Wetting ability of biological liquids in presence of metallic nanoparticles.

The wetting ability of water and of some biological liquids was measured on different biocompatible surfaces with and without different colloidal metals. Insoluble nanoparticles disperse in biological tissues enhance some properties, such as the interface adhesion between two surfaces, the X-ray contrast of medical images and the absorbed dose during radiotherapy treatments. The introduction of nanoparticles in the liquids generally improves the wetting ability and changes other properties of the solution, due to the different distribution of the adhesion forces, to the nature, morphology and concentration of the added nanoparticles. An investigation on the contact angle of the liquid drops, physiological liquids, including the human blood, placed on different substrates (polymers, ceramics and metals) with and without the use of metallic nanoparticles is presented, evaluated and discussed.

Silver coins analyses by X-ray fluorescence methods.

The investigation on the differences occurring in the manufacture of silver coins allows to get information on their elemental composition and represents a powerful support to the methodology to identify the producing technologies, workshops being also instrumental to distinguish between original and counterfeit ones. Aim of the present work is to study recent and old silver coins through non-destructive X-Ray Fluorescence (XRF) analysis. The XRF was applied to extend the analysis to the deepest layers of the coins; for surface layers an X-ray tube or an electron beam were employed to induce the atom fluorescence to obtain information on the surface elemental composition. Moreover, a detailed study has been performed to evaluate the influence of the surface curvature on the measurement, by deducing a proper corrective factor to keep into account in the data analysis. The elemental atomic composition was measured for each coin, mainly by means of the X-ray tube excitation for the bulk and the electron Scanning Electron Microscope (SEM) microbeam probe for the surface patina analysis. Ionization was induced by an X-ray tube using an Ag anode for the bulk and by an electron microprobe for the surface composition. X-ray detection was performed by using a semiconductor Si device cooled by a Peltier system. The Ag L-lines X-ray yield is affected by coin surface morphology and geometry. The comparison between coin spectra and standard samples, shows that the Ag quantitative analysis is influenced by error of the atomic concentration lower that 10%.

Laser generation of Au ions with charge states above 50+.

Results of recent studies on highly charged Au ion generation, using the intense long pulses of the PALS high power iodine laser (lambda=1.315 microm, E(L)=800 J400 ps), operating under variable experimental conditions (1omega, 3omega, varying target thickness and changing focus positions), are presented. Both the ion collectors and the ion electrostatic analyzers were applied for the identification of ions in a large distance from the target. The time-of-flight collector signals were treated by a means of peak deconvolution assuming a shifted Maxwell-Boltzmann form of the constituent ion current peaks. Attention was paid to the influence of pulse precursor, which becomes evident, especially, if using thinner targets and 1omega. The results for 3omega point to the presence of several groups of ions with the highest recorded charge state Au(53+).

Electron beam irradiated UHMWPE: degrading action of air and hyaluronic acid.

Ultra high molecular weight polyethylene, both pure and electron beam irradiated, was exposed to air and hyaluronic acid. Physical and mechanical analyses were performed in order to check the polymeric change due to the treatment. Pure UHMWPE, in fact, was modified by the hyaluronic acid that plasticizes the polymer. The electron irradiation cross links the chains and prevents their sliding in acid presence. A low irradiation dose is preferable rather than an high one. Low doses induce low amount of free radicals, witch react with oxygen and hyaluronic acid inducing low polymer degrade maintaining the initial mechanical performance. High doses degrade significantly the polymer properties.100 kGy irradiation in air can be applicable on the polyethylene as well as a compromise between the low mechanical performance improving and the material degradation.

Treatment techniques on biocompatible titanium to modify the surface wetting properties.

The physical properties of biocompatible titanium surfaces were modified using different techniques of surface treatment. Particularly the measurements of roughness and wetting ability were controlled using six different techniques: polishing, sandblasting, acid attack, laser ablation, ion implantation and nanoparticle deposition. The titanium surface wetting can be modified drastically depending on the used treatment to enhance the hydrophilic or the hydrophobic behaviour of the metallic biocompatible surface. The study demonstrates that a linear relation between roughness and contact angle occurs. Possible applications to permanent or removable prosthesis titanium based are presented and discussed.

Mechanical behavior of quartz fiber reinforced epoxy resins for teeth restoration.

In this work composite materials, based on quartz fibers and epoxy resins, were employed with the aim to restore damaged teeth. The composite materials were chosen because they show biomechanical features very similar to that of the dentine, the main constituent of the tooth. Extracted teeth were rebuilt with two different restorative procedures: in the first, the composite material was pre-formed in a conical trunk shape abutment (PA) and then bonded to a fiber quartz post with a dental bonder. In the second rebuilt system the abutment was prepared by cross linking the resin on the fiber quartz post with a halogen lamp (CRA). The restored teeth were then mechanically tested and observed with a Scanning Electron Microscope (SEM) with the aim to study the interaction between the reconstructive materials. Wetting and roughness measurements were also carried out in order to study the interface adhesion between the post and the abutments. Characterization analysis evidenced that the CRA restorative procedure improves the adhesion between the substitutive materials and shows higher fracture strength than the PA ones. Anyway both the rebuilt systems are able to support the masticator load. An explanation of the interfacial post-abutment interaction phenomenon is discussed.

