bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic mechanical properties and hysteresis loss of epoxidized natural rubber chemically bonded to the silica surface
Authors: Manna Ajay K. , De P. P. , Tripathy D. K.
Published: August 2002

High‐temperature (180°C) molding of epoxidized natural rubber (ENR) filled with precipitated silica leads to chemical bond formation between epoxy groups of ENR and silanol groups of silica. The extent of chemical bond formation is further enhanced in the presence of the silane coupling agent N‐3‐N‐(vinyl benzyl amino)ethyl‐γ‐amino‐propyl trimethoxy silane mono hydrogen chloride (trade name Z‐6032). The results of hysteresis loss measurements show that hysteresis loss increases with increase in coupling agent loading as a result of the higher modulus of the compounds compared to that of the ENR–silica mix. The dynamic mechanical property measurements show that the addition of coupling agent increases the glass‐transition temperature. Whereas strain‐dependent dynamic mechanical properties show that filler structure breakdown increases with increasing loading of coupling agent. Sulfur‐cured systems show higher filler structure breakdown compared to that of nonsulfur systems. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2171–2177, 2002
Preparation and mechanical properties of composite of fibrous cellulose and maleated polyethylene
Authors: Zhang Farao , Endo Takashi , Qiu Wulin , Yang Liqun , Hirotsu Takahiro
Published: August 2002

Fibrous cellulose and maleated polyethylene (FC–MPE) composites were prepared under melt mixing by maleation of polyethylene (PE) to obtain maleic anhydride (MA) grafted PE (MPE) and successive compounding of the resultant MPE with fibrous cellulose (FC). When increasing the content of added MA to 2 wt %, the grafting efficiency of MA decreases gradually to 84% and the grafted MA chains become longer. Scanning electron microscopy (SEM) reveals strong adhesion of MPE to FC in the FC–MPE composite, which is probably due to the increased compatibility between MPE and FC, in contrast to no adhesion of unmaleated PE (UPE) to FC in the FC–UPE composite. This difference in interfacial structure between the FC–MPE and FC–UPE composites results in quite different mechanical properties for them. With an increase in the FC content to 60 wt %, the tensile strength of the FC–MPE composite increases significantly and reaches 125% that of pure PE. Furthermore, the larger Young's modulus, larger bending elastic modulus, and smaller elongation of the FC–MPE composite strongly indicate effective transfer of the high tensile strength and elasticity of FC to the MPE matrix through the strong adhesion between FC and MPE. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1971–1980, 2002; DOI 10.1002/app.10428
Structure and thermal behavior of nylon‐6/polytetrahydrofuran triblock copolymers obtained via anionic polymerization
Authors: Petrov P. , Mateva R. , Dimitrov R. , Rousseva S. , Velichkova R. , Bourssukova M.
Published: August 2002

The structure, crystallization, and phase behavior of nylon6‐b‐polytetrahydrofuran‐b‐nylon6 triblock copolymers synthesized via activated anionic polymerization have been studied. The composition, molecular weight of polytetrahydrofuran (PTHF) soft block, and type of polymeric activators (PACs) have been varied. Differential Scanning Calorimetry (DSC), Wide‐Angle X‐ray Diffraction (WAXD), Transmission Electron Microscopy (TEM), and Polarized Light Microscopy (PLM) experiments have revealed that in triblock copolymers only the nylon‐6 component crystallizes while PTHF segments are amorphous. The soft blocks do not alter the spherulitic crystalline structure of nylon‐6 and hard blocks crystallize in the α‐modification. The degree of crystallinity decreases with increasing PTHF concentration. The phase behavior has been investigated by Dynamic Mechanical Thermal Analysis (DMTA). Two different glass transition temperatures (Tg) for all samples have been observed. This indicates that nylon‐6 and PTHF segments are not molecularly miscible and the copolymers are microphase separated. The mechanical properties of the copolymers synthesized have been evaluated. Nylon‐6 copolymers with soft block concentrations up to 10 w/w %, exhibit improved notched impact strength in comparison to the nylon‐6 homopolymer, retaining relatively high hardness and tensile strength. All copolymers possess low water absorption and good thermal stability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1448–1456, 2002; DOI 10.1002/app.10448
Formation of hydrophilic starch coatings on polyethylene films
Authors: Fanta George F. , Felker Frederick C. , Shogren Randal L. , Salch John H.
Published: August 2002

Thin starch coatings were deposited onto polyethylene (PE) film surfaces when PE films were immersed in 1% jet cooked starch solutions and the hot solutions were allowed to cool. Normal cornstarch, waxy cornstarch, high amylose cornstarch, and solvent‐extracted normal cornstarch (to remove native lipid) were used in these experiments. Amounts of adsorbed starch varied from about 0.03–0.05 mg per cm2 of PE, and these starch coatings imparted hydrophilic properties to film surfaces, as evidenced by contact angle measurements. Although starch could be removed by gently rubbing water‐wet PE surfaces, air‐dried coatings were more firmly attached, and did not separate from the PE surface when films were bent or flexed. SEM images of starch‐coated film surfaces showed that starch was deposited as particles less than 1 μm in diameter, and also as aggregates of these submicron particles. Despite the fact that some starch samples contained only very small amounts of amylose and native lipid, surface‐deposited starch in all experiments contained 90–100% amylose; and exhibited the same Vh X‐ray diffraction pattern, indicative of helical inclusion complex formation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1781–1788, 2002; DOI 10.1002/app.10589
Studies on plasma polymerization of hexamethyldisiloxane in the presence of different carrier gases
Authors: Fang Jianglin , Chen Hong , Yu Xuehai
Published: August 2002

