Bibliothek

Notizen: Amorphous powders of a Nd15Fe77B8 alloy were obtained by mechanical grinding of the alloy ingots. Mechanical grinding of Nd15Fe7B8 alloy ingots reduced the average particle size to 1 μm within the relatively short period of milling times. Extended milling did not yield further reduction in particle size, but resulted in a change in the structures from Nd2Fe14B crystallites to an amorphous structure. It was found that the crystallization of α-iron from amorphous matrix took place in some stage of milling. The amorphous materials were stable up to 820 K at a heating rate of 0.33 K/s. Heat treatment of the amorphous materials above the crystallization temperature resulted in the crystallization of the Nd2Fe14B phase and the resultant materials showed a high coercivity of 11.9 kOe as in the case for the amorphous Nd-Fe-B materials produced by rapid quenching techniques.

Notizen: Objectives To review the epidemiology of published randomised controlled trials in infertility treatment over the last 25 years, with special emphasis on the number and quality of trials.Design Computer literature review by MEDLINE backed up by a manual search of 41 journals. Each trial was classified according to the methodology described and quality criteria. The results were recorded in a computer database. Odds ratios (OR) and confidence intervals (CI) were calculated where the data were sufficient.Subjects Couples suffering from primary or secondary infertility. The trials studied 33 761 patients overall.Setting Institute of Epidemiology and Health Services Research, Leeds.Results Five hundred and one randomised trials in male and female infertility treatment were identified between 1966 and 1990. Pregnancy was an outcome in 291 (58%) and these were the subject of detailed analysis. Two hundred and twenty-four (77%) and 67 (23%) ‘pregnancy trials’ were concerned, respectively, with female and male infertility. Four per cent of the trials were preceded by a sample size calculation, and the average sample size was 96 patients (range 5–933); 700 patients per group would be required to demonstrate plausible success rates for most treatments. The method of randomisation was unstated or pseudo-randomised in 206 (71%) of trials where pregnancy was an outcome. Only 29 (5.8%) of studies were multicentre. The method of confirmation of pregnancy was omitted for 70% of papers. Cross-over design was used in 103 (21%) of cases. Meta-analysis is possible for selected topics such as the use of anti-oestrogens in idiopathic oligospermia and unexplained female infertility. Eight cases of double reporting were identified.Conclusions Trials using randomised methodology were relatively few in comparison with other branches of medicine, although their use is important in the evaluation of treatment for infertility as treatment-independent pregnancy is common. It was encouraging to note that an exponential increase in the use of this methodology occurred during the last three years, especially in association with assisted conception techniques, and meta-analysis has become possible for selected topics. However, many trials suffer from an unrealistically small sample size, inappropriate use of cross-over design or pseudo-randomisation. The trend towards properly controlled studies should be encouraged but these studies should be of improved quality and organised on a multicentre or even international basis.

Notizen: Skin biopsy was performed in five cases of pemphigus; direct immunofluorescence (IF) studies demonstrated intercellularly bound IgG and C3 in each case. Sections of lesional skin, containing in vivo bound IgG were, in two cases, capable of further binding C3in vitro from normal human serum, an effect most marked in relation to areas of acantholysis. This work provides additional evidence that the complement system is involved in the process of pemphigus acantholysis.

Notizen: A novel method was developed to fabricate corrugation for a λ/4-shifted distributed feedback (DFB) laser. Mechanically ruled grating patterns were transferred photolithographically to the surface of an InP substrate. The resultant λ/4-shifted DFB laser operated in a single longitudinal mode at the Bragg wavelength.

Notizen: A varied line-spacing plane grating monochromator is installed at an undulator beamline BL-19B of the Photon Factory. Small contribution of aberrations to image sizes at a focal plane of the varied line-spacing plane grating is calculated with use of an optical path function. The largest resolving power obtained from a ray tracing is estimated to be 4600 at a photon energy of 1239.85 eV and 10 000 at 91.2 eV. Gas absorption spectra show the similar extent of resolution obtained by the ray tracing. A high brightness with a high resolution may be realized in this monochromator. © 1996 American Institute of Physics.

Notizen: We report the second known case of yolk sac tumour of the external auditory canal, occurring in an eight-month-old girl. The excised tumour demonstrated histopathological and immunohistochemical features identical to those of yolk sac tumours of gonadal origin. The tumour was aneuploid by flow cytometry. The patient received chemotherapy post-operatively and has had no evidence of disease 13 months after surgery.

Notizen: We report a case of angiosarcoma and dermal melanocytosis occurring simultaneously in the same lesion. We examined the primary and 2 metastatic lesions. Histopathologically, the anaplastic angiosarcoma cells had a tendency to form irregularly shaped small cavities. Immunohistochemically, they were strongly reactive with Ulex europaeus agglutinin (UEAI) stain. The mid and deep dermis of the same lesion had spindle or elongated slender melanocytes containing melanin granules. The melanocytes were positive with S-100 protein stain. Ultrastructurally, pinocytotic vesicles, fine filaments, and Weibel-Palade body-like dense granules were observed in the cytoplasm of angiosarcoma cells. Dermal melanocytes had external lamina and melanosomes in various stages. The melanocytes showed no similarity to the neoplastic tumor cells and there was no apparent intermediate form between the 2 kinds of cells. The etiological implications of dermal melanocytosis with a tumor of vascular origin are discussed.

Notizen: To study cooking kinetics, slices (6 mm thick, 30 mm diameter) of 3 potato varieties were treated in water at 90°, 100° and 110°C for varying times. Sensory, chemical and physical properties were investigated. Changes during cooking at constant temperature were mathematically described by a 0 order (texture, taste) and a 1st order (shear force, dry matter, pectin, soluble amylose, cell size) equation. The starch content remained constant. Temperature dependence of the rate constant could always be described by a first order equation. The z-values, which are necessary to calculate Cvalue for practical heat treatments, could be determined. Correlations established between kinetics of different properties showed that behavior of certain potato properties may be predicted by shear-force measurement.

Notizen: A previous study of three potato varieties indicated that shear force measurement may be used to predict the behavior of certain potato properties during cooking. To verify this hypothesis and to confirm other previous findings, slices (6 mm thick, 30 mm in diameter) of 21 potato varieties were thermally treated in water at 100°C. Mathematical expressions were assessed, and coefficients were determined to describe the kinetic behavior of the varieties.