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To solve the problem of micro-electro-mechanical system (MEMS) gyroscope noise, this paper presents a variational mode decomposition (VMD) method based on crow search algorithm. First, the signal was decomposed by variational mode decomposition for optimization of crow search algorithm (CSA-VMD) method. The parameters required by the VMD method (penalty parameter α and decomposition number K) are given by the crow search algorithm, and then the signal is decomposed into the superposition of multiple subsignals, called intrinsic mode functions (IMFs). The sample entropy (SE) corresponding to each IMF is then obtained. By calculating the sample entropy, the noise signal can be divided into pure noise part, mixing part, and temperature drift part. Second, Savitzky–Golay smoothing denoising (SG) is used to filter the mixed noise signal to eliminate the influence of noise. Third, for the filtering of the drift part, the least square support vector machine optimized by the crow search algorithm (CSA-LSSVM) was used to filter, so as to reduce the effect of temperature drift. Finally, the processed signal is reconstructed to achieve the goal of denoising. Through the results, it can be found that the optimized VMD and LSSVM using CSA algorithm can achieve more effective denoising. After using the method proposed in this paper, the angular random walk value is 1.1175 ∗ 10−4°/h/√Hz, and the bias stability is 0.0017°/h. Compared with the original signal, the two signals are optimized by 98.1% and 98.2%, respectively. It can be seen from the experimental results that the proposed CSA-VMD method, SG method, and CSA-LSSVM method can effectively eliminate noise effects. [ABSTRACT FROM AUTHOR]

Purpose: To reduce the influence of temperature on MEMS gyroscope, this paper aims to propose a temperature drift compensation method based on variational modal decomposition (VMD), time-frequency peak filter (TFPF), mind evolutionary algorithm (MEA) and BP neural network. Design/methodology/approach: First, VMD decomposes gyro's temperature drift sequence to obtain multiple intrinsic mode functions (IMF) with different center frequencies and then Sample entropy calculates, according to the complexity of the signals, they are divided into three categories, namely, noise signals, mixed signals and temperature drift signals. Then, TFPF denoises the mixed-signal, the noise signal is directly removed and the denoised sub-sequence is reconstructed, which is used as training data to train the MEA optimized BP to obtain a temperature drift compensation model. Finally, the gyro's temperature characteristic sequence is processed by the trained model. Findings: The experimental result proved the superiority of this method, the bias stability value of the compensation signal is 1.279 × 10–3°/h and the angular velocity random walk value is 2.132 × 10–5°/h/vHz, which is improved compared to the 3.361°/h and 1.673 × 10–2°/h/vHz of the original output signal of the gyro. Originality/value: This study proposes a multi-dimensional processing method, which treats different noises separately, effectively protects the low-frequency characteristics and provides a high-precision training set for drift modeling. TFPF can be optimized by SEVMD parallel processing in reducing noise and retaining static characteristics, MEA algorithm can search for better threshold and connection weight of BP network and improve the model's compensation effect. [ABSTRACT FROM AUTHOR]

The noise signal in the gyroscope is divided into four levels: sampling frequency level, device bandwidth frequency level, resonant frequency level, and carrier frequency level. In this paper, the signal in the dual-mass MEMS gyroscope is analyzed. Based on the variational mode decomposition (VMD) algorithm, a novel dual-mass MEMS gyroscope noise reduction method is proposed. The VMD method with different four-level center frequencies is used to process the original output signal of the MEMS gyroscope, and the results are analyzed by the Allan analysis of variance, which shows that the ARW of the gyroscope is increased from 1.998*10−1°/√h to 1.552*10−4°/√h, BS increased from 2.5261°/h to 0.0093°/h. [ABSTRACT FROM AUTHOR]

Recently, the High-G MEMS accelerometer (HGMA) has been used in navigation, mechanical property detection, consumer electronics, and other fields widely. As the core component of a measuring system, it is very crucial to enhance the calibration accuracy of the accelerometer. In order to remove the noises in the accelerometer output signals to enhance its calibration accuracy, a combined denoising method which combines variational mode decomposition (VMD) with permutation entropy (PE) and wavelet threshold is given in this article. For the sake of overcoming the defect of signal distortion caused by the traditional denoising methods, this joint denoising method combines the good decomposition characteristics of VMD and the good denoising ability of wavelet threshold and introduces PE as a judgment criterion to achieve a good balance between denoising effect and signal fidelity. The combination of PE and VMD not only avoids the phenomenon of mode aliasing but also improves the ability to identify the noise components, which makes the wavelet threshold denoising more specific. Firstly, some intrinsic mode functions (IMFs) are obtained by using VMD to decompose the complex signal containing noise which is outputted from the accelerometer. Secondly, the IMF components can be divided into noise IMF components, mixed IMF components, and useful IMF components by PE algorithm. Thirdly, the noise IMF components can be discarded directly, and then the mixed IMF components can be denoised by wavelet threshold to obtain the noiseless IMF components; in addition, the useful IMF components need to be retained. Finally, the final denoising signal can be obtained by reconstructing the IMF components which have been denoised by the wavelet threshold and the useful IMF components retained before denoising. The experimental results prove that the combined denoising algorithm combines the merits of VMD, PE, and wavelet threshold, and this new algorithm has a good performance in the calibration denoising of accelerometer. Compared with the serious signal distortion caused by using only EMD or wavelet threshold, this method not only has a good denoising effect (the noises in the static part are eliminated by 99.97% and the SNR of the dynamic part is raised to 18.56) but also can maintain a good signal fidelity (the error of shock peak amplitude is 3.4%, the error of vibration peak amplitude is 0.4%, and the correlation coefficient between the denoising signals and dynamic part is as high as 0.982). [ABSTRACT FROM AUTHOR]

Bactericidal ZnO@ZnS nanorod-array facilitates the attachment and migration of human gingival fibroblasts via properly controlling the release of zinc. • A ZnO@ZnS nanorod array was designed and successfully coated on pure titanium. • The Zn release by ZnO@ZnS nanorod array was gentler than that by the ZnO one. • The ZnO@ZnS nanorods were bactericidal while promoting the function of fibroblasts. Cell-selective toxic titanium is highly desired in clinical dental practice. Herein, based on the in situ conversion of ZnO to ZnO@ZnS, nanorod-array structured coatings with a controllable release features of zinc (Zn), has been successfully fabricated by a two-step hydrothermal method to endow titanium surface with cell-selectivity, i.e. boosting the functions (attachment and migration) of human gingival fibroblasts (HGnFs) while acting against the invasion of pathogenic bacteria. The improved functions of HGnFs over the ZnO@ZnS nanorod-array were attributed to the material's optimized zinc release, which was decreased from an order of 3.5 mg L−1 to about 0.3 mg L−1 (within the first week). But more importantly, this concentration still had a high antibacterial efficacy up to 100% (against both the S. aureus and E. coli , 107 CFU mL−1). This study demonstrated that a ZnO@ZnS nanorod-array coating could be a promising strategy to endow titanium dental implants with improved soft tissue sealing and effectively reduce peri-implantitis. [ABSTRACT FROM AUTHOR]

