Search Results (162)

This work investigates the impact of an internal electric field on the annihilation characteristics of positrons implanted in a $180\left(10\right)\mathrm{nm}$ SiO₂ layer of a Metal-Oxide-Silicon (MOS) capacitor, using Positron Annihilation Lifetime Spectroscopy (PALS). By varying the gate voltage, electric fields up to $1.72\mathrm{MV}/\mathrm{cm}$ were applied. The measurements reveal a field-dependent suppression of positronium (Ps) formation by up to $64\%$, leading to an enhancement of free positron annihilation. The increase in free positrons suggests that vacancy clusters are the dominant defect type in the oxide layer. Additionally, drift towards the SiO₂/Si interface reveals not only larger void-like defects but also a distinct population of smaller traps that are less prominent when drifting to the Al/SiO₂ interface. In total, by combining positron drift with PALS, more detailed insights into the nature and spatial distribution of defects within the SiO₂ network and in particular near the SiO₂/Si interface are obtained. Full article

Recent advancements in photonics have intensified the performance requirements for optical systems and present significant challenges for optical coating technologies. Conventional interference coating systems often prove to be insufficient, especially in applications requiring large angles of light incidence or a wide wavelength range. Nanostructures, which consist of an air material mixture, offer promising alternatives. In this work, silica nanostructures are manufactured by the AR-plas2 method, in which first an organic layer is evaporated onto a substrate. This organic layer forms self-organizing nanostructures by a plasma etching step, which are subsequently coated with silica. Finally, the organic residues are removed by additional plasma etching and heat treatment steps, which results in hollow silica structures. The work examines the optical and functional properties of these structures designed for 355 nm to demonstrate their use as anti-reflective coatings for advanced optical systems. Full article

Background/Objectives: The objective of this study was to investigate the association between congestive heart failure (CHF) and T1 mapping in both liver lobes using cardiac MRI. Methods: This retrospective study included patients who underwent cardiac MRI with T1 mapping sequences on a 1.5 T scanner. The liver T1 values were measured in four hepatic regions, utilizing cardiac short axis and four-chamber views. Echocardiographic and laboratory data were collected within 90 days of the cardiac MRI. Comparisons of the liver T1 values and echocardiographic parameters between patients with and without elevated NT-proBNP levels (>125 pg/mL) were conducted using the Mann–Whitney U test. Logistic regression models were employed to adjust for confounding factors. Results: A total of 397 patients were included (with a median age of 56 years; 127 females), of whom 35% (n = 138) exhibited elevated NT-proBNP levels. The patients with elevated NT-proBNP levels showed a larger end-diastolic volume (EDV: 92 vs. 81 mL/m², p < 0.001) and a lower LVEF level (50% vs. 60%, p < 0.001). The liver T1 was significantly higher in the right liver lobe (670 vs. 596 ms, p < 0.001) and the caudate lobe (664 vs. 598 ms, p < 0.001), but not in the left lobe (571 vs. 568 ms, p = 0.068) or the dome (590 vs. 560 ms, p = 0.1). T1 mapping in the caudate (OR 1.013, 95% CI 1.004–1.023, p = 0.005) and right liver lobes (OR 1.012, 95% CI 1.003–1.021, p = 0.009) remained independently predictive in the logistic regression analysis. Conclusions: Elevated T1 values in the caudate and right liver lobes assessed by cardiac MRI were independently associated with CHF and outperformed T1 measurements in the left liver lobe in predicting disease. Full article

Pollutants information can be retrieved from visible (VIS) and ultraviolet (UV) diffuse solar spectra exploiting Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) instruments. In May 2021, the Italian research institute CNR-ISAC acquired and deployed a MAX-DOAS system SkySpec-2D. It is located in the “Giorgio Fea” observatory in San Pietro Capofiume (SPC), in the middle of the Po Valley, where it has constantly acquired zenith and off-axis diffuse solar spectra since the 1st October 2021. This work presents the retrieved tropospheric NO₂ and aerosol extinction profiles (and their columns) derived from the MAX-DOAS measurements using the newly developed DEAP retrieval code. The code has been validated both using synthetic differential Slant Column Densities (dSCDs) from the Fiducial Reference Measurements for Ground-Based DOAS Air-Quality Observations (FRM4DOAS) project and real measured data. For this purpose, DEAP results are compared with the ones obtained with three state-of-the-art retrieval codes. In addition, an inter-comparison with satellite products from Sentinel-5P TROPOMI, for the tropospheric NO₂ Vertical Column Densities (VCDs), and MODIS-MAIAC for the tropospheric Aerosol Optical Depth (AOD), is performed. We find a bias of −0.6 × 10¹⁵ molec/cm² with a standard deviation of 1.8 × 10¹⁵ molec/cm² with respect to Sentinel-5P TROPOMI for NO₂ tropospheric VCDs and of 0.04 ± 0.08 for AOD with respect to MODIS-MAIAC data. The retrieved data show that the SPC measurement site is representative of the background pollution conditions of the Po Valley. For this reason, it is a good candidate for satellite validation and scientific studies over the Po Valley. Full article

