Characterization Of Topography Research Articles

Characterization and filtering of profile and areal surface topography by combining the discrete Legendre and cosine transforms

In the standardized processing of surface topography data, the form removal and filtering operations are clearly separated. This is reflected in the current ISO standards concerning profile surface texture and areal surface texture, the ISO 21920 and the ISO 25178 series respectively. When the scale-limited surface texture is significant compared to the form to be removed, for example with additive manufactured surfaces, the dependence of the surface Fourier spectrum on the removed form and orientation may become significant. This may lead to interaction between the form removal and filtering operations. To counter this interaction, in this paper, the lower-order discrete Legendre polynomials that describe the form are combined with cosine functions that describe the surface texture. This set of base functions is orthonormalized using a Gram-Schmidt procedure. This results in a set of orthonormal functions that allow an independent parameterization of both form and texture. The concept and the related theory are given and illustrated using examples of filtering profiles and areal topographies, description of cylinders and treatment of missing data. The examples show that the concept as presented in this paper is useful for filtering surfaces with a dominant form and can be used in the parametrization of surfaces and cylindrical geometries. Also, the methods presented here can be used for filtering and parametrization in the case of missing points in the data, actual holes in the profile or non-rectangular surfaces.

Fractal and statistical characterization of brushstroke on paintings

Identification of an individual artist’s touch on paintings is studied using surface metrology. Paintings’ topographies were measured using focus variation and stitching, creating 13 × 13 mm maps with 1 μm sampling intervals, and 169 megapixels, with a 10X objective lens. Topographic characterization parameters were analyzed for their ability to differentiate different painters’ renderings. Statistical treatments from data mining were used to discriminate, by optimization, multiscale topographic signatures characterized by a multitude of areal texture parameters. It appears that a fractal dimension can define 3 characteristic scale ranges. One from 3 to 70 μm corresponds to brushstroke details. Another, from 70 to 700 μm, corresponds to the topography of the material of the canvas fabric. Finally, scales greater than 700 μm correspond to undulations of the canvas. For scales less than 50 μm, the fractal structure of the topography left by brushstrokes follows a power law characterized by the slopes of the topography. The topography of the clouds painted on the canvas has an Sdq (topographic slopes) increasing with the clarity of the clouds at scales of 3–500 μm. According to the Torrance-Sparrow theory, the higher the Sdq, the more diffuse the light on the surface. The painter therefore wanted to show, by his brushstroke, that the light clouds diffuse more light giving an impression of local brightness. This study is confirmed by the analysis of the painting of Max Savy, a French painter from Carcassonne (1918–2009), which was measured with a white light interferometer Zygo NewView 7300, a X100 objective lens giving a 517 μm × 517 μm stitched surface, with a sampling interval of 0.109 μm. The box-counting method for estimating the fractal dimension of the topography of an oil painting appears optimal by the fact that it morphologically integrates scale variations of the local slopes of the surface morphology. This method thus characterizes the multiscale aspects, as well as the scale changes, of the topography.

Reduction in Errors in Roughness Evaluation with an Accurate Definition of the S-L Surface

Characterization of surface topography, roughly divided into measurement and data analysis, can be valuable in the process of validation of the tribological performance of machined parts. Surface topography, especially the roughness, can respond straightly to the machining process and, in some cases, is defined as a fingerprint of the manufacturing. When considering the high precision of surface topography studies, the definition of both S-surface and L-surface can drive many errors that influence the analysis of the accuracy of the manufacturing process. Even if precise measuring equipment (device and method) is provided but received data are processed erroneously, the precision is still lost. From that matter, the precise definition of the S-L surface can be valuable in the roughness evaluation allowing a reduction in the rejection of properly made parts. In this paper, it was proposed how to select an appropriate procedure for the removal of the L- and S- components from the raw measured data. Various types of surface topographies were considered, e.g., plateau-honed (some with burnished oil pockets), turned, milled, ground, laser-textured, ceramic, composite, and, generally, isotropic. They were measured with different (stylus and optical) methods, respectively, and parameters from the ISO 25178 standard were also taken into consideration. It was found that commonly used and available commercial software methods can be valuable and especially helpful in the precise definition of the S-L surface; respectively, its usage requires an appropriate response (knowledge) from the users.