Plasma polymerization of hexamethyldisiloxane(HMDSO) in the presence of different carrier gases such as H2, He, N2, Ar, and O2 was carried out using an inductively coupled electrodeless glow discharge. The polymerization kinetics showed that the monomer HMDSO plasma‐polymerized at different rates from low to high for the carrier gases H2, He, N2, Ar, and O2 in that order. The products were studied using FTIR, electron spectroscopy for chemical analysis, and elemental analysis. The results indicated that HMDSO molecules underwent different degrees of fragmentation in plasma polymerization for different carrier gases and radio frequency (RF) powers. The polymer deposition rate and the structures of products were mainly dependent on molecular fragmentation, which varied with carrier gas and imposed RF power. O2 and H2 gases can incorporate in the plasma polymers to form products containing more oxygen or hydrogen components, while other gases such as N2 have no detectable component in products. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1434–1438, 2001
Atomic force microscopy study on structure and properties of irradiation grafted silica particles in polypropylene‐based nanocomposites
Authors: Zhang Ming Qiu , Rong Min Zhi , Zeng Han Min , Schmitt Stefan , Wetzel Bernd , Friedrich Klaus
Published: August 2002

Nanosilica particles treated by irradiation grafting polymerization can effectively improve the strength and toughness of a thermoplastic polymer at a rather low filler content. A detailed investigation on the modified nanoparticles in the absence and presence of a polypropylene matrix is carried out by using atomic force microscopy. The results indicate that the loosen agglomerates of the untreated SiO2 became more compact due to the linkage between the nanoparticles offered by the grafting polymer. In addition, the molecules of the polypropylene matrix are able to diffuse into the modified nanoparticle agglomerates during the melt processing. Entanglement between the molecules of the grafting polymer and the matrix is thus available, which in turn facilitates a strong particle–matrix interfacial interaction. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2218–2227, 2001
Preparation and characterization of siliconized epoxy/bismaleimide (N,N′‐bismaleimido‐4,4′‐diphenyl methane) intercrosslinked matrices for engineering applications
Authors: Ashok Kumar A. , Alagar M. , Rao R. M. V. G. K.
Published: August 2002

Novel hybrid intercrosslinked networks of hydroxyl‐terminated polydimethylsiloxane‐modified epoxy and bismaleimide matrix systems have been developed. Epoxy systems modified with 5, 10, and 15 wt % of hydroxyl‐terminated polydimethylsiloxane (HTPDMS) were developed by using epoxy resin and hydroxyl‐terminated polydimethylsiloxane with γ‐aminopropyltriethoxysilane (γ‐APS) as compatibilizer and dibutyltindilaurate as catalyst. The reaction between hydroxyl‐terminated polydimethylsiloxane and epoxy resin was confirmed by IR spectral studies. The siliconized epoxy systems were further modified with 5, 10, and 15 wt % of bismaleimide (BMI). The matrices, in the form of castings, were characterized for their mechanical properties. Differential scanning calorimetry and thermogravimetric analysis of the matrix samples were also performed to determine the glass‐transition temperature and thermal‐degradation temperature of the systems. Data obtained from mechanical studies and thermal characterization indicate that the introduction of siloxane into epoxy improves the toughness and thermal stability of epoxy resin with reduction in strength and modulus values. Similarly the incorporation of bismaleimde into epoxy resin improved both tensile strength and thermal behavior of epoxy resin. However, the introduction of siloxane and bismaleimide into epoxy enhances both the mechanical and thermal properties according to their percentage content. Among the siliconized epoxy/bismaleimide intercrosslinked matrices, the epoxy matrix having 5% siloxane and 15% bismaleimide exhibited better mechanical and thermal properties than did matrices having other combinations. The resulting siliconized (5%) epoxy bismaleimide (15%) matrix can be used in the place of unmodified epoxy for the fabrication of aerospace and engineering composite components for better performance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 38–46, 2001
Curing kinetics and thermal properties of diglycidylether of bisphenol A with various diamines
Authors: Hwang Seok‐Ho , Jung Jae‐Chang
Published: August 2002

To prepare a high‐performance epoxy, we synthesized three types of diamines {N,N′‐(4,4′‐diphenylether)‐bis(4‐aminophthalimide), 4,4′‐bis(p‐aminophenoxy)dibenzalphentaerythriol, and 2,2′‐bis[4‐(p‐aminobenzoyl)phenyl]propane} as epoxy curing agents with a two‐step reaction sequence. The structures of the synthesized diamines were confirmed with Fourier transform infrared and nuclear magnetic resonance spectroscopy. The curing kinetics and thermal stability of the cured epoxy resin with diglycidylether of bisphenol A were estimated with differential scanning calorimetry and thermogravimetric analysis under a nitrogen atmosphere. The kinetics parameters were determined with the Ozawa and Kissinger equations. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 279–284, 2001
Time–temperature–transformation diagram for reactive processing of polyamide 12
Authors: Luisier A. , Bourban P.‐E. , Månson J.‐A. E.
Published: August 2002

