Modification Technology Research Articles

Ternary modification of polymer-derived carbon from disposable diapers for advanced energy storage: Three birds with one stone

In order to improve the energy storage capacity of carbon materials, exploring advanced preparation and modification technologies for carbon materials has always been the primary challenge in this field. Herein, we report a novel and diversified modification strategy for carbon materials, which can simultaneously satisfy pore regulation, catalytic graphitization, and heteroatoms doping. By modifying the carbon materials derived from super absorbent polymer in baby disposable diapers, both supercapacitors and lithium-oxygen batteries have achieved excellent electrochemical performance. In the application of supercapacitors, it shows a large specific capacitance of 384.1 F g−1 at 0.5 A g−1 and an outstanding ultrastability with a capacitance retention of 99 % over 10,0000 cycles at 20 A g−1. For the application in lithium-oxygen batteries, a high discharge capacity of 13,589 mAh g−1 can be achieved. These attractive electrochemical properties demonstrate enormous potential for practical applications of the as-developed ternary-modified carbon materials.

Recent Progress in the Application of Ion Beam Technology in the Modification and Fabrication of Nanostructured Energy Materials.

The development of green, renewable energy conversion and storage systems is an urgent task to address the energy crisis and environmental issues in the future. To achieve high performance, stable, and safe operation of energy conversion and storage systems, energy materials need to be modified and fabricated through rationalization. Among various modification and fabrication strategies, ion beam technology has been widely used to introduce various defects/dopants into energy materials and fabricate various nanostructures, where the structure, composition, and property of prefabricated materials can be further accurately tailored to achieve better performance. In this paper, we review the recent progress in the application of ion beam technology in material modification and fabrication, focusing on nanostructured energy materials for energy conversion and storage including photo- (electro-) water splitting, batteries (solar cells, fuel cells, and metal-ion batteries), supercapacitors, thermoelectrics, and hydrogen storage. This review first provides a brief basic overview of ion beam technology and describes the classification and technological advantages of ion beam technology in the modification and fabrication of materials. Then, modification of energy materials by ion beams is reviewed mainly concerning doping and defect introduction. Fabrication of energy materials is also discussed mainly in terms of heterojunctions, nanoparticles, nanocavities, and other nanostructures. In particular, we emphasize the advantages of ion beam technology in improving the performance of energy materials. Finally, we point out our understanding of challenges and future perspectives in applying ion beam technology for the modification and fabrication of energy materials.

Synergistic Amelioration of Osseointegration and Osteoimmunomodulation with a Microarc Oxidation-Treated Three-Dimensionally Printed Ti-24Nb-4Zr-8Sn Scaffold via Surface Activity and Low Elastic Modulus.

Biomaterial scaffolds, including bone substitutes, have evolved from being primarily a biologically passive structural element to one in which material properties such as surface topography and chemistry actively direct bone regeneration by influencing stem cells and the immune microenvironment. Ti-6Al-4V(Ti6Al4V) implants, with a significantly higher elastic modulus than human bone, may lead to stress shielding, necessitating improved stability at the bone-titanium alloy implant interface. Ti-24Nb-4Zr-8Sn (Ti2448), a low elastic modulus β-type titanium alloy devoid of potentially toxic elements, was utilized in this study. We employed 3D printing technology to fabricate a porous scaffold structure to further decrease the structural stiffness of the implant to approximate that of cancellous bone. Microarc oxidation (MAO) surface modification technology is then employed to create a microporous structure and a hydrophilic oxide ceramic layer on the surface and interior of the scaffold. In vitro studies demonstrated that MAO treatment enhances the proliferation, adhesion, and osteogenesis capabilities on the scaffold surface. The chemical composition of the MAO-Ti2448 oxide layer is found to enhance the transcription and expression of osteogenic genes in bone mesenchymal stem cells (BMSCs), potentially related to the enrichment of Nb2O5 and SnO2 in the oxide layer. The MAO-Ti2448 scaffold, with its synergistic surface activity and low stiffness, significantly activates the anti-inflammatory macrophage phenotype, creating an immune microenvironment that promotes the osteogenic differentiation of BMSCs. In vivo experiments in a rabbit model demonstrated a significant improvement in the quantity and quality of the newly formed bone trabeculae within the scaffold under the contact osteogenesis pattern with a matched elastic modulus. These trabeculae exhibit robust connections to the external structure of the scaffold, accelerating the formation of an interlocking structure between the bone and implant and providing higher implantation stability. These findings suggest that the MAO-Ti2448 scaffold has significant potential as a bone defect repair material by regulating osteoimmunomodulation and osteogenesis to enhance osseointegration. This study demonstrates an optional strategy that combines the mechanism of reducing the elastic modulus with surface modification treatment, thereby extending the application scope of β-type titanium alloy.

