Biocompatible Tough Hydrogels via Micellar Copolymerization of NIPAM and Stearyl Acrylate: Synthesis and Characterization

Novel biocompatible tough hydrogels were prepared through free radical micellar polymerization of N-isopropylacrylamide (NIPAM) with ammonium persulphate (APS) as initiator, in which hydrophobic monomer stearyl acrylate (C18) underwent micellar polymerization in the presence of gelatin as emulsifier. FT-IR and DSC demonstrated the formation of co-polymer of NIPAM and C18. Swelling results indicated that hydrophobic polymer domains derived from C18 in aqueous medium acted as the physical crosslinking points by hydrophobic association. Uniaxial tensile test demonstrated the mechanical properties of hydrogels increased with increasing C18 and gelatin contents. The hydrogel exhibited low toxicity and promoted cell proliferation. The desirable toughness, low toxicity and the promoting effect of cell proliferation made the present hydrogels good candidates for tissue regeneration materials.

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Biomechanical-Structural Correlation of Chordae tendineae in Animal Models: A Pilot Study

Animals ◽

10.3390/ani11061678 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1678

Author(s):

Justyn Gach ◽

Izabela Janus ◽

Agnieszka Mackiewicz ◽

Tomasz Klekiel ◽

Agnieszka Noszczyk-Nowak

Keyword(s):

Mitral Valve ◽

Complex Structure ◽

Future Research ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Histopathological Analysis ◽

Papillary Muscles ◽

Chordae Tendineae ◽

Structural Correlation ◽

Ring Valve

The mitral valve apparatus is a complex structure consisting of the mitral ring, valve leaflets, papillary muscles and chordae tendineae (CT). The latter are mainly responsible for the mechanical functions of the valve. Our study included investigations of the biomechanical and structural properties of CT collected from canine and porcine hearts, as there are no studies about these properties of canine CT. We performed a static uniaxial tensile test on CT samples and a histopathological analysis in order to examine their microstructure. The results were analyzed to clarify whether the changes in mechanical persistence of chordae tendineae are combined with the alterations in their structure. This study offers clinical insight for future research, allowing for an understanding of the process of chordae tendineae rupture that happens during degenerative mitral valve disease—the most common heart disease in dogs.

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The Effect of Hispidulin, a Flavonoid from Salvia plebeia, on Human Nasopharyngeal Carcinoma CNE-2Z Cell Proliferation, Migration, Invasion, and Apoptosis

Molecules ◽

10.3390/molecules26061604 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1604

Author(s):

Yiqun Dai ◽

Xiaolong Sun ◽

Bohan Li ◽

Hui Ma ◽

Pingping Wu ◽

...

Keyword(s):

Cell Proliferation ◽

Nasopharyngeal Carcinoma ◽

Migration And Invasion ◽

Dependent Manner ◽

Etoh Extract ◽

Tumor Drug Resistance ◽

Diphenyltetrazolium Bromide ◽

Scratch Wound ◽

Low Toxicity ◽

Induced Apoptosis

Nasopharyngeal carcinoma (NPC) is a common malignant head and neck tumor. Drug resistance and distant metastasis are the predominant cause of treatment failure in NPC patients. Hispidulin is a flavonoid extracted from the bioassay-guided separation of the EtOH extract of Salvia plebeia with strong anti-proliferative activity in nasopharyngeal carcinoma cells (CNE-2Z). In this study, the effects of hispidulin on proliferation, invasion, migration, and apoptosis were investigated in CNE-2Z cells. The [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay and the colony formation assay revealed that hispidulin could inhibit CNE-2Z cell proliferation. Hispidulin (25, 50, 100 μM) also induced apoptosis in a dose-dependent manner in CNE-2Z cells. The expression of Akt was reduced, and the expression of the ratio of Bax/Bcl-2 was increased. In addition, scratch wound and transwell assays proved that hispidulin (6.25, 12.5, 25 μM) could inhibited the migration and invasion in CNE-2Z cells. The expressions of HIF-1α, MMP-9, and MMP-2 were decreased, while the MMPs inhibitor TIMP1 was enhanced by hispidulin. Moreover, hispidulin exhibited potent suppression tumor growth and low toxicity in CNE-2Z cancer-bearing mice at a dosage of 20 mg/kg/day. Thus, hispidulin appears to be a potentially effective agent for NPC treatment.

