BACKGROUND:The increased incidence rate of skin cancers during the last decades is alarming. One of the significant difficulties in the histopathology of skin cancers is appearance variability due to the heterogeneity of diseases or tissue preparation and staining process. This study aims to investigate whether the high-resolution acoustic microscopy has the potential for identifying and quantitatively classifying skin cancers. MATERIAL/METHODS:Unstained standard formalin-fixed skin tissue samples were used for ultrasonic examination. The high-frequency acoustic microscope equipped with the 320 MHz transducer was utilized to visualize skin structure. Fourier transform was performed to calculate the sound speed and attenuation in the tissue. RESULTS:The acoustic images demonstrate good concordance with the traditional histology images. All histological features in the tumour were easily identifiable on acoustic images. Each skin cancer type has its combination of ultrasonic properties significantly different from the healthy skin. CONCLUSIONS:High-resolution acoustic imaging strengthened with quantitative analysis shows a potential to work as an auxiliary imaging modality assisting pathologists to lean to the particular decision in doubtful cases. The method can also assist surgeon to ensure the complete resection of a tumour.

Understanding the complex mechanical behavior of stainless steel based composite coatings is important for engineering applications. The focus of this research was on gaining a fundamental understanding of the structure/property relationships that exist during structure formation of the coatings made by new low pressure cold spraying with propellant gas at the temperatures of 800-1000°C (warm spray). While composition is one of the key parameter in determining the final microstructure, the specific warm spray powder shock consolidation parameters (particle velocity and gas temperature) were found to have significant effects on the development of composite structure formation and mechanical properties. Microstructural examination and modeling results revealed that the strain localization mechanism differs from that of adiabatic shear band formation that results in large differences in the ensuing microstructure of the composite coating and its properties.

The main purpose of this study was to form cold-sprayed copper coatings on A 516 low carbon steel, which is considered a prospective material for manufacturing used nuclear fuel containers. The 3 mm-thick Cu coatings were formed using the high pressure cold spray method with Nitrogen as the propellant gas. The deformation of copper particles during the deposition process was studied. The obtained SEM images of the Cu layer-A 516 low carbon steel substrate interface cross sections demonstrated that the Cu layer at the substrate interface had a dense microstructure with localized jet-metallic mixing areas. The Cu particles were deformed considerably more severely in this layer than in the consequently deposited upper layers. The steel substrate underwent severe deformation due to the impact of Cu particles. The mutual severe deformation of Cu particles and steel substrate resulted in a considerable increase of adhesion strength up to 120 MPa. The structure of coatings and coating-substrate interface was studied.

AZ31 alloy is used as a lightweight material for structural application in the automobile and aircraft production. However, alloy AZ31 is known to have poor corrosion resistant due to high electrochemical activity. In this study, the possibility of improving the corrosion resistance by applying protective coatings deposited by the low pressure cold spray process was investigated. The relative performance of each cold sprayed corrosion preventive coatings was assessed in accordance with American Society for Testing and Materials standards. The data for the bare AZ31 alloy were initially obtained and used as a reference point to compare the corrosion protective performance of different preventive coatings. Electrochemical behaviour of each coating composition was analyzed after a given time period of the accelerated corrosion test. Microstructure and mechanical properties of the deposited preventive coatings are also discussed. The cold sprayed preventive coatings provide sufficient protection to substantially reduce the corrosion rate of alloy AZ31.

