Ultrastructural pathology of bioprosthetic heart valves with infectious endocarditis

Aim. To study the ultrastructure of mitral bioprosthetic heart valves (BHVs) which failed due to infective endocarditis.Materials and Methods. Here we examined 7 ethylene glycol diglycidyl ether-treated xenopericardial BHVs excised during repeated BHV replacement because of prosthetic endocarditis. After being fixed in formalin and postfixed in osmium tetroxide, BHVs were dehydrated and stained in uranyl acetate with the subsequent embedding into epoxy resin, grinding, polishing, and lead citrate counterstaining. Upon the sputter coating with carbon, we visualised the BHV microanatomy by means of backscattered scanning electron microscopy at 15 kV voltage.Results. The extracellular matrix underwent degradation and disintegration resulting in loosening, fragmentation, and reduction in the electron density of collagen and elastin fibers. We observed a number of recipient cells (macrophages, multinucleated giant cells, neutrophils, endothelial cells and smooth muscle cells) within the BHVs. The highest number of cells was localized on the valve surfaces. The localization of the recipient cells on the ventricular and atrial surfaces was different. The central part of the valves was abundantly populated by macrophages.Conclusion. Prosthetic endocarditis is accompanied by the migration of recipient cells into the BHV structure, which is the consequence of surface and extracellular matrix disintegration.

Development, Characterisation and High-Temperature Suitability of Thin-Film Strain Gauges Directly Deposited with a New Sputter Coating System

New sensor and sensor manufacturing technologies are identified as a key factor for a successful digitalisation and are therefore economically important for manufacturers and industry. To address various requirements, a new sputter coating system has been invented at the Institute of Micro Production Technology. It enables the deposition of sensor systems directly onto technical surfaces. Compared to commercially available systems, it has no spatial limitations concerning the maximum coatable component size. Moreover, it enables a simultaneous structuring of deposited layers. Within this paper, characterisation techniques, results and challenges concerning directly deposited thin film strain gauges with the new sputter coating system are presented. Constantan (CuNiMn 54/45/1) and NiCr 80/20 are used as sensor materials. The initial resistance, temperature coefficient of resistance and gauge factor/k-factor of quarter-bridge strain gauges are characterised. The influence of a protective layer on sensor behaviour and layer adhesion is investigated as well. Moreover, the temperature compensation quality of directly deposited half-bridge strain gauges is evaluated, optimised with an external trimming technology and benchmarked against commercial strain gauges. Finally, the suitability for high-temperature strain measurement is investigated. Results show a maximum operation temperature of at least 400 °C, which is above the current state-of-the-art of commercial foil-based metal strain gauges.

Surface Modification of Bacterial Cellulose by Copper and Zinc Oxide Sputter Coating for UV-Resistance/Antistatic/Antibacterial Characteristics

In our study, the surface of bacterial cellulose was successively modified by copper and zinc oxide nanoparticles using direct current (DC) magnetron sputtering and radio frequency (RF) reactive sputter coating techniques. The target materials, copper and zinc, were 99.99% pure and used in the presence of argon (Ar) gas, while zinc nanoparticles were sputtered in the presence of oxygen gas to make zinc oxide nanoparticles. The as-prepared bacterial cellulose/copper/zinc oxide nanocomposite has good ultraviolet resistance, anti-static and antibacterial characteristics. The surface morphology and chemical composition of the nanocomposite were examined by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopic (EDS) techniques. The prepared bacterial cellulose/copper/zinc oxide nanocomposite illustrates excellent ultraviolet resistance (T.UVA%; 0.16 ± 0.02, T.UVB%; 0.07 ± 0.01, ultraviolet protection factor (UPF); 1850.33 ± 2.12), antistatic behavior (S.H.P; 51.50 ± 4.10, I.E. V; 349.33 ± 6.02) and antibacterial behavior (Escherichia coli; 98.45%, Staphylococcus aureus; 98.11%). Our nanocomposite prepared by sputter coating method could be a promising and effective candidate for ultraviolet resistance, antistatic and antibacterial in term of functional, technical, medical and in many daily life applications.

Bird safety coating for architectural and commercial applications

Scientific observations conclude that modern buildings can cause a high number of bird deaths due to birds’ collision with glass windows and glass walls. There are many efforts to put bird-deterrent patterns on glass in order to avoid bird collision. To make the patterns environment-friendly and meanwhile invisible for human eye, we developed a special “first surface PVD coating”. This paper describes a design for bird-deterrent stack from sputter-coating processes, our method to improve the contrast ratio between coated and uncoated area, followed by some discussions on the tunnel-test results.

Enhancement Open Circuit Voltage of Calcium Titanate AR Coated Magnesium Solar Cell

The present research aims to enhance the open circuit voltage of fabricated solar cell through Anti–Reflection (AR) coating on the cell substrate. Solar cell is fabricate using ITO Glass, titanium dioxide, magnesium and redox. Calcium Titanium Oxide (CaTiO3) is chosen as the AR coating material for constructing thin film layer on fabricated solar cell. Selected AR coating material have unique features such as orthorhombic, biaxial, non-radioactive and non-magnetic with electron bulk density of 3.91 g/cm3 respectively. Commonly, voltage generation of the multi crystalline solar cell is low (12% to 14%) due to much reflection of inward sun radiation. Deposition of AR coating on the substrate (fabricated solar cell) can minimize the reflection loss of sun radiation. The maximum improvement in solar cell efficiency after AR coating has been reported as 19.3%. Sputter coating technique is more favorable for thin film coating due to its salient features like uniform coating thickness controlled by time. This uniform coating thickness absorbs more sun radiation. Radio Frequency (RF) magnetron sputter coating technique is utilized in the current research to deposit CaTiO3 on solar cells. Prior to coating, the AR material is pelletized using Universal Testing Machine (UTM). The substrate are coated under varying time duration of 15-minutes, 30-minutes and 45-minutes in order to analyze the variation in open circuit voltage. The deposition of coating on the substrate are confirmed using SEM and FESEM. Open circuit voltage of controlled atmosphere studies for pure and AR coated solar cells (fabricated) are examined. Controlled atmosphere tests of AR coated thin films are conducted by placing the substrate inside a solar simulator and the solar simulator consist of IR thermometer (To measure Temperature), solar power meter (To measure Radiation) and multimeter (To measure Open circuit voltage). Neodym daylight lamp is used to control the radiation in solar simulator. The improvement in cell voltage proves that thin film AR coating considerably minimizes the reflective loss.

Sample preparation utilizing sputter coating increases contrast of cellulose nanocrystals in the transmission electron microscope

Cellulose nanocrystals (CNCs) are prepared for transmission electron microscopy (TEM) using positive or negative stains in an effort to increase the contrast between the specimen and background. When imaging CNCs, conventional stains have been shown to induce particle aggregation and produce artifacts. In this study, we report on methods used to image CNCs. To increase contrast and decrease artifacts and aggregation, sputter coating was used to coat the samples. CNCs were loaded onto copper grids and sputter coated with one of four different metals: iridium, carbon, gold, and titanium. The final layer was deposited at 5 nm to ensure surface homogeneity. The thin layer of conductive metal atoms deposited onto the specimen surface significantly increased contrast and improved image quality. The results presented here demonstrate the advantages of using sputter coating for imaging of highly crystalline cellulose materials with TEM.