An automatic approach for artifacts detection and shadow enhancement in intravascular ultrasound images

Intravascular ultrasound (IVUS) is clinically available for visualizing coronary arteries. However, it suffers from acoustic shadow areas and ring-down artifacts as two of the common issues in IVUS images. This paper introduces an approach which can overcome these limitations. As shadow areas were displayed behind hard plaques in the IVUS grayscale images, calcified plaques were first segmented by using Otsu threshold. Then, active contour, histogram matching, and local histogram matching are implemented. In addition, a new modified circle Hough transform is introduced to remove the ring-down artifacts from IVUS images. In order to evaluate the efficacy of this new method in detection of shadow and ring-down regions, 300 IVUS images are considered. Sensitivity of 89% and specificity of 92% are achieved from a comparison in revelation of calcium along with shadow in the proposed method and virtual histology images. Also, area differences of \(5.83 \pm 3.3\) and \(5.65 \pm 2.83\) are obtained, respectively, for ring-down and shadow domain when compared to measures performed manually by a clinical expert.     

Wrap-bake-peel process for nanostructural transformation from beta-FeOOH nanorods to biocompatible iron oxide nanocapsules

The thermal treatment of nanostructured materials to improve their properties generally results in undesirable aggregation and sintering. Here, we report on a novel wrap-bake-peel process, which involves silica coating, heat treatment and finally the removal of the silica layer, to transform the phases and structures of nanostructured materials while preserving their nanostructural characteristics. We demonstrate, as a proof-of-concept, the fabrication of water-dispersible and biocompatible hollow iron oxide nanocapsules by applying this wrap-bake-peel process to spindle-shaped akagenite (beta-FeOOH) nanoparticles. Depending on the heat treatment conditions, hollow nanocapsules of either haematite or magnetite were produced. The synthesized water-dispersible magnetite nanocapsules were successfully used not only as a drug-delivery vehicle, but also as a T2 magnetic resonance imaging contrast agent. The current process is generally applicable, and was used to transform heterostructured FePt nanoparticles to high-temperature face-centred-tetragonal-phase FePt alloy nanocrystals.     

Microfluidic behavior in melt-spun hollow and liquid core fibers

The development of thermoplastic fibers containing a liquid core is described. Internal morphology analysis confirms that the liquid-containing core is composed of a continuous cylindrical microchannel of constant diameter. Microfluidic experiments on both liquid core and reference hollow fibers were conducted by pumping distilled water through several filaments simultaneously. The observed fluid motions are satisfactorily described by the Hagen-Poiseuille law, indicating that the hollow and liquid core fibers have internal diameters of 31.6 and 14.8 µm, respectively. Flushing the liquid core fibers with a surfactant solution efficiently removes the saturated ester initially used during the melt spinning of the fiber.     

Predicting pressure drop in venturi scrubbers with artificial neural networks

In this study a new approach based on artificial neural networks (ANNs) has been used to predict pressure drop in venturi scrubbers. The main parameters affecting the pressure drop are mainly the gas velocity in the throat of venturi scrubber (V(g)(th)), liquid to gas flow rate ratio (L/G), and axial distance of the venturi scrubber (z). Three sets of experimental data from five different venturi scrubbers have been applied to design three independent ANNs. Comparing the results of these ANNs and the calculated results from available models shows that the results of ANNs have a better agreement with experimental data.     

Study of Corrosion Behavior and In Vitro Bioactivity of Single NbSi2 and Duplex NbSi2/Nb5Si3 Coatings on Nb Substrates for Biomedical Applications

Protection of Metals and Physical Chemistry of Surfaces - Single NbSi2 and duplex NbSi2/Nb5Si3 coatings were successfully applied on Nb substrates using halide activated pack cementation (HAPC)...     

