The purpose of this paper is to present a new approach for the modelling of post-tensioned beams with calibration of the FE model to experimental results until the load capacity and post-critical state are reached. Two post-tensioned beams with different nonlinear tendon layouts were analysed. Material testing for concrete, reinforcing steel and prestressing steel was performed prior to the experimental testing of the beams. The Hypermesh program was used to define the geometry of the spatial arrangement of the finite elements of the beams. The Abaqus/Explicit solver was used for numerical analysis. The concrete damage plasticity model was used to describe the behaviour of concrete with different laws of elastic–plastic stress–strain evolution for compression and tension. Elastic-hardening plastic constitutive models were used to describe the behaviour of steel components. An effective approach to modelling the load was developed, supported by the use of Rayleigh mass damping in an explicit procedure. The presented model approach ensures good agreement between numerical and experimental results. The crack patterns obtained in concrete reflect the actual behaviour of structural elements at every loading stage. Random imperfections found during experimental studies on the results of numerical analyses were also discussed. Prestressed elements are successfully used worldwide to obtain longer spans, higher load capacities and to reduce the dead weight of structures. However, the most important factor for assessing the safety of structures is to understand the behaviour of materials and their properties, especially in accidental situations. The results of the behaviour analysis of structural elements can be obtained during experimental studies or predicted in advanced modelling using the finite element method (FEM). Even the most detailed numerical modelling cannot be treated as a relevant result. It should be calibrated with experimental tests prepared for structural element geometry, material properties and loading conditions.Prestressed structures have been studied by many researchers, and their approaches to verifying the behaviour of structural elements are different and apply to different types of elements.There are several published works aimed at verifying the behaviour of structural elements under the action of prestressing force on the basis of experimental studies. Noble et al.  studied Some of the work was aimed at confirming that the new theoretical approaches lead to a good agreement between the results of analytical and experimental studies. Fu et al.  developeSeveral authors have calibrated the FEM results using experimental investigations or empirical formulations. There are various modelling techniques to model prestressed concrete elements, either 2D or 3D. In the publications, reinforcing steel bars are often modelled as truss elements (T3D2) embedded in the concrete material. Tendons are usually defined as truss elements, 2-node beam elements (B31) or solid elements (C3D8). Approaches to modelling stress–strain relationship for structural materials also differ. Some researchers do not include tension stiffening for concrete in the analysis and some of them do not consider the plastic hardening of steel.Kang et al.  studied e et al.  investigg et al.  verifiedg et al.  developeand Hong  studied g et al.  analysedo et al.  developeFEM models are also used to verify the local behaviour of different parts of a prestressed structure in the event of their actual failure in order to investigate the cause of the loss of load capacity.Chrościelewski et al.  investigThe following observations emerge from the bibliography review. Combined experimental studies and finite element method modelling for post-tensioned structures are carried out by relatively small group of researchers. Tests and analyses of post-tensioned beams are usually limited to a straight tendon route. Comparative analysis of the behaviour of post-tensioned beams with different curvilinear tendon systems in combined experimental studies with numerical modelling were not the subject of research. The approach to the creation of finite element meshes is similar for all material components. However, concrete is most often modelled as a solid element, the anchorages of the tendons are modelled in a simplified way as flat elements and the reinforcing bars are modelled as truss elements in a 2D plane or in 3D space. Due to the approach to modelling adopted in other publications, the local loss of concrete stiffness caused by the specific location of reinforcing bars, especially stirrups, was not taken into account in the modelling of crack propagation in concrete. Damage analysis is usually performed with a concrete damage plasticity (CDP) material model implemented in Abaqus. However, no numerical analyses take into account the damage of concrete that is already under compression from the beginning of the plastic hardening phase. In addition, no detailed description of the development of concrete damage in particular deformation phases of post-tensioned beams is provided, which is important for understanding the behaviour of beams under the influence of external loads.The aim of this article is to present a new approach to the modelling of post-tensioned beams with a detailed calibration of the FEM model to the experimental results until the load capacity and post-critical state are reached. Two post-tensioned beams with curvilinear systems of tendons with different eccentricities were experimentally tested. As part of the experimental studies, strength tests of concrete, prestressing steel and reinforcing steel bars were also performed. The finite element method for beam models was developed using Abaqus/Explicit approach. Hypermesh was used to define the finite element mesh. A spatial model of the entire beam was developed without applying symmetry conditions. Hexahedral finite elements were used to model all construction materials. The finite elements of the curvilinear tendons and all reinforcing bars were surrounded by the finite elements of the concrete. The anchorages were modelled as multi-segment steel blocks. Appropriate contact conditions of finite elements for concrete with lateral surfaces of finite elements for all steel structural elements were also modelled. The concrete damage plasticity model was used to describe the behaviour of concrete. A four-phase model of stress–strain evolution for compression and a three-phase model for tension was proposed. These models included an extended range of damage description from the onset of plastic hardening in compression and in the range of constant residual stress both in compression and tension. The method proposed in the papers of Cichorski and Stolarski ,24 and S2, the characteristic tensile strength declared by the manufacturer was Two post-tensioned beams were designed. Their cross-section size was 150 mm × 220 mm from C40/50 designed concrete class. Both beams were 3.2 m long. Main prestressing reinforcement was assumed as a single-strand 7-wire tendon with a 15.2 mm diameter and a total cross-section of 139 mmMono-strand TTM 1E15 anchorages were used in both experimental beams, Additionally, beams were reinforced with steel reinforcing bars. Two 10 mm diameter bars were located in both the upper and lower parts of the section. The cross-sectional area of these reinforcing bars was designed as minimum reinforcement area required to control cracking. Both post-tensioned beams were designed in a such a way that the ultimate load capacity was determined by the strength of the concrete compression zone. Shear capacity was increased by stirrups of 6 mm diameter at the 60 mm spacing in the support zone and then with 105 mm spacing within the central part of the beam. At the anchorage zones, spiral reinforcement and additional stirrups were provided according to the European Technical Approval of the manufacturer anchorages, Tension Technology Martin S.r.l. . ReinforDuring concreting of the beams, 5 samples of 150 mm × 150 mm × 150 mm concrete cubes were taken for compressive strength test according to PN-EN 206 + A1:2016-12 .On the 28th day, 2 concrete samples were tested, the formwork of the beams was removed, and the tendon was prestressed to the first level of prestressing force of 158 kN.On the 45th day, i.e., on the day of beam testing, the concrete strength of 3 samples was checked and the tendon was prestressed to the second level of prestressing force of 206.1 kN.The machine controls of I-st accuracy class were used to conduct the testing. The results of compressive strength tests According to the compliance criteria for the compressive strength test specified in PN-EN 206 + A1:2016-12 Annex B, : “the teA tensile strength test was performed for three samples taken from the prestressing strand. This strand was used to transfer prestressing force into concrete in the beams. Experimental results for tensile strength Reinforcing steel grade B500SP, class C with increased ductility was used. The results of the reinforcement steel bars’ tensile strength tests are presented in Ultimate capacity of the beams was verified using the ZD40 strength machine of the I-st accuracy class with a maximum load application up to 400 kN. For the purposes of the tests, additional steel beams for both supporting and loading zones were introduced to allow for testing of 3200 mm long beams. Based on the following, a four-point bending scheme was adopted with two loading and two support points, as shown in Loading was applied with a constant value of maximum 0.8 kN/s. Results were recorded with Phantom MIRO M310 camera with a recording speed of 3260 fps at a maximum resolution of 1280 × 800 pixels and high-resolution digital camera Nikon D5200 with a maximum photo resolution of 6000 × 4000 pixels. Photos were taken every one second.Both beams were loaded until the ultimate strength of the concrete was achieved. For each beam test, damage progression was similar. Firstly, uniformly distributed perpendicular cracks appeared at the largest bending moment area , then a The highest concentration of degradation within the compression zone appeared between loading points for beam No. 1. For beam No. 2, it was localized under the left loading point. It has been noted that the loading beam had rotated during the loading force application process, which could be a reason for the damage concentration at the left loading point instead of at the middle part of the beam.Due to multiple curvatures caused by assumed tendon layout, a proper model meshing has a crucial impact on the obtained results. In addition, a post-tensioned beam has anchorages on both ends to maintain prestressing force in the beam, which has further implications on the FE modelling approach. The developed models consist of a tendon in a nonlinear route layout, two anchorages on both ends, steel reinforcing bars  and concrete material. The finite elements of all the beams’ component parts were created as C3D8R spatial elements in the Hypermesh and then mesh geometry was exported to Abaqus/Explicit to perform the computational analysis, shown in The model of beam No. 1 has 121,951 nodes and the model of beam No. 2 