This article suggested two methods to compensate for the temperature drift of the micro-electro-mechanical system gyroscopes, which are support vector machine method and C-means support vector machine. The output of X axis which was ranged from −40°C to 60°C based on the micro-electro-mechanical system gyroscope is reduced and analyzed in this article. The results showed the correctness of the two methods. The final results indicate that when the temperature is ranged from −40°C to 60°C, the factor of B is reduced from 0.424 (° h) to 0.02194 (° h) , and when the temperature is ranged from 60°C to −40°C, the factor of B is reduced from 0.1056 (° h) to 0.0329 (° h) , and the temperature drift trend and noise characteristics are improved clearly. [ABSTRACT FROM AUTHOR]

This paper proposed three methods to compensate the temperature energy influence drift of the MEMS vibration gyroscope, including radial basis function neural network (RBF NN), RBF NN based on genetic algorithm (GA), and RBF NN based on GA with Kalman filter (KF). Three-axis MEMS vibration gyroscope (Gyro X, Gyro Y, and Gyro Z) output data are compensated and analyzed in this paper. The experimental results proved the correctness of these three methods, and MEMS vibration gyroscope temperature energy influence drift is compensated effectively. The results indicate that, after RBF NN-GA-KF method compensation, the bias instability of Gyros X, Y, and Z improves from 139°/h, 154°/h, and 178°/h to 2.9°/h, 3.9°/h, and 1.6°/h, respectively. And the angle random walk of Gyros X, Y, and Z was improved from 3.03°/h1/2, 4.55°/h1/2, and 5.89°/h1/2 to 1.58°/h1/2, 2.58°/h1/2, and 0.71°/h1/2, respectively, and the drift trend and noise characteristic are optimized obviously. [ABSTRACT FROM AUTHOR]

Tantalum films were deposited on negatively biased Ti6Al4V substrates using filtered cathodic vacuum arc deposition to enhance the corrosion resistance of the Ti6Al4V alloy. The effect of substrate voltage bias on the microstructure, mechanical and corrosion properties was examined and the cytocompatibility of the deposited films was verified with mammalian cell culturing. The Ta films deposited with substrate bias of −100 V and −200 V show a mixture of predominantly β phase and minority of α phase. The Ta/−100 V film shows adhesive failure at the Ti/Ta interface and a cohesive fracture is observed in Ta/−200 V film. The Ta/−100 V showed a significant improvement in corrosion resistance, which is attributed to the stable oxide layer. The in - vitro cytocompatibility of the materials was investigated using rat bone mesenchymal stem cells, and the results show that the Ta films have no adverse effect on mammalian cell adhesion and spreading proliferation. [ABSTRACT FROM AUTHOR]

This paper presents the bandwidth expanding method with wide-temperature range for sense mode coupling dual-mass MEMS gyro. The real sensing mode of the gyroscope is analyzed to be the superposition of in-phase and anti-phase sensing modes. The mechanical sensitivity and bandwidth of the gyroscope structure are conflicted with each other and both governed by the frequency difference between sensing and drive modes (min {Δω1, Δω2}). The sensing mode force rebalancing combs stimulation method (FRCSM) is presented to simulate the Coriolis force, and based on this method, the gyro’s dynamic characteristics are tested. The sensing closed- loop controller is achieved by operational amplifier based on phase lead method, which enable the magnitude margin and phase margin of the system to reach 7.21 dB and 34.6° respectively, and the closed-loop system also expands gyro bandwidth from 13 Hz (sensing open-loop) to 102 Hz (sensing closed-loop). What’s more, the turntable test results show that the sensing closed-loop works stably in wide-temperature range (from −40 °C to 60 °C) and the bandwidth values are 107 Hz @−40 °C and 97 Hz @60 °C. The results indicate that the higher temperature causes lower bandwidth, and verify the simulation results are 103 Hz @−40 °C and 98.2 Hz @60 °C. The new bottleneck of the closed loop bandwidth is the valley generated by conjugate zeros, which is formed by superposition of sensing modes. [ABSTRACT FROM AUTHOR]

Modulating immune response to biomaterials through changing macrophage polarization has been proven to be a promising strategy to elicit beneficial outcomes in tissue repair. The objective of this study was to evaluate the response of macrophage polarization to titanium doped with magnesium (0.1~0.35%), which was prepared through the magnesium plasma immersion ion implantation (Mg PIII) technique. The M1/M2 polarization profile of macrophages was investigated using a murine cell line RAW 264.7 in vitro and a murine air pouch model in vivo. Our results demonstrated that the Mg PIII-treated titanium induced a higher percentage of M2 macrophages and higher concentrations of the anti-inflammatory cytokines interleukin (IL)-4 and IL-10. Genes encoding two growth factors, bone morphogenetic protein 2 (BMP2) and vascular endothelial growth factor (VEGF) were up-regulated, thus indicating the ability of the M2 phenotype to promote wound healing. The nuclear factor κB (NF-κB) signalling pathway was down-regulated. In vivo the Mg PIII -treated titanium elicited a similar effect on macrophage polarization and induced thinner fibrous capsule formation and a decrease in infiltrated cells. These results indicate that Mg PIII treatment has the immunomodulatory potential to elicit the pro-healing M2-polarized macrophage phenotype, thus providing new insight into the development of immunomodulatory biomaterials. [ABSTRACT FROM AUTHOR]

The antimicrobial efficacy of silver nanoparticles (Ag NPs) modified material was generally governed by the dose of the particles or their capability to release silver ions. Here, it was found that Ag NPs acted against microbes by cooperating with tantalum oxide (TAO) in a Schottky barrier dependent manner. Size tunable Ag NPs were in situ fabricated and immobilized on TAO coating by a silver plasma immersion ion implantation process (Ag PIII). The antibacterial efficacy of these Ag NPs was reversely dependent on their size, that is large particles (~20 nm) were more efficiency than small ones (~10 nm) in defeating the invasion by bacteria. The result is consistent with the prediction of Schottky-Mott theory, which rectified the electron transfer nature across the interfaces between Ag NPs and the TAO substrate. [ABSTRACT FROM AUTHOR]