Background: Differences in serum creatinine (SCr) between the Jaffe and enzymatic methods affect the detection and staging of chronic kidney disease in kidney transplant recipients (KTRs). However, there are very limited data on the extent to which the detection of acute kidney injury (AKI) is affected, what impact immunosuppression can have and whether a KTR-specific estimated glomerular filtration rate (eGFR) formula is beneficial. Methods: A total of 12,081 parallel Jaffe/enzymatic SCr (eSCr) measurements of adult outpatient KTRs (61% male, median age 53 years) in the same serum sample at the University Hospital Essen (Germany) between January 2020 and October 2023 were evaluated. AKI and CKD were defined according to current KDIGO guidelines. The GFR was estimated using CKD-EPI and KTR-specific formulas. Results: In about 1% of all measurements and 5% of the KTR patients, the SCr difference between the two methods was ≥ 0.3 mg/dl. A total of 81% of these patients were male; the median age was 52 years. High levels of immunosuppression, including when Belatacept was used, did not seem to have a clinically relevant impact on the difference between Jaffe and eSCr. The KTR-specific eGFR formula generally showed a greater agreement between Jaffe and eSCr than the CKD-EPI eGFR formula, but they showed differences in the classification of CKD stages, especially in less severe stages. Conclusions: Clinically relevant SCr differences between Jaffe and SCr are rare and depend on the type of immunosuppression. A KTR-specific eGFR formula could be beneficial in some cases, but there are limitations in less severe CKD stages. Full article

Industrially applied bioelectrochemical systems require long-term stable operation, and hence the control of biofilm accumulation on the electrodes. An optimized application of biofilm control mechanisms presupposes on-line, in-situ monitoring of the accumulated biofilm. Heat transfer sensors have successfully been integrated into industrial systems for on-line, non-invasive monitoring of biofilms. In this study, a mathematical model for the description of the sensitivity of a heat transfer biofilm sensor was developed, incorporating the hydrodynamic conditions of the fluid and the geometrical properties of the substratum. This model was experimentally validated at different flow velocities by integrating biofilm sensors into cylindrical pipes and planar mesofluidic flow cells with a carbonaceous substratum. Dimensionless sensor readings were correlated with the mean biovolume measured gravimetrically, and optical coherence tomography was used to determine the sensors’ sensitivity. The biofilm sensors applied in the planar flow cells revealed an increase in sensitivity by a factor of 6 compared to standard stainless steel pipes, as well as improved sensitivity at higher flow velocities. Full article

Non-metallic inclusions (NMIs) in steel have a detrimental effect on the processing, mechanical properties, and corrosion resistance of the finished product. This is particularly evident in the case of macroscopic inclusions (>100 µm), which are rarely observed in steel castings produced using state-of-the-art technologies, whereby casting parameters are optimized towards steel cleanliness, and post-treatment steps such as vacuum arc remelting (VAR) are used, but frequently result in the rejection of the affected product. To improve production processes and develop effective countermeasures, it is essential to gain a deeper understanding of the origin and formation of NMIs. In this study, the potential of elemental and isotopic fingerprinting to trace the sources of macroscopic oxide NMIs found in VAR-treated steel ingots using SEM-EDX, inductively coupled plasma mass spectrometry (ICP-MS), laser ablation ICP-MS (LA-ICP-MS), and laser ablation multicollector ICP-MS (LA-MC-ICP-MS) were exploited. Following this approach, main and trace element content and ⁸⁷Sr/⁸⁶Sr isotope ratios were determined in two specimens of macroscopic NMIs, as well as in samples of potential source materials. The combination of the data allowed the drawing of conclusions about the processes leading to the formation of these inclusions. For both specimens, very similar results were obtained, indicating a common mechanism of formation. The inclusions were likely exogenous in origin and were primarily composed of calcium–aluminum oxides. They appeared to have undergone chemical modification during the casting and remelting process. The results indicate that particles from the refractory lining of the casting system most likely formed the macroscopic inclusions, possibly in conjunction with a second, calcium-rich material. Full article

