This paper investigated the preparation method and the dispersion behaviour of Modified Carbon Nanotube-fiber Reinforcements (MCNF), the change laws and the effect mechanisms of dynamic compressive strength of MCNF concretes. Electrophoresis method was used to prepare MCNF and its interfacial shear performance was tested by interfacial shear strength (IFSS) test. In addition, the dispersion behavior of MCNF in simulated concrete solution was verified by turbidity method. Split Hopkinson Pressure Bar (SHPB), Scanning Electron Microscope (SEM) and Mercury Intrusion Porosimetry (MIP) tests were carried on concrete samples with different volume fractions  of MCNF. The results show that carbon nanotubes are easier to deposit to the negative electrode, and the higher the content of polycarboxylate superplasticizer, the more obvious the dispersity of MCNF in alkaline environment. The dynamic compressive strength of MCNF concrete was 14.0–35.5% higher than that of untreated concrete, and reached the maximum when the MCNF content was about 0.3%. The MCNF was wrapped in concrete matrix and promoted hydration reaction of interface between cement and MCNF from microscopic observation. The addition of MCNF could increase the porosity. The volume percentage of ≥ 100 nm pore decreased first and then increased. Reasons for the improvement strength of MCNF concrete is that the bridging effect is stronger with the increase of MCNF content (≤ 0.3%) and limited when the MCNF content is equal to 0.4%. MCNF concrete could be used in actual engineering with high requirements for dynamic load. On the other hand, scholars have carried out extensive studies on the mechanical properties of various fiber reinforced concrete, such as steel fiber reinforced concrete7, basalt fiber reinforced concrete10, carbon fiber reinforced concrete16, and polyethylene fiber reinforced concrete18. Fiber-modified concrete has become one of the development trends of concrete in the future.Nearly all construction buildings suffer dynamic loads, such as wind load, earthquake load and violent collision. The impact load of weapon explosion has been considered in structural design of military protection facilities, underground command posts and other national defense projects. Concrete is the primary material used in the design and construction of civil architecture and national defense engineering. Therefore, how to effectively improve the dynamic impact mechanical properties of concrete has become the focus and hotspot of the research and development of concrete materials. In this regard, carbon fiber, steel fiber and synthetic fiber are traditionally used to improve the tensile strength and ductility of concrete19. Therefore, it is widely used by the civil engineering community. This paper found that the traditional carbon fiber reinforced concrete has some shortcomings, such as poor surface interfacial properties and weak adhesion with the cement matrix. Under heavy loads, carbon fiber and concrete matrix are prone to slip failure, which affects the macroscopic mechanical properties of carbon fiber reinforced concrete, and has become one of the main factors restricting the development of carbon fiber reinforced concrete.Comparatively speaking, carbon fiber and steel fiber reinforced concrete are the most widely studied and used at present. Though the effect of steel fiber on the mechanical properties of concrete is obvious, the utilization of steel fiber is limited to a certain extent due to its high self-weight and corrosion tendency. In contrast, carbon fiber not only has the advantages of high tensile strength, large elastic modulus and strong toughness, but also has excellent electrical and thermal conductivity, wear resistance and corrosion resistance. Taking the advantages of its high strength, light weight, corrosion resistance, fatigue resistance and excellent high-temperature stability, when mixed into concrete, it can not only enhance the strength and resist cracking, but also endow concrete with intelligent functions, such as electric conductivity, pressure sensitivity, temperature sensitivity, and electromagnetic shielding20. The combination of carbon fibers and carbon nanotubes can effectively overcome the shortcomings of poor surface interfacial properties and weak adhesion with the cement matrix, making them a hotspot in the field of novel material research21. The current studies on the preparation of MCNF are mature, and the main preparation methods include chemical grafting22, electrophoretic deposition23, CVD24, sizing25, etc. MCNF is currently still mainly used for research, which is seldom applied, let alone its application in concrete. And the research on the explosive impact resistance of concrete is even rarer. Due to its strain rate sensitivity, the mechanical properties of concrete material under dynamic loads differ from those under static loads26. Therefore, it is necessary to study the dynamic mechanics of MCNF concrete.MCNF is a kind of carbon fiber material. Carbon nanotubes have a unique one-dimensional tubular structure with high strength and toughness. Its Young's modulus is estimated to be 5 TPa theoretically, and the measured value is 1.8 TPa through laboratory tests, besides, its tensile strength is 100 times that of ordinary steelMCNF was prepared by using electrophoretic deposition method, and its interfacial shear performance was tested by interfacial shear strength test. The dispersion ability of MCNF was verified based on turbidimeter method. In addition, the effect of MCNF content and impact velocity on the failure patterns, dynamic compressive strengths of MCNF concrete was studied through SHPB tests. The microstructure and pore distribution of MCNF concrete were examined by SEM and MIP tests separately. And the modification mechanisms of MCNF concrete were deeply analyzed. All results are of theoretical significance for engineering design and construction with high requirements for dynamic load.The carbon fiber used T700SC-1000-50C) and the carbon nanotube (XFM06) were taken from Toray Industries of Japan and Nanjing Xianfeng Nanomaterials Technology Co. Ltd. of China, respectively. The main parameters of both products are shown in Tables 000-50C aMCNF is prepared by electrophoresis. Electrophoresis refers to the phenomenon that the charged particles move towards the electrode opposite to their electrical properties under the action of electric field. The electrophoresis equipment used is composed of a DYY-8C power supply from Beijing LIUYI Biotechnology Co., Ltd. and a self-made electrophoresis tank. The turbidimeter used (SGZ-200BS) is produced by Shanghai Yuefeng Instrument Co., LTD. of China.23.The specific preparation process of MCNF is described as follows. Firstly, remove surface sizing of carbon fibers by soaking them in acetone for 48 h, and then clean them in 200 ml alcohol for three times and in 200 ml deionized water for another three times. Dry them to constant weight at 60 ℃ before cooling them down to room temperature. Add carbon nanotubes (0.375 g) to cetyl trimethyl ammonium bromide (CTAB) solutions  under the dispersion by ultrasonic waves for 2 h. The electrophoresis tests were conducted with carbon fiber as the positive or negative electrode, and the stain less steel sheet as the other electrode. The voltage was set to 60 V, and the electrophoresis duration was 1 h27.Turbidity is used to indicate the dispersion degree of MCNF. It refers to the obstruction degree of the solution to the passage of light, including the scattering of light by suspended solids and the absorption of light by solute molecules. The specific verification process of dispersive behaviour of MCNF is described as follows. Add MCNFs (6 mm long) and polycarboxylic water reducers  into saturated calcium hydroxide (10 ml), and oscillate the mixture for 3 Min. by magnetic oscillator equipment. Finally, the turbidity of mix solution was obtained by turbidimeterIn order to verify the preparation effect of MCNF better, the interfacial shear strength test of carbon fiber and MCNF was carried out. First, a single carbon fiber was taken out from the carbon fiber bundle, fixed on a concave metal plate with double-sided tape, and then the uncured polymer matrix was slightly contacted with the fiber surface with a metal needle. The polymer matrix forms oval droplets on the fiber surface, as shown in Fig. IFSS refers to the interfacial shear strength, Fmax refers to the maximum load when the carbon fiber is peeled off, df refers to the diameter of the carbon fiber, Le refers to the length of carbon fiber wrapped in vertical ball.After the droplet matrix was completely solidified, the metal sheet was fixed in the center of a pair of symmetrical blades of the interfacial strength evolution instrument, and then a uniform load was applied to one end of the fiber until the fiber was pulled out from the droplet, and the pulling force-time curve was recorded. The fiber is pulled out, and the maximum tensile load during the pull-out process is obtained. The interface bond strength value between the monofilament carbon fiber and the resin matrix can be calculated according to the following formula:The mix ratio of concrete is shown in Table The concrete samples for SHPB tests are cylinders in the size of Φ 98 mm × 48 mm. To eliminate the interface friction effect, the mixture of graphite and lubricant in the shape of an even thin layer was applied on both ends of concrete samples before the tests.The schematic diagram of φ100 mm SHPB equipment is shown in Fig. 28.The SHPB tests are based on the elastic stress propagation theory in slender rods. It has two basic assumptions, i.e., the plane assumption and the uniform stress assumption. The former is that each cross section of the elastic rod stays in plane state when the stress wave propagates in the slender rod. And the latter is that the stress is equal everywhere inside the sample29 was adopted to calculate the stress, strain rate and strain according to the stress waveform in the elastic rod. The formulas are expressed as follows.Ce refers to the velocity of stress wave propagation in the rod, L stands for the thickness of sample, τ represents the propagation time of stress wave in rod, Ee and Ae are the elastic modulus and cross section area of rod, respectively, and As denotes the area at end face of sample.Three-wave methodSelect the samples with suitable size after crushing by SHPB tests. After that, remove the residues and dusts from