This paper analyzes different noise components in MEMS gyroscope silicon structure, including mechanical–thermal noise (MTN), electronic-thermal noise (ETN), flicker noise (FN) and Coriolis signal in-phase noise (IPN). The structure equivalent electronic model is established, and the improved differential interface is proposed based on weak signal detection technology, after that, the noise components in silicon structure are introduced and analyzed in sense open loop. The quadrature error (QE) signal automatically cancellation loop is proposed, and the results of the experiment indicate that the equivalent angular rates of QE and IPN are 46°/s and 4.55°/s respectively. The interfaces contrast experiments show that the DC noise and the useful signal amplitudes of differential and single-side detection interfaces are −49.8 dBmV, −16.8 dBmV and −39.8 dBmV (−42.1 dBmV), −22.1 dBmV (−22.2 dBmV), which confirms the differential interface has better SNR. The carrier experiments also illustrate that higher carrier frequency (from 500 kHz to 10 MHz) can restrain DC noise (from −19.8 dBmV to −54.2 dBmV) better, which demonstrate the FN is the dominant noise component of the silicon structure under normal temperature. The temperature experiments show the DC noise enhances from −48.5 dBmV to −14.6 dBmV over the range 20 °C to 60°C while the useful signal amplitude remains around -16.6dBmV, and this phenomenon indicates the MTN and ETN become the dominant structure noise components gradually with temperature rising. [ABSTRACT FROM AUTHOR]

Prevention of periprosthetic infection (PPI) by inhibiting biofilm formation on prostheses is crucial to orthopedic surgery. In this work, silver nanoparticles (Ag NPs) are fabricated in situ and immobilized on titanium by silver plasma immersion ion implantation (PIII). The anti-biofilm activity rendered by the immobilized Ag NPs is assessed using Staphylococcus epidermidis , a biofilm producing strain, in vitro and in vivo . The immobilized Ag NPs show no apparent cytotoxicity but reduce biofilm formation in vitro by inhibiting bacteria adhesion and icaAD transcription. The immobilized Ag NPs offer a good defense against multiple cycles of bacteria attack in vitro , and the mechanism is independent of silver release. Radiographic assessment, microbiological cultures, and histopathological results demonstrate the ability of the functionalized surface against bacterial infection to reduce the risk of implant-associated PPI. [ABSTRACT FROM AUTHOR]

Surface modification of titanium based materials with balanced biological property, i.e. inhibit the adhesion of pathogenic bacteria but promote the positive functions of mammalian cells, is highly desired. Accordingly, titanium was successively treated with magnesium and silver plasma immersion ion implantation & deposition (Mg–Ag PIII&D). Scanning electron microscopy (SEM) observations revealed that nanoparticles were precipitated and bound to the titanium surface after Mg–Ag PIII&D. X-ray photoelectron spectroscopy (XPS) results indicated that these particles are metallic silver. Responses of both bacterial and mammalian cells were studied with Escherichia coli ( E. coli ) and osteoblast-like cell line MG63. The results indicated that the Mg–Ag PIII&D treated titanium inhibits the adhesion and proliferation of E. coli , but promotes the initial adhesion and alkaline phosphatase (ALP) expression of MG63 cells. It can be concluded that the antibacterial and osteogenic activities of titanium can be balanced by simultaneously taking advantage of the biological nature of magnesium and silver. [ABSTRACT FROM AUTHOR]

Highlights: [•] Zn was implanted into titanium using plasma immersion ion implantation technology. [•] The Zn-implanted titanium surfaces exhibited excellent osteogenic activity. [•] The Zn-implanted titanium surfaces possessed partly antibacterial effect. [Copyright &y& Elsevier]

Abstract: It is believed that the excellent biological performance of a titanium implant is a result of its passivating nature, forming of a whole titanium oxide layer on the implant. There are increasing evidences that the titanium oxide layer is decisive for a good contact of an orthopedic implant to its surrounding tissue. And numerous reports reveal that the titanium oxide can be activated by chemical or physical procedures. In this article, based on the mechanisms and mode of action, they are classified into four categories, including doping of inorganic components, light exciting, interface engineering, and external electric field programming. The exploration and design on light exciting and interface engineering procedures are most worth receiving further illuminations since these kinds of processes are promising in fabrication of coatings with selective or “smart” biological activity. [Copyright &y& Elsevier]

A novel method is investigated in this paper to estimate the temperature's influence upon the resonant frequency (RESF) and quality factor (Q) of a vacuum packaged Micro-Electro-Mechanical-System (MEMS) gyroscope, which can give suggestions to improve the architecture's temperature robustness. The dual-mass decoupled gyroscope's architecture is introduced, and the drive and sense modes' mechanical character are analyzed. The models of RESF and damping are established, and the influence factors are investigated. Four samples are tested and the results indicate that the models can estimate and evaluate the tendency of the RESF and Q in different temperature. The investigation also considers the Young Modulus is the dominate element influencing RESF and increasing the thickness and width of the U-shaped spring can decrease this influence; Q is impacted mainly by the air viscosity coefficient and ambient pressure. The errors of the models are caused by manufacture error and the air getter's influence. [ABSTRACT FROM AUTHOR]

Osseointegration of an orthopedic implant involves a cascade of cellular and extracellular biological events that take place at bone/implant interface. The process can be enhanced by coating implants with materials of various compositions, chemistry, topographies. The aim of this article was to review the literatures on development and application of numerous plasma-sprayed ceramic coatings (including hydroxyapatite, wollastonite, dicalcium silicate, titanium oxide, and zirconia coatings) for establishing and maintaining the osseointegration based on some major biological requirements, such as good cytocompatibility, advantageous cell response, superior tissue response, effective anti-infection activities. [ABSTRACT FROM AUTHOR]

Abstract: Titanium embedded with silver nanoparticles (Ag NPs) using a single step silver plasma immersion ion implantation (Ag-PIII) demonstrate micro-galvanic effects that give rise to both controlled antibacterial activity and excellent compatibility with osteoblasts. Scanning electron microscopy (SEM) shows that nanoparticles with average sizes of about 5 nm and 8 nm are formed homogeneously on the titanium surface after undergoing Ag-PIII for 0.5 h and 1 h, respectively. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) indicate that those nanoparticles are metallic silver produced on and underneath the titanium surface via a local nucleation process from the solid solution of α-Ti(Ag). The Ag-PIII samples inhibit the growth of both Staphylococcus aureus and Escherichia coli while enhancing proliferation of the osteoblast-like cell line MG63. Electrochemical polarization and Zeta potential measurements demonstrate that the low surface toxicity and good cytocompatibility are related to the micro-galvanic effect between the Ag NPs and titanium matrix. Our results show that the physico-chemical properties of the Ag NPs are important in the control of the cytotoxicity and this study opens a new window for the design of nanostructured surfaces on which the biological actions of the Ag NPs can be accurately tailored. [ABSTRACT FROM AUTHOR]