Surface Modification of Fluorine‐Doped Tin Oxide Thin Films Using Femtosecond Direct Laser Interference Patterning: A Study of the Optoelectronic Performance

Transparent conductive oxides (TCOs) are used in solar cells not only to extract photogenerated carriers but also to allow sunlight to reach the photoactive material. Therefore, controlling the electrical and optical properties of such oxides is crucial for the optimization of the efficiency of solar cells. Herein, direct laser interference patterning (DLIP) method is used to control the surface morphology, optical and electrical properties of fluorine‐doped tin oxide (FTO) by applying femtosecond laser pulses. The topography characterization reveals periodic line‐like microstructures with a period of 3.0 μm and average heights between 20 and 185 nm, depending on the applied laser fluence levels. Laser‐induced periodic surface structures are observed on the valleys of the texture aligned perpendicularly to the laser radiation polarization. A relative increase in the average total and diffuse optical transmittance up to 5% and 500%, respectively, is obtained in the 400–800 nm spectral range as a consequence of the generated micro‐ and nanostructures. Calculations of two figures of merit suggest that the texturing of FTO might enhance the efficiency of solar cells, in particular dye‐sensitized (DSSCs). The findings of this study confirm that DLIP is a convenient technique for structuring electrodes for highly efficient optoelectronic devices.

Surface characterization and analysis of textured injection moulded PC-ABS automotive interior components

Automotive interior components are produced by injection moulding due to its cost effectiveness in mass production. The surfaces of these components are textured to control the appearance and other surface functional properties such as wear and scratch resistance. Key challenges lie in replicating the features of mould tool with high aspect ratio which are influenced by the polymer and large number of process variables. Hence, to control the aesthetic properties, it is important to improve the understanding of the replication of textured surfaces and its relationship with measured gloss. In this study, the surface topography of PC-ABS samples is investigated using coherence scanning interferometry. Replication of two types- coarse and fine grain surface texture are investigated to identify the effects of tool temperature, injection speed and holding pressure. Areal surface parameters are scrutinized for the quantitative characterization and discrimination of study samples surface topographies. The correlations between process parameters, measured gloss and areal surface parameters are discussed. The results show significant influence of process variables on the replication of surface topography and measured gloss. The grain pattern governed the set of surface parameters selected and the variation in gloss. The process variables are observed to influence different region or distribution of specific surface features represented by surface parameters.

High-Translucency Zirconia Following Chemical Vapor Deposition with SiH4: Evidence of Surface Modifications and Improved Bonding.

To evaluate the effect of plasma-enhanced chemical vapor deposition (PECVD) with silicon hydride (SiH4) at different times on HT-zirconia surface characteristics and bonding of composite cement before and after thermocycling. Blocks of HT zirconia were obtained, polished, sintered and divided into five groups, according to PECVD time (n = 31): Zr-30 (30 s), Zr-60 (60 s), Zr-120 (120 s) and Zr-300 (300 s). The control group (Zr-0) did not receive PECVD. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS) in conjunction with field-emission scanning electron microscopy (FE-SEM), x-ray photoelectron spectroscopy (XPS), goniometry, and profilometry tests were used for chemical and topographic characterization. Monobond N silane (Ivoclar Vivadent) was applied to the surface, and a cylinder of composite cement (Variolink N) was made (3 x 3 mm). Half of the specimens of each group were stored for 24 h or subjected to thermocycling (6 x 103 cycles). A shear bond strength (SBS) test was performed. Results were subjected to one-way ANOVA and Tukey's tests (α = 0.05). For experimental groups, XPS showed that formation of Si-O bonds contributed to increased surface free energy (SFE). FE-SEM and EDS showed that the longer the deposition time, the greater the amount of silicon on the surface. Zr-60 and Zr-300 presented higher and lower surface roughnesses, respectively. The silicon penetrated the microstructure, causing higher stress concentrations. The bond strength to composite cement was improved after all PECVD deposition times. The PECVD technique with SiH4, associated with chemical treatment with primer based on silane methacrylate, is a solely chemical surface treatment capable of maintaining bonding between composite cement and HT zirconia.

