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Results of analysis of swelling behaviour of alloying austenitic steels are described from the point of view of the cooperative interaction of defect structure, solid solution decay and precipitates evolution.

Oxide-dispersion-strengthened (ODS) ferritic steel incorporating nanoscale oxide particles was produced by mechanical alloying, and the complex oxide particles, comprised of titanium and yttrium, characterized by high-resolution transmission electron microscopy (HRTEM) and characteristic X-ray nano-analyses. The interface between the ferritic matrix and the major Ti-Y complex oxide was incoherent. From HRTEM and characteristic X-ray nano-analyses, plus the extremely limited literature data on ODS ferritic steels, it was determined that the most stable complex oxide was cubic Y2Ti2O7, which formed by a spontaneous reaction between nano-sized ceramics with a low solubility limit in the metal.

This paper describes the design features and operational status of the RF systems for the KEK B-Factory (KEKB). Two types of new RF cavities have been developed to store very high-intensity beams with many short bunches. The design and performance of the cavities and other critical components, such as the input couplers and HOM dampers, are reported. The configuration of the RF systems is given and descriptions of various control loops are made, including a direct RF feedback loop and a 0-mode damping loop. The effects of transient beam loading due to a bunch gap on bunch phase modulations were simulated and measured. The development of a superconducting crab cavity, which is a component of luminosity upgrade strategy, is also presented.

An 8-GeV electron/3.5-GeV positron injector for KEKB was completed in 1998 by upgrading the existing 2.5-GeV electron/positron linac. The main goals were to upgrade its accelerating energy from 2.5 to 8 GeV and to increase the positron intensity by about 20 times. This article describes not only the composition and features of the upgraded linac, but also how these goals were achieved, by focusing on an optics design and commissioning issues concerning especially high-intensity single-bunch acceleration to produce positron beams.

KEKB has been operated since December, 1998, to deliver BB pairs for a physics detector. In this paper,we describe the commissioning procedure of KEKB.

The KEKB accelerator control system including a control computer system, a timing distribution system, and a safety control system are described. KEKB accelerators were installed in the same tunnel where the TRISTAN accelerator was. There were some constraints due to the reused equipment. The control system is based on Experimental Physics and Industrial Control System (EPICS). In order to reduce the cost and labor for constructing the KEKB control system, as many CAMAC modules as possible are used again. The guiding principles of the KEKB control computer system are as follows: use EPICS as the controls environment, provide a two-language system for developing application programs, use VMEbus as frontend computers as a consequence of EPICS, use standard buses, such as CAMAC, GPIB, VXIbus, ARCNET, RS-232 as field buses and use ergonomic equipment for operators and scientists. On the software side, interpretive Python and SAD languages are used for coding application programs. The purpose of the radiation safety system is to protect personnel from radiation hazards. It consists of an access control system and a beam interlock system. The access control system protects people from strong radiation inside the accelerator tunnel due to an intense beam, by controlling access to the beamline area. On the other hand, the beam interlock system prevents people from radiation exposure by interlocking the beam operation. For the convenience of accelerator operation and access control, the region covered by the safety system is divided into three major access control areas: the KEKB area, the PF-AR area, and the beam-transport (BT) area. The KEKB control system required a new timing system to match a low longitudinal acceptance due to a low-alpha machine. This timing system is based on a frequency divider/multiply technique and a digital delay technique. The RF frequency of the KEKB rings and that of the injector Linac are locked with a common divisor frequency. The common divisor frequency determines the injection timing. The RF bucket selection system is also described. r 2002 Elsevier Science B.V. All rights reserved.

Solid state reaction at an interface between doped zirconia and ceria has been analyzed by X-ray diffraction and EDX. The solid state reaction between Y-doped ceria and Y-stabilized zirconia occurred on heating at 1300°C or higher temperatures to form a single cubic fluorite Y-doped ceria–zirconia phase. The reaction proceeded by preferential migration of the Ce component to the zirconia lattice. The reaction significantly lowered the electrical conductivity. The reaction between Sm-doped ceria and Y-stabilized zirconia, on the other hand, proceeded by migration of every component equally, i.e. preferential migration of a specific component was hardly observed.

About 90 stripline-type beam-position monitors have been newly installed in the KEKB injector linac. These monitors easily reinforce the handling of beam orbits and measure the amount of beam charge for single-bunch electron and positron beams which are injected to the KEKB rings. The design value of the beam-position resolution is expected to be less than 0.1 mm. A new data-acquisition system based on VME/OS-9 computers has been developed in order to control the monitors in real time. A hardware and software system which includes 18 front-end computers was tuned for the linac commissioning. This report describes the hardware and software system, the monitor calibration, and the beam-test results in detail.

