Degree Of Elasticity Research Articles

The role of elastography in determining the risk of malignant thyroid nodules in children.

Ultrasonography is fundamental method of diagnosing focal thyroid lesions. The additional element of ultrasound examination is Strain Elastography which allows for determining the degree of elasticity of the nodule while comparing it to the surrounding thyroid parenchyma. Pediatric thyroid nodules have a higher malignancy risk than in adults, warranting the consideration of fine-needle aspiration biopsy (FNAB) in children. A prospective data analysis of children with focal thyroid lesions treated from 2021 to 2022 was performed. The patients underwent ultrasound and elastography examinations to obtain the Strain Ratio (SR) of the nodules and were qualified for FNAB. SR was determined by the windowing method of relative strains in a semi-quantitative assessment. The FNAB score was determined on the Bethesda scale and the histological examination of the thyroid nodule was performed. The SR values were stratified in three groups: I - thyroid cancer, II - low-risk thyroid tumors, and III - benign lesion. The Kruskal-Wallis test was used to find the relation between the value of SR elastography and the malignancy, with the p value < 0.05 considered significant. The data were analyzed using the multiple comparisons test. The 123 FNABs were performed in 100 patients. The final analysis included 119 nodules in 96 patients. In 19 cases, the nodule was malignant, in 5 cases they were low-risk tumors, and in 95 - benign lesions. A difference of the SR value between groups in the pairs of malignant and benign tumors, and malignant and low-risk tumors was revealed. Since no statistically significant difference in the level of elastography was found between benign and low-risk tumors, both groups were combined and formed a group of benign tumors. For the combined groups, the Man-Whitney test was performed, confirming that there was a statistically significant difference between the groups of malignant and benign tumors in the value of SR elastography. The cut-off point for SR for malignant tumors was >3. The SR index of elastography is significantly higher in malignant nodules. and might be used to select changes with an increased risk of malignancy in thyroid ultrasound of children.

Longitudinal dynamic behavior study of a vibrating rod connected through an elastic nonlinear single degree freedom coupler

This research explores the efficacy of integrating nonlinear single-degree-of-freedom systems in the vibration control of rod coupling systems. By interlinking two rods with a nonlinear single-degree-of-freedom system as the intermediary, the study employs the Lagrange method (LM) to forecast nonlinear vibrational behaviors. The findings, substantiated by numerical analyses, affirm the precision of LM in gauging the amplitude responses when such a nonlinear system is utilized. The nonlinear dynamics, characterized by intricate vibrational patterns, peak jumping phenomena, and the migration of resonance zones, are induced by the nonlinear single-degree-of-freedom system. By fine-tuning the system’s parameters, significant alterations in the vibrational states of the rod coupling system are achievable. This suggests that the application of a nonlinear single-degree-of-freedom system is a viable strategy for modulating vibrations in rod systems. Furthermore, optimal parameterization of this system is proven to effectively dampen vibrations, showcasing its potential as a sophisticated mechanism for vibration suppression in coupled rod configurations.

Analyzing tourist expenditures incurred on long-, medium-, and short-haul trips to Taiwan

This study examined the consumption demands of short-, medium-, and long-haul tourists in Taiwan, considering the effects of tourism attractiveness, generational cohorts, and nationalities on tourism consumption demand. We employed an Almost Ideal Demand System model to estimate the expenditures and price elasticities based on tourism expenditure data of 3018 visitors to Taiwan. The results indicated that varying degrees of price elasticity were observed among short-, medium-, and long-haul tourists. Long-haul tourists exhibited the highest elasticity in terms of shopping prices and expenditure. The factors influencing tourists' attraction to Taiwan were identified as the geographical convenience of their travel and their nationalities, which, in turn, affected their consumption demands. Thus, based on tourists' relevant characteristics to implement targeted marketing strategies.

