In this study, polymer composite films were prepared by the solution casting method using ceramic filler barium titanate (BT) to enhance the mechanical and dielectric properties of polyvinylidene fluoride (PVDF). A silicon dioxide (SiO2) shell was coated on BT surface by hydrolysis reaction of tetraethyl orthosilicate (TEOS) at different concentrations in order to provide a strong interface between PVDF and BT. The influence of SiO2 coating on morphology, structure, thermal, tensile and dielectric properties of composites were investigated compared to neat PVDF. The results of analyses show that SiO2 is successfully coated on BT and that the ceramic filler enhances the tensile and dielectric properties of the composites. At low BT concentrations (5 and 10 vol.%) the tensile strength and Young modulus are improved compared to neat PVDF. For films having a high content of SiO2, in particular, coated BT high values, such as 24.8 at 102 Hz are found for the dielectric constant, which is greatly improved by almost 2.3 times compared to neat PVDF. Properties, such as flexibility and thermal stability, are well retained in the prepared composites.

Despite the latest technologies and advances in microbiology and orthopedic surgery, chronic osteomyelitis is still a challenging disorder. Antibiotic resistance and bacterially induced bone destruction can have very serious consequences. We hypothesized that calcium phosphate-based bone graft substitution with silver ion doping would simultaneously treat bone infection and the bony defect in the chronic osteomyelitis. An unicortical 10-mm-diameter bone was harvested in the proximal tibial metaphysis of 24 rabbits. After contaminating the wounds with an infective dose of methicillin-resistant Staphylococcus aureus (MRSA), osteomyelitis was proven radiographically and microbiologically in all rabbits. Animals were than divided into three groups. The first group received vancomycin-impregnated bone cement beads (comparative control group), the second/experimental group received silver ion-doped calcium phosphate beads and the third group received pure calcium phosphate beads (negative controls). Radiographs, intraosseous cultures, and histopathological examinations were performed on postoperative Week 10. The cultures showed no evidence of intramedullary infection in the silver ion-doped calcium phosphate beads group, but they were positive for MRSA in four of the six rabbits in the vancomycin- impregnated bone cement beads group and in all of the eight rabbits in the pure calcium phosphate beads group. Quantitative assessment of histopathological examination showed lowest total damage score in silver ion-doped calcium phosphate beads group (p < .001). Percentage of osteoid tissue + bony tissue was also higher in this group compared with other groups. In the final radiological examinations, it was observed that the changes caused by osteomyelitis in the bone tissue in the silver ion-doped calcium phosphate beads group were much improved compared with the vancomycin-impregnated bone cement beads group. Silver ion doped calcium phosphate-based bone-graft substitute offer the ability to stimulate bone growth, combat infection, and, ultimately, treat experimental chronic osteomyelitis in an animal model.

In this study, piezoelectric based compressive type accelerometer has been de-signed by using PZT-5A ceramics with bellewasher type spring. FEA analysis were carried out by using COMSOL. According to COMSOL simulation, reso-nance frequency is nearly 42500 Hz. Sensitivity of the designed sensors were measured and compared each other. Frequency spectrum was between 100Hz-10 kHz. The effects of piezodisk thickness, stiffness of the spring and seismic mass on the sensitivity of the designed sensor were investigated. Voltage output is in-creasing from 4.1 mV/g to 12.7 mV/g while seismic mass is raised from 3 gr to 10 gr. Linearity depending on the frequency of the designed accelerometer was dis-torted above 5.5 kHz like commercial accelerometer. In addition, real-time tests were performed using a calibrated accelerometer and a designed accelerometer on the internal combustion engine and drivetrain. Vibration profiles were carried out randomly. According to the results obtained here, it is observed that all the peaks were matched with a coefficient about 1.3.

In the use of piezocermic applications, piezoceramic compositions have high d33 (>500 pC/N) and Kt (2000) such as PZT-5H. However, these ceramics can be sintered at high temperatures up to 1200˚C). Since these require the use of Ag-Pd inner electrodes with higher Pd ratio, multilayer ceramics are not preferred due to their high costs. In this study, it was aimed to reduce the sintering temperature without dramatically losing the electrical properties of the PZT-5H ceramics with high d33, kp and dielectric constant values. In this context, the PZT-5H composition was modified with different proportions of Li2CO3 and sintered for 2-4 hours at different sintering temperatures such as 875˚C-1250˚C depending on the ratio of additions. The piezoelectric and ferroelectric properties of the ceramics were investigated and obtained values were compared with undoped PZT-5H. It was observed that the d33 values of the different amount of Li2CO3 added compositions sintered at optimum sintering temperature are close that the composition without additives. In this way, it is predicted that 9/1 Ag/Pd and Ag inner electrode materials can be used in multilayer production and their costs can be reduced.

