Concrete is a material that is widely used in the construction market due to its availability and cost, although it is prone to fracture formation. Therefore, there has been a surge in interest in self-healing materials, particularly self-healing capabilities in green and sustainable concrete materials, with a focus on different techniques offered by dozens of researchers worldwide in the last two decades. However, it is difficult to choose the most effective approach because each research institute employs its own test techniques to assess healing efficiency. Self-healing concrete (SHC) has the capacity to heal and lowers the requirement to locate and repair internal damage  without the need for external intervention. This limits reinforcement corrosion and concrete deterioration, as well as lowering costs and increasing durability. Given the merits of SHCs, this article presents a thorough review on the subject, considering the strategies, influential factors, mechanisms, and efficiency of self-healing. This literature review also provides critical synopses on the properties, performance, and evaluation of the self-healing efficiency of SHC composites. In addition, we review trends of development in research toward a broad understanding of the potential application of SHC as a superior concrete candidate and a turning point for developing sustainable and durable concrete composites for modern construction today. Further, it can be imagined that SHC will enable builders to construct buildings without fear of damage or extensive maintenance. Based on this comprehensive review, it is evident that SHC is a truly interdisciplinary hotspot research topic integrating chemistry, microbiology, civil engineering, material science, etc. Furthermore, limitations and future prospects of SHC, as well as the hotspot research topics for future investigations, are also successfully highlighted. Autogenous healing, on the other hand, is restricted to minor cracks and is effective only when water is accessible, which makes it difficult to fully control or predict its accuracy. However, concrete can be adapted to include a bacterial stimulant system for sealing cracks [Self-healing is a well-established and well-known property of concrete due to its innate autogenous healing properties . After ag cracks . Since tg cracks . After 3SHC has a distinct system  into a concrete mix that contains repairing solutions. When a crack appears, the fibers or capsules break, and the liquid contained within them spreads and heals the crack at the same moment. Even though too many hollow fibers or capsules have a negative influence on the strength qualities of the cement matrix, several studies clearly reveal the possibility of self-healing under numerous damage events via encapsulation techniques. In this review study, an overview of self-healing techniques based on microbiological calcium carbonate production is presented. Furthermore, numerous obstacles associated with crack treatment by microbiological factors are explored, as well as providing recommendations for future study areas. Aside from bio-based healing and concrete durability, the cost of producing bio-concrete is also an issue. A more detailed examination of ways to lower costs related to bio self-healing, such as bacteria and nutrient costs is required . StrategThe self-healing process is affected by a series of variables, including the healing agent used, the protective casing material, the dosage of capsules, the capsule diameter, the crack width and depth, the causes of cracks, the temperature and humidity, the concrete or mortar mix design, and finally the healing time. The appearance of the specimens with the addition of both spores and nutrients differed greatly. Not only were the cracks completely filled, but the surface of the specimens was partly covered by white precipitates after 28 days of healing. Some pores were also filled by the deposits c. The me3. The second is that CaCO3 is generated during Ca(OH)2 dissolution [The first is that unreacted cement particles are employed to initiate hydration and form CaCOsolution . There asolution . PreviouThe availability of free water is critical to the healing of a cracked surface. Several previous studies have indicated that the presence of water plays an important role in facilitating crack healing. However, when the healing process is only efficient in the presence of water, the self-healing process has more difficulty to control its occurrence and it is also difficult to predict its efficacy ,49. It iBacillus sphaericus can completely heal a maximum crack width of 0.97 mm, which is almost four times that observed in a non-bacteria sample [0) of the reference specimens after damage and the strength recovery (h1) of the damaged specimens after healing (Equation (4)) [In general, spontaneous or autogenous healing is most efficient for extremely small cracks of less than 0.3 mm in width ,54 see . The pota sample . For thea sample . Howevera sample . Furthera sample . Accordia sample . From a a sample . In genea sample . The chaa sample . Therefoion (4)) .H = ) as the non-steady-state migration coefficient .Dnssm =It is widely established that prolonged hydration results in improved self-healing capacity. Self-healing is a well-established and well-known property of concrete due to its innate autogenous healing characteristics . Figure It seems that the hydration rate is significantly greater at low w/c ratios than it is at high w/c ratios. This is due to the fact that the hydration kinetics of cementitious composites containing mineral additives can be slow in the first weeks, so, in recent years, several methods have been proposed to stimulate and accelerate the self-healing process, including using alkaline solutions , and theSHC, also known as bio-concrete, can be produced by adding bacteria in concrete along with its nutrients to keep them alive for the production of calcite to fill cracks after precipitation. Bacteria are to be added in concrete along with calcium lactate to repair cracks. It was noted that the crack’s capillary attractive force and the gravitational force on the fluid mass were inadequate to overcome the cylindrical capsules’ capillary resistive force and the negative pressure forces created by the sealed ends . HoweverIt is found that the use of high cement content and a low water-to-cement ratio also increases the autogenous self-healing capacity of ECC . AccordiBacillus pasteurii has also been shown to enable cracked concrete to regain 90% of its original strength. According to Victor Li of Michigan University [Self-healing is believed to be promising in enhancing the durability and serviceability of cementitious structures, and it is widely understood that water is a crucial factor for the self-healing process to occur  see Tab. Bacilluiversity , when thiversity  reportediversity . It is aiversity . It was iversity ,104. Thuiversity ,106,107 iversity . Jacobseiversity ,110 repoiversity . The autiversity .3) inside micro-cracks and the recovery of air permeability during water re-curing. In comparison to other types of concrete and fiber-reinforced concrete, research into the self-healing behavior of UHPFRC is still in its early stages, with just one study [In recent years, researchers have reported the self-healing behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC), which has potential for self-healing because the incorporated micro steel fibers restrict cracking, following cryogenic cooling ,135. A sne study  looking Autogenic self-healing (ASH) is the ability of concrete to repair or heal cracks in the presence of moisture and the absence of tensile stress . The uti2 and aragonite, was also observed to have a significant impact on the healing process. In a another study [The marine environment has an impact on autogenous self-healing as well ,145. OrdReportedly, the use of pozzolanic minerals was proven to improve the autogenous self-healing capacity of OPC concrete when used as supplementary cementitious materials due to their pozzolanic activity ,24. The 3)–alginate composite material [The autonomic self-healing mechanism relies on additives such as microcapsules containing healing capsules filled with bacteria spores, which are considered responsible for depositing the healing materials ,159,160.material . It is amaterial . In the material , beads amaterial . In brieThe autonomic self-healing process is based on the action of additives such as healing-agent-filled microcapsules ,160. OneThe design cycle for capsule-based self-healing materials involves the following steps: (1) capsule encapsulation; (2) capsule integration into the matrix; (3) mechanical characterization; (4) healing agent triggering and release to the damaged region; and (5) healing agent assessment . Five diThe capsule/dispersed catalyst healing mechanism is based on encapsulating a self-healing agent within brittle capsules and dispersing the catalyst/hardener within the matrix. Damage propagating in the crack form results in the capsules breaking and releasing the monomer, which then comes into contact with the catalyst, resulting in polymerization . The thiThis is explained by their brittleness and size: glass tubes with a wall thickness of 2 mm can rupture upon crack development, whereas tubes with a wall thickness of 3 mm cannot burst satisfactorily upon crack formation ,176. TheBacillus sphaericus cells [Bacillus sphaericus in diatomaceous earth was revealed in terms of water absorption. The finding indicated that the absorbed water rate of specimens with immobilized bacteria was around 50% with respect to specimens without bacteria [Bacillus sphaericus made the concrete more waterproof [Bacillus sphaericus in mortar reduces the compressive strength by 15% to 34% [Bacillus sphaericus in cube mortar increases the compressive strength at 7 and 28 days [Compressive strength ,198,199 us cells ,205. It bacteria . It has terproof . Over a % to 34% ; however 28 days .6 cells/mm3 [8 cells/mm3. The effect of Sporosarcina pasteurii on the compressive strength of mortar specimens was investigated after 7 and 28 days [Sporosarcina pasteurii on porous glass beads was shown to significantly boost the compressive strength of the mortar specimen by 24%. Furthermore, compressive strength increased as the cell concentration increased from 6.1 × 107 to 3.1 × 109 cells/cm3. In addition, the influence of immobilized ureolytic and denitrifying bacteria in protective materials on compressive strength has been documented [It was reported that a bio-based agent had a positive influence on compressive strength for the cell concentration of 5 × 10ells/mm3 ; however 28 days . On the cumented .Bacillus sphaericus in concrete decreased the compressive strength at 7 and 28 days by 63% and 60%, respectively. It was also noted that although the utilization of denitrifying bacteria caused a reduction in compressive strength at both 7 and 28 days, immobilization of Diaphorobacter nitroreducens in expanded clay and granular activated carbon marginally enhanced the compressive strength. Bacillus sphaericus immobilization in metakaolin and zeolite, on the other hand, had a negative effect on compressive strength [The findings indicated that the application of strength . These istrength ,218. TheThe review by Tittelboom and De Belie  providesAnother study reported the development of two test procedures for determining the sealing effectiveness . The firIt is reported by Zemskov et al  that mecMicrocapsule resilience is defined as the capacity of a microcapsule to tolerate high pressures and external stresses without losing its desired performance ,220. MicThis is supported by the experimental results, which demonstrate that the specimen’s crack strength was 32% greater than that of the control specimen . In summFurthermore, it is reported by Mullem et al.  that theIt is well established that increasing the durability of cracked concrete by lowering the permeability of the damage zone by crack sealing or densification of the damaged cementitious matrix is possible ,220. In According to reports, closing toward the crack’s tip, the distance between the crack planes steadily decreases and the healing processes becomes more efficient. In addition, sodium silicate was shown to be more effective at sealing than some polymers. Complete sealing is seen in 110–170-µm-wide cracks and 80% sealing in 180–250-µm-wide cracks in specimens containing 6% of 290 µm sodium silicate microcapsules . When 6%The development of novel self-healing cementitious materials that mimic the behavior of natural living systems has attracted the global research community across a broad range of engineering and scientific disciplines and has the potential to revolutionize the way in which concrete structures are designed and constructed ,37,257. 