Abstract: The phase transformations occurring in a 0.45 wt.% C plain steel subjected to plasma nitriding at 540–560 °C for 5.5 h, followed by a salt bath thermoreactive deposition and diffusion (TRD) chromizing process at 500 °C or 550 °C (a process referred to as low-temperature chromizing or duplex chromizing) was investigated by means of optical microscopy(OM), scanning electron microscopy(SEM), X-ray energy dispersive spectroscopy(EDS), and X-ray diffraction. It was found that a CrN compound layer with an average thickness of 7.4 μm and an average micro-hardness of 1476 HV0.01 was formed in the prior plasma nitrided compound layer by low-temperature chromizing at 550 °C for 6 h. The chromized coating as a whole was found consisting of three sub-layers, namely the outer CrN layer, the intermediate diffusional layer, and the inner residual nitrided compound layer, all formed in the prior nitrided compound layer, and with the inner sub-layer vanishing by prolonging the chromizing time. The intermediate diffusional layer formed at the initial stages of TRD was seen “black” under OM (hence is called “black zone”), and found consisting of α-Fe as a major phase. The self-exhaustion of the “black zone” promoted the chromium atom diffusion deeper into the substrates. The transformation paths involved in the decomposition of the prior nitrided compound layer was likely to be ε-Fe2–3N→γ′-Fe4N→α-Fe; and the high hardness of the chromized coating was attributed to a large amount of nano-sized and evenly distributed CrN grains generated in the compound layer. [Copyright &y& Elsevier]

[Display omitted] • Fibrinogen assembly behaviors were first imaged by scanning electrochemical microscopy. • Fibrinogen assembly structures were only detectable in calcium-doped titanium surfaces. • A dye-assisted scanning electron microscopy method was developed to image fibrinogen assembly morphologies. Fibrinogen adsorption is a critical host response to the insertions of various medical devices. Scanning electrochemical microscopy (SECM) has the power to probe the local interactions between proteins and bulk solids in liquid environments; however, our knowledge of the distribution or the assembly structures of protein adsorption is limited. Here, fibrinogen assembly behaviors on calcium-doped titanium are imaged by resolving the strength of the SECM probe's negative feedback in two-dimensional micro-regions. By using ion implantation techniques, calcium and/or silver were doped into polished titanium surfaces. The calcium-doped titanium was capable of releasing calcium, while the clean titanium and silver-doped titanium did not release their constituents. The two-dimensional discontinuous distribution of the probe current/steady current ( i / i 0 ) values were only detectable in calcium-doped groups, and this was incubating duration dependent, showing the micro-regions preferential for fibrinogen assembly in calcium-doped groups. This was consistent with the fibrinogen adsorption morphologies on calcium-doped titanium examined by dye-assisted scanning electron microscopy. It is concluded that protein assembly behaviors on bulk solid surfaces in liquid environments can be imaged by resolving the distribution of the SECM probe currents in two-dimensional areas. The method is promising in illuminating the true surface-protein interactions and the protein adsorption structure–function relations. [ABSTRACT FROM AUTHOR]

Editor's Note: this Article has been retracted; the Retraction Note is available at https://doi.org/10.1038/s41598-021-88664-z. [ABSTRACT FROM AUTHOR]

Finding approaches to control the elementary processes of plasma-solid interactions and direct the fluxes of matter at nano-scales becomes an important aspect in science. This letter reports that, by taking advantages of the spacing characteristics of discrete TiO2 nanotube arrays, the flying trajectories and the subsequent implantation and deposition manner of energetic carbon ions can be directed and controlled to fabricate hollow conical arrays. The study provides an alternative method for plasma nano-manufacturing. [ABSTRACT FROM AUTHOR]

In recent years, High-G MEMS accelerometers have been widely used in aviation, medicine, and other fields. So it is extremely important to improve the accuracy and performance of High-G MEMS accelerometers. For this purpose, we propose a fusion algorithm that combines EMD, wavelet thresholding, and temperature compensation to process measurement data from a High-G MEMS accelerometer. In the fusion algorithm, the original accelerometer signal is first decomposed by EMD to obtain the intrinsic mode function (IMF). Then, sample entropy (SE) is used to divide the IMF components into three segments. The noise segment is directly omitted, wavelet thresholding is performed on the mixing segment, and a GA-BP performs temperature compensation on the drift segment. Finally, signal reconstruction is implemented. Later, a comparative analysis is carried out on the results from four models: EMD, wavelet thresholding, EMD + wavelet thresholding, and EMD + wavelet thresholding + temperature compensation. The experimental data show that the acceleration random walk change from 1712.66 g/h/Hz0.5 to 79.15 g/h/Hz0.5 and the zero-deviation stability change from 49275 g/h to 774.7 g/h. This indicates that the fusion algorithm (EMD + wavelet thresholding + temperature compensation) not only effectively suppresses the noise of high-frequency components but also compensates for temperature drift in the accelerometer. [ABSTRACT FROM AUTHOR]

Modulating immune response to biomaterials through changing macrophage polarization has been proven to be a promising strategy to elicit beneficial outcomes in tissue repair. The objective of this study was to evaluate the response of macrophage polarization to titanium doped with magnesium (0.1~0.35%), which was prepared through the magnesium plasma immersion ion implantation (Mg PIII) technique. The M1/M2 polarization profile of macrophages was investigated using a murine cell line RAW 264.7 in vitro and a murine air pouch model in vivo. Our results demonstrated that the Mg PIII-treated titanium induced a higher percentage of M2 macrophages and higher concentrations of the anti-inflammatory cytokines interleukin (IL)-4 and IL-10. Genes encoding two growth factors, bone morphogenetic protein 2 (BMP2) and vascular endothelial growth factor (VEGF) were up-regulated, thus indicating the ability of the M2 phenotype to promote wound healing. The nuclear factor κB (NF-κB) signalling pathway was down-regulated. In vivo the Mg PIII -treated titanium elicited a similar effect on macrophage polarization and induced thinner fibrous capsule formation and a decrease in infiltrated cells. These results indicate that Mg PIII treatment has the immunomodulatory potential to elicit the pro-healing M2-polarized macrophage phenotype, thus providing new insight into the development of immunomodulatory biomaterials. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Partially fluorinated graphene shows favorable antibacterial ability. • Fluorinated graphene film could inhibit platelet aggregation. • Partially fluorinated graphene is more suitable for biological applications. Abstract Graphene halides are promising two-dimensional systems which have interesting physical and chemical properties. In particular, high quality fluorinated graphene offers a great potential in modulating variable properties by regulating its surface microstructure. Moreover, the fluorine introduction and carbon-fluorine bonding characters will enable some interesting biological response. Here, the biological responses to bacteria and cells of fluorinated graphene were studied. Present work revealed that partially fluorinated graphene behaved satisfactory antibacterial ability. Fluorinated graphene showed well facilitating function to cell adhesion in early period, however, after a longer incubation period, the enhanced intracellular ROS level in rBMSCs on the fully fluorinated graphene gives rise to the decrease of cell viability. It was found that there is no statistical difference in the activity of alkaline phosphatase (ALP) and matrix mineralization of rBMSCs on pristine graphene, partially fluorinated graphene and fluorographene. In addition, the introduction of fluorine into pristine graphene plane reduced the adhesion and aggregation of blood platelets due to the attenuation of π–π interaction between material surface and blood protein. The findings in this work revealed that partial fluorinated graphene exhibited better antibacterial ability and cytocompatibility, outperforming pristine graphene and fluorographene. [ABSTRACT FROM AUTHOR]

