bluuebunny/crossref_metadata_2025_split huggingface dataset:
A preconditioning mass matrix to accelerate the convergence to the steady Euler solutions using explicit schemes
Authors: Storti M. A. , Baumann C. E. , Idelsohn S. R. 
Published: February 2006

AbstractWhen explicit time marching algorithms are used to reach the steady state of problems governed by the Euler equations, the rate of convergence is strongly impaired both in the zones with low Mach number and in the zones with transonic flow, e.g. Mach ⩽ α and | Mach − 1| ⩽ α, with α ⩽ 0·2. The rate of convergence becomes slower as α diminishes.We show in this paper, with analytical and numerical results, how the use of a preconditioning mass matrix accelerates the convergence in the aforementioned ranges of Mach numbers.The preconditioning mass matrix (PMM) we advocate in this paper can be applied to any FEM/FVM that uses an explicit time marching scheme to find the steady state. The method's rate of convergence to the steady state is studied, and results for the one‐ and two‐dimiensional cases are presented.In Sections 1‐3, using the one‐dimensional Euler equations, we first explain why there exists a slow rate of convergence when the plain lumping of mass is used. Then the convergence rate to steady solutions is analysed from its two constituents, that is, convergence by absorption at the boundaries and by damping in the domain. Next we give the natural solution to this problem, and with several examples we show the effectiveness of the proposed mass matrix when compared with the plain scheme.In Sections 4‐8 we give the multidimensional version of the preconditioning mass matrix. We make a stability analysis and compare the group velocities and damping with and without the new mass matrix. To finish, we show the velocity of convergence for a common test problem.
Boundary element method of multi‐lobe hydrodynamic lubrication bearing for numerical analysis in lubrication theory
Authors: Dequan Yang 
Published: February 2006

AbstractIn the present paper, the hydrodynamic lubrication problems of multi‐lobe bearings are treated by the Boundary Element Method in lubrication theory. For example, we have made numerical calculations for elliptical bearings and three‐lobe bearings. The stress and pressure distributions on the bearings and the velocity fields of the lubricant are given. We also studied conditions for the occurrence of vortexes in the flow region. The numerical investigations have shown that the method is very effective in handling hydrodynamic lubrication problems and it can be used to study the vortex in arbitrary shape bearings. Furthermore, the method has some advantages of computational convenience and superior accuracy. Especially, the ending point of the oil film pressure can be ascertained when non‐linear terms are considered, and that is undoubtedly extremely important in studying hydrodynamic lubrication problems.
Alveolar epithelialisation in ovine pneumonia
Authors: Alley M. R. , Manktelow B. W. 
Published: February 2006

AbstractPROLIFERATION of the alveolar epithelium, usually termed (epithelialisation) is a common feature of many mammalian pneumonias (Bell, 1943; Jarrett, 1954; Stamp and Nisbet, 1963). It occurs as a non‐specific reaction of the lung to injury by a wide variety of unrelated toxic and infective agents (Greever, Neubuerger and Davis, 1943; Omar, 1964).Although changes resembling alveolar epithelialisation have been recognized since before the turn of the century (Colberg, 1866, cited by Miller, 1947) the exact origin of the cells involved in this reaction has remained uncertain.
Experimental respiratory distress induced by paraquat
Authors: Robertson B. , Enhörning G. , Ivemark B. , Malmqvist Eva , Modée J. 
Published: February 2006

AbstractTHE weed‐killer Paraquat (1,1′‐dimethyl‐4,4′‐dipyridyliurn dichloride, Gramoxone, ICI) is toxic not only to plants but also to animals including man. The predominant lesions induced by paraquat are found in the lungs and consist of collapse, hyaline membranes, haemorrhage, interstitial inflammation and proliferation of bronchiolar epithelium (Bullivant, 1966; Clark, McElligott and Hurst, 1966; Almog and Tal, 1967; Manktelow, 1967; Campbell, 1968; Matthew et al., 1968; Oreopoulos et al., 1968; Conning, Fletcher and Swan, 1969). The pathogenesis of these changes, which persist several days after the excretion of injected paraquat (Daniel and Cage, 1966), is obscure. However, the similarity between the pulmonary lesions in paraquat poisoning and those of newborn infants dying from idiopathic respiratory distress suggests some common pathogenic mechanism, possibly a derangement of surfactant (Manktelow).The purpose of the present study is to analyse, by quantitative methods, the effect of paraquat on the surfactant system of the rat lung. In particular, we tried to find out whether experimental paraquat poisoning could be adopted as a model for the study of the idiopathic respiratory distress syndrome.
Alkaline phosphatase in craniopharyngiomas
Authors: Timperley W. R. , Turner P. , Davies S. 
Published: February 2006