Irradiation experiment on 20% cold worked P, Ti-modified 316 stainless steel with step-wise change of temperature was conducted in JOYO and Phenix. These were analyzed from the viewpoint of the influence of temperature change on microstructure change. With temperature decreasing, void formation is accelerated, compared with that of with constant temperature irradiation, and void formation is suppressed as temperature increases. From these results, it is suggested that the change of void formation behavior is caused by step-wise change of vacancy supersaturation associated with a change in irradiation temperature.

ODS ferritic steels (13Cr–0.5Ti–0.2Y2O3) were prepared by the mechanical alloying method followed by the hot extrusion and several heat treatments including recrystallization. ODS steels with different heat treatment and a ferritic/martensitic (F/M) steel for the reference were irradiated to 12 dpa at 670–770 K in HVEM. After recrystallization, the dislocation density decreased with increasing grain size, however, the oxide particles did not show any obvious change in the size and the number density. During the electron-irradiation the microstructure was relatively stable, i.e. oxide particles showed good stability and the dislocation density remained almost constant. A limited void formation was observed in the specimens, and the suppressive effect due to dislocations with high number density was confirmed. From these results, the behavior of microstructure and the limited void formation in ODS steels have been discussed.

Dispersion shifted fiber with a high nonlinearity coefficient (20.4 W-1 km-1) and low attenuation (0.51 dB/km) was successfully fabricated. 500 m of the fabricated fiber efficiently generated four-wave mixing, and nearly constant wavelength conversion efficiency over 20 nm was demonstrated.

Modified Type-316 and higher-nickel advanced austenitic steels were irradiated in the FFTF and JOYO fast reactors to a neutron dose as high as 210 dpa. At temperatures greater than 500°C, P-, Si-, and Ti-bearing cold-worked austenitic steels showed significant swelling suppression even after 150 dpa. The dominant mechanism is associated with formation of stable phosphide precipitated by addition of Ti and/or increased Si. In the lower-temperature regime, where the phosphide precipitate is not present, silicon acts to suppress swelling at contents of about 0.8 wt%. Only at this higher silicon level, increased amounts of nickel reduced the swelling. At 0.5 wt% silicon, the swelling was insensitive to the alloying elements, such as Ni, Ti and P. The effect of Si and Ni could be explained by their influence on void nucleation through effects on effective vacancy diffusion coefficient. Further improvement in swelling was expected by increasing the nickel and possibly the phosphorus contents of the advanced austenitics.

Oxide dispersion strengthened (ODS) ferritic steels were irradiated in a high voltage electron microscope (HVEM) to study their response to irradiation. Fe-13Cr with 0.25 wt% Y2O3 as dispersed particles and containing additions of either 0.45% Nb, 0.45% V and 0.67% Zr were irradiated at 673 and 723 K up to 15 dpa. The Y2O3 particles in all specimens were stable under these irradiation conditions. During irradiation, two types of dislocations were formed but observable voids were not formed. Furthermore, plate-like and granular-like precipitates formed in both the irradiated and nonirradiated regions.

Commercially developed 20% cold-worked P,Ti-modified 316 stainless steel claddings were irradiated as fuel pins in C-type irradiation rigs of JOYO under typical fast reactor conditions. The microstructural changes of irradiated claddings at temperatures around 500 C were extensively analyzed using transmission electron microscopy. Void formation is closely related with M{sub 6}C and G-phase precipitates and concomitant phosphide dissolution beyond the fast neutron fluence of 15 {times} 10{sup 26} n/m{sup 2}. Such phase instability in the fuel pin cladding during the fast reactor operation is caused by the radiation induced solute segregation, and it mainly interpreted in terms of varying system sink strength due to dislocation and precipitate changes.

