Adsorption and desorption of deuterium on partially oxidized Si(100) surfaces

Adsorption and desorption of deuterium are studied on the partially oxidized Si(100) surfaces. The partial oxygen coverage causes a decrease in the initial adsorption probability of D atoms. The observed D2 temperature-programmed-desorption (TPD) spectra comprise of multiple components depending on the oxygen coverage (θO). For θO=0.1ML the D2 TPD spectrum is deconvoluted into four components, each of which has a peak in the temperature region higher than the D2 TPD peaking at 780 K on the oxygen free surface. The highest TPD component with a peak around 1040 K is attributed to D adatoms on Si dimers backbonded by an oxygen atom. The other components are attributed to D adatoms on the nearest or second nearest sites of the O-backbonded Si dimers. D adatoms on the partially oxidized Si surfaces are abstracted by gaseous H atoms along two different abstraction pathways: one is the pathway along direct abstraction (ABS) to form HD molecules and the other is the pathway along indirect abstraction via collision-induced-desorption (CID) of D adatoms to form D2 molecules. The ABS pathway is less seriously affected by oxygen adatoms. On the other hand, the CID pathway receives a strong influence of oxygen adatoms since the range of surface temperature effective for CID is found to considerably shift to higher surface temperatures with increasing θO. Gradual substitution of D adatoms with H atoms during H exposure results in HD desorption along the CID pathway in addition to the ABS one. By employing a modulated beam technique the CID-related HD desorption is directly distinguished from the ABS-related one

Precipitation Behavior of Wrought Fe-Ni-Based Alloy HR6W

Age-hardening behavior of Fe-Ni-based alloy HR6W was investigated at the temperature range between 973 K and 1073 K. Two-step increase in hardness is detected for the alloy at each temperature; the first increase in hardness results from the precipitation of M23C6 phase and the second one corresponds to that of Laves phase. The TTP (time-temperature precipitation) diagram for the alloy is established based on the results of hardness measurement and microstructure observation, where the precipitation of Laves phase is slower than that of M23C6 phase by three orders of magnitude and the nose temperature of Laves phase is above 1073 K. The M23C6 phase precipitates with plate-like morphology along grain-boundaries at the early stage of aging, followed by the precipitation of Laves phase with granular morphology with increasing aging time. It is found that the M23C6 and Laves phases are aligned under stress condition, due to their precipitation on the dislocations introduced during creep deformation

Experimental H-type bovine spongiform encephalopathy characterized by plaques and glial- and stellate-type prion protein deposits

Atypical bovine spongiform encephalopathy (BSE) has recently been identified in Europe, North America, and Japan. It is classified as H-type and L-type BSE according to the molecular mass of the disease-associated prion protein (PrPSc). To investigate the topographical distribution and deposition patterns of immunolabeled PrPSc, H-type BSE isolate was inoculated intracerebrally into cattle. H-type BSE was successfully transmitted to 3 calves, with incubation periods between 500 and 600 days. Moderate to severe spongiform changes were detected in the cerebral and cerebellar cortices, basal ganglia, thalamus, and brainstem. H-type BSE was characterized by the presence of PrP-immunopositive amyloid plaques in the white matter of the cerebrum, basal ganglia, and thalamus. Moreover, intraglial-type immunolabeled PrPSc was prominent throughout the brain. Stellate-type immunolabeled PrPSc was conspicuous in the gray matter of the cerebral cortex, basal ganglia, and thalamus, but not in the brainstem. In addition, PrPSc accumulation was detected in the peripheral nervous tissues, such as trigeminal ganglia, dorsal root ganglia, optic nerve, retina, and neurohypophysis. Cattle are susceptible to H-type BSE with a shorter incubation period, showing distinct and distinguishable phenotypes of PrPSc accumulation

Intraspecies Prion Transmission Results in Selection of Sheep Scrapie Strains

Background: Sheep scrapie is caused by multiple prion strains, which have been classified on the basis of their biological characteristics in inbred mice. The heterogeneity of natural scrapie prions in individual sheep and in sheep flocks has not been clearly defined. Methodology/Principal Findings: In this study, we intravenously injected 2 sheep (Suffolk and Corriedale) with material from a natural case of sheep scrapie (Suffolk breed). These 3 sheep had identical prion protein (PrP) genotypes. The protease-resistant core of PrP (PrPres) in the experimental Suffolk sheep was similar to that in the original Suffolk sheep. In contrast, PrPres in the Corriedale sheep differed from the original PrPres but resembled the unusual scrapie isolate, CH1641. This unusual PrPres was not detected in the original sheep. The PrPres distributions in the brain and peripheral tissues differed between the 2 breeds of challenged sheep. A transmission study in wild-type and TgBoPrP mice, which overexpressing bovine PrP, led to the selection of different prion strains. The pathological features of prion diseases are thought to depend on the dominantly propagated strain. Conclusions/Significance: Our results indicate that prion strain selection occurs after both inter- and intraspecie

