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Bullous pemphigoid is the most common autoimmune bullous dermatosis. In recent years several studies have tried to identify the main factors of the disease related with an increased risk of death. The aim of this multicenter Italian study was to assess the risk score of death considering epidemiologic, clinical, immunological, and therapeutic factors in a cohort of patients affected by bullous pemphigoid and try to identify the cumulative survival up to 120 months.We retrospectively reviewed the medical records of patients with bullous pemphigoid who were diagnosed between 2005 and 2020 in the 12 Italian centers. Data collected included sex, age at the time of diagnosis, laboratory findings, severity of disease, time at death/censoring, treatment, and multimorbidity.A total of 572 patients were included in the study. The crude mortality rate was 20.6%, with an incidence mortality rate of 5.9 × 100 person/year. The mortality rate at 1, 3, 5, and 10 years was 3.2%, 18.2%, 27.4% and 51.9%, respectively. Multivariate model results showed that the risk of death was significantly higher in patients older than 78 years, in presence of multimorbidity, anti-BP180 autoantibodies72 U/mL, or anti-BP230 3 U/mL at diagnosis. The variables jointly included provided an accuracy (Harrel's Index) of 77% for predicting mortality.This study represents the first nationwide Italian study to have retrospectively investigated the mortality rates and prognostic factors in patients with bullous pemphigoid. A novel finding emerged in our study is that a risk prediction rule based on simple risk factors (age, multimorbidity, steroid-sparing drugs, prednisone use, and disease severity) jointly considered with two biomarkers routinely measured in clinical practice (anti-BP230 and anti-BP180 autoantibodies) provided about 80% accuracy for predicting mortality in large series of patients with this disease.

Guselkumab is a fully human monoclonal IgG1 antibody which, by selectively binding to the p19 subunit of IL-23, prevents it from binding to the IL-23 receptor on the cell surfaces. To date, no prospective data are available on the efficacy and safety of this drug in everyday clinical practice in patients with psoriasis (PSO).This is a longitudinal, single arm, real-world, prospective study to investigate the effect of Guselkumab on PSO and quality of life (DLQI) in 44 PSO patients. Outcomes were PASI, BSA, DLQI at 3 and 6 months.The longitudinal analysis showed that PASI improved from a median value of 24.1 at baseline to 2.0 at 6-months and this was also true for BSA (from 23.0 to 2.0) and DLQI (from 24.0 to 2.5) (all p0.001). At 6-months, PASI75, PASI90 and PASI100 were 95.5%, 59.1% and 16%, respectively. The PSO improvement related with the increase of DLQI (∆PASI vs. ∆DLQI, r=0.77, p0.001). No clinically relevant adverse events were observed.This study demonstrates the effectiveness and safety of Guselkumab on PSO in real world and shows that the reduction of PSO severity due to the drug is directly related with the improvement of quality of life in this patient population.

We propose a Near Infra Red photon emitting 4H-SiC compact vertical pn diode. The “as fabricated” diode exhibits a strong visible emission at 500 nm associated with the intrinsic and/or processing induced D1 centers in the semiconductor. Thanks to opportune He+ ion irradiation, we are able to obtain color centers in the junction region responsible for photon emission around 900 nm while simultaneously quenching unwanted visible emission. Electro-optical investigation was conducted by Electro-Luminescence measurements in the 300 nm −1100 nm range and by Emission Microscopy, both with pumping a current between of 0.1 and 2 mA. The proportionality of the emission intensity to the pumping current opens the interesting perspective of engineering the concentration of defects with the aim of obtaining single defects and thus single photon source devices. This is of considerable interest in low-power proximity sensors for consumer, industrial, automotive and telecommunications applications.

This paper presents the results of the electrical characterization of a silicon Low Voltage Trench Gate charged-coupled Power MOSFET under external uniaxial mechanical stress. The stress was imposed by a 3 Point Bending system during electrical measurement of the oxide leakage current.

