Nanometer Level Research Articles

Deep eutectic solvent-assisted fabrication of bioinspired 3D carbon-calcium phosphate scaffolds for bone tissue engineering.

Tissue engineering is a burgeoning field focused on repairing damaged tissues through the combination of bodily cells with highly porous scaffold biomaterials, which serve as templates for tissue regeneration, thus facilitating the growth of new tissue. Carbon materials, constituting an emerging class of superior materials, are currently experiencing remarkable scientific and technological advancements. Consequently, the development of novel 3D carbon-based composite materials has become significant for biomedicine. There is an urgent need for the development of hybrids that will combine the unique bioactivity of ceramics with the performance of carbonaceous materials. Considering these requirements, herein, we propose a straightforward method of producing a 3D carbon-based scaffold that resembles the structural features of spongin, even on the nanometric level of their hierarchical organization. The modification of spongin with calcium phosphate was achieved in a deep eutectic solvent (choline chloride : urea, 1 : 2). The holistic characterization of the scaffolds confirms their remarkable structural features (i.e., porosity, connectivity), along with the biocompatibility of α-tricalcium phosphate (α-TCP), rendering them a promising candidate for stem cell-based tissue-engineering. Culturing human bone marrow mesenchymal stem cells (hMSC) on the surface of the biomimetic scaffold further verifies its growth-facilitating properties, promoting the differentiation of these cells in the osteogenesis direction. ALP activity was significantly higher in osteogenic medium compared to proliferation, indicating the differentiation of hMSC towards osteoblasts. However, no significant difference between C and C-αTCP in the same medium type was observed.

Single-nucleobase resolution of a surface energy transfer nanoruler for in situ measurement of aptamer binding at the receptor subunit level in living cells.

In situ identification of aptamer-binding targets on living cell membrane surfaces is of considerable interest, but a major challenge, specifically, when advancing recognition to the level of membrane receptor subunits. Here we propose a novel nanometal surface energy transfer (NSET) based nanoruler with a single-nucleobase resolution (SN-nanoruler), in which FAM-labeled aptamers and single-sized gold nanoparticle (GNP) antibody conjugates act as a donor and an acceptor. A single nucleobase resolution of the SN-nanoruler was experimentally illustrated by molecular size, orientation, quenching nature, and other dye-GNP pairs. The SN-nanoruler provides high reproducibility and precision for measuring molecule distance on living cell membranes at the nanometer level owing to only the use of single-sized antibody-capped GNPs. In situ identification of the aptamer binding site was advanced to the protein subunit level on the living cell membrane for the utilization of this SN-nanoruler. The results suggest that the proposed strategy is a solid step towards the wider application of optical-based rulers to observe the molecular structural configuration and dynamic transitions on the membrane surface of living cells.

New insights into the morphological effects of MnOx-CeOx binary mixed oxides on Hg0 capture

In this study, the morphological effects of MnOx-CeOx adsorbents on their Hg0 elimination performance were investigated. The sample with a virgin nanorod microtopography performed significantly better than the nanocube-containing counterparts; in the whole temperature range investigated, a Hg0 removal efficiency of ∼97% was maintained. The microstructure of virgin nanorods possessed a high specific surface area, meaning that the interactions between Hg0 and adsorbent surface active sites would be encouraged. Furthermore, the strong acidity and oxidizability would facilitate the adsorption of Hg0 and the oxidation of the adsorbed Hg0 to HgO, which finally contributed to a superior Hg0 capture ability. During the entire Hg0 capture cycles, only Mn4+ and chemisorbed oxygen operated as the active sites in oxidizing Hg0 to HgO over the nanorod-containing MnOx-CeOx samples, whereas Ce4+ joined the active species group to oxidize Hg0 for the MnOx-CeOx with a virgin nanocube, despite its limited activity. Such knowledge demonstrated that morphology control of the adsorbents at the nanometer level could significantly increase their activity.

