Numerical simulation of the distal stent graft-induced new entry after TEVAR

The study aimed to investigate the mechanical factors for distal stent graft-induced new entry (dSINE) in aortic dissection patients and discussed these factors in conjunction with aortic morphology. Two patients (one dSINE and one non-dSINE), with the same age, gender, and type of implanted stent, were selected, then aortic morphological parameters were calculated. In addition, the stent material parameters used by the patients were also fitted. Simulations were performed based on the patient's aortic model and the stent graft used. The true lumen segment at the distal stent graft was designated as the "dSINE risk zone," and mechanical parameters (maximum principal strain, maximum principal stress) were computed. When approaching the area with higher mechanical parameters in the dSINE risk zone, dSINE patient exhibited higher values and growth rates in mechanical parameters compared to non-dSINE patient. Furthermore, dSINE patient also presented larger aortic taper ratio, stent oversizing ratio, and expansion mismatch ratio of the distal true lumen (EMRDTR). The larger mechanical parameters and growth rates in dSINE patient corresponded to a greater aortic taper ratio, stent oversizing ratio, and EMRDTR. The failure of dSINE prediction by the stent tortuosity index indicated that mechanical parameters were the fundamental reasons for dSINE development.

In-contest body acceleration profiles for the judo male and female weight divisions

Introduction

This study aimed to determine the body accelerations (BA) profile of the judo contest of the male and female weight divisions and to ascertain the involvement of the vertical, mediolateral and anteroposterior axes in it.

Methods

Forty-eight male and forty-eight female national and international level athletes (some of them medalists in World, European and national championships) participated in a 5-min simulated contest (official fight time plus breaks) against an opponent of the same sex and weight division, wearing an accelerometer. Heart rate, blood lactate and ratings of perceived exertion were recorded to certify that the athletes performed the fullest.

Results

The t2way test expressed differences in the athletes' BA (p = 0.001) and three profiles were identified: the light/middle weight male divisions, the light/middle weight female divisions and the heavy male and female ones. Athletes of all weight divisions performed their BA during the contest in all three directions (the one-sample Person's chi-square did not detect any significantly predominant one: p = 0.400, p = 0.631, p = 0.844, p = 0.749, p = 0.644 and p = 0.895, for male light, moderate and heavy, female light, moderate and heavyweight athletes, respectively). Monte Carlo method simulations suggested as the most likely scenarios those with BA involving all axes, with a slight preference of the anteroposterior and mediolateral ones.

Discussion

These results suggest that the demands on judo athletes in a contest differ between weight classes and sexes.

Band Engineering and Phonon Engineering Effectively Improve n-Type Mg3Sb2 Thermoelectric Material Properties

Mg3Sb2-based thermoelectric materials can convert heat and electricity into each other, making them a promising class of environmentally friendly materials. Further improving the electrical performance while effectively reducing the thermal conductivity is a crucial issue. In this paper, under the guidance of the oneness principle calculation, we designed a thermoelectric Zintl phase based on Mg3.2Sb1.5Bi0.5 doped with Tb and Er. Calculation results show that using Tb and Er as cationic site dopants effectively improves the electrical properties and reduces the lattice thermal conductivity. Experimental results confirmed the effectiveness of codoping and effectively enhanced thermoelectric performance. The most immense ZT value obtained by the Mg3.185Tb0.01Er0.005Sb1.5Bi0.5 sample was 1.71. In addition, the average Young's modulus of the Mg3.185Tb0.01Er0.005Sb1.5Bi0.5 sample is 51.85 GPa, and the Vickers hardness is 0.99 GPa. Under the same test environment, the material was subjected to 12 cycles in the temperature range of 323-723 K, and the average power factor error range was 1.8% to 2.1%, which is of practical significance for its application in actual device scenarios.

