Surface Morphology Research Articles

Surface Evolution and Optimizing Strategy for Polishing Natural Heterogeneous Marble Using Sol-Gel Diamond Pad

Inefficiency and poor quality are the main problems in polishing natural heterogeneous marbles using sol-gel (SG) diamond pads. A strategy was proposed to address these issues by establishing a natural heterogeneous marble polishing model based on the optimal polishing time. The surface evolution and optimal time for polishing natural heterogeneous marble were systematically investigated. Six different types of marbles were polished by the sol-gel diamond pads. The surface glossiness, roughness, peak–valley value, and surface morphology of the marbles were measured and analyzed after different polishing times. The optimal polishing time for each marble was revealed using sol-gel diamond pads. The experimental results show that the standard deviation of the hardness distribution of marble tile significantly affects the material removal inconsistency and evolution of the surface during polishing, resulting in different optimal polishing times for different kinds of marble. The larger the standard deviation of the hardness of the marble is, the more difficult it is to obtain better surface quality, and the orange peel effect is more likely to occur. Furthermore, the optimal polishing time has a good logarithmic relationship with the standard deviation of the hardness distribution. Finally, a curve model of the optimal polishing time for each marble was established. The determination of the optimal polishing time can effectively optimize the polishing process, simplify the processing flow, improve production efficiency, and reduce production costs. The proposed method and obtained results in this paper can provide a theoretical basis and reference for polishing other types of heterogeneous stone materials.

Influences of fiber orientation and process parameters on diamond wire sawn surface characteristics of 2.5D Cf/SiC composites

2.5D Cf/SiC composite materials are widely used in aerospace high-temperature components, optical system structural components and other fields due to their excellent performance. For the cutting of 2.5D Cf/SiC composites, diamond wire saw cutting process has great potential for application. In this study, experiments were conducted on cutting 2.5D Cf/SiC composites with diamond wire saw along different fiber orientations (P0°, P90°, V90°) and different process parameters. The effects of fiber orientation, feed speed, and wire speed on the surface morphology, surface waviness profile, and roughness of the as-sawn surface were analyzed. The results show that fiber orientation significantly affects the fiber damage mode and surface quality of the as-sawn surface, with the surface quality of the slices ranked as V90°>P0°>P0°. The surface morphology and surface roughness improves with decreasing feed speed and increasing wire speed. However, surface waviness profile peak-valley (PV) values increases with increasing the feed speed and wire speed. The study provides experimental references for process optimization and quality improvement in diamond wire saw cutting of 2.5D Cf/SiC composite materials.

The potential of nanocomposites (patuletin-conjugated with gallic acid-coated zinc oxide) against free-living amoebae pathogens.

Free-living amoebae infections are on the rise while the prognosis remains poor. Current therapies are ineffective, and there is a need for novel effective drugs which can target Naegleria, Balamuthia, and Acanthamoeba species. In this study, we determined the effects of a nano-formulation based on flavonoid patuletin-loaded gallic acid functionalized zinc oxide nanoparticles (PA-GA-ZnO) against Acanthamoeba, Balamuthia, and Naegleria trophozoites. Characterization of the nano-formulation was accomplished utilizing analytical tools, namely Fourier-transform infrared spectroscopy, drug entrapment efficiency, polydispersity index, dimensions, and surface morphologies. Anti-amoebic effects were investigated using amoebicidal assay, cytopathogenicity assay, and cytotoxicity of the nano-formulation on human cells. The findings revealed that nano-formulation (PA-GA-ZnO) displayed significant anti-amoebic properties and augmented effects of patuletin alone against all three brain-eating amoebae. When tested alone, patuletin nano-formulations showed minimal toxicity effects against human cells. In summary, the nano-formulations evaluated herein depicts efficacyversusAcanthamoeba, Balamuthia, and Naegleria. Nonetheless, future studies are needed to comprehend the molecular mechanisms of patuletin nano-formulations versus free-living amoebae pathogens, in addition to animal studies to determine their potential value for clinical applications.

Wetting Preference of Silica Surfaces in the Context of Underground Hydrogen Storage: A Molecular Dynamics Perspective.