the surface, and then dehydrate them completely. Coated with gold, SEM samples were observed with the appropriate magnification and scope, the others were the examined pore distribution by using Mack AutoPore IV 9500. The mercury infiltration angle was 130°, and the pressure ranged from 20 to 33,000 psi.The detailed test schedule is shown in Table 30. However, the deposition amount of carbon nanotubes was much higher when carbon fiber was used as negative electrode. The micro pictures of MCNF using carbon fiber as negative electrode and negative electrode are shown in Fig. It can be seen from the electrophoresis test results that carbon nanotubes were deposited regardless of whether the carbon fiber was positive electrode or negative electrode with the stain less steel sheet taken as another electrode in the same CTAB solution environment. It is similar to the research result of Guo JinhaiThe reason for the above phenomenon is that when using CTAB as the dispersion solution, based on the polarity of water and the non-polarity of carbon nanotubes, the surfactant molecules on the interface, namely the surface of carbon nanotubes, are arranged in order. The polar end of the surfactant is in water, which is positively charged, while the non-polar end is on the surface of the carbon nanotubes, therefore, the carbon nanotubes are positively charged in CTAB, and deposited onto the negative electrode.The interfacial shear strength test results is shown in Table 27. In another word, the higher the content of polycarboxylate superplasticizer, the more obvious the dispersity of MCNF in alkaline environment.The result of turbidity tests is shown in Fig. 31. The dynamic compressive strength of MCNF concretes under different impact loads is shown in Table Concrete samples exhibit different failure patterns under different impact forces. The main failure patterns include core retention, spalling, bulk crushing, severe crushing, thorough crushing and so onIt can be seen that the geometry of the rising section of the curve of each group of specimens is basically the same, which can be roughly divided into three stages, i.e., compaction stage, linear elastic deformation stage and yield stage. In another word, the initial internal pores of the specimen are compacted under the impact load, and the strength of the specimen increases slowly at this time; when the deformation of the specimen increases linearly to the yield point, and then enters the failure stage, it increases linearly with the strength of the specimen; while when the peak value is reached, the specimen is damaged under compression, and the residual strength decreases gradually.The effect laws of impact velocity and MCNF content for dynamic compressive strength are shown in Fig. 32 and Janach33 et al., the strain rate hardening effect of concrete can be regarded as the mechanical response of material during the transformation from one-dimensional stress state to one-dimensional strain state. The reason is that the stress inside the sample can no longer be regarded as one-dimensional stress due to the large size in the SHPB test. The surrounding concrete generate hoop pressure to the central concrete. Under the impact load, the concrete will also generate the hoop effect. And the hoop pressure effect is more obvious at larger material size and higher impact velocity34. During high-speed impact, the concrete undergoes compression deformation along the impact direction, and the height of the concrete specimen decreases. The diameter increases in the compression direction, and the concrete produces tensile stress. When the tensile stress of the concrete reaches the ultimate tensile strength, the concrete will be damaged.It can be seen from Fig. 35.It can be seen from Fig. Micro morphology pictures of concrete with 0.4% MCNF are shown in Fig. 36.The pore size distribution curves and pore proportion distribution curves of the MCNF-reinforced concrete are shown in Figs. 37 and pore distribution of MCNF concrete are shown in Fig. Pore classification method with reference to ZHANG J XThe hydration at the interface between MCNF and concrete is more sufficient because the carbon fiber absorbs the water originally used for mixing during mixing; however, due to the lack of hydration in other parts of concrete, the macropores show an overall trend of enlargement.With the increase of the content of MCNF, it becomes increasingly difficult for MCNF to disperse, and the bubbles and pores produced by the matrix gradually increase.36.With the increase of the content of MCNF, it becomes easier for MCNF to aggregate, and the uniform internal force field cannot be formed, resulting in the gradual increase of poresThe pore size of MCRC is enlarged mainly due to the following three reasons:Combining with the experimental results described above, it can be concluded that the essential reason for the change of dynamic mechanical properties lies in the balance between the porosity and bridging action. Compared with carbon fiber, MCNF has rough surface, which is more difficult to be pulled out, therefore, the bridging effect is more obvious. As shown in Fig. 38, and the further decline of the mechanical properties of the concrete.In the case of low content of MCNF (≤ 0.3%), the dispersion degree in concrete and the porosity will increase less. Therefore, MCNF can effectively connect microscopic cracks in the concrete, thereby improving the mechanical properties of MCNF concrete. In the case that the MCNF content is greater than 0.3%, the pores continue to increase. However, at the same time, due to the large pores, the original equilibrium relationship between pores and bridging is broken, and too much MCNF cannot be effectively dispersed, leading to honeycomb defects in the concrete, the decrease of the bond strength between MCNF and concrete matrixThe dynamic mechanical properties of MCNF concrete are studied. MCNF can improve the dynamic mechanical strength of concrete with low cost, which can be applied, to a certain extent, in the projects with impact load as the main load (such as railway and airport pavement). This study is of reference significance for the improvement of the dynamic mechanical properties of concrete.In CTAB solution, the electrical properties of carbon nanotubes would change, and they can be easily deposited onto the negative electrode.Compared with regular concrete, the dynamic mechanical strength of MCNF concrete increases with the increase of MCNF. It reaches the peak value at the MCNF content of 0.3%.Compared with pure carbon fibers, MCNF has a rougher surface and higher pull-out resistance, resulting in improved dynamic compressive strength.The total pore volume of MCNF concrete increases with the increase of MCNF, and the macropore also increases to a certain extent.To improve the smoothness of carbon fiber surface, carbon nanotubes were grafted on the surface of carbon fiber by electrophoresis to prepare MCNF. Then, the MCNF concrete was prepared by uniformly mixing MCNF into the concrete. The dynamic mechanical strength of regular concrete and MCNF concrete was studied at different impact speeds, and the modification mechanism was explained. The results are as follows:This paper provides a new research idea for the improvement of the surface smoothness of carbon fiber materials.


Crumb rubber concrete (CRC) is a concrete that contains rubber crumbs. This article presents a study of three experiments on long aged CRC specimens that were cored from a decade old CRC bridge deck in Tianjin, China. The three experimental tests conducted were: (1) the flexural stress–strain test on semi-circular disk specimens; (2) the accelerated steel-rebar corrosion test and (3) the carbonation test. In addition, the in situ carbonation test was also carried out on the CRC bridge deck. The flexural stress–strain test results showed that the CRC semi-circular disk specimens exhibited a ductile pattern and high-energy absorbing capacity with its flexural tensile strength being at 5 MPa and the flexural modulus of 10 GPa. The steel corrosion rust rate via the calculation of steel mass loss before and after the test in the accelerated steel-rebar corrosion test remained extremely low. The carbonation test results showed that in comparison with the prediction of two popular carbonation models, the carbonation in the CRC bridge deck took place at a much slower rate during the last 13 years. All of the results obtained in this study are reported for the first-time and indicate that these CRC cored specimens exhibit good mechanical properties and excellent durability characteristics after a decade in service, which may provide the technical knowledge for the possible future application of CRC in concrete constructions. Crumb rubber concrete (CRC) is a composite material by adding rubber crumbs into Portland cement concrete. Rubber crumbs are made by shredding old automobile tires. In this sense, CRC is a “green” material. The early study on CRC can be traced back to Savas et al.  in the eWith respect to durability, rubber crumbs can reduce noticeable early drying shrinkage in CRC . Singh eIt is fair to say that after 40 years of study, the material properties of CRC have been both well-researched and understood. The publications on CRC may exceed thousands if not ten thousands worldwide. The overall description of CRC is that, in comparison with ordinary concrete, it has high deformation/strains, energy absorption, ductility, damping capacity, cracking resistance, and excellent freeze–thaw resistance, and its benefit can go on to a long list. Despite all the good things about CRC, the real world application of CRC is very limited because CRC suffers from two weaknesses. One is that adding rubber crumbs into concrete will reduce the compressive and flexural strength that is vital to the concrete industry. The other is that rubber tends to float upward in a fresh mix when slump is high (say 10 cm or more), which causes the segregation phenomenon in the CRC mix. For the strength reduction, this can be compensated for by adding more cement and reducing the water–cement ratio at a cost hike so that the strength design requirement can be met. These days, CRC can readily be made at a compressive strength of 60 MPa or more. Regarding the rubber float-upward problem, the remedy is to add additives that increase the viscous level of the fresh concrete mix. One method is to add Superabsorbent polymer (SAP), a water-absorbing polymer, into CRC, which