bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling hydrogen spillover in dual‐bed catalytic reactors
Authors: Weigle John C. , Phillips Jonathan 
Published: April 2004

AbstractA semiquantitative model was developed to describe hydrogen spillover in dual‐bed catalytic reactors. In previous studies it has been conclusively demonstrated that hydrogen can diffuse macroscopic distances and activate catalytic sites. The test reaction in those studies was the isomerization of 1‐butene to 2‐butene. The model is derived based on the fundamental principles of transport phenomena and reaction kinetics. Because many of the required values in the model are unknown, it cannot be solved quantitatively. Thus, a parametric analysis was conducted. The model successfully predicts trends observed experimentally. Specifically, the activity increases nonlinearly as the bed composition changes, the selectivity was low for all dual‐bed reactors, and the selectivity was high for well‐mixed catalyst beds. © 2004 American Institute of Chemical Engineers AIChE J, 50: 821–828, 2004
Occupation and risk of meningioma and acoustic neuroma in the United States
Authors: Rajaraman Preetha , Roos Anneclaire J. De , Stewart Patricia A. , Linet Martha S. , Fine Howard A. , Shapiro William R. , Selker Robert G. , Black Peter M. , Inskip Peter D. 
Published: April 2004

AbstractBackgroundWorkplace exposures may be related to the development of brain tumors. In this case‐control study, we examine occupation as a risk factor for meningioma and acoustic neuroma.MethodsA lifetime work history was obtained for 197 incident cases of meningioma, 96 cases of acoustic neuroma and 799 controls with non‐malignant diseases enrolled from three hospitals in the United States between 1994 and 1998. Jobs considered to have similar tasks and chemical exposures were assigned to an occupational group. Logistic regression was used to estimate odds ratios (OR) adjusted for study matching factors (hospital, age, sex, race/ethnicity, and proximity of residence to the hospital) and education.ResultsElevated risk of meningioma was observed for individuals who had ever worked in the following occupational groups: auto body painters, designers and decorators, military occupations, industrial production supervisors, teachers, and managers. For acoustic neuroma, increased risk was noted for having worked as an athlete, gas station attendant, purchasing agent, sales representative, or teacher.ConclusionsAlthough limited by multiple comparisons and the relatively small number of cases and controls in many occupational groups, these results nevertheless provide clues that deserve additional study in future epidemiologic studies. Am. J. Ind. Med. 45:395–407, 2004. Published 2004 Wiley‐Liss, Inc.
Mutagenic testing of workers exposed to toluene‐diisocyanates during plastics production process
Authors: Bilban Marjan 
Published: April 2004

AbstractBackgroundToluene diisocyanates (TDIs) are important industrial intermediates used in conjunction with polyester polyols as coreactants in the manufacture of polyurethane foam blocks, paints, etc. It is listed as a potential carcinogen by the National Toxicology Program (NTP) and International Agency for Research on Cancer (IARC) and is known to induce chromosomal aberrations.MethodsThe study involved 26 people, exposed to TDI during the production of plastics. The corresponding control group was comprised of 21 people coming from the same geographic area, who were never exposed to isocyanates.ResultsThe concentration of TDI ranged between 0.007 mg/m3 and 0.016 mg/m3, which amounts to 0.10–0.23 MDK (extreme value of a single substance) 0.007 mg/m3. Structural chromosome aberrations (SCA) were evaluated in 200 lymphocytes of peripheral blood. The average value was 2.6. Sister chromatid exchange (SCE) was established in 50 cells, the average being 8.127. Micronucleus (MN) was established in 500 CB, with an average of 12.07. The averages of the control group were 1.89 (SCA), 5.52 (SCE), and 4.38 (MN). The difference between the groups is of statistical significance.ConclusionsThe ascertained results accentuate mutagenic activity of isocyanates or their metabolic products. Am. J. Ind. Med. 45:468–474, 2004. © 2004 Wiley‐Liss, Inc.
The psychosocial work environment and musculoskeletal disorders: Design of a comprehensive interviewer‐administered questionnaire
Authors: Rugulies Reiner , Braff Jeffrey , Frank John W. , Aust Birgit , Gillen Marion , Yen Irene H. , Bhatia Rajiv , Ames Genevieve , Gordon Deborah R. , Janowitz Ira , Oman Doug , Jacobs Bradly P. , Blanc Paul 
Published: April 2004

