and disease duration. However, there was no clear correlation between the levels of tau, phospho‐tau or Aβ1–42 and disease duration. The results suggest that Glyc‐AChE and Glyc‐BuChE are unlikely to be early markers of AD, although they may have value as markers of disease progression. © 2003 Wiley‐Liss, Inc.
Morphological and electrophysiological characterization of abnormal cell types in pediatric cortical dysplasia
Authors: Cepeda Carlos , Hurst Raymond S. , Flores‐Hernández Jorge , Hernández‐Echeagaray Elizabeth , Klapstein Gloria J. , Boylan Marea K. , Calvert Christopher R. , Jocoy Emily L. , Nguyen Oanh K. , André Véronique M. , Vinters Harry V. , Ariano Marjorie A. , Levine Michael S. , Mathern Gary W.
Published: April 2003

The mechanisms responsible for seizure generation in cortical dysplasia (CD) are unknown, but morphologically abnormal cells could contribute. We examined the passive and active membrane properties of cells from pediatric CD in vitro. Normal‐ and abnormal‐appearing cells were identified morphologically by using infrared videomicroscopy and biocytin in slices from children with mild to severe CD. Electrophysiological properties were assessed with patch clamp recordings. Four groups of abnormal‐appearing cells were observed. The first consisted of large, pyramidal cells probably corresponding to cytomegalic neurons. Under conditions that reduced the contribution of K+ conductances, these cells generated large Ca2+ currents and influx when depolarized. When these cells were acutely dissociated, peak Ca2+ currents and densities were greater in cytomegalic compared with normal‐appearing pyramidal neurons. The second group included large, nonpyramidal cells with atypical somatodendritic morphology that could correspond to “balloon” cells. These cells did not display active voltage‐ or ligand‐gated currents and did not appear to receive synaptic inputs. The third group included misoriented and dysmorphic pyramidal neurons, and the fourth group consisted of immature‐looking pyramidal neurons. Electrophysiologically, neurons in these latter two groups did not display significant abnormalities when compared with normal‐appearing pyramidal neurons. We conclude that there are cells with abnormal intrinsic membrane properties in pediatric CD. Among the four groups of cells, the most abnormal electrophysiological properties were displayed by cytomegalic neurons and large cells with atypical morphology. Cytomegalic neurons could play an important role in the generation of epileptic activity. © 2003 Wiley‐Liss, Inc.
Melatonin regulates neuronal plasticity in the hippocampus
Authors: El‐Sherif Y. , Tesoriero J. , Hogan M.V. , Wieraszko A.
Published: April 2003

The influence of melatonin on hippocampal evoked potentials initiated by low‐ and high‐frequency electrical stimulations and by two pulses applied in rapid succession was investigated. In confirmation of our previous studies, melatonin attenuated the population spike triggered by low‐frequency stimulation (0.03 Hz). High‐frequency stimulation (HFS; 100 Hz for 1 sec, three times every 10 sec), which in control slices permanently facilitated neuronal excitability (347% ± 32%), was also able to amplify the melatonin‐depressed potential (467.8% ± 59.6%). Because melatonin is a hydrophobic molecule, it was dissolved and applied in ethanol. Ethanol (0.4%) by itself reduced the magnitude of HFS‐induced potentiation (233.5% ± 16.8%). The slices stimulated with two pulses separated with a delay longer than 15 msec demonstrated a facilitation of the response to the second stimuli (paired‐pulse facilitation; PPF). The influence of melatonin (100 μM) on PPF was biphasic: Shortly after addition of melatonin, PPF was briefly (5–10 min) reversed to paired‐pulse inhibition (PPI), which gradually returned to a stable PPF. Ethanol (0.4%) applied without melatonin exerted only a marginal, facilitatory effect on PPF. The delay between two successively applied pulses, shorter than 13 msec, resulted in attenuation of the response to the second stimuli (PPI). Melatonin (100 μM) reversed the attenuation of the second potential within 15–20 min following its application. Ethanol applied by itself at the concentration of 0.4% temporarily (5–10 min), but significantly, depressed the second potential. These results demonstrate the ability of melatonin to modulate specific forms of plasticity in hippocampal pyramidal neurons. © 2003 Wiley‐Liss, Inc.
Normal nigrostriatal innervation but dopamine dysfunction in mice carrying hypomorphic tyrosine hydroxylase alleles
Authors: Althini Susanna , Bengtsson Henrik , Usoskin Dmitry , Söderström Stine , Kylberg Annika , Lindqvist Eva , Chuva de Sousa Lopes Susana , Olson Lars , Lindeberg Jonas , Ebendal Ted
Published: April 2003

