Zea mays) is the most important coarse cereal utilized as a major energy source for animal feed and humans. However, maize grains are deficient in methionine, an essential amino acid required for proper growth and development. Synthetic methionine has been used in animal feed, which is costlier and leads to adverse health effects on end-users. Bio-fortification of maize for methionine is, therefore, the most sustainable and environmental friendly approach. The zein proteins are responsible for methionine deposition in the form of δ-zein, which are major seed storage proteins of maize kernel. The present review summarizes various aspects of methionine including its importance and requirement for different subjects, its role in animal growth and performance, regulation of methionine content in maize and its utilization in human food. This review gives insight into improvement strategies including the selection of natural high-methionine mutants, molecular modulation of maize seed storage proteins and target key enzymes for sulphur metabolism and its flux towards the methionine synthesis, expression of synthetic genes, modifying gene codon and promoters employing genetic engineering approaches to enhance its expression. The compiled information on methionine and essential amino acids linked Quantitative Trait Loci in maize and orthologs cereals will give insight into the hotspot-linked genomic regions across the diverse range of maize germplasm through meta-QTL studies. The detailed information about candidate genes will provide the opportunity to target specific regions for gene editing to enhance methionine content in maize. Overall, this review will be helpful for researchers to design appropriate strategies to develop high-methionine maize.Maize ( It is also called the “Queen of Cereals” because of its high genetic yield potential among cereals. The worldwide production of maize was around 1123.07 million metric tons (M MT) in 2020-2021 (kharif (rainy season) crop. Total maize production accounts for ~10% of total food grain production in the country. India contributes around 2.80% of maize production with a quantum of 31.51 M MT in 2020-2021 .Maize is consumed as a staple food in Africa, South America and some parts of Asia. In India, about 60% (18.91 M MT) of maize produced is used for livestock and poultry feed, 20% (6.30 M MT) as food, the rest is used as fuel (3.0 M MT) and for industrial purposes (3.2 M MT) . The rapStructurally, the maize kernel consists of an embryo, a much larger endosperm and a pericarp . Nutritide novo and are thus a dietary source of this nutrient for animals. However, supplementation of feed with synthetic amino acids and mineral mixture is a common practice in the feed sector. Thus, synthetic amino acids have become a multimillion-dollar industry  are balanced in their amino acid composition. The high proportion of zeins in the endosperm is the primary reason for the poor protein quality of maize  as zeinso2 mutant maize lines, as they have high Lys content, but these lines failed to increase the level of Met, rather somewhat decreased its level  9 and 6, respectively (The most abundant α-zeins (19 and 22 kDa) are synthesized by four highly duplicated gene families distributed across six chromosomal locations on 4S consisting of more than 40 genes . Gene faectively . Due to ectively .1.1.3dzr1) which stabilizes the transcript of dzs10. This transcript has 22.5% codons for Met (dzr1 regulator is located in the untranslated regions (UTRs) of the mRNA of the dzs10 gene  trans-methylation to form S-adenosylmethionine (SAM), a primary methyl donor that methylates compounds to form products like creatine, which is used to produce energy in the form of adenosine triphosphate (ATP) during vigorous exercise, and phosphatidylcholine, which is a structural component of cell membranes mostly present on the outer leaflets of membranes and also plays a role in cell signaling; 2) trans-sulphuration to produce Cys, which is then incorporated into glutathione (used to protect against oxidative damage under oxidative stress) or catabolized to taurine ; and 3) On the other hand, Hence, there’s a need to consider the impact of dietary Met on public health in order to frame administrative policies around it. It is also essential to carefully assess the source of Met while measuring its potential effect on health. Plant proteins are taken up by animals, which later enter the food chain. Biological food processing and cooking results in changes to the protein structure and function. Oxidation of the dietary protein has been linked to a number of diseases . It has It is suggested that along with the bio-fortification, incorporation of antioxidant system in maize will be beneficial for animal feed . The aut1.2.2via Cys may alter the quantity of organic sulphur in TSAA  requirement of the body through the Met trans-sulphuration pathway, as Met acts as a precursor for Cys. Whereas, Cys is not able to act as a precursor for Met because the Met trans-sulphuration pathway is irreversible . A numbe in TSAA .1.31.3.1Amino acids are synthesized in bundle sheath cells during seed development in plants and transferred to the seeds, where they are stored in the form of proteins that are compatible with seed dormancy and germination. Sulphur is taken up by plants from the soil, reduced, and then integrated into Cys and Met in the leaf bundle sheath cells through sulfur assimilation Figure 142-) is the stable form of sulphur present in the soil, and plants can takeup this sulfate via roots, and convert +6 oxidation state of sulfate to −2 oxidation state of organic sulphur with the help of three enzymes, ATP sulphurylase, adenosine phosphosulfate reductase (APR) and sulfite reductase. The rate of sulfate assimilation is relatively low, accounting for 5% of the rate of nitrate assimilation and 0.1-0.2% of photosynthetic carbon reduction. The activities involved in sulfate assimilation are so minute that it is difficult to elucidate the reaction mechanism involved. The enzymes involved in Cys biosynthesis have been found in the cytosol, plastids and mitochondrion of various plants which reflects the inability of these organelles to transport Cys across their membranes (42- is first converted to adenosine 5’-adenylylsulfate (APS) through the enzyme ATP sulphurylase, APS then is converted to SO32- by the enzyme APR, then to sulfide (S2-) via sulfite reductase enzyme. Sulfide (S2-) molecule reacts with the O-acetyl serine (OAS) and forming Cys through the enzyme OAS thiol-lyase (OAStL). O-acetyl serine is formed from serine and acetyl CoA through serine acetyltransferase (SAT) enzyme. Formed Cys molecules are used for the synthesis of Cys rich proteins (β- and γ-zeins) and Met, Met then incorporation into the Met-rich δ- zeins protein , or it goes towards the synthesis of Met. Hence, OPH acts as common substrate for both cystathionine-gamma-synthase (CGS) and TS. These two enzymes (TS and CGS) compete with each other to form their respective products   is not fully understood because mmt mutants and wild type Arabidopsis thaliana plants both have the same amount of Met (Methionine synthesis takes place in the bundle sheath cells of the leaves and accumulates there during the vegetative phase. It is converted to S-methyl-L-methionine (SMM) through the activity of methionine S-methyl transferase and then transported to the seeds in the form of SMM or other appropriate forms during reproductive phase . The SMMse (HMT) . There ase (HMT) . The impse (HMT)  and rolet of Met . The trat of Met  and latet of Met  of seed via S-adenosylmethionine synthase. Decarboxylated SAM is formed through SAM decarboxylation. It supplies an aminopropyl group during polyamine production, following which Met is reproduced. The SAM is a biologically significant biomolecule because it plays a role in a variety of vital plant processes, including acting as a methyl group donor for DNA methylation and contributing to the discrimination of daughter and parent DNA during DNA repair. It also serves as a secondary metabolite and aids in the production of biotin and ethylene  and kernel hardness. Several studies were directed to identify QTLs associated with endosperm modification and protein quality including Met levels. Grain quality is an important feature that regulates the breeding programmes. The essential genes regulating the composition and structure of endosperm have been studied extensively. Multiple modifier genes contribute to superior grain quality under different genetic backgrounds . The mar1.4.2o2 lines decreases the Lys accumulation in contrast to unmodified counterparts. This decrease in Lys content in modified kernels is justified by increased zein content  as a common precursor (Ask2) was found to be linked to a QTL on Ch2L affecting FAA content  from the reported study had multiple effects on more than one amino acid. Biosynthesis of almost 11 amino acids (Alanine (Ala), Arginine (Arg), Aspartate (Asp), Glutamic acid (Glx), Glycine (Gly), Isoleucine (Ile), Leucine (Leu), Met, Phenylalanine (Phe), Tyrosine (Tyr), and Valine ) was contributed by QTL qAAC6.1  markers which will be an important stepping stone to accelerating the maize nutritional quality program globally.1.5o2 mutant) depend on the compensatory increase of Lys-rich non-zeins. According to the mechanism, an increase in Lys level tends to be accompanied by a decrease in Met content  in maize kernels is determined by the type of maize protein. In previous investigations, high δ-zein lines were found to be sufficient to substitute synthetic Met in a complete feed for poultry and human consumption . However content . The decabove 4% . As a reabove 4% . These s22.1o2 gene with the help of MAS and phenotypic screening for endosperm modifications. It’s QPM version was named “Vivek QPM 9” and released in India during 2008. There was significant improvement of Met by 3.4% in the “Vivek QPM 9” hybrid compared to its normal version “Vivek Hybrid 9” , were identified about 55 years ago  and aspartokinase2 (ask2), encoding enzymes free from feedback inhibition by Lys, have been found in maize  and alfalfa (Medicago sativa) which leads to the accumulation of free Met content in leaves but does not show any effect on the storage protein-bound Met. But, opposite results were attained in transgenic tobacco seeds which express a truncated version of the Arabidopsis cystathionine-γ-synthase (AtCGS) gene. The feedback-insensitive form of CGS enzyme produces less soluble Met but more bound Met  availability, the B101 exemplified the utmost natural threshold of Met accumulation in maize grain. This threshold apparently can be overcome with increased sulphur-reduction and assimilation during photosynthesis. The role of non-seed tissues in producing and transporting Met to the seed has been studied through genetic engineering. The transgenic maize line developed by using AtSAT1 gene from Arabidopsis thaliana under the control of leaf bundle sheath cell-specific promoter rbcS1  exhibited 12-fold higher activity of SAT enzyme and led to higher sulphur assimilation (Escherichia coli SAT gene (EcSAT) in rice resulted in a 40% and 4.8-fold increase in soluble and protein-bound Met, respectively (O-acetyl serine (thiol) lyase gene (OAS-tL) was overexpressed (pRbcs : AtSAT1-pRbcs : EcPAPR), which resulted in 2.24 fold increase of Met in maize  and bacterial feedback insensitive aspartate kinase gene have been inserted into narbon bean (Vicia narbonensis) (Brassica napus)   and rapea napus)  to impromulation Figure 