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Biomedical subjects

M Fabrizio

Publications and source records attributed to M Fabrizio.

At least 19 recordsLinked to original sources

Ni-Zr alloys: relationship between surface characteristics and electrocatalytic behavior

A relationship between electrocatalytic activity for the hydrogen evolution reaction and the surface composition of the electrode was established for Ni-Zr crystalline and amorphous alloys by means of secondary ion mass spectrometry (SIMS). Electrocatalytic activity was tested by means of cathodic polarization in 1 M KOH at 25 degrees C and the resulting exchange current density has been taken as a measure of catalytic efficiency. Surface activation treatment involved chemical etching in HF solutions; the consequent morphological and compositional surface changes were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical behavior of the pure elements (Ni and Zr) was also considered for comparison. All samples submitted to chemical etching in HF solutions showed an increase in electrocatalytic activity, particularly the alloy with the highest Ni content. The beneficial effect of chemical etching is due to dissolution of the zirconium oxide layer and to the formation of nanocrystalline Ni on the surfaces.

Journal Article↗

Secondary ion mass spectrometric investigation on ruthenium oxide systems: a comparison between poly- and nanocrystalline deposits

The influence of different RuO(2) crystallite sizes was investigated by secondary ion mass spectrometry (SIMS) on the oxide deposited on various support materials (Ni, Ti, Al(2)O(3), oxidized Si(100)). In order to examine the effect of an oxidic environment on the film structure, RuO(2) 20%-TiO(2) 80% at. mixed oxide was deposited on Ti. The polycrystalline coatings were prepared by heating the Ru (and Ti)-containing solution dropped on the supports.1 RuO(2) nanocrystalline coatings were grown by chemical vapor deposition (CVD) from Ru(COD)(eta(3)-allyl)(2).2 The identification of mixed oxide clusters showed the higher reactivity of Ni and Al(2)O(3) over the other substrates. Diffusion and migration characteristics were observed to be influenced by the nature of the support. The results are complementary to those of a previous SIMS investigation.3 Copyright 2000 John Wiley & Sons, Ltd.

Journal Article↗

Laparoscopic live donor nephrectomy: pre-operative assessment of technical difficulty.

Laparoscopic live donor nephrectomy decreases disincentives to live kidney donation. Thus, many centers are interested in adopting this procedure. However, the high stakes involved for both the donor and the recipient, and the technical difficulties of the operation, have tempered the enthusiasm of some surgeons. Ideally, if early in their series, surgeons could select patients that would be the least challenging technically, it would facilitate the dissemination of this operation. The purpose of this study is to determine if anatomic or radiologic parameters can accurately assess pre-operatively the degree of technical difficulty of laparoscopic live donor nephrectomy for any individual patient. Abdominal spiral three-dimensional CT scanning was performed prior to laparoscopic donor nephrectomy. CT scans were reviewed for six radiographic anatomic parameters. Seven clinical anatomic measurements relating to body habitus were recorded upon induction anesthesia at the time of surgery. Demographic data for gender, age, race, weight, height, and smoking history were collected. Following laparoscopic live donor nephrectomy, the following six component parts of the operation were graded on a scale of 1-4 (1 = easy, 4 = very difficult) for technical difficulty: a) mobilization of the colon; b) mobilization of the upper pole; c) dissection of the renal vein; d) dissection of the renal artery; e) division of the adrenal vein; and f) dissection of the ureter. Also, operative time, estimated blood loss, and intra-operative fluid requirements were recorded as surrogate markers of operative difficulty. Forty-one patients were included in the study. Laparoscopic donor nephrectomy was successfully completed in all cases. The sum of the difficulty scores was 9.9+/-3.1 (mean) (range, 6-18). No anatomic, demographic, or radiologic parameters were predictive of the total operative difficulty score. Of the surrogate markers, only operative time correlated with total difficulty score (R = 0.47, p = 0.003). Donor weight and abdominal girth correlated with operative time (R = 0.50, p = 0.002; R = 0.38, p = 0.019) but not with total difficulty score (R = 0.10, p = 0.51; R = -0.02, p = 0.90, respectively). When the easiest cases and the hardest cases (< or = 25th percentile and > or =75th percentile total difficulty score, respectively) were segregated out, again no anatomic, demographic, or radiologic parameters were predictive of operative technical difficulty. In conclusion, laparoscopic live donor nephrectomy technical difficulty could not be predicted by body habitus from the variables examined in this study. Hence, it was equally likely that performing laparoscopic live donor nephrectomy using a heavy donor would be technically easy, as using a thin donor would be difficult. Although, in general, operative time increased with donor size and weight, it appears that laparoscopic live donor nephrectomy operative technical difficulty is dependent upon such factors as amount of laparoscopic working space, quality of tissue planes, and retractability of the colon and mesocolon; factors that, to date, are not quantifiable.

Adult↗

Ureteroscopic and radiographic imaging of the upper urinary tract.

Direct endoscopic viewing of the upper urinary tract offers multiple benefits, including recognition and diagnosis, and also permits unsurpassed accuracy in positioning working instruments for biopsy and treatment. We have demonstrated the normal and abnormal endoscopic findings within the upper urinary tract in patients who were treated ureteroscopically for numerous indications, including calculi, filling defects, or ureteral obstruction. Small (7 to 7.5F) rigid and flexible ureteroscopes were employed in all patients. Selected endoscopic images of the subject lesions were photographed using a 35-mm camera with an endoscopic zoom lens and ISO-400 film. Endoscopic findings are illustrated in 13 patients, with case summaries in 11. Selected radiographic and endoscopic images show the essential features in each case and demonstrate the value of ureteroscopic examination.

Adult↗

Vigilance and automobile accidents in patients with sleep apnea or narcolepsy.

Patients with obstructive sleep apnea or narcolepsy report difficulty remaining alert and attentive. To detect impaired vigilance, we designed Steer Clear, a computer program simulating a long and monotonous highway drive that presents 780 obstacles in 30 min. Sixty-two patients with sleep apnea hit a higher percentage of obstacles (4.3 +/- 0.6% [SEM]) than 12 age- and sex-matched subjects without sleep apnea (1.4 +/- 0.3%; p < 0.05) and 10 age- and sex-matched volunteers (1.2 +/- 0.3%; p < 0.05). Ten patients with untreated narcolepsy hit a higher percentage of obstacles while performing on Steer Clear (7.7 +/- 3.2%) than 10 age- and sex-matched subjects without narcolepsy (1.2 +/- 0.3%; p < 0.05). Poor performance on Steer Clear was associated with a higher auto accident rate in the patients with sleep apnea or narcolepsy (p < 0.01). Twenty-one patients who performed normally on Steer Clear had 1 accident in 5 years (0.05 accident/driver/5 yr), and in none of these accidents were they at fault as drivers. Twenty-five patients who performed poorly on Steer Clear had 5 auto accidents in 5 years (0.20 accident/driver/5 yr), and in 20% of these accidents they were at fault as drivers. Twenty-one patients who performed very poorly on Steer Clear had 8 auto accidents in 5 years (0.38 accident/driver/5 yr), and in 38% of these accidents they were at fault as drivers. These 21 patients who performed very poorly on Steer Clear (hitting > 4.5% of obstacles) had a significantly higher auto accident rate than the patients who performed normally (hitting < 1.8%). We conclude: (1) Patients with sleep apnea or narcolepsy performed more poorly on a test of vigilance, Steer Clear, than did control subjects; (2) Impaired vigilance as measured by Steer Clear is associated with a high automobile accident rate in patients with either sleep apnea or narcolepsy.

Accidents, Traffic↗