It sounds like an action potential: unification of electrical, chemical and mechanical aspects of acoustic pulses in lipids

In an ongoing debate on the physical nature of the action potential (AP), one group adheres to the electrical model of Hodgkin and Huxley, while the other describes the AP as a nonlinear acoustic pulse propagating within an interface near a transition. However, despite remarkable similarities, acoustics remains a non-intuitive mechanism for APs for the following reason. While acoustic pulses are typically associated with the propagation of density, pressure and temperature variation, APs are most commonly measured electrically. Here, we show that this discrepancy is lifted upon considering the electrical and chemical aspects of the interface, in addition to its mechanical properties. Specifically, we demonstrate how electrical and pH aspects of acoustic pulses emerge from an idealized description of the lipid interface, which is based on classical physical principles and contains no fit parameters. The pulses that emerge from the model show similarities to APs not only in qualitative shape and scales (time, velocity and voltage), but also demonstrate saturation of amplitude and annihilation upon collision.

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Physical and Mechanical Properties of Tenun Pahang Fabrics using Alternative Yarns

Scientific Research Journal ◽

10.24191/srj.v13i2.9377 ◽

2016 ◽

Vol 13 (2) ◽

pp. 67

Author(s):

Engku Liyana Zafirah Engku Mohd Suhaimi ◽

Jamil Salleh ◽

Suzaini Abd Ghani ◽

Mohamad Faizul Yahya ◽

Mohd Rozi Ahmad

Keyword(s):

Mechanical Properties ◽

Physical And Mechanical Properties ◽

The Other ◽

Silk Fabrics ◽

Recovery Angle ◽

Made In

An investigation on the properties of Tenun Pahang fabric performances using alternative yarns was conducted. The studies were made in order to evaluate whether the Tenun Pahang fabric could be produced economically and at the same time maintain the fabric quality. Traditional Tenun Pahang fabric uses silk for both warp and weft. For this project, two alternative yarns were used which were bamboo and modal, which were a little lower in cost compared to silk. These yarns were woven with two variations, one with the yarns as weft only while maintaining the silk warp and the other with both warp and weft using the alternative yarns. Four (4) physical testings and three (3) mechanical testings conducted on the fabric samples. The fabric samples were evaluated including weight, thickness, thread density, crease recovery angle, stiffness and drapability. The results show that modal/silk and bamboo silk fabrics are comparable in terms of stiffness and drapability, hence they have the potential to replace 100% silk Tenun Pahang.

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Study of Rheological Properties of Modified Concrete Mixtures at Vibration

Materials Science Forum ◽

10.4028/www.scientific.net/msf.968.96 ◽

2019 ◽

Vol 968 ◽

pp. 96-106

Author(s):

Oleksandr Pshinko ◽

Olena Hromova ◽

Dmytro Rudenko

Keyword(s):

Mechanical Properties ◽

Rheological Properties ◽

Physical Nature ◽

Concrete Mixture ◽

Practical Significance ◽

Vibration Displacement ◽

Concrete Mixtures ◽

Variable Quantity ◽

Vibration Compaction ◽

Mechanism Of Interaction

Study of rheological properties of concrete mixtures based on modified cement systems in order to determine process parameters. Methodology. To study structural-mechanical properties of modified concrete mixtures of different consistency at their horizontal vibrating displacement an oscillatory viscometer was designed. Results. The optimization of the process of vibration displacement of concrete mixtures with the specification of parameters of vibration impacts taking into account structural-mechanical properties of the mixture is performed. It has been established that the viscosity of the modified cement system of the concrete mixture is a variable quantity, which depends on the parameters of the vibration impacts. Scientific novelty. The mechanism of interaction of the modified concrete mixture with the form and the table vibrator during its vibration compaction is determined. On the basis of this, a model of concrete laying process control is proposed, that allows to predict the ability to form a dense concrete structure. Practical significance. Disclosed physical nature of the process of vibrating displacement of modified concrete mixtures using the principles of physical-chemical mechanics of concrete allows reasonably choose the best options for vibration impacts.

