Surface Morphology Research Articles

Investigation of effective parameters on Fe/Ta thin films by plasma focus device: number of shots and distance from tip anode

This experimental investigation is the first to generate a surface iron-tantalum (Fe/Ta) alloy as a sublayer-layer using a plasma focus device. Examining how ion beams from a plasma focus device alloy iron and tantalum with varying melting points is one of the key objectives of this study. Fe/Ta thin film nanostructure and surface morphology were also examined. The distance from the tip anode and the varied number of shots are the experimental variables. Although tantalum's melting point (3020 ∘C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ{\\rm C}$$\\end{document}) is generally known to be near to that of iron (2862 ∘C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ{\\rm C}$$\\end{document}), it is possible that iron vaporizes and partial alloying of iron with tantalum occurs before tantalum reaches its melting point. Fe/Ta thin film identification techniques include scanning electron microscopy, mapping of cross-section, energy dispersive X-ray spectroscopy, and X-ray diffraction pattern. Additionally, the composition of multilayer structures is examined using EDS. In conclusion, the results of the X-ray diffraction pattern showed that the number of shots had a significant impact on the residual strain degree of the thin films that were deposited. Furthermore, structures made of FeTa and Fe2Ta were produced. Additionally, photos from scanning electron microscopy and cross-section mapping verify that the sample with five shots at an 8 cm distance from the tip anode formed a uniform Fe/Ta alloy structure. The sample with five shots at a distance of 4 cm from the tip anode formed micro-island structures, as seen by scanning electron microscopy, with decreasing distance. Furthermore, depth elemental distribution revealed that the optimal depth of penetration in a homogenous material to develop alloying is best determined by number of PF shots.

Bio‐Based Foams to Function as Future Plastic Substitutes by Biomimicry: Inducing Hydrophobicity with Lignin

To replace common plastics, bio‐based alternatives are needed. Cellulose foams, as plant‐based materials, are the most attractive solution, being often biodegradable and inexpensive and having the potential for distributed production. Cellulose and its derivatives, as raw materials, present a fundamental challenge, as they are hydrophilic. Herein, this problem is solved by drawing inspiration from the hydrophobic barrier that lignin creates in wood and applying lignin to methylcellulose (MC) foams. The lignin (0.0–1.0 wt% being the range studied here) is applied directly to the suspension consisting of water and MC (1.8 wt%), which is then foamed and solidified to a dry 3D porous structure. By comparing different types of lignin and the resulting surface morphologies, it is shown that organosolv lignin (OL) most strongly self‐assembles to the air–foam interfaces, achieving area fractions up to 27%. Using different concentrations of OL, how hydrophobicity—described by the initial water contact angle and its time evolution—increases with increasing lignin concentration is then shown. Thus, significantly increased water resistance (up to 91 times higher compared to the pure MC foam), a crucial property for developing novel bio‐based materials that can compete with traditional plastics, is able to be achieved.

Surface morphology of 3C–SiC layers grown on 4H–SiC substrates using TCS as silicon precursor

The hetero-epitaxial growth of 3C–SiC layers on on-axis 4H–SiC substrates has been demonstrated in a hot-wall CVD reactor using trichlorosilane and ethylene as precursors. The additional chlorine is supplied by hydrogen chloride for variation of Cl/Si ratio. The influence of temperature, C/Si ratio and Cl/Si ratio process parameters on the morphology is studied. Double-position-boundaries free 3C–SiC epitaxial layers have been successfully grown at the optimized condition, which is at a temperature of 1340 °C, with C/Si = 0.6 and Cl/Si = 6 using a carbon-rich pretreatment. Low temperature near bandgap photoluminescence shows a good optical property of the obtained 3C–SiC epitaxial layers. Compared to the standard chemistry, a higher growth rate of 12 μm/h could be achieved by utilizing the chlorinated precursors. This study provides a feasible way to grow double-position-boundaries free 3C–SiC epitaxial layers using TCS as silicon precursor.