A model of the servomechanism used for high-powered actuators in mechanical systems consists of a position feedback loop around the cascade connection of a memoryless saturation function with an integrator with a large time constant. The saturation function in the servomechanism has a linear high gain characteristics for a small input and so the equivalent time constant of the actuator servomechanism becomes small. As the input to the saturation function becomes larger than the small linear range for a drastic control demand, the output of the saturation function becomes constant irrespective of the input magnitude and the actuator response has a rate saturation determined by the large time constant of the integrator and so the time lag of the actuator response behind the demand results in the actual plant input much different from the demand and the plant may exhibit an undesirable behavior of the system. Therefore in this paper we consider a control method for a system with rate saturations in the actuator servomechanisms to keep stable by switching the controller gain according to the input magnitudes to the saturation functions so that the inputs to the saturation functions are controlled within the permissible maximum absolute values which are decided according to each level of LQ controller gain groups determined beforehand to ensure the local absolute stability of the total system whose conditions are expressed as a linear matrix inequalities optimization problem by introducing a Lure-Postnikov-type Lyapunov function. In a piecewise linear control the switching function selects a controller gain group by on-line monitoring the inputs to the saturation functions in the actuator servomechanisms. The effectiveness of the design method is illustrated with a practical example of dynamic positioning(DP) system.

The control engineers make adequate evaluations of the control unit with respect to the control performance, cost, reliability and so on by using the various verification measures for example, (1)computer simulation, (2)simulator apparatus and (3)actual equipment. In the initial evaluation it is efficient to use the measures of computer simulation and in the final evaluation it is necessary to use the measures of actual equipments. In the intermediate stage of evaluation the measures of simulator apparatus is an important factor which influences the evaluations of control performance and cost. In this paper the verification measures of simulator apparatus is considered which consists of the simulator apparatus for the controlled unit, and the actual equipments for the control unit and I/F unit and the design method of the simulator apparatus by use of control similarity principle is proposed in order to do the efficient design of simulator apparatus and the accurate evaluation of control performance of the total system. The method to derive the dimensionless parameters to establish the control similarity principle and the design method of simulator apparatus by use of the dimensionless parameters are revealed. As a practical example the design of a load simulator apparatus of the electric-motor driven injection molding machine is described.

We herein present a case who underwent vacuum-assisted wound closure (VAC) therapy for post-sternotomy mediastinitis. A 71-year-old female with chronic renal failure on dialysis underwent a graft replacement of the ascending aortic aorta for the treatment of an acute aortic dissection. After she was discharged from the hospital, a purulent discharge was noted to occur from the median sternal wound. The wound was therefore reopened and all sternal wires were removed. Thereafter, polyurethane foam which was shaped to fit the defect was placed within the cavity. The area was covered with adhesive drape and suction drainage was carried out at -100 mmHg. The polyurethane foam was replaced every few days. The wound was finally closed using a muscle flap at 49 days after surgery. VAC therapy is therefore considered to be a useful treatment modality for deep sternal wound infections.

The aim of this paper was to examine effectiveness of maintaining venous blood flow through dissected, but not harvested, grafts on prostaglandin I2 production and endothelial cell regeneration after implantation.Using 10 dogs, 8-cm-long bilateral jugular veins were dissected; 1 was harvested, and immersed in heparinized blood for 60 or 120 min. The other was left in situ with retained blood flow until harvest after 60 or 120 min. Two 1-cm-long specimens were obtained from these 4 graft types and subjected to PGI2 assay or silver nitrate staining for measurement of endothelial cell coverage area. The remaining 6-cm portions of the 120-min grafts were autogenously implanted into the abdominal aorta, retrieved after 7 days and assayed and measured.Comparisons between groups suggested beneficial effects of preserving venous blood flow until implantation on endothelial coverage and PGI2 production (p0.05).Venous blood flow through dissected vein grafts effectively helps preserve PGI2 production.

We have experienced a case of acute pulmonary embolism after lung cancer operation. The case was a 74-year-old male. He underwent left upper lobectomy due to squamous cell carcinoma. He fell into shock state suddenly on the 6th day postoperatively. We diagnosted acute pulmonary embolism, performed urgent embolectomy under percutaneous cardiopulmonary support (PCPS). Postoperative course was smooth, and he has returned to normal daily life. Urgent diagnosis and management are indispensable for acute pulmonary embolism after lung cancer operation from the aspect of residual among of pulmonary vascular bed.

A C-band (5712 MHz) rf system for a 500 GeV to 1 TeV e{sup +}e{sup -} linear collider is proposed. An accelerating gradient of 30 MV/m (including beam loading) is generated by 50 MW C-band klystrons in combination with an rf-compression system. The klystron and its power supply can be fabricated by conventional technology. The straightness tolerance for the accelerating structures is 30 {micro}m, which is also achievable with conventional fabrication processes. No critical new technology is required in a C-band system. Therefore a reliable system can be constructed at low cost with the minimum of R/D studies.