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Influence of artificial aging: mechanical and physicochemical properties of dental composites under static and dynamic compression

Clinical Oral Investigations ◽

10.1007/s00784-021-04122-0 ◽

2021 ◽

Author(s):

D. C. Gornig ◽

R. Maletz ◽

P. Ottl ◽

M. Warkentin

Keyword(s):

Mechanical Properties ◽

Water Sorption ◽

Artificial Aging ◽

Filler Content ◽

Dynamic Compression ◽

The Other ◽

Chemical Degradation ◽

Dental Composites ◽

Compression Tests ◽

Acid Ph

Abstract Objective The aim of the study was to evaluate the influence of filler content, degradation media and time on the mechanical properties of different dental composites after in vitro aging. Materials and Methods Specimens (1 mm3) of three commercially available composites (GrandioSO®, Arabesk Top®, Arabesk Flow®) with respect to their filler content were stored in artificial aging media: artificial saliva, ethanol (60%), lactic acid (pH 5) and citric acid (pH 5). Parameters (Vickers microhardness, compressive strength, elastic modulus, water sorption and solubility) were determined in their initial state (control group, n = 3 for microhardness, n = 5 for the other parameters) and after 14, 30, 90 and 180 days (n = 3 for microhardness, n = 5 for the other parameters for each composite group, time point and media). Specimens were also characterized with dynamic-mechanical-thermal analysis (compression tests, F = ± 7 N; f = 0.5 Hz, 1 Hz and 3.3 Hz; t = 0–170 °C). Results Incorporation of fillers with more than 80 w% leads to significantly better mechanical properties under static and dynamic compression tests and a better water sorption behavior, even after chemical degradation. The influence of degradation media and time is of subordinate importance for chemical degradation. Conclusion Although the investigated composites have a similar matrix, they showed different degradation behavior. Since dentine and enamel occur only in small layer thickness, a test specimen geometry with very small dimensions is recommended for direct comparison. Moreover, the use of compression tests to determine the mechanical parameters for the development of structure-compatible and functionally adapted composites makes sense as an additional standard. Clinical relevance Preferential use of highly filled composites for occlusal fillings is recommended.

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The Effect of Different Annealing Strategies on the Microstructure Development and Mechanical Response of Austempered Steels

Metals ◽

10.3390/met11071041 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1041

Author(s):

Eliseo Hernandez-Duran ◽

Luca Corallo ◽

Tanya Ros-Yanez ◽

Felipe Castro-Cerda ◽

Roumen H. Petrov

Keyword(s):

Mechanical Properties ◽

Retained Austenite ◽

Mechanical Response ◽

Steel Grade ◽

The Other ◽

Microstructure Development ◽

Microstructural Refinement ◽

Heterogeneous Distribution ◽

Parent Austenite ◽

Conventional Annealing

This study focuses on the effect of non-conventional annealing strategies on the microstructure and related mechanical properties of austempered steels. Multistep thermo-cycling (TC) and ultrafast heating (UFH) annealing were carried out and compared with the outcome obtained from a conventionally annealed (CA) 0.3C-2Mn-1.5Si steel. After the annealing path, steel samples were fast cooled and isothermally treated at 400 °C employing the same parameters. It was found that TC and UFH strategies produce an equivalent level of microstructural refinement. Nevertheless, the obtained microstructure via TC has not led to an improvement in the mechanical properties in comparison with the CA steel. On the other hand, the steel grade produced via a combination of ultrafast heating annealing and austempering exhibits enhanced ductility without decreasing the strength level with respect to TC and CA, giving the best strength–ductility balance among the studied steels. The outstanding mechanical response exhibited by the UFH steel is related to the formation of heterogeneous distribution of ferrite, bainite and retained austenite in proportions 0.09–0.78–0.14. The microstructural formation after UFH is discussed in terms of chemical heterogeneities in the parent austenite.

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Ultrapurified Alginate Gel Containing Bone Marrow Aspirate Concentrate Enhances Cartilage and Bone Regeneration on Osteochondral Defects in a Rabbit Model

The American Journal of Sports Medicine ◽

10.1177/03635465211014186 ◽

2021 ◽

pp. 036354652110141

Author(s):

Liang Xu ◽

Atsushi Urita ◽

Tomohiro Onodera ◽

Ryosuke Hishimura ◽

Takayuki Nonoyama ◽

...

Keyword(s):