Exploring The Future of Prosthetics and Orthotics: Harnessing The Potential of 3D Printing.

This paper explores the transformative impact of 3D printing on Orthotics and Prosthetics, focusing on enhancing patient outcomes and clinical efficiency. Over the past decade, the integration of additive manufacturing has revolutionized device fabrication, particularly in diagnostic socket production, leading to significant time reductions in patient care. This article addresses challenges such as material limitations and the need for equivalent strength to traditional sockets, exploring the use of PETG filaments and advanced printers. It emphasizes the role of digital scanning and model modification technology, highlighting affordable solutions like Structure Sensor Scanners and iPhone-based capture systems in shaping the digital workflow. The importance of a standardized digital workflow in clinical settings is discussed, showcasing reduced practitioner time and improved patient care. The paper concludes by outlining ongoing efforts to enhance patient care through automation and flexible prints. In summary, this paper provides a concise overview of the impactful advancements in Orthotics and Prosthetics through 3D printing, highlighting its potential for improved clinical efficiency and patient outcomes.

Numerical investigation on pool boiling heat transfer with trapezoidal/inverted trapezoidal micro-pillars using LBM

Pool boiling with high-efficient heat transfer process is crucial to chemical engineering, nuclear engineering, electronic cooling, and other energy conversion applications. Surface modification technology has attracted more attention in recent years as a simple and reliable boiling enhancement technique. Most of the studies using surface modification technology have focused on the enhancement effect of rectangular micro-structures, only a few researchers have adequately investigated the enhancement effects on pool boiling heat transfer and mechanisms of other complex micro-structures (like circle, trapezoid, or inverted trapezoid). In the present study, the pool boiling processes on surfaces with trapezoidal/inverted trapezoidal micro-pillars were numerically investigated using lattice Boltzmann method (LBM). The bubble dynamics and heat transfer characteristics during the pool boiling processes on surfaces with different pillar bottom angles (30° ≤ θ ≤ 135°) were compared under different wall-superheat conditions. The orthogonal tests were adopted on micro-pillars to optimize the geometric parameters, including the bottom angle of the micro-pillar, the bottom width of the micro-pillar, the number of the micro-pillar, and the height of the micro-pillar. A new CHF correlation on the mixed wettability surface with trapezoidal/inverted trapezoidal micro-pillars was proposed. It can be found that the main mechanism of nucleate boiling heat transfer on the micro-pillars is the evaporation of the microlayer, and the pillar bottom angle reveals a remarkable effect on the pool boiling performance on the mixed wettability surfaces. The surface of θ = 135° has the minimum wall-superheat at the onset of nucleate boiling (ONB). Within a wide range of wall-superheat conditions, the heat transfer efficiency of pool boiling firstly increases with the increasing of the bottom angle of the micro-pillar and subsequently decreases. The surface of θ = 60° has the highest critical heat flux (CHF). The surface of θ = 90° has the highest heat transfer efficiency in the film boiling process. The results of orthogonal tests suggested that the bottom angle of the micro-pillar is the most significant influential factor, and the optimal geometrical combinations were proposed. The new CHF correlation has acceptable accuracy in predicting the CHF on surfaces with trapezoidal/inverted trapezoidal pillars, which provides guidance for the design and optimization of micro-structured surface modification in various pool boiling applications.