The almost universal availability of electronic connectivity, web software, and portable devices is bringing about a major revolution: information of all kinds is rapidly becoming accessible to everyone, transforming social, economic and cultural life practically everywhere in the world. Internet technologies represent an unprecedented and extraordinary two-way channel of communication between producers and users of data. For this reason, the web is widely recognized as an asset capable of achieving the fundamental goal of transparency of information and of data products, in line with the growing demand for transparency of all goods that are produced with public money. This chapter describes the “Open Universe”, an initiative proposed to the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) with the objective of stimulating a dramatic increase in the availability and usability of space science data, extending the potential of scientific discovery to new participants in all parts of the world.

In this paper, we present the extensive characterization of large-area silicon carbide-based UV sensors candidate for outdoors spectroscopic applications of gas or liquid. The proposed SiC Schottky devices exhibit a dark current density of 0.12 nA/cm(2) at 15 V, a 0.12-A/W responsivity at 300 nm, optimal visible blindness, and a switching time of similar to 190 ns. Effects of temperature on the sensor performance, of crucial interest for outdoors applications, are also examined in the range from -20 degrees C to 90 degrees C.

We propose a solid state-based spectroscopy compact apparatus for monitoring environmental SO2, particularly suitable, for example, for volcanic applications. A prototype system, with a 170-mm long optical path, was assembled and tested using a commercial LED operating at 285 nm and a large area silicon carbide. The laboratory tests were carried out using calibrated quartz cuvettes containing SO2 at fixed concentrations and standard SO2 gas with 20% of O2 and complemented with N2 dry gas to fill the optical system chamber. Optical signal attenuations in the chemically interactive chamber follow the Beer-Lambert-Bouguer law in all the performed tests and a 0.16 ppm/pA nominal chemical resolution and ± 0.8 ppm concentration error were obtained from the experimental data for the current prototype.

This paper reports the electrooptical characteristics of ultraviolet light-sensitive 4H-SiC p $^{+} $ -n junction photodiodes obtained by aluminium (Al) ion implantation on low-doped n-type epilayers. A low dark current density ( $ at $-$ 100 V) was measured on 1- $\hbox{mm}^{2}$ area devices up to 90 $^{\circ}\hbox{C} $ . A peak responsivity of 0.11 A/W at 280 nm corresponding to a quantum efficiency of about 50% and a visible blindness $>\ 10^{3} $ were demonstrated. The absence of optically active defects and nitrogen donor–aluminum acceptor pair recombination centers was monitored by optical measurements in the visible range.

SiC detectors based on Schottky diodes with an interdigit or a thin continuous front electrode are employed for the characterization of plasma generated by low intensity (1010 W/cm2) laser were photons, electrons and keV ions are produced. The exposure to plasma induces the formation on the detector surface of debris and/or micrometric clusters of the target material whose concentration increases with the number of laser shots, leading to the formation of nanometric film after long exposure time. The presence of this deposit strongly modifies the electrical characteristics, the optical response and ion detection properties of the detectors. In particular, we monitored the current-voltage characteristics of SiC devices and we observed an increase of the leakage current, a decrease of the Schottky barrier height and a reduction of the photon detection efficiency in the UV region, by increasing the number of plasma shots. The modification in the electrical and optical properties have been observed after a high number of laser shots, and a simple cleaning procedure allows to remove the surface deposit and, in the case of the continuous front electrode device, to restore the initial electro-optical device performances. The differences related to geometry of the front electrode are discussed.

This paper reports the electrooptical characteristics of ultraviolet light-sensitive 4H-SiC p+-n junction photodiodes obtained by aluminium (Al) ion implantation on low-doped n-type epilayers. A low dark current density (2 at -100 V) was measured on 1-mm2 area devices up to 90 °C. A peak responsivity of 0.11 A/W at 280 nm corresponding to a quantum efficiency of about 50% and a visible blindness> 103 were demonstrated. The absence of optically active defects and nitrogen donor-aluminum acceptor pair recombination centers was monitored by optical measurements in the visible range.