2 [The technology will be available for the first time this year. It will be available in three different forms: self-healing concrete, repair mortar, and liquid repair medium. Unfortunately, the technology is currently extremely expensive, costing approximately USD 33–44/m2 . As a re2 . Further2 . Owners 2 . Since 12 . In the 2 . As a reCurrently, the application of self-healing technology is still inconsistent, in part owing to a lack of systematic data reporting and defined testing and characterization criteria ,231. Thi− Strategies to enhance bio self-healing and lower costs will bring about a shift in contractors’ acceptance of bio-concrete as a material of choice in the near future .− Future research should concentrate on the protection of bacteria in their natural habitats and the maintenance of a constant supply of nutrients.− The area of study should be extended to include the impact of healing on the return of these BSH materials’ original mechanical characteristics.− It is imperative that further study be done to see how these BSH systems perform in real environmental conditions, such as when the concrete is older, when it has many cracks, or when it is subjected to varied sustained loads.− There is still a shortage of large-scale meaningful commercial experience, where BSH strategies have not been employed in practical engineering projects till now.− Additional research is needed to determine how to reduce related expenses, specifically microorganisms, nutrients, and labor ,272.− A comprehensive evaluation of whether healed BSH concrete elements will achieve a similar or equivalent lifetime performance when compared to uncracked conventional concrete elements would require long-term durability tests to be conducted.− Further research is needed to determine how to cheaply scale up the various processes involved in the manufacturing of BSH materials.− Despite recent advances in the design of protocols for bio-based self-healing concrete, the available research is still hindered by a lack of numerical simulation, which would allow them to minimize experimental costs and time in the early stages of commercial application .− In addition, it is required to establish methodologies, such as life-cycle assessments, to evaluate the cradle-to-gate sustainability of various BSH options.− Further research is needed to expand the available bacterial isolates for case-specific bespoke solutions.− In order to improve our understanding of the precise determinants underpinning an ideal bacterium, it could be better to use genetically modified microorganisms to aid in the focused selection of the most appropriate species.− Despite this, SHC’s application to the concrete industry is still a while away.− The feasibility of applying a healing agent during the mixing process and the persistence of bacteria in cured concrete require more investigation .− It is critical that future research be directed toward the creation of capsules that are capable of surviving the concrete mixing and manufacturing processes without affecting the mechanical qualities of the resulting concrete.The target of the current study is to show that bacteria-based self-healing (BSH) cementitious composites can ‘self-heal’ by successfully sealing cracks that occur within a particular width range ,154,270.− Autogenous healing is still limited to small cracks, and its reliability still is lower because it is dependent on the matrix composition at the time of crack development, which determines the possible reaction mechanisms.− It should also consider the chance of a fracture reaching a capsule, the release efficiency, and the healable crack volume.− Because tubular capsules must be manually inserted, this method is only suitable to precast concrete elements.In the last two decades, there has been a surge in interest in self-healing materials, particularly self-healing characteristics in cementitious materials, with dozens of researchers proposing various methods ,274. It A comprehensive assessment of SHC research, reported by Tittelboom and Belie  showed tAs reported by García et al , it is f-The manufacturing of low-cost corrosion-free steel.-The use of nanoparticles, carbon nanotubes, and nanofibers to boost the strength and durability of cement materials on the SHC capability of high-performance concrete, as well as to reduce pollution .-The creation of coatings and thin films with self-cleaning and self-coloring properties to reduce energy usage.-The production of thermal insulating materials with ten times the performance of current market choices.-The creation of nanosensors and nanomaterials with sensing and SHC capabilities.-Further study in the realm of nanotoxicity is also required; nevertheless, significant caution should be utilized while employing nanoparticles .Nanotechnologies have the ability to open the door to a brand new universe of building construction. Although the reproduction of natural systems is one of the most promising areas of modern technology, scholars are still struggling to comprehend their incredible intricacies . They arSelf-healing of concrete is a complicated process that involves a combination of physical, chemical, and mechanical forces. Due to the low tensile strength of concrete, cracks are a regular occurrence. These fissures reduce the durability of concrete by providing a convenient conduit for the passage of liquids and gases that may contain dangerous compounds. If micro-cracks become large enough to reach the reinforcement, not only will the concrete be harmed, but the reinforcement will also deteriorate. As a result, it is critical to keep the crack width under control and to cure the cracks as quickly as feasible. The creation of SHC is the subject of this research since the costs of maintaining and repairing concrete structures are often significant. Self-healing concrete cracks would extend the lifespan of concrete structures, making the material slightly more resilient but also more efficient. SHC is a technique that can be used to create smart materials and a high degree of flexibility. Depending on the application, multiple self-healing concrete technologies can be used. The most challenging issues for all self-healing technologies in the concrete industry are general adoption, increased expenses, and long-term durability effectiveness confirmation.Restriction of crack initiation, wet–dry cycle, the use of SCMs such as GGBS, silica fume, and fly ash, and the use of expansive minerals such as bentonite clay, MgO, CSA, quicklime, and crystalizing mineral agents could all improve concrete’s autogenous self-healing potential. The success of autogenous self-healing, on the other hand, is heavily reliant on the amount of unhydrated cement or mineral left in the concrete. This has hitherto been limited to lower healable crack widths, longer healing times, and strength return. In contrast to autogenous healing, autonomic healing in concrete necessitates the discharge of the self-healing stimulating agent from restricted encapsulation or a continuous supply network. This is to increase the efficiency of concrete’s self-healing compared to the autogenous healing process. Microencapsulation, microvascular, and pellets containing various autonomic healing agents such as epoxies, methyl methacrylate, cyanoacrylates, microorganisms, minerals, and alkali–silica solutions are popular autonomic self-healing systems.Encapsulation of biological healing agents in concrete is a superior alternative since the reaction between unhydrated cement particles and healing agents produces favorable effects. The effectiveness of a healing procedure, according to available healing techniques, is determined as to how much the matrix and healing agent interact with one another. The size and geometry of the crack also have a part in determining the efficient outcomes of concrete healing. For instance, mending uniform-width cracks differs from healing variable-width cracks. The ability of SHC to heal reduces the need for external intervention in locating and repairing internal damage . This results in concrete deterioration and reinforcing corrosion, as well as decreased costs and increased durability. The tactics, influential factors, mechanisms, and efficacy of self-healing were rigorously reviewed in this study. This research study also includes critical synopses of the characteristics, performance, and evaluation of SHC composites’ self-healing efficiency. Furthermore, development study is trending toward a broad grasp of SHC’s application potentiality as a superior concrete material and a turning point for fostering sustainable and serviceable concrete nanocomposites for modern buildings.Based on this detailed literature review study, the development of self-healing high-performance concretes is a unique, cutting-edge, accessible, and environment-friendly concrete technology for proposing robust and sustainable homes for upcoming generations. It has been discovered that the initial strength attributes have yet to be recovered. Because only partial recovery of strength properties after fracture healing is possible in conventional concrete, this element will be more difficult to achieve in high-strength concrete due to the greater initial mechanical properties. Furthermore, the healing of larger cracks must be attempted, which will be critical in particularly aggressive settings or when concrete structures are subjected to very aggressive operating circumstances. Both milestones must be met, which necessitates the adoption of self-healing systems that are well-suited to the concrete matrix. It has become evident that nanotechnology will be one of the primary techniques used to indicate that self-healing systems based on nanoparticles are likely to have a lower negative impact on the resulting initial strength qualities than those based on microcapsules. Furthermore, it is possible that SHC will allow builders to create structures without concern of damage or costly maintenance. There is also evidence that SHC is a truly interdisciplinary hotspot research topic that integrates civil engineering, chemistry, material science, microbiology, and other disciplines. Furthermore, the SHC’s limitations and future opportunities, as well as hotspot research issues for future studies, have been successfully highlighted.


