Modelling a new approach for radio-ablation after resection of breast ductal carcinoma in-situ based on the BAT-90 medical device

The majority of local recurrences, after conservative surgery of breast cancer, occurs in the same anatomical area where the tumour was originally located. For the treatment of ductal carcinoma in situ (DCIS), a new medical device, named BAT-90, (BetaGlue Technologies SpA) has been proposed. BAT-90 is based on the administration of 90Y β-emitting microspheres, embedded in a bio-compatible matrix. In this work, the Geant4 simulation toolkit is used to simulate BAT-90 as a homogenous cylindrical 90Y layer placed in the middle of a bulk material. The activity needed to deliver a 20 Gy isodose at a given distance z from the BAT-90 layer is calculated for different device thicknesses, tumour bed sizes and for water and adipose bulk materials. A radiobiological analysis has been performed using both the Poisson and logistic Tumour Control Probability (TCP) models. A range of radiobiological parameters (α and β), target sizes, and densities of tumour cells were considered. Increasing α values, TCP increases too, while, for a fixed α value, TCP decreases as a function of clonogenic cell density. The models predict very solid results in case of limited tumour burden while the activity/dose ratio could be further optimized in case of larger tumour beds.

Image-Aided LiDAR Mapping Platform and Data Processing Strategy for Stockpile Volume Estimation

Stockpile quantity monitoring is vital for agencies and businesses to maintain inventory of bulk material such as salt, sand, aggregate, lime, and many other materials commonly used in agriculture, highways, and industrial applications. Traditional approaches for volumetric assessment of bulk material stockpiles, e.g., truckload counting, are inaccurate and prone to cumulative errors over long time. Modern aerial and terrestrial remote sensing platforms equipped with camera and/or light detection and ranging (LiDAR) units have been increasingly popular for conducting high-fidelity geometric measurements. Current use of these sensing technologies for stockpile volume estimation is impacted by environmental conditions such as lack of global navigation satellite system (GNSS) signals, poor lighting, and/or featureless surfaces. This study addresses these limitations through a new mapping platform denoted as Stockpile Monitoring and Reporting Technology (SMART), which is designed and integrated as a time-efficient, cost-effective stockpile monitoring solution. The novel mapping framework is realized through camera and LiDAR data-fusion that facilitates stockpile volume estimation in challenging environmental conditions. LiDAR point clouds are derived through a sequence of data collections from different scans. In order to handle the sparse nature of the collected data at a given scan, an automated image-aided LiDAR coarse registration technique is developed followed by a new segmentation approach to derive features, which are used for fine registration. The resulting 3D point cloud is subsequently used for accurate volume estimation. Field surveys were conducted on stockpiles of varying size and shape complexity. Independent assessment of stockpile volume using terrestrial laser scanners (TLS) shows that the developed framework had close to 1% relative error.

Studies on Copper Nanometric-Film Deposited by an In-House Developed DC Magnetron Sputtering System

Copper nanofilms are extensively used in the field of material science research. Nanoparticles and nanostructures of copper have various utilities in the field of photocatalytic and sensor applications. The transition metal nanoparticles and nanostructures supply plenty free electrons which drastically enhances the optical and electrical properties compared to bulk material. Here, copper thin films have been deposited on glass slides and silicon substrates using an indigenously developed DC magnetron sputtering system. These depositions have been carried out at three different time spans keeping the magnetron discharge current, working vacuum and target to substrate distance unaltered. The objective of this work is to study the crystalline structure and measure the thickness of the copper nanofilm deposited at three different times. The synthesized films were characterized by using X-Ray Fluorescence (XRF), X-Ray Diffractometer (XRD) and Secondary Ion Mass Spectrometer (SIMS). Characteristic peaks of copper (111) along with Cu2O (110), (220) and (111) were obtained from the XRD pattern. The average grain size of the deposited films has been calculated using Debye-Scherrer equation. The film thickness ranging from 80-160 nm for various time spans were measured from depth profile analysis using SIMS data.

Алгоритм предварительного анализа дифракционных спектров для нанокомпозитных материалов с примесью массивной фракции

This contribution is devoted to discussion of questions related to the influence of a possible contribution from a bulk material on the lineshape of elastic peaks observed in diffraction experiments at neutron and / or X-ray radiation scattering on nanoporous matrices containing substances embedded into their porous space (channels). The proposed algorithm permits to estimate the input of massive component into diffraction peaks using the analysis of the experimentally observed distortions of the lineshape of the Bragg peaks. This preliminary analysis greatly simplifies the profile analysis of nanocomposite diffraction patterns, especially for molecular sieves based on powders of SBA-15, MCM-41, MCM-48, etc. types.

Finite Element Study on the Effect of Geometrical Parameters on the Mechanical Behavior of 3D Reentrant Auxetic Honeycombs.