The growing interest in large-scale underground hydrogen (H2) storage (UHS) emphasizes the need for a comprehensive understanding of the fundamental characteristics of subsurface environments. The wetting preference of subsurface rock is a crucial parameter influencing the H2 flow behavior during storage and withdrawal processes. In this study, we utilized molecular dynamics simulation to evaluate the wetting preference of the silica surface in subsurface hydrogen systems, with the aim of addressing disparities observed in experimental results. We conducted an initial comprehensive assessment of potential models, comparing the wettability of five common silica surfaces with different surface morphologies and hydroxyl densities in CO2-H2/water/silica systems against experimental data. After introducing the INTERFACE force field as the most accurate potential model for the silica surface, we evaluated the wetting behavior of the α-quartz (101) surface with a hydroxyl density of 5.9 number/nm2 under the impact of actual geological storage conditions (333-413 K and 10-30 MPa), the coexistence of cushion gases (i.e., CO2, CH4, and N2) at various mole fractions, and pH levels ranging from 2 to 11 characterized through considering the negative charges of 0 to -0.12 C/m2 via deprotonation of silanol on the silica surface. Our results indicate that neither pressure nor temperature has a significant impact on the wetness of the silica in the case of pure H2 (single component UHS operations). However, when CO2 coexists with H2, especially at higher mole fractions, an increase in pressure and a decrease in temperature lead to higher contact angles. Moreover, when the mole fraction of cushion gas ranges from 0 to 1, the contact angle increases 20, 9.5, and 4.5° for CO2, CH4, and N2, respectively, on the neutral silica substrate. Interestingly, at higher pH conditions where the silica surface carries a negative charge, the contact angle considerably reduces where surface charges of -0.03 and -0.06 C/m2 result in an average reduction of 20 and 80% in the contact angle, respectively. More importantly, at a pH of ∼11 (-0.12 C/m2), a 0° contact angle is observed for the silica surface under all temperatures, pressures, types of cushion gases, and varying mole fractions.

CFRTP single-lap adhesive bonding and its mechanical performance enhanced by laser surface treatment: Finite element simulation and experimental validation

The outstanding mechanical properties of carbon fiber reinforced thermoplastic polymer (CFRTP) have led to its widespread application in many industrial sectors. In response to the engineering challenge of repairing large non-critical CFRTP structural components in situ, an infrared fiber laser surface cleaning technology is proposed to treat the bonding interface and enhance the tensile strength of polypropylene (PP)-based CFRTP single-lap bonded joints. Specifically, through single-factor and orthogonal experiments, the impact of different process parameters on the properties of the bonded joints was identified first. Then, online temperature monitoring was performed to elucidate the laser treatment mechanism of the CFRTP sample interface. Surface morphology of the laser-treated samples further indicates that when the temperature of the sample surface surpasses the resin decomposition temperature with extended holding time, the resin could be removed from the surface more thoroughly. Additionally, a novel three-dimensional woven finite element (FE) model, accounting for anisotropic heat transfer, was established to predict the surface temperature and cleaning quality of CFRTP. The FE model incorporates the anisotropic heat transfer characteristics of carbon fibers, thus accurately simulating the heat transfer behaviors between carbon fibers and the resin matrix. The laser ablation mechanism is elucidated by examining the surface ablation morphologies and peak surface temperatures. A comparison between experimental results and FE simulations demonstrated a notable coherence in the trend of surface morphology variations, with discrepancies in peak surface temperatures ranging from 3.29 % to 24.63 %. The experimental tests proved that the shear strength of single-lap bonded joints reaches its maximum value when the laser power is 35 W, the scanning speed is 2500 mm/s, and the number of scans is four. The enhancement of the mechanical properties of bonded joints can be attributed to the improved wettability and higher surface free energy of the laser-treated samples.

High responsivity and detectivity β-Ga2O3 solar-blind photodetectors optimized by oxygen vacancy engineering