In order to describe the different events occurring during the anionic polymerization of polyamide 12 (PA12), a general concept of a time, temperature, and transformation (TTT) diagram was established and related to reactive processing conditions. Polymerization kinetics were established, and it was found that the reaction was best described by an autocatalytic expression. Polymerization temperatures above and below the final polymer melting temperature were considered. Furthermore, the variation of the melting temperature and viscosity were followed as a function of the polymerization time and degree of conversion. It was shown that monomer–polymer phase separation and crystallization may occur during PA12 polymerization. The results could be adapted for use during liquid molding of PA12 polymers and their composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 963–972, 2001
Thermooxidative stability of different polyurethanes evaluated by isothermal and dynamic methods
Authors: Fambri L. , Pegoretti A. , Gavazza C. , Penati A.
Published: August 2002

Two methods for the evaluation of resistance to the thermooxidation of different classes of polyurethane films (PURs) throughout thermogravimetric analyses were used. Normal and waterborne polyurethanes were characterized using either isothermal or dynamic heating. In the isothermal method, the times required to reach degradations of 0.025, 0.05, and 0.10 were determined at several temperatures in the interval of 190–250 °C. In the dynamic method, heating rates of 0.5, 1, 2, 5, and 10 °C/min were used in the range of 30–500 °C, and degradations of 0.025, 0.05, 0.10, 0.20, and 0.40 were considered. From the Arrhenius plots, activation energies were evaluated ranging between 130 and 230 kJ/mol for normal PURs and between 80 and 170 kJ/mol for waterborne PURs depending on the method, temperature interval, and degree of degradation. Advantages and disadvantages of the two methods were compared. The isothermal method requires a preliminary test, and it was more useful for degradation studies up to 0.05. The dynamic method offered evidence for the presence of different degradation processes, and it was more suitable for the evaluation of kinetics parameters at higher degrees of degradation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1216–1225, 2001
Gasoline permeation resistance of the as‐blow‐molded and annealed polyethylene, polyethylene/polyamide, and polyethylene/modified polyamide bottles
Authors: Yeh Jen‐Taut , Chen Chin‐Her , Shyu Wei‐De
Published: August 2002

An investigation of the gasoline permeation resistance of the as‐blow‐molded and annealed polyethylene, polyethylene (PE)/polyamide (PA), and polyethylene/modified polyamide (MPA) bottles is reported. The gasoline permeation resistance improves dramatically after blending PA and MPA barrier resins in PE matrices during blow‐molding, and the order of barrier improvement corresponds to the order of barrier improvement of the barrier resins added in PE. Somewhat unexpectedly, the gasoline permeation rates of the annealed PE and/or PE/PA bottles annealed at 90°C or higher temperatures increase significantly with the annealing temperature and time. On the contrary, the gasoline permeation resistance of the annealed PE/MPA bottles increase significantly as the annealing temperature and/or time increase. For instance, the gasoline permeation rate of the PE/MPA bottle annealed at 120°C for 32 h is about 190 times slower than that of the as‐blow‐molded PE bottle. Further investigations found that, after blending the MPA and PA barrier resins in PE matrices, the relatively nonpolar hydrocarbon components present in the gasoline fuels were significantly blocked, without permeation during the permeation tests, in which the as‐blow‐molded PE/MPA bottle inhibited the permeation of hydrocarbon components more successfully than did the as‐blow‐molded PE/PA bottle. In contrast, the amounts of polar components that permeated through the as‐blow‐molded PE/PA and PE/MPA bottles were very small and about the same as the amount that permeated through the as‐blow‐molded PE bottle. Possible mechanisms accounting for these interesting behaviors are proposed in this study. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2827–2837, 2001
Mercapto‐modified copolymers in polymer blends. III. The effect of functionalized ethylene‐propylene‐diene rubber (EPDM) on curing and mechanical properties of NBR/EPDM blends
Authors: Oliveira Marcia G. , Soares Bluma G.
Published: August 2002

Ethylene‐propylene‐diene with ethylene norbornene as the diene (EPDM) samples functionalized with thioacetate (EPDMTA) or mercapto groups (EPDMSH) were employed as compatibilizing agents for nitrile rubber (NBR)/EPDM blends. The cure rate of the blend was affected by the presence of a small portion of these compounds. EPDMTA decreases the cure rate of the blends, whereas EPDMSH was able to decrease the scorch time and increase the cure rate when employed in a proportion as high as 5.0 phr. The compatibilization effect was influenced by the nature of the EPDM employed in the blends. Blends consisting of an EPDM sample with lower viscosity display better dispersion of the EPDM phase inside the NBR matrix and also better mechanical performance with the compatibilization. The compatibilization with EPDMSH is reactive, with the formation of chemical bond between the mercapto groups of the compatibilizing agent and the double bond of the diene rubber. The compatibilization with EPDMTA is also considered to be reactive because the vulcanized blends containing this functionalized copolymer contain a higher amount of cross linked material, as indicated by the lower weight loss after swelling experiments. A scanning electron micrograph demonstrated that these functionalized copolymers led to a finer phase morphology, mainly in NBR/EPDM57C blends. The compatibilization increases the dynamic elastic modulus without affecting the damping. An improvement of thermal aging resistance of the studied blends was also achieved with the presence of the functionalized copolymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 38–52, 2001
Sequence analysis of poly(ethylene terephthalate)/poly(butylene terephthalate) copolymer prepared by ester‐interchange reactions
Authors: Kim Joon Ho , Lyoo Won Seok , Ha Wan Shik
Published: August 2002