32.2.4Another approach to enhance amino acid levels is by replacing a storage protein that is lacking in an amino acid with a protein that is enriched with particular amino acid. The sink capacity could be enhanced through the expression of genes encoding Met-rich protein content in the seed. Enhanced expression of Met-rich maize proteins probably led to lower expression of γ- and β-zeins genes . Silencidzs10 gene (Zm00001eb382030) located in chr9:47915348-47917942bp and 18 kDa δ-zein associated with the dzs18 gene (Zm00001eb281380) located in chr6:125301025-125303844bp  are key targets to enhance the Met percentage in maize.The higher Met level could be possible at the salvage of other sulphur-containing metabolites and/or enzymes. The reduced synthesis of Cys-containing proteins leads to increased sulphur flux to other amino acids such as Met, resulting in higher δ-zein proteins in the seed . In the In conclusion, targeting the maize protein with a lower Met percentage such as α, β and γ-zeins for its inhibition, or enhancement of protein rich in Met (10 and 18 kDa δ-zeins) will be the potential way for enhancing the protein-bound Met Figure 32.2.5aspartokinase under the seed-specific promoter at the final stage of seed development produce 6.5% more bound Met  accumulation in comparison to the wild-type (via genetic engineering techniques.The enzyme methionine gamma lyase (MGL) is present abundantly in the cytoplasm of all the plant’s organs except seeds which converts Met into methanethiol, ammonia and α-ketobutyrate. It has been reported that this enzyme had a higher kthe cell . The higild-type . It has ild-type . The rep2.2.6Arabidopsis thaliana  and potato plants with deficient TS enzyme activity produced higher free Met content in leaves  under the control of leaf-specific promoter, down-regulates the endogenous APR and increases the expression of gene coding for Cys-rich non-zein proteins. These transgenic maize lines produced 57.6% more kernel-bound Met than the best Met-rich maize inbred line B101 (Transgenic maize PE5 (contains the expression cassettes PepC-EcPAPR) with ine B101 . Transgeine B101 . Howeverine B101  or gene ine B101 . Reductiine B101 .In maize, targeted inhibition of TS and SAM synthase enzymes will be beneficial to enhance the Met accumulation. Silencing the expression of sulphur-deficient maize proteins may result in the accumulation of sulphur-rich proteins to balance the overall protein percentage and that can be a better approach for developing Met-rich maize germplasm Figure 32.2.7E. coli PAPS (3’-phosphoadenosine-5’-phosphosulfate) reductase (PPAR) and maize δ-zein and improved the Met content for 58% as compared to control without apparent proteome rebalancing. Thus, targeting the δ-zein protein or δ-zein encoding gene is important for Met regulation. The existence of alternative routes for Met synthesis through PPAR provides flexibility in metabolic engineering in maize.By modifying the genes encoding proteins with relatively higher Met in such a way that their encoding regions contain more codons for Met, or engineering the promoter region of those genes to enhance their expression in turn leads to higher accumulation of δ-zein protein in maize endosperm during seed development. This strategy mainly encountered problems of protein instability and relatively small improvement . A gene 2.2.8lpomoea batatas) and soybean, seed-specific expression of synthetic genes (MB-16 for soybean) resulted in seed protein with 13-16 percent (higher) Met residues  associated with Met production has been prepared Table 3 2.3.1As methionine regulation is a complex process the strategies have to be used in combination to enhance the Met content. This combinatorial strategy works on improved sink and source relationship. In sink capacity, Met enriched albumin protein was added whereas the source was improved through making carbon family enzyme insensitive. Similar combinatorial strategy with insensitive SAT and sunflower albumin in lupin increased the Met content to 2-folds but the dosage effect of SAT was negligible . Recentl3via genetic engineering or genome-editing approaches. Although these strategies seem to be promising, their effectiveness depends upon the additional studies to define the effect of these manipulations on traits such as seed morphology, seed starch, amino acids, oil content and germination rate. Thus, genetic manipulation had proven successful in increasing the content of Met in seeds. Nevertheless, supplemental information is required to confirm the in vivo stability of genetically engineered Met-rich proteins for optimal fortification of seeds. Once nutritionally improved genetically modified (GM)/genetically edited (GEd) genotypes possessing high Met content in their seeds are being developed, there will be an urgent need to analyze the genotype with the best response for superior agronomic traits to perform well under field conditions.The enhancement of Met in the seed for balancing the amino acid content is a tricky process. A number of metabolic enzymes, transporters, genes and transcription factors are involved in regulating the biosynthesis and accumulation of Met. Apart from it, temporal separation for Met transporting molecules and spatial separation of sulphur assimilation makes the control of whole biosynthetic pathway a difficult task. The tissue-specific expression of Cys in bundle sheath cells and glutathione in mesophyll cells compartmentalizes the sulphur at the next higher level of cellular hierarchy. Hence, a combination of multiple approaches without compromising the yield is required to be adopted. The genomic regions associated with the trait identified in orthologous cereal crops could be used for identifying hotspot genomic regions in maize for the trait of interest. This review provides trait-related information which can be used further in metaQTL analysis to study the congruency of the identified regions associated with specific traits of interest. The strategies explained in this review will give potential insight into target enzymes and candidate genes, which can be used to enhance Met content Conceptualization, DC and VD; writing-original draft preparation, VD; writing-review and editing, BB, VS, MS, AS, CK, MG, SR, RK, and DC; supervision, DC. All authors contributed to the article and approved the submitted version.


The construction and coal industries generate substantial industrial waste, including coal gangue and construction and demolition (C&D) waste, leading to environmental pollution and high disposal costs. Integrating recycled aggregates (RAs) and coal gangue powder (CGP) into concrete is an effective approach for waste management. However, CGP can affect the performance of traditional recycled concrete. This study primarily aims to optimize the utilization of RAs and CGP while maintaining concrete performance. They utilized orthogonal experimental designs and microscopic characterization techniques, including scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), and X‐ray diffraction (XRD). Orthogonal experimental analysis indicated that with a water‐cement ratio (WCR) of 0.5 and replacement rates of 10% for CGP and 60% for RA, compressive and splitting tensile strengths reached 73.6% and 77.4% of ordinary C30 concrete, respectively. This mix proportion minimizes strength decline in coal gangue powder‐recycled aggregate concrete (CGP‐RAC) while maximizing recycled material replacement. Microscopic analysis revealed that CGP increased the Ca/Si ratio in cement paste, impeding hydration reactions, resulting in a looser internal structure and reduced concrete strength. These findings are anticipated to provide fresh theoretical insights for solid waste recycling and utilization. This study examined recycled concrete production using coarse recycled aggregates (RAs) to replace natural aggregates and a partial substitution of ordinary Portland cement with coal gangue powder (CGP). They identified the optimal CGP‐RA concrete mix ratio and analyzed microscopic factors affecting its performance decline. Their findings offer new insights for solid waste recycling. Concrete itself constitutes 50−70% of total C&D waste globally. Furthermore, the rapid development of infrastructure and urbanization in countries such as China has led to a surge in the generation of construction and demolition waste. This mounting waste accumulation urgently necessitates sustainable approaches for the disposal of C&D waste to reduce the use of landfills. In 2018, China's construction industry alone accounted for an energy consumption equivalent to 1.1 billion tons of standard coal and emitted 2.72 billion tons of carbon dioxide during the production of building materials. Notably, cement production contributed to 130 million tons of coal equivalent in energy consumption and 11.1 billion tons of carbon emissions, representing 11.8% and 40.8% of the total energy consumption and carbon emissions during the construction material production phase, respectively. Consequently, achieving the sustainable utilization of concrete while reducing energy consumption and carbon emissions associated with cement production is crucial in attaining carbon peak and carbon neutrality goals. Recycling industrial wastes as substitutes for natural aggregates and ordinary Portland cement in concrete offers potential benefits by reducing carbon emissions and reducing the use of landfills.Concrete, one of the most extensively utilized construction materials worldwide, has an average annual production of approximately one ton per person, resulting in a global output of ≈8 billion tons.1 Howe Argiz and Menéndez introduced CBA as a gel material into cement and found that the concrete's resistance to chloride and sulfate corrosion improved with an increase in the CBA content (within the range of 25%). Özkılıç et al. introduced varying proportions of waste glass aggregate (WGA) into a fixed ratio of alkali‐activated fly ash‐based geopolymer concrete. They conducted tests on its physical properties and observed that the concrete's performance was inversely related to the proportion of WGA but directly proportional to the NaOH concentration. They also established a strength model and derived an equation for predicting compressive strength. Karalar and Benzannache et al. partially replaced cement with marble powder to produce reinforced concrete beams (RCB). They observed that as the proportion of marble powder increased, the type of cracks in RCB shifted from bending cracks to shear cracks. Additionally, the flexural load‐bearing capacity of the beams gradually decreased but remained within an acceptable range. Furthermore, the compressive strength of the concrete also exhibited a slight decrease. In order to investigate the impact of recycled Polyethylene Terephthalate (PET) on the physical properties and durability of high‐strength concrete, Qaidi et al. added it as fine aggregate into the concrete. They found that both the physical and mechanical properties as well as the durability of the concrete decreased. Therefore, it is recommended to use it only for non‐structural applications, and the replacement ratio should not exceed 25%. In order to enhance the bond performance of ribbed steel bars embedded in recycled aggregate concrete (RAC), Fayed et al. employed steel mesh fabric cylinders (SMF) of various diameters to confine the recycled concrete around the steel bars. They conducted center pull‐out tests on 12 mm diameter steel bars embedded in concrete with varying levels of recycled concrete