The Influence of Acid Casein on the Selected Properties of Lime-Metakaolin Mortars

One of the ways to modify selected parameters of lime mortars is the use of biopolymers of animal origin, such as bone glue, skin glue, bovine blood, eggs, and casein. These are protein-based biopolymers. Casein is an example of an organic polymer produced from cow's milk. The aim of the work was to investigate the possibilities of improving selected properties of mortars based on hydrated lime and metakaolin. The mixture was modified with powdered technical casein in amounts of 0.5%, 1.5%, 1%, 1.5%, and 2% as a partial mass replacement for the binding mixture. Additionally, the influence of increasing the amount of water on the properties of the mortar with a casein admixture of 2% was checked. This study examined consistency, shrinkage, water absorption, capillary action, porosity, flexural, compressive strength, and Young's modulus. The admixture of casein influenced the properties of the mortar, but not in all cases, and it was possible to determine a clear trend related to the variable amount of casein. Strength properties deteriorated as the amount of casein increased. When air bubbles were introduced into the mortar after the casein was dissolved, the porosity increased as the amount of admixture increased. The moisture properties improved; namely, casein led to a reduction in water absorption and water absorption caused by capillary action. No relationship was observed between the amount of casein and the drying shrinkage. Increasing the amount of water in the mixture led to the expected effects, i.e., an increase in porosity, shrinkage, and water absorption, and a decrease in mechanical strength.

Possibilities of Influencing the Crystallization Process of Bisphenol A- and Bisphenol F-Based Epoxy Resins Used for Hydrophobic Coatings on Concrete

Crystallization of bisphenol A (DGEBA)- and bisphenol F (DGEBF)-based epoxy resins is a natural property of these oligomers. However, manufacturers of coatings and other systems based on these epoxy resins are making efforts to slow down the crystallization process as much as possible, thereby extending the shelf life and improving the competitiveness of their products. This paper focuses on the kinetics of the crystallization process of epoxy resins and the effect of the presence of a certain degree of crystallinity on selected parameters of epoxy-based materials. Furthermore, an analysis of the impact of a certain degree of crystallinity of the epoxy base on the resulting coating parameters was carried out. The highest value of crystallinity (17%) was achieved in the sample containing the highest proportion of DGEBF in the crystallization phase "c", and the enthalpy of melting (Ht) of the crystalline DGEBF sample was 6.3 J/g. Mechanical parameters as well as chemical and thermal resistance of hydrophobic epoxy systems were investigated. The best abrasion resistance (1.5 cm3/50 cm2) was achieved with the blend containing only amorphous DGEBA. The adhesion of the epoxy samples on concrete was greater than 6.5 MPa. The chemical resistance tests performed showed that, in general, the chemical resistance of epoxy systems decreases with increasing crystallinity content. The tighter arrangement of molecules in the crystalline regions of the epoxy matrix results in an increase in density, strength and hardness. This study presents a comprehensive examination of the crystallization of DGEBA and DGEBF, which is, as yet virtually unavailable. It also contributes to knowledge by outlining the possibility of speeding up or slowing down the crystallization process of epoxy resins, including the principle of selecting nucleating agents.

Analysis of the Effect of Component Ratio Imbalances on Selected Mechanical Properties of Seasoned, Medium Viscosity Bone Cements

The paper presents the results of experimental strength tests of specimens made of two commercially available bone cements subjected to compression, that is a typical variant of load of this material during use in the human body, after it has been used for implantation of prostheses or supplementation of bone defects. One of the factors analysed in detail was the duration of cement seasoning in Ringer's solution that simulates the aggressive environment of the human body and material degradation caused by it. The study also focused on the parameters of quantitative deviation from the recommended proportions of liquid (MMA monomer, accelerator and stabiliser) and powder (PMMA prepolymer and initiator) components, i.e., unintentional inaccuracy of component proportioning at the stage of cement mass preparation. Statistical analysis has shown the influence of these factors on the decrease in compressive strength of the cements studied, which may be of significant importance in operational practice.

