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To investigate the safety, durability, and patency rates of stent grafts (SGs) placed in the cannulation zone of hemodialysis access circuits. From April 2020 to April 2023, all procedures with SGs placed in the cannulation zone were retrospectively analyzed. A total of 40 patients (25 men and 15 women) with SGs placed in the cannulation zone were included in the study. Mean age of the patients was 70 years. The Covera covered stent (BD, Franklin Lakes, New Jersey) was used in all cases. Of these, 26 were arteriovenous (AV) fistulae and 14 were AV grafts. SGs were placed for residual stenosis, perforation, aneurysm, and thrombosis. Follow-up outcomes were determined using follow-up angiographic images and included primary patency, primary-assisted patency, and secondary patency. The primary patency of the target lesion was 89% (SD ± 5) and 74% (SD ± 8.4) at 6 and 12 months, respectively. The primary-assisted patency was 89% (SD ± 5.2) and 78% (SD ± 7.6) at 6 and 12 months, respectively. Secondary patency of the access circuit was 97% (SD ± 2.5) at both 6 and 12 months. Mean follow-up was 332 days (range, 28–661 days). All SGs were successfully cannulated for hemodialysis. No cases of stent fracture or stent infection were observed during follow-up. SGs placed for cannulation zone pathologies can be safely cannulated for dialysis and have adequate short- and mid-term patency rates. [Display omitted] [ABSTRACT FROM AUTHOR]

Few reports have studied lung aeration and perfusion in normal lungs, COVID-19, and ARDS from other causes (NC-ARDS) using dual-energy computed tomography pulmonary angiograms (DE-CTPA). To describe lung aeration and blood-volume distribution using DE-CTPAs of patients with NC-ARDS, COVID-19, and controls with a normal DE-CTPA ("healthy lungs"). We hypothesized that each of these conditions has unique ranges of aeration and pulmonary blood volumes. This retrospective, single-center study of DE-CTPAs included patients with COVID-19, NC-ARDS (Berlin criteria), and controls. Patients with macroscopic pulmonary embolisms were excluded. The outcomes studied were the (1) lung blood-volume in areas with different aeration levels (normal, ground glass opacities [GGO], consolidated lung) and (2) aeration/blood-volume ratios. Included were 20 patients with COVID-19 (10 milds, 10 moderate-severe), six with NC-ARDS, and 12 healthy-controls. Lung aeration was lowest in patients with severe COVID-19 24% (IQR13%–31%) followed by those with NC-ARDS 40%(IQR21%–46%). Blood-volume in GGO was lowest in patients with COVID-19 [moderate-severe:-28.6 (IQR-33.1–23.2); mild: -30.1 (IQR-33.3–23.4)] and highest in normally aerated areas in NC-ARDS -37.4 (IQR-52.5–30.2-) and moderate-severe COVID-19 -33.5(IQR-44.2–28.5). The median aeration/blood-volume ratio was lowest in severe COVID-19 but some values overlapped with those observed among patients with NC-ARDS. Severe COVID-19 disease is associated with low total aerated lung volume and blood-volume in areas with GGO and overall aeration/blood volume ratios, and with high blood volume in normal lung areas. In this hypothesis-generating study, these findings were most pronounced in severe COVID disease. Larger studies are needed to confirm these preliminary findings. [ABSTRACT FROM AUTHOR]

The work is devoted to the experimental study of steels and alloys deformation properties with account to the mutual influence of the cyclic and static deformation components. Carbon steel and three different chrome-nickel austenitic steels were tested at different temperatures and durations. At strain-controlled cyclic loading these steels demonstrate cyclic hardening (or softening – depending on the previous history) at the running-in stage, then stabilization and subsequent softening at the pre-fracture stage. Experiments show that in case of comparable cyclic and static damage the mutual influence of the cyclic and static material hardening (softening) strongly affects the stress-strain diagrams; this effect should be taken into account in structural analysis. Models that use only the information about static or strain-controlled cyclic loading are incapable to describe this effect. [ABSTRACT FROM AUTHOR]