ANCF-based modelling of rigid-flexible coupling of helicopter flexible rotor blades

Abstract A high-precision rotor structure dynamic model applicable to a variety of helicopter blade hub structures is established considering rotor blade flexible deformation. The absolute nodal coordinate method is applied to the traditional rotor blade rigid-flexible coupling dynamics model, making the new model applicable to both fully articulated rotor blades and other advanced blade hub structures. No small-volume assumptions were made in the modelling process. Both Green’s strain expression under finite deformation and the geometrical relation of elastic deformation motion based on the absolute nodal coordinate method are used to derive the blade strain energy, kinetic energy, and the external load virtual work. The rotation angle at the articulation constraint at the root of the blade coupled with the elastic deformation degrees of freedom of the blade in three independent rigid body degrees of freedom, respectively. The rotor blade rigid-flexible coupling dynamics equations were established according to the Hamilton action principle. The time-domain simulation is carried out under a free single pendulum and fixed rotational speed/fixed torque for the established flexible blade model, which verifies the validity and high accuracy of the rigid-flexible coupling articulation model of the flexible rotor blade and the blade hub.

Valuing Wealth with Liquidity Restrictions

ABSTRACT Liquidity restrictions are recognized as a potential tool to help individuals avoid overconsumption, but their overall welfare implications are ambiguous. This paper quantifies the implied value of illiquid assets and identifies the conditions under which the implied value of illiquid assets exceeds its nominal value even in the absence of an illiquidity premium. We find that the implied value increases with degrees of present bias and elasticity of inter-temporal substitution. We also show that only the consumption pattern of individuals with liquidity restrictions exhibits hump-shaped dynamics, which is consistent with the well-known life cycle hypothesis and the reality.

Tariffs, Growth and Non-Tariff Transport Costs

This paper examines the impact of unilateral tariff increases on the world growth rate using a two-country endogenous growth model when firms are internationally mobile, technical knowledge in research and development is an international public good, and iceberg transport costs are not subject to tariffs. In this paper, we find that a unilateral tariff increase in one country raises or lowers the world growth rate, depending on the degree of elasticity of substitution between any two differentiated goods and the share of firms owned by the country that raised tariffs.

Natural coil springs: Biomechanics and morphology of the coiled tendrils of the climbing passion flower Passiflora discophora

Tendrils of climbing plants possess a striking spring-like structure characterized by a minimum of two helices of opposite handedness connected by a perversion. By performing tensile experiments and morphological measurements on tendrils of the climbing passion flower Passiflora discophora, we show that these tendril springs act as coil springs within the plant's attachment system and resemble technical coil springs. However, tendril springs have a low spring index and a high pitch angle compared with typical metal coil springs resulting in a more complex loading situation in the plant tendrils. Moreover, the tendrils undergo a drastic shift from the fresh turgescent stage to a dried-off and dead senescent stage. This entails changes in material properties (elastic modulus in tension), morphology (tendril and helix diameter, number of windings), anatomy (tissue composition), and failure behavior (susceptibility to delamination) and reduces the degree of elasticity and strain at failure of the tendrils. Nevertheless, senescent tendrils remain functional as springs and maintain high energy dissipation capacity and high break force. This renders the system highly energy efficient, as the plant no longer needs to metabolically sustain the died-back tendrils. Because of its energy-storing spring system, its high energy dissipation and high safety factor, the attachment system can be considered a ‘fail-safe’ system. Statement of significanceThe use of coil springs as mechanical devices is not restricted to man-made machinery; striking spring structures can also be found within the attachment systems of climbing plants. Passiflora discophora climbs by using long thin tendrils with adhesive pads at their tips. Once the pads have attached to a support, the tendrils coil and form a spring-like structure. Here, we analyze the form and mechanics of these ‘tendril springs’, compare them with conventional technical coil springs, and discuss changes in the tendril springs during plant development. We reveal the main features of the attachment system, which might inspire new artificial attachment devices within the emerging field of plant-inspired soft-robotics.

Optimal fiscal policy in small open economies with habit persistence

Abstract This paper sets up a small open economy model with habit persistence in consumption in which distortionary taxation is available in a flexible price environment. In open economy, the habit persistence in consumption aggravates the terms of trade externality, absent in closed economy, calling for more aggressive fiscal policy. While optimal labor income taxes are time-invariant in a closed economy with internal habit, they should be time-varying in an open economy to alleviate the terms of trade externality, even if the intertemporal elasticity of substitution equals the intratemporal elasticity of substitution. In a small open economy composed of households with habit persistence in consumption, households’ decision to gradually adjust their consumption and labor hours intensifies the undesirable terms of trade externality or the terms of trade channel. This generates a time-varying wedge between the efficiency conditions of the Ramsey planner and the market equilibrium conditions, calling for a time-varying taxation which takes into account the intertemporal elasticity of substitution and the intratemporal elasticity of substitution between home and foreign goods, in addition to the degree of habit and goods market distortion. The volatility of optimal tax rate increases with the degree of habit, whether households have external or internal habit. The volatility of tax rate shows an inverted U-shape in the degree of openness in the small open economy with habit. Finally, the optimal labor income tax rate moves countercyclically for low degree of intratemporal elasticity of substitution, while it moves procyclically for high degree of intratemporal elasticity of substitution.

