Emil Strumban

Assessment of gingival thickness using an ultrasonic dental system prototype: A comparison to traditional methods

Knowledge of periodontal anatomy is essential when performing surgical and non-surgical procedures in the field of oral healthcare. Gingival thickness (GT) is often assessed for this purpose. A dental system prototype was recently developed for quantitative, non-invasive GT assessment by high-frequency (HF) ultrasound. Laboratory trials were conducted to validate system performance against a traditional method of assessment. A system with a 50 MHz broadband, spherically-focused transducer was used. The transducer was housed in a small, hand-held probe equipped with a continuous water supply. A-scans were obtained and thickness at each location was determined. For comparison, the traditional method of transgingival probing through tissue with an endodontic k-file needle was also implemented. Preliminary experiments were performed on phantoms simulating the anatomical and acoustic properties of human periodontal tissues. A porcine cadaver was obtained for further laboratory trials. The speed of sound through porcine gingiva was determined to be 1564 ± 21 m/s. Finally, a multiple-point experiment involved GT assessment in an array of locations on the buccal gingival surface in the fourth quadrant. Ultrasonic measurements were found to yield similar GT values to those obtained from invasive methods. Results obtained in this experiment validate the applicability of ultrasound as a diagnostic tool for assessing periodontal anatomy.

Protective coatings for mechanical aluminum-magnesium joints

Abstract 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.

Retraction Note to: Structure and Mechanical Properties of Thick Copper Coating Made by Cold Spray

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.

Characterization of human breast cancer by scanning acoustic microscopy

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.

Portable, low pressure cold spray systems for industrial applications

Publisher Summary Widespread adoption of the Cold Spray [“CS”] technology implies, as the next logical step, its application in the industrial environment. Therefore, the development of a portable low pressure CS system is of fundamental importance. Of special practical interest is establishing the relationship between the operating parameters of a portable CS machine and the resultant micro-structure of the formed spray coatings. To obtain high quality coatings, the configuration of a portable CS system and the spray process parameters have to be selected thoroughly. Due to the number of CS process parameters, it is inevitable that a certain degree of trial and error is required to optimize the spray process for each specific coating–substrate combination. This chapter presents some specific characteristics related to a portable, low pressure system. These characteristics are subsequently compared with those of established high pressure CS systems. One can observe a substantial difference between the velocities of the gas and the particle. This variation is taken into account when the parameters of the powder-laden jet are calculated.