Preparation of anode material zinc ferrite by molten salt method and its electrochemical performance

• For the first time, zinc ferrite nanomaterials were synthesized by molten salt method which is an innovation in method. • The use of zinc, iron and other metals widely distributed in nature as anodes not only has low cost, but also has no pollution to the environment. It is very likely to replace carbon as a commercial lithium ion battery anode material. • Materials synthesized by molten salt method, high phase purity, good material characterization, stable cycle performance. Ternary zinc-based oxides are considered as excellent anode materials for lithium-ion batteries. In the present research, because the poor cycling stability, rapid capacity decay and poor rate performance of metal oxides as battery anodes limit its use to some extent, the electrochemical performance is improved by reducing the material particle size. The ZnFe 2 O 4 synthesized by molten salt method with NaCl and KCl as salt medium reaches the nanometer level and has great morphology. Through high temperature combustion at 838 °C, the material exhibits lamellar structure. The pure phase of ZnFe 2 O 4 is confirmed by X-ray diffractometer, and the diameter of the submicron stacks is about 100 - 400 nm by scanning with field emission electron microscope. After transmission electron microscopy analysis, the size of a single nanosheet is between 80 nm and 100 nm, and the lattice fringe at (311) crystal plane is confirmed to be 0.2475 nm by high-resolution transmission. Confirming the material image analysis and characterization analysis, the material is electrochemically tested. The first discharge capacity reaches 1285.8 mAh g −1 at the current density of 200 mA g −1 by using the Land test system, the charge specific capacity is 654.8 mAh g −1 , and the coulombic efficiency is 50.93%. After 300 cycles, the high reversible discharge capacity of 550 mAh g −1 is still maintained, keep that zinc ferrite synthesized by molten salt method not only has high capacity, but also has cycle stability compared with other anode materials, which can be used as anode materials for lithium-ion batteries.

Radial Error Motion Measurement and Its Uncertainty Estimation of Ultra Precision Axes of Rotation with Nanometer Level Precision.

The radial error is the key performance indicator of ultra-precision axis. In order to measure and evaluate the radial error of ultra-precision axis with nanometer accuracy, a measurement system with an accuracy of nanometer based on capacitive displacement probes and standard spheres is developed. The nonlinearity error of capacitive displacement probes, misalignment error of the probes, eccentric error of standard spheres, error caused by environment temperature change, environment vibration and error separation methods are analyzed and the effects of the above factors are obtained; Multiple measurement examples carried out with the measurement system this paaper constructed indicate the repeatability of the measurement system reaches 10.5 nm and the roundness error of artifact separated is less than 4.03 nm. In order to evaluate the measurement dispersion of the ultra-precision axis radial error, the major uncertainty components and the complete process of the comprehensive evaluation of the measurement uncertainty are proposed. The combined uncertainty of radial error motion measurement of the ultra-precision axis with Donaldson reversal is 31.64 nm (k = 2).

Effect of the Binder during Ultra-Precision Polishing of Tungsten Carbide Using a Semirigid Bonnet Tool.

Tungsten carbide (WC) has the characteristics of high hardness, high strength, corrosion resistance, wear resistance and excellent fracture toughness. Accordingly, it has been commonly used as the material for cutting tools and molds in glass-forming techniques. To obtain ultra-smooth surfaces, fine polishing of WC is indispensable. However, the efficiency of WC polishing is low using the existing polishing methods, and the mechanism behind the polishing process requires further investigation. Specifically, the effect of the binder in WC polishing is not clear since there are different kinds of WC with various weight percentages of the binder. In this paper, we present the findings of a study on the polishing performance of two kinds of WC material, with and without the binder, using a semi-rigid (SR) bonnet polishing tool. A series of experiments were performed on a 6-DOF robotic polishing instrument to investigate the material-removal characteristics, surface integrity and sub-surface damage after polishing. The results demonstrate that the SR bonnet polishing tool successfully reduced the surface roughness of WC with and without the binder to the nanometric level, though the lowest surface roughness was obtained on binder-less WC. No obvious sub-surface damage was observed under SEM inspection, while the processing efficiency was greatly improved owing to the high material removal rate of the tool. Based on our analysis of key polishing parameters and corresponding surface integrities, the effect of the binder on the polishing performance is explained, which offers excellent guidance for WC polishing.