Summary: In this paper, we present an extended state observer–based robust dynamic surface trajectory tracking controller for a quadrotor unmanned aerial vehicle subject to parametric uncertainties and external disturbances. First, the original cascaded dynamics of a quadrotor unmanned aerial vehicle is formulated in a strict form with lumped disturbances to facilitate the backstepping design. Second, based on the separate outer‐ and inner‐loop control methodologies, the extended state observers are constructed to online estimate the unmeasurable velocity states and lumped disturbances existed in translational and rotational dynamics, respectively. Third, to overcome the problem of “explosion of complexity” inherent in backstepping control, the technique of dynamic surface control is utilized for trajectory tracking and attitude stabilization, and with the velocity and disturbance estimates incorporated into the dynamic surface control, a robust dynamic surface flight controller that guarantees asymptotic tracking in the presence of lumped disturbances is synthesized. In addition, the stability analysis is given, showing that the present robust controller can ensure the ultimate boundedness of all signals in the closed‐loop system and make the tracking errors arbitrarily small. Finally, comparisons and extensive simulations under different flight scenarios are performed to validate the effectiveness and superiority of the proposed scheme in accurate tracking performance and enhanced antidisturbance capability. [ABSTRACT FROM AUTHOR]

The clinic application of magnesium is mainly impeded by its poor corrosion resistance and implants with localized drug delivery attract tremendous interest. Here, Mg/Al layered double hydroxide (Mg-Al LDH) film was in situ prepared on AZ31 alloy by a hydrothermal process, and further calcined to form metastable mixed oxides, also named Mg/Al layered double oxide (LDO). Finally, immersing in 5-Fluorouracil (5-FU) solution, Mg/Al LDO would revert to Mg/Al LDH via a memory effect, and be loaded with 5-FU (#LDO-5FU). Comparing to AZ31 alloy, the corrosion resistance of the as-prepared #LDO-5FU sample was enhanced. The amount of released 5-FU from #LDO-5FU sample was ∼993 ng/cm 2 . The proliferation of human cholangiocarcinoma cell (RBE) was effectively inhibited on the surface of #LDO-5FU sample owing to the release of 5-FU. This work broadens the application of calcined LDH and provides a new strategy in the field of surface modification of magnesium alloy. [ABSTRACT FROM AUTHOR]

Titanium (Ti) has been widely used as orthopedic and dental implants, it is very important to improve the osteogenic activity and antibacterial ability of titanium implants. The objective of this work was to investigate the osteogenic and antibacterial ability of the zinc (Zn) ion implanted Ti at different implantation voltage. X-ray photoelectron spectroscopy results indicate that Zn was successfully implanted into titanium. Zn-implanted titanium surfaces exhibit enhanced cell proliferation ability, alkaline phosphatase (ALP) activity, and partial resistance to both Escherichia coli ( E . coli ) and Staphylococcus aureus ( S . aureus ). The excellent osteogenic and antibacterial ability are highly related to the implantation voltage. The cell proliferation and antibacterial ability can be enhanced by increasing the implantation voltage from 15 kV to 30 kV, indicating that Zn implantation at 30 kV is more beneficial to both osteogenic and antibacterial ability. [ABSTRACT FROM AUTHOR]

Dynamic calibration is an important measurement method to improve the dynamic performance of sensors. However, the structure and packaging of the accelerometer and the ubiquitous noise interfered with the results. Therefore, a method based on BP neural network and particle swarm optimization algorithm is proposed to dynamically calibrate the elevation accelerometer in a composite package in the frequency domain, to realize the systematic identification of the accelerometer dynamic model. Numerical simulations and experimental results demonstrate that compared with the narrow pulse width calibration theory, this method achieves the accuracy requirement while broadening the calibration band by more than 7 times. It is also proved that this method is effective in parameter identification. [Display omitted] • The accelerometer dynamic model is proposed and the parameters are optimized. • The combination of neural network and particle swarm optimization algorithm can improve the accuracy of the model parameters. • The high-G shock experiment is finished by using Hopkinson bar, and the shock is over 100,000 g. [ABSTRACT FROM AUTHOR]

This paper presents a new type of three-axis gyroscope. The gyroscope comprises two independent parts, which are nested to further reduce the structure volume. The capacitive drive was adopted. The motion equation, capacitance design, and spring design of a three-axis gyroscope were introduced, and the corresponding formulas were derived. Furthermore, the X/Y driving frequency of the gyroscope was 5954.8 Hz, the Y-axis detection frequency was 5774.5 Hz, and the X-axis detection frequency was 6030.5 Hz, as determined by the finite element simulation method. The Z-axis driving frequency was 10,728 Hz, and the Z-axis sensing frequency was 10,725 Hz. The MEMS gyroscope's Z-axis driving mode and the sensing mode's frequency were slightly mismatched, so the gyroscope demonstrated a larger bandwidth and higher Z-axis mechanical sensitivity. In addition, the structure also has good Z-axis impact resistance. The transient impact simulation of the gyroscope structure showed that the maximum stress of the sensitive structure under the impact of 10,000 g@5 ms was 300.18 Mpa. The gyroscope was produced by etching silicon wafers in DRIE mode to obtain a high aspect ratio structure, tightly connected to the glass substrate by silicon/glass anode bonding technology. [ABSTRACT FROM AUTHOR]

Titanium implants possessing simultaneous osseointegration and antibacterial ability are desirable. In this work, three types of Zn/Ag micro-galvanic couples are fabricated on titanium by plasma immersion ion implantation to investigate the osseointegration and antibacterial effects as well as the involved mechanisms. The in vitro findings disclose enhanced proliferation, osteogenic differentiation, and gene expressions of the rat bone mesenchymal stem cells (rBMSCs), as well as good antibacterial ability on all three micro-galvanic couples. Excellent antimicrobial ability is also observed in vivo and the micro-CT and histological results reveal notable osseointegration in vivo despite the presence of bacteria. The Zn/Ag micro-galvanic couple formed on Zn/Ag dual-ion co-implanted titanium shows the best osseointegration as well as good antibacterial properties in vivo obtained from a rabbit tibia model. The difference among the three Zn/Ag micro-galvanic couples can be ascribed to the contact between the Ag NPs and Zn film, which affects the corrosion process. Our results indicate that the biological behavior can be controlled by the corrosion process of the Zn/Ag micro-galvanic couples. [ABSTRACT FROM AUTHOR]

Abstract: Zinc (Zn) and silver (Ag) are co-implanted into titanium by plasma immersion ion implantation. A Zn containing film with Ag nanoparticles (Ag NPs) possessing a wide size distribution is formed on the surface and the corrosion resistance is improved due to the micro-galvanic couples formed by the implanted Zn and Ag. Not only are the initial adhesion, spreading, proliferation and osteogenic differentiation of rBMSCs observed from the Zn/Ag implanted Ti in vitro, but also bacteria killing is achieved both in vitro and in vivo. Electrochemical polarization and ion release measurements suggest that the excellent osteogenic activity and antibacterial ability of the Zn/Ag co-implanted titanium are related to the synergistic effect resulting from the long-range interactions of the released Zn ions and short-range interactions of the embedded Ag NPs. The Zn/Ag co-implanted titanium offers both excellent osteogenic activity and antibacterial ability and has large potential in orthopedic and dental implants. [Copyright &y& Elsevier]

