Functional Surface Structures Research Articles

Creation of an Aluminum Alloy Template with a Surface Structure by Micro-Milling for Subsequent Replication of the Microstructure to Achieve Hydrophobicity

This research paper focuses on the fabrication of a microstructure based on a natural structure pattern of hydrophobic properties using micro-milling technology, followed by an investigation of the dimensional accuracy, roughness, and replication of the fabricated microstructure. Design, modeling (CAD system), fabrication, and replication are the steps of this process. Knowledge of biomimetics was used to select the microstructure. The main research aim of the experiments is to verify and extend the applicability of conventional CNC manufacturing technologies to obtain a functional surface structure. The micro-milling was carried out on a conventional DMG MORI CNC machine, a CMX 600 V three-axis horizontal milling center, using an external high-frequency electric spindle clamped to the machine. The machined material was aluminum alloy EN AW 7075. The tool was a 0.1 mm diameter double-edged ball mill made of sintered carbide and coated with TiSiN. The cutting conditions were determined according to the tool manufacturer’s recommendations. To compare the achieved accuracies, the same microstructure was fabricated using PLA technology. For subsequent replication of the sample, the negative of the selected microstructure was created and machined. Subsequently, a positive microstructure was created using the silicone impression material by the replication process. This paper and the experiments performed extend the technical knowledge in the field of manufacturing surface functional structures and confirm the possibility of manufacturing the designed structures using chip and laser machining technology, with achieved discontinuities in the range of 3 to 50 μm. They also highlight the issues of replication of such structures with respect to critical manufacturing locations (geometrical parameters of the structures affecting the functional properties of the structure, venting, replica defects, etc.).

Influence of Brönsted Acid Sites on Activated Carbon-Based Catalyst for Acetylene Dimerization.

Activated carbon (AC) has been widely used as a support material with both tunable acidity and abundant functional groups for solid acid catalysts in various chemical processes such as acetylene dimerization. A facile, mild acid modification method that directly activates AC to generate rich defects and oxygen functional group surface structures with Brönsted acid sites and an enhanced conductivity is presented here. Impressively, the catalyst with optimized Brönsted acid sites and an enhanced dispersion of active components exhibited a superior acetylene dimerization catalytic activity. Moreover, theoretical calculations indicated that an increase in hydrogen concentration could inhibit the formation of coke. This research offered a feasible potential way to devise and construct a carbon-based solid acid catalyst with an excellent catalytic performance.

Bio-functional hydroxyapatite-coated 3D porous polyetherketoneketone scaffold for enhanced osteogenesis and osteointegration in orthopedic applications.

Polyetherketoneketone (PEKK), a high-performance thermoplastic special engineering material, maintains bone-like mechanical properties and has received considerable attention in the biomedical field. The 3D printing technique enables the production of porous scaffolds with a honeycomb structure featuring precisely controlled pore size, porosity and interconnectivity, which holds significant potential for applications in tissue engineering. The ideal pore architecture of porous PEKK scaffolds has yet to be elucidated. Porous PEKK scaffolds with five pore sizes P200 (225 ± 9.8 μm), P400 (411 ± 22.1 μm), P600 (596 ± 23.4 μm), P800 (786 ± 24.2 μm) and P1000 (993 ± 26.0 μm) were produced by a 3D printer. Subsequently, the optimum pore size, the P600, for mechanical properties and osteogenesis was selected based on in vitro experiments. To improve the interfacial bioactivity of porous PEKK scaffolds, hydroxyapatite (HAp) crystals were generated via in situ biomimetic mineralization induced by the phase-transited lysozyme coating. Herein, a micro/nanostructured surface showing HAp crystals on PEKK scaffold was developed. In vitro and in vivo experiments confirmed that the porous PEKK-HAp scaffolds exhibited highly interconnected pores and functional surface structures that were favorable for biocompatibility and osteoinductivity, which boosted bone regeneration. Therefore, this work not only demonstrates that the pore structure of the P600 scaffold is suitable for PEKK orthopedic implants but also sheds light on a synergistic approach involving 3D printing and biomimetic mineralization, which has the potential to yield customized 3D PEKK-HAp scaffolds with enhanced osteoinductivity and osteogenesis, offering a promising strategy for bone tissue engineering.

