Search Results (42)

In this work, micro Zn-doped Ga₂O₃ films (GZO) were deposited by one-step mixed atomic layer deposition (ALD) followed by post-thermal engineering. The effects of Zn doping and post-annealing temperature on both structure characteristics and electric properties were investigated in detail. The combination of plasma-enhanced ALD of Ga₂O₃ and thermal ALD of ZnO can realize the fast growth rate (0.62 nm/supercyc.), high density (4.9 g/cm³), and smooth interface (average R_q = 0.51 nm) of Zn-doped Ga₂O₃ film. In addition, the thermal engineering of the GZO was achieved by setting the annealing temperature to 400, 600, 800, and 1000 °C, respectively. The GZO film annealed at 800 °C exhibits a typical crystalline structure (Ga₂O₃: β phase, ZnO: hexagonal wurtzite), a lower roughness (average R_q = 2.7 nm), and a higher average breakdown field (16.47 MV/cm). Notably, compared with the pure GZO film, the breakdown field annealed at 800 °C increases by 180%. The O_V content in the GZO after annealing at 800 °C is as low as 34.8%, resulting in a remarkable enhancement of electrical properties. These research findings offer a new perspective on the high-quality ALD-doped materials and application of GZO in high-power electronics and high-sensitive devices. Full article

Thermal barrier coating can effectively reduce the temperature of engine piston substrates. However, traditional YSZ coating materials are prone to sintering under high-temperature conditions, resulting in coating failure. To address this issue, finite element simulation of a type of new coating was conducted. Gd₂Zr₂O₇ (GZO), a material with strong anti-sintering properties, was selected as a potential candidate for the design of a dual-ceramic layer thermal barrier coating. A GZO/YSZ-coated piston of a diesel engine was designed, and its mechanical/thermal behavior was simulated by a finite element model. A piston surface temperature experiment was conducted to validate the finite element model. The temperature and the thermal stress of the GZO/YSZ dual-ceramic layer coated piston were analyzed by finite element simulation software ANSYS 2023. The results showed that the GZO/YSZ dual-ceramic layer coating effectively reduced the substrate temperature and showed potential for improving the thermal efficiency of the engine. However, due to the properties of GZO and the structure of the coating, the surface stress of the GZO/YSZ dual-ceramic layer coating was relatively high, requiring further studies to verify its reliability. Full article

In this paper, the sensitivity to sub-ppm NO₂ concentration of 50 nm thick Ga-doped ZnO (GZO) films grown by RF magnetron sputtering is studied. The films were annealed under dry air for 4 h at either 500 °C, 600 °C, or 700 °C. The increase in the annealing temperature leads to an improvement of the crystallinity while no significant evolution of the surface grain size is observed. The electrical resistance of the thin films was measured at 250 °C under neutral argon atmosphere, humid air reference atmosphere, and reference atmosphere polluted by 100 ppb of NO₂. An increase in sensitivity to NO₂ is noted for samples annealed at 600 °C, leading to a response R_NO2/R_air of ~10 for 100 ppb of NO₂. Finally, photoluminescence spectra are compared with their electrical resistance at 250 °C under the various atmospheres to understand this phenomenon. It is proposed that the origin of the NO₂ maximum sensitivity for films annealed at 600 °C is the consequence of a specific annihilation of point defects resulting in an increase in the relative concentration of oxygen vacancies, which improves selectivity toward NO₂. Full article

Gadolinium zirconate (Gd₂Zr₂O₇, GZO) has been investigated for two decades as a thermal barrier coating (TBC) material in gas turbines. The advantages of this material over conventional yttria-stabilized zirconia (YSZ) are its lower thermal conductivity, phase stability, and low sintering tendency at elevated temperatures above 1200 °C. However, a major disadvantage is the low fracture toughness of the material and the reaction with the thermally growing oxide layer (TGO). As a result, single-layer GZO coatings cannot be used as TBCs. To overcome these challenges, the present study focuses on the development of double-layer TBC systems, produced with a single gun to keep the manufacturing time low. The respective layers were optimized for specific requirements using a porous atmospheric plasma spray (APS)-YSZ interlayer covered by a suspension plasma sprayed (SPS)-GZO top layer. In furnace cycling tests at 1100 °C, the double-layer systems developed in this study were able to achieve a significant increase in thermal cycle life compared to single-layer APS-YSZ coatings. In addition, the failure mechanism after thermal cycling was investigated, and phase analysis was performed using XRD. The examination of Young’s modulus and the hardness of the layers revealed sintering in the GZO layer due to thermal cycling, while the APS layer showed only minor changes. Full article

