Mechanical Strength Characteristics Research Articles

Extrusion 3D printing of carbon nanotube-assembled carbon aerogel nanocomposites with high electrical conductivity

Carbon nanotubes (CNTs) with high aspect ratio and excellent electrical conduction offer huge functional improvements for current carbon aerogels. However, there remains a major challenge for achieving the on-demand shaping of carbon aerogels with tailored micro-nano structural textures and geometric features. Herein, a facile extrusion 3D printing strategy has been proposed for fabricating CNT-assembled carbon (CNT/C) aerogel nanocomposites through the extrusion printing of pseudoplastic carbomer-based inks, in which the stable dispersion of CNT nanofibers has been achieved relying on the high viscosity of carbomer microgels. After extrusion printing, the chemical solidification through polymerizing RF sols enables 3D-printed aerogel nanocomposites to display high shape fidelity in macroscopic geometries. Benefiting from the micro-nano scale assembly of CNT nanofiber networks and carbon nanoparticle networks in composite phases, 3D-printed CNT/C aerogels exhibit enhanced mechanical strength (fracture strength, 0.79 ​MPa) and typical porous structure characteristics, including low density (0.220 ​g ​cm−3), high surface area (298.4 ​m2 ​g−1), and concentrated pore diameter distribution (∼32.8 ​nm). More importantly, CNT nanofibers provide an efficient electron transport pathway, imparting 3D-printed CNT/C aerogel composites with a high electrical conductivity of 1.49 ​S ​cm−1. Our work would offer feasible guidelines for the design and fabrication of shape-dominated functional materials by additive manufacturing.

3D g-C3N4 porous nanoribbons pillared-MXene/ PVA nanocomposite: An architecture with high dielectric, breakdown strength, thermal conductivity, and mechanical strength characteristics

In polymer nanocomposites with conductive fillers, obtaining boosted dielectric constant, breakdown strength, lower dielectric loss concurrently, and mixing to build a homogeneous structure is challenging. In this work, 3D g-C3N4 porous nanoribbons pillared-MXene/PVA nanocomposite (MXene/CNNR/PVA) was fabricated. The solution casting method was utilized for embedding Mxene/CNNR into poly (vinyl alcohol) (PVA) to produce MXene/CNNR/PVA dielectric composites. The maximum observed electrical displacement is 10.95 μC/cm2 at (T = 25 °C and E = 400 MV/m). Furthermore, the obtained density of discharged energy is 18.11 J/cm3, much higher than that of pristine PVA (4.21 J/cm3 at E = 200 MV/m). The relative permittivity of 3.5 wt% ternary composites (MXene/CNNR/PVA) at 25 °C and 1000 Hz is 25.1, and the loss is just 0.03. Moreover, the combined use of MXene and CNNR results in a synergistic effect; the MXene/CNNR/PVA composite films exhibit more incredible mechanical characteristics compared to pure PVA nanocomposite modified by MXene alone, with notable increases in tensile strength and Young’s modulus while retaining the majority of its elasticity.

Zein-Bioactive Glass nanocomposite Coating on Magnesium Alloy Substrate for Orthopedic Applications