The Plant Leaf: A Biomimetic Resource for Multifunctional and Economic Design

As organs of photosynthesis, leaves are of vital importance for plants and a source of inspiration for biomimetic developments. Leaves are composed of interconnected functional elements that evolved in concert under high selective pressure, directed toward strategies for improving productivity with limited resources. In this paper, selected basic components of the leaf are described together with biomimetic examples derived from them. The epidermis (the "skin" of leaves) protects the leaf from uncontrolled desiccation and carries functional surface structures such as wax crystals and hairs. The epidermis is pierced by micropore apparatuses, stomata, which allow for regulated gas exchange. Photosynthesis takes place in the internal leaf tissue, while the venation system supplies the leaf with water and nutrients and exports the products of photosynthesis. Identifying the selective forces as well as functional limitations of the single components requires understanding the leaf as an integrated system that was shaped by evolution to maximize carbon gain from limited resource availability. These economic aspects of leaf function manifest themselves as trade-off solutions. Biomimetics is expected to benefit from a more holistic perspective on adaptive strategies and functional contexts of leaf structures.

Iron-modified biochar reduces nitrogen loss and improves nitrogen retention in Luvisols by adsorption and microbial regulation

Nitrogen (N) loss poses a great threat to global environmental sustainability. The application of modified biochar is a novel strategy to improve soil nitrogen retention and alleviate the negative effects caused by N fertilizers. Therefore, in this study iron modified biochar was used as a soil amendment to investigate the potential mechanisms of N retention in Luvisols. The experiment comprised five treatments i.e., CK (control), 0.5 % BC, 1 % BC, 0.5 % FBC and 1 % FBC. Our results showed that the intensity of functional groups and surface structure of FBC was improved. The 1 % FBC treatment showed a significant increment in soil NO3−-N, dissolved organic nitrogen (DON), and total nitrogen (TN) content by 374.7 %, 51.9 %, and 14.4 %, respectively, compared with CK. The accumulation of N in cotton shoots and roots was increased by 28.6 % and 6.6 % with 1 % FBC addition. The application of FBC also stimulated the activities of soil enzymes related to C and N cycling i.e., β-glucosidase (βG), β-Cellobiohydrolase (CBH), and Leucine aminopeptidase (LAP). In the soil treated with FBC, a significant improvement in the structure and functions of the soil bacterial community was found. FBC addition altered the taxa involved in the N cycle by affecting soil chemical properties, especially for Achromobacte, Gemmatimonas, and Cyanobacteriales. In addition to direct adsorption, the regulation of FBC on organisms related to N-cycling also played an important role in soil nitrogen retention.

Formation of Laser-Induced Periodic Surface Structures on Reaction-Bonded Silicon Carbide by Femtosecond Pulsed Laser Irradiation

Reaction-bonded silicon carbide (RB-SiC) is an excellent engineering material with high hardness, stiffness, and resistance to chemical wear. However, its widespread use is hindered due to the properties mentioned above, making it difficult to machine functional surface structures through mechanical and chemical methods. This study investigated the fundamental characteristics of laser-induced periodic surface structures (LIPSSs) on RB-SiC via femtosecond pulsed laser irradiation at a wavelength of 1028 nm. Low-spatial-frequency LIPSS (LSFL) and high-spatial-frequency LIPSS (HSFL) formed on the surface along directions perpendicular to the laser polarization. SiC grains surrounded by a large amount of Si show a reduced threshold for LIPSS formation. By varying laser fluence and scanning speed, HSFL–LSFL hybrid structures were generated on the SiC grains. Transmission electron microscopy observations and Raman spectroscopy were carried out to understand the formation mechanism of the hybrid LIPSS. A possible mechanism based on the generation of multiple surface electromagnetic waves due to the nonlinear response of SiC was proposed to explain the hybrid structure formation. Furthermore, the direction of laser scanning with respect to laser polarization affects the uniformity of the generated LIPSS.

Hierarchical Colloidal Self-Assembly on Lattice-Mismatched Moiré Patterns.

