Calculation of laser absorption by metal powders in additive manufacturing.

We have calculated the absorption of laser light by a powder of metal spheres, typical of the powder employed in laser powder-bed fusion additive manufacturing. Using ray-trace simulations, we show that the absorption is significantly larger than its value for normal incidence on a flat surface, due to multiple scattering. We investigate the dependence of absorption on powder content (material, size distribution, and geometry) and on beam size.

First-principles studies of the metallization and the equation of state of solid helium.

The insulator-to-metal transition in hcp solid helium at high pressure is studied with first-principles simulations. Diffusion quantum Monte Carlo (DMC) calculations predict that the band gap closes at a density of 21.3 g/cm;{3} and a pressure of 25.7 terapascals, which is 20% higher in density and 40% higher in pressure than predicted by density functional calculations based on the generalized gradient approximation (GGA). The metallization density derived from GW calculations is found to be in very close agreement with DMC predictions. The zero point motion of the nuclei had no effect on the metallization density within the accuracy of the calculation. Finally, fit functions for the equation of state are presented, and the magnitude of the electronic correlation effects left out of the GGA approximation are discussed.

Interplay between magic number stabilities and superfluidity of small parahydrogen clusters.

The interplay between magic number stabilities and superfluidity of small parahydrogen clusters with sizes N=5 to 40 and temperatures 0.5 K

Glomus tumors: report on eleven cases and a review of the literature.

INTRODUCTION: Glomus tumor is a well known pathology in hand surgery; in addition to sites in the upper limbs, it can also affect the lower limbs and develop in other parts of the body. MATERIALS AND METHODS: Seven females and four males with glomus tumors underwent surgery between 1990 and 1998 at our hospital. These cases were retrospectively studied, and immunohistochemical staining was carried out for vimentin, factor VIII and CD34. RESULTS: At the time of diagnosis, the mean age of the patients was 49 years, with a mean follow-up of 18.5 months. Regarding tumor site, there were six digital, one wrist, two neck and two lower limb locations. In this series, familial incidence was observed in two cases, i.e., two sisters with tumor occurrence at the same digital site. Tumor size varied from 0.2 to 5 cm. In agreement with the findings in the literature, the present results showed only a low incidence of locations other than in the upper and lower limbs. Moreover, no multiple locations or degenerative malignancy were observed, both of which are known to be rare. In all cases, the histological aspect of these tumors was typically benign. Immunohistochemical studies of the tumor cells were positive for anti-vimentin antibody in all cases, negative for anti-factor VIII in all cases and irregularly positive for anti-CD34 antibody. DISCUSSION: It was not possible to confirm the specificity of the anti-CD34 antibody for glomus tumor in this series. The hypothesis of the endothelial origin of glomus tumor can probably be dismissed in the absence of the expression of anti-factor VIII and anti-CD34 antibodies.

Bilateral breast cancer in a male? Case report.

Cancer of the breast in male is a rare disease. Its bilaterality is exceptional. In this article, the authors report the case of a probable bilateral cancer in a 41-year-old male who lived three years after diagnosis of his disease.

Fungal keratitis in Saudi Arabia.

We studied a total of 27 cases of fungal keratitis is Saudi Arabia. History of trauma was found in 9 patients, and previous use of topical steroids in 6 patients. In the majority of patients the onset of the disease was in fall and spring. The most frequent cause of fungal keratitis was found to be Aspergillus spp., and these were isolated from 11 cases (41%). Eight of the 11 isolates were Aspergillus flavus. Other causes of keratomycosis included: Fusarium, Candida, and Mycelia sterilia. All patients were treated with antifungal therapy and 18 patients required surgical intervention. Vision improved among 11 patients, remained the same in 4 patients, and deteriorated after treatment in 6 patients. (6 patients failed to return for follow-up.) Four of the 27 patients developed fungal endophthalmitis. The high prevalence of Aspergillus spp. may be due to the fact that spores of Aspergillus can survive the hot and dry weather of Saudi Arabia.

[Segmental dilatation of the ileum in a neonate. Study of the myenteric plexus with a silver staining preparation (author's transl)]. / Dilatation segmentaire du grêle à révélation néonatale. Etude par imprégnation argentique des plexus myentériques.

A case of segmental dilatation of the ileum in a neonate is reported. Conventional staining methods failed to show any abnormality, but a study of the myenteric plexus with a silver preparation demonstrated reduction in the number of agyrophil neurons and irregular and altered neuron cell bodies. Occurring in a neonate, therefore without previous clinical history, this case, together with various published data suggests that in some cases segmental dilatation of the ileum is due to congenital damage to the myenteric plexus.