Formation of nanoparticles by ion beam irradiation of thin films.

The possibility of fabricating nanoparticles by ion bombardment was investigated by the ion bombardment of indium films on oxide covered Si and Cr surfaces. The different masses of implanting specimen ensured the different energy transfer while the same Si substrate ensured the same thermal conductivity for the In and Cr layers. Chromium served as a reference for the effect of ion bombardment and as a substrate as well. The SRIM program was used to simulate the ion surface interaction process. The nanoparticles were detected by scanning electron microscopy (SEM). We found that the melting of the In layer results in the formation of nanoparticles of 50-300 nm diameter and 5-10 nm height. This method can be promising for nanoparticle formation of materials with low melting point.

Divalent Mn in calcium hydroxyapatite by pulse laser deposition.

Pulse laser deposition (PLD) was used to deposit Mn containing calcium hydroxyapatite (HAMn). The PLD process ensures that the composition of the target and the deposited layer is the same. In some cases additional effort should be made to preserve some volatile components, namely OH. This was ensured by water steam supply. Calcium hydroxyapatite deposited by this method has the same properties as the target in respect to lattice parameters and valence state of Mn, which ensures the fixation between hard tissue and metal implants. This fact makes PLD grown HAMn layer covering implants to be improved for practical use.

[Surface treatment of dental implants with high-energy laser beam] . / Fogászati implantátumok felületkezelése nagy teljesítményú lézersugárral.

In the present study the biological value of the laser prepared titanium implants has been investigated. Screw-type implants with different surface modifications were placed into the femurs of rabbits. Removal torque measurements and histological examinations were prepared. The examinations were divided into two groups. In the first part of the examinations the laser surface treatment was compared to other type of surface modifications. In the examination groups the implants were prepared with the following surfaces: 1. machined, 2. sandblasted, 3. low intensity laser surface, 4. high intensity laser surface, 5. titanium oxide coated surface. In the second part of the examinations laser treatment with different physical variables were observed. It has been concluded, that in both cases the high energy laser treated implants needed higher removal torque and in some cases an osteogenic activity was observed around them in the medullary space as well. The authors think the advantage of laser surface treatment lies in special micromorphology and the increased cleanliness of the surface.

Prospects of imaging by associated particle timing with D + D and D + T neutrons.

The optimum parameters and limits are predicted for the performance of an associated particle imaging system on the basis of recently completed projects studying the use of timing with neutrons for elemental analysis of bulk samples such as the human body or traveling trunks.

The elemental analysis of the human body using associated particle timing based on the D + D reaction.

Fast (approximately 2.8 MeV) neutrons are generated in the 2H(d,n)3He reaction, and are used for excitation of sample materials via inelastic scattering. Nanosecond timing identifies the spatial origin of the measured gamma radiation, making possible three-dimensional imaging and improved detection sensitivity. Several elements have been measured, and it is estimated that a clinical device, with equivalent dose of 10 mSv, will be capable of detecting the order of 10-100 mg.

The use of associated particle timing based on the D + D reaction for elemental analysis of bulk samples such as the human body.

The use of associated particle timing based on the D + D reaction has been demonstrated for elemental analysis of bulk samples such as the human body. The neutron energy of 2.8 MeV eliminates the background from organic matrices. The nanosecond timing of a HPGe detector renders it possible to identify the spatial origin of the measured gamma radiation limiting the sensitive area to a single pixel. By this technique the background could be reduced by a factor of > or = 1000, but the present set-up has achieved an effective factor only in the range 20-100, due to losses in the generation of timing signals. The very clean gamma-spectra obtained permit the use of high efficiency scintillation detectors. Sensitivities for measuring Al, Ti, and Fe are presented at an extrapolated dose of 10 mSv.