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Purpose: Sagittal spinal malalignment often leads to surgical realignment, which is associated with major complications. Low bone mineral density (BMD) and impaired bone microstructure are risk factors for instrumentation failure. This study aims to demonstrate differences in volumetric BMD and bone microstructure between normal and pathological sagittal alignment and to determine the relationships among vBMD, microstructure, sagittal spinal and spinopelvic alignment. Methods: A retrospective, cross-sectional study of patients who underwent lumbar fusion for degeneration was conducted. The vBMD of the lumbar spine was assessed by quantitative computed tomography. Bone biopsies were evaluated using microcomputed tomography (μCT). C7-S1 sagittal vertical axis (SVA; ≥ 50 mm malalignment) and spinopelvic alignment were measured. Univariate and multivariable linear regression analysis evaluated associations among the alignment, vBMD and μCT parameters. Results: A total of 172 patients (55.8% female, 63.3 years, BMI 29.7 kg/m2, 43.0% with malalignment) including N = 106 bone biopsies were analyzed. The vBMD at levels L1, L2, L3 and L4 and the trabecular bone (BV) and total volume (TV) were significantly lower in the malalignment group. SVA was significantly correlated with vBMD at L1–L4 (ρ = -0.300, p < 0.001), BV (ρ = − 0.319, p = 0.006) and TV (ρ = − 0.276, p = 0.018). Significant associations were found between PT and L1–L4 vBMD (ρ = − 0.171, p = 0.029), PT and trabecular number (ρ = − 0.249, p = 0.032), PT and trabecular separation (ρ = 0.291, p = 0.012), and LL and trabecular thickness (ρ = 0.240, p = 0.017). In the multivariable analysis, a higher SVA was associated with lower vBMD (β = − 0.269; p = 0.002). Conclusion: Sagittal malalignment is associated with lower lumbar vBMD and trabecular microstructure. Lumbar vBMD was significantly lower in patients with malalignment. These findings warrant attention, as malalignment patients may be at a higher risk of surgery-related complications due to impaired bone. Standardized preoperative assessment of vBMD may be advisable. [ABSTRACT FROM AUTHOR]

Purpose: Lumbar fusion surgery has become a standard procedure in spine surgery and commonly includes the posterior placement of pedicle screws. Bone quality is a crucial factor that affects pedicle screw purchase. However, the relationship between paraspinal muscles and the bone quality of the pedicle is unknown. The aim of the study was to determine the relationship between paraspinal muscles and the ex vivo bony microstructure of the lumbar pedicle. Methods: Prospectively, collected data of patients undergoing posterior lumbar fusion for degenerative spinal conditions was analyzed. Pre-operative lumbar magnetic resonance imaging (MRI) scans were evaluated for a quantitative assessment of the cross-sectional area (CSA), functional cross-sectional area (fCSA), and the proportion of intramuscular fat (FI) for the psoas muscle and the posterior paraspinal muscles (PPM) at L4. Intra-operative bone biopsies of the lumbar pedicle were obtained and analyzed with microcomputed tomography (µCT) scans. The following cortical (Cort) and trabecular (Trab) bone parameters were assessed: bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), connectivity density (CD), bone-specific surface (BS/BV), apparent density (AD), and tissue mineral density (TMD). Results: A total of 26 patients with a mean age of 59.1 years and a mean BMI of 29.8 kg/m2 were analyzed. fCSAPPM showed significant positive correlations with BV/TVTrab (ρ = 0.610; p < 0.001), CDTrab (ρ = 0.679; p < 0.001), Tb.NTrab (ρ = 0.522; p = 0.006), Tb.ThTrab (ρ = 0.415; p = 0.035), and ADTrab (ρ = 0.514; p = 0.007). Cortical bone parameters also demonstrated a significant positive correlation with fCSAPPM (BV/TVCort: ρ = 0.584; p = 0.002; ADCort: ρ = 0.519; p = 0.007). FIPsoas was negatively correlated with TMDCort (ρ = − 0.622; p < 0.001). Conclusion: This study highlights the close interactions between the bone microstructure of the lumbar pedicle and the paraspinal muscle morphology. These findings give us further insights into the interaction between the lumbar pedicle microstructure and paraspinal muscles. [ABSTRACT FROM AUTHOR]