AbstractTHE derivation of the epithelium from which craniopharyngiomas arise is in doubt. Willis (1953) and Russell and Rubinstein (1959) state that these tumours are not distinguishable from “epitheliomas” in which squamous and basal cells are both present. Timperley (1968a), in a histochemical investigation, showed that craniopharyngiomas differed from squamous epithelium and epidermal cyst epithelium in that they contained a high activity of alkaline phosphatase and in this respect they closely resembled the ameloblastoma of the jaw and the developing tooth bud. The present paper is a histochemical and chemical analysis comparing several more craniopharyngiomas with dental and dentigerous cysts.
Bending properties of compression molded three‐layer long fiber polypropylene composites
Authors: Hamada H. , Shonaike G. O. , Sato T. , Yamaguchi S. , Maekawa Z. , Koshimoto M. 
Published: February 2006

AbstractThe results of studies on bending properties of three‐layer long fiber polypropylene composites are presented. Thirteen samples with glass fibers of various lengths (i.e., 13, 25, 50 mm and continuous fiber length) in the laminates were prepared by stamping. Bending properties of shorter lengths exhibited a large scatter. On substitution of the middle layer with a continuous glass fiber the scatter was reduced. These results have been explained on the basis of flow models and X‐ray shadowgraphs, which showed that both slippage flow and orientation of the glass fiber during stamping are the major phenomena responsible for the scatter.
Grafting of commercially available amines bearing aromatic rings onto poly(vinylidene‐co‐hexafluoropropene) copolymers
Authors: Taguet A. , Ameduri B. , Boutevin B. 
Published: February 2006

AbstractThe grafting of poly(VDF‐co‐HFP) copolymers with different amines containing aromatic rings, such as aniline, benzylamine, and phenylpropylamine, is presented. 19F NMR characterization enabled us to show that the sites of grafting of aromatic‐containing amines were first difluoromethylene of vinylidene fluoride (VDF) in the hexafluoropropene (HFP)/VDF/HFP triad and then that of VDF adjacent to HFP. The kinetics of grafting of benzylamine, monitored by 1H NMR spectroscopy, confirmed those sites of grafting and showed that all VDF units located between two HFPs were grafted in the first 150 min, whereas those adjacent to one HFP unit were grafted in the remaining 3000 min. Parameters such as the temperature or the molar percentage of HFP in the copolymer had an influence on the maximum rate of grafted benzylamine. The higher the temperature, the higher the molar percentage of grafted benzylamine. Furthermore, the higher the molar percentage of HFP in the copolymer, the higher the molar percentage of VDF in the HFP/VDF/HFP triad, and the higher the molar percentage of grafted benzylamine. The spacer length between the aromatic ring and the amino group had an influence on the kinetics of grafting: aniline (pKa = 4.5) could not add onto the polymeric backbone, whereas phenylpropylamine was grafted in the first 150 min, and benzylamine required 3000 min to reach the maximum amount of grafting. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1855–1868, 2006
Structural changes in poly(ethylene terephthalate) induced by cryomilling and ambimilling
Authors: Zhu Yan‐guo , Li Zhi‐Qiang , Zhang Di , Tanimoto Toshio 
Published: February 2006

AbstractPoly(ethylene terephthalate) (PET) has been subjected to high energy ball milling at two different temperatures (cryogenic temperature and ambient temperature). The morphological and crystal structural evolutions of milled powders are characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X‐ray diffraction measurement. The particle size and distribution of milled powders are measured by laser diffraction particle size analyzer (LDPSA). The results indicate that the mechanisms of refining and amorphization are remarkably different between cryomilling (mechanical milling under cryogenic temperature) and ambimilling (mechanical milling under ambient temperature). The cryomilled particles are agglomerated morphology, while the ambimilled particles are cold‐welded morphology. Cryomilling induced crystalline PET translates to general amorphous, however, ambimilling induced crystalline PET transforms to oriented amorphous. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 986–993, 2006
Functional evolution within a protein superfamily
Authors: Yi Zhengping , Vitek Olga , Qasim M.A. , Lu Stephen M. , Lu Wuyuan , Ranjbar Michael , Li Jiangtian , Laskowski Michael C. , Bailey‐Kellogg Chris , Laskowski Michael 
Published: February 2006