Although the cleaner surgical environment, antibiotic use, and surgical asepsis-antisepsis have reduced the incidence of infections during surgery, the risk of implant-related infections is still high. Surgical site infections, a common complication after all surgical procedures, are usually caused by the exogenous and endogenous microorganisms that enter the wound during the surgical procedure. It is a potential complication associated with any type of procedure and is among the most preventable health care-associated infection. Surgical site infections are usually localized to the incision site, but may extend into deeper structures, including musculoskeletal tissues. In orthopedic surgery the ability of the implants (joint prosthesis, intramedullary nail, external fixator, etc.) to be used for many years depends mainly on the integration of the implant with the bone and no infection in the surrounding areas. The ideal antimicrobial agent for infections should be able to reach high local concentrations without causing systemic toxicity and should not interfere with bone regeneration and implant integration with biological tissues. Despite the use of very high doses of antibiotics for implant-related infections, a relatively lower drug concentration was achieved at the target site and the success rate was not high. Since implant-related infections occur mainly in the tissues directly surrounding the implant surface, it is wiser to transport antimicrobials locally to prevent and treat these infections. Methods that prevent microbes from adhering to the surface of the implant are preferred for the prevention of infections. Given the high risk of antibiotic resistance associated with antibiotic-loaded coatings and other problems, nonantibiotic substances are a much more attractive alternative. Among the various substances, silver ion is a substance that, come forward because it prevents bacterial attachment, its broad antibacterial spectrum (both Gram negative and positive bacteria) has a long-term antibacterial effect and is less prone to resistance development.

© 2020. The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (CC BY-NC 4.0, https://creativecommons.org/licenses/by-nc/4.0/deed.en which permits the use, redistribution of the material in any medium or format, transforming and building upon the material, provided that the article is properly cited, the use is noncommercial, and no modifications or adaptations are made. Arch. Metall. Mater. 65 (2020), 2, 609-614

In this study, lead-free 94Bi0,5Na0,5TiO3 -6BaTiO3 (94NBT-6BT) ceramics were fabricated by solidstate synthesis method at ambient atmosphere.Glassy phase and rounded particles in 94NBT-6BT was observed with increasing Mn content.The effects of doping manganese on the ferroelectric properties of 94NBT-6BT bulk ceramics were evaluated.From the XRD results of the calcined powders, peaks were slightly changed to higher 2 theta value while increasing manganese ratio.Multivalence additive Mn ions act as acceptor dopant in 94NBT-6BT structure at ambient atmosphere.Samples were sintered from 1075°C to 1175°C for 2 hours to obtain highest piezoelectric values.SEM results show that glassy phase and rounded particles in 94NBT-6BT was observed with increasing Mn content so, bulk density was enhanced up to 1125C.From the results, 0.3 wt% manganese doped 94NBT-6BT samples have highest electromechanical coupling factor about 0.23, mechanical coupling factor (Qm) 150 and d33 110 pC/N respectively.Further work, 94NBT-6BT and Mn-doped 94NBT-6BT multilayer actuators were manufactured by water-based tape casting technique.The active area was 49 mm 2 MLA and was fabricated by using Ag-Pd internal electrode without Pd-Bi reaction at the electrode-ceramic interface.Hysterisis loop measurements of manufactured lead free actuators were done by using Aixacct CMA module.Remnant polarization values of Mn-doped 94NBT-6BT MLA for a layer were higher than 6 µC/cm 2 .

This study proposed a unique wideband energy harvester with a spiral metal plate design which has the potential to harvest vibrational energy over a broad range of ambient frequencies. In this design, metal shim with various length was integrated with piezoceramic rings in a spiral form as the cochlea. Spiral form metal shims with various radius leaves were integrated with piezoelectric ceramic. Each metal leaves has its resonance frequency that is slightly different than its neighboring ones. Parametric studies such as split structure, the radius of the metal shim, brass thickness, and tip mass and clamped area were performed to investigate the energy harvester structure. From the results, the buzzer form energy harvesting unit is designed to split leaf form, resonance frequency shifts to lower frequency. In split structure design for various leaf radius, every leaf keeps their resonance frequencies. This designed structure was resonated on the broader frequency range. Radius difference for neighbor leaves provided wider effective energy harvesting frequency range. Thicker brass shim led to higher stress on piezoelectric ceramic, more significant peak to peak output voltage at own resonance frequency.