This investigation deals with the prediction of mechanical behavior in basalt-fiber-reinforced concrete using the finite element method (FEM). The use of fibers as reinforcement in concrete is a relatively new concept which results in several advantages over steel-reinforced concrete with respect to mechanical performance. Glass and polypropylene (PP) fibers have been extensively used for reinforcing concrete for decades, but basalt fibers have gained popularity in recent years due to their superior mechanical properties and compatibility with concrete. In this study, the mechanical properties of basalt-fiber-reinforced concrete are predicted using FEM analysis, and the model results are validated by conducting experiments. The effect of fiber-volume fraction on the selected mechanical performance of concrete is evaluated in detail. Significant improvement is observed when the loading is increased. There are superior mechanical properties, e.g., load bearing and strain energy in basalt-fiber-reinforced concrete as compared to conventional concrete slabs reinforced with gravel or stones. The results of the simulations are correlated with experimental samples and show a very high similarity. Basalt-fiber-reinforced concrete (BFRC) offers a lightweight construction material as compared to steel-fiber-reinforced concrete (SFRC). Further, the problem of corrosion is overcome by using this novel fiber material in concrete composites. Fiber-reinforced composites have been utilized for quite some time now. Composites using fibrous reinforcement materials with high strength, low density, along with high ductility are used in many fields such as aerospace, construction, and defense. Due to their evident advantages, much research has been carried out in this field to examine the possibility of using such composites in other fields where they have not been used. This approach also helps in decreasing the cost of materials for more widespread applications. Fiber-reinforced concrete, as opposed to conventional concrete, is a relatively new concept. The use of fibers in concrete decreases the weight of the slabs and columns. They also have very good insulation properties and are not magnetic in nature. Though at lower loads the crack widths and extensions are higher for fiber-reinforced concrete due to its lower Young’s modulus, at higher loads, crack spacing decreases relative to steel reinforcement. Creep and shrinkage behavior in fiber-reinforced concrete is similar to those in steel-reinforced concrete slabs and columns ,2. The f2, Al2O3, CaO, MgO, K2O, Na2O, Fe2O3 and FeO. It has high abrasion resistance, excellent resistance to extreme temperatures, good insulation properties , lower moisture absorption, inertness to the environment, and very high durability [Basaltic rock is formed from solidified lava (igneous rock). It is an extremely hard, fine-grained extrusive rock and consists of the minerals SiOrability ,9,10,11.rability .Unlike many other fibers, basalt fiber is known to properly disseminate in the concrete mix when used instead of forming balls and has very high bio-solubility. Its stress–strain behavior is linear up to its failure ,15,16,17Basalt-fiber-reinforced concrete shows higher splitting tensile strength and toughness as compared to pure concrete, but its compressive strength decreases over time. With increasing fiber length, there is an increase in tensile strength, compressive strength, and toughness, which may be because interfacial bonding increases with increasing surface area ,24,25,26Basalt fibers are extracted from volcanic rocks and are therefore a purely natural product. They do not involve artificial chemicals or reagents. They have been referred to as a “green material” in the literature. The environmental impact of using such material instead of synthetic material is very significant ,34.Using chopped basalt fibers in concrete mix is not the only way of reinforcing. Basalt-woven structures or rebars are other alternatives. They are lighter than other forms of reinforcement, and using a lower amount of basalt fibers/rebars may generate the same strength while considerably reducing the weight of the slabs ,35. TheyIn this study, the mechanical properties of basalt-fiber-reinforced concrete slabs were predicted using the finite element analysis. Simulations were conducted using ANSYS by making CAD models of the samples and the obtained results were analyzed. To study the tensile property of basalt-fiber-reinforced concrete, experiments were carried out by making samples of pure concrete and 1%, 2%, and 3% basalt-fiber-(by weight) reinforced concrete. The simulation results were compared with experimental samples as well as with findings of previous studies. The properties were also compared to those of fine and coarse aggregates used in concrete. The influence of basalt fiber as a replacement for stone/aggregates in concrete slabs was investigated.Details of the basalt fibers and concrete used are given in The chemical composition of the basalt fiber is given in 2 and Al2O were the dominant compounds. The content of FeO and Fe2O3 played a very important role in determining many physico-mechanical properties of basalt fibers, such as density, color , lower heat conduction, and better temperature stability compared with those of E-glass fibers. The basalt fibers were pretreated against possible alkali reactions [A qualitative elemental analysis of the basalt fiber determined that SiOeactions ,35.Four types of experimental samples were prepared as shown in The tensile testing was conducted on a Zwick/Roell universal tensile tester as per the standard ASTM C1399 ,37. TwenThe average material property was used for defining the composite/concrete elements. Multi-scale mechanical models were developed in order to predict the properties of the fiber-based composites.For the theoretical estimation of the mechanical properties of the fiber-reinforced concrete, the corresponding mechanical properties of the fibers and pure concrete were experimentally evaluated. The mechanical properties of the basalt-fiber-reinforced concrete was estimated using a Halpin–Tsai model. This model is commonly used for the prediction of the effective mechanical properties of fiber-reinforced concrete (composites) ,37,38. TcK = the effective mechanical property of the fiber-reinforced concrete;fK and mK are the corresponding fiber and concrete mechanical properties, respectively;fV = the fiber volume fraction;ζ = the geometrical parameter, which represents the loading conditions .The modeling was carried out using a micro-scale representative volume element (RVE), which was subsequently transferred to a meso-scale RVE of the final composite to calculate the elastic constants by homogenization. Research has been reported about the prediction of mechanical properties in concrete with a given fiber-volume percentage. The predictions were reported to have a very good agreement with the experimental results ,40.The FE solution is broken down into the following three stages. This is the basic guideline that can be used for setting up any FEA ,40,41.Defining key points/lines/areas/volumes in the concrete slab.Defining element type and material/geometric properties for fiber, gravels, as well as the cementitious matrix.Defining mesh lines/areas/volumes as required.The major steps in preprocessing are given below:The amount of detail required depends on the dimensionality of the analysis .Plain concrete sample;Concrete sample reinforced with 1% basalt fiber;Concrete sample reinforced with 2% basalt fiber;Concrete sample reinforced with 3% basalt fiber.Simulations were conducted on the following models to test their tensile strength:3 and a volume equivalent to that of the chopped fibers;Three percent very fine aggregates (average 4 mm) with a density of 2615 kg/m3 and a volume equivalent to that of the chopped fibers.Three percent coarse aggregates (average 7 mm) with a density of 2660 kg/mIn addition to these, some other simulations were also conducted in order to compare the fiber-reinforced concrete with the standard concrete reinforced with aggregates/stones. For such a simulation, the volume fraction of aggregates was considered as 3%. The density of such aggregates was taken from the literature ,34,38. TA unit cell was prepared for each case with a dimension of 0.5 × 7 × 1 cm. A total of twenty-two (22) unit cells were stacked one above the other to make the complete concrete slab structures shown in 5 N acting on the opposite face.The simulation of all samples with one end fixed and a force of 50 × 105 N acting on the opposite face .The simulation of the pure concrete sample with one end fixed and a force of 150 × 105 N acting on the opposite face (the force at which the 1% fiber-reinforced concrete sample failed in the conducted experiment).The simulation of the 1% fiber-reinforced concrete sample with one end fixed and a force of 300 × 105 N acting on the opposite face (the force at which the 2% fiber-reinforced concrete sample failed in the conducted experiment).The simulation of the 2% fiber sample with one end fixed and a force of 500 × 105 N acting on the opposite face (the force at which the 3% fiber sample failed in the experiment conducted).The simulation of all the 3% filler-based concrete samples  with one end fixed and a force of 700 × 10The static structural module in ANSYS was used to carry out the simulation in order to compare the tensile strengths of each of the samples. The following simulations were carried out:To determine the advantages of the linear behavior of basalt fiber until failure, simulations were also conducted assuming a yield point before the ultimate failure. The simulations for these are not shown in this paper, but the effects were insignificant.The input parameters given are as follows:Young’s modulus of basalt fiber = 89 GPa; Poisson’s ratio of basalt fiber = 0.3.Young’s modulus of concrete = 17 GPa; Poisson’s ratio of concrete = 0.33.The tensile yield and ultimate strength values, as well as the compression yield and ultimate strengths were also given as inputs, but they were found to have no effect on the results as explained later in this section.The basalt fibers, fine aggregates, and coarse aggregates were all given with the same dimensions for comparison purposes. The model was built with a coarse mesh and the simulation was carried out. The distribution of stress along the samples were found for the following parameters in each sample:y-axis, along which the force was applied).Directional deformation (m)— is given by the following expression:U = strain energy, V = volume, E = Young’s modulus, and S = stress.Strain energy .The experimental samples were tested on a universal testing machine. The average result of 20 measurements was taken. The load extension graph obtained for the samples is given in The tensile strength significantly increased as the percentage of the fiber increased. The strength increased by