Objective: This study develops a BI-RADS-like scoring system for vascular microcalcifications in mammographies, correlating breast arterial calcification (BAC) in a mammography with coronary artery calcification (CAC), and specifying differences between microcalcifications caused by BAC and microcalcifications potentially associated with malignant disease. Materials and Methods: This retrospective single-center cohort study evaluated 124 consecutive female patients (with a median age of 57 years). The presence of CAC was evaluated based on the Agatston score obtained from non-enhanced coronary computed tomography, and the calcifications detected in the mammography were graded on a four-point Likert scale, with the following criteria: (1) no visible or sporadically scattered microcalcifications, (2) suspicious microcalcification not distinguishable from breast arterial calcification, (3) minor breast artery calcifications, and (4) major breast artery calcifications. Inter-rater agreement was assessed in three readers using the Fleiss’ kappa, and the correlation between CAC and BAC was evaluated using the Spearman’s rank-order and by the calculation of sensitivity/specificity. Results: The reliability of the visual classification of BAC was high, with an overall Fleiss’ kappa for inter-rater agreement of 0.76 (ranging between 0.62 and 0.89 depending on the score). In 15.1% of patients, a BAC score of two was assigned indicating calcifications indistinguishable regarding vascular or malignant origin. In 17.7% of patients, minor or major breast artery calcifications were found (BAC 3–4). BAC was more prevalent among the patients with CAC (p < 0.001), and the severity of CAC increased with the BAC score; in the group with a BAC score of one, 15% of patients exhibited mild and severe CAC, in those with a BAC of two, this was 31%, in those with BAC of three, this was 38%, and in those with a BAC of four, this was 44%. The sensitivity for detecting CAC, based on the mammographic BAC score, was 30.3% at a specificity of 96.7%. Conclusions: The standardized visual grading of BAC in mammographies on a four-point scale is feasible with substantial interobserver agreement, potentially improving the treatment of patients with suspicious microcalcifications and CAC. Full article

In DCE-MRI, the degree of contrast uptake in normal fibroglandular tissue, i.e., background parenchymal enhancement (BPE), is a crucial biomarker linked to breast cancer risk and treatment outcome. In accordance with the Breast Imaging Reporting & Data System (BI-RADS), it should be visually classified into four classes. The susceptibility of such an assessment to inter-reader variability highlights the urgent need for a standardized classification algorithm. In this retrospective study, the first post-contrast subtraction images for 27 healthy female subjects were included. The BPE was classified slice-wise by two expert radiologists. The extraction of radiomic features from segmented BPE was followed by dataset splitting and dimensionality reduction. The latent representations were then utilized as inputs to a deep neural network classifying BPE into BI-RADS classes. The network’s predictions were elucidated at the radiomic feature level with Shapley values. The deep neural network achieved a BPE classification accuracy of 84 ± 2% (p-value < 0.00001). Most of the misclassifications involved adjacent classes. Different radiomic features were decisive for the prediction of each BPE class underlying the complexity of the decision boundaries. A highly precise and explainable pipeline for BPE classification was achieved without user- or algorithm-dependent radiomic feature selection. Full article

In this work, gallium-doped zinc oxide was deposited with a Radio Frequency Magnetron sputtering method on test platforms. The NO₂ sensing properties of the resulting devices were studied. The sensing properties of ZnO:Ga thin films were successfully stabilized through annealing in dry air, and then improved by either a thinning of the layer or an increase in the roughness of the substrate. The sensing response with an Rgas/Rair of 15 for 100 ppb of NO₂ under 50% humidity was obtained, with a response time below 10 min. Full article