was successfully employed in a bridge deck construction in Henan, China in 2018 with the CRC slump being 18 cm and higher and concrete pumping facility being used in pouring CRC to the bridge deck . With thIn early August 2006, a CRC bridge deck was constructed in a suburb of Tianjin, China, as shown in Six core specimens from the aged CRC bridge deck were further investigated with respect to: (1) the spilt strength test; (2) the CRC density measure by the wax-immersion method; (3) the rubber content measure and calculation; (4) crack observation; and (5) the layered distribution of rubber crumbs with the computerized image scanning method. The details of the investigation can be found in  by the cThis article continues the study in  by conduSo far, most of the experiments on CRC specimens have been conducted in a laboratory. The experimental tests conducted in this article were carried out on specimens cored from a decade old in-service CRC bridge deck for the purpose of studying long-term CRC behaviors with respect to the durability and mechanical properties. Such a study has not been found in any of the public literature that has explored how well CRC withstands a decade of tear and wear with respect to its long-age effect on the mechanical properties and durability as well as to provide the technical knowledge for possible future application of CRC in concrete constructions.The primary information on materials such as CRC mix proportion, cored specimens, etc. can be found in . The CRCThe semi-circular disk bending (SCDB) experimental test is frequently used to measure the flexural tensile stress–strain response and the flexural strength of the asphalt concrete specimens. The experimental process is to apply a vertical load on the top center of the semi-circular disk specimen until fracture failure takes place and the specimen is broken into two pieces. The maximum load and deformation are recorded to obtain the stress–strain response and tensile strength. The fracture energy can also be obtained by calculating the area of the load deformation curve. The SCDB experiment originated in the category of rock mechanics in which Wei et al.  studied It is well-known that the tensile property of Portland cement concrete is obtained by the beam type of bending test. A limited number of reports have explored SCDB on Portland cement concrete. Razmi and Mirsayar  showed tThe corrosion of steel rebar in steel reinforced concrete takes place when chlorite ions react with the steel rebar. In a natural environment, the chlorite ions permeate very slowly inside concrete, and the corrosion or rust rate of rebar in concrete is generally low, taking months, years, or even decades to be observed. As such, accelerated steel rebar corrosion tests in a laboratory environment have been developed to gear up the steel-rusting speed ,20,21,22The specimens in this test are usually a steel reinforced beam. However, since only cored specimens were available in the study, the steel rebar had to be implanted by drilling a hole into a semi-circular disk CRC specimen, inserting the steel bar into the hole and using cement to “glue” the steel to the disk. In this way, six specimens were made see a,b, and 2 in hardened cement slurry. Saetta et al. [2 airflow diffusion, and temperature change in the concrete carbonation process. In addition to the experimental work, many scholars have conducted theoretical analyses to model or simulate the carbonation process in concrete for the purpose of estimating the time of carbonation [Concrete is a strong alkali material with a pH greater than 12.5, but carbon dioxide in air will slowly permeate from the surface to the interior of the concrete and react with calcium hydroxide, which results in the decrease in pH and weakens the alkaline protection of steel rebar in concrete, which is called the concrete carbonation phenomenon. Therefore, the carbonation test, which measures the carbonation depth in concrete, is considered as an important durability assessment. Houst and Wittmann  studied a et al.  establisbonation ,26,27,28The carbonation test is a relatively simple experiment that sprays a phenolphthalein indicator solution into a pre-made concrete facade along the depth direction, producing a purple-red color zone when it meets un-carbonized concrete and a colorless zone when it meets carbonized concrete. The thickness of the colorless zone is measured as the carbonation degree see . The detThis test was conducted according to the German Standard for fiber reinforced Concrete (DBV 1998) . The dimWhile the strains were recorded in the test, the corresponding bending stress was also calculated by the following equation:σB and εB represent the elastic limit strain and stress, respectively. σC and εC represent the ultimate limit strain and stress, respectively.For the purpose of estimating the bending strain energy, point B and point C were further introduced and labelled into the three curves in It can be observed in The areas under the OB section are defined as the CRC elastic strain energy AE, and the area under the BC section is defined as the CRC on-linear strain energy AP. The total strain energy (AE + AP) was used to illustrate the energy absorption capacity of CRC, and the results are tabulated in r of the CRC specimens can be deduced and expressed in terms of Equation (3):0.5 and F0 are the semi-final load and initial load (N); δ0.5 and δ0.5 correspond to the dial meter reading of F0.5 and F0, respectively. L is the distance between the pedestals of the specimen; J is the moment of inertia of the specimen section in which J = 1/12 bh3. Three corresponding calculated Er are given in The flexural modulus is an important material property in concrete pavement engineering. Following the stress–strain curves in The photo of the actual test setup given in 0 and w are the steel rebar weight before and after rust, respectively.At the completion of the test, the implanted steel bars were taken out of specimens see , washed The indoor carbonation test was conducted according to the GB-T50082-2009 standard . The corIn addition to the carbonation test on the broken CRC cored specimens, the on-site test on seven locations on the CRC deck was also carried out by drilling holes with a diameter of 15 mm and a depth of 10 mm on the deck, and the phenolphthalein indicator solution was sprayed into the holes see . Then, tThe main objective of the carbonation test is to see what the current level of the carbonation depth is in the concrete from the surface onward to the concrete inside and the possible future development. As such, many scholars have proposed theoretical models to predict the carbonation depth in the future. Among them, the two models developed by Niu  and ZhancomK is the concrete carbonation comprehensive coefficient, which reflects environmental conditions, concrete material property, and stress conditions, and the unit is mm/t0.5; t is the natural carbonation time (in year); mch is the model adjusting constant and the regression constant without stress; ck is the cement dosage influence coefficient; rk is the cement type influence coefficient; bk is the curing method influence coefficient, which is 1.0 for standard curing and 1.85 for steam curing; jk is the angular correction coefficient, 1.4 for the angular part, and 1.0 for the non-angular part; w/ck is the water–cement ratio influence coefficient; CO2k is the natural carbonation in the atmospheric environment; ek is the influence coefficient of ambient temperature and humidity; fk is the concrete quality influence coefficient; sk is the concrete stress level influence coefficient.The Niu carbonation model of concrete under stress is expressed as follows:t = 13 (it means the time of 13 years from 2006–2019); mch = 1.645; ck = 253C−0.964 in which C is the cement weight per cubic meter concrete. In the study, C = 481 kg and ck = 0.657; rk was 1.0 for ordinary cement, and 1.35 for slag cement. In this study, rk = 1. Additionally, bk = 1 and jk = 1.4. In this study, w/ck = (W/(0.3822 × C))0.5 = 1.023, where W/C = 0.4. CO2k = 1. ek = 2.564(1 − RH)RH × T0.25, and T and RH are the annual mean temperature and annual mean humidity, respectively. In this study, T = 11.6, RH = 0.62, and e =k 1.115. fk = 57.94/fcuk − 0.76 where cukf is the standard value of the compressive strength of concrete in MPa, and in this study, cukf = 40 and fk = 0.689; sk = 0.0149 + 27.729s − 62.224s2 + 57.439s3 − 18.224s4,and s = 0.8 and sk = 4.319. With all of these parameters assigned a value, the outcome of Equation (5) is: X = 10.934 mm.In this study, wK is the influence coefficient of the concrete curing condition with the outdoor being = 1.0 and indoor being = 1.87. In this study, wK = 1.0. The T and RH values were taken as given in Niu’s model: T = 11.6 and RH = 0.62. oC is the CO2 volume concentration in the carbonation environment and oC = 0.039% in this study. Again, cukf = 40 MPa in this study. t is the service time of concrete in years and t = 13. With all of the parameters assigned a value, Zhang’s model in Equation (7) yielded at X being 2.106 mm  was more than eight times that of the AE value. All indicate that the long aged CRC had good material strength, bending toughness, and large deformation properties.Observing For typical ordinary concrete pavement, its flexural elastic modulus is about 30 GPa, which is considered as “rigid”. Bai  conducteLowing the flexural elastic modulus may have a profound influence on the airfield pavement design. In the current design cases, the flexural elastic modulus is set at a default value of 36 GPa. The study conducted by Li et al. [Regarding long-aged concrete carbonation, Chen et al.  made a sThis article mainly carried out three types of experimental tests including semi-circular disk bending (SCDB) tests, carbonation tests, and electric accelerated corrosion tests on decade-old cored CRC specimens. The results can be concluded for this decade long-aged CRC specimens as follows: (1) Maintaining good material properties such as high energy absorption capacity, good flexural strength, high deformation, and low flexural tensile module; (2) good ion chloride corrosion resistance; and (3) low carbonation depth. This indicates that CRC possesses good long-aged durability that is comparable to good quality ordinary concrete. It should be mentioned that the results obtained here were obtained using a small number of samples, which did not possess any statistical significance.