Underwater polarization information can provide reliable autonomous heading feedback for underwater scenes in the presence of satellite denial and multi-source interference. A biologically inspired highly robust polarization orientation strategy is proposed to address the degradation caused by weak polarization and noisy patterns in underwater environments with poor illumination, turbidity, and cloud recession. This approach initially develops a biomimetic algorithm that enhances weak polarization information, based on the increased perception mechanism of the visual neural pathway of syrphid fly under weak light conditions. After overcoming restricting polarization transmission, it is further optimized with a non-local sparse coding denoising part that takes into account the similarity in the detailed structure of the polarized image's effective zenith region. Relying on the stable ∞ symmetric distribution of the angle of polarization, the ±π/2 feature point distribution is traversed and assigned, and polarization information is quantitatively assigned, compensated, and regulated along the solar meridian region, excluding invalid polarized pixels. The experiments demonstrate that the methodology effectively reconstructs the symmetry of the partially damaged angle of polarization distribution, eliminates external interference, autonomously solves the fitted heading correction problem, and improves the environmental adaptability of the bionic polarization compass. The data from underwater experiments indicate the orientation accuracy: the error in weakly polarized patterns is within 2°, and the accuracy in noisy patterns can be increased by over 50%. • A biologically inspired highly robust polarization orientation strategy is proposed in underwater environments. • Using a biomimetic algorithm based on the visual neural pathway of syrphid fly under weak light conditions. • The non-local sparse coding denoising part is supplemented for the noise of polarized images in turbid water bodies. [ABSTRACT FROM AUTHOR]

To address the effect of temperature, we establish a temperature compensation model for gyroscope output signal using long short-term memory network (LSTM), support vector machine (SVM), and depth belief network (DBN). We develop a denoising algorithm using variational mode decomposition (VMD), and sampling entropy (SE) to eliminate the influence of factors other than temperature on the MEMS gyroscope. First, the signal is decomposed into several intrinsic mode functions (IMF) using VMD. Then, the decomposed IMFs are classified into three categories: feature terms, mixture terms, and noise terms using SE. These three categories of signals are processed separately, preserving the useful signal of the original signal while precisely removing the noise. Subsequently, the processed signals are reconstructed to obtain the reconstructed signals. Finally, we perform temperature experiments and find that the rate random wander and bias instability of the gyroscope compensated output signal are reduced by 84.35% and 95.57%, respectively. [Display omitted] • Parallel processing effectively protects the static drift model. • The proposed LSTM-SVM-DBN model, is particularly well-suited for effectively analyzing MEMS gyroscope signals. • The rate random wander and bias instability of the gyroscope output signal were reduced by 84.35% and 95.57%. [ABSTRACT FROM AUTHOR]

This article investigates a neurodynamic quantized control problem with improved transient performances for microelectromechanical system (MEMS) gyroscopes subject to lumped disturbances induced by parameter uncertainties, dynamic coupling, and external disturbances. First, a modified prescribed performance control mechanism based on a hyperbolic cosecant performance function is proposed to specify the transient behavior of tracking errors with an arbitrarily small overshoot. Then, to eliminate the lumped disturbances with a better identification property, a novel echo state network approximator that uses the estimation error to learn neural weights is designed with the aid of a minimal learning parameter technique, which not only can exclude the poor transient behaviors occurring extensively in the existing neural control with a large adaptive gain, but also dramatically reduce the number of parameters to be updated online. Furthermore, contrasting to the available tracking results assuming a continuous control updating, a hysteresis quantizer is introduced to provide discrete values of control signals, supporting the use of digital devices in MEMS gyroscope implementations to realize a closed-loop error stabilization. Finally, ultimately uniformly bounded stability of closed-loop system is proved with the aid of Lyapunov function and nonsmooth analysis technique, while not only simulations but also experimental results are performed to validate the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

To improve the seamless navigation ability of an integrated Global Positioning System (GPS)/inertial navigation system in GPS-denied environments, a hybrid navigation strategy called the self-learning square-root- cubature Kalman filter (SL-SRCKF) is proposed in this article. The SL-SRCKF process contains two innovative steps: 1) it provides the traditional SRCKF with a self-learning ability, which means that navigation system observations can be provided continuously, even during long-term GPS outages; and 2) the relationship between the current Kalman filter gains and the optimal estimation error is established, which means that the optimal estimation accuracy can be improved by error compensation. The superiority of the proposed SL-SRCKF strategy is verified via experimental results and prominent advantages of this approach include: 1) the SL-SRCKF comprises two cycle filtering systems that work in a tightly coupled mode, and this allows more accurate error correction results to be obtained during GPS outages; 2) the system's error prediction ability is effectively improved by introducing a long short-term memory, which provides much better performance than other neural networks, such as random forest regression or the recursive neural network; and 3) under different (30, 60, and 100 s) GPS outage conditions, the long-term stability of SL-SRCKF is much better than that of other error correction approaches. [ABSTRACT FROM AUTHOR]

Navigation in primates is generally supported by cognitive maps. Such a map endows an animal with navigational planning capabilities. Numerous methods have been proposed to mimic these natural navigation capabilities in artificial systems. Based on self-navigation and learning strategies in animals, we propose in this work a place recognition strategy for brain-inspired navigation. First, a place recognition algorithm structure based on convolutional neural networks (CNNs) is introduced, which can be applied in the field of intelligent navigation. Second, sufficient images are captured at each landmark and then stored as a reference image library. Simple linear iterative clustering (SLIC) is used to segment each image into superpixels with multi-scale viewpoint-invariant landmarks. Third, highly representative appearance-independent features are extracted from these landmarks through CNNs. In addition, spatial pyramid pooling (SPP) layers are introduced to generate a fixed-length CNN representation, regardless of the image size. This representation boosts the quality of the extracted landmark features. The proposed SLIC-SPP-CNN place recognition algorithm is evaluated on one collected dataset and two public datasets with viewpoint and appearance variations. [ABSTRACT FROM AUTHOR]