The UV–Visible Working Group of the Network for the Detection of Atmospheric Composition Changes (NDACC) focuses on the monitoring of air-quality-related stratospheric and tropospheric trace gases in support of trend analysis, satellite validation and model studies. Tropospheric measurements are based on MAX-DOAS-type instruments that progressively emerged in the years 2010 onward. In the interest of improving the overall consistency of the NDACC MAX-DOAS network and facilitating its further extension to the benefit of satellite validation, the ESA initiated, in late 2016, the FRM4DOAS project, which aimed to set up the first centralised data processing system for MAX-DOAS-type instruments. Developed by a consortium of European scientists with proven expertise in measurements, data extraction algorithms and software design specialities, the system has now reached pre-operational status and has demonstrated its ability to deliver a set of quality-controlled atmospheric composition data products with a latency of one day. The processing system has been designed using a highly modular approach, making it easy to integrate new tools or processing updates. It incorporates advanced algorithms selected by community consensus for the retrieval of total ozone, lower tropospheric and stratospheric NO₂ vertical profiles and formaldehyde profiles. The ozone and NO₂ products are currently generated from a total of 22 stations and delivered daily to the NDACC rapid delivery (RD) repository, with an additional mirroring to the ESA Validation Data Centre (EVDC). Although it is still operated in a pre-operational/demonstrational mode, FRM4DOAS was already used for several validation and science studies, and it was also deployed in support of field campaigns for the validation of the TROPOMI and GEMS satellite missions. It recently went through a CEOS-FRM self-assessment process aiming at assessing the level of maturity of the service in terms of instrumentation, operations, data sampling, metrology and verification. Based on this evaluation, it falls under class C, which is a good rating but also implies that further improvements are needed to reach full compliance with FRM standards, i.e., class A. Full article

ALDH1A3 is a marker for mesenchymal glioblastomas characterized by a greater degree of aggressiveness compared to other major subtypes. ADH1A3 has been implicated in the regulation of stemness and radioresistance mediated by glioblastoma stem cells. Mechanisms by which ALDH1A3 promotes malignant progression of glioblastoma remain elusive posing a challenge for rationalization of ALDH1A3 targeting in glioblastoma, and it is also unclear how ALDH1A3 regulates glioblastoma cells stemness. Usage of different models with diverse genetic backgrounds and often unknown degree of stemness is one possible reason for discrepant views on the role of ALDH1A3 in glioblastoma stem cells. This study clarifies ALDH1A3 impacts on glioblastoma stem cells by modelling ALDH1A3 expression in an otherwise invariable genetic background with consideration of the impacts of inherent plasticity and proliferative changes associated with transitions between cell states. Our main finding is that ALDH1A3 exerts cell-state dependent impact on proliferation of glioblastoma stem cells. We provide evidence that ALDH1A3 augments radiation-induced inhibition of self-renewal and promotes the proliferation of differentiated GSC progenies. Congruent effects ALDH1A3 and radiation on self-renewal and proliferation provides a framework for promoting glioblastoma growth under radiation treatment. Full article

This study examines the effects of ultrasound-enhanced friction stir welding (USE-FSW) on the mechanical properties and microstructural characteristics of aluminum alloy AA6082-T6, commonly used in automotive, aerospace, and construction industries. The investigation included tensile and bending tests, as well as detailed microstructural evaluations using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and energy-dispersive X-ray spectroscopy (EDS). The results indicate that USE-FSW led to an approximately 26% increase in tensile strength compared to similar samples produced by conventional friction stir welding (CFSW). Additionally, the elongation at break improved by around 52%, indicating better ductility. Flexural strength also showed a notable improvement of over 70%. Microstructural analysis revealed a finer grain structure in the stir zone, contributing to these mechanical enhancements. However, the changes in texture and grain orientation were relatively modest, as shown by EBSD and Kernel Average Misorientation (KAM) analyses. Overall, USE-FSW offers incremental improvements in weld quality and mechanical performance, making it a promising technique for producing joints with slightly enhanced strength and ductility. Full article