aggregate (RCA) replacement. The results showed that SMF significantly improved the ultimate bond strength of the confined specimens. Additionally, they proposed a formula to calculate the ultimate bond strength of RAC.To recycle and utilize these wastes, experts have conducted in‐depth research. Noor and colleagues incorporated coal bottom ash (CBA) as a fine aggregate into concrete and observed that as the percentage of CBA increased, the strength of the concrete decreased.9 Argi In 2018, global coal production reached 7.85 billion tons, with coal gangue accounting for ≈117–157 million tons. Developing countries, particularly China, have accumulated ≈5 billion tons of coal gangue, leading to severe environmental pollution and high disposal costs. Coal gangue contains significant amounts of siliceous and aluminous minerals, which give it a certain level of pozzolanic activity. Additionally, the chemical composition of coal gangue is similar to that of fly ash (FA), and research on the use of fly ash as a supplementary cementitious material has been conducted for nearly a century. Hence, research is underway on grinding coal gangue into powder and using it as a substitute for ordinary Portland cement.Coal gangue is an industrial waste generated during coal mining and processing operations.17 In  Due to its lightweight and high‐strength characteristics, researchers have investigated the crushing of coal gangue for use as an aggregate for recycled concrete. Studies of its physical properties and failure mechanisms showed that substituting natural coarse aggregates with coal gangue in the production of C30 and C40 concrete was feasible. To investigate the static and dynamic mechanical properties of coal gangue aggregate concrete (CGAC) in mine support structures, Yao et al. conducted compressive strength tests, drop hammer impact tests, and split Hopkinson pressure bar (SHPB) tests. The comprehensive results indicated that CGAC could be used for supporting coal mining engineering projects, considering its favorable performance in terms of compressive strength and resistance to dynamic loading. Zhang et al. utilized the spontaneous combustion gangue aggregate (SCGA) contained in coal gangue as a substitute for natural aggregates. They investigated the influence of the SCGA replacement ratio and particle size distribution on the mechanical properties of concrete. Furthermore, they proposed a method for predicting the mechanical performance of coarse SCGA‐concrete. The results demonstrated that SCGA had a significant impact on the mechanical properties of concrete. Zhang et al. utilized coal gangue as an aggregate to prepare thermal insulation concrete. They found that when the replacement ratio of coal gangue reached 30%, the comprehensive strength of the concrete reached its optimum level. Zhang et al. replaced natural sand with coal gangue sand in concrete and observed that coal gangue sand weakened the adhesive properties in the transition zone between mortar and coarse aggregates. Researchers investigated various volcanic ash materials and added them to concrete; These materials could improve the mechanical properties of recycled aggregate concrete. Zhu et al. introduced coal gasification slag (CGS) as a gel material in concrete. After subjecting the concrete to 125 cycles of freeze‐thaw testing, CGS concrete exhibited strong frost resistance. Guan et al. investigated the degradation mechanism of coal gangue concrete under the combined effects of bending load and freeze‐thaw cycles. Su et al. found that adding thermally activated coal gangue powder as a gel material to concrete results in a denser interfacial transition zone between aggregates and the matrix. Wang et al. developed steam‐cured aerated concrete using coal gangue (CGC) and iron ore tailings. They analyzed the material composition of coal gangue, the calcination temperature, and the composition of hydration products using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and scanning electron microscopy (SEM). The study revealed that coal gangue powder exhibited optimal volcanic ash activity when subjected to high‐temperature calcination at ≈600 °C, which could improve the microstructure of cement‐based systems. However, the high‐temperature calcination of coal gangue can release harmful substances, causing environmental pollution and posing health risks to humans. Moreover, the calcination process consumes a significant amount of energy, leading to increased carbon emissions that contradict the original intention of achieving carbon peak and carbon neutrality. Therefore, in this study, CGP was directly used to replace Portland cement, investigating its impact on the performance of recycled aggregate concrete. There are currently relatively few papers in this field.Currently, research on coal gangue concrete primarily focuses on the use of coal gangue as recycled coarse aggregates and its incorporation as a gel material in concrete.30 Due To achieve this objective, this study was based on the research of experts and scholars worldwide. It involved the utilization of coarse recycled aggregates obtained from construction and demolition waste (C&D) to replace natural aggregates at different substitution rates. Additionally, coal gangue micro‐scale powder is substituted for ordinary Portland cement (OPC) at various levels to produce recycled concrete. In this study, the influence of various factors on the strength of concrete was investigated by incorporating different percentages of CGP as a sole replacement, RA as a sole replacement, and varying the WCR. Furthermore, an orthogonal experiment was conducted to investigate the influence of different substitution percentages of RA , CGP substitution ratios of cement , and WCR values  on the macroscopic mechanical properties of CGP‐RAC. Moreover, SEM, EDS, and XRD techniques were employed to perform microscopic investigations on the morphology of CGP, elemental composition, hydration products, and hydration mechanism to reveal the mechanism of the influence of CGP on the strength of RACs.Sustainable concrete production necessitates the efficient use of energy and materials.47 To 22.1Figure and JGJ52‐2006. The results showed that compared to natural crushed stone, the particle size distribution of recycled aggregates was significantly uneven. The bulk density of RA was ≈10% less than that of NA, which indicated that RA was lighter than NA. The crushing index of RAs was 1.6 times that of natural aggregates NAs, which indicated that RA had less strength compared to NA. The water absorption of RA was 3.4 times that of NA, and the moisture content of RA was 4.2 times that of natural aggregates. Overall, the various indicators were significantly weaker for RA than NA. The particle size distribution curves of RAs and NAs are shown in FigureTableIn this study of CGP‐RAC, the main materials included RA, CGP, cement, natural sand, natural aggregates (NAs), and water. The recycled aggregates and natural aggregates used in this study were obtained from the Xijian Recycling Material Plant in Chengdu Figure1. The TableFigureThe natural raw coal gangue used in this study was sourced from Maping Mine in southwestern China. The XRD diffraction pattern revealed that the main components of the coal gangue were quartz, biotite, and pyroxen. The content of each component is presented in  The grading curve of the natural sand is shown in Figure All the blended materials complied with the requirements of GB/T175, including ordinary Portland cement with a nominal strength of 42.5 MPa (P.O.42.5R), ordinary tap water, and continuously graded natural sand.54 The2.2TableTableTableTableTable3) orthogonal column design. Thirty mixed proportions were established, resulting in a total of 276 cubic specimens for testing.Four concrete mix designs with a target strength of C30 were developed for this experiment. The compressive strength and splitting tensile strength of the four concrete mix designs were measured to investigate the influence of incorporating RA and CGP into concrete as well as the influence of WCR on the strength of RAC. The first group Table3 was d2.3 The RA should be pre‐wetted by immersing it in water for 10 min and then draining it for 10 min to achieve a state of saturated surface dryness before incorporating it into the concrete mix. A 30 L capacity single‐axis forced mixer was used in this experiment . The gel materials, fine aggregates, and water were first placed into the mixer and stirred for 60–90 s, followed by the addition of coarse aggregates and continued mixing for 120 s. According to the requirements of GB/T50080, the slump test was conducted on the fresh concrete, and the slump of the recycled concrete was slightly higher than that of the ordinary concrete. The prepared concrete was poured into a plastic mold and placed on a vibrating table to compact the mixture until it became smooth and dense. After 24 h of curing at room temperature, the concrete was demolded. The specimens were cured at 100% humidity for 7 or 28 days. After natural drying, they were subjected to mechanical performance testing. The preparation process is shown in FigureRecycled aggregate has greater porosity and water absorption capacity than natural aggregate, which means that it can absorb some of the water in concrete, decreasing the water‐cement ratio of the concrete. To maintain the workability of the concrete, it is necessary to pre‐treat RA to reduce its water absorption rate before mixing.56 The33.1 specimens with dimensions of 100 mm × 100 mm × 100 mm were used for the compressive strength test at a loading rate of 0.5 For the splitting tensile strength test, a loading rate of 0.05 MPa s−1 was applied. The steps for the splitting tensile strength test are as follows: 1) The specimen was removed from the curing water tank and checked for any damage, honeycombs, or surface defects. Any problematic specimens were discarded. 2) The axial centerline was marked on the surface of the specimen to determine the location of the splitting plane. 3) The flatness and height differences of the upper and lower pressure plates of the testing machine were checked to ensure compliance with the specifications. 4) A steel pad was placed in the center position of the pressure plate of the testing machine, and the specimen was positioned at the center of the steel pad. 5) The parameters of the testing machine were set; the loading rate was set to 0.05 MPa s−1. 6) The testing machine was started to conduct the test, the specimen was observed under tension, and the data were recorded. To reduce variability, the test results for three samples of each mix proportion were averaged. Photographs of the compressive strength test and split tensile strength test are shown in Figurefcu and ft represent the compressive strength and split tensile strength of the concrete specimens, respectively, (MPa); F represents the peak load at specimen failure, (N); and A is the cross‐sectional area of the specimen subjected to compressive or tensile stress, (mm2).Compressive strength tests were conducted on concrete cubes after 3, 7, and 28 days of curing using a 3000 kN computer‐controlled hydraulic servo pressure testing machine . According to the requirements of GB/T50081,58 spe3.2F value indicates the ratio of the mean square (MS) of each factor to that of the experimental error and is analyzed by the F test. The sum of squared deviations (SS) reflects the differences in experimental results caused by changes at every level of each factor or error and is calculated as follows:yj is the value of the result of each trial, and y¯ is the arithmetic average of yj.ANOVA is the statistical treatment most commonly applied to experimental results. It can be used to divide the influence of the factors from those of experimental error. The e F test.56 TheThe MS of each factor or experimental error is SS divided by the number of degrees of freedom (DF) and obtained by Equation .