Auxetic materials are a special case of cellular materials, which exhibit a negative Poisson’s ratio. This in fact is the reason behind their peculiar behavior i.e. lateral shrinkage under longitudinal compression and vice versa. Since these materials do not obey the laws of “normal” materials and go beyond common sense, they are still an emerging class which can be put to use for various purposes like self-locking reinforcing fibers in composites, controlled release media, self-healing films, piezoelectric sensors, and also be used in biomedical engineering. Their stress-strain behavior, Poisson’s ratio and impact energy absorption are controlled by bulk material as well as the unit cell geometry. Among many forms of auxetic structures available, we have chosen a three-dimensional reentrant auxetic honeycomb unit cell. The unit cell geometrical parameters were taken from literature. In this study, we try to understand the effects of strut angle through finite element simulations while keeping the bulk material, unit cell size, strut thickness and number of repetitions constant. A total of three different angles were tested, based on which we conclude that as angle increases, the Poisson’s ratio increases and Energy absorption is maximum at 30 deg.

Нелокальная динамика электронов в AlGaN/GaN-транзисторных гетероструктурах

The nonlocal electrons heating in transistor heterostructures based on gallium nitride and arsenide is compared. It is shown that if, in comparison with a pure bulk material, in the case of GaAs double doped pseudomorphic heterostructures, the real space transfer of electrons significantly reduces their drift velocity overshot in the region of a strong field, then for GaN-based heterostructures, the decrease of the drift velocity overshot in the studied cases does not exceed 30%.

Структурный переход и температурные зависимости коэффициентов теплового расширения NaNO-=SUB=-3-=/SUB=-, внедренного в нанопористое стекло

The temperature evolution of the crystal structure of a nanocomposite material obtained by introducing sodium nitrate NaNO3 from a melt under pressure into a nanoporous alkali borosilicate glass with an average pore diameter of 7 nm has been studied by the method of diffraction of synchrotron radiation in a wide temperature range upon heating. Analysis of the experimental diffraction patterns revealed a significant decrease in the temperature of the structural (orientational) transition by more than 50 K (up to 496 K) compared to bulk sodium nitrate. From the temperature dependence of the intensity of the superstructure peak (113), the dependence of the critical exponent β (T) for this transition was obtained and a significant difference from the critical exponent for a bulk material was found in the temperature range from 455 K to the transition temperature. Analysis of the broadening of Bragg reflections made it possible to estimate the average size (~ 40 nm) of sodium nitrate nanoparticles into the pores. An increase in the linear coefficient of thermal expansion in the [001] direction was found in NaNO3 nanoparticles in comparison with bulk material at temperatures above 450 K.

Non-Destructive 3D Imaging Method Using Muonic X-Rays and a CdTe Double-Sided Strip Detector

Elemental analysis based on muonic X-rays resulting from muon irradiation provides information about bulk material composition without causing damage, which is essential in the case of precious or otherwise unreachable samples, such as in archeology and planetary science. We developed a three-dimensional (3D) elemental analysis technique by combining the elemental analysis method based on negative muons with an imaging cadmium telluride double-sided strip detector (CdTe-DSD) designed for the hard X-ray and soft γ-ray observation. A muon irradiation experiment using spherical plastic samples was conducted at the Japan Proton Accelerator Research Complex (J-PARC); a set of projection images was taken by the CdTe-DSD, equipped with a pinhole collimator, for different sample rotation angles. The projection images measured by the CdTe-DSD were utilized to obtain a 3D volumetric phantom by using the maximum likelihood expectation maximization algorithm. The reconstructed phantom successfully revealed the 3D distribution of carbon in the bulk samples and the stopping depth of the muons. This result demonstrated the feasibility of the proposed non-destructive 3D elemental analysis method for bulk material analysis based on muonic X-rays.

Complex Material and Surface Analysis of Anterolateral Distal Tibial Plate of 1.4441 Steel

Nickel-based austenitic stainless steels are still common for manufacture of implants intended for acute hard tissue reinforcement or stabilization, but the risk of negative reactions due to soluble nickel-rich corrosion products must be considered seriously. Corrosion processes may even be accelerated by the evolution of microstructure caused by excessive heat during machining, etc. Therefore, this study also deals with the investigation of microstructure and microhardness changes near the threaded holes of the anterolateral distal tibial plate containing approx. 14wt.% Ni by composition. There were only insignificant changes of microhardness, grain size, or microstructure orientation found close to the area of machining. In addition, wettability measurements of surface energy demonstrated only minor differences for bulk material and areas close to machining. The cyclic potentiodynamic polarization tests were performed in isotonic physiological solution. The first cycle was used for the determination of corrosion characteristics of the implant after chemical passivation, the second cycle was used to simulate real material behavior under the condition of previous surface damage by excessive pitting corrosion occurring during previous polarization. It was found that the damaged and spontaneously repassived surface showed a three-time higher standard corrosion rate than the “as received” chemically passivated surface. One may conclude that previous surface damage may decrease the lifetime of the implant significantly and increase the amount of nickel-based corrosion products distributed into surrounding tissues.