We report a new progress in the development of a portable ultrasonic transcranial imaging system, which is expected to significantly improve the clinical utility of transcranial diagnostic ultrasound. When conventional ultrasonic phased array and Doppler techniques are applied through thick skull bones, the ultrasound field is attenuated, deflected, and defocused, leading to image distortion. To address these deficiencies, the ultrasonic transcranial imaging system implements two alternative ultrasonic methods. The first method improves detection of small foreign objects, such as bone fragments, pieces of shrapnel, or bullets, lodged in the brain tissue. Using adaptive beamforming, the method compensates for phase aberration induced by the skull and refocuses the distorted ultrasonic field at the desired location. The second method visualizes the blood flow through intact human skull using ultrasonic speckle reflections from the blood cells, platelets, or contrast agents. By analyzing these random temporal changes, it is possible to obtain 2D or 3D blood flow images, despite the adverse influence of the skull. Both methods were implemented on an advanced open platform phased array controller driving linear and matrix array probes. They were tested on realistic skull bone and head phantoms with foreign inclusions and blood vessel models.

This work is devoted to development of techniques for detection of adhesive in joints and image construction of the adhesive spatial distribution. Based on numerical modeling, the specific behavior of the reverberating pulseecho waveforms in steel–adhesive and aluminum–adhesive multi–layered structures is analyzed. It is shown that the energy of the received waveform weighted within a certain time gate can be used as a metric for discriminating between no/adhesive areas. To generate the image of the adhesive distribution the waveforms received by the elements of the matrix ultrasonic array were independently processed and the outputs are spatially interpolated and compared with a certain threshold. The developed algorithms have been tested on steel-to-steel, aluminum-toaluminum and aluminum-to-steel adhesive joints using 15 MHz, 52-element, 10 mm x 10 mm matrix array of ultrasonic transducers.

Abstract Surface preparation is very important for reliable adhesive bonding of cold sprayed coatings to the substrate. In this work, the grit blasting of low-carbon A516 steel substrates with Al2O3 particles was studied and the roughness parameters Ra and Rt of the grit blasted surfaces were then measured. The influence of alumina grit size on the roughening of the A516 steel substrate, and the resulting effect on the roughness of the Cu coating – steel interface were studied. The results showed that variations of the grit blast size had significantly affected the resultant surface roughness of the substrate. The adhesive strength of the formed copper coatings on A516 steel substrates depends on the surface roughness and hardness of the base material. The adhesive strength about 110-200MPa was achieved. The specific features of the Cu coating-A516 steel interface topography were examined and discussed.

Abstract The main goal of the combined Cold Spray – Sintering technology development is to obtain high density ductile Fe- Al intermetallics based thermal barrier coatings as an alternative to conventional ZrO2 coatings widely applied in industry. The task of this paper is to examine the structural changes of cold sprayed Al-AISI 316L composite coatings due to synthesis of Fe-Al intermetallics during annealing and find the conditions of high density composite formation. A dense Fe/Al intermetallic-Al composite coating is obtained. Three factors are found to play the main role in the structure formation of dense Fe-Al intermetallic composite coating: i) layered structure, ii) particle size and thickness of Fe and Al layers, iii) annealing temperature.

In this article, the influences of environmental conditioning and cyclic compressive loading on bio-based neat polyurethane and fiber reinforced composite foams have been studied. Within the context of this manuscript the term bio-based polyurethane foam is defined as any foam containing one or more renewable materials based on chemical components in their basic composition. The samples studied are blocks with side lengths ranging from 20 mm to 80 mm in size. In addition to investigating the mechanical material behavior of these materials, the rationale for the investigation was to develop and disseminate engineering knowledge of these materials and also to consider these materials as possible alternatives to fiberglass and/or other foam reinforcing additives. It was observed that environmental conditioning resulted in overall foam material degradation after the first cycle of loading. Energy absorption levels were higher in the first loading cycle for the unconditioned specimens, but after 50 loading cycles the foams exhibited almost identical responses approaching zero. The load bearing capacity was lower in both bio-based foams when environmental conditioning was present and dry heat conditioning contributed to a more significant impact than wet heat conditioning. Cyclic mechanical testing results indicated that the foams degrade significantly after the first loading cycle and the degree of degradation between consecutive cycles decreases as the compression continues. Moreover, scanning electron microscopy was conducted to observe cellular geometry and cell fracture. A further investigation illustrated that the low density foam without fiber proved to be more resistant to both mechanical loading and environmental conditioning compared to the high density foam with fiber. This finding indicates that the presence of the fiber within foams results in a reduction of mechanical performance when either environmental conditioning or a given amount of compression is applied.