The molecular structure of the copolyester formed through the interchange reaction in poly(ethylene terephthalate)/poly(butylene terephthalate) blends was investigated with 13C‐NMR spectroscopy. The molar fractions of heterolinkage triads in the copolyesters were lower than the values calculated by Bernoullian statistics; this indicates that the sequence of heterolinkages was far from a random distribution at the initial stage of the interchange reaction. However, the randomness increased and the number‐average sequence length decreased with reaction time. The solubility of the blend decreased with increasing sequence length, resulting from the formation of block copolymers with long sequence lengths at the initial stage of the interchange reaction. The solubility of the copolyester formed by a dibutyltin dilaurate (DBTDL)‐catalyzed reaction was higher than that of the copolyester formed by a titanium tetrabutoxide‐catalyzed reaction; this is related to the fact that alcoholysis prevailed in the DBTDL‐catalyzed reaction. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 159–168, 2001
Electrical and thermal properties of composite of liquid crystalline polymer filled with carbon black
Authors: Wong Y. W. , Lo K. L. , Shin F. G.
Published: August 2002

The electrical resistivity and thermal conductivity of a liquid crystalline polymer (LCP) filled with a commercial carbon black (CB) of various volume fractions (ϕ) is investigated. The percolation threshold (ϕc) is found at about 3%, and the resistivity (ρ) as a function of (ϕ − ϕc) satisfies the exponential function. Although the pure LCP is highly anisotropic in thermal and mechanical properties after processing, the composite samples exhibit no preferential direction for electrical conduction. Samples of ϕ below ϕc exhibit a negative temperature coefficient of resistivity while those above ϕc show almost no temperature dependence from room temperature to 200°C. In addition, the samples at lower ϕ have higher thermal conductivity in the LCP flow direction than those measured in the transverse and thickness directions, and they approach the same value at higher ϕ. This result indicates that preferential molecular alignment of the matrix LCP is responsible for the behavior of the thermal conductivity of the composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1549–1555, 2001
Effect of emulsion polymerization conditions of vinyl acetate on the viscosity fluctuation and gelation behavior of aqueous poly(vinyl alcohol) solution
Authors: Lyoo Won Seok , Lee Sung Min , Koo Kang , Lee Joon‐Seok , Ghim Han Do , Kim Jae Pil , Lee Jinwon
Published: August 2002

Poly(vinyl alcohol) (PVA) was prepared by emulsion polymerization of vinyl acetate (VAc) at 40, 50, and 60°C. PVAs of various molecular parameters were dissolved in water at concentrations of 3, 5, and 7% (g/dL) and aged at 30 and 60°C. The effects of the molecular weight and polymerization temperature on the viscosity fluctuation and gelation behavior of aqueous PVA solutions were investigated. Viscosity was increased with increasing molecular weight when other parameters were held the same. PVA of superior molecular regularity due to the lower polymerization temperature of VAc had higher relative viscosity. Viscosity and its fluctuation of PVAs with aging time varied with the polymerization temperature of the precursors, concentration of the aqueous solutions, and aging time. For PVA with a number‐average degree of polymerization of 2800 prepared from poly(vinyl acetate) polymerized at 40°C, a sharp increase in viscosity was observed after 500 min of aging at a concentration of 7%. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1897–1902, 2001
Block copolymer molecular weight determination via gel permeation chromatography: Choosing a combining rule
Authors: Sebastian John M. , Register Richard A.
Published: August 2002

We present a method for accurately determining the true molecular weights of narrow‐distribution block copolymers, using only a basic gel permeation chromatograph (GPC) equipped with a refractive index detector and calibrated with polystyrene standards. Our approach is based on the well‐known observation that GPC calibration curves for different homopolymers in good solvents are essentially parallel, allowing the curves for different polymers to be described by simple hydrodynamic equivalence ratios rB versus polystyrene. We present values of rB, in both toluene and tetrahydrofuran, for various polydiene and hydrogenated polydiene homopolymers commonly incorporated into commercial styrenic block copolymers. These values of rB must be combined to yield the hydrodynamic equivalence ratio of the block copolymer, from which the block copolymer's true molecular weight can be determined. Three combining rules proposed in the literature are tested against a series of symmetric polystyrene–polybutadiene diblock copolymers of varying molecular weight. A simple linear combining rule accurately represents the results. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2056–2069, 2001
Diet of blue cod, Parapercis colias, living on undisturbed biogenic reefs and on seabed modified by oyster dredging in Foveaux Strait, New Zealand
Authors: Jiang Weimin , Carbines Glen
Published: August 2002

Little has been done to assess the potential impact of habitat modification by bottom fishing gear on the feeding habits of demersal fishes. An analysis is presented of the diet of blue cod in Foveaux Strait, southern New Zealand, based on the gut content of fish taken in winter 1999 from two sites where each site consisted of both undisturbed biogenic reefs and reefs modified by oyster dredging.

Of the 420 guts collected, 13% were empty. The overall mean wet weight of gut content was <4 g. No significant habitat or site effects were detected for the proportion of empty guts or the amount of food consumed.

