The New 5 MeV Electrostatic Ion Accelerator at the Central Research Institute for Physics, Budapest, Hungary

The new 5 MeV electrostatic ion accelerator, projected, built, and tested at the Central Research Institute for Physics in Budapest, with some necessary aid from Hungarian industry /pressure vessel etc./ is described. The accelerator's main specifications are detailed and an account is given of the experiences with glass and porcelain accelerating tubes. By careful design, the intensity of radiation in the range of 4-5 MV has been reduced by 2-3 orders of magnitude. Without an ion beam there was only 3-5 times the intensity of the natural radiation background /i.e. less than 0.5 mR/h/ on the outer surface of the generator vessel when operated at 4-5 MV. The radiation level with the accelerated ion beam is accordingly also very low. During a 7-month period in 1970 the generator ran for 3,250 hours of measurements in nuclear physics.     

Microstructure evolution in refill friction stir spot weld of a dissimilar Al–Mg alloy to Zn-coated steel

In the present study, dissimilar welds of an Al–Mg–Mn alloy and a Zn-coated high-strength low-alloy steel were welded by refill friction stir spot welding. The maximum shear load recorded was approximately 7.8?kN, obtained from the weld produced with a 1600?rev min^?1 tool rotational speed. Microstructural analyses showed the formation of a solid–liquid structure of an Al solid solution in Mg–Al-rich Zn liquid, which gives rise to the formation of Zn-rich Al region and microfissuring in some regions during welding. Exposure of steel surface to Mg–Al-rich Zn liquid led to the formation of Fe₂Al₅ and Fe₄Al₁₃ intermetallics. The presence of defective Zn-rich Al regions and Fe–Al intermetallics at the faying surface affects the weld strength.     

Influence of micro-blasting on the microstructure and residual stresses of CVD κ-Al2O3 coatings

Cemented carbides coated with CVD multilayers are commonly used in metal cutting turning and milling operations. For many applications, a micro-blasting finishing procedure based on an impact treatment of the surfaces is carried out in order to smooth the coated surface and reduce sharp cutting edges. In this work, micro-blasting with corundum in aqueous solution at pressures between 0.05 and 0.3 MPa was applied to CVD TiN/Ti(C,N)/κ-Al₂O₃ multilayer coatings deposited onto cemented carbides in order to investigate its influence on the micro-topography, microstructure and residual stresses. The results showed that the micro-blasting reduces the surface roughness and affects the coating thickness. TEM investigations revealed no significant changes on the microstructure of the κ-Al₂O₃ top layer. Synchrotron X-ray investigations showed that the residual stress state of the as-deposited κ-Al₂O₃ top layer is not affected by the micro-blasting treatment under the conditions investigated.     

Instability of malondialdehyde in the presence of H2O2: Implications for the thiobarbituric acid test

The content of thiobarbituric acid-reactive material (primarily malondialdehyde) is frequently used to estimate the extent of lipid peroxide formation. How-ever, malondialdehyde is unstable in the presence of millimolar concentrations of hydrogen peroxide. This observation considerably limits the applicability of the thiobarbituric acid test, as hydrogen peroxide is known to be formed in a number of lipid peroxidation-promoting systems. The instability of malondialdehyde in the presence of hydrogen peroxide seems to account for the inconsistent outcomes in studies relating the manipulations of intermediate H₂O₂ levels to the initiation of lipid peroxidation.     

Export of importin alpha from the nucleus is mediated by a specific nuclear transport factor

NLS proteins are transported into the nucleus by the importin alpha/beta heterodimer. Importin alpha binds the NLS, while importin beta mediates translocation through the nuclear pore complex. After translocation, RanGTP, whose predicted concentration is high in the nucleus and low in the cytoplasm, binds importin beta and displaces importin alpha. Importin alpha must then be returned to the cytoplasm, leaving the NLS protein behind. Here, we report that the previously identified CAS protein mediates importin alpha re-export. CAS binds strongly to importin alpha only in the presence of RanGTP, forming an importin alpha/CAS/RanGTP complex. Importin alpha is released from this complex in the cytoplasm by the combined action of RanBP1 and RanGAP1. CAS binds preferentially to NLS-free importin alpha, explaining why import substrates stay in the nucleus.     

Pyrographit – Eigenschaften und anwendung

Pyrolytic Graphite – Properties and Application The carbon material known as pyrolytic graphite is remarkable for its exceptional properties which make it capable of being used in fields and processes in which high thermal, chemical and electrical stress is required. Its technical importances has increased in recent years. A report is given of the preparation of pyrolytic graphite and also of its important application properties, and the most important fields of application are touched on.     

Microstructural evolution of a Ni-based superalloy (617B) at 700 °C studied by electron microscopy and atom probe tomography

We report on the microstructural evolution of a polycrystalline Ni-based superalloy (Alloy 617B) for power plant applications at a service temperature of 700 °C. The formation of secondary M₂₃C₆-carbides close to grain boundaries (GBs) and around primary Ti(C,N) particles is observed upon annealing at 700 °C, where γ′ is found to nucleate heterogeneously at M₂₃C₆ carbides. Using atom probe tomography, elemental partitioning to the phases and composition profiles across phase and grain boundaries are determined. Enrichments of B at γ/M₂₃C₆ and γ′/M₂₃C₆ interfaces as well as at grain boundaries are detected, while no B enrichment is found at γ/γ′ interfaces. It is suggested that segregation of B in conjunction with γ′ formation stabilizes a network of secondary M₂₃C₆ precipitates near GBs and thus increases the creep rupture life of Alloy 617B. Calculations of the equilibrium phase compositions by Thermo-Calc confirm the chemical compositions measured by atom probe tomography.     

Effect of Shot-peening on the Oxidation Behaviour of Boiler Steels

The presence of short diffusion paths is very important for rapid diffusion processes which are involved in forming protective oxide layers against high temperature corrosion, e.g. on boiler steels. Rapid diffusion paths can be produced by applying cold work such as shot-peening to the surface of the boiler steels prior to oxidation. The effect of shot-peening on oxidation behaviour was tested experimentally on 12 wt% Cr martensitic steel and 18 wt% Cr austenitic steel. Isothermal oxidation tests were performed at 700 and 750 °C. The surface treatment proved to be very effective in improving oxidation protection at 700 °C. Shot-peening the surface prior to the oxidation has an influential effect in changing the diffusion mechanisms of the elements involved in oxidation and changes the oxidation kinetics substantially at the applied conditions in this study.