(4)MSF value (Fα) for a different level of significance, such as α = 0.01; 0.05, can be found in the F‐statistic distribution table. When F > F0.01, the factor effect for the results is highly significant to the index and marked as “***”. If F0.05 < F ≤ F0.01, then the corresponding factor has a significant effect on the index and is marked as “**”. If F0.1 < F ≤ F0.05, then the corresponding factor has a minimal impact on the index and is marked as “*”. If F < F0.1, then the corresponding factor has no impact on the index and is marked as “–”.The critical value of the F value Fα for a d3.3FigureFigureThe recycled concrete consists of a “five‐phase” structure, which includes coarse aggregates, old interfacial transition zone, old mortar, new interfacial transition zone, and new mortar, as illustrated in the diagram Figure6. This44.14.1.1FigureFigureIn Figure 4.1.2Figure This was attributed to the rough surface and high porosity of the recycled aggregates, which resulted in a water absorption rate three times greater than that of natural aggregates. During the concrete preparation process, the recycled aggregates tended to absorb a significant amount of water (considered in the mix design). The additional water absorbed and stored by the recycled aggregates was gradually released with increasing curing time. The released water could effectively reduce the heat generated by cement hydration, thereby balancing the temperature difference between the interior and exterior of the concrete. This process improved the mechanical properties of the concrete and is known as the “internal curing” effect. The internal curing effect could be better achieved when sufficient recycled aggregate was present, which allowed for adequate absorption and release of water. The presence of an excessive amount of recycled aggregate could have drawbacks such as less inherent strength and poor gradation, which could lead to a reduction in the overall strength of the concrete. This could explain why the concrete was strongest when the replacement ratio of recycled aggregate was ≈50–60%.Detailed information on the 28‐day compressive strength and split tensile strength of concrete with different substitution ratios of RA is provided in 4.1.3Figure4.24.2.1fcu at 3, 7, and 28 days from the orthogonal experiment can be found in TableFigurefcu values of all specimens in the orthogonal experiment were more than 32% of the 28‐d fcu values; Specimen Z7 reached 44.5%. For the control group, the values of the strength at 3 days were 33.3% and 31.9% of the values of the 28‐day strength. When the curing age was 7 days, every specimen had developed compressive strength that exceeded 50% of the 28‐day compressive strength. In particular, specimen Z1 reached a high compressive strength of 65.1%. The 7‐day compressive strengths of the reference group were 64.3% and 63.5% of the corresponding 28‐day strengths. At a curing age of 28 days, the specimens achieved a maximum compressive strength of 25.42 MPa, which was 75.6% and 73.6% of the compressive strengths of the reference group specimens. The development of ft for all specimens in the orthogonal experiment was similar to that of fcu. It showed a relatively fast initial development rate but ultimately exhibited varying degrees of decrease compared to the reference group  should follow the results of the single‐factor analysis.From According to Tables TableBased on the comprehensive analysis above, we concluded that the water‐cement ratio (Factor A) at the level of 0.45 (A1) was optimal in the range analysis trend graphs Figure  for 7 d.4.3In the study conducted in Section 4.3.1Figures4.3.2FiguresTablesThe analysis of EDS data can be divided into qualitative analysis and quantitative analysis. Qualitative analysis in EDS allows for rapid identification of the elements present in a test sample. Quantitative analysis, in contrast, builds upon qualitative analysis by calculating the relative intensities of signals to determine the concentration ratios or molar ratios of the corresponding elements. The chemical element distribution and energy spectrum of the EDS scans for the Z4 and Z9 test groups are shown in Figures  found that in low Ca/Si ratio cement, the C‐S‐H structure was more stable and ordered, with smaller cracks. In high Ca/Si ratio cement, the C‐S‐H structure was more disordered, and larger cracks were observed. According to Tables The calcium‐to‐silicon ratio (Ca/Si) in cement was an important factor that influenced the strength of the cementitious bond. Silicate cement is composed of minerals such as C3S, C2S, C3A, and others. These minerals undergo hydration reactions to form a gel‐like substance called calcium silicate hydrate (C‐S‐H), which significantly affects the strength and durability of the cement. Zhu et al.64 fou2 exhibits alkaline properties, while SiO2 exhibits acidic properties. When fly ash is present, it selectively adsorbs Ca2+ from the cementitious matrix while not adsorbing Si4+. Therefore, the presence of FA in cementitious materials can result in the presence of free calcium ions, leading to an increase in the Ca/Si ratio of the material. CGP, being a volcanic ash‐like material with similar physical and chemical properties to FA, also exhibits the same characteristic of adsorbing calcium ions. The higher Ca/Si ratio in the Z9 group compared to the Z4 group could be attributed to the higher content of coal gangue powder in the Z9 group. As the dosage of coal gangue powder increased, more free Ca2+ ions were present in the cement matrix, resulting in a larger Ca/Si ratio.The higher calcium‐to‐silicon ratio in the Z9 group compared to the Z4 group was attributed to the adsorption effect of FA on alkaline substances. In cementitious materials, Ca(OH)4.3.3FigureTo further investigate the influence of CGP on the hydration reaction mechanism, an XRD analysis was performed on the Z4 and Z9 test groups to analyze the hydration products. The test results are shown in 2 were more pronounced in both the Z4 and Z9 groups. However, the SiO2 diffraction peak was more intense for Z9 than Z4, indicating the presence of a certain amount of SiO2 crystals in the composite paste of both groups, with a higher concentration in Z9. Cement mainly consists of dicalcium silicate (C2S) and tricalcium silicate (C3S). When cement reacts with water, it undergoes hydration to form calcium silicate hydrate (C‐S‐H). Since C‐S‐H does not have a crystalline structure, it is difficult to determine its presence through XRD analysis. However, in the SEM micrograph at a magnification of 1 00 000x, we clearly observed the cloud‐like morphology of the C‐S‐H gel, as shown in Figure2 in the paste indicated the residue after hydration. At this stage, CaO has been completely consumed in the hydration reaction. Due to the relatively incomplete hydration reaction in the Z9 group, there was more remaining SiO2 in the paste, resulting in greater intensity of the SiO2 diffraction peak.In Figure 2 and Al2O3. It undergoes secondary hydration reactions with components in cement, such as Ca(OH)2, resulting in the formation of low‐alkalinity hydrated calcium silicate (C‐S‐H) gel. This phenomenon is commonly referred to as the volcanic ash effect. Figure 2 at 18.1°2θ, 34°2θ, and 50.8°2θ. Additionally, in Figure 2 could be identified. In contrast, Ca(OH)2 could not be observed in the XRD or SEM images of the Z9 group. This was attributed to the higher dosage of 10% CGP in Z9, which led to more consumption of Ca(OH)2 due to secondary hydration reactions. Furthermore, the water‐to‐binder ratio of Z9 was 0.05 greater than that of Z4. The increase in water content could result in the leaching and dissolution of Ca(OH)2, leading to the loosening of the cementitious matrix structure in Z9. Therefore, Ca(OH)2 could not be observed in Z9. This explained why, despite the more intense secondary hydration reaction in the internal structure of Z9 coal gangue recycled concrete compared to Z4, its compressive strength decreased by 30%. However, even the maximum strength achieved by Z4 reached only 73.6% of the compressive strength and 77.4% of the splitting tensile strength of ordinary concrete. This indicated that due to the differences in composition, the use of coal gangue micro‐scale powder as a replacement for cement severely hindered the original hydration reaction, resulting in poor development of hydration products and a decrease in concrete strength. While CGP exhibited volcanic ash activity and underwent secondary hydration reactions in the cementitious matrix, resulting in the formation of a small amount of hydration products with a certain strength contribution, it was not sufficient to compensate for the strength loss caused by the hindered primary hydration reaction.Coal gangue is a volcanic ash‐like supplementary cementitious material that contains a significant amount of amorphous SiO51)a) The influence of various factors on the early strength of CGP‐RAC was not significant. However, the compressive strength and splitting tensile strength of CGP‐RAC decreased with increasing water‐cement ratio. Therefore, the water‐cement ratio should be controlled between 0.45 and 0.5. The compressive strength and splitting tensile strength of CGP‐RAC decreased with increasing replacement rate of CGP‐RAC. The replacement rate of coal gangue micro‐powder should be controlled within 20%. The compressive strength and splitting tensile strength of CGP‐RAC exhibited wave‐like variations with increasing replacement rate of RA. Initially, they decreased, then increased, and finally decreased again. The optimal replacement rate of RA was 60%.b)The orthogonal experimental design resulted in the following mixture proportions for CGP‐RAC: WCR of 0.5, CGP replacement rate of 10%, and RA replacement rate of 60%. The mixture ratio was as follows: cement:sand:water:recycled aggregate:natural aggregate:coal gangue powder = 1:1.59:0.55:1.64:1.09:0.11. For this mixture proportion, the CGP‐RAC exhibited compressive strengths of 9.32, 14.45, and 25.42 MPa at 3, 7, and 28 days, respectively. The split tensile strengths were 0.59, 1.25, and 2.43 MPa at 3, 7, and 28 days, respectively. The utilization of coal gangue and recycled aggregates as solid waste was maximized while ensuring that the CGP‐RAC met the basic strength requirements.2)Microscopic effects of coal gangue on the mechanical properties of CGP‐RAC.a)As the replacement ratio of CGP increased, the internal structure of CGP‐RAC became more porous and looser.b)As the replacement ratio of coal gangue fine powder increased, the calcium‐silicon ratio (Ca/Si) in the cement paste increased. The cement paste with a greater Ca/Si ratio exhibited an unstable structure, resulting in decreasing macroscopic concrete strength.c)Increasing the replacement ratio of CGP significantly hindered the hydration reaction and led to limited development of hydration products.d)Increasing the replacement ratio of CGP enhanced the volcanic ash effect (secondary hydration reaction), resulting in the formation of a small amount of hydration products that contributed to the strength. However, the contribution of the volcanic ash effect to the strength was far