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Extremely high pressures over a million of atmospheres are required to deform diamonds permanently. Under dynamic high-pressure conditions, even such strong materials lose their strengths so rapidly that the initially pristine lattice transforms into complex dynamics. Here, we report femtosecond x-ray diffraction observations that directly resolve how shock waves deform the crystal lattice in the isotropic nano-polycrystalline form of diamond. The results show that the nano-grain reinforced diamond retains its strength at shock pressures far beyond its elastic limit until it finally approaches zero at 707 GPa, indicating the existence of brittle-ductile transition of nano-polycrystalline diamond under high-strain rate shock compression. The atomic-level deformation process of the diamond observed in this study is a key benchmark for designing high strength materials and simulating their behavior under extreme conditions.

The propagation of a shock wave in solids can stress them to ultra-high pressures of millions of atmospheres. Understanding the behavior of matter at these extreme pressures is essential to describe a wide range of physical phenomena, including the formation of planets, young stars and cores of super-Earths, as well as the behavior of advanced ceramic materials subjected to such stresses. Under megabar (Mbar) pressure, even a solid with high strength exhibits plastic properties, causing the shock wave to split in two. This phenomenon is described by theoretical models, but without direct experimental measurements to confirm them, their validity is still in doubt. Here, we present the results of an experiment in which the evolution of the coupled elastic-plastic wave structure in diamond was directly observed and studied with submicron spatial resolution, using the unique capabilities of the X-ray free-electron laser. The direct measurements allowed, for the first time, the fitting and validation of a strength model for diamond in the range of several Mbar by performing continuum mechanics simulations in 2D geometry. The presented experimental approach to the study of shock waves in solids opens up new possibilities for the direct verification and construction of the equations of state of matter in the ultra-high pressure range, which are relevant for the solution of a variety of problems in high energy density physics., Comment: 14 pages, 15 figures, submitted to Nature

High energy density physics 32, 63 - 69 (2019). doi:10.1016/j.hedp.2019.05.002, We present results from the SPring-8 Angstrom Compact free electron LAser (SACLA) X-ray free electron laser (XFEL) facility, using an X-ray pump, X-ray probe scheme to observe ultrafast changes in the structure of heated graphite. The 9.8 keV XFEL beam was focused to give an intensity on the order of ∼ 10$^{19}$ W/cm$^2$, and the evolution of the diffraction pattern observed up to delays of 300 fs. The interplanar diffraction peaks weaken significantly within 10s of femtoseconds, but in-plane diffraction orders i.e. those with Miller Index $(hk0)$, persist up to 300 fs, with the observed signal increasing. We interpret this as nonthermal damage through the breaking of interplanar bonds, which at longer timescales leads to ablation by removal of intact graphite sheets. Post-experiment examination of the graphite samples shows damage which is comparable in size to the range of the excited photoelectrons. These results highlight the challenges of accurately modelling X-ray driven heating, as it becomes a routine approach to generating high energy density states., Published by Elsevier, Amsterdam [u.a.]

High intensity X-ray Free Electron Lasers (XFEL) are an ideal tool to heat materials directly and isochorically, which can cause them to be modified and damaged irreversibly. During XFEL-matter interactions, the energy of an XFEL beam will be mainly absorbed by photoionization, creating numerous high-energy photo- and Auger electrons. Modelling this process is quite complex since both atomic physics and plasma physics are involved. Atomic collisional-radiative (CR) codes such as FLYCHK are widely used to simulate such processes. However, the CR codes typically assume local thermodynamic equilibrium (LTE) and are limited to zero dimension. In order to understand the sample damaging mechanisms, we performed two-dimensional kinetic particle-in-cell simulations with radiation transport (PIC-RT) to retrieve the temporal processes of XFEL-matter interactions. The dynamics of XFEL-Matter interactions can roughly divide into three different time scales: 1) electron heating and photoionization by XFEL in ~ 10 fs ; 2) collisional heating and ionization by high-energy photo- and Auger electrons with several keV energy in tens of fs to sub-ps; and 3) collective hydrodynamic explosion driven by ~ TPa thermal pressure from ~100 fs to nanoseconds. The simulation results are compared to our recent experiment that a variety of samples were irradiated by Japanese XFEL SACLA with intensities on the order of 10^20 W/cm^2. The post-analysis of the irradiated samples showed that large holes with radius sizes more than one order of magnitude higher than the XFEL spot were created for metallic samples. The hole size is also much larger than the stopping range of high energy electrons. According to our PIC-RT simulations, we attribute the generation of such large holes to the micro-explosion process. Kinect simulation of the hole generation with multiple time scales is also useful and complementary to understand the change of X-Ray diffraction pattern in the experiment that infers significant material structural change on femtosecond timescales.