Co-doped ZnO thin films have attracted much attention in the field of transparent conductive oxides (TCOs) in solar cells, displays, and other transparent electronics. Unlike conventional single-doped ZnO, co-doped ZnO utilizes two different dopant elements, offering enhanced electrical properties and more controllable optical properties, including transmittance and haze; however, most previous studies focused on the electrical properties, with less attention paid to obtaining high haze using co-doping. Here, we prepare high-haze Ga- and Zr-co-doped ZnO (GZO:Zr or ZGZO) using atmospheric pressure plasma jet (APPJ) systems. We conduct a detailed analysis to examine the interplay between Zr concentrations and film properties. UV-Vis spectroscopy shows a remarkable haze factor increase of 7.19% to 34.8% (+384%) for the films prepared with 2 at% Zr and 8 at% Ga precursor concentrations. EDS analysis reveals Zr accumulation on larger and smaller particles, while SIMS links particle abundance to impurity uptake and altered electrical properties. XPS identifies Zr mainly as ZrO₂ because of lattice stress from Zr doping, forming clusters at lattice boundaries and corroborating the SEM findings. Our work presents a new way to fabricate Ga- and Zr-co-doped ZnO for applications that require low electrical resistivity, high visible transparency, and high haze. Full article

This study presents gallium-doped zinc oxide (ZnO:Ga, GZO) thin films. GZO thin films with both high transparency and low sheet resistance were prepared by RF sputtering and then post-annealed under nitrogen and hydrogen forming gas. With post-annealing at 450 °C, the proposed films with a film thickness of 100 nm showed high transparency (94%), while the sheet resistance of the films was reduced to 29 Ω/square, which was comparable with the performances of commercial indium tin oxide (ITO) samples. Post-annealing under nitrogen and hydrogen forming gas enhanced the films’ conductivity while altering the thin-film composition and crystallinity. Nitrogen gas played a role in improving the crystallinity while maintaining the oxygen vacancy of the proposed films, whereas hydrogen did not dope into the thin film, thus maintaining its transparency. Furthermore, hydrogen lowered the resistance of GZO thin films during the annealing process. Then, the detailed mechanisms were discussed. Hydrogen post-annealing helped in the removal of oxygen, therefore increasing the Ga³⁺ content, which provided extra electrons to lower the resistivity of the films. After the preferable nitrogen/hydrogen forming gas treatment, our proposed films maintained high transparency and low sheet resistance, thus being highly useful for further opto-electronic applications. Full article

Obstructive sleep apnea (OSA) is well known to often improve with non-supine positioning as opposed to supine positioning. Emerging research supports a role for sleep position management in patients with central sleep apnea (CSA) as well. We report a case of de novo complex sleep apnea syndrome (CompSAS) in a 78-year-old female, who presented after a car accident due to unclear syncope. Diagnostic polysomnography (PSG) showed moderate OSA. A CompSAS developed under automatic positive airway pressure (APAP), while 4 years of downloaded data showed good adherence. No significant benefit was reported under adaptive servo ventilation (ASV) and BiPAP-ST, while a reduction in CSA in the non-supine position was noticed. Oxygen and sleep positional therapy (SPT) were considered, resulting in a significant improvement in CSA and sleep quality. Further research on the prevalence of positional CSA is needed. Full article

Gallium-doped ZnO (GZO) thin films on glass, which can be used as transparent electrodes, were prepared using a spin coating technique. Thermal analysis and Fourier-transform infrared spectroscopy of the dried precursor solution of Zn acetate and Ga nitrate dissolved in ethanol with diethanolamine confirmed the decomposition of the organic components upon heating and the formation of ZnO at 450 °C. The thin films fired at 600 °C in oxygen and air, and the films annealed at 400 °C in Ar/H_2, were polycrystalline, 140 nm thick, and exhibited a homogeneous microstructure with 50 nm grains and a smooth surface, as shown by X-ray powder diffraction and scanning electron and atomic force microscopy. The sheet resistance R_s measured using the 4-probe technique showed a change in R_s within 80 days for all samples. The R_s of the GZO thin films annealed in oxygen and air with values of MΩ/sq decreased over time. R_s values of 150 kΩ/sq were obtained for GZO thin films annealed in Ar/H₂, but the R_s increased over time. We suggest that the degradation of R_s is related to the adsorption of water on GZO and that the responses depend on the nature of the defects in the GZO lattice. Full article

