Experimental investigation of the dynamic properties of natural cartilage under reciprocating sliding at two typical rubbing pairs

2019 ◽  
Vol 233 (9) ◽  
pp. 1318-1326 ◽  
Author(s):  
Shanhua Qian ◽  
Liguo Liu ◽  
Zifeng Ni ◽  
Yong Luo
Keyword(s):  
Coefficient Of Friction ◽  
Solid Phase ◽  
Dynamic Properties ◽  
Surface Characteristics ◽  
High Water ◽  
Sampling Frequency ◽  
High Water Content ◽  
Data Systems ◽  
The Coefficient Of Friction ◽  
Contact Displacement

Natural cartilage is a multiporous viscoelastic biological material with extremely high water content and a macroscopically curved surface. Due to the sampling frequency limitations of typical data systems, the dynamic properties of the contact of cartilage against other surfaces, including rubbing surface characteristics and coefficient of friction, is still not completely understood. In this study, cartilage samples were retrieved from 18- to 24-month-old bovine femora. Contact displacement and coefficient of friction of two typical rubbing pairs of for cartilage-on-glass and cartilage-on-cartilage were recorded using a UMT-2 testing rig using a high sampling frequency data system. A five-point sliding average method was adopted to analyze the experimental data. The results showed that contact displacement comprised cartilage deformation and nominal rubbing profile. Cartilage deformation increased nonlinearly with time while nominal rubbing profile was associated with the rubbing configuration and appeared to be a factor in the low surface sample configuration. Higher cartilage deformation resulted in more load being carried by the solid phase and coefficient of friction with the time as a whole, but the surface characteristics played a role in determining the coefficient of friction in the cartilage-on-cartilage configuration but a lesser role for cartilage-on-glass. Therefore, surface characteristics have a clear role in defining the dynamic properties of natural viscoelastic soft biological materials and these research results will help to evaluate in future the frictional properties of artificial cartilage biomaterials.

Targeted Chemotherapy for Breast Cancer Using an Intelligent Doxorubicin-Loaded Hexapeptide Hydrogel

2020 ◽  
Vol 16 (6) ◽  
pp. 842-852
Author(s):  
Shiyao Luo ◽  
Ying Zhu ◽  
Yiping Li ◽  
Li Chen ◽  
Shunzhong Lv ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Solid Phase ◽  
Synthesis Method ◽  
High Water ◽  
High Water Content ◽  
Normal Tissues ◽  
Self Assembling ◽  
Peptide Hydrogel

Self-assembling peptide hydrogels have a high water content, good biocompatibility and have become a competitive research object in the fields of tissue engineering, cancer treatment and drug delivery. In our research, a hexapeptide with high pH sensitivity was designed and synthesized by utilizing a solid-phase synthesis method. Under physiological conditions, the peptide could self-assemble into a hydrogel. When it reached the tumor acidic microenvironment, the peptide was degraded and doxorubicin was released to exert its antitumor effect. A series of physicochemical properties were investigated, including gelling ability, secondary structure, micromorphology, rheological properties and drug release studies. The results illustrated that PIDO peptide hydrogel has good pH responsiveness and injectability. In vitro cytotoxicity experiments and in vivo antitumor experiments showed that PIDO peptide hydrogel has a highly effective therapeutic effect on tumor cells and is less toxic to normal tissues. Our research provides a promising option for targeted drug delivery and sustainable release.

Microstructure and Tribological Properties of TPU/Fluoropolymer Composites

2020 ◽  
Vol 35 (5) ◽  
pp. 415-421
Author(s):  
K. Rohm ◽  
M. Amirkhosravi ◽  
I. Manas-Zloczower
Keyword(s):  
Shear Stress ◽  
Coefficient Of Friction ◽  
Solid Phase ◽  
Thermoplastic Polyurethane ◽  
Stress Transfer ◽  
Interfacial Area ◽  
Melt Mixing ◽  
Molded Part ◽  
The Matrix ◽  
The Coefficient Of Friction

