bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystallization kinetics of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) blends
Authors: Shi Yu , Jabarin Saleh A. 
Published: August 2002

AbstractThe crystallization kinetics of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) (PET/PEN) blends were investigated by DSC as functions of crystallization temperature, blend composition, and PET and PEN source. Isothermal crystallization kinetics were evaluated in terms of the Avrami equation. The Avrami exponent (n) is different for PET, PEN, and the blends, indicating different crystallization mechanisms occurring in blends than those in pure PET and PEN. Activation energies of crystallization were calculated from the rate constants, using an Arrhenius‐type expression. Regime theory was used to elucidate the crystallization course of PET/PEN blends as well as that of unblended PET and PEN. The transition from regime II to regime III was clearly observed for each blend sample as the crystallization temperature was decreased. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 23–37, 2001
Kinetic study of olefin polymerization with a supported metallocene catalyst. IV. Comparison of bridged and unbridged catalyst in gas phase
Authors: Chakravarti S. , Ray W. Harmon , Zhang Simon X. 
Published: August 2002

AbstractA kinetic study of ethylene/1‐hexene (E/1‐H) copolymerization is conducted with a supported bridged metallocene catalyst in a gas phase reactor. The investigation into the kinetics of ethylene/1‐hexene copolymerization includes the effects of operational parameters such as the reaction temperature, pressure, and comonomer concentration. On‐line perturbation techniques are implemented to determine key kinetic parameters such as the activation energies for propagation and catalyst deactivation. A comparison of the kinetic parameters and behavior is made between the bridged and a previously studied unbridged catalyst. Finally, a two‐site model is proposed to explain the observed kinetic behavior with changing reaction temperature and comonomer concentration. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1451–1459, 2001
Oil shale solid waste recycling in the development of new silica fillers for elastomeric composites
Authors: Perruso Carlos Renato , Neto Arnaldo Alcover , Neumann Reiner , Nunes Regina Célia Reis , De Araújo Fonseca Marcus Vinícius , Nascimento Regina Sandra Veiga 
Published: August 2002

AbstractThe production of Brazilian shale oil gives rise to 6600 ton/day of a solid waste of retorted shale, and larger amounts of dolomitic waste rock are generated during mining. Two vitreous materials were obtained through the melting of different proportions of these two wastes. By leaching these materials with hydrochloric acid at 90°C, two different kinds of silicas (powder and gel, both amorphous) with specific surface areas reaching up to ∼ 420 m2/g were generated. These silicas were further modified through an Ostwald‐ripening type of treatment in ammonium hydroxide solution at 80°C. The process eliminated almost completely the deleterious micropores. The obtained silicas were evaluated as reinforcing fillers for SBR‐1502. The employment of one of the modified silicas gave rise to a composite with better mechanical properties than those displayed by the one with untreated silica. Scanning electronic microscopic observation disclosed the existence of great morphological differences between these silicas. Apparently, the aging treatment gave rise to the production of better anchoring sites for the elastomer molecules. NMR studies also showed the reduction of the silanol content of the treated silica. The fracture surface of the composite disclosed a good wetting of this silica by the elastomeric matrix. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2856–2867, 2001
Effects of hard‐segment compositions on properties of polyurethane–nitrolignin films
Authors: Zhang Lina , Huang Jin 
Published: August 2002

AbstractSegmented polyurethane (PU) films from castor‐oil‐based PU prepolymer with different hard‐segment compositions and nitrolignin (NL) were synthesized. Diisocyanates (DIs), such as 2,4‐tolylene DI (TDI) and 4,4′‐diphenylmethane DI (MDI), 1,4‐butanediol (BDO) as a chain extender, and trimethanol propane (TMP) as a crosslinker were used to obtain PU films containing NL (UL) which were named as UL–TB for TDI and BDO, UL–TT for TDI and TMP, UL–MB for MDI and BDO, and UL–MT for MDI and TMP, respectively. The mechanical properties and thermal stability of the films were characterized by a tensile test and thermogravimetric analysis, respectively. The MDI‐based UL films exhibited a higher tensile strength (σb) and thermal stability than TDI‐based UL. However, the recoverability of the TDI‐based UL films was better than that of others. The UL films with TMP (UL–TT and UL–MT) had higher σb and lower breaking elongation (ϵb) than the UL films with BDO (UL–TB and UL–MB), caused by enhancement in the crosslinking network of hard segments and microphase separation between soft and hard segments. The values of σb and ϵb of the UL films that contained NL were much higher than those of the PU films, which indicates that the introduction of NL increased the interaction between hard segments by crosslinking. The hydrogen bonding in the UL films was studied by infrared spectroscopy, which indicated that MDI favored the formation of hydrogen bonds, especially in the ordered domain. Differential scanning calorimetry, dynamic mechanical analysis, and wide‐angle X‐ray diffraction indicated that the UL films were compatible as a whole, but microphase separation existed between soft and hard segments and significantly affected the mechanical properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3251–3259, 2001
Flow instability in capillary extrusion of plasticized poly(vinyl chloride)
Authors: Yamaguchi Masayuki 
Published: August 2002