Extending atomic epitaxy concepts to colloidal systems for realizing functional surface structures has recently piqued scientific interest. Akin to the growth of ordered metal clusters on graphene moiré, spatially ordered colloidal crystals have been realized on soft lithographically fabricated moiré patterns. In addition to moiré periodicity, lattice misfit strain can bring about a further level of hierarchy in colloidal self-assembly, although its role in self-organization remains unexplored. Here, we demonstrate the self-organized growth of micrometer-sized colloidal pyramid arrays with lateral order extending over millimeter length scales on lattice-mismatched moiré patterns. By probing the film growth dynamics with single-particle resolution, we uncovered the interplay between lattice misfit strain and topographically varying surface potential within the moiré unit cell, which significantly alters the nucleation process. We also show that the structural organization of colloids within moiré regions primarily depends on the moiré angle, and by tuning it, multiple levels of hierarchy can be achieved.

Efficient removal of hexavalent chromium ions from simulated wastewater by functionalized anion exchange resin: Process optimization, isotherm and kinetic studies

In the present study, hazardous heavy metal ion hexavalent chromium (Cr(VI)) was removed from aqueous solution by using Indion GS-300 (IGS-300), strong base anion exchange resin. The process parameters for the removal of Cr(VI) were optimized using response surface methodology (RSM) approach. Procured resin was analyzed by various techniques like FTIR, and FESEM associated with elemental analysis which provided functional groups and surface structure of the adsorbents. Various batch adsorption experiments were conducted by varying parameters such as Cr(VI) concentrations from 5 mg/L to 45 mg/L, 2 to 10 pH, IGS-300 resin dosage between 0.38 and 1.88 g/L, and temperature of 20–40 °C with 90 min fixed contact time. Fixed time was determined from preliminary study of the present work. The maximum adsorption capacity of IGS-300 resin was found 294.11 mg/g and 98.20% of removal achieved with optimum conditions of 4 pH, 1.50 g/L adsorbent dosage, 15 mg/L Cr(VI) concentration and 35 °C temperature. The experimental data was found with best fitted Freundlich Isotherm and pseudo second order kinetic model. Regeneration study was also done on the adsorbed resins using different solution includes water, 0.1 M HCl, and 0.1 M NaOH. Up to 3 cycles of 0.1 M NaOH treatment, resin showed >50% Cr(VI) removal in aqueous solution whereas water and HCl were found less effective on third cycle. Therefore, this study found that IGS-300 resin is more efficient adsorbent for the removal of Cr(VI) from aqueous solutions and possessing highly significant regeneration capacity.

Isolation and characterization of exopolysaccharide derived from Lacticaseibacillus paracasei AS20(1) with probiotic potential and evaluation of its antibacterial activity.

This study was done to find exopolysaccharide (EPS)-producing lactic acid bacteria (LAB) against foodborne pathogens. Isolated LAB were screened to find the ones with the ability to produce antibacterial EPS against foodborne pathogens. Among tested EPSs, EPS of AS20(1) isolate showed inhibitory effects on the growth of Listeria monocytogenes (MIC = 0·935 mg ml-1 , MBC = 0·935 mg ml-1 ), Yersinia enterocolitica (MIC = 12·5 mg ml-1 , MBC = 50 mg ml-1 ) and Bacillus cereus (MIC = 6·25 mg ml-1 , MBC = 12·5 mg ml-1 ). According to 16S rRNA sequencing, AS20(1) showed the closest similarity to Lacticaseibacillus paracasei (100%). This antibacterial EPS showed negligible toxicity (4·4%-5·2%) against red blood cells. Lacticaseibacillus paracasei AS20(1) showed probiotic properties, including high acid resistance, hydrophobicity (47·5%), autoaggregation and coaggregation with foodborne pathogens. Also, L. paracasei AS20(1) showed no haemolysis activity and antibiotic resistance. Characterization of antibacterial EPS revealed that it is a heteropolysaccharide with various functional groups, amorphous structure, and smooth surface, sheet and compact structure, which can be suitable for food packaging. L. paracasei AS20(1) and its antimicrobial EPS can be used to make functional food.