The fracture with the formation of crack patterns instead of a single main crack may occur in the structures for several reasons. The main factor is always the presence of high gradients through the depth of a structure at almost constant stresses near the surface. In this case a growing crack can get into the zone of low stresses and stop, and the fracture will continue by formation of new cracks. Such fracture type is typical for heat-stressed structures, but can also occur under mechanical loading. This paper discusses the possible mechanisms of the crack pattern formation. It is shown that in addition to the form of stress field, the fracture type depends on material properties - in particular, its creep. The considered fracture by crack pattern formation could be characteristic of not only the metallic structural elements, but also for the natural formations, for instance rock or ice massives. [ABSTRACT FROM AUTHOR]

The need to analyze the stability of low-cycle processes of deformation is stimulated by the transition from strength criteria in terms of allowable stresses to the analysis of limit states of structures and risk criteria. It is proposed to separate the solution of this problem for the four main types of a low-cycle deformation. The deformation properties of the material are qualitatively different to those process types. This leads to qualitative and quantitative differences in both the unstable processes and their consequences. Possibilities and methods of the analysis and those providing a desired durability of structures also become different. [ABSTRACT FROM AUTHOR]

Technological parameters of selective laser melting determine the quality of the parts produced: porosity, residual stresses and so strength and plasticity. Numerical modeling can help understand this dependence. The modeling process must account for the fact that typical sizes of metal powder particles, used for selective laser melting, are comparable (near equal) to the diameter of the laser beam, so considering powder a continuum is not fully correct. It is shown that LS-DYNA finite element code has enough capability to model important features of the process – heat exchange, melting, contact interaction of the particles. [ABSTRACT FROM AUTHOR]

Objective To test the hypothesis that perioperative OMEGA-3 polyunsaturated fatty acid infusion would reduce the incidence of postoperative atrial fibrillation in patients after coronary artery bypass grafting as assessed by an implantable continuous cardiac monitor. Design Prospective, randomized, double-blind, placebo-controlled study. Setting Tertiary cardiothoracic referral center. Participants Thirty-nine patients with coronary artery disease who underwent surgery with cardiopulmonary bypass. Interventions Patients were assigned randomly to receive either OMEGA-3 polyunsaturated fatty acids (200 mg/kg/day starting before anesthesia induction for 24 hours followed by 100 mg/kg/day for 7 days) or placebo. The primary outcome was freedom from atrial fibrillation at 2-year follow-up. Reveal ® cardiac monitor was implanted subcutaneously in all patients. Data from the cardiac monitor were collected on the 10th day and 3, 6, 12, and 24 months postoperatively. Measurement and Main Results Postoperative atrial fibrillation developed in 4 (19%) patients in the control group and in 5 (27.8%) patients in the study group at 10-day follow-up (p = 0.88). At 2-year follow-up, 5 (27.8%) patients in the control group and 6 (35.3%) patients in the study group had atrial fibrillation (p = 0.9). Atrial fibrillation duration predicted risk of cardiovascular hospitalization at the 2-year follow-up (regression coefficient estimate = 0.24, standard error 0.02, p<0.0001; R 2 = 0.74). Conclusions Infusion of OMEGA-3 polyunsaturated fatty acids failed to prevent the occurrence of atrial fibrillation in 2 years after coronary artery bypass grafting surgery. The cumulative atrial fibrillation duration registered by the continuous cardiac monitor at the 2-year follow-up was a significant predictor of an adverse outcome. [ABSTRACT FROM AUTHOR]

