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Based on the discrete element method (DEM), four packed beds composed of soybean kernels with diameters of 6.4, 6.8, 7.4 mm, and the mixture of three kinds of particles were established. Then, a double-diffusion heat and mass transfer model between the grain pile and the interstitial air was established based on the local mass and thermal non-equilibrium (LMTNE) mechanism. Finally, employing particle-resolved computational fluid dynamics (PRCFD), the heat and mass transfer between the grain kernels and air during the drying process in the four packed beds were numerically resolved. It was found that the packed bed formed by stacking particles of different diameters had a minimum porosity of 0.4547. The radial porosity of the packed bed oscillates and decreases toward the central axis, while the tortuosity of the airflow path oscillates and decays toward the periphery. The mass transfer Biot number for soybean kernels with diameters of 6.4, 6.8, and 7.4 mm were 2.38 × 106, 2.44 × 106, and 2.53 × 106, respectively. This indicates that the mass transfer rate in the grain pile primarily depends on the magnitude of the moisture diffusion coefficient within the grain kernels. Compared with mass diffusion, thermal diffusion occurs much faster, which results in temperature gradients in packed beds only existing in the first 5 min of drying, and the drying rate in the early stage is higher than that in the later stage. Most importantly, the airflow characteristics, heat and moisture content are not in local equilibrium in the packed bed, and should be considered when designing drying systems. [ABSTRACT FROM AUTHOR]

The microporous layer (MPL) plays an important role in water and thermal management of proton exchange membrane fuel cells (PEMFCs). An in-depth investigation of the mechanical compression effect on transport properties in the MPL can help optimize cell performance. In this work, the microstructure of the MPL is numerically reconstructed and the finite element method is applied to simulate mechanical behavior. Besides, the distribution of stress-strain, porosity, and pore size in the MPL under ten different levels of mechanical compression strains are studied. Lastly, the pore-scale model is employed to investigate the effective transport properties of the MPL as a function of compression strain. The analysis reveals that as the MPL strain increases from 0% to 40%, there is a 29% decrease in porosity, a 50% reduction in average pore diameter, a 60% decrease in effective gas diffusivity, a 100% increase in tortuosity, and an 80% increase in electrical and thermal conductivity. With the escalation of mechanical compression, both the magnitude and uniformity of stress-strain-displacement concurrently rise. Mechanical compression strains below 20% exhibit a lesser impact on transport properties. Beyond this threshold, exceeding the 20% compression strain point, mechanical stress assumes a critical role in influencing MPL transport properties. • The realistic microstructure of the microporous layer is reconstructed numerically. • The properties of each component of the microporous layer are fully considered. • The finite element method is utilized to simulate mechanical stresses. • Pore-scale simulations are utilized to obtain the effective transport properties. • Critical compressive strain points are identified to guide assembly optimization. [ABSTRACT FROM AUTHOR]

Introduction: Extracranial carotid artery aneurysms (ECAA) are rare compared to occlusive disease, less than 1% of all arterial aneurysms and only 10% are considered true aneurysms. Clinical case: A 84-yearold female, active and in excellent general health, with a prior history significant only for hypertension and hyperlipidemia was referred for a right internal carotid artery aneurysm and elongation in the context of contralateral internal carotid artery occlusion. The patient denied neurologic symptoms. Resection of the aneurysm and end-to-end anastomosis, endarterectomy of the ostium and patch angioplasty was performed. The patient had an uneventful recovery, remaining asymptomatic and the reconstruction patent on duplex scan at 6 month follow up. Discussion: The choice of repair alternatives for EICA depend on its morphological characteristics. The presence of extreme tortuosity of the internal carotid artery in this case, on one hand make difficult to consider endovascular alternatives, but facilitates aneurysm resection and primary end-to-end anastomosis. Conclusion: Aneurysmectomy and arterial reconstruction is a treatment alternative for EICA repair. [ABSTRACT FROM AUTHOR]

A control problem for the heating of moist paperboard with the evaporation of moisture from the inner pore surface is considered. The microstructure of the paperboard is known from the CT images. It is easily parametrized w.r.t. the volume fraction of the pores, the surface area of the pores related to the unit volume, averaged area of the contact surfaces between two fibers and the unsupported fiber length between two contact nodes, fiber thickness, and tortuosity. Simple averaging formulas are provided for the computation of the effective coefficients in the coupled diffusion‐heat problem and the dissipation energetic balance was analyzed and we pass to the limit w.r.t. the small parameter, the relation between the pore size and the paper‐board thickness. The limit model is similar to those models, recently available in the literature. However, it provides more understanding and different limiting models and the thresholds for them. Also, the limitation on the heating is derived from the solvability criteria, which means, that the evaporation should not overtake the heating. The model is validated by experimental and numerical results found in the literature. [ABSTRACT FROM AUTHOR]

In >70% of patients with hemifacial spasm (HFS), the offending artery is either the anterior inferior cerebellar artery (AICA) or posterior inferior cerebellar artery (PICA), without a tortuous vertebrobasilar artery (VBA). We hypothesized that anchoring perforators around the root exit zone (REZ) of the AICA or PICA might induce vascular deviation and compression. We investigated the occurrence of these perforators from the AICA or PICA and the extent of VBA tortuosity to reveal the pathology of vascular compression. This retrospective review included 110 patients after excluding those with vertebral artery (VA) compression alone. The occurrence of perforators was determined according to operative findings within 5 mm of the REZ, and VBA tortuosity was evaluated using MATLAB. We analyzed the association between perforators, VBA tortuosity, and the surgical implications. The occurrence of perforators from the offending AICA or PICA around the REZ was significantly higher in the group without VA compression (Group A) than in the group with VA compression (Group B). VBA tortuosity was significantly lower in Group A. VBA tortuosity was inversely correlated with the presence of AICA or PICA perforators in all 110 patients. Operative results were similar between the groups, although patients with low VBA tortuosity tended to require interposition in decompression procedures. Anchoring perforators around the REZ play a crucial role in vascular compression for patients with less tortuous VBAs. Moreover, surgeons should be prepared to deal with multiple perforators in a more complicated surgery in cases of less tortuous VBA. [ABSTRACT FROM AUTHOR]

Permeability is a required parameter for studying aquifer properties. However, for sandstone aquifers with low permeability, it is difficult to measure permeability directly through experiments. Based on fractal theory and the J function, a new method to calculate the permeability of a sandstone aquifer is derived. This work first solves the J function under each water saturation according to its definition. Combined with mercury pressure data, the J function and logarithmic curve equation of water saturation are then fitted by the drawing method, and the fractal dimension and tortuosity of the aquifer are further solved. Finally, the aquifer's permeability is calculated using the new permeability calculation method. To verify the accuracy of the proposed method, 15 rock samples from the Chang 7 Group, Ordos Basin, are taken as research objects. The permeability is calculated using the new method combined with mercury injection data and aquifer characteristic parameters, and the results are compared with the real permeability. The relative error of most samples is <20%, which shows the permeability calculated by this method is accurate and reliable. The effects of fractal dimension, tortuosity, and porosity on permeability are also analyzed. [ABSTRACT FROM AUTHOR]