A pattern was detected that blue cod on dredged habitats generally fed on more crustaceans than those on undistributed habitats. Blue cod from undisturbed habitat also displayed a more diverse diet than those taken from dredged habitat. These results suggest that long‐term disturbance of seabed habitat by the oyster fishery in Foveaux Strait has caused changes to the diet of blue cod. The findings also suggest that actions should be taken to protect the biogenic reefs from further damage if the blue cod fishery and related resources are to be effectively managed.

Changes in prey diversity with increasing fish size were also found, with prey diversity (Shannon–Wiener index) increasing from 0.83 to 1.35 over a range of fish size from <25 cm to larger than 34 cm. A total of 52 prey taxa were identified in the diet of blue cod. Crustaceans were the main component, followed by mollusca and polychaeta. Fish, echinodermata and ‘other’ were less important in the diet.

Copyright © 2002 John Wiley & Sons, Ltd.
Mechanics of venom expulsion in Crotalus, with special reference to the role of the fang sheath
Authors: Young Bruce A. , Blair Michael , Zahn Krista , Marvin Jessica
Published: August 2002

A combination of anatomical and experimental preparations were used to explore the function of the venom delivery system in rattlesnakes (Crotalus). The distal end of the venom duct is compressed near the point where it empties into the venom chamber, a space surrounding the fang defined by the fang sheath. Within the venom chamber, the inner fang membrane lies obliquely over the base of the fang at least partially occluding the entrance orifice. When the fang is retracted the combination of the compressed venom duct and the spatial position of the inner fang membrane serve to inhibit or block venom flow. As the fang is erected beyond approximately 60° (relative to the roof of the mouth) localized compression of the fang sheath decreases the size of the venom chamber, relieves the compressive force from the venom duct, and displaces the inner fang membrane away from the entrance orifice of the fang. Pressure recordings taken at different locations along the venom delivery system demonstrate that the venom gland produces suction during relaxation of the extrinsic glandular musculature. These findings suggest that the venom delivery system of Crotalus is both more flexible and more regulated than previously assumed. Anat Rec 264:415–426, 2001. © 2001 Wiley‐Liss, Inc.
Vagal afferents innervating the gastrointestinal tract and CCKA‐receptor immunoreactivity
Authors: Patterson Laurel M. , Zheng Huiyuan , Berthoud Hans‐Rudolf
Published: August 2002

A large body of evidence derived from electrophysiological recording and pharmacological/behavioral experiments suggests the presence of CCKA‐receptors on vagal primary afferent fibers innervating the gastrointestinal tract. With the availability of antibodies specific for the CCKA‐receptor, we wanted to demonstrate its presence and distribution on identified vagal afferent fibers and different types of terminals in the mucosa, myenteric plexus, and external muscle layers of the stomach and duodenum. In the duodenal mucosa, neither a C‐terminal (Ab‐1) nor an N‐terminal (Ab‐2) specific antibody produced any specific staining; in the myenteric plexus, non‐vagal enteric neurons and their processes, but not vagal intraganglionic laminar endings (IGLEs), exhibited CCKAR‐immunoreactivity. Similarly, in the gastric myenteric plexus, a population of enteric neurons and their processes, but not identified vagal IGLEs, were labeled by both antibodies. In both external muscle layers of the stomach, CCKAR‐immunoreactive axons were in close register with labeled vagal afferent intramuscular arrays, but the two labels were not contained in the same varicosities. Ab‐1 immunoreactivity was found in the cell membrane of vagal afferent perikarya in the nodose ganglia and in pancreatic acinar cells. The failure to detect CCKAR‐immunoreactivity in peripheral vagal afferent terminals cannot be due to methodological problems because it was present in enteric neurons in the same sections, and because it did not stain structures resembling IGLEs in material without the potentially masking vagal afferent label. We conclude that CCKA‐receptors on vagal afferent terminals: 1) are below the immunohistochemical detection threshold, 2) exhibit a conformation or affinity state inaccessible to the two antibodies, or 3) are not transported to the peripheral terminals. Anat Rec 266:10–20, 2002. © 2002 Wiley‐Liss, Inc.
The Sambungmacan 3 Homo erectus calvaria: A comparative morphometric and morphological analysis
Authors: Delson Eric , Harvati Katerina , Reddy David , Marcus Leslie F. , Mowbray Kenneth , Sawyer G. J. , Jacob Teuku , Márquez Samuel
Published: August 2002

The Sambungmacan (Sm) 3 calvaria, discovered on Java in 1977, was illegally removed from Indonesia in 1998 and appeared in New York City in early 1999 at the Maxilla & Mandible, Ltd. natural history shop. Here we undertake an analysis of its phylogenetic and systematic position using geometric morphometrics and comparative morphology. The coordinates of points in the sagittal plane from glabella to opisthion were resampled to yield “lines” of 50 semi‐landmarks. Coordinates of glabella, bregma, lambda, inion, and opisthion were also collected and analyzed separately. Casts of Homo erectus fossils from Indonesia, China, and Kenya and of “archaic H. sapiens” from Kabwe and Petralona, as well as 10 modern human crania, were used as the primary comparative sample. The modern humans were well separated from the fossils in a graphical superimposition of Procrustes‐aligned semi‐landmarks as well as in principal component and canonical discriminant analyses. In all of these, Sm 3 falls intermediate between the fossil and modern groups. Morphological comparisons of Sm 3 with a selection of Homo erectus fossils revealed its greatest similarity to specimens from Ngandong and the Sm 1 calvaria. Compared to all other H. erectus, Sm 3 was distinctive in its more vertical supratoral plane, less anteriorly projecting glabella and less sharply angled occiput. In these features it was somewhat similar to modern humans. It is not yet possible to determine if this similarity implies an evolutionary relationship or (more likely) individual or local populational variation. Several features of Sm 3 (small size, gracile supraorbital torus and lack of angular torus, and position in principal component analysis) suggest that it was a female. The use of geometric morphometrics provides a means to statistically test the shapes of such fossils in a manner not easily duplicated by other methods. The intermediate position of Sm 3 between fossil and modern samples in several different subanalyses exemplifies the value of this approach. Anat Rec 262:380–397, 2001. © 2001 Wiley‐Liss, Inc.
Secretion of the type 2 peritrophic matrix protein, peritrophin‐15, from the cardia
Authors: Eisemann Craig , Wijffels Gene , Tellam Ross L.
Published: August 2002

