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Background. Nanocoating of biomedical materials may be considered the most essential developing field recently, primarily directed at improving their tribological behaviors that enhance their performance and durability. In orthodontics, as in many medical fields, friction reduction (by nanocoatings) among different orthodontic components is considered a substantial milestone in the development of biomedical technology that reduces orthodontic treatment time. The objective of the current research was to explore the tribological behavior, namely, friction of nanocoated thin layer by tantalum (Ta), niobium (Nb), and vanadium (V) manufactured using plasma sputtering at 1, 2, and 3 hours on substrates made of 316L stainless steel (SS), which is thought to be one of the most popular alloys for stainless steel orthodontic archwires. The friction of coated 316L SS archwires coated with Ta, Nb, and V plasma sputtering is hardly mentioned in the literature as of yet. Results. An oscillating pin-on-plate tribological test using a computerized tribometer was performed by applying a load of 1 N for 20 minutes under the dry condition at room temperature (25°C) to understand their role in the tribological behavior of the bulk material. Ta and Nb were found to reduce the friction of their SS substrate significantly (45 and 55%, respectively), while V was found to deteriorate the friction of its substrate. Moreover, sputtering time had no substantial role in the friction reduction of coatings. Conclusions. Nanocoating of 316L SS bulk material by Nb and Ta with a 1-hour plasma sputtering time can enhance dramatically its tribological behavior. Higher coating hardness, smaller nanoparticle size, intermediate surface coating roughness, and lower surface binding energy of the coatings may play a vital role in friction reduction of the coated 316L SS corresponding to SS orthodontic archwires, predicting to enhance orthodontic treatment. [ABSTRACT FROM AUTHOR]

In this paper, a capillary coated with poly(glycidyl methacrylate) nanoparticles (PGMA NPs) was prepared and applied to construct a capillary electrophoresis (CE) enantioseparation system with glucosyl-β-cyclodextrin (Glu-β-CD) as a chiral selector. The PGMA NP coating can be easily introduced through a simple ring-opening reaction. Two basic drugs were used as models to evaluate the separation performance of the PGMA coating. Under the optimal conditions selected, the separation of the two enantiomers was obtained. [ABSTRACT FROM AUTHOR]

We investigated the slow release of Zn ion (Zn2+) from nanocoatings and compared the in vitro response of osteoblasts (MC3T3-E1) and proosteoclasts (RAW 264.7) cultured on Ca2ZnSi2O7 nanocoated with different Zn/Ca molar ratios on a Ti-6Al-4V (i.e., Ti) substrate to optimize cell behaviors and molecule levels. Significant morphology differences were observed among samples. By comparing with pure Ti and CaSiO3 nanocoating, the morphology of Ca2ZnSi2O7 ceramic nanocoatings was rough and contained small nanoparticles or aggregations. Slow Zn2+ release from nanocoatings was observed and Zn2+ concentration was regulated by varying the Zn/Ca ratios. The cell-response results showed Ca2ZnSi2O7 nanocoating at different Zn/Ca molar ratios for osteoblasts and osteoclasts. Compared to other nanocoatings and Ti, sample Zn/Ca (0.3) showed the highest cell viability and upregulated expression of the osteogenic differentiation genes ALP, COL-1, and OCN. Additionally, sample Zn/Ca (0.3) showed the greatest inhibition of RAW 264.7 cell growth and decreased the mRNA levels of osteoclast-related genes OAR, TRAP, and HYA1. Therefore, the optimal Zn-Ca ratio of 0.3 in Ca2ZnSi2O7 ceramic nanocoating on Ti had a dual osteoblast-promoting and osteoclast-inhibiting effect to dynamically balance osteoblasts/osteoclasts. These optimal Zn-Ca ratios are valuable for Ca2ZnSi2O7 ceramic nanocoating on Ti-coated implants for potential applications in bone tissue regeneration. [ABSTRACT FROM AUTHOR]

Novel protein sensors based on tapered optical fibres modified with Au coatings deposited using two different procedures are proposed. Au-based coatings are deposited onto a nonadiabatic tapered optical fibre using (i) a novel facile method composed of layer-by-layer deposition consisting of polycation (poly(allylamine hydrochloride), PAH) and negatively charged SiO2 nanoparticles (NPs) followed by the deposition of the charged Au NPs and (ii) the sputtering technique. The Au NPs and Au thin film surfaces are then modified with biotin in order to bind streptavidin (SV) molecules and detect them. The sensing principle is based on the sensitivity of the transmission spectrum of the device to changes in the refractive index of the coatings induced by the SV binding to the biotin. Both sensors showed high sensitivity to SV, with the lowest measured concentration levels below 2.5 nM. The calculated binding constant for the biotin-SV pair was 2.2×10-11 M−1 when a tapered fibre modified with the LbL method was used, with a limit of detection (LoD) of 271 pM. The sensor formed using sputtering had a binding constant of 1.01×10-10 M−1 with a LoD of 806 pM. These new structures and their simple fabrication technique could be used to develop other biosensors. [ABSTRACT FROM AUTHOR]