Sulfated Dextrans Enhance In Vitro Amplification of Bovine Spongiform Encephalopathy PrPSc and Enable Ultrasensitive Detection of Bovine PrPSc

Prions, infectious agents associated with prion diseases such as Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy (BSE) in cattle, and scrapie in sheep and goats, are primarily comprised of PrP(Sc), a protease-resistant misfolded isoform of the cellular prion protein PrP(C). Protein misfolding cyclic amplification (PMCA) is a highly sensitive technique used to detect minute amounts of scrapie PrP(Sc). However, the current PMCA technique has been unsuccessful in achieving good amplification in cattle. The detailed distribution of PrP(Sc) in BSE-affected cattle therefore remains unknown.We report here that PrP(Sc) derived from BSE-affected cattle can be amplified ultra-efficiently by PMCA in the presence of sulfated dextran compounds. This method is capable of amplifying very small amounts of PrP(Sc) from the saliva, palatine tonsils, lymph nodes, ileocecal region, and muscular tissues of BSE-affected cattle. Individual differences in the distribution of PrP(Sc) in spleen and cerebrospinal fluid samples were observed in terminal-stage animals. However, the presence of PrP(Sc) in blood was not substantiated in the BSE-affected cattle examined.The distribution of PrP(Sc) is not restricted to the nervous system and can spread to peripheral tissues in the terminal disease stage. The finding that PrP(Sc) could be amplified in the saliva of an asymptomatic animal suggests a potential usefulness of this technique for BSE diagnosis. This highly sensitive method also has other practical applications, including safety evaluation or safety assurance of products and byproducts manufactured from bovine source materials

Vacuolating cytotoxin and variants in Atg16L1 that disrupt autophagy promote Helicobacter pylori infection in humans

Peer reviewedPreprin

Structural variation in the incoming Philippine Sea plate along the Nankai Trough

The next large-thrust earthquake along the Nankai Trough, southwest Japan is concerned to occur within this century. Nonvolcanic deep low-frequency tremors and earthquakes are observed around the down-dip limit of the coseismic rupture zone of the last Tonankai and Nankai earthquakes [Obara, 2002]. One of the causes of these low-frequency seismic phenomena is considered to be fluid generated by dehydration processes from the subducting slab. It is important to investigate structural variation in the incoming Philippine Sea plate, including its fluid content to understand the generation of the low-frequency seismic phenomena as well as large-thrust earthquakes. In 2014, we conducted the seismic refraction and reflection survey in the northern margin of the Shikoku Basin, where the Philippine Sea plate is subducting beneath the Eurasia plate at the Nankai Trough. We conducted a 360km long seismic profile about 50-60km seaward of the deformation front along the Nankai Trough. 35 OBSs were deployed along the profile with the interval of 10km. A tuned airgun array shot with a total volume of 7800 cu. in. every 200m for OBSs, and 380 cu. in. every 37.5m for a 192-channel, 1.2km-long hydrophone streamer. In the time-migrated reflection section, variation in the sedimentary layer and basement reflection can be recognized off Shikoku, which may correspond with the boundary of the plate age proposed by magnetic lineation [Okino et al., 1999]. In the southwestern part of the profile, the basement reflection is not always clear, and shows smooth structure. Comparatively in the northeastern part, basement changes in depth drastically with prominent reflection signals. In the wide-angle OBS data, PS converted waves are clearly observed over along the seismic profile. In particular, PS converted waves refracted from the uppermost mantle can be remarkably recognized in the northeastern half of the profile. We will show the structural variation of the oceanic crust of the incoming plate, which may be related to the formation of the Shikoku Basin as well as the generation of the various seismic activities including the low-frequency events, by using OBS data. This study is part of ‘Research project for compound disaster mitigation on the great earthquakes and tsunamis around the Nankai Trough region’ funded by MEXT, Japan.Poster abstract T51A-4578 presented at 2014 Fall Meeting, AGU, San Francisco, Calif., 15-19 Dec.http://www.godac.jamstec.go.jp/darwin/cruise/kairei/kr14-05/ehttp://www.godac.jamstec.go.jp/darwin/cruise/kaiyo/ky14-07/

Isolation of two distinct prion strains from a scrapie-affected sheep

We performed a transmission study using mice to clarify the characteristics of the most recent case of scrapie in Japan. The mice that were inoculated with the brain homogenate from a scrapie-affected sheep developed progressive neurological disease, and one of the scrapie-affected mice showed unique clinical signs during primary transmission. This mouse developed obesity, polydipsia, and polyuria. In contrast, the other affected mice exhibited weight loss and hypokinesia. In subsequent passages, the mice showed distinct characteristic scrapie phenotypes. This finding may prove that different prion strains coexist in a naturally affected sheep with scrapie