The midgut of most insects is lined with a peritrophic matrix, which is thought to facilitate digestion and protect the midgut digestive epithelial cells from abrasive damage and invasion by ingested micro‐organisms. The type 2 peritrophic matrix is synthesised by a complex and highly specialised organ called the cardia typically located at the junction of the cuticle‐lined foregut and midgut. Although the complex anatomy of this small organ has been described, virtually nothing is known of the molecular processes that lead to the assembly of the type 2 peritrophic matrix in the cardia. As a step towards understanding the synthesis of the peritrophic matrix, the synthesis and secretion of the intrinsic peritrophic matrix protein, peritrophin‐15 has been followed in the cardia of Lucilia cuprina larvae using immuno‐gold localisations. The protein is synthesised by cardia epithelial cells, which have abundant rough endoplasmic reticulum, Golgi, and vesicles indicative of a general secretory function. Peritrophin‐15 is packaged into secretory vesicles probably produced from Golgi and transported to the cytoplasmic face of the apical plasma membrane. The vesicles fuse with the plasma membrane at the base of the microvilli and release peritrophin‐15 into the inter‐microvilli spaces. The protein then becomes associated with the nascent peritrophic matrix, which lies along the tips of the epithelial cell microvilli. It is proposed that peritrophin‐15 binds to the ends of chitin fibrils present in the nascent peritrophic matrix, thereby protecting the fibril from the action of exochitinases. Arch. Insect Biochem. Physiol. 47:76–85, 2001. © 2001 Wiley‐Liss, Inc.
Determination of the minimal clinically important difference in rheumatoid arthritis joint damage of the Sharp/van der Heijde and Larsen/Scott scoring methods by clinical experts and comparison with the smallest detectable difference
Authors: Bruynesteyn Karin , van der Heijde Désirée , Boers Maarten , Saudan Ariane , Peloso Paul , Paulus Harold , Houben Harry , Griffiths Bridget , Edmonds John , Bresnihan Barry , Boonen Annelies , van der Linden Sjef
Published: August 2002

Objective

To assess the minimal clinically important difference (MCID) in joint damage on hand and foot radiographs of patients with early rheumatoid arthritis (RA) as assessed with the Sharp/van der Heijde and Larsen/Scott methods, and to study how the smallest detectable difference (SDD) relates to the MCID for each method.

Methods

The judgments of an international panel of experts on the clinical relevance of progression of joint damage as seen on sets of radiographs obtained at 1‐year intervals in 4 clinical settings (early versus late RA and mild versus high disease activity) were used as the external criterion, which was compared with the progression scores as determined by the 2 scoring methods. Progression scores with the highest combined sensitivity and specificity for detecting clinically relevant progression represented the MCID. Subsequently, the sensitivity and specificity of the scoring methods were determined when using the SDD as the threshold for relevant progression, and these were compared with the sensitivity and specificity of the MCID.

Results

The panel judged changes in joint damage around the level of the SDD (5.0) of the Sharp/van der Heijde method as minimal clinically important, resulting in satisfactory sensitivity (mean 79%) and specificity (mean 84%) for detecting clinically important progression in the 4 clinical settings when using the SDD as the threshold value. The MCID (mean 2.3) of the Larsen/Scott method was much smaller than its SDD (5.8), and the sensitivity for detecting clinically important progression by applying the SDD as threshold was consequently low (mean 51%), accompanied by high specificity (mean 99%).

Conclusion

This study suggests that the SDD of the Sharp/van der Heijde method can be used as the MCID, i.e., as the threshold level for individual response criteria. The SDD of the Larsen/Scott method, however, turned out to be too insensitive to use as the threshold for individual clinically relevant change.
On the assessment of effects of food on the pharmacokinetics of drugs in early development
Authors: Li Zhihong , Vachharajani Nimish N. , Krishna Rajesh
Published: August 2002

The impact of food on the pharmacokinetics of a drug has important implications in drug development. This commentary is aimed at addressing two key challenges, developability of drugs whose pharmacokinetics are severely influenced by food, and the need for addressing the effects of fruit juice ingredients which modulate metabolic/efflux properties of a compound. Perspectives on the value in predicting food‐drug interactions during preclinical development, timing of clinical food‐drug interaction studies, and implications of food effects are presented herein. Copyright © 2002 John Wiley & Sons, Ltd.
Static and ELF magnetic fields induce tumor growth inhibition and apoptosis
Authors: Tofani Santi , Barone Domenico , Cintorino Marcella , de Santi Maria Margherita , Ferrara Adriana , Orlassino Renzo , Ossola Piero , Peroglio Flavio , Rolfo Katia , Ronchetto Flavio
Published: August 2002