around four times when the fiber percentage was 2%. The elastic modulus also increased when the fiber percentage increased from 0 to 1% but after that, remained almost constant when further increased. The crack patterns were also very different for the sample without the fibers and the samples reinforced with the fibers. The failure/crack path in the case of the samples reinforced with basalt fibers was much more tortuous due to the presence of fibers, not a straight horizontal line , unlike the case of the pure concrete sample. The overall extension increased for the fiber-reinforced concrete, and it was also proportional to the fiber weight percentage. The samples are shown in The peak load and extension are also given in It can be observed that an addition of basalt fiber of up to 3% increased the peak stress in the concrete. Further, the deformation at peak stress was reduced, thus increasing the load-bearing capacity. The basalt-fiber-reinforced concrete showed improved performance as compared to pure concrete as well as fine-/coarse-aggregate-based samples. Similar studies have been reported in the literature where the performance of concrete was improved by an addition of up to 3% microfibers and waste mineral admixtures .The inclusion of micro-silica in small doses has been reported to be superior with respect to the tensile performance of concrete. It has also been reported that micro-fillers enhance the bond strength, which was responsible for the improvement of mechanical performance in concrete composites .The simulations of concrete samples were carried out based on the defined conditions. The results are shown in 4 Pa and a maximum strain 4.2 × 10−6 m/m at 50 × 105 N force. The corresponding deformation was 1.36 × 10−6 m. These values were quite close to the experimental result. The model for the plain concrete sample predicted a maximum stress of 6.9 × 105 N force was 2.1 × 105 Pa. The maximum strain was predicted as 1.25 × 10−5 m/m.The predicted value for maximum stress at 150 × 105 N force. The value was predicted to be 4.35 × 105 Pa. The strain was predicted as 4.75 × 10−6 m/m.The model for the 1% basalt-fiber-reinforced concrete predicted an increased maximum stress at 50 × 105 N. they were based on the peak load obtained during the experimental trials. The predicted value of maximum stress was 4.35 × 105 Pa. The corresponding strain was predicted as 2.9 × 10−5 m/m.Simulations were performed for 1% basalt-fiber-reinforced concrete at a load of 300 × 105 N force. The predicted maximum stress was 7.29 × 104 Pa. The maximum strain was predicted as 4.76 × 10−6 m/m. The performance was predicted as superior to that of the 1% basalt-fiber-reinforced concrete sample. This also corresponded to the findings of the experimental analysis.Further simulations were performed for the 2% basalt-fiber-reinforced concrete samples at 50 × 105 Pa. This was significantly higher than the maximum stress for the 1% fiber-loaded concrete. Further, the stress was higher at a higher load. The maximum strain was predicted as 4.76 × 10−5 m/m. It was observed to be slightly higher at higher loading. The performance was similar to that of the results obtained from the experimental samples.Based on the peak experimental load, the simulations for the 2% basalt-fiber-based concrete were performed at 500 × 105 N force. The maximum stress was predicted as 7.22 × 105 N force. The maximum stress was predicted as 7.38 × 104 Pa. This was much higher than the stress level for the 1% and 2% fiber-loaded samples. These findings resembled the experimental tests.Simulations for the 3% fiber-reinforced sample were carried out at 50 × 105 N. The maximum stress was predicted as 10.18 × 105 Pa. This value was significantly higher than the maximum stress for the 1% and 2% basalt-reinforced concrete. The corresponding strain was predicted as 6.66 × 10−5 m/m.Based on the peak experimental load, further simulations were performed for the 3% basalt-fiber-reinforced concrete slabs at a load of 700 × 105 N force. The maximum stress was predicted as 7.05 × 104 Pa. This stress value was higher than that of the plain concrete but lower than that of even the 1% basalt-fiber-based concrete. Further, the strain was predicted as 4.42 × 10−6 m/m, which was lower than that of the basalt-fiber-based samples but slightly higher than that of the plain concrete sample.For a comparison of the fiber-reinforced concrete with respect to the standard concrete with fine aggregates, simulations were performed at 50 × 105 N force in order to compare its performance with the corresponding sample of the 3% basalt-fiber-reinforced concrete slab. It was predicted that the maximum stress would be 7.12 × 105 Pa. This was higher than the maximum stress for the 1% basalt-fiber-based sample. However, it was significantly lower than that of the 3% basalt-fiber-reinforced sample and slightly lower than that of the 2% fiber-based sample. This was an indication that a 2–3% reinforcement of basalt fiber in the concrete would be optimum. It was also established through the experimental analysis that the 3% basalt-fiber-based samples showed a higher stress level than that of the 3% fine-aggregate-based concrete [−5 m/m. This was lower than the predicted stress for the basalt-fiber-reinforced concrete. This was the result of fiber extensibility, which was higher than that of the stones/aggregates.The fine-aggregate-based sample was also loaded at 700 × 10concrete ,45. A hi5 N. The maximum stress was predicted as 6.96 × 104 Pa, which was lower than that of all the samples reinforced with basalt fiber. The maximum strain was predicted as 4.31 × 10−6 m/m. Thus, coarse aggregates could be successfully replaced with basalt fibers comprising up to 3% of the overall volume in a concrete mix.Simulations were performed on concrete samples reinforced with coarse aggregates. The loading condition was set as 50 × 105 N force. The maximum stress of 6.58 × 105 Pa was predicted. It was significantly lower than the maximum stress in samples reinforced with 2% and 3% basalt fibers. Although, it was higher than that of the pure concrete sample. This indicated that coarse aggregates can be useful for the reinforcement of concrete; however, much better performances can be achieved by replacing these with basalt fibers comprising up to 3% of the overall volume. The maximum strain for the coarse-aggregate-based sample was predicted as 3.88 × 10−5 m/m. This was smaller than that of the basalt-fiber-based samples with 2% and 3% loading. This was an indication of higher deformability under loading when there was 2% and 3% basalt fiber in concrete. Such behavior in basalt-fiber-reinforced concrete can prove beneficial under severe loading conditions, e.g., in the case of earthquakes. Similar results have been reported in the literature that a hybrid effect of fibers and fillers improved the crack resistance in reinforced composites and concretes. This performance was dependent on the dosing percentage of the micro-fillers [The sample with 3% coarse aggregates was also simulated under 700 × 10-fillers ,45.5 N tensile force are summarized in The results of the simulation at 50 × 10The results of the simulation based on the corresponding load values obtained from the experimental tensile tests are summarized in The meshing used for the FEM was relatively coarse (because of the limitation of the number of nodes for which computation could be performed on the software). Although this did not have much effect on the amount of deformation, the other parameters  may have varied because of the difference in meshing, and thus the values may have been more accurate and precise. But it can be clearly observed that the trend was similar and independent of the meshing density/intensity. The conditions given in the experiment and the simulations were similar; therefore, the values obtained through the simulation were validated with the obtained experimental values. Thus, it is important to note that the trends were found to be similar to those shown in 5 N force, the deformations in all the samples were almost the same . The Young’s modulus increased between the 0% and 1% basalt-fiber-based samples but remained almost the same for the 2% and 3% fiber-reinforced samples. The same behavior was also observed from the experiments (the strain energies were compared to compare the Young’s moduli). The force just-before-failure can also be noted . Maximum deformation was obtained for the 3% basalt-fiber-reinforced concrete, followed by the 2% fiber, 1% fiber, and pure concrete slabs. Therefore, it can be concluded that the values significantly varied when the fiber weight percentage was increased from 0% to 1%, but after that, they remained fairly similar, especially for those of the 2% and 3% basalt-fiber-reinforced samples (from 50 × 105 N force).It can be observed from the results of the simulation that regarding 50 × 105 N force category). This seemed to prove that the basalt fiber distribution in the concrete mix influenced the strength, but the fiber structure itself did not affect the mechanical properties. The simulations for the 3% coarse-aggregate-reinforced concrete were conducted using a finer mesh, since the results were not obtained for the same coarse mesh used for other samples, but the values were comparable with those obtained for the pure concrete slabs with fine mesh. There was not much improvement of mechanical performance in the case of the coarse aggregates.Other simulations were conducted in order to understand the influence of fillers, e.g., 3% basalt fiber, 3% fine aggregates, or 3% coarse aggregates. The behaviors of basalt-fiber- or fine-aggregate-reinforced concrete slabs were very similar. However, the 3% coarse-aggregate-reinforced sample showed very different results . From the simulations, it was also established that the percentage of basalt fiber (or aggregates) did not seem to make much difference when the percentage was increased from 1% to 3% , but the increase from 0% to 1% significantly influenced the mechanical behavior. Maximum stress was predicted for 3% basalt-fiber-reinforced concrete samples. The results were found to be similar to those reported in the literature in this area. The simulations were further validated with experimental samples with relatively higher accuracy. The error of prediction was limited to 3%. Moreover, the distribution of the filler material (fiber or aggregates) in the sample influenced the mechanical properties, as observed from the 3% coarse aggregate and pure concrete samples. The fiber’s internal structure itself did not have much effect on the mechanical properties of the concrete sample (shown by similar results for fine aggregates and fibers). The simulation software only considered the values of Young’s modulus and Poisson’s ratio for fiber-reinforced concrete. Changing the input parameters into ultimate tensile and compression strength or yield point strength did not affect the results.


