Feedstock aids microPIM parts production: Tiny cogs test the imagination of powder professionals as small parts demand ever-finer materials…

With commercially available PIM feedstock reportedly unable to fulfill the requirements for the microPIM components under investigation, researchers at the Institute for Materials Research III (IMR) in Karlsruhe, Germany, have developed new binder systems for feedstock based on both nanoceramic and ultrafine metallic powders. In the case of ceramics (zirconia) the powders can be as fine as 300 nm, and for metals in the 3μm-5μm particle size range. The powders are used to develop PIM gearwheels (Figure 1) and other components for a demonstrator micro annular gear pump design (Figure 2); however, the technology is also said to be applicable to micro gears used in watches.     

Fatigue crack initiation and propagation of binder-treated powder metallurgy steels

Many of the targeted applications for powder-metallurgy materials, particularly in the automotive industry, undergo cyclic loading. It is, therefore, essential to examine the fatigue mechanisms in these materials. The mechanisms of fatigue-crack initiation and propagation in ferrous powder-metallurgy components have been investigated. The fatigue mechanisms are controlled primarily by the inherent porosity present in these materials. Since most, if not all, fatigue cracks initiate and propagate at the specimen surface, surface replication was used to determine the role of surface porosity in relation to fatigue behavior. Surface replication provides detailed information on both initiation sites and on the propagation path of fatigue cracks. The effect of microstructural features such as pore size and pore shape, as well as the heterogeneous microstructure on crack deflection, was examined and is discussed. Fracture surfaces were examined to elucidate a mechanistic understanding of fatigue processes in these materials.     

The murine Tcl1 oncogene: embryonic and lymphoid cell expression

In human leukemias and lymphomas nonrandom chromosomal rearrangements cause changes in cell growth and/or survival in such a way as to promote malignancy. The detailed study of the biochemical and genetic pathways altered in human cancer requires the identification or development of models to allow the study and manipulation of cancer gene function. Recently, the breakpoint gene TCL1, involved in chromosome translocations observed mostly in mature T-cell proliferations and chronic lymphocytic leukemias (CLL), was isolated and characterized, and showed to be part of a new gene family of proteins involved in these tumors. The murine Tcl1 gene, is similar in sequence to the murine and human MTCP1 gene also involved in T cell leukemias. The murine Tcl1 gene was shown to reside on mouse chromosome 12 in a region syntenic to human chromosome 14. Furthermore, we show that the murine Tcl1 gene is expressed early in mouse embryonic development and demonstrates expression in fetal hematopoietic organs as well as in immature T and B cells. Characterization of the murine Tcl1 gene will help in developing a mouse model of CLL and would provide the best opportunity to study and decipher the role of TCL1 in malignant transformation.     

Consent to treatment by minors attending accident and emergency departments: guidelines

The absolute right to refuse medical treatment, even if the reasons are irrational, is confined to competent adults. Children under 16 years can give legal consent to treatment in the absence of consent from those with parental responsibility. Children under 18 years do not, however, have an absolute right to consent, or refuse to consent, to treatment. The views of children assume increasing importance with age and maturity. Accident and emergency medical and nursing staff may face difficult decisions when children, or those with parental responsibility, refuse to consent to medical treatment. This paper presents guidelines designed to guide the decision making process in immediately or potentially life threatening conditions and in non-life-threatening conditions.