Y2O3 nanoparticle suspension aqueous solution was prepared using citric acid. Then, Y2O3 film was deposited using this solution with pulsed electrophoretic deposition (EPD). A dense Y2O3 film of 25.7 μm thickness was obtained with deposition conditions of 0.5 wt% Y2O3 concentration, bias voltage of 0.5 V, and bias frequency of 1 kHz. The respective resistivities of the as-deposited film and films heat-treated at 200°C and 400°C were 2.84 × 103 Ω·cm, 5.36 × 104 Ω·cm, and 2.05 × 106 Ω·cm. A 59.8 μm thick dense Y2O3 film was obtained using two-step deposition with change of the bias voltage: a first step of 0.5 V and a second step of 2.0 V. [ABSTRACT FROM AUTHOR]

A thermal sprayed CoCrAlY coating was prepared by air plasma spray on the surface of Ni-based superalloy GH4169; then, a nanoscale aluminum film was deposited with electron beam vacuum deposition on it. The coatings irradiated by high-current pulsed electron beam were investigated. After HCPEB treatment, the Al film was remelted into the bond coat. XRD result shows that Al and Al2O3 phase were recorded in the irradiated and aluminized coatings, while Co-based oxides which originally existed in the initial samples disappeared. Microstructure observations reveal that the original coating with porosity, cavities, and inclusions was significantly changed after HCPEB treatment as compact appearance of interconnected bulged nodules. Moreover, the grains on the irradiated coating were very refined and homogeneously dispersed on the surface, which could effectively inhibit the corrosive gases and improve the coating oxidation resistance. [ABSTRACT FROM AUTHOR]

A large number of researches have been made to make the textile intelligent and smarter; this is achieved by imparting functionality to the textile materials. The indoor environment possesses a variety of pollutants which do not come from the outer environment, but they come from the inner environment itself. Today, the smarter fabrics that may clean the indoor air have been studied by various researchers. The smarter fabrics contain the nanocoating of semiconductor oxides, mostly TiO2; thus the synthesis and application of these nanoparticles on the textile material have been reviewed in this paper. Moreover, there are lots of environmental and health issues regarding nanoparticles that have also been discussed in brief. [ABSTRACT FROM AUTHOR]

The renewable cationic polyelectrolyte chitosan (CH) and anionic nanomontmorillonite (MMT) layers were alternately deposited on the surface of sisal fiber cellulose microcrystals (SFCM) via layer-by-layer (LBL) self-assembly method. The structure and properties of the composites were characterized by zeta potential, thermal gravimetric analysis (TGA), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometer (FTIR), microcalorimeter (MCC), and so forth. The zeta potential results show that the cellulose microcrystalline surface charge reversed due to the adsorption of CH and MMT nanoplatelets during multilayer deposition. MMT characteristic diffraction peaks appear in XRD patterns of SFCM(CH/MMT)5 and SFCM(CH/MMT)10 composites. Additionally, FESEM reveals that the SFCM(CH/MMT)10 surface is covered with a layer of material containing Si, which has been verified by elemental analysis. TGA results show that the initial decomposition (weight loss of 5%) temperature of SFCM(CH/MMT)5 is increased by 4°C compared to that of pure SFCM. On the other hand, carbon residue percentage of SFCM(CH/MMT)10 is 25.1%, higher than that of pure SFCM (5.4%) by 19.7%. Eventually, it is testified by MCC measurement that CH/MMT coating can significantly reinforce the flame retardant performance of SFCM. [ABSTRACT FROM AUTHOR]

Sodium alginate (NaAlg), as a natural biopolymer, was electrospun from aqueous solution via blending with a biofriendly synthetic polymer polyethylene oxide. The morphology and chemical properties of resultant alginate-based nanofibers were characterized by using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffractometer (PXRD), and differential scanning calorimetry (DSC). At a wide voltage window (i.e., 12–24 kV), smooth and uniform nanofibers were obtained from the 5.0% concentration with the NaAlg/PEO ratio ranging from 1 : 1 to 1 : 3. The results from FTIR, PXRD, and DSC demonstrate that molecular interaction exists between these two polymers and, therefore, contributes to the alteration of crystallinity of electrospun fibers. In addition, NaAlg/PEO nanofiber-coated polylactic acid (PLA) yarns with different twist levels were also fabricated in this work. The results show that the tensile strength of the nanocoated hybrid yarn and the tensile strength of uncoated yarn increase with the twist per centimeter (TPC) up to 0.5 but decrease when TPC is further increased. The tensile properties of hybrid yarn are superior to those of the uncoated yarn. [ABSTRACT FROM AUTHOR]