Endoprosthetic hip replacement is the conventional way to treat osteoarthritis or a fracture of a dysfunctional joint. Different manufacturing methods are employed to create reliable patient‐specific devices with long‐term performance and biocompatibility. Recently, additive manufacturing has become a promising technique for the fabrication of medical devices, because it allows to produce complex samples with various structures of pores. Moreover, the limitations of traditional fabrication methods can be avoided. It is known that a well‐designed porous structure provides a better proliferation of cells, leading to improved bone remodeling. Additionally, porosity can be used to adjust the mechanical properties of designed structures. This makes the design and choice of the structure's basic cell a crucial task. This study focuses on a novel computational method, based on the basic‐cell concept to design a hip endoprosthesis with an unregularly complex structure. A cube with spheroid pores was utilized as a basic cell, with each cell having its own porosity and mechanical properties. A novelty of the suggested method is in its combination of the topology optimization method and the structural design algorithm. Bending and compression cases were analyzed for a cylinder structure and two hip implants. The ability of basic‐cell geometry to influence the structure's stress–strain state was shown. The relative change in the volume of the original structure and the designed cylinder structure was 6.8%. Computational assessments of a stress–strain state using the proposed method and direct modeling were carried out. The volumes of the two types of implants decreased by 9% and 11%, respectively. The maximum von Mises stress was 600 MPa in the initial design. After the algorithm application, it increased to 630 MPa for the first type of implant, while it is not changing in the second type of implant. At the same time, the load‐bearing capacity of the hip endoprostheses was retained. The internal structure of the optimized implants was significantly different from the traditional designs, but better structural integrity is likely to be achieved with less material. Additionally, this method leads to time reduction both for the initial design and its variations. Moreover, it enables to produce medical implants with specific functional structures with an additive manufacturing method avoiding the constraints of traditional technologies. [ABSTRACT FROM AUTHOR]

We simulate cataclastic flow deformation using discrete elements for high porous Bentheim sandstone under 1D compression and high confinement (~300 MPa) to assess the flow path and permeability evolution during cataclasis. The model accounts for particle crushing by replacing balls with smaller fragments and cement damage by removing existing bonds beyond a threshold stress level. The particle packing in the deformed numerical specimens is further analysed using an image processing tool to extract the pore structure. The analysis suggests that beyond 10% particle breakage, there is a decreasing trend in tortuosity, indicating the crushed finer fragments enable additional flow channels. The same is quantitatively ascertained through pore coordination number and visual identification. The overall analysis implies that during the compression under high confinement, the rate of permeability reduction depends on the flow path evolution due to crushing, and tortuosity can decrease due to excessive crushing. [ABSTRACT FROM AUTHOR]

Based on the tortuous capillary network model, the relationship between anisotropic permeability and rock normal strain, namely the anisotropic dynamic permeability model (ADPM), was derived and established. The model was verified using pore-scale flow simulation. The uniaxial strain process was calculated and the main factors affecting permeability changes in different directions in the deformation process were analyzed. In the process of uniaxial strain during the exploitation of layered oil and gas reservoirs, the effect of effective surface porosity on the permeability in all directions is consistent. With the decrease of effective surface porosity, the sensitivity of permeability to strain increases. The sensitivity of the permeability perpendicular to the direction of compression to the strain decreases with the increase of the tortuosity, while the sensitivity of the permeability in the direction of compression to the strain increases with the increase of the tortuosity. For layered reservoirs with the same initial tortuosity in all directions, the tortuosity plays a decisive role in the relative relationship between the variations of permeability in all directions during pressure drop. When the tortuosity is less than 1.6, the decrease rate of horizontal permeability is higher than that of vertical permeability, while the opposite is true when the tortuosity is greater than 1.6. This phenomenon cannot be represented by traditional dynamic permeability model. After the verification by experimental data of pore-scale simulation, the new model has high fitting accuracy and can effectively characterize the effects of deformation in different directions on the permeability in all directions.

The path tortuosity t is an indicator of rill morphology accounting for the deviation of the thalweg from a straight alignment. The effect of t on flow resistance has been little investigated for rills. This paper reports the results of a plot investigation aimed to establish the suitable accuracy of the rill thalweg measurement to determine the tortuosity parameter and to test the reliability of a theoretical flow resistance law. Four rills were incised in clay soil (CS) and clay-loam soil (LS) and shaped by a clear flow discharge. The three-dimensional Digital Terrain Models were created by the Structure from Motion technique. For rills on LS, an approximate thalweg was tracked by photo-interpretation, and a specific calculation routine was applied to identify the cross sections with a constant spacing d. The actual rill thalweg was obtained as the line joining the lowest points of these cross-sections. Among the different tested d values, d = 0.075 m was chosen to determine t. For both CS and LS, the Darcy-Weisbach friction factor f featured a non-monotonic relation with t, which was explained as the result of three additive components due to bed roughness, sediment transport, and localized energy losses due to curves. The effect of the former two components on f contrasts that of the third, resulting in a linearly decreasing f-t relationship and constant flow velocity for the three lowest tortuosity values, and an increased friction factor and reduced flow velocity for the highest tortuosity value. The flow resistance law was positively tested, and the predicted friction factor was dependent on t.

Background Subarachnoid hemorrhage (SAH) associated with vessel injury during endovascular therapy for acute ischemic stroke is a known complication. Arterial anatomy may predispose to increased risk of SAH and technical safety, yet factors such as clot location, arterial size, and tortuosity have not been explored. We examined these anatomic factors with respect to SAH during thrombectomy. Methods Arterial anatomy at the site of occlusion and mechanical thrombectomy during device deployment was detailed by the STRATIS (Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke) core laboratory. Luminal diameters, arterial branching, and segmental tortuosity were measured. Arterial tortuosity was quantified using the distance factor metric. Statistical analyses included descriptive variables of arterial anatomy, with univariable and multivariable modeling to predict SAH. Results Arterial tortuosity in each segment from the proximal cerebral arteries to the site of occlusion was quantified in 790 subjects treated with mechanical thrombectomy in STRATIS. Cumulative arterial tortuosity to the site of vessel occlusion was greater in distal lesions. SAH was clearly linked with more distal thrombectomy (P = 0.02), occurring in 19.0% of distal M2, 16.7% of M3, 7.3% of distal M1, 5.8% of proximal M2, 2.4% of distal internal carotid artery, and 2.1% of proximal M1. In multivariable analysis after adjusting for arterial diameter at the site of occlusion, arterial tortuosity was a significant predictor of SAH (upper tertile versus 1: odds ratio, 3.08 [95% CI, 1.04–9.09]; P = 0.04), while arterial diameter was unrelated to SAH (P = 0.30) when accounting for tortuosity. Conclusion This novel analysis of arterial tortuosity and angiographic anatomy during mechanical thrombectomy establishes tortuosity as a determinant of SAH, providing insight for future techniques and innovative device designs.

