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Background: We retrospectively reviewed our experience in combined liver-kidney (L-KT) and heart-kidney (H-KT) transplantations. Patients and Methods: Between January 1997 and April 2007, we performed 25 L-KT and 5 H-KT. Patient mean age was 51 ± 8 years in L-KT and 43 ± 11 years in H-KT. The main cause of liver failure was chronic viral hepatitis (14 cases). Etiology of heart failure was dilated cardiomyopathy and hypertrophic cardiomyopathy (4 and 1 patients, respectively). The main causes of renal failure in L-KT were chronic glomerulonephritis (n = 8) and polycystic disease (n = 7). Etiology of renal failure in H-KT was interstitial nephropathy (n = 2), vascular nephropathy (n = 2), and chronic glomerulonephritis (n = 1). Results: Mean follow-up was 32 ± 26 months in L-KT and 24 ± 17 months in H-KT. Immunosuppression was cyclosporine-based (n = 4) or tacrolimus-based (n = 21) in L-KT and cyclosporine-based in H-KT. Acute rejection rate was 8% for both liver and kidney in L-KT; 80% (mild) for heart and 40% for kidney in H-KT. In the L-KT group, there was no primary graft nonfunction (PGNF). Two patients experienced liver delayed graft function (DGF); 1 patient required postoperative dialysis. One-year graft and patient survivals were both 84% and overall graft and patient survival was 76%. In the H-KT group, 3 patients needed postoperative dialysis and 1 required a cardiac assistance device for 48 hours; overall graft and patient survival was 100% with good cardiac and renal functions. Conclusion: Our experience confirmed that H-KT and L-KT are safe procedures, offering good long-term results.

Brazed molybdenum and tantalum alloy honeycomb structures offer good potential for structural and heat shield applications in the 2500 - 3500F range. However, molybdenum is seriously embrittled at braze temperatures above approximately 2500F. Tantalum alloys are not embrittled by high braze temperatures, but there are serious production problems associated with braze temperatures above 3000F. The purpose of this program is to develop molybdenum and tantalum braze systems which braze at relatively low temperatures, but develop high remelt temperatures. Some attention is also being directed to the development of braze alloys for tantalum that braze several hundred degrees above the expected service temperature. Most of the effort will be based on the TZM molybdenum alloy and the Ta-10W alloy. Some work will be performed using the Ta-8W-2Hf and Ta-30Cb-7,5V alloys.

The elevated temperature creep properties of Type 301 EFH Stainless Steel and two titanium alloys, Ti-5Al-2.5Sn and Ti-13V-11Cr-3Al were evaluated at 600F and 900F under steady state, cyclic load and cyclic temperature creep exposure. In addition the effects of creep strain on subsequent room temperature tensile properties were studied. On the basis of density compensated tensile and creep strength, the Ti-13V-11Cr-3Al alloy (B120VCA) was found to be the best alloy for use from room temperature to about 800F. Above 800F the Ti-5Al-2.5Sn alloy (A110AT) is the better material. Between 400F and 800F the 301 EFH and Ti-5Al-2.5Sn alloys are quite competitive when compared on a density compensated basis. On an over-all basis the stainless steel appears slightly superior in this temperature range. Below 400F the Ti-5Al-2.5Sn alloy may be the better choice. The effects of cyclic loading and cyclic temperature creep exposure compared to steady state creep exposure on the over-all creep strain and creep rate was quite small in general. Creep damage, i.e., the decrease in room temperature tensile properties due to prior exposure to stress at elevated temperatures, was quite small also except for elongation. In general, changes in F sub tu and F sub ty did not exceed 6 percent. Decreases in ductivity due to creep damage were quite large in some cases. For example, the elongation of the Ti-5Al-2.5Sn alloy decreased from 22 percent to about 7 percent when stressed for periods of 24 hours at 900F. Creep damage produced by cycle creep conditions was similar to that found under steady state creep conditions. (Author)

Brazed molybdenum and tantalum alloy honeycomb structures offer good potential for structural and heat shield applications in the 2500-3500 F range. However, molybdenum is seriously embrittled at braze temperatures above approximately 2500F. Tantalum alloys are not embrittled by high braze temperatures, but there are serious production problems associated with braze temperatures above 3200F. The purpose of this program was to develop molybdenum and tantalum braze systems which braze at relatively low temperatures, but develop high remelt and service temperatures. Some attention was also directed to the development of braze alloys for tantalum that braze several hundred degrees above the expected service temperature. Most of the effort was based on TZM molybdenum alloy and Ta-10W alloy. Some work was performed using Ta-8W-2Hf and Ta-30Cb-7. 5V., See also Part 2, AD-470 280.