Excellent mechanical strength and biodegradable characteristics of magnesium alloys have sparked considerable interest in orthopedic applications. The utilization of magnesium alloys in orthopedic applications has been restricted due to their brittleness caused by high corrosion rate in biological environments. One of the best techniques for increasing corrosion resistance of these alloys is surface coating. For the first time, the present work aims to dip-coat zein-bioactive glass (BG) nanocomposite on AZ31B magnesium alloy. The alloy surface was also coated by native zein as a control coating. BG nanoparticles required for zein and BG (zein_BG) composite were synthesized by a bio-inspired method using cetyltrimethylammonium bromide (CTAB) as a template. The formation of BG particles was affirmed by FTIR showing characteristic Si-O-Si and Si-O– peaks. Nano-size of BG particles with an average diameter of 6.67 ± 0.06 nm was reported by TEM. SEM micrographs revealed successful deposition of zein and zein_BG coatings on the magnesium alloy surfaces. High-resolution XPS analysis on zein_BG-coated Mg alloy immersed in HBSS revealed the corrosion deposition of Mg(OH)2, MgHPO4.H2O, CaHPO4.H2O, SiO2, MgCO3, and CaCO3 on the substrate surface. More than twofold wettability, 95% adhesion strength and 14-fold increase in surface roughness were reported for zein_BG-coated magnesium alloy compared to the bare surface. Measurements of weight loss in zein and zein_BG-coated alloy substrates in Hanks Balanced Salt Solution (HBSS) for 10 d at 37°C showed a drastic decrease in weight loss of substrates after coating. As a result, zein_BG-coated substrate was observed to possess the maximum protective efficacy (95.99%) against corrosion. Interestingly, electrochemical measurements revealed a vast decrease in corrosion current density (2.41 E−6 A.cm−2) of zein_BG-coated substrate compared to the uncoated substrate (3.04 E−4 A.cm−2). Electrochemical impedance spectra (EIS) confirmed capacitive behavior of zein_BG-coated alloy substrate. These findings demonstrated that simple zein_BG composite dip coating was a successful corrosion-resistant implant coating on magnesium alloy surface for orthopedic applications.

Future perspectives of biopolymeric industry

Abstract Because of some specific properties such as hydrophilicity, poor mechanical strength, barrier properties, and other characteristics, biopolymers and biocomposite materials are not suitable for various important industrial applications. In the last few decades, the demand for biopolymers and their composites has increased continuously due to the extensive use of fossil resources or stock resources. Hence, eco-friendly biomaterials are highly essential for maintaining the sustainability of the environment. Now, biomaterials are considered highly promising materials that can be used as proper substitutes for fossil-based synthetic polymers and their composites through proper modification of the biopolymers. Recently, a novel non-biodegradable biomaterial (polythioesters) has been developed through microbial fermentation. Researchers throughout the globe are now developing improved biocomposite materials by incorporating different fillers in the nanoscale range that exhibit adequate mechanical properties and can be designed as future biomaterials that can replace traditional plastics. Now biopolymers and bionanocomposites are used noticeably in many countries throughout the world for food packaging, cosmetics, automobile industries, water purification, tissue engineering, textile industries, electronic industries, etc. For the industrialization of biobased polymeric materials and bionanocomposite materials, they should be synthesized in a sophisticated way by using green technology with improved geometry, good control in internal architecture, mechanical properties, and porosity. Chitin, alginate, pectin, zein, chitosan, poly-glutamic acid (-PGA), and other natural biopolymers are now found to be the future materials for various bioplastic industries. However, the future prospects of the biopolymer industry still pose challenges for industrialization and commercialization and should not be overlooked lightly.

Biodegradable ion-conductive polyvinyl alcohol/okra polysaccharide composite films for fast-response respiratory monitoring sensors

Polyvinyl alcohol (PVA) and okra polysaccharide (OP) are biodegradable polymers with high hydrophilicity and good biocompatibility with potential for use as flexible humidity-sensitive materials. Herein, biodegradable flexible composite films (named POP films) were prepared from PVA, OP, and phytic acid using a solution-casting method based on. POP films exhibited excellent mechanical strength, flexibility, flame retardancy, water resistance, humidity response, and humidity-sensing characteristics. Notably, the POP humidity sensors exhibited a hysteresis value of 1.88 % relative humidity for the adsorption and desorption processes and good sensitivity over a wide humidity range of 35–95 %. In addition, the humidity sensor distinguished the frequency of nose breathing, and its response and recovery times were 0.9 and 1.98 s, respectively. The excellent performance of POP sensors in monitoring humidity and human respiratory rates demonstrates the sensor's potential for wearable smart devices.