Evaluation of the Effect of Selected Physiological Fluid Contaminants on the Mechanical Properties of Selected Medium-Viscosity PMMA Bone Cements

Revision surgeries several years after the implantation of the prosthesis are unfavorable from the patient’s point of view as they expose him to additional discomfort, to risk of complications and are expensive. One of the factors responsible for the aseptic loosening of the prosthesis is the gradual degradation of the cement material as a result of working under considerable loads, in an aggressive environment of the human body. Contaminants present in the surgical field may significantly affect the durability of the bone cement and, consequently, of the entire bone-cement-prosthesis system. The paper presents the results of an analysis of selected mechanical properties of two medium-viscosity bone cements DePuy CMW3 Gentamicin and Heraeus Palamed, for the samples contaminated with saline and blood in the range of 1–10%. The results obtained for compressive strength and modulus of elasticity were subjected to statistical analysis, which estimated the nature of changes in these parameters depending on the amount and type of contamination and their statistical significance.

Long-Term Behavior of Cement Mortars Based on Municipal Solid Waste Slag and Natural Zeolite-A Comprehensive Physico-Mechanical, Structural and Chemical Assessment

Limitations in natural aggregate resources and the continuous increase in the demand for concrete as a building material, as well as the increase in the production of waste and the problem with its storage were the reasons for attempts to replace the sand fraction in cement matrices with a corresponding slag fraction. Municipal solid waste incineration (MSWI) slag, which is a product of waste incineration, can be used as an aggregate. This extends its service life and reduces landfill waste. Therefore, three types of cement mortars with different aggregate composition were prepared. In addition, to increase the durability of the cement matrix and the degree of immobilization of harmful heavy metals and salts present in the slag, a natural zeolite with pozzolanic properties was used. A set of tests was carried out on fresh mortar and hardened mortar, including strength tests after 7, 28 and 360 days. What is more, chemical tests were undertaken, including the content of chlorides and sulfates, leaching using the TCLP method and oxide composition. The conducted tests revealed that all mortars had similar strength properties and demonstrated the effectiveness of immobilizing harmful substances contained in the municipal solid waste incineration (MSWI) slag by cementing.

The Influence of Gum Arabic Admixture on the Mechanical Properties of Lime-Metakaolin Paste Used as Binder in Hemp Concrete

Organic admixtures based on polysaccharides are used in construction for modifying the properties of mortars and concretes. Gum arabic is an example of a polysaccharide-based biopolymer. The aim of the article was to investigate the possibilities of improving the strength parameters of a binder paste based on hydrated lime and metakaolin. The paste was modified with powdered gum arabic at 1%, 3% and 5% (by mass) as a partial replacement for the binder mix. The influence of the admixture on the pore size distribution as well as flexural and compressive strength was investigated. The admixture enhanced the total porosity of the paste, increasing the pore diameter compared with the reference formulation. The increase in porosity, in turn, did not reduce the mechanical strength. Conversely, the admixture in the amount of 3% and 5% caused a significant increase in the flexural (by about 300% in relation to reference paste) and compressive strengths (by 25% and 60%, respectively). The tested pastes were used as a binder in a composite based on hemp shives. The influence of binder modification on the water absorption and compressive strength of hemp concrete was tested. The strength of the composite soaked in water was also tested. The modification of the binder with gum arabic in the amount of 3% and 5% increased the compressive strength of hemp concrete (not soaked in water) by 53% and 92%, respectively and reduced the mass absorptivity by 6.6% and 10.4%, respectively.

