bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal degradation of flax: The determination of kinetic parameters with thermogravimetric analysis
Authors: Van De Velde K. , Kiekens P.
Published: August 2002

The thermal degradation of flax was investigated with thermogravimetric analysis. The flax used for these experiments underwent different stages of retting or, in one case, boiling. The most retted type of flax was also chemically treated to obtain elementary fibers. These samples were all tested in dynamic and isothermal runs after careful sample preparation. The resulting thermograms were analyzed and later used to calculate the kinetic parameters of cellulose degradation. These kinetic parameters included reaction constants and activation energies. A clear difference in the various tested types of flax was observed through a comparison of these values, and an explanation for these differences was suggested. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2634–2643, 2002
Structure and properties of injection‐molded polypropylenes with different molecular weight distribution and tacticity characteristics
Authors: Fujiyama Mitsuyoshi , Kitajima Yoshiyuki , Inata Hitoshi
Published: August 2002

Two series of polypropylenes with different molecular weight distribution and tacticity characteristics were injection molded into flexural test specimens by varying cylinder temperature and the effects of the molecular weight distribution and tacticity on the structure and properties of the moldings were studied. Measured propertied were flexural modulus, flexural strength, heat distortion temperature, Izod impact strength, and mold shrinkage and structures studied were crystallinity, the thickness of skin layer, a*‐axis‐oriented component fraction and crystalline orientation functions. The relations between the structures and properties were also studied. It was found that the molecular weight distribution and tacticity characteristics affect the properties mainly through the molecular orientation and crystallinity, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2142–2156, 2002
Cure reaction for modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide
Authors: Boey F. Y. C. , Song X. L. , Rath S. K. , Yue C. Y.
Published: August 2002

The glass‐transition temperature as a function of curing conversion for a modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide (BMI) resin was investigated at different temperature regimes and modeled using a modified Di Benedetto equation. Although the relationship between the glass‐transition temperature and conversion of the BMI system conforms to the Di Benedetto equation for α < 0.6 and at lower cure temperatures, at higher cure temperatures the results deviated significantly from the equation; thus, it was an inadequate model for the system. Fourier transform IR analysis showed that the major crosslinking reactions did not occur during cure for the modified BMI at and below 150°C. However, as the cure temperature was increased, the crosslinking reactions responsible for 3‐dimensional network structures became more dominant. At 190°C the CNCstretch vibration of the uncured maleimide ring converted into succinimide rings in the curing process. Simultaneously, a decrease was observed for the absorbance bands of  CHbending (maleimide). The higher cure temperatures induced a significantly faster initial crosslinking rate and also resulted in a shorter period of time after which further crosslinking was retarded, because the increase in the crosslinks also physically slowed further crosslinking activity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 227–235, 2002
Chemical modification of hemp, sisal, jute, and kapok fibers by alkalization
Authors: Mwaikambo Leonard Y. , Ansell Martin P.
Published: August 2002

Plant fibers are rich in cellulose and they are a cheap, easily renewable source of fibers with the potential for polymer reinforcement. The presence of surface impurities and the large amount of hydroxyl groups make plant fibers less attractive for reinforcement of polymeric materials. Hemp, sisal, jute, and kapok fibers were subjected to alkalization by using sodium hydroxide. The thermal characteristics, crystallinity index, reactivity, and surface morphology of untreated and chemically modified fibers have been studied using differential scanning calorimetry (DSC), X‐ray diffraction (WAXRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), respectively. Following alkalization the DSC showed a rapid degradation of the cellulose between 0.8 and 8% NaOH, beyond which degradation was found to be marginal. There was a marginal drop in the crystallinity index of hemp fiber while sisal, jute, and kapok fibers showed a slight increase in crystallinity at caustic soda concentration of 0.8–30%. FTIR showed that kapok fiber was found to be the most reactive followed by jute, sisal, and then hemp fiber. SEM showed a relatively smooth surface for all the untreated fibers; however, after alkalization, all the fibers showed uneven surfaces. These results show that alkalization modifies plant fibers promoting the development of fiber–resin adhesion, which then will result in increased interfacial energy and, hence, improvement in the mechanical and thermal stability of the composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2222–2234, 2002
Fine polystyrene latexes with reactive poly(ethylene oxide) –poly(propylene oxide)–poly(ethylene oxide) triblock macrosurfactants in modified miniemulsion polymerization
Authors: Kim Jin‐Woong , Ko Ji‐Young , Park Jin‐Gyu , Jun Jung‐Bae , Chang Ih‐Seop , Suh Kyung‐Do
Published: August 2002

Polystyrene latexes were produced via a newly accessible miniemulsion polymerization where reactive poly(ethylene oxide)–poly(propylene oxide) –poly(ethylene oxide) triblock macrosurfactants were used to impart the interfacial activity during the emulsification and the reactivity in the polymerization. Through atomic force microscopy studies, it was found that the polystyrene latexes produced were extremely small to about 50 nm in a proper experimental condition, and covered richly with poly(ethylene oxide) groups. The polystyrene latexes were expected to have great applicability in the production of structured latex films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 328–332, 2002
Influence of die angles on pressure drop during extrusion of rubber compound
Authors: Liang Ji‐Zhao
Published: August 2002