Multidirectional SPEG (Solid Phase Epitaxial Growth) of silicon has been investigated in micro and nanoamorphous structures generated on a crystalline substrate by a nano-sized ion beam, Gaussian shaped and with a standard deviation of about 5 nm. The 20 keV Ga+ ions were implanted at a fluence of 5 × 1014 ions cm−2 in a bulk Si(1 0 0) single crystal. Two structures were used for the implants: circular regions of 100 nm and 1 μm diameters respectively and straight lines 10 nm in width and few microns in length along (1 0 0) or (1 1 0) directions. The lateral spread of ions has been taken into account in the damage estimation. Transmission Electron Microscopy indicates that the structures are made of an amorphous core surrounded by a defective and filamentary shell. The recovery of the damaged outer regions promptly occurs during the early stages of the thermal treatment at 500–600 °C for all the structures. By prolonging annealing time, re-crystallization of the amorphous cores is achieved too by the movement of the underneath crystal–amorphous interface. The re-growth is almost defects free when the contribution of the crystalline seed below the structures is present, defective and twin mediated if it misses as in the thinnest regions of the specimen.

Electrically trimmable resistors have been manufactured using the phase change alloy Ge 2 Sb 2 Te 5 . High resistivity values (about 1 mΩ cm) and almost zero temperature coefficient of resistance (TCR) have been obtained using resistors with hcp phase of metallic behavior and converting a small region of the film into the fcc phase, with opposite trend of resistance versus temperature. The conversion into the fcc phase has been obtained through two electric pulses, the first for melting and quenching in the amorphous phase and the second for crystallization in the fcc semiconductive phase. Theoretical considerations together with the experimental measurements allow to determine the proper ratio between the metallic and the semiconductive phase required to obtain a target resistance and temperature dependence. For example, a resistor almost independent on the temperature can be achieved by electrical trimming, increasing the resistance of about 10% of the initial value. The resistor layout has been optimized through electro-thermal simulations, to achieve the modification of the resistors structure only in a confined region. Experimental results confirm the theoretical expectations and demonstrate that phase change materials can be effectively used to obtain reversible electrically trimmable resistors with adjustable TCR.

We report on the structure and performance of 4H-SiC p(+)-n APDs fabricated in a fully planar technology. A dark current density lower than 10 nA/cm(2) at 30-V reverse bias and a breakdown voltage of 88 V were observed. A gain as high as 105 was measured at 94-V reverse bias, confirming the avalanche multiplication working condition. The maximum responsivity value was measured at 270 nm, increasing from 0.06 A/W (QE = 29%) at 0-V bias to 0.10 A/W ( QE of about 45%) at 30-V reverse bias.

Micro- and nano-electromechanical systems (MEMS and NEMS) fabricated in 3 C-SiC are receiving particular attention thanks to the material physical properties: its wide band gap (2.3 eV), its ability to operate at high temperatures, its mechanical strength and its inertness to the exposure in corrosive environments. However, high residual stress (which is normally generated during the hetero-epitaxial growth process) makes the use of 3 C-SiC in Si-based MEMS fabrication techniques very limited leading to a failure of micro-machined/sensor structures. In this paper, micro-Raman characterizations and finite-element modeling (FEM) of microstructures realized on poly and single-crystal (100) 3 C-SiC/Si films are performed. Transverse optical (TO) Raman mode analysis reveals the stress relaxation on the free standing structure (796.5 cm−1) respect to the stressed unreleased region (795.7 cm−1). Also, microstructures as cantilever, bridge and planar rotating probe show an intense stress field located around the undercut region. Here, the TO Raman mode undergoes an intense shift, up to 2 cm−1, ascribed to the modification of the Raman stress tensor. Indeed, the generalized axial regime, described by diagonal components of the Raman stress tensor, cannot be applied in this region. Raman maps analysis and FEM simulations show the ‘activation’ of the shear stress, i.e. non-diagonal components of the stress tensor. The stress-Raman modes shift correlation, in the case of fully non-diagonal stress tensors, has been investigated. The aim of future works will be to minimize the stress field generation and the defects density within the epitaxial layer. Copyright © 2012 John Wiley & Sons, Ltd.