A detailed study comparing two – dry and wet – numerical approaches to model filtration processes at stake in actual granular filters is presented using the discrete element method (DEM). In the first approach, the migration of fines is provided by gravitational forces, while in the second, hydrodynamic forces induce their movement. Numerical filtration tests were performed on granular filters involving materials with different gradings and porosities. The study demonstrated that the wet filtration approach generates higher tortuosity due to the possibility for fines to deviate from direct paths towards more open sideways. It leads to a lower coefficient of retention for the filter than if it were characterised using a dry filtration approach. However, the intensity of this feature greatly depends on the grading and the porosity of the granular filter. Finally, an enhanced dry filtration model designated as the "equivalent cyclic wet filtration model" is presented, which better mimics the results obtained through the preferable wet filtration model compared to the original dry filtration model. This new model constitutes a valuable alternative tool for studies of filtration properties in granular materials. [ABSTRACT FROM AUTHOR]

The prediction accuracy of soil thermal conductivity is crucial to the design of geothermal-related structures such as ground source heat pump and borehole heat. Based on the complex, random and self-similar microstructure characteristics of soil,by using fractal theory to consider the effects of soil porosity, particle arrangement and other parameters on soil curvature, a capillary physical model and a corresponding mathematical model of effective thermal conductivity of three-phase soil were established. The predicted results of the model were compared with existing experimental data. The results show that the model with the addition of soil particle arrangement and other parameters has higher accuracy in predicting the soil thermal conductivity with porosity between 0. 21 ~ 1, and the three-phase soil thermal conductivity with different porosity is related to the soil particle arrangement blocking parameters. The larger the porosity and the smaller the blocking parameters, the closer the model prediction is to the experimental results. The bending degree has a direct influence on the series-parallel ratio of the thermoelectric ratio model. The influence of soil particle arrangement on the bending degree decreases with the increase of porosity, and the bending degree is inversely proportional to the change trend of the three-phase soil thermal conductivity. The relevant results are helpful to the research of the three-phase soil heat transfer efficiency of buried pipe and outside pipe. [ABSTRACT FROM AUTHOR]

Aerogels are porous ultralight materials known for their high porosity, wide range of pore sizes, low density, and good macroscopic mechanical properties, all of which make them promising candidates for shaped adsorbents, catalysts, and insulators, among other applications. Here, this work reports a new approach that enables both the formation of modular aerogels, via dynamic covalent chemistry, and their post‐synthetic modification, via coordination chemistry. To demonstrate this strategy, this work first polymerizes porous amino‐functionalized Rh(II)‐based metal‐organic polyhedra (MOPs) with aldehydes, which afforded robust imine‐gel networks that is then converted into aerogels. Next, this work functionalizes these aerogels through the coordination of ligands on the axial site of Rh(II) paddlewheels of the MOP. Interestingly, in this chemistry, the local changes in the coordination site of the MOPs are transferred to the overall aerogel, thereby altering its macroscopic physicochemical properties. Importantly, this feature enables the synthesis of optimized adsorbents tailored to specific guests, as this work demonstrates through a series of experiments using ligands of different electrostatic and hydrophobic characters. [ABSTRACT FROM AUTHOR]

Background: Supra aortic obstruction in children is uncommon and is seen in certain unique conditions. While intraluminal obstruction due to heavy calcification is seen in older populations, it is not described in pediatric populations. The coral reef aorta is a rare and distinct calcifying disease causing luminal obstruction of the suprarenal aorta in adults. The definition of this diagnosis relies entirely on the unique aspects and consistency of the lesions, which are rock-hard, irregular, gritty plaques with a white luminal surface resembling a coral reef. However, no such case has been described in children. Case presentation: We present an adolescent boy who presented with a heavily calcified ascending aortic lesion associated with aortopathy and hypertension, 12 years after an aortic coarctation repair. The investigations included echocardiography, magnetic resonance and computer-tomographic imaging. A 3-D model was printed in order to visualize and plan surgical steps in advance for safe placement of clamps and defining the extent of resection. In addition, it provided an idea about tissue quality, thickness, spatial relationship, and orientation in relation to surrounding structures. Successful resection and replacement of the diseased segment of the aorta were achieved on cardiopulmonary bypass support. Post-operative recovery was uneventful, and at 6-month follow-up, the patient is doing well. In this report, various aspects of such lesions have been discussed, including clinical presentations, complications, planning and conduct of a safe cardiopulmonary bypass, and precautions during surgery for a successful outcome. Conclusion: Complicated obstructive aortic lesions in children require careful assessment, appropriate advanced imaging, and the use of 3-D printing technology in order to plan and perform safe and effective surgical management. The etiology of severe calcified aorta in children may be related to metabolic factors, previous surgery, use of a homograft, or an inflammatory process. However, it has yet to be proven. [ABSTRACT FROM AUTHOR]

The pore geometry of porous rocks is fundamental for accurate description of stress dependence of effective permeability, which is an important parameter of mass transfer in porous rocks. An important physical assumption that porous rocks contain numerous elliptical or spherical pores has been shown to be successfully applied to many aspects of hydromechanical coupling properties of porous rocks. To investigate the detailed description of pore structures on the degree of effect on the coupled hydromechanical process, in this work, a generalized stress-dependent model for permeability of porous rocks has been proposed based on fractal geometry theory and mechanics of porous rock. The proposed model is expressed as a nonlinear function of pore structure parameters, such as aspect ratio ( γ σ ), the fractal dimensions ( D T , σ and D T , a v ) for tortuosity, the initial fractal dimension ( D f , 0 ), and initial porosity ( ϕ 0 ) as well as matrix elastic constants (E and ν) of porous rocks without any empirical parameter. The validity of the proposed models is verified by the good agreements between available experimental data and theoretical predictions of stress-dependent permeabilities of porous rocks. Detailed discussions of the essential effects of pore structures parameters and material elastic constants of porous rocks on the dimensionless stress-dependent permeabilities are performed. It is found that the stress parameters (E and γ 0 ) have remarkable effects on the dimensionless stress-dependent permeabilities compared with other parameters ( ϕ 0 and ν). The proposed model may contribute to a better quantitative understanding of the coupled hydromechanical properties of porous rocks. [ABSTRACT FROM AUTHOR]

The Kozeny–Carman (KC) equation is a well-known semi-empirical formula, which is used to calculate the permeability of porous media in the seepage field. The KC constant is an empirical constant in the KC equation. In this paper, based on the fractal theory, the Fractal-Monte Carlo technique is used to simulate the KC constant of the roughened fibrous porous media (RFPM) with micro-scale effects. There is no empirical constants in the proposed model, and each parameter has its physical meaning. The KC constant model of RFPM can be expressed as a function of structural parameters, including relative roughness (), porosity (ϕ), pore area fractal dimension ( D f ), tortuosity fractal dimension ( D T ), capillary diameter (λ) and Knudsen number (Kn). The result shows that the KC constant increases with increases in ϕ , , D f and D T . On the contrary, with increases in λ and Kn , the KC constant decreases. In addition, the KC constant model constructed in the paper agrees well with the existing experimental data and the model. According to the proposed Fractal-Monte Carlo technique, it is possible to better clarify the transmission physical mechanism in RFPM with micro-scale effects. [ABSTRACT FROM AUTHOR]

The purpose of this study is to develop a systematic meso‐level theoretical modeling approach for analyzing the mode‐I fracture failure behaviors of concrete. Firstly, the eXtended Universal Morphological Model (XUMM) is briefly reviewed. Secondly, a normalized analysis method for the evaluation of effects of properties and scales of meso structures on the performance of concrete is proposed based on the XUMM. Afterwards, parametric studies regarding the aggregate strength effect, the aggregate volume effect, the maximum aggregate size (MAS) effect, the tortuosity of mesoscopic crack, the roughness of fracture surface and the characteristic length are conducted. At last, a case study on the MAS effect based on experimental tests is provided to verify the applicability of the XUMM. [ABSTRACT FROM AUTHOR]

