Narrow Results

Metallic biomaterials are used to replace and rebuild human structural components due to their biocompatibility, corrosion resistance, and good mechanical properties. Biomedical metals have been used for 30 years. Medical implants use metallic biomaterials. Metallic biomaterials are needed to cure failed hard tissue, bone, and fractures. Because they’re strong, tough, and long-lasting. As the world population ages and seniors are more prone to experience hard tissue disintegration, there is a huge demand for improved metallic biomaterials. Titanium-based alloys, cobalt-based alloys, and stainless steel are feasible metallic biomaterials (316L). These biomaterials’ Young’s modulus should match that of human bones, reducing stress shielding. Implant designs include plates, rods, screws, and pins. Since the FDA approved these biocompatible metallic implants, orthopedic practices often employ them. Metals aren’t believable as biomaterials because they’re synthetic and have insufficient bio-functionality. The biocompatibility of metallic biomaterials must be considerably enhanced. Metallic biomaterials are often synthetic materials with no biological activity. The key issue is coating-to-substrate adhesion. Cover spalling from the substrate causes implant and tissue responses. Due to inadequate crystallization, the hydroxyapatite (HA) coating degrades, increasing implant failure risk by lowering titanium adhesion. Coated 316L stainless steel specimens have better adherence than untreated ones. The coating/substrate material, coating process, and coating thickness are thoroughly identified and discussed. The surface structure and microstructure of HA-based coating are explored to support the conclusions.

Cold spraying is a promising technique for depositing wear-resistant coatings on components like hydroturbine steels. This paper highlights the feasibility of hard WC-17Co coating on 13Cr4Ni hydroturbine steel. The coating was deposited at 25, 30, and 40 bar at 800^∘C and 50 bar at 900^∘C. Further, different characterization techniques (SEM, XRD) were used to analyze the developed coatings. The Vicker hardness testing was employed to determine the hardness of the coated sample. It was observed that WC-17Co coatings deposited at 40 bar and 800^∘C offered a maximum hardness of up to 275 Hv, which is an excellent quality for anti-wear applications in hydro turbine blades.

Adhesive interaction in the presence of plastic deformation may be crucial in additive manufacturing, pharmaceuticals and powder metallurgy. Only limited studies on adhesive contact accounting for plastic deformation had been conducted mainly on the basis of the linear elastic fracture mechanics model where the singular distribution of traction is involved, which is believed to be applicable to softer materials. In this work, an analytical model for elastic–perfectly plastic contact during unloading has been proposed for different adhesion effects, where the effect of yield on normal traction in the cohesive zone has been taken into account. The adhesive contact behaviors during unloading are then illustrated by the proposed model and compared with the predictions of the existing models.

The main objective of this study is to examine the effect of Qi-training on the immune system, especially neutrophil bactericidal function. Nine healthy male subjects were studied for the effects of one bout of ChunDoSunBup (CDSB) Qi-training on superoxide (O₂^-) production and adhesion capacity of neutrophils at times immediately after (Post I) and 2 hours after the Qi-training (Post II). The Qi-training enhanced the (O₂^-) production, reaction velocity and neutrophil adhesion capacity and there were significant differences at Post I compared to before Qi-training (Pre). In addition, the number of white blood cells (WBC), monocytes and lymphocytes were changed significantly through Qi-training. Therefore, it seems that CDSB Qi-training may increase the resistance of trained individuals against common infection and inflammation.

Alteration of the cell surface glycoproteins of cancerous cells correlate with malignancy potential. To evaluate the mediation of membrane glycoproteins in wehi-164 cancerous cells, under the effect of D. mucronata crude extract and one of its purified active components, gnidilatimonoein, their attachment to fibronectin-coated wells were investigated. The plant extract, 27 μl/ml (equivalent to 0.54 mg/of plant leaves powder per ml of culture medium), as well as gnidilatimonoein (0.94 μM), were capable of quenching by 58% and 64%, respectively, the attachment of wehi-164 cells to fibronectin-coated wells (4 μg/ml). In addition to alteration of cell adhesive properties, the morphology of the treated cells were significantly changed upon treatment with the non-toxic dose of the plant extract or gnidilatimonoein. While the untreated cells have polygonal shapes, the treated cells had spherical shapes.