Tokamak magnetic fusion research has progressed to an advanced project, i.e., ITER (International Thermonuclear Experimental Reactor). Therefore, existing tokamaks must explore operational scenarios necessary for a high-performance plasma while simultaneously suppressing any disruptive instabilities. To implement this investigation, various advanced real-time controls using processed profile data and all available actuators should be tested in the experiments. To satisfy these requirements at the large tokamak JT-60, we are upgrading its original real-time control system completely. Two criteria for the new system configuration have been adopted: (i) The distributed processors for the measurements, actuators, and supervisory controllers (SVCs) am linked through a "reflective memory (RM)" network for fast, real-time communication. The profile data in the RM modules are also updated in real time. (ii) For efficient parallel and pipeline processes performed by multiple controllers, synchronization is provided from two sources: external hardware clocks and software counters in the RMS, which are updated by the SVCs. For a control function, the following simple and flexible method has been employed to perform various experimental proposals: New test control methods are first registered in the supervisory controllers. In accordance with the preprogrammed waveforms that indicate which control method to use, the SVCs select the correct control method in real time. The upgraded configuration of the JT-60 plasma control system and its effectiveness in seeking advanced operational scenarios applicable to ITER are discussed in detail.

We have measured beta functions using single kick closed orbit at KEKB. The measured beta functions were compared with the model lattice and gradient errors were extracted from the result in a beta beat. The gradient errors were also obtained by changing strength of steering magnets and measuring beam positions as the second method. The methods of the error estimation and preliminary results are reported.

A full-scale prototype C-band structure for the e/sup +/e/sup -/ linear collider has been built in which the dipole powers are damped to suppress the long-range transverse wakefield. To verify that the damping works as expected, the C-band structure was tested in the Accelerator Structure SETup (ASSET) at SLAC. This paper presents results of wakefield measurement with ASSET.

An absolute beam-charge measurement of single-bunch electron beams with a pulse width of 10 ps and short-pulsed electron beams with a pulse width of 1 ns was performed by the beam test for the KEKB injector linac using a Faraday cup. A wall-current monitor was directly recalibrated by the beam test with an error of /spl plusmn/2%.

Enhancement of re-endothelialization inhibits the progression of intimal hyperplasia. We investigated uptake of Lipoprostaglandin E(1) (LPGE(1)) by endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), and effects of the LPGE(1) on re-endothelialization of vein grafts.Primary cultured ECs and VSMCs were obtained from mongrel dogs, and incubated in mediums containing 0.5, 5, 50, and 250 ng/ml of DiI-LPGE(1) (DLPGE(1)); its uptake was visualized by the standard rhodamine excitation, and assessed by flow cytometry. In an implantation study, the bilateral femoral veins of 18 animals were implanted into the femoral artery, and the animals were given 0.2 microg/kg LPGE(1) for 2 weeks. Percentages of EC coverage area of the grafts (%EC) were measured by silver nitrate staining at intervals of 3, 7, and 21 days after implantation.VSMCs showed significant uptake in all of the mediums containing DLPGE(1), whereas the ECs revealed no fluorescence. In flow cytometry, histograms of VSMCs showed a specific notch of DLPGE(1), which increased the height according to the grade of the concentrations. The notch did not appear in the histograms of the ECs incubated with any concentration nor in the VSMCs incubated in control medium. These results suggested that LPGE(1) is predominantly absorbed by the VSMCs and exuded PGE(1) then acts on the VSMCs itself and on ECs alike. The %EC at 7 days was 58.4+/-1.9% in the DLPGE(1) group and 31.6+/-6.8% in controls (p0.05) showing a significant enhancing effect of DLPGE(1) on re-endothelialization of the vein grafts.In an animal model, daily administration of LPGE(1) resulted in significant enhancement of vein graft re-endothelialization. LPGE(1) was absorbed by the VSMCs, whereas the ECs showed no uptake, therefore the enhancement is probably due to a paracrine effect of VSMCs.

An automatic profile digital control system is presented which is based on a fundamental control system. The fundamental control system measures the film thickness at five points corresponding to five actuators, and controls the thickness at the location corresponding to the position of the central actuator at the specified value by using the five actuators. The basic idea is that in order to effect thickness control along the total width of the film, the fundamental control system will be applied to every thickness control point. It was designed by the state-prediction servo control theory, which solves such difficulties as a large amount of dead time and interaction between film thickness and actuators. Its practicality has been verified through testing. Tests were conducted for biaxially oriented polyester film by using a lip heater type die and for nonoriented polypropylene film by using a heat bolts type die. It was found that in this control system, the time to reach steady state was reduced and an accurate profile was obtained. >

A new type of RF compression scheme was proposed by the authors for the C-band RF system in the e/sup +/e/sup -/ linear collider in 1996. This scheme generates a flat pulse output using 3-cell coupled-cavity for the high-Q energy-storage. A cold model cavity was fabricated and tested to test the flat pulse generation. The input RF amplitude is modulated with a scheduled waveform in order to compensate the output power ripple associated with the coupled cavity resonances. The cold model generated a flat pulse compressed with gain G/sub p/ of 3.25.