Solar-blind photodetectors (SBPDs) are core essential components for many critical applications such as precision guidance, fire warning, and space communications. Ultra-wide bandgap semiconductor β-Ga2O3 is considered to be an ideal material for the fabrication of SBPDs. However, synthetizing β-Ga2O3 with high quality factor while simultaneously in situ modulation of electronic and optoelectronic properties to enhance performance has been challenging. Here, pulsed laser deposition (PLD) technology is used to synthesize high-quality β-Ga2O3 thin films on a sapphire substrate. The oxygen vacancy engineered β-Ga2O3 films can achieve in situ precise control of their surface morphology, optical parameters, and optoelectronic properties by simply adjusting the oxygen pressure. Meanwhile, the optimal thickness of the β-Ga2O3 film for the developing high-performance SBPD is ∼221 nm, determined by fitting and analyzing the optical parameters measured by the ellipsometry. Subsequently, the influence of oxygen pressure on the performance of β-Ga2O3 SBPD is thoroughly explored, considering the optimization of electrode size and deposition time. When the oxygen pressure is set to 15 Pa, the β-Ga2O3-based SBPD achieves highly competitive responsivity (R) and detectivity (D*) at 250 nm, with values of 1080 A·W−1 and 1.4 × 1016 cm·W−1·Hz1/2, respectively. Additionally, the noise component of the β-Ga2O3 SBPD is further studied to calibrated the traditional device performance results. This work introduces a simple and straightforward approach to in situ tuning of the optoelectronic properties of β-Ga2O3, which is important for advancing β-Ga2O3 film growth technology and fabricating high-performance photodetectors.

Evaluation of a binary amphiphile/solvent mixture for the formulation of an ecological detergent as an alternative for removing fat from natural fiber surfaces

The application of a binary amphiphile/solvent blend composed of a natural surfactant (alkyl polyglucoside) and the green solvent ethyl lactate (EL) as an active component in the formulation of a new ecological detergent has improved the washing process conditions. Foaming properties of the detergent were optimal, with foam stability (R5) values of 76.17% and 78.61% for the best formulations. It is common practice to add substances that can regulate the pH to 9 to enhance the washing efficiency. This was reflected in the results of this study, where pH and the interaction between pH and surfactant type significantly influenced the percentage of residual fat. Currently, commercial detergents recommend a 1% dilution. However, studies have evaluated a 0.5% dilution. Therefore, it opted to evaluate new concentrations of 0.4% and 0.3%. Optimization of the factorial design resulted in dirt removal rates exceeding 91%, while the lowest percentage of residual fat (< 0.37%) was achieved at 25 °C, pH 9, and 0.3% detergent doses without lipase. Furthermore, illustrations of the surface morphology of the washed fibers demonstrated that the samples were not adversely affected by the formulated detergent or the washing process conditions. The alkyl polyglucoside/ethyl lactate binary blend was shown for the first time to exhibit strong interactions, possessing excellent residual fat and soil removal properties, suggesting its potential use in the formulation of green detergents for washing natural and synthetic textile fibers as a replacement for detergents based on ethoxylated fatty alcohols.

Ultralight activated carbon/polyimide foam with heterogeneous interfaces for improved thermal stability, mechanical properties, and microwave absorption

AbstractThe activated carbon (AC) has been widely used in the field of electromagnetic protection because of its porous, hollow microstructure and excellent electrical conductivity. In this paper, AC was prepared through KOH activation process. The ACs/polyimide foam (PIF) composite was prepared in situ during the synthesis of PI and the ACs. In this paper, AC was prepared using the potassium hydroxide (KOH) activation process. The AC/PIF composites were prepared by mixing ACs and pyromellitic dianhydride (PMDA) with methylene diphenyl diisocyanate (MDI). The pore structure and surface morphology of the ACs were observed using nitrogen adsorption–desorption isotherms and scanning electron microscopy (SEM). After KOH activation with KOH, the surface area and total pore volume of ACs significantly increased by 79.31% and 0.9539 cm3/g, respectively, mainly were the microporous structure. X‐ray photoelectron spectroscopy (XPS) results confirmed an increase in the oxygen content of ACs after KOH activation, indicating an increase in the relative hydroxyl content on the surface. The SEM resulting of the ACs/PIF composite has a well‐developed open cell structure. Thermal gravimetric analysis (TGA) revealed that ACs significantly improved the thermal stability of the ACs/PIF composite. The compressive strength of the ACs/PIF‐3 increased from 518 to 834 KPa, significantly enhancing its mechanical properties. Simultaneously, the microwave absorption performance can be controlled and regulated by optimizing the impedance gradient of the skeleton. Results showed that when ACs constituted 8 wt% of the PIF, the real permittivity (ɛ′) and imaginary permittivity (ɛ″) of ACs‐PIF‐5 were approximately 2.03 and 0.025, respectively.