In this study, lead free 94Na0.5Bi0.5TiO3-6BaTiO3 (94NBT-6BT) single crystals were successfully grown by flux growth technique. Morphology of the grown crystals with dimension of nearly 3x3x3 mm was characterized by stereo and scanning electron microscopy (SEM). Elemental characterization were evaluated with energy dispersive X-ray (EDX) and X-ray fluorescence (XRF) methods. Crystalline phase of the samples were analyzed by X-ray diffraction (XRD) techniques. The crystallographic analyses show that the 94NBT-6BT single crystal indicates rhombohedral-tetragonal phase at room temperature. Electrical characterization exhibited that the room temperature dielectric constant for unpoled crystal sample was nearly 1030 at 1kHz and it decreased to 800 after poling depend on the poling electric field. Also, dielectric constant was changed between 1030 to 900 as a function of frequencies. Piezoelectric constant d33 of the crystals were obtained 65, 83, 114pC/N at 3-4-5 kV/mm poling condition, respectively.

Long-term survival and favourable outcome of implant use are determined by bone-implant osseointegration and absence of infection near the implants. As with most diseases, prevention is the preferr...

Inguinal hernia repairs are the most common interventions in adults in general surgery clinics. Depending on the type of mesh and repair, the incidence of mesh-related infection ranges from 0.6 to 8%. Methicillin-resistant Staphylococcus aureus is the most common microorganism causing graft infection. The aim of this study was to investigate the efficacy of nano-crystalline silver-coated polypropylene grafts against graft infection created with MRSA in rats.

Accelerated Mesenchymal Stem Cells (MSCs) condensation and robust MSC-matrix and MSC-MSC interactions on nano-surfaces may provide critical factors contributing to such events, likely through the orchestrated signal cascades and cellular events modulated by the extracellular matrix. In this study, human adipose tissue derived mesenchymal stem cells (hMSC)', were grown on metal ion (Zn, Ag and Cu) doped hydroxyapatite (HAP) nano-coated surfaces. These metal ions are known to have different chemical and surface properties; therefore we investigated their respective contributions to cell viability, cellular behavior, osteogenic differentiation capacity and substrate-cell interaction. Nano-powders were produced using a wet chemical process. Air spray deposition was used to accumulate the metal ion doped HAP films on a glass substrate. Cell viability was determined by MTT, LDH and DNA quantitation methods Osteogenic differentiation capacity of hMSCs was analyzed with Alizarin Red Staining and Alkaline Phosphatase Specific Activity. Adhesion of the hMSCs and the effect of cell adhesion on biomaterial biocompatibility were explored through cell adhesion assay, immunofluorescence staining for vinculin and f-actin cytoskeleton components, SEM and microarray including 84 known extracellular matrix proteins and cell adhesion pathway genes, since, adhesion is the first step for good biocompability. The results demonstrate that the viability and osteogenic differentiation of the hMSCs (in growth media without osteogenic stimulation) and cell adhesion capability are higher on nanocoated surfaces that include Zn, Ag and/or Cu metal ions than commercial HAP. These results reveal that Zn, Ag and Cu metal ions contribute to the biocompatibility of exogenous material.

Mammography and ultrasound are commonly used techniques for detection and follow-up of breast cancer. Microwave induced thermoacoustic imaging is a new non-ionizing imaging modality that can facilitate early detection and follow-up of cancer. Here we present development of an experimental microwave induced thermoacoustic imaging system along with preliminary test results.

In this study, lead-free 94Na(0.5)Bi(0.5)TiO(3)-6BaTiO(3) (94NBT-6BT) piezoelectric ceramics and embedded single crystals in polycrystalline 94NBT-6BT matrix were sintered by conventional (CS) and spark plasma sintering (SPS) techniques. The effects of SPS and CS on the microstructure of the 94NBT-6BT ceramics were discussed and compared. Theoretical density of the CS and SPS treated samples were found to be 94% and almost 99.9%, respectively. High porosity and weak seed-matrix interaction at 1180 degrees C for 2 h were obtained from CS sintered ceramics. On the other hand, sintered samples with SPS showed non-porous polycrystalline matrix, and quite strong seed-matrix interface bonding at 950 degrees C for 5 min. Also, dielectric properties of sintered ceramics with SPS gave better results than CS. Therefore, SPS assisted 94NBT-6BT samples can be used to grow high quality and high performance single crystals using solid state single crystal growth.