An insight on Vietnamese bio-waste materials as activated carbon precursors for multiple applications in environmental protection

Abstract Vietnam is known as an agricultural country with a variety of agricultural crops. In addition to agricultural by-products, bio-waste is the by-product from livestock waste, forestry, industry, and daily life. They affect the soil, water, and air environment by self-degradation processes in the environment. Therefore, researchers have come up with ideas for the usage of the by-products to decrease the amount of waste and minimize the environmental effects. In Vietnam, the by-products were used by researchers to produce bio-ethanol, fertilizers, composites, and activated carbon (AC). AC is one of the materials used to rapidly reduce the number of agricultural by-products by researchers. The synthesis process is optimized for the highest yield, while the physicochemical properties are also clearly analyzed through the X-ray diffraction, Fourier transform infrared, and Bacterial endotoxin testing assays. The average recorded specific surface area was about 300 m2 g−1. The functional groups and surface structure showed that the material has an amorphous structure with –OH, –CH, –CC, –C═C, –C═O groups. The AC from agricultural waste had been studied and applied to treat pollutants present in water.

Multifunctional Surface Construction for Long-Term Cycling Stability of Li-Rich Mn-Based Layered Oxide Cathode for Li-Ion Batteries.

Li-rich Mn-based layered oxides (LMLOs) are promising cathode material candidate for the next-generation Li-ion batteries (LIBs) of high energy density. However, the fast capacity fading and voltage decay as well as low Coulombic efficiency caused by irreversible oxygen release and phase transition during the electrochemical process hinder their practical application. To solve these problems, in the present study, a multifunctional surface construction involving a coating layer, spinel-layered heterostructure, and rich-in oxygen vacancies is successfully conducted by a facile thermal reduction of the LMLO particles with potassium borohydride (KBH4 ) as the reducing agent. The multifunctional surface structure plays synergistic effects on suppressing the interface side reaction, reducing the dissolution of transition metal, increasing electron conductivity and lithium diffusion rate. As a result, electrochemical performances of the LMLO cathode are effectively enhanced. With optimization of the addition of KBH4 , the electrode delivers a reversible capacity of 280 mAh g-1 at 0.1 C, which maintains after 100 cycles. The capacity retention with respect to the initial capacity is as high as 98% at 1 C after 400 cycles. The present work provides insights into designing a highly effective functional surface structure of LMLO cathode materials for high-performance LIBs.

Plowing-Extrusion Processes and Performance of Functional Surface Structures of Copper Current Collectors for Lithium-Ion Batteries

Most copper current collectors for commercial lithium-ion batteries (LIBs) are smooth copper foils, which cannot form a stable and effective combination with electrode slurry. They are likely to deform or fall off after long-term operation, resulting in a sharp decline in battery performance. What is worse is that this condition inevitably causes internal short circuits and thus brings about security risks. In this study, a process route of fabricating the functional surface structures on the surface of a copper collector for LIBs by twice-crisscross micro-plowing (TCMP) is proposed, which provides a new idea and an efficient method to solve the above problems from the perspective of manufacturing. The finite element simulation of TCMP combined with the cutting force test and morphological characterization is conducted to verify the forming mechanism of the surface structures on a copper sheet and its relationship with the processing parameters. The influence of several key processing parameters on the surface characteristics of the copper sheet is comprehensively explored. A series of functions is tested to obtain the optimal parameters for performance improvement of the current collector. Results show that the structured copper sheet with the cutting distance of 250 μm, cutting depth of 80 μm, and cutting crossing angle of 90° enables the best surface features of the current collector; the contact angle reaches 0°, the slurry retention rate is up to 89.2%, and the friction coefficient reaches 0.074. The battery using the as-prepared structured copper sheet as the current collector produces a specific capacity of 318.6 mAh/g after 50 cycles at a current density of 0.2 C, which is 132.7% higher than the one based on a smooth surface. The capacity reversibility of the sample with the new current collector is much better than that of the traditional samples, yielding a lower impedance.

Comparative analysis of three kinds of extraction kinetic models of crude polysaccharides from Codonopsis pilosula and evaluate the characteristics of crude polysaccharides.