The factors affecting pressure losses during extrusion of polymer melts are discussed in the present article. The rheological properties of an unvulcanized rubber compound were examined by using a Monsanto processability tester (MPT) under experimental conditions of temperatures varied 90 to 120°C and shear rates from 102 to 103 s−1. Furthermore, a set of dies with different entry angle (2α) was selected to identify the effects of die angles on pressure losses in capillary extrusion of the sample fluid. It was found that the total pressure drop (ΔP) decreased when 2α < 75 degrees, and then increased with increasing 2α. The ΔP reached the minimum value when 2α is around 75°. It suggests that the natural converging angle of the sample fluid be about 75° under the experimental conditions, according to the research results presented in previous work. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1150–1154, 2001
Poly(lactide‐co‐glycolide) solution behavior in supercritical CO2, CHF3, and CHClF2
Authors: Conway S. E. , Byun H.‐S. , McHugh M. A. , Wang J. D. , Mandel F. S.
Published: August 2002

Cloud point and solution density data between 20 and 100°C and pressures to 3000 bar are presented for poly(lactide) (PLA) and poly(lactide‐co‐glycolide) (PLGAx, where the molar concentration of glycolide in the backbone x ranges from 0 to 50 mol %) in supercritical CO2, CHClF2, and CHF3. PLA dissolves in CO2 at pressures near 1400 bar, in CHF3 at pressures of 500 to 750 bar, and in CHClF2 at pressures of 20–100 bar. As glycolide (GA) is added to the backbone of PLGA, the cloud point pressure increases by 50 bar/(mol GA) in CO2, 25 bar/(mol GA) in CHF3, and by only 2.5 bar/(mol GA) in CHClF2. PLGA50 does not dissolve in CO2 to pressures of 3000 bar whereas it is readily soluble in CHClF2 at pressures as low as 100 bar at 50°C. In comparison, the increases in cloud point pressure with increasing weight average molecular weight (Mw) are only approximately 2.3 bar/(1000 Mw) for PLGA copolymers in CO2. The solution densities with all three SCF solvents range from 1.1 to 1.5 g/cm3 and they vary only by a small amount over the 80°C range used to obtain cloud point data. More than likely, the ability of the acidic hydrogen in CHF3 and CHClF2 to complex with the ester linkage in PLGA makes these better solvents than CO2 especially since any change in favorable energetic interactions is magnified due to the liquid‐like densities exhibited by these SCF solvents. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1155–1161, 2001
Curing and toughening of a styrene‐modified epoxy resin
Authors: Yoon Tae‐Ho , Mcgrath James E.
Published: August 2002

A commercially available epoxy resin (E907) formulated with a viscosity‐reducing styrene monomer and several additives was subjected to thermal cure studies and mechanical property measurements. Thermoplastic poly(arylene ether sulfone) (PES) and poly(arylene ether phosphine oxide) (PEPO) with reactive amine or hydroxyl end groups were utilized to toughen and co‐cure with the system. The cure cycle was optimized and the networks were analyzed via differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analyzer, scanning electron microscopy, sol–gel extractions, and fracture toughness. A model epoxy resin was prepared from a tetrafunctional epoxy, e.g., MY722, difunctional EPON828, styrene monomer, and benzoyl peroxide initiator (BPO), and was evaluated as a control to assess the possible role of the styrene monomer. The optimized cure cycle for E907 was 6 h at 93°C, followed by a postcure of 2 h at 204°C. The fracture toughness of E907 was increased only marginally with PES and PEPO. In contrast, the model epoxy resin demonstrated a positive effect due to the styrene monomer and BPO and exhibited significantly increased fracture toughness with PES modification. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1504–1513, 2001
Study of fusion percolation thresholds of rigid PVC compounds
Authors: Chen Cheng‐Ho , Mao Ching‐Feng , Lo Yu‐Wen
Published: August 2002

Rigid poly(vinyl chloride) (PVC), PVC/chlorinated polyethylene (CPE), and PVC/CPE/oxidized polyethylene (OPE) compounds were prepared in a Haake torque rheometer. The fusion percolation thresholds (FPTs) of these compounds were defined and compared. Moreover, the fusion curves of these compounds were illustrated and compared. A higher processing temperature resulted in a shorter fusion time and a lower FPT. For PVC/CPE compounds, a higher concentration of CPE could decrease the FPT and promote PVC particles to fuse together easily. Meanwhile, in the beginning of the fusion process, the interaction between a higher concentration of OPE and calcium stearate in PVC/OPE compounds could also promote an easy fusion of the PVC particles. For PVC/CPE/OPE compounds, the synergistic interaction among CPE, OPE, and calcium stearate resulted in the shortest fusion time and the lowest FPT. The FPTs of rigid PVC samples were strongly dependent on not only the processing conditions but also the formulations of the samples. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3022–3029, 2001
Fabrication of 6FDA‐durene polyimide asymmetric hollow fibers for gas separation
Authors: Wang Rong , Cao Yiming , Vora Rohit , Tucker Robert J.
Published: August 2002