Internalization of the Na+/K+-ATPase (the Na+ pump) has been studied in the human lung carcinoma cell line H1299 that expresses YFP-tagged α1 from its normal genomic localization. Both real-time imaging and surface biotinylation have demonstrated internalization of α1 induced by ≥100 nm ouabain which occurs in a time scale of hours. Unlike previous studies in other systems, the ouabain-induced internalization was insensitive to Src or PI3K inhibitors. Accumulation of α1 in the cells could be augmented by inhibition of lysosomal degradation but not by proteosomal inhibitors. In agreement, the internalized α1 could be colocalized with the lysosomal marker LAMP1 but not with Golgi or nuclear markers. In principle, internalization could be triggered by a conformational change of the ouabain-bound Na+/K+-ATPase molecule or more generally by the disruption of cation homeostasis (Na+, K+, Ca2+) due to the partial inhibition of active Na+ and K+ transport. Overexpression of ouabain-insensitive rat α1 failed to inhibit internalization of human α1 expressed in the same cells. In addition, incubating cells in a K+-free medium did not induce internalization of the pump or affect the response to ouabain. Thus, internalization is not the result of changes in the cellular cation balance but is likely to be triggered by a conformational change of the protein itself. In physiological conditions, internalization may serve to eliminate pumps that have been blocked by endogenous ouabain or other cardiac glycosides. This mechanism may be required due to the very slow dissociation of the ouabain·Na+/K+-ATPase complex. [ABSTRACT FROM AUTHOR]

Abstract: The necessary use of heavy duty trawl winches can cause plastic deformation of winch barrels, known as “rolling”. Numerical analysis shows that the main reason for such deformation is pressure from layers of cable, while other reasons – a “rolling spot” of stress near the rope-barrel contact point, barrel bending and torsion – play a small role. The influence of different factors (barrel sizes, material properties, rope properties, and load levels) on the strain accumulation rate is analyzed. The described method provides a barrel design for new winches and load constraints for existing winches. New rope tension gauge and special software are developed to help the trawler master predicts situation that can lead to barrel plastic deformation. [Copyright &y& Elsevier]

This work analyses the deformation of high-loaded structures for problems of strength and safety. Determining the load safety factor typically requires a series of calculations with successively increasing loads, up to fracture. In cyclic loading, each calculation is a numerical modeling of the structure behavior during several (or several tens) cycles up to stabilization to estimate the damage accumulated during one stable cycle. In multi-parameter loading, different load combinations may cause different mechanisms of structural deformation (i.e., different distributions of plastic strains and their velocities in the structure) with different consequences for the structure, thereby requiring different safety factors. At one-parameter loading, the assumption that the deformation mechanism remains the same for different load levels could reduce the required number of calculations. This article presents examples proving that this assumption could lead to incorrect results and requires careful verification. • Two qualitative factors characterize cyclic inelastic deformation: the type and the mechanism. • The type depends on strain span and strain increment per cycle (alternating flow, strain accumulation, or their combination). • The mechanism is inelastic strain rate distribution in every moment of the cycle. • Different types and mechanisms lead to dissimilar consequences, which influence the estimation of strength and durability. • The type and mechanism of deformation may vary with load, even for one-parameter loads. [ABSTRACT FROM AUTHOR]

Abstract: A product formula for the parity generating function of the number of 1’s in invertible matrices over is given. The computation is based on algebraic tools such as the Bruhat decomposition. It is somewhat surprising that the number of such matrices with odd number of 1’s is greater than the number of those with even number of 1’s. The same technique can be used to obtain a parity generating function also for symplectic matrices over . We present also a generating function for the sum of entries of matrices over an arbitrary finite field calculated in . The Mahonian distribution appears in these formulas. [Copyright &y& Elsevier]

Abstract: We discuss permutation representations which are obtained by the natural action of S n × S n on some special sets of invertible matrices, defined by simple combinatorial attributes. We decompose these representations into irreducibles. The multiplicities involved have a nice combinatorial interpretation. We also generalize known results on asymptotic behavior of the conjugacy representation of S n . [Copyright &y& Elsevier]