A hydrogen adsorbing PUR/Pd nanocomposite nanofibrous membrane prepared by electrospinning technology

A graphic representation of applied electrospinning technology and methods of one-step and multi-step modification of nanofibrous membranes for targeted hydrogen sorption.

Development of plasma technology for the preparation and modification of energy storage materials.

The development of energy storage material technologies stands as a decisive measure in optimizing the structure of clean and low-carbon energy systems. The remarkable activity inherent in plasma technology imbues it with distinct advantages in surface modification, functionalization, synthesis, and interface engineering of materials. This review systematically expounds upon the principles, classifications, and application scenarios of plasma technology, while thoroughly discussing its unique merits in the realm of modifying electrode materials, solid-state electrolytes, and conductive carbon materials, which are widely used in lithium-ion batteries, sodium ion batteries, metal air batteries and other fields. Finally, considering the existing constraints associated with lithium-ion batteries, some application prospects of plasma technology in the energy storage field are suggested. This work is of great significance for the development of clean plasma technology in the field of energy storage.

Modeling of Smart Bio-Medical Active Polymeric Hydrogel Transdermal Materials

In this article, effective 3D printing modeling technology of smart bio-medical polymeric hydrogel transdermal materials based on gelatin and sodium alginate, modified by humic acids, was researched. Such smart biologically active polymeric hydrogel materials showed interesting applicability in tissue engineering fields due to their intrinsic biological compatibility, adaptability, and capacity to replicate the extracellular matrix environment. A literature review was carried out and proved that 3D printing modeling technology is a perspective for the functional effect on the smart bio-medical polymer hydrogel transdermal properties. Smart biomedical polymeric transdermal hydrogel patches were produced using a micromolding technique. A stereolithography (SLA) 3D printer was used to print the master mold. The three-stage technology of lignite humic acids modification of smart biologically active polymeric hydrogel transdermal microneedles patches based on gelatin, hydroxypropyl methylcellulose, and sodium alginate was designed. It was shown that modification of gelatin-sodium alginate and hydroxypropyl methylcellulose-sodium alginate biopolymer hydrogels by humic acids makes it possible to obtain smart biologically active polymeric hydrogel transdermal materials with an increased swelling degree and ability to improve the skin moisture-lipid balance (from the initial moisture 34–36 % and fatness 8–10, they increase to 58–66 % and 52–60 %). Finally, the developed 3D printing modeling technology of smart bio-medical polymeric hydrogel transdermal materials hydrogel based on gelatin sodium alginate, modified by humic acids, is a transdermal material with required properties.

Novel fabrication of mixed wettability micromodels for pore-scale studies of fluid-rock interactions.

Wettability plays a crucial role in multiphase fluid flow in porous media, impacting various geological applications such as hydrocarbon extraction, aquifer remediation, and carbon dioxide sequestration. Microfluidic methods have attracted interest for their capacity to explore and visualize essential multiphase flow dynamics at the pore level, mimicking actual rock pore structures. However, creating micromodels with representative mixed wettability is currently a challenge. Existing technology is limited to producing micromodels with a singular wettability, either water-wet or oil-wet, leaving a gap in representing mixed-wet scenarios. In this study, we introduce a novel method to fabricate microfluidic devices with controlled spatial distribution of wettability at the micro-scale, mimicking actual configurations of mixed-wet rocks arising from varied mineralogy and pore structures. The proposed method combines the soft lithography process with thin film deposition techniques. The micromodels were designed to mimic the pore network of actual reservoir rocks, and a silicon substrate served as the foundation for the photolithography process optimization and wettability alteration methodology. Perfluorodecyltrichlorosilane coating was applied using molecular vapor deposition technology for surface wettability modification. The coated parts of the microdevice substrate altered the localized wetting state of the silicon towards hydrophobic, while the wettability remained unchanged in the non-coated areas. We utilized surface measurements, including contact angle, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, and atomic force microscopy, to assess the wettability, composition, thickness, shape, roughness, and overall quality of the coating. Our fabrication process successfully produced a microfluidics device with tailored mixed-wet attributes at the micro-scale, which is, to our best knowledge, the first achievement in the field. This method enables the replication of mixed-wet characteristics commonly seen in various applications, such as carbonates and shales within underground rocks, providing a more accurate examination of fundamental multiphase fluid dynamics and rock interactions at the pore level.

