Exploring the linkage between mechanical behaviour and particle-scale interaction of kaolinite

77 Background: Large breast volume (BV) and distance of separation (DoS) have historically served as exclusionary criteria for hypofractionated whole breast irradiation (H-WBI). We investigate dosimetric parameters impacting toxicity and cosmesis. Methods: 299 consecutive patients with T0-2,N0-1,M0 breast cancer were treated with H-WBI at a single institution from 2007-2013. 4,256 cGy were delivered in 16 fractions via tangent photon beams utilizing inverse planning, with objectives to limit the V105 to 15%, the V110 to 2%, and the V115% to <0.1%. 227 patients with available treatment planning information and at least 6 months of follow-up (FU) were analyzed. Dosimetric parameters were correlated with acute (≤6 months post-treatment) and chronic toxicity and overall cosmesis. Proportions of toxicity grade and cosmesis score were compared with chi-square or Fisher exact tests. Results: With a median FU of 2.7 years (range 0.4-6.6 years), there were no local or regional recurrences, 1 distant failure, and one in-field angiosarcoma. Rates of any acute and chronic grade 1/2/3 toxicity were 47%/32%/9% and 53%/22%/7%. Cosmesis (beyond 6 months) was reported as excellent, good, and fair in 45%, 55%, and <1% of patients. The V105 was the best predictor for cosmesis and chronic toxicity, with a V105≤10% being associated with better cosmesis (excellent vs fair/poor) and lower toxicity (grade 0 vs grade 1 vs grade 2/3) compared to a V105>10% (p=0.09 and 0.03, respectively). The mean DoS was 22 cm, with 22% and 3% of patients having a DoS greater than 25 cm and 28 cm. The mean BV was 1523 cc, with 19% and 5% having a BV greater than 2000 cc and 2500 cc. Neither a larger DoS nor a larger BV correlated with an inability to achieve a V105≤10% (p= 0.37 and p=0.13, respectively). Neither DoS nor BV predicted for worse acute toxicity, chronic toxicity, or cosmesis. Conclusions: Minimizing the V110 and V115 and limiting the V105 to ≤10% are useful dosimetric objectives to achieve excellent or good cosmesis following H-WBI. Acceptable toxicity and excellent cosmesis are achievable in women with large DoS or BV, provided techniques to maximize dose homogeneity are employed.

Novel numerical method for calculating initial flux of colloid particle adsorption through an energy barrier

Evaluation of DLVO interaction between a sphere and a cylinder

We investigate the link between particle interactions and induced flow patterns around two identical spheres sedimenting along their centerline in a polymeric fluid. The fluid is strongly shear thinning and, in agreement with previous results, the spheres are observed to chain even at large initial separation distances. The wake of a single particle displays an upward motion of fluid, i.e., a “negative wake” that is commonly observed in fluids with low extensional viscosities. We show that the features of this negative wake vary only weakly with the Deborah number. In the two-sphere case, the pattern of the induced flow depends on the sphere separation distance. The change in the flow pattern does not, however, induce any significant qualitative change in the sphere interactions. Upstream of the leading sphere and downstream of the trailing one along the sedimentation axis, the variations of the fluid velocity are well described by a single master curve for different values of the sphere separation distance. The existence of such a curve indicates that non-Newtonian effects near each particle are dominated by local conditions near the sphere surfaces, and are only weakly influenced by the presence of a second sphere.

A bounded vortex flow is generated by a nozzle with a central suction outlet surrounded by inlet jets with a 15 deg inclination in the azimuthal direction. The jets impinge on a flat surface called the impingement surface. The circulation introduced by azimuthal tilting of the inlet jets is concentrated at the flow centerline by the suction outlet to form a wall-normal vortex, with axis nominally orthogonal to the impingement surface. An experimental study was conducted in water to examine the structure and dynamics of bounded vortex flows with balanced inlet and outlet flow rates for different values of the separation distance h between the nozzle face and the impingement surface. The experiments used a combination of laser-induced fluorescence (LIF) to visualize the vortex and jet flow structure and particle-image velocimetry (PIV) for quantitative velocity measurements along a planar slice of the flow. Different liquid flow rates were examined for each separation distance. The results show that a stationary wall-normal vortex is formed at small separation distances, such as when the ratio of h to the inlet jet radial position R is set to h/R=0.67. When the separation distance is increased such that h/R=1.3, the intake vortex first becomes asymmetric, drifting to the one side of the flow, and then bifurcates into a vortex pair that rotates in a V-state around the flow centroid. At large separation distances (e.g., h/R=6.7), the intake vortex adopts a spiral structure that is surrounded by the inlet jets, with upward-flowing exterior fluid at the center of the spiral vortex structure. The arms of this spiral are advected downward with time by the inlet jet flow until they reach the impingement surface. Knowledge of this flow structure at different separation distances is necessary in order to design systems that utilize this flow field for enhancement of particle removal rate or heat/mass transfer from a surface.