Application of magnetic field assisted finishing process for nanofinishing of freeform femoral knee joint and performance analysis of finished surface

Finishing of femoral knee joint implant is very cumbersome due to its freeform nature. In the present study, a magnetic field-assisted finishing process is employed to uniformly finish the femoral knee implant over its surface curvature at the nanometer level. Experiments are conducted to analyze the freeform surface finishing capability of magnetic field-assisted finishing tool, which proves the tool’s capability to achieve the required surface properties of a femoral knee implant. A comparative analysis between the performance of the magnetic field assisted finishing process and manually polished surface relative to tibial bearing material, that is, ultra-high molecular weight polyethylene with the help of pin-on-disc tribometer, is carried out. It will help to understand the in vivo performance of a finished femoral component of the knee joint by a magnetic field-assisted finishing process. The wear tests prove that the volume loss of the disc material while considering magnetic field-assisted finished pins (11.79 mm3) are better in all cases than the manually polished pins (27.97 mm3). The tribology test also demonstrates that femoral knee implant polished using magnetic field-assisted finishing process will face fewer problems related to wear debris. It will also reduce the problems that occur due to the mixing of debris in the bloodstream. The polishing tool provides almost uniform nanometer-level surface finishing with a standard deviation of 19.23 along the surface curvature. The minimum achieved surface roughness of the femoral knee joint is 20 nm.

Preparation and characterization of Lycium Barbarum seed oil Pickering emulsions and evaluation of antioxidant activity

Lycium barbarum seed oil contains a variety of unsaturated fatty acids and other active substances, which is very beneficial to people's health. However, the application of Lycium barbarum seed oil is limited because it is insoluble in water and needs to be stored away from light. To solve these problems, Pickering emulsions were prepared by combining bacterial cellulose nanofibers and edible gelatin to stabilize Lycium barbarum seed oil. The average particle size, microstructure and rheology of the emulsion were characterized, and it was found that the droplets of the emulsion were smooth and distributed to the nanometer level, and the lowest concentration of bacterial cellulose nanofibers which could stabilize the emulsion was 0.3% (w/v). Surprisingly, by comparing the scavenging abilities of the Lycium barbarum seed oil and the emulsion on same free radicals, we observed that the antioxidant capacity of the emulsion increased significantly.

Advances in Superplasticity from a Laboratory Curiosity to the Development of a Superplastic Forming Industry

Superplasticity refers to the ability of some materials to pull out to tensile elongations of 400% or more when the strain rate sensitivity is ~0.5. The first report of true superplastic flow was published in 1934 in experiments conducted in England. However, this remarkable result attracted little interest among western scientific researchers and the result remained a laboratory curiosity for many years. Later, following extensive research on superplasticity in the Soviet Union, interest developed in the west, and superplasticity became a topic of extensive scientific research. This research was further enhanced with the demonstration that the application of severe plastic deformation provided an opportunity for achieving grain refinement to the submicrometer or even the nanometer level, and these small grains were especially attractive for achieving good superplastic properties. It is now recognized that superplastic alloys provide an excellent forming capability, especially in making high quality curved parts that are not easily fabricated using more conventional processes. This has led to the development of a large superplastic forming industry that currently processes many thousands of tons of sheet metals. This report traces these developments with an emphasis on the scientific principles behind the occurrence of superplastic flow.