Contribution of geometrical infill pattern on mechanical behaviour of 3D manufactured polylactic acid specimen: Experimental and numerical analysis

Additive manufacturing is regarded as a very efficient fabrication technique since it permits the manufacturing of any three-dimensional product. The present work determines the effect of various infill pattern on the mechanical properties in term of tensile strength, yield strength and hardness of poly-lactic acid (PLA) samples fabricated by fused deposition modeling method. The mechanical behaviour of the 3D-printed PLAs investigated using dog-bone specimens with six distinct infill patterns: line, triangle, tri-hexagon, cubic, octet, and gyroid. The mechanical characteristics were evaluated using the uniaxial tensile test and shore D type hardness tester. The strain and deformation criteria were employed to substantiate the ductile and brittle characteristics. The fractural surface morphology analyzed using the field emission scanning electron microscope. Nonlinear Finite Element Analysis (FEA) was employed to simulate the uniaxial tensile test and establish a Yeoh third order hyperelastic material model for the predictions of the stress-strain response. This model is chosen for its precise ability to predict the nonlinear stress-strain responses for significant deformation and is crucial in applications that involve high degrees of flexibility and elasticity, such as in tire modeling, polymer and elastomer analysis, sports equipment designing, 3D printed components etc. Results revealed that the cubic infill had a maximum tensile strength 32.648 ± 1.42 MPa and octet infill had a minimum tensile strength 22.373 ± 0.79 MPa. The majority of experimental data indicated a brittle behaviour for line-infilled, but triangular, trihexagonal, cubic, octet, and gyroid infill patterns demonstrated ductile behaviour. In comparison to other geometrical infills, cubic shown relatively superior mechanical responses. Consequently, the geometrical infill effect plays a significant role in finding the appropriate mechanical property for industrial applications. The developed material model possesses potential utility in non-linear FEA investigations pertaining to 3D printed PLA objects that are predicted to sustain tensile strength.

Crop Management System Consisting of Biodegradable Mulching Film + Drip Irrigation Increases Yield and Quality of Flue-Cured Tobacco

Mulching is one of the most recommended practices in agriculture due to its positive effects on the plant/soil system. Very few experiments have been conducted to date to investigate the effect of mulching, with both organic and inorganic materials, on tobacco. The main aim of this study was to test the synergic effect of a soil-biodegradable (according to standard EN17033) mulching film (the commercial Mater-Bi®, Novamont SpA, Novara, Italy) and drip irrigation (M-D) compared with that of bare soil and sprinkler/drip irrigation (first/second part of the growing season; BS-SD) on a tobacco crop (Nicotiana tabacum L., flue-cured Virginia) grown in the Tiber Valley (the tobacco cultivation district of Central Italy). BS-SD represents the standard practice applied by tobacco growers in the study area. The plants grown under the M-D management system grew more and developed faster than the plants grown under BS-SD conditions. Under the M-D system, yields increased in comparison with the BS-SD conditions (+29%, on average). The gross revenue obtained via the M-D-cured products also increased (+63%, on average) thanks to higher prices assigned by expert evaluators on the basis of the extrinsic quality traits (color, structure and texture, degree of ripeness, elasticity, lamina integrity, handling defects, and vein incidence). The economic value of the cured products increased with the leaf crowns; it was the lowest in the basal (B) leaves and the highest in the middle-upper (MU) leaves. The intrinsic quality traits of the cured leaves (total N and nitrate contents, alkaloids, and reducing sugars) also confirmed that the best quality was found in the M-D-cured products, as determined by expert evaluation. Interestingly, the reducing sugar (RS) contents of tobacco obtained using the M-D management system were 2.5-, 1.1-, and 0.9-fold greater than those under the BS-SD conditions (B, M, and MU products, respectively). An additional commercial value of the cured products was thus obtained with the M-D crop management system due to RS, an intrinsic quality trait considered by manufacturing industries.