Both in vitro and in vivo, contrast agent microbubbles move near bounding surfaces, such as the wall of an experimental container or the wall of a blood vessel. This problem inspires interest in theoretical models that predict the effect of a wall on the dynamics of a contrast microbubble. There are models for a bubble at a large distance from a wall and for a bubble adherent to a wall. The aim of the present study is to develop a generalized model that describes the dynamics of a contrast microbubble at arbitrary distances from a wall and thereby make it possible to simulate the acoustic response of the bubble starting from large separation distances up to contact between the bubble and the wall. The wall is assumed to be a plane. Therefore, the developed model applies for in vitro investigations of contrast agents in experimental containers. It can also be used as a first approximation to the case of a contrast microbubble within a large blood vessel. The derivation of the model is based on the multipole expansion of the bubble velocity potential, the image source method, and the Lagrangian formalism. The model consists of two coupled equations, one of which describes the bubble radial oscillation and the second describes the translation of the bubble center. Numerical simulations are performed to determine how the acoustic response of a contrast microbubble depends on the separation distance near walls of different types: rigid, plastic, arterial, etc. The dynamics of the bubble encapsulation is described by the Marmottant shell model. The properties of the plastic wall correspond to OptiCell chambers commonly used in experiments. The results of the simulations show that the bubble resonance frequency near a wall depends on both the separation distance and the wall material properties. In particular, the rigid wall makes the resonance frequency decrease with decreasing separation distance, whereas in the vicinity of the OptiCell wall and the arterial wall, the resonance frequency increases. The theoretical model is validated by comparing with experimental data available in the literature for phospholipid-shelled microbubbles near a compliant agarose gel boundary. The comparison is conducted for two data sets. In the first case, the simulated and measured parameters of the bubble acoustic response (resonance frequency and maximum amplitude of the scattered pressure) are compared as a function of bubble diameter, using the experimental data obtained for bubbles with diameters ranging from 2.3 to 4 μm, insonified at 30 kPa in the frequency range from 4 to 13.5 MHz. In the second case, the simulated and measured values of the maximum amplitude of the scattered pressure are compared as a function of separation distance from the agarose boundary, using the experimental data for a 2.3 μm-diameter bubble insonicated at 69 kPa and 11 MHz. In both cases, the theoretical model correctly predicts the qualitative tendency in the behavior of the measured quantities and their quantitative level.

Unraveling the details of how supported lipid bilayers (SLBs) are coupled to oxide surfaces is experimentally challenging, and there is an outstanding need to develop highly surface-sensitive measurement strategies to determine SLB separation distances. Indeed, subtle variations in separation distance can be associated with significant differences in bilayer-substrate interaction energy. Herein, we report a nanoplasmonic ruler strategy to measure the absolute separation distance between SLBs and oxide surfaces. A localized surface plasmon resonance (LSPR) sensor was employed to track SLB formation onto titania- and silica-coated gold nanodisk arrays. To interpret measurement data, an analytical model relating the LSPR measurement response to bilayer-substrate separation distance was developed based on finite-difference time-domain (FDTD) simulations and theoretical calculations. The results indicate that there is a larger separation distance between SLBs and titania surfaces than silica surfaces, and the trend was consistent across three tested lipid compositions. We discuss these findings within the context of the interfacial forces underpinning bilayer-substrate interactions, and the nanoplasmonic ruler strategy provides the first direct experimental evidence comparing SLB separation distances on titania and silica surfaces.

Operation parameters optimization of a separating system for non-ferrous metal scraps from end-of-life vehicles based on coupled simulation

The dynamics of biofilm formation in clinical strains of Staphylococcus epidermidis and Staphylococcus haemolyticus associated with neonatal infections

Heat transfer characteristics of dual flame with outer swirling and inner non-swirling flame impinging on a flat surface

Flow-structure interactions of two parallel inverted flags with small separation distances in a water tunnel

A study of bubble–particle interaction using atomic force microscopy

A theoretical model is developed that describes nonlinear spherical pulsations and translational motions of two interacting bubbles at arbitrary separation distances between the bubbles. The derivation of the model is based on the multipole expansion of the bubble velocity potentials and the use of the Lagrangian formalism. The model consists of four coupled ordinary differential equations. Two of them are modified Rayleigh-Plesset equations for the radial oscillations of the bubbles and the other two describe the translational displacement of the bubble centers. The equations are not subject to the assumption that the distance between the bubbles is large compared to the bubble radii and hence make it possible to simulate the bubble dynamics starting from large separation distances up to contact between the bubbles providing that the deviation of the bubble shape from sphericity is negligible. Numerical simulations are carried out to demonstrate the capabilities of the developed model. It is shown that the correct modeling of the translational dynamics of the bubbles at small separation distances requires terms accurate up to ninth order in the inverse separation distance. Physical mechanisms are analyzed that lead to the change of the direction of the relative translational motion of the bubbles in finite-amplitude acoustic fields.

In this paper, we apply the slender body theory to study the effect of higher order hydrodynamic interactions between two slender bodies of revolution moving in close proximity, in an unbounded, inviscid, and incompressible fluid. We compare between leading and second-order approximations, as well as approximate and exact separation distances. The total solution is found to be valid for both small and large lateral separation distances. The contribution of the higher order forces is found to be relatively small for large separation distances, though significant for small separation distances. Comparisons with measurements and simulations are satisfactory.

An object‐based technique was utilized to identify hydrometeor size‐sorting signatures at lower levels in the convective regions of 10 mesoscale convective systems (MCSs) during the 2015 Plains Elevated Convection at Night (PECAN) field campaign. Composite statistical analysis indicates that the magnitudes of size‐sorting signatures (the separation distances between rain diameter maxima and concentration maxima) are nonlinearly correlated to the echo‐top height, rain mass beneath the melting level, and precipitation rates at higher percentiles. To explore this correlation, the weather forecasting and research model was used to simulate the 20 June 2015 MCS during PECAN. Statistical analysis of the model outputs indicates more active riming growth and quicker graupel fallout at warmer temperatures near areas with larger separation distances. While updraft intensity above the melting level was also positively correlated to separation distances, this correlation was only statistically significant within certain temperature ranges. Additional analyses reveal that the higher intense precipitation potential near signatures with large separation distances could be attributed to precipitation production from the melted graupel. Finally, spatial correspondence between graupel distribution at the melting level and rain distribution at the lowest model level illustrates the critical role of graupel sedimentation and sorting in creating size‐sorting signatures in MCSs during the PECAN field experiment.