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Controllable production of nanometre-sized structures is an important field of research, and synthesis of one-dimensional objects, such as nanowires, is a rapidly expanding area with numerous applications, for example, in electronics, photonics, biology and medicine. Nanoscale electronic devices created inside nanowires, such as p-n junctions, were reported ten years ago. More recently, hetero-structure devices with clear quantum-mechanical behaviour have been reported, for example the double-barrier resonant tunnelling diode and the single-electron transistor. The generally accepted theory of semiconductor nanowire growth is the vapour-liquid-solid (VLS) growth mechanism, based on growth from a liquid metal seed particle. In this letter we suggest the existence of a growth regime quite different from VLS. We show that this new growth regime is based on a solid-phase diffusion mechanism of a single component through a gold seed particle, as shown by in situ heating experiments of GaAs nanowires in a transmission electron microscope, and supported by highly resolved chemical analysis and finite element calculations of the mass transport and composition profiles.

Maxillary growth after unilateral closure of surgically induced defects in the hard palate in 6- to 8-week old Beagle puppies was studied. The hard palate except for a 4 mm wide strip of bone in the midline and with its overlaying oral mucoperiosteum was removed. On one side the nasal mucoperiosteum was covered with an autogenous full-thickness skin graft (side SGS) and, on the other side the raw surface (side RS) was left for secondary epithelialization. The animals were killed at 47 to 52 weeks of age. Measurements on the dried skulls of the experimental dogs showed no difference in total maxillary length between the two sides of the maxilla. However, the posterior half of the maxilla was longer in 8 dogs on side SGS and the anterior half of the maxilla was in 7 dogs long on side RS. The palatine suture was displaced towards side RS on all dogs, and the height of the nose was in all dogs greater on side SGS. There was a small consistent tendency that the overall growth was more pronounced on the side with the full-thickness skin graft. It is concluded that reducing the amount of scar tissue by covering raw surfaces with an autogenous full-thickness skin graft is one way to reduce maxillary growth impairment after palatal surgery.

The use of adhesive tape as wound treatment in leprosy cases is described and found to be superior to the classical dressing as regards security and facility of application, and for the rapidity and quality of healing. Its use as a "preventive" treatment is stressed. The results of this study seem to justify the following conclusions: The adhesive tape is easy to handle, it heals the leprosy wounds in about half the time necessary for the classical dressing and it costs about 50 times less.

A total of 23 patients with partly resected mandible were repaired with autogenous bone grafts from the iliac crest and ribs. The reasons for reconstruction are presented in Table 1. The grafts healed without complications in 21 cases. With the exception of two of the cases with gunshot wounds, all patients recovered good mobility of the jaw and satisfactory mandibular contours. The patients had been folloed up for 6 months to 11 years. Radiographic examination at the last examination showed that resorption of the graft had been only slight or moderate. Through marrow-spongious bone grafts are regarded as best from an osteogenetic point of view, our cases showed that good results can be achieved also with solid block grafts. The authors discuss the use of plate osteosynthesis without IMF instead of other types of graft fixation and IMF. In six cases where the area of the graft was loaded with a prosthesis, resorption was not more extensive than in the other cases.

Homologous vessel grafts were tried as substitutes for flexor tendon grafts. Pieces of different lengths were excised from a flexor tendon and replaced by a homologous abdominal aorta graft which was turned inside out and then anastomised by drawing it over the tendon stumps in a cuff-like manner. The grafts became firm, homogeneous and completely tendon-like with very little adhesion but with a tendency to become extended and thus too long to be functional.

Abstract: For a G-graded ring R, the problem of Gr-regularity (i.e. von Neumann regularity condition on homogeneous elements) has been treated earlier (see Năstăsescu and Van Oystaeyen, 1982 ). Once the concept of the smash product was introduced, this problem has been resumed by several authors. This paper is concerned with von Neumann regularity of two smash products: the smash product of the G-graded ring R by the group G and the smash product of R by a finite left G-set A. The connections between the regularity of and the (Gr-)regularity of R are also investigated. One consequence of our results is that the smash product is a von Neumann regular ring if and only if the category -gr is regular, in Stenström''s sense. [Copyright &y& Elsevier]