We have developed defect‐free asymmetric hexafluoro propane diandydride (6FDA) durene polyimide (6FDA‐durene) hollow fibers with a selectivity of 4.2 for O2/N2 and a permeance of 33.1 ×10−6 cm3 (STP)/cm2‐s‐cmHg for O2. These fibers were spun from a high viscosity in situ imidization dope consisting of 14.7% 6FDA‐durene in a NMP solvent and the inherent viscosities (IV) of this 6FDA‐durene polymer was 0.84 dL/g. Low IV dopes cannot produce defect‐free hollow fibers, indicating a 6FDA‐durene spinning dope with a viscosity in the region of chain entanglement seems to be essential to yield hollow fibers with minimum defects. The effects of spinning parameters such as shear rates within a spinneret and bore fluids as well as air gap on gas separation performance were investigated. Experimental data demonstrate that hollow fibers spun with NMP/H2O as the bore liquid have higher permeances and selectivities than those spun with glycerol as the bore liquid because the former has a relatively looser inner skin structure than the latter. In addition, the selectivity of hollow fibers spun with NMP/H2O as the bore liquid changes moderately with shear rate, while the selectivity of hollow fibers spun with glycerol are less sensitive to the change of shear rate. These distinct behaviors are mainly attributed to the different morphologies generated by different bore fluids. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2166–2173, 2001
Graft copolymerization ofN‐isopropylacrylamide on styrene‐butadiene‐styrene block copolymer
Authors: Lee Wen‐Fu , Chen Ying‐Jou
Published: August 2002

Graft polymerization ofN‐isopropylacrylamide (NIPAAm) onto styrene‐butadiene‐styrene (SBS) block copolymer using benzoyl peroxide was studied to improve the water absorptivity and thermosensitivity of SBS. The influence of various grafting reaction factors on the conversion of NIPAAm and the grafting percentage of SBS‐g‐NIPAAm were also investigated in the study. The experimental results showed that the conversion of SBS‐g‐NIPAAm was enhanced as the monomers of NIPAAm were increased. The maximum conversion of SBS‐g‐NIPAAm was observed when the molar ratio of NIPAAm to butadiene was 1.25. In addition, increasing the reaction time enhanced the conversion of SBS‐g‐NIPAAm; the maximum grafting percentage was obtained with a 4‐h reaction. The optimal concentration of the initiator was 3 × 10−4mol/20 mL of toluene, and the grafting reaction occurred at over 65°C. The test results of the hydrophilicity of the grafted membranes showed that the hydrophilicity and thermosensitivity were significantly enhanced by grafting NIPAAm onto SBS. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2641–2650, 2001
Sorption, diffusion, and pervaporation separation of water–acetic acid mixtures through the blend membranes of sodium alginate and guar gum‐grafted‐polyacrylamide
Authors: Toti Udaya S. , Kariduraganavar Mahadevappa Y. , Soppimath Kumaresh S. , Aminabhavi Tejraj M.
Published: August 2002

Nonporous homogeneous dense membranes were prepared from the blends of sodium alginate (Na–Alg) with guar gum‐grafted polyacrylamide (GG‐g‐PAAm) in the ratios of 3 : 1 and 1 : 1 and these were tested for the pervaporation separation of water–acetic acid mixtures at 30°C. Blend compatibility was studied in solution by measuring the viscosity and the speed of sound. Membranes were crosslinked by glutaraldehyde. The GG‐g‐PAAm polymer and the crosslinked blend membranes were characterized by Fourier transform infrared spectra. High separation selectivity was exhibited by the pure Na–Alg membrane for water–acetic acid (HAc) mixtures containing 20 mass % of water. The permeation flux increased with increasing mass percent of water in the feed as well as with an increase in the amount of GG‐g‐PAAm in the blend, but separation selectivity decreased. Sorption selectivity was higher for the Na–Alg membrane than for the blend membranes, but it decreased with increasing mass percent of GG‐g‐PAAm in the blends. Diffusion selectivity values vary systematically with the blend composition, but not with the amount of water in the feed. Diffusion coefficients of the water–HAc mixtures were calculated from Fick's equation using sorption data and compared with those calculated from flux values obtained in pervaporation experiments. The Arrhenius activation parameters were calculated for the 20 mass % of water in the feed using flux and diffusion data obtained at 30, 40, and 50°C. The diffusion and pervaporation results are explained in terms of solution–diffusion concepts. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 259–272, 2002
Influence of casting substrate on the surface free energy of various polyesters
Authors: Smith R. , Pitrola R.
Published: August 2002

The surface free energies of various polyester surfaces have been determined from contact angle measurements using several liquid types. The geometric mean, the harmonic mean, and Fowkes' methods for obtaining the components of surface free energy have been compared for poly(L‐lactic acid) (PLLA), poly(DL‐lactic acid) (PDLLA), poly(hydroxybutyrate) (PHB), and poly(hydroxybutyrate‐hydroxyvalerate) (PHB–HV) copolymers. Polymer films were obtained by solution casting onto a number of smooth substrates, ranging from high‐energy surfaces (aluminum, mercury, glass, and freshly cleaved mica) to low‐energy surfaces [poly(ethyleneterephthalate) (PET), polytetrafluoroethylene (PTFE), and air]. Results show that the dispersion and polar surface free energy components of polyester surfaces cast against high surface energy (hydrophilic) substrates decrease with aging time toward a stable value. However, when cast against low surface energy substrates, the surface free energy of the resulting polymer/substrate‐contacting surface was independent of aging time. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 997–1008, 2002
The use of biomarkers in aquatic biomonitoring: the example of esterases
Authors: Pretti Carlo , Cognetti‐Varriale Anna Maria
Published: August 2002

1. The term biomarker refers to the physiological, biochemical, and histological changes used as indicators of exposure to chemical contaminants and/or of its effects at the suborganismal or organismal level. Recently the development of sensitive biochemical markers for monitoring environmental quality in aquatic ecosystems has raised a great deal of interest.