has 114,121 nodes. The finite elements of tendon, steel reinforcing bars and concrete material stiffnesses are not duplicated, so the model stiffness is not artificially increased. Each component part of each beam contains its own finite elements with the corresponding contact parameters defined between each of them, as shown in Tendon with anchorages and steel reinforcement were modelled as a separate FE-s as shown in the The mesh size of the beam model was dependent on the geometry and curvature of the tendon in different areas of the beam, the location of the anchorages and the location of the steel reinforcement. Generally, a 20 mm × 20 mm mesh grid was provided along longitudinal direction, but mesh density was reduced to a 10 mm × 10 mm grid between the loading blocks. At the stirrups’ location, a 5 mm × 5 mm mesh was provided. Additionally, mesh elements located next to the stirrups in the zone between loading blocks were also meshed with a denser mesh of 5 mm × 5 mm. Two areas of denser mesh were provided for the elements adjacent to the tendon (above and below the tendon). Those were meshed with 5 mm × 5 mm elements, as shown in Beam No. 2, due to the higher inclination angle of the tendon, had smaller element sizes for the mesh elements adjacent to the tendon within areas with the largest tendon eccentricity. Here, the smallest element size was 4 mm × 4 mm, show in The defined values of the stresses and strains for prestressing bars are calibrated with experimental results presented in Constitutive model of prestressing steel is defined by elastic and nonlinear plastic material properties. The four-linear stress–strain diagram was properly adjusted to the experimental curve shown in Elastic strength limit;Lower yield limit equal to the tensile strength at 0.1% permanent plastic strain;Upper yield limit;Ultimate tensile strength.The following characteristic points of the stress—strain diagram were assumed:Corresponding stress and strain values at each characteristic point are presented in the For the other steel components present in the FE model, i.e., reinforcing bars and anchorages, a catalogue of values of strength and deformation parameters were adopted based on the manufacturer’s information, Tension Technology Martin S.r.l. , with thBased on the modulus of elasticity and yield strength values, the elastic strain values were calculated. Steel properties for anchorages have the largest ultimate strain values, which indicate the highest ductile level of all presented steel types. The strength and deformation parameters of steel components are presented in the A constitutive model of steel components is defined by elastic and linear plastic hardening material properties. Based on the adopted strength and deformation parameters, bilinear, elastic–plastic with linear hardening and stress–strain relationships, are presented in The concrete damage plasticity model was used for numerical analysis. There are several publications by Jankowiak et al. , Sumer aAt first, the basic parameters of the CDP model were assumed, such as dilation angle ε have the greatest impact on the obtained results. An important stage of the analysis is the appropriate calibration of the model parameters in relation to the experimental results. The dilation angle was analysed in the range of From the above-mentioned parameters, the dilation angle Then, the stress–strain relationships for compression and tension together with the damage variables, were determined. The basis for the description of these relationships is the determination of the mean values of concrete’s compressive and tensile strength as well as the deformation modulus. For this purpose, the authors assume that all concrete parameters relevant to the analysis depend on the mean compressive strength Therefore, if the actual concrete class:modulus, :(5)fcm=f2, and the mean deformation modulus is Taking into account that the mean compressive strength for the concrete cube samples is Concrete material is very sensitive to creep effects. It is often found that FE models obtain much stiffer behaviour than experimental beams; however, even if the experiment happens just a few days after pouring the concrete, creep and shrinkage effects occur. This is one of the reasons why the authors have found it important to include creep effects in the FE analysis. This approach is based on the assumption that the total deformation including creep is calculated by using an effective deformation modulus for concrete according to the formula, EN 1992-1-1 :(8)Ecm,eThe creep coefficient is calculated using the method provided in EN 1992-1-1 , in the Considering that the beams were supported by a formwork until compressive strength was reached, and were prestressed to the first prestressing force level in The most crucial factor for the proper definition of the constitutive relationship in the concrete damage plasticity material model is the adoption of the appropriate law of stress evolution in the strain function. For this purpose, separate laws of evolution were adopted for compression and tension, as shown in For compression, an elastic–plastic material model with non-linear hardening, linear softening and constant residual stress was assumed. For tension, the elastic material model with linear softening and constant residual stress was adopted.This model is described by the following stress–strain relationships:A full description of the adopted law of stress evolution in the strain function for concrete modelling is possible with the following parameters, More detailed information on the modelling of concrete behaviour is presented, among others, in the works of Cichorski and Stolarski ,24 and SThe last step of the CDP material model definition is a proper assignment of the damage parameters for both compressive and tensile zones. It was assumed that the damage parameter is proportional to the maximum stress value that material is capable to withstand to the actual residual stress which occurs.In accordance with this assumption, the damage model is described by the following damage–stress relationships:A full description of the adopted damage model is possible with the following limit values of damage parameters:All experimental, code and analytical stress and strain relationships discussed above are considered nominal. For the purposes of numerical analysis, they have been transformed into true stress–strain relationships, based on the equations:Anchorages, stirrups and longitudinal rebars are permanently connected with concrete material, without any slippery action. The surface-to-surface contact was used as a contact discretization method, consisting of the equality of displacements in the nodes of both contacting surfaces. The same assumption was made for contact between the outer surface of the tendon and the inner surface of the hole in the anchorage.Due to the assumed unbonded post-tensioned system in the experimental research, similar behaviour needed to be reflected in the numerical model. In this case, the interaction between the outer surface of the tendon and the inner concrete surface at the contact points is defined as the kinematic contact method with finite sliding. Contact interaction properties were defined in tangential and perpendicular directions to the tendon. Within a tangential direction, the friction formulation was used with a friction coefficient of in S.rl. .In turn, in the perpendicular direction, the contact pressure can be defined alternatively for two cases. Namely, if any contact occurs, the contact pressure is transferred between the defined surfaces, or if surfaces do not touch or separate after contact, the contact pressure drops to zero. In the numerical analysis it was assumed that the tendon is tightly embedded with concrete, and that it is not possible to separate the two materials in a perpendicular direction.Static analysis of post-tensioned beam will be obtained using an explicit solving procedure based on limit formulation of the dynamic equilibrium equation of motion.An explicit procedure was used for solving the equation of motion under the assumption of the lumped mass matrix of diagonal structure, see Wriggers . Then, tThe Rayleigh model of damping was adopted, in which the damping matrix is a linear combination of the mass and stiffness matrices:The central-difference scheme is used for explicit time integration the equations of motion. Within this scheme the velocities and the displacements are determined at the end of the next time increment 3 follows on the first-order accurate Taylor-series expansion for the velocities.The initialization the central-difference scheme necessitates the introduction of the initial conditions at the time Since the explicit method for integration equations of motion is conditionally stable, it is necessary to introduce the time step limitation in relation to the critical time step:According to the Rayleigh damping model, structural damping is defined as proportional to both mass and stiffness of structure.β = 0) is justified by the fact that non-linear material models are used, which describe the significant part of the structure stiffness reduction.In the numerical analysis, only Rayleigh mass damping was used, changing the Comparative analysis of the numerical force—displacement results with the results of experimental tests of the beams will allow for the selection of the optimal mass-damping parameter.Decisive for calculation of the dilatation wave velocity for the entire post-tensioned concrete beam model is the material defined for anchorages with parameters The smallest characteristic length of the element in the FE-discretization for both beam models is equal to The post-tensioned beam has initial loading caused by prestressing force in the tendon. Prestressing force was applied in the beam numerical model as a result of initial stress in the tendon.Since the beams were ultimately prestressed on the day of the experimental trial, it was assumed that only initial prestressing losses occurred without any long-term effects, e.g., steel relaxation.Total prestressing force was reduced by initial losses and then, as the value equal to Since the purpose of the analysis is to obtain the behaviour of a static model, not a dynamic one, the method of applying the external load has a significant impact on the behaviour of the numerical model. Too high a load application velocity may cause an unexpected model response.It has been found that the most effective way to control the loading process is to use the vectors of displacement velocity propagation, defined in every node on the top surface of selected beam nodes as presented in the Typically, the recommended static load velocity value should be less than 1% of the fastest dilatation wave velocity, as proposed by the manual Abaqus .However, this proposed range turned out to be too large for post-tensioned beams. At this velocity of loading application, large oscillations occurred in the model. It should be noted that a typical post-tensioned beam already has an initial prestressing force applied, which results in a greater dynamic response than typical reinforced concrete beams with no initial forces applied.In order