Wafer-Level Au—Sn Solid-Liquid Interdiffusion Bonding for Microwave Applications

Future compact integration of microwave modules will require intermetallic bonding with pitch connections lower than 10 μm. Solid-liquid interdiffusion (SLID) bonding is a potential bonding method for close heterogeneous integration because of its bonding temperature in the range of solder bonding, its ability to withstand higher temperaturs than bonding and its moderate compatibility with the joining of rough surfaces. This paper presents the results of an investigation of the Au—Sn system for integration of A3B5 chips on wafer level using SLID bonding. A sequence of five layers of Au and Sn with weight ratios of about 3:2 was deposited on a sapphire substrate. The structure and phases of the obtained system were investigated before and after annealing. The initial system has five distinctive alternating layers with an overall thickness of around 4.5 μm. After heat treatment at 320 °C with a holding time of 10 minutes, the Au—Sn system transforms into one layer that consists of only one phase ζ (Au0.853Sn0.147). The homogenization process is completed in less than 10 minutes. The ζ phase, of which the system is composed after annealing, has a melting point of 522 °C, which ensures the high temperature stability of the bonding layer. Bonding using the formed system was conducted. Morphology, elemental composition, and the initial mechanical properties of bonded structures have been studied. There are two types of defects in the joint's cross section: voids and the presence of local interfaces between two surfaces (an unbonded-like line). EDX analysis of the cross section of the joint between two crystals shows that the average ratio of Sn to Au over the cross section of the joint is 10.7 %. The complex of studies conducted suggests that the bonding area mostly includes the ζ phase, which will provide the best mechanical strength characteristics among the phases with a high Au concentration. The average bond shear strength is 32 MPa. Initial robustness results of the bonding are promising for space applications.

Влияние способа подготовки сырья для изготовления нативных стейков на их качественные показатели и органолептические характеристики

Purpose. Study of the influence of various methods of preparing raw materials for the production of native steaks on quality and organoleptic characteristics. Materials and Methods. The object of research was native beef steaks, which were made from raw materials obtained by various preliminary processing. Depending on the type of technological influences, the organoleptic characteristics of products (GOST 32125-2013), shear stress (GOST 52601-2006) and mechanical strength of meat (GOST 31797-2012) were studied. Results. As a result of the experiment, it was revealed that the experimental products (native steaks) had high organoleptic characteristics, namely: a more pronounced taste, color and aroma, consistency. This was achieved due to increased proteolytic activity of proteins, their faster splitting into amino acids, which affects the taste formation. Also, when using the developed method for preparing raw materials, a higher complex effect on meat proteins of proteolytic enzymes of the gastric tract (pepsin and trypsin) was noted and, as a result, an increase in the digestibility of the studied steaks. The methods and modes of preliminary exposure and processing of raw materials contribute to the increase of the hydrothermal effect, which improves their consistency, namely: the steaks processed by the proposed method had better organoleptic properties and more worthy results in terms of the tension of the slice of boiled meat – 350 H/m2, mechanical strength – 52.70%. All this can favorably affect the further development of finished products. Conclusion. It has been established that the use of the developed method of processing raw materials for the preparation of native steaks has a positive effect on the organoleptic characteristics of products, and also improves their quality indicators, which makes it possible to obtain products with good organoleptic characteristics, as well as quality characteristics.

Mechanical strength characteristics of saline soil stabilized by all-solid waste cementitious material based on projection pursuit regression modeling

Mechanical strength characteristics of saline soil stabilized by all-solid waste cementitious material based on projection pursuit regression modeling

Mechanical Properties and Strength Characteristics of Rock–Coal–Rock Assemblages under Different Peripheral Pressures