Background and Purpose: Decompressive surgery is a potentially life-saving treatment in patients with malignant space-occupying cerebellar infarction. However, there is only limited literature on functional outcomes and complications after surgery. Our aim was to establish markers which predict poor outcome. Methods: We retrospectively analyzed data of all patients who underwent surgery due to malignant swelling of a space-occupying cerebellar infarction in our hospital between 2005 and 2023. Statistical analyses were conducted on multiple parameters to identify predictors of poor functional outcome (mRS 4–6) 90 days after surgery. Complications during hospitalization were reviewed for each patient. Results: In total, 58 patients received decompressive surgery. The 90-day mortality rate was 27.6% (n = 16). A good functional outcome (mRS 0–3) 90 days after surgery was achieved in 24 patients (41.4%). Multivariable analysis revealed multiple factors associated with a poor outcome on day 90 (mRS 4–6): a higher premorbid mRS score (OR 2.715 [95% CI, 1.166–6.323]; p = 0.021), higher NIHSS score on admission (OR 1.088 [95% CI, 1.014, 1.168]; p = 0.019) and the presence of an additional brainstem infarction (OR 7.035, [95% CI, 1.255, 39.424], p = 0.027). Hyperactive delirium was associated with good clinical outcome (OR 0.020 [95%CI, 0.001–0.623]; p = 0.026). Aspiration pneumonia (n = 22, 37.9%), urinary tract infection (n = 15, 25.9%), and hyperactive delirium (n = 8, 13.8%) were the most common complications during hospitalization. Conclusions: Decompressive surgery is a safe, life-saving treatment for malignant space-occupying cerebellar infarction. Higher premorbid mRS, higher NIHSS score on admission and the presence of brainstem infarction are associated with a poor functional outcome. Full article

Background/Objectives: Microsurgical clipping has traditionally been considered a standard treatment for middle cerebral artery (MCA) aneurysms. Recently, a caseload reduction related to improved endovascular treatment options has occurred in cerebrovascular neurosurgery. Therefore, studies that report the clinical and radiological outcomes after clipping are highly warranted. Methods: Patients with an unruptured MCA bifurcation aneurysm, who were surgically treated at the Department of Neurosurgery in Linz between 2002 and 2019, were included in this study. Clinical and radiological outcome parameters were evaluated for each patient. Results: Overall, 272 patients were eligible for inclusion. Complete aneurysm occlusion was demonstrated in 266 (99.3%) of the 268 (98.5%) patients who underwent postoperative digital subtraction angiography. In six (2.2%) patients, a permanent new neurological deficit (pNND) persisted after treatment. Intraoperative aneurysm rupture was a significant factor (p = 0.0049) in the logistic regression. At the last follow-up, only two patients (0.7%) had an unfavorable outcome (mRS > 2). More recent surgeries were associated with fewer cases of pNND (p = 0.009). A transient new neurological deficit occurred in 13 patients (4.8%), with aneurysm size being a significant risk factor (p = 0.009). Surgical site infections were reported in four patients (1.5%), with patient age (p = 0.039) and time (p = 0.001) being significant factors. Two patients died (0.7%) perioperatively and two patients (0.7%) needed a retreatment in the long-term follow-up. Conclusions: The findings indicate that microsurgical clipping is a safe procedure with minimal need for retreatment. It achieves a high occlusion rate while maintaining a very low rate of adverse outcomes. Continuous intraoperative enhancements over time have contributed to a progressive improvement in clinical outcomes in recent years. This trend is exemplified by the absence of detectable pNND in the era of ICG angiography. Consequently, these data support the conclusion that microsurgical clipping should still be considered an appropriate treatment option for unruptured MCA bifurcation aneurysms. Full article