2. Selected biochemical markers measured in feral organisms can provide sensitive indexes, or early warning signals, of potential ecosystem degradation caused by contaminants. Compared with chemical residue analysis, biomarkers have the advantage of measuring the stress on the organism, thus being more biologically relevant.

3. Some of the most frequently used biomarkers in aquatic biomonitoring in different countries are briefly described.

4. The use of cholinesterase activity as a biomarker of pesticide exposure for biomonitoring in estuarine areas is also given as an example. Copyright © 2001 John Wiley & Sons, Ltd.
Osteoclast induction in periodontal tissue during experimental movement of incisors in osteoprotegerin‐deficient mice
Authors: Oshiro Takahiro , Shiotani Aya , Shibasaki Yoshinobu , Sasaki Takahisa
Published: August 2002

Osteoprotegerin (OPG) is a novel secreted member of the tumor necrosis factor (TNF) receptor superfamily that negatively regulates osteoclastogenesis. The receptor activator of the NFKB ligand (RANKL) is one of the key regulatory molecules in osteoclast formation and binds to OPG. In this study, it was suggested that OPG and RANKL are involved in alveolar bone remodeling during orthodontic tooth movement. We examined RANKL localization and osteoclast induction in periodontal tissues during experimental movement of incisors in OPG‐deficient mice. To produce orthodontic force, an elastic band was inserted between the upper right and left incisors for 2 or 5 days, and the dissected maxillae were examined for cytochemical and immunocytochemical localization of tartrate‐resistant acid phosphatase (TRAP), vacuolar‐type H+‐ATPase, and RANKL. Compared to wild‐type OPG (+/+) littermates, TRAP‐positive multinucleated cells were markedly induced in the periodontal ligament (PDL) on the compressed side and in the adjacent alveolar bone of OPG‐deficient mice. These multinucleated cells exhibited intense vacuolar‐type H+‐ATPase along the ruffled border membranes. Because of accelerated osteoclastic resorption in OPG‐deficient mice, alveolar bone was severely destroyed and partially perforated at 2 and 5 days after force application. In both wild‐type and OPG‐deficient mice, RANKL expression became stronger at 2 and 5 days after force application than before force application. There was no apparent difference in intensity of RANKL expression between OPG (+/+) littermates and OPG‐deficient mice. In both wild‐type and OPG‐deficient mice, expression of RANKL protein was detected in osteoblasts, fibroblasts, and osteoclasts mostly located in resorption lacunae. These results suggest that during orthodontic tooth movement, RANKL and OPG in the periodontal tissues are important determinants regulating balanced alveolar bone resorption. Anat Rec 266:218–225, 2002. © 2002 Wiley‐Liss, Inc.
Missing Omo L338y‐6 occipital‐marginal sinus drainage pattern: Ground sectioning, computer tomography scanning, and the original fossil fail to show it
Authors: Holloway Ralph L. , Yuan Michael S. , Broadfield Douglas C. , Degusta David , Richards Gary D. , Silvers Adam , Shapiro Jill S. , White Tim D.
Published: August 2002

The Omo L338y‐6 occipital region has been recently studied by White and Falk (1999), who claim that it shows a readily identifiable enlarged left occipital‐marginal sinus (O/M). These observations are contrary to the direct observations of previous investigators (Rak and Howell, 1978; Kimbel, 1984; Holloway, 1981; Holloway, 1988). White and Falk (1999) further argue that the presence of this enlarged O/M strongly suggests that the Omo L338y‐6 hominid was indeed a “robust” Australopithecus. We used direct sectioning and CT scanning to analyze magnified sections of a high‐quality first‐generation cast of the newly cleaned original fossil. These methods fail to show any evidence of a morphological landmark that can be interpreted as an enlarged O/M, either as an eminence or a sulcus. In contrast, the same techniques used with both SK 1585 and OH5 (“robust” Australopithecus with an enlarged O/M) show extremely visible and palpable enlarged O/M's. Examination of the original Omo fossil confirms that it lacks an O/M. This evidence clearly shows that an enlarged O/M cannot be identified on either the original fossil or a first‐generation cast, although this does not rule out the possibility that the Omo L338y‐6 hominid was a “robust” Australopithecus. We believe that the differences between observers regarding this feature are most probably due to displacement caused by a crack and the different source materials employed, i.e., the difference between a first‐generation cast of the original fossil and a third‐ or fourth‐generation cast of the endocast made two decades ago. Anat Rec 266:249–257, 2002. © 2002 Wiley‐Liss, Inc.
Alkaline phosphatase activity in whitefly salivary glands and saliva
Authors: Funk C. Joel
Published: August 2002