Molecular engineering controlled electric-optical performance of polymer dispersed liquid crystals

ABSTRACT In this work, the methods of doping different fluorine-containing monomers and fluorine-containing nanoparticles into the mixture were adopted to boost the electro-optical performance of PDLC films. The electro-optical measurements indicate the improved electro-optical performance of PDLCs through the introduction of MX-3 monomer, and the corresponded SEM results demonstrate the successful adjustment of surface morphology. Further doping F-Si@SiO2 nanoparticles into MX-3 monomer-modified PDLC system, the Vth and Vsat values are greatly reduced and reach lowest when F-Si@SiO2 content is 5 wt.%. The enhanced electro-optical property is due to the combined control of fluorine-containing MX-3 monomer and F-Si@SiO2 nanoparticles, the fluorine functional group can promote the uniform dispersion of nanoparticles; the existence of F-Si@SiO2 nanoparticles can regulate the anchoring effect on liquid crystal molecules in the polymer matrix, thus electric-optic characteristics of the PDLC materials are greatly enhanced.

Microscopic and Color Changes in Direct Dental Restorative Composite Resins upon Immersion in Beverages: Characterization by Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS).

This study aimed to evaluate the staining sensitivity and surface changes in recent composite resins (Herculite Ultra XRV (Kerr, Bolzano, Italy), G-ænial A'CHORD (GC Corp, Tokyo, Japan), and Omnichroma (Yamaguchi, Japan)) when exposed to common beverages such as coffee, red wine, and Coca-Cola. A total of 60 disk-shaped specimens were prepared from three different resin composites (n = 20 each). The specimens were exposed to coffee, red wine, and Coca-Cola for 10 days. Color measurements were taken using a spectrophotometer, and surface morphology and elemental composition were analyzed using SEM and EDS. The SEM and EDS analyses revealed significant changes in the surface morphology and elemental composition of the composites after immersion. Coffee and wine caused significant surface degradation, whereas Coca-Cola resulted in the greatest degree of surface and elemental variations. Color changes (ΔE = 4 ± 0.52) were most notable in Coca-Cola for Herculite Ultra XRV (Kerr, Italy), in red wine for G-ænial A'CHORD (GC Corp, Japan) (ΔE = 12.51 ± 0.38), and in coffee for Omnichroma (Yamaguchi, Japan) (ΔE = 10.85 ± 1.03). The tested beverages significantly affected both the surface condition and the chemical composition of the resin at the surface level. These findings highlight the importance of understanding the effects of common dietary beverages on dental composites.

Study on dynamic mechanical properties and microscopic damage mechanisms of granite after dynamic triaxial compression and thermal treatment

As underground mining operations gradually extend deeper, the conditions for orebody occurrence become increasingly complex, and various geological disasters occur frequently. Rock masses are prone to different degrees and types of damage, making it impractical to continue using intact rock as a reference. To study the dynamic mechanical properties of damaged rock under actual conditions, this study subjected granite samples to impact and high-temperature damage. Detailed observations were made of the samples' surface morphology and microstructure before and after damage, and the patterns of damage changes were investigated. Subsequently, uniaxial compression tests at different loading rates were conducted on the damaged samples. By calculating the loading rate effect sensitivity, it was found that as the damage increased, the rate effect gradually diminished. In addition, this study also summarized the influence of damage and loading rate on the macroscopic failure characteristics of the samples. The novelty of this study lies in focusing on damaged rock, which more closely resembles the actual rock conditions encountered in most underground mining operations today. This research can provide a reference for stability assessment and safe construction in deep mining rock engineering and offers important insights into the feasibility of non-explosive extraction of damaged rock.

Pentahomoserine functionalized graphene oxide decorated polyamide thin film for enhanced separation of green tea polyphenols

