Due to the accumulated fatigue damage in steel–concrete continuous composite box beams, a plastic hinge forms in the negative moment zone, leading to significant internal force redistribution. To investigate the internal force redistribution in the negative moment zone and confirm structural safety under fatigue loading, experimental tests were conducted on nine steel–concrete continuous composite box beams: eight of them under fatigue testing, one of them under static testing. The test results showed that the moment modification coefficient at the middle support increases during the fatigue process. When approaching fatigue failure, an increase of 1.0% in the reinforcement ratio or 0.27% in the stirrup ratio results in a reduction of 13% in the moment modification coefficient. Furthermore, a quadratic function model was proposed to calculate the moment modification coefficient of a steel–concrete continuous composite box beam during the fatigue process, which exhibited good agreement with the experimental results. Finally, we verified the applicability of the plastic hinge rotation theory for steel–concrete continuous composite box beams under fatigue loading. Compared with ordinary reinforced concrete beams, steel–concrete composite beams exhibit the advantages of light weight, small cross-section, good ductility, and high seismic resistance ,2,3. SinIn recent research, many scholars have conducted fatigue tests and investigated the fatigue failure mechanisms in steel–concrete composite beams. The results indicate that under fatigue loading, steel–concrete continuous composite beams experience stud failure and concrete cracking, leading to degradation decrease in stiffness. Lin et al.  conducteIn addition, in continuous composite beams, the negative moment at the middle support leads to an unfavorable situation where the concrete slab is under tension and the steel beam is under compression . When thHowever, few studies have been carried out on the internal force redistribution of steel–concrete continuous composite beams in the negative moment zone under fatigue tests. Previous studies ,27 have To investigate the internal force redistribution condition of steel–concrete continuous composite box beams during the fatigue loading process, eight specimens (FSCB-1 to FSCB-8) with different parameters—including load amplitude, reinforcement ratio, stirrup ratio, and shear connection degree—were subjected to fatigue load testing. One specimen (FSCB-0) was subjected to static load testing. Based on the experimental results, a moment modification coefficient–fatigue process model was proposed, showing good agreement with all specimens. Furthermore, by comparing the calculated results with the experimental results, we verified the applicability of plastic hinge rotation theory for steel–concrete continuous composite box beams under fatigue loading.2 gas-shielded welding. The fillet weld joints had a leg size of 6 mm. Thirteen cross partitions of 8 mm thickness were installed in the steel box, and a 50 mm × 6 mm longitudinal stiffening rib was installed at the bottom of the steel box to prevent shear failure before bending failure occurred. The steel box had a width of 258 mm and a height of 176 mm, with the upper flange width being 60 mm. The concrete slab was cast with C30 concrete, with a width of 650 mm and a height of 70 mm. The 6 mm diameter HPB300 rebars were used as the stirrups, and the 14 mm diameter HRB400 rebars were used as the reinforcement steel. The concrete slab and steel box were connected by 13 mm diameter and 50 mm high studs. The size of each component and the layout of the reinforcements and studs are shown in Based on the experiment of Zhang et al. , nine 1:The arrangement of the measurement points for the tests is shown in To verify whether the strain along the height of the section during fatigue loading satisfied the plane section assumption, six strain gauges were arranged at each mid-span position along the height of the specimens. The strain gauges were numbered from 1 to 6, from the top of the concrete slab to the bottom of the steel box. Two strain gauges were arranged along the concrete slab’s thickness, which were 10 mm away from the top and bottom of the slab. Three strain gauges were arranged on the steel box web along the height direction, and two strain gauges were arranged on the bottom of the steel box’s lower flange—one near the center and one near the edge.5, 1 × 106, 1.5 × 106, 2 × 106, 2.5 × 106, and 3 × 106, in order to conduct the intermediate static tests. The fatigue life of each specimen was determined based on the longest fatigue life of the steel material. Specifically, when the first crack could be observed on the steel box, the number of cycles at this point was considered to represent the fatigue life of the steel–concrete continuous composite box beam [The test was conducted in the National Engineering Laboratory of High-speed Railway Construction Technology at Central South University. A two-point symmetric loading method was used, and the load was uniformly transferred to the loading point by a PMS-500 hydraulic jack through the spread beam, as shown in box beam . The fatSpecimen FSCB-0 was subjected to a static load, and observable damage occurred as the load increased. At 85 kN, the first crack appeared in the top surface of the concrete slab at the middle support. At 382 kN, with a loud sound, the slippage between the steel box and the concrete slab began to increase, and some studs near the middle support were sheared off. Finally, at 820 kN, the concrete near the mid-span was crushed; however, no cracks were observed on the steel box.cN) increased. Taking FSCB-1 as an example, when cN = 0, a few cracks appeared on the top surface of the concrete slab at the middle support. When cN = 1 × 104, the width of initial cracks on the concrete slab at the middle support started to expand. When cN = 1 × 106, the cracks in the concrete slab at the middle support gradually expanded from the edges to the middle until they penetrated the top surface of the concrete slab. When cN = 1.3 × 106, obvious separation could be observed between the steel box and the concrete slab, and fatigue shear failure occurred at the bottom section of some studs near the middle support. When cN = 1.5 × 106, a few cracks appeared on the bottom surface of the concrete slab at the mid-span and gradually developed toward the top surface. When cN = 1.92 × 106, the first fatigue crack on the upper flange of the steel box at the middle support could be observed with the naked eye. Fatigue loading continued until cN = 2.01 × 106, at which point the width of the crack on the steel box had expanded to 5 mm. The fatigue test was then terminated, and the final static test was conducted. In the final static test, the crack on the steel box vertically penetrated the whole steel box section from the upper flange to the bottom of the web, while the lower flange of the steel box remained intact. The length of the concrete slab’s crack distribution area reached 1.15 m. The development of concrete cracks is shown in For specimens FSCB-1 to FSCB-8, which were subjected to fatigue loads, the same damage characteristics appeared sequentially as the fatigue load cycle (defined as iN). The three-stage damage characteristics of the continuous composite box beam are shown in According to the fatigue test phenomena, the fatigue damage of the continuous composite box beam can be divided into three stages: (1) Stage I: in the early stage of fatigue loading, concrete cracks appeared at the middle support and expanded with increasing fatigue load cycles. (2) Stage II: as the number of fatigue load cycles increased, some studs near the middle support were sheared off, and obvious separation and slippage between the concrete slab and the steel box could be observed on both sides. (3) Stage III: the continuous composite box beam failed to bear the load as a single unit, and cracks appeared on the upper flange of the steel box and expanded downward to the middle support with increasing fatigue load cycles. After the upper flange of the steel box fractured, the continuous composite box beam could be considered to have undergone fatigue failure, and the number of fatigue load cycles at this time could be taken as the fatigue life of the beam :f is the deflection of the mid-span, M is the moment of the mid-span, B is the stiffness, α is the coefficient that takes account of the support and the load, nB is the stiffness when cN = n, and B0 is the stiffness when cN = 0.g et al. , the stic/NiN indicates the process of fatigue failure). The results demonstrated that the residual stiffness coefficient of the continuous composite box beams decreased with increasing fatigue load cycles, following an “S-shaped” pattern with three stages: In the first stage, the residual stiffness coefficient decreased by about 20% to 30%, and the rate of decrease was stable; this stage accounted for about 20% of the fatigue life. In the second stage, the residual stiffness coefficient decreased slowly; this stage accounted for about 50% of the fatigue life. In the third stage, when approaching fatigue failure, the residual stiffness coefficient decreased rapidly and ultimately reached a value between 0.165 and 0.387. Among the eight continuous composite box beams tested, FSCB-4 and FSCB-7 exhibited the highest residual stiffness coefficients when approaching the end of their fatigue life, with values of 0.387 and 0.382, respectively. Overall, the residual stiffness coefficient curves were consistent with the three-stage damage characteristic, and the results indicated that continuous composite box beams with higher reinforcement or stirrup ratios experience a slower decrease in stiffness when approaching fatigue failure.The residual stiffness coefficient degeneration curves of FSCB-1 to FSCB-8 are shown in Previous studies have shown that the formation of the plastic hinge will cause obvious internal force redistribution at the middle support of continuous composite box beams ,25,26,27expβ is the experimental moment modification coefficient at the middle support, M is the elastic calculated moment (M = 3 FL/32), M′ is the measured moment, F is the applied load, mF is the measured force at the middle support, and l is the length of one span.The internal force redistribution at the middle support can be expressed by Equation (3) :βexp = :a = 0.4 and b = 0.6 were obtained. The fitting curves are shown in 2) of all models are above 0.86, as shown in By substituting the relevant data in this study into Equation (4), values of The difference in the ultimate moment modification coefficient from FSCB-1 to FSCB-8 is shown in θ is the angle displacement caused by the modified moment ΔM, l is the length of one span, m is the ratio of the length of the negative moment zone to the length of one span, n is the ratio of the stiffness at the positive moment to the stiffness at the negative moment, B is the stiffness at the positive moment, uθ is the ultimate plastic angle displacement of the plastic hinge at the middle support, uφ is the ultimate curvature when the bottom of the steel box yields, yφ is the curvature when the reinforcement yields, pl is the length of the negative moment zone, uM is the ultimate bending moment at the negative moment, and u,calβ is the calculated moment modification coefficient.Based on the plastic hinge rotation theory, Sun  obtainedu,calβ and u,expβ of each specimen are shown in u,calβ values of the specimens under static loads are in good agreement with the u,expβ values. However, for the specimens under fatigue loads, the calculated values are in good agreement with the experimental values for FSCB-1, FSCB-4, FSCB-5, and FSCB-8, while there is some deviation for FSCB-2, FSCB-3, FSCB-6, and FSCB-7. This discrepancy is due to the fact that the stiffness calculation takes into account the influence of the reinforcement ratio and the shear connection degree, but neglects the effects of the fatigue amplitude and stirrup ratio on the stiffness of the negative bending moment zone. In addition, most u,calβ values under fatigue failure are lower than the u,expβ values for the specimens under fatigue loads. This is because after a period of fatigue