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Experimental and Numerical Evaluation of Mechanical Properties of 3D-Printed Stainless Steel 316L Lattice Structures

Journal of Materials Engineering and Performance ◽

10.1007/s11665-021-05737-w ◽

2021 ◽

Author(s):

M. Carraturo ◽

G. Alaimo ◽

S. Marconi ◽

E. Negrello ◽

E. Sgambitterra ◽

...

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

Mechanical Behavior ◽

Numerical Simulations ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Lattice Structures ◽

Stainless Steel 316L ◽

Research Attention ◽

Octet Truss

AbstractAdditive manufacturing (AM), and in particular selective laser melting (SLM) technology, allows to produce structural components made of lattice structures. These kinds of structures have received a lot of research attention over recent years due to their capacity to generate easy-to-manufacture and lightweight components with enhanced mechanical properties. Despite a large amount of work available in the literature, the prediction of the mechanical behavior of lattice structures is still an open issue for researchers. Numerical simulations can help to better understand the mechanical behavior of such a kind of structure without undergoing long and expensive experimental campaigns. In this work, we compare numerical and experimental results of a uniaxial tensile test for stainless steel 316L octet-truss lattice specimen. Numerical simulations are based on both the nominal as-designed geometry and the as-build geometry obtained through the analysis of µ-CT images. We find that the use of the as-build geometry is fundamental for an accurate prediction of the mechanical behavior of lattice structures.

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Polar poly(n-butyl acrylate)-g-polyacrylonitrile elastomer with high temperature elasticity and healability as flexible electronic substrate

Fashion and Textiles ◽

10.1186/s40691-020-00235-4 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Yuzhu Zheng ◽

Deli Xu ◽

Shiyou Tian ◽

Manli Li ◽

Wenwen Wang ◽

...

Keyword(s):

High Temperature ◽

Graft Copolymer ◽

Butyl Acrylate ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Self Healing ◽

Chemical Structures ◽

Flexible Electronic ◽

Ag Nanowires ◽

Cyano Groups

AbstractIn this work, graft copolymer poly (n-butyl acrylate)-g-polyacrylonitrile with poly (n-butyl acrylate) as backbones and polyacrylonitrile as side chains (PnBA-g-PAN) was synthesized by macromonomer method and emulsion polymerization. The macromonomer was synthesized by atom transfer radical polymerization and end-group modification. The chemical structures and thermal properties of macromonomer and graft copolymer were investigated by FTIR, GPC, NMR and TGA, etc. The mechanical properties of graft copolymer elastomer was also measured by uniaxial tensile test. Rheological properties at different temperature and mechanical property demonstrated that graft copolymer elastomer possessed elasticity until 180 oC because of cyclization of cyano groups. Ag nanowires@PnBA-g-PAN composite elastomer was developed, and the resulted material exhibited autonomic healing property on account of segments’ flexibility and dynamic interaction between Ag nanowires (AgNWs) and cyano groups. This is a general method for generation of elastomer with high temperature elasticity and fast self-healing. The composite elastomer has potential application in flexible electronic conductor.

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Ability of Constitutive Models to Characterize the Temperature Dependence of Rubber Hyperelasticity and to Predict the Stress-Strain Behavior of Filled Rubber under Different Defor Mation States

Polymers ◽

10.3390/polym13030369 ◽

2021 ◽

Vol 13 (3) ◽

pp. 369

Author(s):

Xintao Fu ◽

Zepeng Wang ◽

Lianxiang Ma

Keyword(s):

Experimental Data ◽

Temperature Dependence ◽

Mechanical Response ◽

Constitutive Models ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Chain Model ◽

Stress Strain ◽

Filled Rubber ◽

Yeoh Model

In this paper, some representative hyperelastic constitutive models of rubber materials were reviewed from the perspectives of molecular chain network statistical mechanics and continuum mechanics. Based on the advantages of existing models, an improved constitutive model was developed, and the stress–strain relationship was derived. Uniaxial tensile tests were performed on two types of filled tire compounds at different temperatures. The physical phenomena related to rubber deformation were analyzed, and the temperature dependence of the mechanical behavior of filled rubber in a larger deformation range (150% strain) was revealed from multiple angles. Based on the experimental data, the ability of several models to describe the stress–strain mechanical response of carbon black filled compound was studied, and the application limitations of some constitutive models were revealed. Combined with the experimental data, the ability of Yeoh model, Ogden model (n = 3), and improved eight-chain model to characterize the temperature dependence was studied, and the laws of temperature dependence of their parameters were revealed. By fitting the uniaxial tensile test data and comparing it with the Yeoh model, the improved eight-chain model was proved to have a better ability to predict the hyperelastic behavior of rubber materials under different deformation states. Finally, the improved eight-chain model was successfully applied to finite element analysis (FEA) and compared with the experimental data. It was found that the improved eight-chain model can accurately describe the stress–strain characteristics of filled rubber.

