Search Results (9,551)

The investment casting process, also known as lost-wax casting, is widely used for producing ferrous and non-ferrous metal parts due to its excellent surface finish and dimensional accuracy. In recent years, the use of Co-Cr-Mo alloy has increased due to its high corrosion resistance, good biocompatibility, and relatively high wear resistance. Laser melting of materials has been demonstrated to refine the surface grain structure, reduce surface roughness, and improve both wear and corrosion resistance. The ability to fine-tune parameters such as laser power density and scanning speed facilitates the optimization of the treated layers’ thickness and homogeneity, thereby addressing many of the shortcomings inherent in conventional methods. This study investigates the microstructural, mechanical wear and bioactive behavior of investment-cast Co-Cr-Mo parts subjected to a Nd:YAG laser surface treatment. The effects of different processing parameters were analyzed quantitatively and comprehensively. The specimens were characterized using metallographic techniques, bioactivity evaluation, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), wear testing (Pin-on-Disk), and hardness testing. Our results demonstrate that Nd:YAG laser melting significantly enhances the surface properties and maintains the dimensional accuracy of complex Co-Cr-Mo biomedical components, through microstructural refinement, increased hardness, improved wear resistance, and preserved biocompatibility. The specific combination of investment casting with precisely controlled laser surface modification represents a significant advancement for improving the longevity and performance of biomedical implants. Full article

Methicillin-resistant Staphylococcus epidermidis (MRSE) contamination is commonly found on human skin and medical devices. Herein, we present a sensor utilizing molecularly imprinted polymer nanobodies (nanoMIP) for recognition and electrochemical impedance spectroscopy (EIS) to detect S. epidermidis. Sensor manufacturing involves synthesizing nanoMIP via solid-phase synthesis using whole bacteria as templates. Screen-printed gold electrode (AuSPE)-modified 16-mercaptohexadecanoic acid (MHDA) served to immobilize the nanoMIPs on the sensor surface through an amide bond, with the remaining functional groups blocked by ethanolamine (ETA). Scanning electron microscope (SEM) analysis of the modified AuSPE surface reveals immobilized spherical nanoMIP particles of 114–120 nm diameter, while atomic force microscope (AFM) analysis showed increased roughness and height compared to bare AuSPE. The sensor is selective for S. epidermidis, with a remarkable detection limit of 1 CFU/mL. This research demonstrates that the developed nanoMIP-based sensor effectively detects S. epidermidis. Further research will focus on developing protocols to integrate the nanoMIP-based EIS sensor into medical and industrial applications, ultimately contributing to improved safety for both humans and animals in the future. Full article

A surface treatment of amorphous alloy was conducted using reciprocating friction, and precursors with varying degrees of surface roughness were selectively etched to form a three-dimensional nanoporous structure with interconnected networks. The wear behavior induced by friction facilitates dealloying to different extents. While altering the surface roughness of the amorphous alloy, this method preserves its unique structure and maintains the advantages of the precursor in preparing nanoporous materials (NPMs). Under identical dealloying conditions, the thickness of the nanoporous copper layer on the rougher surface (with a surface roughness of approximately 0.808) is significantly greater than that on the smoother surface (with a surface roughness of approximately 0.002), and this disparity increases over time. The findings indicate that friction-induced changes in surface roughness play a crucial role in the preparation of nanoporous copper via dealloying. Modifying the surface roughness through friction can enhance the dealloying process, improve the adhesion between the nanoporous copper (NP-Cu) layer and the amorphous matrix, and mitigate crack propagation during NP-Cu formation and under stress. Selecting an appropriate level of roughness can enhance the long-term stability of NP-Cu. Full article

Lignocellulosic waste biomass, a versatile natural resource derived from plants, has gained significant attention for its potential in the sustainable production of biobased chemicals. Furfural (FAL), xylo-oligosaccharides (XOSs), and reducing sugars are important platform chemicals, which can be obtained through the valorization of lignocellulosic solid biomass in a green and sustainable way. Waste yellow bamboo (YB) is one kind of abundant, inexpensive, and renewable lignocellulosic biomass resource. In order to improve the high-value utilization rate of raw YB, biochar-based solid acid catalyst (AT-Sn-YB) was utilized to assist the hydrothermal pretreatment for the valorization of YB in water. Under the optimal reaction conditions (200 °C, 60 min, and AT-Sn-YB dosage of 5.4 wt%), the FAL yield reached 60.8%, and 2.5 g/L of XOSs was obtained in the pretreatment system. It was observed that the surface structure of YB became rough and loose, exposing a significant number of pores. The accessibility increased from 101.8 mg/g to 352.6 mg/g after combined treatment. The surface area and hydrophobicity of lignin were 70.7 m²/g and 2.5 L/g, respectively, which were significantly lower than those of untreated YB (195.4 m²/g and 4.1 L/g, respectively). The YB solid residues obtained after treatment were subjected to enzymatic saccharification, achieving an enzymatic hydrolysis efficiency of 47.9%. Therefore, the hydrothermal pretreatment assisted by the AT-Sn-YB catalyst shows potential application value in FAL production and bamboo utilization, providing important references for other biomass materials. Full article