The goal of this study was to investigate the effect of the Panax notoginseng ethanol extract (PNEE) on the regulation of human colorectal cancer (CRC) metastasis. The migratory, invasive, and adhesive abilities and the expression of metastasis-associated regulatory molecules in cultured human CRC cells (HCT-116) treated with the PNEE were analyzed in this study. The migratory and invasive abilities of HCT-116 cells were reduced after PNEE treatment. The incubation of HCT-116 cells with the PNEE for 24 h decreased MMP-9 expression and increased E-cadherin expression compared with the control group. The adhesion reaction assay indicated that treatment with the PNEE led to significantly decreased HCT-116 adhesion to endothelial cells (EA.hy926 cells). The integrin-1 protein levels in HCT-116 cells were significantly decreased following treatment with the PNEE. Similarly, the protein levels of E-selectin and intercellular adhesion molecule-1 (ICAM-1) were significantly decreased by treatment of the EA.hy926 endothelial cells with PNEE. A scanning electron microscope (SEM) examination indicated that HCT-116 cells treated with LPS combined with the PNEE had a less flattened and retracted shape compared with LPS-treated cells, and this change in shape was found to be a phenomenon of extravasation invasion. The transepithelial electrical resistance (TEER) of the EA.hy926 endothelial cell monolayer increased after incubation with the PNEE for 24 h. A cell-cell permeability assay indicated that HCT-116 cells treated with the PNEE displayed significantly reduced levels of phosphorylated VE-cadherin (p-VE-cadherin). These results demonstrate the antimetastatic properties of the PNEE and show that the PNEE affects cells by inhibiting cell migration, invasion, and adhesion and regulating the expression of metastasis-associated signaling molecules.

Deguelin, a rotenoid, is isolated from a natural plant species, and has biological activities including antitumor function. In the present study, we investigated the effect of deguelin on the cell adhesion, migration and invasion of NCI-H292 human lung cancer cells in vitro. Cell viability was analyzed by using flow cytometer. Cell adhesion was determined by using the cell-matrix adhesion assay. Wound healing assay was used to examine cell migration. Cell migration and invasion were investigated using a Boyden chamber assay. The protein expression was measured by Western blotting and confocal laser microscopy. The electrophoretic mobility shift assay was used to measure NF-$\kappa$B p65 binding to DNA.We selected the concentrations of deguelin at 0, 0.5, 1.0, 1.5, 2.0 and 2.5$\mu$M and we found that those concentrations of deguelin did not induce significant cytotoxic effects on NCI-H292 cells. Thus, we selected those concentrations of deguelin for metastasis assay. We found that deguelin inhibited cell adhesion, migration and invasion in dose-dependent manners that was assayed by wound healing and transwell methods, respectively. Deguelin decreased the expression of MMP-2/-9, SOS 1, Rho A, p-AKT (Thr308), p-ERK1/2, p-p38, p-JNK, NF-$\kappa$B (p65) and uPA in NCI-H292 cells. Deguelin suppressed the expression of PI3K, SOS 1, NF-$\kappa$B (p65), but did not significantly affect PKC and Ras in the nuclei of NCI-H292 cells that were confirmed by confocal laser microscopy. We suggest that deguelin may be used as a novel anticancer metastasis of lung cancer in the future.

In contrast to their exceptional mechanical properties, titanium and its alloys possess poor friction and wear characteristics. Nanocrystalline diamond (NCD) films appear to be a promising solution for their tribological problem due to their smooth surfaces and small grain size. However, the synthesis of a well adherent NCD film on titanium and its alloys is always complicated due to the different thermal expansion coefficients of the two materials, the complex nature of the interlayer formed during diamond deposition, and the difficulty in achieving very high nucleation density. In this work NCD thin films have been deposited on pure Ti substrates in a microwave plasma chemical vapor deposition (MWPCVD) reactor under fixed pressure and methane concentration in hydrogen but over a wide temperature range. The effects of depositing temperatures on the adhesion of films are evaluated using Rockwell indentation tests. It is found that by increasing the deposition temperature the films bonding deteriorates. The films synthesized are characterized by field emission scanning electron microscopy, atomic force microscopy, Raman spectroscopy, and X-ray diffraction.

The new Raster Spring Imaging Mode is developed to study soft and bad – fixed objects in AFM. The normal and lateral force between tip and sample is minimized. We discuss the principle of operation, main features and its prospect for specific applications. Experimental results revealed advantages with regard to other techniques like contact or semicontact mode. The silicon structure measurements with Raster Spring Imaging Mode allow to obtain information of elastic and adhesion properties without losing sight of good topography image.