Inhibition of enzymes associated with metabolic and neurological disorder by dried pomegranate sheets as a function of pomegranate cultivar and fruit puree

BACKGROUND

Obesity and type 2 diabetes mellitus are the most extended current chronic diseases and also Alzheimer pathology which is a progressive degenerative neurological disorder. Therefore, finding effective enzyme inhibitors responsible for the development of these diseases are essential. Therefore, the aim of this study was to investigate the impact of fruit purée (Cydonia oblonga, Ziziphus jujube and Malus domestica) and pomegranate juice cultivar ('Mollar de Elche' and 'Wonderful') of dried pomegranate sheets (DS) on the inhibition of enzymes associated with metabolic (α-amylase, α-glucosidase, and pancreatic lipase activity), and neurological disorder (acetylcholinesterase and butyrylcholinesterase activity). Quality properties (colour coordinates, texture properties and sensory characteristics) of DS were also studied. In addition, it was researched the effect of storage conditions (4 months at 4 and 20 °C) on phenolic content.

RESULTS

DS from jujube had the highest antioxidant capacity and were characterized by the highest storage stability with respect to phenolic compounds. The α-amylase and α-glucosidase half maximal inhibitory concentration (IC₅₀ , in mg mL^-1 ) inhibition of DS ranged from 107 to 216 and from 55.2 to values indicating no effect, respectively. The inhibition toward pancreatic lipase (IC₅₀  < 5 mg mL^-1 ), acetylcholinesterase (ranged 9.15-22.2%) and butyrylcholinesterase (ranged 20.6-48.6%) was increased with the presence of total flavonoids and hydroxycinnamic acids content (identifying mainly in DS from quinces). It is noteworthy that none of the samples presented off-flavour notes, supporting the high quality of the products.

CONCLUSION

DS can be an innovative supplement to a diet as a snack used in the prevention of neurological changes and disorders of carbohydrate and lipid metabolism. © 2020 Society of Chemical Industry.

Effect of Physiological Saline Solution Contamination on Selected Mechanical Properties of Seasoned Acrylic Bone Cements of Medium and High Viscosity

Bone cements play a key role in present-day surgery, including the implantation of hip and knee joint endoprostheses. The correct and durable bonding of the prosthesis to the bone is affected by both the static strength characteristics determined in accordance with ISO 5833:2002 and the resistance to long-term exposure to an aggressive environment of the human body and the impurities that may be introduced into the cement during implementation. The study attempts to demonstrate statistically significant degradation of cement as a result of the seasoning of cement samples in Ringer’s solution with simultaneous contamination of the material with saline solution, which is usually present in the surgical field (e.g., during the fixing of endoprostheses). The results of statistical analysis showed the nature of changes in compressive strength and microhardness due to seasoning time and degree of contamination.

Identification of Fracture Mechanic Properties of Concrete and Analysis of Shear Capacity of Reinforced Concrete Beams without Transverse Reinforcement

The study of new and innovative quasi-brittle materials offers new possibilities for use in construction, but detailed knowledge of their behavior and mechanical properties is required. The use of new materials in the design solution of a structure is usually associated with numerical methods, which has a number of both advantages and disadvantages. Sophisticated numerical methods, without a sufficiently detailed input knowledge, can provide highly variable results with little informative value. The main goal of this article is to present the procedure for the identification of fracture mechanical parameters for a specific concrete with the use of developed inverse analysis combining multi-criteria decision analysis, stochastic modelling and nonlinear analysis. Subsequently, the identified mechanical parameters of concrete are used for the parametric study of shear resistance of structural beams without shear reinforcement, as an alternative or generalized approach to the study of damage to concrete and concrete structures. This research includes an experimental program using 24 reinforced concrete beams and a detailed determination of basic and specific mechanical properties during laboratory tests. The process of inverse analysis is illustrated in detail for the solved task. The use of nonlinear analysis for detailed failure modelling is based on a 3D computational model and a fracture plastic material model for concrete. Finally, the results of the experimental program and numerical modelling are discussed, leading to a number of conclusions.

