Search

Experimental results from stressing Schottky diodes and HBTS employing TLP (Transmission Line Pulses) with 100ns duration time and ESD pulses following the Human Body Model are compared. Based on optical and electrical characterisation the same failure mechanisms seem to occur indicating the strong degree of relationship between these two methods. Device failures are explained by thermally activated interface and bulk reactions, field enhanced material transport and hot charge carrier effects.

Serial measurements of blood haemoglobin, serum iron, serum transferrin, total iron-binding capacity, transferrin per cent saturation and serum ferritin were determined in 51 post-operative critically ill patients to investigate body iron status in severely stressed patients. The results showed decreased blood haemoglobin, serum iron, serum transferrin and transferrin saturation compared to an increase in serum ferritin levels. These results indicate that there is inadequate availability of iron to tissues (secondary to rearrangement of body iron to the advantage of the iron storage compartment), which is often present in severely critically ill patients. A positive correlation was found between the initial (ferritin) levels and SAPS (r=0.41,p< 0.01). In addition, the increase of ferritin concentration parallels a worsening of the clinical status in severely ill patients. This is due to enhanced release by the macrophage system. From this, we consider serum ferritin as an acute-phase protein and a useful marker of the severity of the clinical status. It appears to be useful in predicting the patient's outcome, but is not reliable in evaluating iron stores in stressed patients.

Red cell and iron status parameters were studied in a group of 44 children undergoing tonsillectomy for recurrent throat infections and in a control group of 40 healthy children. In the patient group, before tonsillectomy, 8 children presented a latent iron deficiency and 15 a decrease in serum ferritin levels. This altered iron status can be attributed to a reduced intestinal iron absorption, due to recurrent infections. One and seven days following surgery there was a significant fall in serum iron, serum transferrin and transferrin saturation, in parallel with an increase of serum ferritin and alpha-2 globulins levels. These modifications cannot be attributed to the blood loss, as proven by the constance of haemoglobin level and of other red cell parameters, but to an unspecific reaction to surgical stress, as observed in fever, traumas and inflammation. They reflect an altered processing of iron, with a temporary block of its release to plasma and an increased storage within the reticuloendothelial cells.