Crystallization in Zirconia Film Nano-Layered with Silica

Gravitational waves are detected using resonant optical cavity interferometers. The mirror coatings’ inherent thermal noise and photon scattering limit sensitivity. Crystals within the reflective coating may be responsible for either or both noise sources. In this study, we explored crystallization reduction in zirconia through nano-layering with silica. We used X-ray diffraction (XRD) to monitor crystal growth between successive annealing cycles. We observed crystal formation at higher temperatures in thinner zirconia layers, indicating that silica is a successful inhibitor of crystal growth. However, the thinnest barriers break down at high temperatures, thus allowing crystal growth beyond each nano-layer. In addition, in samples with thicker zirconia layers, we observe that crystallization saturates with a significant portion of amorphous material remaining.

Experimental Investigation and Numerical Simulation for Corrosion Rate of Amorphous/Nano-Crystalline Coating Influenced by Temperatures

A high-velocity oxygen fuel (HVOF) system was employed to prepare a Fe49.7Cr18Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 amorphous coating on mild steel. The electrochemical behavior of the resultant coatings, namely as-sprayed coating and vacuum heat-treated coating (at 650 °C and 800 °C), were investigated in a 3.5% NaCl solution at variable temperatures using scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, optical microscopy (OM), and XRD diffraction. Moreover, COMSOL Multiphysics version 5.5 software were employed for predicting the galvanic corrosion of amorphous material immersed in an aqueous NaCl solution, using the software finite element kit. The experiments demonstrated that the coatings’ pitting resistance was significantly affected by temperature. The results also showed that temperature affected the pitting corrosion rate and changed the shape of the pits. However, the changes were not as extreme as those observed in stainless steel. Furthermore, there was no significant difference between the as-sprayed coating and the vacuum-heat-treated coating at 650 °C. At low NaCl concentrations at and temperatures below the critical pitting temperature, the resulting pits were significantly small with a hemisphere-like. By contrast, at a higher NaCl concentration at 70 °C, particularly in the case of heating at 650 °C, the pits appearing on the Fe-based amorphous coating were vast and sometimes featured a lacy cover.

Electro-plasticity’s Effect By Deformation And Impulse Impact Of A High Energy Electromagnetic Field

The problem of obtaining predicted physical and mechanical properties and a given service life of multifunctional composite protective coatings in the form of barrier layers that increase the service life of mechanical engineering products and formative tools are inherently interconnected. Among all the variety of innovative highly efficient technological processes, a special place should be given to the method of electro-acoustic spraying (ELAN). This method is innovative in the field of synthesis of multifunctional composite coatings, which allows the formation of protective films of an amorphous material on any conductive substrates [1]. This technology is based on the use of the complex energy of an electric spark and a complex ultrasonic field. The aim of this work is to optimize the process of obtaining multifunctional composite protective coatings based on the complex mass transfer of the electrode material and the subsequent formation of amorphous structures with predictable physical and mechanical properties by the method of electro-acoustic spraying based on the effect of electro-plasticity during deformation and pulsed action of a high-energy electromagnetic field.

An Exceptionally Stable and Widespread Hydrated Amorphous Calcium Carbonate Precipitated By the Dog Vomit Slime Mold Fuligo Septica (Myxogastria)

Biogenic amorphous calcium carbonate (ACC) is typically metastable and can rapidly transform through aging, dehydration, and/or heating to crystalline calcium carbonate. Gaining insight into its structure and properties is typically hampered by its tendency to crystallize over short time periods once isolated from the host organism, and also by the small quantities that are usually available for study. Here, we describe an exceptionally stable hydrated ACC (HACC) precipitated by the cosmopolitan slime mold, Fuligo septica (L.) F.H. Wigg. (1780). A single slime mold can precipitate up to one gram of HACC over the course of one night. Powder x-ray diffraction (XRD) patterns, transmission electron microscopy (TEM) images, infrared absorption (IR) spectra, and lack of optical birefringence are consistent with an amorphous material. XRD simulations supported by thermogravimetric (TG) and evolved gas analysis (EGA) data suggest an intimate association of organic matter with ~1-nm-sized ACC units that have monohydrocalcite- and calcite-like nano-structural properties. It is postulated that this association imparts the extreme stability of the HACC by preventing loss of H2O and subsequent crystallization. The composition, structure, and thermal behavior of the HACC precipitated by F. septica collected over 8000 km apart, and in markedly different environments, suggests a common structure, as well as similar biochemical and biomineralization mechanisms for the HACC formation.

About the Dominance of Mesopores in Physisorption in Amorphous Materials

Amorphous, porous materials represent by far the largest proportion of natural and men-made materials. Their pore networks consists of a wide range of pore sizes, including meso- and macropores. Within such a pore network, material moisture plays a crucial role in almost all transport processes. In the hygroscopic range, the pores are partially saturated and liquid water is only located at the pore fringe due to physisorption. Therefore, material parameters such as porosity or median pore diameter are inadequate to predict material moisture and moisture transport. To quantify the spatial distribution of material moisture, Hillerborg’s adsorption theory is used to predict the water layer thickness for different pore geometries. This is done for all pore sizes, including those in the lower nanometre range. Based on this approach, it is shown that the material moisture is almost completely located in mesopores, although the pore network is highly dominated by macropores. Thus, mesopores are mainly responsible for the moisture storage capacity, while macropores determine the moisture transport capacity, of an amorphous material. Finally, an electrical analogical circuit is used as a model to predict the diffusion coefficient based on the pore-size distribution, including physisorption.