SiC is a candidate material for microelectromechanical and nanoelectromechanical systems, but the high residual stress created during the film grow limits the development of the material for these applications. To understand the stress relaxation mechanism in hetero-epitaxial 3C-SiC films, different micromachined free-standing structures have been realized. In this paper, assisted by finite-element method (FEM), a micromachined planar rotating probe was developed for residual stress analysis to split the stress into the following two components: 1) the gradient residual stress (σ1) related to the film defects and 2) the uniform stress (σ0) related to the substrate. Transmission electron microscopy characterization studies about the defect formation and the defect evolution as a function of thickness on 3C-SiC on the Si substrate revealed the problems due to the incorrect linear stress approximation in a heteroepitaxial thin film. With FEM, an exponential approximation of the stress relationship was studied, yielding a better fit with the experimental data. This paper shows that the new approximation of the total residual stress function reduces the actual disagreement between experimental and simulation data.

The growing interest in natural medicine makes it necessary to study plant properties as well as their possible secondary effects. In recent years the toxic effects of many medicinal plants on the preimplantational mouse embryo development have been studied. Many of them produce malformations and alterations in the embryonic development. Ruta graveolens "ruda", Origanum vulgare "oregano" and Persea americana "palta" are used in rural areas to menstrual colic and to provoke abortion (estrella, 1995). This study is aimed at assessing "in vivd'the effect of extracts of "oregano", "ruda" and "palta" to 20% on the morphology and growth of preimplantational mouse embryos.

The small-angle neutron scattering (SANS) of some aqueous solutions of short-chain amphiphiles (glycols, diglycols, diols) has been measured as a function of concentration and temperature. The analysis of the spectra in terms of the Teubner-Strey phenomenological formula indicates that, on increasing the concentration of the amphiphile, the structure of all these systems evolves in a similar way, i.e. a transition from disordered structures toward correlated aggregates (microstructures). The transition is depressed by increasing the temperature.

Silicon Carbide (SiC) is the most promising material for the fabrication of a new category of sensors and devices, to be used in very hostile environments (height temperature, corrosive ambient, presence of radiation ...). The fabrication of Silicon Carbide sensors requires new processes able to realize microstructures on bulk material or on the silicon carbide surface. A very promising method to create microstructures in SiC is the electrochemical etch in aqueous solution of hydrofluoric acid. In this paper the bulk micromachining of SiC substrate and the structural and electrical characterization of porous silicon carbide formation are reported. These results were used to create a novel method for the bidimensional pattering of SiC substrate. In particular a novel Si-based hard mask to transfer the design onto the SiC substrate was used. The hard mask is formed by a sandwich structures made by subsequent deposition of VAPOX, POLY Si, SiO2.

The numerical simulation of the etched surface evolution is applied to the selective (chemical and electrochemical) etching dopant delineation technique. The analysis of the etched sample section, obtained by means of transmission electron microscopy, is performed using a 3D simulation code based on the level set method for evolving surfaces. The correlation between the etched profile and the total dopant distribution is inferred, assuming that a functional relationship F=F{ρ(r)} occurs between the local dopant density ρ(r) and the local etch rate F(r). The reliability of the etch rate expression, derived by the theory of the charge transport in the solution–semiconductor interface, has been demonstrated by using the direct electrical simulation of the current flow during the etching process. The calibration of the technique consists in the fit of the parameters in the F=F{ρ(r)} relation depending only on the external conditions (bias potential, chemical moisture). The fitting has been performed, using reference profiles, at fixed optimal conditions. The measurement of the 2D dopant density map is based on the cross graphical comparisons, performed automatically by the computational tool, between TEM images of the eroded zone and the simulations of the etched surface, obtained using trial dopant distributions.

The galvanic displacement deposition of silver on H-terminated Si (100) in the time scale of seconds is instantaneous and characterized by a cluster density of 10(11)-10(12) cm(-2). The amount of deposited Ag follows a t(1/2) dependence in agreement with a Cottrell diffusion limited mechanism. At the same time, during the deposition, the cluster density reduces by a factor 5. This behavior is in contrast with the assumption of immobile clusters. We show in the present work that coalescence and aggregation occur also in the samples immersed in the diluted hydrofluoric acid (HF) solution without the presence of Ag(+). Clusters agglomerate according to a process of dynamic coalescence, typical of colloids, followed by atomic redistribution at the contact regions with the generation of multiple internal twins and stacking-faults. The normalized size distributions in terms of r/rmean follow also the prediction of the Smoluchowski ripening mechanism. No variation of the cluster density occurs for samples immersed in pure H2O solution. The different behavior might be associated to the strong attraction of clusters to oxide-terminated Si surface in presence of water. The silver clusters are instead weakly bound to hydrophobic H-terminated Si in presence of HF. HF causes then the detachment of clusters and a random movement on the silicon surface with mobility of about 10(-13) cm(2)/s. Attractive interaction (probably van der Waals) among particles promotes coarsening.