from sufficient to compensate for the loss of strength caused by the hindrance of the primary hydration reaction.3)2 diffraction peak decreased. When the WCR increased, the water content increased, leading to the dissolution and erosion of the hydration product Ca(OH)2. As a result, the structure of the cementitious paste became porous and loose. This was manifested macroscopically as a decrease in the strength of the concrete.With increasing WCR, the intensity of the Ca(OH)The purpose of this study was to investigate the comprehensive utilization of coal gangue and construction solid waste. Coal gangue powder was used to partially replace cement, and construction solid waste was used as coarse aggregate to prepare concrete. By conducting single‐factor experiments, orthogonal experiments, and microscopic performance tests, combined with theoretical analysis, the optimal mix proportion of CGP‐RAC, factors affecting the mechanical properties of CGP‐RAC, the strength development behavior of CGP‐RAC, and the mechanism of the influence of CGP‐RAC were obtained. The main conclusions were as follows:Due to the increase in the proportion of CGP and the water‐cement ratio, the strength of concrete decreases. Therefore, it is recommended that CGP‐RAC be used for non‐structural applications such as sidewalks and hollow wall panels. The CGP replacement rate should not exceed 20%, but the water‐cement ratio can be reduced appropriately to enhance the strength of the concrete. Compared to other forms of addition , CGP has a greater impact on the performance of recycled concrete. However, its advantage lies in the ability to reduce the use of Portland cement, while simultaneously using recycled aggregates to replace natural aggregates, further reducing carbon emissions.The authors declare no conflict of interest.


Methionine (Met) is an essential amino acid, and its excessive dietary intake and/or its metabolism disturbance could lead to accumulation/depletion of hepatic Met and some of the key intermediates of these pathways, which would interfere normal liver function and would be associated with liver diseases. Biliary atresia (BA) is a life-threatening disease characterized by inflammatory fibrosclerosing changes of the intrahepatic and extrahepatic biliary systems and is the primary cause of obstructive neonatal cholestasis with a rapid course of liver failure. However, its pathogenesis remains unknown. Previous studies reported elevated Met level in patients with obstructive cholestasis, suggesting a potential link between Met and BA. This paper reviews the Met metabolism in normal conditions and its dysregulation under abnormal conditions, the possible causes of hypermethioninemia, and its connection to BA pathogenesis: Abnormal hepatic level of Met could lead to a perturbation of redox homeostasis and mitochondrial functions of hepatocytes, enhancement of viral infectivity, and dysregulation of innate and adaptative immune cells in response to infection/damage of the liver contributing to the initiation/progression of BA. MAT1A encodes two liver-specific MAT isoenzymes, such as MATI (MAT1A homo-tetramer) and MATIII (MAT1A homo-dimer), that catalyze the transfer of an adenosyl group of adenosine triphosphate (ATP) to Met to produce SAMe and tripolyphosphate  is an essential amino acid (AA), and nearly half of the Met consumed is metabolized in the liver in mammals. Met is first metabolized by methionine adenosyltransferase (MAT) to form S-adenosylmethionine   Figure . Two forSAMe serves mainly as a methyl donor in the cell and transfers its methyl group to substrates such as nucleic acids, proteins, lipids, and secondary metabolites with the formation of S-adenosylhomocysteine , via transmethylation , 4. SAH 2.de novo synthesis of Met occurs via the transfer of a methyl group from methylene-THF first by methylene-THF reductase (MTHFR) and then by Met synthase (MS) to Hcy to form Met to make up the difference  is defined as the persistence of a direct bilirubin concentration of >20% of the total serum bilirubin of newborns for more than 14 days after birth. NC is attributed to a wide range of conditions including obstructive, infectious, metabolic, and genetic causes with variable incidence.Biliary atresia (BA) is a life-threatening disease characterized by inflammatory fibrosclerosing changes of the intrahepatic and extrahepatic biliary systems that shuts down the bile outflow from the liver and is the primary cause of obstructive NC. The incidence of BA is 5–20 per 100,000 newborns, with the highest incidence among Asians, and its pathogenesis remains unknown. If left untreated, within 2 years, this disease would progress to biliary fibrosis and eventual hepatic failure requiring liver transplantation. A procedure called Kasai hepatoportoenterostomy (KPE) that replaces the obliterated extrahepatic bile duct with an intestinal conduit is the first-line treatment to re-establish the bile flow with only 50% success rate . As intrBA is most likely a clinical phenotype resulting from a number of prenatal or perinatal insults to the hepatobiliary tree, and this disease is underpinned by a number of key pathobiological factors (KPFs) either singly or more often in combinations. These KPFs include genetic predisposition and injury triggered by viral infections/toxins and/or niche abnormalities, with inflammatory and immune dysfunction, leading to obliteration and eventual fibrosis and atresia of the bile ducts .4.4.1.Hypermethioninemia (plasma concentration of Met above 45μM)  could beBA patients’ diet primarily consists of breast milk and milk powder. Hence, their mother's high Met diet could increase the Met level in the breast milk, which subsequently causes a passive intake of excessive Met in their babies. In addition, as one of the essential amino acids, Met supplement in milk powder is accepted. However, the concentration of Met in the milk powder varies among brands. Some brands offer milk powder with high Met content.4.2.In rabbit, intravenous administration of Met (121 mg/kg/d) could lead to a blockage of bile flow and jaundice , and the4.3.Met transmethylation begins with the ATP-dependent conversion of Met to SAMe . ATP dep5.Cellular redox homeostasis is an essential and dynamic process that ensures the balance between reducing and oxidizing reactions within cells and is critical for normal cellular functions. Proteins, lipids, and DNA of hepatocytes are among the cellular structures that are primarily affected by the oxidant and antioxidant imbalance within the cell, which participates in the course of inflammatory, metabolic, and proliferative liver diseases. The cellular redox homeostasis is substantiated primarily by GSH, which represents the major redox buffer in the maintenance of cellular redox homeostasis .Met is a substrate for GSH, and intake of dietary Met directly affects the hepatic GSH level. High Met diet causes alteration of hepatic prooxidant/antioxidant status and oxidative stress parameters in rats , 34. HypMat1a in mice resulted in depleted liver SAMe levels and reduced GSH levels, hypermethioninemia, marked changes in the expression of many enzymes of Met metabolism, and increased expression of many acute-phase markers and growth-related genes  caused obstructive jaundice, abnormal liver function, increased lipid peroxide levels, and decreased GSH levels in rats, which indicated that oxidative stress in rats with obstructive jaundice was observed. SAMe application alleviated these injuries in rats that underwent BDL . Deletioed genes . A high ed genes . Reducedr injury . In cirrr injury , which rr injury , 56, 59.r injury .Mat1a-/- mice showed a higher expression of cytochrome P450 family 2 subfamily E member 1 (CYP2E1) and a reduction in mitochondrial membrane potential  in hypoxic cells and participate in the regulation of redox homeostasis. The establishment of the mitochondrial membrane potential is an essential component in the generation of ATP during oxidative phosphorylation. Disruption of the mitochondrial function and mitochondrial membrane potential is associated with the pathophysiology of liver diseases . Hepatocotential –64. The -/- mice , 66. Met6.Oxidative stress exacerbates the pathogenesis of coxsackievirus B3 (CVB3) infection in mice, and the change in virulence is attributed to changes in the viral genome and in the immune functions of the oxidatively stressed mice . DepletiPerinatal cytomegalovirus (CMV) infection has been suggested to be a possible cause or trigger of BA, in that CMV infection initiates damage to the bile duct, which is then followed by autoimmune responses targeting the bile duct. It was found that approximately 10% of BA patients showed serum CMV IgM+, and CMV IgM + BA patients usually have a worse outcome with reduced clearance of jaundice, native liver survival, and increased mortality, representing a distinct clinical and pathological entity of BA with a diminished response to KPE , 75.DNMT1 and DNMT3b eliminates methyltransferase activity and reduces genomic DNA methylation  by greater than 95% , such as DNMT1, DNMT3A, and DNMT3B, write and regulate the DNA methylation patterns, which in turn regulate gene expression. DNMT1 and DNMT3b cooperate to silence genes in human cancer cells, and deletion of than 95% . Interesst cells . The enhst cells , 79. Const cells . Bile acst cells . The intst cells . Therefo7.SAMe increases the suppression competency of regulatory T cells (Treg cells) in a dose-dependent manner via affecting the expression of FOXP3 , promotiKupffer cells (KCs), which are the largest population of resident macrophages in the liver, are the first innate immune cells and protect the liver from infections. Upon activation, cytokine and chemokine production by activated KCs is involved in the pathogenesis of liver damage. A lower SAMe level could attenuate the suppressing activation of the TLR4/MAPK pathway, therefore upregulating the tumor necrosis factor-alpha (TNF-α) expression in KCs . Met cou8.Hepatic stellate cells (HSCs) are liver-specific mesenchymal cells that retain features of resident fibroblasts. They are located in the space of Disse and maintain close interactions with sinusoidal endothelial cells and hepatocytes. In chronic liver damage, HSCs transdifferentiate from a “quiescent” to an “activated” state and are responsible for collagen deposition in the liver tissue, playing a key role in the fibrosis process. Via the activation of TLR4/MAPK signaling in KCs , low SAMIn addition to HSCs, in an injured liver, hepatocytes and bile duct cells can also transform into fibroblasts via the process of epithelial–mesenchymal transition (EMT), and excessive extracellular matrix (ECM) deposition by fibroblasts contributes to liver fibrosis. Under the stress of liver injury, bile duct cells undergo EMT and express fibroblast markers such as fibroblast-specific protein 1 (FSP-1), vimentin, and other mesenchymal markers in a diseased liver with ductular proliferation . Bile duSnail and Slug, repressing the mesenchymal program and EMT of hepatocytes , and the proliferation and differentiation of hepatocyte-derived HPCs are closely associated with ductular reactions and portal fibrosis in liver injury . HPCs isse model . TGF-β1 se model .9.Mat1a enhances the susceptibility to liver injury in mice  and accumulation of toxic metabolic intermediates  in the liver, which in turn affects the functions and the inflammatory responses to damage/infection of the liver .10.In sum, perturbation of Met metabolism may promote the damage process of hepatobiliary injury triggered by viral infections/toxins and/or niche abnormalities, with dysregulated inflammatory and immune responses of the liver, and contribute to the obliteration and eventual fibrosis and atresia of the bile ducts in the initiation/progression of BA.