loading, the neutral axis moved downward, so the uM of specimens was overestimated and the uθ was underestimated. Hence, it is necessary to take the load amplitude and stirrup ratio into consideration in the calculation of fatigue moment modification.According to Equations (6)–(9), the moment modification coefficients for FSCB-0 to FSCB-8 and the specimens in references ,26 were u,calβ of FSCB-1 to FSCB-8 was within 20% of the u,expβ. This indicates that Equations (6)–(9) can be applied to steel–concrete composite beams under fatigue loads, but it is necessary to consider the effects of the load amplitude and stirrup ratio on the stiffness and length of the negative moment zone to improve the calculation accuracy.Overall, the Under fatigue loading, the failure of steel–concrete composite continuous box beams exhibits a three-stage characteristic, and the fatigue failure mode is the fracture of the upper flange of the steel beam in the negative moment zone.The degradation of the residual stiffness shows an “S-shape pattern”. In the fatigue loading process, the stiffness of the concrete–steel composite box beams decreased more slowly with higher reinforcement ratio or stirrup ratio. When approaching fatigue failure, the residual stiffness of FSCB-1 to FSCB-8 reached 17% to 39%.Compared with the load amplitude or shear connection, the reinforcement ratio and stirrup ratio are significant factors that control the moment modification coefficient under fatigue load. When approaching fatigue failure, an increase of 1.0% in the reinforcement ratio or 0.27% in the stirrup ratio results in a reduction of 13% in the moment modification coefficient.The moment modification coefficient increases with an increase in the number of fatigue load cycles, and the curves show a quadratic function pattern. Based on the test results, this paper proposes a model to calculate the moment modification coefficient for steel–concrete continuous composite box beams during the fatigue process. The model showed good agreement with the test results for all specimens.The findings of this paper verify that the plastic hinge rotation theory is applicable for steel–concrete continuous composite box beams under fatigue load, by comparing the calculated results with the experimental results. However, it is necessary to consider the effects of the load amplitude and stirrup ratio on the stiffness and length of the negative moment zone to improve the calculation accuracy.To investigate the internal force redistribution in the negative moment zone of steel–concrete continuous composite box beams under fatigue loading, static and fatigue tests were performed on nine specimens. The specific research conclusions are as follows:


Inappropriate antibiotic prescribing by dentists is as high as 80% and in the U.S., dentists rank third for writing the most antibiotic prescriptions. At NewYork-Presbyterian Brooklyn Methodist (NYP-BMH), the Antimicrobial Stewardship Program (ASP) and Division of Dental Medicine collaborated to create a clinical practice guideline regarding antibiotic use in dentistry that was implemented in May 2021 and is reinforced with annual education to dental prescribers. The purpose of this study is to compare outpatient antibiotic prescribing trends pre- and post-guideline implementation.Patients presenting to NYP-BMH dental clinic for an emergent indication and prescribed an antibiotic from January-April of 2019-2021 (pre) and January-April of 2022 (post) were included. The primary outcome was appropriateness of antibiotic therapy. Secondary outcomes included a comparison of antibiotic selection, dosing and duration of therapy. A subgroup analysis of patients with reported penicillin allergies was conducted to compare alternative agents prescribed.A total of 119 patients in the pre and 100 patients in the post-guideline period were included. The primary outcome of appropriate antibiotic prescriptions significantly improved after guideline implementation . The majority of antibiotic indications were treatment-related and the most common dental diagnosis was caries. The most common antibiotic prescribed in the study was amoxicillin. Compared to pre-guideline, there was significant decreased utilization of penicillin VK  and amoxicillin-clavulanate post-guideline . A wide variety of dosing regimens were utilized with more guideline-concordant regimens utilized post-guideline . On average, shorter durations of therapy were prescribed post-guideline . Penicillin-allergic patients were prescribed less clindamycin after guideline implementation.ASP initiatives and collaboration with outpatient dental clinics can improve appropriate antibiotic prescribing. As ASPs look to expand into ambulatory care settings, dental clinics should be prioritized.All Authors: No reported disclosures


Metformin (MET) has the potential to activate p‐AMPK and block mTORC1‐induced proliferation of tubular cells in PKD kidneys. The aim of this study was to determine the effects of MET on cyst growth, kidney function, AMPK and mTOR signaling, and lactate levels in male PCK rats, a Pkhd1 gene mutation model of human autosomal recessive polycystic kidney disease (ARPKD). MET 300 mg/kg/day IP from days 28 to 84 of age resulted in a mean serum metformin level that was 10 times the upper limit of therapeutic, no effect on cyst indices, nephrotoxicity, and increased serum lactate. MET 150 mg/kg resulted in a therapeutic serum metformin level but had no effect on kidney weight, cyst indices, kidney function, or mTOR and autophagy proteins. In summary, a standard dose of MET was ineffective in reducing PKD, did not activate p‐AMPK or suppress mTOR and the higher dose resulted in increased lactate levels and nephrotoxicity. In conclusion, the study dampens enthusiasm for human studies of MET in PKD. Doubling the metformin dose resulted in a 10‐fold increase in mean blood levels and toxicity suggesting that the dosage range between therapeutic and toxic is narrow.  Metformin has not previously been tested in a rat model of polycystic kidney disease.Therapeutic blood levels of metformin did not slow PKD. Doubling the metformin dose resulted in a 10‐fold increase in mean blood levels and toxicity suggesting that the dosage range between therapeutic and toxic is narrow.Metformin did not activate p‐AMPK or inhibit proliferation in the PKD kidney.The study raised concerns about using metformin in patients with PKD.1Autosomal‐dominant polycystic kidney disease (ADPKD) is the commonest inherited kidney disease and is characterized by the slow and persistent growth of renal tubular epithelial cell‐lined cysts. Over time, these fluid‐filled cysts change the gross anatomy of the kidney, normal parenchymal structures are compressed, and kidney function is impaired. Proliferation and fluid secretion of the cells lining the cyst are the major mechanisms of cyst growth  or vehicle  by intraperitoneal (IP) injection from 28 to 84 days of age. MET was administered intraperitoneally after dissolving with sterile saline. MET was obtained from Sigma‐Aldrich. At the end of the treatment period, rats were sacrificed under isoflurane anesthesia. Blood samples were obtained with a cardiac puncture and then the kidneys, heart, and liver were removed and weighed. Slices of organs were preserved in formaldehyde and embedded in paraffin for histological examination.2.3max (sex averaged) of 41.1 μg h/mL and 10.3 μg/mL, respectively, which corresponds to ∼2× and 8× the human AUC and Cmax following a 2000‐mg total daily dose  of MET is 200 mg/kg/day orally in Sprague Dawley rats  using a urea assay kit (BioAssay Systems). Serum creatinine levels were measured by HPLC‐tandem mass spectrometry.2.5S473 # 9271, p‐AktS308 # 9275, AMPK # 2532, p‐AMPKT172 # 2535, p‐ACC S79 # 3661, ACC #3662, GAPDH # 2118, LC3‐II # 2775, mTOR # 2983, p62 # 5114, S6 # 2217, pS6S235/236 # 2211, and anti‐rabbit IgG HRP # 7074. The specificity of each of these antibodies used has been validated by the vendor . Blots were developed with chemiluminescence, and densitometric analysis was performed using ImageJ.Proteins were isolated in tissues using RIPA, whole protease, and phoSTOP phosphatase inhibitor cocktails (Sigma) as we have previously described  to the first and last well of the SDS‐polyacrylamide gel used for the immunoblot. This ladder was visible to the naked eye after being transferred to a nitrocellulose membrane. The film was placed in a dark cassette firmly aligned to one side of the cassette to expose the film to fluorescing protein bands. After the desired exposure time, the film was developed and the film was placed back into the cassette in the original alignment. The visible molecular weight ladders framing the nitrocellulose membrane were then traced onto the film with a black marking pen Figure .2.62 were determined separately in the cortex and medulla in each rat on three transverse sections  in both left and right kidney and two sections of the liver. Tissue tears that could be identified at ×40 magnification were excluded from the analysis.Hematoxylin–eosin‐stained kidneys were scanned using an Aperio ImageScope (Leica Biosystems) and snapshots were analyzed using a custom NIS‐Elements macro  for 25 min at 100°C to unmask the antigen as previously described  by an operator blinded to the treatment modality. The pathology slide viewing software in Aperio ImageScope enables extensive image analysis including length measurements and counting of positive staining cells. Tubules less than 50 μm in diameter were defined as noncystic tubules. For the noncystic areas, 15–20 fields of view at X40 magnification per sample were randomly selected for noncystic quantification. Positive staining was counted in cysts with a diameter of ~75–200 μm to avoid potential changes in the tubular epithelium covering massive cysts, as well as sensitivity and selection artifacts between noncystic and dilated, possibly precystic tubules. For histological analysis, 50–75 medullary cysts per tissue section were randomly selected for histological analysis.2.9Samples (10 μL) were analyzed by liquid chromatography with tandem mass spectrometry (LC/MS–MS). Metformin and d6‐metformin were purchased from Toronto Research Chemicals. Control serum was purchased from BioIVT. An Applied Biosystems Sciex 4000 (Applied Biosystems) equipped with a Shimadzu HPLC  and a Shimadzu auto‐sampler (Nexera SIL‐30ACMP UHPLC 6‐MTP cooled auto‐sampler) were used. Liquid chromatography employed an Agilent Technologies, Zorbax extended‐C18 250 × 4.6 mm, 5‐micron column equipped with a C18 column guard at 40°C with a flow rate of 0.4 mL/min.4OAc), 0.1% formic acid in H2O and B: (1:1) acetonitrile:ethanol. The chromatography method used was 5% B for 0.5 min, then ramped to 95% B at 2.5 min, and held for 4.5 min. Next, it was ramped back to 5% B at 8.0 min and held for 2.0 min for a 10.0 min total run time. Metformin and d6‐metformin  were monitored via electro‐spray ionization positive ion mode (ESI+) using the following conditions: (i) an ion‐spray voltage of 5500 V; (ii) temperature, 450°C; (iii) curtain gas  and Collisionally Activated Dissociation  gas were nitrogen; (iv) Ion Source gas one (GS1) and two (GS2) were set at 35 and 50, respectively; (v) entrance potential was set at 10 V; (vi) quadruple one (Q1) and (Q3) were set on low resolution; (vii) dwell time was set at 200 ms; and (viii) de‐clustering potential (DP), collision energy (CE), and collision cell exit potential (CXP) are voltages (V). Samples (10 mL) were analyzed by LC/MS–MS. Settings: Metformin (tR = 6.6 min) 130.04 → m/z 70.89 (quantitative MRM), DP = 46, CE = 29, CXP = 6; 130.04 → 59.88 m/z (confirmatory MRM), DP = 46, CE = 19, CXP = 4; d6‐Metformin (tR = 6.6 min) 136.08 → 76.92 m/z , DP = 31, CE = 31, CXP = 8. A standard curve  using control serum was prepared in triplicate, frozen (−80°C) subjected to one freeze–thaw cycle. For every 100 mL of serum, 200 mL of extraction solution (1:1 methanol:acetonitrile‐containing d6‐metformin) was added, vortex mixed (5 s), and then centrifuged at 11,000 rpm for 5.0 min. The supernatants were transferred to a 96‐well plate and analyzed by LC/MS–MS.The mobile phase consisted of A: 10 mM  vs. 0.31 ± 0.02 in PCK rats (N = 6) . MET had no effect on heart