AbstractBackgroundPsychosocial working conditions are likely to contribute to work‐related musculoskeletal disorders (WRMSDs), but a lack of standardized measurement tools reflects both the theoretical and methodological limitations of current research.MethodsAn interdisciplinary team including biomedical, behavioral, and social science researchers used an iterative process to adapt existing instruments for an interviewer‐administered questionnaire assessing psychosocial workplace exposure related to musculoskeletal disorders.ResultsThe resulting questionnaire included measures of psychosocial workplace factors based on two theoretical models (the demand‐control‐support and the effort‐reward imbalance models), supplemented by the additional constructs of “emotional demands,” and “experiences of discrimination.” Other psychosocial and physical measures selected for questionnaire inclusion address physical workload, sociodemographic and anthropometric characteristics, social relations and life events, health behaviors, and physical and psychological health.ConclusionUsing an interdisciplinary approach facilitated the development of a comprehensive questionnaire inclusive of key measures of psychosocial factors that may play a role in the complex mechanisms leading to WRMSDs. Am. J. Ind. Med. 45:428–439, 2004. © 2004 Wiley‐Liss, Inc.
Unilateral nerve injury produces bilateral loss of distal innervation
Authors: Oaklander Anne Louise , Brown Jennifer M. 
Published: April 2004

AbstractThere are no known anatomical connections between neurons that innervate homologous right and left body parts. Nevertheless, some patients develop bilateral abnormalities after unilateral injury, a phenomenon often unrecognized and not yet characterized. Therefore, we examined in rats the effects of ligating and cutting one tibial nerve on sensory function and on density of innervation in hind paws contralaterally as well as ipsilaterally to the injury, at times between 1 day and 5 months after surgery. Punches removed from tibial‐ or sural‐innervated planter paw skin were immunolabeled to quantitate epidermal nerve endings. Naive and sham‐operated rats provided controls. Axotomized rats had near‐total loss of PGP9.5+ innervation within ipsilateral tibial‐innervated skin at all time‐points. Adjacent ipsilateral sural‐innervated skin had persistent hyperalgesia without denervation, and robust axonal sprouting at 5 months after surgery. Contralesional hind paws lost 54% of innervation in tibial‐innervated epidermis starting 1 week after surgery and persisting throughout. Contralesional sural‐innervated skin had neither neurite loss nor sprouting. These results imply that unilateral nerve injury can cause profound, long lasting, nerve–branch–specific loss of distal innervation contralaterally as well as ipsilaterally. They discredit the practice of using tissues contralateral to an injury to provide normative controls and suggest the possibility of rapid, transmedian postinjury signals between homologous mirror‐image neurons.
Use of cationic starch derivatives for the removal of anionic dyes from textile effluents
Authors: Khalil Mohamed I. , Aly Amal A. 
Published: April 2004

AbstractSix types of cationic starch derivatives were prepared. These types were (1) cationic starch derivatives containing primary, secondary, and tertiary amino groups and quaternary ammonium salt and (2) etherified and grafted cationic starch derivatives. These cationic starch derivatives were treated with three types of dyes, an acid dye, a hydrolyzed reactive dye, and a direct dye. Different factors affecting the dye sorption value (mmol/100 g of sample) were been studied. These factors were the pH of the medium, treatment time, amine type, amine content, dye type and molecular size, and the distance between the amine groups. The dye sorption value and the sorption efficiency percentage were determined. The dye sorption value increased with increasing amine content to a maximum value and then decreased. This phenomenon occurred with all of the amine types. The maximum dye sorption values on with the acid dye depended on the amine type. These values were 73.8 (at an amine content of 155), 90 (at an amine content of 150), 84.9 (at an amine content of 133), and 72.5 (at an amine content of 75) for primary, secondary, and tertiary amines and the quaternary ammonium salt, respectively. The sorption efficiency percentage at these maximum values were 47.6, 60, 63.8, and 96.3%, respectively. The maximum sorption values were acid dye > hydrolyzed reactive dye > direct dye. The dye sorption value and the sorption efficiency percentage of the etherified cationic starch derivatives had higher values than that of the grafted cationic starch derivatives. The prepared cationic starch derivatives that had amine contents of 155, 150, 133, and 75 m atom/100 g of sample for primary, secondary, and tertiary amines and the quaternary ammonium salt, respectively, had the best ability to adsorb anionic dyes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 227–234, 2004
Polyimides. IV. Synthesis and characterization of fluorinated copolyimides
Authors: Madhra Mukesh Kumar , Sharma Mamta , Banerjee Susanta 
Published: April 2004