Influence of surface micro-oxidation on the formability of pure copper powders by selective laser melting

The absorption of laser energy by pure copper powders has a huge impact on the formation of high quality pure copper parts by selective laser melting. In this paper, surface modification technology was used to treat pure copper powder to improve the laser absorption effect of pure copper powder. It was found that modifying the surface of pure copper powder to generate a layer of CuO film effectively improved the absorption of laser energy by pure copper powder. Uniform and dense CuO films improved the quality of selective laser melting pure copper parts, which solved the problem of preparing pure copper powders for selective laser melting of high-density parts. The microstructure of selective laser melting high-density pure copper parts consisted of fine columnar and cellular crystals. The presence of subcrystals and dislocations was found in localized areas. The results of the physical phase analysis showed that the CuO phase existed in the parts prepared from the surface-modified pure copper powder, and the presence of the nano-CuO phase also enhanced, which effectively improved the microstructure and properties of the constituent selective laser melting pure copper parts.

A review of the utilization of modified flour: Local food potential

Indonesia's wheat imports reached 11.22 million tons of wheat, ranked second in the world based on data from the United States Department of Agriculture (USDA) in 2021/2022. Wheat flour, which comes from wheat endosperm and has a high gluten content, is a taboo for those with celiac disease. The purpose of this review is to examine the development and potential of local food through flour modification to reduce the use of gluten, especially in food products such as bread, biscuits and noodles. Flour modification with chemical modification, physical modification, and biological modification technology methods can improve the characteristics and increase the physicochemical properties of the flour produced, while providing an integral role in cost savings, encouraging the utilization of local food, encouraging local farmers, and improving the agricultural system.

Engineered exosomes: a potential therapeutic strategy for septic cardiomyopathy.

Septic cardiomyopathy, a life-threatening complication of sepsis, can cause acute heart failure and carry a high mortality risk. Current treatments have limitations. Fortunately, engineered exosomes, created through bioengineering technology, may represent a potential new treatment method. These exosomes can both diagnose and treat septic cardiomyopathy, playing a crucial role in its development and progression. This article examines the strategies for using engineered exosomes to protect cardiac function and treat septic cardiomyopathy. It covers three innovative aspects: exosome surface modification technology, the use of exosomes as a multifunctional drug delivery platform, and plant exosome-like nanoparticle carriers. The article highlights the ability of exosomes to deliver small molecules, proteins, and drugs, summarizing several RNA molecules, proteins, and drugs beneficial for treating septic cardiomyopathy. Although engineered exosomes are a promising biotherapeutic carrier, they face challenges in clinical application, such as understanding the interaction mechanism with host cells, distribution within the body, metabolism, and long-term safety. Further research is essential, but engineered exosomes hold promise as an effective treatment for septic cardiomyopathy.

Advances in Droplet-Based Microfluidic High-Throughput Screening of Engineered Strains and Enzymes Based on Ultraviolet, Visible, and Fluorescent Spectroscopy