Uncertainty budget of a large-range nanopositioning platform based on Monte Carlo simulation

The objective of precision systems design is to obtain machines with very high and totally predictable work-zone accuracies. In already functional systems, where the errors can be measured, this is achieved by error correction and compensation. The aim of this work is to propose an uncertainty budget methodology to obtain the final measuring uncertainty of precise measuring systems, after error compensation. The case study is a nanopositioning platform, referred as NanoPla, with a confocal sensor integrated as measuring instrument. The NanoPla performs precise positioning in a large range of 50 mm × 50 mm, and its target is surface topography characterization, at a submicrometre scale. After performing the uncertainty budget of the NanoPla, Monte Carlo method is used to obtain the final measuring uncertainty along the whole NanoPla working range, considering all the casuistry. By studying the results, the authors are able to propose solutions to minimize the final measuring uncertainty.

A 3D surface nanomechanical property mapping method with a magnetic-drive orthogonal cantilever probe.

Traditional force-distance curve based atomic force microscopy (FD-AFM) is limited to two-dimensional (2D) surface characterization, making the in situ mapping of three-dimensional (3D) surface nanomechanical properties (SNMP) challenging. This paper presents a multimode 3D FD-AFM based on a magnetic-drive orthogonal cantilever probe (MD-OCP) that can achieve SNMP imaging of 3D micro-nano structures with surface contour fluctuations reaching or exceeding several microns. Bending, torsion and vector tracking modes are integrated into this method for a 2D horizontal surface, 2D sidewall, and 3D surface mapping, respectively. The MD-OCP consists of a horizontal cantilever, a vertical cantilever with a protruding tip, and a magnetized bead. It can be utilized in the detection of deep trench and dense microarray units. The force analysis during 3D SNMP measurement is performed through mathematical derivation, which shows a clear relationship between effective indentation force, friction, and total tip-sample interactions. Single-point SNMP evaluation, discrete 2D SNMP imaging, and continuous omnidirectional 3D SNMP mapping of a 3D microarray unit verify the accurate and comprehensive measurement abilities of the reported method in its bending, torsion, and vector tracking modes. The experimental results demonstrate that this method can achieve excellent 3D quantitative characterization of topography and SNMP, including critical dimensions, adhesion, Young's modulus, stiffness, and energy dissipation, along a 3D device surface. This novel 3D FD-AFM technique has many potential applications in the further exploration of 3D micro-nano devices.

Experimental estimation of thermal contact conductance across pressed copper–copper contacts at cryogenic-temperatures

• Present experimental work presents a valuable database of TCC in cryogenics. • Reports systematic estimates of TCC for copper contacts on which data are scarce. • Effects of broad temperature, pressure, roughness on TCC are covered in vacuum. • Anomalous TCC trend at low temperature is correlated to thermo-physical properties. • Proposes generalized empirical correlations of TCC with temperature and pressure. The accurate estimation of thermal contact conductance (TCC) is a fundamental need towards the optimal design of any cryogen-free conduction-based cooling systems, which routinely utilizes mechanically pressed components of bare copper to form the heat conduction path. There exists a dearth of databases and reliable correlation for TCC between bare copper contacts for such applications. Present work is an experimental study, which has been performed systematically to address the requirement of design engineers for such applications. A novel experimental setup has been made to carry out axial heat transfer experiments between copper contacts under a varying set of temperature and pressure parameters of 50 to 300 K and 0.5 to 8 MPa, respectively. The surface roughness at the contact between copper specimens varied between 0.8 and 10 μ m . The TCC has shown a non-linear variation with temperature in the 50 to 300 K. The temperature-dependent thermophysical properties, nature of asperities deformation, and surface topography characterization were considered in analyzing the results. This effectively helps in dealing with the coupled nature of the TCC problem and thus enhances the accuracy, reliability, and scope of the present study performed at sub-ambient ranges under a varying set of selected parameters. The TCC results have also been compared with theoretical model predictions, and the improvements needed in them are highlighted. Finally, an empirical correlation of the reduced dimensionless TCC with dimensionless temperature and dimensionless pressure has been proposed, which covers a wide deformation range of the asperities, temperature, and surface roughness than existing models in the literature. The proposed correlation consistently explains the non-linear dependence of TCC with temperature and pressure and provides a direct means to the design engineers for the TCC estimation at cryogenic temperatures.