Mosaic trisomy 17 in amniocytes: phenotypic outcome, tissue distribution, and uniparental disomy studies.

Mosaicism for trisomy 17 in amniocyte cultures is a rare finding, whilst postnatal cases are exceptional. In order to gain insight into the possible effects of the distribution of the trisomic line and of uniparental disomy (UPD) on embryofoetal development, we have performed follow-up clinical, cytogenetic and molecular investigations into three newly detected prenatal cases of trisomy 17 mosaicism identified in cultured amniotic fluid. In the first case, the pregnancy ended normally with the birth of a healthy girl, and analysis of newborn lymphocytes and of multiple extra-embryonic tissues was indicative of confined placental mosaicism. The second case was also associated with a normal pregnancy outcome and postnatal development, and only euploid cells were found in peripheral blood after birth. However, maternal isodisomy 17 consequent to a meiosis II error and loss of a chromosome 17 homologue was detected in peripheral lymphocytes postnatally. In the third case, pathological examination after termination of pregnancy showed growth retardation and minor dysmorphisms, and the trisomic line was detected in foetal skin fibroblasts. In addition, biparental derivation of chromosome 17 was demonstrated in the euploid lineage. These results, together with previously reported data, indicate that true amniotic trisomy 17 mosaicism is more commonly of extra-embryonic origin and associated with normal foetal development. Phenotypic consequences may arise when the trisomic line is present in foetal tissues. Case 2 also represents the first observation of maternal UPD involving chromosome 17; the absence of phenotypic anomalies in the child suggests that chromosome 17 is not likely to be subject to imprinting in maternal gametes.

Pervasive developmental disorder and epilepsy due to maternally derived duplication of 15q11-q13.

Duplications of chromosome 15 have been reported in individuals with atypical autism, varying degrees of mental retardation, and epilepsy. The authors report the molecular analysis, neurophysiologic, and clinical evaluation of a 12-year-old boy with atypical autism and epilepsy due to a maternally derived 15q11-q13 duplication. Their findings suggest that this chromosomal region harbors genes for autism and possibly for partial epilepsy that may act in a dose-dependent manner.

Rearrangements of chromosome 15 in epilepsy.

A number of observations point to chromosome 15 as a good candidate to harbor genes involved in epilepsy. This hypothesis is supported by at least two lines of evidence: one is the finding that haploinsufficiency of the 15q11-q13 region, of maternal origin, is responsible for Angelman syndrome, one of the cardinal manifestations of which is epilepsy; the second is the observation that extra copies of this same genomic region, in the form of inv-dup(15) or intrachromosomal duplications, again of maternal origin, are usually associated with a severe neurological phenotype characterized by developmental delay and untreatable seizures. Therefore, both reduced and increased dosage of genes from the 15q11-q13 region, possibly subjected to maternal imprinting, appear to be causally involved in severe forms of epilepsy. We tested the hypothesis that submicroscopic rearrangements of this genomic region might be responsible for nonsyndromic epilepsy in both familial and sporadic forms. To this purpose, we genotyped 118 epileptic patients and their parents with closely spaced microsatellite markers mapped within the 15q11-q13 region. We report on the results of these studies and review the relevant literature.

Wear of nickel-titanium endodontic instruments evaluated by scanning electron microscopy: effect of ion implantation.

The present work analyzes possible increases in resistance to wear of nickel-titanium endodontic instruments that have undergone a process of ionic implantation. ProFile .04 taper #25 instruments were subjected to ionic implantation with bands of nitrogen ions of 250 KeV, currents in the order of 10 microA/cm2, and doses of 2 x 10(17) ions/ cm2. The instruments were used to make preparations in acrylic endodontic training blocks. Scanning electron microscopic investigations showed that after 60 s of work inside the endodontic training blocks nonionic implanted control instruments showed small modifications in their blades, and their tips showed the first signs of wear. After 240 s the control instruments showed consistent signs of wear and frequent changes to their surfaces. After 240 s of use the ionic-implanted instruments did not present any significant changes in the micromorphology of their surfaces. The implanted instruments did not manifest the typical signs of wear and did not show the surface changes that quickly affect the working life of untreated endodontic instruments manufactured from nickel-titanium.

Microfilters for biomedicine obtained by swift ion processing.