weight  was 0.31 ± 0.02 in +/+ rats  plays a key role in the regulation of energy homeostasis  is a ubiquitin‐binding protein that binds the autophagosomal membrane protein LC3 and brings p62‐containing protein aggregates to the autophagosome (12). Lysosomal degradation of autophagosomes leads to a decrease in p62 during active autophagy while autophagy inhibitors increase p62. MET has been shown to activate autophagy in some cases by decreasing mTORC1 , an inhibitor of mTOR or directly phosphorylating mTOR in a rapamycin‐sensitive complex containing raptor . In rats treated with MET 150 mg/kg IP, the mean serum MET level (μmol/L) was 32 ± 11 (N = 6). Thus, doubling the dose of MET resulted in a 10‐fold increase in mean serum MET levels and toxicity suggesting that the dosage range between therapeutic and toxic is narrow.Peak MET levels were obtained at the end of the study, 2 h after the last dose of MET. In rats treated with MET 300 mg/kg IP, the mean serum MET level (μmol/L) was 359 ± 137  resulted in MET blood levels more than 10 times the therapeutic level, weight loss, and nephrotoxicity and had no effect on PKD in rats. Although MET 150–300 mg/kg orally are the standard doses used in rats, toxic effects on the kidney are seldom measured. The present study suggested that 300 mg/kg IP may be too high a dose to use in rats and that renal toxicity may mask a therapeutic effect on cyst growth and kidney function in PKD. Thus, we used a lower dose of 150 mg/kg which is below the NOAEL of 200 mg/kg/day orally in Sprague Dawley rats , plasma membrane monoamine transporter (PMAT), and multidrug toxin extrusions (MATEs) transporters  levels of MET are required to have antiproliferative effects  resulted in toxic blood levels, weight loss, increased lactate levels, and nephrotoxicity in male PCK rats. A lower dose of MET 150 mg/kg resulted in therapeutic blood levels, no weight loss, did not reduce kidney weight or cyst indices, and had no effect on kidney function or serum lactate levels in male PCK rats. Both doses had no effect on p‐AMPK, p‐ACC, mTOR, and autophagy proteins. Both doses did not decrease proliferation in the cystic kidney. The present study highlights a number of concerns on the use of MET in PKD: (1) Although the hypothesis in most studies is that MET activates AMPK, suppresses mTORC1, and reduces proliferation, few mouse studies actually show activated p‐AMPK, suppressed mTOR, and reduced proliferation. (2) The dosage of MET required to activate p‐AMPK and suppress mTOR or activate autophagy in human PKD kidneys may be too high which can result in increased lactate levels and nephrotoxicity. (3) Blood and tissue levels of MET may be too low to have an effect on proliferation. (4) MET had no effect on early liver cyst growth. (5) The MET dosage range between therapeutic and toxic may be narrow.C.L.E. was funded by a Merit Award grant from the Department of Veteran's Affairs (grant nos. I01BX003803‐05) and a grant from the Zell Family Foundation. O.A.O. was funded by an International Postdoctoral Fellowship Grant from the Scientific and Technological Research Council of Turkey. A.S.L. was funded by the National Institutes of Health (grant nos. 5T32DK007135‐46).Figure S1.Click here for additional data file.


Heroin is an opioid agonist commonly abused for its rewarding effects. Since its synthesis at the end of the nineteenth century, its popularity as a recreational drug has ebbed and flowed. In the last three decades, heroin use has increased again, and yet the pharmacology of heroin is still poorly understood. After entering the body, heroin is rapidly deacetylated to 6-monoacetylmorphine (6-MAM), which is then deacetylated to morphine. Thus, drug addiction literature has long settled on the notion that heroin is little more than a pro-drug. In contrast to these former views, we will argue for a more complex interplay among heroin and its active metabolites: 6-MAM, morphine, and morphine-6-glucuronide (M6G). In particular, we propose that the complex temporal pattern of heroin effects results from the sequential, only partially overlapping, actions not only of 6-MAM, morphine, and M6G, but also of heroin per se, which, therefore, should not be seen as a mere brain-delivery system for its active metabolites. We will first review the literature concerning the pharmacokinetics and pharmacodynamics of heroin and its metabolites, then examine their neural and behavioral effects, and finally discuss the possible implications of these data for a better understanding of opioid reward and heroin addiction. By so doing we hope to highlight research topics to be investigated by future clinical and pre-clinical studies. Papaver somniferum). The opium poppy was first domesticated circa 6000 B.C.E. in Europe, and its cultivation spread eastwards over the following millennia )δ (delta), and κ (kappa) opioid peptide receptors . Additional types have been proposed, like the nociceptin/orphanin FQ opioid peptide receptor, but their physiological/pharmacological status is still debated , as a function of the ligand (‘biased agonism’) raclopride positron emission tomography (PET) imaging in people with heroin use disorder, that heroin’s high is not associated with changes in dopamine receptor binding in the striatum. Another PET imaging study conducted in a small sample of non-opioid-dependent people found that morphine produces a very small increase in dopamine receptor occupancy (about 8%), which, however, is inversely correlated with subjective ratings of ‘high’ and other measures of reward ).max = 8 min). However, dopamine levels increased with a delay of 3–4 min relative to those of 6-MAM and then declined sharply , far in advance of the much slower decline of 6-MAM . Completely different was the pattern produced by morphine. After an injection of morphine, striatal concentrations of dopamine increased much more slowly (Tmax = 46 min) than those of morphine (Tmax = 6 min). Heroin produced a third pattern: while striatal heroin peaked rapidly (Tmax = 2 min), dopamine began to rise only at 8 min  than after 6-MAM (approximately 10 nM), even though, as discussed in a previous section, the striatal concentrations of 6-MAM were about 50% higher after an injection of heroin than after an equimolar dose of 6-MAM. It is remarkable that the ratio of dopamine to total opioid concentrations  in the striatum was much smaller after heroin than after 6-MAM and followed a completely different temporal profile .Ever since the seminal paper by Wise and Bozarth , many stWith respect to heroin , 6-MAM iIncreased but delayed locomotor activity has been reported also for M6G , althougFew studies have directly compared the subjective effects of heroin and morphine in humans. Martin and Fraser  administIn preclinical studies, heroin was successfully used as a training drug in discriminative procedures. It was shown that in the rat the discriminative stimulus properties of 6-MAM and morphine overlap with those of heroin . HoweverIn a drug discrimination procedure, M6G was fully substituted for heroin in rhesus monkeys  and for The propensity of rats to electrically self-stimulate discrete brain regions  was discovered in the mid-1950s by Olds and Milner . Since tIn the early 1990s, Hubner and Kornetsky compared the effects of heroin, 6-MAM, and morphine on the threshold for ICSS of the medial forebrain bundle , and fouWhen animals are repeatedly exposed to one of the two chambers of a CPP apparatus while under the effects of an addictive drug, they exhibit a preference for the drug-paired chamber relative to the vehicle-paired chamber –196. TheA great deal of research has investigated the reinforcing effects of heroin and morphine using i.v. self-administration procedures in primates and rodents. These studies have shown greater reinforcing potency of heroin relative to morphine , 213. ThSelf-administration of 6-MAM in the rat has been investigated only recently by Avvisati and colleagues . This stPharmacokinetic modelling suggests that brain concentrations of 6-MAM might contribute to determine the pattern of heroin self-administration in the rat. In a recent study in rats, two schedules of heroin self-administration were compared. One group of rats were trained with a 20-s timeout after each heroin infusion, whereas the other rats were trained without timeout. The rats in the latter group self-administered heroin in a ‘burst-like’ pattern, which produced spikes in 6-MAM that were sharper and of greater magnitude than those observed in rats trained on a timeout schedule. Interestingly, the drops in 6-MAM concentrations coincided with the resumption of lever pressing for heroin .max for M6G synthesis in liver microsomal preparations incubated with morphine, correlated with plasma levels of M6G in rats that had self-administered heroin, whereas M6G was undetectable in rats that had self-administered saline. Furthermore, in rats trained to self-administer heroin or morphine, the M6G receptor antagonist 3-MNTX increased the infusion rate of both drugs at doses effective in blocking morphine analgesia only [To date, no study has directly investigated the rewarding effects of M6G in either humans or animals. And yet, as pointed out in previous sections, there is evidence of increased M6G synthesis in people with heroin use disorder . It has sia only , 222. Thsia only .We reviewed here major aspects of the neuropsychopharmacology of heroin and of its active metabolites: 6-MAM, morphine, and M6G. While it is often assumed that the rewarding effects of heroin depend on morphine, the contribution of 6-MAM and M6G have not yet received enough attention. Indeed, there is growing evidence that heroin and its three metabolites all play a major role in both the acute effects of heroin, and in the development of heroin use disorder.After i.v. injection in humans, heroin peaks at 30 s in the arterial blood (and presumably in the brain) , a timinOne way to untangle the contribution of heroin versus 6-MAM would be to block the deacetylation of heroin. Peripheral administration of the cholinesterase inhibitor tri-ortho-tolyl phosphate (which does not cross the blood-brain barrier) was found to increase the analgesic potency of heroin (but not that of 6-MAM or morphine) in the mouse . Yet, thmax of striatal dopamine after heroin was half that observed after 6-MAM, with a much longer Tmax (14 min after heroin vs. 8 min after 6-MAM). This suggests that the pharmacological actions of heroin somewhat ‘antagonize’ those of 6-MAM, at least for what concern dopamine release in the rat striatum. In any case, to the extent that the kinetics of dopamine release observed in the rat [Another appraoch would be to compare the brain concentration profiles of heroin and 6-MAM with the time-course of early neurobiological effects. Of course, this type of studies cannot be conducted in humans, at least at this time, but only in experimental animals. As discussed in detail in previous sections, Gottås and colleagues  found th the rat  reflect  the rat , 47, 147 the rat –225. Dop the rat , 227, alBoth morphine and M6G have been shown to possess intrinsic rewarding effects. Morphine produces subjective effects similar to those of heroin when given i.v. , 228, anThe long half-lives of morphine (about 1.5–3 h) and M6G (about 2–6 h) might play a role not only in the acute rewarding effects of heroin but also in the neural adaptations underlying tolerance, physical dependence, and transition to addiction , 231. MoIn the light of the findings summarized above, it is interesting that higher M6G/M3G concentration ratio was found in people with heroin use disorder relative to people receiving morphine for pain control . FurtherHuman studies are sorely needed to tease apart the role of heroin and its metabolites (as well as the interaction among them) in heroin addiction. At present, we know very little about the reinforcing effects of 6-MAM and M6G, and what we know comes exclusively from animal studies . Thus, it would be important to investigate the rewarding effects of these two metabolites in humans. Furthermore, future research should address four crucial questions. Is the initial, instantaneous, short-lived ‘flash’ produced by i.v. heroin due to the similarly instantaneous spike in arterial concentrations of heroin (implying a similarly instantaneous spike in the brain)? Is the subsequent pleasant state of stunned calm the result of 6-MAM actions? Is the prolonged sense of contentment and well-being experienced by some heroin users the result of morphine and/or M6G actions? Do morphine and M6G contribute to the neuroplastic adaptations responsible for heroin use disorder and vulnerability to relapse? These issues might be addressed by testing the effects of enzymatic inhibitors, as well as of compounds that mimic the pharmacodynamic profiles of heroin, 6-MAM, or morphine without being subject to enzymatic transformation in active metabolites.For a long time, morphine has been considered the substance responsible for the rewarding effects of heroin, the latter being demoted to the status of pro-drug. In this review we argued for a more complex interplay among four actors: heroin per se, 6-MAM, morphine, and M6G. This novel viewpoint has important clinical and theoretical implications.Given its chronic relapsing nature, the treatment of heroin use disorder is mainly based on long-term replacement treatment with opioid agonists such as oral methadone and sublingual buprenorphine . Both drFinally, we have emphasized the role of dopamine-independent mechanisms in heroin reward, without discounting the possible contribution of dopamine-dependent mechanisms, particularly in the case of 6-MAM. In this respect it is important to notice that major differences in the ability to engage dopaminergic transmission are not limited to heroin and its metabolites. Even more dramatic differences are evident when opiates like morphine are compared to synthetic opioids, such as oxycodone . Therefo