Differing from metal alloys produced by conventional techniques, metallic products prepared by additive manufacturing experience distinct solidification thermal histories and solid−state phase transformation processes, resulting in unique microstructures and superior performance. This review starts with commonly used additive manufacturing techniques in steel−based alloy and then some typical microstructures produced by metal additive manufacturing technologies with different components and processes are summarized, including porosity, dislocation cells, dendrite structures, residual stress, element segregation, etc. The characteristic microstructures may exert a significant influence on the properties of additively manufactured products, and thus it is important to tune the components and additive manufacturing process parameters to achieve the desired microstructures. Finally, the future development and prospects of additive manufacturing technology in steel are discussed. [ABSTRACT FROM AUTHOR]

To understand the process window of bias‐enhanced nucleation of diamond, it is important to study surface modifications of Ir substrates that occur under different conditions. Herein, various microstructures formed on Ir substrates are reported. The first microstructure contains rectangular particles with a size of several hundred nanometers obtained at a relatively high pressure of 12.5 kPa and a high temperature of 880 °C; these particles consist of epitaxially grown Ir3Si species. The second microstructure includes particles oriented along the [110] direction; these particles, however, consist of etched Ir pillars with a height of 400 nm when the substrate temperature increases to 1110 °C. Both microstructures form because of Ir sputtering due to the bombardment of energetic charged ions and the transport of Ir surface atoms. This study demonstrates two types of surface modifications under different bias‐enhanced nucleation conditions and provides a method for preparing an epitaxial Ir–Si compound that can be applied in various silicon‐based electronic devices. [ABSTRACT FROM AUTHOR]

Tetrahedral amorphous carbon (ta-C) films with many superior properties approaching those of diamond crystal were prepared using filtered cathodic vacuum arc technology. To ascertain the sp3-rich deposition condition, the dependence of the film microstructure on the deposition energy was investigated by means of visible Raman spectroscopy, x-ray photoelectron spectroscopy, electron energy loss spectroscopy, x-ray reflectivity, and nanoindentation. The maximum hardness and Young’s modulus are achieved at a bias of -80 V, at which the maximum sp3 fraction of about 82% is obtained. Under this condition, the most symmetric Raman line shape, the highest x-ray photoemission C 1s core level position and a π* transition peak with the smallest integral area in the K-edge spectra are simultaneously achieved. The structural properties are found to be strongly correlated with the mass density of the films. At the optimal substrate bias of -80 V, the film mass density reaches its maximum value. The cross section of the films is characterized with a layered distribution in mass density. A surface layer with low density is an intrinsic feature and experimental evidence of the subplantation growth of the films. [ABSTRACT FROM AUTHOR]

Abstract: A series of yttrium oxide films has been fabricated on Si (100) wafers by different substrate temperatures based on reactive magnetron sputtering technology. And the evolution of composition, microstructure and optical properties of Y2O3 films has been investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and spectroscopic ellipsometry (SE). It is shown that stoichiometric Y2O3 with much strong Y O bond and cubic nanophase with larger size notably enhance the optical properties, especially refractive index. At low substrate temperature, the composition of Y2O3 films has nonstoichiometry feature accompanying with much physisorbed oxygen (Oδ) compared with these at high temperature. Increasing substrate temperature promotes the formation of Y O bonds, approaching the stoichiometry with lower Oδ content. The film commences crystallizing at room temperature, and transformation of crystalline phase from monoclinic to cubic occurs, along with preferred (111) orientation and large grain as temperature increases. The results facilitate clear relationship between the characterizations of Y2O3 film and growth parameters, also, it can be realized that adjustment of optical constants of Y2O3 films in a large range having the aid of substrate temperature to obtain desirable composition and structure for optical applications. [Copyright &y& Elsevier]