To investigate the deformation and damage characteristics of internal coal bodies of small pillars under different pressures, rock–coal–rock assemblage samples were subjected to the conventional triaxial compression test to analyze the mechanical behavior characteristics under different pressures. The results showed that, with the increase in peripheral pressure, the peak strength and modulus of elasticity of the assemblage specimens increased, the range of fracture compaction stage gradually decreased, and the specimen was gradually transformed from brittle to ductile. With an increase in peripheral pressure, the residual strength gradually increased, and the strength decay coefficient gradually decreased. The strength decay coefficient decreased the most at 0–10 MPa, and this decrease slowed down after exceeding 15 MPa. When the peripheral pressure was 0 MPa, the damage degree of the coal pillar was larger. With the increase in peripheral pressure, the number of cracks in the coal column increased, the damage degree increased more, and mixed damage characteristics of tension–shear were found. Based on the Hoek–Brown criterion, the strength criterion applicable to the specimen of rock–coal–rock combination was obtained through numerical fitting iteration, which provides an experimental and theoretical basis for realizing the stability control of small coal columns.

Modeling strength characteristics of basalt fiber reinforced concrete using multiple explainable machine learning with a graphical user interface

This study investigated the importance of applying explainable artificial intelligence (XAI) on different machine learning (ML) models developed to predict the strength characteristics of basalt-fiber reinforced concrete (BFRC). Even though ML is widely adopted in strength prediction in concrete, the black-box nature of predictions hinders the interpretation of results. Among several attempts to overcome this limitation by using explainable AI, researchers have employed only a single explanation method. In this study, we used three tree-based ML models (Decision tree, Gradient Boosting tree, and Light Gradient Boosting Machine) to predict the mechanical strength characteristics (compressive strength, flexural strength, and tensile strength) of basal fiber reinforced concrete (BFRC). For the first time, we employed two explanation methods (Shapley additive explanations (SHAP) and local interpretable model-agnostic explanations (LIME)) to provide explanations for all models. These explainable methods reveal the underlying decision-making criteria of complex machine learning models, improving the end user's trust. The comparison highlights that tree-based models obtained good accuracy in predicting strength characteristics yet, their explanations were different either by the magnitude of feature importance or the order of importance. This disagreement pushes towards complicated decision-making based on ML predictions which further stresses (1) extending XAI-based research in concrete strength predictions, and (2) involving domain experts to evaluate XAI results. The study concludes with the development of a “user-friendly computer application” which enables quick strength prediction of basalt fiber reinforced concrete (BFRC).

Obtaining microcrystalline cellulose based on biodamaged wood as a way to improve the sanitary and forest pathological state of forests

The paper-forming properties of the fibrous suspension and the physical and mechanical characteristics of the finished types of paper largely depend on the type of initial plant material. Depending on what purpose it is necessary to obtain paper, a composition is made from fibrous semi-finished products of plant origin in various proportions. Basically, paper is produced from two, three, or more fibrous semi-finished products, forming a paper composition according to the type of fibers, and sometimes from one fibrous semi-finished product, suitably prepared for this. The properties of the original fibrous semi-finished products to a large extent affect not only the properties of the finished paper, but also determine the technological mode of their processing. This paper shows the possibility of obtaining cellulose from biodamaged wood. The mechanical strength characteristics of the finished castings are analyzed after grinding the fibrous mass on a knifeless grinding plant of the “jet-barrier” type. The conditions for obtaining microcrystalline cellulose from biodamaged wood are determined.

Investigation of dynamic response of drilling parameters and deformation characteristics of coal around borehole during multi-stage reaming in tectonic coal

Tectonic coal refers to the coal with varying degrees of brittle fracture or ductile deformation under the action of one or multi-period tectonic stresses, showing the characteristics of low mechanical strength, weak cohesion and large deformation. Therefore, drilling in tectonic coal is easy to cause the aperture shrinkage or closure due to the poor anti-deformation capability. Enlarging the initial borehole can effectively increase the borehole diameter and reduce the risk of pipe jamming and burying without changing the borehole structure. In order to investigate the dynamic evolution characteristics of drilling parameters in the process of drilling and reaming in tectonic coal, a self-designed drilling experimental system that can monitor drilling parameters in real time was used in this study. Additionally, the acoustic emission (AE) response and borehole wall strain were observed to study the coal-breaking and the deformation characteristics of coal around borehole. The results demonstrate that the drilling rate and drilling torque increase sequentially in the initial drilling, primary reaming and secondary reaming stages. The magnitude of drilling rate is affected by both drilling thrust and rotational speed, whereas drilling torque is mainly affected by drilling thrust. The intensity of AE phenomena increases gradually at different stages of the borehole formation, which means that the drilling efficiency is improved and more strain energy is accumulated in the coal around the borehole during reaming. The borehole wall strain effectively reflects the convergence deformation of borehole wall, that is, the larger the borehole diameter, the greater the deformation of the borehole wall. The deformation of borehole is mainly affected by the redistribution of stress in the coal body, rather than the drilling parameters.