Antibiotics are widely prescribed in the neonatal intensive care unit (NICU) and duration of prescription is varied. We sought to decrease unnecessary antibiotic days for the most common indications in our outborn level IV NICU by 20% within 1 year.A retrospective chart review was completed to determine the most common indications and treatment duration for antibiotic therapy in our 39-bed level IV NICU. A multidisciplinary team was convened to develop an antibiotic stewardship quality improvement initiative with new consensus guidelines for antibiotic duration for these common indications. To optimize compliance, prospective audit was completed to ensure antibiotic stop dates were utilized and provider justification for treatment duration was documented. Multiple rounds of educational sessions were conducted with neonatology providers.In total, 262 patients were prescribed antibiotics (139 in baseline period and 123 after the intervention). The percentage of unnecessary antibiotic days (UAD) was defined as days beyond the consensus guidelines. As a balancing measure, reinitiation of antibiotics within 2 weeks was tracked. After sequential interventions, the percentage of UAD decreased from 42% to 12%, which exceeded our goal of a 20% decrease. Compliance with antibiotic stop dates increased from 32% to 76%, and no antibiotics were reinitiated within 2 weeks.A multidisciplinary antibiotic stewardship team coupled with a consensus for antibiotic therapy duration, prescriber justification of antibiotic necessity and use of antibiotic stop dates can effectively reduce unnecessary antibiotic exposure in the NICU. Although neonatal sepsis is associated with both considerable mortality and morbidity, early antibiotic exposure is also associated with adverse outcomes in preterm neonates including chronic lung disease, late-onset sepsis, necrotizing enterocolitis, periventricular leukomalacia, severe retinopathy of prematurity, and poor long-term neurodevelopmental outcomes. Unnecessary antibiotic use in the NICU can lead to separation of the neonate from the parent due to NICU admission, delay in breast feeding, increased healthcare costs, antibiotic resistance, and invasive candidiasis. Finally, early antibiotic exposure is also linked to increased incidence of atopy, allergic disorders, asthma, and childhood weight gain.Antibiotics are the most commonly prescribed medication in the neonatal intensive care unit (NICU).Critically ill neonates are frequently initiated on antibiotics because of their high risk of sepsis. However, literature is limited regarding effective antibiotic stewardship strategies to reduce unnecessary antibiotic days for the most medically complex, critically ill neonate in the level IV NICU. In review of our local practices, we noted a lack of uniform duration of antibiotic therapy, inconsistent diagnostic criteria for infections, and fear of treatment failure which contributed to unnecessary antibiotic days. A multidisciplinary NICU antibiotic stewardship team was developed to address these inconsistencies and to increase awareness of the importance of antibiotic stewardship in the neonatal population. We sought to decrease unnecessary antibiotic days (UAD) for the most common antibiotic indications in our NICU by 20% within 1 year.This quality improvement project was initiated at St. Christopher’s Hospital for Children’s NICU, a 39-bed level IV regional perinatal center in Philadelphia, Pennsylvania. Approximately 250 neonates are admitted to our NICU annually, and all patients are outborn and transferred from regional NICUs. Admitted infants frequently require advanced surgical and pediatric subspecialty services.; (2) to increase awareness and engage frontline neonatology healthcare workers about NICU antibiotic stewardship; and (3) to address the need for multidisciplinary input , continuation, and duration of antibiotic use during rounds, with tremendous inter-prescriber variability. To increase awareness and engage NICU providers about antibiotic stewardship, a consensus guideline for therapy duration was developed, manual antibiotic stop dates were implemented, justification of antibiotic use was requested, and a series of educational sessions were conducted. In our level IV unit, a NICU-specific clinical pharmacist is present on rounds 5 days a week who encouraged justification and verbal timeouts during rounds. In addition, the antibiotic stewardship pharmacist provided prospective audit and feedback.Over the course of the study period, 5 specific interventions to address these drivers were implemented to achieve the primary aim. We used the Institute for Healthcare Improvement’s Model for Improvement for this initiative and plan–do–study–act (PDSA) cycles to assess our progress Fig. .15 DisIn the retrospective data review, the most common indications for antibiotic prescription were 1) rule out sepsis, (2) culture-negative sepsis, and (3) respiratory tract infection (tracheitis and pneumonia). In addition, we noted wide variation in antibiotic duration for each indication between providers. During the baseline period, treatment to rule out sepsis had a duration of 2–3 days, treatment for culture-negative sepsis had a duration of 5–14 days, treatment for tracheitis had a duration of 5–7 days, and treatment for pneumonia had a duration of 7–10 days, based on provider preference. Thus, based on this wide variation, interventions focused on the development of consensus guidelines for these  indications of antibiotic use. Available evidence was reviewed to develop appropriate therapy duration for these indications, and a consensus was determined by the division and presented during an educational conference on January 14, 2020, (Table  rule out1). This intervention began on January 1, 2020.Our retrospective analysis revealed that antibiotics were unnecessarily prolonged because there was a delay in manual discontinuation of antibiotics. Automatic duration of therapy or a hard stop on specific antibiotics were considered but could not be implemented because the electronic health record (EHR) system did not have this feature. Therefore, to avoid delay in antibiotic discontinuation, antibiotic orders were required to have a manually entered stop date , the clinical pharmacist performed a verbal time-out on rounds 24–48 hours after antibiotic initiation for every patient prescribed antibiotics. Time-outs included defining the indication for antibiotic use, appropriate duration of therapy and potential narrowing of antibiotic therapy. This process was performed daily until all questions were documented in the progress note.Several educational sessions were held to discuss consensus guidelines, to reinforce the importance of antibiotic stop dates, and to request documentation of justification of antibiotics for all the neonatology fellows, neonatology attending physicians, neonatal nurse practitioners, and nurses. Fellow educational conferences were used as opportunities for education of the neonatal fellows and attending physicians Table . In addiAntibiotic stewardship, pharmacist-driven, prospective audit and feedback began on January 14, 2020. The antibiotic stewardship pharmacist was responsible to perform a daily screen of antibiotic duration and stop dates in the EHR for any patients on antibiotics >48 hours. Antibiotic duration was considered prolonged if it was longer than the consensus guidelines. If there was prolonged antibiotic duration or was no stop date, the stewardship pharmacist called the neonatology fellow, pediatric resident physician, or advanced practitioner in the NICU to provide real-time feedback. Ultimately, the final decision for the antibiotic duration was at the primary team’s discretion.The primary outcome was percentage of patients with UADs per 2-week interval. UADs were defined as therapy duration beyond the consensus guidelines. All antibiotic orders were reviewed for compliance with inclusion of a stop date. Total number of stop dates ordered was tracked as a percentage of total number of patients initiated on antibiotics each month. For percentage of justification of antibiotic use, progress notes of only those patients who had UADs and 5 other randomly selected progress notes were reviewed retrospectively every month for documentation of why antibiotics were initiated, indication, duration of therapy, and reason therapy was longer than the consensus guidelines if there were UADs.The antibiotic stewardship pharmacist performed prospective audit and feedback for prolonged therapy duration, and the total number of feedback sessions was tracked as a percentage of total number of patients initiated on antibiotics each month. The most frequent reason that the focus group  cited to not decrease duration of antibiotics was failure of therapy. Therefore, we tracked reinitiation of antibiotics for any indication within 2 weeks of onset of antibiotic prescription as a balancing measure.2 test were performed with statistical package for social sciences using SPSS version 24 software . The outcome, process and balancing measures were displayed using statistical process control (SPC) P and X bar and S charts. QI-Macros 2020 software was used to analyze and generate SPC charts. Centerlines and 3-Δ (delta) control limits were applied when at least 8 consecutive points were above or below the center line, when 1 or more data points fell beyond the control limits, or when 6 consecutive points comprised a trend in either direction. Centerlines were adjusted based on detection of special cause signal. Ethical aspects of the interventions and studying of interventions was reviewed by local institutional review board and was exempt from consent by the Internal Review Board of Drexel University College of Medicine .Descriptive analysis was conducted for gestational age, birth weight, any antibiotic exposure and antibiotic use for each indication. A descriptive analysis and Pearson χDuring the study period, 514 neonates were admitted to the NICU. Of these, 250 were admitted during the baseline period  and 264 were admitted during the postintervention period . Charts were reviewed for exposure to at least 1 antibiotic prior to discharge, noted as antibiotic exposures. In total, 139 (55%) of 250 neonates were exposed to at least 1 antibiotic in the baseline period compared to 123 (46%) of 264 in the postintervention period. Of these antibiotic-exposed neonates, 90 (65%) of 139 in the baseline period and 86 (70%) of 123 in the postintervention period were treated with antibiotics for the most common indications  (Table After 3 PDSA cycles Fig. . SpecialWe observed special cause variation in the percentage of antibiotic stop dates used, which increased from 32% to 76% Fig. A. DocumeIn a level IV NICU with a medically complex outborn population, there can be considerable variability in antibiotic prescription duration. Therefore, standardized guidelines for antibiotic duration must be developed for appropriate antimicrobial stewardship in this unique population. Here, a comprehensive approach for antibiotic stewardship to safely reduce UAD at a level IV NICU was achieved through the creation of a NICU-specific multidisciplinary antibiotic stewardship team, standardized duration of therapy for the most common antibiotic indications, antibiotic stop dates and prospective audit and feedback. reduction of initiation of antibiotic therapy, and infrastructural antibiotic stewardship program implementation. Here, we employed 2 of these key components: reduction of the duration of antibiotic therapy through consensus guidelines and the creation of a NICU-specific antibiotic stewardship program. Reduction of initiation of antibiotic therapy, such as the use of an early-onset, sepsis-risk calculator, can reduce antibiotic exposure in infants >35 weeks gestational age in the delivery hospital setting. However, this model is less practical in our medically complex term or preterm infants, who frequently have been initiated on antibiotics by the referring institution.Although antibiotic stewardship strategies have been described in the neonatal population, literature is limited regarding stewardship initiatives specifically in NICUs that care for the most critically ill neonates. Antibiotic stewardship interventions have focused on shortening the duration of antibiotic therapy, standardized duration of therapy for common indications, and prospective audit and feedback. Here, we applied these interventions in an outborn level IV NICU with some unit-specific modifications. We encountered infrastructure difficulties in making changes in the EHR to implement automatic antibiotic stop dates. Therefore, provider education to manually enter stop dates at the time of antibiotic prescription was completed. Although manual entry of stop dates was more labor intensive, this approach was effective in reducing the percentage of patients with UAD in our NICU, as demonstrated by others, and this strategy could be utilized by other centers with similar EHR restrictions.Identification of strategies that could be both safely and effectively applied to a level IV NICU population was of particular importance in this antibiotic stewardship initiative. Several strategies have been applied to reduce the duration of antibiotics in high-acuity inborn NICUs, including antibiotic hard stops,The development of a consensus guideline for duration of therapy targeted at the indications mostly commonly used in the NICU was an important component of effectively reducing UAD. Developing evidence-based guidelines with infectious disease input was key to engage the neonatologists and create consensus. Given the clinical severity and complexity of our patients, our interventions centered on a team-based approach to provider education with real-time discussions and feedback, while affording neonatologists the autonomy to initiate and select antibiotics of their choice. Ultimately, this autonomy improved acceptance of the consensus guidelines and drove culture change. a successful component of our initiative was requesting daily documentation to justify antibiotic prescription. The clinical pharmacist conducted a verbal time-out during daily rounds if antibiotics remained necessary and discussed opportunities to narrow therapy and planned duration. This particular intervention is consistent with the tenet of accountability in the CDC Core Elements of Hospital Antibiotic Stewardship Programs. A recent multicenter national quality improvement project of the Vermont Oxford Network reduced antibiotic use by 34% with improved adherence to several of the CDC Core Elements. Similarly, we were successful in reducing the percentage of patients with UADs by 70% with our multipronged approach.Similar to central-line–associated bloodstream infection reduction initiatives,This study had several limitations. The initiative was conducted at a single-center NICU. Therefore, generalizability may be limited to level IV NICUs with a similar patient population and a full complement of resources, such as a dedicated clinical pharmacist present during daily rounds. Furthermore, the scope of this initiative was limited to the most common indications for antibiotic use. Culture-proven infection of blood and urinary tract were rare during this epoch. Our consensus guidelines focused on treatment for either culture-negative sepsis or positive respiratory cultures, which frequently reflect colonization. Further work should explore treatment duration for culture-proven infections in the most vulnerable patients with immature immune systems, especially in the first weeks after birth.A multidisciplinary antibiotic stewardship team coupled with focused interventions including the use of standardized duration of therapy, antibiotic justification, stop dates, and prospective audit and feedback can effectively and safely reduce UAD in an outborn level IV NICU. Future PDSA cycles will expand the breadth of this initiative to other antibiotic indications and will facilitate strategies that focus on reducing antibiotic initiation to further decrease UAD in our NICU.