Influences of ultrasonic vibration directions, amplitudes, and frequencies on sapphire polishing studied by molecular dynamics

The sapphire surface morphology, atom removal rate, temperature, polishing force, subsurface damage, dislocation, and stress were explored under different ultrasonic directions, frequencies and amplitudes through molecular dynamics (MD). For both vertical and horizontal vibration, the rising ultrasonic frequency and amplitude will reduce the tangential and normal force, and increase the subsurface temperature and the material removal rate (MRR). Higher frequencies promote the basal dislocation, thus reducing the subsurface damage. Higher amplitudes cause thinner subsurface damage layer under horizontal vibration. However, it is opposite at vertical vibration. The horizontal vibration can obtain a flatter polished surface and a thinner subsurface damage layer due to the longer trajectory and less impact on sapphire surface. This study can provide reference for sapphire high-quality polishing.

Effect of Surface Morphologies on the In Vitro and In Vivo Properties of Biomedical Metallic Materials.

Metallic biomaterials, including traditional bioinert materials (such as stainless steel, cobalt-chromium alloys, pure titanium, and titanium alloys), novel biodegradable metals (such as pure magnesium and magnesium alloys, pure zinc and zinc alloys, and pure iron and iron alloys), and biomedical metallic glasses, have been widely used and studied as various biomedical implants and devices. Many scientists and researchers have investigated their superior biomechanical properties, corrosion behavior, and biocompatibility. However, their surface characteristics are of extreme importance due to continuing interactions between the surface/interface of an implanted metallic biomaterial and the surrounding physiological environment. Surface morphologies on these metallic biomaterials can modulate their in vitro and in vivo biological responses. In this review, we have summarized and investigated the effect of various surface morphologies on the corrosion behavior, cellular response, antibacterial activity, and osteogenesis of biomedical metallic materials. In addition, future research directions and challenges of surface morphologies on biomedical metallic materials have been elaborated. This review can lay a theoretical and practical foundation for further research and development on biomedical metallic materials.

A mechanism study of thermal resistance formation and post-fire strength recovery in cement paste with carbon nanotubes and nanosilica via focused ion beam/scanning electron microscopy tomography

Although carbon nanotubes (CNT) and nanosilica (NS) have shown substantial potential for enhancing the thermal resistance and post-fire mechanical recovery of cementitious composites, their combined synergistic effects remain unclear. This study aimed to elucidate the influence of CNT and NS double-hybrids on the physicochemical properties of cementitious composites under different heating temperatures (200, 500, and 800 °C) and re-curing conditions (25 °C/65 % RH and water immersion). We assessed the changes in the compressive and tensile strengths, bulk density, surface morphology, hydration products, and pore characteristics using focused ion beam scanning electron microscopy to visualize the evolving nanoscale pore structures. Our findings reveal a remarkable synergistic effect on the thermal resistance and strength recovery properties of the CNT/NS hybrid samples, owing to the stable matrix observed after heating to 800 °C. Following exposure to 800 °C, the tensile strength exhibited a remarkable 69.6 % increase compared to its pre-heating state, without any indication of crack formation. The CNT served as nucleation sites, expediting the pozzolanic reaction of NS during heating and resulting in a homogenized pore structure with interconnected hydrates. The CNT/NS hybrid samples exhibited uniform shrinkage of hydrates without creating nanoscale rod-like pores typical in ordinary cement paste, while the increase in pore volume was predominantly attributed to the expansion of existing pores and the formation of nearby new pores.

Влияние технологических параметров на микроструктуру и свойства сплава AlSiMg, полученного методом селективного лазерного плавления