Abstract A network of poly(tetrafluoroethylene) (PTFE) microfibers in a thermoplastic polyurethane (TPU) was prepared by melt mixing the TPU with solid PTFE particles. The effect of rotor speed on the fiber dimensions was investigated. Higher shear stress was found to be the critical parameter for producing thinner PTFE fibers, rather than the shear rate imposed by the mixer. Shear stress transfer from the melt to the PTFE crystal results in solid phase plastic deformation, and the efficiency of the deformation depends on the shear stress in the matrix. All of the PTFE fiber/TPU composites show lower coefficients of friction compared with the neat TPU. The magnitude of the coefficient of friction was found to correlate with the interfacial area between PTFE and TPU generated by the microfiber network. However, for macroscale PTFE agglomerates, the reduction in the coefficient of friction is mostly affected by the uneven distribution of PTFE in the bulk and on the molded part surface.

Features of spring feeding of sterlet of the middle course of the Northern Dvina river

2020 ◽  
pp. 8-17
Author(s):  
A. Bykov ◽  
D. Palatov ◽  
I. Studenov ◽  
D. Chupov
Keyword(s):  
Benthic Communities ◽  
High Water ◽  
Food Composition ◽  
Fish Growth ◽  
High Water Content ◽  
Feeding Intensity ◽  
Biting Midges ◽  
Size Groups ◽  
Main Components ◽  
A Minor

The article provides information about the features of spring feeding of sterlet in the spawning grounds of the middle course of the Northern Dvina river in may 2019. The main and secondary groups of forage objects in the diet of this species of sturgeon are characterized. The article considers the variability of the sterlet food composition with an increase in the size of fish from 30 to 60 cm. In the process of fish growth in the diet of the Severodvinsk sterlet, the main components in terms of occurrence and mass in all size groups are the larvae of Brooks and chironomids. A minor occurrence was the larvae of midges, biting midges, stoneflies, mayflies and small clams. To random and seasonal food are the larvae of water bugs, butterflies, flies, beetles and eggs of other fish. The feeding intensity of the smaller sterlet (30–40 cm) was significantly higher than that of the fish in the size groups 40–50 and 50–60 cm. Fundamental changes in the diet of the Severodvinsk sterlet for the main food objects for more than sixty years of observations have not been established. During periods of high water content of the Northern Dvina due to seasonal changes in the structure of benthic communities, the value of Brooks in the diet of sterlet increases and the proportion of chironomids decreases.

Hydrogels as Antibacterial Biomaterials

2018 ◽  
Vol 24 (8) ◽  
pp. 843-854 ◽  
Author(s):  
Weiguo Xu ◽  
Shujun Dong ◽  
Yuping Han ◽  
Shuqiang Li ◽  
Yang Liu
Keyword(s):  
Mechanical Properties ◽  
Drug Delivery ◽  
Tissue Engineering ◽  
Water Content ◽  
Oxygen Permeability ◽  
Structural Diversity ◽  
High Water ◽  
Clinical Applications ◽  
High Water Content ◽  
Biomedical Field

Hydrogels, as a class of materials for tissue engineering and drug delivery, have high water content and solid-like mechanical properties. Currently, hydrogels with an antibacterial function are a research hotspot in biomedical field. Many advanced antibacterial hydrogels have been developed, each possessing unique qualities, namely high water swellability, high oxygen permeability, improved biocompatibility, ease of loading and releasing drugs and structural diversity. In this article, an overview is provided on the preparation and applications of various antibacterial hydrogels. Furthermore, the prospects in biomedical researches and clinical applications are predicted.