Controlled/living radical polymerization was examined with the use of magnetic iron oxide (Fe3O4) prepared through various processes, including hydrothermal synthesis, a bioinspired process, and magnetotactic bacteria. Prior to the use of various types of Fe3O4, commercially available Fe3O4 was employed as a heterogeneous catalyst for styrene polymerization in conjunction with an alkyl halide as an initiator. Under appropriately optimized conditions, with the addition of Ph3P in a solvent mixture of toluene and DMF, the polymerization proceeded in a well-controlled manner. In addition, solid Fe3O4 was recovered using a magnetic approach and was reused for a polymerization reaction. The effects of stirring on the polymerization rate suggest that the surface of Fe3O4 is responsible for the catalysis in polymerization. Fe3O4 samples prepared through various processes were then used for styrene polymerization and showed different activities depending on the preparation process. In particular, Fe3O4 prepared through hydrothermal synthesis exhibited a much higher activity compared with commercial Fe3O4.

A singly charged ion source (SCIS) has been designed using a newly developed three-dimensional particle-in-cell (PIC) code. The SCIS is to be used in an isotope separation on-line (ISOL) system that provides 11C ions for heavy-ion cancer therapy with simultaneous verification of the dose distribution using positron emission tomography. The SCIS uses low-energy electron beams to produce singly charged carbon ions efficiently and maintain a high vacuum in the ISOL system. Because the SCIS has to realize a production efficiency of 1% if its carbon ions are to be used in the ISOL system, a suitable design for the SCIS was investigated by using the developed PIC code to study the beam trajectories of the electrons and extracted ions. The simulation results show that hollow electron beams are produced in the designed SCIS resulting in a high effective electron current. The results also predict that the designed SCIS would realize ion-production efficiencies (IPEs) of εSCIS ≃ 6.7% for CO+2 production from CO2 gas and εSCIS ≃ 0.1% for C+ production from CH4 gas. Moreover, to examine the validity of the developed code and confirm that the SCIS was able to be designed appropriately, the space-charge-limited current of the electron gun and the total IPE obtained by adding the IPEs of each ion were compared between the experiment and the simulation.

Short extraction called preliminary extraction has been added before irradiation in order to avoid an overshoot of the beam spill. A fast beam shutter was developed and installed in the extraction line to prevent the beam delivering to the patient during preliminary extraction. The fast shutter enables us to switch from preliminary extraction to irradiation in 100 ms, and the reliability of the beam-intensity control system was drastically improved by the preliminary extraction technique.

The Dome Fuji Project is a comprehensive study of present and past glaeiological/climatological features of the Antarctic ice sheet in east Dronning Maud Land. Field observations on a 100U km traverse route from the coast to Dome Fuji slum changes in various glaciological parameters with surface elevation and distance from the coast. Deep ice-core drilling at Dome Fuji was started in August 1995 and reached a depth of 2503.52 m in December 1996. in situ core analyses revealed 25 visible tephra layers and a number of distinct cloudy bands in the ice.

In order to improve the strain/stress characteristics of the critical current I_c, the availability of Nb matrix as well as the external CuNb reinforcing stabilizer to bronze processed Nb_3Sn multifilamentary superconducting wires has been examined up to the magnetic field of 14T and at a temperature of 4.2K. Although the axial tensile strain sensitivity of I_c does not change, the strain for peak I_c as well as the reversible strain limit increase in the wire with CuNb reinforcing stabilizer. Furthermore, the transverse compressive stress sensitivity of I_c decreases and the reversible stress limit increases. Although critical current density is not high, the Nb matrix Nb_3Sn wire shows higher tolerance to stress/strain. Correlation between axial strain effect and transverse compressive stress effect is briefly discussed.

The type of the Electron String Ion Sources (ESIS) is considered to be the appropriate one to produce pulsed C4+ and C6+ ion beams for cancer therapy accelerators. In fact, the new test ESIS Krion-6T already now provides more than 1010 C4+ ions per pulse and about 5 × 109 C6+ ions per pulse. Such ion sources could be suitable to apply at synchrotrons. It has also been found that Krion-6T can provide more than 1011 C6+ ions per second at the 100 Hz repetition rate, and the repetition rate can be increased at the same or larger ion output per second. This makes ESIS applicable at cyclotrons as well. ESIS can be also a suitable type of ion source to produce the 11C radioactive ion beams. A specialized cryogenic cell was experimentally tested at the Krion-2M ESIS for pulse injection of gaseous species into the electron string. It has been shown in experiments with stable methane that the total conversion efficiency of methane molecules to C4+ ions reached 5% ÷ 10%. For cancer therapy with simultaneous irradiation and precise dose control (positron emission tomography) by means of 11C, transporting to the tumor with the primary accelerated 11C4+ beam, this efficiency is preliminarily considered to be large enough to produce the 11C4+ beam from radioactive methane and to inject this beam into synchrotrons.