Abstract: In this study, alumina thin films were deposited on Si (100) substrates by reactive magnetron sputtering in an Ar–O2 atmosphere. The resputtering technique without any separated ion source was applied, as well as various substrate biases and deposition temperatures. Suitable oxygen/argon gas flow rate ratio was obtained to deposit stoichiometric Al2O3 films. As investigated by grazing incidence X-ray diffraction (GIXRD) and nanohardness measurements, the amorphous characteristics and hardness values of alumina films aren''t altered with the various substrate biases up to −120V at the temperatures up to 600°C. The microstructure of alumina films with thin crystalline Al2O3 layer between the amorphous layers was achieved with the resputtering technique at elevated temperatures (≤300°C). This suggests that the reactive magnetron sputtering with the resputtering technique is a simple and effective method of preparing crystalline alumina films at relatively low temperature. The existence of thin crystalline Al2O3 layers between the amorphous layers makes the film harder than the amorphous films. In general, increasing the deposition temperature with the resputtering technique increased the hardness of the films, thus the crystalline-volume fraction of the films. However, the hardness was not a monotonic function of the deposition temperature. [Copyright &y& Elsevier]

Yttrium oxide films were prepared on silicon wafers by reactive magnetron sputtering at different oxygen flow rates to investigate the microstructure and optical properties for desirable planar optical waveguiding applications. Under the different conditions of target surface, the deposition rate, structure, and optical properties have great changes. The deposition rate increases to the maximum, and then monotonically decreases. Oxygen content in films increases and the composition of films transforms from stoichiometry to an oxygen-rich state. YO films grow with the (222) preferred growth orientation at low oxygen flow rate, and then turn into the (622) orientation; the microstructure evolves from crystal structure to amorphous state as oxygen flow rate increases from 2 to 12 sccm. Sufficient oxygen makes films low-order structure and oxygen-rich films have poor crystallinity. Very smooth film has been obtained at oxygen flow rate of 12 sccm. The refractive index can be greatly modulated by the oxygen-content factor. It is convincing that the controllable structure and optical properties of YO films can be achieved by adjustment the oxygen flow rate for desired optical design and applications. [ABSTRACT FROM AUTHOR]

Abstract: In order to take the tetrahedral amorphous carbon (ta-C) films as the high acoustic impedence layer in a Bragg reflector isolating acoustic wave from the substrate in solidly mounted resonator, the multilayer films consisting of sp2-rich layers and sp3-rich layers were deposited from a filtered cathodic vacuum arc by adjusting the substrate bias. The microstructure of the films was evaluated using a visible Raman spectroscopy. The stress was calculated according to the changed curvature of the coated and bare substrate. The hardness, modulus and scratching were measured using a nanoindenter. It has been shown that the multilayer structure maintaining high tetrahedral content, high hardness and high elastic modulus is still characterized with lower intrinsic stress and better adhesion. [Copyright &y& Elsevier]

Abstract: Yttrium oxide (Y2O3) is a promising ceramic material for electronic and optical applications due to its excellent properties. The purpose of this study is to characterize the effects of deposition parameters on the structure and composition of Y2O3 films. The films are grown on Si substrates by reactive magnetron sputtering at different substrate temperatures and oxygen pressures. The composition and structure of the films are studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. It is shown that the Y2O3 films deposited by reactive magnetron sputtering are mainly cubic phase and polycrystalline. The films are composed of Y–O, Y–O–Si, and Si–O bonds. Increasing substrate temperature induces the monoclinic to cubic phase transition and results in the formation of oxygen vacancies in the film. The preferred growth orientation of Y2O3 film is the (110) plane at low temperature, and it changes to the (111) plane at high temperature. The low temperature is preferable for the formation of Y–O bonds. The oxygen pressure influences on the concentration of Y–O bonds significantly. An optimal oxygen partial pressure for the formation of Y–O bonds exists during the film deposition. In addition, the deposited Y2O3 films exhibit excellent mechanical properties. [Copyright &y& Elsevier]