Effect of pressure on the phase stability, elastic anisotropy, and physical properties of CuZr structures

AbstractThe effect of hydrostatic pressure on the relative stabilities of the four main structures in CuZr has been estimated using first‐principles calculations. The results indicate that hydrostatic pressure induces the B19′ → B19 transformation at ~40 GPa and Cm → B19 transformation at ~68 GPa. At 0 GPa, these CuZr structures exhibit analogous values of B, G, and E and small difference in σ. However, the differences between these structures become appreciable in B, G, E, and σ values. 3D graphs of Young's modulus reflect the elasticity is directional. Pressure promotes the increase of elastic anisotropy degree of B2. For B19′ and Cm, the variation trends under pressure firstly decrease, then slightly increase, while that is opposite for B19. The quasi‐harmonic Debye model is used to evaluate the effects of temperature and pressure on the thermodynamic properties (heat capacity, thermal expansion coefficient, Debye temperature, and Grüneisen parameter) of the CuZr structures.

Demographic regulation processes in Pinna nobilis population subunits: Implications for restocking

A mass mortality event (MME) affected the endemic bivalve Pinna nobilis across the Mediterranean Sea in autumn 2016. This event affected specimens of all sizes, depth ranges and habitat types, resulting in a drastic decline in the species population close to 100%. Indeed, the consequences of a potential recovery, and therefore the viability of the populations of the species are unknown. To evaluate the likelihood of success when designing the reintroduction of the species in optimal areas, knowledge of population dynamics is essential. Here we compare two population subunits of Pinna nobilis from two areas with different environmental conditions, located in Cabrera National Park (protected area with low exposure to hydrodynamic activity) and San Telmo (unprotected area exposed to hydrodynamic activity), both in the Balearic Islands. A total of 259 individuals were tagged and monitored annually between 2011 and 2014, prior to the MME. Matrix population models were used to reduce the complexity of the age-structured population dynamics and assessing the degree of elasticity of the population. We showed that the subunit of San Telmo showed highly variable values of demographic rates, higher stochasticity and higher sensitivity to environmental variability than the population subunit of Cabrera National Park. The study shows the importance of the buffering effect of a large population as there are many adult individuals of many size classes in the population subunit of Cabrera National Park, as its age structure helps to cope with highly variable reproductive success. Therefore, these population subunits are more stable regardless of depth and would be a more suitable site for future reintroduction programs.

Вторинні порушення форми грудної клітки після корекції лійкоподібної деформації за методом Nuss

Aim - studying the influence of the elasticity of the chest on the formation of secondary pectus carinatum and secondary protrusion of costal arches after Nuss procedure in order to determine the risk groups for the occurrence of data of secondary postoperative deformations in order to optimize a surgical intervention in these groups . Materials and methods. We analysed the data of 6 patients with pectus carinatum and 5 children with rib arches protrusion, which were formed as a result of Nuss funnel chest correction. The elasticity of the chest was studied by determining the ratio of its circumference during maximum inhalation and exhalation (mobility index - MI) as well as the ratio of the distance between the support plane in the supine position and the front surface of the chest in a neutral position and at the moment of compression (compliance index - CI). To calibrate the indicators, the data were calculated in a group of 30 healthy children. Depending on the obtained values, 3 degrees of chest elasticity are distinguished: high, medium and rigid chest. Results. 3 degrees of chest elasticity were determined in children without chest deformity: high (MI - 9.1±0.9%; CI - 28.1±1.8%), medium (MI - 6.8±0.2%; CI - 22.7±2.1%) and a low or rigid chest (MI - 4.9±0.2%; CI - 15.6±1.8%). The following data were recorded in patients with secondary deformities: 80% of patients with secondary pectus carinatum had a high degree of elasticity of the chest, 20% - average degree. In 83.33% of cases, patients with secondary rib arches protrusion had a high degree of elasticity of the chest, and 16.67% had an average degree. Secondary rib arches protrusion in 80% of cases is combined with the use of one horizontal bar. All cases of occurrence of secondary deformations are associated with a symmetric local type of funnel chest with or without deformations of costal arches or with an asymmetric local type. Conclusions. Using the Nuss operation technique with short plates in patients in the period of rapid growth with a high degree of elasticity of the chest with type IA and IIA1 of funnel chest can reduce the risk of secondary pectus carinatum; and in cases of high level risk of secondary protrusion of the rib arches the "flare buster" technique can help avoid this complication. The vast majority of secondary deformations are prone to spontaneous regression. The research was adhered to the principles of the Declaration of Helsinki. The research protocol was agreed by the Local Ethics Committee of the mentioned institution. The patients' informed consent was obtained for the study. No conflict of interests was declared by the authors.