This paper presents an investigation of polypropylene composites reinforced with natural fibers (sisal, microfiber, and wheat straw) with ultrasonic methods. Results show a correlation between sound speed in composite and fiber content and water absorption. Fiber inhomogeneity and voids distribution were assessed with various ultrasonic imaging devices with different resolution. The obtained results justify the feasibility of using the ultrasonic technique for evaluation of the fiber's volume fraction and water content and for visualization of voids and fibre homogeneity. The ultrasonic method provides quick feedback in optimizing the molding technological regime settings to produce composites with the required mechanical performance.

Since the beginning of the last century, the number of methods available to art analysts has significantly increased. In addition to methods based on personal experience, new approaches have appeared that rely on the use of contemporary technologies, including lasers, radiation of various wavelengths, acoustics and any combination thereof for the extraction of a full range of information. The information of interest is often related to the composition and the conservation state of an artwork, as well as to the materials used and their age. Quite recently, thermographic defectoscopy has been introduced as a new method for artwork diagnostics. After being proven effective for the analysis of wood and plasters, this method has been applied to the inspection of canvas-based paintings. Thermography of pictorial art objects usually utilises a short heat pulse in order to bring the object out of thermal equilibrium. The following evolution of the temperature is recorded by a thermal imager. Since the temperature distribution on the surface is affected by the internal structure of the object, it becomes possible to draw conclusions on the condition of the subsurface layers. The readings of the thermal imager can sometimes be used without any post-processing (for example in the detection of large detachments), but may require an additional mathematical algorithm to reveal minute internal defects. There are several ways of post-processing the raw thermographic measurements for the extraction of information. This article outlines some existing methods, as well as their theoretical backgrounds, and discusses their applicability. Several examples of thermographic analyses of real paintings are given and discussed.

Objectives: The purpose of this study was to characterize human breast cancer tissues by the measurement of microacoustic properties. Methods: We investigated eight breast cancer patients using acoustic microscopy. For each patient, seven blocks of tumor tissue were collected from seven different positions around a tumor mass. Frozen sections (10 micrometer, μm) of human breast cancer tissues without staining and fixation were examined in a scanning acoustic microscope with focused transducers at 80 and 200 MHz. Hematoxylin and Eosin (H and E) stained sections from the same frozen breast cancer tissues were imaged by optical microscopy for comparison. Results: The results of acoustic imaging showed that acoustic attenuation and sound speed in cancer cell-rich tissue regions were significantly decreased compared with the surrounding tissue regions, where most components are normal cells/tissues, such as fibroblasts, connective tissue and lymphocytes. Our observation also showed that the ultrasonic properties were influenced by arrangements of cells and tissue patterns. Conclusions: Our data demonstrate that attenuation and sound speed imaging can provide biomechanical information of the tumor and normal tissues. The results also demonstrate the potential of acoustic microscopy as an auxiliary method for operative detection and localization of cancer affected regions.

Noninvasive methods of near-infrared, short-wave infrared, and thermographic inspection of artwork are described in this article and compared in terms of their ability to reveal both hidden graphite underdrawings and subsurface degradations. This inspection aids the understanding of the artist's work methods and locates hidden areas of damage. While all three inspection methods are suitable for locating sketches and changes in composition, this study has proven that thermographic methods are very useful in detecting structural defects such as delaminations and cavities, as demonstrated with experiments conducted on test samples and real paintings.