In this study, the second-order model, Fick’s second law of diffusion, and the Peleg model were used to evaluate the extraction kinetic model of polysaccharide (CPP) from Codonopsis pilosula. The characteristic functional groups, surface structure, and physical and chemical properties of CPP were analyzed by multi-spectroscopic and microscopic techniques. The results showed that the extraction process agreed well with the second-order model, Fick’s second diffusion law, and Peleg model. Rheological tests showed that CPP exhibited different viscosity changes under different conditions (Solution viscosity was inversely proportional to temperature, time, etc.; proportional to polysaccharide concentration, Na+ content, etc.). CPP was composed of molecular aggregates composed of small particles, with more pore structure and basically completely decomposed at 130 °C. The hypoglycemic study showed that CPP had a strong inhibitory effect on α-glycosidase than α-amylase. The morphology and subsequent structural features, anti-diabetic potential, and rheological properties of CPP were revealed to provide a theoretical basis for the development of pharmaceutical preparations or health food and functional food for the treatment of diabetes.Graphic Supplementary InformationThe online version contains supplementary material available at 10.1007/s13399-022-02518-w.

Addition of dissimilar metal nodes to improve the electrochemical performance of MOF as a supercapacitor

Supercapacitors benefit from their high power density and long cycle life and are on the road of rapid development. Metal-organic framework (MOF) with abundant energy storage active sites (metal nodes, benzene-containing functional groups, pores and surface structure) has become a member of the library of supercapacitor electrode materials. However, the poor conductivity of most MOFs leads to unsatisfactory rapid charge and discharge capabilities and instability in cycles caused by uneven electron transfer. Here, we newly reported a three-dimensional trimetallic MOF (MnCoNi-MOF) based on 1,2,4,5-benzenetetracarboxylic acid ligand, which has better conductivity and larger specific surface area than monometallic MOF (Ni-MOF). Attributable to more active sites, MnCoNi-MOF as an electrode material has a specific capacitance of 655 F g−1 at 1 A g−1, which is much higher than Ni-MOF (95 F g−1). In addition, benefiting from the multi-metal synergistic effect, MnCoNi-MOF also exhibits excellent rate performance and durability (92.3% capacity retention after 10,000 cycles). After assembled into a hybrid capacitor with activated carbon, it delivers an energy density of 61 Wh kg−1 at 844 W kg−1, accompanied by a capacity decay of only 1.7% after 2000 cycles. The promising results prove that increasing the metal active center of MOF can greatly improve the energy storage performance. In the long term, this research would be expandable to a wide range of transition-organometallic materials for energy storage paradigm.

Travelling Wave Generation of Wrinkles on the Hydrogel Surfaces.

The dynamic and static properties of structured surfaces have important functions in nature. In particular, wrinkles have important static roles, for example, increasing surface area, but dynamic roles of wrinkles remain poorly understood. Specifically, to understand and utilize the dynamic functions of wrinkles, it is necessary to observe wrinkle formation directly. In this study, a polyion complex (PIC) is formed on a hydrogel surface by electrophoresis, and the process of wrinkle formation through a transparent electrode is directly observed. By quantitative analysis of the wavelength and amplitude of wrinkles, it is found that the wrinkles move randomly in a wavy pattern in the initial stage of growing process. Furthermore, the direction of wavy motion of wrinkles is controlled by the compression of hydrogels in the in-plane direction. The present study provides important insights into the fabrication of wrinkled surfaces with a controlled flow direction; opening the possibility for active wrinkles used in the development of functional surface structures as actuators that are capable of transporting small objects in water.

New Progress and Development Trend of Manufacturing of Functional Surface Structure

New Progress and Development Trend of Manufacturing of Functional Surface Structure

Glycocalyx Curving the Membrane: Forces Emerging from the Cell Exterior.

Morphological transitions are typically attributed to the actions of proteins and lipids. Largely overlooked in membrane shape regulation is the glycocalyx, a pericellular membrane coat that resides on all cells in the human body. Comprised of complex sugar polymers known as glycans as well as glycosylated lipids and proteins, the glycocalyx is ideally positioned to impart forces on the plasma membrane. Large, unstructured polysaccharides and glycoproteins in the glycocalyx can generate crowding pressures strong enough to induce membrane curvature. Stress may also originate from glycan chains that convey curvature preference on asymmetrically distributed lipids, which are exploited by binding factors and infectious agents to induce morphological changes. Through such forces, the glycocalyx can have profound effects on the biogenesis of functional cell surface structures as well as the secretion of extracellular vesicles. In this review, we discuss recent evidence and examples of these mechanisms in normal health and disease.

