Biomedical subjects
Publications and source records attributed to P Bruno.
We present a novel mechanism of nanostructure growth based on quantum confinement of surface-state electrons. Ab initio calculations and the kinetic Monte Carlo simulations reveal the phenomenon of confinement-induced adatom self-organization in quantum corrals. Our studies indicate that new atomic-scale nanostructures can be engineered exploiting the quantum confinement of surface electrons.
Nuisance caused by odors is one of the most important problems for waste management plants. To control an odor nuisance, it must first be quantified. The analytical difficulties in odor measurements are related to the high number of volatile components (belonging to several chemical classes), above all when the concentration is lower than the detection limit of the technique used for the measurement. In this work, 2-butanone, alpha-pinene, tetrachloroethylene, dimethyldisulfide, beta-pinene, limonene, phenol and benzoic acid are determined, because they are representative of some important classes of compounds with higher odor impact. The compounds are sampled with thermal desorbable radial diffusive samplers Radiello containing Tenax cartridges. The analytical repeatability and the complete thermal desorption of the cartridges were verified for each odor compound; the relative standard deviations for repeated samples and the recovery percentage were, respectively, less than 7% and about 97% for all compounds. The measurements of the linearity of sampling showed no systematic difference according to the collection period. The comparison between the odor threshold and the limit of detection demonstrated that this method is reliable for the recognition and quantification of odor compounds, allowing Public Administration to impose legal limits and the control agencies to verify them.
It is shown that, by utilizing spin-selective quantum interference, the spin polarization of nanostructures deposited on a magnetic substrate with a surface state can be strongly modulated locally and energetically by an appropriate structural design. This finding is deduced from state-of-the-art ab initio calculations and interpreted within an analytical model. We present results for hexagonal Cu corrals and mesoscopic triangular Co islands on Co-covered Cu(111). These systems are experimentally feasible, and the effect should be detectable with current technology.
We present x-ray diffraction experiments and multiple-scattering calculations on the structure and transport properties of a Fe/MgO/Fe(001) magnetic tunnel junction (MTJ). Coherent growth of the top Fe electrode on the MgO spacer is observed only for Fe deposition in ambient oxygen atmosphere leading to a coherent and symmetric MTJ structure characterized by FeO layers at both interfaces. This goes in parallel with calculations indicating large positive tunnel magnetoresistance (TMR) values in such symmetric junctions. The results have important implications for achieving giant TMR values.
The state of the art ab initio calculations of quantum mirages, the spin polarization of surface-state electrons, and the exchange interaction between magnetic adatoms in Cu and Co corrals on Cu(111) are presented. We find that the spin polarization of the surface-state electrons caused by magnetic adatoms can be projected to a remote location and can be strongly enhanced in corrals, compared to an open surface. Our studies give clear evidence that quantum corrals could permit one to tailor the exchange interaction between magnetic adatoms at large separations.
OBJECTIVE: To compare the prevalence rates of nasopharyngeal carriage of Streptococcus pneumoniae (SP) and of SP with diminished susceptibility to penicillin (PDSP) according to two types of day care, i.e. children in group day-care (GDC) and those attended by a child minder (CM) before and after the implementation of a local public health campaign promoting prudent antibiotic use in pediatric care. METHODS: Two cross sectional studies were conducted in each care setting in 1999, 2000 and 2002, on a random sample of children. RESULTS: Initial prevalence rates for SP before the campaign were 54% in the GDC group in 1999 and 34% in the CM group in 2000, with 63% and 52% PDSP, respectively. In 2002 theses rates were 58 and 33% for SP (p<10(-5)) and 64 and 53% for PDSP, respectively. The proportion of children who received antibiotics decreased in both care settings between the two surveys, from 47 to 37% in the CM group (p=0.03) and from 60 to 51% in the GDC group (p=0.03). CONCLUSION: These results are in favor of the child minder setting and also illustrate the positive impact of a public health campaign on the frequency of antibiotic prescriptions.
We discuss the anomalous Hall effect in a two-dimensional electron gas subject to a spatially varying magnetization. This topological Hall effect does not require any spin-orbit coupling and arises solely from Berry phase acquired by an electron moving in a smoothly varying magnetization. We propose an experiment with a structure containing 2D electrons or holes of diluted magnetic semiconductor subject to the stray field of a lattice of magnetic nanocylinders. The striking behavior predicted for such a system (of which all relevant parameters are well known) allows one to observe unambiguously the topological Hall effect and to distinguish it from other mechanisms.