AbstractThe ability to predict and characterize distributions of reactivities over families and even superfamilies of proteins opens the door to an array of analyses regarding functional evolution. In this article, insights into functional evolution in the Kazal inhibitor superfamily are gained by analyzing and comparing predicted association free energy distributions against six serine proteinases, over a number of groups of inhibitors: all possible Kazal inhibitors, natural avian ovomucoid first and third domains, and sets of Kazal inhibitors with statistically weighted combinations of residues. The results indicate that, despite the great hypervariability of residues in the 10 proteinase‐binding positions, avian ovomucoid third domains evolved to inhibit enzymes similar to the six enzymes selected, whereas the orthologous first domains are not inhibitors of these enzymes on purpose. Hypervariability arises because of similarity in energetic contribution from multiple residue types; conservation is in terms of functionality, with “good” residues, which make positive or less deleterious contributions to the binding, selected more frequently, and yielding overall the same distributional characteristics. Further analysis of the distributions indicates that while nature did optimize inhibitor strength, the objective may not have been the strongest possible inhibitor against one enzyme but rather an inhibitor that is relatively strong against a number of enzymes. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Metabolism of aflatoxin B1, benzo[a]pyrene, and 1,2‐dimethylhydrazine by cultured rat and human colon
Authors: Autrup Herman , Schwartz Rochelle D. , Essigmann John M. , Smith Lee , Harris Curtis C. , Trump Benjamin F. 
Published: February 2006

AbstractA model system for comparing carcinogen metabolism between human and rat colon has been developed. Tissue explants maintained under chemically defined conditions were treated with radioactively labeled carcinogens. After incubation for 24 hours, the binding of radioactive carcinogen to DNA was quantitated. Further, the carcinogen‐DNA adducts and carcinogen metabolites released into the culture media were identified. Both human and rat colon activate benzo[a]pyrene (BP), aflatoxin B1 (AFB), and 1,2‐dimethylhydrazine (DMH) into chemical species that reacted with cellular macromolecules. When human and rat colons were compared, the metabolism of AFB and DMH was qualitatively similar – the same major carcinogen‐DNA adducts and metabolic profile. However, the mean binding levels of DMH and AFB to colonic DNA were higher in rats than in humans. BP‐guanine adducts were the major adducts formed by both rat and human colonic DNA. However, BP‐adenine adducts were observed in rat colonic DNA but not in human colonic DNA. A positive correlation for the binding of BP and DMH to human DNA of different individuals was observed, but no correlation was found between BP and AFB. The data suggest that similar enzyme systems may be involved in the metabolism of BP and DMH, whereas different enzymes might be involved in the metabolic activation of AFB.
Cortisone‐induced cleft palate in the brachymorphic mouse
Authors: Pratt R. M. , Salomon D. S. , Diewert V. M. , Erickson R. P. , Burns R. , Brown K. S. 
Published: February 2006

AbstractPrevious studies have shown that the autosomal recessive gene brachymorphic (bm/bm), which is maintained on a C57BL/6J (C57) background, reduces limb growth and sulfation of cartilage proteoglycans. Hydrocortisone administered on gestational days 11–14 resulted in 20% CP in the C57 mouse, but 95% CP in the bm/bm mouse. The bm/bm mouse had a median effective dose for CP of 45 mg/kg, compared to 325 mg/kg for C57 and 40 mg/kg for A/J. Morphometric analysis indicated that the time of palatal elevation was delayed in the bm/bm relative to the C57 mouse both with and without hydrocortisone treatment. The amount of cytoplasmic glucocorticoid receptor protein present in the bm/bm palate on day 14 was the same as the amount found in the C57 palate, and was not elevated as it is in the A/J palate. The levels of cyclic AMP in the bm/bm palate on day 14 were 30–70% higher than that found in the C57 palate with or without hydrocortisone. These results suggest that both bm/bm and A/J exhibit a delay in palatal shelf rotation and elevated levels of cyclic AMP, which appear to be predisposing factors for cortisone‐induced cleft palate. These strains differ in that elevated levels of steroid receptors are present in A/J palate, whereas lower levels are found in the C57 and bm/bm mice.
Comitogenic activity of n‐alkane and related tumor promoters in murine lymphocytes
Authors: Baxter C. Stuart , Fish Larry A. , Bash Jerry A. 
Published: February 2006