Rare-earth zirconates are proven to be very effective in restricting the CMAS attack against thermal barrier coatings (TBCs) by forming quick crystalline reaction products that seal the porosity against infiltration. The microstructural effects on the efficacy of Electron Beam-Physical Vapor Deposition gadolinium zirconate (EB-PVD GZO) against CMAS attack are explored in this study. Four distinct GZO microstructures were manufactured and the response of two selected GZO variants to different CMAS and volcanic ash melts was studied for annealing times between 10 min and 50 h at 1250 °C. A significant variation in the microstructural characteristics was achieved by altering substrate temperature and rotation speed. A refined microstructure with smaller intercolumnar gaps and long feather arms lowered the CMAS infiltration by 56%–72%. Garnet phase, which formed as a continuous layer on top of apatite and fluorite, is identified as a beneficial reaction product that improves the CMAS resistance. Full article

Thin films of gallium-doped zinc oxide (GZO), with a thickness of around fifty nanometers were deposited on bio-based poly(ethylene furanoate) (PEF) substrates by radio-frequency sputtering. By optimizing the Ga concentration in the target, the optics, water vapor barrier and antibacterial properties of PEF/GZO composite films can be adjusted. The highest visible light transmittance of the samples was around 85.1%. Furthermore, by introducing some GZO films with typical concentrations, the water vapor barrier and antibacterial properties of PEF films were improved. The optimized water vapor permeability of PEF/GZO composite film was 5.3 × 10⁻¹² g·m/m²·s·Pa, and the highest antibacterial rate can reach 99.85% after 4 h. By XPS analysis, the antibacterial mechanism in the samples is envisaged to be mainly due cytotoxicity of Ga ions. The above results indicate that PEF/GZO films have great potential in the field of antibacterial food packaging. Full article

Heterojunction light-emitting diodes (LEDs), based on p-type ZnO and n-type ZnMgO nanoparticles, have been demonstrated. ZnMgO nanoparticles were prepared by the thermal diffusion of Mg onto ZnO nanoparticles. p-ZnO/GZO homostructure LEDs and p-ZnO/n-ZnMgO/GZO heterostructure LEDs have been fabricated using ZnO and ZnMgO nanoparticles. By comparing the characteristic results of these diodes, it can be seen that LEDs with the p-ZnO/n-ZnMgO/GZO structure showed better I–V characteristics with a lower current density leakage than those with the p-ZnO/GZO LED structure. Moreover, the emission intensity was improved by adding the ZnMgO NP layer to the LEDs. These results show that the ZnMgO NP layer acts as a hetero-barrier layer that suppresses the diffusion of holes into the n-type layer and confines holes to the p-type layer. Full article

Background: Medical progress is increasingly enabling more and more stationary treatment to be provided in the outpatient sector. This development should be welcomed, as healthcare costs have been rising for years. The design of efficient processes and a needs-based infrastructure enable further savings. According to international recommendations (EHS/IEHS), outpatient treatment of unilateral inguinal hernias is recommended. Method: Data from patients in GZO Hospital Wetzikon/Zurich between 2019 and 2021 for unilateral inguinal hernia repair was included in this study (n = 234). Any over- or under-coverage correlated with one of the three treatment groups: stationary, partially stationary and patients treated in outpatients clinic. Complications and 30-day readmissions were also monitored. Results: Final revenue for all patients is −95.36 CHF. For stationary treatments, the mean shifts down to −575.01 CHF, for partially stationary treatments the mean shifts up to −24.73 CHF, and for patients in outpatient clinic final revenue is 793.12 CHF. This result is also consistent with the operation times, which are lowest in the outpatient clinic with a mean of 36 min, significantly longer in the partially stationary setting with 58 min, and longest in the stationary setting with 76 min. The same applies to the anesthesia times and the relevant care times by the nurses as the most important cost factors in addition to the supply and allocation costs. Conclusions: We show that cost-effective elective unilateral inguinal hernia care in the outpatient clinic with profit (mean 793.12 CHF) is possible. Stationary unilateral hernia care (mean −575.01 CHF) is loss-making. Crucial factors for cost efficiency are optimized processes in the operating room (anesthesia, surgical technique and quality, operating time), as well as optimized care processes with minimal preoperative services and care times for the patient. However, at the same time, these optimizations pose a challenge to surgical and anesthesiology training and structures with high levels of preoperative and Postoperative services and pay-as-you-go costs. The complication rate is 0.91% lower than in a comparable study. The readmission within 30 days post-operation results with a positive deviation of −3.53% (stationary) and with a negative deviation of +2.29% (outpatient clinic) compared to a comparative study. Full article