AbstractFlow instability in a capillary extrusion is studied for a high molecular weight, plasticized poly(vinyl chloride) (PVC). The onset of melt fracture correlates with the long time relaxation ascribed to the generation and/or growth of PVC crystallites. An increase in the residence time in the cylinder leads to this long time relaxation and results in the melt fracture, although the apparent shear stress remains constant, irrespective of the residence time. The extrudate temperature and the species of the plasticizer also have a significant influence on the apparatus of the extruded products. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1277–1283, 2001
Improvements of white pine wood properties by impregnation with unsaturated polyesters in admixture with styrene
Authors: Mahmoud A. A. , Eissa A. M. F. , Omar M. S. , El‐Sawy A. A. , Shaaban A. F. 
Published: August 2002

AbstractFour unsaturated polyester resins based on poly(ethyleneglycol‐maleate‐phthalate) (PE) with different bromine contents were used for the impregnation and coating of oven‐dried white pine wood samples in admixture with styrene (St). Curing was affected by the initiator–heat technique by using 0.2 wt % of benzoyl peroxide (Bz2O2). It was found that the use of the four prepared unsaturated polyester/styrene (PE/St) mixtures resulted in the formation of wood plastic combinations (WPC) with a higher percentage retention, higher percentage crosslinking, water repellent effectiveness, and antiswelling efficiency. ASE properties are excellent for wood samples impregnated with resin without bromine. Water absorption was decreased and a good water uptake was obtained by wood samples impregnated by resin of lower bromine content. Compressive strength was increased for all samples, especially for the wood samples impregnated with resin without bromine. The flammability test for the prepared plastics showed that the samples without bromine are classified as burning substance and the other three samples contain bromine are classified as self‐extinguishing samples from ASTM D635‐68T (1956). On the other hand, impregnated wood samples with PE/St mixtures show no fire retardancy after carrying ASTM E160‐50 (1965), whereas coated wood samples with the same mixtures show excellent fire‐retarding properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1410–1416, 2001
Dielectric spectroscopy of conductive polyaniline salt films
Authors: Han Moon Gyu , Im Seung Soon 
Published: August 2002

AbstractDielectric responses of polyaniline (PANI) salt films, made from two different methods, were compared to investigate the effect of a dopant and film‐formation methods on the dielectric properties. One of the film‐formation methods for emeraldine salt was the film‐doping method, and the other, the solution‐doping method. The conductivity relaxation and dielectric properties were measured by a microdielectrometer at 293 K in the frequency range of 1–100,000 Hz. Dielectric spectra were a function of the dopant in the case of the film‐doping method, whereas it was a function of solvent–dopant combinations as well as the dopants in the solution‐doping method. The dielectric responses of film‐doped samples had similar patterns irrespective of the dopants, while those of solution‐doped samples were varied, probably due to different conjugation conditions or/and the conduction mechanism. In the case of film‐doped samples, dielectric loss and permittivity values were increased with decreasing dopant sizes. The dielectric relaxation times were also varied depending on the kind of dopants. The different solvent–dopant combinations led to variation of the dielectric responses in the solution‐doped PANI due to an altered chain structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2760–2769, 2001
Absorption and desorption of liquid water by a superabsorbent polymer: Effect of polymer in the drying of the soil and the quality of certain plants
Authors: Bakass M. , Mokhlisse A. , Lallemant M. 
Published: August 2002

AbstractIn this work, we were interested in the study of the kinetic behavior of the reaction of drying soil representing the Marrakesh region (south of Morocco) in the presence of an superabsorbent polymer. The presence of a polymer in the soil diminished the kinetic drying of the soil, which will have as an application a reduction in water loss in the process of irrigation. The presence of a polymer in the soil enables a complete modification of the kinetic regimes controlling the soil‐drying kinetic. We also realized the first study of the behavior of certain selected plants in the melange of a soil and a polymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 234–243, 2002
Formation and structure of high mechanical performance fibers. II. Flexible polymers
Authors: Kikutani Takeshi 
Published: August 2002