A photocatalyst, such as titanium dioxide (TiO2), is a material that causes a catalytic reaction when exposed to light, has exceptional characteristics such as decomposition of pollutants, and can be used permanently. This study aimed to investigate NOx reduction performance by developing ecofriendly permeable concrete with photocatalytic treatment to reduce fine dust generated from road mobile pollution sources. Permeable concrete specimens containing an activated loess and zeolite admixture were prepared and subjected to mechanical and durability tests. All specimens, including the control (CTRL) and admixture, met quality standard SPS-F-KSPIC-001-2006 for road pavement. Slip resistance and permeability coefficient also satisfied the standards, while freeze–thaw evaluation criteria were met only by CTRL and A1Z1 specimens. NOx reduction performance of the permeable concrete treated with TiO2 photocatalyst was assessed using ISO standard and tank chambers. NOx reduction efficiency of up to 77.5% was confirmed in the permeable concrete specimen with TiO2 content of 7.5%. Nitrate concentration measurements indirectly confirmed photolysis of nitrogen oxide. Incorporating TiO2 in construction materials such as roads and sidewalks can improve the atmospheric environment for pedestrians near roads by reducing NOx levels through photocatalysis.Fine dust, recently classified as a carcinogen, has raised concerns about the health effects of air pollution. Vehicle emissions, particularly nitrogen oxide (NO In particular, PM can easily infiltrate bronchial tubes and lungs; therefore, it causes various respiratory diseases as well as cardiovascular, skin, and eye diseases. Samet et al. (2000) reported that the total mortality rate increases by 0.51% if the concentration of atmospheric PM10 increases [Air pollution due to rapid economic growth is one of the problems facing the world, mainly in the form of fine dust in the process of burning fossil fuels such as coal and oil in factories and automobiles, etc. . Particue dust PM.5 when tncreases ,4. Therex) accounts for approximately 60% of PM originating from the roadside. NOx is a pollution source that secondarily generates PM2.5 by reacting with vapor (H2O), ozone (O3), and organic compounds under certain conditions in the atmosphere. NOx is mainly generated by the combustion of fossil fuels such as coal or petroleum. In particular, it is estimated that a significant amount of NOx is emitted from road mobility pollution sources in large cities with significant vehicle transit, and it has been reported that approximately 45% of NOx from Seoul has been emitted through road mobility pollution sources [x in urban areas, controlling NOx emitted through road mobility sources or using road facilities is effective. Among various road facilities, those composed of concrete, such as boundary stones, bagged and sacked concrete, and crash walls, have large surface areas; therefore, the use of infrastructure composed of functional concrete is an efficient method of reducing roadside NOx [Nitrogen oxide  and electron holes (h+) are formed when TiO2 is irradiated using light with a wavelength of 380 nm (ultraviolet rays) or below. The generated e− and h+ are strong reducing agents and oxidizing agents, respectively; thus, hydroxyl radical (OH) and superoxide anion (O2−) can be created through reaction with water and oxygen from the surrounding atmosphere, demonstrating excellent efficiency for decomposing atmospheric pollutants [x decomposition reaction mediated by TiO2 is presented in Equation (1), and x decomposition process [TiOllutants ,9,10. Tillutants . The NOx process .(1)Actix using TiO2 photocatalysts that demonstrate excellent decomposition of organic matter. Guo et al. (2020) assessed the photocatalytic decomposition efficiency of concrete consisting of nano-TiO2 photocatalysts [2 into the concrete: (1) directly mixing nano-TiO2 particles with concrete and (2) spreading nano-TiO2 particles onto the concrete surface by spraying. They reported that the photocatalytic efficiency improved when concrete was not polished according to the increase in nano-TiO2 content increase as well as the increase in the concentration of pollutants. Gopala Krishna Sastry et al. (2021) experimentally studied the effect of nano-TiO2 on fly ash-based geopolymer concrete durability and strength [2 were assessed; the fly ash-based geopolymer concrete was soaked in magnesium sulfate and sodium chloride to assess durability. They reported that the strength and durability of the fly ash-based geopolymer concrete increased as the amount of substituted TiO2 increased. Kim et al. (2018) investigated the NOx removal efficiency of the highway-retaining wall of South Korea’s Gyeongbu Expressway, where TiO2 was spread onto the concrete surface through a surface penetrant [x concentration was reduced by approximately 12% following the addition of TiO2. Additionally, they reported that the NOx removal efficiency increased as the amount of sunshine and traffic increased. Beeldens (2014) investigated the photocatalyst block pavement in Antwerp, Belgium [2 photocatalyst paint in a parking lot [2 in the Umberto 1 tunnel in Rome to identify its NOx reduction capacity [2 photocatalyst is only active in UV light, which is about 5% of sunlight [2/g-C3N4@Ag NPs showed visible light activation and improved photocatalytic performance under not only UV but also visible light irradiation [Various studies have investigated the reduction in atmospheric NOatalysts . They utstrength . In theienetrant . They re Belgium , and Th.king lot . Furtheret al. 20 investigsunlight ,20, variet al. 20 experimesunlight ,23. Islaadiation .x reduction performance of road pavement concrete coated with TiO2 photocatalysts to reduce fine dust generated from roadsides for pedestrians. Unlike asphalt or general concrete pavement, rainwater is drained to prevent aquaplaning, enabling smooth passage of vehicles and moving objects, and a permeable concrete containing ecofriendly materials was developed. In addition, a tank photoreactor was fabricated and the NOx reduction efficiency of the specimen that utilized real-size construction material was determined. For this purpose, the mixing ratio of permeable concrete for sidewalk pavement was derived, and the compressive strength, bending strength, freeze–thawing resistance, skid resistance, and permeability performance were determined. Next, TiO2 photocatalyst was coated onto the fabricated permeable concrete mixed with the derived optimal mixing ratio to assess the NOx reduction efficiency according to the TiO2 content. NOx reduction assessment involved analysis using a newly developed tank chamber that can accommodate large-scale specimens and an ISO standard chamber that uses small specimens. Additionally, a water quality analyzer was used to identify the generated nitrate concentration after NOx reduction assessment.Thus, this study investigated the NO2 photocatalyst is mixed/spread as pavement material for sidewalks and bicycle roads reduces NOx generated from road mobility pollution sources such as vehicles/motorcycles, and the effect of NOx on pedestrians can be directly reduced. To this end, the durability of permeable concrete containing a mixture of active loess and zeolite and the NOx reduction efficiency of TiO2 spray coating was assessed at the laboratory level.Most road pavements are made up of asphalt or concrete; hence, the surface layer and base layer are impervious. Consequently, rainwater wells up when there is heavy rainfall, resulting in hydroplaning. Hydroplaning reduces skid resistance, threatens safety, and disturbs smooth transit. Permeable concrete has increased permeability owing to the mixture of single-size particle aggregate, cement, and water. Paving roads with this permeable concrete can smoothly drain rainwater unlike general concrete/asphalt pavements and facilitate smooth transit of moving objects. In particular, using permeable concrete where TiO3 and Blaine of 3000 cm2/g.2 and Al2O3 by rapidly cooling natural red clay after high-temperature heating. According to previous research, concrete containing active loess is known to have strong acid resistance. In particular, active loess as a material that forms a porous structure is an environmentally friendly material that has excellent far-infrared radiation emissivity and deodorant performance. Zeolite is mainly composed of SiO2 and Al2O3 similar to other pozzolan material and forms a porous structure similar to active loess. Zeolite is known to have outstanding absorption performance owing to its excellent cation exchange properties. Therefore, this study used porous active loess and zeolite as mixing materials for the permeable concrete to improve the coating performance of TiO2 photocatalyst. 