100,435 research outputs found
Thermochemistry of selected R-T-Al (R= rare earth, T= Ni, Pd) alloys
No full textThe synthesis, structure and properties of R-T-Al (R= rare earth, T= Ni and Pd) alloys are of growing interest for fundamental aspects as well as for potential applications in various technological fields, because of their typical properties. Selected R–T–Al ternary systems are considered in our laboratory in order to study different thermodynamic properties; in particular, results about the standard enthalpy of formation at 300K recently obtained for the RNiAl, RNi2Al3 and RPdAl will be presented. Experimental investigations have been performed by using direct calorimetry and different analytical techniques to check the state and composition of the samples: X−ray Powder Diffraction (XRD), Light Optical Microscopy (LOM), Scanning Electron Microscopy (SEM) and Electron Probe Micro-Analysis (EPMA). Results obtained for RNiAl, RNi2Al3 and RPdAl are discussed and compared also with those available for the binary compounds of the R-Ni and R-Pd systems
Risultati del trattamento endoscopico e chirurgico nei pazienti affetti da ittero ostruttivo da litiasi residua e/o recidiva del coledoco.
No full textInterfacial reactions in the Sb-Sn/(Cu, Ni) systems: Wetting experiments
No full textInterfacial reactions in the SbeSn/Cu and SbeSn/Ni systems have been investigated by means of wetting experiments. The wetting behaviour of two lead-free alloys, namely, Sb2.5Sn97.5 and Sb14.5Sn85.5 (at.%), in contact with Cu and Ni-substrates has been studied in view of possible applications as high-temperature solders in the electronics industry. The contact angle measurements on Cu and Ni plates were performed by using a sessile drop apparatus. The solder/substrate interface was characterised by the SEM-EDS
analyses
Au-Ge based alloys for novel High-T Lead Free Solder materials - Fundamentals and applications(
No full textLow melting Au based alloys offer a combination of high corrosion and creep resistance as well as good electrical and thermal conductivity, and they support the capability for fluxless soldering. Despite their high price, Au alloys are of special interest for high temperature solder applications where these characteristics are essential, e.g. special MEMS devices, sensors exposed to aggressive media, biomedical applications or in space technology. The alloying system Au-Ge is characterized by a deep eutectic point with a melting temperature of 360°C, but information on the use of eutectic Au-Ge as solder material is very limited. In this work, the results of a group project within the European COST Action MP0602 "High Temperature Lead Free Solders" on the feasibility of Au-Ge based alloys as high-temperature lead free solder will be summarized. Beside the thermodynamic assessment of a number of important alloying systems (Cu-Ge, Ge-Ni, Au-Ge-Sb, Au-Ge-Si, Au-Ge-Sn) wetting and soldering tests using eutectic Au-Ge alloy and Cu and Ni substrates were performed. Sound joints with a high strength could be produced
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
Bismuth activity in lead-free solder Bi-In-Sn alloys
No full textThe thermodynamics of Bi-In-Sn lead-free solder alloys has been studied by two different experimental techniques: torsion-effusion and differential scanning calorimetry. The results show that this ternary system at fixed Bi composition, X-Bi = 0.20, and 565 K behaves as a non-ideal system with exothermic Delta(mix) H-T(0) passing through a minimum at X-In = 0.58 and X-sn = 0.22. In the whole range of the quantity X-Sn/(X-Sn + X-In) T and at 1050 K the average value of the bismuth activity is 0.14 +/- 0.02 which implies an average activity coefficient of Bi equal to 0.70 +/- 0.01. The Bi activity in ternary alloys at 1000 K with variable X-Bi and fixed ratio rho = X-Sn/X-In = 0.85 has been measured. The excess integral free energy change for the mixing, Delta(mix) G(T)(0) (xs), has also been evaluated by making use of both the torsion-effusion experimental and literature data T for Bi-Sn and Bi-In binary systems. Under these conditions, the ternary system is not a regular solution and the entropy contribution to the free energy of mixing is dominating the Gibbs energy. (C) 2006 Elsevier Ltd. All rights reserved
The effect of Sb addition on Sn-based alloys for high-T lead-free solders: an investigation of the Ag-Sb-Sn system
No full textHandwritten biographical information on Paulina T. McClung Merritt
No full textA handwritten biography of Paulina T. McClung Merritt by an unknown author, 1892.
Heterogeneous and tissue-specific regulation of effector T cell responses by IFN-gamma during Plasmodium berghei ANKA infection.
No full textIFN-γ and T cells are both required for the development of experimental cerebral malaria during Plasmodium berghei ANKA infection. Surprisingly, however, the role of IFN-γ in shaping the effector CD4(+) and CD8(+) T cell response during this infection has not been examined in detail. To address this, we have compared the effector T cell responses in wild-type and IFN-γ(-/-) mice during P. berghei ANKA infection. The expansion of splenic CD4(+) and CD8(+) T cells during P. berghei ANKA infection was unaffected by the absence of IFN-γ, but the contraction phase of the T cell response was significantly attenuated. Splenic T cell activation and effector function were essentially normal in IFN-γ(-/-) mice; however, the migration to, and accumulation of, effector CD4(+) and CD8(+) T cells in the lung, liver, and brain was altered in IFN-γ(-/-) mice. Interestingly, activation and accumulation of T cells in various nonlymphoid organs was differently affected by lack of IFN-γ, suggesting that IFN-γ influences T cell effector function to varying levels in different anatomical locations. Importantly, control of splenic T cell numbers during P. berghei ANKA infection depended on active IFN-γ-dependent environmental signals--leading to T cell apoptosis--rather than upon intrinsic alterations in T cell programming. To our knowledge, this is the first study to fully investigate the role of IFN-γ in modulating T cell function during P. berghei ANKA infection and reveals that IFN-γ is required for efficient contraction of the pool of activated T cells
Short and long term results after endoscopic sphincterotomy for retained or recurrent common bile duct stones.
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