Abstract: We investigate the growth process and structural properties of phosphorus incorporated tetrahedral amorphous carbon (ta-C:P) films which are deposited at different substrate biases by filtered cathodic vacuum arc technique with PH3 as the dopant source. The films are characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy, Raman spectroscopy, residual stress measurement, UV/VIS/NIR absorption spectroscopy and temperature-dependent conductivity measurement. The atomic fraction of phosphorus in the films as a function of substrate bias is obtained by XPS analysis. The optimum bias for phosphorus incorporation is about −80V. Raman spectra show that the amorphous structures of all samples with atomic-scaled smooth surface are not remarkably changed when PH3 is implanted, but some small graphitic crystallites are formed. Moreover, phosphorus impurities and higher-energetic impinging ions are favorable for the clustering of sp2 sites dispersed in sp3 skeleton and increase the level of structural ordering for ta-C:P films, which further releases the compressive stress and enhances the conductivity of the films. Our analysis establishes an interrelationship between microstructure, stress state, electrical properties, and substrate bias, which helps to understand the deposition mechanism of ta-C:P films. [Copyright &y& Elsevier]

The microstructure and surface morphology of ta-C films deposited on p-type (1 0 0) single crystal silicon with the substrate negative bias varying from 0 to 2000 V by the filtered cathodic vacuum arc technology have been investigated by means of Raman spectroscopy and atomic force microscope. The optimal deposition process of sp3-rich ta-C films can be confirmed in light of the relations between the coupling coefficients or full-width at half-maximum and the substrate negative bias. The surfaces of these films are uniform and smooth and RMS surface roughness is less than 0.4 nm. At the lower energetic grades, the more the content of sp3 is in the film, the smoother the surface of the film is. The dependence of the surface morphology and the impinging energy of the species can be illustrated according to the subimplantation growth mechanism. Nevertheless at the high energetic grade, the impinging ions with appropriate energy sputter and smoothen the surface so that the roughness might be even lower than the one of the films with the richest sp3 component. [Copyright &y& Elsevier]

Thermal damage is one of the principle modes of wagon railway wheels. A new bainitic railway wheel steel with high thermal damage resistance and good combination of strength, plasticity, and toughness was developed. Microstructure and mechanical properties of the new steels in a tempered condition at different temperatures were examined. Microstructures were observed using scanning electron microscope and transmission electron microscope. Mechanical properties were evaluated by tensile, hardness, and Charpy impact tests with a simultaneous comparison to pearlitic railway wheel steel. The characteristic of retain austenite and V(C,N) were measured through X-ray diffractometry and energy disperse spectroscopy. The results indicate that this new bainitic wheel steel presents a submicron-sized carbide-free bainite morphology and preferable integrated mechanical properties when tempered at 280–360 °C. Precipitation strengthening plays an important role for the high strength, since a two-time-strengthening mechanism of the yield strength led by precipitation has been found at 280–360 and 480–560 °C, respectively. Compared with a pearlitic railway wheel steel, bainitic wheel steel tempered at 320 °C has a 10% higher yield strength, five times higher impact toughness, and much better thermal damage resistance, which is a promising railway wheel material for higher speed or heavier axle-load service conditions. [ABSTRACT FROM AUTHOR]