The corrugation of the interfaces of the cross-section of hollow core fibers based on the inhibited coupling waveguiding mechanism is modeled and the impact on propagation loss analyzed. The proposed model is based on a combined use of coupled-mode theory and Azimuthal Fourier Decomposition. It shows that such transverse roughness causes coupling between the core modes and the dielectric modes of the cladding and consequently an increase of the fiber loss. The model is validated by comparing theoretical and numerical results obtained by applying both deterministic and stochastic corrugations to tubular lattice and nested fibers. Scaling laws and impact of the fibers’ parameters are discussed. The model shows that the loss increase is not directly correlated to the root mean square of the stochastic roughness but only to the value of the power spectral density in specific spatial frequency ranges. In particular, the spectral components characterized by a periodicity lower than ${10}^{-1}$ of the tube circumference must have a power spectral density value lower than 0.2 nm² to ensure a negligible effect of the transverse roughness on fibers with losses lower than 0.1 dB/Km. Full article

The aim of this article is to simulate the distribution of oil or lubricants on the surface by the characterization of the R and S roughness parameters. It is considered that undesirable particles may appear in the oil due to friction, the wear of parts, or dirt in the lubrication circuit. One of the problems that can generate the appearance of particles in the oil is the poor distribution of this along the surface, using standards, standardised particle sizes, and following the standard. This research aims to implement effective algorithms for the calculation of profile and surface roughness parameters following existing standards, as well as the development of a morphological filter that will simulate particles on the surface. The analysis of the surface roughness of the surface in contact with the lubricant can help to decide the maximum particle size that is permissible in the system; therefore, analysing the oil will help to decide when it is necessary to filter or replace that lubricant. This research is carried out form the geometrical point of view of the morphological filter effect. This paper represents a first approach to researching the calculation of all standardized profile and surface roughness parameters. As a result, only a selection of parameters has been chosen from the full range of available ones, in order to improve effectiveness. Full article

This study focuses on enhancing the biomedical performance of PBF-LB Ti6Al4V, produced using Selective Laser Melting (SLM), an advanced manufacturing technology widely used for patient-specific medical devices and implants. Hydroxyapatite (HA), titanium (Ti), and bilayer Ti/HA coatings were applied, using the powder flame spray coating technique. A comprehensive analysis was conducted to examine the microstructural, chemical, and mechanical properties of the coatings. Surface analysis was performed using a scanning electron microscope (SEM), chemical composition was determined by energy-dispersive spectroscopy (EDS), crystal structure was analyzed via X-ray diffraction (XRD), and surface roughness was evaluated through topographic analyses. Additionally, in vitro wear and corrosion resistance tests, crucial for biomedical applications, were conducted. In wear tests, HA coatings exhibited the lowest wear resistance with the highest wear rate (73.83 × 10⁻³ mm³/N·m), while Ti coatings showed the highest wear resistance (6.32 × 10⁻³ mm³/N·m), and Ti/HA coatings demonstrated an intermediate performance (34.22 × 10⁻³ mm³/N·m). Corrosion tests revealed that bilayer Ti/HA coatings provided the best protection (0.00009 mm/year), followed by Ti coatings (0.0002 mm/year) and HA coatings (0.003 mm/year). The results indicate that Ti/HA coatings offer the most suitable biomedical performance. Full article

The third-generation semiconductor single-crystal silicon carbide (SiC), as a typical difficult-to-machine material, improves the chemical reaction rate on the SiC surface during the polishing process, which is key to realizing efficient chemical mechanical polishing (CMP). In this paper, a new core-shell structure Fe₃O₄@MIL-100(Fe) magnetic catalyst was successfully synthesized, which can effectively improve the reaction rate during the SiC polishing procesSs. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), and was used as a heterogeneous photocatalyst for chemical mechanical polishing, and the polishing results of SiC were optimized using response surface methodology (RSM). The experimental results show that the surface roughness of SiC can reach the minimum value of 0.78 nm when the polishing pressure is 0.06 MPa, the polishing speed is 60 rpm, and the polishing flow rate is 12 mL/min. The results of the study provide theoretical support for the visible photocatalysis-assisted CMP of SiC. Full article