Background: The surgical treatment of adolescent idiopathic scoliosis (AIS) is influenced by factors such as skeletal maturity, curve magnitude, progression, and spinal flexibility. The assessment of spinal flexibility is crucial for surgical planning; supine bending radiographs are commonly used but there is no consensus on the optimal technique. Fulcrum bending radiographs (FBRs) have shown better prediction of post-surgery correction compared to supine bending radiographs. New radiological techniques allow a significant reduction in radiation exposure. This study aims to compare spinal flexibility assessment and radiation exposure between FBRs and standing side-bending radiographs (SSRs) using biplanar stereoradiography. Materials and Methods: Twenty-five consecutive AIS patients scheduled for surgery were included in this prospective cohort study. Exclusion criteria were non-idiopathic etiology, age younger than 12 years, and older than 18 years. Pre-surgery FBRs and SSRs were performed, and the Cobb angles were measured. Flexibility and correction rates were calculated. Dose–area products (DAPs) were recorded. Statistical analysis was conducted using the Wilcoxon signed-rank test and Spearman correlation. Results: The mean pre-surgery Cobb angle of the thoracic curve was 66.3°. The FBR was superior to SSR for assessing flexibility for thoracic curves and provided a better prediction for post-surgery correction. There was no significant difference in lumbar curves between FBR and SSR. The mean DAP for SSRs was 0.81 Gy*cm² compared to 3.42 Gy*cm² for FBR, indicating a lower radiation exposure using SSRs. Conclusions: FBRs are superior for flexibility assessment of thoracic curves in AIS and offers a better prediction of post-surgery correction compared to SSRs. However, FBR is associated with a higher radiation exposure. Full article

Background: Deviations in serum creatinine (SCr), due to its determination using a Jaffe or an enzymatic method, have an effect on kidney disease detection and staging. It is not yet clear how large this effect is in kidney transplant recipients (KTRs). SCr measurement differences are of particular importance here to evaluate the graft function. Methods: The results of all parallel SCr measurements (Jaffe and enzymatic method) of adult outpatient KTRs in the same serum sample at the University Hospital Essen (Germany) between January 2020 and October 2023 were evaluated. A Bland–Altman plot with 95% limits of agreement (LoA) was used to assess the difference between the Jaffe and the enzymatic SCr (eSCr). For all patients, we used the CKD-EPI 2009 and EKFC formula, and for patients ≥ 70 years, we also used the BIS1 formula for the determination of eGFR. Results: A total of 12,081 parallel SCr measurements from 1243 KTRs were analyzed, where 61% were male and the median age was 53 years. On average, Jaffe SCr was 0.03 mg/dL higher than eSCr (LoA −0.16; 0.21 mg/dL). On average, the eGFR determined by Jaffe SCr was 1.9 mL/min/1.73 m² lower than the eGFR determined by eSCr (LoA −9.5; 5.7 mL/min/1.73 m²). The comparison of eGFR between the two SCr methods revealed a different CKD stage in 1589 (13%) of all analyzed measurements, most frequently between G2/G3a (41%) and G3a/G3b (24%). When using the EKFC and BIS1 formulas, there were approximately the same number of measurements leading to a different CKD stage. Conclusions: In more than every tenth SCr determination in outpatient KTRs, the difference between the Jaffe and enzymatic methods had an influence on the assignment to a CKD stage. This effect was comparably pronounced for all eGFR formulas applied. Full article

When engaging in the friction stir welding of aluminum/aluminum joints, the conventional use of tools made of hard metal and steel involves a complex and costly production process. These tools experience wear over welding distances and require frequent replacement to ensure the consistency of the welded seams. The exploration of silicon nitrite as a tool material emerges as a promising alternative in this scenario. The heightened hardness of non-oxide ceramics anticipates a diminished wear rate compared to traditional welding materials, translating into an extended operational lifespan. Nevertheless, the adoption of ceramics introduces challenges initially perceived as detrimental to friction stir welding. The inherent brittleness of silicon nitrite makes it susceptible to breakage under specific loads, and thermal stresses within the component can lead to failure. To mitigate these vulnerabilities, a ceramic material with high thermal shock resistance and a low proportion of sintering additives was used. Employing these accurately designed tools friction stir welding (FSW) was performed on sheets of AA5754, followed by a comprehensive examination of their microstructural and mechanical properties. It was demonstrated that a joint efficiency of 88% can be achieved, and that an increase in hardness within the stir zone occurred as a consequence of grain refinement. Furthermore, the Portevin–Le Chatelier effect, which is characteristic of this alloy, was influenced by the FSW process. Full article