3 and 1.27%, respectively.The active loess is red clay that activates SiO®W740X by Evonik Industries AG, and an anatase-type TiO2 with outstanding photolytic efficiency was used. The characteristics of AERODISP®W740X used in this study are summarized in The photocatalyst used as surface coating material of permeable concrete in this study was a product of AERODISP®W740X product used as a surface coating material for permeable concrete has a high solid fraction with 40% TiO2 content. To determine the optimal TiO2 content for reducing NOx, photocatalysts with varying TiO2 content were used as shown in ®W740X. T0 refers to the permeable concrete where the photocatalyst was not spread.The AERODISPIn the SPS-F-KSPIC-001-2006(2018) standard (Korea standard), the evaluation criteria and quality required performances of permeable concrete for road pavement are presented as shown in The effect of the method of compaction and compaction intensity of permeable concrete on its strength properties and durability are significant. Therefore, this study compacted permeable concrete by performing the free fall of a rammer that is 50 mm in diameter and 2.5 kg in mass at 300 mm height, as shown in The compressive strength of permeable concrete was assessed on days 7, 14, and 28 using a single-axis compression test according to the KS F 2405 standard. The bending strength, skid resistance, and permeability coefficient of permeable concrete were assessed on day 28 according to the KS F 2408, KS F 2375, and KS F 4001 standards, respectively. Lastly, the freeze–thaw resistance was assessed on day 28 using a single-axis compression test according to the KS F 2405 standard with the specimen that underwent 100 cycles of freezing and thawing according to the KS F 2456 standard.x removal performance of the photocatalyst, the schematic of nitrogen oxide reduction evaluation system that complies with ISO 22197-1(2016) is shown in x reduction evaluation system consists of a test gas supplier, a photoreactor (test chamber), and a test gas analyzer. The test gas supplier consists of a flow controller, a humidifier, a gas mix tank, etc. A mixture of dry air, moist air that has passed through the humidifier, and polluted gas supplies 1ppm polluted gas with 50% relative humidity. The test chamber for testing NOx reduction was fabricated in two sizes: an ISO standard photoreactor (sample size 100 mm × 50 mm × 5 mm) for small specimens and a tank photoreactor (tank size 240 mm × 140 mm × 200 mm) for large specimens such as concrete and asphalt construction materials. The upper part of the chamber was composed of tempered glass that ultraviolet (UV) could penetrate. As the size of the specimen for testing NOx reduction, a small specimen of 50 mm × 10 mm × 5 mm in size is used for the ISO standard photoreactor, but the ISO standard photoreactor specimen guideline was corrected to the size of the aggregate used in permeable concrete fabrication (10 mm or above), and permeable concrete 50 mm × 10 mm × 25 mm in size was fabricated for use. In the case of the tank photoreactor, a permeable concrete compressive strength test piece (100 mm diameter × 50 mm height) was used. Images of each chamber and specimens are shown in −1 and stabilized for 1 h. Then, the pollutant gas concentration was documented for 5 h while irradiating with a UV lamp at a wavelength of 325 nm. Lastly, the UV lamp was turned off and the pollutant gas concentration was observed for 1 h. The NOx reduction efficiency of the photocatalyst could be determined using the NOx concentration (NOxequil) at equilibrium during the photocatalyst reaction and the initial NOx concentration  (Equation (2)).To assess the NOx reduction experiment  in both reactors were used. As an indirect measurement method for validating the photodecomposition reaction of nitrogen oxide, the nitrate concentration on the surface of photocatalyst-coated permeable concrete was analyzed . Distill2, is also reduced [ reduced ,31,32,33−3 cm/s with the lowest compressive and flexural strengths. However, this was determined not to be a significant difference between other specimens. The skid resistance of all specimens satisfied the standard of 1 × 10−3 cm/s of permeable concrete presented by SPS-F-KSPIC-001-2006.2 content, the photocatalyst was coated with varying TiO2 contents onto the A1Z1 permeable concrete supporter, and a nitrogen oxide removal experiment was performed in the ISO standard photoreactor chamber according to ISO 22197-1:2016.To assess the nitrogen oxide removal performance of the photocatalyst according to TiOx reduction performance according to photocatalyst content, and the average NOx reduction efficiency values of each specimen are summarized in x reduction efficiency of 1.6%. In all specimens with photocatalyst coating, the NO gas concentration rapidly decreased owing to the activation of the photocatalyst reaction after lighting the UV lamp, the photocatalyst reaction was deactivated after turning off the UV lamp, and recovery to the initial concentration was shown. Additionally, the tendency of an increase in nitrogen oxide removal efficiency was shown according to the increase in photocatalyst content, and the NOx reduction effect was the greatest at 77.5% with 7.5% TiO2 content. Meanwhile, with 10% TiO2 content, the NOx reduction efficiency was 67.7%, which was lower than that with 7.5% TiO2 content despite the higher TiO2 content. In this result, the reason for the maximum NOx reduction effect of permeable concrete using T7.5 photocatalyst is that TiO2 particles of 70 nm show the most appropriate dispersion and adsorption at a content of 7.5% in macro- and micropores on the surfaces of active loess and zeolite as porous materials and coarse aggregate.x reduction assessment of construction materials with large volumes, such as concrete and asphalt, a tank photoreactor chamber that modified the ISO 22197-1:2016 standard experiment regulation was fabricated, and the NOx reduction experiment was performed with the compressive strength test piece. For the photocatalyst used in surface coating, T7.5 and T10, which demonstrated high efficiency in previous experiments, were used, and the results are shown in x reduction efficiency value in the sample using the compressive strength test piece in the tank photoreactor was lower than that in the ISO standard photoreactor despite the broad coating area. The observed low NOx reduction efficiency can be attributed to the larger volume of the tank photoreactor compared to the specimen in the ISO standard photoreactors. As the volume inside the chamber increased, the NOx reduction efficiency decreased due to the increase in the amount of pollutants to be reduced compared to the photocatalyst coating unit area. In addition, as shown in 2 content than with 10% TiO2 content.For the NO2 photocatalyst decomposition reaction, the concentration of nitrate generated directly after the NOx reduction experiment was analyzed. The nitrate content accumulated on the surface of T0, T7.5, and T10 specimens that completed the NOx reduction experiment from the ISO standard photoreactor and tank photoreactor was dissolved in distilled water for extraction. Nitrate concentrations in the specimens in both photoreactor types measured through the water quality analyzer are summarized in x reduction experiment revealed that a photodecomposition reaction occurred in the specimen treated with TiO2 photocatalyst. In addition, higher nitrate concentration was shown in specimen T7.5 than in T10; this was attributed to the greater amount of nitrate generated in specimen T7.5 with higher NOx reduction efficiency than in T10, as shown in the NOx reduction experiment results. The specimens in the tank photoreactor exhibited a similar trend to the results observed in the ISO standard photoreactor specimens.As an indirect method of identifying the TiO2 photocatalyst to construction materials for enhancing air quality has garnered significant interest among researchers in both industry and academia. In line with the objective of creating functional construction materials to reduce NOx emissions from roadside sources, this study focused on developing permeable concrete containing porous materials like active loess and zeolite for sidewalk pavements. The NOx reduction performance was then evaluated with the application of TiO2. Based on our findings, the following conclusions can be drawn:1.A decrease in the physical performance of permeable concrete that includes active loess and zeolite was observed in comparison to the CTRL, but they all satisfied the quality standard of permeable concrete for sidewalk and road pavement.2.The skid resistance and permeability coefficient showed results that satisfy standards for sidewalk concrete in all permeable concrete specimens, but the quality standard was satisfied at 80% or above of residual compressive strength in only CTRL and A1Z1 specimens in the freezing and thawing experiment.3.2 photocatalyst.Considering the physical and durability performances of this study, A1Z1 mixture was determined as the optimal mixing ratio for permeable concrete for applying TiO4.x reduction efficiency tended to increase according to the increase in TiO2 content. With 7.5% TiO2 content, a maximum NOx reduction efficiency of 77.5% was observed.The NO5.The tank photoreactor of the specimen using the compressive strength test piece also showed similar results to the NOx reduction tendency in the ISO standard photoreactor.6.x reduction assessment, it was found that a photocatalyst reaction occurred during UV irradiation on the surface of the photocatalyst-coated permeable concrete. Additionally, higher nitrate concentration and higher NOx reduction efficiency were observed with 7.5% TiO2 content than with 10% TiO2 content.By assessing the nitrate concentration generated after NOThe application of TiO


Biochar (BC), a byproduct of agricultural waste pyrolysis, shows potential as a sustainable substitute material for ordinary silicate cement (OPC) in concrete production, providing opportunities for environmental sustainability and resource conservation in the construction industry. However, the optimal biochar dosage and fineness for enhancing concrete performance are still unclear. This study investigated the impact of these two factors on the mechanical and durability properties of biochar concrete. Compressive and flexural strength, carbonation resistance, and chloride ion penetration resistance were evaluated by varying biochar dosages  and fineness dimensions , with the 0% dosage serving as the control group (CK). The results showed that the addition of 1–3 wt% of biochar could effectively reduce the rapid carbonation depth and chloride diffusion coefficient of concrete. The compressive and flexural strength of BC concrete initially increased and then decreased with the increase in biocarbon content, BC with a fineness of 73.28 μm having the most significant effect on the mechanical strength of concrete. At the dosage of 3 wt%, BC was found to promote the hydration degree of cement, improving the formation of cement hydration products. These findings provide valuable insights for the development of sustainable and high-performance cement-based materials with the appropriate use of biochar as an additive. However warming . Hence, Biochar is a kind of biomass material produced by pyrolysis of waste biomass at a high temperature under anoxic conditions . IncorpoAlthough using biochar in cement-based composites offers many advantages, the impact of biochar fineness on concrete strength development and durability remains inadequately studied. In the existing body of literature, there is a prevailing consensus that the incorporation of fine BC into cement production results in improved hydration reactions and mechanical strength compared to the use of coarse BC ,19. SuchIn this study, waste wood was used as the raw material to prepare biochar (BC). Four different fineness levels of BC were produced by grinding with a grinder for 20 s, 30 s, 1 min, and 2 min, respectively, and were used to prepare biochar concrete with varying BC content. The effects of BC on the anti-carbonation and anti-chlorine ion permeability, as well as the compressive and flexural properties of concrete, were investigated. The mechanism underlying the performance change of biochar concrete was analyzed, and the relationship between fineness and BC content is discussed. The findings of this research are expected to contribute to further studies of the properties of cement composites containing BC and the wider use of environmentally friendly BC as a supplementary cementitious material (SCM) to reduce agricultural waste.3. All the materials were procured from the Nanning Conch cement sales store.The cement used in this experiment was P.O.42.5 grade ordinary silicate cement from the Conch brand, and its physical properties are shown in In this study, we chose waste wood as a raw material for the preparation of BC. First, the collected four kinds of raw materials were dried and put into a sealed container and then put it into a muffle furnace, heated to 500 °C for cracking at a heating rate of 20 °C/min under anoxic conditions, and kept at a constant temperature for 2 h to completely carbonize them. The BC obtained by pyrolysis at high temperatures was naturally cooled to room temperature. Then, it was removed from the muffle furnace and crushed with a pulverizer for 20 s, 30 s, 1 min, and 2 min, respectively, to obtain four kinds of BC with different fineness levels, which were placed in sealed bags for later use. The specific production process is shown in The fineness distribution of BC was measured using the LA-960 A laser fineness analyzer from HORIBA, Ltd. in Kyoto, Japan, which is capable of measuring fineness ranging from 10 nm to 5000 μm. BC was used to replace cement in equal amounts at biochar dosages of 0%, 1%, 3%, 5%, and 10% by weight and a water-to-binder (w/b) ratio of 0.45, as presented in According to GB/t 