AbstractLinear alkanes of specific chain length were found to enhance differentially the mitogenic response of murine spleen lymphocytes to the lectin phytohemagglutinin. Within the homologous series of compounds having between six and eighteen carbon atoms, a biphasic structure–function relationship was found, with maximum comitogenic activity occurring for tetradecane, and none or little for octane and octadecane. No alkane was mitogenic per se, and no alkane displaced the optimum mitogenic concentration of the lectin. The concentration of tetradecane having equivalent comitogenic activity was similar to that of methyl myristate, a simple alkyl ester of equal alkyl chain length, but approximately four orders of magnitude less that of the potent promoter 12‐0‐tetradecanoylphorbol‐13‐acetate (TPA). A similar ratio of potencies of TPA and the alkane dodecane, also a lymphocyte comitogen, has previously been found for promotion of mouse epidermal tumorigenesis. Maximum comitogenic activity was found when alkane and lectin were added to cultures simultaneously, the effect decreasing sharply when alkane addition was delayed relative to lectin. These findings suggest the existence of a cellular receptor with specificity for hydrophobic functions with chain lengths lying within a restricted range. Binding to this receptor also appears to be a common early event in tumor promotion, comitogenicity, and comutagenicity by agents of several chemical types.
Parametric statistical methods and sample size considerations for dominant lethal experiments: The use of clustering to achieve approximate normality
Authors: Whorton Elbert B. 
Published: February 2006

AbstractWhile the dominant lethal (DL) assay is often used to assess the mutagenic potential of suspect agents, questions remain concerning its sensitivity, the appropriate way to analyze resultant data, and the necessary study size. Many questions surrounding the statistical analysis methods relate to a specification of the basic independent unit of experimentation and analysis, the particular type of study design used, and the distributional properties of the study variables. These statistical analysis issues must be resolved before adequate attention can be given to the related questions of experimental sensitivity and sample size. This report deals with the development of a statistical analysis methodology which incorporates a particular type of data clustering scheme to achieve desirable distributional properties of the measured variables so that analysis of variance (AOV) and related parametric testing procedures can be used. Further, the differences between dose groups which can be detected using 20, 10, and 5 cluster units of 6 males and 18 females each are estimated for each variable according to the size of selected Type I and II errors. While these procedures were developed in part using data from two replicate studies on the DL effects of differing doses of n‐butyl glycidyl ether in mice, the clustering scheme suggested can be used with other AOV and regression procedures corresponding to the specific study design employed.
Influence of microinjected alkylating agents on the development of amphibian eggs
Authors: Ellinger Mark S. , Garone Louise M. 
Published: February 2006

AbstractA direct‐acting alkylating agent, beta‐propiolactone (BPL), was microinjected into eggs of the frog, Bombina orientalis (Anura: Discoglossidae). Response to injected BPL was dose‐dependent. Seventeen or more nmoles of BPL disrupted cortical pigment in the animal hemisphere and completely inhibited cleavage. Ten nmoles of BPL allowed normal cleavage but caused a variety of teratogenic patterns and decreased survivorship at every developmental stage. Small neoplasms were found in several prehatching tadpoles derived from BPL‐microinjected eggs. Responses of diploid and laser‐irradiation‐induced haploid eggs to BPL and ethyl‐methanesulfonate (EMS) were then compared to determine whether or not the induced anomalies could be attributed to genetic (mutational) events; development of the haploid and diploid embryos did not differ. Egg microinjection is not suitable as a mutagenesis assay. However, the technique has potential to reveal insights into nucleocytoplasmic interactions in development, and further analysis of the mode of action of injected alkylating agents, for example, by nuclear transplantation, may provide insights into mechanisms of teratogenesis and neoplasia.
Sister chromatid exchanges and chromosome aberrations in rubber workers
Authors: Mäki‐Paakkanen Jorma , Sorsa Marja , Vainio Harri 
Published: February 2006