Ordinary Portland cement (53 Grade) was mixed with fly ash, silica fume, and GGBS. Sintered fly ash aggregate (SFA) and palm oil shell aggregate (POS) were used as coarse aggregates. Hooked steel fibers and polyvinyl alcohol fibers were combined in a hybrid form to improve crack propagation properties at the initial and subsequent stages. The water-to-binder ratio was kept constant at 0.30 to 0.35 with a 1% superplasticizer. Four volume fractions of hybrid fibers  were added. In addition, XRD, SEM, EDS, and EDS mapping tests were performed to finalize the material’s chemical composition and crystalline structure. Furthermore, beams and cylinders were tested to determine the modulus of rupture, which was determined to be between 9.5 and 14 MPa by ACI code C 1609-M, and indirect tensile strength, achieved as 10 to 14 MPa by ACI code C 496-M. The researcher altered the modulus of elasticity (Ec) formula for lightweight concrete and discovered a relationship between fc’ and fcb, fc’ and fspt, and fcb and fspt. Finally, ANOVA and regression tests were run to check the significance of the experiment. The cost analysis revealed that the cost of LWHFRC increased by approximately 16.46%, while the strength increased by 55.98% compared to regular concrete.To create cost-effective structures, the modern construction industry has sought to reduce the dead load of buildings. Lightweight concrete is a quick way to reduce dead load. The current study is primarily concerned with identifying modern substitutes for coarse aggregate likely to aid in waste management and offer potential alternatives to the most exploited natural resources. According to ACI C 39-M, this study developed a novel lightweight hybrid fiber-reinforced concrete (LWHFRC) with a density of less than 1825 kg/m Advancements in expertise enhance not only human comforts but also impairment the environment. In the world, most industries are accompanied by many materials such as fly ash ,2,3,4, sSteel fiber and polyvinyl alcoholic fiber (PVA) were also used independently and combined to produce high-performance fiber-reinforced lightweight concrete by a few researchers. The researcher’s primary goal is to use an environmentally harmful material as a light component to create high-performance, lightweight concrete. However, few researchers have already developed ultra-high-performance fiber-reinforced lightweight concrete, which is most suitable for structural members such as beams, columns, floors, and precast members. However, this was very expensive in the concrete industry because most researchers did not use coarse aggregate in their ultra-high-performance concrete (UHPC). In addition, many researchers developed only lightweight concrete. We plan to create new inventive concrete that will be high-performance and lightweight with truncated cost. There are numerous benefits of lightweight structural concrete over normal-weight concrete in the construction industry, particularly in high-rise buildings. The original method of fabricating lightweight structural concrete uses lightweight aggregates instead of ordinary aggregates in concrete. Due to the insufficient resources for natural and artificial lightweight aggregates, the substitute sources for lightweight aggregates should be revealed from industrial wastes. Oil palm shell (OPS) and oil palm-boiler clinker (OPBC) are two solid wastes from the palm oil industry ,13 and aSuperior tensile strength, flexibility, toughness, and crack resistance were proven as the main properties enhanced by fiber reinforcement. Hybrid fiber-reinforced composites were renowned for further improving the properties at the early and future stages of crack and propagation. The key is to combine various beneficial properties of fiber into a single matrix, resulting in superiority in both aspects. Steel fiber and PVA fiber ,19 were The mix design is based upon ACI-213 R-03 and ACI-211.2. In this research, 20 to 50% SFA and 10 to 30% POS gave better results. The higher volume of GGBS has a tremendous role in the high strength of concrete. Finally, ANOVA and regression analyses were performed to identify the lightweight hybrid fiber-reinforced ,27,28,29The development of lightweight concrete without sacrificing performance or strength is a novel aspect of this study. This novel material alters design considerations and reduces the self-weight of the structure. This study will cover the numerous practical applications in civil engineering practices. Because of their overwhelming strength and performance, these innovative concrete composites may be used in earthquake-prone areas. Because sintered fly ash aggregate (SFA) and palm oil shell aggregate (POS) have regular and irregular shapes in structure, researchers had the brilliant idea of combining both totals with a high volume of cementitious materials without natural aggregate to achieve lightweight, high-performance concrete at a lower cost for bridge structures and high-rise building applications.3), water/cement ratio (w/c = 0.3 to 0.35), superplasticizer dosage (SP = 1%), and weight ratio of coarse lightweight aggregate to natural river sand (LWA/S = 1.5), remained constant across all mixtures. The water absorption of aggregates was determined within the mixing time, and the batch proportions were adjusted accordingly.Twenty-four mix designs with varying volumes of steel and PVA fibers were prepared to investigate the effect of steel and PVA fibers on the properties of lightweight aggregate concrete. The volume fraction of steel fibers and PVA fibers in concrete ranged from 0% to 2%. 3 are used. The properties of the materials are listed in The 24-mix design  used in this experiment is as follows. The quantity of the materials used in this experiment was calculated from that mixed design. The number of specimens in this experiment is 576 pieces divided into four series. All mixing and preparation of samples were performed at room temperature. The first series consists of a cylinder specimen (100 mm × 200 mm) for compressive strength. The second series consists of the flexural specimen (150 mm × 150 mm × 530 mm) for flexural strength, and the third series consists of a cylinder specimen (150 mm × 300 mm) for the split tensile strength of concrete. The four series consists of a cylinder specimen (100 mm × 200 mm) for the water absorption test. The volume fraction (Vf) of both the steel fiber and PVA fiber was also categorized in a hybrid form of 1% (HA series), 1.5% (HB Series), and 2% (HC Series). The amount of each material used in this experiment is shown in The fine and coarse aggregates were mixed in a concrete mixer for about 2 min before cement was added to the concrete mixtures. The ingredients were re-mixed until a uniform color was achieved. The steel fiber and PVA fiber were then gradually added to the mixture. The water had been split in half. The first half was added to the ingredients in the mixer and mixed for 2–3 min before adding the remaining water and superplasticizer. After that, the ingredients were mixed for another 2–3 min. The concrete was then poured into the molds and consolidated on a vibrator. The specimens were cured under laboratory conditions by covering them with a plastic sheet for 24 h, followed by wet curing. The effect of partial/complete substitution of coarse artificial aggregate with POS on mechanical properties such as unit weight, compressive strength, flexural strength, split tensile strength, modulus of elasticity, water absorption test, and workability test was evaluated (slump cone).After 28 days of curing, three cylindrical concrete specimens measuring 100 mm in diameter and 200 mm in height were prepared from each concrete mixture to determine the unit weight. The specimens were air-dried for 48 h before being measured to ensure uniform moisture content. The weight-to-volume ratio was expressed as the unit weight of concrete. For each mixture, triplicate measurements were taken, and the average values were reported. Workability tests such as slump, compaction factor, and vee bee consistometer were performed on various lightweight concrete and lightweight hybrid fiber-reinforced concrete mixtures. The slump test was carried out following ACI-C143/C143M 12. A 300 mm high frustum of a cone with a leveled surface was placed in the mold. The concrete was filled in three layers, with each layer tamped 25 times with a 16 mm steel rod with a rounded nose. The top was not level, and the mold was firmly pressed against the slab base. The mold was gently lifted, and the decrease in concrete height was measured and recorded in The compacting factor test was performed following ACI-C143/C143M-12 using a compacting factor test apparatus. The top hopper was filled gently with concrete, while the bottom hopper was kept closed. The top hopper was opened, and the concrete fell from the upper to the lower hopper and then from the lower hopper to the mold. The vee bee time apparatus measured the workability of concrete as per ACI-C143/C143M-12. The time required for the complete remolding of