Scientific progress in the field of knee and hip arthroplasty has enabled the preservation of mobility and quality of life in the case of patients with many primary degenerative and (post-) traumatic joint diseases. This comparative study aims to investigate differences in scientific performance between the leading continents in the field of hip and knee arthroplasty.Using specific search terms all studies published by the scientific leading continents Europe, North America, Asia and Oceania listed in the Web of Science databases were included. All identified publications were analysed and comparative conclusions were drawn regarding the qualitative and quantitative scientific merit of each continent.Europe, followed by North America, Asia, and Oceania, had the highest overall number of publications in the field of arthroplasty. Since 2000, there has been a strong increase in knee arthroplasty publication rate, particular pronounced in Asia. Studies performed and published in North America and those on knee arthroplasty received the highest number of fundings. Publications regarding hip arthroplasty achieved the highest average citation rate. In contradistinction to the others, in North America most funding was provided by private agencies.Although Europe showed the highest total number of publications, authors and institutions, arthroplasty research from North America received greater scientific attention and financial support. Measured by citations, publications on hip arthroplasty attained higher scientific interest and studies on knee arthroplasty received higher economic affection. Scientific progress in the field of knee and hip arthroplasty has enabled the preservation of mobility and quality of life in the case of patients with primary degenerative and (post-) traumatic joint diseases. Due to increasing life expectancy, not only the number of necessary surgical interventions  but alsoComparative analyses evaluate the scientific development in certain fields of research in accordance with scientific standards. This involves recording all publications in a thematic field . SubsequIn addition to differences in the quantity of publications on individual fields of hip and knee arthroplasty, there are also major differences in the publication behaviour of the countries and continents involved –7. Even Currently, the dynamics of publication in hip and knee arthroplasty across the leading continents remain unknown. Comparative analyses can be of assistance, as they aim to structure the scientific contributions to a topic and show in which countries, at which institutions, and in which disciplines the most research has been conducted. Therefore, this study aims at answering the following questions regarding such intercontinental differences: 1. Are there significant differences in the mere publication output in hip and knee arthroplasty? 2. Are there qualitative differences in the publication behaviour ? 3. Are there differences in funding?.In this study, publications on the clinically most relevant subgroups of arthroplasty for hip and knee joints were investigated. All publications from 1945 to 2021 (date of data collection: 28 August 2022) were recorded, analysed, and compared in accordance with the principles of infometrics. Here, regional differences were worked out on a continental level, whereby, for reasons of representativity, only the four continents with the most publications—Europe (EU), North America (NA), Asia (AS) and Oceania (OC)—were included , 12 Fig.Data collection was carried out using the worldwide established, multi-disciplinary search platform for bibliographic databases Web of Science™ (WoS) , 14. To The four continents with the largest publishing power  were selThe publications were subsumed under the term arthroplasty and compared within the subgroups hip and knee arthroplasty between the continents. Here, the time course and the general publication rate were collected by the WoS analysis function and exported into an Excel table  for further statistical evaluation.The authors and institutions were collected by the WoS analysis function and exported to an Excel table for further statistical calculation.The compound annual growth rate (CAGR = https://jcr.clarivate.com). For journals that are no longer published, the IF of the last year of publication was used. If the journal had been renamed in the meantime, the IF of the current journal was used. The geographical assignment was made according to the information in the Journal Citation Report.The funding agencies and publication titles were assigned to the corresponding continents by the WoS analysis function. Due to the large amount of data and the necessity of a manual analysis only, the top 100 agencies and publication titles were identified by means of their number of fundings or publication volume. The agencies were then assigned to either the private sector  or the non-private sector  according to their economic background. The journals were manually ranked regarding their current impact factor (IF) of the Journal Citation Report  and Microsoft Excel table were applied.Significance was assumed at The largest number of publications on the topic of hip and knee arthroplasty derived from European researchers, followed by those from North America, Asia, and Oceania, . Europe and Oceania had more publications in the field of hip arthroplasty than in knee arthroplasty. The opposite was true for North America and Asia.Europe consequently also achieved the highest compound annual growth rate (CAGR) of publications in the period under consideration . Since 2000, there has been a relative decrease in CAGR in Europe and North America. In contrast, in the two other continents, and Asia in particular, there has been an increase in the publication rate. The overall decrease is mainly due to the reduced publication performance in the field of hip arthroplasty  . In the p = .758).Europe showed the highest number of authors contributing to publications on hip and knee arthroplasty in absolute terms .The average number of four authors per publication in the field of arthroplasty was not statistically significant. . Europe and North America each had the highest average number of institutes per single publication . The institutes with the most publications for each subgroup were located in North America .The largest number of agencies active in research funding was found in Europe. Except for Europe, most funding agencies were involved in knee replacement research .More significantly, however, the most funding in absolute and thus also relative terms took place in North America . This also shows that, except for Europe, publications on the subject of knee arthroplasty received more frequent funding.In Asia, funding was almost exclusively provided by non-private agencies (private: 2.2% vs. non-private: 97.8%). In Europe, the largest amount of funding was provided by non-private agencies too (private: 21.1% vs. non-private: 79.0%), while in Oceania, the ratio was balanced (private: 50.0% vs. non-private: 50.0%). In North America, on the other hand, funding was mainly provided by private agencies (private: 66.7% vs. non-private: 33.3%) .Publications from North America received the most citations per publication in both subject areas. Publications on the field of hip arthroplasty achieved on average more citations than publications on knee arthroplasty  .European studies were published in the largest number of different journals . Regarding the 100 most popular journals, Europe, Asia and Oceania showed a preference for publishing in European journals . Publications from Oceania among the 100 most popular journals achieved the highest average impact factor .In this study, we were able to show for the first time that the highest number of publications in the field of hip and knee arthroplasty between 1945 and 2021 derived from Europe, followed by North America, Asia and Oceania. In the last 20 years, Asia has shown a particularly strong increase in publication rate. Most authors and participating institutes were located in Europe. Publications regarding knee arthroplasty received the most funding, whereas publications about hip arthroplasty achieved more citations. Funding in Asia tended to involve almost exclusively non-private agencies. In North America, on the other hand, most funding was provided by private agencies. Researchers from Europe, Asia and Oceania published mainly in European journals, while North American researchers published mostly in journals from North America. Interestingly, publications from Oceania, yielded the highest cumulative IF.In the field of joint replacement, there have been significant innovations and improvements since the first studies on this topic. Evidence of this is provided by the growing number of published research papers. In addition to the increasing quantity of publications observed in this study and others , there hIn this research, an average of four authors per publication was observed, with no significant variation across continents. This high average aligns with findings from other bibliometric studies  and is lRegarding financial support, no statements could be made about the total amount of funding received , as this analysis only refers to the number of funding grants awarded. Publications from North America received the most funding, predominantly by private funding agencies. As a proportional relationship exists between the financial support of an author, the average h-index and the number of publications , 27, thiAs a probable consequence of the above-mentioned correlation between funding and scientific impact , 29 reseDue to the high total number of journals identified in this study, a focussed analysis of the 100 journals with the most publications was carried out. This revealed the trend that North American authors prefer to publish in North American journals. Previous studies have already shown that the rate of paper acceptance in American journals differs significantly depending on the origin of the submitting author . Hence, To ensure equal opportunities for scientific development in the future, the continents and their affiliated institutions must cooperate closely. All researchers must have access to the divergent scientific structures and expertise, which focus on sub-topics unique to each continent, to facilitate collaboration. In doing so, complementary strengths can be cultivated and weaknesses resolved.Like all comparative studies, this study is subject to some limitations. Unspecific search terms may result in off-topic publications, while over-specific combinations can lead to the exclusion of relevant publications. Even though the Web of Science databases are among the most comprehensive databases, not all publications are represented and there are deficits especially with regard to non-English publications . The extAlthough Europe had the highest total number of publications, authors and institutions, publications from North America received greater scientific attention and financial support. As measured by citations, publications on hip arthroplasty attained higher scientific interest and studies on knee arthroplasty received higher economic attention. In recent years, Asia has shown a particularly strong increase in publication rate.