AbstractA series of new copolyimides were synthesized by the reaction of pyrometallic dianhydride, benzophenone tetracarboxylic acid dianhydride, and 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane (6FDA) with two diamines, 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl and 4,4′‐diaminodiphenyl ether, at a 50:50 ratio by a thermal imidization route. The complete spectral assignment of the copolymer derived from 6FDA was done with the help of distortionless enhancement of polarization transfer 90° and two‐dimensional heteronuclear (C, H) shift correlation spectroscopy. The various types of couplings in the copolymers were assigned with the help of two‐dimensional correlated spectroscopy (COSY) homonuclear correlation spectroscopy. A long‐range connectivity was also observed by a heteronuclear correlation spectroscopy via long‐range coupling experiment. The copolyimides derived from 6FDA were soluble in common organic solvents such as N,N‐dimethyl formamide, N,N‐dimethyl acetamide, dimethyl sulfoxide, N‐methyl pyrrolidone, and chloroform. Water absorption values, after the samples were boiled in water for 72 h, were in the range 0.3–0.7%. These polyimides had low dielectric constants of 2.79–3.01 at 1 MHz, low refractive indices of 1.655–1.705 at 589.3 nm, and high optical transparencies (>90%). The onset temperature for 5% weight loss for these polyimides, as assessed by thermogravimetric analysis, was up to 551°C in air, indicating a very high thermal stability, and the polyimides showed glass‐transition temperatures as high as 316°C. Transparent thin films of these polyimides exhibited tensile strengths up to 93 MPa, moduli of elasticity up to 3.1 GPa, and elongations at break up to 24% depending on the exact repeat unit structure. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 235–246, 2004
Modeling of the copolymerization, with depropagation, of α‐methyl styrene and methyl methacrylate at an elevated temperature
Authors: Cheong Seong Ill , Penlidis A. 
Published: April 2004

AbstractWe propose a dynamic model for the copolymerization of α‐methyl styrene (α‐MS) and methyl methacrylate (MMA) in a batch reactor. The parameters are based on data from the literature and our own laboratories over the full conversion range. A two‐parameter model with constant reactivity ratios shows the most reasonable results. The dynamic model depicts the reaction kinetics and reactor behavior more clearly. Termination occurs mainly by the cross reaction of unlike radicals, and its rate increases with the molar ratio of α‐MS to MMA. The model enables us to predict the instantaneous and cumulative properties of the copolymer and also provides us with a basic tool for the optimization and control of industrial reactors. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 261–270, 2004
Adhesion between dissimilar polymers. II. Effects of bonding temperature and crosslinking agent
Authors: Tse M. F. , Hu W. , Yeganeh M. S. , Zhang D. 
Published: April 2004

AbstractWe study the effects of bonding temperature and crosslinking agent on the adhesion of a crosslinkable BIMS polymer (terpolymer of isobutylene, p‐bromomethylstyrene, and p‐methylstyrene) to a crosslinkable diene polymer, such as polyisoprene rubber (IR) or polybutadiene rubber (BR). The strength of adhesion between these two dissimilar polymers, represented by the work of detachment, Ga, is measured by using the T‐peel geometry at various test temperatures and separation speeds. Surface‐sensitive infrared‐visible sum frequency generation (SFG) spectroscopy is used to characterize the surface of BIMS and ensure the existence of crosslinkable species, the p‐bromomethylstyrene functional group, on this polymer. Time‐of‐flight secondary ion mass spectroscopy (ToF‐SIMS) is utilized to determine the loci of failure of the debonded surfaces and the influence of curative migration, if any, on adhesion. Although a zinc di‐2‐ethylhexanoate crosslinkable BIMS polymer shows interfacial crosslinking or cocure when bonded to a sulfur crosslinkable diene polymer at 140°C, interfacial cocure does not occur when the bonding temperature is raised to 180°C. On the other hand, if the sulfur crosslinking agent in the diene polymer is replaced by another crosslinking agent, a brominated phenolic resin, interfacial cocure occurs between BIMS and the diene polymer when the bonding temperature is 140, 160, or 180°C. Also, this brominated resin cocures the BIMS and diene polymer phases when these immiscible polymers are blended together in the presence of a metal compound (salt) of carboxylic acid, such as zinc di‐2‐ethylhexanoate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 323–335, 2004
Crystallization behavior of poly(N‐methyldodecano‐12‐lactam). III. Kinetics of isothermal crystallization
Authors: Kratochvíl J. , Sikora A. 
Published: April 2004