concrete was measured. The vee bee times are tabulated in At 28 days of curing, the cylinder samples were tested for water absorption capacity. First, the dry masses of concrete specimens were saturated in the water basin for 28 days in the methodology. Following that, the saturated concrete samples were reweighed, and the soaked mass of the samples was subtracted from the dry mass to determine the mass of water absorption and thus the percentage of water absorption relative to dry mass. The rates of water absorption by the sample cylinder specimen are shown in The cylinder compressive strength test was performed on the 100 mm diameter and 200 mm high cylinder specimens at the ages of 7 and 28 days, respectively, using a 100-ton capacity compression testing machine following ACI-C39/C39M-20 .The split tensile strength test is an indirect tensile strength test for cylindrical specimens. Splitting tensile strength tests were performed at 28 days for concrete cylinder specifications of 150 mm in diameter and 300 mm in length, using an ASTM-C496 . Figure spt = splitting tensile strength of the specimen (MPa);fP = maximum load applied to specimen (N).l = length of the specimen (mm).d = cross-sectional diameter of the specimen (mm).The splitting tensile strength was estimated after 28 days by using the following relationship:A flexural strength test was performed on the 150 mm × 150 mm × 530 mm beam specimen at 28 days using a 50-ton capacity universal testing machine by subjecting the specimen to four-point bending to determine the flexural strength as per ASTM C 1609 M. The flexural strength was calculated using the result analysis and test configuration formula. 3. The unit weight of concrete from the C1 to C3 series was used to replace NCA, SFA, and POS completely. However, the unit weights of C2 and C3 fell within the ACI 213 R-03 lightweight concrete criteria. The E1 to E6 series were also within the light concrete unit weight range of 1819–1828 kg/m3.As a substitute for SFA, the unit weight of concrete specimens prepared with varying amounts of POS is used. In Fresh concrete is usable when it can be easily transported, placed, compacted, and finished without segregation. Slump tests were performed on concrete with lightweight aggregate from E1 to E6 as lightweight concrete (LWC) and HA to HC series as lightweight hybrid fiber-reinforced concrete (LWHFRC) to determine comparable workability. Before the fresh concrete specimens were cast in the molds, four batches of all concrete types were tested for workability. At 28 days of curing, the cylinder samples were tested for water absorption capacity. First, the dry masses of concrete specimens were saturated in a water basin for 28 days. Following that, the saturated concrete samples were reweighed. Finally, the soaked mass of the samples was subtracted from the dry mass to determine the mass of water absorption and, thus, the percentage of water absorption relative to dry mass. (a)E Series (LWC)3) set by ACI-213 R-03 and developed a strong bond between irregular triangular coarse aggregate (POS) and regular circular coarse aggregate (SFA) at a 1:4 ratio (POS: SFA). (b)HA Series (1% Hybrid Fiber)At the age of 28 days, the compressive strengths (HA1-HA6) of LWHFRC (1% hybrid fiber) were increased by 55.99%, 57.96%, 64.44%, 57.48%, 69.97%, and 47.50%, respectively, when compared to control concrete (C1). At 28 days, the compressive strength of 1% steel fiber (HA5) was 60.425 MPa, nearly as high as the other results. (c)HB Series (1.5 % Hybrid)At the age of 28 days, the compressive strengths (HB1-HB6) of LWHFRC (1.5% hybrid fiber) were increased by 55.99%, 56.24%, 67.59%, 78.58%, 86.34%, and 23.42%, respectively, when compared to control concrete (C1). At 28 days, the compressive strength of 1.5% steel fiber (HB5) was 66.245 MPa, nearly as high as the other results in this series. (d)HC Series (2% Hybrid)At the age of 28 days, the compressive strengths (HC1-HC6) of LWHFRC (2% hybrid fiber) were increased by 55.99%, 56.24%, 58.81%, 75.63%, 95.29%, and 5.85% (-ve), respectively, when compared to control concrete (C1). At 28 days, the compressive strength of 2% steel fiber (HC5) was 69.425 MPa, nearly as high as other results in this series. At 7 and 28 days, the split tensile strength of the concrete specimens was determined.The concrete specimens’ flexural strength was measured after 7 and 28 days. Finally, we concluded that adding a certain percentage of fiber in concrete increased the specimen’s compressive, tensile, and flexural strength since the randomly oriented fibers arrest a microcracking mechanism and limit crack propagation, thus improving stability and elasticity.According to ACI 318-19, the modulus of elasticity was calculated by the following formulas:We concluded from We also concluded from From From From (a)XRD ReportThe SFA peak was higher than fly ash and silica fume peaks ,37. Figu(b)EDS AnalysisAccording to the EDS analysis report from (c)SEM ReportThe SEM image in (d)SEM Report—EDS mappingMorphological characteristics were found by using the JEOL-IT-100 instrument. It gives the direct result of the significant depth of field ,37. Figup-value is less than 0.05. The bulk density ANOVA analysis [The ANOVA and regression analysis confirmed whether our findings were significant or not. The summary of ANOVA and regression analysis are shown in analysis ,39,40 foRegression analysis revealed significant regression for bulk density, water absorption, and slump. Nonetheless, within the lightweight hybrid fiber-reinforced concrete group, only the deterioration for compressive strength was not significant . We concluded that regression analysis was substantial for bulk density, water absorption, and the slump in lightweight hybrid fiber-reinforced concrete. Both ANOVA and regression analysis revealed that the compressive strength of the lightweight hybrid fiber-reinforced concrete was not significant (LWHFRC). As a result, the experimental results matched the ANOVA and regression results.3 for all three stages of hybrid fiber-reinforced lightweight concrete, which met the ACI 318-19 light concrete criteria. The water binder ratio remained constant throughout all three stages at 0.30 to 0.35. . The average slump flow diameter is around 51 cm. The average slump height is 24.2 cm for lightweight concrete without fiber (E3). The slump value decreases gradually while the fiber percentage increases.The unit weight of concrete was around 1825 kg/mThe compressive strengths (E1–E6) of LWC at 28 days were increased by 80.44%, 61.53%, 55.99%, 11.83%, 18.78%, and 4.93%, respectively, when compared to control concrete (C1).Similarly, at 28 days, the compressive strengths (HA1–HA6) of LWHFRC were increased by 55.99%, 57.96%, 64.44%, 57.48%, 69.97%, and 47.50%, respectively (1% hybrid fiber). At 28 days, the compressive strengths (HB1-HB6) of LWHFRC (1.5% hybrid fiber) increased by 55.99%, 56.24%, 67.59%, 78.58%, 86.34%, and 23.42%, respectively. At the age of 28 days, the compressive strengths (HC1–HC6) of LWHFRC were increased by 55.99%, 56.24%, 58.81%, 75.63%, 95.29%, and 5.85% (-ve), respectively (2% hybrid fiber).The strength of lightweight concrete without fiber increased by 55.98%, while the cost of lightweight concrete increased by approximately 16.46%, and unit weight decreased by about 26.67% compared to normal concrete without mineral admixture.The significant effect of replacing 50% of the GGBS with cement played an essential role in increasing compressive strength.SFA outperforms POS and NCA in compressive strength. However, the workability of SFA is lower than that of the other two aggregates. The researchers also discovered that the 90% SFA and 10% POS mixture and the 80% SFA and 20% POS mixture had higher strength and unit weight, meeting lightweight structural criteria.The series of 2% steel fiber and 0.5% PVA fiber had higher compressive strength than the other percentages. The compressive strength of the 2% hybrid fiber (1.5% steel + 0.5% PVA) was higher.In the flexural strength test of the beam, PVA fiber deflected more than steel fiber. As a result, the modulus of rupture of a steel fiber beam was higher.1.0175, R2 = 0.8426.The relationship between the beam flexural strength, and the cylinder split tensile strength of LWHFRC was fcb = 0.9782 fspt0.8103, R2 = 0.8875.A relationship was formed between the cylinder split tensile strength and compressive strength of LWHFRC: fspt = 0.4309 fc’0.9062, R2 = 0.868.The LWHFRC beam flexural and compressive strengths formed a relationship fcb = 0.2984 fc’0.5, R2 = 1.The cylinder modulus of elasticity and LWHFRC compressive strength formed a relationship E = 3.3525 fc’The ACI-318-19-Ec lightweight concrete equation matched the current lightweight hybrid fiber-reinforced concrete study.Mineral admixtures improve the structure of the aggregate’s contact zone, resulting in a better bond between aggregates and cement paste, as demonstrated by the SEM micrograph and XRD report.ANOVA and regression analysis produced the most significant results with 5 to 10% error.