To increase an electric field symmetry in a coupler cavity, a very simple structure of a two-iris coupler cavity was proposed by H. Matsumoto in 1994. The MAFIA 3D code is useful to simulate Slater's tuning curve method, which is used to determine the dimensions of the coupler cavity such as iris aperture and cavity diameter. It was find that MAFIA simulation results show that two-iris method will realize a good symmetrical electric field with a very simple structure as well as no difficulties for fabrication. This type of double feed coupler will be used for a Choke-mode type damped accelerating structure at C-band (5712 MHz) and an rf-gun for a linear collider.

Two types of ARES cavities were tested in the TRISTAN accumulation ring in KEK. In this paper, results relating to the fundamental mode in the accelerating cavity are reported. The status of the cavity, including the detuning frequency under beam loading and the output power from the coupling cavity damper, was measured at different beam current and with various bunch patterns. Its behavior agrees well with the calculation based on a coupled resonator model.

The ARES (Accelerator Resonantly coupled with an Energy Storage) cavity, which consists of three cells, has been developed for the KEK B-Factory, and two types of the ARES cavity have been constructed for the beam test. Both the types were installed in the KEK TRISTAN Accumulation Ring and beam-tested. The accelerating cell of the ARES has a HOM-damped structure to lower the impedance of HOMs in order to store a high current beam. The spectra excited by the beam (single bunch, 100 mA) were measured for both the cavities with scanning of the resonant frequency. Basically these results are consistent with those of calculations. The HOMs appear to be damped as expected. But the actual spectra for three cells are more complicated than only the accelerating cell. During this experiment, however, any beam instabilities due to the impedance of the cavities were not observed. This paper describes only the "ARES95"-one of the two types of the ARES.

The coaxial (WX120D) antenna damper has been developed for damping the parasitic 0 and /spl pi/ modes of the KEKB ARES cavity. It is installed in the coupling cavity of the ARES. The damper consists of a disk-type coaxial ceramic window and a cross stub angle. The damper has a broadband RF property in order to absorb the RF power of the parasitic modes. The cross angle is utilized for supplying the cooling water to the antenna. The damper was designed by using a computer simulation code without a cold model test. Finally the properties of the damper has been confirmed by the high-power and the beam test for the ARES cavity.

High power waveguide components at C-band (5712 MHz) frequencies have been developed for a main linac of a e/sup +/e/sup -/ linear collider in the range 300-500 GeV C.M. energy. 350 MW of maximum rf power has to be transmitted through the waveguide components. An EIA-WR187 (W: 44.55 mm, H: 22.15 mm and t: 4 mm) type sized conventional rectangular waveguide was chosen to reduce transmission loss to about the same order of magnitude as with an existing S-band waveguide. The thickness of the waveguide was fixed to make for easy machining, and assembling for the brazing process. A vacuum waveguide flange of unisex type with a simple shape was successfully developed. A Beth-hole type coaxial coupler, E- and H-corner, directional coupler, vacuum pumping port, 3-stub tuner, viewing port and phase shifter were successfully developed all with input VSWRs of less than the 1:1.1.

A completely new approach to measure beam emittance is examined. It is based on measuring the decay rate of the coherent betatron-oscillation through nonlinear filamentation caused by lattice nonlinearity. Experimental results, computer simulations and an analytic approach using differential algebra are presented. This method may provide useful tools in measuring emittance at high brightness light sources, high luminosity particle factories and damping rings for linear colliders where emittance and coupling are expected to be very small.

International audience; The beam experiments of Final Focus Test Beam (FFTB) started in September 1993 at SLAC, and have produced a 1.7 μm×75 nm spot of 46 GeV electron beam. A number of new techniques involving two nanometer spot-size monitors have been developed. Several beam diagnostic/tuning schemes are applied to achieve and maintain the small spot. This experiment opens the way toward the nanometer world for future linear colliders

In a large ring with extremely heavy beam loading, such as a B-factory, it is possible that the accelerating mode, itself, gives rise to a longitudinal coupled-bunch instability. In order to solve this problem, T. Shintake (1993) has proposed to attach a TE015-mode storage cavity to an accelerating cavity. It has subsequently been shown that the system can be put into practical use if a coupling cavity is added in between the two cavities. The three-cavity system, which is now referred to as an accelerator resonantly coupled with an energy storage (ARES), is under development for the KEKB.