Hydrothermal assisted conventional sol-gel method for synthesis of bioactive glass 70S30Cы

Bioactive glasses (Bioglasses) are widely synthesized by the conventional sol-gel method consisting of two main steps for sol and gel formation. However, the conversion from sol to gel requires a long time (5–7 days). In this study, the hydrothermal system was used to quickly synthesize the bioactive glass by reducing the conversion time from sol to gel. The hydrothermal assisted conventional sol-gel method was applied for synthesis of the bioactive glass 70SiO2–30CaO (mol%) (noted as 70S30C). The synthetic glass was investigated by the physical-chemical techniques. The ‘‘in vitro’’ experiments in SBF (Simulated Body Fluid) solution was also performed to evaluate the bioactivity of synthetic material. The obtained results show that the bioactive glass 70S30C was successfully elaborated by using the hydrothermal assisted conventional sol-gelmethod. The consuming time was reduced compared to the conventional method. The physical-chemical characterization confirmed that the synthetic glass is amorphous material with mesoporous structure consisting of interconnected particles.The specific surface area, pore volume and average pore diameter of synthetic glass were 142.8 m2/g, 0.52 cm3/g, and 19.1 nm, respectively. Furthermore, synthetic bioactive glass exhibited interesting bioactivity when immersed in simulated body fluid (SBF) solution for 1 days and good biocompatibility when cultured in cellular media.

Effect of Calcination on the Chemical and Microstructural Properties of Rice Husk Ash

This research study is aimed to evaluate the effects of different calcination temperatures on the properties of rice husk ash such as the chemical and microstructural properties. Rice husk ash is not utilized properly; it is not dumped with proper handling which is also causing environmental issues. Currently researchers are working on supplementary cementitious materials in concrete, in light of which, this research study is aimed to evaluate the effects of burning on Rics Husk Ash (RHA) structure and its pozzolanic reactivity for utilizing it in concrete. The rice husk is burnt at temperatures of 600-800°C for a duration of 8, 16 and 24 hours and for evaluating different chemical and structural properties through tests of X-ray Diffraction (XRD), X-Ray fluorescence (XRF) and Fourier Transform Infrared Spectroscopy (FTIR). It is concluded that burning of rice husk at 600-800°C for duration of 24 hours gives us more reactive and amorphous material and can be used as a cement substitute for sustainable concrete production.

Lamellar Hole-associated Epiretinal Proliferation in choroideremia: a case report

Background To report a clinical case of a patient affected with choroideremia (CHM) who underwent macular surgery for a macular hole (MH) with Lamellar Hole-associated Epiretinal Proliferation (LHEP). Case presentation We have described a 48-year-old male patient affected with CHM who developed MH with LHEP over a 7-year follow-up. The patient was referred to the Regional Center for Hereditary Retinal Degenerations of the Eye Clinic in Florence (Italy) in April 2012. The patient underwent vitrectomy and Inner Limiting Membrane (ILM) and LHEP peeling with fluid-air exchange. Ultra-structural examination of the excised epiretinal proliferation, carried out using electron microscopy, showed dense amorphous material, mainly composed of abundant clusters of fibrous collagens resembling compact fibrous long spacing collagen (FLSC), embedded in native vitreous collagen (NVC) and type IV collagen. No cells were detected in any of the specimens collected. At the 3rd-week postoperative follow-up the macular hole was closed. Conclusion Macular hole with LHEP can be detected in CHM patients; in our patient the macular hole showed tractional and degenerative features, with good anatomical results after macular surgery.

Experimental Analysis of Partial Replacement of Glass Powder and Fly Ash with Different-Different Percentages of Cement to Improve the Compressive and Flexural Strength of Concrete

The ordinary material for construction is concrete in India and its production causes some environmental effects during the production. There are many countries seeing deficiency of human dumping wastes or it’s becoming very serious day by day for each nation. In order to deal with atmospheric impact related with cement manufacturing and so there is a requirement to produce an alternative binding material for preparing concrete. The development of concrete could reducing the utilization of naturally occurring sources or lesser the load of pollutants on atmosphere. In current scenario, no. of researchers have recognized the uses of additional cementing materials like silica fumes, fly ash, glass powder, rice husk ash, blast furnace slag etc. It could also change the different properties of hardened and freshen state of concrete, and also contributing the financial system in constructional cost. Efforts put on the concrete construction to mix fly ash and waste glass powder as half substitute with cement .Now a days Glass used in different way in day-to-day life. As glass is non-biodegradable, landfills don’t provided an environmental eco-friendly resolution for dumping. Fly ash containing large amount of silica in comparison to cement. In current scenerio lots of industries producing more quantity of fly ash or its sold out very cheapest price in market. Glass is an inert material which could be recycled and used several times without altering its chemical property. Glass is an amorphous material which having high % of silica content. This property makes it probable pozzolanic property when its particles sizes is less than 75 mm. An important anxiety related to the uses of glass powder in concrete mix is that is chemical reaction happen among the alkali in pore solution and silica rich glass particle, which is called Alkali-Silicate. Reactions could be more harmful for the stability parameters of concrete, for this proper safety measure should be taken to reduce its effects. The addition of fly ash in glass concrete reducing the alkalies, silica reaction and improves the workability and durability of concrete. Unwanted glass powder is using for preparing concrete which leads environmental ecofriendly. The main purpose of this study is to find out effectiveness on durability of unwanted glass powder and fly ash based concrete. For analysis it was proposed that the uses of unwanted glass powder and fly ash as half substitution with cement in following proportion (10%, 20%, 30%, 40%) in concrete mix. Compressive strengthening of cubes and flexural strengthening of beams at the interval of 7th, 28th days were considered and compared with the conventional concrete. The results showing the probability of using unwanted glass powder and fly ash as half substitution with cement in concrete. Keywords: Silica fumes, Blast furnace, Rice husk, Glass powder, Fly ash, Compressive strengthening, Flexure strengthening