Suboptimal antibiotic prescribing may be more common in patients living in rural versus urban areas due to various factors such as decreased access to care and diagnostic testing equipment. Prior work demonstrated a rural health disparity of overprescribing antibiotics and longer durations of antibiotic therapy in the United States; however, large-scale evaluations are limited. We evaluated the association of rural residence with suboptimal outpatient antibiotic use in the national Veterans Affairs (VA) system. Outpatient antibiotic dispensing was assessed for the veterans diagnosed with an upper respiratory tract infection (URI), pneumonia (PNA), urinary tract infection (UTI), or skin and soft tissue infection (SSTI) in 2010–2020. Rural–urban status was determined using rural–urban commuting area codes. Suboptimal antibiotic use was defined as (1) outpatient fluoroquinolone dispensing and (2) longer antibiotic courses (>ten days). Geographic variation in suboptimal antibiotic use was mapped. Time trends in suboptimal antibiotic use were assessed with Joinpoint regression. While controlling for confounding, the association of rurality and suboptimal antibiotic use was assessed with generalized linear mixed models with a binary distribution and logit link, accounting for clustering by region and year. Of the 1,405,642 veterans diagnosed with a URI, PNA, UTI, or SSTI and dispensed an outpatient antibiotic, 22.8% were rural-residing. In 2010–2020, in the rural- and urban-residing veterans, the proportion of dispensed fluoroquinolones declined by 9.9% and 10.6% per year, respectively. The rural-residing veterans were more likely to be prescribed fluoroquinolones , 1.03; 95% confidence interval (CI), 1.02–1.04) and longer antibiotic courses  than the urban-residing veterans. Among a large national cohort of veterans diagnosed with URIs, PNA, UTIs, and SSTIs, fluoroquinolone use and longer antibiotic courses were disproportionally more common among rural- as compared to urban-residing veterans. Outpatient antibiotic prescribing must be improved, particularly for rural-residing patients. There are many possible solutions, of which antibiotic stewardship interventions are but one. Appropriate antibiotic use is an important public health priority in all healthcare settings. The majority of antibiotic expenditures >60%) and consumption 80–90%) occur in outpatients . Each ye0% and co0–90% occClostridioides difficile infection, selection of resistance, and several serious and disabling side effects, such as tendinitis, tendon rupture, myasthenia gravis, QT interval prolongation, severe hypoglycemia, and mental health effects relative to other antibiotics [Fluoroquinolone use and long courses of therapy are two important process metrics targeted by outpatient antibiotic stewardship programs. Despite their utility as a broad-spectrum option for urinary tract infections (UTIs), cellulitis, and upper respiratory infections, oral fluoroquinolones are often overprescribed when more selective options are available . Each yeibiotics ,13. Sincibiotics . Beyond ibiotics .C. difficile infection, compared to shorter courses [Another area of focus for antibiotic stewardship programs is the use of longer than recommended antibiotic courses . Nearly  courses ,17,18.This paper focuses on the disparities in inappropriate antibiotic prescribing in patients living in rural areas. There are several reasons why rural-residing patients may be at a higher risk of inappropriate antibiotic prescribing, including decreased access to care and diagnostic testing equipment, such as X-ray, ECG, and biochemistry and microbiology testing facilities ,9,19. Clp < 0.05) from those residing in urban locations. The rural-residing veterans were older (60.7 vs. 58.3 years) and more likely to be of the White race (83.1% vs. 68.8%) and less likely to be of the Black race (9% vs. 21.7%) and other races (7.9% vs. 9.5%) than the urban-residing veterans. The distribution of rural- versus urban-residing veterans varied by region. Several chronic conditions, including chronic pulmonary disease (19.1% vs. 15.5%), diabetes mellitus (31.3% vs. 28.7%), and hypertension (56.2% vs. 51.1%), were more common in the rural-residing veterans. The median Charlson comorbidity score for the cohort was 0, and the median Elixhauser score was 2.We identified 1,405,642 patients who were dispensed an antibiotic in a VA outpatient setting and diagnosed with an upper respiratory tract infection, pneumonia, UTI, or SSTI between 2010 and 2020, of which 22.8% lived in a rural location. Demographics and comorbidities of VA outpatients by rurality are presented in Trends in suboptimal antibiotic use by rurality are presented in Outpatient antibiotic treatments are presented in The median duration of antibiotic prescriptions for our cohort of VA outpatients was 9 days (interquartile range (IQR), 5–10). The median duration was longer in the rural-residing veterans  than in the urban-residing veterans . In adjusted analyses, the rural-residing veterans were more likely to be prescribed longer antibiotic courses  and longer antibiotic courses in all the four regions. Mixed results were found in a previous large national cohort of women with uncomplicated UTI, with the rural-residing women having a varying likelihood of receiving inappropriate agents by region but consistently being more likely to receive an inappropriate duration across all the regions . There are several reasons that rural-residing veterans may be exposed to more risky outpatient antibiotic prescriptions beyond remoteness and limited access to high-quality ID care. A recent systematic review identified several factors influencing antimicrobial prescribing in rural and remote primary healthcare settings, related to upstream factors, healthcare facilities, physicians and other healthcare providers, and patients in these settings . While tRural health disparities and antibiotic stewardship are important VA priorities ,33. As sThere are limitations to this observational study which utilized secondary data sources. There are important differences (known and unknown) between rural-residing veterans and urban-residing patients who receive suboptimal antibiotics. We did adjust for known and measured confounders of rurality and suboptimal antibiotic use; however, our results may be biased by residual confounding due to other unknown and/or unmeasured factors . Our work is also limited by the accuracy of the data captured by the data sources, particularly pharmacy data. We only captured the antibiotics filled within the VA healthcare system, and therefore our data may underestimate exposure, given that some patients may obtain their antibiotics from external sources . While our population was limited to patients with a recent diagnosis of a common outpatient infection, our results are limited in that indications for the antibiotics prescribed were not captured. We assumed that the infection diagnosis captured represented the antibiotic indication.Our definition of rural–urban status was based on zip code data rather than distance or access to urbanized areas or VA healthcare facilities. Additionally, we measured fluoroquinolone use and longer courses of antibiotics as surrogates of potentially inappropriate outpatient prescribing practices since there is no gold-standard definition for inappropriate outpatient prescribing. As such, some of the fluoroquinolone prescribing and longer durations may have been appropriate based on best-practice recommendations of the Infectious Diseases Society of America. For example, for community-acquired pneumonia, levofloxacin or moxifloxacin are recommended for outpatients, for pyelonephritis or complicated UTI, fluoroquinolones are recommended, and for group A streptococcal pharyngitis, an antibiotic duration of 10 days is recommended ,36,37. MFuture research should continue to develop a consensus definition of inappropriate outpatient antibiotic prescribing and investigate disparities among rural-residing patients. We conducted a retrospective study using the national VA data accessed through the VA Informatics and Computing Infrastructure (VINCI) . VA is tThe datasets used included outpatient and inpatient pharmacy data, patient demographics, vital status, inpatient and outpatient medical visits, surgeries, procedures, microbiology results, laboratory results, and vital signs. We included the veterans with an upper respiratory infection, pneumonia, UTI, or SSTI diagnosis and acute outpatient antibiotic dispensing (duration < 30 days) between January 2010 to December 2020. We included the first qualifying outpatient antibiotic treatment course during the study period, which included all the antibiotics dispensed from the start to the end of treatment.We defined rurality using the five-digit US Postal Service zone improvement plan (ZIP) codes of the veteran’s home address per the definitions of the Rural–Urban Commuting Areas (RUCA) ,40. We uAntibiotic dispensing was evaluated by agent, class, and duration. The following antibiotic classes were evaluated: penicillins , beta-lactams with increased activity , fluoroquinolones , macrolides , cephalosporins , tetracyclines , and urinary tract antibiotics . Antibiotic class definitions were based on those used by the Centers for Disease Control and Prevention (CDC) for outpatient antibiotic prescriptions . The CDCWe evaluated demographics and comorbidities, where comorbidities were identified using the International Classification of Diseases, Ninth or Tenth Revision (ICD-9 or 10) diagnosis and procedure codes in the year prior to the first day of antibiotic treatment, including the summary comorbidity Charlson and Elixhauser scores.p < 0.05. Additionally, we plotted state-level maps of suboptimal outpatient antibiotic use, stratified by rurality. We first assessed rural–urban temporal trends differences in suboptimal outpatient antibiotic use, defined as (1) fluoroquinolone use and (2) longer antibiotic courses, over the study period . Longer t-tests or nonparametric Wilcoxon tests for the continuous variables, where appropriate. To examine the relationship between rurality and suboptimal outpatient antibiotic use, defined as (1) fluoroquinolone use and (2) longer antibiotic courses, we used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) adjusting for confounders. Previous work demonstrated that comorbidity burden (including the Charlson score) is associated with potentially inappropriate medications in VA patients [p-value < 0.1, retained-in-model p-value < 0.001) and accounted for clustering by region and year. We used generalized linear models to compare the mean durations of antibiotic courses by rurality. We also conducted stratified analyses by region and infection diagnosis.We compared demographics, comorbidities, and antibiotic prescriptions between the rural-residing and urban-residing veterans. We used the chi-squared or Fisher’s exact tests for the categorical variables, where appropriate, and patients . ConfounOur large national cohort of over 1.4 million veterans diagnosed with upper respiratory infections, pneumonia, UTIs, and SSTIs demonstrated two areas of risky outpatient prescribing, specifically fluoroquinolone use and longer antibiotic courses, were disproportionally higher among our rural-residing veterans. Fluoroquinolone use and longer antibiotic prescribing are process metrics that should be followed by antibiotic stewardship teams in rural and urban outpatient patients. Telehealth approaches that provide patients with an increased access to high-quality specialized ID care and antibiotic stewardship may be helpful in reducing risky antibiotic prescribing practices in rural-residing patients.