Swift ions with 50 MeV energy are used to irradiate bio-polymeric films. Lithium, carbon and oxygen beams, with fluencies ranging between 10(8) and 10(13) ions/cm2, are swept on large surfaces of hydrogenated and fluorated polymers. The electronic stopping power of the ion induces high rates of ionization, excitation and radical formation along the ion path with production of chain-scission and cross-linking processes which can be investigated by the molecular emission from the irradiated polymer. The radiation damage increases the chemical solubility of the material around the ion track up to distances of the order of 100 nm. A suitable chemical etching removes the damaged material leaving micrometric holes in the polymeric film. This process gives rise to micro-perforated films which can be used as microfilters, with sub-micrometric pore dimension, high selectivity and controllable porosity. Their use is very interesting for special applications in ultra- and microfiltration of biological liquids.

Ion implantation and thermal nitridation of biocompatible titanium.

Nitrogen implantation and thermal nitridation processes are investigated to improve the wear resistance of titanium medical devices. Ion implantation uses 80 keV nitrogen ions and doses ranging between 1 x 10(17) and 5 x 10(17)/cm2 to modify the surface layers up to 140 nm depth. Stable surface layers are obtained at high ion doses by post-annealing at 550 degrees C for 30 min. Thermal processes are developed as a function of the time (20-90 min) and annealing temperature (950-1100 degrees C) in a dry nitrogen atmosphere. The amount of titanium nitride formed during the thermal process increases with the annealing temperature and time. Samples are analysed by Rutherford Backscattering Spectroscopy (RBS), Auger Electron Spectroscopy (AES) and Scanning Electron Microscopy (SEM). Ion implantation and thermal nitridation processes increase the surface hardness and wear resistance improving the mechanical properties of titanium used for movable devices for total joint replacements, such as the hip and knee protheses.

The NiTi superelastic alloy application to the dentistry field.

The main properties of NiTi alloys are presented, discussed and compared with respect to those of stainless steels. Special regard is given to the use of NiTi alloy as orthodontic wires and endodontic instruments. The superelastic properties of orthodontic wires and endodontic files are measured as a function of the applied stress, of the strain and of the temperature. Both biomedical devices are submitted to surface analysis to control the interface with the biological environment in which they will be immersed.

Micron-size particles emission from bioceramics induced by pulsed laser deposition.

Pulsed laser deposition of hydroxyapatite is applied to cover titanium medical prosthesis. Laser irradiation of ceramics by power-pulsed ruby laser produces high velocity micron-size particles emission with a narrow ejection plume directed normally to the target surface. Photoemitted particles are deposited on a metal surface at 400 degrees C to obtain a granular film, stoichiometric, polycrystalline, and very adherent to the substrate. Deposited films are highly biocompatible and may be used to induce osteointegration processes of the implanted prosthesis with the bone tissues. The comparison between laser and plasma spray depositions of bioceramics is discussed.

Microfilters by laser processing of bio-polymers.

Thin films of bio-polymers, such as polymethylmetacrylate, polytetrafluoroethylene, polyethylene-terephthalate and polyimide, are efficiently etched in air by UV laser pulses. A different sharp laser fluence threshold for significant etching is measured for each polymer. The thresholds are correlated to the chemical structure and to the wavelength-dependent absorption coefficient of the irradiated polymer. The polymers, having low absorption coefficients, show thresholds of the order of some J/cm2, about one magnitude higher than polymers having high absorption coefficients. Measurements on the polymer etching rates, in terms of removed molecules per eV at the used 347 nm wavelength, and a discussion on the laser-polymer interaction are presented. An interesting application of the laser ablation process to bio-polymers, concerning the ability to realize microfilters for the bio-medical field by irradiating the polymer surface through a perforated metal mask, is discussed.

Study of hardness and roughness modification in explanted joint components.

The significant wear of the UHMWPE bearings of explanted knee prostheses is produced mainly by micrometric debris ("third-body" wear) that diffuse toward the mobile metal-polymer interface. Here debris is crushed during the movement producing scratches in the metal and in the polymeric surfaces. Mechanical stress and the biological effects change the physical polymeric properties. In order to evaluate the area of UHMWE bearings submitted to high load stresses, in this work physical investigations are performed on the explanted knee prosthesis. Particularly, the roughness profile analysis (RPA) and the micro-hardness measurements (MHM) resulted suitable for the localisation of the mechanical and biological wear area. In the stressed zone, surface treatments could be applied in order to improve the mechanical resistance of the polymeric material. Particularly, the ion implantation with heavy ions is proposed to enhance the polymeric wear resistance. The Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometry (EDX) and Infrared absorption spectroscopy (FTIR) techniques were also applied and results discussed.

Improvements in bio-mechanical adhesion of screws used in medical field: first application in spinal surgery.