Purpose: To explore the long-term course of patients with meibomian gland dysfunction (MGD), and to analyse potential factors affecting the recovery of meibomian gland (MG) dropout. Methods: Seventy-nine MGD patients (79 eyes) aged 36.03±15.78 years old who underwent more than one year of follow-up were enrolled in this retrospective study. Corneal fluorescein staining (CFS), tear meniscus height (TMH), noninvasive breakup time (NIBUT), and noncontact meibography at baseline and last visit were collected and analysed. Then an automatic MG analyzer was used to measure the morphological and functional parameters of MGs, including their area ratio (AR), tortuosity index (TI), and signal index (SI). The patients whose AR increased by more than 5% were defined as MG improvement, and AR decreased by more than 5% was MG worsening. Results: A total of 79 patients (79 eyes) were assessed with at least 1-year of follow-up. More than 1/3 of MGD patients (27 eyes, 34.2%) underwent MG improvement, and 30.4% of MGs became worsened. Age (P=0.002), gender (P<0.001), IPL treatment (P=0.013), the change of CFS (P=0.0015), and the recovery of SI (P=0.035) showed significant differences among different recovery groups. Age(P<0.001), female sex (P=0.003), ΔCFS (P<0.001), AR at baseline (P<0.001) were negative correlation with AR recovery, and the change of SI (P=0.003) and IPL treatment (P=0.003) had a positive correlation with it. Among them, age (P=0.038), the change of CFS (P=0.004), and AR at baseline (P=0.007) were confirmed as negatively correlated factors predicting the long-term change of the MG. Conclusion: Although the MGD treatment has continued for more than 1 year, only 34.2% of MGD patients were observed to undergo MG improvement. Younger patients and patients with better CFS recovery seem to have more opportunities to improve their MGs. [ABSTRACT FROM AUTHOR]

Triply periodic minimal surfaces (TPMSs) are relevant structures for building synthetic bone grafts due to their tortuosity and interconnected pores. In order to investigate their porosity and mechanical properties, three different hydroxyapatite-based TPMSs were printed by vat polymerization: the Schwartz diamond, Schwartz primitive, and gyroid scaffolds. Each structure was designed with three levels of porosity, two different pore sizes, and two different wall thicknesses so as to gain an understanding of the effect of pore size and wall thickness on the mechanical properties. The results highlighted the importance of cleaning in the manufacturing process and its impact on the final porosity, especially for small pore sizes. This article intends to be among the first to discuss mechanical testing with macro spherical indentation. Bending and macro spherical indentation resistance tests revealed differences in the mechanical properties between the different structures, with a strong sensitivity of bending strength to the presence of cracks after thermal treatment. Notably, increasing the wall thickness was shown to increase the risk of damage to the solid parts of the scaffolds, therefore lowering the bending strength. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper presents the hydrogen reduction behaviour of industrial pellets designed for the efficient hydrogen based direct reduction. The pellets were provided with very low non ferrous oxides percentage (0.52 of basicity index) and with the absence on TiO 2 oxides. The pellets measured diameters in the range 1.14–1.72 cm and were characterized in terms of porosity, pores size, tortuosity and compression strength. The pellets were reduced in hydrogen atmosphere in a laboratory shaft furnace in the temperature ranges of 600–1200 °C at the pressures of 1 and 5 bar. The pellets' reduction behaviour was analysed in terms of time to reduction, rate of reduction and kinetics constant. All the obtained results were analysed through the employment of a commercial multi-objective optimization tool (modeFrontier) in order to precisely define the effect of each single parameter on the pellets' reduction. It was also defined the effect of the ongoing reduction rate of the final metallization of the starting iron oxides. • High grade pellets were rapidly direct reduced through hydrogen. • Porosity and pores size evolve in hydrogen as a function of the reduction temperature. • The kinetics of reduction depends on the starting pellets properties. [ABSTRACT FROM AUTHOR]

High grade pellets with basicity index close to 0.5 were directly reduced in pure hydrogen atmosphere. The reduction experiments were performed in the temperature range 800–1000 °C at the pressure of 8 bar. The pellets internal structure was analysed through micro tomography observations in the unreduced and reduced conditions. After reduction, the pellets showed a variation of porosity up to more than 15% with a remarkable change in the pore dimensions and aspect. Given the pores aspect variations, tortuosity strongly varied. This is believed to have large influence on the pellets reduction kinetics depending on the reduction conditions. After reduction, the pellets were re-oxidized in the temperature range 200–700 °C for different times. Up to 500 °C the weight increase due to oxidation resulted very slow, for higher temperatures the re-oxidation behaviour showed a very remarkable acceleration. • High grade pellets were direct reduced through hydrogen at high pressure. • Porosity is reduced by a maximum of 15% after reduction. • The kinetics of reduction depends on the composition and porosity of the pellets. • Reoxidation resulted slow up to 500 °C in air. • A remarkable acceleration of the reoxidation was recorded at 600 and 700 °C in air. [ABSTRACT FROM AUTHOR]

This article presents an improved and extended modeling approach for acoustic wave propagation in rigid porous materials, focusing on examples, such as plastic foams used for noise reduction in automotive applications. We demonstrate that the classical model (Johnson-Champoux-Allard) in the asymptotic high-frequency limit, widely employed in the literature, fails to accurately reconstruct the transmitted acoustic signal through high absorbent porous materials characterized by significant wave attenuation. The study focuses on the airborne ultrasonic frequency range (30–200 kHz). To address this limitation, we introduce new non-acoustic parameters Σ and V for viscous effects, and Σ ′ and V ′ for thermal effects, with surface and volumetric dimensions, respectively, allowing for the reconstruction of the transmitted signal and accurate modeling of the pronounced acoustic attenuation within the material. These parameters are incorporated into the expansion on skin depths of the dynamic tortuosity α(ω) and thermal tortuosity α ′ (ω) response functions, which describe the inertial-viscous and thermal interactions between the fluid and the solid, respectively. This novel modeling approach enables a more comprehensive study of high attenuating porous media, which are crucial for effective noise reduction. Additionally, it opens up new possibilities for characterization beyond the capabilities of current models. [ABSTRACT FROM AUTHOR]

Coronary tortuosity has been recognized as a potential pathophysiological mechanism in the development of non-obstructive coronary artery disease (CAD). The aim of this study was to examine the role of two coronary tortuosity measurement methods in the detection of clinically significant coronary tortuosity. The study included 160 patients with angina symptoms and myocardial ischemia detected by cardiac stress tests in chronic settings and those diagnosed with acute coronary syndrome. After coronary angiography, tortuosity of coronary arteries was assessed by two methods, including measurement of tortuosity angles and calculating of tortuosity index. Significantly more tortuous coronary arteries were detected in the group with non-obstructive CAD (p < 0.01 for all three arteries), with significantly higher tortuosity index (TI) for all three coronary arteries in this group of patients, compared to patients with obstructive CAD. The highest TI for LCX was found in patients with lateral ischemia (p < 0.001) and for LAD in patients with anterior ischemia (p < 0.001). When measured by the angle method, the only association was found between LCX tortuosity and lateral ischemia (OR 4.9, p = 0.046). In conclusion, coronary tortuosity represents a pathophysiological mechanism for myocardial ischemia in non-obstructive CAD. The coronary tortuosity index could be a reliable and widely applicable tool for the quantification of coronary tortuosity. [ABSTRACT FROM AUTHOR]

