2,897 research outputs found
A new recursive dynamic factor analysis for point and interval forecast of electricity price
published_or_final_versio
A 60-year record of 129I in Taal Lake sediments (Philippines): Influenceof human nuclear activities at low latitude region
The influence of human nuclear activities on environmental radioactivity is not well known at low latitude regions that are distant from nuclear test sites and nuclear facilities. A sediment core collected from Taal Lake in the central Philippines was analyzed for 129I and 127I to investigate this influence in a low-latitude terrestrial system. A baseline of 129I/127I atomic ratios was established at (2.04e5.14) * 10-12 in the pre-nuclear era in this region. Controlled by the northeasterly equatorial trade winds, increased
129I/127I ratios of (20.1e69.3) * 10-12 suggest that atmospheric nuclear weapons tests at the Pacific Proving Grounds in the central Pacific Ocean was the major source of 129I in the sediment during 1956-1962. The 129I/127I ratios, up to 157.5*10-12 after 1964, indicate a strong influence by European nuclear fuel reprocessing plants. The East Asian Winter Monsoon is found to be the dominant driving force in the atmospheric dispersion of radioactive iodine (129I) from the European nuclear fuel reprocessing plants to Southeast Asia, which is also important for dispersion of other airborne pollutants from the middle-high to low latitude regions. A significant 129I/127I peak at 42.8 cm in the Taal Lake core appears to be the signal of the Chernobyl accident in 1986. In addition, volcanic activities are reflected in the iodine isotope profiles in the sediment core, suggesting the potential of using iodine isotopes as an indicator of volcanic eruptions.<br style="line-height: normal; text-align: -webkit-auto; text-size-adjust: auto;" /
The technology of large-scale pharmaceutical plasmid purification by cetyltrimethylammonium bromide and Tritonx-114
Many methods for plasmid purification have been developed, and the whole process must be designed to remove the host RNA, protein, genomic DNA and endotoxin. Currently, plasmid is mostly purified by time-consuming chromatographies. As an alternative, a new plasmid purification technology with cetyltrimethylammonium bromide (CTAB) is described. After lysis with alkali, the CTAB was directly titrated into the supernatant for plasmid precipitation, then the coprecipitated pellets were dealt with 3 M KAc and TritonX-114. Quality detection showed that the purified plasmids were free from the contamination of host RNA. In 1 mg purified plasmid, the bacterial genomic DNA, host endotoxin and protein were less than 10 g/ mg, 50 EU/ mg and 10 g/mg, respectively. The ratio of OD260/OD280 was between 1.75 - 1.85, more than 90% of the prepared plasmid presented in the supercoiled form. Further test demonstrated that the pcDNAlacZ purified with CTAB and authoritative endotoxin-free plasmid Kit had the similar transfection efficiency in vivo and in vitro. CTAB can be used for plasmid purification; the main advantages of the DNAs purified with CTAB include the avoidance of animal-derived enzymes, toxic substance like chloroform and phenol. More attractive is that the whole process has the predominance of low cost
Load/Price Forecasting and Management of Demand Response for Smart Grids: Methodologies and Challenges
published_or_final_versio
Boron carbide amorphous solid with tunable band gap
Boron carbide BxC (x = 1/6 − 10) powders were synthesized through a microwave-assisted carbothermic reduction reaction as a potential clean energy material. Their crystallographic structures and optical properties were characterized. X-ray diffraction and electron diffraction indicated that the synthesized BxC powders were amorphous. Electron energy-loss spectroscopy demonstrated that the composition of boron and carbon was in amorphous materials, and their chemical bonding were disclosed from Raman scattering spectroscopy. UV–vis absorption spectroscopy indicated that the bandgap of the bulks varied from 2.30eV to 3.90eV, tuned by the boron/carbon element ratio. The synthesized powders were potential photovoltaic materials. A short-range ordering model was established to explain the optical properties
Effects of Short-Term Exposure to Inhalable Particulate Matter on Telomere Length, Telomerase Expression, and Telomerase Methylation in Steel Workers
Shortened leukocyte telomere length (LTL) is a marker of cardiovascular risk that has been recently associated with long-term exposure to ambient particulate matter (PM). However, LTL is increased during acute inflammation and allows for rapid proliferation of inflammatory cells. Whether short-term exposure to proinflammatory exposures such as PM increases LTL has never been evaluated.We investigated the effects of acute exposure to metal-rich PM on blood LTL, as well as molecular mechanisms contributing to LTL regulation in a group of steel workers with high PM exposure.We measured LTL, as well as mRNA expression and promoter DNA methylation of the telomerase catalytic enzyme gene [human telomerase reverse transcriptase (hTERT)] in blood samples obtained from 63 steel workers on the first day of a workweek (baseline) and after 3 days of work (postexposure).LTL was significantly increased in postexposure (mean \ub1 SD, 1.43 \ub1 0.51) compared with baseline samples (1.23 \ub1 0.28, p-value < 0.001). Postexposure LTL was positively associated with PM\u2081\u2080 (\u3b2 = 0.30, p-value = 0.002 for 90th vs. 10th percentile exposure) and PM\u2081 (\u3b2 = 0.29, p-value = 0.042) exposure levels in regression models adjusting for multiple covariates. hTERT expression was lower in postexposure samples (1.31 \ub1 0.75) than at baseline (1.68 \ub1 0.86, p-value < 0.001), but the decrease in hTERT expression did not show a dose-response relationship with PM. We found no exposure-related differences in the methylation of any of the CpG sites investigated in the hTERT promoter.Short-term exposure to PM caused a rapid increase in blood LTL. The LTL increase did not appear to be mediated by PM-related changes in hTERT expression and methylation
