Some Geotechnical Aspects of 1999 Chi-Chi, Taiwan Earthquake

The Chi-Chi, Taiwan earthquake with a magnitude of 7.3 occurred on September 21, 1999. It was the largest and most damaging earthquake in Taiwan in a century. It induced extensive geotechnical hazards including landslides, soil liquefaction, foundation failures, and ground movements in central Taiwan, and caused substantial damages to buildings, roadways, bridges, and waterfront structures. Field investigations and studies in geotechnical aspects, including landslides, soil liquefaction, foundations, retaining structures, dams and tunnels, in the affected areas were performed. The results of field explorations and laboratory tests for the study of soil liquefaction and evaluation of the secondary hazard of debris flow are also discussed

Post-closure performance assessment of waste packages for the Yucca Mountain Project

This report details a system model of some core features of the performance of waste packages for the permanent disposal of spent nuclear fuel at the Yucca Mountain Site. The model is realized in the prototype computer program PANDORA-1.1. The PANDORA system model links processes leading to possible release of radionuclides from the waste package. The PANDORA submodels are being developed for processes and conditions specific to this potential repository site, notably the comparatively dry location in an arid area and well above the groundwater table, and the rock medium of porous partially welded tuff

Performance of the transverse coupled-bunch feedback system in the SRRC

A transverse feedback system has been implemented and commissioned in the SRRC storage ring to suppress transverse coupled-bunch oscillations of the electron beam. The system includes transverse oscillation detectors, notch filter, baseband quadrature processing circuitry, power amplifiers, and kickers. To control a large number of transverse coupled-bunch modes, the system is broad-band, bunch-by- bunch in nature. Because the system is capable of bunch-by-bunch correction, it can also be useful for suppressing instabilities introduced by ions. The sextupole strength was then reduced to improve dynamic aperture and hence lifetime of the storage ring

[1,3-Bis(diphenyl­phosphino)pentane-κ2 P,P′]tetra­carbonyl­chromium(0)

In the title compound, [Cr(C29H30P2)(CO)4], the Cr atom is octa­hedrally coordinated by four carbonyl ligands and one bidentate phosphine ligand, which is bounded as a chelate in a cis position. The average Cr—P and Cr—C bond lengths are 2.377 and 1.865 Å, respectively

Second-Hand Smoke–Induced Cardiac Fibrosis Is Related to the Fas Death Receptor Apoptotic Pathway without Mitochondria-Dependent Pathway Involvement in Rats

Exposure to environmental tobacco smoke has been epidemiologically linked to heart disease among nonsmokers. However, the molecular mechanism behind the pathogenesis of cardiac disease is unknown. In this study, we found that Wistar rats, exposed to tobacco cigarette smoke at doses of 5, 10, or 15 cigarettes for 30 min twice a day for 1 month, had a dose-dependently reduced heart weight to body weight ratio and enhanced interstitial fibrosis as identified by histopathologic analysis. The mRNA and activity of matrix metalloprotease-2 (MMP-2), representing the progress of cardiac remodeling, were also elevated in the heart. In addition, we used reverse-transcriptase polymerase chain reaction and Western blotting to demonstrate significantly increased levels of the apoptotic effecter caspase-3 in treated animal hearts. Dose-dependently elevated mRNA and protein levels of Fas, and promoted apoptotic initiator caspase-8 (active form), a molecule of a death-receptor–dependent pathway, coupled with unaltered or decreased levels of cytosolic cytochrome c and the apoptotic initiator caspase-9 (active form), molecules of mitochondria-dependent pathways, may be indicative of cardiac apoptosis, which is Fas death-receptor apoptotic-signaling dependent, but not mitochondria pathway dependent in rats exposed to second-hand smoke (SHS). With regard to the regulation of survival pathway, using dot blotting, we found cardiac insulin-like growth factor-1 (IGF-1) and IGF-1 receptor mRNA levels to be significantly increased, indicating that compensative effects of IGF-1 survival signaling could occur. In conclusion, we found that the effects of SHS on cardiomyocyte are mediated by the Fas death-receptor–dependent apoptotic pathway and might be related to the epidemiologic incidence of cardiac disease of SHS-exposed non-smokers

Experimental approaches to evaluate activities of cytochromes P450 3A

Cytochrome P450 (CYP) is a heme protein oxidizing various xenobiotics, as well as endogenous substrates. Understanding which CYP enzymes are involved in metabolic activation and/or detoxication of different compounds is important in the assessment of an individual's susceptibility to the toxic action of these substances. Therefore, investigation which of several in vitro experimental models are appropriate to mimic metabolism of xenobiotics in organisms is the major challenge for research of many laboratories. The aim of this study was to evaluate the efficiency of different in vitro systems containing individual enzymes of the mixed-function monooxygenase system to oxidize two model substrates of CYP3A enzymes, exogenous and endogenous compounds, α-naphtoflavone (α-NF) and testosterone, respectively. Several different enzymatic systems containing CYP3A enzymes were utilized in the study: (i) human hepatic microsomes rich in CYP3A4, (ii) hepatic microsomes of rabbits treated with a CYP3A6 inducer, rifampicine, (iii) microsomes of Baculovirus transfected insect cells containing recombinant human CYP3A4 and NADPH:CYP reductase with or without cytochrome b5 (Supersomes™), (iv) membranes isolated from of Escherichia coli, containing recombinant human CYP3A4 and cytochrome b5, and (v) purified human CYP3A4 or rabbit CYP3A6 reconstituted with NADPH:CYP reductase with or without cytochrome b5 in liposomes. The most efficient systems oxidizing both compounds were Supersomes™ containing human CYP3A4 and cytochrome b5. The results presented in this study demonstrate the suitability of the supersomal CYP3A4 systems for studies investigating oxidation of testosterone and α-NF in vitro

The modulation of topoisomerase I-mediated DNA cleavage and the induction of DNA–topoisomerase I crosslinks by crotonaldehyde-derived DNA adducts

Crotonaldehyde is a representative α,β-unsaturated aldehyde endowed of mutagenic and carcinogenic properties related to its propensity to react with DNA. Cyclic crotonaldehyde-derived deoxyguanosine (CrA-PdG) adducts can undergo ring opening in duplex DNA to yield a highly reactive aldehydic moiety. Here, we demonstrate that site-specifically modified DNA oligonucleotides containing a single CrA-PdG adduct can form crosslinks with topoisomerase I (Top1), both directly and indirectly. Direct covalent complex formation between the CrA-PdG adduct and Top1 is detectable after reduction with sodium cyanoborohydride, which is consistent with the formation of a Schiff base between Top1 and the ring open aldehyde form of the adduct. In addition, we show that the CrA-PdG adduct alters the cleavage and religation activities of Top1. It suppresses Top1 cleavage complexes at the adduct site and induces both reversible and irreversible cleavage complexes adjacent to the CrA-PdG adduct. The formation of stable DNA–Top1 crosslinks and the induction of Top1 cleavage complexes by CrA-PdG are mutually exclusive. Lastly, we found that crotonaldehyde induces the formation of DNA–Top1 complexes in mammalian cells, which suggests a potential relationship between formation of DNA–Top1 crosslinks and the mutagenic and carcinogenic properties of crotonaldehyde