Infrared imaging of surface confluent polydopamine (PDA) films at the nanoscale

Polydopamine (PDA) is one of the most commonly used materials for the preparation of protective adhesive layers for biomedical and tribological applications. Despite its widespread use, the way in which the polymer binds to the substrate is yet to be fully understood. At the nanometre level, the spatial arrangement of individual molecules and the initial growth of PDA layers are expected to be influenced by the utilized substrate material and PDA deposition time. To investigate these hypotheses, we have prepared PDA layers with various times of deposition on surfaces of gold and oxygen-terminated materials (silicon/silicon dioxide and nitrogen-doped titanium oxide). The prepared samples were subsequently analysed using a scattering-type scanning near-field optical microscope utilizing four irradiation energies in the mid-infrared region to detect the chemical contrast originating from vibrational modes of selected chemical moieties. It was found that the polymerization process leads to a formation of a surface confluent PDA layer and deposition of PDA nanoaggregates. The differences in the optical contrast observed at irradiation energies corresponding to the vibrations of indole units of PDA and quinoid groups of polymerization intermediates indicated a slightly different composition of the nanoaggregates and the surrounding confluent layer.

Obtaining and Characterizing Andean Multi-Floral Propolis Nanoencapsulates in Polymeric Matrices

Propolis is a substance with significant anti-inflammatory, anticancer, and antiviral activity, which could be used more efficiently at the nano level as an additive in the food industry. The aim was to obtain and characterize nanoencapsulated multi-floral propolis from the agro-ecological region of Apurimac, Peru. For nanoencapsulation, 5% ethanolic extracts propolis with 0.3% gum arabic and 30% maltodextrin were prepared. Then, the mixtures were dried by nano spraying at 120 °C using the smallest nebulizer. The flavonoid content was between 1.81 and 6.66 mg quercetin/g, the phenolic compounds were between 1.76 and 6.13 mg GAE/g, and a high antioxidant capacity was observed. The results of moisture, water activity, bulk density, color, hygroscopicity, solubility, yield, and encapsulation efficiency were typical of the nano spray drying process. The total organic carbon content was around 24%, heterogeneous spherical particles were observed at nanometer level (between 11.1 and 562.6 nm), with different behaviors in colloidal solution, the thermal gravimetric properties were similar in all the encapsulates, the FTIR and EDS analysis confirmed the encapsulation and the X-ray diffraction showed amorphous characteristics in the obtained material; stability and phenolic compound release studies indicated high values of 8.25–12.50 mg GAE/g between 8 and 12 h, the principal component analysis confirmed that the flora, altitude, and climate of the propolis location influenced the content of bioactive compounds, antioxidant capacity, and other properties studied. The nanoencapsulate from the district of Huancaray was the one with the best results, allowing its future use as a natural ingredient in functional foods. Nevertheless, technological, sensory, and economic studies should still be carried out.

Defects localization using the data fusion of laser Doppler and image correlation vibration measurements

This work proposes a defects localization method based on the combination of laser Doppler vibrometry (LDV) and Digital image correlation (DIC). DIC and LDV are the dominant non-contact vibration measurement methods with a matured theory and high stability. DIC gives a high spatial resolution with a measurement accuracy of several microns, whereas the Multipoint LDV has a limited spatial resolution with high-precision results for the sparse points up to nanometer level. However, the vibration-based defect localization (VBDL) necessitates certain measurement methods with both the high spatial resolution and measurement accuracy. Unfortunately, the accuracy of DIC is not sufficient to detect the data anomalies caused by the structural defects. Nevertheless, LDV cannot achieve a high-precision defect localization owing to the limited spatial resolution. In this study, a nonlinear weighted least-squares fitting has been proposed to improve the measurement accuracy and reliability. A Chebyshev polynomial has been employed as the basis function in the fitting process. The effective signal-to-noise ratio (SNR) and the correlation coefficient are employed as the weight basis of the LDV points and the DIC subsets, respectively. Based on the simulation analysis, the determination of the optimal polynomial order at multiple noise levels and the influence of the LDV points distribution are discussed. The experiment proves that the data fusion method can significantly improve spatial resolution and measurement accuracy. From the data fusion results, the reference-free defects localization in cantilever beams and plates based on residuals have been presented.