Lead-free piezoelectric (Bi_1/2Na_1/2)TiO₃ (abbreviated as BNT) films were deposited on 0.2 mm thick pure titanium(Ti) substrates by a hydrothermal method. Scratch tests and Vickers indentation tests were performed to quantitatively assess the adhesion strength between BNT films and Ti substrates. Some of Ti substrates were pretreated by chemical polish and mechanical polish respectively prior to BNT film deposition with a view of investigating the effects of substrate surface pretreatments on the adhesion of BNT films. In the scratch test, the critical force was determined from the variations of the tangential force and the acoustic emission (AE) signals with the normal force. The scratch test results revealed that the chemical polish pretreatment effectively improved the adhesion of BNT films. In addition, the critical substrate strain inducing the adhesion failure of BNT films has been investigated by the Vickers indentation test combined with finite element analysis (FEM).

We consider the membranes interacting via short, intermediate and long stickers. The effects of the intermediate stickers on the lateral phase separation of the membranes are studied via mean-field approximation. The critical potential depth of the stickers increases in the presence of the intermediate sticker. The lateral phase separation of the membrane is thus suppressed by the intermediate stickers. Considering the membranes interacting with short and long stickers, the effect of confinement on the phase behavior of the membranes is also investigated analytically.

We use the $\pi$-orbital axis vector (POAV) analysis to deal with large curvature effect of graphene in the tight-binding model. To test the validities of pseudo-magnetic fields (PMFs) derived from the tight-binding model and the model with Dirac equation coupled to a curved surface, we propose two types of spatially constant-field topographies for strongly-curved graphene nanobubbles, which correspond to these two models, respectively. It is shown from the latter model that the PMF induced by any spherical graphene nanobubble is always equivalent to the magnetic field caused by one magnetic monopole charge distributed on a complete spherical surface with the same radius. Such a PMF might be attributed to the isometry breaking of a graphene layer attached conformably to a spherical substrate with adhesion.

The life time and quality of thermal spray coatings are strongly influenced by the technological parameters of the coating process and characteristics of the coated surface. In this paper, 16Mn steel substrates of different surface roughness are coated by Cr₃C₂-NiCr using a plasma spray technique. The adhesion of the coating to the substrate has been studied in relation to the roughness of the substrate and the plasma current of the spraying process. The results showed that the adhesion of the Cr₃C₂-NiCr coating to 16Mn steel substrate is strongly influenced by the roughness and the current intensity. The range of substrate surface roughness and current intensity at which the Cr₃C₂-NiCr exhibited high adhesion to the steel substrate are discussed in this paper.

To clarify the anti-adhesive properties of the textured tool, two types of micro-grooved textures were fabricated on the tool rake face. The cutting tests were conducted on aluminum alloys under no lubrication condition. Experimental results showed that the cutting force, tool–chip friction coefficient, and surface wear of the P_1 textured tool decreased. However, noticeable disadvantages were observed in samples with other textures. Detailed research indicated that the chip material (Al alloy) was easy to squeeze into and clog in the micro-grooved texture, due to low hardness and high ductility. In contrast, the cutting force, tool–chip interfacial friction, and wear of steel samples with T_1, T_2, and P_2 textures were all greater than that of the nontextured tool. The difference observed in these various textures signifies the importance of the small geometric size of the surface texture in the P_1 texture. Thus, an improvement of tool anti-adhesion with aluminum alloy material was obtained under dry cutting conditions.

Neutron reflectometry (NR) was used to examine various live cells' adhesion to quartz substrates under different environmental conditions, including flow stress. To the best of our knowledge, these measurements represent the first successful visualization and quantization of the interface between live cells and a substrate with sub-nanometer resolution.

In our first experiments, we examined live mouse fibroblast cells as opposed to past experiments using supported lipids, proteins, or peptide layers with no associated cells. We continued the NR studies of cell adhesion by investigating endothelial monolayers and glioblastoma cells under dynamic flow conditions. We demonstrated that neutron reflectometry is a powerful tool to study the strength of cellular layer adhesion in living tissues, which is a key factor in understanding the physiology of cell interactions and conditions leading to abnormal or disease circumstances. Continuative measurements, such as investigating changes in tumor cell — surface contact of various glioblastomas, could impact advancements in tumor treatments. In principle, this can help us to identify changes that correlate with tumor invasiveness. Pursuit of these studies can have significant medical impact on the understanding of complex biological problems and their effective treatment, e.g. for the development of targeted anti-invasive therapies.