The isolation of valuable compounds from the byproducts of food processing industries presents a significant contemporary challenge. Thin film nanocomposite (TFN) membranes have been identified as potential media for separating bioactive compounds. In this work, pentahomoserine functionalized graphene oxide (FGO) based TFN membranes were prepared for the effective separation of tea polyphenols epigallocatechin (EGC) and epigallocatechin gallate (EGCG). The nanocomposite selective polyamide (PA) layer was prepared through the dispersion of FGO in an aqueous monomer solution. The prepared membranes possess high average surface roughness with improved hydrophilicity and thermal stability. Additionally, FGO membranes contain more hydroxyl or carboxyl groups with cross-linked PA layer through interfacial polymerization (IP) process. Moreover, FGO membranes featured increased hydroxyl or carboxyl groups, facilitating cross-linking with the PA layer via intermolecular forces. The effects of amine functionality on the membrane characteristics such as surface morphology, roughness and hydrophilicity were also investigated. Remarkably, the membranes demonstrated rejection efficiency of 96.3% towards polyphenols. Furthermore, comprehensive assessments of reusability performance of the membrane highlighted their potential for industrial applications. This study provides valuable insights into the fabrication of highly efficient TFN membranes for biomolecule separation across diverse technological domains.

Influence of Graphite and Zirconia Addition on the Tribological Properties of Plasma-Sprayed Alumina Coatings

Al2O3, Al2O3-graphite and Al2O3-ZrO2 coatings were formed on the C45 steel rolls using atmospheric plasma spraying. The influence of graphite and zirconia addition on the surface morphology, phase composition and tribological properties under dry sliding conditions using 30 N load were analyzed. It was found that the addition of graphite or ZrO2 slightly affected the fraction of the α-Al2O3 and γ-Al2O3 phases in the alumina coatings. The highest mass loss rate (~8.84 × 10−4 g/s) was obtained for the friction pair of C45 steel roll and steel plate. The friction coefficient of the Al2O3-graphite coating was slightly lower (up to 7%) compared to the coating of Al2O3-ZrO2. However, the friction pair of Al2O3-ZrO2 coating and steel plate demonstrated the highest wear resistance under dry sliding conditions. The increase in the wear resistance of the Al2O3-graphite and Al2O3-ZrO2 coatings is due to the formation of tribofilm in the sliding contact zone.

Bacteria-Derived Cellulose Membranes Modified with Graphene Oxide-Silver Nanoparticles for Accelerating Wound Healing.

This study reports on the modification of bacterial cellulose (BC) membranes produced by static fermentation of Komagataeibacter xylinus bacterial strains with graphene oxide-silver nanoparticles (GO-Ag) to yield skin wound dressings with improved antibacterial properties. The GO-Ag sheets were synthesized through chemical reduction with sodium citrate and were utilized to functionalize the BC membranes (BC/GO-Ag). The BC/GO-Ag composites were characterized to determine their surface charge, morphology, exudate absorption, antimicrobial activity, and cytotoxicity by using fibroblast cells. The antimicrobial activity of the wound dressings was assessed against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The results indicate that the BC/GO-Ag dressings can inhibit ∼70% of E. coli cells. Our findings also revealed that the porous BC/GO-Ag antimicrobial dressings can efficiently retain 94% of exudate absorption after exposure to simulated body fluid (SBF) for 24 h. These results suggest that the dressings could absorb excess exudate from the wound during clinical application, maintaining adequate moisture, and promoting the proliferation of epithelial cells. The BC/GO-Ag hybrid materials exhibited excellent mechanical flexibility and low cytotoxicity to fibroblast cells, making excellent wound dressings able to control bacterial infectious processes and promote the fast healing of dermal lesions.

Synthesis and bio-medical applications of multifunctional phosphorester cyclic amide anchored sterculia network

