Influence of multi-cycle loading on the structure and mechanics of marine mussel plaques.

The proteinaceous byssal plaque-thread structures created by marine mussels exhibit extraordinary load-bearing capability. Although the nanoscopic protein interactions that support interfacial adhesion are increasingly understood, major mechanistic questions about how mussel plaques maintain toughness on supramolecular scales remain unanswered. This study explores the mechanical properties of whole mussel plaques subjected to repetitive loading cycles, with varied recovery times. Mechanical measurements were complemented with scanning electron microscopy to investigate strain-induced structural changes after yield. Multicyclic loading of plaques decreases their low-strain stiffness and introduces irreversible, strain-dependent plastic damage within the plaque microstructure. However, strain history does not compromise critical strength or maximum extension compared with plaques monotonically loaded to failure. These results suggest that a multiplicity of force transfer mechanisms between the thread and plaque-substrate interface allow the plaque-thread structure to accommodate a wide range of extensions as it continues to bear load. This improved understanding of the mussel system at micron-to-millimeter lengthscales offers strategies for including similar fail-safe mechanisms in the design of soft, tough and resilient synthetic structures.

Prenatal diagnosis of alpha thalassaemia major following cordocentesis--a case report.

The relevant investigations and management of a case of alpha-thalassaemia major suspected antenatally is discussed. The value of ultrasonically guided cordocentesis in the definite diagnosis of this condition is emphasised in the management of this pregnancy. We believe that this is the first time such a procedure has been done in this country.

Congenital leukemoid reaction followed by fatal leukemia. A case with Down's syndrome.

A serial clinical, hematologic, and cytogenetic study was done on a baby with Down's syndrome in whom a myeloid leukemoid reaction developed at birth that spontaneously regressed within a month only to relapse two years later to an acute undifferentiated stem cell leukemia. He died 1 1/2 months after onset. The unresolved controversy of the diagnosis of the congenital leukemia-like state is discussed. The importance of following up such patients with apparent remission of their congenital leukemia-like disorder is emphasized.