Properties of Fibrous Concrete Made with Plastic Optical Fibers from E-Waste

This article presents research results relating to the potential for waste utilization in the form of polymer optical fiber (POF) scraps. This material is difficult to recycle due to its diverse construction. Three different volumes of POF were used in concrete in these tests: 1%, 2%, and 3%. The experimental studies investigated the basic properties of the concrete, the elastic and dynamic moduli, as well as deformation and deflection of reinforced beams. The microstructures, including the interfacial transition zones (ITZs), were recorded and analyzed using a scanning electron microscope. It was observed that 180 freezing–thawing cycles reduced the concrete frost resistance containing 3% POFs by half compared to the control concrete. The resistance to salt crystallization of this concrete decreased by about 55%. POFs have significant effects on the splitting tensile and flexural strengths compared to the compressive strength. The control beams were destroyed during the four-point static bending tests at half the force applied to the beams that were reinforced with POFs.

Mechanical Changes and Microfilament Reorganization Involved in Microcystin-LR-Promoted Cell Invasion in DU145 and WPMY Cells

Microcystin-leucine arginine (MC-LR) is a potent tumor initiator that can induce malignant cell transformation. Cellular mechanical characteristics are pivotal parameters that are closely related to cell invasion. The aim of this study is to determine the effect of MC-LR on mechanical parameters, microfilament, and cell invasion in DU145 and WPMY cells. Firstly, 10 μM MC-LR was selected as the appropriate concentration via cell viability assay. Subsequently, after MC-LR treatment, the cellular deformability and viscoelastic parameters were tested using the micropipette aspiration technique. The results showed that MC-LR increased the cellular deformability, reduced the cellular viscoelastic parameter values, and caused the cells to become softer. Furthermore, microfilament and microfilament-associated proteins were examined by immunofluorescence and Western blot, respectively. Our results showed that MC-LR induced microfilament reorganization and increased the expression of p-VASP and p-ezrin. Finally, the impact of MC-LR on cell invasion was evaluated. The results revealed that MC-LR promoted cell invasion. Taken together, our results suggested that mechanical changes and microfilament reorganization were involved in MC-LR-promoted cell invasion in DU145 and WPMY cells. Our data provide novel information to explain the toxicological mechanism of MC-LR.

Investigation of physico-mechanical properties of flexible poly (vinyl chloride) filled with antimony trioxide using ionizing radiation

Composites of polyvinyl chloride (PVC) with 2% calcium carbonate, 2% diethyl phthalate, 2% paraffin wax and 2% lead sulphate and different contents of antimony trioxide (Sb₂O₃) prepared by melting and irradiated with gamma ray have been considered. Assessment of the mechanical and thermal properties of the unirradiated and irradiated flexible polyvinyl chloride (FPVC) were completed utilizing elasticity (TS), Elongation at break (Eb) and thermogravimetric analysis measurements. TS and thermal stability of FPVC displayed advanced improvement after addition of additives and this approach highlighted the efficiency of those ingredients on PVC. The compounding of FPVC with Sb₂O₃ in various extents was examined by FTIR, X-ray diffraction and scanning electron microscope methods. It is obvious that the presence of Sb₂O₃ begins impacting oxidative degradation, leading to a decrease in mechanical properties up to 10%. Moreover, a slight increase in the thermal stability of composites by exposure to ionizing radiation is apparently due to cross-linking of FPVC chains.

Experimental Analysis of MOC Composite with a Waste-Expanded Polypropylene-Based Aggregate

Polypropylene (PP) is one of the most widely produced types of plastic worldwide, but its recycling is limited. This work presents a study of the utilization of expanded polypropylene (EPP) waste in a magnesium oxychloride cement (MOC) composite usable in the building industry. MOC is formed by mixing magnesium oxide powder and a concentrated solution of magnesium chloride and is characterized by excellent bonding ability to large quantities of different types of aggregates. A developed air-cured MOC composite, where an EPP-based aggregate was used for the full replacement of natural aggregate, was investigated in terms of its basic physical, mechanical, thermal and water resistance properties. The results demonstrate that incorporation of EPP waste greatly improved the thermal insulation properties, while the mechanical resistance was reduced to an acceptable level. The developed MOC composite containing EPP waste can be considered as an alternative thermal insulation material applicable for the construction of floor or envelope construction systems.