AbstractConditions for the formation of high performance fibers from flexible and semi‐flexible polymers are reviewed in terms of the chemical structure, chain conformation, super structure, and modeling. Small cross‐sectional area and extended conformation are important factors for designing the high‐performance polymers. Tensile modulus decreases significantly by only a small contraction of main chain from the planar zigzag conformation. Model calculation for the estimation of the ultimate tensile strength includes the evaluations of bond strength and the kinetic theory for rupture of primary and secondary bonds. Presence of defects such as chain ends are also considered. Macroscopic defects can be evaluated based on Griffith's theory. Drawability, which is important for the production of high performance fibers, can be improved through the control of entanglement. Experimental and industrial procedures for the production of high performance fibers such as gel spinning of polyethylene, pressurized drawing of polyoxymethylene, controlled shrinkage and drawing of polytetrafluoroethylene, and solid state co‐extrusion of high molecular weight poly(ethylene terephthalate) are also reviewed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 559–571, 2002
Does electrofishing harm freshwater pearl mussels?
Authors: Hastie Lee C. , Boon Philip J. 
Published: August 2002

Abstract1. Two experiments were carried out in a Scottish river to test the effects of electrofishing on endangered freshwater pearl mussels (Margaritifera margaritifera).2. In the first experiment, two areas of mussel bed were marked out as treatment and control sites and the former was electrofished using standard equipment. The mussels were examined 10 min, 24 h and 35 days after treatment and their shell valve closure responses, burrowing capabilities and gravidities were recorded as signs of normal ‘functioning’.3. In the second experiment, individual mussels were marked as treatments and controls and the former were electrofished. These mussels were examined as before.4. No mortalities occurred and no significant differences in ‘functioning’ between treatments and controls were observed in either experiment.5. Since no measurable treatment effect could be demonstrated, it appears that electrofishing did not adversely affect the short‐term survival of M. margaritifera. Copyright © 2001 John Wiley & Sons, Ltd.
Assessing adult Trichoptera communities of small streams: a case study from Charnwood Forest, Leicestershire, UK
Authors: Greenwood M.T. , Bickerton M.A. , Petts G.E. 
Published: August 2002

Abstract1. Adult caddisflies were collected using non‐attracting Malaise traps at four sites on a small headwater stream from May to November 1990. Sites S1 and S2 were most natural and upstream of a reservoir; where S3 was located in the bypass channel, and S4, downstream.2. The flight period for each species is recorded to provide baseline data. Flight activity patterns fall into two groupings: (a) species with a flight activity of 3–4 months, and (b) those species with a short flight period of up to 6 weeks.3. Sixty‐one species from 15 families were collected, including the endangered Red Data Book species Tinodes pallidulus McLachlan.4. Significant differences in community parameters are shown among all sites, many species apparently having local catchment areas. The influence of artificial habitats, the open bypass channel and adjacent reservoir, is clearly demonstrated.5. The data illustrate the potential of using adult caddisflies in conservation assessment of small streams. Working with adults is taxonomically rigorous and they are useful bioindicators of the environmental quality of the valley floor corridor. Copyright © 2001 John Wiley & Sons, Ltd.
Cellular events at the onset of physiological root resorption in rabbit deciduous teeth
Authors: Sahara Noriyuki 
Published: August 2002

AbstractFor elucidation of how physiological root resorption of deciduous teeth is initiated, the cellular events that occur surrounding the root of rabbit deciduous teeth before and at the onset of physiological root resorption were observed by means of light and electron microscopy. In addition, the cytodifferentiation of odontoclasts during the initial phase of this root resorption was evaluated by histochemical staining of tartrate‐resistant acid phosphatase (TRAP) activity as a marker odontoclasts and their precursors. The present investigation was focused on the physiological root resorption of the deciduous lower second molar of rabbits from Day 0–5 postnatally. At birth, the deciduous molar had not erupted yet, and no TRAP‐positive cell could be found surrounding the tissue adjacent to the root of the deciduous tooth. TRAP‐positive mononuclear cells were initially detected in the coronal portion of the dental follicle of the permanent tooth at Day 1 postnatally. Ultrastructurally, these mononuclear cells had moderate numbers of mitochondria and short‐strand rough endoplasmic reticulum, as well as scattered free ribosomes throughout their cytoplasm. TRAP‐positive mononuclear cells then appeared in the cementoblast layer immediately adjacent to the surface of the deciduous roots. These mononuclear cells projected cytoplasmic extensions between the cementoblasts and made contact with the cementum. At that time, cell–cell contact was frequently observed between these mononuclear cells and cementoblasts. During 3–5 days postnatally, the number of TRAP‐positive multinucleate odontoclasts on the root surface gradually increased. They had well‐developed ruffled borders and made typical resorption lacunae on the root surface of the deciduous tooth. During this early postnatal period, neither inflammatory cells nor necrotic tissue could be observed surrounding the deciduous root. This study demonstrates that the dental follicle of the permanent tooth as well as the connective tissue adjacent to the deciduous root might play important role in site‐ and time‐specific recruitment, development, and activation of odontoclasts before and at the onset of physiological root resorption. Anat Rec 264:387–396, 2001. © 2001 Wiley‐Liss, Inc.
Developmental pattern of ANF gene expression reveals a strict localization of cardiac chamber formation in chicken
Authors: Houweling Arjan C. , Somi Semir , Van Den Hoff Maurice J.B. , Moorman Antoon F.M. , Christoffels Vincent M. 
Published: August 2002