Primary Health Care (PHC) is essential for the health and wellbeing of people living with HIV/AIDS. This study evaluated the effects of one of the largest community-based PHC programs in the world, the Brazilian Family Health Strategy (FHS), on AIDS incidence and mortality.A retrospective cohort study carried out in Brazil, from January 1 2007 to December 31 2015. We conducted a quasi-experimental effect evaluation using a cohort of 3,435,068 ≥13 years low-income individuals who were members of the 100 Million Brazilians Cohort, linked to AIDS diagnoses and deaths registries. We evaluated the effect of FHS on AIDS incidence and mortality and comparing outcomes between residents of municipalities with no FHS coverage with those in municipalities with full FHS coverage. We used multivariable Poisson regressions adjusted for all relevant municipal and individual-level demographic, socioeconomic, and contextual variables, and weighted with inverse probability of treatment weighting (IPTW). We also estimated FHS effect by sex and age, and performed a wide range of sensitivity and triangulation analyses.FHS coverage was associated with lower AIDS incidence  and mortality . FHS effect was similar between men and women, but was larger in people aged ≥35 years old both for incidence  and mortality .AIDS should be an avoidable outcome for most people living with HIV today, and our study shows that FHS coverage could significantly reduce AIDS incidence and mortality among low-income populations in Brazil. Universal access to comprehensive healthcare through community-based PHC programs should be promoted to achieve the Sustainable Development Goals of ending AIDS by 2030. FHS characteristics include: universal access with no payment for services; coordinated and comprehensive preventive and curative care delivered by a multidisciplinary team of a physician, a nurse, and community health workers (CHW); geographic empanelment of about 3,500 people residing near the health center’s location; and monthly visits by a CHW who often lives in the area.16We conducted a quasi-experimental study based on longitudinal data from a cohort of 3.4 million low-income individuals aged 13 and older followed up for 9 years. These individuals represent a subgroup of the ‘100 Million Brazilians Cohort’ based on a set of inclusion criteria discussed below. The study protocol was previously published.This study was approved by the research ethics committee of the Federal University of Bahia, under number 41691315.0.0000.5030 (Report No:3.783.920). The ‘100 Million Brazilians Cohort’ is based on the linkage of administrative data and did not require an additional consent form.17 This cohort was then linked to the National Disease Notification System (SINAN), a registry of notifiable diseases, and the Mortality Information System (SIM), that registers all deaths and their causes classified by International Classification of Diseases (ICD-10) codes (see Appendix p.2).The ‘100 Million Brazilians Cohort’ was previously constructed using the Brazilian national database for social benefits—the Cadastro Único (CadUnico)—which comprises the poorest half of the Brazilian population and is used in determining eligibility for social welfare programs.18 In the first step, the linkage is deterministic. In the second step, entries that were not linked deterministically were then linked probabilistically based on a similarity score between all the pairwise comparisons ; entries with the highest similarity scores were considered to be linked pairs.18These databases were combined using a previously-validated record linkage tool based on the name of the individual and that of their mother, date of birth, sex, and municipality of residence in a two-step procedure.CadUnico records were linked to municipal FHS coverage data by municipality code with deterministic linkage. Annual FHS coverage was calculated according to the Brazilian Ministry of Health definition: the total number of FHS teams deployed in the municipality in that year multiplied by 3,450—representing the average number of individuals served by each FHS team—divided by the population of the municipality. (Appendix p. 2–3)19 c) because these thresholds has been used by similar individual-based PHC evaluation studies,20 and d) because FHS needs a municipal coverage greater than 70% to realize its potential according to previous studies.19 However, lower thresholds have been tested in the sensitivity analyses. Moreover, our study population was selected based on 4) Data availability - excluding individuals without complete information for all covariates; and 5) transmission - excluding individuals infected with HIV through vertical transmission.The complete Cohort contains information on 114,008,306 individuals. We applied several inclusion criteria to develop our analytical sample as follows: 1) dates - excluding those with registration dates in CadUnico or AIDS diagnosis outside of the study period from Jan 1, 2007 to Dec 31, 2015 ; 2) treated population - those individuals resident in municipalities where the FHS had 100% coverage over all the study period; 3) comparison (untreated) population - those individuals residing in municipalities where public health facilities provided care via the FHS for less than 20% of the population over all the study period. We used the threshold of <20% coverage for the comparison group - instead of lower coverage levels – in order to: a) capture a higher number of individuals , b) given the evidence from the literature that low incipient FHS coverage is poorly effective,21 and ii) AIDS mortality rate, i.e., deaths where the underlying cause of death was ICD-10 codes B20 to B24.21 Each measure was divided by person-years at risk and multiplied by 100,000. Follow-up time was calculated from the date of entry into the cohort until diagnosis of AIDS, death from AIDS, death from any cause, or the end of the cohort , whichever came first.Outcomes included: i) AIDS incidence, i.e., new AIDS cases, defined by adapted Centers for Disease Control and Prevention (CDC) criteria, Rio de Janeiro/Caracas criteria, and Death Criterion;We performed descriptive analyses of the study population by FHS coverage for each outcome and for selected independent variables. These included demographic characteristics (sex and age), socioeconomic status , year of entry into the cohort, time of receipt of the Brazilian conditional cash transfer program Bolsa Família , and annual cumulative AIDS incidence for each individual’s municipality of residence from the study cohort, used as proxy of the municipal-level endemic burden of AIDS.20We selected these variables based on a conceptual framework of the main structural determinants of HIV infection, AIDS incidence and mortality, and of the hypothesized effects of PHC on each step of the evolution of the disease . Associations between FHS exposure and AIDS incidence and mortality rates were estimated using multivariable Poisson regression models adjusted for all these relevant individual and municipal-level demographic and socioeconomic confounding variables, including follow-up time as an offset variable, with observations weighted using stabilized truncated inverse probability of treatment weighting (IPTW), a consolidated method to evaluate the impact of PHC, and other interventions, with the 100 Million Brazilians Cohort.We first calculated the IPT weights using multivariable logistic regression models that take into account the probability that each individual lives in a municipality with 100% FHS coverage. Independent variables of the regression included all the baseline demographic and socioeconomic characteristics cited above. Considering Pt as the marginal probability of treatment in the population and PSmul as the propensity score obtained from the multivariable logistic regression adjusted for all independent variables, we calculated the IPTW using the formula (1 − Pt) / (1 − PSmul) for non-treated individuals and used the formula Pt / PSmul for treated individuals. As is standard practice, we dropped extreme weights that were below the first percentile or above the 99th percentile. We then adjusted the IPT weighted multivariable Poisson regression using the same demographic and socioeconomic covariates used to calculate the first stage weights along with: household economic conditions , and municipal conditions . Multivariable logistic regression models for the prediction of the propensity scores, and the odds ratios (OR) for each covariate are presented in Appendix, p. 6.For each model, multicollinearity was assessed using Variance Inflation Factors (VIF). Subgroup analyses included models by sex and age , and additional stratifies were used as complementary analysis .22 - to check if the results are different from the main analysis. Sixth, mortality from external causes (ICD-10 codes V01-Y98) was included as a negative control, since the FHS was not expected to influence them. Seventh, marital status was included in the IPTW regressions as adjusting variable -even with its high number of missing values- to verify if it was a relevant confounder. Eighth, to assess the differences between treated and untreated individuals in relation to sexual preferences and behavior, we estimated the percentage of MSM – variable only available in the records of AIDS cases – in the two groups. We also did complementary tests dividing the analysis in 2 periods, i.e., up to 2010 and after 2011, to check possible differences related to changes in treatments and protocols over the period. We chose for 2011 because in this year PHC started carrying out rapid HIV tests12 (Appendix p. 17–24). We also used the records of HIV cases from 2014, year in which they started to be compulsorily notified, to assess if FHS exposure was also associated with potential HIV reductions (even if available study period was of only 2 years). Finally, we performed a triangulation test23, using Cox regression  to estimate the FHS effects on AIDS incidence, and compared these