50082-2009 , the car2/s) could be determined. The chloride ion diffusion coefficient is calculated by Equation (1):nssmD is the non-stationary migration diffusion coefficient (10−12 m2/s); T is the average value of the initial and final temperatures in the anode electrolyte solution (°C); U is the absolute value of the applied voltage (V); L is the thickness of the sample (mm); t is the test duration (h); and dx is the average penetration depth (mm) at the seven locations measured.To perform the chloride ion rapid penetration test of concrete specimens, the anode and cathode were filled with 0.3 mol/L NaOH solution and 3% NaCl solution, respectively, and the direct current power supply voltage was set at 25 V. The newly cracked section was then sprayed with silver nitrate solution, and the test duration was set to 48 h. The chloride ions infiltrated into the sample reacted with the silver nitrate, resulting in the formation of white precipitate, from which the penetration depth and chloride ion diffusion coefficient Dnssm 2. Their characteristic peaks changed with variations in biochar fineness. As the biochar fineness decreased, the intensity of CaCO3 diffraction gradually decreased, while the intensity of SiO2 and Ca(OH)2 diffraction initially decreased and then increased.To further investigate the impact of biochar fineness on cement hydration, X-ray analysis was conducted on 28-day concrete specimens with a 3% biochar dosage. The main mineral composition of each group of specimens is presented in 2 reacts with SiO2 based on biochar as a carrier [2 and transforms it into a higher-strength C-S-H cementitious gel, which fills the concrete pores and increases its strength, better explaining the concrete’s compressive strength peak. However, when BC-3 and BC-4 were added, the secondary reaction of the hydration product Ca(OH)2 was weakened or even prevented by the adsorption of some of the free water onto the biochar. Consequently, there were increases in Ca(OH)2 and SiO2 content and a reduction in the C-S-H gel produced, leading to a reduction in the biochar concrete’s strength development.These findings suggest that biochar modifies the cement hydration process by influencing the formation and transformation of hydration products. When added in appropriate quantities, Ca(OH) carrier . This prIncreasing biochar fineness initially led to a decrease in rapid carbonation depth and chloride diffusion coefficient, followed by an increase. Adding 1–3% biochar resulted in the rapid carbonation depth and chloride diffusion coefficient of concrete decreasing by a maximum of 17.9% and 32%, respectively.The compressive and flexural strength of concrete increased and then decreased as the replacement rate of BC increases. When the content was less than 5%, the strength of biochar concrete was not lower than that of the control group. Of all the biochar fineness levels tested, BC-2 exhibited the most significant improvement in the strength of concrete.SEM and XRD analyses demonstrated that the addition of biochar enhanced the microstructure of concrete by facilitating additional nucleation sites for cement hydration and filling internal pores, ultimately leading to a more uniform and dense composition.This paper investigated the four different fineness levels of biochar made from waste wood as a raw material and their effects on the anti-carbonation properties, chloride ion resistance, and compressive and flexural strength of cement materials after mixing with biochar. Based on the experimental results, the following conclusions were drawn:In conclusion, the addition of biochar made from waste wood could effectively improve the anti-carbonation properties, chloride ion resistance, and mechanical strength of cement-based materials. The results of this study provide valuable insights for the development of sustainable construction materials with improved performance.


Two studies are reported that extend the evidence base for use of the Personal Stigma of Suicide Questionnaire (PSSQ). In the first study (N = 117), the Rosenberg Self-Esteem Scale, the WHO-5 measure of well-being, as well as measures of suicidality were examined in relation to the PSSQ. A self-selected sub-sample (N = 30) completed the PSSQ after an interval of two months. In line with the stigma internalization model, when demographic variables and suicidality were accounted for, the PSSQ self-blame subscale was the most significant predictor of self-esteem. As for well-being, the rejection subscale was involved as well as self-blame. The retest stability of the PSSQ for the sub-sample was 0.85 and coefficient alpha for the total sample was 0.95, indicating both good stability and internal consistency for the scale. In the second study (N = 140), PSSQ was studied in relation to intention to seek help from four sources in the case of suicidal ideation. The strongest relationship with PSSQ was with intention not to seek help from anyone (r = 0.35). When other variables were included in the prediction of help-seeking from a general medical practitioner, family or friends, or from nobody, the only significant PSSQ correlate was minimization. For help-seeking from a psychologist or psychiatrist, the most significant predictor was judged helpfulness of prior contact with them. The results from these studies strengthen previous findings of the construct validity of the PSSQ and point to its utility in understanding barriers to help-seeking among those experiencing suicidality. Stigma originally meant a bodily mark indicative of disease, but over time has come to mean a mark of shame or discredit that, as Goffman  observedLess research has been directed to the stigma of suicidal behaviour, although it can affect well-being and can act as a barrier to necessary care . SheehanOne of the few scales that assesses suicide stigma from the perspective of the individual experiencing it is the Personal Suicide Stigma Questionnaire (PSSQ) . The terBecause the PSSQ is relatively new, there is still limited data on its construct and discriminant validity. Scores on the PSSQ have been found to relate positively to an index of suicidality (r = 0.68) and to a measure of mental illness stigma (r = 0.30) . The corIn seeking to extend the construct validity of the PSSQ, we drew on the model proposed by Corrigan and colleagues ,14 to acA similar process of internalization of stigma, we argue, applies to suicide stigma. Becoming aware of the social stigma of suicidal behaviour can lead the person to agreement and concurrence with the stereotype, and this in turn can lead to reduction in self-esteem and subsequently to other impacts on well-being and the likelihood of seeking help for the behaviour. We further posit that the minimization and rejection subscales of the PSSQ encompass perceptions and experiences of stigma and reflect awareness of the suicide stereotype, and that the self-blame subscale assesses self-stigma, which, by Corrigan and colleagues’  definitiWe examined this formulation of personal stigma of suicide in two studies. Study 1 examined the links between the PSSQ and its subscales, on the one hand, and self-esteem and well-being, on the other. In a second study, the links between stigma and help-seeking were examined. A second study was necessary because of the need to control for other factors that can potentially influence help-seeking.Because no previous studies had examined the retest reliability of PSSQ, a second aim of Study 1 was to address this gap by re-administering the test two months after the first administration. Stability of scores over time is of particular importance where a test is being used to assess change as a consequence of an intervention. A test that yields unstable scores cannot accurately reflect reliable change. We chose two months as an interval that was unlikely to allow simple recall of previous responses and of the duration of counselling or psychoeducational interventions (6–10 weeks) that might be employed to reduce stigma. Our expectation was that the retest reliability of the PSSQ is at least “good” according to standards proposed by Cicchetti ; that isp < 0.0125 (0.05/4). According to GPower , gender , education , relationship status , or employment . Those who provided a second test result did not differ from those who did not in terms of age , gender , education , relationship status , or employment .Those who did not complete the psychological test section of the survey did not differ from those who did in terms of age . For the subscales of the PSSQ the values were: for rejection 0.86 [0.728 to 0.931]; for minimization 0.74 ; and for self-blame 0.69 .An ongoing problem in suicide prevention is putting those in need of help in touch with professional services . In theiThe present cross-sectional study examined both suicide literacy, using the SOSS, and suicide stigma, using the PSSQ, in relation to help-seeking as assessed with the GHSQ, as adapted by Calear et al. . We expeWe also included an assessment of whether or not participants had previously sought professional help and how useful that had been for them. This was based on the four-item prior counselling measure (PCM) described by Wilson et al. . In theiAs in Study 1, participants were screened for past suicidal ideation or behaviour. We used the same logic as in Study 1 and G*Power 3  to estimThis study included the 16-item PSSQ for assessment of personal suicide stigma as described in Study 1. In addition to age and gender, participants were asked about their educational background, which was reduced to a two-level variable: having had education/experience in the mental health field (coded 1) and no education/experience in the mental health field (coded 0).The GHSQ, as adapted by Calear et al. , was useThe PCM ,35 comprThe 27-item version of the LOSS  was usedThis study used the same online software platform (REDCap) and participant recruitment procedure as in Study 1. In a departure from Study 1, based on ethical concerns, the participants were advised through the survey that completion of all questions was voluntary to ensure that forcing an answer to a particular question was not distressing for the participant. Upon completion of the survey, participants were provided with an information page of options for support if the participant was affected by the survey items. Participants were advised that the survey included 59 questions and would take approximately 25 min to complete. The final survey page included a link for participants who chose to enter the prize draw (one of three $50 gift vouchers). This took them to a new page not linked to the survey where they could provide contact details.Prior to conducting this study, it was approved by the University Research Ethics Committee (GU Ethics Ref: 2021/443).Possibly because of the permissive instructions, coupled with the opportunity to enter the prize draw, there was a substantial amount of missing data. Of the 187 cases registered on the data base, 35 provided no responses to any of the questions, 9 provided responses only to the demographic questions, and the data for 3 were deleted because they indicated on the screening question that they had not experienced suicidal thoughts. Of the remaining 140, missing values ranged from 2.1% to 9.3% for the help-seeking items, from 12.9% to 15.7% for the previous experience questions, from 13.6% to 15.7% for the PSSQ items, and from 22.1% to 24.3% for items on the LOSS. Listwise deletion would have resulted in the loss of 61 participants.2 (df = 1334) = 1424.957, p = 0.041], indicating that the data were more likely missing at random than missing completely at random. Multiple imputation [Little’s MCAR test was statistically significant [χputation ,39 was iPearson correlation was used to examine bivariate relations among the help-seeking intentions and other measures. Hierarchical multiple regression analyses were performed using each of the four sources of help as an outcome. The demographic factors were entered at the first step, followed by LOSS score and PSSQ subscales at the final step. For those who reported prior treatment from mental health professionals, additional regression analyses were run predicting seeking help from psychologist/psychiatrist and nobody, adding