BACKGROUND:Despite improvement in operative techniques and antibiotic therapy, septic complications still occur in open fractures. We developed silver ion containing ceramic nano powder for implant coating to provide not only biocompatibility but also antibacterial activity to the orthopaedic implants.QUESTIONS/PURPOSES:We hypothesised silver ion doped calcium phosphate based ceramic nano-powder coated titanium nails may prevents bacterial colonisation and infection in open fractures as compared with uncoated nails.METHODS:33 rabbits divided into three groups. In the first group uncoated, in the second group hydroxyapatite coated, and in the third group silver doped hydroxyapatite coated titanium nails were inserted left femurs of animals from knee regions with retrograde fashion. Before implantation of nails 50 μl solution containing 10(6)CFU/ml methicillin resistance Staphylococcus aureus (MRSA) injected intramedullary canal. Rabbits were monitored for 10 weeks. Blood was taken from rabbits before surgery and on 2nd, 6th and 10th weeks. Blood was analysed for biochemical parameters, blood count, C-reactive protein and silver levels. At the end of the 10 weeks animals were sacrificed and rods were extracted in a sterile fashion. Swab cultures were taken from intramedullary canal. Bacteria on titanium rods were counted. Liver, heart, spleen, kidney and central nervous tissues samples were taken for determining silver levels. Histopathological evaluation of bone surrounding implants was also performed.RESULTS:No significant difference was detected between the groups from hematologic, biochemical, and toxicological aspect. Microbiological results showed that less bacterial growth was detected with the use of silver doped ceramic coated implants compared to the other two groups (p=0.003). Accumulation of silver was not detected. No cellular inflammation was observed around the silver coated prostheses. No toxic effect of silver on bone cells was seen.CONCLUSION:Silver ion doped calcium phosphate based ceramic nano powder coating to orthopaedic implants may prevents bacterial colonisation and infection in open fractures compared with those for implants without any coating.

The electrospray deposition (ESD) of SnO2 films from SnCl4.5H2O precursor solution was performed for gas sensor applications. Deposition time, solution flow rate and solution concentration were the main control parameters in the ESD process. The morphological properties of the deposited films were characterised by scanning electron microscopy. X-ray diffraction and energy dispersive X-ray analyses were employed to confirm the crystal phases and composition of the films. The best coatings with an island of particle agglomerates were observed at a flow rate of 0.12 ml min−1, for 60 min, and at a 0.05M concentration. The crystallisation of SnO2 films was observed at 650°C. The grain size and surface morphology of the films were influenced by the sol concentrations. Larger grain size and cracked surface were observed by increasing the sol concentration. The film thickness of 6 µm and a grain size of less than 100 nm were achieved.

In this study, silicon nitride ceramics (Si3N4) were joined by using a capacitor discharge technique with an Inconel 718 superalloy interlayer and heat-treated in order to determine possible reactions between these two materials. After capacitor discharge joining, some of the samples were heat-treated at 1100 °C under air and the resulting interfacial microstructure was characterized by using a scanning electron microscope (SEM) attached with an energy-dispersive x-ray spectrometer (EDS) and wavelength dispersive x-ray spectrometer (WDS). According to back-scattered electron images (BSE), all the joining samples were well bonded through the interlayer and cracks were not observed along the interlayer, interface and the ceramics. According to point SEM–EDS and SEM–WDS analysis, the reaction layer and nitrogen (N) were not detected but a small amount of silicon (Si) and aluminium (Al) was detected at the interlayer of as-joined samples. For the heat-treated samples at 1100 °C, the symmetrical reaction layer was observed at both sides of the interlayer which is expanding towards the ceramic side and approximately 25-nm-thick another continuous reaction layer next to this was also determined. According to SEM–EDS and SEM–WDS point-line scan analysis along the metallic interface and ceramic side, nickel (Ni), iron (Fe) and chromium (Cr) were detected at the reaction layer next to the ceramic side, whereas mainly Cr, niobium (Nb), molybdenum (Mo), titanium (Ti) and Al were concentrated at the 25-nm-thick reaction layer.