Mechanical Properties ◽

Bone Marrow ◽

Cell Transplantation ◽

Cartilage Repair ◽

Subchondral Bone ◽

Bone Repair ◽

Bone Marrow Aspirate ◽

Defect Group ◽

The Other ◽

Osteochondral Defects

Background: Ultrapurified alginate (UPAL) gel implantation has been demonstrated as effective in cartilage repair for osteochondral defects; however, cell transplantation within UPAL gels would be required to treat larger defects. Hypothesis: The combination of UPAL gel and bone marrow aspirate concentrate (BMAC) would enhance cartilage repair and subchondral bone repair for large osteochondral defects. Study Design: Controlled laboratory study. Methods: A total of 104 osteochondral defects (1 defect per knee) of 52 rabbits were randomly divided into 4 groups (26 defects per group): defects without any treatment (Defect group), defects treated using UPAL gel alone (UPAL group), defects treated using UPAL gel containing allogenic bone marrow mesenchymal stromal cells (UPAL-MSC group), and defects treated using UPAL gel containing BMAC (UPAL-BMAC group). At 4 and 16 weeks postoperatively, macroscopic and histologic evaluations and measurements of repaired subchondral bone volumes of reparative tissues were performed. Collagen orientation and mechanical properties of the reparative tissue were assessed at 16 weeks. Results: The defects in the UPAL-BMAC group were repaired with hyaline-like cartilage with well-organized collagen structures. The histologic scores at 4 weeks were significantly higher in the UPAL-BMAC group (16.9 ± 2.0) than in the Defect group (4.7 ± 1.9; P < .05), the UPAL group (10.0 ± 3.3; P < .05), and the UPAL-MSC group (12.2 ± 2.9; P < .05). At 16 weeks, the score in the UPAL-BMAC group (24.4 ± 1.7) was significantly higher than those in the Defect group (9.0 ± 3.7; P < .05), the UPAL group (14.2 ± 3.9; P < .05), and the UPAL-MSC group (16.3 ± 3.6; P < .05). At 4 and 16 weeks, the macroscopic evaluations were significantly superior in the UPAL-BMAC group compared with the other groups, and the values of repaired subchondral bone volumes in the UPAL-BMAC group were significantly higher than those in the Defect and UPAL groups. The mechanical properties of the reparative tissues were significantly better in the UPAL-BMAC group than in the other groups. Conclusion: The implantation of UPAL gel containing BMAC-enhanced hyaline-like cartilage repair and subchondral bone repair of osteochondral defects in a rabbit knee model. Clinical Relevance: These data support the potential clinical application of 1-step treatment for large osteochondral defects using biomaterial implantation with cell transplantation.

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Effects of water absorption on the mechanical properties of hybrid natural fibre/phenol formaldehyde composites

Scientific Reports ◽

10.1038/s41598-021-92457-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sekar Sanjeevi ◽

Vigneshwaran Shanmugam ◽

Suresh Kumar ◽

Velmurugan Ganesan ◽

Gabriel Sas ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Impact Strength ◽

Water Absorption ◽

Hybrid Composites ◽

Phenol Formaldehyde ◽

Natural Fibre ◽

The Other ◽

Fibre Reinforcement ◽

Dry Conditions

AbstractThis investigation is carried out to understand the effects of water absorption on the mechanical properties of hybrid phenol formaldehyde (PF) composite fabricated with Areca Fine Fibres (AFFs) and Calotropis Gigantea Fibre (CGF). Hybrid CGF/AFF/PF composites were manufactured using the hand layup technique at varying weight percentages of fibre reinforcement (25, 35 and 45%). Hybrid composite having 35 wt.% showed better mechanical properties (tensile strength ca. 59 MPa, flexural strength ca. 73 MPa and impact strength 1.43 kJ/m2) under wet and dry conditions as compared to the other hybrid composites. In general, the inclusion of the fibres enhanced the mechanical properties of neat PF. Increase in the fibre content increased the water absorption, however, after 120 h of immersion, all the composites attained an equilibrium state.

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Enzymes for Leather Processing: Effect on Pickling and Chroming

Materials ◽

10.3390/ma14061480 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1480

Author(s):

Renata Biškauskaitė ◽

Violeta Valeikienė ◽

Virgilijus Valeika

Keyword(s):

Mechanical Properties ◽

Acidic Medium ◽

Proteolytic Enzymes ◽

Relative Elongation ◽

The Other ◽

Shrinkage Temperature ◽

Processing Effect ◽

Leather Processing ◽

Production Processes ◽

Pickling Process

Recently, increasing attention has been paid to the application of enzymes in a wide variety of leather production processes. The aim of the present study was to investigate the action of enzymatic pickling on derma’s collagen and the influence of this action on subsequent processes and properties of chromed and finished leather. The application of active in acidic medium proteolytic enzymes in the pickling process led to an additional impact on derma structure: collagen was more strongly affected and the porosity of the pelt dermis was reduced, but the hide became more thermally stable. The enzymatically pickled pelt bonded more chromium and reached higher shrinkage temperature while chroming; dyes penetrated deeper; such leather bonded more fatliquors. On the other hand, the action of enzymes worsened the physical–mechanical properties of the leather, as the experimental leather was weaker than the conventional one. The first was characterised by weaker grain layer and had significantly higher relative elongation. Therefore, as some properties improve and others worsen during such a process, the application of every enzyme should be carefully investigated and optimized to produce a leather with defined properties.