This report addresses three variants identified within a female cadaver. Specifically, these were an anomalous origin of the right suprarenal artery, an abnormal bilateral ovarian vein branch, and a arterial tortuosity of the left ovarian artery. Indeed, the cadaver evinced abnormal origins in the case of the middle suprarenal artery (MSA), right inferior phrenic artery (IPA), and the renal capsule artery (emanating from the right renal artery). The MSA and IPA shared a common trunk with the inferior suprarenal artery. It was additionally observed that the right ovarian vein anastomoses the branches from the right kidney posterior inferior along with those to the renal fat capsule. Abnormal origin was evident in the case of the left ovarian artery, and arterial tortuosity was apparent in the lower region of the vessels. This report addresses both the clinical import of these variations and their likely causes. In the subdiaphragmatic region, surgical success and prognosis may be impacted by such anomalies; accordingly surgeons must be aware of anatomical variants of the ovarian and suprarenal arteries. [ABSTRACT FROM AUTHOR]

Conventional Pervious Concrete (CPC) addresses flash flooding and urban heat island effect. However, the major problems observed in CPC pavements include 'clogging' and 'ravelling' reduces its functionality. This study proposes a new method of preparing pervious concrete (PC) to limit clogging and ravelling, which is referred to as two-layered pervious concrete (2L-PC). Several combinations of top and bottom layers with different aggregate sizes were studied initially using AutoCAD to identify the combination, resulting in a minimum of 20% interface porosity. The selected combinations were investigated for basic properties, flow, and clogging behaviour. A well-defined relationship between density and porosity was found, which was in the domain of CPC. The average permeability, clogging, and rejuvenation potential varied in the range 0.16–0.75 cm/s, 63.74–93.88% and 57.82–80.13%, respectively. It was observed that, 2L-PC with 4.75 mm (Top) – 9.5 mm (Bottom) had higher permeability, lower clogging potential, and higher rejuvenation potential. It was found that on an average, 53–59% of clogging materials were restrained from entering into the pore structure and at least 60% of their original permeability was recovered by all the samples post-rejuvenation, which make the material clogging resistant and well suitable for porous pavement applications. [ABSTRACT FROM AUTHOR]

For concrete materials, durability is closely related to the mass transport property. The tortuosity of concrete material is an important factor accounting for the transport property. In this paper, the tortuosity of concrete is studied by mercury intrusion porosimetry and permeation tests in order to consider the existence of aggregate induced in the interfacial transition zone (ITZ). Tortuosity gained through the corrugated pore structure model and the Katz–Thompson model are compared and analysed to quantify the tortuosity of fly ash concrete. The ITZ was observed by scanning electron microscopy. The results show that the effect of aggregate should be considered when studying the tortuosity of concrete materials. With an aggregate value fraction of 43.8%, when considering the ITZ around coarse aggregate, concrete tortuosity is 1.29–16.18 times higher than that of the mortar matrix. [ABSTRACT FROM AUTHOR]

Continuous monitoring of artery and vein vessels in the human eye to prevent the loss of eyesight is essential in the diagnosis of diabetic retinopathy. The progression of diabetic retinopathy is echoed by the internal anatomical changes of the retina, such as changes in the artery vein ratio, formation of fake vessels, tortuosity, lesion formation, etc. Among these symptoms, calculation of the artery vein ratio is still a challenging task since the visibility of the artery and vein changes over different regions in the fundus image. The proposed Atrous Depth Concatenated neural network with the enriched encoder (EEDCFCNN) architecture for artery vein classification is based on the deep semantic segmentation architecture. The proposed architecture can achieve an improved result on the public databases DRIVE, INSPIRE, and IOSTAR. [ABSTRACT FROM AUTHOR]

Understanding the integrated transport behavior of oil in shale nanopores is critical to efficient shale oil development. In this paper, based on the time-dependent Poiseuille flow momentum equation, we present a novel transient model to describe oil transport in unsteady and steady states. The model incorporates the effect of the critical shift density, apparent viscosity, slip length, and alkane property, as well as pore tortuosity and surface roughness. We evaluated our model through a comparison with other models, experiments, and molecular dynamics simulations. The results show that the development rates of the volume flows of C6–C12 alkane confined in inorganic nanopores and C12 alkane confined in organic nanopores were faster than that of the corresponding bulk alkane. In addition, the critical drift density positively promoted the volume flow development rate in the unsteady state and negatively inhibited the mass flow rate in the steady state. This effect was clearest in pores with a smaller radius and lower-energy wall and in alkane with shorter chain lengths. Furthermore, both the nanoconfinement effect and pore structure determined whether the volume flow enhancement rate was greater than or less than 1. The rate increased or decreased with time and was controlled mainly by the nanoconfinement effect. Moreover, as the wall energy increased, the flow inhibition effect increased; as the carbon number of alkane increased, the flow promotion effect increased. The results indicate that the proposed model can accurately describe oil transport in shale nanopores. [ABSTRACT FROM AUTHOR]

Tortuosity of intracranial arteries has been proven to be associated with the risk of intracranial aneurysm development. We decided to analyze which aspects of tortuosity are correlated with hemodynamics parameters promoting intracranial aneurysm development. We constructed 73 idealized models of tortuous artery (length: 25 mm, diameter: 2.5 mm) with single bifurcation. For each model, on the course of segment before bifurcation, we placed 1–3 angles with measures 15, 30, 45, 60, or 75 degrees and arc lengths 2, 5, 7, 10, or 15 mm. We performed computational fluid dynamics analysis. Blood was modeled as Newtonian fluid. We have set velocity wave of 2 cardiac cycles. After performing simulation we calculated following hemodynamic parameters at the bifurcation: time average wall shear stress (TAWSS), time average wall shear stress gradient (TAWSSG), oscillatory shear index (OSI), and relative residence time (RRT). We found a significant positive correlation with number of angles and TAWSS (R = 0.329; P < 0.01), TAWSSG (R = 0.317; P < 0.01), and negative with RRT (R = −0.335; P < 0.0.01). Similar results were obtained in terms of arcs lengths. On the other hand, mean angle measure was negatively correlated to TAWSS (R = −0.333; P < 0.01), TAWSSG (R = −0.473 P < 0.01), OSI (R = −0.463; P < 0.01), and positively to RRT (R = 0.332; P < 0.01). On the basis of the obtained results, we developed new tortuosity descriptor, which considered angle measures normalized to its arc length and distance from bifurcation. For such descriptor we found strong negative correlation with TAWSS (R = −0.701; P < 0.01), TAWSSG (R = 0.778; P < 0.01), OSI (R = −0.776; P < 0.01), and positive with RRT (R = 0.747; P < 0.01). Hemodynamic parameters promoting aneurysm development are correlated with larger number of smaller angles located on larger arcs. [ABSTRACT FROM AUTHOR]

