Search Results (116)

Background/Objectives: Vertebral discitis osteomyelitis (VDO) is a serious infection involving the vertebral bodies and intervertebral discs, often requiring biopsy for pathogen identification. However, biopsy yields are variable, and guidance on patient selection remains limited. This study aimed to assess how biopsy culture results influence clinical management and to develop imaging-based scoring systems to predict biopsy outcomes. Methods: In this retrospective study, 70 patients who underwent image-guided vertebral biopsy for suspected VDO between 2013 and 2022 were reviewed. Pre-biopsy MRI and CT findings were scored using novel, simplified criteria. MRI was graded based on soft tissue involvement, while CT evaluated the presence or absence of a vacuum phenomenon. Culture results were correlated with imaging scores and subsequent changes in antibiotic management. Statistical analysis included logistic regression, ROC analysis, and interobserver agreement using Cohen’s Kappa. Results: Of the 70 patients, 27 (38.6%) had positive cultures, and 20 (28.5%) experienced changes in management. Among the 48 patients with both MRI and CT imaging, MRI scores indicating soft tissue involvement and absence of the vacuum sign on CT were independent predictors of positive culture (p = 0.022 and p = 0.047, respectively). The combined predictive model showed an AUC of 0.76. Interobserver agreement was excellent (κ = 0.90 for MRI, κ = 0.95 for CT). Conclusions: MRI and CT features can be used to predict biopsy yield and guide clinical decisions in suspected VDO. These scoring systems may help clinicians identify patients most likely to benefit from biopsy, potentially improving outcomes and minimizing unnecessary procedures. Full article

The success of orthopedic implants critically depends on achieving mechanical and biological compatibility with bone tissue. Traditional titanium implants often suffer from high stiffness, which induces stress shielding, a phenomenon that compromises implant integration and accelerates prosthetic loosening. This study introduces an innovative approach to mitigate these limitations by engineering a porous titanium substrate with a controlled microstructure. Utilizing sodium chloride as a spacer holder, an elution and sintering process was applied at 1250 °C under high vacuum conditions to reduce the material’s elastic modulus. By manipulating NaCl volume fractions (20%, 25%, 30%, and 35%), porous titanium samples were created with elastic moduli between 16.37 and 22.56 GPa, closely matching cortical bone properties (4 to 20 GPa). A hydroxyapatite coating applied via plasma thermal spraying further enhanced osseointegration of the material. Comprehensive characterization through X-ray diffraction, scanning electron microscopy, and compression testing validated the material’s structural integrity. In vitro cytotoxicity assessments using osteoblast cells demonstrated exceptional cell viability exceeding 70%, confirming the material’s biocompatibility. These findings represent a significant advancement in biomaterial design, offering a promising strategy for developing next-generation joint prostheses with superior mechanical and biological adaptation to bone tissue. Full article

In this study, through RH water model simulation experiments, the effects of precipitation bubbles on the two-phase flow pattern, liquid steel flow behavior, and flow characteristics in an RH reactor during the whole decarburization process were comparatively investigated and analyzed by using quasi-counts that reflected the similarity of the precipitation bubble phenomenon. The experimental results show that an increase in precipitation bubbles is positively related to an increase in circulating flow rate, a reduction in mixing time, and an increase in gas content and negatively related to the residence time of liquid steel in the vacuum chamber. The two-phase flow pattern of the rising tube under the influence of precipitation bubbles includes bubble flow, slug flow, mixing flow, and churn flow. Under the influence of precipitation bubbles, the liquid surface spattering inside the vacuum chamber is reduced, the fluctuation amplitude is reduced, the efficiency of liquid steel processing is improved, it is not easy for cold steel to form, and the fluctuation frequency is increased, which is conducive to increasing the surface area of the vacuum chamber; the bubbles’ rising, aggregating, and crushing behavior increases the stirring effect inside the vacuum chamber, which is conducive to improving the decarburization and mass transfer rate. Under the influence of the precipitated bubbles, the concentration gradient between the ladle and the vacuum chamber is increased, which accelerates the mixing speed of the liquid steel in the ladle, and the volume of the dead zone is reduced by 50%. The lifting gas flow rate can be appropriately reduced in the plant. Full article