Alkaline phosphatase activity was histochemically localized in adult whiteflies (Bemisia tabaci B biotype, syn. B. argentifolii) with a chromogenic substrate (5‐bromo‐4‐chloro‐3‐indolylphosphate) and a fluorogenic substrate (ELF‐97). The greatest amount of staining was in the basal regions of adult salivary glands with additional activity traced into the connecting salivary ducts. Other tissues that had alkaline phosphatase activity were the accessory salivary glands, the midgut, the portion of the ovariole surrounding the terminal oocyte, and the colleterial gland. Whitefly nymphs had activity in salivary ducts, whereas activity was not detected in two aphid species (Rhodobium porosum and Aphis gossypii). Whitefly diet (15% sucrose) was collected from whitefly feeding chambers and found to have alkaline phosphatase activity, indicating the enzyme was secreted in saliva. Further studies with salivary alkaline phosphatase collected from diet indicated that the enzyme had a pH optimum of 10.4 and was inhibited by 1 mM cysteine and to a lesser extent 1 mM histidine. Dithiothreitol, inorganic phosphate, and ethylenediaminetetraacetic acid (EDTA) also inhibited activity, whereas levamisole only partially inhibited salivary alkaline phosphatase. The enzyme was heat tolerant and retained approximately 50% activity after a 1‐h treatment at 65°C. The amount of alkaline phosphatase activity secreted by whiteflies increased under conditions that stimulate increased feeding. These observations indicate alkaline phosphatase may play a role during whitefly feeding. Arch. Insect Biochem. Physiol. 46:165–174, 2001. Published 2001 Wiley‐Liss, Inc.
Activity of insulin growth factors and shrimp neurosecretory organ extracts on a lepidopteran cell line
Authors: Hatt P.J. , Liebon C. , Morinière M. , Oberlander H. , Porcheron P.
Published: August 2002

Ecdysteroids, or molting hormones, have been proven to be key differentiation regulators for epidermal cells in the postembryonic development of arthropods. Regulators of cell proliferation, however, remain largely unknown. To date, no diffusible insect peptidic growth factors have been characterized. Molecules structurally related to insulin have been discovered in insects, as in other eucaryotes. We developed in vitro tests for the preliminary characterization of potential growth factors in arthropods by adapting the procedures designed to detect such factors in vertebrates to an insect cell line (IAL‐PID2) established from imaginal discs of the Indian meal moth. We verified the ability of these tests to measure the proliferation of IAL‐PID2 cells. We tested mammalian insulin and insulin‐like growth factors (IGF‐I, IGF‐II). Following an arrest of cell proliferation by serum deprivation, IGF‐I and IGF‐II caused partial resumption of the cell cycle, evidenced by DNA synthesis. In contrast, the addition of 20‐hydroxyecdysone arrested the proliferation of the IAL‐PID2 cells. The cell line was then used in a test for functional characterization of potential growth factors originating from the penaeid shrimp,Penaeus vannamei. Crude extracts of neurosecretory and nervous tissues, eyestalks, and ventral neural chain compensated for serum deprivation and stimulated completion of mitosis. Arch. Insect Biochem. Physiol. 34:313–328, 1997. © 1997 Wiley‐Liss, Inc.
Large granular lymphocytic (LGL) leukemia in rats exposed to intermittent 60 Hz magnetic fields
Authors: Anderson L.E. , Morris J.E. , Miller D.L. , Rafferty C.N. , Ebi K.L. , Sasser L.B.
Published: August 2002

An animal model for large granular lymphocytic (LGL) leukemia in male Fischer 344 rats was utilized to determine whether magnetic field exposure can be shown to influence the progression of leukemia. We previously reported that exposure to continuous 60 Hz, 1 mT magnetic fields did not significantly alter the clinical progression of LGL leukemia in young male rats following injection of spleen cells from donor leukemic rats. Results presented here extend those studies with the following objectives: (a) to replicate the previous study of continuous 60 Hz magnetic field exposures, but using fewer LGL cells in the inoculum, and (b) to determine if intermittent 60 Hz magnetic fields can alter the clinical progression of leukemia. Rats were randomly assigned to four treatment groups (18/group) as follows: (1) 1 mT (10 G) continuous field, (2) 1 mT intermittent field (off/on at 3 min intervals), (3) ambient controls ( <  0.1 μT), and (4) positive control (5 Gy whole body irradiation from cobalt‐60 four days prior to initiation of exposure). All rats were injected intraperitoneally with 2.2 × 106 fresh, viable LGL leukemic spleen cells at the beginning of the study. The fields were activated for 20 h per day, 7 days per week, and all exposure conditions were superimposed over the natural ambient magnetic field. The rats were weighed and palpated for splenomegaly weekly. Splenomegaly developed 9–11 weeks after transplantation of the leukemia cells. Hematological evaluations were performed at 6, 8, 10, 12, 14, and 16 weeks of exposure. Peripheral blood hemoglobin concentration, red blood cells, and packed cell volume declined, and total white blood cells and LGL cells increased dramatically in all treatment groups after onset of leukemia. Although the positive control group showed different body weight curves and developed signs of leukemia earlier than other groups, differences were not detected between exposure groups and ambient controls. Furthermore, there were no overall effects of magnetic fields on splenomegaly or survival in exposed animals. In addition, no significant and/or consistent differences were detected in hematological parameters between the magnetic field exposed and the ambient control groups. Bioelectromagnetics 22:185–193, 2001. © 2001 Wiley‐Liss, Inc.
Control of retinal growth and axon divergence at the chiasm: lessons from Xenopus
Authors: Mann Fanny , Holt Christine E.
Published: August 2002