Granite powder as partial replacement of cement in M30 grade concrete mix using IS 10262:2019

PurposeThis study aims at designing consistent and durable concrete by making use of waste materials. An investigation has been carried out to evaluate the performance of conventional and optimal concrete (including 5% GP) at high temperatures for different exposure times.Design/methodology/approachAn experimental work is carried out to compare the conventional and optimal concrete with respect to weight loss, mechanical strength characteristics (compressive, tensile and flexural) after exposed to 100, 200 and 300 °C with 1, 2 and 3 h duration of exposure followed by cooling in furnace for 24 h and then air cooling.FindingsThe workability of granite powder modified concrete decreases as percentage of replacement increases. Compressive, tensile and flexural strengths all increased at 100 °C when compared to strength characteristics at normal temperature, regardless of the exposure conditions, and there was no weight loss noticed. For 200 and 300 °C, the strengths were decreased compared to normal temperature and an elevated temperature of 100 °C, as weight loss of concrete specimens are observed to be decreased at these temperatures. So, the optimum elevated temperature can be concluded as 100 °C.Originality/valueIncorporating pozzolanic binder (granite powder) as cement replacement subjecting to elevated temperatures in an electric furnace is the research gap in this area. Many of the works were carried out replacing GP for fine aggregate at normal temperatures and not at elevated temperatures.

Natural and manmade fibers as sustainable building materials

This review paper aims to assess of workability, mechanical and durability parameters of mortar and concrete developed by several natural and manmade fibers. Natural and manmade fibers were used by several researchers for enhancing the inherent properties of mortar and concrete. Various researches were carried out and the outcome of their studies are concisely depicted in this paper. The objective of this study is to accumulate the existing data on natural and man-made fibers assessed in the last few years, and consequently, it can be utilized as a reference paper for further research on a specific fiber. Typically natural and manmade fibers are utilized to enhance the mechanical strength characteristics of the mortar and concrete. Though all parameters cannot be value-added due to differences in fiber's character. Hence it is suggested that suitable fiber should be used based on the place of application. Similarly, a standard guideline should be maintained for the recognition of natural and man-made fibers due to variations in the properties of a particular fiber in diverse areas. Indeed, natural and manmade fibers can be utilized through a wide zone, yet the need for research for fiber characterization and its impact as a sustainable alternative building material on the construction industry is tranquil essential.

Modern structural and operating materials in development of road-building machines

BACKGROUND: The analysis of modern state of using structural and operating materials in development of road building machines is given in the article. AIMS: To highlight the most important tendencies in obtaining modern structural and operating materials in development of road building machines. METHODS: The study subject is modern structural and operating materials in development of road building machines. The novelty of the study lies in highlighting main modern tendencies of modification and technological features of modern structural and operating materials for road building machines with enhanced mechanical strength characteristics. The materials of the study include main scientific and practical information on ways of using structural and operating materials in development of road building machines. The study methods include classification and integration of the information on the topic of modern structural and operating materials in development of road building machines. RESULTS: It is found that the key difference between steel types for structural and operating materials as a part of development of units, mechanisms and parts of road building machines is parameters of corrosion resistance, which is defined by qualitative and quantitative chemical composition directly. Among the main issues of modern industry development, improvement of cost-performance ratio of road building machines, their mechanisms and engineering parts by means of reducing specific metal content and increasing operational reliability and durability is outlined. CONCLUSIONS: It is shown that, opposed to majority of low-alloyed structural steel types, change of austenite in steel types, micro-alloyed with vanadium and niobium and with strength class in the range from S350 to S490, with constant cooing according to the thermal cycle of welding performs mainly in bainitic range. As a result of structural changes, taking place in steel and influenced by thermal cycles of welding, the static strength indicators of the metal in zones of thermal impact of welding joints increase, whereas the indicators of plastic properties reduce. Sufficient reduce of impact viscosity of the metal in zones of thermal impact of welding joints of micro-alloyed structural steel types is observed at w6/5 5C/s. With increasing of cooling speed, the impact viscosity of the metal in zones of thermal impact rapidly increases and it may achieve the level of the main metal in some steel types.