AbstractSister chromatid exchanges and chromosomal aberrations were studied in peripheral blood lymphocytes of 55 rubber workers (from two different plants) and 35 controls mainly employed in office jobs. In both plants an increased frequency of SCEs (P < 0.05 for plant A and P < 0.01 for plant B) was detected in nonsmoking rubber workers as compared with nonsmoking referents.When the SCEs of worker groups belonging to the different job categories were compared with referents, the only groups showing statistically significant increases in SCEs were the smoking workers from the weighing and mixing departments of factory A and the nonsmoking weighers of factory B. A slight increase in the SCE frequencies was seen especially among smoking workers employed in the chemical mixing departments.The frequency of structural chromosome aberrations was not significantly increased in the occupational groups studied, the only exception being the small group of nonsmoking weighers in plant B.Among both the exposed workers and the controls, smokers had a higher mean SCE frequency than nonsmoking referents. This difference was significant between the exposed smokers and nonsmokers of plant A (P < 0.01) and between smoking and nonsmoking controls for plant B (P < 0.001). In addition, the chromosome aberration frequency of smoking controls of plant A was significantly higher (P < 0.01 when gaps excluded and P < 0.05 when gaps included) than that of nonsmoking referents. Also, smokers among controls for plant B had an increased frequency of aberrations in their cultured blood lymphocytes when compared with nonsmokers. This difference was significant (P < 0.05) when gaps were excluded.
Comparative genetic activity of cis‐ and trans‐1,2‐dichloroethylene in yeast
Authors: Bronzetti Giorgio , Bauer Carlo , Corsi Claudio , Del Carratore Renata , Galli Alvaro , Nieri Riccardo , Paolini Moreno , Cundari Enrico , Forti Giorgio Cantelli , Crenshaw John 
Published: February 2006

AbstractThe cis and trans isomers of 1,2‐dichloroethylene were tested for mutagenic effects in a diploid strain (D7) of the yeast Saccharomyces cerevisiae in suspension tests with and without a mammalian microsomal activation system, an S9 mouse liver fraction, and by an in vivo intrasanguineous host mediated assay. The effects of the same agents on aminopyrine N‐demethylase activity and cytochrome P‐450 level in liver were studied in nonpretreated and in phenobarbital + β‐naphtoflavone‐pretreated mice. In the suspension test, both isomers exhibited dose dependent toxicity, and survival was lower with metabolic activation than without. In this test also, both isomers exhibited genetic activity as measured by increases in recombinants at the ade 2 locus in experiments with metabolic activation. In the host‐mediated assay, only the cis isomer showed evidence of mutagenic activity with significant increases in convertants at the trp locus and revertants at the ilv locus. Such mutagenic activity was found both after acute and chronic doses and in liver, kidney, and lung tissue. The two isomers exhibited different effects with respect to aminopyrine N‐demethylase activity and cytochrome P‐450 level. In general, the trans isomer appeared to emphasize induction of enzyme activity or level while the cis isomer more frequently tended to inhibit activity or destroy the enzyme.
Glucuronide conjugation reduces the cytotoxicity but not the mutagenicity of benzo(a)pyrene in the CHO/HGPRT assay
Authors: Recio Leslie , Hsie Abraham W. 
Published: February 2006

AbstractBenzo(a)pyrene (B[a]P) is biotransformed by the mixed‐function oxidase (MFO) system to numerous metabolites some of which are cytotoxic and/or mutagenic to mammalian cells. However, conjugation of B(a)P metabolites with glucuronic acid in vivo is a major pathway of detoxication and elimination. The effects of glucuronide conjugation on B(a)P‐induced cytotoxicity and mutagenicity were studied using the CHO/HGPRT assay with a rat liver homogenate preparation containing MFO system cofactors (S9 mix) and uridine diphosphate α‐D‐glucuronic acid (UDPGA). B(a)P metabolites proximate to the biologically active B(a)P quinones (B[a]P 6‐OH) and to the B(a)P 7,8‐diol‐9,10 epoxide isomers (B[a]P 7,8‐diol), were also assayed with S9 mix in the absence and presence of UDPGA. The addition of UDPGA to S9 mix reduced B(a)P‐induced cytotoxicity but did not affect mutagenicity. B(a)P 6‐OH‐mediated cytotoxicity was also reduced in the presence of UDPGA. UDPGA had no effect on B(a)P 7,8‐diol‐induced cytotoxicity or mutagenicity. B(a)P phenols have been shown to be the preferred B(a)P‐ metabolite substrates for UDP‐glucuronyltransferase enzymes. Thus, the reduction of B(a)P and B(a)P 6‐OH‐induced cytotoxicity by glucuronide conjugation is likely due to the elimination of cytotoxic phenols and quinones. Since B(a)P 7,8‐ diol is a poor substrate for UDP‐glucuronyltransferase enzymes, no effects on B(a)P‐induced mutagenicity or B(a)P 7,8‐diol‐induced cytotoxicity and mutagenicity were observed.