The ability of static and extremely low frequency (ELF) Magnetic Fields (MF) to interfere with neoplastic cell function has been evaluated. In vitro experiments were carried out to study the role of MF characteristics (intensity, frequency, and modulation) on two transformed cell lines (WiDr human colon adenocarcinoma and MCF‐7 human breast adenocarcinoma) and one nontransformed cell line (MRC‐5 embryonal lung fibroblast). Increase in cell death morphologically consistent with apoptosis was reported exclusively in the two transformed cell lines. Cell‐death induction was observed with MF of more than 1 mT. It was independent of the MF frequency and increased when modulated MF (static with a superimposition of ELF at 50 Hz) were used. Based on the in vitro results, four different MF exposure characteristics were selected and used to treat nude mice xenografted with WiDr cells. The treatment of nude mice bearing WiDr tumors subcutaneously. with daily exposure for 70 min to MF for 4 weeks caused significant tumor growth inhibition (up to 50%) by the end of the treatment when modulated MF were used for at least 60% of the whole treatment period and the time‐averaged total MF intensity was higher than 3.59 mT. No toxic morphological changes induced by exposure were observed in renewing, slowly proliferating, or static normal cells. A discussion on the possible biophysical mechanism at the base of the observed biological results is also offered. Bioelectromagnetics 22:419–428, 2001. © 2001 Wiley‐Liss, Inc.
Fibroblast growth factor signaling in Caenorhabditis elegans
Authors: Borland Christina Z. , Schutzman Jennifer L. , Stern Michael J.
Published: August 2002

Growth factor receptor tyrosine kinases (RTKs), such as the fibroblast growth factor receptor (FGFR), play a major role in how cells communicate with their environment. FGFR signaling is crucial for normal development, and its misregulation in humans has been linked to developmental abnormalities and cancer. The precise molecular mechanisms by which FGFRs transduce extracellular signals to effect specific biologic responses is an area of intense research. Genetic analyses in model organisms have played a central role in our evolving understanding of these signal transduction cascades. Genetic studies in the nematode C. elegans have contributed to our knowledge of FGFR signaling by identifying genes involved in FGFR signal transduction and linking their gene products together into signaling modules. This review will describe FGFR‐mediated signal transduction in C. elegans and focus on how these studies have contributed to our understanding of how FGFRs orchestrate the assembly of intracellular signaling pathways. BioEssays 23:1120–1130, 2001. © 2001 John Wiley & Sons, Inc.
DNA replication joins the revolution: Whole‐genome views of DNA replication in budding yeast
Authors: Newlon Carol S. , Theis James F.
Published: August 2002

Replication origins, which are responsible for initiating the replication of eukaryotic chromosomal DNAs, are spaced at intervals of 40 to 200 kb. Although the sets of proteins that assemble at replication origins during G1 to form pre‐replicative complexes are highly conserved, the structures of replication origins varies from organism to organism. The identification of replication origins has been a labor‐intensive task, requiring the analysis of chromosomal DNA replication intermediates. As a result, only a few replication origins have been identified and studied. In a pair of recently published papers,(1, 2) Raghuraman and colleagues and Wyrick, Aparicio and colleagues provide complementary microarray‐based approaches to the identification of replication origins. These genome‐wide views of DNA replication in Saccharomyces cerevisiae provide new insights into the way that the genome is duplicated and hold promise for the analysis of other genomes. BioEssays 24:300–304, 2002. ©2002 Wiley Periodicals, Inc.
The DAP kinase family of pro‐apoptotic proteins: novel players in the apoptotic game
Authors: Kögel Donat , Prehn Jochen H.M. , Scheidtmann Karl Heinz
Published: August 2002

The DAP (Death Associated Protein) kinase family is a novel subfamily of pro‐apoptotic serine/threonine kinases. All five DAP kinase family members identified to date are ubiquitously expressed in various tissues and are capable of inducing apoptosis. The sequence homology of the five kinases is largely restricted to the N‐terminal kinase domain. In contrast, the adjacent C‐terminal regions are very diverse and link individual family members to specific signal transduction pathways. There is increasing evidence that DAP kinase family members are involved in both extrinsic and intrinsic pathways of apoptosis and may play a role in tumor progression. This review will focus on structural composition and subcellular localization of DAP kinase family members and on signal transduction pathways leading to their activation. Potential mechanisms of DAP kinase family‐mediated apoptosis will be discussed. BioEssays 23:352–358, 2001. © 2001 John Wiley & Sons, Inc.
Preparation of active enzyme samples for IR studies of Na+/K+‐ATPase
Authors: Thoenges Detlef , Zscherp Christian , Grell Ernst , Barth Andreas
Published: August 2002

In the case of the integral membrane protein Na+/K+‐ATPase, preparation of highly concentrated samples for IR difference spectroscopy often leads to inactivation of the enzyme. Therefore, we compared the activity of Na+/K+‐ATPase using different techniques of sample preparation. The loss of activity can be minimized by cooling the sample to 10°C and by the addition of glycerol and dithiothreitol. The activity of Na+/K+‐ATPase isolated from pig kidney is independent of the protein concentration whereas the enzyme from shark rectal gland is inactivated at concentrations above 1 μg/μL and is thus unsuitable for IR experiments. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 271–274, 2002
Albumin recovery with centrifugal adsorption technology (CAT)
Authors: Peet D. J. , Bisschops M. A. T. , van Hateren S. H. , van der Wielen L. A. M.
Published: August 2002