When it was continued to react with titanium-hybridized aminopropyl-polyhedral oligomeric silsesquioxane (Ti-POSS) through a Schiff-base reaction, new grafted copolymers poly[(Ti-POSS-HAMA)m-b-HEPOMAn] (abbrev. PolyTi) were obtained. Then, they were used as macromolecular flame retardant to modify epoxy resin materials. The thermal, flame retardant and mechanical properties of the prepared EP/PolyTi composites were tested by TGA, DSC, LOI, UL-94, SEM, Raman, DMA, etc. The migration of phosphorus moiety from epoxy resin composites was analyzed by immersing the composites into ethanol/H2O solution and recording the extraction solution by UV-Vis spectroscopy. The results showed that the added PolyTi enhanced the glass transition temperature, the carbon residue, the graphitization of char, LOI, and mechanical properties of the EP/PolyTi composites when compared to pure cured EP. Furthermore, the phosphorus moieties were more likely to migrate from EP/DOPO composites than that from EP/PolyTi composites. Obviously, compared with small molecular flame retardant modified EP, the macromolecular flame retardant modified EP/PolyTi composites exhibited better thermal stability, flame retardancy, and resistance to migration.In this paper, the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-containing diblock copolymer poly[ Epoxy resin (EP) is a very important polymer material, which has good thermal stability, mechanical properties and processability. However, epoxy resin is easy to burn and unsuitable for most applications. With more stringent requirements for environmental protection, flame retardant, and fireproof functions of materials, the development of flame-retardant modified epoxy resin composites have become an important research topic ,2. Usual1.5)n and the molecular size was about 1–3 nm, which is an intermediate between silica and polysiloxane (R2SiO)n. POSS can be incorporated into polymers by physical blending or copolymerization, endowing the composite materials with good mechanical and thermal properties. The related development of POSS has grown rapidly over the past few decades. For example, epoxy- or amino-functionalized POSS can participate in the epoxy curing process, thereby introducing POSS into the epoxy curing network. It is found that the POSS-modified epoxy resin has obvious self-extinguishing effect with a low heat release [POSS is an organic-inorganic hybrid molecule with an inorganic Si-O skeleton as the cage core and the organic substituents at the eight corners as reactive functional groups. The general formula of POSS is oxy)ethyl methacrylate)n] (abbrev. poly(HAMAm-b-HEPOMAn)) were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization. And then, titanium-hybridized aminopropyl-POSS (Ti-POSS) reacted with poly(HAMAm-b-HEPOMAn) via a Schiff-base reaction to synthesize grafted copolymers poly[(Ti-POSS-HAMA)m-b-HEPOMAn] (abbrev. PolyTi), which contained DOPO and Ti-POSS units. Meanwhile, the grafted copolymer without titanium element poly[(POSS-HAMA)m-b-HEPOMAn] (abbrev. PolyC) was also synthesized from poly(HAMAm-b-HEPOMAn) and aminopropyl POSS for a comparison. The chemical structure and thermal properties of the polymers were characterized by 1H NMR, FITR, XRD, TGA, and DSC. In addition, the POSS-grafted and Ti-POSS-grafted copolymers were added to epoxy resin as flame retardants to prepare the EP/PolyC and EP/PolyTi composites, respectively. Finally, the thermal, flame retardant and mechanical performance of the prepared epoxy resin composites were tested by TGA, DSC, LOI, UL-94, SEM, Raman, DMA, etc., and the influence of a block ratio with a different Ti content on the flame retardancy was discussed. Moreover, the migration of phosphorus moiety DOPO from epoxy resin composites was evaluated by immersing the composites into ethanol/H2O solution and recording the extraction solution by UV-Vis spectroscopy.Recently, there has been a growing concern about phosphorus flame retardant as emerging contaminants with increasing environment emission. For the sake of human health and environment safety, the release and exposure of phosphorus in water should be controlled. One strategy is to replace small organic phosphorus molecules such as organophosphate esters and DOPO derivates with phosphorus-containing macromolecules. In the present work, poly, poly[(Ti-POSS-HAMA)28-b-HEPOMA30] and poly[(Ti-POSS-HAMA)28-b-HEPOMA109] were obtained, which were named as PolyTi1, PolyTi2 and PolyTi3. The synthesis of Ti-POSS grafted copolymers: firstly, Poly1 (1.1160 g), Poly2 (1.6320 g) and Poly3 (4.7280 g) separately dissolved in DCM under stirring. Secondly, Ti-hybridized aminopropyl-POSS  were added into the Poly1, Poly2 and Poly3 solution, respectively. After reacting for 12 h at room temperature, the mixture was concentrated with a rotary evaporator and then precipitated with 200 mL acetonitrile. The Ti-POSS-grafted copolymers of poly was obtained by filtration. It was named as PolyC and used as a comparison sample.Similarly, added the stoichiometric aminopropyl POSS (NHPolyTi was added into DGEBA (E51) for preparing EP/PolyTi composites. Firstly, E51 was heated to 60 °C and stirred for 20 min. Secondly, PolyTi was dissolved in DCM, and then dropped into E51. After stirring for 30 min, it was heated up to 90 °C and a certain amount of DDM was added. Thirdly, after all the PolyTi and DDM was mixed homogeneously, a vacuum pump was used to remove the solvent, water, air and other small molecules. Finally, the mixture was poured into an aluminum mould and thermally cured at 120 °C for 4 h, 140 °C for 2 h and 180 °C for 2 h. The compositions of the prepared EP/PolyTi composites were listed in A series of approximately 1.0 g EP composite samples with similar total surface area were weighed and then put into tubes. A total of 10 mL of 10% ethanol solution and 50% ethanol solution were added into tubes, respectively. Then, the samples were sealed and kept at room temperature for 8 months. Finally, the extraction solution was removed and the absorption curve was recorded by UV-Vis spectroscopy.1H NMR spectra were recorded on a Bruker Avance 400 MHz NMR spectrometer  with a standard 5 mm probe at 25 °C using CDCl3 as solvent. IR spectra were characterized by a Nicolet iS10 FTIR . XRD spectra were tested by Bruker-AXS XRD (D8-A25)  with a scan angle of 5–80°. Thermogravimetric analysis (TGA) was tested on a Netzsch STA 409EP by heating from 35 to 800 °C at a heating rate of 10 °C/min under air or inert gas atmosphere. DSC was measured by using Netzsch STA 449C heating from room temperature to 250 °C under N2. The limited oxygen index (LOI) was conducted on fire testing technology oxygen index with samples size 80 × 10 × 4 mm according to ISO 4589. The vertical burning test was performed by using a FTT 0082 UL-94 instrument according to IEC 60695-11-10. Scanning electron microscopy (SEM) was conducted on an SU-70 microscope to observe the morphology of the inner and outer surfaces of the residual carbon and the morphological structures of the fracture surfaces. The release of DOPO moiety was determined by a UV-2550 spectrometer .m-b-HEPOMAn) were shown in −1, 1473 cm−1 and 965.9 cm−1, respectively  (PolyC) and poly[(Ti-POSS-HAMA)m-b-HEPOMAn] (PolyTi). The IR spectra of PolyC and PolyTi were shown in m-b-HEPOMAn) in −1 appeared, which indicated the formation of C=N bond and Si-O-Si bond, respectively. In addition, there also appeared a new peak at 914 cm−1 for PolyTi, which was assigned to the stretching vibration absorption of Ti-O-Si  containing Ti-POSS moiety and DOPO units were prepared by a aldehyde amine condensation Schiff-base reaction. It showed that the cage-like structure of POSS in side-chains provided physical cross-linking points, which improved the interaction between polymer chains and made the melting temperature higher. The cage structure of Ti-POSS primitive can increase the free volume between chain segments, and the molecules are prone to displacement after being stressed, which played a role in transmitting energy. Therefore, the higher the content of Ti-POSS primitive in a certain range, the better the mechanical properties. When the ratio m/n of the two blocks in PolyTi was about 1, the EP/PolyTi2 composite could achieve good comprehensive properties. Compared with pure EP, the Tg of EP/PolyTi2 was 170.4 °C and the LOI was 28.8%, which was increased by 7.3% and 25.0%, respectively. In addition, the maximum bending strength and fracture energy of the cured EP was 178.32 MPa and 394.33 N/m, respectively. Meanwhile, the storage modulus of EP/PolyTi2 composite was 1288 MPa, higher than that of EP/PolyC with a value of 1245 MPa. Obviously, the addition of PolyTi could raise Tg of EP/PolyTi composites to a relatively high temperature to meet the working requirements under a high temperature. What is more, the phosphorus moieties were less likely to migrate from EP/PolyTi composites than that from EP/DOPO. In a word, the new macromolecular flame retardant PolyTi can play an important role in improving the degree of graphitization of char, flame retardancy, thermal and mechanical properties of the modified EP/PolyTi composites, accompanying with a better resistance to migration, which will be of significance to application aspect and environment protection.In this paper, three diblock copolymers with different degrees of polymerization, poly(HAMA