MET exon 14 skipping mutations (METex14). However, the emergence of acquired resistance to capmatinib/tepotinib is almost inevitable partially due to D1228X or Y1230X secondary mutations of the MET. In this study, we explored agents that are active against both D1228X and Y1230X MET to propose an ideal sequential treatment after capmatinib/tepotinib treatment failure in NSCLC patients with METex14.Capmatinib and tepotinib are guideline-recommended front-line treatments for non-small-cell lung cancer (NSCLC) patients with METex14 plus MET D1228A/Y secondary mutations. The screen revealed four-candidate type II MET-TKIs . Therefore, we performed further growth inhibitory assays using these four MET-TKIs plus cabozantinib and merestinib in Ba/F3 cells carrying MET D1228A/E/G/H/N/V/Y or Y1230C/D/H/N/S secondary mutations. We also performed analyses using Hs746t cell models carrying METex14  with/without D1228X or Y1230X in vitro and in vivo to confirm the findings. Furthermore, molecular dynamics (MD) simulations were carried out to examine differences in binding between type II MET-TKIs.The inhibitory effects of 300 drugs, including 33 MET-TKIs, were screened in Ba/F3 cells carrying All 6 type II MET-TKIs were active against Y1230X secondary mutations. However, among these 6 agents, only foretinib showed potent activity against D1228X secondary mutations of the MET in the Ba/F3 cell and Hs746t in vitro model and Hs746t in vivo model, and CEP-40783 and altiratinib demonstrated some activity. MD analysis suggested that the long tail of foretinib plays an important role in binding D1228X MET through interaction with a residue at the solvent front (G1163). Tertiary G1163X mutations, together with L1195F/I and F1200I/L, occurred as acquired resistance mechanisms to the second-line treatment foretinib in Ba/F3 cell models.METex14 after campatinib/tepotinib treatment failure by secondary mutations at residue D1228 or Y1230.The type II MET-TKI foretinib may be an appropriate second-line treatment for NSCLCs carrying The online version contains supplementary material available at 10.1186/s13045-022-01299-z. MET exon 14 skipping mutations (METex14). These drugs yielded progression-free survival of 5.4–12.4 months in clinical trials [Two type Ib MET-tyrosine kinase inhibitors (TKIs), capmatinib and tepotinib, were recently approved for the treatment of non-small-cell lung cancer (NSCLC) patients carrying MET-TKIs are usually classified into two types based on their binding mode to MET . Type I Currently approved type Ib MET-TKIs, capmatinib and tepotinib, interact with the residue Y1230 residue; thus, it is reasonable that secondary mutations at Y1230 cause resistance to these drugs. In addition, through analyses of clinical specimens obtained from patients who acquired resistance to type I MET-TKIs, the emergence of secondary mutations at the D1228 position was also found to be frequent after capmatinib/tepotinib treatment failure –13.50 values for type II MET-TKIs than cancer cells with Y1230X through in vitro experiments [As a potential second-line treatment, type II MET-TKIs that bind to the inactive form of MET have been suggested in previous studies to overcome many of the secondary mutations that emerge after front-line capmatinib/tepotinib monotherapy –17. Altheriments , 16, 24.A total of 33 MET-TKIs and other receptor TKIs, multi-kinase inhibitors and cytotoxic inhibitors were evaluated in the present study. A SCADS inhibitor kit was provided by the Screening Committee of Anticancer Drugs supported by a Grant-in-Aid for Scientific Research on Innovative Areas, Scientific Support Programs for Cancer Research, from the Ministry of Education, Culture, Sports, Science, and Technology of Japan. In addition, we purchased almost all commercially available MET-TKIs which are under clinical development or were developed clinically in the past. The features of TKIs evaluated in the present study are summarized in the Additional file METex14 and MET amplification, was purchased from the American Type Culture Collection . Gp2-293 packaging cells were purchased from Takara .The interleukin-3 (IL-3) dependent murine pro-B cell line (Ba/F3) and myelomonocytic, macrophage-like, BALB/c mouse leukemia cells (WEHI-3) were provided by the RIKEN Bio Resource Center . WEHI-3 secretes IL-3 into the medium and was thus used as a source of IL-3 for Ba/F3. The human gastric cancer-derived Hs746t cell line carrying 2. Gp2-293 cells and Hs746t cells were maintained in Dulbecco’s modified Eagle’s medium (DMEM) containing 10% FBS and 1% PS at 37 °C in an incubator in a humidified atmosphere containing 5% and 10% CO2, respectively.Ba/F3 cells were maintained in RPMI-1640  medium supplemented with 10% fetal bovine serum (FBS)  and 1% penicillin–streptomycin (PS)  at 37 °C in an incubator in a humidified atmosphere containing 5% COMETex14 and MET-TKI-resistant Ba/F3 clones (METex14 plus D1228A/E/G/H/N/Y or Y1230C/D/S/N/H) were established in our previous study [A Ba/F3 clone with us study . These MMETex14 plus one of the secondary mutations (D1228H/N/V/Y or Y1230H) as described previously [METex14 was used as a template, and the retroviral vector constructs encoding METex14 plus point mutations (D1228H/N/V/Y and Y1230H) were generated by a Prime STAR mutagenesis basal kit (Takara). All mutations were confirmed by direct sequencing. The viral particles were generated by co-transfection of these retroviral vector and the pVSV-G vector (Clontech) into Gp2-293 cells and were added to Ba/F3 and Hs746t cells. Ba/F3 cells and Hs746t cells infected with the retrovirus were collected using green fluorescence protein (GFP)-based fluorescence-activated cell sorting by a BD FACS Aria cell sorter .Transfection was applied to Ba/F3 parental cells and Hs746t cells to generate in vitro models of eviously . Briefly3 cells were seeded per well of 96-well plates. After 24 h, MET-TKIs were added at indicated concentrations. After a 72-h incubation, 10 μl of Cell Counting Kit-8 solution  was added to the wells, and the plates were incubated for an additional 3 h. The absorbance at 450 nm was read using a multiplate reader . The percentage of viable cells was evaluated and compared with that in DMSO-treated control samples. The half-maximal inhibitory concentration values (IC50) were determined by fitting a nonlinear regression curve to a variable slope model with normalized response in GraphPad Prism version 8 .A total of 3 × 104 cells were plated in 96-well plates in the presence of foretinib at indicated concentrations. The medium containing individual MET-TKIs was replaced once weekly for three weeks. When cell growth was detected macroscopically, total RNA was isolated from the resistant clones using an RNeasy Plus Mini kit . Then, RNA was converted to cDNA using ReverTra Ace . The MET gene was sequenced from exon 15 to exon 21 using Genetic Analyzers 3130 or 3500XL .MET-TKI-resistant clones were generated by ENU mutagenesis as described previously . Ba/F3 cBa/F3 and Hs746t cells were treated with MET-TKIs at the indicated concentrations for 3 h. The cells were then washed twice with PBS and resuspended in lysis buffer. Lysates were quantified using a BCA protein assay , and proteins were electrophoresed and transferred to polyvinylidene difluoride membranes. Immunoblotting was performed with antibodies purchased from Cell Signaling Technology  according to the manufacturer’s instructions  reached 0.75 cm3, the mice were randomized to three groups and treated once daily with foretinib, cabozantinib, and vehicle via oral gavage. Foretinib and cabozantinib were first dissolved in DMSO and then diluted with ddH2O to a dose of 16.36 mg/kg and 12.3 mg/kg, respectively. The final concentration of DMSO was 2%. The mixture of ddH2O containing 2% DMSO was used as a vehicle. Tumor size and body weight were monitored every two days and twice weekly, respectively, until the average tumor volume reached 2.0 cm3. Statistical analysis was performed using Kruskal–Wallis test with Dunnett’s multiple comparison test.An in vivo study was performed at Kindai University in accordance with the guidelines of the Institutional Animal Care and Use Committee of Kindai University. Five-week-old nude male mice were purchased from CLEA Japan , and 1.0 × 10Formalin-fixed, paraffin-embedded tissue Sects. (4-μm thick) obtained from in vivo experiments were deparaffinized and heated in Antigen Retrieval Citrate Solution, pH 6 . The tissue sections were treated with Protein Block Serum-Free (Dako) and then incubated with a phospho-MET antibody (#3077)  and then Histofine Simple Stain MAX PO(R) . Peroxidase activity was visualized via the DAB reaction using a reagent from Dako. The sections were counterstained with hematoxylin.Using MolDesk Basic ver. 1.1.77 , molecular dynamics (MD) simulations of MET-TKIs and the MET protein were performed. Co-crystal structures of wild type of MET kinase domain in complex with merestinib, foretinib, altiratinib (type II kinase inhibitors) or MET D1228V with foretinib were downloaded from The Protein Data Bank, respectively . The retrieved protein–ligand structures were processed by MolDesk Basic ver. 1.1.77  (1): addition of all hydrogens and deletion of all water molecules for protein. (2) Addition of all hydrogens and partial charge for ligand was performed using MOPAC7 AM1 BCC of MolDesk Basic. A docking pocket of each ligand for c-Met kinase domain was generated specifying the site where the MET inhibitor was originally bound. For foretinib and merestinib, the structurally determined ligands within 6sd9, 4eev were used. For cabozantinib, 3D structure file  was downloaded from PUBchem. Molecular docking simulation of foretinib, cabozantinib and merestinib with MET kinase domain (wild type or D1228V mutant) were carried out and docking score and RMSD were calculated using the sievgene of MolDesk Basic. Ligands (foretinib and merestinib) were used from co-crystal structure model within the above files. PyMOL (ver 2.5.2) was used to draw the 3D structure and to measure the distance between two points.https://pubmed.ncbi.nlm.nih.gov/) was used to review previous publications and summarize the on-target mechanisms of resistance to type I MET-TKIs in NSCLC patients carrying METex14 [PubMed  are summarized in Fig. METex14 plus Y1230X mutations  or Y1230H secondary mutations into Hs746t cells to generate in vitro models with a secondary mutation in a part of the MET protein (with exon 14 skipping). We selected these four variants based on their frequencies in clinical samples  at the Y1230 position using th K1110 , 30, secth K1110 , 31. ThrAs one of the reasons for the different efficacies against D1228X secondary mutations between foretinib and other type II MET-TKIs, in this study, we found that the distances between V1228 and foretinib were larger than the distance between V1228 and cabozantinib/merestinib Fig. . In geneMET [The safety and tolerability of foretinib have been confirmed in two phase I trials (Additional file MET . ConsideIn this study, we explored adequate second-line MET-TKIs that show high activity against secondary mutations that emerge after treatment failure of two approved type Ib MET-TKIs, capmatinib and tepotinib. We showed that many type II MET-TKIs can overcome Y1230X mutations; however, our results suggest that cabozantinib and merestinib, which are currently under clinical development, may be insufficient to overcome resistance conferred by D1228X secondary mutations. On the other hand, foretinib showed potent activity against both D1228X and Y1230X secondary mutations.Additional file 1:Table S1. A list of tyrosine kinase inhibitors used in this study. Table S2. A list of antibodies used in this study. Table S3. Results of drug screening other than tyrosine kinase inhibitors. Table S4. Type II MET-TKIs evaluated in this study. Table S5. Clinical information of two phase I studies of foretinib. Table S6. Clinical information of five phase II studies of foretinib.Additional file 2: Fig. S1. Drug screening against MET D1228A/Y using a drug library. Fig. S2. Summary of growth inhibitory curves of eight MET-TKIs for Ba/F3 cells with each MET mutation. Fig. S3. Evaluation of the effects of secondary mutations on sensitivity to MET-TKIs using the Hs746t cell line. Fig. S4. Analysis of the secondary resistance mutations against 1st line foretinib. Fig. S5. Growth inhibition curves for ENU-derived foretinib resistant Ba/F3 cells carrying MET secondary mutation. Fig. S6. Comparison of the structures of each type II MET-TKI. Fig. S7. Summary of growth inhibitory curves of three MET-TKIs for Ba/F3 cells with MET tertiary mutations. Fig. S8. Structure of MET in the DFG-in and DFG-out conformations.