The main focus of the present research is to design network hydrogels derived from natural polymers to promote a sustainable future. Multifunctional hydrogels were prepared by combining sterculia gum (SG), phosphorester -cyclic amide polymers for bio-medical applications including drug delivery (DD). The antibiotic drug ceftriaxone was incorporated into hydrogels to enhance wound healing potential. The surface morphology of copolymers was investigated by using FESEM and AFM techniques. FTIR and 13C NMR spectroscopic techniques provided insight into the formation of network structures. In FTIR analysis, distinctive bands were identified: at 1649 cm−1 attributed to CO stretching of the cyclic amide of PVP, at 1147 cm−1 and 974 cm−1 representing PO stretching and P-O-C of poly(BMEP), respectively. In the 13C NMR spectrum, a prominent peak at 63.272 ppm revealed the presence of (O-CH2) linkage of poly(BMEP). XRD demonstrated amorphous characteristics of hydrogels. The interactions of copolymer with blood, bio-membrane and encapsulated drug illustrated their biocompatibility, bio-adhesion and controlled DD properties. The dressings expressed a hemolytic index value of 2.58 ± 0.03 %. The hydrogels exhibited mucoadhesive character, revealed from the adhesion force of 50.0 ± 5 mN needed to separate polymer dressing from the mucosa. Dressings exhibited antioxidant properties and displayed 33.73 ± 0.3 % radical scavenging in the DPPH assay. Protein adsorption test of copolymer illustrated 9.48 ± 0.970 % of albumin adsorption. The tensile strength of the dressing was found 0.54 ± 0.03 N mm−2 while the burst strength 9.92 ± 0.27 N was observed. The sustained release of the drug was provided by supra-molecular interactions. Drug release followed a non-Fickian diffusion mechanism and the release profile was best described by the Higuchi kinetic model. Additionally, hydrogel dressings revealed permeability to H2O vapors and O2 and antimicrobial activity. These findings suggest the suitability of sterculia gum-based hydrogels for DD uses.

Nanocrystal Formulation to Enhance Oral Absorption of Silybin: Preparation, In Vitro Evaluations, and Pharmacokinetic Evaluations in Rats and Healthy Human Subjects.

Despite the various therapeutic benefits and high tolerance of orally administered silybin, poor water-solubility can be the main restrictive physicochemical feature, which results in low oral bioavailability in the absorption. A milk thistle nanocrystal formulation (HM40) was prepared using a modified wet-milling method. Comprehensive characterization was performed to determine the physical morphology, crystallinity, and physicochemical properties. The long-term stability was evaluated over 24 months. In vitro silybin release was assessed at pH 1.2 for 2 h, followed by pH 6.8 for 4 h. Finally, in vivo pharmacokinetic studies were conducted in rats and healthy human volunteers. HM40 exhibited a nanocrystal structure maintaining crystallinity and enhanced the solubility and dissolution of silybin compared to that of the raw material. The stability over 24 months revealed consistent surface morphology, particle size, silybin content, and solubility. In vitro release profiles indicated a significant increase in the silybin release from HM40. In vivo pharmacokinetic studies demonstrated that HM40 showed 2.61- and 1.51-fold higher oral bioavailability in rats and humans, respectively, than that of the reference capsule. HM40 formulation presents a stable and promising approach for the oral delivery of poorly water-soluble silybin, with the potential for use in pharmaceutical formulations containing milk thistle.

Histological Analysis of Enamel Microstructure in Response to Dietary Habits: Comparative Study A cross Different Populations

Background: The protective role of enamel against physical and chemical injury is well documented. Despite being classified as connective tissue, with its composition and microstructure dominated by hydroxyapatite crystals it is the hardest in the human body Objective: The purpose of this study is to investigate the histological changes in enamel microstructure that occur when distinct populations follow different food habits. Study Design: This study employs a comparative cross-sectional design. Duration and Place of the Study: This study was conducted at Department of pathology Watim medical and dental college, Rawat , from 3rd June 2022 to 2nd May 2023. Material and Methods: A sum of 300 dental examples were acquired from members having a place with one or the other, High Carbohydrate Diet Group (n=95): people accounting their principle dietary consumption high-carb nourishments like grains/pay/aries and starches. High-Proteins Diet Group (n=108): participants who had the highest consumption of protein-rich foods, such as meat products, legumes and dairy. Mixed Diet Group (n=97): People with intermediate consumptions of carbohydrates, proteins and fats Subsequently, study participants were determined to best represent the two diet groups based on dietary surveys and medical histories. Results: In total, 300 participants are considered in this research, with the mean age of the group on HC totals 3.5 ± 1.3 years, HP group 3.4 ± 9.2 years, and MD group 3.6 ± 1.1 years. The gender distribution also shows similar characteristics, males are 55.8% in HC group, 46.3% in HP group, and 52.6% in MD group; females are 44.2%, 53.7%, and 47.4%, respectively. Concerning the age range, the major cluster is 26-35 years old and 36-45 years old cohorts, which proves the majority of the middle ages. Conclusion: Our results indicate that decomposition is a major factor affecting the surface morphology, structure and health of enamel.