Necrostatin-1 Supplementation to Islet Tissue Culture Enhances the In-Vitro Development and Graft Function of Young Porcine Islets

Pre-weaned porcine islets (PPIs) represent an unlimited source for islet transplantation but are functionally immature. We previously showed that necrostatin-1 (Nec-1) immediately after islet isolation enhanced the in vitro development of PPIs. Here, we examined the impact of Nec-1 on the in vivo function of PPIs after transplantation in diabetic mice. PPIs were isolated from pancreata of 8–15-day-old, pre-weaned pigs and cultured in media alone, or supplemented with Nec-1 (100 µM) on day 0 or on day 3 of culture (n = 5 for each group). On day 7, islet recovery, viability, oxygen consumption rate, insulin content, cellular composition, insulin secretion capacity, and transplant outcomes were evaluated. While islet viability and oxygen consumption rate remained high throughout 7-day tissue culture, Nec-1 supplementation on day 3 significantly improved islet recovery, insulin content, endocrine composition, GLUT2 expression, differentiation potential, proliferation capacity of endocrine cells, and insulin secretion. Adding Nec-1 on day 3 of tissue culture enhanced the islet recovery, proportion of delta cells, beta-cell differentiation and proliferation, and stimulation index. In vivo, this leads to shorter times to normoglycemia, better glycemic control, and higher circulating insulin. Our findings identify the novel time-dependent effects of Nec-1 supplementation on porcine islet quantity and quality prior to transplantation.     

Controlled-pH tissue cleanup protocol for signal enhancement of small molecule drugs analyzed by MALDI-MS imaging

The limit of detection of low-molecular weight compounds in tissue sections, analyzed by matrix assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI), was significantly improved by employing sample washing using a pH-controlled buffer solution. The pH of the washing solutions were set at values whereby the target analytes would have low solubility. Washing the tissue sections in the buffered solution resulted in removal of endogenous soluble ionization-suppressing compounds and salts, while the target compound remained in situ with minor or no delocalization during the buffered washing procedure. Two pharmaceutical compounds (cimetidine and imipramine) and one new protease inhibitor compound were successfully used to evaluate the feasibility of the pH-controlled tissue washing protocol for MALDI-MSI. Enhancement in signal-to-noise ratio was achieved by a factor of up to 10.     

Axial compressive behavior of concrete actively confined by metal strips; part A: experimental study

This paper presents the results of an experimental study on the application of strapping technique for retrofit of concrete compressive specimens. In this technique, standard strapping devices, which are used in the packaging industry, are applied to post-tension high strength metal strips around the concrete columns. Experimental program included axial compressive tests on 72 cylindrical and prismatic compressive specimens, which were actively confined by pre-stressed metal strips. The effects of various parameters on strength and ductility of confined concrete were studied including compressive strength of concrete, mechanical volumetric ratio of confining strips, post-tensioning force in the strip, number of strip layers wrapped around the specimens and details of strip joint. The effects of strength and ductility of confining strips on the behavior of confined specimens were also studied. Longitudinal and lateral strains of concrete and strain of the strips were monitored. Test results showed significant increase in the strength and ductility of specimens due to active confinement by metal strips. It was observed that ductility of confining material plays the most important role in enhancement of concrete ductility. The gain in strength is strongly dependent to the effective mechanical volumetric ratio of confining strips. It was also observed that the active confinement of concrete by post-tensioning the confining element results in stiffer pre-peak response of concrete specimens than the usual passive confinement.     

Contribution of City Prosperity to Decisions on Healthy Building Design:A cases tudy of Tehran

In this paper,the city prosperity manifest is analyzed through a logical process and a framework is then proposed for designing healthy buildings in Tehran. The current status of urbanization in terms of the number of people living together and the changes in old behavior and perspectives have resulted in deficiencies to the health and hygiene of buildings apart from their surrounding environment. Consequently,these problems have affected people's well-being.This study mainly aims to determine policies and strategies for the architecturaldesign of healthy buildings according to health and safety conditions that influence the quality of internal spaces and external environment of cities.The study is conducted based on logical reasoning and uses focus group and in-depth interviews to assess the final result. The result is aframework that suggests a number of policies that can promote the mental and physical health as well as hygiene of residents through healthy buildings.