In this study, we examine the complex interplay between psychiatric epistemic power and its institutional applications through the phenomenon of “diagnosis removal” in Turkey. Within the constraints of limited mental health legislation, psychiatric diagnostic categories serve both as markers of risk and as administrative constructs that can be erased when convenient, presenting paradoxical challenges for healthcare providers and patients alike. Through a systematic analysis of case studies and theoretical frameworks, we explore how bureaucratic authorities can misuse psychiatric diagnoses in employment contexts. The study reveals a significant paradox where psychiatric expertise is simultaneously invoked and challenged, potentially undermining both therapeutic relationships and legal rights. This situation arises from a regulatory vacuum in mental health legislation, further exacerbated by a harm-based approach to mental health issues rather than a rights-based one. Key findings demonstrate how the institutional handling of psychiatric diagnoses creates a treatment disincentive effect, where individuals avoid seeking mental health care due to employment concerns. The analysis also reveals how concept creep and harm-based morality contribute to the misappropriation of psychiatric knowledge in administrative contexts. These findings highlight the urgent need for comprehensive mental health legislation that balances individual rights with public health concerns while protecting the integrity of psychiatric practice from institutional misuse, particularly in employment contexts. Full article

In this article, the results of full-scale experiments on the addition of a sodium sulfide to the ${\mathrm{CaCO}}_3$ slurry circuit in a wet flue gas desulfurization (WFGD) plant are presented. Tests are performed on two comparable WFGD installations (spray tower, 4 spraying levels and two stage gypsum de-watering by hydrocyclones and vacuum belt filter) which allows the investigation of the influence of lignite composition (lignite mined in Poland and the Czech Republic are compared) on the reduction in mercury emission. Additionally, the efficiency of precipitation of metals from the slurry (Hg, Zn, Pb, Cd, Cr, Cu, Ni, Fe, Se, and Mn) is investigated as the result of sulfide addition. For both objects, mercury re-emission from absorber occurs (the concentration of mercury in the chimney is higher than that before the WFGD absorber) and the sulfide addition to WFGD slurry stops this phenomenon. The addition of sulfide works effectively (mercury removal efficiency from flue gas reaches up to 88% for Polish tests and up to 87% for Czech Republic tests). For the tests in the Poland power plant, all of measured metals are precipitated from the slurry (precipitation of metals efficiency varied from 2% for zinc to 88% for mercury), but in the case of the test in the power plant in the Czech Republic, there is no effect on manganese, iron, and lead (precipitation of metals efficiency varied from 6.5% for copper to 86% for mercury). The addition of sulfide works effectively for lignite mined in Polish and Czech power plants under the conditions of similar WFGD installations. Full article

This paper consider a nonlinear shear thickening fluid in one dimensional bounded interval. The model illustrates that the movement of the compressible fluid is driven by non-Newtonian gravity, and represents a more realistic phenomenon. The well-posedness of strong solution was proved by considering the influence of damping term. The essential difficulty lies in the equation’s significant nonlinearity and the initial state may allow for vacuum. Full article