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Relationship of Microstructure and Mechanical Properties in Er-Containing Aluminum Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1120-1121.1109 ◽

2015 ◽

Vol 1120-1121 ◽

pp. 1109-1114

Author(s):

Xin Lei ◽

Hui Huang ◽

S.P. Wen

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Aluminum Alloy ◽

Treatment Process ◽

Mg Alloys ◽

The Other ◽

Heat Treatment Process ◽

Comprehensive Performance ◽

Relationship Of ◽

Al Mg Alloys

This study investigated the mechanical properties and microstructures of Er-containing Al–Mg alloys. The research found that the H114-T sheet of Er-containing Al–Mg alloys showed a relative good comprehensive performance in mechanical properties. With the special rolling and heat treatment process, this H114-T sheet showed different morphology of microstructures with the other sheets in Er-containing Al–Mg alloys. Grains in H114-T sheet performed irregular shape polygon, a number of subgrains appeared in grains, the amount of dislocations in grains decreased. H114-T sheet possessed a lot of Copper texture, this may be one of important factors influenced the mechanical properties.

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EFFECT OF THERMO-MECHANICAL TREATMENT ON PROPERTIES OF PARICA PLYWOODS (Schizolobium amazonicum Huber ex Ducke)

Revista Árvore ◽

10.1590/1806-90882017000100015 ◽

2017 ◽

Vol 41 (1) ◽

Cited By ~ 3

Author(s):

Mírian de Almeida Costa ◽

Cláudio Henrique Soares Del Menezzi

Keyword(s):

Mechanical Properties ◽

Mechanical Treatment ◽

Physical And Mechanical Properties ◽

The Other ◽

Modulus Of Rupture ◽

Thermal Treatments ◽

Mechanical Compression ◽

Specific Mass ◽

Thermo Mechanical Treatment ◽

Temperature And Pressure

ABSTRACT Thermo-mechanical treatment is a technique for wood modification in which samples are densified by means of heat and mechanical compression, applied perpendicularly to fibers, which under different combinations of time, temperature, and pressure increases wood density and thus improve some of its properties. This study aimed to treat thermo-mechanically parica plywood and observe the effects on its physical and mechanical properties. Specimens were submitted to two treatments, 120 and 150 ºC, remaining under pressure for seven minutes and, subsequently, under zero pressure for 15 minutes. Results showed a significant increase in specific mass from 0.48 g cm-3 to an average of 0.56 g cm-3, and a compression ratio of about 31.7% on average. Physical properties also varied significantly and results showed that treated samples swelled and absorbed more water than those untreated, leading to a greater thickness non-return rate. This indicates the proposed thermal treatments did not release the internal compressive stress generated during panel pressing, not improving its dimensional stability as a result. On the other hand, mechanical properties were positively affected, leading to an increase of 27.5% and 51.8% in modulus of rupture after treatments at 120 and 150 ºC, respectively. Modulus of elasticity and glue-line shear strength did not vary statistically and Janka hardness was 29.7% higher after treatment at 150 ºC.

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Unidentified emission features in the R Coronae Borealis star V854 Centauri

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731549 ◽

2018 ◽

Vol 610 ◽

pp. L6 ◽

Cited By ~ 2

Author(s):

L. C. Oostrum ◽

B. B. Ochsendorf ◽

L. Kaper ◽

A. G. G. M. Tielens

Keyword(s):

Near Infrared ◽

Physical Nature ◽

The Other ◽

Large Telescope ◽

Circumstellar Material ◽

Spatially Resolved ◽

Broad Emission ◽

Very Large Telescope ◽

New Feature ◽

Molecular Nature

During its 2012 decline, the R Coronae Borealis star (RCB) V854 Cen was spectroscopically monitored with X-shooter on the ESO Very Large Telescope. The obscured optical and near-infrared spectrum exhibits many narrow and several broad emission features, as previously observed. The envelope is spatially resolved along the slit and allows for a detailed study of the circumstellar material. In this Letter, we report on the properties of a number of unidentified visual emission features (UFs), including the detection of a new feature at 8692 Å. These UFs have been observed in the Red Rectangle (RR), but their chemical and physical nature is still a mystery. The previously known UFs behave similarly in the RR and in V854 Cen, but are not detected in six other observed RCBs. Some hydrogen might be required for the formation of their carrier(s). The λ8692 UF is present in all RCBs. Its carrier is likely of a carbonaceous molecular nature, presumably different from that of the other UFs.

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