Estimation Method of Ideal Fractal Parameters for Multi-Scale Measurement of Polished Surface Topography

A surface topography characterization parameter system based on fractal parameters has been established, and several estimation methods for these fractal parameters have been suggested accordingly. Since scale dependence exists in these conventional methods, it is necessary to find an estimation method for characterization parameters with uniqueness. An estimation method for ideal fractal parameters for multi-scale measurement of polished surface topography is proposed in this study. Polished surfaces of two materials, WC-Ni and 9Cr18Mo, are measured under multi-scale for frequency component analysis. This study proposes an estimation method for ideal fractal parameters based on a modified determination method for the scale-free region and the decomposition of frequency components into three classifications. The reasonable results verify the existence of ideal fractal parameters: for the WC-Ni surface, ideal fractal dimension D = 1.3 and scale coefficient G = 2.23×1020 μm; for the 9Cr18Mo surface, ideal fractal dimension D = 1.2 and scale coefficient G = 3.33×1033 μm. Additionally, it is revealed that the scale-dependent components conform to the same regulation on the same instrument by comparing the results of two materials. The conclusions of this study are expected to support tribology research and mechanical engineering related to surface topography.

Topographical Characterization of the Young, Healthy Human Femoral Medial Condyle.

The medial femoral condyle of the knee exhibits some of the highest incidences of chondral degeneration. However, a dearth of healthy human tissues has rendered it difficult to ascertain whether cartilage in this compartment possesses properties that predispose it to injuries. Assessment of young, healthy tissue would be most representative of the tissue's intrinsic properties. This work examined the topographical differences in tribological, tensile, and compressive properties of young (n = 5, 26.2 ± 5.6 years old), healthy, human medial femoral condyles, obtained from viable allograft specimens. Corresponding to clinical incidences of pathology, it was hypothesized that the lowest mechanical properties would be found in the posterior region of the medial condyle, and that tissue composition would correspond to the established structure-function relationships of cartilage. Young's modulus, ultimate tensile strength, aggregate modulus, and shear modulus in the posterior region were 1.0-, 2.8-, 1.1-, and 1.0-fold less than the values in the anterior region, respectively. Surprisingly, although glycosaminoglycan content is thought to correlate with compressive properties, in this study, the aggregate and shear moduli correlated more robustly to the amount of pyridinoline crosslinks per collagen. Also, the coefficient of friction was anisotropic and ranged 0.22-0.26 throughout the condyle. This work showed that the posteromedial condyle displays lower tensile and compressive properties, which correlate to collagen crosslinks and may play a role in this region's predisposition to injuries. Furthermore, new structure-function relationships may need to be developed to account for the role of collagen crosslinks in compressive properties.

Simultaneous local spectral, colorimetric, and topographic characterization of laser-induced colored stainless steel with low coherence interference microscopy

Laser marking is a well-established advanced technology for changing the color properties of an object. The spectral response or color information induced by the laser is generally measured with a spectrometer or an ellipsometer. These instruments only provide an average response over an area of a few thousand µm² at best. However, color laser marking is a local process that modifies the structure of the metal at a micrometer scale. In this work, we propose a technique for extracting simultaneously the 3D topography and the 2D spectral response from 460 nm to 900 nm, providing color information over this spectral range, in a single measurement. The proposed technique uses a low-coherence interference microscope to provide a laterally diffraction-limited measurement (∼1 µm) over a large field of view (up to 200 × 200 µm²) with the advantages of being rapid (<3 min) and contactless. Through the Fourier Transform analysis of the measured interferogram, a multimodal characterization (quantitative spectra, color (xy) and topography) of reflective samples can be achieved. Results obtained on laser-induced colored stainless steel are reported.