In the production process of electrical steel, with respect to the industrial RH (Ruhrstahl–Heraeus), the steel producers must balance the high-circulation flow rate (operating efficiency) and the frequent cleaning of cold steel in the vacuum chamber due to the splashing of liquid steel (high maintenance costs). Excessive lifting gas flow can induce splashing, causing cold steel to adhere to the inner walls of the vacuum chamber. To address this issue, this study utilized an 80-ton RH vacuum refining unit from a specific plant as the research prototype and established a 1:2.6 scale water model for physical model simulation. Two innovative blowing methods were implemented by adding gas injection nozzles to the sidewalls and to the bottom of the vacuum chamber, respectively. The study investigated the effects of altering the blowing method on liquid surface fluctuations, flow patterns, the circulation flow rate, and the mixing time without changing the total gas flow rate. For the macroscopic flow in the RH unit, implementing side-blowing on the sidewalls of the vacuum chamber can accelerate the diffusion rate of the ink tracer, whereas implementing bottom-blowing in the vacuum chamber has little effect on the diffusion rate. The results show that modifying the blowing method can effectively reduce liquid surface fluctuations and suppress the splashing behavior within the vacuum chamber. Firstly, implementing side-blowing causes the ink tracer flow pattern within the vacuum chamber to become triangular, to increase the circulation flow rate, to shorten the residence time of the ink tracer within the chamber, and simultaneously to promote mixing in the ladle, which reduces the mixing time. Secondly, implementing bottom-blowing results in the formation of a gas column at the center of the vacuum chamber, which suppresses fluid flow within the chamber. Compared with side-blowing, it reduces the circulation flow rate and increases the mixing time in the ladle. Combined gas blowing through the up-snorkel and sidewalls is effective in solving splashing issues and reducing the mixing time in RH vacuum refining, and this method is a good candidate for industrial applications. Full article

The main component of vacuum interrupters responsible for ensuring the correct flow of current is the contact system. In a vacuum environment, due to the higher values of the mean free path of electrons and particles in the contact gap, the material and condition of the contacts exert the greatest influence on the development of the arc discharge. To accurately analyze the phenomenon of discharge development in vacuum insulating systems, the authors conducted a time-lapse photographic analysis of a vacuum electric arc. For this purpose, they used a test setup comprising a discharge chamber, a vacuum pump set, a power and load assembly, an ultra-high-speed camera, and an oscilloscope with dedicated probes. The measurement process involved connecting the system, determining the power supply, load, and measurement parameters and subsequently performing contact opening operations while simultaneously recording the process using the oscilloscope and ultra-high-speed camera. An analysis of a low-current vacuum arc in a residual helium gas environment, with a pressure of p = 1.00 × 10¹ Pa was carried out. Different phases of vacuum arc burning between electrodes in the discharge chamber were identified. In the stable phase, the arc voltage remained constant, while in the unstable phase, the arc voltage increased. The results of the time-lapse analysis were compared with the characteristics recorded by the oscilloscope, revealing a correlation between the increase in vacuum arc voltage and the intensity of flashes in the interelectrode space. The movement of microparticles ejected from the surface of the contacts—either reflecting or adhering to one of the electrodes—was observed. This analysis provides a deeper understanding of the processes involved in discharge formation and development under reduced pressure conditions. Understanding these mechanisms can support the design of vacuum interrupters, particularly in the selection of suitable contact materials and shapes. Full article

The enigmatic phenomenon of dark energy (DE) is the elusive entity driving the accelerated expansion of our Universe. A plausible candidate for DE is the non-zero Einstein Cosmological Constant ${\Lambda }_E$ manifested as a constant energy density of the vacuum, yet it seemingly defies gravitational effects. In this work, we interpret the non-zero ${\Lambda }_E$ through the lens of scale-invariant cosmology. We revisit the conformal scale factor $\lambda$ and its defining equations within the Scale-Invariant Vacuum (SIV) paradigm. Furthermore, we address the profound problem of the missing mass across galactic and extragalactic scales by deriving an MOND-like relation, $g\sim \sqrt{a_0{g}_N}$, within the SIV context. Remarkably, the values obtained for ${\Lambda }_E$ and the MOND fundamental acceleration, $a_0$, align with observed magnitudes, specifically, $a_0\approx {10}^{-10}\mathrm{m}{\mathrm{s}}^{-2}$ and ${\Lambda }_E\approx 1.8\times {10}^{-52}{\mathrm{m}}^{-2}$. Moreover, we propose a novel early dark energy term, ${\tilde{T}}_{\mu \nu }\sim \kappa H$, within the SIV paradigm, which holds potential relevance for addressing the Hubble tension. Full article