Enhanced Electrocatalysis on Copper Nanostructures: Role of the Oxidation State in Sulfite Oxidation.

The influence of surface morphology and the oxidation state on the electrocatalytic activity of nanostructured electrodes is well recognized, yet disentangling their individual roles in specific reactions remains challenging. Here, we investigated the electrooxidation of sulfite ions in an alkaline environment using cyclic voltammetry on copper oxide nanostructured electrodes with different oxidation states and morphologies but with similar active areas. To this aim, we synthesized nanostructured Cu films made of nanoparticles or nanorods on top of glassy carbon electrodes. Our findings showed an enhanced sensitivity and a lower detection threshold when utilizing Cu(I) over Cu(II). Density functional theory-based thermochemical analysis revealed the underlying oxidation mechanism, indicating that while the energy gain associated with the process is comparable for both oxide surfaces, the desorption energy barrier for the resulting sulfate molecules is three times higher on Cu(II). This becomes the limiting step of the reaction kinetics and diminishes the overall electrooxidation efficiency. Our proposed mechanism relies on the tautomerization of hydroxyl groups confined on the surface of Cu-based electrodes. This mechanism might be applicable to electrochemical reactions involving other sulfur compounds that hold technological significance.

Oxidation characteristics of copper oxide thin films deposited by direct current sputtering under substrate temperature and post-deposition copper-ion implantation

The oxidation and structural, optical and morphological properties of copper oxide thin films deposited by direct current magnetron sputtering under different substrate temperatures and oxygen (O2) partial pressures, and subsequent 200 keV Cu ion implantation are investigated. The colour of the films progressively changed from yellowish brown to dark brown and oxide phase from Cu2O to Cu4O3 to CuO through mixed phases with increase in oxygen partial pressure from 20 to 90 % of the working pressure and substrate temperature from room temperature (27 °C) to 350 °C. The rate of oxidation and crystallinity of the films substantially increased with increase in substrate temperature. The ion implantation in the room temperature deposited films produced significant crystallization and decrystallization with respect to the ion fluence, and that in 350 °C substrate temperature deposited films instigated Cu-rich phase. The substrate temperature and ion implantation engendered distinctive red shift of the absorption edge and prevalent changes in the interference patterns in the optical spectra of the films. The calculated direct band gap values of the films are in the range of 1.7 to 2.42 eV, which decreased to the range of 1.65 to 2.17 eV on ion implantation. The indirect band gap of the films with predominant Cu4O3 and CuO phases are in the range of 1.23 to 1.49 eV. The refractive index and extinction coefficient of the films at 1100 nm are in the range of 2.1 to 2.5 and 0.03 to 0.12, which increased to the range of 3 to 7 and 0.2 to 0.45, respectively, on ion implantation. The films displayed agglomeration of the particles and directional growth of the agglomerates with respect to O2 partial pressure and substrates temperature, and increase in the size of the particles / agglomerates, and rough surface morphology on ion implantation.

Optimizing Surface Morphology for Enhanced Radiative Properties in Thermal Energy-Efficient Materials

Environmental concerns related to heat-absorbing materials in the construction industry can be effectively addressed by optimizing the reflectivity of incoming sunlight and thermal emissivity of materials. These radiative properties are closely tied to the surface morphology characteristics of building materials, making superficial topography a critical factor in determining their thermal and energy performance. In our research, we performed reflectance analysis in the UV-Vis-NIR-MIR region and conducted FT-IR analysis to assess the colour and reflectance behaviour of the samples, along with surface morphology and topography investigations. The data collected were utilized in a statistical study to analyse the relationship between superficial topography and thermo-optical characteristics. Our findings underscore the significant impact of surface morphology as a secondary factor influencing radiative properties. Specifically, our results indicate that large-scale components influence Mid-Infrared absorbance, while surface roughness is crucial in determining solar reflectance properties. Notably, an increase in roughness consistently leads to a reduction in Near-Infrared and visible reflectance properties by up to 17% and 8%, respectively, with no noticeable effect in the UV region. In conclusion, our research demonstrates the potential for customizing and optimizing surface properties to reduce energy consumption for cooling purposes and alleviate the Urban Heat Island effect.