Genetic engineering and directed evolution are effective methods for addressing the low yield and poor industrialization level of microbial target products. The current research focus is on how to efficiently and rapidly screen beneficial mutants from constructed large-scale mutation libraries. Traditional screening methods such as plate screening and well-plate screening are severely limited in their development and application due to their low efficiency and high costs. In the past decade, microfluidic technology has become an important high-throughput screening technology due to its fast speed, low cost, high automation, and high screening throughput, and it has developed rapidly. Droplet-based microfluidic high-throughput screening has been widely used in various fields, such as strain/enzyme activity screening, pathogen detection, single-cell analysis, drug discovery, and chemical synthesis, and has been widely applied in industries such as those involving materials, food, chemicals, textiles, and biomedicine. In particular, in the field of enzyme research, droplet-based microfluidic high-throughput screening has shown excellent performance in discovering enzymes with new functions as well as improved catalytic efficiency or stability, acid-base tolerance, etc. Currently, droplet-based microfluidic high-throughput screening technology has achieved the high-throughput screening of enzymes such as glycosidase, lipase, peroxidase, protease, amylase, oxidase, and transaminase as well as the high-throughput detection of products such as riboflavin, coumarin, 3-dehydroquinate, lactic acid, and ethanol. This article reviews the application of droplet-based microfluidics in high-throughput screening, with a focus on high-throughput screening strategies based on UV, visible, and fluorescence spectroscopy, including labeled optical signal detection screening, as well as label-free electrochemical detection, mass spectrometry, Raman spectroscopy, nuclear magnetic resonance, etc. Furthermore, the research progress and development trends of droplet-based microfluidic technology in enzyme modification and strain screening are also introduced.

The effect of modification with nanocompositions on the structure and properties of foundry silumins


 Abstract. Problem. The difficulty of solving the problem lies not only in the improved quality of casting alloys, but also in the development of recommendations for achieving stability of the chemical composition, refining the structure, and increasing the mechanical and technological properties of castings. Goal. The goal of the work is to achieve a stable dispersed structure and increase the complex of mechanical properties of foundry silumins. Methodology. Based on the Al – Si influence diagram, the choice of cast aluminum alloys for modification with nanocompositions is substantiated. The technology of modification with nanodisperse compositions consisted in introducing powders of the complex nanomodifier Mg2Si+SiС into the aluminum melt. A mixture of Mg2Si+SiC nanopowders with a particle size of 50...100 nm, obtained by plasma chemical synthesis, was mixed for several hours in a special attritor with successive pressing of modifier tablets on an automatic press. Results. The technological process of modifying aluminum melts with a complex modifier was developed, the temperature and time parameters of the process were determined. Brinell hardness was measured on samples of AL4 and AL4C alloys, 25x25 mm in size. As a result of the obtained data, it is observed that in the modified samples of the AL4 alloy, the hardness increased by 6.9%, and in the AL4C samples – by 4.8%. The obtained hardness measurement data are consistent with the results of testing the strength properties of alloys before and after modification. Originality. In the modified alloys, a higher fluidity than in the initial state and a homogeneous dispersed microstructure were obtained. Practical value. In the modified alloys, an increase in strength properties was achieved: σv by 9 - 10%; σ0.2 by 11-12%, while maintaining the level of plasticity. The impact strength of modified alloys is significantly increased by 20-30%. As a result of the conducted studies of the structure and properties of cast alloys AL4 and AL4C, the effect of modification with nanodisperse compositions was confirmed.

One-step fast fabrication of multi-layer quantum dot diffusion plate for stable display and ultra-long life, a novel quantum dot packaging strategy