Introduction. The development of additive technologies is aimed at the synthesis of new powder compositions for selective laser melting plants, the study of the effect of mode parameters on the stable quality of products. The purpose of this work is to study the effect of the scanning strategy on the microstructure, elemental composition, porosity and density of specimens obtained by selective laser melting from non-spherical powders (Al — 91 wt. %, Si — 8 wt. %, Mg — 1 wt. %), subjected to special preparation to determine the optimal conditions for selective laser melting. The research methods are methods of X-ray diffraction and X-ray phase analysis, transmission electron microscopy. The paper examines specimens formed using four different scanning strategies. Results and discussions. A promising aluminum alloy AlSi8Mg is developed for selective laser melting. The material has good manufacturability and low powder cost. The technological parameters of melting make it possible to form a thin structure with a low level of porosity. The mechanism of influence of the scanning strategy on porosity, surface morphology, relative density and microstructure is investigated. A specimen from the AlSi8Mg powder composition with a high relative density of 99.97 % is produced by selective laser melting with an energy density of 200 J/mm3, a specimen scanning circuit when the direction of laser movement changes by an angle of 90° each odd layer. It is proved that the density of the AlSiMg alloy depends on the scanning strategy used. The calculated density of the specimen was 2.5 g/cm3, which corresponds to the density of silumin. Analysis of SEM images and maps of the distribution of elements (Al, Mg, Si) of the specimens showed that different specimen formation strategies do not affect the nature of silicon distribution. A unique grain structure is observed in the resulting AlSi8Mg alloy. The melt pool consists of small grains along the border and large grains in the center. The formation of fine grains is explained by the addition of Si and the high cooling rate during selective laser melting.

Gossypol derivate as a green anti-corrosion agent in the aqueous phase of crude oil.

Keeping recruitment of green and cost-effective solutions for environmental challenges in view, the current work was designed to solve the problems related to metal corrosion in the aqueous phases of crude oil in chemical industries. Green materials can play an important role in protecting metals from this corrosion. Hence, the green anti-corrosion material based upon gossypol derivate is suggested to solve the above problems. The electrochemical characteristics were appraised by cyclic voltammetry, electrochemical impedance spectroscopy, potentiodynamic polarization, and electrochemical noise methods. The thermodynamics were studied by gravimetric analyses. The surface morphology was scrutinized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Density functional theory and molecular dynamic simulations were exploited in theoretical analyses. The gossypol derivate is green, non-toxic, more efficient, non-volatile, and chemically stable anti-corrosion material for gas and oil industries. Carbon steel corrosion simulated in aqueous phases of crude oil (NaCl solutions (1.0M) saturated with H2S and CO2) was maximally prohibited by forming a protective layer of binaphthalene. Its protection degree is 96.71% (at 100.0mg/L/0.107mM). The gossypol ring is a suitable core for preparing the next modification materials to protect against corrosion. The rigid adsorption progressed mainly via hydroxyl functional moieties. Compared to the inhibition behavior of the neutral form of gossypol, the optimized protonated form causes a greater inhibition.

Optimization of Zn-Cr proportions for hybrid multilayer electroplating of AISI 1045 steel – towards super-hydrophobicity and anti-corrosive nature

Localized corrosion in steel heat exchangers is a major concern, occurring mostly during operational shutdowns. Due to the absence of flow and moisture content availability, corrosion reduces operation efficiency. A study aimed to optimize the proportions of Zinc and Chromium (Zn-Cr) for developing a hybrid multi-layer electroplating method to inhibit corrosion in hypo-eutectoid carbon steel commonly used in heat exchangers. The Zn-Cr coating was performed using the amperometric method in an electrochemical workstation, producing coatings of varying thicknesses by varying the potential and time. The surface morphology was characterized using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analysis. The average thickness of the Zn-Cr coating was found to be 2.5 µm using the scanning probe microscope analysis. The corrosive action of a standard 3.5% NaCl solution was investigated on both coated and uncoated specimens through open circuit potential measurement and electrochemical impedance spectroscopy. The results indicated that the Zn-Cr coating effectively resisted corrosion. Contact angle measurement of water particles with the Zn-Cr coated specimen revealed a near-super hydrophobic nature with the highest contact angle of 146.8°.

Effect of peroxide-free and peroxide-based in-office bleaching on the surface and mechanical properties of CAD/CAM esthetic restorative materials.

The study aimed to investigate the influence of H2O2-based and H2O2-free in-office bleaching on the surface and mechanical attributes of CAD/CAM composite blocks. CAD/CAM composite blocks from five different composite materials (CC1, CC2, CC3, CC4, and CC5) were randomly divided into two groups according to bleaching application (H2O2-based and H2O2-free). The surface topography, morphology, nanohardness, elastic modulus, flexural strength, and fracture toughness were measured. A paired and unpaired sample t-tests gauged the effect of pre- and post-bleaching on the substrates. The estimated mean differences (before-after bleaching) suggested an increase in surface roughness for two materials CC2 and CC4, and a significant decrease in nanohardness for material CC4 and in elastic modulus for materials CC2 and CC4 with H2O2-based bleaching, whereas H2O2-free bleaching resulted in changes compatible with no change in these properties. Flexural strength and fracture toughness showed no evidence of changes, irrespective of the bleaching gel used. Scanning electron microscopic analysis revealed erosive effects and micropore formation due to H2O2-based bleaching. H2O2-based bleaching deteriorates the surface of CAD/CAM composite materials while H2O2-free bleaching gel had an insignificant effect on both surface and bulk properties. The clinician should carefully evaluate the potential effects of H2O2-based bleaching on the surface properties of CAD/CAM composites.

