Experimental investigation of dielectric barrier impact on breakdown voltage enhancement of copper wire-plane electrode systems

Non-pressurized air is extensively used as basic insulation media in medium / high voltage equipments. An inherent property of air-insulated designs is that the systems tend to become physically large. Application of Dielectric barrier can increase the breakdown voltage and therefore decrease the size of the equipments. In this paper, the impact of dielectric barrier on breakdown voltage enhancement of a copper wire-plane system is investigated. For this purpose, the copper wire is covered with different dielectric materials. Depending on the air gap and dielectric strength of the barrier the breakdown can be initiated in the solid or gas dielectric. Theoretically, free charges are affected by the electric field between the electrodes and accumulated at the dielectric surface, this leads to the reduction of electric field in air gap and enhancement of the ifield in the dielectric layer. Therefore, with appropriate selection of the barrier thickness and material, it is possible to increase the breakdown voltage of the insulation system. The influence of different parameters like inter-electrode spacing, and dielectric material on the break-down voltage is investigated for applied 50 Hz AC and DC voltages. The results indicate that up to 240% increase of the breakdown voltage can be achieved

PRL-3 promotes the motility, invasion, and metastasis of LoVo colon cancer cells through PRL-3-integrin β1-ERK1/2 and-MMP2 signaling

<p>Abstract</p> <p>Background</p> <p>Phosphatase of regenerating liver-3 (PRL-3) plays a causative role in tumor metastasis, but the underlying mechanisms are not well understood. In our previous study, we observed that PRL-3 could decrease tyrosine phosphorylation of integrin β1 and enhance activation of ERK1/2 in HEK293 cells. Herein we aim to explore the association of PRL-3 with integrin β1 signaling and its functional implications in motility, invasion, and metastasis of colon cancer cell LoVo.</p> <p>Methods</p> <p>Transwell chamber assay and nude mouse model were used to study motility and invasion, and metastsis of LoVo colon cancer cells, respectively. Knockdown of integrin β1 by siRNA or lentivirus were detected with Western blot and RT-PCR. The effect of PRL-3 on integrin β1, ERK1/2, and MMPs that mediate motility, invasion, and metastasis were measured by Western blot, immunofluorencence, co-immunoprecipitation and zymographic assays.</p> <p>Results</p> <p>We demonstrated that PRL-3 associated with integrin β1 and its expression was positively correlated with ERK1/2 phosphorylation in colon cancer tissues. Depletion of integrin β1 with siRNA, not only abrogated the activation of ERK1/2 stimulated by PRL-3, but also abolished PRL-3-induced motility and invasion of LoVo cells in vitro. Similarly, inhibition of ERK1/2 phosphorylation with U0126 or MMP activity with GM6001 also impaired PRL-3-induced invasion. In addition, PRL-3 promoted gelatinolytic activity of MMP2, and this stimulation correlated with decreased TIMP2 expression. Moreover, PRL-3-stimulated lung metastasis of LoVo cells in a nude mouse model was inhibited when integrin β1 expression was interfered with shRNA.</p> <p>Conclusion</p> <p>Our results suggest that PRL-3's roles in motility, invasion, and metastasis in colon cancer are critically controlled by the integrin β1-ERK1/2-MMP2 signaling.</p

PAH–DNA Adducts in Cord Blood and Fetal and Child Development in a Chinese Cohort

Polycyclic aromatic hydrocarbons (PAHs) are an important class of toxic pollutants released by fossil fuel combustion. Other pollutants include metals and particulate matter. PAH–DNA adducts, or benzo[a]pyrene (BaP) adducts as their proxy, provide a chemical-specific measure of individual biologically effective doses that have been associated with increased risk of cancer and adverse birth outcomes. In the present study we examined the relationship between prenatal PAH exposure and fetal and child growth and development in Tongliang, China, where a seasonally operated coal-fired power plant was the major pollution source. In a cohort of 150 nonsmoking women and their newborns enrolled between 4 March 2002 and 19 June 2002, BaP–DNA adducts were measured in maternal and umbilical cord blood obtained at delivery. The number of gestational months occurring during the period of power plant operation provided a second, more general measure of exposure to plant emissions, in terms of duration. High PAH–DNA adduct levels (above the median of detectable adduct level) were associated with decreased birth head circumference (p = 0.057) and reduced children’s weight at 18 months, 24 months, and 30 months of age (p < 0.05), after controlling for potential confounders. In addition, in separate models, longer duration of prenatal exposure was associated with reduced birth length (p = 0.033) and reduced children’s height at 18 (p = 0.001), 24 (p < 0.001), and 30 months of age (p < 0.001). The findings suggest that exposure to elevated levels of PAHs, with the Tongliang power plant being a significant source, is associated with reduced fetal and child growth in this population

Prenatal Exposure to Polycyclic Aromatic Hydrocarbons, Benzo[a]pyrene–DNA Adducts, and Genomic DNA Methylation in Cord Blood

Background: Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic environmental pollutants generated during incomplete combustion. After exposure and during metabolism, PAHs can form reactive epoxides that can covalently bind to DNA. These PAH–DNA adducts are established markers of cancer risk. PAH exposure has been associated with epigenetic alterations, including genomic cytosine methylation. Both global hypomethylation and hypermethylation of specific genes have been associated with cancer and other diseases in humans. Experimental evidence suggests that PAH–DNA adduct formation may preferentially target methylated genomic regions. Early embryonic development may be a particularly susceptible period for PAH exposure, resulting in both increased PAH–DNA adducts and altered DNA methylation

Predictors and Consequences of Global DNA Methylation in Cord Blood and at Three Years

DNA methylation changes have been implicated in many common chronic diseases leading to the hypothesis that environmental and age-related DNA methylation changes within individuals are involved in disease etiology. Few studies have examined DNA methylation changes within an individual over time and all of these studies have been conducted in adults. Here, we aim to characterize how global DNA methylation changes from birth to age three within a longitudinal birth cohort study and to determine whether there are consistent predictors of DNA methylation levels measured three years apart. We measured global DNA methylation in the same children at birth (cord blood) and again at three years of age among 165 children, using an immunoassay. We found that on average, DNA methylation was significantly higher in blood at age 3-years than in cord blood (p&0.01). However, for any individual child, the difference was less than would be expected by chance. We found that pre-pregnancy BMI was negatively predictive of both cord and three-year DNA methylation, even after statistical adjustment to account for the correlation between cord blood and three-year DNA methylation. The biologic implications of small changes in global DNA methylation are unknown. However, the observation that global DNA methylation levels persist within an individual from birth to age three supports the belief that factors that influence global DNA methylation, including pre-pregnancy BMI, may confer long-term effects

Pathology Case Study: Two Weeks in Africa

The University of Pittsburgh School of Medicineâs Department of Pathology has compiled a series of case studies to help both students and instructors. In this clinical microbiology case, a 16-year-old male developed symptoms of fatigue, diarrhea, nausea, and vomiting after returning to the United States from a two-week trip to Sudan. Laboratory test results and information from a microscopic examination are included in the case study. Clicking on the âFinal Diagnosisâ section will take you to a detailed discussion of the patientâs condition from the contributing doctor. A list of references, which students could use to get more background information, is also included at the bottom of the section

Pathology Case Study: Petechiae

This is a case study presented by the University of Pittsburgh Department of Pathology in which a 6-hour-old baby was found to have petechiae. Visitors are given the case description and the opportunity to diagnose the patient. This is an excellent resource for students in the health sciences to familiarize themselves with using patient history and laboratory results to diagnose disease. It is also a helpful site for educators to use to introduce or test student learning in pathology and transfusion medicine