to avoid model oscillations and the so-called local jetting effect, the blocks displacement velocity applied cannot exceed 0.025% of the fastest dilatation wave velocity identified in the model of beam. For this proportion of the fastest dilatation wave velocity, the value of displacement velocity was applied as Of equal importance to the value of displacement velocity, in order to stop the oscillating motion and to reflect the slow and smooth loading application, is the determination of the load amplitude and the total analysis time. For the considered static analysis, the method of smooth steps loading application was found to be suitable.Total analysis time depends on the expected total displacement value and loading velocity:Since the maximum load capacity of the beams was reached experimentally with the displacementam No. 2 , if the The relationship of the load amplitude to the analysis time was proposed using the smooth steps method in the following form, see manual Abaqus :(21)υ=υlThe applied relationship of the load velocity amplitude to the analysis time is shown in the Comparative analysis of the numerical results of the force—displacement relationship with the results of experimental tests of the beams will allow for the selection of the optimal value of the timeThe obtained numerical results of the force–displacement relationship are largely dependent on the selected mass-damping parameter. Several calculation tests were performed according to the mass-damping parameter range presented in Basically, both diagrams reflect the experimentally found behaviour of the beams during the loading process. Particularly good agreement between the numerical results and the experimental results was found for beam No. 1. However, in the numerical solution of beam No. 2, the stiffness of the beam to reach the load capacity was greater than in the experimental test. Namely, a good agreement of the load capacity was obtained with a much smaller value of displacement.The reason for the lower agreement of the numerical and experimental results in beam No. 2 can be seen in the probable occurrence of unintentional, random material imperfections in the experimental beam. This fact is confirmed by the almost identical stiffness of both beams observed in the experimental diagrams until the load value of about 65 kN is reached. This means that the potentially stronger beam No. 2 showed no greater stiffness than beam No. 1.The highest values of the maximum principal stresses are obtained below the velocity application nodes. Negative maximum principal stresses reflect compression stresses, and positive values represent tensile stresses (in MPa units). The highest stress values are obtained between loading points, but they do not exceed the strength of the material. Just below the load application areas there are local stress concentrations due to local load application. A similar stress distribution is obtained for both beams after reaching their load capacity .The first tensile cracks occurred in the concrete below the load application points, in the place of stirrups in both beams. Further damage propagation consists of the appearance of successive cracks between the stirrups, and then in diagonally distributed regions. Differences in tensile damage propagation were observed for both beams. Beam No. 1 for its hardening phase reached larger diagonal damage areas located on the outer sides of the load points than beam No. 2 .The extent of these zones increased in the post-critical phase of softening. Moreover, beam No. 1 had larger areas of tensile damage next to the load points than beam No. 2 .Since the damage was described from the beginning of plastic hardening in compression, the maximum range of compression damage under load capacity was obtained in the numerical results shown in the In the post-critical softening phase, beam No. 1 had larger areas of compression damage located outside the loading forces than beam No. 2. In turn, beam No. 2 had larger zones of compression damage between loading forces than beam No. 1, .The yield strength was reached only in the lower longitudinal rebars, in the regions below the loading forces . The yieThe damage progression obtained from numerical analysis was fully symmetrical, since no imperfections were introduced in the models. In fact, reinforced concrete structures experience many imperfections caused by, e.g., uneven distribution of aggregate, blockage of aggregate between reinforcement bars, rotation of stirrups during concrete pouring or local reduction of concrete cover. Such imperfections may cause an initial cross-sectional reduction; this is the starting point for further damage progression during loading.Asymmetrical damage progression occurred in both experimental beams. The initial cracks in beam No. 1 appeared in the middle between loading points , while iThere was no significant difference in the load capacity of both beams in the experimental results in the elastic phase and in the plastic hardening phase (up to 65 kN loading force), despite the introduction of the different eccentricities of the tendon system. Actually, beam No. 2 should be stiffer than beam No. 1. There may have been additional imperfections related to the execution of the beams, the precise preparation of the stand or the execution of the experiment, which could have caused the unexpected behaviour of beam No. 2. The numerical results show the expected differences in load capacity from the initial load phases.Imperfection modelling can be initiated by introducing an artificial crack in the place obtained during experimental tests. A similar approach is also presented by other authors, e.g., Jankowiak and Łodygowski  and SzczThe initiated crack caused the greatest concentration of stresses between the load points  and resuThe maximum stresses in the steel reinforcement have also changed. Now, instead of only stress concentrations below the load points, the maximum stress values occurred below the crack initiation point as shown in There are a few specific places where local stress values exceed the material resistances determined in the applied constitutive model of concrete. These places are located near the load application points and at the greatest contact forces of the steel reinforcement with the concrete in both numerical models. In experimental studies, the loading force was applied locally by a steel support beam. Therefore, authors decided to model a similar approach in the numerical analysis. Due to the nature of the load application, stress values above the concrete compressive strength appeared in the overload zone at the achieved beam load capacity, as shown for the location of the right loading point in beam No. 1 in the In the post-critical phase of the beam deformation, a similar effect was observed at the contact place between the steel reinforcement and the concrete . At thisThese specific overload areas must be the focus of further detailed contact analysis. The behaviour of concrete in these areas is influenced, for example, by the size and shape of the FE mesh, the area (or volume) of the contact zone between two materials with extremely different properties and determination of the properties of concrete with increased strength parameters in high compression contact zones.This paper presents the results of the numerical analysis of post-tensioned beams based on the results of its own experimental research.Precise preparation of experimental models of post-tensioned concrete beams and careful execution of experimental tests allowed the avoidance of unintentional model imperfections and the obtainment of appropriate results;The use of a separate finite element for modelling each material component of each beam: concrete, prestressing steel, reinforcing steel and anchorages, with appropriate modelling of contact interactions, results in a damage simulation qualitatively similar to the results of experimental tests. Initial cracks in the concrete occur at the location of stirrups and then develop into larger damage with new cracks between the stirrups;The convergence of the numerical solution is closely related to the precise modelling of the finite element geometry system. Elements in the finite element mesh should be made as square as possible to avoid numerical effects, i.e., shear locking and volume locking. The proposed meshing of the model allowed the avoidance of the numerical hourglass effect. The use of the reduced integration method for 3D hexahedral finite elements was sufficient to obtain a convergent solution, which is more efficient than other methods in terms of computational time. The applied meshing did not cause differences in the results between the incompatible modes and the reduced mode of the integration methods;The explicit procedure is an effective method for modelling post-tensioned concrete beams with different curvilinear tendon systems under static loading. With the ap-propriate calibration of the numerical model in relation to a detailed analysis of the experimental damage mechanism, the presented approach allows for the modelling of various geometries of post-tensioned beams. The proposed loading procedure in explicit solution method, based on an application of the loading velocity equal to 0.025% of the fastest dilatation wave velocity, gave a convergent solution for analysed post-tensioned beams without model oscillations and the local jetting effect. The beam models were calibrated to experimental results with the Rayleigh mass-damping parameter An appropriate simulation of concrete damage was obtained on the basis of the description of concrete material softening with a model of concrete damage plasticity. The inclusion of residual stresses in the concrete model ensured an increase in the ductility of the concrete material in interaction with the steel reinforcement to enable an extended damage simulation in the FEM beam models. Taking into account the effective modulus of the elasticity of concrete with the use of the real creep coefficient ensured a reduction in the stiffness in the numerical beam models by about 44%;A very good agreement between the numerical results and the experimental results for beam No. 1 was obtained. The slightly lower agreement between the numerical and experimental results for beam No. 2, especially in terms of displacements, was due to random imperfections found in the experimental results. The experimentally observed nature of concrete damage mechanisms and the numerical simulations of stress and damage states of both considered beams confirmed the design assumption about the ultimate load capacity that was determined by the strength of the concrete compression zone.On the basis of the obtained results, the following conclusions can be drawn, relevant for conducting experimental research, modelling of post-tensioned beams using the FEM and calibrating the numerical model to the experimental results:


Staphylococcus, Streptococcus, Corynebacterium, Leifsonia, Vicinamibacterales, and Actinophytocola were the most abundant genera.Concrete contains low microbial biomass, but some bacteria can grow in this highly alkaline environment. We used silica-based DNA extraction and 16S rRNA sequence analysis to identify the bacteria in a corroded concrete bridge sample from Bethlehem, Pennsylvania.  Concrete is a common building material used to construct most bridges in the United States. The deterioration of it over time results in bridge failure . The strWe obtained a concrete fragment from the Minsi Trail Bridge in Bethlehem, Pennsylvania . After soaking it in 10% bleach for 10 min to decontaminate the surface, we extracted DNA per reference GCTATGCGCGAGCTGC-3′) (–16S rRNA amplicons (V4 region) were produced by a two-step method  and 806RCTGC-3′) –11. TaxoTGC-3′) –, 13. DefTGC-3′) –. Sample Staphylococcus, Streptococcus, and Corynebacterium, which were demonstrated previously to be the primary bacterial community constituents in cement powder .SRX18763179 (interior sample), SRX18763180 (surface sample), and SRX18763181 (glass bead control sample).16S rRNA amplicon DNA sequences from this study have been uploaded to the National Center for Biotechnology Information Sequence Read Archive (SRA) under the accession numbers


Background: The coronavirus disease 2019 (COVID-19) pandemic severely affected Southeast Asia, with >35 million cases and ~360,000 deaths. Despite relatively low rates of secondary bacterial infection among inpatients with COVID-19, several countries reported increased antibiotic use; raising concerns for worsening antimicrobial resistance. We assessed the impact of the COVID-19 pandemic on the use of antibiotics commonly used to treat respiratory infections in Southeast Asia. Methods: We evaluated intravenous antibiotic use among hospitalized adults in acute-care wards in 6 hospitals; 3 in Indonesia and 3 in the Philippines. We abstracted data on antibiotics that are commonly used to treat respiratory infections in these hospitals. We calculated antibiotic use rates for the 25 included antibiotics as monthly defined daily dose per 1,000 patient days (or patient discharges where patient days was unavailable) using data from pharmacy dispensing records and administrative records. Median antibiotic use rates for the prepandemic period (March 2018–February 2020) and the pandemic period (March 2020–February 2021) were compared, and percentage changes were calculated for (1) all 25 antibiotics combined; (2) ceftriaxone; (3) vancomycin and linezolid combined (anti-MRSA); and (4) broad-spectrum antibiotics with activity against Pseudomonas aeruginosa (anti-PSA). Monthly antibiotic use and COVID-19 patient discharges were graphed over the 36-month study period (March 2018–February 2021) to visualize trends . The Wilcoxon rank-sum test was used to determine whether differences in median antibiotic use rates were statistically significant (2-tailed P < .05). Results: Overall, trends in antibiotic use were higher during months with increased COVID-19 patient discharges . Use of all 25 antibiotics combined significantly increased in 4 of 6 hospitals (6.9%–63.6%) during the pandemic period compared to the prepandemic period. Ceftriaxone use significantly increased in 3 of 6 hospitals (37.1%–55.4%) and decreased in 3 of 6 hospitals (15.9%–31.9%). Anti-PSA antibiotic use significantly increased in 4 of 6 hospitals (16.1%–161.5%). Although anti-MRSA antibiotic use was low , use during the pandemic increased in 3 of 6 hospitals (59.8%–212.6%). Conclusions: We observed substantial increases in antibiotic use among hospitalized adults in Indonesia and the Philippines during the COVID-19 pandemic. The increased use of broad-spectrum antibiotics is concerning given the potential consequence of worsening antimicrobial resistance. Understanding how increases in antibiotic use compares to rates of bacterial infection, antimicrobial resistance, and antibiotic availability and accessibility during this time is important to contextualize results. These findings reinforce the importance of antibiotic stewardship practices to optimize antibiotic use, especially during pandemics.Disclosure: None


This quality improvement study aims to determine whether diagnostic stewardship (avoiding unnecessary urine cultures) or antibiotic stewardship (reducing unnecessary antibiotic treatment after an unnecessary culture) is associated with better outcomes in reducing antibiotic use for asymptomatic bacteriuria. Is stewardship focused on diagnostic testing or antibiotic treatment associated with reduced asymptomatic bacteriuria (ASB) treatment in hospitalized patients?In this 3-year, 46-hospital quality improvement study including 14 572 patients with positive urine cultures, the percentage of patients with a positive urine culture who had ASB declined from 34.1% to 22.5%, suggesting more selective urine testing. In contrast, the percentage of patients with ASB who received antibiotics and antibiotic duration for ASB remained relatively stable.To decrease antibiotic treatment related to ASB, hospitals should prioritize reducing unnecessary urine cultures . Hospitalized patients with asymptomatic bacteriuria (ASB) often receive unnecessary antibiotic treatment, which increases antibiotic resistance and adverse events.To determine whether diagnostic stewardship (avoiding unnecessary urine cultures) or antibiotic stewardship (reducing unnecessary antibiotic treatment after an unnecessary culture) is associated with better outcomes in reducing antibiotic use for ASB.This 3-year, prospective quality improvement study included hospitalized general care medicine patients with a positive urine culture among 46 hospitals participating in a collaborative quality initiative, the Michigan Hospital Medicine Safety Consortium. Data were collected from July 1, 2017, through March 31, 2020, and analyzed from February to October 2022.Participation in the Michigan Hospital Medicine Safety Consortium with antibiotic and diagnostic stewardship strategies at hospital discretion.Overall improvement in ASB-related antibiotic use was estimated as change in percentage of patients treated with antibiotics who had ASB. Effect of diagnostic stewardship was estimated as change in percentage of patients with a positive urine culture who had ASB. Effect of antibiotic stewardship was estimated as change in percentage of patients with ASB who received antibiotics and antibiotic duration.Of the 14 572 patients with a positive urine culture included in the study ; 28.4% (n = 4134) had ASB, of whom 76.8% (n = 3175) received antibiotics. Over the study period, the percentage of patients treated with antibiotics who had ASB  declined from 29.1%  to 17.1%  . The percentage of patients with a positive urine culture who had ASB (diagnostic stewardship metric) declined from 34.1%  to 22.5%  . The percentage of patients with ASB who received antibiotics (antibiotic stewardship metric) remained stable, from 82.0%  to 76.3%  , as did adjusted mean antibiotic duration, from 6.38  days to 5.93  days .This quality improvement study showed that over 3 years, ASB-related antibiotic use decreased and was associated with a decline in unnecessary urine cultures. Hospitals should prioritize reducing unnecessary urine cultures  to reduce antibiotic treatment related to ASB. Successful urine culture stewardship strategies include reflex urine cultures, order-set hygiene, suppressing urine culture results, or education.21 Although these efforts have reduced ASB treatment in single-center studies, data from large collaboratives are lacking. In addition, it is unclear whether efforts to reduce ASB treatment should focus on diagnostic or antibiotic stewardship.Despite national guidelines recommending against treating ASB in most hospitalized patients,In 2017, the Michigan Hospital Medicine Safety Consortium (HMS), a statewide collaborative quality initiative, began collecting data, sharing best practices, and benchmarking performance related to antibiotic treatment of ASB. In this quality improvement study, we report the outcomes of the collaborative and estimate the effect of diagnostic vs antibiotic stewardship on ASB treatment.26 Briefly, HMS is a statewide collaborative quality initiative sponsored by Blue Cross Blue Shield of Michigan and Blue Care Network to improve care for hospitalized medical patients. Of the 92 hospitals in Michigan, 50 (54.3%) participated during the study period. We report through March 31, 2020 (around the beginning of the COVID-19 pandemic).Descriptions of HMS have been published previously.24 First, HMS collects patient-level data from each hospital through medical record review by nurse abstractors employed by individual hospitals but trained and supported by HMS. Patient data include signs and symptoms, diagnostic testing, antibiotic prescriptions, and outcomes.8 These data inform hospital quality metrics that are shared to benchmark performance and identify areas for improvement27  2.0 reporting guidelines.Because the purpose of HMS is to measure and improve the quality of existing care practices, this project was determined by the University of Michigan’s institutional review board to be nonregulated, as it did not satisfy the definition of human participant research. We followed Standards for Quality Improvement Reporting Excellence (3), or urine culture positive only for candida. Patients were also ineligible if they had altered urinary tract anatomy or a urologic procedure during hospitalization or were receiving antibiotic treatment for a UTI at the time of admission. Patients with symptoms of a UTI who did not receive antibiotics were excluded.Patients were eligible for inclusion if they were hospitalized at an HMS hospital, had a positive urine culture, and did not receive antibiotic treatment for another infection during hospitalization. Patients ineligible for inclusion were those with any of the following: concomitant infection , initial admission to intensive care, pregnancy, severe immune compromise , rigors, or pyelonephritis. Patients with new-onset mental status changes without other symptoms of a UTI were considered to have a UTI only if they had leukocytosis (>10 000 cells/uL), hypotension (<90 mm Hg), or at least 2 systemic inflammatory response syndrome (SIRS) criteria. Patients with bacteremia from a urinary source or severe sepsis (≥2 SIRS criteria plus organ damage) were considered to have a UTI. Patients were considered treated for a UTI if they received antibiotic therapy within 3 days of the positive urine culture. The goal for each hospital was to include 8 patients every 16 days, including weekends. To identify patients for inclusion, HMS abstractors consecutively screened positive urine culture lists in order of discharge time. Once 1 case was included (or if no eligible cases were identified that day), the abstractor would screen the subsequent discharge day until 8 patients were included. Abstractors undergo case-based training and random yearly audits by HMS for quality assurance  and antibiotic stewardship .The association between the primary outcomes and how each could be improved through diagnostic vs antibiotic stewardship is shown in Because we only sampled patients with a positive urine culture, patients who had ASB did not enter the cohort when a urine culture was not collected. If diagnostic stewardship was associated with positive outcomes, the percentage of positive