Hyperthermic Limb Perfusion (HILP) with Tumor Necrosis Factor alpha (TNFalpha) and interferon gamma (IFNgamma) was pioneered by Liénard and Lejeune in 1988. TNFalpha was empirically employed at a dosage of 3-4 mg that is ten times the systemic maximum tolerated dose (MTD). Sixteen years after its first clinical application more than 300 patients have been treated and some clarifications can be made regarding three major questions: the real role of IFNgamma, the TNFalpha dose and eligibility criteria for patient selection. A randomized phase II study has demonstrated that IFNgamma does not increase significantly the efficacy but does increase side-effects. Experimental and clinical results seem to indicate that patients with bulky melanoma disease can really benefit from TNFalpha HILP carried out with only 1 mg.
Determination of inorganic anions in waters of high salinity is one of the most difficult task in analytical chemistry. A simple column-switching method, based on an original chromatographic set-up, for the determination of nutrients (nitrate, nitrite and phosphate) in chloride rich aqueous matrices is presented. A pre-separation system (made of two in line pre-columns, Dionex AG9-HC 4 mm) connected to an analytical column (Dionex AS9-HC 4 mm) by a four way pneumatic valve, allows chloride to be eluted off into the waste and nutrients to be separated and detected by a conductimeter and/or a UV spectrophotometer. Neither chemical pre-treatment nor sample dilution are required; sample matrices presenting a large range of chloride concentrations can be investigated. Moreover by using this technology, automation for routine analysis, low analysis time and low costs can be achieved. LODs of 100, 300, 1000 microg/l for nitrate, nitrite and phosphate, respectively, have been obtained by spiking a synthetic sea water sample containing 20,000 mg/l of chloride and 3000 mg/l of sulphate. Analyte calibration curves of analytes are linear (r>0.99) in the range between the LODs and 60 mg/l. This method was applied to nutrients determination in sea water samples collected near a river outlet.
The electronic structure of thin Co nanoislands on Cu(111) has been investigated below and above the Fermi level (E(F)) by scanning tunneling spectroscopy at low temperature. Two surface related electronic states are found: a strong localized peak 0.31 eV below E(F) and a mainly unoccupied dispersive state, giving rise to quantum interference patterns of standing electron waves on the Co surface. Ab initio calculations reveal that the electronic states are spin polarized, originating from d3(z(2)-r(2))-minority and sp-majority bands, respectively.
In a joint experimental and theoretical study, we investigate the bias-voltage dependence of the tunnel magnetoresistance (TMR) through a vacuum barrier. The TMR observed by spin-polarized scanning tunneling microscopy between an amorphous magnetic tip and a Co(0001) sample is almost independent of the bias voltage at large tip-sample separations. Whereas qualitative understanding is achieved by means of the electronic surface structure of Co, the experimental findings are compared quantitatively with bias-voltage dependent first-principles calculations for ballistic tunneling. At small tip-sample separations, a pronounced minimum in the experimental TMR was found at +200 mV bias.
The "magnetic force theorem" is frequently used to compute exchange interaction parameters and adiabatic spin-wave spectra of ferromagnets. The interest of this approach is that it allows one to obtain these results from a non-self-consistent calculation of the (single-electron) band energy only, which greatly reduces the computational effort. However, as discussed by various authors, this approach entails some systematic error. Here, a "renormalized magnetic force theorem" allows us to remove this systematic error without significantly increasing the computational effort involved. For systems with one atom per unit cell, it amounts to a simple renormalization of the spin-wave spectrum.