The structural transformations occurring in Ge2Sb2Te5 films heated at temperature up to 400 °C, and under hydrostatic pressure up to 12 GPa, have been investigated through in-situ X ray diffraction measurements. The adopted experimental conditions are close to those experienced by the phase change material during the SET (crystallization)/RESET (amorphization) processes in a nonvolatile memory device. The compression enhances the thermal stability of the amorphous phase, which remains stable up to 180 °C at 8 GPa and to 230 °C at 12 GPa. The structure of the crystalline phases is also modified, with the formation of a CsCl-type structure instead of rock-salt and of a GeS-type structure at the temperature at which usually the trigonal stable phase is formed. Overall, the stability of the stable phase appears to be more affected by the compression. We argue that the presence of weak bonds associated to the van der Waals gaps is a determining factor for the observed reduced stability.

The electroless deposition of Gold on H-terminated Si(100) substrates has been investigated with 2.0 MeV He+ ions Rutherford Backscattering Spectrometry (RBS) and Transmission Electron Microscopy (TEM). A large number of Gold nanoparticles (in excess of 1011 cm−2) was instantaneously generated on the silicon substrate by immersion in a solution containing 1mM KAuCl4 and 4.8M HF. The gold atomic surface concentration, as given by the RBS measurements, increases with the square root of the immersion time from 1 to 5s. The experimental data are fitted with a diffusion coefficient for the metallic ions in the solution of 1.45 × 10−5 cm2 s−1. At longer deposition times, instead, the Au ions flux is constant, with a static boundary layer of few hundred microns thick in agreements with one dimensional diffusion limited mechanism.

In this study we report on a patient affected by a brain migration disorder and a T-cell activation deficiency presumably inherited as an autosomal recessive trait. The immunological evaluation revealed that the mitogen stimulation failed to induce a proper up-regulation of membrane expression of T-cell activation markers, and cell proliferation. This functional impairment was associated with abnormalities of the signal transduction process that follows T-cell receptor stimulation. A constitutive hyperphosphorylation of the Fyn tyrosine kinase was documented. This is the first report on a T-cell signaling abnormality associated with a developmental brain disorder. Whether the alteration of Fyn, which plays a role in both neurological and immunological systems, is responsible for either disorder remains to be elucidated.

By means of density, dielectric spectroscopy and sound velocity measurements we perform a systematic study on the polyoxyethylene C12E6 nonionic surfactant solutions as a function of temperature and concentration. Both density and sound velocity data, at about 34°C, coincide with the value obtained for pure water. Above this temperature the density is lower than the water density whereas below, it is greater, the opposite happens for the compressibility. Combining results from these different techniques we attempt a detailed description of the evolution of the micellar interfacial properties with temperature. It is well known that nonionic surfactant solutions dehydrate with growing temperature. Our results indicate that this process is associated with a continuous change in the polymer conformation and in the local density of the micellar interface.

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We present small-angle neutron scattered intensity measurements for some binary and ternary aqueous solutions of 2-butoxyethanol and C 6 E 3 (a nonionic surfactant) at 4, 20 and 40°C. The spectra were analysed in terms of two models which take into account the simultaneous presence of aggregates and concentration fluctuactions. The analysis for the binary solutions focuses on the similarities and differences existing in the aggregates of the alcohol and the surfactant. We determine the various parameters of the aggregates, such as size, hydration water and aggregation number. The analysis performed for the ternary solutions shows the role of different amounts of alcohol added to solutions of fixed surfactant concentrations.