The contact of rock joints during shearing induced by underground excavation significantly impacts the hydro-mechanical behaviour of fractured rock mass, since fluid tends to flow through a rough-walled fracture along connected channels while bypassing the contact areas with tortuosity. However, previous research mostly considered joint roughness or aperture changes based on 2D joint profiles, while the contact and tortuosity using 3D surfaces were often overlooked. This paper considers the evolution of contact area and aperture distribution during shearing. The concept of the critical inclination angle is introduced and correlated with the contact area during shearing based on Grasselli's criterion. The standard deviation of the mean mechanical aperture is calculated using the modified algorithm. An improved model for estimating the hydraulic aperture with the mechanical aperture is then developed, applying an aperture correction term and a contact correction term. A number of shear-flow tests on artificial joint samples under constant normal loads are conducted. The accuracy and reliability of the proposed model are verified by comparing it against the experimental results and by comparing the prediction performance with other published models. Results show that the proposed model can improve the prediction of the hydraulic aperture and hydraulic conductivity of a single rock joint during shearing. Highlights: An improved model is proposed to estimate hydraulic aperture with mechanical aperture, incorporating aperture and contact correction terms. The evolutions of geometric morphologies during shear can be computed, and the effects on flow behaviour are well described. A series of coupled shear-flow tests are conducted on two artificial joints with different surface characteristics under constant normal loads. The proposed model can predict the shear-flow coupled behaviour of rock joints with good accuracy. [ABSTRACT FROM AUTHOR]

Arterial tortuosity syndrome (ATS) is a very rare autosomal recessive disorder that affects the connective tissue. The incidence of ATS is not well known and to date only 106 patients have been described in the literature. ATS affects medium and large size arteries, leading to widespread elongation and intensification of the average vessel tortuousness, responsible of several loops and kinks. Like other connective tissue disorders, ATS can present with joint laxity, hernias, pectus excavatum, scoliosis or other musculoskeletal abnormalities, and ocular defects. Due to the extreme variability of clinical symptoms and the fact that ATS has no curative management, prompt diagnosis is of tremendous importance to prevent disease-associated complications. In this situation, imaging techniques have a central role. In this study, we describe a rare case of a male newborn with tortuosity and lengthening of the main arterial and venous medium and large caliber branches with associated aortic coarctation who passed away prematurely. The finding of aortic coarctation in a newborn with ATS has rarely been described in the literature. [ABSTRACT FROM AUTHOR]

Background: Intracranial vessel tortuosity is a key component of dolichoectasia and has been associated with atherosclerosis and adverse neurologic outcomes. However, the evaluation of tortuosity is mainly a descriptive assessment. Purpose: To compare the performance of three automated tortuosity metrics (angle metric [AM], distance metric [DM], and distance‐to‐axis metric [DTA]) for detection of dolichoectasia and presence of segment‐specific plaques. Study Type: Observational, cross‐sectional metric assessment. Population: 1899 adults from the general population; mean age = 76 years, female = 59%, and black = 29%. Field Strength/Sequence: 3‐T, three‐dimensional (3D) time‐of‐flight MRA and 3D vessel wall MRI. Assessment: Tortuosity metrics and mean luminal area were quantified for designated segments of the internal carotid artery, middle cerebral artery, anterior cerebral artery, posterior cerebral artery, vertebral artery, and entire length of basilar artery (BA). Qualitative interpretations of BA dolichoectasia were assessed based on Smoker's visual criteria. Statistical Tests: Descriptive statistics (2‐sample t‐tests, Pearson chi‐square tests) for group comparisons. Receiver operating characteristics area under the curve (AUC) for detection of BA dolichoectasia or segment‐specific plaque. Model inputs included 1) tortuosity metrics, 2) mean luminal area, and 3) demographics (age, race, and sex). Results: Qualitative dolichoectasia was identified in 336 (18%) participants, and atherosclerotic plaques were detected in 192 (10%) participants. AM‐, DM‐, and DTA‐calculated tortuosity were good individual discriminators of basilar dolichoectasia (AUCs: 0.76, 0.74, and 0.75, respectively), with model performance improving with the mean lumen area: (AUCs: 0.88, 0.87, and 0.87, respectively). Combined characteristics (tortuosity and mean luminal area) identified plaques with better performance in the anterior (AUCs ranging from 0.66 to 0.78) than posterior (AUCs ranging from 0.54 to 0.65) circulation, with all models improving by the addition of demographics (AUCs ranging from 0.62 to 0.84). Data Conclusion: Quantitative vessel tortuosity metrics yield good diagnostic accuracy for the detection of dolichoectasia. Level of Evidence: 1 Technical Efficacy Stage: 2 [ABSTRACT FROM AUTHOR]

Background: The internal carotid artery (ICA) is one of the vital structures of the head and neck region to be preserved during neck dissection. It may present several unusual forms of tortuousness, and surgeons should be mindful of these variations while performing surgeries. Case presentation: The patient is an 80‐year‐old woman presented with a T2N0M0 squamous cell carcinoma affecting the left side of the tongue. During neck dissection, significant tortuosity of the ICA was observed. With careful surgical manipulation, the surgery was a success, avoiding any potential damage. Conclusion: Surgeons must avoid the potentially fatal complication through a detailed preoperative imaging evaluation and careful intraoperative observation. [ABSTRACT FROM AUTHOR]

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The pore-type hydrate reservoirs in the permafrost region of the Qilian Mountains (PRQM) have complex characteristics, including low porosity, low permeability, high shale content, and conductive minerals. Currently, the research on the electrical properties of these reservoirs still needs to be sufficiently in depth, and there are limitations in well-logging evaluation methods. To fill in this gap, a conductivity model of pore-type gas hydrate reservoirs (GHRs) is established based on the pore-combination modeling theory to investigate the influencing factors of the resistivity characteristics of GHRs through numerical simulations. The comparison between the laboratory-measured resistivity of different hydrate saturations and the results of the calculated model shows good agreement, indicating the accuracy of the conductivity model in describing the electrical characteristics of GHRs in the PRQM. Compared to conductive minerals, the numerical simulation results indicate that the high shale content is the main reason for the decrease in resistivity of pore-type GHRs in the study area. The hydrate saturation evaluation of well DK-3 from 386.3 to 393.6 m depth shows that the hydrate saturation ranges from 5.1 to 66.4%, with an average value of 44.0%. The identified hydrate interval using this model is consistent with the actual hydrate interval encountered during the drilling. This study, as an innovation, can help clarify the conductive mechanism of pore-type GHRs in the PRQM and provide more accurate parameters for evaluating gas hydrate resources in the study area. [ABSTRACT FROM AUTHOR]

In the Sichuan Basin, bitumen widely distributes in the carbonate reservoir, and the bitumen occurrence morphology affects the pore structure and petrophysics. Two types of bitumen, boundary-filled and centre-filled, were reconstructed using a pore morphology-based method based on dolomite carbonate digital cores from X-ray computerized tomography. The pore structures of the reconstructed bitumen-filled digital core models were determined using an extracted pore network model. The finite element method simulated the electrical resistivity of the digital core model. The investigation showed that (i) boundary-developed bitumen increases the pore size whereas centre-developed bitumen decreases the pore size, and bitumen development increases the shape factor while reducing the coordination number; (ii) for electrical resistivity, boundary-filled bitumen increases the porosity exponent with increasing pore size, whereas centre-filled bitumen decreases the porosity exponent. Bitumen development caused a negative correlation between the porosity exponent and pore shape factor, a logarithmic increase between the porosity exponent and coordination number, and a power increase between the porosity exponent and porosity. Subsequently, a new porosity exponent model related to porosity was proposed based on the curve-fitting method. This new porosity exponent combines the Archie equations to calculate the saturation of the carbonate reservoir in the Sinian Dengying Formation in the Penglai gas area on the northern slope of the central Sichuan paleo-uplift, which fits the sealed core plug saturation well and provides the basis for further reservoir evaluation and fluid identification in the Penglai gas area. [ABSTRACT FROM AUTHOR]