rated helpfulness of previous professional contact at the second step in addition to LOSS. When the multiple imputation option is employed, SPSS 23.0 does not provide tests for the statistical significance of increments in the variance accounted for at each step or beta coefficients for comparisons of variables, so only tests of the statistical significance of unstandardized regression coefficients are reported. Regression diagnostics  were run to examine the satisfactoriness of the models.Of the sample of 140 participants, 118 (84.3%) reported they had seen a professional mental health worker for a personal problem and offered an assessment of the helpfulness of the experience. Inspection of the table indicates that rated helpfulness of previous experience was the strongest predictor of intention to seek help from a psychologist/psychiatrist, and that PSSQ score was not significantly correlated with this source of help. For the other three sources of help, PSSQ and one or two of its subscales were significant predictors. For intention to seek help from nobody, PSSQ was a stronger predictor than rated helpfulness of previous professional contact. The LOSS scale was not significantly correlated with any of the sources of help.Results of the regression models are summarized in Inspection of Scores on the PSSQ and its subscales show stability over a two-month period;The PSSQ relates at a non-trivial level to measures of self-esteem and well-being, both independently and when the contribution of suicidality and demographic variables are taken into account;The self-blame subscale of the PSSQ is the major correlate in the case of self-esteem, but in the case of well-being both self-blame and rejection are involved;The PSSQ predicts help-seeking, in the case of suicidal ideation, from a general practitioner, family and friends, or from no one, but not help-seeking from a psychologist or psychiatrist, in which case previous positive experience is the statistically significant predictor;The minimization subscale of the PSSQ, and not the self-blame subscale, is the stronger predictor of help-seeking.The PSSQ was developed to assess personal stigma associated with suicidal ideation and behaviour. Previous studies demonstrated that the PSSQ has good psychometric properties, including a clear and reproducible factor structure and good internal consistency, and that it correlates with measures of reported suicidal ideation and suicide attempt ,12. ThesThese new findings speak to the reliability of the PSSQ and its subscales and to the utility and construct validity of the scale.The data on retest reliability over a two-month period indicated a high degree of agreement between PSSQ scores on the two occasions. The lower bound of the 95% confidence interval places the estimate for this sample within the range Cicchetti  describeIn exploring construct validity of the PSSQ, we adapted the model proposed by Corrigan and colleagues ,14 for sThe differences with respect to the two outcome variables might result from the breadth of the constructs involved, with well-being a more conceptually complex outcome. In this regard, it is noteworthy that current suicidal ideation remained a significant predictor of well-being once demographic variables and stigma were accounted for. This indicates that the PSSQ is not redundant with indices of suicidality but, more importantly, indicates that well-being is not a simple function of stigma but reflects the severity of suicidality. This in turn suggests that targeting only personal stigma without help with the experiences of suicidality is unlikely to be a sufficient intervention.We expected PSSQ score to predict intention to seek help beyond the prediction provided by LOSS and the judged helpfulness of previous experience of help from professional sources, which had been shown to be significant in previous studies ,34,35. WHelp-seeking from a psychologist or psychiatrist seems to be less likely if a person has mental health education or work experience. However, positive prior contact with a mental health worker was the strongest predictor of intention to seek help in the future, irrespective of mental health literacy or self-stigma. This suggests a hypothesis that an increase in the uptake of mental health services for people with suicidality is better achieved by organizing opportunities to have a positive contact with mental health specialists, such as brief contact interventions , rather In general, the PSSQ and its subscales have been shown to have some important correlates, but the mechanisms underlying these relations are not clear. The adaptation of the Corrigan model had some success but the network of relations needs further explication.These studies have certain limitations. They used a cross-sectional design and thus are uninformative with respect to the direction of effects. For example, it is unclear whether personal stigma results in lower self-esteem or whether lower self-esteem gives rise to personal stigma. Both effects may of course be occurring, with self-esteem affecting personal stigma which in turn influences self-esteem. Such reciprocal interaction is to be expected in personality functioning but can only be addressed with difficulty and only in longitudinal designs .A further limitation is that the psychological variables employed here all employed self-report as the method of measurement. Common method variance is known to inflate correlations among variables  and thisThe samples were relatively small and self-selected. Although sample sizes were in line with pre-study power calculations, participants volunteered for this study, which may well have produced bias. Participants who volunteer, particularly for a study on suicidality, may differ from those who do not and thus are not representative of the wider population. More importantly, not all those who initially volunteered actually completed this study. The attrition rate was higher than expected, which we attributed to the use of an attractive incentive and the failure to provide a mechanism for ensuring that participants completed all sections of the survey before being eligible for the prize draw. Some may well have avoided completing the psychological test items because of the time involved or because of the content, but by at least commencing the survey they became eligible. We compared those who completed with those who did not based on the information that we had available, and no differences were detected, but it remains possible that there were differences that we were not able to test. Whether the results generalize to other populations, such as patients presenting to hospital emergency departments following a suicide attempt or patients seeking treatment for suicidal behaviour awaits further examination. A larger sample and longer intervals between testing would provide more data on test–retest reliability.The network of relations demonstrated in these and previous studies, limitations notwithstanding, point to the construct validity of the PSSQ and its subscales as a measure of the personal stigma associated with suicidal thinking and behaviour. As such, they provide support for use of the PSSQ to gauge the impact of suicide stigma when working with people experiencing suicidality. Assessment of a person’s position on the scale or subscales can be a point of departure for exploration of issues relevant to the person’s experience of stigma and self-worth. The scale may also be useful in tracking changes in personal stigma over the course of counselling or psychoeducation.


Overall, the concrete with a total compounding of 30% and a compounding ratio of 2:1 has the best shrinkage resistance performance.Shrinkage deformation of concrete has been one of the difficulties in the process of concrete performance research. Cracking of concrete caused by self-shrinkage and temperature-drop shrinkage has become a common problem in the concrete world, and cracking leads to a decrease in the durability of concrete and even a safety hazard. Mineral admixtures, such as fly ash and mineral powder, are widely used to improve the temperature drop shrinkage of mass concrete; fly ash can reduce the temperature rise of concrete while also reducing the self-shrinkage of concrete, there are different results on the effect of mineral powder on the self-shrinkage of concrete, but the admixture of fly ash will reduce the strength of concrete, and mineral admixtures have an inhibitory effect on the shrinkage compensation effect of MgO expander(MEA). The paper investigates the effect of mineral admixtures on the mechanical and deformation properties of C50 mass concrete with a MgO expander(MEA), aiming to determine the proportion of C50 mass concrete with good anti-cracking properties under working conditions. The experiments investigated the effect of fly ash admixture, mineral powder admixture and MgO expander admixture on the compressive strength and deformation of concrete under simulated working conditions of variable temperature and analyzed the effect of hydration of magnesite in MgO expander and pore structure of cement paste on deformation. The following main conclusions were obtained: 1. When the concrete compounded with mineral admixture was cured under variable temperature conditions, the compounded 30% fly ash and mineral powder decreased by 4.3%, 6.0% and 8.4% at 7d age, and the compounded 40% fly ash and mineral powder decreased by 3.4%, 2.8% and 2.3% at 7d age, respectively. The incorporation of MEA reduced the early compressive strength of concrete; when the total amount of compounding remained unchanged, the early compressive strength of concrete was gradually smaller as the proportion of compounding decreased. 2. The results of concrete deformation showed that when the temperature rose, the concrete expanded rapidly, and when the temperature dropped, the concrete also showed a certain shrinkage, and the deformation of concrete basically reached stability at 18d. 3. The compounding of 30% fly ash and mineral powder As the compounding ratio decreases, the deformation of concrete increases, and the 28d deformation of concrete with a compounding ratio of 2:1 is 280 × 10 Concrete is one of the most commonly used construction materials in our life and has superior capacity under compressive loads, but it suffers from some serious defects. These defects are caused by drying shrinkage, thermal shrinkage, self-shrinkage and carbonation shrinkage, which cause the concrete volume to shrink ,2. This For large-volume concrete, with severe shrinkage deformation and high requirements for restriction, it is necessary to incorporate a large amount of MEA, but the delayed expansion of MEA can lead to shrinkage in concrete that is often overcompensated at a later stage, resulting in cracks and a reduction in all properties . To prevIn recent years, the increasing cross-sectional size of the component, cement strength level and the amount of cement per unit volume resulted in a significant enhancement in the internal temperature rise during the hardening of concrete. This makes the difference between the standard curing temperature in the laboratory and the temperature in the actual structure, which also leads to a large gap between the strength of the specimen measured in the laboratory and the strength of the concrete in the actual structure. Based on this, this paper investigates the mechanical and shrinkage properties of mineral admixtures  on MgO-based concrete in the context of the prevalence of concrete cracking in mass concrete and the actual curing temperature. The changes in expansion and mechanical properties under variable temperature conditions are studied macroscopically, and the effects of mineral admixtures on concrete are analyzed microscopically in terms of pore structure and micromorphology. By simulating the variable temperature environment inside the actual mass concrete, the concrete is mixed and formed, and then cured in the variable temperature environment; the properties of the concrete are measured, its development pattern is grasped, and its mechanism of action is studied, which can be used to guide the actual engineering projects in the future.The cement selected in this experiment is P·II52.5 Portland