Development and characterization of kefiran-gelatin bio-nanocomposites containing Zhumeria majdae essential oil nanoemulsion to use as active food packaging in sponge cakes

Active packaging films based on kefiran-gelatin were developed and characterized using Zhumeria majdae essential oil nanoemulsion (ZMEO-NE) at concentrations of 0 (control), 1, 2 and 3 %. The main compounds of the essential oil (EO) of Zhumeria majdae (ZM) plant were linalool (61.44 %) and camphor (20.67 %). Adding the ZMEO-NE to the films decreased permeability to water vapor (from 7.82 × 10−7 to 4.09 × 10−7 g·m/m2·Pa·h), ultimate tensile strength (from 38.44 to 33.48 MPa), percentage of light transmission, and increased thickness (from 0.085 to 0.121 mm), opacity (from 2.11 to 2.79), and elongation at break (from 19.97 to 34.73 %), and changed color parameters. The establishment of hydrogen bonds between the ZMEO-NE and polymer network was confirmed. The ZMEO-NE decreased the storage modulus and glass transition temperature. Distinct variations in the films' surface morphology and a reduction in the crystalline structure were observed due to the presence of the ZMEO-NE. Elevating the concentration of the ZMEO-NE increased antioxidant capabilities of the films. The films incorporating the ZMEO-NE exhibited notable antibacterial efficacy against Staphylococcus aureus (reductions ≥4 log CFU/cm2) and Escherichia coli (reductions ≥2 log CFU/cm2) bacteria. The films also demonstrated suitable antifungal properties during storage of sponge cakes for 16 days.

Enhanced Mechanical, Corrosion, and Tribological Properties of Hydroxyapatite Coatings for Orthopedic and Dental Applications

Biomedical coatings were elaborated by pulsed electrodeposition with hydrogen peroxide (H2O2) into electrolytes on Ti6Al4V substrates, and the effect of H2O2 concentration on the electrolyte and the heat treatment was studied. The experimental procedures employed in this study produce a consistent hydroxyapatite coating. This coating is well-suited for use in bio-implants, as it enhances the integration of the implant with surrounding bone tissue and improves the mechanical performance. The coatings' surface morphology and chemical composition were assessed using scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDXS) for x-ray microanalysis. X-ray diffraction (XRD) was also utilized to identify the phases and composition of the coatings. Nanoindentation and scratch tests were conducted to analyze the nanomechanical properties and adhesion behavior. Potentiodynamic polarization was employed in the Ringer solution to evaluate the corrosion resistance and replicate the conditions of the human body environment. The results of our thorough investigation revealed that employing pulsed electrodeposition with 9% H2O2 in the electrolyte, combined with subsequent heat treatment, facilitated the creation of coatings comprising two distinct phases: stoichiometric hydroxyapatite (HAP) and β-tricalcium phosphate (β-TCP). Our meticulous research underscores the significance of this process in achieving these specific coating compositions. Under these tests listed above, this composite demonstrated favorable mechanical properties (E = 30.45 GPa and H = 72.2 MPa). It also exhibited superior scratch adhesion and a critical load of 23 MPa and 12 N, respectively. Additionally, an improvement in tribological comportment was observed, and the wear volume decreased from 4.15 106 μm3 to 2.44 106 μm3. The HAP coating heat treated with 9% H2O2 exhibited the highest corrosion resistance, with Ecorr at -0.189 V/SCE and icorr at -1.11 μA.cm-2

Hybrid-feature based spherical quasi-conformal registration for AD-induced hippocampal surface morphological changes