Quantum dots (QDs), renowned for their distinctive optical and physical attributes, are extensively employed in diverse fields such as lighting, displays, electronics, sensors, and solar cells. Nonetheless, the susceptibility to light, oxygen, and moisture is a major obstacle to the development of QDs. Achieving simple, efficient, and universal modification or encapsulation for enhanced stability remains a challenge. Herein, a one-step fast fabrication of multi-layer quantum dot diffusion plate (QD-DP) with excellent barrier and optical properties was proposed, which is alternately stacked by MS-EVOH and MS-QDs layers. The barrier phase morphology undergoes a fiber-flake transition induced by the bidirectional tensile force field during multiplication, and layer-by-layer encapsulation synergistically enhances the barrier performance, photo-oxygen stability, thermal-oxygen stability, and fluorescence lifetime of QD-DP in backlight applications. Under high-power UV irradiation, the fluorescence intensity ofMS/MS-QD 128L dropped to 90 % (T90) in only about 10 minutes, while the T90 of MS-E/MS-QD 128L was close to 216 hours, improved more than 1200 times. Concurrently, the quantum dot diffusion plate (QD-DP), characterized by an alternating multi-layer structure, demonstrated an elevated backlight color gamut value of ∼ 120 % NTSC, outperforming conventional quantum dot light emitting diodes (QLED). Compared with existing QDs backlight modules, a simpler structure, more efficient preparation process, and longer fluorescence lifetime of QD-DP were achieved.Moreover, unlike prevalent modification or packaging technologies that only target specific QD types, our alternating multilayer coextrusion packaging technology is applicable to all kinds of QDs and is simple, efficient, and universal.It was believed that this work could provide new opportunities for all kinds of QDs encapsulation and application in many fields and will be the dawn of large-scale commercialization of QDs.

Innovative Developments in Lumbar Interbody Cage Materials and Design: A Comprehensive Narrative Review.

This review comprehensively examines the evolution and current state of interbody cage technology for lumbar interbody fusion (LIF). This review highlights the biomechanical and clinical implications of the transition from traditional static cage designs to advanced expandable variants for spinal surgery. The review begins by exploring the early developments in cage materials, highlighting the roles of titanium and polyetheretherketone in the advancement of LIF techniques. This review also discusses the strengths and limitations of these materials, leading to innovations in surface modifications and the introduction of novel materials, such as tantalum, as alternative materials. Advancements in three-dimensional printing and surface modification technologies form a significant part of this review, emphasizing the role of these technologies in enhancing the biomechanical compatibility and osseointegration of interbody cages. In addition, this review explores the increase in biodegradable and composite materials such as polylactic acid and polycaprolactone, addressing their potential to mitigate long-term implant-related complications. A critical evaluation of static and expandable cages is presented, including their respective clinical and radiological outcomes. While static cages have been a mainstay of LIF, expandable cages are noted for their adaptability to the patient's anatomy, reducing complications such as cage subsidence. However, this review highlights the ongoing debate and the lack of conclusive evidence regarding the superiority of either cage type in terms of clinical outcomes. Finally, this review proposes future directions for cage technology, focusing on the integration of bioactive substances and multifunctional coatings and the development of patient-specific implants. These advancements aim to further enhance the efficacy, safety, and personalized approach of spinal fusion surgeries. Moreover, this review offers a nuanced understanding of the evolving landscape of cage technology in LIF and provides insights into current practices and future possibilities in spinal surgery.

CATHODIC PLASMA ELECTROLYTIC DEPOSITION (CPED) TECHNIQUE FOR SURFACE STRENGTHENING OF TITANIUM AND TITANIUM ALLOYS: A MINI REVIEW

Due to the unique properties of titanium (Ti) and its alloys, it has a particularly wide range of applications in aerospace, automotive, medical and other fields. However, the problems of low surface hardness, high friction coefficient and low wear resistance of Ti alloys limit its development to a certain extent. The destruction of Ti and its alloys often occurs on the surface of materials such as wear damage, corrosion, and oxidation resistance. Therefore, the exploration and application of surface strengthening technology is particularly important. The cathodic plasma electrolytic deposition (CPED) technology, as a surface modification technology, can achieve better adhesion and facilitate the material to achieve better comprehensive performance. This paper briefly introduces the basic concepts, principles and development progress of CPED. Starting from the preparation of ceramic coatings, metal coatings, diamond-like carbon films and composite coatings, it summarizes the application of CPED in Ti and its alloys. Applications in alloys to improve thermal oxidation resistance, wear resistance, corrosion resistance, and film-based adhesion. At the end, its development in the new era environment is prospected.

BaSO4-Epoxy Resin Composite Film for Efficient Daytime Radiative Cooling.