The HOM absorber for the normal conducting RF cavity of the KEK B-factory (KEKB) was designed. Sixteen bullet-shape sintered SiC (silicon carbide) ceramics are used for HOM absorption. The HOM power to be handled will be about 10 kW per cavity, corresponding to about 1 kW per absorber. A prototype of SiC absorber was made to verify the performance as a HOM absorber in vacuum. The high power test was carried out successfully using a pulsed klystron (f=1296 MHz). The design of the HOM absorber and the results of the high power test are discussed.

In a bottle or can filling plant, the beverage should be chilled to the appropriate temperature. A plate heat exchanger is usually applied to do the cooling. We propose a new cooling method. The coolant is supplied from the refrigeration unit directly to the plate heat exchanger. The flow of it is controlled using a bypass valve. In order to improve the response and precision of the control, an observer and a regulator are introduced. Through simulations and an experiment at an experimental plant, we can conclude that our proposed method can be utilized in an actual filling plant.

The movable mask is a device that cuts off spent electrons/positrons near the beam orbit and reduces background of the detector. For the KEKB, sixteen movable masks had been installed for each ring. The originally designed masks, however, had severe troubles of heating, arcing and vacuum leaks. Several kinds of improved masks had been designed partially employing RF technologies in dealing with HOM and were installed to the ring step by step. The latest masks are working almost as expected now. Here the problems of movable masks so far are summarized and the structure of the latest movable masks and their status are presented.

Mitral valve aneurysm is a rare disease and in Japan, cases of perforation which is considered to be mainly caused by infectious endocarditis is usually only encountered through case reports. We experienced a case who received aortic valve replacement and mitral valve annuloplasty for combined valvular heart disease of aortic insufficiency and mitral insufficiency followed by mitral valve replacement for severe mitral valve regurgitation subsequent to perforation of the anterior mitral cusp, leading to recovery.

A 77-year-old female had acute myocardial infarction and ventricular septal perforation (VSP). An operation was performed 14 days after VSP. During cardiopulmonary bypass, a patch was sutured in place on the left side of the defect under a mild hypothermia with topical cardiac cooling procedure. In the postoperative period, mechanical ventilation was continued with use of pulmonary monitor (CP-100, BICORE). When the patient was weaned of mechanical ventilation, work of breathing increased (WOBp: 1.67 J.l-1) without the change of SaO2, PaO2, PaCO2 and the respiratory state. After extubation, the chest X-ray showed elevated right diaphragmatic level and a diagnosis of unilateral diaphragmatic paralysis was made. Oral intake was started two days after extubation. SpO2 decreased after oral intake, and it was significantly improved by taking a left lateral position. The symptoms disappeared 47 days after the operation. It should be noticed that the rise of endoceliac pressure in the patient who had a unilateral phrenic nerve palsy, affected the SpO2.

Electron irradiation experiments on Oxide Dispersion Strengthened steels (ODS ferritic steels) were performed using a high-voltage electron microscope (HVEM) with the aim of clarifying irradiation behavior. Four types of Fe-13 Cr base steels dispersed with Y2O3 particles were irradiated at 673–823 K up to 30 dpa. They were made by mechanical alloying with high-energy milling. Y2O3 particles in all specimens were stable under the irradiation conditions and no dissolution could be recognized. At first dislocation loops were formed, and subsequently complexes of defect clusters were formed on these loops. Voids developed except in steels which included either a high fraction of Y2O3 or Ti additions. It is suggested that the addition of Ti and/or Y2O3 particles to higher concentration are effective for the retardation of void formation or growth.

We report serial cerebral computed tomography (CT) and magnetic resonance imaging (MRI) in a case of hemolytic uremic syndrome (HUS) with the complication of the central nervous system due to Escherichia coli O157:H7. Although initial brain CT was normal, follow-up CT and MRI revealed lesions in the white matter and bilateral basal ganglia, representing brain edema and infarcts, respectively. Especially, lesions in the bilateral basal ganglia were very unique. Serial CT and MRI findings are useful to understand the mechanism of the complications of the central nervous system associated with HUS.