This paper describes the influence of surface roughness of steel plate on self-assembly behavior of silica particles based on SEM observations and the wettability of the suspension. The 304 stainless steel plate having two different surface roughness and spherical silica powder were used for the investigation. The silica layer was obtained by dipping the steel plate into the suspension and drawing it under various drawing speed. As a result, silica particle layers were formed on the plate surface when the stainless steel had a rough surface. In contrast, it was difficult to obtain the silica layers for the smooth surface.

The main aim of the paper is to embed the experimental results recently obtained studying the detachment force of single adhesion bonds in a multiphase model developed in the framework of mixture theory. In order to do that the microscopic information is upscaled to the macroscopic level to describe the dependence of some crucial terms appearing in the PDE model on the sub-cellular dynamics involving, for instance, the density of bonds on the membrane, the probability of bond rupture and the rate of bond formation. In fact, adhesion phenomena influence both the interaction forces among the constituents of the mixtures and the constitutive equation for the stress of the cellular components. Studying the former terms a relationship between interaction forces and relative velocity is found. The dynamics presents a behavior resembling the transition from epithelial to mesenchymal cells or from mesenchymal to ameboid motion, though the chemical cues triggering such transitions are not considered here. The latter terms are dealt with using the concept of evolving natural configurations consisting in decomposing in a multiplicative way the deformation gradient of the cellular constituent distinguishing the contributions due to growth, to cell rearrangement and to elastic deformation. This allows the description of situations in which if in some points the ensemble of cells is subject to a stress above a threshold, then locally some bonds may break and some others may form, giving rise to an internal reorganization of the tissue that allows to relax exceedingly high stresses.

Titanium nitride (TiN) films were deposited on high-speed steel (HSS) using cathodic arc physical vapor deposition (CAPVD) technique. The effect of substrate bias on the crystallography, microstructure, deposition rate, coating thickness and composition, hardness, and adhesion strength of TiN films was investigated. The crystallography of the films was investigated using X-ray diffraction with glazing incidence angle technique. The coating microstructure and elemental composition analysis were carried out using field emission scanning electron microscopy (FE-SEM) together with energy-dispersive X-ray. Crystallography of the films revealed that the effect of substrate bias shows complex symmetry in crystal structure. The resputtering effect due to the high-energy ion bombardment on the film surface influenced the thickness as well as the color of deposited coatings. By increasing the substrate bias from 0 to - 150 V, the size and amount of macrodroplets decreased, whereas the micro-Vickers hardness decreased from 2530 HV_0.05 to 1500 HV_0.05. Scratch tester used to compare the critical loads for coatings and the adhesion achievable at substrate bias of - 50 V was demonstrated, with relevance to the various modes.

In the present study, TiN coatings have been deposited on D2 tool steel substrates by using cathodic arc physical vapor deposition technique. The objective of this research work is to determine the usefulness of TiN coatings in order to improve the micro-Vickers hardness and friction coefficient of TiN coating deposited on D2 tool steel, which is widely used in tooling applications. A Pin-on-Disc test was carried out to study the coefficient of friction versus sliding distance of TiN coating deposited at various substrate biases. The standard deviation parameter during tribo-test result showed that the coating deposited at substrate bias of -75 V was the most stable coating. A significant increase in micro-Vickers hardness was recorded, when substrate bias was reduced from -150 V to zero. Scratch tester was used to compare the critical loads for coatings deposited at different bias voltages and the adhesion achievable was demonstrated with relevance to the various modes, scratch macroscopic analysis, critical load, acoustic emission and penetration depth. A considerable improvement in TiN coatings was observed as a function of various substrate bias voltages.

Cathodic Arc Physical Vapor Deposition (CAPVD), a technique used for the deposition of hard coatings, for tooling applications, has many advantages. The main drawback of this technique is the formation of macrodroplets (MDs) during deposition, resulting in films with rougher morphology. Constant etching, by increasing nitrogen gas flow rate up to 200 sccm, helped in reducing the MD size and number; at higher rates, of say 300 sccm, the behavior was reversed. Minimum value of surface roughness recorded at 200 sccm was measured via both surface roughness tester and atomic force microscopy (AFM). Micro-Vickers hardness of TiN-coated tool showed about 564% times increase in hardness than the uncoated one. Scratch tester was used to study the critical loads for the coating and the excellent adhesion achievable, of say 200 sccm, was demonstrated, with relevance to the various modes.