Vitiligo is a common dermatological disorder affecting 1–2% of the world’s population. It is characterized by postnatal, autoimmune destructions of melanocytes in the skin, resulting in patches of depigmentation. Autoimmunity in vitiligo may also affect melanocytes in non-integumental tissues, including the eyes where choroidal melanocytes are the target of the autoimmune response. The Smyth line (SL) of chicken is the only animal model that spontaneously and predictably develops all clinical and biological manifestations of autoimmune vitiligo. In SL vitiligo (SLV), destruction of epidermal melanocytes in growing feathers (GFs) involves a melanocyte-specific, Th1-mediated cellular immune response. Smyth chickens may also exhibit uveitis and vision impairment. Previous studies established a strong association between SLV and vision impairment, including similar pathology in affected eyes and GFs. To determine the presence, types, and activities of choroid infiltrating mononuclear cells, we collected eyes before, near onset, and during active SLV from sighted, partially blind, and blind SL chickens. All SL chickens with vision impairment had SLV. Immunohistochemistry and quantitative reverse transcriptase-PCR analyses revealed mononuclear cell and cytokine expression profiles in the autoimmune destruction of melanocytes in choroids that are identical to those described in GF, demonstrating the systemic nature of autoimmunity against melanocytes in SLV. In addition, we observed aberrant melanogenesis in SL eyes. The immunopathogenesis in SL vision impairment resembles human vitiligo-associated ocular diseases, especially Vogt–Koyanagi–Harada syndrome and sympathetic ophthalmia. Hence, the Smyth chicken autoimmune vitiligo model provides the opportunity to expand our understanding of spontaneous autoimmune pigmentation disorders and to develop effective treatment strategies. Vitiligo is a progressive pigmentary disorder characterized by autoimmune loss of epidermal melanocytes in the skin, resulting in white patches of the skin. Vitiligo affects about 1% of the world’s population –4. The SB locus) 101. The incidence of visual problems in the SLV populations varies year to year from 5 to 20%, although mating of affected birds greatly increases the prevalence of visual problems in offspring  maintained by G. F. Erf at the University of Arkansas Systems, Division of Agriculture in Fayetteville. The Arkansas SL vitiligo model was established in 1996 from fertilized eggs provided by Dr. J. R. Smyth, Jr. and consists of three lines: the vitiligo-susceptible SL with an 80–95% vitiligo-incidence, the vitiligo-susceptible parental Brown line (BL) which continues to have a 1–2% vitiligo incidence, and the vitiligo-resistant Light-brown Leghorn (LBL) which serves as the pigmentation control. All three lines are homozygous for MHC  infiltrated the pulp of GF 3–4 weeks before SLV onset, reached the highest levels near SLV onset, remained elevated throughout active SLV (4–8 weeks), and returned to near baseline levels when melanocyte destruction was complete. Within the T cell populations, CD4+ T helper cells reached peak levels 3–7 days before SLV onset and started to decline 3–7 days after onset, whereas CD8+ cytotoxic T cells reached maximal levels within days after onset and remained at high levels until complete loss of melanocytes. At the onset of SLV, the ratio between CD4+ and CD8+ T cells in the feather pulp was near 1.0 and decreased to below 0.4 as melanocyte destruction progressed –17. DuriConsidering the established link between vitiligo development and vision problems in SL chickens, and the reported similarities in melanocytes degeneration and mononuclear cell infiltration in affected GF and eyes, we hypothesize that autoimmune activities in the eye parallel those observed in vitiliginous GF. The objective of this study was to examine the presence, type, and activities of mononuclear cells in the eyes of fully sighted, partially blind, and blind SL chickens and in normally sighted BL and LBL controls. For this, eyes were collected at 1 week of age when no abnormalities were reported in previous studies, at 4 weeks when early signs of melanocyte degenerative processes were described, and at 12 weeks when melanocyte degeneration, mononuclear cells infiltration, and vision problems were observed in vitiliginous SL chickens. To gain insight into melanocyte activities in eye tissue of SL and controls, the expression of melanogenesis-related genes also was examined.All procedures involving animals were approved by the Institutional Animal Care and Use Committee (protocol # 08011). For this study, SL, BL, and LBL chicks from a large pedigreed breeder replacement hatch were raised under conventional husbandry conditions by G. F. Erf on the Agricultural Experiment Station’s Poultry Farm in Fayetteville, AR, United States. The SL chicken has a high incidence of vitiligo development (about 80–95%), and frequently shows signs of visual impairment (5–20%). Non-vitiliginous BL  and LBL (vitiligo resistant) chickens were also included as normally sighted controls.Chickens were checked weekly for visual acuity based on their response to hand signals as described in Boissy et al. . During 2 inhalation (1 and 4 weeks) or i.v. injection of sodium pentobarbital (8 and 12 weeks). Both eyes were collected from each bird, placed in separate aluminum cups in OCT freezing medium with the pupil and cornea facing the side of the cup. Eye samples were snap-frozen in liquid nitrogen and stored at -80°C until processed for immunohistochemical staining and gene-expression analyses.For eye collection, chicks were euthanized by COUsing a cryostat (Microm Microtome HM505 E) at −29°C, thick, horizontal sections (100 μm) were cut from one eye of each bird until nearing maximal eye diameter and the optic nerve and pecten were visible (middle of the eye). The cutting thickness was then changed to 7 μm to cut a total of 8 sections for immunohistochemical (IHC) staining. Individual sections were placed on poly-L-lysine coated microscope slides and fixed in acetone for 5 min. Eye sections were blocked overnight with 10% horse serum in PBS in a humidifying chamber. The next day, slides were stained as described in Erf et al. . Briefly® Plus software  as described in Erf and Ramachandran  equipped with a Cool SNAP digital camera and computer. The isotype control-stained sections were evaluated for nonspecific staining, endogenous peroxidase activity, choroidal melanocyte damage , and appearance of the RPE . The relative amount (% area) of immunostaining for various leukocyte populations and MHC class II+ cells in choroids was determined by image analysis using ImageProchandran .CT method was used to determine relative gene expression (fold change) . Quantitative and qualitative RNA analysis was conducted using the lab-on-chip Experion™ RNA StdSens analysis kits and the Experion™ analyzer . The isolated RNA was reverse transcribed into complementary DNA (cDNA) using Taqman reverse transcription reagents . cDNA was used in a quantitative real-time polymerase reaction (qPCR) assay . Target  change) .P ≤ 0.05.One-way ANOVA was conducted to compare data between groups of chickens . ANOVA was followed by Fisher’s least-significant difference (LSD) multiple means comparison to determine differences between the individual groups. There were no differences between BL and LBL eyes at any age, hence, data were pooled (controls) for comparison with SL. Similarly, there were no differences in SL-IV partial samples collected at 8 and 12 weeks for any parameter examined, and, except for melanocyte and RPE scores, between SL-IV partial and SL-IV blind birds. Therefore, for all data, except melanocyte and RPE scores, 12-week comparisons were made between controls, SL-NV, and SL-IV, with SL-IV including all data from partially sighted (8 and 12 weeks) and blind (12 weeks) samples. Statistical analyses were carried out using SYSTAT software . All data are reported as mean ± SEM and means are considered different if All SL chickens which exhibited signs of visual impairment also had vitiligo . MicroscThe overall appearance of eyes in blind SL-IV birds was different from those of SL-NV. Blind SL-IV birds had swollen, vitiliginous eyelids, and sunken eyes with irregular-shaped pupils, pink sclera, and brown-red-colored iris instead of the yellowish iris with an outer black rim seen in SL-NV .P = 0.025 and 0.018, respectively) levels of MHC class II+ cells than controls (P ≤ 0.001) mononuclear cells infiltration, consisting predominantly of CD4+ and CD8+ T cells , followed by γδ TCR+ T cells (6%), B cells (7%), and macrophages (9%). Nearly 20% of cells in the choroid were MHC class II+ in SL-IV. The one 4-week-old SL-IV chick exhibited similar mononuclear cell profiles and MHC class II-staining in choroids as the chickens in the 12-week SL-IV