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A well-corroborated numerical methodology ensuring reproducibility in the modeling of pharmaceutical aerosols deposition in the respiratory system via CFD-DEM simulations within the RANS framework is currently missing. Often, inadequately clarified assumptions and approximations and the lack of evidences on their quantitative impact on the simulated deposition phenomenology, make a direct comparison among the different theoretical studies and the limited number of experiments a very challenging task. Here, with the ultimate goal of providing a critical analysis of some crucial computational aspects of aerosols deposition, we address the issues of velocity fluctuations propagation in the upper intra-thoracic airways and of the persistence of secondary flows using the SimInhale reference benchmark. We complement the investigation by describing how methodologies used to drive the flow through a truncated lung model may affect numerical results and how small discrepancies are observed in velocity profiles when comparing simulations based on different meshing strategies.

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Recent advances in the characterization of the human respiratory system and in multi-phase flow dynamics in complex geometries have led numerical simulations to play an expanding role for exploring aerosol deposition mechanisms in the lungs. However, the development of an efficient numerical and mathematical description is far from unique, and determining which aspects of the modelling are critical and which details are essentially irrelevant is indeed a difficult task. With the aim of addressing this lack of a rationalized framework, we propose a systematic analysis of pharmaceutical aerosols deposition in the extra-thoracic airways, focusing on several important modelling aspects whose related assumptions and approximations have not always been sufficiently discussed and clarified. We consider the importance of intrinsic time dependent fluctuations of the air flow, highlighting how their contribution in aerosol deposition is as important as the particle-turbulence interaction one. We show how sensitive the turbulence intensity can be to the meshing strategy and how aerosol deposition can be influenced by the latter choice. We demonstrate how a swirling air jet can enhance extra-thoracic deposition compared to a straight one, and how different the deposition patterns can be in case a realistic inhalation profile and aerosol plume are employed.

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In the framework of a Frenkel-Kontorova-like model, we address the robustness of the superlubricity phenomenon in an edge-driven system at large scales, highlighting the dynamical mechanisms leading to its failure due to the slider elasticity. The results of the numerical simulations perfectly match the length critical size derived from a parameter-free analytical model. By considering different driving and commensurability interface configurations, we explore the distinctive nature of the transition from superlubric to high-friction sliding states which occurs above the critical size, discovering the occurrence of previously undetected multiple dissipative jumps in the friction force as a function of the slider length. These driving-induced commensurate dislocations in the slider are then characterized in relation to their spatial localization and width, depending on the system parameters. Setting the ground to scale superlubricity up, this investigation provides a novel perspective on friction and nanomanipulation experiments and can serve as a theoretical basis for designing high-tech devices with specific superlow frictional features.

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Recent measurements suggest the possibility to exploit ionic liquids (ILs) as smart lubricants for nano-contacts, tuning their tribological and rheological properties by charging the sliding interfaces. Following our earlier theoretical study of charging effects on nanoscale confinement and squeezout of a model IL, we present here molecular dynamics simulations of the frictional and lubrication properties of that model under charging conditions. First, we describe the case when two equally charged plates slide while being held together to a confinement distance of a few molecular layers. The shear sliding stress is found to rise strongly and discontinuously as the number of IL layers decreases stepwise. However, the shear stress shows, within each given number of layers, only a weak dependence upon the precise value of the normal load, a result in agreement with data extracted from recent experiments. We subsequently describe the case of opposite charging of the sliding plates and follow the shear stress when the charging is slowly and adiabatically reversed in the course of time, under fixed load. Despite the fixed load, the number and structure of the confined IL layers change with changing charge, and that in turn drives strong friction variations. The latter involves first of all charging-induced freezing of the IL film, followed by a discharging-induced melting, both made possible by the nanoscale confinement. Another mechanism for charging-induced frictional changes is a shift of the plane of maximum shear from mid-film to the plate-film interface, and vice versa. While these occurrences and results invariably depend upon the parameters of the model IL and upon its specific interaction with the plates, the present study helps identifying a variety of possible behavior, obtained under very simple assumptions, while connecting it to an underlying equilibrium thermodynamics picture.