Electroless silver deposition (for 1–100s) has been simultaneously performed on (100) and (111) planes of macro and micro patterned silicon, fabricated using optical lithography and anisotropic etching with alkaline solution. Metal clusters formation occurs preferentially on the upper edge region separating the two main planes. Their density and mean size are higher on the (100) plane. Similar experiments performed on same patterned samples but with the surface amorphized by ion implantation elucidated the role played by the preferential mass transport caused by the pattern geometry. For the micro-sized pyramidal holes, the non uniform surface distribution of metal clusters is enhanced. The metal deposition occurs mainly on the (100) top strips surrounding the pyramids. The subsequent preferential oxidation of silicon under the metallic clusters gives rise to nanowires of (100) and (111) orientation in the macro and to nanopillars in the micro patterns respectively. Nanowire’s tips are preferentially sites for metal deposition as shown after re-immersion in the plating solution. Samples with contiguous one dimensional nanostructures of different orientation could be used for the study of transport properties’ anisotropy. The formation of metal tips on top of the nanostructures might be of relevance in the field of metal-semiconductor contacts. © 2013 The Electrochemical Society. [DOI: 10.1149/2.002311jss] All rights reserved.

The electrical properties of amorphous GeTe films deposited at room temperature, ion implanted, and melt-quenched have been studied. The activation energy for the mobility gap varies from 0.64, in the melt-quenched, to 0.74 eV, in the as deposited film. In all the types of amorphous, pre-annealing at temperatures below crystallization induces relaxation, increasing the resistance and the mobility gap. Pre-annealing also reduces the nucleation rate for crystallization by a factor up to 4. A model is proposed, describing the competing processes of structural relaxation and crystallization, as governed by a population of sub-critical nuclei formed by medium range ordered regions.

A nano-sized ion beam apparatus has been used as maskless lithography to implant 20 keV Ga+ ions into a 26 nm thick silicon crystalline film on insulator. The ion beam, with about 5 nm standard deviation, delivered few hundred ions during a single shot. Circular areas with nominal diameter of 20 or 50 nm were irradiated to a fluence of 5 x 10(14)/cm(2). Transmission electron microscopy evidenced that the damaged regions are characterized by an irregular contour with many disordered filaments. Damage extends across the layer thickness and fast Fourier transform analysis indicates that implantation causes the amorphization of a region which extends beyond the nominal diameter. In situ annealing experiments demonstrated that the disordered filamentary regions disappear in the 250-450 degrees C temperature range and the interfaces with the surrounding crystalline regions sharpen. A temperature as high as 600 degrees C is required to fully re-crystallize the amorphous core of the implanted dots. Reordering occurs by multi-orientation lateral solid-phase epitaxial growth and the breaking of (111) and (101) interfaces, due to the formation of twins, triggers a fast crystallization kinetics. Rapid thermal annealing (890 degrees C-10 s) completely crystallizes the amorphous regions, twins are absent and small cluster of defects remains instead. Preliminary scanning capacitance measurements indicate that the implanted atoms, after crystallization, are electrically active. The implant method is then a viable processing step for the doping of non-bulk fully depleted ultra-thin-body MOSFET.

We tested a new biosensor for urea monitoring in the ultrafiltrate during PFD in a group of 5 hemodialyzed stable patients. The inspection of the UF-urea profile reflects the dynamical changes of the plasma urea concentration during diffusive dialysis and allows the fitting of the main mathematical models of urea kinetics. The biosensor efficiency was 98.4% on average (SD: 1.5%) at Uf fluxes varying from 45 to 55 ml/min (mean: 51 ml/min; SD: 3.2) and at Uf-urea concentrations varying from 23 to 165 mg/dl. The mean difference between Uf-urea determined by the laboratory method and Uf-urea assayed by the biosensor was -1.07 mg/dl and the 95% confidence interval ranged from -2.01 to 0.13 mg/dl. The mean difference between laboratory plasma urea and Uf-urea from the biosensor was on average -1.9 mg/dl and the estimated limits of agreement with a confidence of 95% were -3.16 and 0.64 mg/dl. Comparison between kinetic models and experimental profiles of plasma urea decrease, evaluations of recirculation and post-dialytic rebound, the role of Kt/V on-line during dialysis were the preliminary clinical applications of this biosensor.