Feature-Based Characterisation of Turned Surface Topography with Suppression of High-Frequency Measurement Errors.

Errors that occur when surface topography is measured and analysed can be classified depending on the type of surface studied. Many types of surface topographies are considered when frequency-based errors are studied. However, turned surface topography is not comprehensively studied when data processing errors caused by false estimation (definition and suppression) of selected surface features (form or noise) are analysed. In the present work, the effects of the application of various methods (regular Gaussian regression, robust Gaussian regression, and spline and fast Fourier Transform filters) for the suppression of high-frequency measurement noise from the raw measured data of turned surface topography are presented and compared. The influence and usage of commonly used available commercial software, e.g., autocorrelation function, power spectral density, and texture direction, which function on the values of areal surface topography parameters from selected (ISO 25178) standards, are also introduced. Analysed surfaces were measured with a stylus or via non-contact (optical-white light interferometry) methods. It was found that the characterisation of surface topography, based on the analysis of selected features, can be crucial in reducing measurement and data analysis errors when various filters are applied. Moreover, the application of common functions can be advantageous when feature-based studies are proposed for both profile and areal data processing.

Ferroso-ferric oxide (Fe3O4) embedded g-C3N4 nanocomposite sensor fabricated by photolithographic technique for environmental pollutant gas sensing and relative humidity characteristics

• The effective nanocomposite C 3 N 4 /Fe 3 O 4 fabricated by cost effective co-precipitation method. • The photolithographic technique involving 40s size, having mesh number 355 was utilized to fabricate film sensor. • Mechanism for testes gases CO and NO 2 is established. • Comparative reports of bare Fe 3 O 4 and modified Fe 3 O 4. • Synergetic effect of C 3 N 4 and Fe 3 O 4 , makes modified sensor as an effective sensor for tested gases. The research portrayed in the present investigation of gas sensing and humidity sensing characteristics of the screen printed thick film sensors. The materials bare Fe 3 O 4 and C 3 N 4 /Fe 3 O 4 were fabricated by conventional co-precipitation and heat treatment method. The prepared materials were characterized of series of nanomaterial characterization techniques such as x-ray diffraction (XRD) technique to confirm structural parameters, scanning electron microscopy (SEM) for topographic and surface characterization of the fabricated materials, while energy dispersive spectroscopy (EDS) was utilized to confirm elemental composition. High resolution transmission electron microscopy (HR-TEM) was employed to confirm the lattice parameters of the fabricated materials. The magnetic properties were investigated from vibrating sample magnetometer (VSM), additionally the elemental composition and chemical states of the prepared materials was confirmed from x-ray photoelectron spectroscopy (XPS) technique. The thick film sensors of the fabricated materials Fe 3 O 4 and C 3 N 4 /Fe 3 O 4 were prepared by standard photolithographic technique. The thick film sensors were employed for gas sensing characteristics of the gases such as CO, NO 2 , CO 2 ,tolune vapours (TV) and dichloromethanne vapours (DCM). Out of that the C 3 N 4 /Fe 3 O 4 sensor showed excellent gas response of 85.25% for CO and 75.80 % for TV at 1000 ppm gas concentration. The overall gas sensing properties such as selectivity, response recovery and temperature effects and ppm variation of the gases were investigated in detailed. Additionally, the fabricated sensors were also explorated for humidity sensing properties. As per the data of gas sensing, the modified C 3 N 4 /Fe 3 O 4 is observed to be promising and stable sensor to sense the CO and TV vapors at moderate temperature and humid conditions.