urine cultures that were ASB would decrease over time; thus, the diagnostic stewardship metric was the percentage of positive urine cultures that were ASB, regardless of antibiotic treatment.We measured the estimated effect of antibiotic stewardship in 2 ways. First, we characterized the change in the percentage of patients identified to have ASB who received antibiotic therapy. Second, we characterized the change in antibiotic duration in patients with ASB. Additional outcomes of interest included estimated ASB cases and antibiotic treatment days avoided, hospital characteristics associated with improvements in antibiotic use over time, and self-reported diagnostic and antibiotic stewardship strategies conducted by participating HMS hospitals.The HMS consortium does not continuously collect rates of urine cultures over time. To confirm changes in urine culture practices over time, HMS conducted 3 separate, 2 week–long prevalence surveys of urine cultures. During the 3 time periods , hospitals reviewed all urine cultures and reported the total number of cases that met HMS inclusion criteria.As noted in We first described the percentage of patients with a positive urine culture who had ASB (treated vs not) and UTI, as well as the change over time in each group. We then characterized self-reported diagnostic or antibiotic stewardship strategies using descriptive statistics.To estimate the change over time in the primary outcomes, we used logistic regression (for dichotomous outcome) or negative binomial models (for duration), adjusted for within-hospital clustering by allowing for random intercepts and slopes, to obtain adjusted odds ratios (aORs) or adjusted incidence rate ratios assessing the change in each outcome by quarter. Because patient characteristics were used to define appropriateness, no patient-level adjustments were included. Random intercepts describe baseline differences in treatment between hospitals. Random slopes estimate how the rate of change in treatment over time varied across hospitals. Using these models, we graphically presented  the predTo assess whether hospital characteristics were associated with changes in ASB treatment over time, we added potential hospital-level explanatory variables  to the logistic regression models and assessed for interaction effects with baseline rates or slopes. Change in the number of urine cultures reported in point-prevalence surveys over time was assessed using linear regression. Change in signs and symptoms over time in patients classified as having a UTI was assessed using logistic regression.All statistical tests were performed at an α level of .05. Two-tailed estimates of effect and 95% CIs are reported for all regression coefficients. Statistical analyses were performed with SAS, version 9.4 (SAS Institute), and StataSE, version 17 (StataCorp). Because disparities due to patient demographics may exist, we report data on sex, race, and ethnicity obtained from medical records and categorized as noted in the eAppendix in Although 50 hospitals contributed data to HMS, 4 were excluded for having fewer than 10 patients, leaving 46 hospitals. After exclusions  received antibiotic therapy . In patients with ASB who received antibiotic therapy, the median (IQR) duration was 6 (4-8) days. The most common empirical and discharge antibiotics are listed in eTable 1 in Of the 46 included hospitals, 40 received the 2019 survey and 39 (98%) responded. An additional 3 hospitals answered a November 2018 survey when antibiotic stewardship, but not diagnostic stewardship, data were collected. All 42 responding hospitals had a UTI-directed antibiotic stewardship strategy during the study period, and 26 of 39 (66.7%) reported an ASB-directed diagnostic stewardship strategy. Additional self-reported diagnostic and antibiotic stewardship strategies are summarized in P < .001; P < .001; P = .09; P = .045).After adjusting for clustering, overall ASB-related antibiotic use decreased over the study period, illustrated by the percentage of patients treated for UTI who had ASB declining from 29.1%  to 17.1%  . There was a small increase in subjective symptoms over time  (eAppendix in For patients classified as having a UTI (n = 10 438), there was no change over time in the frequency of objective signs  decrease. Together, this suggests that strategies to reduce unnecessary urine cultures  resulted in the majority of the reduction in overall ASB-related antibiotic use. The idea of diagnostic stewardship was first codified in 2017 by Morgan et al in a This study must be interpreted in the context of limitations. First, due to heterogeneity in type, strength, and timing of diagnostic stewardship strategies reported by hospitals, we were unable to assess which diagnostic stewardship strategy was most effective. Second, we were unable to collect complete data on the number of urine cultures over time. The findings from the 3 prevalence surveys that the number of patients with positive urine cultures decreased despite stable hospital bed size supports the inference that urine cultures decreased over time. Third, we were unable to collect data on hospitalized patients in whom urine cultures were avoided. It is possible that these patients still received antibiotic therapy. Fourth, we relied on data collection from medical records. It is possible that documentation of symptoms increased over time (improved documentation vs gaming), which could affect the classification of UTI vs ASB over time. However, in a sensitivity analysis, we found that most objective signs of a UTI  remained stable over time, suggesting documentation did not substantially influence the changes seen. Study strengths include, to our knowledge, the largest sample size, including medical record review, for an ASB study; a large, diverse group of hospitals; and the ability to distinguish the outcomes of diagnostic vs antibiotic stewardship over 3 years.This study has implications. Antibiotic stewardship is a Joint Commission and Centers for Medicare & Medicaid Services requirement for accreditation/participation. We found that diagnostic stewardship may improve ASB-related antibiotic use more than antibiotic stewardship. Although we could not assess which specific diagnostic stewardship strategy was most effective, best practice may be to identify where  and how  inappropriate urine cultures are being ordered and design a diagnostic stewardship strategy based on need. Thus, national policy and antibiotic stewardship programs should consider requiring and incorporating diagnostic stewardship into ASB improvement efforts.In this quality improvement study, we found that antibiotic treatment for ASB appeared to decrease over time, associated with a reduction in unnecessary urine cultures. Hospitals and national policy should prioritize reducing unnecessary urine cultures  to reduce ASB-related antibiotic use.


Upworthy.com comparing multiple headline variants for the same news articles. This unique setup allows us to control for factors that could otherwise have important confounding effects on headline success. Based on the prior literature and an exploratory portion of the data, we formulated hypotheses about the linguistic features associated with statistically superior headlines, previously published as a registered report protocol. Here, we report the findings based on a much larger portion of the data that became available after the publication of our registered report protocol. Our registered findings contribute to resolving competing hypotheses about the linguistic features that affect the success of text and provide avenues for research into the psychological mechanisms that are activated by those features.What makes written text appealing? In this registered report, we study the linguistic characteristics of news headline success using a large-scale dataset of field experiments (A/B tests) conducted on the popular website  The spread of news and other important information has changed significantly in the age of online social media. As readers increasingly obtain their news over social media ,2, publiNew York Times articles that were heavily shared, identifying that articles that express positive or high-arousal emotions have a higher likelihood of becoming popular. A broad literature focuses on predicting success in news by various means ), recall is 53.17%, and precision is 54.53%. We thus find evidence in favour of the hypothesis that the more successful headline in a controlled pair in the Confirmatory Dataset can be predicted significantly better when using linguistic features than when guessing randomly.Using our regression model, with a 0.5 decision threshold on the predicted value, prediction accuracy on the Confirmatory Dataset is 54.42%  as no significant negative effect is detected. Regarding negative-emotion words (H2b), we hypothesized that their presence is positively associated with headline success. Confirmatory analysis supports this hypothesis .Regarding positive-emotion words (H2a), we hypothesized that their presence is negatively associated with headline success (H2a). We find no evidence in favour of this hypothesis .Consistent with the hypothesis H3, we find that length is positively associated with headline success  as no significant negative effect is detected.We hypothesized that higher readability is negatively associated with headline success (H4). We do not find evidence in favour of this hypothesis , but we do not find evidence in support of H5b .We hypothesized that generality, i.e., the use of indefinite articles is positively associated with headline success (H5a), while specificity, i.e., the use of definite articles is negatively associated with headline success (H5b). We find evidence in support of H5a  is positively associated, whereas the use of first-person plural  pronouns is negatively associated with headline success. Furthermore, the use of third-person pronouns, both singular  and plural  is positively associated with headline success. On the contrary, we found no significant positive association between the use of second-person pronouns and headline success .Out of the five hypotheses related to pronouns, our confirmatory analyses are consistent with four, and not consistent with one. The use of first-person singular pronouns  between the compared headlines the same. We have further studied the performance of the regression model in identifying the better headline by exploring the presence of a dose-response relationship. In our hypothesis H1, we only predict that the model will perform significantly better than the random baseline when making predictions on the complete dataset. However, we also expected that the model would perform much better in instances when the difference in click-through rate (CTR) between the compared headlines is larger. Performing such an analysis , we see New York Times headlines. The most frequent topics among the tested headlines are related to everyday ordinary experiences and entertainment news . The nature of the tested headlines should be taken into account when considering the extent to which our findings are expected to generalize to other news domains .We investigated the topic distribution of