• Low-cycle thermal fatigue could appear even at small observed temperature. • Closely located cracks are symptom of a thermal fracture but not of mechanical one. • High thermal conductivity of a material masks local areas of high thermal gradient. The heater of blast furnace intended to provide hot blast and has a metal casing lined inside with refractory bricks. The technological process involves cyclic changes of gas temperature in the heater from 400 to 1200 °C (673 to 1473 K) with cycle duration of 3 h. After some operating time, cracks appear in the casing. Internal pressure in the apparatus is low; nevertheless, the cracks are dangerous because the stream of hot (1200 °C) oxygen-enriched air can damage surrounding structures. A way to prevent cracks depends on the mechanism of their formation. Three possible reasons of the crack formation were considered: uncompensated forces caused by thermal expansion of the entire structure, vibrations, and thermal stresses due local uneven heating of the casing. The observed cracks have different orientations and in some cases are located sufficiently close to each other. This pattern is characteristic for thermal cracks and is not typical for cracks caused by mechanical loads and/or vibrations. Numerical analysis shows that the non-uniformity of temperatures may cause the thermal fatigue cracks despite the fact that the non-uniformity observed on the outer surface of the casing is small enough. Fractographic studies confirmed the thermo-fatigue nature of the cracks. As a possible measure to prevent cracking the usage of 2-layer casing was analyzed, numerical estimations proved potential effectiveness of such solutions. [ABSTRACT FROM AUTHOR]

Abstract: Epidural hematoma is a potentially life threatening event that demands prompt diagnosis and surgical treatment, usually following head trauma. We present a case of a 9-year-old boy with no history of head trauma, and who was diagnosed with epidural hematoma secondary to frontal sinusitis; and the medical literature was reviewed. [Copyright &y& Elsevier]

Abstract Patient-specific QCT-based finite element (QCTFE) analyses enable highly accurate quantification of bone strength. We evaluated CT scanner influence on QCTFE models of long bones. A femur, humerus, and proximal femur without the head were scanned with K 2 HPO 4 phantoms by seven CT scanners (four models) using typical clinical protocols. QCTFE models were constructed. The geometrical dimensions, as well as the QCT-values expressed in Hounsfield unit (HU) distribution was compared. Principal strains at representative regions of interest (ROIs), and maximum principal strains (associated with fracture risk) were compared. Intraclass correlation coefficients (ICCs) were calculated to evaluate strain prediction reliability for different scanners. Repeatability was examined by scanning the femur twice and comparing resulting QCTFE models. Maximum difference in geometry was 2.3%. HU histograms before phantom calibration showed wide variation between QCT scans; however, bone density histogram variability was reduced after calibration and algorithmic manipulation. Relative standard deviation (RSD) in principal strains at ROIs was <10.7%. ICC estimates between scanners were >0.9. Fracture-associated strain had 6.7%, 8.1%, and 13.3% maximum RSD for the femur, humerus, and proximal femur, respectively. The difference in maximum strain location was <2 mm. The average difference with repeat scans was 2.7%. Quantification of strain differences showed mean RSD bounded by ∼6% in ROIs. Fracture-associated strains in "regular" bones showed a mean RSD bounded by ∼8%. Strains were obtained within a ±10% difference relative to the mean; thus, in a longitudinal study only changes larger than 20% in the principal strains may be significant. ICCs indicated high reliability of QCTFE models derived from different scanners. [ABSTRACT FROM AUTHOR]

Nanocomposite transparent coatings on the quartz substrates based on the Si-Al-N system were formed by pulsed magnetron sputtering. The protective properties of the coatings were discovered by means of an impact of the flows of iron particles. The microparticles accelerated up to 5–8 km/s using a two-stage light-gas gun. A significant decrease in the surface density of the craters was observed on the coated quartz substrate formed under the microparticles impacts. The effect was explained by a change in the structure, phase composition and the mechanical properties of the surface layer of the quartz when a nanocomposite coating was deposited on it. [ABSTRACT FROM AUTHOR]