Material extrusion-based additive manufacturing of polyetheretherketone cranial implants: Mechanical performance and print quality

Polyetheretherketone (PEEK) is considered a ‘gold-standard’ material choice for cranial bone reconstruction. The introduction of additive manufacturing (AM) into the pipeline for patient specific cranial implant (PSCI) fabrication could accelerate supply chain needs and improve patient outcomes. Fused filament fabrication (FFF), a material extrusion-based technology, is a much-researched process due to its accessibility and ease of use. However, the quality of PEEK processed by FFF is highly affected by the applied printing profile. Therefore, in this study, the effects of printing parameters such as build orientation and air flow temperature on mechanical performance (cyclic and impact tests) and implant quality (characterisation of surface topography, discoloration and crystallinity) were analysed and compared with a commercial milled PEEK implant. It has been found that horizontally printed implants show higher mechanical integrity compared to implants printed upright or tilted by 45°, but obtain lower surface quality. In addition, lower air flow temperatures lead to strong implant discolorations due to high amounts of amorphousness, which further result in high absorbed energies during impact as well as large deformations until complete failure. The best results from a mechanical point of view were achieved with PSCIs printed at a build orientation of 180°, an air flow temperature of 210 °C, a shell number of 3, a layer height of 0.15 mm, a printing speed of 50 mm/min, a rectilinear ±45° infill pattern and an implant thickness of 5 mm. However, the surface quality of implants produced this way is not completely satisfactory, and the arrangement of the support structures must be further improved.

Comparison of 316L and Ti6Al4V biomaterial coated by ZrCu-based thin films metallic glasses: Structure, morphology, wettability, protein adsorption, corrosion resistance, biomineralization

In this study, ZrCu-based thin films were obtained using a PVD-cathodic arc technique, aiming to improve the surface properties of 316L stainless steel and Ti6Al4V implant materials. By combining their superior mechanical properties with the corrosion resistance of amorphous metallic glasses, the obtained ZrCu-based layers could be qualified as candidates for medical applications. Ca, Mo, Mg, Si and Sr additions to ZrCu structure were considered and the resulting ternary systems were subjected to a detailed investigation. Potentiodynamic polarization was employed to assess corrosion kinetics and their overall electrochemical behaviour after 1 h immersion in SBF solution, the experiments being conducted at human body temperature (37.0 ± 0.5 °C). Additionally, electrochemical impedance spectroscopy (EIS) was carried out for detecting fast changes of the system under investigation and to reveal in depth information related to coating/substrate–solution interface. For morphology and topography characterization before and after electrochemical tests, scanning electron microscopy was used. The results showed a dependence of mechanical properties on the used substrate: the hardness was higher and a better adhesion was achieved when Ti6Al4V was used. Immersion tests were also influenced by the substrate related outcome, since the coatings deposited on 316L substrate showed a significant degradation compared to those on Ti6Al4V substrate, where the apatite structure formed on the surface was more evident. ToF-SIMS analysis revealed protein adsorption enhanced for all applied coatings.

Boron- and Boric Acid-Treated Titanium Implant Surfaces in Sheep Tibia: A Histologic, Histomorphometric and Mechanical Study.

The aim of this study was to compare the topographical, chemical and osseointegration characteristics of sandblasting and acid-etching (SLA) surfaces and dental implants treated by boron compounds. Titanium (Ti) disks (n = 20) were modified using boron (B) and boric acid (H3BO3) and then compared with the conventional SLA surface via surface topographic characterizations. Dental implants (3.5 mm in diameter and 8 mm in length) with the experimental surfaces (n = 96) were inserted into the tibias of six sheep, which were left to heal for 3 and 7 weeks. Histologic, histomorphometric (bone-implant contact (BIC%)) and mechanical tests (removal torque value (RTV)) were performed. The boron-coated surface (BC group) was smoother (Rz: 4.51 μm ± 0.13) than the SLA (5.86 μm ± 0.80) and the SLA-B (5.75 μm ± 0.64) groups (p = 0.033). After 3 weeks, the highest mean RTV was found in the SLA group (37 N/cm ± 2.87), and the difference compared with the BC group (30 N/cm ± 2.60) was statistically significant (p = 0.004). After 7 weeks, the mean RTV was &gt;80 N/cm in all groups; the highest was measured in the H3BO3-treated (BS) group (89 N/cm ± 1.53) (p &lt; 0.0001). No statistically significant differences were found in the BIC%s during both healing periods between the groups. H3BO3 seems to be a promising medium for dental implant osseointegration.