Abstract With the ability to host anions or neutral drugs, layered double hydroxide (LDH) are hot spots in the field of biomaterials. Intensive works so far only have focused on their application in surface modification or injectable medicine. Yet, little literatures report the potential of LDH as bone implants. In the present study, four types of LDH (Mg Al, Mg Fe, Zn Al and Zn Fe) were prepared via a coprecipitation method. Our results showed that the synthetic LDH powders can be pressed into discs in the absence of binder. The discs can maintain their shape after immersed in culture medium for 10 days, not including Mg Al LDH disc. The elastic modulus of all discs was between 9 and 35 GPa, which was close to cortical bone (5–23 GPa). Zn Al LDH and Zn Fe LDH showed higher cytotoxicity than Mg Al LDH and Mg Fe LDH whether in the form of suspension or extract. Furthermore, even up to 10 mg/mL, the extract of Mg Al LDH and Mg Fe LDH showed no cytotoxicity, while cells were totally died in the extract of Zn Al LDH and Zn Fe LDH. Compared with cells, bacterial showed an even lower tolerance concentration to Zn Al LDH and Zn Fe LDH. This study indicates that Mg-containing LDH show better cytotocompatibility, while Zn-containing LDH show better antibacterial property. With proper elastic modulus and controllable biological effect, LDH are promising to be used as bone implants. Highlights • Mg Al LDH, Mg Fe LDH, Zn Al LDH and Zn Fe LDH are prepared at pH 10. • Pressed Mg Al LDH disc is collapsed when immersed in solution. • The elastic modulus of all the pressed discs is in nature bone range. • Zn-containing LDH show higher toxicity to cells and bacteria than Mg-containing LDH. [ABSTRACT FROM AUTHOR]

Background/Aims: Accumulating evidence demonstrates the superior osteoinductivity of tantalum (Ta) to that of titanium (Ti); however, the mechanisms underlying these differences are unclear. Thus, the objective of the present study was to examine the effects of Ta and Ti surfaces on osteogenesis using rat bone mesenchymal stromal cells (rBMSCs) as a model. Methods: Ta and Ti substrates were polished to a mirror finish to minimize the influences of structural factors, and the intrinsic surface effects of the two materials on the integrin α5β1/mitogen-activated protein kinases 3 and 1 (ERK1/2) cascade-mediated osteogenesis of rBMSCs were evaluated. Alkaline phosphatase (ALP) activity, Alizarin Red staining, real-time polymerase chain reaction, and western blot assays of critical osteogenic markers were conducted to evaluate the effects of the two substrates on cell osteogenesis. Moreover, the role of the integrin α5β1/ERK1/2 pathway on the osteoinductive performance of Ta and Ti was assessed by up- and down-regulation of integrin α5 and β1 with RNA interference, as well as through ERK1/2 inhibition with U0126. Results: Osteogenesis of rBMSCs seeded on the Ta surface was superior to that of cells seeded on the Ti surface in terms of ALP activity, extracellular matrix calcification, and the expression of integrin α5, integrin β1, ERK1/2, Runt-related transcription factor 2, osteocalcin, collagen type I, and ALP at both the mRNA and protein levels. Moreover, down-regulation of integrin α5 or integrin β1, or ERK1/2 inhibition severely impaired the osteoblastic differentiation on the Ta surface. By contrast, over-expression of integrin α5 or integrin β1 improved osteogenesis on the Ti substrates, while subsequent ERK1/2 inhibition abrogated this effect. Conclusion: The integrin α5β1/ERK1/2 pathway plays a crucial role in regulating rBMSCs osteogenic differentiation; thus, the greater ability of a Ta surface to trigger integrin α5β1/ERK1/2 signaling may explain its better osteoinductivity. The different effects of Ta and Ti surfaces on rBMSC osteogenesis are considered to be related to the conductive behaviors between integrin α5β1 and the oxides spontaneously formed on the two metals. These results should facilitate the development of engineering strategies with Ta and Ti surfaces for improved osteogenesis in endosteal implants. [ABSTRACT FROM AUTHOR]

This paper presents a high-G MEMS accelerometer (HGMA). HGMA employs our-beams and central-island mass silicon structure, which features a robust stability in shock environment. Theoretical analysis is conducted to investigate the influence of structure parameters on the Von Mises stress distribution, mechanical sensitivity and natural frequency. With consideration of smaller stress, higher mechanical sensitivity and natural frequency, the structure parameters are optimized and the theoretical sensitivity of HGMA is calculated as 0.488μV/g. Then, the optimized structure is analyzed with finite element analysis software, which shows a maximum stress of 23.19 MPa and a frequency response of 408.19 kHz when a 100 000 g shock is loaded. Finally, a processing flow is designed and the structure is fabricated. Hopkinson bar is utilized to calibrate HGMA sample, and shows an experimental sensitivity of 0.5611μV/g. Long-term static bias and temperature experiments are arranged to evaluate HGMA. Test results verify the presented theoretical analysis, processing flow, and experiment method, which are of great value for guiding the design, fabrication and calibration of other HGMAs. [ABSTRACT FROM AUTHOR]

In this paper, we design a symmetric quad-beam accelerometer structure for z-axis sensing. Considering the extremely high chemical stability of SiC, traditional dry etching is not suitable for machining SiC MEMS sensor. Thus, we put forward a method using ultraviolet laser cutting to release cantilever beam of SiC accelerometer and using laser ablating to process mass. Pulse Repetition Frequency (PRF) and processing laps are optimized to obtain high-quality surface morphology and much less thermal effect. Finally, we use the optimal parameters with 35 kHz pulse frequency, 4 processing laps, 200 mm/s scanning speed to process through-hole. Combing with Raman spectrum and EDS spectrum, the feasibility of laser machining SiC sensor is studied. The result shows that in machining cantilever beam the carbonization and generation of silicon accelerates the trepanning depth of SiC. However, in machining the hole, the thermal effect of photon energy barely adds influence on region from boundary of hole to 30 μm. Thus, it is feasible to use laser cutting to release cantilever beam while it is difficult to use laser ablating processing back cavity of accelerometer. The time of laser micromachining 4 H-SiC cantilever beam is less than 2 s. Compared with the traditional ICP etching (0.2–1.3 μm/min), etching rate with laser ablating in releasing cantilever beam significantly increases nowadays. Finally, the sensitivity of SiC accelerometer is measured to 0.644 μV/g. [ABSTRACT FROM AUTHOR]

Pulse Coupled Neural Network (PCNN) has gained widespread attention as a nonlinear filtering technology in reducing the noise while keeping the details of images well, but how to determine the proper parameters for PCNN is a big challenge. In this paper, a method that can optimize the parameters of PCNN by combining the genetic algorithm (GA) and ant colony algorithm is proposed, which named as GACA, and the optimized procedure is named as GACA-PCNN. Firstly, the noisy image is filtered by median filter in the proposed GACA-PCNN method; then, the noisy image is filtered by GACA-PCNN constantly and the median filtering image is used as a reference image; finally, a set of parameters of PCNN can be automatically estimated by GACA, and the pretty effective denoising image will be obtained. Experimental results indicate that GACA-PCNN has a better performance on PSNR (peak signal noise rate) and a stronger capacity of preserving the details than previous denoising techniques. [ABSTRACT FROM AUTHOR]