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The critical fluctuations at second order structural transitions in a bulk crystal may affect the dissipation of mechanical probes even if completely external to the crystal surface. Here, we show that noncontact force microscope dissipation bears clear evidence of the antiferrodistortive phase transition of SrTiO_{3}, known for a long time to exhibit a unique, extremely narrow neutron scattering "central peak." The noncontact geometry suggests a central peak linear response coupling connected with strain. The detailed temperature dependence reveals for the first time the intrinsic central peak width of order 80 kHz, 2 orders of magnitude below the established neutron upper bound.

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Electrical charging of parallel plates confining a model ionic liquid down to nanoscale distances yields a variety of charge-induced changes in the structural features of the confined film. That includes even-odd switching of the structural layering and charging-induced solidification and melting, with important changes of local ordering between and within layers, and of squeezout behavior. By means of molecular dynamics simulations, we explore this variety of phenomena in the simplest charged Lennard-Jones coarse-grained model including or excluding the effect a neutral tail giving an anisotropic shape to one of the model ions. Using these models and open conditions permitting the flow of ions in and out of the interplate gap, we simulate the liquid squeezout to obtain the distance dependent structure and forces between the plates during their adiabatic approach under load. Simulations at fixed applied force illustrate an effective electrical pumping of the ionic liquid, from a thick nearly solid film that withstands the interplate pressure for high plate charge to complete squeezout following melting near zero charge. Effective enthalpy curves obtained by integration of interplate forces versus distance show the local minima that correspond to layering and predict the switching between one minimum and another under squeezing and charging.

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The effects of a displacive structural phase transition on sliding friction are in principle accessible to nanoscale tools such as atomic force microscopy, yet they are still surprisingly unexplored. We present model simulations demonstrating and clarifying the mechanism and potential impact of these effects. A structural order parameter inside the material will yield a contribution to stick-slip friction that is nonmonotonic as temperature crosses the phase transition, peaking at the critical T(c) where critical fluctuations are strongest, and the sliding-induced order-parameter local flips from one value to another more numerous. Accordingly, the friction below T(c) is larger when the order-parameter orientation is such that flips are more effectively triggered by the slider. The observability of these effects and their use for friction control are discussed, for future application to sliding on the surface of and ferro- or antiferrodistortive materials.

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Sliding friction between crystal lattices and the physics of cold ion traps are so far non-overlapping fields. Two sliding lattices may either stick and show static friction or slip with dynamic friction; cold ions are known to form static chains, helices or clusters, depending on the trapping conditions. Here we show, based on simulations, that much could be learnt about friction by sliding, through, for example, an electric field, the trapped ion chains over a corrugated potential. Unlike infinite chains, in which the theoretically predicted Aubry transition to free sliding may take place, trapped chains are always pinned. Yet, a properly defined static friction still vanishes Aubry-like at a symmetric-asymmetric structural transition, found for decreasing corrugation in both straight and zig-zag trapped chains. Dynamic friction is also accessible in ringdown oscillations of the ion trap. Long theorized static and dynamic one-dimensional friction phenomena could thus become accessible in future cold ion tribology.

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An electrodeless measurement system based on a resonant circuit is proposed for the measurement of dielectric properties of liquid samples at RF (radio frequency). Generally, properties as dielectric constant, loss factor and conductivity are measured by parallel plate capacitor cells: this method has several limitations in the case of particular liquid samples and in the range of radiofrequencies. Our method is based on the measurements of resonance frequency and quality factor of a LC resonant circuit in different measuring conditions, without and with the liquid sample placed inside a test tube around which the home made coil is wrapped. The measurement is performed using a network analyzer and a dual loop probe, inductively coupled with the resonant circuit. One of the advantages of this method is the contactless between the liquid sample and the measurement electrodes. In this paper the measurement system is described and test measurements of conventional liquids dielectric properties are reported.

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In order to validate specific personal selectors for the collection of fine particles, 65 double measurements of PM10 and PM2.5 were carried out at the same collection site; thus allowing a comparison between two different methods of sampling. The first method was that normally used by ARPAV in order to sample the above-mentioned granulometric fractions in outdoor environment. The second method was chosen by us for personal sampling (PEM working at 2 l/min and at 4 l/min). In both cases the filters gravimetric analysis conformed to the expectations of D.M. 60 of 2/4/2002. The comparison between the two methods showed a good correlation in both the granulometric fractions: correlation coefficients r for the PM2.5 are equal to 0.96 and 0.99 for the PEM working at 2 l/min and at 4 l/min respectively; r for the PM10 are equal to 0.98 and 0.99 for the PEM working at 2 l/min and at 4 l/min respectively. The analysis of results in terms of fine particles concentration and difference between methods against their mean, shows a slight overestimate of the particles concentration with PEM working at 2 l/min, compared to those working at 4 l/min. Nevertheless, considering the good results obtained even with a flow of 2 l/min, we believe that using PEM working at 2 l/min to monitoring 24 hours-personal exposure assures an improved capacity in the battery-operated pumps.

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The authors report the case of a young patient with an aneurysm of the ascending aorta and moderate aortic incompetence, who underwent a conservative operation at our institution. Dilatation of the sinotubular junction, particularly at the level of the non-coronary sinus of the aortic valve with loss of coaptation between the corresponding leaflet and the two coronary leaflets, was identified at the time of surgery as major cause of valve insufficiency. During surgery, the dilated ascending aorta and pathologic aortic sinus were replaced with a 26 Hemashield prosthesis tailored according to the David guidelines. An intraoperative post-repair transesophageal echo exam showed that the aortic valve appeared to be working competently. The post-operative course was uneventful and at one year, an echographic check of the aortic valve showed that it was fully competent, with normal leaflet motion. Conservative surgery can be a good option in selected patients with ascending aortic aneurysm and aortic valve insufficiency.

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Six phases summarize the evolution of the healthy male gonad. Qualitative examination of two-dimensional echograms detects tonal differences at different ages of the testes. However, routine qualitative evaluation of the echograms is too subjective and dependent upon the scanner controls; on the other hand, simple morphology reports are not sufficient to establish the correct histologic and physiologic evolution. So far computer-assisted quantitative analysis of ultrasonic images has been successful in the characterization of tissues based on their echographic properties; thus this approach could be suitable for an accurate identification of the age of healthy testis. Sixty-two normal subjects, ranked in six groups according to age, underwent echographic examination in standard conditions. Echograms were digitized and analysed by means of well-established algorithms for first and second order statistics. Significant differences in tonal features were found able to discriminate among different ages, in agreement with the qualitative analysis and the histologic reports. Furthermore, some second order analysis features exhibit statistically significant alterations of the micro-structural organisation of the echo patterns consequent to changes of the configuration of the ultrasonic targets, that is, of the gonad's histology. In conclusion, quantitative analysis of echograms can provide a tool for a better assessment of normal testis evolution than the qualitative approach.

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The combination of a standardized echographic contrast agent with the analysis of the ultrasonic radio frequency (RF) signal allowed in vitro flow quantitation in a circulation model. The purpose of this study was to investigate both the effects of biological tissues, intervening between probe and insonated structure, and the effects of the angle of incidence between flow and ultrasonic beam on RF flow quantitation. Thus, the contrast agent SHU 454 was intravenously injected (0.4 ml) as a bolus into a circulation model, at variable flow rates, while keeping the pressure and volume of the vessel constant. Injections were performed with saline interposed between probe and vessel and after the addition of the subcutaneous tissue of a pig; injections were also performed using the probe normal to the flow and with an angle of incidence of 45 degrees. Echographic data were recorded by a mechanical sector scanner, capable of sampling the RF signal from a region of interest positioned in the center of the vein. Contrast echo time-intensity curves were generated. As expected, both peak intensity and the area under the curves decreased with intervening tissue (-58 and -70% of baseline values, respectively, p < 0.001). Surprisingly, mean transit time also decreased with intervening tissue (from 1.12 +/- 0.25 seconds with saline, to 0.92 +/- 0.13 seconds with tissue, p < 0.001), thus producing a systematic overestimation of flow (21% on the average). To compensate for signal attenuation, contrast injections were repeated in the presence of tissue after increasing the electronic signal amplification (10 dB), and transit time did not significantly differ from control.(ABSTRACT TRUNCATED AT 250 WORDS)

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Contrast echocardiography has the potential for measuring cardiac output and regional blood flow. However, accurate quantitation is limited both by the use of non-standard contrast agents and by the electronic signal distortion inherent to the echocardiographic instruments. Thus, the aim of this study is to quantify flow by combining a stable contrast agent and a modified echo equipment, able to sample the radio frequency (RF) signal from a region of interest (ROI) in the echo image. The contrast agent SHU-454 (0.8 ml) was bolus injected into an in vitro calf vein, at 23 flow rates (ranging from 376 to 3620 ml/min) but constant volume and pressure. The ROI was placed in the centre of the vein, the RF signal was processed in real time and transferred to a personal computer to generate time-intensity curves. In the absence of recirculation, contrast washout slope and mean transit time (MTT) of curves (1.11-8.52 seconds) yielded excellent correlations with flow: r = 0.93 and 0.95, respectively. To compare the accuracy of RF analysis with that of conventional image processing as to flow quantitation, conventional images were collected in the same flow model by two different scanners: a) the mechanical sector scanner used for RF analysis, and b) a conventional electronic sector scanner. These images were digitized off-line, mean videodensity inside an identical ROI was measured and time-intensity curves were built. MTT by RF was shorter than by videodensitometric analysis of the images generated by the same scanner (p < 0.001). In contrast, MTT by RF was longer than by the conventional scanner (p < 0.001). Significant differences in MTT were also found with changes in the gain setting controls of the conventional scanner. To study the stability of the contrast effect, 6 contrast injections (20 ml) were performed at a constant flow rate during recirculation: the spontaneous decay in RF signal intensity (t1/2 = 64 +/- 8 seconds) was too long to affect MTT significantly. In conclusion, the combination of a stable contrast agent and a modified echocardiographic instrument provides accurate quantitation of flow in an in vitro model; RF analysis is more accurate than conventional processing as to flow quantitation by contrast echocardiography.

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The authors report a case of cardiac metastasis of a rectal adenocarcinoma that infiltrated the right ventricle and partially obstructed its outflow tract. Surgical treatment was performed because of syncopal attacks. The differential diagnosis between organized thrombi and intracardiac tumor is considered.

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In this study 126 subjects (91 males and 35 females, range of age 43-65 years) were studied by coronary angiography. We considered positive for coronary atherosclerosis also patients showing mild or moderate stenosis (> or = 25%). In all subjects we have evaluated serum lipid and apoprotein A-I, B, C-II, C-III and E levels; therefore also cholesterol concentrations in all lipoprotein fractions, separated by sequential ultracentrifugation (VLDL d < 1.006, LDL d 1.006-1.063, HDL d > 1.063 g/ml) and apoprotein B in LDL have been measured. Subjects with coronary atherosclerosis have shown significantly higher levels of total cholesterol, LDL-cholesterol, total cholesterol/HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratios than controls. Therefore, a lower apo A-I/apo B ratio in males and a higher LDL-apo B levels in females has been found in subjects with coronary atherosclerosis in comparison with controls. The stepwise multiple analysis has demonstrated that LDL-cholesterol levels is the parameter that best correlates with the presence of coronary atherosclerosis. These data confirm the importance of the reduction of LDL-cholesterol levels in primary and secondary prevention of coronary heart disease.

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Altered myocardial texture associated with inflammatory infiltration or fibrosis of the myocardium has already been described using qualitative and subjective analysis of two-dimensional echocardiograms. The aim of this work is to test whether quantitative analysis of regional image texture in two-dimensional echocardiograms would be an accurate method to identify myocarditis and myocardial fibrosis. A set of 20 two-dimensional studies with endomyocardial biopsy evaluation was examined in 13 patients. Biopsy-proven myocarditis was present in 8 studies; myocarditis and fibrosis in 4; fibrosis in 3; healing/healed myocarditis in 5. A control group of 8 normal subjects was also studied by echocardiography. After quantitative texture analysis of the first order, entropy appeared to consistently differentiate myocarditis from controls. Among second-order parameters, patients affected by myocarditis or fibrosis showed a decreased entropy and higher angular second moment versus controls. We conclude that myocarditis and fibrosis induce similar image texture alterations in ultrasonic images, with increased spatial heterogeneity of the gray level distribution, which can be differentiated from normal structures with digital image analysis techniques.

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Conventional echocardiography provides fundamental information about mitral valve morphology and function but has a relatively low specificity in evaluating valve calcific deposits, which is critical information for the preoperative decision to perform commisurotomy or replacement. In vitro radiofrequency ultrasonic quantitative analysis of the mitral valve has been demonstrated to be a reliable tool in identifying normal, fibrotic and calcific valves. This study evaluates quantitative ultrasound characterization of the mitral valve in vivo. Thirty-three patients, scheduled to undergo mitral valve replacement, and 20 normal subjects (10 young and 10 older control subjects) were studied with a 2.25-MHz transducer. Radiofrequency signal was analyzed by a microprocessor system (used with an M-mode commercially available echocardiograph) for on-line evaluation of ultrasonic backscatter with 8 bits of amplitude resolution, 40-MHz sampling rate and a 1-microsecond acquisition gate. The integrated value of the rectified radiofrequency signal amplitude was deemed the integrated backscatter index. The highest value recorded with the ultrasonic analysis from each valve was taken as representative and expressed as the percent value with respect to the pericardial integrated backscatter index value of that subject. The 33 excised mitral valves underwent histologic examination. Four groups were identified: young controls (group I, n = 10); older controls age-matched with patients (group II, n = 10); patients with fibrotic mitral valves (group III, n = 13); and patients with calcific mitral valves (group IV, n = 20).(ABSTRACT TRUNCATED AT 250 WORDS)

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The aim of this study was to assess in vivo whether the regional ultrasonic reflectivity, evaluated by a real-time integrated backscatter analysis, was related to the local content of connective tissue in human myocardium as estimated by quantitative histology of endomyocardial biopsies. Sixteen patients with presumptive diagnosis of cardiomyopathy were ultrasonically studied by means of an M-mode-based echocardiographic system with quantitative integrated backscatter analysis capabilities. A 2.25-MHz transducer was used. The integrated value of the rectified radiofrequency signal of the interventricular septum was taken as integrated backscatter index and expressed in percent normalized for the pericardial interface (assumed to be 100%). All patients also underwent multiple left ventricular endomyocardial biopsies, which were stained with Masson's trichrome and studied with the use of a computer-assisted image analysis system. The percent integrated backscatter index was significantly higher in the presence of connective tissue area greater than 20% (eight patients) versus less than 20% (eight patients): 51 +/- 25% versus 26 +/- 11%, p less than 0.05. A significant correlation (p less than 0.05, R = 0.55) was found between percent integrated backscatter index and percent connective tissue area. In vivo on-line quantitative ultrasound analysis is feasible in man and reliably identifies variations in the regional extent of fibrosis in human myocardium.

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