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FHA Rodrigues EF Santos JPA Feitosa NMPS Ricardo F Heatley 《Polymer International》2004,53(6):733-739
Unstretched films of natural rubber (NR) from Hevea brasiliensis were exposed to ozone flow of 15 ml min?1 from 4 to 300 min. The efficiency of reaction was determined by ozone consumption of NR films. Plots of reacted ozone mass versus film thickness show that the ozone penetration and the ozone reaction progressed into deeper layers (170 µm) than described in the literature (~0.5 µm). The previous proposed model based on viscometry measurements was corroborated by ozone consumption results. The effect of thickness on the O3/NR stoichiometric ratio indicated that the diffusion process that controls the ozonation in unstretched film does not consist of the boundary progression behind which all reactive sites have been saturated. Ozonation in unstretched rubber film, while being less efficient than ozonolysis in solution, does have a reaction efficiency of the same order of magnitude. NMR spectroscopy was used to characterise the products formed by ozonation. Copyright © 2004 Society of Chemical Industry 相似文献
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From January 1981 through October 1995, a total of 28 patients underwent surgery for metastatic lung tumors in our institute. A retrospective review and survival analysis of these patients are reported. There were 12 males and 16 females, with the mean age of 57 years. Of them, 20 patients had solitary lesions. Pulmonary metastasis was from the colon in 8 patients, from the breast in 5, from the stomach and the uterus in each 3, from the bladder, the rectum and the soft tissue in each 2, and from the kidney, the ovarium and the thyroid in each 1. A lobectomy was performed in 22 patients, 17 of whom were accompanied with mediastinal lymph node dissection (R2a). Partial resection without lymph node dissection was performed in 6 patients (R0). Overall 5-year survival was 24.7%. Four-year or over survivor were 4 patients who underwent a lobectomy with R2a. The patients undergoing lobectomy had a significantly better prognosis compared with patients with partial resection (p<0. 05). The patients with R2a had significantly less local recurrence than patients with R1 or R0 (p<0.05). We conclude that lobectomy with R2a is suitable treatment for metastatic lung cancer. 相似文献
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C Schleper EF DeLong CM Preston RA Feldman KY Wu RV Swanson 《Canadian Metallurgical Quarterly》1998,180(19):5003-5009
Molecular phylogenetic surveys have recently revealed an ecologically widespread crenarchaeal group that inhabits cold and temperate terrestrial and marine environments. To date these organisms have resisted isolation in pure culture, and so their phenotypic and genotypic characteristics remain largely unknown. To characterize these archaea, and to extend methodological approaches for characterizing uncultivated microorganisms, we initiated genomic analyses of the nonthermophilic crenarchaeote Cenarchaeum symbiosum found living in association with a marine sponge, Axinella mexicana. Complex DNA libraries derived from the host-symbiont population yielded several large clones containing the ribosomal operon from C. symbiosum. Unexpectedly, cloning and sequence analysis revealed the presence of two closely related variants that were consistently found in the majority of host individuals analyzed. Homologous regions from the two variants were sequenced and compared in detail. The variants exhibit >99.2% sequence identity in both small- and large-subunit rRNA genes and they contain homologous protein-encoding genes in identical order and orientation over a 28-kbp overlapping region. Our study not only indicates the potential for characterizing uncultivated prokaryotes by genome sequencing but also identifies the primary complication inherent in the approach: the widespread genomic microheterogeneity in naturally occurring prokaryotic populations. 相似文献
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Measurements of the width and depth of the palate were used to predict the race (American black or white) or sex or both of an individual. The sample consisted of 332 living subjects with permanent dentitions, and measurements were made between cusp tips, so palate size includes bony and dental components. Blacks, with a more square palate, were distinguished from whites primarily by greater interpremolar widths and P1-to-M2 depths. Simultaneous prediction of race and sex had a correct classification of 48%, which is about twice that expected from chance. Pooling the two sex increases correct classification of race to 83%. Formulas also are provided for each variable separately to accommodate fragmentary remains. Resilience of palatal structures to traumatic and natural forces makes this method practical in several forensic situations. 相似文献
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