AbstractDifferential scanning calorimetry, combined with Avrami theory, was used to investigate the kinetics of three steps of the complex crystallization process of poly(N‐methyldodecano‐12‐lactam) (MPA): (1) primary melt crystallization at respective crystallization temperature (Tc), (2) additional crystallization at 30°C, and (3) recrystallization at 54°C. Kinetics of the three steps was discussed with respect to Tc. The Avrami exponent n of primary melt crystallization decreased between 2.5 and 1.9 in the range of Tc values of −10 to 20°C, which suggests heterogeneous nucleation, followed by two‐dimensional growth, with a larger involvement of homogeneous thermal nucleation at greater supercoolings. The crystallization rate constant k decreased with increasing Tc. The value of n = 1.5 for additional crystallization implies a two‐dimensional diffusion‐controlled crystal growth with a suppressed nucleation phase. For Tc values ranging from −10 to 0°C and 0 to 20°C, k showed weak and quite strong decreasing dependencies on Tc, respectively. The recrystallization mechanism involved partial melting of primary crystallites and two‐dimensional rearrangement of chains into a more perfect structure. The rate of this process was almost independent of Tc. The values of activation energies were derived for the three steps of MPA crystallization using the Arrhenius equation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 279–293, 2004
Structural changes of injection molded starch during heat treatment in water atmosphere: Simultaneous wide and small‐angle X‐ray scattering study
Authors: Cagiao M. E. , Rueda D. R. , Bayer R. K. , Baltá Calleja F. J. 
Published: April 2004

AbstractNative starches with wide varying amylose content were processed by injection molding. The injection‐molded materials were conditioned in water for 20 days and sealed in glass capillaries. Simultaneous wide‐ and small‐angle X‐ray scattering (WAXS and SAXS, respectively) were recorded during thermal heating using a synchrotron source. Crystallinity, SAXS invariant, Q, and long period, L, were measured as a function of heating temperature. The injection‐molding process provokes a destruction of the crystal forms A (cereal starch) and B (tubercle starch) but favors a development of the crystal form Vh. After wet conditioning, WAXS of the injection‐molded samples shows again the appearance of the crystal forms A or B, and crystallinity reaches values similar or larger than those of native starch. A constant heating rate (5°C/min) was particularly used for a comparison of potato and corn starch with a similar amylose content. While the crystallinity associated to forms A and B slowly decreases below 55°C and then rapidly decreases until its disappearance at 85–90°C, the invariant shows a maximum around 40°C and rapidly decreases thereafter. The total nanostructure disappearance occurs at temperatures about 10°C higher for the case of potato starch. In addition, a recovery of the WAXS and SAXS maxima during the subsequent cooling process before reaching room temperature was observed only for potato starch. Analysis of WAXS and SAXS for the rest of the starch materials reveals clear differences in the structural parameters of the samples that cannot be easily explained solely on the basis of the amylose content. Thus, for Cerestar and Roquette, it is noteworthy that there was a continuous decrease of L until its total disappearance as well as the persistence of crystallinity (form B), presumably stabilized by the presence of the Vh structure (12–15%). Real‐time crystallization experiments on two amorphous injection molded samples, waxy maize (free amylose starch) and potato starch, are also discussed. It is shown that the absence of amylose delays the recrystallization of amylopectine during the experiment. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 301–309, 2004
On rotation, torsion, lateralization, and handedness of the embryonic heart loop: New insights from a simulation model for the heart loop of chick embryos
Authors: Männer Jörg 
Published: April 2004