Highlights • Mode coupling vibration of thickness-extensional (TE) ZnO thin film resonator is studied based on exact dispersion curve. • Frequency spectra predicting the relation between coupling content and plate aspect ratios are obtained by using three different WBCs. • The desirable plate aspect ratios where TE mode weakly couples to spurious modes are located at the first flat area of frequency spectra. • Frequency spectra obtained by balance of high order stress are consistent with those obtained by Saint-Venant's principle quantitatively. • Frequency spectra firstly yielded by Hamilton principle give wider flat areas providing more structural parameter choices. Abstract In this paper, the mode coupling vibration of finite ZnO thin film resonator (FBAR) with its c-axis along the thickness direction operating at the thickness-extensional mode is studied. The dispersion curve of unbounded fully-electroded ZnO thin film indicates that the thickness-extensional mode couples to two unwanted spurious modes. Since the displacement solutions consisting of the sum of three mode branches in the dispersion curve have satisfied the differential equations and boundary conditions on the top and bottom surfaces exactly, the substitution of them into Hamilton principle as weak boundary condition (WBC) can give an integral boundary condition across plate thickness at the side edge of ZnO thin film resonator. Two other WBCs are also employed to study the same coupling problem to prove the validity of Hamilton principle. The frequency spectra obtained through all three WBCs indicate that the extent of mode couplings is sensitive to plate length/thickness ratios. The desirable values of plate aspect ratios where thickness-extensional mode weakly couples to two spurious modes are all located at the flat part of the obtained frequency spectra. Besides, the frequency spectra obtained through Hamilton principle include those obtained through other two WBCs because the mathematical expressions of Hamilton principle contain all terms in other two WBCs. The frequency spectra predicted by Hamilton principle have wider flat part than those from other WBCs providing more structural choices for device designers. These obtained results provide a significant guidance to the design and optimization of FBARs. Graphical abstract The above frequency spectra obtained through weak boundary conditions predict the relationship between the content of mode couplings and plate length/thickness ratio. The desirable values where the thickness-extensional mode dominates among considered vibration modes are located at the flat part of frequency spectra, which is preferred for good device performance. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract: Successful modification of stress and conductivity for tetrahedral amorphous carbon (ta-C) films is realized by phosphorus incorporation via filtered cathodic vacuum arc technique with PH3 as the impurity source. By establishing the structure as a function of phosphorus content, it is found that phosphorus fraction in phosphorus incorporated ta-C (ta-C:P) films increases with varying levels of PH3 from 3 to 30 sccm, and that all samples retain their amorphous structures without remarkable changes, just exhibiting the clustering of sp2 sites and the evolution of structural ordering. Furthermore, the addition of phosphorus causes the compressive stress relaxation in terms of the rearrangement in atomic bonding structures. The increased number of localized electronic π and π⁎ states as hopping sites after phosphorus incorporation results in several orders of magnitude increase in the conductivity, and the films represent the hopping conduction in band tail states in the temperature range of 293–463 K. However, more H induced by excessive PH3 may saturate some defects and compensate the hopping sites, leading to a slight drop in the conductivity. The nature of ta-C:P films as n-type semiconductors is proved from the features of rectifying current–voltage cures. [Copyright &y& Elsevier]

Abstract In p-type γ -CuI thin films synthesized by the iodination of Cu layers with iodine vapor, a frosted-glass-like appearance with a rough surface is usually obtained, which makes it difficult to apply the γ -CuI films to transparent electronics. This paper proposes an innovative method for the preparation of highly transparent p-type γ -CuI films. A chemical reaction between Cu thin films and iodine vapor, combined with the layer-by-layer process at a temperature between room temperature and 120 °C are found to result in highly transparent polycrystalline γ -CuI films. The root-mean-square roughness values of the γ -CuI films prepared by this method are 8.5–21.2 nm, which are smaller than those for the γ - CuI films synthesized by the conventional method. The microstructure and optoelectronic properties of the γ-CuI thin films are sensitive to the temperature of iodine vapor. A high transmittance (80%) of the film obtained at an iodine vapor temperature of 80 °C has a low resistivity of 5 × 10−2 Ω cm and high mobility of 8.7 cm2/Vs. Moreover, a boosted figure of merit is realized due to the simultaneously low resistivity and high transparency: its value jumps from ∼488 to ∼1630 MΩ−1. Graphical abstract Unlabelled Image Highlights • A traditional iodination reaction method combined with the layer-by-layer process. • Simultaneously high transmittance and low resistivity. • A boosted figure of merit is realized. [ABSTRACT FROM AUTHOR]