Carbon nanotube reinforced FeMoO4 nanorods as a high-performance anode for sodium-ion batteries

Iron molybdate (FeMoO4) nanostructures show great promise as a superior anode for sodium-ion batteries. However, its use in practical application is hampered by its poor electronic conductivity, large volume changes and sluggish reaction kinetics. Herein, we have developed an interconnected network of multiwall carbon nanotube (CNT) and FeMoO4 (FMO) by a simple one-step hydrothermal method. As well as providing efficient channels for charge transfer and diffusion, highly conductive CNTs also have a degree of volume elasticity and excellent electrical conductivity to ensure migration of sodium ions, enabling both fast kinetics and long-term stability. As a result, the FMO@CNT anode delivers a high reversible capacity of 485 mA h g−1 at 0.05 A/g and very long cycling stability with a capacity of 75 mA h g−1 after 1000 cycles at 1 A/g. Furthermore, by combining the ex-situ X-ray diffraction, ex situ X-ray photoelectron spectroscopy and cyclic voltammetry results, sodium ion storage mechanism of the FMO@CNT electrode obeys a conversion mechanism. The results of this work provide a better understanding on the sodium ion storage mechanism of binary metal oxides.

Structural and non‐structural numerical blind prediction of shaking table experimental tests on fixed‐base and base‐isolated hospitals

AbstractBase‐isolated hospitals are frequently preferred to fixed‐base ones because of their improved seismic structural performance. Despite this, the question remains open on the advisability of using this modern seismic protection technology in preference to other conventional solutions, on the grounds of a holistic approach based on limiting non‐structural damage as well as continuity of service to the community in the aftermath of an earthquake. Two full‐scale four‐storey (fixed‐base) and three‐storey (base‐isolated) hospital buildings have been recently built and subjected to three‐dimensional shaking table tests at the National Research Institute for Earth Science and Disaster Prevention (Japan), with particular attention to evaluating and classifying functionality of non‐structural components and vital medical equipment. A two‐phase experimental campaign was carried out considering two earthquakes scaled at different intensity levels and applied along the horizontal and vertical directions. The current study aims to provide results of a numerical structural and non‐structural blind prediction of these hospital settings. A homemade numerical code is developed to account for lumped plasticity modelling of steel frame members and variability of the friction coefficient of spherical sliding bearings. Moreover, three non‐structural components are modelled in the fixed‐base structure: that is, elastic single degree of freedom systems representing two tanks filled with sand at the top floor; elastic beam elements for piping at the third floor; five‐element macro‐model for the in‐plane‐out‐of‐plane nonlinear response of partition walls at the first floor. The identification of predominant vibration periods of the fixed‐base structure is carried out using a homemade numerical code based on the continuous wavelet transforms in combination with the complex Morlet wavelet. Finally, the sliding and rocking motion of three items of medical equipment (i.e., incubator at third floor, dialysis machine at second floor and surgical bed at first floor) are analysed by means of a homemade numerical code, considering acceleration time histories of selected structural nodes of the fixed‐base structure.

Comparing flows of FENE-P, sPTT, and Giesekus model fluids in a helical static mixer

Helical static mixers are used widely for mixing of non-Newtonian fluid flows in the laminar regime. We study flows of three viscoelastic constitutive models (sPTT, FENE-P, and Giesekus) in the helical static mixer using computational fluid dynamics. These three models have similarities in steady viscometric flows in that they all exhibit shear thinning and their planar extensional viscosities can be matched, but their responses can differ in complex geometries. We observe flow distribution asymmetries at the element intersections for all three models, which hinders the mixing performance of the device. These have previously been observed with the constant shear viscosity FENE-CR model. The asymmetry behaves similarly between the sPTT and Giesekus models, however the FENE-P model behaves in a distinct manner; beyond a critical degree of elasticity, the asymmetry sharply changes direction. This was also observed previously with the FENE-CR model. These results suggest that shear thinning and second-normal stress differences (present in the Giesekus model) do not significantly influence mixing performance in the range of conditions studied. We show that increasing the aspect (length/diameter) ratio of the mixer elements mitigates the poor mixing caused by elasticity. Overall, this study provides insight into the behaviour of these well-used constitutive models in complex, industrially-relevant flows.