Gallium Antimonide Spherical Semiconductor Quantum Dots

The quantum effects at the nano-metric level have been observed in a variety of confined structures, particularly in semiconductor quantum dots. In this contribution, the electronic and optical properties of GaSb spherical semiconductor quantum dots are investigated. For the calculations, the pseudo potential approach was employed. The size dependence of the energy gaps at Г, X and L points, the effective masses of electrons and heavy-holes, the refractive index, and the dielectric function for a studied GaSb spherical quantum dot are analyzed and discussed. When the degree of quantum confinement effect was changed by decreasing the radius of the spherical quantum dots, a striking charge in comparison to the bulk values has been obtained. Our results indicate that as the quantum dot radius is raised, most of properties rapidly decrease. This demonstrates an improvement in the mobility of the material. However, the refractive index and the dielectric constant are increased with increasing the radius of the nano-crystal.

Slow-Off-Rate-Modified Aptamer Labeling for Fluorescence Microscopy and DNA-PAINT.

Super-resolution microscopy methods enable the visualization of biological processes on the level of a few nanometers. However, the application of these techniques in biological systems is limited by the availability of small affinity reagents. Slow off-rate-modified aptamers as nucleic acid analogues to antibodies have been successfully applied to improve the resolution and quantification of DNA-PAINT. In this chapter, we describe a protocol for using SOMAmers as labeling reagents for super-resolution microscopy.

Measurement and correction of lateral distortion in a Fizeau interferometer based on the self-calibration technique.

The lateral distortion of a surface measuring Fizeau interferometer may cause distorted image features in the lateral direction, as well as the surface form error in the axial direction (which is a source of the retrace error). Traditional method for lateral distortion measurement requires a high-accuracy calibration plate featuring a grid pattern. Such a calibration plate is not always available, especially when the required accuracy of the grid pattern comes to the order of sub-micrometer or even nanometer level. To remove the dependence on the plate accuracy, we propose a self-calibration method for the measurement and correction of lateral distortion in Fizeau interferometer. The self-calibration technique may separate the lateral distortion and the geometric error of the calibration plate. This method is verified using a 108-mm-aperture Fizeau interferometer. The experiments show that the form measurement error of a surface tilted at approximately 5° and 16° can be reduced from 92 nm to 43 nm and from 251 nm to 144 nm (peak-to-valley value), respectively, after the distortion correction.

Deformation temperature impacts on the microstructure evolution and mechanical properties of a novel medium-heavy alloy (MHA)

Medium-heavy alloys (MHAs) were rolled under different temperatures to characterize the microstructural evolution and mechanical properties by using optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, electron back scattered diffraction, tensile testing and microhardness testing. The results show that with an increase in the degree of deformation, the equiaxed grains are elongated along the rolling direction. A large number of slip bands are generated to coordinate intense plastic deformation, which leads to the formation of a fibrous texture. The sharp increase in dislocation density promotes significantly the dislocation interaction, which, in turn, refines the grain size of the MHAs to the nanometer level. Compared with the room-temperature rolling specimens, the cryorolling specimens underwent intense deformation. After 90% cryorolling deformation, the MHA grains were refined to 16.1 nm. The strength and hardness of the cryorolling specimens were significantly higher than those of the room-temperature rolling specimens, though the elongation was slightly lower. The fracture morphology of both specimens changed from ductile fracture (before deformation) to a mixed ductile–brittle fracture (after deformation).

Design, modeling, and test of a normal-stressed electromagnetic actuated compliant nano-positioning stage

This paper presents the design, modeling, and test of a novel normal-stressed electromagnetic (NSEA) compliant nano-positioning stage. The stage has a concise structure, which makes it compact and easy to assemble. With the consideration of the coupling interaction between the electromagnetic and mechanical components, an electromagnetic–mechanical modeling method for NSEA compliant nano-positioning stages is introduced. The direct relationship between the input current and the output displacement is derived in the static model, and the potential energy resulting from the magnetic field is considered in the dynamic model. Therefore, the working stroke and natural frequency of the NSEA compliant nano-positioning stage can be accurately predicted. A prototype with a stroke of 132.2μm and a natural frequency of 683.8 Hz is fabricated. Experimental results demonstrate that the proposed electromagnetic–mechanical modeling method has significantly higher prediction accuracy over the previous methods. A feedforward–feedback controller is designed, which enables a −3 dB control bandwidth of 145% of the open-loop natural frequency and a nanometer level motion resolution. A RMS tracking error of 0.45% is achieved for a 10 Hz triangular motion with ±50μm amplitude.