High-Conductive CsH2PO4 Membranes with PVDF-Based Polymers Additives.

The study is devoted to one of the important problems of hydrogen energy-the comparative analysis and creation of novel highly conductive and durable medium-temperature proton membranes based on cesium dihydrogen phosphate and fluoropolymers. The proton conductivity, structural characteristics and mechanical properties of (1 - x)CsH2PO4-x fluoropolymer electrolytes (x-mass fraction, x = 0-0.3) have been investigated and analyzed. UPTFE and PVDF-based polymers (F2M, F42, and SKF26) with high thermal stability and mechanical properties have been chosen as polymer additives. The used fluoropolymers are shown to be chemical inert matrices for CsH2PO4. According to the XRD data, a monoclinic CsH2PO4 (P21/m) phase was retained in all of the polymer electrolytes studied. Highly conductive and mechanically strong composite membranes with thicknesses of ~50-100 μm were obtained for the soluble fluoropolymers (F2M, F42, and SKF26). The size and shape of CsH2PO4 particles and their distribution have been shown to significantly affect proton conductivity and the mechanical properties of the membranes. The thin-film polymer systems with uniform distributions of salt particles (up to ~300 nm) were produced via the use of different methods. The best results were achieved via the pretreatment of the suspension in a bead mill. The ability of the membranes to resist plastic deformation increases with the growth of the polymer content in comparison with the pure CsH2PO4, and the values of the mechanical strength characteristics are comparable to the best low-temperature polymer membranes. The proton-conducting membranes (1 - x)CsH2PO4-x fluoropolymer with the optimal combination of the conductivity and mechanical and hydrophobic properties are promising for use in solid acid fuel cells and other medium-temperature electrochemical devices.

Anodonta anatina midye kabuklarının yapısı ve sertlik özelliklerinin araştırılması

In this study, the shell structure of the freshwater mussel Anodonta anatina (Linnaeus, 1758) which has a widespread population in Gölbaşı Lake (Hatay) and is not economically exploited, was microscopically examined at a morphological level. It was determined that the shells of Anodonta anatina, which are not under significant fishing pressure, are mostly found discarded along the shores of the lake. This mussel species is important as a composite biological material with multifunctional roles in freshwater ecology. Considering the potential use of freshwater mussel shells as a biological material, an assessment of the shell structure, physical properties, mechanical strength, shell microstructure, and morphological characteristics of A. anatina was conducted. When cross-sections of the shell taken from the umbo, middle periostracum, and the region close to the pallial edge were examined in the dorsal-ventral direction, it was determined that the periostracum layer in the umbo region had a more prismatic and polygonal structure. The interior of the shell was found to consist of a shiny nacreous layer. In nacreous shell sections, it was observed that the nacreous layer contained more distinct layers near the pallial edge. Vickers microhardness tests were performed on individual shells, and it was found that the hardness value of the inner layer was the highest (625.5 ±172.7 HV), while the outer layer had a lower hardness value (531.5 ±110.7 HV). Based on XRF data, it was shown that the seashell powder is mainly composed of calcium oxide (98.8% wt., CaO) as a biological material.