Purpose This study aims to fabricate and manipulate ensemble spin of negative nitrogen-vacancy (NV−) centres optimally for future solid atomic magnetometers/gyroscope. Parameters for sample preparation most related to magnetometers/gyroscope are, in particular, the concentration and homogeneity of the NV− centres, the parameters’ microwave antenna of resonance frequency and the strength of the microwave on NV− centres. Besides, the abundance of other impurities such as neutral NV centres (NV0) and substitutional nitrogen in the lattice also plays a critical role in magnetic sensing.Design/methodology/approach The authors succeeded in fabricating the assembly of NV centres in diamond and they determined its concentration of (2-3) × 1016 cm−3 with irradiation followed by annealing under a high temperature condition. They explored a novel magnetic resonance approach to detect the weak magnetic fields that takes advantage of the solid-state electron ensemble spin of NV− centres in diamond. In particular, the authors set up a magnetic sensor on the basis of the assembly of NV centres. They succeeded in fabricating the assembly of NV centres in diamond and determined its concentration. They also clarified the magnetic field intensity measured at different positions along the antenna with different lengths, and they found the optimal position where the signal of the magnetic field reaches the maximum.Findings The authors mainly reported preparation, initialization, manipulation and measurement of the ensemble spin of the NV centres in diamond using optical excitation and microwave radiation methods with variation of the external magnetic field. They determined the optimal parameters of irradiation and annealing to generate the ensemble NV centres, and a concentration of NV− centres as high as 1016 cm−3 in diamond was obtained. In addition, they found that sensitivity of the magnetometer using this method can reach as low as 5.22 µT/Hz currently.Practical implications This research can shed light on the development of an atomic magnetometer and a gyroscope on the basis of the ensemble spin of NV centres in diamond.Social implications High concentration spin of NV− in diamond is one of the advantages compared with that of the atomic vapor cells, because it can obtain a higher concentration. When increasing the spin concentration, the spin signal is easy to detect, and macro-atomic spin magnetometer become possible. This research is the first step for solid atomic magnetometers with high spin density and high sensitivity potentially with further optimization. It has a wide range of applications from fundamental physics tests, sensor applications and navigation to detection of NMR signals.Originality/value As has been pointed out, in this research, the authors mainly worked on fabricating NV− centres with high concentration (1015-1016 cm−3) in diamond by using optimal irradiation and annealing processes, and they quantitatively defined the NV− concentration, which is important for the design of higher concentration processes in the magnetometer and gyroscope. Until now, few groups can directly define the NV− concentration. Besides, the authors optimized the microwave antenna parameters experimentally and explored the dependence between the splitting of the magnetic resonance and the magnetic fields, which dictated the minimum detectable magnetic field. [ABSTRACT FROM AUTHOR]

Boundary structure is an important factor for significantly influencing the settlement of microalgae. In order to investigate the effect of boundary structure on the antifouling performances of biomimetic textured coatings, three different boundary structures were fabricated via biomimetic replication method and evaluated by recording the settlement amount of fouling microalgae including Nitzschia closterium f. minutissima , Phaeodactylum tricornutum and Chlorella . The results showed that imbricate boundary structure was more positive for antifouling, but depressed boundary structure and raised boundary structure played a negative role for antifouling. Especially, the depressed boundary structure displayed the worst antifouling performance which attributed to providing shelters for microalgae. The antifouling mechanism of microalgae settled on the biomimetic textured coatings with different boundary structures was revealed deeply. [ABSTRACT FROM AUTHOR]

• Proposed a Pitch Angle Sliding Variance Test method based on Mahony for zero-velocity detection. • The performance of zero-velocity detection is improved compared to traditional method. • Better zero-velocity detection results are obtained by using PSVT under multiple motion states. The threshold judgment method is a comparatively simple and classic zero-velocity detection (ZVDT) method for zero-velocity update. To solve the problem with the existing threshold judgment method, where the ZVDT effect is critically diminished by sensor noise, motion state changes, and other factors, this paper proposes a pitch angle sliding variance test (PSVT) method based on Mahony filtering. First, a Mahony filtering algorithm is designed to merge and de-noise the original foot acceleration and angular velocity information to provide high-precision pitch angle information. Subsequently, based on the significant periodicity, isolation, and characteristics of foot pitch angle variation during pedestrian movement, a PSVT method is proposed for pedestrian ZVDT. Experimental results show that for the motions of different pedestrians in different scenes, the average single-step misjudgment rate in the zero-velocity interval of the proposed method is less than 10% overall. When compared with the generalized likelihood ratio test, the ZVDT effect is improved by approximately 30%. The method effectively improves the applicability and accuracy of ZVDT for pedestrian movement, and will be significant in improving the applicability, navigational accuracy, and practical use of pedestrian autonomous navigation systems. [ABSTRACT FROM AUTHOR]

A temperature error processing method for a dual-mass micro-electromechanical system (MEMS) gyroscope based on multi-scale parallel model is proposed. At first, a sample entropy based bounded ensemble empirical mode decomposition (SE-BEEMD) is proposed to decompose the original signal into different scales, include noise-only scale, mixed scale and drift scale; then forward linear prediction (FLP) is employed to eliminate the noise at mixed scale and extreme learning machine (ELM) based model is employed to compensate the drift at drift scale, the two steps are carried out paralleled; at last the final results can be obtained after reconstruction. Experimental results show that: (1) compared to tradition serial model, the proposed parallel model can eliminate the temperature errors more effectively, and each parameter of Allan analysis is improved. Specially, the quantification noise reduced from 0.035 μrad to 9.93e4 μrad, angle random walk reduced from 2.13e-5/s 1/2 to 7.94e-6/s 1/2 , bias instability reduced from 5.28e-4/s to 4.79e-4/s, rate random walk from 0.012/s 3/2 to 0.092/s 3/2 and angular rate ramp reduced from 0.013/s 2 to 0.011/s 2 ; (2) compared to traditional time consuming neural networks, the ELM has the best modeling accurate and shortest training time, which would be valuable for online temperature drift modeling and compensation. [ABSTRACT FROM AUTHOR]

Topographic modification in nanoscale is one of the most often used strategies to enhance the interfacial biocompatibility of implant materials. The aim of this work is to produce SiO 2 /TiO 2 coatings with nanoporous structures and favorable biological properties by atmospheric plasma spraying technology and subsequently hydrothermal etching method in hydrogen fluoride solution. The effects of hydrothermal time and temperature on the microstructures and osteoblast behavior of the SiO 2 /TiO 2 coatings were investigated. Results demonstrated that the as-sprayed SiO 2 /TiO 2 coating was mainly composed of rutile and quartz phases. After etching, nanoporous topographies were formed on the surface of the coatings and the hydrothermal parameters had important influences on the size and shape of the pores. The interconnected network pores on the coating surface could only produce at the appropriate hydrothermal conditions (the hydrothermal time and temperature were 60 min and 100 °C, respectively). Compared to TiO 2 and SiO 2 /TiO 2 coatings, nanoporous SiO 2 /TiO 2 coatings could enhance osteoblast adhesion and promote cell proliferation. The results suggested the potential application of the porous coatings for enhancing the biological performance of the currently used dental and orthopedic implant materials. [ABSTRACT FROM AUTHOR]