Background and objectiveEstablishing accurate one-to-one morphological correspondence between different hippocampal surfaces is a solid foundation for the analysis of AD-induced hippocampal morphological changes. However, owing to the large variations between hippocampal surfaces, exiting registration work either fails to obtain the accurate matching of local and overall morphological features or does not preserve the bijectivity during parametric mapping. For this reason, this study proposes a hybrid-feature based spherical quasi-conformal registration (HSQR) method that can effectively maintain the diffeomorphic property while meeting the hybrid-feature matching constraints in the spherical parameter domain. MethodsThe HSQR algorithm is primarily achieved through hippocampal surface hybrid feature extraction and spherical quasi-conformal registration. First, hybrid features for a comprehensive morphological description of the hippocampal surface were established, which included essential anatomical features (landmarks) and mean curvature (intensity) features to ensure the accuracy of surface morphology alignment. Second, spherical parameterization was applied to genus-0 closed surfaces, such as the hippocampus, which maximized the preservation of the original local surface morphology through area-preserving properties. Third, a novel spherical quasi-conformal registration algorithm that can handle large deformations is established. It transforms a 3D spherical parameter domain into a 2D plane parameter domain using iterative local stereo projection to improve the efficiency of the registration algorithm. Subsequently, by controlling the Beltramin coefficient, the hybrid morphological features could be aligned while ensuring bijection before and after registration. ResultsUsing a cohort including 161 patients with amyloid-β (Aβ) positive Alzheimer disease (AD), 234 Aβ positive mild cognitive impairment (MCI) and 266 Aβ negative cognitively unimpaired (CU) individuals from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, we set up the experiment which indicated that the HSQR-based whole bilateral hippocampal atrophy features demonstrated the stronger statistical power for group morphological differences of CU vs. MCI with q-value: 0.0453 for left hippocampus and 0.0401 for right hippocampus and group morphological differences of AD vs. MCI with q-value: 0.0282 for left hippocampus and 0.0421 for right hippocampus. ConclusionsOur registration algorithm may provide a solid foundation for the accurate quantification of hippocampal surface morphological changes for the differential diagnosis and tracking of AD.

Surface characteristics and machining rate of SS 316L coating developed using hydroxyapatite-mixed EDM process

Hydroxyapatite (HA) or bioceramic-based coatings on stainless steel (SS) 316L significantly enhance the biofunctionality of the base material’s surface. However, HA’s low thermal conductivity and brittleness limit its effectiveness as a coating material. This study investigates HA coating on SS 316L using electric discharge machining (EDM) with varying discharge energies and powder concentrations. Surface morphology, elemental composition, and phase analysis of untreated and coated samples were characterised using field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD). The results demonstrate that the HA-assisted EDM process creates a coating comprising biocompatible oxides, phosphates, carbides, and intermetallic compounds. The coating exhibits a thin resolidified layer of 10.74 μm, characterised by redeposited spherical debris, shallow cavities, and a surface texture of 2.688 μm. The layer’s hydrophilic nature is confirmed by a minimum contact angle of 47.68°. Taguchi analysis indicates that the machining rate is optimised at an HA powder concentration of 16 g/l, with peak current and HA powder concentration being the most influential parameters affecting resolidified layer thickness, surface texture, and wetting angle. The research intends to motivate SS 316L medical device manufacturers to implement the HA-assisted EDM process for bioimplant’s dual machining and coating.

Optimization of nanosecond laser drilling strategy on CFRP hole quality

The drilling and cutting of carbon fiber-reinforced epoxy resin matrix composite (CFRP) structural parts is a prerequisite for one-off moulding and assembly connections. However, the thermal ablation effect observed during nanosecond laser hole-making of CFRP results in significant accuracy errors and thermal damage defects in the quality of the holes obtained from the process. To enhance the quality of laser-drilling CFRP holes, a spiral drilling path was employed in this work. The influence of diverse drilling methodologies, encompassing the trajectory of the laser beam, the spacing between scans, and the direction of the suction system's pumping, on the quality of the holes was examined. The impact of these techniques on the precision and integrity of the holes was assessed in terms of their dimensions, the quality factor, the width of the heat-affected zone (HAZ), and the prevalence of microscopic defects. The results demonstrated that when the drilling strategy involves moving the laser beam from the outside to the inside (Scheme I), a scanning spacing of 20 μm, and backward pumping, the optimal micro-hole accuracy and surface morphology, as well as minimal thermal damage defects can be achieved. This study provides a reference for further optimization of the nanosecond laser drilling process.