The multiscale analysis in the authors' finite element code confirmed possibility of fracture, because of not sufficiently high level of compressive residual stress in the TiN deposited by physical deposition method and varied mechanical properties of the thin film and substrate. The residual stress cannot be identified by X-ray technique for amorphous polymer and layer with domains of crystalline TiN. It is assumed that the buffer biocompatible thin film of Au in the TiN/Bionate II material system will alter the evolution of residual stress and, therefore, will allow to determine the residual stress in profilometry studies, and helps to improve toughness of the connection between TiN and Bionate II. The introduction of Au nanocoating in the material system results in bending of the sample and a compressive residual stress in the TiN coating. Results of finite element simulation show improvement of connection between the polymer and TiN, and an increase of compressive residual stress in the coating by introduction of Au nanointerlayer results in reduction of stress and strain in the substrate (close to the boundary between substrate and coating). [ABSTRACT FROM AUTHOR]

A parametric study on the release of titanium dioxide (TiO2) nanoparticles from two commercial photocatalytic nanocoatings is carried out. For this, abrasion tests are performed on them. The formed aerosols are characterized by their number concentration, particle size distribution, individual particle shape, size, and chemical composition. The two nanocoatings appear to exhibit contrastingly opposite behavior with respect to the number concentration of the released particles. Having irregular shapes, the released particles are found to have unimodal size distributions with 1.5-3.5% (in mass) of Ti content. However, no free nanoparticles of TiO2 were found. Distinct phases during the particle number concentration evolution with time are also discussed and evaluated. Two quantities-(ΔC/Δt)I and TII-are identified as the important indicators to qualitatively measure the resistance strength and hence the concentration of the released particles from a nanocoating during stress application. [ABSTRACT FROM AUTHOR]

Conductive carbon nanocoatings (conductive carbon layers—CCL) were formed on α-Al2O3 model support using three different polymer precursors and deposition methods. This was done in an effort to improve electrical conductivity of the material through creating the appropriate morphology of the carbon layers. The best electrical properties were obtained with use of a precursor that consisted of poly-N-vinylformamide modified with pyromellitic acid (PMA). We demonstrate that these properties originate from a specific morphology of this layer that showed nanopores (3-4 nm) capable of assuring easy pathways for ion transport in real electrode materials. The proposed, water mediated, method of carbon coating of powdered supports combines coating from solution and solid phase and is easy to scale up process. The optimal polymer carbon precursor composition was used to prepare conductive carbon nanocoatings on LiFePO4 cathode material. Charge-discharge tests clearly show that C/LiFePO4 composites obtained using poly-N-vinylformamide modified with pyromellitic acid exhibit higher rechargeable capacity and longer working time in a battery cell than standard carbon/lithium iron phosphate composites. [ABSTRACT FROM AUTHOR]

Alternate hard and soft layers increase deformation accommodation as thin hard layers slide relative to each other due to shear deformation of low modulus layers. However, the processing of such multi layers is challenging. In the present paper the alternating soft and hard multilayered SiCN coating deposited by magnetron sputtering has been studied and presented. A hardness and modulus of 37GPa and 317GPa with elastic recovery of 62% are achieved by alternate hard and soft layer of Si-C-N by magnetron sputtering. The trilayer films sustained even 2000 gf under indentation without failure though substrate plastically deformed. The fracture toughness value KIC was measured to be 9.5-10MPam½, significantly higher than many reported hard coatings. [ABSTRACT FROM AUTHOR]

Using the electrodeposition process, cobalt-iron (Co-Fe) nanocrystalline coatings were successfully synthesized onto stainless steel in deposition times of 30, 60, and 90 minutes. The temperature used throughout the process was 50°C in an acidic environment of pH 3. By changing the deposition time, physical properties such as phase and crystallographic structure, surface morphology, grain size, microhardness, and magnetic properties of Co-Fe coatings were examined. FESEM micrographs showed that the grain sizes of the coatings were in the range from 57.9 nm to 70.2 nm. Dendrite and irregular shapes were found in the microstructure of Co-Fe nanocoating. TheCo-Fe nanocrystalline coating prepared in a deposition time of 90 minutes achieved the highest microhardness of 339 HVN. The magnetic properties associated with Co-Fe nanocoating at longer deposition times show greater coercivity, Hc, and saturation magnetization, Ms, values of 56.43 Oe and 70.45 eμ/g, respectively. The M-H curves for all the Co-Fe coatings exhibited soft ferromagnetic behaviour with narrow hysteresis loops. It was found that increasing the deposition time also improved the microhardness and magnetic properties of Co-Fe nanocoating, which is much needed for long-life high-coercivity magnetic strip card applications. [ABSTRACT FROM AUTHOR]

Attempts have been made to improve the performance of dye-sensitized solar cells by forming metal-oxide nanocoating layers on ZnO electrodes by a sol-gel transformation. SiO2, Nb2O5, TiO2, or ZrO2 nanocoating layers could be formed by dipping ZnO films into metal alkoxide solutions of low concentrations and subsequent heat treatments. The performance of DSSCs using the coated ZnO electrodes depends strongly on the structure of coating layers such as the thickness and the surface coverage, which are significantly influenced by the coating conditions. In particular, SiO2 and Nb2O5 coating layers are effective to suppress the recombination by constructing the energy barrier at the ZnO/electrolyte interface and enhance energy conversion efficiency. It is found that the coating layers also hinder the grain growth of ZnO, contributing to the enhanced cell performance as well. [ABSTRACT FROM AUTHOR]