Mitral regurgitation (MR) is common in ischemic heart disease and contributes to symptoms and mortality. This report compares the results of baseline transesophageal echocardiography (TEE) and transthoracic echocardiography (TTE) imaging of the mechanism and severity of functional MR in patients with ischemic cardiomyopathy in the Surgical Treatment for Ischemic Heart Failure (STICH) trial. Independent core laboratories measured both TTE and TEE images on 196 STICH participants. Common measurements to both models included MR grade, mitral valve tenting height and tenting area, and mitral annular diameter. For each parameter, correlations were assessed using Spearman rank correlation coefficients. A modest correlation was present between TEE and TTE for overall MR grade (n = 176, r = 0.52). For mechanism of MR, modest correlations were present for long-axis tenting height (n = 152, r = 0.35), tenting area (n = 128, r = 0.27), and long-axis mitral annulus diameter (n = 123, r = 0.41). For each measurement, there was significant scatter. Potential explanations for the scatter include different orientation of the imaging planes between TEE and TTE, a mean temporal delay of 6 days between TEE and TTE, and statistically significant differences in heart rate and blood pressure and weight between studies. In conclusion, TEE and TTE measurements of MR mechanism and severity correlate only modestly with enough scatter in the data that they are not interchangeable. [ABSTRACT FROM AUTHOR]

The mechanisms underlying functional mitral regurgitation (MR) and the relation between mechanism and severity of MR have not been evaluated in a large, multicenter, randomized controlled trial. Transesophageal echocardiography (TEE) was performed in 215 patients at 17 centers in the Surgical Treatment for Ischemic Heart Failure (STICH) trial. Both 2-dimensional (n = 215) and 3-dimensional (n = 81) TEEs were used to assess multiple quantitative measurements of the mechanism and severity of MR. By 2-dimensional TEE, leaflet tenting area, anterior and posterior leaflet angles, mitral annulus diameter, left ventricular (LV) end-systolic volume index, LV ejection fraction (LVEF), and sphericity index (p <0.05 for all) were significantly different across MR grades. By 3-dimensional TEE, mitral annulus area, leaflet tenting area, LV end-systolic volume index, LVEF, and sphericity index (p <0.05 for all) were significantly different across MR grades. A multivariate analysis showed a trend for annulus area (p = 0.069) and LV end-systolic volume index (p = 0.071) to predict effective regurgitant orifice area and for annulus area (p = 0.018) and LV end-systolic volume index (p = 0.073) to predict vena contracta area. In the STICH trial, multiple quantitative parameters of the mechanism of functional MR are related to MR severity. The mechanism of functional MR in ischemic cardiomyopathy is heterogenous, but no single variable stands out as a strong predictor of quantitative severity of MR. [ABSTRACT FROM AUTHOR]

Aim: To determine the prevalence and clinical significance of pleural microbubbles in thoracic empyema. Materials and Methods: The charts of 71 consecutive patients with empyema were retrospectively reviewed for relevant demographic, laboratory, microbiological, therapeutic and outcome data. Computed tomography (CT) images were reviewed for various signs of empyema as well as pleural microbubbles. Two patient groups, with and without microbubbles were compared. Results: Mean patient age was 49 years and 72% were males. Microbubbles were detected in 58% of patients. There were no significant differences between patients with and without microbubbles in regard to pleural fluid chemistry. A causative organism was identified in about 75% of cases in both. There was no difference in the rates of pleural thickening and enhancement, increased extra-pleural fat attenuation, air-fluid levels or loculations. Microbubbles were diagnosed after a mean of 7.8 days from admission. Thoracentesis before CT was performed in 90 and 57% of patients with and without microbubbles (p=0.0015), respectively. Patients with microbubbles were more likely to require repeated drainage (65.9 versus 36.7%, p=0.015) and surgical decortication (31.7 versus 6.7%, p=0.011). Mortalities were 9.8 and 6.6% respectively (p=0.53). Conclusion: Pleural microbubbles are commonly encountered in CT imaging of empyema but have not been systematically studied to date. Microbubbles may be associated with adverse outcome such as repeated drainage or surgical decortication. The sensitivity and specificity of this finding and its prognostic implications need further assessment. [ABSTRACT FROM AUTHOR]