Damage properties of basaltic rocks under multilevel stress loading and microwave irradiation

The deterioration of mechanical strength and damage characteristics of rock under microwave is the primary focus in evaluating the applicability of microwave-efficient rock-breaking technology. This study analyzed the mechanical strength deterioration and damage characteristics of basalt under microwave irradiation and performed an X-ray digital radiography (DR) image analysis of the damage process of basalt under a multilevel stress loading (MSL) path. The research results show that basalt with a large porosity had a better thermal effect on microwave irradiation and significantly enhanced the resistance to deterioration. The microwave thermal effect of polar minerals is critical to plastic failure behavior. This study also proposes a rock damage characteristic evaluation model based on X-ray DR image quantitative analysis and X-ray absorption dose threshold segmentation. The image analysis model can accurately describe the evolution process of rock damage characteristics. A modified model for basalt damage characteristic analysis is provided. The elastic–plastic damage model based on the Cast3M finite element software was compared with the proposed damage model based on X-ray DR images. The calculated results show that the change in the damage zone was consistent with the damage crack propagation process of basalt. Therefore, the proposed damage evaluation model can provide guidance for the scientific evaluation of the adaptability of microwave-assisted tunnel boring machine (TBM) efficient rock-breaking technology.

Hydrogels for 3D bioprinting in tissue engineering and regenerative medicine: Current progress and challenges.

Three-dimensional (3D) bioprinting is a promising and innovative biomanufacturing technology, which can achieve precise position controlling of cells and extracellular matrix components, and further create complex and functional multi-cellular tissues or organs in a 3D environment. Bioink in the form of the cell-loaded hydrogel is most commonly used in bioprinting, and it is vital to the process of bioprinting. The bionic scaffold should possess suitable mechanical strength, biocompatibility, cell proliferation, survival, and other biological characteristics. The disadvantages of natural polymer hydrogel materials include poor mechanical properties as well as low printing performance and shape fidelity. Over the past years, a series of synthetic, modified, and nanocomposite hydrogels have been developed, which can interact through physical interactions, chemical covalent bond crosslinking, and bioconjugation reactions to change the characteristics to satisfy the requirements. In this review, a comprehensive summary is provided on recent research regarding the unique properties of hydrogel bioinks for bioprinting, with optimized methods and technologies highlighted, which have both high-value research significance and potential clinical applications. A critical analysis of the strengths and weaknesses of each hydrogel-based biomaterial ink is presented at the beginning or end of each section, alongside the latest improvement strategies employed by current researchers to address their respective shortcomings. Furthermore, we propose potential repair sites for each hydrogel-based ink based on their distinctive repair features, while reflecting on current research limitations. Finally, we synthesize and analyze expert opinions on the future of these hydrogel-based bioinks in the broader context of tissue engineering and regenerative medicine, offering valuable insights for future investigations.

Study on the mechanical properties and microstructure of a rich-watered grouting material

The effective method of mine gas control and efficient development is gas extraction technology. The sealing effect of grouting material on borehole directly affects the efficiency of gas extraction. The new type of rich-watered sealing material with suitable mechanical strength and significant plastic characteristics was developed based on the addition of accelererant, alkali activator, expansion agent and reinforcing agent to Portland cement for mining. The effect of reinforcing agent on the mechanical properties of materials under different w/c ratios was tested by RMT. By means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and other test methods, the microstructure evolution of grouting materials and its influence mechanism on macroscopic mechanics were revealed. The results show that the crystal structures of hydration products AFt, Ca(OH)2 and C-A-H regulate the development of mechanical strength of materials. The uniaxial compressive strength of rich-watered grouting materials can reach 3.5–5.6 MPa and the residual strength is greater than 3 MPa in the range of rich-watered ratio of 0.9–1.3. The new rich-watered grouting material developed has significant plastic deformation characteristics under high rich-watered ratio conditions, which can greatly adapt to borehole deformation and reduce the gap width of slurry-coal interface, and can meet the technical requirements of long-term sealing of gas extraction boreholes.