In this study, 8Cr4Mo4V steel was selected as the research material to develop a numerical model of the macrosegregation phenomenon during vacuum arc remelting (VAR). The accuracy of the model was validated by comparing it with the literature and experimental results. According to the simulation results, molten steel flows down along the solidification front, resulting in positive segregation at the center and negative segregation close to the edge of the ingot. Solute enrichment reduces the undercooling of the alloy system, which in turn decreases the local solidification rate and causes a slight increase in steady-state molten pool depth. Notably, as the molten pool depth increases, the temperature gradient decreases, while the local cooling rate remains nearly constant, which leads to an increase in the local solidification rate again. Consequently, the positive segregation degree at the ingot’s center is gradually alleviated, and the depth of the molten pool gradually decreases. Furthermore, macrosegregation in VAR ingots becomes pronounced with an increase in melt rate. The main reason for this is due to the increased molten pool depth when the melt rate is increasing, which strengthens fluid flow and accelerates the migration of solute elements to the center. Additionally, due to the increase in the extent of solute enrichment when the melt rate is increasing, the degree of fluctuation in both the steady-state molten pool depth and positive segregation increases. Full article

Nitride films such as tantalum nitride (TaN), titanium nitride (TiN) and boron nitride (BN) are widely used in aerospace and vacuum electronics. The electron emitting properties of these nitride films are of great interest due to the phenomenon of surface electron emission when the films are irradiated, leading to surface modification. In this study, we have prepared three kinds of thin films, TaN, TiN and BN, by sputtering. Then the effect of the nitrogen component on the film formation quality and the dependence of the electron emission coefficient (EEC) on the film’s physical properties were investigated. The results of elemental analysis show that by rising the nitrogen gas flow during sputtering, the N elemental ratios inside the TaN and TiN films can be increased, and the film resistivity decreases follow, while BN films do not show such a tunable characteristic of the elemental ratios or resistivity. The conductivity test results show that TaN and TiN films exhibit conductive properties like those of semiconductor materials. The proportion of N elements inside the films has a significant effect on the film conductivity, namely, the conductivity of the film shows an upward trend with the increase in the proportion of N elements. The EEC test shows that TaN and TiN films with good conductive properties have relatively low EEC values, which are generally lower than 2.10. For TaN and TiN, the test results show that the EEC decreases with the increase of the conductivity. The EEC peak values are 1.92 and 1.56 for TaN and TiN films when their resistivities are 1.45 × 10⁻⁵ Ω·m and 7.26 × 10⁻⁶ Ω·m, respectively. The EEC values of BN are larger than TaN and TiN, with an EEC peak value higher than 2.49, and the electron energy to obtain the peak value is about 250 eV. The results are instructive for revealing the electron emission regularity of nitride thin films. Full article

Background: Oblique lumbar interbody fusion (OLIF) is a minimally invasive technique used to manage degenerative lumbar conditions. The presence of vacuum phenomenon (VP) and associated endplate sclerosis may increase the risk of cage subsidence. This study evaluated the relationship between VP grade, endplate sclerosis, and subsidence in OLIF. Methods: This retrospective cohort study included 165 patients who underwent a single-level OLIF for lumbar stenosis. Patients were stratified into VP grades (0–3) based on preoperative computed tomography scans. Disc height, endplate sclerosis, and cage subsidence were radiologically assessed. Clinical outcomes, including back and leg pain visual analog scale, Oswestry Disability Index, and EuroQol-5 Dimension, were measured preoperatively and at follow-up. Results: High VP grades were associated with low preoperative disc height and increased endplate sclerosis. Although no significant differences in clinical outcomes or final fusion rates across VP grades were observed, the subsidence rate increased with VP grade, with a significant difference between VP grades 1 and 2 (p = 0.045) and between VP grades 2 and 3 (p = 0.032), indicating that subsidence rates increased as the VP grade advanced. Conclusions: High VP grades, particularly grades 2 and 3, may increase the risk of cage subsidence following OLIF. Therefore, VP grading may be worth considering during surgical planning to reduce the subsidence risk and improve outcomes. Full article