Centrifugal adsorption technology (CAT) is a new compact, countercurrent technology for efficient adsorption from large liquid streams by using adsorbent particles in the micrometer range. CAT seems particularly suited for the recovery of macromolecules at low concentrations, because the small particle dimensions lead to fast mass transfer rates. In this work, the potential of CAT for protein recovery is studied by model and experiment. A predictive model for the separation performance of CAT is presented, incorporating mass transfer resistance and axial dispersion transport in the liquid and the adsorbent phases. The model calculations were compared to experimental data for the adsorption of bovine serum albumin (BSA) on a standard commercial anion‐exchange resin with particle diameter dp = 50 μm in a pilot‐scale CAT apparatus. The model calculations accurately predicted the separation efficiency of CAT. The experimental set‐up is shown to be mass transfer limited for the conducted experiments, which agrees with the model predictions. The model was also used to estimate the dimensions and performance of a CAT apparatus for the large‐scale recovery of human serum albumin (HSA) from fermentation broth at the scale of 40 tons per year. The resulting equipment dimensions proved to be very small indeed, making CAT a potentially very attractive technology. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 237–250, 2002.
Host selection as a downstream strategy: Polyelectrolyte precipitation of β‐glucuronidase from plant extracts
Authors: Menkhaus Todd J. , Eriksson Sara U. , Whitson Paul B. , Glatz Charles E.
Published: August 2002

Host selection can be a strategy to simplify downstream processing for protein recovery. Advancing capabilities for using plants as hosts offers new host opportunities that have received only limited attention from a downstream processing perspective. Here, we investigated the potential of using a polycationic precipitating agent ( polyethylenimine; PEI ) to precipitate an acidic model protein ( β‐ glucuronidase; GUS) from aqueous plant extracts. To assess the potential of host selection to enhance the ease of recovery, the same procedure was applied to oilseed extracts of canola, corn ( germ), and soy. For comparison, PEI precipitation of GUS was also evaluated from a crude bacterial fermentation broth. Two versions of the target protein were investigated — the wild‐type enzyme (WTGUS) and a genetically engineered version containing 10 additional aspartates on each of the enzyme's four homologous subunits (GUSD10). It was found that canola was the most compatible expression host for use with this purification technique. GUS was completely precipitated from canola with the lowest dosage of PEI (30 mg PEI/g total protein), and over 80% of the initial WTGUS activity was recovered with 18‐fold purification. Precipitation from soy gave yields over 90% for WTGUS but only 1.3‐fold enrichment. Corn, although requiring the most PEI relative to total protein to precipitate ( 210 mg PEI/g total protein for 100% precipitation), gave intermediate results, with 81% recovery of WTGUS activity and a purification factor of 2.6. The addition of aspartate residues to the target protein did not enhance the selectivity of PEI precipitation in any of the systems tested. In fact, the additional charge reduced the ability to recover GUSD10 from the precipitate, resulting in lower yields and enrichment ratios compared to WTGUS. Compared to the bacterial host, plant systems provided lower polymer dosage requirements, higher yields of recoverable activity and greater purification factors. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 148–154, 2002.
Comparison of linear gradient and displacement separations in ion‐exchange systems
Authors: Natarajan V. , Ghose S. , Cramer S. M.
Published: August 2002

The linear gradient mode of chromatography is the most widely employed mode of operation in ion‐exchange chromatographic separations. However, in recent years, the displacement mode has received considerable attention because of its promise of high throughput and high resolution. To enable a comparison of these two modes of chromatography, it is essential to identify the optimum operating conditions for each. We employed an iterative algorithm to carry out the necessary optimization. The Steric Mass Action model of ion‐exchange chromatography is used in concert with the solid‐film linear‐driving force model to describe the chromatographic behavior of the solutes in these systems. The performances of displacement and gradient modes of chromatography are compared for different types of separation problems. It turns out that for “easy” separations, both the modes are equally effective. However, for challenging separations, the displacement mode is superior to the gradient mode. Our results shed significant light on the performance of gradient and displacement modes in protein ion‐exchange systems. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 365–375, 2002.
Choline‐binding domain as a novel affinity tag for purification of fusion proteins produced in Pichia pastoris
Authors: Caubín J. , Martín H. , Roa A. , Cosano I. , Pozuelo M. , de la Fuente J. M. , Sánchez‐Puelles J. M. , Molina M. , Nombela C.
Published: August 2002

The choline‐binding domain (ChoBD) of the carboxy‐terminal region of the Streptococcus pneumoniae amidase LYTA (C‐LYTA) presents a strong affinity for tertiary amines. We report a method for single‐step purification of proteins expressed in the methylotrophic yeast Pichia pastoris based on the fusion of C‐LYTA to the protein of interest. We show that C‐LYTA can be efficiently expressed and secreted in this host. Tagged proteins fused to this binding domain can be purified on inexpensive DEAE matrices. It therefore provides a useful system for the purification of recombinant proteins with high specificity suitable for industrial purposes. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 74: 164–171, 2001.