The slip mechanism between the chunk and wafer during high-speed dynamic scanning of the extreme ultraviolet lithography (EUV) motion stage remains unclear. Considering real-machined roughness, molecular dynamics (MD) simulations were performed to investigate the nanotribological behavior of 6H-SiC sliders on single-crystal silicon substrates. The effects of sinusoidal asperity parameters and normal loads on wear and slip were systematically analyzed. Results indicate that, for friction between sinusoidal asperities and ideal flat surfaces, the amplitude of surface parameters exhibits negligible influence on friction. In contrast, reduced normal loads and lower periods significantly increase both friction force and coefficient of friction (COF). Full article

With the increasing demand for environmental protection, flattened bamboo is gradually attracting attention as a sustainable material. The purpose of this study was to compare and analyze the surface properties of flattened bamboo and PU self-foaming plastic by subjective and objective evaluation methods, and to explore the substitutability of flattened bamboo and PU self-foaming plastic in furniture design. Objective test methods such as surface hardness testing, gloss measurement, and friction coefficient determination were used in the experiments, and the subjective evaluation of visual and tactile perception of the materials were combined with the semantic differential method. It was found that the flattened bamboo was generally superior to the PU self-foaming plastics in terms of color, gloss, roughness, and wettability, giving a more delicate, warm and comfortable feeling, while the PU self-foaming plastics stood out in terms of personalized style. Further correlation analysis showed that surface gloss and color saturation had a significant effect on the users’ psychological feelings. This study provides a scientific basis for replacing PU self-foaming plastic with bamboo in furniture design and also provides a valuable reference for “bamboo instead of plastic” product design. Full article

Understanding the structural evolution of two-phase fluid flow in fractured rock is of great significance for related rock engineering, including underground oil and gas extraction, contaminant storage and leakage, etc. Considering that rock fracture is the fundamental element of fractured rock, we conduct a series of numerical simulations to investigate the role of fracture aperture, surface roughness and shear displacement in the transition of two-phase fluid flow. The roughness fracture surfaces were generated by a MATLAB code we developed according to successive random addition algorithms. The level set method was applied to describe two-phase fluid flow and the numerical solution of the governing equations in COMSOL 6.2, and its effectiveness was verified by comparing it with the results of previous experiments. Numerical simulation results indicated the following: the water saturation (S_w) in the fracture decreases with an increase in the gas–water flow rate ratio; with an increase in roughness, the water saturation contained within the fracture gradually increases; the effect of fracture roughness on the two-phase fluid flow structure is enhanced; with an increase in dislocations, the water saturation in the low-roughness fracture increases, and the water saturation in the high-roughness fracture first increases and then decreases. The results of this study can provide reference significance for the study of gas–water two-phase fluid flow and provide theoretical guidance in related engineering. Full article

With the continuous and rapid development of global industries, issues such as offshore oil spills, leakage of organic chemicals, and the direct discharge of industrial oily sewage have caused serious damage to the ecological environment and water resources. Efficient oil–water separation is widely recognized as the solution. However, there is an urgent need to address the difficulties in treating thin oil films on the water surface and the low separation efficiency of existing oil–water separation materials. In view of this, this study aims to investigate high-efficiency oil–water separation materials for thin oil films. Four types of oil–water separation materials with different materials are designed to treat thin oil films on the water surface. The effects of factors such as oil film thickness, pressure, and temperature on the oil–water separation performance of these materials are studied. The viscosities of kerosene and diesel oil are tested, and the adsorption and separation effects of the oil–water separation materials on different oil products and oily organic solvents are examined. In addition, the long-term stability of the movable and portable oil–water separation components is verified. The results show that the oil-absorbing sponge-based oil–water separation membrane has an excellent microporous structure and surface roughness, endowing the membrane surface with excellent hydrophobicity and lipophilicity, and exhibiting good oil–water separation performance. The filtration flux of oil increases with the increase in pressure and temperature. It has good adsorption and separation performance for different oil products and oily organic solvents. Moreover, it maintains stable operation performance during the 12-month long-term oil–water separation process for kerosene and diesel oil. Full article