The association between inflammation, arterial stiffness, oxidized LDL and cardiovascular disease in Finnish men with metabolic syndrome – a 15-year follow-up study

BackgroundAll-cause mortality and cardiovascular disease are increased in subjects with metabolic syndrome (MetS). Risk scores are used to predict individual risk of heart disease. We performed a long-term follow-up study to investigate whether risk scores and cardiovascular risk factors such as arterial stiffness, high-sensitive C-reactive protein (hs-CRP) and oxidized LDL (OxLDL) can be used to predict cardiovascular events in Finnish men with MetS.MethodsAfter baseline measurements we followed 105 Finnish men aged 30 to 65 years with MetS for a mean period of 16.4 years. The primary outcome of the study was a composite of myocardial infarction, stroke, symptomatic vascular disease diagnosed with invasive angiography, coronary or peripheral revascularization, amputation due to peripheral vascular disease, cardiovascular death and non-cardiovascular death. The endpoints were retrieved from electronic medical records.ResultsThe number of acute myocardial infarctions and strokes during the first 10 years was lower than estimated by FINRISK score but SCORE predicted cardiovascular death correctly. During the whole follow-up period, 27 of 105 participants (25.8%) had 30 endpoint events. The incidence of the primary composite outcome was significantly lower in subjects with hs-CRP < 1.0 mg/L than in subjects with hs-CRP ≥ 1.0 mg/L (6 of 41 subjects [14.6%] vs. 21 of 64 subjects [32.8%]; p = 0.036). The incidence of the primary composite outcome was higher among subjects with large artery elasticity classified as borderline compared to subjects with normal large artery elasticity (5 of 10 subjects [50%] vs. 22 of 93 subjects [24%]; p = 0.05). There was no difference in the incidence of primary composite outcome in groups with different degrees of small artery elasticity or different level of oxLDL.ConclusionsMen with MetS who had hs-CRP ≥ 1.0 mg/L had higher risk for CVD and all-cause mortality than those with hs-CRP of < 1.0 mg/L. This also applies to subjects with borderline decreased large artery elasticity. The amount of OxLDL had no predictive value on the incidence of CVD and all-cause mortality. Men with MetS participating in the Hämeenlinna Metabolic Syndrome Research Program without lifestyle or drug intervention had better outcome for myocardial infarction or stroke than estimated by the FINRISK score.Trial registrationClinicalTrials.gov NCT01119404 retrospectively registered 07/05/2010.

Application of Adipose Stem Cells in 3D Nerve Guidance Conduit Prevents Muscle Atrophy and Improves Distal Muscle Compliance in a Peripheral Nerve Regeneration Model.

Peripheral nerve injuries (PNIs) represent a significant clinical problem, and standard approaches to nerve repair have limitations. Recent breakthroughs in 3D printing and stem cell technologies offer a promising solution for nerve regeneration. The main purpose of this study was to examine the biomechanical characteristics in muscle tissue distal to a nerve defect in a murine model of peripheral nerve regeneration from physiological stress to failure. In this experimental study, we enrolled 18 Wistar rats in which we created a 10 mm sciatic nerve defect. Furthermore, we divided them into three groups as follows: in Group 1, we used 3D nerve guidance conduits (NGCs) and adipose stem cells (ASCs) in seven rats; in Group 2, we used only 3D NGCs for seven rats; and in Group 3, we created only the defect in four rats. We monitored the degree of atrophy at 4, 8, and 12 weeks by measuring the diameter of the tibialis anterior (TA) muscle. At the end of 12 weeks, we took the TA muscle and analyzed it uniaxially at 10% stretch until failure. In the group of animals with 3D NGCs and ASCs, we recorded the lowest degree of atrophy at 4 weeks, 8 weeks, and 12 weeks after nerve reconstruction. At 10% stretch, the control group had the highest Cauchy stress values compared to the 3D NGC group (0.164 MPa vs. 0.141 MPa, p = 0.007) and the 3D NGC + ASC group (0.164 MPa vs. 0.123 MPa, p = 0.007). In addition, we found that the control group (1.763 MPa) had the highest TA muscle stiffness, followed by the 3D NGC group (1.412 MPa), with the best muscle elasticity showing in the group in which we used 3D NGC + ASC (1.147 MPa). At failure, TA muscle samples from the 3D NGC + ASC group demonstrated better compliance and a higher degree of elasticity compared to the other two groups (p = 0.002 and p = 0.008). Our study demonstrates that the combination of 3D NGC and ASC increases the process of nerve regeneration and significantly improves the compliance and mechanical characteristics of muscle tissue distal to the injury site in a PNI murine model.