the headlines  by taggiWhile the specific words associated with the hypotheses related to pronouns and articles are stated in -2). We found that this conclusion is robust to the exclusion of any individual word from the dictionary, with the effect estimate ranging between β = -0.04 (corresponding to the variation when the word “pretty” is excluded) and β = -0.02 (when the word “better” is excluded). Consistent with the conclusion of no evidence of an effect according to the pre-registered significance level α = 0.01, the p-values range between p = 3.64x10-2 (corresponding to the variation when the word “pretty” is excluded) and p = 2.95x10-1 (when the word “better” is excluded).For each word frequently categorized as either positive or negative emotion, we individually omitted that word from the category dictionary, fitted the regression model following the analysis plan, and estimated the corresponding coefficients for positive and negative emotion. Regarding positive-emotion words (H1b), in the main confirmatory analyses, we found no evidence in favor of the hypothesized effect . We found that this conclusion is robust to the exclusion of any specific word from the dictionary, with the effect estimate ranging between β = 0.17 (corresponding to the variation when the word “wrong” is excluded) and β = 0.20 (when the word “fight” is excluded). Consistent with the conclusion of a positive effect according to the pre-registered significance level α = 0.01, the p-values range between p = 1.60x10-12 (corresponding to the variation when the word “wrong” is excluded) and p = 5.44x10-17 (when the word “fight” is excluded).Similarly, regarding negative-emotion words (H2b), in the main confirmatory analyses, we found evidence in favor of the hypothesis that their presence is positively associated with headline success  is unlikely to skew the estimated effects and alter the conclusions of our study.Our analyses are consistent with the hypothesis that the more successful headline in a controlled pair in the Confirmatory Dataset can be predicted at a statistically significant level based on linguistic features alone (H1). Even though the accuracy is significantly higher compared to the random baseline, we note that it is still low, i.e., 54% for all pairs, and less than 60% even for the pairs with the largest difference in the actual click-through rate. When comparing confirmatory to exploratory pairs, even though the number of modeled pairs increased by more than four times, the accuracy of the model fitted on confirmatory pairs did not increase significantly. The fact that predictability did not increase with sample size implies that identifying better headlines based on linguistic features is an inherently hard problem, not merely a sample size issue.Overall, we found that the pilot results generalize to the Confirmatory Dataset. We also note that the point estimates from the confirmatory data fall within the 95% confidence intervals of the pilot estimates. This speaks in favor of the robustness of the analyses of the A/B tests since the exploratory estimates generalize to the confirmatory estimates made with unseen data.Overall, our findings are aligned with recent research  using a Thus, our work contributes findings regarding linguistic features that confirm and refine insights derived by Hagar et al. in a different setting  and using a different methodology (predictive modeling vs. explanatory modeling). The discrepancies between certain linguistic cues  open the door for future investigations in order to elucidate the precise mechanisms at play.Understanding the linguistic features that promote information sharing has broad implications, and it can shed light on what compels people to view and share online content. Knowledge of the linguistic features that cause success could be used by benevolent and malevolent actors alike. Benevolent actors might aim to optimize linguistic features in order to maximize engagement in high-stakes contexts such as public health messaging ,61. MaleOf particular relevance for headline design, our confirmatory analyses found evidence supporting the hypothesis that the presence of negative-emotion words is positively associated with headline success. Previous work has found that online systems might promote negativity by design since negative emotions are more important when conveying the meaning of the message with a few words . Our anaWe believe that our work goes beyond prior research due to the way the A/B test nature of the experiments lets us control content and author confounds, reader confounds, and context confounds. Content and author confounds are controlled since headlines are about the same article with the same content and are written by the same author, reader confounds are controlled since readers are randomly assigned with a headline version without user-specific selection biases, and context confounds are controlled since the image thumbnail and the rest of the website the user landed on were exactly the same. However, when interpreting our results, certain limitations should be taken into account.First, we acknowledge that we do not remove all potential confounds. The compared headlines are not directly manipulated by the website on a single linguistic variable while keeping the rest of the headline fixed in  on our dSecond, we note that Upworthy headlines are written in a specific style. For instance, headlines omit articles by stylistic convention. Therefore, findings from other media might not easily transfer. Future work should determine the extent to which these findings generalize to other domains, including frequently studied literature and social media domains, based on which the hypotheses were developed. Similarly, linguistic features of news articles and their impact on headline success might vary across cultures and languages. Future work should determine the extent to which our findings generalize to other languages beyond English.Third, the textual cues might not necessarily always match the psychological interpretation. For example, regarding measuring emotions, advanced machine learning approaches to classify the emotion in the headlines exist. Similarly, the combined use of more sophisticated text representation tools, including other dictionary-based approaches and machine learning methods, could be used in future research to increase the predictability of success. However, we opt for using the LIWC dictionary approach due to its simplicity, interpretability, and frequent use in the previous literature. Additionally, the dictionary approach lets us identify the words that carry positive or negative emotion, which is compatible with our dictionary-based approaches of measuring other linguistic features of interest. Similarly, the usage of definite and indefinite articles is an imperfect proxy for generality and specificity of a headline, and headline length may not accurately reflect the quantity of information present in the headline. More detailed analyses are necessary to disentangle headline length, the amount of information that the headline contains, and its conciseness.Finally, we note that unfortunately no reliable statistics about the website’s user demographics are available. We know that in the period when the tests were conducted (between 2013 and 2015), Upworthy was a fairly popular website and an important actor in the online ecosystem . TherefoWe found that generality (H5a), the use of negative emotion words (H2b), headline length (H3), and the use of first-person singular and third-person pronouns are positively associated , while the use of first-person plural pronouns is negatively associated, with success (H6b). Although Upworthy headlines have a specific style, we expect that the psychological processes leading to a click on Upworthy, e.g., referring to general contexts (H5a) or the use of negative emotions words (H2b), can be expected to generalize to different types of content. We believe these insights about linguistic properties that lead to clicks on Upworthy will be of interest to content creators across domains.


We hypothesized that any significant change in inflammatory markers between the two groups would indicate the role of inflammation in Met-S that would help in future directions for screening and treatment of Met-S. Design and Methods. A total of 2010 adult men, aged 18-30 years, were divided into two groups: with Met-S (N = 488) and without Met-S (N = 1522), according to the International Diabetes Federation definition. We compared the serum levels of inflammatory biomarkers between the two groups. We also studied the correlations between the inflammatory markers and the components of Met-S to explore the biomarker potential of inflammatory markers for screening of Met-S. Logistic regression analysis was performed to test the association between inflammatory markers and Met-S.  Inflammatory mediators are associated with many chronic diseases; however, their role in metabolic syndrome (Met-S) is not well documented. We therefore aimed to compare the serum markers of inflammation including C-reactive protein (CRP), myeloperoxidase (MPO), interleukin-6 (IL-6), tumour necrosis factor alpha , blood pressure, body mass index (BMI), and age; however, none of these markers were correlated with HDL. Logistic regression analysis showed a significant association between Met-S and inflammatory markers.  A large number of subjects in the Met-S group were suffering from obesity. Out of the 2010 total subjects, only 731 (36.4%) had normal fasting blood sugar (FBS), while the prevalence of prediabetes and diabetes was significantly higher in subjects with Met-S. We observed significant increases in serum levels of CRP, MPO, IL-6, and TNF-β are significantly increased in young adults with Met-S. This is probably the first study reporting TNF-β levels in Met-S. Since a proinflammatory cascade precedes many years before the onset of cardiovascular disease, these inflammatory biomarkers could help in the monitoring of high-risk individuals with Met-S who will be requiring therapeutic intervention. Serum levels of CRP, MPO, IL-6, and TNF- Metabolic syndrome (Met-S) and associated diseases are a global health problem. Met-S is a cluster of metabolic abnormalities characterized by hypertension, high fasting blood glucose, increased waist circumference, hypertriglyceridemia, and low high-density lipoprotein (HDL) cholesterol levels . In receModern lifestyle, including sedentary behaviour and high intake of caloric and sugar-rich foods, contributes to metabolic ailments with preceding pathophysiological changes such as hyperglycaemia, obesity, hypertension, dyslipidaemia, and a proinflammatory state associated with accumulation of adipose tissue . Adiposeα), and TNF-β in young military recruits with and without Met-S. We also studied the correlations between the inflammatory markers and the components of Met-S to explore the biomarker potential of inflammatory markers for the screening of Met-S. We hypothesized that a clear understanding of the role of inflammatory mediators in Met-S would not only help in selecting potential biomarkers for screening high-risk individuals but also pave the way for