Hyperthermic antiblastic perfusion/HAP) has been proven to be an effective neoadjuvant treatment in the treatment of advanced soft tissue limb sarcoma. As a matter of fact high percentage of limb sparing surgery, local control and functional results have been obtained wide this technique. Many antineoplastic drugs have been associated to hyperthermia by isolation limb perfusion, the aim of this paper was to describe the results obtained with doxorubicin in association to hyperthermia with or without Tumor Necrosis Factor (TNF) alpha in order to identify the most effective regimen in the multidisciplinary treatment of soft tissue limb sarcoma. A total of 106 patients have been evaluated. Three different study were performed: the first was a phase I study carried out in order to assess the maximum tolerable dose (MTD) of doxorubicin during HAP; the second was a phase II study with doxorubicin, and the third was a phase I - II study aimed at evaluating the MTD and tumor response of TNF alpha in association to doxorubicin and hyperthermia. Grade IV limb toxicity was recorded in 11 patients ( 4 in trial A, 3 in trial B, and 4 in trial C). The grade of limb reaction was strictly related to TNF dosage (> 1 mg) and temperature level (> 41.5 degrees C), therefore the best regimen is represented by temperature level not exceeding 41.5 degrees C and 1 mg of TNFalpha. The trimodality association (TNF, doxorubicin and hyperthermia) was proven to be the best regimen able to obtain a 77% of objective response (complete response, 22%) and a 77% of limb sparing in patients candidate to amputation. The results above mentioned showed the HAP with doxorubicin and TNFalpha (1 mg) is a very effective neoadjuvant treatment in the multidisciplinary treatment of advanced soft tissue limb sarcoma.
The spectrum of a photoexcited electron pair carries detailed information on the electron-electron interaction in metals. This is deduced from the results of a theoretical model presented here for the treatment of the double-photoelectron emission from surfaces. Main features in the two-particle spectra are assigned to (a) the exchange-correlation interaction, (b) the electronic band structure, (c) the photoelectron diffraction, and (d) the specific experimental setup. Comparison with experiments is made and common features and differences to the atomic case are pointed out.
The zero-point quantum fluctuations of the electromagnetic field in vacuum are known to give rise to a long-range attractive force between metal plates (Casimir effect). For ferromagnetic layers separated by vacuum, it is shown that the interplay of the Casimir effect and of the magneto-optical Kerr effect gives rise to a long-range magnetic interaction. The Casimir magnetic force is found to decay as D-1 in the limit of short distances, and as D-5 in the limit of long distances. Explicit expressions for realistic systems are given in the large- and small-distance limits. An experimental test of the Casimir magnetic interaction is proposed.
BACKGROUND: Recent studies have sparked a renewed interest in the use of autogenous radial arteries in coronary operations. Some concerns have been found about sequelae of conventional harvesting. A less invasive technique for radial artery harvesting has been proposed by others using endoscopic devices. This technique is time consuming, needs expensive instrumentation and an important learning curve. METHODS: A new less invasive approach for radial harvesting has been developed with a light assisted retractor under direct vision. A small skin incision, median in the forearm, is followed by dissection of the proper plane of the artery. A subcutaneous tunnel is created around the vessel and all the branches are ligated or clipped. The dissection of the pedicle under the skin is completed with the aid of a modified light assisted retractor, originally designed for the saphenous vein harvesting. The incision is closed after heparin reversal with a small redon as drainage. RESULTS: A preliminary serie of 15 patients have been operated with this technique. In all patients the radial artery was patent and functional at the postoperative angiography. Morbidity included only a light hematoma at the beginning of our experience. CONCLUSION: This less invasive technique for the radial artery harvesting appears to be an excellent surgical compromise between the open technique and the endoscopic procedure; it is easy to perform, the learning curve is acceptable and it offers an excellent aesthetic result.
The Mermin-Wagner theorem is strengthened so as to rule out magnetic long-range order at T > 0 in one- or two-dimensional Heisenberg and XY systems with long-range interactions decreasing as R(-alpha) with a sufficiently large exponent alpha. For oscillatory interactions, ferromagnetic long-range order at T > 0 is ruled out if alpha > or = 1(D = 1) or alpha > 5/2(D = 2). For systems with monotonically decreasing interactions, ferro- or antiferromagnetic long-range order at T > 0 is ruled out if alpha > or = 2D.
A multivariate statistical method has been applied to apportion the atmospheric pollutant concentrations measured by automatic gas analyzers placed on a mobile laboratory for air quality monitoring in Taranto (Italy). In particular, Principal Component Analysis (PCA) followed by Absolute Principal Component Scores (APCS) technique was performed to identify the number of emission sources and their contribution to measured concentrations of CO, NOx, benzene toluene m+p-Xylene (BTX). This procedure singled out two different sources that explain about 85% of collected data variance.