cement produced by Onoda of Nanjing, and the strength grade is C50; Fly ash is grade II fly ash of Nanjing Pukou power plant; The Minera powder is S95 grade Minera powder from the Pukou area of Nanjing; The expansion agent is MgO expansion agent produced by Jiangsu Subut New Materials Co. The fine aggregate is river sand with a fineness modulus of 2.7; the coarse aggregate is crushed stone with a continuous gradation of 5–31.5 mm; the water-reducing agent is polycarboxylic acid high-performance water-reducing agent produced by Jiangsu Subutech New Material Co. The chemical composition of raw materials is shown in 3, and the amount of mineral admixture is 30% and 40% of the amount of cementitious material when fly ash is compounded with mineral powder, as this paper studies the effect of the admixture of mineral admixture on the performance of concrete, fly ash is extremely effective in improving the ease of ready-mixed concrete, but the concrete Early and medium-term strength development is slow, mineral powder relative to fly ash on the concrete strength development of each age faster, but poorer than fly ash, the two double admixture of concrete after each age strength and mix compatibility are better, the best ratio of 30% to 40% of the mass of cement [In order to study the effect of mineral admixture on MgO-based concrete under variable temperature conditions, the total amount of cementitious material used is 450 kg/mf cement . In the f cement . So thisThe temperature difference generated by the heat of hydration released from the hydration of cementitious materials is the main cause of cracks in mass concrete, so a hydration calorimeter  was used to determine the early hydration process of concrete slurry containing MEA. Due to the small water-cement ratio of the cement slurry mixture, it could not be stirred in the calorimeter. Therefore, the calorimeter needs to be placed at a constant temperature of 20 °C for 24 h before testing, and 10.00 g of the test slurry is weighed with an accuracy of 0.01 g and loaded into the test cup of the reaction vessel to continuously follow the exothermic process of hydration of the net cement slurry over a period of time (72 h) to obtain a typical isothermal calorimetric curve, including the exothermic rate and the total exothermic amount with time.According to Chinese standard GB/T 50081-2019, MgO-based concrete is used in Variable temperature curve course as shown in Concrete was mixed and poured in Φ160 mm × 400 mm PVC pipe, pouring in the center of the specimen buried strain gage, and then a slight vibration until no air bubbles were generated. After the completion of the pouring, maintenance 20 °C environment, after the initial setting of the concrete will be closed with paraffin at both ends of the specimen to prevent the influence of water vapor, and then the specimen will go into the variable temperature curing box, continuous monitoring of the deformation of concrete, the concrete specimens are shown in 2 atmosphere with a temperature rise rate of 20 °C/min from 30 °C to 1000 °C.The gravel-free concrete mixes were sealed up and placed in a variable temperature curing chamber using ages of 1d, 3d and 7d. The degree of hydration of MgO was evaluated by thermal analysis. The specimens were cut into slices, soaked in anhydrous ethanol for 3d and dried in a vacuum drying oven at 60 °C for 24 h. The specimens were ground into powder and sieved through a 0.08 μm square hole sieve. The DSC-TG method was used to heat the specimens under the NSince the temperature in the natural environment shows periodic changes, the hydration of MEA will lead to constant changes in the volume of concrete. In order to be able to continuously track the volume deformation of MgO concrete, this experiment uses the MCU-32 automatic measuring instrument produced by Nanjing GeNan Industrial Company in China. To track the strain gauge, strain variables of the test and the acquisition time interval is 1 h. Since the temperature change under natural conditions will cause the volume of concrete to deform, the result calculated by Equation (1) is the strain variation of the concrete specimen after excluding the temperature deformation.In Equation (1) −6/F).−6/°C).−6/°C).Determination of pore structure and porosity of concrete mixes by Poremaster GT-60 mercury compression meter . The samples of 1d age were cut into small pieces of 2–3 mm in size, put into anhydrous ethanol to terminate hydration, soaked for 3d, and then dried in a vacuum drying oven at 60 °C for 24 h before being taken out for testing. The pore pressure was 415 Mpa, and the pore range was 0.007 μm–360 μm.Samples were taken from the pressed concrete specimens, soaked in anhydrous ethanol to terminate hydration, soaked for 3d, dried at a temperature of 60 °C for 24 h and then removed, the specimens were coated with gold, and the microscopic morphology of concrete was observed using a JSM6480 scanning electron microscope, and the relationship between strength and concrete structural densities was desired.2+ and OH−. On the other hand, the high concentration of SP also inhibited the nucleation growth of unhydrated cement particles and the formation of Ca(OH)2, which led to a slower hydration process in the HPC system [C system . It is pAs shown in 2 and Mg(OH)2 stimulated the volcanic ash activity of the fly ash, producing large amounts of C-S-H, C-A-H, and M-S -H [−6, and the stable value is −50 × 10−6, showing a shrinkage state. In the proportion of concrete mixed with MEA, the maximum volume deformation of concrete mixed with 30% second-grade fly ash and 10% mineral powder is 220 × 10−6, and the stable value is 150 × 10−6. The maximum volume deformation of concrete with 26.7% second-grade fly ash and 13.3% mineral powder is 230 × 10−6, and the stable value is 180 × 10−6. The maximum volume deformation of concrete with 20% secondary grade fly ash and 20% mineral powder is 250 × 10−6, and the stable value is 170 × 10−6. It can be seen from the above data that the concrete mixed with 26.7 secondary fly ash and 13.3% mineral powder has the smallest shrinkage with the decrease in temperature, and the concrete has the best shrinkage resistance.d M-S -H ,26. The 2-H2O system, MgO can not only be chemically synthesized into Mg(OH)2 but also react with SiO2 to form M-S-H. Among them, the energy required to complete the second reaction is less than the first one [2 content increases. This way, the residual SiO2 combines with MgO and Mg(OH)2 as much as possible to form M-S-H [irst one . With thrm M-S-H ,32,33,342 and Ca(OH)2 undergo thermal decomposition at a temperature range of 330–420 °C and 420–500 °C, respectively [The TG curves of C4, C5, C6, C7, C8 and C9 samples at d 1d, 3d and 7d are shown in ectively ,37.2 can be calculated according to Equation (4) and The equations of the calculation equation are displayed in Equations (2) and (3). The fraction of the mass of the sample at 1d age under variable temperature conditions is displayed in 2 (%); 2, H2O (g/mol). In Equations (2)–(4) 2 in the pure pulp of Grade II fly ash and mineral powder cement mixed with 30% and 40% at variable temperatures. It can be seen from the figure that, The Mg(OH)2 content of concrete slurry with 22.5% secondary fly ash, 7.5% ore powder, 20% secondary fly ash 10% ore powder, 15% secondary fly ash, 15% ore powder, 30% secondary fly ash 10% ore powder, 26.7% secondary fly ash 13.3% ore powder and 20% secondary fly ash 20% ore powder at 7 days age, respectively is 9.24%, 9.51%, 9.86%, 8.60%, 8.60% and 9.73%. 15% secondary fly ash has the largest Mg(OH)2 content and corresponding deformation, with an expansion of 350 με at 7d, while 30% secondary fly ash 10% mineral powder has the lowest Mg(OH)2 content and the lowest deformation, with an expansion of 170 με at 7d. The curve in the figure also decreases with the increase of secondary fly ash content and the decrease of mineral powder content. For example, the C6 curve in the figure is above C5. It can be seen that the incorporation of fly ash weakens the hydration process of magnesium oxide to some extent. Although the Mg(OH)2 content of 15% secondary fly ash and 20% secondary fly ash is very similar at 3d age, the expansion of the former is 120 με larger than that of the latter. From the point of view of total shrinkage compensation, the concrete mixed with 20% secondary fly ash and 10% mineral powder is the most suitable.2 crystals is related to the hydration of MgO, which leads to premature swelling. Strongly demonstrates the positive effect of fly ash on improving the structural compactness of concrete. There are two possible reasons for this positive effect. One is that fly ash attenuates the delayed over-swelling by reducing Mg(OH)2, and the other is that it forms a better cement matrix.In order to have a deeper understanding of the differences in the mechanical strength development of C4 and C6 samples from 3d to 60d, In this topic, the effects of mineral admixtures on MgO concrete under variable temperature conditions were systematically studied from some aspects, such as shrinkage properties, mechanical properties and microstructure. Based on the experimental results, the following conclusions can be obtained.1.Compared with the sample without MEA, the addition of MEA can significantly reduce the heat flow of cement, increase the mineral admixture can, reduce the heat of hydration and inhibit the delayed overexpansion of concrete, improve the later mechanical properties of concrete, and reduce the risk of cracking of concrete.2.The results of the self-shrinkage show that concrete expands sharply and then shrinks under variable temperature conditions. However, concrete without MEA eventually exhibits shrinkage, while concrete with MEA exhibits expansion. The incorporation of mineral admixtures prevents cracking of the concrete due to self-shrinkage and prevents delayed over-expansion of the concrete in the later stages.3.Under variable temperature conditions, the addition of mineral admixtures will lead to a decrease in the mechanical properties of concrete, but the amount of reduction is very small and meets the actual needs. Under variable temperature conditions, the mechanical properties decrease with the decrease of fly ash content, indicating that the incorporation of fly ash is conducive to the mechanical properties of concrete.4.The XRD and TG results show that under variable temperature conditions, fly ash leads to weaker shrinkage resistance of concrete in the early stages by reducing the hydration of MEA inside the concrete, and in the later stages, mineral admixtures form stronger concrete cementing substances through secondary reactions. Overall, fly ash can harmonize the relationship between shrinkage resistance and shrinkage of concrete.5.MIP analysis shows that the porosity of the C5 sample with 10% ore powder of 20% fly ash is 16%, while the porosity of 20% ore powder of 20% fly ash is 17%. Increasing the ore powder content can increase the porosity, indicating that a large amount of ore powder is not conducive to the thinning of pore size. The addition of fly ash makes the pore size refined continuously, the porosity reduced, and the hydration products closer to each other. It will make the structure of concrete more dense and strengthen the mechanical properties of the content.By studying the laws of mineral admixtures on the mechanical and shrinkage properties of concrete under variable temperature conditions. When working on mass concrete, we need to fully consider its internal temperature rise due to the hydration of cement, where temperature gradient changes can lead to cracking of the concrete, thus, affecting the durability performance of concrete and even safety hazards. In order to reduce the temperature rise of concrete, we can take the internal buried cooling pipes and also add mineral admixtures. The above study found that adding 30% of mineral admixture is the most suitable, and 30% of the total amount of compounding, compounding ratio 2:1, and the best case, its final deformation for the expansion state, to solve the cracking of concrete because of shrinkage, also will not occur excessive expansion of concrete, its mechanical properties are also to meet the project requirements.