Superior performance of multi-layer graphene assisted Al/ B i 2 O 3 nanothermite for small-scale propulsion applications

ABSTRACT Highly reactive Al/ B i 2 O 3 nanothermite reinforced with MLG (multi-layer graphene) is prepared using physical mixing technique, and its exothermic energy release and specific impulse are studied for small-scale propulsion applications using differential scanning calorimeter and force sensor, respectively. The chemical composition of nanothermite samples is examined using X-Ray Diffraction (XRD). Field emission scanning electron microscopy (FESEM) is employed to analyze the surface morphology of prepared samples. According to DSC data, the energy release in Al/Bi2O3 nanothermite increases with increasing content of MLG nanoplatelets up to three weight percent of MLG in nanothermite composition. The maximum value of observed energy release is 668 J/g for nanothermite with three weight percent of MLG. Similar outcomes are observed for the specific impulse values of Al/MLG/Bi2O3. The maximum value of specific impulse observed for Al/Bi2O3 nanothermite with two weight percent of MLG is 50.8 s.

3D Micro-CT and O-PTIR Spectroscopy Bring New Understanding of the Influence of Filler Content in Dental Resin Composites

BackgroundDental resin composites' performance is intricately linked to their polymerisation shrinkage characteristics. This study compares polymerisation shrinkage using advanced 3D micro-computed tomography (micro-CT) and traditional 2D linear assessments. It delves into the crucial role of filler content on shrinkage and the degree of conversion in dental resin composites, providing valuable insights for the field. MethodsFive experimental dental composite materials were prepared with increasing filler contents (55-75wt%) and analysed using either 3D micro-CT for volumetric shrinkage or a custom-designed linometer for 2D linear shrinkage. The degree of conversion was assessed using Optical Photothermal Infrared (O-PTIR) and Fourier-Transform Infrared (FTIR) spectroscopy. Light transmittance through a 2-mm layer was evaluated using a NIST-calibrated spectrometer. Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDX) examined surface morphology and elemental distribution. Correlation between the investigated parameters was determined using Spearman correlation analyses. ResultsThe study found significant differences in polymerisation-related properties among different filler content categories, with volumetric shrinkage consistently demonstrating higher mean values than linear shrinkage across most groups. Volumetric shrinkage decreased with increasing curing depth, showing no direct correlation between filler content and shrinkage levels at different curing depths. The results highlighted a strong negative correlation between filler content and degree of conversion, volumetric and linear shrinkage, as well as maximum shrinkage rate. Light transmittance showed a moderate correlation with the filler content and a weak correlation with other tested parameters. ConclusionsThis study underscores the importance of considering both volumetric and linear shrinkage in the design and analysis of dental composite materials. The findings advocate optimising filler content to minimise shrinkage and enhance material performance. Integrating micro-CT and O-PTIR techniques offers novel insights into dental composites' polymerisation behaviour, providing a foundation for future research to develop materials with improved clinical outcomes.

Droplet transition behavior and compositional homogenization of TiAl alloys fabricated via dual-wire electron beam-directed energy deposition