Metallic screws are becoming more and more useful to join bones or for prosthesis support in orthopaedic and dental surgery. High biocompatible materials such as titanium alloys and hydroxyapatite ceramics are making possible the realization of stable fixation devices utilizable in load-bearing applications. The mechanical and biological anchorage of metallic screws to the bone depends on many factors: mechanical screws-bone thread matching, use of cements between bone and screw, chemical-physical treatments of screw surface, use of screw coverage films based on osteointegrating ceramics or active bioglasses, use of porous coverage films to induce bone ingrowth into the pore, and so on. The first step of the research, the aim of the present paper, is the comparison among screws of different shapes and geometric characteristics in order to find the best macromechanical system versus the different load conditions. Static and dynamic tests are applied to the screws mounted on segments of pig spine, in order to measure the mechanical characteristics of the system under tension (pull-out), bending on the principal planes along the axis of the screw and fatigue loads. Physical analysis, obtained using energetic charged particles, such as SEM, RBS, and AES, are used to characterize the screw surface compositions and morphology.

Auger and pixe microanalysis of intrauterine devices (IUDs).

Auger Emission Spectroscopy (AES) and Particle Induced X-ray Emission (PIXE) analysis were employed in a study on the calcification and oxidation processes of the copper wires used in Intra-Uterine Device (IUDs) contraceptives. A strong copper release (approximately 50 micrograms/day) has been observed in the first year of IUDS application during the high device antifertility effect. The copper release is reduced with the IUD-use time, because of the calcification process on the surface by organic liquids. This effect produces a drastic reduction in the contraceptive efficiency, and a new IUDs replacement is needed after about 2 years of use. Auger, X-ray spectrometry and scanning electron microscopy (SEM) have been used to investigate the lifetime and efficiency of IUDS in order to understand the surface modification of copper wire during its permanence in the intrauterine environment.

PIP: Auger Emission Spectroscopy (AES) and Particle Induced X-ray Emission (PIXE) analysis were employed in a study on the calcification and oxidation processes of the copper wires used in IUDs. A strong copper release (approximately 50 mcg/day) was observed in the 1st year of IUD use, during the high device antifertility effect. Copper release is reduced over time due to the calcification process on the surface by organic liquids. This effect produces a drastic reduction in contraceptive efficiency and new IUDs are necessary after 2 years of use. Auger, x-ray spectrometry, and scanning electron microscopy have been used to investigate IUD lifetime and efficiency in order to understand the surface modifications of copper wire during its performance in the intrauterine environment. (author's modified).

Enhancement of anaerobic treatability of olive oil mill effluents by addition of Ca(OH)2 and bentonite without intermediate solid/liquid separation.

Previous work on the anaerobic treatment of olive oil mill effluents (OME) have shown: (a) lipids, even if more easily degraded than phenols, were potentially capable of inhibiting methanogenesis more strongly; (b) a pretreatment based on addition of Ca(OH)2 and bentonite removed lipids almost quantitatively; (c) preliminary biotreatability tests performed on the pretreated OME showed high bioconversion into methane at very low dilutions ratios, especially when the mixture (OME, Ca(OH)2 and bentonite) was fed to the biological treatment without providing an intermediate phase separation. This paper was directed towards two main aims: (a) to optimize pretreatment: the best results in terms of methane production were obtained by addition of Ca(OH)2 up to pH 6.5 and of 10 g L-1 of bentonite; (b) to evaluate the enhancement of anaerobic treatability of OME pretreated under optimized conditions in a lab-scale continuous methanogenic reactor fed with the substrate without intermediate solid/liquid separation: very satisfactory performances were obtained (at an organic load of 8.2 kg COD m-3 d-1 and at a dilution ratio of 1:1.5 total COD removal was 91%, biogas production was 0.80 g CH4 (as COD)/g tot. COD, lipids removal was 98%, phenols removal was 63%). The results confirm the double role played by bentonite (adsorption of the inhibiting substances and release of the adsorbed biodegradable matter in the methanogenic reactor).

[Boron in dental hard tissues studied by 11B(p,alpha)8Be nuclear reaction]. / Il boro nei tessuti duri dentari studiato con la reazione nucleare 11B(p,alpha)8Be.

Boron's low atomic number and low concentration make its measurement in hard dental tissues difficult. Using nuclear reaction, the 11B(p,alpha)8Be*, enamel, dentine and radicular cement of 18 dental elements, ten healthy and eight decayed teeth, both permanent and deciduous were studied. The highest Boron concentrations were found in the two most superficial microns of the vestibular enamel in non-decayed incisors, particularly deciduous ones. Premolar and molar teeth showed lower Boron concentrations than frontal ones, decayed teeth revealed hardly any Boron. In confirmation of the prevailing exogenous contribution of this karyostatic trace element, on average, Boron concentrations were 2.5 times as high as dentine and 10 times as high as cement.