Polymeric heart valves offer the potential to overcome the limited durability of tissue based bioprosthetic valves and the need for anticoagulant therapy of mechanical valve replacement options. However, developing a single‐phase material with requisite biological properties and target mechanical properties remains a challenge. In this study, a composite heart valve material was developed where an electrospun mesh provides tunable mechanical properties and a hydrogel coating confers an antifouling surface for thromboresistance. Key biological responses were evaluated in comparison to glutaraldehyde‐fixed pericardium. Platelet and bacterial attachment were reduced by 38% and 98%, respectively, as compared to pericardium that demonstrated the antifouling nature of the hydrogel coating. There was also a notable reduction (59%) in the calcification of the composite material as compared to pericardium. A custom 3D‐printed hydrogel coating setup was developed to make valve composites for device‐level hemodynamic testing. Regurgitation fraction (9.6 ± 1.8%) and effective orifice area (1.52 ± 0.34 cm2) met ISO 5840‐2:2021 requirements. Additionally, the mean pressure gradient was comparable to current clinical bioprosthetic heart valves demonstrating preliminary efficacy. Although the hemodynamic properties are promising, it is anticipated that the random microarchitecture will result in suboptimal strain fields and peak stresses that may accelerate leaflet fatigue and degeneration. Previous computational work has demonstrated that bioinspired fiber microarchitectures can improve strain homogeneity of valve materials toward improving durability. To this end, we developed advanced electrospinning methodologies to achieve polyurethane fiber microarchitectures that mimic or exceed the physiological ranges of alignment, tortuosity, and curvilinearity present in the native valve. Control of fiber alignment from a random fiber orientation at a normalized orientation index (NOI) 14.2 ± 6.9% to highly aligned fibers at a NOI of 85.1 ± 1.4%. was achieved through increasing mandrel rotational velocity. Fiber tortuosity and curvilinearity in the range of native valve features were introduced through a post‐spinning annealing process and fiber collection on a conical mandrel geometry, respectively. Overall, these studies demonstrate the potential of hydrogel‐polyurethane fiber composite as a heart valve material. Future studies will utilize the developed advanced electrospinning methodologies in combination with model‐directed fabrication toward optimizing durability as a function of fiber microarchitecture. [ABSTRACT FROM AUTHOR]

Objective: Tortuosity of the carotid artery is a common angiographic finding that may impact blood flow and neuronal function. However, information on its prevalence and risk factors remains limited. In this study, we determined to explore the factors affecting carotid artery tortuosity. Methods: The head and neck computed tomography angiography (CTA) imaging and cerebral angiography data performed at the Second Affiliated Hospital of Wenzhou Medical University between January 2019 and September 2021 were collected, and a total of 356 cases were enrolled in the study after screening. Carotid artery tortuosity refers to the angle between the two adjacent segments of the carotid artery, from the opening of the aortic arch on either side to the external orifice of the carotid canal, being less than 150°. A retrospective analysis was performed to compare the general information, laboratory indicators, personal history, and medical history between the two groups. The χ2 test, t-test, and Mann–Whitney U-test were performed to compare the parameters between the two groups. If there were significant differences between the groups, multivariate logistic regression was performed to analyze the factors affecting carotid artery tortuosity. Results: A total of 222 of the 356 cases were determined to have carotid artery tortuosity, accounting for 63.6%. There were statistically significant differences in age, body mass index (BMI), duration of diabetes and hypertension, levels of low-density lipoprotein cholesterol (LDL-C), diastolic blood pressure, history of ischemic and hemorrhagic stroke, and the usage of antihypertensive drugs between the two groups. Multivariate logistic regression analysis of the above factors showed that age (OR= 5.063, 95% CI 2.963–10.26, p < 0.001) and duration of hypertension (OR= 2.356, 95% CI 1.353–8.625, p = 0.021) were associated with a higher incidence of carotid artery tortuosity. Compared to patients who did not consume antihypertensive drugs, the incidence of carotid artery tortuosity was significantly less (OR= 0.094, 95% CI 0.002–0.713, p = 0.019) in those consuming antihypertensive drugs. Conclusion: Carotid artery tortuosity is a relatively common carotid artery disease. The incidence of carotid artery tortuosity may increase with age and the duration of hypertension. The consumption of antihypertensive drugs may reduce the incidence of carotid artery tortuosity. [ABSTRACT FROM AUTHOR]

The objective of this study is to assess the ability of an Artificial Circulatory Phantom (ACP) to verify its accuracy in simulating the movement of artificial vessels vs. real vessels under changing cardiovascular parameters such as heartbeat, ejection fraction, and total peripheral resistance. The experiments were conducted with blood-like fluid that flows through two types of vessels: iliac arteries and different types of ePTFE vascular prostheses. Parameters such as diameter and tortuosity were measured and analyzed. The flow characteristics included a pulsating pattern with a frequency of 60–120 min−1 and ejection volumes ranging from 70 to 115 mL. The results showed a predominantly positive correlation between wall displacement (Wd) and tortuosity index (Ti) for the iliac artery (R2 = 0.981), as well as between Wd and mean tortuosity index (MTi) (R2 = 0.994). Similarly, positive correlations between Wd and Ti (R2 = 0.942) and Wd and MTi (R2 = 0.922) were computed for the ePTFE vascular prosthesis. The ACP introduced in this study is a valuable tool for evaluating various vessel types and the spatial configurations of vascular prostheses under diverse hemodynamic conditions. These findings are promising for the advancement of novel approaches to the testing and design of vascular grafts, ultimately enhancing their patency rates in future applications. [ABSTRACT FROM AUTHOR]

This communication study integrates composite multimodal research on postmortem human submandibular glands, based on macromorphometry. The normal ductographic sialograms were pairwise analyzed using linear morphometry, whole-gland planimetry and fractal properties, such as main duct length, caliber and tortuosities, side branches and accessory ducts/lobes. All the examined parameters presented a significant correlation, i.e., symmetry between the left and the right submandibular glands. The morphometric data presented can serve as a valuable reference in clinical practice. [ABSTRACT FROM AUTHOR]

Sea ice surface patterns encode more information than can be represented solely by the ice fraction. The aim of this paper is thus to establish the importance of using a broader set of surface characterization metrics, and to identify a minimal set of such metrics that may be useful for representing sea-ice in Earth System Models. Large-eddy simulations of the atmospheric boundary layer over various idealized sea ice surface patterns, with equivalent ice fraction and average floe area, demonstrate that the spatial organization of ice and water can play a crucial role in determining boundary-layer structure. Thus, different methods to quantify heterogeneity in categorical lattice spatial data, such as those done in landscape ecology and Geographic Information System (GIS) studies, are used here on a set of high-resolution, recently-declassified sea ice surface images. It is found that, in conjunction with ice fraction, the patch density (representing the fragmentation of the surface), the splitting index (representing the variability in patch size), and perimeter-area fractal dimension (representing the tortuosity of the interface) are all required to describe the two-dimensional pattern exhibited by a sea ice surface. Furthermore, for surfaces with anisotropic patterns, the orientation of the surface relative to the mean wind is needed. Furthermore, scaling laws are derived for these relevant landscape metrics to estimate them from aggregated spatial sea ice surface data at any resolution. The methods used and results gained from this study are a first step towards further development of methods to quantify the variability of non-binary surfaces, and for parameterizing mixed ice-water surfaces in coarse geophysical models. [ABSTRACT FROM AUTHOR]