Conventional cooling methods are based on active cooling technology by air conditioning, which consumes a large amount of energy and emits greenhouse gases. Radiative cooling is a novel promising passive cooling technology that uses external space as the cooling source and requires no additional energy consumption. Herein, we propose an approach to prepare highly dispersed BaSO4 nanoparticles (NPs) using a direct precipitation method combined with the in situ surface modification technology. The as-prepared PVP-modified BaSO4 NPs with an average size of 20 nm can be stably dispersed in ethanol for more than 6 months and then were used as building blocks to prepare spherical BaSO4 clusters with an average size of 0.9 μm using a scalable spray drying technique. The BaSO4 NPs/clusters (mass ratio 1:1) were used for preparing radiative cooling epoxy resin film, showing a high solar reflectance of 71% and a high sky window emissivity of 0.94. More importantly, this composite film displays superior radiative cooling performance, which can reduce the ambient temperature by 13.5 °C for the indoor test and 7 °C for the outdoor test. Compared with the commercial BaSO4 filled film, our BaSO4-epoxy resin composite film offers advantages not only in radiative cooling but also in mechanical properties with a 16.6% increase of tensile strength and 40.1% increase of elongation at break, demonstrating its great application potential in the field of building air conditioning.

Research Progress of Aluminum Alloy Welding/Plastic Deformation Composite Forming Technology in Achieving High-Strength Joints.

Fusion welding causes joint deterioration when joining aluminum alloys, which limits the use of aluminum alloy components in high-end equipment. This paper focuses on an overview of how to achieve high-strength aluminum alloy welded joints using welding/plastic deformation composite forming technology. The current technology is summarized into two categories: plastic deformation welding and plastic deformation strengthening. Plastic deformation welding includes friction stir welding, friction welding, diffusion welding, superplastic solid-state welding, explosive welding, and electromagnetic pulse welding. Plastic deformation strengthening refers to the application of plastic deformation to the weld seam or heat-affected zone, or even the whole joint, after welding or during welding, including physical surface modification and large-scale plastic deformation technology. Important processing parameters of plastic deformation welding and their effects on weld quality are discussed, and the microstructure is described. The effect of plastic deformation strengthening technology on the microstructure and performance evolution, including the hardness, tensile strength, fatigue property, residual stress, and hot cracking of aluminum alloy welded joints, and its evolution mechanism are systematically analyzed. Finally, this paper discusses the future development of plastic deformation strengthening technology and anticipates growing interest in this research area.

Molecular modification based on site-directed mutagenesis improves the substrate specificity of β-ester acyltransferase for L-carnosine synthesis

L-carnosine is a natural β-peptide compound with a wide range of important physiological functions. In this study, β-ester acyltransferase (As DmpA) can catalyze the reaction of β-amino acid methyl ester and β-amino acid methyl ester to form β-peptides and can also catalyze the reaction of β-amino acid methyl ester and L-histidine to form L-carnosine. Therefore, the reaction system will produce a variety of β-peptides, including L-carnosine. To solve this problem, the substrate specificity of As DmpA was improved by molecular modification to further increase the catalytic synthesis yield of L-carnosine. It was found that L341 W, L341K and L341R in saturated mutations increased the ability to catalyze L-carnosine synthesis. It was also found that the high proportion of L-histidine in the reaction system was conducive to the synthesis of L-carnosine. When the concentration ratio of L-histidine to β-alanine methyl ester hydrochloride is 140:10, the conversion rate of L-carnosine can reach more than 90%. When the concentrations of L-histidine and β-alanine methyl ester hydrochloride were 140 mM and 210 mM, respectively, the concentration of L-carnosine reached 105 mM by adding β-alanine methyl ester hydrochloride in batches, which increased the concentration of L-carnosine by 3.28 times compared with the nonbatch feeding. In conclusion, the ability of As DmpA to catalyze L-carnosine synthesis was improved by molecular modification technology and batch feeding methods, which provides an excellent method for the production of L-carnosine.