Influence of specimen orientation and loading history on s.c.c. in an aluminium alloy

A contoured double cantilever beam specimen developed for linear elastic fracture mechanics (LEFM) studies was used in a stress corrosion cracking study of the Al Alloy RR 58. Subcritical s.c.c. tests were performed, in which a 3.5% NaCl solution, at 21°C, was drip-fed on to the crack surfaces with the crack propagating in the S-L orientation.Initial results showed three distinct regions of crack propagation when plotted as crack growth rate, da/dt, as a function of stress intensity K. Additional comparative tests showed that a faster-crack growth rate was obtained when the specimens had their longitudinal axis positioned vertically rather than horizontally, due to the better access of the corrodent to the crack tip. The present results were compared with data obtained under similar conditions on a range of 2000 series A1 alloys.The influence of loading history on the crack growth rate was studied. When the level of K was increased a temporary increase in crack growth rate was observed. Tests under decreasing K values showed an increase of the incubation time with decreasing values of the stress intensity. This latter effect is discussed in terms of the plastic zone size and an analytical solution suggested.     

High magnetic field effect on texture and grain growth of GNO silicon steel

Magnetic annealing at 800 °C for 3, 15 and 30 minutes was conducted to evaluate the effect of a 17T magnetic field on the microstructure formation of cold rolled Fe‐0.75 %Si samples. According to texture measurements magnetic field did not seem to significantly affect the development of grains with Goss orientation, however it showed to affect the nucleation and growth process of {001}, {110} and {111} grains by increasing the volume fraction of the η fiber and by decreasing the fraction of the alfa and gamma fibers. ESEM/OIM and optical microscope results indicate that although magnetic field may retard nucleation it also promotes grain boundary displacement and for longer annealing times the retardation effect is compensated by the magnetic filed driving force.     

Mitral valve insufficiency caused by tendinous cord rupture and mitral valve aneurysm. Significance of the echocardiographic study

Mitral valve aneurysm is a rare complication that may occur in a myxomatous valve. We report the case of a 73 year old male patient with severe mitral regurgitation and heart failure-class IV NYHA. Echocardiography showed perforation of an aneurysm of the anterior leaflet of the mitral valve associated with rupture of tendinous cords of the posterior mitral leaflet. Diagnosis was made by transthoracic echocardiography and confirmed by transesophageal echocardiography. The patient was urgently operated with success and a mitral valve prosthesis was implanted.     

Production performance and milk composition of dairy cows fed whole or ground flaxseed with or without monensin

Eight multiparous Holstein cows averaging 570 ± 43 kg of body weight and 60 ± 20 d in milk were used in a double Latin square design with four 21-d experimental periods to determine the effects of feeding ground or whole flaxseed with or without monensin supplementation (0.02% on a dry matter basis) on milk production and composition, feed intake, digestion, blood composition, and fatty acid profile of milk. Intake of dry matter was similar among treatments. Cows fed whole flaxseed had higher digestibility of acid detergent fiber but lower digestibilities of crude protein and ether extract than those fed ground flaxseed; monensin had no effect on digestibility. Milk production tended to be greater for cows fed ground flaxseed (22.8 kg/d) compared with those fed whole flaxseed (21.4 kg/d). Processing of flaxseed had no effect on 4% fat-corrected milk yield and milk protein and lactose concentrations. Monensin supplementation had no effect on milk production but decreased 4% fat-corrected milk yield as a result of a decrease in milk fat concentration. Feeding ground compared with whole flaxseed decreased concentrations of 16:0, 17:0, and cis6-20:4 and increased those of cis6-18:2, cis9, trans11-18:2, and cis3-18:3 in milk fat. As a result, there was a decrease in concentrations of medium-chain and saturated fatty acids and a trend for higher concentrations of long-chain fatty acids in milk fat when feeding ground compared with whole flaxseed. Monensin supplementation increased concentrations of cis9 and trans11-18:2 and decreased concentrations of saturated fatty acids in milk fat. There was an interaction between flaxseed processing and monensin supplementation, with higher milk fat concentration of trans11-18:1 for cows fed ground flaxseed with monensin than for those fed the other diets. Flaxseed processing and monensin supplementation successfully modified the fatty acid composition of milk fat that might favor nutritional value for consumers.     

Structural and physical properties of the U9Fe7Ge24 uranium germanide

A new ternary compound, U₉Fe₇Ge₂₄, was synthesized by arc-melting the elements, followed by annealing at 900 °C. This compound was characterized by single crystal and powder X-ray diffraction, magnetization, specific heat and electrical transport measurements. It crystallizes in an original tetragonal structure type (space group I4/mmm), with lattice parameters a = 12.3789(2) Å and c = 18.2881(3) Å. Three uranium, eighth germanium, and three iron crystallographic sites exist in this structure, with the atoms making a stacking of infinite chains along the a and b axis. From their interatomic distances strong interactions between the uranium and germanium atoms can be predicted. The magnetic and specific heat measurements down to 2 K do not show any magnetic transition. The Curie–Weiss behaviour with a negative paramagnetic Curie temperature θp = ?94 K and reduced effective magnetic moment of μ_eff = 2.13 μ_B/U indicate that the compound is rather far from onset of magnetism, presumably due to a strong hybridisation of the 5f and ligand states. The electrical transport measurements show a metallic behaviour.     

An in vitro and in vivo investigation of the biological behavior of a ferrimagnetic cement for highly focalized thermotherapy

The cancer treatment by local hyperthermia, using a high frequency electromagnetic field is an extensively studied subject. For this propose it was developed a ferrimagnetic cement (FC) to be injected directly into the tumor. In this study it was determined the FC injectability, its capability to generate heat when placed within a magnetic field and its interaction with a modified simulated body fluid using SEM/EDS and XRD. The FC biological response was assessed by the intramuscular implantation in rats and histological analysis of the surrounding tissues. The results suggest that FC can be injected directly into the tumor, its temperature can be increased when exposed to a magnetic field and the surface of the immersed samples quickly becomes coated with precipitate denoting its ionic change with the surrounding medium. The histological analysis revealed a transient local inflammatory reaction, similar to the control material, only slightly more abundant during the first weeks, with a gradual decrease over the implantation time. Based on these results, we concluded that FC might be useful for highly focalized thermotherapy, with a good potential for clinical use.     

FATIGUE ANALYSIS AND PREDICTION IN FILLET WELDED JOINTS IN THE LOW THICKNESS RANGE

Abstract— The paper reports the results of a comprehensive research project concerning fatigue life prediction in fillet welded joints. Geometry variables such as main plate thickness, radius of curvature at the weld toe and leg to leg distance were analysed in detail. Fatigue life computations were carried out for semi-elliptical cracks using appropriate FE techniques. The range of results covered several types of welded joints loaded in tension and in bending. A comparison of results was made using two methods of stress intensity determination. Experimental data was also obtained and that included measurements of weld toe radius, monitoring of crack shape and S-N curves. Correlation of results with the theoretical predictions gave generally good agreement. A set of fatigue design curves for fillet welded joints is proposed and in these the designer can introduce the geometry of the weldment.