The rational use of wood waste allows the saving of forest resources and contributes to the reduction of the greenhouse effect. Three types of wood waste were used in this work: packaging (W), demolition and furniture construction (PLY), and door production (DW). The work performed an analysis of the granulometric composition of the wood waste and assessed the size, shape, and composition of the wood particles. The particle size was in the range of 0–20 mm, but the quantitative proportion of particles of different sizes in waste of different nature and shape was different. All wood particles were thermochemically treated to reduce the amount of dust and soluble particles and to increase the surface roughness of the wood particles to ensure better adhesion parameters with the binder. The binder used was biopolyurethane. Engineered wood composites (EWC) were formed from biopolyurethane and wood waste in a 50:50 ratio to evaluate compressive and bending strength. The strength values showed that all wastes were suitable for forming composites, but the size of the particles affected the magnitude of these values. The highest compressive stress of 11.7 MPa was obtained from composites using 0–5 mm PLY waste, while the lowest stress of 5.2 MPa was obtained from 0–20 mm W waste. In this case, the size of the wood waste particles affected not only the compressive stress but also the density of the composite. The analysis of the composite densities showed that 84.1% of the variation in the total density values was determined by the sample fraction, particle length-width ratio, angularity and sharpness and 15.9% by other factors that were not evaluated. For flexural strength, particle size and nature did not show a clear tendency, and values ranged from 7.2 to 11.5 MPa. The thermochemical treatment method of the wood particles had no or only a slight effect on the strength characteristics of the engineered wood composite. Full article

Pneumatic polishing tools are commonly used in traditional robot mold polishing systems, but they have problems with the stable control of mold surface roughness due to low precision and poor adaptability in polishing force adjustment. The integration of an adaptive hydraulic polishing (AHP) tool and robot system effectively solves the above problems, providing a robust solution for the high-precision polishing of various molds. This study systematically investigates the robotic polishing of NAK80 mold steel using an AHP-equipped robotic platform with 3M abrasive discs of progressively refined grit sizes (P180, P400, P800). Through single-factor experiments and response surface methodology, the effects of polishing force, rotational speed, and feeding speed on surface roughness were quantitatively analyzed. The relationship between surface roughness and the polishing parameters was derived to elucidate the roughness evolution before and after over-polishing. Orthogonal experiments combined with range analysis identified optimal parameter combinations for P180 (20 N polishing force, 5000 RPM rotational speed, and 5 mm·s⁻¹ feeding speed) and P400 abrasives (10 N polishing force, 4000 RPM rotational speed, and 5 mm·s⁻¹ feeding speed), achieving minimum surface roughness values of 0.08 µm and 0.044 µm, respectively. For P800 abrasives, a central composite design was used to develop a roughness prediction model with a ≤7.14% relative error, and the optimal parameters are a 20 N polishing force, a 5000 RPM rotational speed, and a 5 mm·s⁻¹ feeding speed. The sequential application of the optimized parameters across all the grit sizes can reduce the surface roughness from an initial 0.4 µm to a final 0.017 µm, representing a 95.75% improvement in the surface finish. Full article

This study investigates the biodegradation behavior of poly(butylene succinate) (PBS) copolyesters containing dilinoleic acid (DLA) co-monomeric units and wood flour (WF) as a filler. PBS-DLA is a segmented thermoplastic elastomer (TPE), where the soft amorphous phase is formed by DLA ester segments, while the hard phase consists of crystallizable PBS domains. Wood–plastic composites (WPCs) were prepared with WF at weight fractions of 10%, 20%, 30%, and 40% wt. and analyzed in terms of surface morphology, chemical structure, mechanical performance, and thermal stability before and after biodegradation in soil conditions. The results of microscopic analysis confirmed that the PBS-DLA copolymer and its composites undergo surface biodegradation as manifested by increased surface roughness and microcrack formation, particularly in composites with a higher WF content. ATR FT-IR spectroscopy indicated oxidation and hydrolysis, supporting the hypothesis of progressive surface erosion. Mechanical tests showed a decline in tensile strength and elongation at break, with the most pronounced changes in composites containing 20% WF. Thermal analysis (DSC, DMTA, and TGA) confirmed that the PBS-DLA copolymer retains its thermoplastic elastomeric behavior after a 3-month biodegradation experiment. The storage modulus (E′) remained stable, while only minor variations in melting and crystallization temperatures were observed. These findings reinforce the hypothesis of surface erosion rather than a bulk degradation mechanism. Given their biodegradability and retained thermoplastic behavior, WPC composites based on PBS-DLA copolyester could be promising for eco-friendly applications where controlled degradation is desirable, such as in packaging, agriculture, or biodegradable consumer goods. Full article