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102.
103.
Mohamed M Ghanem Lori A Battelli Brandon F Law Vincent Castranova Michael L Kashon Joginder Nath Ann F Hubbs 《Particle and fibre toxicology》2009,6(1):21-12
Background
Many polycyclic aromatic hydrocarbons (PAHs) can cause DNA adducts and initiate carcinogenesis. Mixed exposures to coal dust (CD) and PAHs are common in occupational settings. In the CD and PAH-exposed lung, CD increases apoptosis and causes alveolar type II (AT-II) cell hyperplasia but reduces CYP1A1 induction. Inflammation, but not apoptosis, appears etiologically associated with reduced CYP1A1 induction in this mixed exposure model. Many AT-II cells in the CD-exposed lungs have no detectable CYP1A1 induction after PAH exposure. Although AT-II cells are a small subfraction of lung cells, they are believed to be a potential progenitor cell for some lung cancers. Because CYP1A1 is induced via ligand-mediated nuclear translocation of the aryl hydrocarbon receptor (AhR), we investigated the effect of CD on PAH-induced nuclear translocation of AhR in AT-II cells isolated from in vivo-exposed rats. Rats received CD or vehicle (saline) by intratracheal (IT) instillation. Three days before sacrifice, half of the rats in each group started daily intraperitoneal injections of the PAH, β-naphthoflavone (BNF). 相似文献104.
The effects of precursor and calcination temperature on the nano morphology of ruthenium dioxide on titanium, prepared from thermal decomposition of aqueous salt solutions were investigated. Transmission electron microscopy, X-ray diffraction, gas porosimetry and cyclic voltammetry showed that lower calcination temperature yielded smaller crystallites. The crystallites were between 6 and 22 nm in diameter. When using ruthenium nitrosyl nitrate the firing temperature had a large impact on the grain size, but for chloride there was only a minor effect in the temperature range 350-550 °C. 相似文献
105.
Hui Jin Mary Ann LundteigenMarvin Rausand 《Reliability Engineering & System Safety》2011,96(3):365-373
Safety instrumented systems (SISs) are usually divided into two modes of operation, low-demand and high-demand. Unfortunately, this classification is not easy to justify and the available formulas that are used to quantify the reliability performance in these two modes of operation are unable to capture combined effects of functional testing, spurious activations, and successful responses to demands. This article discusses some important modeling issues for SIS reliability performance quantification, and demonstrates their implementation in a Markov model. The accuracy of the Markov model for a simple case study of a pressure transmitter is verified through comparison with a scenario-based formula, and it is shown that the Markov approach gives a sufficiently accurate result for all demand rates, covering both low- and high-demand modes of operation. 相似文献
106.
Ann Heylighen Monika Rychtáriková Gerrit Vermeir 《Universal Access in the Information Society》2010,9(3):283-292
Inclusive design aims at objects and environments that are accessible, usable and comfortable for all people throughout their
entire lifespan. In architecture, this aim is usually associated with physical accessibility. Yet acoustic qualities may considerably
impact usability and comfort as well, especially in spaces for listening. This case study explores the notion of acoustic
comfort for all in the context of university education. One auditorium, situated in a historic building and subject to renovation
in the near future, is studied in detail: acoustic obstacles are identified in collaboration with user/experts and are measured
in situ; specific interventions are proposed in consultation with building professionals, technicians and conservation specialists
and are tested using dedicated acoustic simulation software. The study draws attention to the importance of acoustic comfort
for all and offers a first view of which solutions are possible and desirable and how these can be obtained. 相似文献
107.
108.
Burkard Alan W.; Pruitt Nathan T.; Medler Barbara R.; Stark-Booth Ann M. 《Canadian Metallurgical Quarterly》2009,3(1):37
In this paper, the authors report on the development and initial psychometric evaluation of the Lesbian, Gay, and Bisexual Working Alliance Self-Efficacy Scales (LGB-WASES) with data collected from two studies and 534 counseling trainees. Exploratory factor analysis results yielded a 32-item scale with a three-factor model (a) Emotional Bond, (b) Establishing Tasks, and (c) Setting Goals. LGB-WASES scores were internally consistent and remained stable over a 3-week period. Construct validity evidence suggests the LGB-WASES scores were (a) positively related to general perceptions of counseling self-efficacy and multicultural counseling competency, (b) negatively related to attitudes toward lesbians and gay men, and (d) unrelated to social desirability. Recommendations for future research are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
Semi-interpenetrating networks (sIPNs) designed to mimic extracellular matrix via covalent crosslinking of poly(ethylene glycol)
diacrylate in the presence of gelatin have been shown to aid in wound healing, particularly when loaded with soluble factors.
Ideal systems for tissue repair permit an effective release of therapeutic agents and flow of nutrients to proliferating cells.
Appropriate network characterization can, consequently, be used to convey an understanding of the mass transfer kinetics necessary
for materials to aid in the wound healing process. Solute transport from and through sIPNs has not yet been thoroughly evaluated.
In the current study, the diffusivity of growth factors and nutrients through the polymeric system was determined. Transport
of keratinocyte growth factor was modeled by treating the sIPN as a plane sheet into which the protein was loaded. The diffusion
coefficient was determined to be 4.86 × 10−9 ± 1.86 × 10−12 cm2/s. Glucose transport was modeled as flow through a semi-permeable membrane. Using lag-time analysis, the diffusion coefficient
was calculated to be 2.25 × 10−6 ± 1.98 × 10−7 cm2/s. The results were evaluated in conjunction with previous studies on controlled drug release from sIPNs. As expected from
Einstein-Stokes equation, diffusivity decreased as molecular size increased. The results offer insight into the structure-function
design paradigm and show that release from the polymeric system is diffusion controlled, rather than dissolution controlled. 相似文献
110.
Ans De Roeck Thomas DuvetterIlse Fraeye Iesel Van der PlanckenDaniel Ndaka Sila Ann Van LoeyMarc Hendrickx 《Food chemistry》2009
Heat sterilization of plant derived food products entails considerable organoleptic and nutritional quality losses. For instance, texture loss of fruits and vegetables occurs, next to turgor pressure losses, mainly due to chemical changes in the cell-wall pectic polysaccharides. High-pressure sterilization, i.e. the combination of high temperature (?90 °C) with high pressure (?500 MPa), could present a positive alternative assuring safety while minimizing quality losses. In this study, the potential of high-pressure sterilization in preserving fruit and vegetable texture was evaluated by investigating the effect of combined high-pressure/high-temperature (HP/HT) treatments on two texture related chemical pectin conversions in model sytems. First, a protocol was developed to perform reproducible kinetic studies at HP/HT under constant processing conditions. Subsequently, apple pectin solutions at pH 6.5 were subjected to different HP/HT combinations (500, 600 and 700 MPa/90, 110 and 115 °C) and the extent of chemical demethoxylation and β-eliminative depolymerization was determined. At atmospheric pressure, both zero-order reaction rate constants increased with increasing temperature. At all temperatures, demethoxylation showed a higher rate constant than β-elimination. However, a temperature rise resulted in a stronger acceleration of β-elimination than of demethoxylation. When combining high temperature with high pressure, β-elimination was retarded or even stopped, whereas demethoxylation was stimulated. These results are very promising in the context of the texture preservation of high-pressure sterilized fruits and vegetables, as β-elimination is accepted to be one of the main causes of thermal softening and low methoxylated pectin can enhance tissue strength by forming cross-links with calcium ions present. 相似文献