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Effect of PWHT on the Microstructure and Mechanical Properties of Friction Stir Welded DP780 Steel

Metals ◽

10.3390/met11071097 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1097

Author(s):

Umer Masood Chaudry ◽

Seung-Chang Han ◽

Fathia Alkelae ◽

Tea-Sung Jun

Keyword(s):

Mechanical Properties ◽

Annealing Temperature ◽

Tensile Elongation ◽

Image Correlation ◽

Frictional Heat ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Friction Stir ◽

Microstructure And Mechanical Properties ◽

Dp780 Steel

In the present study, the effect of post-weld heat treatment (PWHT) on the microstructure and mechanical properties of friction stir welded (FSW) DP780 steel sheets was investigated. FSW was carried out at a constant tool rotation speed of 400 rpm and different welding speeds (200 mm/min and 400 min/min). A defect free weld was witnessed for both of the welding conditions. The mutual effect of severe plastic deformation and frictional heat generation by pin rotation during the FSW process resulted in grain refinement due to dynamic recrystallization in the stir zone (SZ) and thermo-mechanically affected zone (TMAZ). Lower tensile elongation and higher yield and ultimate tensile strengths were recorded for welded-samples as compared to the base material (BM) DP780 steel. The joints were subsequently annealed at various temperatures at 450–650 °C for 1 h. At higher annealing temperature, the work hardening rate of joints gradually decreased and subsequently failed in the softened heat-affected zone (HAZ) during the uniaxial tensile test. Reduction in yield strength and tensile strength was found in all PWHT conditions, though improvement in elongation was achieved by annealing at 550 °C. The digital image correlation analysis showed that an inhomogeneous strain distribution occurred in the FSWed samples, and the strain was particularly highly localized in the advancing side of interface zone. The nanoindentation measurements covering the FSWed joint were consistent with an increase of the annealing temperature. The various grains size in the BM, TMAZ, and SZ is the main factor monitoring the hardness distribution in these zones and the observed discrepancies in mechanical properties.

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Coupled Thermomechanical Response Measurement of Deformation of Nickel-Based Superalloys Using Full-Field Digital Image Correlation and Infrared Thermography

Materials ◽

10.3390/ma14092163 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2163

Author(s):

Krzysztof Żaba ◽

Tomasz Trzepieciński ◽

Sandra Puchlerska ◽

Piotr Noga ◽

Maciej Balcerzak

Keyword(s):

Surface Temperature ◽

Strain Rate ◽

Rolling Direction ◽

Image Correlation ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Response Measurement ◽

Sheet Rolling ◽

Inconel Alloys ◽

The Relationship

The paper is devoted to highlighting the potential application of the quantitative imaging technique through results associated with work hardening, strain rate and heat generated during elastic and plastic deformation. The aim of the research presented in this article is to determine the relationship between deformation in the uniaxial tensile test of samples made of 1-mm-thick nickel-based superalloys and their change in temperature during deformation. The relationship between yield stress and the Taylor–Quinney coefficient and their change with the strain rate were determined. The research material was 1-mm-thick sheets of three grades of Inconel alloys: 625 HX and 718. The Aramis (GOM GmbH, a company of the ZEISS Group) measurement system and high-sensitivity infrared thermal imaging camera were used for the tests. The uniaxial tensile tests were carried out at three different strain rates. A clear tendency to increase the sample temperature with an increase in the strain rate was observed. This conclusion applies to all materials and directions of sample cutting investigated with respect to the sheet-rolling direction. An almost linear correlation was found between the percent strain and the value of the maximum surface temperature of the specimens. The method used is helpful in assessing the extent of homogeneity of the strain and the material effort during its deformation based on the measurement of the surface temperature.