Analysis of the selected mechanical parameters of coating of filters protecting against hazardous infrared radiation

This article presents a comparison of the test results of selected mechanical parameters (hardness, Young's modulus, critical force for delamination) for protective filters intended for eye protection against harmful infrared radiation. Filters with reflective metallic films were studied, as well as interference filters developed at the Central Institute for Labour Protection - National Research Institute (CIOP-PIB). The test results of the selected mechanical parameters were compared with the test results, conducted in accordance with a standardised method, of simulating filter surface destruction that occurs during use.

The effect of lateral epicondylosis on upper limb mechanical parameters

BACKGROUND

Lateral epicondylosis is a prevalent and costly musculoskeletal disorder characterized by degeneration of the common extensor tendon origin at the lateral epicondyle. Grip strength is commonly affected due to lateral epicondylosis. However, less is known about the effect of lateral epicondylosis on other functional parameters such as ability to react to rapid loading.

METHODS

Twenty-nine lateral epicondylosis participants and ten controls participated in a case-control study comparing mechanical parameters (mass, stiffness and damping), magnetic resonance imaging signal intensity and grip strength of injured and uninjured limbs. A mixed effects model was used to assess the effect of dominance and injury on mechanical parameters and grip strength.

FINDINGS

Significant effect of injury and dominance was observed on stiffness, damping and grip strength. An injured upper limb had, on average, 18% less stiffness (P<0.01, 95% CI [9.8%, 26%]), 21% less damping (P<0.01, 95% CI [11%, 31%]) and 50% less grip strength (P<0.01, 95% CI [37%, 61%]) than an uninjured upper limb. The dominant limb had on average 15% more stiffness (P<0.01, 95% CI [8.0%, 23%], 33% more damping (P<0.01, 95% CI [22%, 45%]), and 24% more grip strength (P<0.01, 95% CI [6.6%, 44%]) than the non-dominant limb.

INTERPRETATION

Lower mechanical parameters are indicative of a lower capacity to oppose rapidly rising forces and quantify an important aspect of upper limb function. For individuals engaged in manual or repetitive activities involving the upper limb, a reduction in ability to oppose these forces may result in increased risk for injury or recurrence.

Mechanical and magnetic resonance imaging changes following eccentric or concentric exertions

BACKGROUND

Prior work has shown that changes in mechanical parameters and magnetic resonance imaging parameters occur following submaximal eccentric activity but it is unclear whether similar changes occur following submaximal concentric activity. This study compared mechanical response parameters and MRI relaxation parameters following submaximal concentric or eccentric exertions.

METHODS

This single site, randomized study investigated in vivo changes in human upper limb dynamic mechanical properties following exposure to short term repetitive submaximal eccentric or concentric exertions. Eighteen subjects were assigned to either an eccentric or concentric group and exercised for 30 min at 50% of isometric forearm maximum voluntary contraction. Changes in strength, symptom intensity, magnetic resonance imaging T2 relaxation measurements, which are indicative of edema, and dynamic mechanical parameters (stiffness, effective mass, and damping) were ascertained prior to exercise, 1h after, and 24h later.

FINDINGS

Strength decreased following exercise (P<0.01), however only the eccentric exercise group exhibited a reduction in mechanical stiffness (55%, P<0.01) and damping (31%, P<0.05), and an increase (17%, P<0.05) in magnetic resonance imaging T2 relaxation time.

INTERPRETATION

The changes in mechanical parameters and magnetic resonance imaging findings following repetitive submaximal eccentric activity could negatively impact the ability of the arm to react to rapid forceful loading during repetitive industrial work activities and may result in increased strain on the upper limb. Similar changes were not observed following concentric exercise.