Eleven bicarbonate hemodialyses (HD) of 6 patients under constant ultrafiltration were continuously monitored with an optical Hb-meter, considered to be a marker of blood volume (BV) changes. A theoretical model was fed experimental data for prediction of blood volume and estimation of vascular parameters, and a time course of rate of refilling was extrapolated. The adequacy of the model was very good for the time course of BV prediction (r2 = 0.85-0.95, n = 11) and for plasma protein concentration (r2 = 0.83-0.86, n = 2). Parameters estimated included (mean-DS): filtration coefficient (Cf) = 0.22 (0.16) dl/min*mmHg, transcapillary hydrostatic pressure (DP) = 17.80 (3.44) mmHg and protein concentration of the refilling fluid (Cref) = 0.45 (0.30) g/dl. In conclusion our study has shown that the model chosen fits the observed BV profile well in all cases, thus the Hb data series can be used for BV dynamic modeling and for estimation of vascular parameters.

As an aid toward a better understanding of data retention of phase change memories we have analyzed in situ by Transmission Electron Microscopy the crystallization of amorphous Ge2Sb2Te5 dots of 100 nm and 20 nm diameter, embedded in the hexagonal crystalline phase. Amorphization was obtained by 40 keV Ge+ irradiation at LN2 through Electron Beam Lithography masked pattern. At 75 degrees C/90 degrees C, crystallization in 100 nm dots occurs by grain growth from the surrounding crystalline material, with an initial growth velocity of 0.6 (6.4) pm/s followed by a slower rate of 0.14 (1.7) pm/s. At 75 degrees C, the 20 nm amorphous regions disappear just after two hours of annealing.

Density, ultrasonic velocity, viscosity, and electrical conductance of water/AOT/n-heptane microemulsions as a function of the volume fraction of the dispersed phase (0

We present a detailed experimental investigation of the simultaneous selective electrochemical etch of arsenic and boron doped regions in silicon. We used different chemical solutions containing HF and/or HCl. The etching selectivity is evaluated in calibration samples, implanted with As and/or B, by comparing the topography of the etched surface, analyzed by transmission electron microscopy, with the carrier concentration profiles, measured by spreading resistance profiling. We demonstrate the capability of tuning the selectivity of the two different dopant species by changing the chemical solution used in the electrochemical cell. We also present an application demonstrating the high sensitivity that we achieve in delineating weakly boron-doped regions in a silicon device.

We have studied the shear viscosity in a water-butoxyethanol (${\mathrm{C}}_{4}$Et) mixture as a function of temperature and concentration. The critical and off-critical mixtures have been studied over a very large T range, and the results are compared with recent light-scattering data confirming the amphiphilic character of the ethoxylated alcohol molecule that originates micellar structures. On this basis the data are discussed, considering the system as a colloidal dispersion of interacting micellar particles, where the attractive interaction plays the main role. In these terms the data near and below the lower critical solution temperature ${\mathit{T}}_{\mathit{c}}$ are well accounted for by the current mode-coupling theory of critical binary fluids. For low temperatures (T\ensuremath{\le}20 \ifmmode^\circ\else\textdegree\fi{}C) where large clusters are present, the \ensuremath{\eta} data are explained by considering the fundamental role of the attractive interaction effects among the dispersed micelles and using in this respect a two-fluid model, a micelle system plus an inert background.

Small‐angle neutron scattering (SANS) measurements have been performed in heavy water solutions of 2‐butoxyethanol as a function of concentration and temperature. The results indicate that there exist some alcohol aggregation above a narrow concentration range (x=0.015–0.02, where x is the alcohol molar fraction) and the size of the aggregates increases with temperature taking a maximum value at a composition close to the critical concentration. The analysis of the size and of the absolute scattered intensity at q=0(I0) in terms of a microscopic model of aggregation, as well as the indications from other experiments, suggest that these aggregates are micelle‐like structures.

The ultrasonic absorption in water/sodium bis(2‐ethylhexyl) sulfosuccinate (AOT)/n‐heptane system has been measured at 25 °C, as a function of the water/AOT molar ratio (X) and of the volume fraction (φ) of the micellar phase. The ultrasonic spectra have been found strongly dependent on φ and nearly independent on X. In particular, as φ increases, ultrasonic dynamics shifts from a single to a distribution of relaxation times with occurrence of viscoelastic effects. Such findings have been correlated to the increased connectivity of the micellar network.