Experimental Investigation of aluminum doping crumb rubber/epoxy composite in reciprocating motion

2015 ◽  
Vol 3 ◽  
pp. 1
Author(s):  
Goutam Chandra Karar ◽  
Nipu Modak
Keyword(s):  
Experimental Investigation ◽  
Coefficient Of Friction ◽  
Epoxy Composite ◽  
Normal Load ◽  
Crumb Rubber ◽  
The Other ◽  
Reciprocating Motion ◽  
Molding Process ◽  
Friction Tester ◽  
The Coefficient Of Friction

The experimental investigation of reciprocating motion between the aluminum doped crumb rubber /epoxy composite and the steel ball has been carried out under Reciprocating Friction Tester, TR-282 to study the wear and coefficient of frictions using different normal loads (0.4Kg, 0.7Kgand1Kg), differentfrequencies (10Hz, 25Hz and 40Hz).The wear is a function of normal load, reciprocating frequency, reciprocating duration and the composition of the material. The percentage of aluminum presents in the composite changesbut the other components remain the same.The four types of composites are fabricated by compression molding process having 0%, 10%, 20% and 30% Al. The effect of different parameters such as normal load, reciprocating frequency and percentage of aluminum has been studied. It is observed that the wear and coefficient of friction is influenced by the parameters. The tendency of wear goes on decreasing with the increase of normal load and it is minimum for a composite having 10%aluminum at a normal load of 0.7Kg and then goes on increasing at higher loads for all types of composite due to the adhesive nature of the composite. The coefficient of friction goes on decreasing with increasing normal loads due to the formation of thin film as an effect of heat generation with normal load.

Microwave-Induced Thermoacoustic Imaging for Embedded Explosives Detection in High-Water Content Medium

2019 ◽  
Vol 67 (7) ◽  
pp. 4803-4810 ◽  
Author(s):  
Xiong Wang ◽  
Tao Qin ◽  
Yexian Qin ◽  
Ahmed H. Abdelrahman ◽  
Russell S. Witte ◽  
...  
Keyword(s):  
Water Content ◽  
High Water ◽  
Explosives Detection ◽  
High Water Content ◽  
Thermoacoustic Imaging

scholarly journals Tribological Aspects, Optimization and Analysis of Cu-B-CrC Composites Fabricated by Powder Metallurgy

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4217
Author(s):  
Üsame Ali Usca ◽  
Mahir Uzun ◽  
Mustafa Kuntoğlu ◽  
Serhat Şap ◽  
Khaled Giasin ◽  
...  
Keyword(s):  
Weight Loss ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Applied Load ◽  
Practical Significance ◽  
Tribological Characteristics ◽  
M 10 ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Four Levels

Tribological properties of engineering components are a key issue due to their effect on the operational performance factors such as wear, surface characteristics, service life and in situ behavior. Thus, for better component quality, process parameters have major importance, especially for metal matrix composites (MMCs), which are a special class of materials used in a wide range of engineering applications including but not limited to structural, automotive and aeronautics. This paper deals with the tribological behavior of Cu-B-CrC composites (Cu-main matrix, B-CrC-reinforcement by 0, 2.5, 5 and 7.5 wt.%). The tribological characteristics investigated in this study are the coefficient of friction, wear rate and weight loss. For this purpose, four levels of sliding distance (1000, 1500, 2000 and 2500 m) and four levels of applied load (10, 15, 20 and 25 N) were used. In addition, two levels of sliding velocity (1 and 1.5 m/s), two levels of sintering time (1 and 2 h) and two sintering temperatures (1000 and 1050 °C) were used. Taguchi’s L16 orthogonal array was used to statistically analyze the aforementioned input parameters and to determine their best levels which give the desired values for the analyzed tribological characteristics. The results were analyzed by statistical analysis, optimization and 3D surface plots. Accordingly, it was determined that the most effective factor for wear rate, weight loss and friction coefficients is the contribution rate. According to signal-to-noise ratios, optimum solutions can be sorted as: the highest levels of parameters except for applied load and reinforcement ratio (2500 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 0 wt.%) for wear rate, certain levels of all parameters (1000 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 2.5 wt.%) for weight loss and 1000 m, 15 N, 1 m/s, 1 h, 1000 °C and 0 wt.% for the coefficient of friction. The comprehensive analysis of findings has practical significance and provides valuable information for a composite material from the production phase to the actual working conditions.

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