1,390 research outputs found

    Evaluation of forest decontamination using radiometric measurements

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    An experiment has been conducted to evaluate the additional dose reduction by clear felling contaminated forestry in Fukushima Prefecture, Japan, and using the timber to cover the areas with wood chips. A portable gamma spectrometry system, comprising a backpack containing a 3x3” NaI(Tl) detector with digital spectrometer and GPS receiver, has been used to map dose rate and radionuclide activity concentrations before, after and at stages during this experiment. The data show the effect of the different stages of the experiment on dose rate at different locations around the site. The spectrometric data have allowed the assessment of the contributions of natural and anthropogenic radionuclides to the dose rate at different parts of the site before and after the experiment. This has clearly demonstrated the value of radiometric methods in evaluating remediation, and the effect of other environmental processes. The value of spectrometric methods which directly measure radionuclide concentrations has also been shown, especially through the identification of the contribution of natural and anthropogenic activity to the measured dose rate. The experiment has shown that clearing trees and applying wood chips can reduce dose rates by 10-15% beyond that achieved by just clearing the forest litter and natural redistribution of radiocaesium

    Synthesis of fused tricyclic peptides using a reprogrammed translation system and chemical modification

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    AbstractHere we report a unique method of ribosomally synthesizing fused tricyclic peptides. Flexizyme-assisted in vitro translation of a linear peptide with the N-terminal chloroacetyl group and four downstream cysteines followed by the addition of 1,3,5-tris(bromomethyl)benzene results in selective production of the fused tricyclic peptide. This technology can be used for the ribosomal synthesis of fused tricyclic peptide libraries for the in vitro selection of bioactive peptides with tricyclic topology

    Phase Diagram for Self-assembly of Amphiphilic Molecule C12E6 by Dissipative Particle Dynamics Simulation

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    In a previous study, dissipative particle dynamics simulation was used to qualitatively clarify the phase diagram of the amphiphilic molecule hexaethylene glycol dodecyl ether (C12E6). In the present study, the hydrophilicity dependence of the phase structure was clarified qualitatively by varying the interaction potential between hydrophilic molecules and water molecules in a dissipative particle dynamics (DPD) simulation using the Jury model. By varying the coefficient of the interaction potential xx between hydrophilic beads and water molecules as x=-20, 0, 10, and 20, at a dimensionless temperature of T=0.5 and a concentration of amphiphilic molecules in water of phi=50% the phase structures grew to lamellar (x=-20), hexagonal (x=0), and micellar (x=10) phases. For x=20, phase separation occurs between hydrophilic beads and water molecules

    Active and Passive Monitoring and Analysis of IP Option Header Transparency from Covert Channel Point of View

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    In a context of network covert channels, unused header fields in communication protocols are vulnerable to embed secret data. An IP Option field in the IP header is considered as one of useful spaces for constructing the Internet-wide network covert channels. On the other hand, IP packets with IP Option have been said non-transparent on the global Internet. This paper investigates how an IP packet with IP option can be going through over the Internet by active and passive monitoring methods. At first, we investigated AS border traffic in an academic AS and a commercial IX. The result was that only four types of IP Options, Route Record (RR), Time Stamp (TS), No Operation (NOP) and End of Option List (EOOL), were observed. Then, we preliminary evaluated transparency of these four types IP Options over the global Internet by probing from ten Planetlab nodes on six countries against 5,000 randomly chosen destination IP addresses and 11,251 intermediate routers. Both destination addresses and intermediate routers were included in 1,132 intermediate ASes. As the active measurement result, 57% routers replied to IP packets with the RR Option, that is, the RR Option was transparent in 914 intermediate ASes on this experiment. On the other hand, 41% of intermediate routers replied probe packets with the TS option, that is, the TS Option was transparent in 811 intermediate ASes on this experiment

    Magnetization Curves of the Reentrant-Spin-Glass Fe_<0.65>Mn_<0.35>TiO_3 : Dependence on the Sweep Rate of Magnetic Fields(Magnetism)

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    The magnetization curves of the reentrant-spin-glass Fe_Mn_TiO_3 have been observed at 4.2 K and 1.4 K in applied fields with various sweep rates. Depending on the sweep rates and temperatures, the anomalous jumps of the magnetizations towards the values of the field-cooled-magnetization M^ are observed. This phenomenon is interpreted to be closely related to the properties of the spin-glass state

    Ejecta Size Distribution Resulting from Hypervelocity Impact of Spherical Projectiles on CFRP Laminates

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    AbstractThe size distributions of ejecta resulting from projectile perforation of CFRP (carbon fiber reinforced plastic) laminates were examined. The shape of the ejecta cone and the debris cloud was observed using a high-speed video camera. The ejecta fragments were collected from the test chamber after impact experiments. The number of fragments ejected on the front side of the target was altered by the impact velocity. Conversely, regardless of impact velocity, the number of fragments ejected on the rear side of the target was almost the same.The results were also compared with the results of NASA's breakup model. The slope on the cumulative number distribution curve of characteristic length, LC, was almost the same as that of NASA's breakup model. The area-to-mass ratio distribution of ejecta fragments from CFRP laminates ranged within and above the area surrounded by ±3σ of NASA's breakup model