Low-temperature tracer diffusion of Mo, V and W in Fe-Cr ferritic alloys

Diffusivities of radioiostopes ⁹⁹Mo, ⁴⁸V and ¹⁸¹W in ferritic alloys Fe-Cr, Fe-Cr-C and in two commercial 8% Cr ferritic steels were measured using the serial sectioning method in a temperature interval from 743 K to 1123 K. The coefficients of volume diffusion exhibit the magnetic anomaly of diffusion that was described by jönsson's theoretical model, the measured diffusivities along high diffusivity paths were discussed on the basis of interaction of diffusant with carbidic particles.     

CMSX-3单晶合金的微观组织研究

镍基单晶高温合金是重要的航空燃气轮机涡轮叶片材料。本文利用光学金相、SEMTEM等分析手段研究了采用定向凝固造晶法制造的CMSX－3单晶合金的微观组织。对其铸态组织与γ＇形态做了描述与分析。     

Reduced turnover of the D1 polypeptide and photoactivation of electron transfer in novel herbicide resistant mutants of Synechocystis sp. PCC 6803

Two missense mutants, A263P and S264P, and a deletion mutant des-Ala263, Ser264, have been constructed in the D1 protein of the cyanobacterium Synechocystis sp PCC 6803. All were expected to induce a significant conformational change in the QB-binding region of photosystem II (PSII). Although the des-Ala263, Ser264-D1 mutant accumulated some D1 protein in the thylakoid membrane it was unable to grow photoautotrophically or evolve oxygen. Thermoluminescence and chlorophyll fluorescence studies confirmed that this deletion mutant did not show any functional PSII activity. In contrast, [S264P]D1 was able to grow photoautotrophically and give light-saturated rates of oxygen evolution at 60% of the rate of the wild-type control strain, TC31. The A263P missense mutant was also able to evolve oxygen at 50% of TC31 rates although it did not readily grow photoautotrophically. Thermoluminescence, flash oxygen yield and chlorophyll fluorescence measurements indicated that in both missense mutants electron transfer from QA to QB was significantly impaired in dark adapted cells. However, QA to QB electron transfer could be photoactivated in the mutants by background illumination. Both the A263P and S264P mutants also showed an increase in resistance to the s-triazine family of herbicides although this feature did not hold for the phenolic herbicide, ioxynil. Of particular interest was that the two missense mutants, especially S264P, possessed a slower rate of turnover of the D1 protein compared with TC31 and in vivo contained detectable levels of a 41-kDa adduct consisting of D1 and the alpha subunit of cytochrome b559. When protein synthesis was blocked by the addition of lincomycin, D1 degradation was again slower in S264P than TC31. The results are discussed in terms of structural changes in the QB-binding region which affect herbicide and plastoquinone binding and perturb the normal regulatory factors that control the degradation of the D1 protein and its synchronisation with the synthesis of a replacement D1 protein.     

Practical prediction of cyclic humidity effect in creep and shrinkage of concrete

The previously published BP Model for prediction of concrete creep and shrinkage is generalized to cover the increase of creep caused by the cyclic component of environmental relative humidity. A simple formula, which is partly empirical, partly based on the diffusion theory, is proposed and is calibrated by comparisons with test data from the literature.     

Ormond's disease

Three cases of Ormond's disease (syndrome) are described, and the aetiopathogenesis, clinical picture and diagnostics of the disease are dealt with in this report. Besides, the traditional therapy and the new therapeutic possibilities are discussed. For a disease of low incidence and assumed autoimmune origin malignancy cannot be excluded. Therefore, surgical exploration and histological verification are indispensable interventions in every case of Ormond's disease. In two of the present cases, steroid was administered in defence of percutaneous nephrostomy. In two cases, the recently recommended anti-oestrogen therapy was successful. Stagnation, or even regression, of the process followed. The authors are sure that they were the first in Hungary to administer anti-oestrogen to patients suffering from IFR.     

Thermal cycles effects on interlaminar shear strength (ILSS) and impact behaviour of carbon/PEI composites

In this paper, the effect of thermal cycle on the interlaminate shear strength (ILSS) and impact behaviour of unidirectional carbon fibre reinforced polyetherimide (PEI) matrix composites were studied. Samples were subjected to 100 thermal cycles (by immersing from boiling water (100°C) to ice water (0°C). The effects of thermal cycles were characterized by short beam shear and instrumented impact testers. Also Fractographic investigations were done using a scanning electron microscope (SEM). It is observed that the plastic deformations at the fibre/matrix and interlaminar interface as well as residual stresses lower the ILSS and flexural modulus of the material proportional with the number of thermal cycles. Up to the first 20 thermal cycles the material shows a brittle fracture with lower fracture energy, but after the 20th thermal cycles it is possible to observe that the material fractures with higher fracture energy at longer fracture time. A remarkable difference in the fracture morphology between the thermal cycled and un-treated materials has been observed. It is found that thermal cycles strictly affect the fracture morphology.