A study on the functions of ubiquitin metabolic system related gene FBG2 in gastric cancer cell line
<p>Abstract</p> <p>Background</p> <p>FBG2 (F-BOX6) gene is an important member in ubiquitin metabolic system F-BOX family, and forms E3 complex with the other members in the family. But its role in gastric cancer is still not clear. In the present study, we intended to investigate the influence of FBG2 on the growth, proliferation, apoptosis, invasion and cell cycle of the gastric cancer line MKN45 and gastric cell line HFE145.</p> <p>Methods</p> <p>As a critical component of ubiquitin-protein ligase complex, FBG2 cDNA was subcloned into a constitutive vector PCDNA3.1 followed by transfection in MKN45 and HFE145 by using liposome. Then stable transfectants were selected and appraised. The apoptosis and cell cycles of these clones were analyzed by using flow cytometry. The growth and proliferation were analyzed by cell growth curves and colony-forming assay respectively. The invasion of these clones was tested by using cancer cell migration assay. The FBG2 stable expression clones(MKN-FBG2 and HFE-FBG2) and their control groups were detected and compared respectively.</p> <p>Results</p> <p>MKN-FBG2 grew faster than MKN45 and MKN-PC(MKN45 transfected with PCDNA3.1 vector). HFE-FBG2 grew faster than HFE145 and HFE-PC(HFE145 transfected with PCDNA3.1 vector). The cell counts of MKN-FBG2 in the forth, fifth, sixth and seventh days were significantly more than those of others (P < 0.05). Cell cycle analysis showed that MKN-FBG2 and HFE-FBG2 proliferated faster, proportions of cells in G2-M and S were different significantly with control groups (P < 0.05). Results of colony-forming assay showed that the colony formation rates of MKN-FBG2 and HFE-FBG2 were higher than those of control groups (P < 0.05). The results of cell migration assay were all negative.</p> <p>Conclusion</p> <p>FBG2 can promote the growth and proliferation of gastric cancer cells and normal gastric cells. It can help tumor cell maintain malignant phenotype too. But it can have a negative influence on the apoptosis or the ability of invasion of gastric cancer cells.</p
Correlation of cell growth and heterologous protein production by Saccharomyces cerevisiae
With the increasing demand for biopharmaceutical proteins and industrial enzymes, it is necessary to optimize the production by microbial fermentation or cell cultures. Yeasts are well established for the production of a wide range of recombinant proteins, but there are also some limitations; e.g., metabolic and cellular stresses have a strong impact on recombinant protein production. In this work, we investigated the effect of the specific growth rate on the production of two different recombinant proteins. Our results show that human insulin precursor is produced in a growth-associated manner, whereas alpha-amylase tends to have a higher yield on substrate at low specific growth rates. Based on transcriptional analysis, we found that the difference in the production of the two proteins as function of the specific growth rate is mainly due to differences in endoplasmic reticulum processing, protein turnover, cell cycle, and global stress response. We also found that there is a shift at a specific growth rate of 0.1 h(-1) that influences protein production. Thus, for lower specific growth rates, the alpha-amylase and insulin precursor-producing strains present similar cell responses and phenotypes, whereas for higher specific growth rates, the two strains respond differently to changes in the specific growth rate
Airborne particulate matter and mitochondrial damage: a cross-sectional study
<p>Abstract</p> <p>Background</p> <p>Oxidative stress generation is a primary mechanism mediating the effects of Particulate Matter (PM) on human health. Although mitochondria are both the major intracellular source and target of oxidative stress, the effect of PM on mitochondria has never been evaluated in exposed individuals.</p> <p>Methods</p> <p>In 63 male healthy steel workers from Brescia, Italy, studied between April and May 2006, we evaluated whether exposure to PM was associated with increased mitochondrial DNA copy number (MtDNAcn), an established marker of mitochondria damage and malfunctioning. Relative MtDNAcn (RMtDNAcn) was determined by real-time PCR in blood DNA obtained on the 1<sup>st </sup>(time 1) and 4<sup>th </sup>day (time 2) of the same work week. Individual exposures to PM<sub>10</sub>, PM<sub>1</sub>, coarse particles (PM<sub>10</sub>-PM<sub>1</sub>) and airborne metal components of PM<sub>10 </sub>(chromium, lead, arsenic, nickel, manganese) were estimated based on measurements in the 11 work areas and time spent by the study subjects in each area.</p> <p>Results</p> <p>RMtDNAcn was higher on the 4<sup>th </sup>day (mean = 1.31; 95%CI = 1.22 to 1.40) than on the 1<sup>st </sup>day of the work week (mean = 1.09; 95%CI = 1.00 to 1.17). PM exposure was positively associated with RMtDNAcn on either the 4<sup>th </sup>(PM<sub>10</sub>: β = 0.06, 95%CI = -0.06 to 0.17; PM<sub>1</sub>: β = 0.08, 95%CI = -0.08 to 0.23; coarse: β = 0.06, 95%CI = -0.06 to 0.17) or the 1<sup>st </sup>day (PM<sub>10</sub>: β = 0.18, 95%CI = 0.09 to 0.26; PM<sub>1</sub>: β = 0.23, 95%CI = 0.11 to 0.35; coarse: β = 0.17, 95%CI = 0.09 to 0.26). Metal concentrations were not associated with RMtDNAcn.</p> <p>Conclusions</p> <p>PM exposure is associated with damaged mitochondria, as reflected in increased MtDNAcn. Damaged mitochondria may intensify oxidative-stress production and effects.</p
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