Dosimetry and microdosimetry of monoenergetic neutrons using recombination chamber – Measurements and Monte Carlo simulations

The REM-2 tissue-equivalent recombination chamber was used for dosimetry measurements performed in monoenergetic neutron reference fields at National Physical Laboratory, UK for the neutron energy range from 144 keV to 5 MeV. Measurement data were used for the determination of the recombination index of radiation quality, ambient dose, and finally ambient dose equivalent, H*(10). Results justify the relevance of the application of this measuring method in mixed radiation fields with dominant neutron component, which are present, for example, at photon and proton radiotherapy facilities. The relative response of the chamber in terms of H*(10) in the investigated neutron energy range, resulted in the correction factor at the maximum level of 1.25. Analysis of the saturation curves and use of the recombination microdosimetric method, RMM resulted in the determination of dose distribution at a nanometric level in terms of restricted linear energy transfer, LΔ. Monte Carlo simulations performed with the FLUKA code allowed to obtain double-differential distributions of L which were compared with those obtained during measurements. Comparison between measured and simulated data showed that RMM is a reliable method for microdosimetric investigations in mixed neutron-gamma fields present around medical radiotherapeutic units.

In-situ TEM investigation of failure processes in metal-plastic joint interfaces

The nano-scale failure behaviors of joint interfaces were investigated by in-situ straining technique to observe the crack propagations in a transmission electron microscope (TEM). The thin sections of bonded interfaces were subjected to tensile loading by using a specially designed specimen holder. The deformation at the crack tip before the initiation of crack and the initiation of the crack were observed in the nanometer level. The experiments with identical and dissimilar polymer/polymer welded specimens allowed us to see the plastic deformation ahead of the crack tip and the creation of craze, which is the typical failure mode of polymers. The failure of the interfaces between aluminum alloy (Al5052) and epoxy adhesive and between Al5052 and thermoplastic directly bonded by injection molding were investigated to visualize the failure behaviors in small scale before the macroscopic fracture of the interfaces. The in-situ straining technique under a high-resolution scanning transmission electron microscopy (STEM) mode enables the observation of micro deformation ahead of the crack, microvoids produced prior to the crack progression and the failure of the surface modified layer on Al surface.

Application of Polymer Nanocolloid Preparation in Stability Analysis of Motion Mechanics

Nanomaterials are widely used in various fields because of their own advantages. When the particle size of the material is reduced to the nanometer level, it will lead to new characteristics of acoustic, optical, electrical, magnetic, and thermal properties. This will greatly enrich the research content of the material and is expected to get new uses. Therefore, the preparation technology of nanomaterials is one of the current research hotspots and has broad application prospects. At present, the most commonly used preparation techniques are hydrothermal method and sol-gel method, but not all crystals grow in a hydrothermal environment, so this paper adopts the sol-gel method for preparation. However, in the preparation of nanocolloids, agglomeration often occurs between colloidal nanoparticles. In order to avoid the agglomeration between particles, this paper adopts an appropriate method to disperse the particles. In order to further explore the stability of nanocolloids, the colloidal film material prepared by the cadmium sulfide (CdS) sol method was used as the research sample. It also proposes a sol preparation method incorporating ultrasonic waves and further discusses the kinetic characteristics. The research results show that the sedimentation velocity of 1 nm cadmium sulfide nanocolloids in water is 1.3 × 10−12 (m/s) prepared by colloid of cadmium sulfide.