South Africa possesses the largest anti-retroviral therapy (ART) program in the world, but the path to this record was dramatic. There is scarce literature employing a comprehensive framework to explain this achievement and inform epidemic responses. This paper applies the Advocacy Coalition Framework (ACF) to analyse the interactions among diverse actors, institutions and networks that were associated with the AIDS policy change in South Africa. Post-apartheid, HIV/AIDS and AIDS-related mortality were serious public health problems. At the time, the discernible coalitions in the HIV/AIDS policy subsystem were the pro-science coalition and AIDS dissidents. In view of the availability of compelling scientific evidence on the pathogenesis of HIV/AIDS, the clinical usefulness of ART, the availability of funding for national ART roll-out, strong global advocacy to reduce the cost of ART, all of these in an era when access to adequate HIV treatment/care was increasingly considered a human right, the environment to establish an appropriate HIV/AIDS policy for the country was conducive. However, AIDS dissidents dominated the policy agenda via their control over key institutions, the use of various dimensions of power, biasing evidence to inform policy, and promoting the activities of strong interest groups that were not in support of ART. National ART roll-out finally emerged as a political priority because of external shocks (on the AIDS policy subsystem) which disfavoured the dominant coalition. As in this important experience in the history of HIV treatment, stakeholders involved in epidemic response tend to engage in intense ideological conflicts. An adequate appraisal of the outcomes of these conflicts in terms of population health gains and adopted public health and social measures to control epidemics would require the supplementation of complex system thinking with relevant public policy concepts, notably power dimensions, governance, emergence of global health networks and evidence use in policy. The advent of antiretroviral therapy (ART) has greatly revolutionized HIV treatment and care and over the years, tremendous efforts to expand ART coverage have been observed in resource-limited settings . In sub-The ACF proposes that a policy agenda or policy change is the result of competition among coalitions that exist within policy subsystems. A coalition comprises actors, institutions, networks or interest groups that share common fundamental belief systems regarding issues within a subsystem , 19. BelThere were two discernible coalitions in the country's AIDS policy subsystem post-apartheid. AIDS dissidents comprised the minority (yet dominant) coalition. Their deep core beliefs were that, HIV is harmless and does not lead to AIDS. They also believed symptoms of AIDS were consequent to poor nutrition, poverty, and ART. They strongly discouraged ART by focusing on its toxic effects. Their policy core beliefs were that improvements in nutrition with food such as garlic, lemon juice, and beetroots could serve as treatment for HIV/AIDS. Within the country, denialists also promoted scientifically indefensible policies by scaling-up traditional remedies, various chemicals, and other alternative therapies. Members of this coalition included important members of the government like Thabo Mbeki (second post-apartheid president) and some ministers, notably, Tshabalala-Msimang . At the international level, members included renowned scientists (like Peter Duesberg and David Rasnick) , anti-AIth international AIDS conference had views that matched with this coalition [The other coalition comprised advocates of science-based medicine. Their deep core beliefs were that HIV infection is caused by the virus called HIV, which is transmitted via blood and other body fluids and without appropriate treatment HIV would lead to AIDS. Their policy core beliefs were that ART had proven efficacy in the prevention and treatment of HIV and should therefore be prescribed to persons living with HIV/AIDS. They fought for the national roll-out of ART in order to reach out to the thousands of people living with HIV/AIDS and to prevent maternal to child transmission of HIV. The members of this coalition included civil society groups such as Treatment Action Campaign (TAC), some government officials like Jeff Radebe and Madlala-Routledge , scientists like William Makgoba , the media and the South African Medical Association. At the international level, members included scientists, AIDS activists, international associations of persons living with HIV/AIDS, popular media. Several delegates at the 16oalition .The first AIDS-related deaths occurred in 1981 and 1982, but little attention was accorded to the epidemic over the following decade . In 1992From the end of 1994 to 1997, a series of events heralded AIDS denialism. First, in 1994, there was a scandal  involving Dlamini-Zuma who was also opposing the introduction of ART for prevention of mother-to-child transmission of HIV. The motives for this minister's change from an advocate of the national AIDS plan to an opponent of ART were unclear. Then, in 1997, a chemical called virodene was being promoted by a university scientist, Olga Visser and Mr Mbeki (then Deputy President), with the latter declaring over media that he felt privileged to have encountered HIV-infected persons who admitted feeling better with virodene. This could only have encouraged more infected persons to take virodene and illustrates how ideological power had been used by Mr Mbeki to favour untested therapies in place of ART. However, the use of virodene was not approved by the South African Medical Control Council which, legitimately, was the drug regulatory authority of the country.The coalition of AIDS dissidents became more evident in 1999. That year, on becoming the head of state, Mr Mbeki formed an association of AIDS dissidents. He informed the National Council of Provinces that Zidovudine (AZT), an antiretroviral drug, was toxic and he wanted clarifications on the use of the drug. In 2000, he set-up a Presidential AIDS Advisory Panel . With reference to the ACF, it is not clear whether Thabo Mbeki wanted to play the policy broker (which is less plausible since he was clearly an AIDS dissident) or if it was a genuine policy-oriented learning process across coalitions although there were no evident shifts in belief systems. Whichever the scenario, the creation of this panel by the president may have been consequent to Luke's second dimension of power: it was alleged that the creation of the panel was enhanced by advice from foreign dissidents  .In 2003, after a court ruling against Tshabalala-Msimang who had been resisting ART roll-out, the South African cabinet announced its plan to roll out ART in the public health sector. However, in 2005, Dr William Makgoba, an immunologist who was president of the national medical research council (MRC) and an advocate of evidence-based medicine, left the MRC. This could be interpreted as an external shock that disfavoured advocates of science-based medicine (to which Makgoba belonged), as the MRC became less independent. A similar weakening occurred in the Medical Control Council (MCC), but the reason for this is unclear. AIDS dissidents in the government then took advantage of these external shocks to foster technical-bias in evidence as a basis for AIDS policymaking, since the country's relevant regulatory institutions (MRC and MCC) had been compromised. For example, in 2005, government supported a claim that trials on micronutrients produced by Rath Foundation  had revealed that high doses of vitamins reversed the course of HIV/AIDS . As a reIn November 2005, the Treatment Action Campaign (TAC) and the South African Medical Association (SAMA) jointly filed court papers against the Minister of Health , Matthias Rath and several other AIDS denialists. They were against denialists distributing untested products in the country . After tThe Toronto International AIDS Conference of 2006 hugely condemned Mr Mbeki and Tshabalala-Msimang over the country's AIDS policy. This, among others, prompted revolts in the African National Congress (the ruling party in South Africa since the end of apartheid) and the cabinet of South Africa , 25 woulet al. had long encouraged the application of the framework on a wider scope [Knowledge of the actors, context and processes involved in the AIDS policymaking is key to understanding the direction of policy change. Nonetheless, historical analyses highlighting the variety of instruments that could be employed by the actors is also fundamental to elucidate the drivers of policy change. The ACF is generally applied to domestic contexts, as its initial construct was designed to understand how different actors worked together through the policy process to implement change in the United States environmental policy . In thiser scope  even thoPost-apartheid and for over a decade, high rates of HIV/AIDS and AIDS-related mortality constituted serious public health menaces in South Africa, even though there was a conducive environment to develop an appropriate HIV/AIDS policy. This conducive environment was due to the availability of compelling scientific evidence on the pathogenesis of HIV/AIDS and the benefits of ART, availability of funding for national ART roll-out, strong global advocacy to reduce the cost of ART , all of From another perspective, the response to the public health menace posed by HIV/AIDS in South Africa could be regarded as the result of the way the menace was framed by diverse actors and institutions, especially those that had access to some form of power. Two important examples are worth citing. First, it was suggested that Mr Mbeki framed the menace and the proposition of rolling-out ART as the products of conspiracies spearheaded by Western societies and he therefore countered every effort to roll out ART in his high authority as president . In lineet al. conducted a comprehensive literature review to comparatively assess the response to the SARS, Zika and Ebola outbreaks. Although they did not apply a comprehensive framework such as the ACF to analyse the available evidence, the themes that emerged from the review revealed that epidemic response tends to be political, public health measures to control epidemics are not necessarily informed by credible evidence (i.e. evidence could be biased at different levels), response strategies tend to be determined by actors or institutions that have some form of power [Even though the ACF is one of the most comprehensive frameworks for explaining policy change, failure to borrow from other public policy concepts such as governance and policy implementation, dimensions of power, framing of global health issues, evidence use in policy and emergence of global health networks to supplement the ACF would lead to suboptimal appraisal of the AIDS policy change and misinformation of policies adopted to response to infectious disease epidemics. Such complex system systems thinking approach should not only serve to better understand policymaking processes, but should also provide insights into the potential downstream effects of adopted policies and strategies to appropriately fine-tune them for population health gains. Kapiriri of power . These oThe main limitation of this paper is that the historical analysis was not supplemented with evidence from key informant interviews and other qualitative data collection methods. This could have provided more perspectives  on the policy change process and how the AIDS policy change was embraced by key stakeholders involved in the management of the pandemic.