We investigated the use of the mouse tyrosine hydroxylase (TH) gene to drive knock‐in constructs in catecholaminergic neurons. Two targeting constructs representing truncated forms of either of the BMP receptors ALK‐2 or BMPR‐II preceded by an internal ribosome entry site (IRES) were introduced into the 3′ untranslated region of TH. An frt‐flanked neomycin‐resistance (neor) cassette was placed in the 3′ end of the targeting constructs. Mice homozygous for the knock‐in alleles showed various degrees of hypokinetic behavior, depending mainly on whether the neor cassette was removed. In situ hybridization and immunohistochemistry showed that TH mRNA and protein were variously down‐regulated in these mouse strains. Reduced levels of dopamine and noradrenalin were found in several brain areas. However, number and morphology of neurons in substantia nigra and their projections to striatum appeared normal in the neor‐positive TH hypomorphic mice as examined by markers for L‐aromatic amino acid decarboxylase and the dopamine transporter. Elimination of the neor cassette from the knock‐in alleles partially restored TH and dopamine levels. The present neor‐positive TH hypomorphic mice show that nigrostriatal innervation develops independently of TH and should find use as a model for conditions of reduced catecholamine synthesis, as seen in, for example, L‐dihydroxyphenylalanine‐responsive dystonia/infantile parkinsonism. © 2003 Wiley‐Liss, Inc.
Analytical resolution of a parallel second‐order reaction mechanism
Authors: Croce A. E. , Mogni L. V. , Irrazábal C. Vicente
Published: April 2003

The competition among the three different elementary second‐order processes involving the radicals A and B,

equation image

equation image

equation image

is frequently established in many combustion and atmospheric chemistry systems. The analytical resolution of the above mechanism for kAB = 2kAA and kAB = 2kBB, that is, for a cross‐combination ratio ϕ = kAB/(kAAkBB)1/2 = 2, is well‐known, but it has been claimed not to exist for ϕ ≠ 2.

In the present paper an analytical resolution of the system (1)–(3), performed under the condition kAB ≠ 2kAA and kAB ≠ 2kBB, leads to

equation image

The mathematical procedure leading to this equation and the equation itself are valid independently of the nature of the products of the reactions (1), (2) and (3), that is, recombination or disproportionation products, provided that the reactants and the order of the reactions remain the same.

The comparison with numerical integration for exemplary cases is performed. The solutions for the particular cases kAB ≠ 2kBB or kAB ≠ 2kAA are also presented. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 246–251, 2003
Über das viskositätsverhalten von holzcellulosenitraten
Authors: Zapf von F.
Published: April 2003

In Fortführung der Untersuchungen über die Ursachen der anomal hohen Km‐Werte von Holzcellulosenitraten wurde durch quantitative Fraktionierung, durch vergleichende viskosimetrische und osmotische Messungen und durch Aufstellung der Verteilungskurven nachgewiesen, daß die Km‐Werte der unfraktionierten Nitrate um so höher sind, je uneinheitlicher der molekulare Verteilungszustand ist. Die Km‐Werte der einzelnen Fraktionen haben den normalen Wert von Baumwollcellulosenitraten.

An der Massenverteilungskurve des polymeranalogen Nitrates einer schonend isolierten. Fichtencellulose wurden 3 Maxima festgestellt. Ein Zusammenhang zwischen der molekularen Uneinheitlichkeit und der Entstehung der Holzcellulose in verschiedenartigen Zellen (tracheale, Parenchym‐ und Sklerenchym‐Zellen) wird erwogen.

Durch vorhergehendes Umfällen der Zellstoffe aus Schweizers Reagens mit Seignettesalzlösung werden die Km‐Werte der polymeranalogen Nitrate nur unbedeutend niedriger. Ein durch die Seignettesalzlösung nicht ausgefällter Anteil besteht aus Holzpolyosen, deren Entfernung die Fraktionierung der Zellstoffnitrate begünstigt.

In die Cellulosemoleküle eingebaute Fremdgruppen oder geringe Beimengungen von nichtcellulosischen Bestandteilen sind für die Viskosität von verdünnten Cellulose‐nitratlösungen ohne wesentlichen Einfluß. Dagegen wirken sie sich infolge ihrer schlechten Löslichkeit bzw. ihrer heteropolaren Natur in konzentrierten Lösungen viskositätserhöhend aus. Durch Vergrößerung der Schubspannung wird dieser viskositätserhöhende Effekt wirkungslos.

In Äther gelöstes Diazomethan baut Cellulosenitrate in Acetonlösung rasch ab. Der Chemismus des Abbaues ist noch unbekannt.
Über einige S,S′‐alkylenbiscysteine und deren isolierung aus chemisch modifizierter wolle
Authors: Zahn von H. , Wollemann B.
Published: April 2003

Die chemische Stabilisierung von Wolle durch Einwirkung bifunktioneller Halogen‐derivate auf reduzierte Wolle (Harrisverfahren) wurde präparativ‐chemisch studiert.

Die von Harris angenommenen Bisthioäther des Cysteins wurden aus l‐Cystein und aliphatischen α,ω‐Dihalogenverbindungen X(CH2)nX mit n = 1–6 dargestellt und durch Elementaranalyse und Papierchromatographie charaketerisiert.

Bei der präparativen Aufarbeitung von reduzierter und mit den genannten α,ω‐Dihalogenverbindungen umgesetzter Wolle wurden S,S′‐Polymethylenbiscysteine in guten Ausbeuten isoliert, welche mit den synthetischen Verbindungen identisch sind.

Der von Harris 1941 angegebene Reaktionsmechanismus für die chemische Modifizierung von Wolle konnte somit präparativ‐chemisch bestätigt werden.