This article presents the author’s methodology for testing selected parameters of a low-current vacuum arc, implemented using an innovative test stand based on a vacuum discharge chamber with a contact system mounted inside. In order to verify the validity of the adopted research methodology, as well as the correctness of the operation of the developed laboratory bench, measurements and calculations were made, among other things, of the energy and burning time of the vacuum arc, depending on selected factors, such as pressure and the delay time of the contact opening, calculated from the “passage through zero” of the sinusoid of the current flowing through the system. The tests were performed at 230 V and a current of 5 A for two pressure values: p₁ = 1.00 × 10⁵ Pa (atmospheric pressure) and p₂ = 4.00 × 10⁻³ Pa (high vacuum environment). It was found that the vacuum insulation technique allows a significant reduction in the value of the arc energy and the burning time of the arc. It was also observed that in the case of a high vacuum environment, the ignition of the vacuum arc occurs after a time equal to about 3 ms from the “passage through zero” of the current flowing through the system. Below this value, the phenomenon did not occur. The results obtained provide an opportunity for the design and manufacturing of vacuum switchgear, where there is the prospect of reducing the negative effects associated with the arc burning process in the contact gap. Full article

Objective: This study investigated the influence of the vacuum phenomenon (VP) on surgical outcomes in patients with lumbar spinal stenosis, comparing minimally invasive oblique lateral interbody fusion (MIS OLIF) and endoscopic decompression. Methods: A cohort of 110 patients diagnosed with lumbar spinal stenosis underwent either endoscopic decompression or MIS OLIF. Patients were classified into two groups based on the presence or absence of the VP on preoperative CT scans, non-VP (n = 42) and VP (n = 68). Radiologic and clinical outcomes, including back and leg pain assessed using the visual analogue scale (VAS), the Oswestry Disability Index (ODI), and the EuroQol-5 Dimension (Eq5D), were compared pre- and postoperatively over a 2-year follow-up period. Results: Preoperatively, the VP group exhibited significantly greater leg pain (p = 0.010), while no significant differences were observed in back pain or the ODI between the groups. In the non-VP group, decompression and fusion yielded similar outcomes, with decompression showing a better ODI score at 1 month (p = 0.018). In contrast, in the VP group, patients who underwent fusion showed significantly improved long-term leg pain outcomes compared to those who underwent decompression at both 1-year (p = 0.042) and 2-year (p = 0.017) follow-ups. Conclusions: The VP may indicate segmental instability and may play a role in the persistence of radiculopathy. Fusion surgery appears to offer better long-term relief in patients with the VP, whereas decompression alone is a viable option in non-VP cases. These findings suggest that the VP may be a useful factor in guiding surgical decision-making. Full article

It is a challenging but key task to reduce the tritium inventory in EU-DEMO to levels that are acceptable for a nuclear regulator. As solution to this issue, a smart fuel cycle architecture is proposed based on the concept of Direct Internal Recycling (DIR), in which the Metal Foil Pump (MFP) will play an important role to separate the unburnt hydrogen isotopes coming from the divertor by exploiting the superpermeation phenomenon. In this study, we will present the assessment of the performance of the lower port of EU-DEMO after the integration of the MFP. For the first time, a thorough comparison of three different MFP (parallel long tubes, sandwich and halo) designs is performed regarding conductance for helium molecules, the pumping speed and the separation factor for deuterium molecules under different physical and geometric parameters. All simulations were carried out in supercomputer Marconi-Fusion with our in-house Test Particle Monte Carlo (TPMC) simulation code ProVac3D because the code had been parallelized with high efficiency. These results are essential for the development of a suitable MFP design in the vacuum-pumping train of EU-DEMO. Full article