Evaluation of polycarbonate substrate hologram recording medium regarding implication of birefringence and thermal expansion

In this paper, we evaluate photopolymer media using a polycarbonate (PC) substrate. In holographic data storage medium, substrates that sandwich the photopolymer material are needed to protect the photopolymer material against exogenous shock and open air. An optical glass such as BK-7 is normally used as a substrate, but a PC substrate has a cost advantage and is easy to fabricate compared with optical glass. For holographic recording and reading, however, the high birefringence and high thermal expansion of a PC substrate are significant problems. First, we analyze the degree of degradation of output power by the polarization change and estimate the threshold value of birefringence to record hologram normally. Next, we estimate the temperature tolerance of hologram readout with polycarbonate substrate hologram medium. These analyses results indicate the possible usage of the PC substrate as holographic recording media.     

Analysis of carcinogenic mechanisms of liver cancers induced by chronic exposure to alpha-particles from internally deposited Thorotrast

For the successful space traveling, the possibility for the detrimental effects on health including cancer caused by exposure to cosmic rays is a major concern. Thorotrast is a 25% colloidal solution of natural -emitter, thorium dioxide used as a radiological contrast medium during World War II. It caused hepatic malignant tumors by the local exposure to -particles decades after administration. Thorotrast-induced liver tumors consist of hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC), and angiosarcoma (AS) at nearly the same instance. We analyzed mutations of the p53 and the K-ras genes, microsatellite instability (MSI), and loss of heterozygosity (LOH) in Thorotrast ICC. The major p53 mutation observed in Thorotrast ICC was the transition type, suggesting that reactive oxygen species are not likely involved in gene mutations of Thorotrast cancers. MSI frequency in Thorotrast ICC was significantly higher than that in non-Thorotrast ICC. MSI was partly attributed to the inactivation of the hMLH1 mismatch repair gene via methylation of the promoter region and to monoclonal expansion of cells with mutations. Thorotrast ICC shared LOH pattern with non-Thorotrast HCC and ICC. Furthermore, we could assess the distribution and the quantity of deposited thorium using an imaging plate and a BAS image analyzer. The distribution of thorium deposits was not always consistent with that of apoptotic cells. We conclude that Thorotrast ICC is developed through complex carcinogenic steps including genomic instability and mutations of crucial genes during remodeling of the liver architecture. We emphasize how pathological specimens from Thorotrast patients are valuable for assessing the relevance of long-term exposure to low dose -particles to radiation carcinogenesis.     

Acute toxicity and metabolism of arsenocholine in mice

The acute toxicity of arsenocholine was examined in mice by oral administration and intravenous injection. The LD₅₀ values of arsenocholine were 6.5 g kg^?1 for oral administration and 187 mg kg^?1 for oral administration and 187 mg kg^?1 for intravenous injection. Decreases of respiration and spontaneous motility were observed in the mice dosed orally at 12 g kg^?1. The animals exhibited ataxia and finally showed paralysis of the hind legs within 20 min of administration. When arsenocholine was administered orally to mice at 5 or 50 mg As kg^?1, the greater part of the arsenic administered was recovered in urine within 96 h. The metabolite of arsenocholine in urine was identified as arsenobetaine by high-performance liquid chromatography-inductively coupled plasma emission spectrometry (HPLC ICP) and fast atom bombardment mass spectrometry (FAB MS). These results suggested that the major part of orally administered arsenocholine was absorbed from the gastrointestinal tract in mice and then rapidly excreted in urine with biotransformation.     

A novel stereocontrolled approach to steroid side chain construction: asymmetric synthesis of potential synthon of the vitamin D series

Stereocontrolled synthesis of (?)-de-AB-8-oxa-cholest-14-en-9-one (2) as an optically active form was achieved starting from the methylene ketone (7). This work constitutes a formal synthesis of de-AB-cholestan (1).     

Synthetic approach to grayanotoxins and asebotoxins: a new construction of the a-homograyanotoxane ring system

The tetracyclic compounds ～3 and ～4 corresponding to A-homograyanotoxane system were synthesised by a thermolysis of the benzocyclobutene ～8, followed by a Wagner-Meerwein rearrangement of the kaurane type of compounds ～15 and ～16.     

Total synthesis of carbomycin B and josamycin (leucomycin A3)

The stereospecific total synthesis of macrolide antibiotics, carbomycin B and josamycin (leucomycin A₃), is described. The key aglycone has been synthesized by coupling two segments of C1–C10 and C11–C16 portions, which are stereospecifically derived from glucose.     

Relationship between reactivity and 13C chemical shifts of benzocyclobutenes

¹³C NMR spectra of benzocyclobutene derivatives have been investigated; substituent effects and the relationship between the chemical shifts and the reactivity of their cyclobutene ring are discussed.     

Optimal checkpointing intervals of three error detection schemes by a double modular redundancy

This paper considers three checkpointing schemes which combine a double modular redundancy and three types of checkpoints: compare-and-store-checkpoint (CSCP), store-checkpoint (SCP), and compare-checkpoint (CCP). An execution time of a task is divided equally into n intervals, and at the end of each interval, a CSCP is always placed. Further, each CSCP interval is also divided equally into m intervals, and at the end of each interval, either CCP or SCP is placed except the last one. Introducing the overheads of comparison, storage, and retry, the mean execution times to complete a task for three schemes are obtained, using the theory of probability. Optimal checkpointing intervals, which minimize the mean times, are analytically derived, and are numerically computed. Three schemes are compared as numerical examples and the best checkpointing scheme is chosen.