Some Consequences of Thermosolutal Convection: The Grain Structure of Castings

The essential principles of thermosolutal convection are outlined, and how convection provides a transport mechanism between the mushy region of a casting and the open bulk liquid is illustrated. The convective flow patterns which develop assist in heat exchange and macroscopic solute segregation during solidification; they also provide a mechanism for the transport of dendritic fragments from the mushy region into the bulk liquid. Surviving fragments become nuclei for equiaxed grains and so lead to blocking of the parental columnar, dendritic growth front from which they originated. The physical steps in such a sequence are considered and some experimental data are provided to support the argument

Acute leukaemia in patients treated for Hodgkin's disease

Fourteen acute non-lymphoid leukaemias (ANLL) were identified among 947 consecutive patients with Hodgkin's disease (HD) treated in five collaborating centres in Italy between January 1969 and December 1979. Leukaemia developed 12-118 months after the diagnosis of HD and was always preceded by a pre-leukaemic phase. The karyotype of the leukaemic cells was studied in nine of the 14 patients and was abnormal in seven cases. Bone marrow agar cultures were performed in five of the 14 patients and were abnormal in every case. The actuarial risk of developing ANLL at 10 years was 6.2% for combined therapy, 4.8% for salvage therapy and 2.2% for chemotherapy alone. No case of ANLL was documented among 136 patients treated with radiotherapy alone. One patient developed acute promyelocytic leukaemia following treatment with ABVD and radiotherapy. Both univariate and multivariate analyses seem to demonstrate that the induction therapy modality is a significant variable in development of secondary acute leukaemia. The recognition of a significant risk of ANLL in patients treated for HD should create changes in treatment policy