Surface periodicity index ([formula omitted]): A measure of periodicity of surface topography

The periodicity of surface features generated by various manufacturing processes plays a vital role in the functionality of the parts. Quantifying the periodicity of such surfaces is essential, which is not effectively captured by the existing surface topography characterization parameter. In this work, a new characterization parameter called surface periodicity index, SPI, is defined to identify and quantify the periodicity of a surface. It also indicates the significance of a periodic feature shrouded by a broad range of aperiodic features on a surface. SPI, established using the power spectral density, measures the energy of the periodic features in the context of the surface. Simulated periodic and aperiodic surfaces are used to demonstrate SPI. Finally, the utility of SPI is demonstrated with a case study of pulsed laser micro polishing. It will be shown that the parameter can also be used to distinguish different process regimes and for process design.

Investigation of photocatalytic performance of titania based hybrid nanocomposite structure for dilapidation of organic contaminants.

This research paper attempt to provide the photocatalytic performance of nitrogen ion (N+) entrenched anodized Ti with hydroxyapatite hybrid nano-sctructure meant for dilapidation of organic contaminant from the environment. The N+ was entrenched at 70keV with varying doses (1×1016, 5×1016, 1×1017 and 2.5×1017N+/cm2) into anodized Ti surface. Functional groups, phase structure, topographic and morphologic characterizations of the synthesized hybrid nano-sctructure were analyzed using Infra Red Spectroscopy, X-ray diffraction and Microscopic techniques, respectively. Wettability of the specimens was found out using contact angle measurements. The anodized Ti specimens without N+ have exhibited less surface energy than the specimens with N+. Porous shell gets smoothened after the entrenchment of N+. Compared to all the doses of nitrogen implantation, better performance was observed for 5×1016N+/cm2 dose. Moreover, the samples with N+ showed better charge transfer resistance indicating enhanced photocatalytic performance of N+ entrenched titania than other samples.

Supplementary motor area driving changes of structural brain network in blepharospasm.

Blepharospasm is traditionally thought to be a movement disorder that results from basal ganglia dysfunction. Recently, accumulating morphometric studies have revealed structural alterations outside the basal ganglia, such as in the brainstem, cerebellum and sensorimotor cortex, suggesting that blepharospasm may result from network disorders. However, the temporal and causal relationships between structural alterations and whether there are disease duration-related hierarchical structural changes in these patients remain largely unknown. Structural MRI was performed in 62 patients with blepharospasm, 62 patients with hemifacial spasm and 62 healthy controls to assess the structural alterations using voxel-based morphology and structural covariance networks. The use of the causal structural covariance network, modularity analysis and functional decoding were subsequently performed to map the causal effect of grey matter change pattern, hierarchical topography and functional characterizations of the structural network throughout the disease duration of blepharospasm. Greater grey matter volume in the left and right supplementary motor areas was identified in patients with blepharospasm compared to that in patients with hemifacial spasm and healthy controls, whereas no significant difference was identified between patients with hemifacial spasm and healthy controls. In addition, increased grey matter volume covariance between the right supplementary motor area and right brainstem, left superior frontal gyrus, left supplementary motor area and left paracentral gyrus was found in patients with blepharospasm compared to healthy controls. Further causal structural covariance network, modularity analysis and functional decoding showed that the right supplementary motor area served as a driving core in patients with blepharospasm, extending greater grey matter volume to areas in the cortico-basal ganglia-brainstem motor pathway and cortical regions in the vision-motor integration pathway. Taken together, our results suggest that the right supplementary motor area is an early and important pathologically impaired region in patients with blepharospasm. With a longer duration of blepharospasm, increased grey matter volume extends from the right supplementary motor area to the cortico-basal ganglia motor and visual-motor integration pathways, showing a hierarchy of structural abnormalities in the disease progression of blepharospasm, which provides novel evidence to support the notion that blepharospasm may arise from network disorders and is associated with a wide range of grey matter abnormalities.