The interest of our study is the in-vivo transcranial visualization of blood flow without removal of the skull. The strong attenuation, scattering, and distortion by the skull bones (or other tissues) make it difficult to use currently existing methods. However, blood flow can still be detected by using the ultrasonic speckle reflections from the blood cells and platelets (or contrast agents) moving with the blood. The methodology specifically targets these random temporal changes, imaging the owing region and eliminating static components. This process analyzed over multiple exposures allows an image of the blood flow to be obtained, even with negative acoustic effects of the skull in play. Experimental results show this methodology is able to produce both 2D and 3D images of the owing region, and eliminates those regions of static acoustic sources as predicted. Images produced of the owing region are found to agree with the physical size of the vessel analogues, and also found to provide a qualitative measure on the amount of flow through the vessels.

The work addresses the important role of conservation science in the pre-restoration diagnostics of paintings. The authors demonstrate how mid-infrared (3-5 μm band) methods, namely, Pulse thermography, Pulse Phase thermography and Principal Component thermography, can be used for the analysis of wood-based and canvas-based paintings, illustrating the power of this approach in the detection of delaminations, degraded regions, as well as uncovering scenes which have been painted over (pentimenti). The results of the application of thermographic methods are compared with the results achieved through Near-Infrared reflectography (0.7-1.1 μm band) which is recognized as one of most conventional methods for art diagnostics.

This chapter presents the results of a study to use broadband frequency acoustic microscopy to carry out digital imaging and computer simulation to characterize tissue. Since contrast in an acoustic image for skin tissue including a cancerous portion is formed by attenuation differences within the tissue, prediction of the amplitude of a transducer output is important for the field of medical ultrasound. An abnormal skin tissue was selected as a specimen, and compared to a normal skin tissue. The technique suggests the use of this approach as a diagnostic tool and opens the door for more sophisticated analysis. The author develops a mathematical modeling for a five-layer acoustic wave propagation system. The results indicate both qualitative and quantitative differences between normal and abnormal melanoma tissue, thus paving the way for a potentially useful diagnostic medical tool without the need for staining tissue as is most often required in optical imaging. Controlled Vocabulary Terms acoustic microscopy; acoustic wave propagation; biomedical optical imaging; mathematical analysis; virtual machines

This paper develops a novel two-frequency approach for noninvasive evaluation of cancerous tissue with optimum depth and resolution. Frequencies of about 50 MHz are used in thickly sliced tissue to detect differences of the relative attenuation (C-scan mode scanning) with relatively limited resolution. Thus, suspect zones can be identified according to a quantitative criterion. These suspect zones are then selected for preparation of thin, transversal slices from within the original thick slices. Very-high-resolution (1-μm) visualization of cells is obtained at around 600 MHz on these transversal sections and adjacent sections are prepared for histological study in parallel. The technique's feasibility and potential are demonstrated on both normal and cancerous (melanoma) skin tissue. Isotropy of the specimens is experimentally verified to ensure that conditions were coherent for use of a 5-layer, angular spectrum model made to simulate longitudinal velocity, allowing estimation of longitudinal velocity from semiquantitative V(z) data.

Scanning acoustic microscopy (SAM) is a modern, powerful technology for visualizing the internal structure of solid samples. It uses high frequency ultrasonic waves to get information from inside inhomogeneities and, therefore, is a sensitive, precise and safe technique for material characterization. It can be successfully used in scientific and research practices but has the greatest potential as a technology used in nondestructive quality evaluation. The present paper describes the methodology and different aspects of ultrasonic testing performed on a variety of industrial samples with a scanning acoustic microscope. The samples came from different areas of manufacturing and were intentionally chosen as revealing specific characteristics for different discontinuities. Acoustical images (B- and C-scans) were obtained with an optimized configuration of the microscope and analyzed for each sample. It was demonstrated that SAM technology can effectively detect, evaluate and classify imperfections: porosity in aluminum casting, undersized and cavernous resistance spot welds, low penetration depth of laser weld seams, insufficient or damaged areas of adhesive bonding of metals and fiber reinforced composites, and so on. The precision and value of the obtained acoustic images in some cases were proven by destructive testing.