Misdiagnosis of intraocular iron foreign bodies (author's transl)

Out of 393 intraocular foreign bodies (1961-1975) 361 were magnetically removed and 32 non-magnetically (copper 7,brass,2,lead 5, glass 10, stone 3, wood 4 and plastic 1).60% of the foreign bodies were caused by hammer and chisel injuries.73 foreign bodies were diagnosed too late, in 71 cases no x-ray was made. The incidence of complications (infection, siderosis, retinal detachment was considerably increased where the foreign bodies were removed late. From the 73 foreign bodies (18.5%) the patient did not consult a doctor in 37 cases because of "insignificance". 4 times the family doctor was consulted, who treated the patient symptomatically. In 4 cases occurring in the weekend no eye-specialist could be ostensibly found. In 26 cases the ophthalmologist performed no x-ray control, and small foreign bodies were twice described as "x-ray plate artefacts" from the roentgen specialist. It must be an absolute rule in the eye-doctor's practice that every injury received while working with metals necessitates an x-ray control!     

The problem of functional achlorhydria]

It was examined whether in anatomically intact specific adenic parenchyma of the gastric mucosa achlorhydria can persist after maximal stimulation or whether there is support to the conception of functional achlorhydria ("functional anacidity") furthermore. Relating to the anatomic structure of the gastric mucosa secretion of chloric acid was studied after submaximal and maximal stimulation in 101 cases. It was shown that there is no correlation between the morphology and the secretion of chloric acid in anatomically intact gastric mucosa after submaximal stimulation. In 18 cases out of 28 only the secretion of acid was in correspondence to the histological condition. In two cases out of 37 with atrophic gastric mucosa diverging results were found. After maximal stimulation with histamine chloride and pentagastrine one out of two cases with histologically intact mucosa showed normochlorhydria after seven days, whereas the second case remained achlorhydric. These results must be interpreted as functional achlorhydria. Submaximal stimulation of gastric secretion as it is practised today does not allow corresponding consequences concerning the morphological condition of the gastric mucosa. Discrepant results are found especially in histologically normal mucosa. There is more congruence in atrophic gastric mucosa.     

Safety on ladders: an ergonomic design approach

By studying the interactions between the user and a ladder or steps, with different shaped rungs, the author determines a preferred rung shape for improved ladder safety.     

Cracking in and around the thermally grown oxide in thermal barrier coatings: A comparison of isothermal and cyclic oxidation

In the present paper the time and temperature dependent evolution of the microstructure of TBC systems and especially of post-experimentally determined physical defects in and around the TGO for both isothermal and cyclic exposure conditions are investigated. Specimens with APS- as well as with PVD-topcoats have been oxidised between 950 and 1100°C up to a maximum duration of 5000 h followed by extensive scanning electron microscopy and subsequent interactive image analysis to measure the maximum crack lengths in and around the TGO. These cracks are additionally classified with respect to their local orientation in the TGO or its vicinity. The results of isothermal and cyclic test conditions show a number of similarities in results e.g. an unsystematic occurrence of inwardly growing, “cauliflower like” oxide or the most frequently occurring type of cracks in APS systems. Nevertheless substantial differences concerning the final failure, microstructure, crack growth behaviour and finally life time of the component between isothermal and cyclic test conditions exist. Some indications were found, that for this particular bond coat occurance of inwardly growing oxide intrusions increases the adherence of the TGO.     

Fabrication of Al/AlN composites by in situ reaction

The tensile properties and microstructures of various Al alloys fabricated by the pressureless infiltration method under a nitrogen atmosphere were examined. The spontaneous infiltration of molten metal into the powder bed occurred at 800 °C for 1 h under a nitrogen atmosphere. As a result, it was possible to fabricate Al alloys reinforced with AlN particles formed by in situ reaction. A significant strengthening even in the control alloy occurred due to the formation of in situ AlN particle even without an addition of artificial reinforcement. Strength values of the control alloy were increased with decreasing Al powders in bottom powders bed. In addition, tensile strength in Al–Mg alloys was increased with Mg content.     

The Transfer of Fibres in the Carding Machine

The problem of understanding the transfer of fibres between carding-machine surfaces is addressed by considering the movement of a single fibre in an airflow. The structure of the aerodynamic flow field predicts how and when fibres migrate between the different process surfaces. In the case of a revolving-flats carding machine the theory predicts a “strong” aerodynamic mechanism between taker-in and cylinder and a “weak” mechanism between cylinder and removal cylinder resulting in effective transfer in the first case and a more limited transfer in the second.     

Sol–gel alumina environmental barrier coatings for SiC grit

SiO₂ surface film is insufficient to protect SiC from the oxidation at widely varying partial pressures of oxygen, in particular in the presence of water vapor (e.g. in gas turbines) and also in other environments, e.g. during brazing for hard “tipping” of turbine blades. This work demonstrates that sol–gel alumina, coated on 0.5 mm coarse SiC grit, may form an acceptable, up to 10 μm thick “environmental barrier coating” EBC for some of these applications. The sol–gel has advantages over other methods (such as CVD) is the simplicity and low cost. We have used NH₄OH pre-treatment to hydroxylate surface of SiC prior to applying alumina coating. Such modified SiC/SiO₂ surface helped to deposit the positively charged alumina sol, and thus allowed to build thick coatings on the SiC grit. There is some indication that these coatings partially convert to mullite through reaction at the interface with the native silica on SiC. Oxidation resistance tests at 1200 °C were performed to show effectiveness of such coated SiC grit.     

Some spectral response characteristics of ZnTe thin films

Zinc telluride thin films have been grown at room temperature and higher temperature substrates by thermal evaporation technique in a vacuum of 10^-6 torr. A main peak in the photocurrent is observed at 781 nm (1.58 eV) with two lower amplitude peaks on the lower wavelength side and one on higher wavelength side. The evaluated thermal activation energy is found to correspond well with the main spectral peak. From these studies it can be inferred that temperatures up to 453 K is still in the extrinsic conductivity region of the studied ZnTe thin films. The paper was presented at the 6th Asian Thermophysical Properties Conference (6th ATPC), held at Gauhati University, during 8–11 October 2001.