Solid‐state methods for producing porous metals vary greatly in their approaches and outcomes, and they often result in distinctly different pore sizes and/or characteristics. By combining methods in a hybrid process, it is possible that unique porous structures can be made that are simpler to produce, have improved functional properties, or are otherwise superior to any single approach. For the first time, a combination of gas entrapment and oxide reduction to produce microscale porosity in millimeter‐scale copper spheres created by planetary milling is reported. The milling process entraps Ar in micron to submicron pores within the spheres, which are comprised of a Cu 2 mol% CuO metal matrix composite. Upon heating at 800 °C in an inert atmosphere, the individual spheres expand and form ≈29% closed porosity with an average pore size of 1.5 μm. When those spheres are then reheated to 600 °C in a reducing atmosphere, the porosity is converted to being almost entirely open with an average size of 2.3 μm. In addition to the unique nature of the porosity, the processing of the spheres is unusual in that it is completed after only 90 min of milling. [ABSTRACT FROM AUTHOR]

Ceramic membranes are now receiving greater attention and are regarded as the best alternative option for reducing energy use. There are currently a number of limitations on the use of ceramic membranes, including high raw material costs and high sintering temperatures during synthesis. Cost‐effective raw materials were employed in the synthesis of ceramic membranes to get around these restrictions. Utilizing a straightforward pressing technique, circular disc‐type membranes were prepared. To assess the membrane properties, the impact of sintering temperatures between 700 and 900°C was examined. By varying the sintering temperature, the average membrane pore diameter was observed. The membrane, which was sintered at 800°C, had pores that were on average 110 nm in size. Furthermore, the porosity of these synthesized membranes ranged from 22% to 35% with an average pore diameter of 74–121 nm. These manufactured membranes showed very good chemical stability when both acidic and basic solutions were used. Various characterization methods, including thermogravimetric analysis (TGA), x‐ray diffraction analysis (XRD), and scanning electron microscopy (SEM), were used. Thermo‐gravimetric investigation revealed that the synthesized cenosphere membrane required a minimum sintering temperature of about 700°C. The flux measured with deionized water and the applied transmembrane pressure showed an upward trend. The impact of sintering temperature on permeate flux was investigated. The results showed that as the sintering temperature increased from 700°C to 900°C, the flux reduced. It was determined that the synthesized membrane cost ₹1618.80/m2. [ABSTRACT FROM AUTHOR]

Coronary computed tomography angiography (CCTA) allows detailed assessment of early markers associated with coronary artery disease (CAD), such as coronary artery calcium (CAC) and tortuosity (CorT). However, their analysis can be time-demanding and biased. We present a fully automated pipeline that performs (i) coronary artery segmentation and (ii) CAC and CorT objective analysis. Our method exploits supervised learning for the segmentation of the lumen, and then, CAC and CorT are automatically quantified. 281 manually annotated CCTA images were used to train a two-stage U-Net-based architecture. The first stage employed a 2.5D U-Net trained on axial, coronal, and sagittal slices for preliminary segmentation, while the second stage utilized a multichannel 3D U-Net for refinement. Then, a geometric post-processing was implemented: vessel centerlines were extracted, and tortuosity score was quantified as the count of branches with three or more bends with change in direction forming an angle >45°. CAC scoring relied on image attenuation. CAC was detected by setting a patient specific threshold, then a region growing algorithm was applied for refinement. The application of the complete pipeline required <5 min per patient. The model trained for coronary segmentation yielded a Dice score of 0.896 and a mean surface distance of 1.027 mm compared to the reference ground truth. Tracts that presented stenosis were correctly segmented. The vessel tortuosity significantly increased locally, moving from proximal, to distal regions (p < 0.001). Calcium volume score exhibited an opposite trend (p < 0.001), with larger plaques in the proximal regions. Volume score was lower in patients with a higher tortuosity score (p < 0.001). Our results suggest a linked negative correlation between tortuosity and calcific plaque formation. We implemented a fast and objective tool, suitable for population studies, that can help clinician in the quantification of CAC and various coronary morphological parameters, which is helpful for CAD risk assessment. [ABSTRACT FROM AUTHOR]

We use molecular dynamics simulations to characterize the shock-induced collapse of porosity of 1,3,5,7-tetranitro-1,3,5,7-tetrazoctane. We focus on how pore size and shape affect the collapse mechanism and resulting hotspot temperature distribution. Within the hydrodynamic collapse regime, for particle velocities above 0.7 km/s, we find that a combination of the curvature of the downstream surface and void length affects the terminal velocity of the expanding material and, consequently, temperature. Increasing curvature and length result in faster speeds, including jetting, and higher temperatures. For long and thin voids, there is a maximum in temperature with curvature as lateral collapse restricts the expanding material. The simulations map void size and shape to the resulting hotspot and provide a key piece of information toward the development of predictive modeling of shock-induced initiation. [ABSTRACT FROM AUTHOR]

Carbon sequestration is one approach to achieve carbon dioxide reduction in the atmosphere. Underground storage of CO2 requires an understanding of geochemical and geomechanical alteration on the integrity of the injection wellbore. In this study, we investigate the reactivity of supercritical CO2 (scCO2) at 65 °C and 20.7 MPa on Portland class G cement plugs used for oil and gas well completion, for exposure of up to 5 weeks.For nanoporous media, such as cement, diffusion is believed to be the major mass transport mechanism (Perkins and Johnston, 1963) [1]. To quantify the extent of the alteration (mineralization/dissolution) on fluid diffusivity through the cement matrix, a novel approach based on Nuclear Magnetic Resonance (NMR) is employed to derive diffusional tortuosity. Comparing pre- and post-scCO2 exposure, deuterium oxide (D2O) intrusion profiles allow us to determine flow path alteration in the cement plugs. Additional characterizations include Fourier Transform Infrared Spectroscopy (FTIR) to observe the change in cement composition, micro X-ray Computed Tomography (μXCT), along with Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) to determine invasion extent and microstructure modifications, Mercury Injection Capillary Pressure (MICP) for pore throat size distribution and BET N2 isothermal adsorption for surface area and pore size distribution.The results show that exposure to scCO2 promotes both calcium carbonate precipitation and dissolution simultaneously. However, the alteration is pore size dependent. After 5 weeks of exposure, there is evidence of carbonate dissolution in smaller pores (

Background Vascular tortuosity affects the outcomes of mechanical thrombectomy (MT). We classified vertebral artery (VA) tortuosity into 3 types and investigated the effect of VA tortuosity on the outcomes in patients with basilar artery occlusion. Methods We retrospectively included patients who underwent MT for basilar artery occlusion between January 2012 and May 2022. Clinical and procedure‐related factors were obtained. VA tortuosity was classified into 3 types: type I: nontortuous VA; type II: S‐shaped vessel or a VA with a single acute angulation (1 location. The 3‐month modified Rankin scale, procedural outcomes, and post‐MT intracranial hemorrhage were assessed. Results A total of 106 patients with basilar artery occlusion were included. Age, baseline stroke severity, and 3‐month modified Rankin scale score were significantly different according to VA tortuosity (P = 0.003, P = 0.002, and P