findings with our main results (Appendix p. 24). All analyses were performed using STATA version 15.0.Sensitivity analyses (Appendix p. 8–16) included first, investigating the effect of defining the comparison group as those living in municipalities with either 0% or with 10% FHS coverage over the study period, to test if the threshold used for the untreated individuals (20%) affected our estimates. Second, we performed a negative binomial regression model comparing results to those found using the IPTW Poisson regression model, to evaluate the robustness of results to other regression specifications. Third, we performed the same multivariable Poisson regressions without IPTW to assess the potential of IPTW for obtaining unbiased FHS estimates. Fourth, we conducted IPTW regressions without the municipal covariates to test the influence of municipal context and resources on our results. This analysis helped to identify whether FHS coverage was truly driving the observed association or whether it was simply collinear with other municipal characteristics. Fifth, we fitted the IPTW Poisson regressions only with a subset of municipalities with high quality of vital information – according to consolidated criteriaThe funding source had no role in study design, data collection, data analysis, data interpretation or the writing of the report.We studied 3,435,068 individuals— 605,890 lived in municipalities with zero (or very low) FHS coverage and 2,829,178 lived in municipalities with full FHS coverage during the entire study period . As presThere were 2,721 new cases of AIDS during the study period, the mean AIDS incidence rate over the period was higher  among individuals living in municipalities with no FHS coverage, than among individuals living in municipalities with full FHS coverage . During follow-up 819 AIDS deaths occurred, in the untreated group the AIDS mortality rate was higher  than among the treated group  .FHS coverage was associated with a reduction in AIDS incidence , and – with a greater magnitude – with a reduction in AIDS-related mortality  . DemograIn the subgroup analyses , the FHSAll sensitivity analyses confirmed the robustness of the findings, and all triangulation analyses showed a high degree of confidence in the impact estimation .To the best of our knowledge, this is the first study that evaluates the effect of a nationwide, community-based PHC strategy on AIDS incidence and mortality in a low- and middle-income country. Using a cohort of 3,435,068 individuals and 2,721 new AIDS cases with a robust quasi experiment design, we found a strong effect of FHS coverage on the reduction of both AIDS incidence and mortality. Moreover, FHS showed a stronger impact among individuals ≥35 years old.20 Another recent quasi-experiment using a similar cohort and design demonstrated that the FHS was also negatively associated with tuberculosis morbidity and mortality.20These findings add to evidence that the FHS is a robust community-based PHC model associated with improved population health outcomes.3 The rationale is that PHC is highly accessible, especially for those with greater social vulnerability,2 who are heavily affected by AIDS incidence and mortality.24 PHC can foster greater trust with patients and by serving as the entry point to the health system can better facilitate access to HIV diagnosis through rapid testing, linkage to treatment services and enable early initiation of ART, all of which are directly related to the reduction of AIDS incidence.26 HIV prevention actions carried out in PHC, such as sex education, family planning with condom distribution, follow-up and counseling of pregnant and postpartum women living with HIV/AIDS, distribution of syringes and needles to reduce harm among injecting drug users and offering PrEP and PEP, can play an essential role in reducing the incidence of HIV and its progression to AIDS.27 It is important to point out that PrEP and PEP were introduced in Brazil in 2018, therefore its effects on the treatment were not evaluated in the present study.28Strengthening and expanding PHC are recommended strategies to end AIDS by 2030.2 as well as dealing with other health problems unrelated to HIV, but that come with the increased life expectancy of PLWH. Centralized services that focus only on HIV/AIDS services may increase stigma among people living with the disease12 and are limited in their ability to provide comprehensive and integrated care. PHC services, like the FHS, establish long-term ties with users and serve as their medical home, which can increase adherence to AIDS treatment and reduce mortality.29 In the FHS, regular home visits, carried out by CHWs, are an important tool for monitoring ART adherence, helping individuals to gain access to other health and social services, identifying other behavioral or environmental risk factors, and delivering tailored education interventions.29 A previous study carried out in Brazil showed that the introduction of rapid testing combined with ART–regardless of the patient’s immunosuppression–reduced AIDS incidence and mortality by 60% and 73%, respectively.28PHC should be the ideal place for managing AIDS, since like other chronic conditions it requires maintaining long-term treatments30 In Brazil, AIDS mortality is higher among the elderly,31 which makes the results of this study even more relevant. However, it is noteworthy that we also found a relevant effect of the FHS in reducing AIDS incidence among people aged 13–34 years. Due to their higher vulnerability to HIV/AIDS, younger populations are a national priority for preventive actions in Brazil.27 Our findings are particularly relevant, given that there are studies showing that youths linked to care initiate ART and achieve viral suppression at lower rates than older adults, due to their lower levels of interest in communicable and noncommunicable disease care  and competing priorities, such as those related to social, educational and economic advancement, that outweighed younger adults’ health concerns, resulting in lower care engagement.32 On the other hand, when adolescents and youth receive counseling regarding ART adherence, as well as support and referral for psychosocial problems, they had better retention in ART.33The effects of PHC on AIDS incidence and mortality were stronger among older people, a result that was also expected since older people in Brazil tend to have greater access to PHC services.21 Second, we estimated the effect of FHS on AIDS outcomes by adjusting models for multiple socioeconomic variables, nonetheless some unobserved confounders  may not have been accounted for in propensity score-based models. For this reason, we incorporated a wide range of individual-level and municipal-level factors as covariates in regression analyses, and we included the endemic levels of AIDS in the municipality as an adjusting variable that represent non-observed factors associated with the local burden of AIDS before the implementation of the intervention. Results from sensitivity analyses showed that the inclusion of other variables related to inequalities, infrastructure, and healthcare assistance at the municipal level do not affect the FHS effect estimates (Appendix p. 8). Moreover, variables related to sexual behavior, such as marital status and self-identification as Men who have Sex with Men (MSM), which were not included in the main models because of the elevated number of missing values, were nevertheless equally distributed among treated and untreated groups and indicated a predominant heterosexual HIV transmission  in our cohort of low-income individuals, the percentage of MSM among the linked AIDS cases was particularly low compared to the national proportion of 42.9% in 2021.21 Furthermore, when incorporated in the regression models they did not change the direction or magnitude of the results (Appendix p. 11–14). Third, our outcome variables were AIDS-related incidence and mortality (and not HIV incidence) because mandatory notification for HIV only started in 2014 in Brazil.27 However, complementary analyses showed a significant negative association between FHS coverage and HIV incidence in 2014–15. Forth, to avoid sparse data, we defined “untreated” individuals as those living in municipalities with <20% FHS coverage. However, sensitivity analyses showed no relevant changes to our results when the untreated groups were defined as those living in municipalities with 0% or <10% FHS coverage (Appendix p. 8). Finally, while the FHS has been found to be a robust model of PHC, not all FHS providers deliver care that is appropriate for some populations at high risk of HIV infection, such as LGBTQ+ individuals. Enhancing the ability of PHC providers to make care more welcoming, appropriate and effective for key populations at risk for HIV infection remains a challenge for the FHS and for PHC in many country contexts.This study has limitations. First, the positive effects of the FHS found in this study are not representative nationally, because all individuals included in the study were derived from the 100 Million Brazilians Cohort, which contains individuals of lower socioeconomic status. Even so, the AIDS incidence rate found in the total population of our study  was very similar to that of the country in 2021 .The main strengths of our study are first its unprecedentedly large cohort of individuals, AIDS cases, and AIDS deaths, and second the robust quasi-experiment design accompanied by a wide range of sensitivity analyses - which confirmed the robustness of the findings - and triangulation tests - that indicate a high degree of confidence in the results.In conclusion, our findings show that a universal model of community-based PHC could significantly reduce incidence and mortality from AIDS in LMIC, and even decrease AIDS-related inequities among vulnerable populations. The results of this study justify the expansion and strengthening of effective PHC strategies globally to reach the Sustainable Development Goal of ending AIDS by 2030.