• Repeated temperature variations occurred between wheel tread and brake shoe. • Adverse microstructure evolutions were brought by the variations. • Retained austenite decomposed and cementite precipitated leading to cracks' creation. Several severe cracks were found in novel 20Mn2SiMoCuV bainite wheel tread after 100,000 km test running, which will significantly affect bainite wheel's service safety. The reason for cracks generation was investigated through microstructure observation and wheel/shoe contact analysis. Results showed that cracks were caused by microstructure evolutions resulting from temperature variations during quickly heating and cooling repeatedly in braking at contact interface of wheel tread and brake shoe. Temperature increased to above 500 °C at contact area will reduce the bainite wheel microstructure stability, leading to retained austenite decomposition to brittle martensite and cementite precipitation along grain boundary and lath boundary. Both above brittle martensite and cementite provided location for crack initiation and propagation. Therefore, some measures can be suggested to prevent initiation and propagation of cracks such as optimizing heat treatment process parameters to improve microstructure stability and adjusting matching of wheel tread/brake shoe to coordinate thermal conductivity. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of deposition conditions on the properties of yttrium oxide thin films. The paper focuses on the texture, optical and mechanical properties. With this objective, a series of yttrium oxide thin films with different thicknesses were deposited by direct current (DC) unbalanced reactive magnetron sputtering at high and low pumping speed. By changing the oxygen flow, depositions were performed in the three characteristic deposition modes for reactive magnetron sputtering, i.e., metallic, transition and poisoned mode. By using an oxygen flow directed to the substrate, full oxidation of the samples, as shown by X-ray photoelectron spectroscopy (XPS), in the three modes is obtained. Crystallographic characterization by X-ray diffraction (XRD) shows that films crystallize in the cubic phase with a strong (222) out-of-plane orientation at low oxygen flow. As the oxygen flow increases a mixture of cubic and monoclinic phase is obtained. In poisoned mode, the films consist of the cubic phase with preferred (420) orientation. Scanning electron microscopy (SEM) cross sections show, with increasing oxygen flow, a loss of the columnar structure. As the oxygen flow rates increase through the metallic, transition, and the poisoned mode, the grain size becomes gradually smaller. An overview diagram of all experimental results uncovers that the textural changes are closely linked to the oxygen partial pressure rather than the oxygen flow. The optical properties of films were investigated by spectroscopic ellipsometry (SE). The films with a columnar structure demonstrate superior hardness and modulus as well as the high plasticity. [ABSTRACT FROM AUTHOR]

• A 3D bi-network of GF and NDs in composites has been designed and fabricated. • Composites with a bi-network structure exhibited higher thermal conductivity. • The thermal conductivity enhancement efficiency can be maintained up to 74.33%. • FEA was carried out to confirm the heat transfer mechanism of the bi-networks. As thermal interface materials, polymers are limited by its low thermal conductivity. In this work, a three-dimensional bi-network structure consisting of chemical vapor deposition graphene foam and close-stacked nanodiamonds was constructed in epoxy matrix via a template method. The obtained composites exhibit interesting properties: significant thermal conductivity enhanced efficiency per unit of fillers (74.33%) based on pure epoxy matrix, and excellent electrical conductivity (0.256 S/cm) compared with epoxy matrix (4.58exp-14 S/cm). Finite Element Analysis based on the design of the dual networks was carried out to confirm the heat transfer mechanism, and it is proved that composites with GF/ND bi-network have a lower temperature gradient. That provides a novel insight of improvement method for thermal conductivity by construction of a three-dimension bi-network structure. [ABSTRACT FROM AUTHOR]