AbstractIn mouse, atrial natriuretic factor (ANF) gene expression was shown to be a marker for chamber formation within the embryonic heart. To gain insight into the process of chamber formation in the chicken embryonic heart, we analyzed the expression pattern of cANF during development. We found cANF to be specifically expressed in the myocardium of the morphologically distinguishable atrial and ventricular chambers, similar to ANF in mouse. cANF expression was never detected in the myocardium of the atrioventricular canal (AVC), inner curvature, and outflow tract (OFT), which is lined by endocardial cushions. Expression was strictly excluded from the interventricular myocardium and most proximal part of the bundle branches, as identified by the expression of Msx‐2, whereas the rest of the bundle branches, trabeculae, and surrounding working myocardium did express cANF. The myocardium that forms de novo within the cushions after looping did not express cANF. At HH9 cANF expression was first observed in a subset of cardiomyocytes, which was localized ventrally in the fused heart tube and laterally in the unfused cardiac sheets. Together, these results show that cANF expression can be used to distinguish differentiated chamber (working) myocardium, including the peripheral ventricular conduction system, from embryonic myocardium. We conclude that differentiation of chamber myocardium takes place already at HH9 at the ventral side of the linear heart tube, possibly preceded by latero‐medial signals in the unfused cardiac sheets. Anat Rec 266:93–102, 2002. © 2002 Wiley‐Liss, Inc.
Kidney of giraffes
Authors: Maluf N.S.R. 
Published: August 2002

AbstractThis study focuses on certain aspects of the renal structure of the giraffe, with some implications as to its function. About 4,000 collecting ducts open at the truncated end of a curved crest that juts into the renal pelvis as the inner medulla (IM). Extensions of the pelvis pass between the medullary (MP) and vascular (VP) processes almost to the corticomedullary border. The MPs contain an IM and an outer medulla (OM) containing clusters of capillaries (vascular bundles). The VPs contain the interlobar arteries and veins. All of the IM and almost all of the OM, with its vascular bundles, are bathed with pelvic urine. The cortex comprises 63% of the parenchyma. The OM has nine times the mass of the IM. The IM comprises 4% of the parenchyma. The ratio of mass of the adult cortex to the medulla is 1.7:1.0, and the number of glomeruli per kidney is 6.6 × 106. Glomerular mass is 6.2–6.7% of renal mass in the adult and 5.2% in the 6‐month‐old calf. The dimensions of the glomerular capsules are the same across the thickness of the cortex. Every terminal collecting duct drains an estimated 1,650 nephrons. In the adult giraffe the ratio of thickness of the muscularis of the main renal artery (RA) to its diameter is 0.117 (right RA) and 0.132 (left RA). These ratios are close to those in rhinoceros and ox but greater than in man. The visceral arteries (celiac, anterior mesenteric, and renal) have about the same muscularis : diameter ratio. Giraffes have arterial hypertension, but atherosclerosis is apparently absent and serum lipid fractions are low. Anat Rec 267:94–111, 2002. © 2002 Wiley‐Liss, Inc.
New fossil hominid calvaria from Indonesia—Sambungmacan 3
Authors: Márquez Samuel , Mowbray Kenneth , Sawyer G J , Jacob Teuku , Silvers Adam 
Published: August 2002

AbstractA morphologically distinct partial calvaria of Homo cf. erectus from Java, Indonesia is described. The fossil hominid Sambungmacan 3 (Sm 3) was first discovered in 1977 from the banks of the Solo River near the village of Poloyo, Sambungmacan district, in central Java. It was later recovered in a New York City natural history establishment in 1999 and quickly returned to the Indonesian authorities. Examination of Sm 3 shows that the calvaria is well preserved with only portions of the cranial base missing. The most striking characteristics of Sm 3 include: the presence of a vertically rising forehead, more open occipital/nuchal and frontal angles, a more globular vault, and a cranial capacity within the Homo erectus range. Most notably absent in Sm 3 are a number of the classic characters attributed to Homo erectus, such as a strongly expressed angular torus and a continuous supratoral sulcus. The absence of such characters would normally place the calvaria outside the range of Homo erectus (sensu stricto), however, overall quantitative and qualitative morphological assessments of Sm 3 place it within the Homo erectus spectrum. The combination of the morphological characters in Sm 3 may be interpreted in several ways: 1.) the known cranial variation of H. erectus from Indonesia and China is extended; 2.) this calvaria shows evidence of evolutionary change within H. erectus; or 3.) more than one species of Homo existed in the (presumed) Middle Pleistocene of Java.) Anat Rec 262:344–368, 2001. © 2001 Wiley‐Liss, Inc.