The dual-wire electron beam-directed energy deposition (EB-DED) process presents considerable advantages for fabricating titanium aluminide (TiAl) alloys via in situ reactions between Ti and Al. However, variations in the thermophysical properties of pure Ti, pure Al, and TiAl alloys pose challenges in achieving consistent droplet transition behavior and uniform chemical composition. This study explored the effects of wire feeding modes on the forming quality of TiAl alloys and droplet transition behaviors and discussed compositional homogenization and elemental evaporation in TiAl alloy components. Both single-side and double-side feeding modes were utilized, and the electron beam directly melted the Ti wire in the double-side mode, thereby achieving superior surface morphology. Random disturbances and suboptimal wire feeding angles led to the wires deviating from the electron beam center and then being inserted into or passing through the molten pool, thereby degrading the forming quality. By positioning the Al wire tip beneath the Ti wire tip, a common droplet emerged as the Ti droplets melted the Al wire. The droplet transition behavior was regulated by the distance between the wire tips and component surfaces, achieving a liquid bridge transition at distances ranging from 0.75 to 5.82 mm. Although the droplet composition was generally uniform owing to elemental evaporation, the fluctuations among the droplets exceeded those observed in the as-deposited components. The extensive molten pool and keyhole effect enhanced compositional homogenization within the TiAl alloy components. During the deposition process, the evaporation rate of Al surpassed that of Ti due to its higher saturation vapor pressure, consequently yielding a lower actual Al content. The loss rate of Al initially decreased and then increased as the calculated Al content increased, which was influenced by the Al content in the molten pool and temperature variations. This research advances the fundamental understanding of TiAl alloy fabrication via in situ reactions and contributes to the development of the EB-DED process.

Synthesis and characterization of fluorescent carbon dots obtained from citrus x sinensis by an eco-friendly method

The synthesis and characterization of fluorescent carbon dots (CDs) obtained by an environmentally friendly method through carbonization, fragmentation and centrifugation of orange peel (citrus x sinensis) are reported. By thermogravimetry, 4 degradation regions associated with hemicellulose, lignin and organic matter were found. The SEM micrograph shows a rough surface morphology with flakes and granulation due to the carbonization process. X-ray diffraction (XRD) shows a hexagonal crystalline structure associated with graphitic carbon, which was confirmed by Raman scatterings, Raman spectroscopy that presented two main vibrational bands, D and G, associated with active defects in the graphitic carbon crystalline structure. The Transmission electron microscopy (TEM) micrograph showed CDs of size 33.65 ± 0.68n, and with High-Resolution TEM (HRTEM) an interplanar distance of 0.213 nm in the direction of the crystal planes (100) of graphitic carbon was obtained, which were confirmed by XRD and Raman spectroscopy. X-ray photoelectron spectroscopy revealed the relative atomic composition and identified the strongest photoelectron transitions of carbon, sp2 (286 eV) and sp3 (285 eV), in graphitic carbon. Ultraviolet–visible (UV–Vis) spectroscopy of the CDs obtained from fragmentation graphitic carbon showed a band at 205 nm associated with CC bonds π-π* of CC and n-π*, as well as two bands at 276 and 328 nm associated with bond transitions. The Fourier Transform Infrared (FTIR) spectrum showed bands associated with CHs bonds as well as CC, CN bonds of the CDs. Fluorescence spectroscopy showed three emission bands at 2.43, 2.54 and 2.87 eV. The CDs showed the emission of the characteristic blue colour.

Biocompatible Electrospun Hydrogel Fibers for Advanced Wound Healing Therapies.

Wound healing is a complex cascade and is governed through a number of crucial factors. Conventional wound dressing possesses numerous limitations which hinder wound healing process and may result in serious infections and even mortality. A lot of effort have been put in through researchers to develop a multifaceted dressing which can address these limitations and facilitate accelerated wound healing. Among various newly developed dressings, electrospun hydrogel nanofibers have emerged as a promising class of biomaterials for advanced wound care and tissue engineering applications. These biomimetic fibers closely mimic the architect of the native extracellular matrix, providing an optimal environment that facilitates cellular proliferation and fast generation required for effective wound healing. Electrospinning offers versatility in precisely controlling fiber attributes such as diameter, alignment, and surface morphology and can entrap a variety of drugs with high efficacy. Recently, such dressings have advanced through the incorporation of smart features such as stimuli-responsive components, real-time wound monitoring sensors, and smart closed-loop systems. The electrospun hydrogels are bestowed with extreme porosity, water-retention attribute, biocompatibility, and modified drug release which make them superior over other wound dressings. The review gives an insight of electrospun hydrogel fibers and their application in wound healing and the studies assessing wound healing potential with underlying mechanisms have been critically analysed. Electrospun hydrogel fibers have significant potential to revolutionize wound care through their biomimetic structure, versatile customization, and capacity for integrating therapeutic and sensing capabilities, outlining future research directions toward next-generation wound care products.