Adsorptive Removal of Cesium Ions Using Prussian Blue Immobilized Coffee Ground Biochar

Objectives: Among various radioactive contaminants, radioactive cesium is one of the most harmful radionuclides that causes human health issues due to its high emission of gamma-ray, high solubility, high mobility, high fission yield, and long half-life. Different kinds of adsorbents have been developed for the removal of cesium from radioactive wastewater. Especially, biochar has attracted great attention as a potential adsorbent in the treatment of pollutants and for water purification. In addition, Prussian blue is a cubic lattice structure that contains a cage size similar to the hydrated cesium ionic radius, indicating it can selectively remove cesium ions. Therefore, the aim of this study is to investigate the cesium adsorption performance of synthesized Prussian blue-immobilized coffee ground biochar (PB-CGBC) under various experimental conditions for cesium removal from radioactive wastewater.Methods: After wasted coffee ground was washed and dried, it was heated at 400℃ with 10℃/min of heating rate and 5 h of retention time in a furnace with little or no available air. The PB-CGBC was synthesized using a facile co-precipitation method. Fourier transform-infrared spectroscopy, X-ray diffractometer, field emission-transmission electron microscope, Brunauer-Emmett-Teller, and zeta potential analyzer were used to analyze physico-chemical characteristics and surface structure of the synthesized adsorbents. The kinetic and equilibrium experiments of cesium adsorption on PB-CGBC were carried out and the effect of pH, temperature, initial cesium concentration, and contact time were also investigated in a batch system.Results and Discussion: The characteristic analysis clearly confirmed the successful synthesis of PB-CGBC, indicating its abundant functional groups and special surface structure. In the batch study, it was found that the cesium adsorption onto the PB-CGBC was exothermic nature. The Elovich kinetic model and Temkin isotherm also provided a good correlation with the cesium adsorption reaction onto the PB-CGBC. The maximum adsorption capacity of PB-CGBC for cesium was 129.57 mg/g at 15℃ and pH 8 at 40 mM of an initial cesium concentration, which was one of the highest values among those of previously reported adsorbents.Conclusions: In this study, the PB-CGBC was synthesized by immobilizing Prussian blue to the surface of coffee ground biochar and successfully applied for the adsorptive removal of cesium ions. Based on the experimental results, the synthesized PB-CGBC can be served as a great adsorbent for treatment of wastewater polluted with radioactive cesium.

Effect of Stoichiometric Composition on the Functional Characteristics of Thin-Film Surface Structures on Gyroscope Components

The results of research into the effect of stoichiometry on the properties of titanium nitride thin-film coatings on the components of floated and electrostatic gyroscopes are presented. The article also considers the results of research into the mechanical and optical characteristics of titanium nitride thin-film structures: microhardness, resistance to wear and friction, and image contrast, which is determined by the reflection coefficients of the titanium nitride base surface and the raster pattern generated by the method of local laser oxidation. The future and technological methods of generation of functional surface structures of niobium carbide and niobium nitride in the process of development of a rotor of a cryogenic gyroscope are discussed. It is shown that the formation of a coating of required composition requires a thermodynamic assessment of possible interactions during which structural-phase modification of the material is carried out, determined by the complex of possible topochemical reactions leading to the formation of compounds, including the ones with nonstoichiometric composition.

Stoichiometric composition of thin-film surface structures and its influence on the functional characteristics as regards gyroscopic devices

This article considers the research results of the effect of stoichiometry on the properties of titanium nitride thin-film coatings of the float and electrostatic gyroscopes. It presents the results of tests of such mechanical and optical characteristics of titanium nitride thin-film structures as microhardness, resistance to wear and friction, and image contrast determined by the reflection coefficients of a titanium nitride base surface and a raster pattern formed by local laser oxidation. When making a rotor of a cryogenic gyroscope, the prospects of use and technological methods for the formation of functional surface structures of niobium carbide and nitride are considered. It is shown that during the formation of coatings of the required composition, the most important is the thermodynamic estimation of possible interactions. These interactions allow us to accomplish the structural-phase modification of the material, which is determined by the complex of possible topochemical reactions leading to the formation of compounds, including non-stoichiometric composition.