Rheological effects on purely-elastic flow asymmetries in the cross-slot geometry.

Viscoelastic flows in the cross-slot geometry can undergo a transition from a steady symmetric to a steady asymmetric flow state, ostensibly due to purely-elastic effects arising beyond a critical flow rate, or Weissenberg number Wi. However, some reports suggest that shear thinning of the fluid's viscosity may also play an important role in this transition. We employ a series of polymer solutions of varying rheological properties to investigate in detail how the interplay between fluid elasticity and shear thinning affects the onset and development of asymmetric flows in the cross-slot. Flow velocimetry is performed on each of the polymer solutions, and is used to assess the degree of flow asymmetry I in the cross-slot as a function of both Wi and a dimensionless parameter S quantifying the flow-rate-dependent extent of shear thinning. Typically, the flow field breaks symmetry as Wi is increased beyond a critical value, but the magnitude of I is found to also be dependent on S. For a few specific polymer solutions, the flow field recovers symmetry above a second, higher critical Wi as S becomes small. The experimental results are summarized in a flow state diagram in Wi-S space, showing the relationship between flow asymmetry and fluid rheology. Finally, to gain a deeper understanding of the effects of shear thinning, numerical simulations are performed using the linear simplified Phan-Thien-Tanner model. We demonstrate that the degree of both shear thinning and elasticity of the fluid, and their interplay, are important factors controlling elastic instabilities in the cross-slot geometry.

Correlation Between Carotid Stenosis and Pulsatile Index Measured by Transcranial Doppler.

Carotid atherosclerosis is often mentioned as one of the main causes of stroke. Currently, embolization is considered the most common mechanism that causes ischemic strokes due to atherosclerotic lesions in the carotid artery. Transcranial Doppler (TCD) ultrasound provides relatively inexpensive, noninvasive, real-time measurement of blood flow characteristics and cerebrovascular hemodynamics within brain arteries. The pulsatile index measured by transcranial Doppler is a parameter that indicates the degree of elasticity of the blood vessels of the brain. The aim of this study is to determine the relationship between the value of the pulsatile index of the middle cerebral artery and the basilar artery in patients with carotid stenosis using transcranial Doppler and the value of the pulsatile index in relation to the degree of carotid stenosis. The study involved a total of 140 patients examined at the Color Doppler and Transcranial Doppler Department of the Neurology Department of the General Hospital "Prim Dr. Abdulah Nakas" Sarajevo The patients were divided into two groups. The research was conducted in the General Hospital "Prim. dr. Abdulah Nakas" in Sarajevo at the Department for Color Doppler and Transcranial Doppler of the Department of Neurology and included patients examined in the period from February 2022 to December 2022. All patients underwent extracranial Doppler of the carotid arteries and transcranial Doppler of the middle cerebral artery and basilar artery. The mean values of PI in ACM in the total sample were statistically significantly lower in patients with stenosis up to 50% compared to the average in patients with stenosis over 50%. Average values of PI in AB in the total sample were statistically significantly lower in patients with stenosis up to 50% compared to the mean values in patients with stenosis over 50%. Transcranial Doppler findings showed an increased pulsatile index in patients who had carotid stenosis greater than 50% compared to patients with mild carotid stenosis. The study showed that in clinical work it would be necessary to introduce the pulsatile index as an indispensable neurosonological parameter that would be included in the findings of the transcranial Doppler and thus objectify the potential risk of a cerebrovascular ischemic event.