Summary Two substrains derived from an uncloned 71st embryo (E7)) passage and a cloned 71st embryo‐10th chick embryo kidney cell (E71CEK10) passage of the Beaudette strain of avian infectious bronchitis virus were back‐passaged through organ cultures of chick embryo trachea. The organ culture‐passaged viruses had altered biological properties such as absence of or delayed lethality for chick embryos and lack or diminution of plaque‐forming ability in chick embryo kidney monolayers but they showed no clear change of pathogenicity for 3‐week‐old chickens. These viruses regained their lethality for chick embryos, their cytopathic effects, and their plaque‐forming ability in chick embryo kidney cells after they had been back‐passaged through chick embryos, depending on the passage number. The results of cross neutralisation tests using the constant serum‐variable virus method in chick embryos indicated little antigenic difference between the original virus and various host‐passaged derivative strains.

The superconducting transition temperature T_c and the upper critical field H_ of the Nb_Ta_xSe_2 system have been measured by a resistive method. The increase of the anisotropy ratio H_/H_ has been found by addition of Ta. Analysis shows that this alloy compound. is treated as a three-dimensional superconductor with a strong anisotopy

Simple assay systems for infectivity titrations of avian infectious bronchitis virus (IBV) in chicken embryo trachea organ cultures (OC) were developed using plastic multiplate wells with one tracheal ring per well; these assays appeared to be much more satisfactory than the conventional rolled-tube method. The medium, 0.05 M HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid)-buffered Eagle minimal essential medium was not changed during observation. A medium containing 0.4% bovine serum albumin did not influence the virus yield, but did stabilize virus viability during storage. Reproducibility of results obtained in the OC system was confirmed by performing replicate titrations of the Beaudette strain with three different passage histories. The mean virus titers in the OC were lower than those in chicken embryos, depending on the IBV passage histories. The time required for ciliostasis was related not only to the concentration of virus, but also to the IBV passage history. Application of OC techniques for the constant serum-variable virus neutralization test gave low neutralization indexes with excellent reproducibility as compared with those obtained in the chicken embryo assay system. Also, the slopes of neutralization curves obtained by assays in OC were less steep than those seen in the chicken embryo system.

Three substrains were cloned from chick kidney cell monolayers infected with the Ishii strain of lentogenic Newcastle disease virus isolated in Japan. These substrains, which differed in plaque morphology, were distinguished as having no +24R+ and -24R- patterns in the hemagglutination (HA)-elution test.

Raster scanning irradiation has been carried out at a HIMAC new treatment facility in NIRS. In order to reduce the difference between prescribed and delivered dose distribution, the accurate beam-intensity control with a low ripple and the fast beam-on/off switching are strongly required. For this purpose, we have developed a new beam-intensity control system using the RFknockout slow extraction. To keep the beam rate constant, this system controls the transverse RF voltage with the feedback proportional-integral control. As a result of the experimental tests, it was verified that this system can modulate the beam-intensity with a low ripple and can switch the beam-on/off with quick responses.

The carbon-ion radiotherapy (RT) with HIMAC has been conducted since 1994, and the accumulated treatment number exceeded 9,000 in May 2014. During the last two decades, NIRS has developed both the accelerator and beam-delivery technologies related to the carbon-ion RT, which has brought several carbon-ion RT facilities in Japan. At present, NIRS has developed a carbon-ion rotating gantry with the superconducting technology to be operated from 2016. As the future plan, NIRS has developed a direct acceleration system of positron-emission beams for verification on an irradiation field, and NIRS also just starts a design study of a superconducting synchrotron ring for carbon-ion RT.

The effects of incubation temperature on virus growth and mortality patterns were studied in antibody-free chicken eggs inoculated with the B1 strain of Newcastle disease virus. Embryo mortality patterns did not differ much between 37, 39, and 41 C of incubation, although virus growth curves were higher at 39 C and 41 C than at 37 C. Below 35 C, embryo mortality was delayed, although from 48 hours after incubation the virus growth curves were similar to those at 37 C. In eggs with and without maternal antibody, virus titers were maximum 48 hours after incubation, although slightly higher in antibody-free eggs than in eggs with antibody whether the eggs were alive or dead. Eggs with maternal antibody had delayed mortality patterns.

Three Beaudette strains of infectious bronchitis virus (IBV) [two chicken-embryo trachea-culture-adapted (E71CET10 and E71CEK10CET30) and one embryo-adapted (E72)] were propagated in 10-day-old embryonated chicken eggs (CE) to investigate growth and lethality patterns. The E72 and E71CEK10CET30 viruses were similar in growth pattern as to logarithmic phase and maximum virus production, but 95% of the CE mortality with E72 virus occurred between 20 and 32 hours whereas with E71CEK10CET30 60% mortality occurred between 36 and 84 hours. The yield of the E71CET10 virus was minimum, with little lethality.