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Synbiotic supplementation attenuates the promoting effect of indole-3-carbinol on colon tumorigenesis

Beneficial Microbes ◽

10.3920/bm2020.0209 ◽

2021 ◽

pp. 1-10

Author(s):

N.A. de Moura ◽

B.F.R. Caetano ◽

L.T. Bidinotto ◽

M.A.M. Rodrigues ◽

L.F. Barbisan

Keyword(s):

Cell Proliferation ◽

Colon Carcinogenesis ◽

Basal Diet ◽

Tumour Volume ◽

Control Group ◽

Promoting Effect ◽

Bifidobacterium Lactis ◽

Colon Tumorigenesis ◽

Synbiotic Supplementation ◽

Well Differentiated

Indole-3 carbinol (I3C) has shown dual effects on the promotion and progression stages of colon carcinogenesis while synbiotics (Syn) have exerted anti-carcinogenic activities in most rodent studies. This study aimed to investigate the effects of I3C given alone or together with a Syn intervention on 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis. All animals were given four subcutaneous DMH injections (4×40 mg/kg bodyweight, twice a week for two weeks) and then received either basal diet (G1), basal diet containing I3C (1g/kg chow) (G2) or basal diet containing I3C+Syn (I3C + inulin 50g/kg chow + Bifidobacterium lactis BB-12®), 2.5×1010 cfu/g of basal diet), (G3) for 21 weeks. Dietary I3C (G2) significantly increased tumour volume and cell proliferation when compared to the DMH control group (G1). Syn intervention (G3) significantly reduced tumour volume and cell proliferation when compared to I3C (G2). The colon tumours found were classified into well-differentiated tubular adenomas or adenocarcinomas. Dietary I3C or I3C+Syn did not significantly affect the incidence and the multiplicity of tumours in comparison with the DMH control group. Furthermore, Syn intervention (G3) increased Gstm1 and reduced Mapk9 gene expression in colonic tumours. The findings of the present study show that the dietary I3C shows a weak promoting activity, while the combination with Syn ameliorates I3C effects.

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Tensile Testing

10.31399/asm.tb.tt2.9781627083553 ◽

2004 ◽

Keyword(s):

Tensile Testing ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Bonded Joints ◽

Adhesively Bonded ◽

Adhesively Bonded Joints ◽

Design And Manufacturing ◽

Data Tables ◽

Reference Section

Tensile Testing, Second Edition is a comprehensive guide to the uniaxial tensile test and its use in determining the mechanical properties and behaviors of materials. The first six chapters cover the fundamentals of tensile testing, including the methodology, the equipment used, the effect of tensile loading on metals, the interpretation of data, and the role of tensile testing in design and manufacturing. The next six chapters deal with the testing of different classes of engineering materials, namely metals, plastics, elastomers, ceramics, and composites, and fabricated structures such as weldments and bolted and adhesively bonded joints. The book also includes three chapters on the nuances of tensile testing at extreme temperatures and strain rates and a reference section with data tables. For information on the print version, ISBN 978-0-87170-806-9, follow this link.

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Realistic hardening-to-softening transition effects of metals over the finite strain range up to failure

Multidiscipline Modeling in Materials and Structures ◽

10.1108/mmms-05-2020-0099 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Zi-Han Xu ◽

Lin Zhan ◽

Si-Yu Wang ◽

Hui-Feng Xi ◽

Heng Xiao

Keyword(s):

Finite Strain ◽

Plastic Work ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Trial And Error ◽

Content Type ◽

Transition Effects ◽

Iterative Procedures ◽

First Time ◽

Hardening And Softening

PurposeA new approach is proposed toward accurately matching any given realistic hardening and softening data from uniaxial tensile test up to failure and moreover, toward bypassing usual tedious implicit trial-and-error iterative procedures in identifying numerous unknown parameters.Design/methodology/approachFinite strain response features of metals with realistic hardening-to-softening transition effects up to eventual failure are studied for the first time based on the self-consistent elastoplastic J2-flow model with the logarithmic stress rate. As contrasted with usual approximate and incomplete treatments merely considering certain particular types of hardening effects such as power type hardening, here a novel and explicit approach is proposed to obtain a complete form of the plastic-work-dependent yield strength over the whole hardening and softening range.FindingsA new multi-axial evolution equation for both hardening and softening effects is established in an explicit form. Complete results for the purpose of model validation and prediction are presented for the finite strain responses of monotonic uniaxial stretching up to failure.Originality/valueNew finite strain elastoplastic equations are established with a new history-dependent variable equivalently in place of the usual plastic work. With these equations, a unified and accurate simulation of both gardening and softening effects up to failure is achieved for the first time in an explicit sense without involving usual tedious implicit trial-and-error iterative procedures.

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