AbstractThe internal organs of vertebrates show specific anatomical left‐right asymmetries. The embryonic heart is the first organ to develop such asymmetries during a process called dextro‐looping. Thereby the initially straight heart tube curves toward its original ventral side and the resulting bend becomes displaced toward the right side of the embryo. Abnormal displacement of the heart loop toward the left is rare and is called levo‐looping. Descriptive studies have shown that the lateralization of the heart loop is driven by rotation around its dorsal mesocardium. However, nothing was known on the modes of this process. To gain insight into this subject, different modes of rotation were tested in a simulation model for the looping chick embryo heart. The morphological phenotypes obtained in this model were compared with normal and mirror‐imaged embryonic hearts. The following observations were made. One, rotation of the heart loop around its dorsal mesocardium has two consequences: first, lateral displacement of its bending portion either toward the right (D‐loop) or left (L‐loop) side of the embryo, and second, torsion of the cardiac bend into a helical structure that is wound either clockwise (right‐handed helix) or counterclockwise (left‐handed helix). The normal loop presents as a D‐loop with left‐handed helical winding and its mirror image presents as an L‐loop with right‐handed helical winding. This conflicts with the use to define D‐loops as right‐ and L‐loops as left‐handed structures. Two, dextro‐looping might be driven almost exclusively by rightward rotation of the arterial pole of the loop. It becomes complemented by leftward rotation of the venous pole during the subsequent phase of looping. An inverse mode of rotation might drive levo‐looping. Three, the two different helical configurations of heart loops both can occur as right‐sided, median, or left‐sided positional variants. When viewed from the front, all right‐sided variants appear as D‐loops and all left‐sided variants appear as L‐loops at the end of dextro‐ or levo‐looping. Their true asymmetric phenotypes become fully apparent only after simulation of the subsequent phase of looping. The terms D‐ and L‐loop obviously do not fully define the chirality of heart loops. The chirality of their helical configuration should be defined, too. The implications of these data with respect to molecular and experimental data are discussed. Anat Rec Part A 278A:481–492, 2004. © 2004 Wiley‐Liss, Inc.
Quantitative study on guinea pig spermatogenesis shows a relative high percentage of early meiotic prophase stages
Authors: Rodríguez Rosana E. , Wettstein Rodolfo M. 
Published: April 2004

AbstractMeiosis is the special double cellular division characterized by the reduction of chromosome number of the final products and recombination of genetic information present in maternal and paternal homologous chromosomes. Early stages of meiotic prophase, leptotene and zygotene (L/Z), are functionally important since homologous chromosomes recognize, align, and pair during them. They are poorly represented in the seminiferous tubules of mammalian species, and this fact turns studies focused on these stages difficult to perform. As a consequence, the molecular bases of these important events are so far poorly known and understood in higher eukaryotes. The purpose of this work was to provide an advantageous experimental mammalian model (with a reasonable number of cells) for biochemical and molecular analysis of early meiotic prophase stages. Here, we present the results of our quantitative study on testes material of both immature and adult guinea pig specimens (Cavia porcellus). We show that their seminiferous tubules contain a comparatively high percentage of L/Z spermatocytes, as well as a very conspicuous chromosome bouquet at the L/Z transition, which points out this species as a well‐suited one to address studies on such stages in mammals. Anat Rec Part A 278A:493–504, 2004. © 2004 Wiley‐Liss, Inc.
New Derivatives of Quinazoline and 1, 2‐Dihydroquinazoline N3‐Oxide with Expected Antitumor Activity
Authors: Mikiciuk‐Olasik Elżbieta , Baszczak‐Światkiewiz Katarzyna , Żurek Elżbieta , Krajewska Urszula , Różalski Marek , Kruszyński Rafał , Bartczak Tadeusz J. 
Published: April 2004

AbstractSome derivatives of quinazoline and 1, 2‐dihydroquinazoline N3‐oxide were synthesised and their cytotoxic activities against human leukaemia HL‐60 cells under hypoxic and aerobic conditions were tested and compared to tirapazamine as the reference compound. Compound 8 showed 5‐fold higher toxicity under hypoxic conditions than in normal oxygen atmosphere. The structure of quinazoline derivatives was established by X‐ray crystal structure analysis.