group  of all mononuclear leukocyte populations examined . At 1 week, levels of MHC class II+ cells were low (1–2%) and not different between controls and SL-NV. However, at 4 and 12 weeks, SL-NV had 2- to 3-fold higher (controls . ChoroidIV group .P = 0.039) and IL-6 (P = 0.042), and lower levels of IL-10 (P = 0.048), in SL-NV than controls, while levels of IL-8, IL-21, and INF-γ were similarly low in both groups. There were no differences in these cytokine mRNA levels between controls and SL-NV at 4 and 12 weeks. At 12 weeks, expression of all cytokines examined was higher (P ≤ 0.001) in SL-IV than in control and SL-NV eyes, with IFN-γ reaching the highest levels. A similar cytokine mRNA expression profile was observed in one 4-week-old SL-IV chick with partial vision  and below 1 in SL-NV than in controls. At 4 weeks, expression levels of melanogenesis-related target genes were not different between controls and SL-NV, although variability was greater in SL-NV samples. For the 12-week groups, MC1R expression was lower (P ≤ 0.05) in controls than in SL-IV, and intermediate in SL-NV. Expression of MITF was similarly elevated in SL-NV and SL-IV and higher (P ≤ 0.05) than in controls. There were no differences in tyrosinase expression levels between the three groups, although mean levels were highest (above 1) and most variable in SL-NV. Expression of TRP1 was higher (P ≤ 0.05) in SL-NV than in SL-IV samples, whereas TRP1 expression in controls was not different from either SL-NV or SL-IV. For TRP2 expression, levels in SL-NV were higher than in controls, with similarly low expression in controls and SL-IV  chicken model described a loss of vision that only occurred in association with the cutaneous pigmentation loss in feathers. Moreover, histological evaluation of the autoimmune lesion in GF and eyes revealed many parallels in epidermal and choroidal melanocyte degeneration, including melanosome abnormalities and participation of mononuclear leukocytes , 13, 22.Similar to the autoimmune activities in GF, T cells dominated the mononuclear cell infiltrate in choroids of vision-impaired SL chickens with similarly high levels (% area) of CD4+ helper and CD8+ cytotoxic T cells , γδ T cells (6%), macrophages (9%), and B cells (7%). The same cell types were present at similar proportions in the GF-pulp during active vitiligo, although at lower levels . A majorIn this study, eyes were collected from different individuals at 1, 4, and 12 weeks of age, representing ages before SLV, the early phase of SLV before the visible loss of feather pigmentation, and active SLV, respectively . All SL-Differences in immune activities were also observed between controls and SL-NV at all ages. MHC class II expression was higher in SL-NV than in controls at 4 and 12 weeks and numerically elevated at 1 week. MHC class II expression may be the first sign of loss of ocular immune privilege and indicative of future SL-IV development . As in SMelanogenesis in choroidal melanocytes and RPE is generally considered to be complete within the first weeks of life in mammalian and avian species , 27–29. In summary, the tight link between the development of uveitis, loss of choroidal melanocytes, and vision impairment, and the manifestation of spontaneous autoimmune vitiligo in SL chickens are maintained in the only remaining population of SL chickens. All chickens with vision impairment had vitiligo and the vision problems were detected within 3 weeks of SLV onset. Our data support the hypothesis that the autoimmune activities that drive the pathogenesis of spontaneous SL uveitis and vision impairment parallel those involved in cutaneous SLV. Specifically, as in active SLV, the loss of choroidal melanocytes is associated with an INF-γ polarized, Th1 cell-mediated immune response and aberrant melanocyte function. The immunopathogenesis in SL vision impairment resembles induced uveitis and human ocular diseases, especially Vogt–Koyanagi–Harada syndrome and sympathetic ophthalmia, both of which are autoimmune disorders associated with vitiligo , 32–34. The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The animal study was reviewed and approved by the University of Arkansas IACUC.GE: conceptualization, resources, project administration, and writing original draft. JS: animal experiments and IHC and histology analyses. WH and KB: gene-expression analyses. JS, WH, and GE: statistical analyses and funding acquisition. GE, JS, KB, and WH: review and editing. JS and GE: visualization. KB and GE: supervision. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


H. pylori, a Gram-negative microaerophilic microorganism, is the only bacterial pathogen classified as a Class I carcinogen, due to its association, since its initial discovery, with severe gastric disease , and its extraordinary overall prevalence, estimated at 4.4 billion patients worldwide [orldwide ,2. It isH. pylori is a primary cause of gastric cancer, with a high mortality rate, immense resources are devoted to the development and research of treatment for H. pylori infections. Treatment is key to patient management, as H. pylori is responsible for histopathological cascades to cancer, which have been reported in large-scale epidemiological studies and reinforced by in vitro and in vivo studies. Furthermore, these data suggest that eradication of the bacterium may halt or even reverse carcinogenesis. Most infected patients receive empirical treatment with a proton pump inhibitor combined with dual antibiotics (tetracycline–metronidazole) or even triple antibiotics (amoxicillin–clarithromycin–metronidazole) combined with bismuth salts or dual antibiotics (amoxicillin–clarithromycin) without bismuth salts. However, the level of eradication failure is increasing due to a rise in resistance to first-line antibiotics, particularly clarithromycin. In some regions, where culture or PCR methods predominate, the rates of primary or secondary resistance to clarithromycin, metronidazole and quinolones increase over time, reaching levels that do not allow non-guided antibiotic therapy according to recommendations [As ndations . These undations .plp1 for amoxicillin; 16S rDNA for cyclins, 23S rDNA for clarithromycin, frxA/rdxA for metronidazole, gyrA/B for quinolon, rpoB for rifamycins), the democratization of nucleotide sequencing techniques (Ultra-deep Sequencing) coupled with the development of bioinformatics have recently favored investigations aimed at analyzing these bacterial populations [Mycobacterium tuberculosis.As the main genetic supports of antibiotic resistance have been “clearly” identified  on which the putative antibiotic-resistant strains will grow. Sequencing of the cultured strains must be performed so as to validate their transformation and to confirm the absence of compensatory mutation. In the absence of culture on resistant agar, sequencing and/or specific PCR should be performed on the entire subpopulation in order to observe and/or quantify the transformed subpopulation. This will enable definitive classification of the impact of the mutation on antibiotic resistance. In addition, special attention should be paid to the genetic background of the selected strain, the objective being to ensure that there are no mutations associated with geographic-specific antibiotic resistance. To resolve this problem, the authors could use the most appropriate reference strain according to the geographical location of the patient from whom the resistant strain was isolated, or else use two or more reference strains, thereby validating the impact of the mutation on the genetic background [From our point of view, the best validation of the impact of a genetic mutation in terms of antibiotic resistance could be based on transformation approaches. Helicobacter pylori is a naturally transformable bacterial strain that could easily be transformed using validated approaches described long ago since 1998) by Wang and Taylor . This pr by Wang Finally, it is important to emphasize that for diagnosis, at least two different biopsies, in the antrum and the fundus, are required. This is justified by the heterogeneity of the distribution of resistant bacterial subpopulations, which may nonetheless be present throughout the tract . In addiHelicobacter pylori. In such infections, it is widely recognized that guided antibiotic therapy is crucial to optimize clinical management. In the context of difficult bacterial culture and given the democratization of molecular biology systems in medical laboratories, validated databases developed in appropriate models to guide the development of new antibiotic molecules or diagnostic procedures are crucial prior to further exploration in animal model examples. The proposed approach will open a new field of research on therapeutic development designed to render therapies more effective by improving the initial choice of antibiotics. The results achieved will improve the clinical and fundamental knowledge of Helicobacter infections themselves.In conclusion, the increasing rate of antibiotic resistance is a major public health problem, especially in major bacterial pathogens such as