exploring therapeutic modalities such as anti-inflammatory drugs for the treatment of Met-S.In this study, we compared serum markers of inflammation including CRP, myeloperoxidase (MPO), interleukin-6 (IL-6), tumour necrosis factor alpha  α, and TNβ were significantly higher in subjects with Met-S compared to subjects without Met-S, there was no difference in TNF-α levels between the two groups. The differences in the biological activity between TNF-α and TNF-β are due to their different abilities for binding to the target cells [α in the development of obesity-related insulin resistance is still controversial. Metabolically triggered inflammation plays an important role in the pathogenesis of obesity-induced insulin resistance and type 2 diabetes mellitus [α on glucose and lipid metabolism as well as its involvement in β-cell apoptosis and endothelial dysfunction in diabetes [α neutralization in type 2 diabetes patients failed to affect insulin sensitivity [α blockage did not improve insulin resistance or endothelial function in volunteers with obesity, insulin resistance, and Met-S.In our study, although the serum levels of TNF-et cells . The rolmellitus , 37. Prediabetes –40. On csitivity , 42. [43β are significantly increased in young adults with Met-S, whereas no significant alteration was observed in TNF-α. This is probably the first study reporting TNF-β levels in Met-S. We also observed a significantly high prevalence of obesity and hyperglycaemia in subjects with Met-S. An increase in fat tissue in subjects with obesity and/or insulin resistance in subjects with hyperglycaemia would result in low-grade systemic inflammation that could easily be monitored by inflammatory biomarkers well before the onset of cardiovascular disease.In conclusion, serum levels of CRP, MPO, IL-6, and TNF-


We are currently facing two big global challenges: antibiotics shortage and multidrug resistance. Since the “Golden Age” of natural products-based antibiotic discovery in the mid-20th century, we have only discovered a very limited number of new antibiotics. This indicates that the traditional antibiotic discovery pipeline is drying up. Moreover, the misuse and overuse of limited classes of antibiotics have caused the emergence and spread of multidrug resistance. Fortunately, the advance of synthetic biology brings us new opportunities for antibiotic discovery. A starting place could be the genomic (gene) and related enzymatic information with the “bottom-up” strategy , empowerSeveral important studies ,4,5,6,7 In the review article written by Huang and colleagues , the bioInonotus hispidus. Its secondary metabolites are mainly polyphenols and triterpenoids, with multiple bioactivities, including anticancer, immunomodulatory, anti-inflammatory, antioxidant, antimicrobial, and enzyme inhibitory activities. I. hispidus is a promising source of bioactive compounds, including antibiotics for health promotion and functional food development.The review by Wang and colleagues  summarizTo address the challenge of the shortage of antifungals, Zhong and colleagues have written a review  that focZymomonas mobilis are deeply investigated using bioinformatics and CRISPR/Cas12a-based genome-editing technology. Six ampicillin-resistant genes are identified, and their related mutants are constructed. It shows that ZMO0103 is the key to ampicillin resistance in Z. mobilis and how other ampicillin-resistant genes may have a synergistic effect [In the study conducted by Geng and colleagues, the mechanisms of antibiotic resistance and genes associated with antibiotic resistance in c effect . This stStreptomyces, and this was found to play an important role in controlling different types of antibiotic production. This study provides insight into the regulation of antibiotic biosynthesis and the potential targets for future antibiotic discovery and production [The research article conducted by Yang and colleagues reports a novel global regulatory protein, SspH, which is widespread in oduction .Streptomyces albus BK3-25. By analyzing transcriptomes, eight putative transporter genes were found and proven to positively impact salinomycin exports. The overexpression of these genes will lead to an increase in the titer of salinomycin and improved self-resistance. The study provides a transcriptome-based strategy for improving the titer of salinomycin and identifying transporter genes for other antibiotics [Liu and colleagues, in their research paper, aimed to identify the genes that are involved in the export of the anti-coccidiosis agent salinomycin produced by ibiotics .Neosartorya pseudofischeri that can produce pseudofisnins: novel 1-benzazepine-containing compounds. A methyltransferase named PseC was identified as a crucial enzyme in this BGC, catalyzing di-methylation in an amine group [In their research article, Xue and colleagues found that L-kynurenine (Kyn) is a building block for the biosynthesis of bioactive natural products. They used a genome-mining approach and discovered a biosynthetic gene cluster (BGC) from ne group .Streptomyces sp. 26D9-414. The new compound 2 showed similar cytotoxicity to cisplatin in treating various cancer cells [Using a combinatory strategy of genome-mining and OSMAC (one strain of many compounds), Zhang and colleagues identified two new and seven known cyclodipeptide derivatives from er cells , which iBacillus subtilis and Escherichia coli). The results showed that cefotaxime metal complexes with Zn and Se had high antioxidant activity against HepG-2 cells, and they also presented potent antibacterial activities at low concentrations [In the study conducted by Al-Thubaiti and colleagues, metal cefotaxime complexes of Ca(II), Cr(III), Zn(II), Cu(II), and Se(VI) were synthesized and characterized. They then investigated the effects of cefotaxime and cefotaxime metal complexes on oxidative stress and their activity against cancer cells (HepG-2) and bacteria , Fe(III), Cu(II), Zn(II), and Se(IV) complexes of the antibiotic ceftriaxone (CFX). Furthermore, they also investigated the effect of CFX and its metal complexes on oxidative stress and tissue injury in rats. It showed that CFX and its metal complexes, especially CFX/Zn, had high antibacterial activity .I hope that readers find the articles in this Special Issue interesting and inspiring for their own research. Joining together, let us bring society another “Golden Age” of antibiotic discovery!


The fracture toughness of sand concrete is affected by aggregate characteristics. In order to study the possibility of exploiting tailings sand, available in large quantities in sand concrete, and find an approach to improve the toughness of sand concrete by selecting appropriate fine aggregate. Three distinct fine aggregates have been used. After characterizing the fine aggregate used, the mechanical properties were tested to characterize the toughness of sand concrete, the box-counting fractal dimensions were calculated to analyze the roughness of fracture surfaces, and the microstructure was tested to observe the path and width of microcracks and hydration products in sand concrete. The results show that the mineral composition of fine aggregates is close, but their fineness modulus, fine aggregate angularity (FAA) and gradation vary considerably; FAA has a significant impact on the fracture toughness of sand concrete. The higher the FAA value, the more resistant it is to crack expansion; with the FAA values of from 32 s to 44 s, the microcrack width in sand concrete was reduced from 0.25 um to 0.14 um; The fracture toughness and microstructure of sand concrete are also related to the gradation of fine aggregates, the better gradation can improve the performance of the interfacial transition zone (ITZ). The hydration products in the ITZ are also different because more reasonable gradation of aggregates reduces the voids between the fine aggregates and the cement paste and restrains the full growth of crystals. These results demonstrate that sand concrete has promising applications in the field of construction engineering. Sand concrete is a new type and special composite material ,2,3, whiThe fracture toughness of concrete is usually improved by adding supplementary cementitious materials, inert fillers, reactive fillers and fibers or by improving curing methods. For instance, Madani Bederina et al.  studied The crack propagation directly affects the fracture energy and fracture toughness. The fracture process of sand concrete with different aggregates is shown in In order to study the effect of fine aggregate characteristics on the fracture toughness of sand concrete, aggregates with different fineness modulus, FAA and aggregate gradation were selected as raw materials. The brittleness coefficient of sand concrete specimens with different fine aggregates was measured and compared with traditional concrete. Moreover, the complexity of the fracture surface and the evolution of the microstructures of sand concrete specimens were analyzed by means of box-counting fractal dimensions and Scanning Electron Microscope (SEM), respectively. This research will contribute to a better understanding of how the characteristics of fine aggregate affect the fracture toughness of sand concrete ,24,25.Fine aggregates here are defined as grain sizes smaller than 2.36 mm. The used fine aggregates are gold tailing sand (GTS) from Tong-guan county, iron tailing sand (ITS) from Shangluo City and river sand (RS) from Xi’an City shown in . The res3 and a specific surface area: 446.5 m2/kg.Ordinary Silicate Cement, 42.5 grade of conch brand, was used in experiments. The physical characteristics of the cement used are a specific density: 1030 ± 20 kg/mThe admixture used is a superplasticizer with 28% of dry matter content in liquid form, and the water-reducing capacity was greater than 25%.The mix proportions for specimen preparation in this study were summarized in In order to analyze the effect of particle characteristics of fine aggregates on the toughness of sand concrete, the physical properties of three kinds of fine aggregates were conducted. The size distributions, fineness modulus, apparent density, bulk density, void ratio and powder content of the fine aggregates were tested following the national standards of GB/T 14684-2011 (Standard of Sand for Construction) used in China. And the FAA determination device required by the cited JTD E42-2005 standard.X-ray Diffraction (XRD) analyses were performed to detect the phase compositions of fine aggregate. Firstly, fine aggregates were grounded into powder, passed through 200 mesh sieves, and then dried for 24 h in a drying oven at 105 °C. Finally, characterized the composition and content of fine aggregate using a D8 ADVANCE X-Ray Diffractometer. The measurement conditions of XRD were a tube voltage of 30 kV and a tube current of 20 mA. Scans were repeated continuously from 15° to 80° with 0.1°/s using Cu target (wavelength is 1.54178 Å).According to the strength test of cement mortar with GB/T 17617-2005. The specimens were tested for compressive strength and flexural strength at the curing periods of 7 and 28 days by means of using the DYE-300 automatic universal testing machine. The loading rate