Metamorphosis in frogs is a critical developmental process through which a tadpole changes into an adult froglet. Metamorphic changes include external morphological transformations as well as important changes in the wiring of sensory organs and central nervous system. This review aims to provide an overview on the events that occur in the visual system of metamorphosing amphibians and to discuss recent studies that provide new insight into the molecular mechanisms that control changes in the retinal growth pattern as well as the formation of new axonal pathways in the central nervous system. BioEssays 23:319–326, 2001. © 2001 John Wiley & Sons, Inc.
Histone acetylation beyond promoters: long‐range acetylation patterns in the chromatin world*
Authors: Forsberg E. Camilla , Bresnick Emery H.
Published: August 2002

Histone acetylation is an important regulatory mechanism that controls transcription and diverse nuclear processes. While great progress has been made in understanding how localized acetylation and deacetylation control promoter activity, virtually nothing is known about the consequences of acetylation throughout entire chromosomal regions. An increasing number of genes have been found to reside in large chromatin domains that are controlled by regulatory elements many kilobases away. Recent studies have shown that broad histone acetylation patterns are hallmarks of chromatin domains. The purpose of this review is to discuss how such patterns are established and their implications for regulating gene expression. BioEssays 23:820–830, 2001. © 2001 John Wiley & Sons, Inc.
Three sons of fortune: early embryogenesis, evolution and ecology of nematodes
Authors: Schierenberg Einhard
Published: August 2002

Comparative analysis of nematode development has revealed considerable variations in how the fates of embryonic cells are specified. Such early variations seem enigmatic as they do not influence the resultant structure or performance of the emerging animal. Three different nematode species are used to consider why alternative ways to reach the same goal may have been established during evolution and why early steps of embryogenesis are particularly variable. A scenario is sketched with a shift from late to early cell specification, along with an increase in maternal contribution and developmental tempo and a decrease in regulative potential expressing different developmental strategies. Future studies of larger numbers of species are needed to assess the extent of such variations and to understand more fully the under lying mechanisms, rules and driving forces. BioEssays 23:841–847, 2001. © 2001 John Wiley & Sons, Inc.
Effects of DRL and DRL combined with response cost on perseverative verbal behavior of an adult with mental retardation and obsessive compulsive disorder
Authors: Kostinas George , Scandlen Alison , Luiselli James K.
Published: August 2002

Although there has been increased interest in the identification and diagnosis of obsessive compulsive disorder (OCD) in people who have developmental disabilities, clinical research has been reported infrequently. The present single‐case study evaluated the effects from systematic behavioral intervention with a 26‐year‐old man who had moderate mental retardation, OCD, and exhibited perseverative verbalizations. Verbalizations were reduced when the man gained access to preferred activities contingent upon a low response frequency (DRL: differential reinforcement of low‐rate responding). The behavior was reduced further when a DRL contingency was implemented in the form of a response cost procedure. The implications of these findings for the treatment of OCD in people with developmental disabilities are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
New structural insights from Raman spectroscopy of proteins and their assemblies
Authors: Thomas George J.
Published: August 2002

Protein structure and stability are sensitive to and dependent on the local interactions of amino acid side chains. A diverse and important type of side‐chain interaction is the hydrogen bond. Although numerous hydrogen bonds are resolved in protein 3‐dimensional structures, those of the cysteine sulfhydryl group (S H) are elusive to high‐resolution X‐ray and NMR methods. However, the nature and strength of sulfhydryl hydrogen bonds (SH…X) are amenable to investigation by Raman spectroscopy. The power of the Raman method for characterizing SH…X interactions is illustrated by resolving the Raman SH stretching band for each of the eight cysteines per 666‐residue subunit in the trimeric tailspike of icosahedral bacteriophage P22. The Raman sulfhydryl signatures of the wild‐type tailspike and eight single‐site cysteine to serine mutants reveal a heretofore unrecognized diversity of SH hydrogen bonds in a native protein. The use of Raman spectroscopy to identify the non‐hydrogen‐bonded state of the tyrosine phenoxyl group is also described. This unusual and unexpected state occurs for all tyrosines in the assembled capsids of filamentous viruses Ff and Pf1. The Raman spectral signature of the non‐hydrogen‐bonded tyrosine phenoxyl, which is characterized by an extraordinary Raman Fermi doublet intensity ratio (I850/I830 = 6.7), extends and refines the existing correlation for hydrogen‐bonded tyrosines. Finally, a novel Raman signature for tryptophan in the Pf3 filamentous virus is identified, which is proposed as diagnostic of “cation–π interaction” involving the guanidinium group of Arg 37 as a cation donor and the indolyl ring of Trp 38 as a π‐electron acceptor. These studies demonstrate the power of Raman spectroscopy for investigating the interactions of key side chains in native protein assemblies. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 214–225, 2002
Selected amino acids protect hybridoma and CHO cells from elevated carbon dioxide and osmolality
Authors: deZengotita Vivian M. , Abston Lisa R. , Schmelzer Albert E. , Shaw Shinie , Miller William M.
Published: August 2002

Elevated pCO2 inhibits cell growth. This growth inhibition is accompanied by a decrease in intracellular pH (pHi), as well as a decrease in glycolysis. Elevated concentrations (mM) of some amino acids have been shown by others to protect cells exposed to two very different environmental stresses: nutrient starvation and hyperosmolality. The fact that many of the amino acids shown to have protective effects against other stresses are transported into the cell through a pHi‐sensitive transporter led us to study the possibility of using these amino acids as protective agents under elevated pCO2. Screening experiments using 5, 15, and 25 mM of each amino acid showed that not all amino acids that protect cells from hyperosmolality protect them from elevated pCO2. Glycine betaine and glycine were chosen for further characterization in both hybridoma and CHO cells. Asparagine and threonine were also tested in hybridoma and CHO cells, respectively. All amino acids tested under 195 mm Hg pCO2/435 mOsm/kg (50% growth inhibition) restored the specific growth rate (μ) in hybridoma cells to that observed under control conditions (40 mm Hg/320 mOsm/kg). Addition of each amino acid resulted in an increase in the consumption rate and intracellular accumulation of that amino acid. In CHO cells, glycine betaine also restored μ to control values, while glycine and threonine partially restored μ. In hybridoma cells, the higher specific antibody productivity obtained at elevated pCO2 was maintained with the lowest amino acid concentration (5 mM). Productivity decreased toward control values with increasing amino acid concentrations. Elevated pCO2 decreased the specific tPA productivity in the CHO cell line studied. Only glycine betaine resulted in a 20% increase in productivity at 195 mm Hg/435 mOsm/kg. With the exception of glycine betaine in hybridoma cells, amino acids did not mitigate the associated pHi decrease of at least 0.2 pH units at 195 mm Hg/435 mOsm/kg. pHi in hybridoma cells under elevated pCO2 in the presence of glycine betaine was about 0.1 pH units below that of control. Amino acids had no effect on the cell size response of hybridoma cells, while they partially offset the increase in CHO cell size at elevated pCO2. Glycine betaine, asparagine, and glycine increased the specific glucose consumption rate observed at 195 mm Hg/435 mOsm/kg (50% of control) to values greater than 70% of control in hybridoma cells. In CHO cells, only glycine betaine increased qglc (by 20%) under elevated pCO2. All amino acids tested improved the cell yield from glutamine at 195 mm Hg/435 mOsm/kg in both cell lines. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 741–752, 2002.
Optimization of maltodextrin hydrolysis by glucoamylase in a batch reactor
Authors: Cepeda E. , Hermosa M. , Ballesteros A.
Published: August 2002

The hydrolysis of maltodextrins (10 DE) by glucoamylase was studied in a batch reactor at temperatures between 40 and 80°C and substrate concentration range from 17 to 300 kg/m−3. The experimental data were fitted to a model including thermal deactivation of the enzyme. In the model, the reaction rate was correlated with an extended Michaelis‐Menten equation including inhibition by product, and the thermal deactivation of glucoamylase was fitted with a first‐order reaction. The dependence of rate parameters on temperature was correlated using the Arrhenius equation. The differential equation of the model was integrated and the optimal enzyme demand and temperature were determined for isothermal operation. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 70–76, 2001.
Assessment of near‐infrared spectral information for rapid monitoring of bioprocess quality
Authors: Vaidyanathan Seetharaman , Arnold S. Alison , Matheson Liliana , Mohan Pankaj , McNeil Brian , Harvey Linda M.
Published: August 2002

Access to real‐time process information is desirable for consistent and efficient operation of bioprocesses. Near‐infrared spectroscopy (NIRS) is known to have potential for providing real‐time information on the quantitative levels of important bioprocess variables. However, given the fact that a typical NIR spectrum encompasses information regarding almost all the constituents of the sample matrix, there are few case studies that have investigated the spectral details for applications in bioprocess quality assessment or qualitative bioprocess monitoring. Such information would be invaluable in providing operator‐level assistance on the progress of a bioprocess in industrial‐scale productions. We investigated this aspect and report the results of our investigation. Near‐infrared spectral information derived from scanning unprocessed culture fluid (broth) samples from a complex antibiotic production process was assessed for a data set that incorporated bioprocess variations. Principal component analysis was applied to the spectral data and the loadings and scores of the principal components studied. Changes in the spectral information that corresponded to variations in the bioprocess could be deciphered. Despite the complexity of the matrix, near‐infrared spectra of the culture broth are shown to have valuable information that can be deconvoluted with the help of factor analysis techniques such as principal component analysis (PCA). Although complex to interpret, the loadings and score plots are shown to offer potential in process diagnosis that could be of value in the rapid assessment of process quality, and in data assessment prior to quantitative model development. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 74: 376–388, 2001.
N‐Removal in a granular sludge sequencing batch airlift reactor
Authors: Beun J. J. , Heijnen J. J. , van Loosdrecht M. C. M.
Published: August 2002

The removal of N‐compounds in the sequencing batch airlift reactor (SBAR) containing granular sludge was studied under conditions of decreased dissolved oxygen (DO). A simulation model was developed to describe and evaluate the effects of several process conditions in the SBAR on N‐removal performance. The model described the experimental data reasonable well. It has been shown that nitrification, denitrification, and removal of chemical oxygen demand (COD) can occur simultaneously in a granular sludge SBR. It has also been shown that the exact location of the autotrophic biomass influences the net N‐removal. The distribution of the autotrophic biomass is influenced by the DO in the reactor. The optimal DO value is expected to be around 40% air saturation. It was shown that storage and subsequent degradation of poly‐β‐hydroxybutyrate (PHB) benefit the denitrification. In particular, PHB is stored in bacteria situated in deeper layers of the granules below where the autotrophic activity occurs, serves as a C‐source for denitrification. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 82–92, 2001.
Golden goose or wild goose? The hunt for the green consumer
Authors: Peattie Ken
Published: August 2002

The green consumer has been the central character in the development of green marketing, as businesses attempt to understand and respond to external pressures to improve their environmental performance. Marketing practitioners and academics are attempting to identify and understand green consumers and their needs, and to develop market offerings that meet these needs. So far there is little consensus about the identity and nature of green consumers, except that they have been something of a disappointment to the marketers who have pursued them. These difficulties perhaps reflect the folly of trying to understand green consumption and green marketing by viewing it as simply a variation on conventional marketing. This article proposes some different ways of looking at green consumption and green marketing, which have the potential to prevent the hunt for the green consumer from deteriorating into a wild goose chase. Copyright © 2001 John Wiley & Sons, Ltd and ERP Environment
Reactions to youth crime: perceptions of accountability and competency*
Authors: Ghetti Simona , Redlich Allison D.
Published: August 2002

Recent changes in juvenile justice policies have stimulated debate among legal professionals and social scientists. As such, public opinion concerning juvenile offenders is an important and timely topic for empirical study. In the present study, respondents read a scenario about a juvenile who committed a crime, and then decided on a sentence and rated perceptions of the juvenile's accountability and legal competence. Four between‐subject factors were manipulated: age of the defendant (11 versus 14 versus 17 years), type of crime (shooting versus arson), crime outcome (victim injured versus died), and time delay between the instigating incident and the crime (immediately versus one day). The type and outcome of the crime were major motivating factors in sentencing decisions and perceptions of legal competence, and, although younger offenders were seen as less accountable and less competent than older offenders, sentence allocation and attitudes towards punishment were not significantly affected by offender age. Copyright © 2001 John Wiley & Sons, Ltd.
A matter of life or death: special considerations and heightened practice standards in capital sentencing evaluations
Authors: Cunningham Mark D. , Reidy Thomas J.
Published: August 2002

Mental health evaluations at capital sentencing represent a complex and specialized arena of practice. The moral culpability focus of capital sentencing is distinct from guilt‐phase considerations of criminal responsibility, and has a specialized literature. Capital violence risk assessment is uniquely oriented to a prison context, relying on past adjustment to incarceration, as well as group statistical data specific to capital offenders and other inmate groups. Personality testing is a more complex consideration in capital sentencing evaluations. The implications of interviewing the defendant, as well as the parameters and documentation of an interview, make full disclosure and informed consent of particular importance. Defense‐ and prosecution‐retained experts are subject to specific ethical vulnerabilities. These are examined in this paper through the lens of current professional standards. Copyright © 2001 John Wiley & Sons, Ltd.
Aberrant muscle between the temporalis and the lateral pterygoid muscles: M. pterygoideus proprius (Henle)
Authors: Akita Keiichi , Shimokawa Takashi , Sato Tatsuo
Published: August 2002

During examination of the positional relationships between the lateral pterygoid and the temporalis muscles and the innervating nerves, an aberrant muscle was observed in three of 66 head halves. The aberrant muscle originated from the medial surface of the anteromedial muscle bundle of the temporalis (Shimokawa et al. 1998, Surg. Radiol. Anat. 20:329–334) and inserted into the inferolateral surface of the lower head of the lateral pterygoid. Due to its location, origin and insertion this aberrant muscle slip is considered to correspond to the pterygoideus proprius described by Henle (1858, Handbuch der Anatomie des Menschen). Based on the innervation findings, the present aberrant muscle might be considered as a remnant muscle bundle between the anteromedial muscle bundle of the temporalis and the lateral pterygoid during differentiation of the lateral masticatory muscle anlage. Clin. Anat. 14:288–291, 2001. © 2001 Wiley‐Liss, Inc.
Children's response to the medical visit for allegations of sexual abuse: maternal perceptions and predicting variables
Authors: Allard‐Dansereau Claire , Hébert Martine , Tremblay Caroline , Bernard‐Bonnin Anne‐Claude
Published: August 2002

This study examined maternal perceptions of their child's response to the medical evaluation for alleged sexual abuse. A total of 50 mothers were interviewed 6 months after a visit to a Child Protection Clinic for a medical evaluation of alleged sexual abuse. The mothers answered a questionnaire on their child's reactions to the medical visit. More than 60% of children were perceived as being reassured about physical integrity. The degree of psychological distress was independent of perpetrator's identity and severity of the abuse. Mothers considered that a hypothetical second visit would generate in their child a level of anxiety that increased with perceived intensity of fear of the examination and decreased with perceived kindness of the physician. These results suggest that the physician's behaviour during the medical evaluation for alleged sexual abuse has an influence on the child's degree of distress that is independent of type and severity of abuse. Copyright © 2001 John Wiley & Sons, Ltd.