Determination of zinc in fingernails by non-flame atomic absorption spectroscopy

The determination of Zn in fingernails directly using the graphite furnace presented certain difficulties due to the anomalous behavior of the analyte in the furnace. The appearance of two peaks which were due to Zn and not to any background interference was noted. The Zn value obtained by adding the area of these two peaks compared fairly well with Zn levels determined by wet ashing and subsequent determination either in the furnace or flame. Wet ashed samples gave only a single peak. It was possible to produce a model of the phenomenon with various Zn salts in a non aqueous matrix. Under these conditions ZnSO4 and ZnO gave a discretely different peak from ZnC12 or metallic Zn. Several tissues such as serum, whole blood, cuticle, and hair were examined for multiple peak formation. Direct determination of Zn in fingernails with the graphite furnace is possible for certain applications such as the determination of Zn levels of white spots in fingernails. For this purpose it is possible to use a sample size as small as 20 mug using the 2138 Zn line. This allows one to run several determinations on a single white spot. However, where sample size is not a limitation, wet ash digestion prior to determination in the furnace is probably the preferred procedure.     

Efficient planar convex hull algorithm

A new algorithm for computing the convex hull of a planar set of points is presented. The method of determining the set of suitable candidates is compared with previous algorithms. The algorithm is also compared with other algorithms in terms of running time and storage requirements, and experiments indicate that it is at least as good in terms of space and generally better in terms of running time.     

Results of the treatment of bladder tumors infiltrating the muscle

The results of PUVA treatment for severe alopecia areata (AA) were reviewed in 102 patients. Fifty-three per cent had greater than 90% regrowth of hair. Although these results appear to be encouraging, they differ little from what would be expected with no treatment. We consider that PUVA is not an effective treatment for AA.     

The initiation of a calcium signal in Xenopus oocytes

Clinical and radiographic healing observations were categorized into four patterns: rapid, typical, delayed, and adverse. While considerable overlap of characteristics was noted between the categories, singular factors or combinations of factors enabled pattern identification. The factor primarily associated with the rapid healing pattern was the appearance of bone in the former defect adjacent to the membrane at removal. In contrast, the adverse healing pattern depicted surface necrosis or loss of tissue height at membrane removal. One hundred random sites were evaluated, revealing 13% rapid healing patterns, 76% typical healing patterns, 8% delayed healing patterns, and 3% adverse healing patterns. With favorable patient compliance with oral hygiene and follow-up care, the rapid and typical healing patterns became clinically successful cases. The level of clinical success varied with the delayed healing pattern; the adverse pattern failed to achieve the therapeutic objective.