is 2400 N/s, and the flexural loading rate is 50 N/s. The sizes of the specimens were all 40 mm × 40 mm × 160 mm.The complexity of the concrete fracture surface can be characterized by the box-counting fractal dimension ,27. The The macroscopic mechanical properties of sand concrete are closely related to the microstructure of sand concrete. So, the microstructure of the specimens of SC1 and OC1 were tested by Hitachi S-4800 Scanning Electron Microscope. The specimens were first immersed in absolute ethanol solution for 24 h in order to terminate the hydration reaction. Regular pieces of a 5-mm size were cut, polished and then kept in an oven for 24 h at 105 ± 5 °C. Finally, the microstructures of the specimens were tested after gold coating.2, Al2O3 and Fe2O3. The river sand is constantly washed in water, and its mineral composition is relatively single; while tailings sand exists in the field environment, its mineral composition is more complex. Therefore, the quartz content of river sand is higher than that of quartz in tailings sand.The mineral compositions of the fine aggregates are shown in The size distributions of the fine aggregates are shown in The micromorphology of the fine aggregates is shown in D is the particle size (mm), P(D) is a fraction of the total solids being smaller than size D, minD is the minimum particle size (mm), maxD is the maximum particle size (mm) and q is the distribution modulus. The value of q is between 0.23 and 0.37. The q value of the target curve in the close packing model is fixed at 0.23 based on the properties of fine aggregates [R2, as shown in Equation (2)).mixP is mixed fine aggregates, the tarP is the target grading calculated from Equation (1), n is the number of points used to calculate the deviation and R2 = 0.86) was highest compared to the target curve, while the correlation coefficient of GTS(R2 = 0.64) and RS (R2 = 0.60) were lower compared to the target curve. As a result, ITS showed the most reasonable aggregate gradation, while RS showed the most undesirable aggregate gradation. This suggests that the gradation is closely related to the particle size distribution of fine aggregate. Finally, it should be noted that the basic difference between these aggregates lies in physical characteristics, grain shape, granularity and particle size distributions.The gradation characteristics of different fine aggregates also affect the fracture toughness of sand concrete. Hence, in this study, the modified Andreasen close packing model  is utiligregates . The graThe results of the compressive strength and flexural strength of sand concrete with different fine aggregates are shown in The brittleness coefficient  reflects the deformation resistance of concrete and can characterize the toughness of concrete simply and intuitively. The lower the brittleness coefficient, the better the resistance to deformation. According to the GB/T50010-2010 code for the design of concrete structures, the brittleness coefficient of ordinary concrete is between 8:1 and 11:1, and it becomes higher with the increase of concrete strength grade. The box-counting fractal dimensions of different concrete fracture surfaces are illustrated in The microstructure and properties of ITZ are one of the most important influencing factors on the mechanical properties of concrete ,35,36. TThe propagation paths of microcracks in different sand concrete and ordinary concrete are shown in The adhesion between the aggregate and the cement paste also affects the fracture toughness of the concrete. The widths of microcracks in the ITZ between the aggregate and cement paste in sand concrete with different fine aggregates and ordinary concrete are shown in The hydration products of sand concrete with different aggregates and ordinary concrete are shown in (1)The fracture toughness of sand concrete is related to the characteristics of the aggregate. However, the brittleness coefficients of sand concrete with different aggregates are between 5:1 and 6.5:1 at different strength grades, and the brittleness coefficient of sand concrete is much lower than that of ordinary concrete. Sand concrete exhibits good fracture toughness than ordinary concrete.(2)The effect of particle fineness of fine aggregates on the fracture toughness of sand concrete is not significant.(3)The fracture toughness of sand concrete is strongly affected by the FAA. As the FAA value increases from 32 s to 44 s, the fractal dimension of the fracture surface of sand concrete increases from 2.25 to 2.69, and the average flexural strength increases by 13.65% under the same compressive strength.(4)The fracture toughness, microstructure and hydration products of sand concrete are also related to the gradation of fine aggregates. A good grading distribution can improve the performance of ITZ. When the correlation coefficient of the gradation compared to the target curve increased from 0.60 to 0.86, the microcrack width of ITZ decreased by about 38.55%, and there was also a difference in the hydration products produced. Therefore, the better the gradation of fine aggregates, the better the crack resistance of sand concrete.From the data of experimental in this study, the following conclusions can be drawn:


This study presents a series of shock-tube tests conducted on structural panels using ammonium nitrate fuel oil (ANFO) as the explosive. The characteristics of the blast waves propagating through the shock tube were analyzed by measuring the pressure generated at specific locations inside the shock tube. The extent of differences in blast pressure generated in a confined space, such as the shock tube, was compared to that predicted by the proposed method in the Unified Facilities Criteria 3-340-02 report. The target specimens of this study were plain reinforced concrete (RC), high-performance fiber-reinforced cementitious composites (HPFRCCs), and composite panels. Polyurea-coated RC panels and steel plate grid structure-attached RC panels were used as composite panels to evaluate the effectiveness of the coating and structural damping methods on the enhancement of structural blast resistance. The tests were conducted with different ANFO charges, and the crack patterns and lengths on the rear surface of each panel were measured. Based on the measured results, discussions regarding the blast resistance capacities of each panel type are provided. With increasing concerns regarding explosion incidents, such as bomb attacks, improvement of the blast resistance of concrete structures has become an important factor to be considered in structural design. When concrete structures are subjected to extreme loads of high amplitudes and short durations, considerable amounts of debris and fragments are generated on the rear face of the concrete structures owing to the brittle characteristics of concrete. Because this phenomenon can result in secondary damage to facilities and human lives inside protective structures, various reinforcement methods have been developed to compensate for the inherent drawbacks of concrete. To improve material performance, different fibers have been introduced in various cement-based composite materials that have high energy absorption and ductility properties; some of them are ultrahigh-performance concrete (UHPC) and high-performance fiber-reinforced cement composites (HPFRCCs) ,2,3,4. FMany studies have investigated the blast-resistance performance of structures using improved cement-based materials. Li et al.  manufactIn addition to the development of cement-based materials to improve material properties, many studies have focused on enhancing structural performance by applying various reinforcing materials to the interior or exterior of structures. Ha et al.  conducteSeveral experimental studies have been conducted to evaluate the resistance performance of structures subjected to blast loads; however, their results were mostly obtained from field tests resulting in large variations and a lack of reproducibility . Therefo3 was introduced into the cementitious matrix to compensate for the insufficient flowability owing to the low water-to-binder ratio (W/B). A glycol-based shrinkage-reducing admixture (SRA) was used to mitigate the potential for shrinkage cracks during production. Straight steel fibers with a 2% volume fraction were added to the HPFRCC mixtures, and the aspect ratio  were installed 11 m, 13.5 m, and 14.85 m away from the ANFO source to identify the superposition of blast load within the shock tube, as shown in W) and the ground distance (R). In this study, the TNT equivalent of ANFO was set to 0.74, incident pressures were calculated based on the graphs provided in [The measured pressures in the shock tube and the calculated pressures were obtained from the procedure proposed in the Unified Facilities Criteria (UFC) 3-340-02 report . The incvided in , and freThe experimental results for each specimen obtained by performing the shock-tube test, including the acceleration, reflected pressure, duration, and crack length at the rear face, are summarized in The total crack lengths on the rear faces of the specimens were measured using an image-processing program after objectification by preprocessing all the images to the same pixel and scale. Based on the measured crack length, the resistance capacities of the specimens against the blast wave were compared, and the experimental results according to the ANFO charge weight are presented in As shown in Several peaks were observed in the pressure–time curve owing to reflection by the mass concrete block located at the back end of the shock tube. The time difference between the first and second peaks decreased with the distance from the explosion source, and the pressure was significantly amplified owing to the overlap of the first and second pressure peaks at the Free 3 location;The blast pressure was amplified owing to multiple reflections of the pressure within the shock tube as the generated pressure passed through it. Thus, the measured pressure in the shock tube was significantly different from the pressure predicted by the method proposed in the UFC report;Among the specimens considered in this study, the HPFRCC panels demonstrated the best performance against blast pressure even for the thinner specimen. This was attributed to the improved material properties and the inclusion of steel fiber to restrain crack propagation;Polyurea can be effectively used to reinforce the tensile behavior of concrete structures and prevent the scattering of fragments;Energy-absorbing panels used in this study were found to be ineffective with regard to their energy absorption capacity. To increase the energy absorption capacity, the stiffness of the energy-absorbing panels should be reduced to allow deformation of the panel to dissipate the blast energy.This study investigated the characteristics of blast waves in a shock tube with an ANFO explosive and compared the blast resistance capacities of the considered specimens. By adopting plain reinforced concrete panel as the control specimen, the application of polyurea, an energy-absorbing panel, and HPFRCC were considered as variables. The following conclusions were drawn from the shock-tube tests: