Current materials engineering trends put forward the development of efficient structural solutions. The steel replacement with fiber-reinforced polymers (FRP) exemplifies the key to the corrosion problem. However, the relatively low deformation modulus of typical FRP materials raises the deformations of the structural components. Together with the self-weight reduction increasing the kinematic displacements, the latter issue makes developing hybrid structures comprising compression-resistant concrete and high-performance in tension FRP profiles important. Although such hybrid systems are applicable for bridge engineering, the uncertainty of the inter-component bonding properties complicates developing these innovative structures, including the design models. The typical solution focuses on the local bond improvement, e.g., employing FRP profile perforation and mechanical anchorage systems. However, this study introduces an alternative solution, using the stress-ribbon bridge structural system for creating the hybrid beam prototype, which combines the synthetic fiber-reinforced concrete slab and pultruded FRP profile fixed on the supports. This work exemplifies the structural development concept when the finite element (FE) modeling outcome defines the target reference of the design procedure. Thus, on the one hand, this innovative structure simplifies the corresponding numerical (FE) model, which assumes the perfect bond between the components of the hybrid beam system. On the other hand, the solution to the support problem (resulting from a low resistance of pultruded FRP profiles to transverse loads) improves the structural performance of the bridge prototype, doubling the structure’s flexural stiffness and load-bearing capacity regarding the weak concrete supports’ system. The bending tests proved the adequacy of this solution in describing the design reference for further development of the proposed structural concept. As a result, there is a tendency to develop new structural materials to change traditionally used concrete and steel3. Fiber-reinforced polymers (FRP) define the promising alternative to steel, and carbon, glass, and aramid fiber-based composites are the most common FRPs on the market5. It is known that manufacturing technology affects the mechanical performance of FRP composites. Thus, this study focuses on the pultruded objects because of the ability of the pultrusion technologies to produce a large volume at low operating costs and high fabrication rate, fiber content, and geometry tolerances7.The materials engineering trends put forward the development of efficient structural solutions9. However, such components often face transverse loads regarding the pultrusion pathway; moreover, the pultruded details must resist bolt removal-induced local stresses5. Therefore, the smooth unidirectional roving and mats protect the longitudinal filaments, complicating the internal reinforcement structure of the FRP material6. At the same time, these additional protection means can be insufficient for developing FRP structures12. In addition, the relatively low deformation modulus of typical FRP materials raises the deformations of the structural components. Together with the self-weight reduction increasing the kinematic displacements13, the latter issue makes developing hybrid structures comprising compression-resistant concrete and high-performance in tension FRP profiles important.The pultrusion direction and reinforcement filament distribution coincide, ensuring the mechanical performance of the structural FRP parts15, the uncertainty of the inter-component bonding properties complicates developing these innovative structures. The typical solution focuses on local bond improvement, employing FRP profile perforation and mechanical anchorage systems, e.g., Mendes et al.16 and Zhang et al.17. However, the design of such structures lies beyond the standard regulation field. At the same time, the bond problem complicates structural analysis and numerical modeling19. Still, studies23 describe the typical analysis examples, neglecting the bond problem.Although hybrid composite systems are applicable for bridge engineering27 define the cases when the bond parameters were among the research subjects. For instance, Chen et al.26 focused the research on the FRP laminate bonding properties. Four remaining works take into account the FRP-concrete bond performance of the hybrid structural systems, which describe the research object of this study. Dang and Phan8 and Cai et al.25 investigated the FRP bar bonding performance in concrete. Robinson and Melby24 studied the mechanical resistance of the concrete-filled GFRP tube, and Muc et al.27 simulated the composite deck slab. However, a rare publication considers the support joint’s resistance of the FRP profiles, e.g., Zhang et al.28.References15 because of the combination of the concrete, resisting the compressive load induced by the glass-fiber-reinforced profile (GFRP) distributed in the tension zone of the flexural element. Furthermore, the reliable profile fixation to the supports ensures the composite behavior of the hybrid beam. In addition, it simplifies the corresponding finite element (FE) model, allowing the perfect bond assumption between the composite parts. Thus, this FE model describes the reference for developing the hybrid beam system. The bending tests substantiate the solution adequacy and exemplify the situation when the numerically predicted outcome determines the hybrid system efficiency and provides the designer with the structural reference.In contrast, this study employs the stress-ribbon bridge solution to create the hybrid beam prototype, combining the polymeric fiber-reinforced concrete (PFRC) slab and pultruded FRP profile. However, the proposed structural system does not require massive supports typical for the stress-ribbon systemsFiberline, Denmark). The preliminary simulations29 determined the support block’s geometry. In addition, a carbon-fiber-reinforced polymer  strip strengthens the most tensioned face of the GFRP profile. Figure The designed beam comprises the polymeric fiber-reinforced concrete (PFRC) slab, resisting the compression force from the support joints and fixing the glass-fiber-reinforced profile  model, shown in Fig. The commercial software Non-Linear Cementitious material model with 55 MPa compressive strength31 determines the deformation behavior and failure mechanism of PFRC. An elastic-plastic model (elasticity modulus = 170 GPa and tensile strength = 2.8 GPa) determines the material behavior of the 10 × 1.4 mm CFRP strip1. The 3D solid finite elements describe the polymer matrix of the GFRP profile, assuming the fracture mechanic principles for tensile failure and the plasticity approach to compressive failure.The 7 adapted the smeared reinforcement model, initially developed for reinforced concrete elements with structural mesh reinforcement32, to represent the glass filaments and verified this numerically efficient solution, simulating the three-point-bending tests of FRP profile fabricated by the same manufacturer as this study. The verification7 demonstrated the FE model’s ability to predict the profile’s load-bearing capacity and deformation response. An elastic-brittle constitutive law defines tension failure of the fibers oriented in the pultrusion direction. A 63.4% smeared reinforcement ratio was assumed for this analysis, corresponding to the previous research7. The polymer matrix has an elastic modulus of 3.23 GPa, and tensile strength of 90 MPa. The E-glass fibers (smeared reinforcement) have a 73 GPa elastic modulus and a 3445 MPa tensile strength; the filaments do not resist compression stresses. The perfect connection was assumed between all the model components. The first loading stage considers the self-weight of the beam. Two point-loads were applied in succeeding increments resulting in a 0.125 kNm moment increase at each successive loading increment on the 600 mm pure bending zone .The physical tests were carried out in two stages, and two nominally identical beams were produced for each series. The specimens were poured using the same mix proportions with a target 55 MPa compressive strength, as considered in the previous studiesThe construction of the support joints made the difference between the beam series. The first series produced the hybrid beam prototypes with nominal geometry, shown in Fig. All the beams were poured into the inverted position. Steel forms with plywood planks were utilized for the beams’ production. The foamed polystyrene and wood inserts were used to form the support blocks, fixing the GFRP profile. The concrete was poured into two layers. In the first layer, a 55 mm thickness concrete deck was formed and densified using the vibration table. After that, the concrete supports were formed using foamed polystyrene plugs. The support blocks of the first beam series ensure the 20 mm cover of the profile on the beam support. The 95 mm monolithic concrete support blocks Fig.  were denThe beam specimens from the second group had improved anchorage blocks—a hollow-section steel 100 × 200 mm rectangular profile protected the GFRP profile at the supports. This modification increased the support block length from 95 to 250 mm, but the support distance remained the same. In addition, the width of the compressive concrete zone was decreased to simplify the beam production, preserving the flexural rigidity of the beam by increasing the compressive zone height. The remaining components of the hybrid system, i.e., GFRP profile, CFRP strip, and adhesive, remained the same. Figures The vertical 6 mm and horizontal 8 mm steel bars prevented movements of the GFRP profile inside the steel tube Fig. . The 8 mThe beams of both series were demolded after two days and stored in laboratory conditions (average temperature 20 °C and 40% relative humidity) for 30 days before the tests. The same loading scheme and distribution of the measurement devices were used for all tested beams. Figure The bending tests were carried out using a 5 MN servohydraulic machine with the load applied in the displacement control manner with the 0.4 mm/min rate. A load cell was used to measure the applied load. An ALMEMO 2890-9 data logger recorded the reading of all LVDT devices and the load cell. The outputs were collected every second.33. These results reasonably agree with the assumed 55 MPa target strength of PFRC. In addition, the test results of the punching shear tests of the 550 × 550 × 40 mm slabs verified the PFRC material model, and these results are not included in this article.The compressive tests identified 65.6 MPa and 70.3 MPa strength of 100 mm concrete cubes, which correspond to the 49.9 MPa, and 53.4 MPa strength of the standard ∅150 × 300 mm cylinders33. The analysis employs the vertical displacements’ monitoring results of the pure bending zone ; L1, L2, and L3 are the LVDT readings . On the contrary, this study demonstrates that the solution to the support problem (resulting from a low resistance of pultruded FRP profiles to transverse loads) improves the structural performance of the bridge prototype, doubling the structure’s flexural stiffness and load-bearing capacity regarding the weak concrete supports’ system.On the one hand, the proposed structural solution contradicts the traditional idea of local bond improvement, e.g., employing FRP profile perforation and mechanical anchorage systems  model determines the adequate reference for designing the hybrid structural systems and efficiently utilizing advanced composite materials.This study introduces a novel hybrid beam system’s design concept when the numerically predicted outcome modifies the design target. The numerical simulations and physical experiments prove the viability of the proposed idea. The following significant conclusions result from this study:


Suture passer needle, as one of commonly used instrument in the arthroscopic rotator cuff repair, often breaks at the notch of the needle, which originally was designed to facilitate suture with thread. Our study aimed to evaluate the suture failure rate and stitch success rate between intact suture needle and broken needle and explore the mechanism of the needle breakage and achieving better future designs.From 2017 to 2021, consecutive 437 shoulders  underwent arthroscopic repair for full-thickness rotator cuff tear at the authors’ institution. The breakage of needles was recorded. Finite elements analysis and mechanical test were utilized to compare stress distribution, puncture performance, and loaded puncture performance between the broken needle and the intact needle.We identified 19 consecutive patients for whom the needle tip of the TruePass™ suture passer was broken in the 437 shoulder surgeries. Based on the finite element analysis of Abaqus, around the tip and the notch of the intact needle was a large stress concentration. The average puncture force required by intact needle tip and the broken tip is 61.78N and 78.23N respectively. While the intact tip with notch is easier to break than the broken tip.The notch of the needle is a weak point in mechanics. The broken needle without the notch still has good tendon piercing and thread passing ability. The notch of needle may be not necessary, and the tip of the needle should be modified. As arthroscopic technologies continue to develop, arthroscopic rotator cuff repair has become an alternative choice for orthopedic surgeons rather than the open surgical approach , 2. ArthHowever, the notch at the tip of the needle often causes problems during the surgery. When the needle tip penetrates through thick tendon or the acromion in the narrow subacromial space, the needle is vulnerable to break at the notch site . Broken Previous studies only reported the needle breakage issue without suggestion of a solution. We also observed such a phenomenon during the shoulder arthroscopic surgery. Additionally, we found that the reason that made us ignore the problem about broken needle was that the suturing process could be successfully achieved without influence from the broken needle. Therefore, we suggested whether the notch of the suture passer, a mechanically vulnerable position, could be modified and we further investigated whether snapping the needle at the notch in advance would influence the suture failure rate of arthroscopic rotator cuff repair. Finite element analysis (FEA) on the needle fracture was used to explore the stress distribution difference between the needles with and without snapping in advance. We hypothesized that the needle with snapping at the notch in advance would result in a reduced occurrence of needle breakage than the needle without snapping in advance.From 2017 to 2021, 426 consecutive patients, 175 men and 251 women, aged 23–83 years, mean age 53.2 ± 11.6 years, 437 shoulders , underwent arthroscopic repair for full-thickness rotator cuff tear at the authors’ institution. The Institutional Review Board of the Shanghai Jiaotong University School of Medicine Renji Hospital approved the study protocol (No. KY2020–177) and granted exemption for patient consent. The indications for surgery included shoulder pain or disability refractory to supervised nonsurgical treatment, including medication, local steroid injections, and physical therapy program, for a minimum of 6 months. Patients were excluded when they had other pathologies, like shoulder instability or chondral procedures. All procedures were performed by one shoulder-trained surgeon group with the TruePass™ suture passer . The broken parts of the needles, the tips of broken needle where were removed and whether it is left during the operation were recorded .Since the stress on the tip of the intact needle was mainly analyzed, SolidWorks  software was used to create a model of the anterior part of the intact needle . A threeThe posterior end of the intact needle was completely fixed (U1 = U2 = U3 = UR1 = UR2 = UR3 = 0), and a 100 N force was applied on the tip of the needle in the direction of the needle body . The bacThe broken needle models were uniformly prepared with one surgical scissor to break the intact needle at 1 mini meter proximal to the needle's notch position in advance. The intact needle model and broken needle model are shown in Five TruePass™ disposable special suture needles with intact needle tips and five broken needle tips were selected. First, the TruePass™ thread passing device and TruePass™ disposable special suture needle are assembled, and then the fresh bovine tendon, 7.5 mm thick, is clamped at TruePass™. Then, the TruePass™ thread connector and TruePass™ test tool are installed on the electronic universal mechanical testing machine . A stable and recordable traction force is transmitted to TruePass™ through the cooperation of the electronic universal tester and TruePass™ testing and trial tooling. In order to simulate the actual use of a suture needle in the human body during arthroscopic surgery, the TruePass™ disposable special suture needle under two conditions (intact needle tip/broken needle tip) was excited to conduct the puncture performance test on fresh bovine tendon , and theLoad puncture performance test in this experiment, five TruePass™ disposable special suture needles with intact needle tips and five broken needle tips were selected, as well as, ultrahigh molecular weight polyethylene . First, the TruePass™ thread passing device and TruePass™ disposable special suture needle are assembled with ultrahigh molecular weight polyethylene , and then the fresh bovine tendon, 4 mm thick, is clamped at TruePass™. Then, the TruePass™ thread connector and TruePass™ test tooling are installed on the electronic universal mechanical testing machine . A stable and recordable traction force is transmitted to TruePass™ through the cooperation of the electronic universal tester and TruePass™ testing and trial tooling. In order to simulate the actual use of a suture needle in the human body during arthroscopic surgery, the TruePass™ disposable special suture needle under two conditions (intact needle tip/broken needle tip) was excited to conduct the puncture performance test on fresh bovine tendon , and thet-tests were used. The software IBM SPSS statistics 24.0  was used for all statistical analyses, and p < 0.05 was considered statistically significant.Continuous variables were expressed as means standard deviations (SD). In order to compare the difference between the two groups in finite element analysis of Abaqus and mechanical test, independent sample In this study, we identified 19 consecutive patients who had the incident that the needle tip of TruePass™ suture passer was broken. Eighteen needle tips were removed during surgery without further tissue injury. One needle tip was removed in the second surgery. One needle tip was embedded inside the tendon and hard to be removed, to avoid further injury to tendon tissue, we did not remove it from the tendon with agreement of patient. The patient with the remnant needle tip was followed up for 3 years without any complaints. In total, 19 broken needles, 18 tips removed were measured, and needle tips were found in different places . In addiBased on the finite element analysis of Abaqus, the stress cloud diagram obtained is shown in −2 mm, while the overall displacement amplitude of the broken needle varies from 0 mm to 2.854 × 10−2 mm, with obvious differences ( р <0.05).The difference in the behavior between the intact needle and the broken needle is illustrated in р < 0.05), , .р < 0.05)  .A suture passer facilitates sutures to penetrate through soft tissues such as tendons, and the needle tip received loading from the surrounding tissues. The total stress can lead to breakage of the needle at the notch or near the notch. Therefore, the optimization of needle tip is important. Analysis of distribution in the needle tip is an essential step, as maximum stress in the needle determines the success or failure of arthroscopic rotator cuff repair . ExcessiWe also found that the most easily broken part of the device is at the indentation in the needle tip through FEA simulation. The unique memory function and flexibility of this nickel-titanium alloy allow the surgical needle return to its original shape after bending. This alloy has been widely used in clinical applications. The mechanical fracture of nickel-titanium alloy has been a hot issue in the endodontology field, and the phenomenon of needle breakage in arthroscopic rotator cuff repair has been reported too , 11, 15.The notch at the needle tip is designed to aid the passage of sutures through tissue. However, suture passers use the same disposable needle frequently during a single case; repeated loadings on the needle tip may easily lead to breakage of the needle at the notch. What we found in this experiment might solve this problem. It should be noted that the length of the needle breakage in advance should not exceed 2 mm proximal to the notch position. In clinical use, there are many factors affecting the stress distribution of the needle tip. The stress distribution is different due to different geometrical parameters, thus affecting the sensitivity of the bending fracture . TherefoThe needle should be marked by scales so that the broken tip can be found in a timely manner. We also have some advice for surgeons. First, when stitching, the surgeon should avoid stretching and pulling of the tendon. Thus, moderate force should be used to suture thick and tough tendon tissues . If the In addition, the subacromial space is very narrow, which results in easy needle breakage when needle tips touch the hard bone , 20. It Through clinical research, mechanical testing, and finite element analysis, we found that the notch of the needle is a weak point in mechanics, and breakage often occurs in or near this point. At the same time, the broken needle without a notch still has good tendon piercing and thread passing ability. The study highlights that all devices should be carefully checked during and after surgery. The notch of needle may be not necessary, and the tip of needle should be modified. The investigation provides knowledge to assist in achieving better future designs.


Staphylococcus aureus and the host immune system can have significant impacts on antibiotic efficacy, suggesting that targeting and modulating the immune response to S. aureus infection may improve antibiotic efficacy and improve infection outcome. As we’ve previously shown, high levels of reactive oxygen species (ROS), associated with an M1-like proinflammatory macrophage response, potently induce antibiotic tolerance in S. aureus. Although the proinflammatory immune response is critical for initial control of pathogen burden, recent studies demonstrate that modulation of the macrophage response to an anti-inflammatory, or M2-like, response facilitates resolution of established S. aureus skin and soft tissue infections, arthritis, and bacteremia. Here, we evaluated the impact of host-directed immunosuppressive chemotherapeutics and anti-inflammatory agents on antibiotic efficacy against S. aureus.Interactions between IMPORTANCEStaphylococcus aureus is the leading cause of hospital-acquired infections in the United States with high rates of antibiotic treatment failure. Macrophages represent an important intracellular niche in experimental models of S. aureus bacteremia. Although a proinflammatory macrophage response is critical for controlling infection, previous studies have identified an antagonistic relationship between antibiotic treatment and the proinflammatory macrophage response. Reactive oxygen species, produced by macrophages during respiratory burst, coerce S. aureus into an antibiotic tolerant state, leading to poor treatment outcome. Here, we aimed to determine the potential of host-directed immunomodulators that reduce the production of reactive oxygen species to improve antibiotic efficacy against intracellular S. aureus. In experimental models of Staphylococcus aureus bacteremia, bacteria are engulfed by macrophages within minutes of entering the bloodstream, leading to a potent proinflammatory immune response associated with increased NF-κB activity  during oxidative burst  and bacteremia via upregulation of peroxisome proliferator-activated receptor gamma (PPARγ)  , 10. Cornt alone . Additiont alone . Nrf2 isnt alone , 14. Incnt alone –15.S. aureus.Here, we evaluate the impact of host-directed immunosuppressive chemotherapeutics and anti-inflammatory agents on antibiotic efficacy against intracellular S. aureus, we treated bone marrow-derived macrophages (BMDMs) with the corticosteroid dexamethasone prior to infection with S. aureus and treatment with rifampicin. While treatment of macrophages with dexamethasone alone did not affect bacterial load, in combination with rifampicin, it significantly improved antibiotic efficacy against S. aureus after 24 h, which correlated with decreased ROS production   . UTIs arBoth Nrf2 activators tested decreased ROS and increased antibiotic efficacy. However, the CDDO-Me ARAPas decreased bacterial load to a greater extent. Nrf2 activators do not present a typical dose response curve, in fact most of them show a hormetic curve where high doses result in inhibition of the pathway . BecauseS. aureus-induced experimental endophthalmitis tested the effect of combinatorial antibiotic and dexamethasone treatment on bacterial clearance, tissue damage, and retinal function  + 10% FBS + l-glutamine (complete MEM) and allowed to adhere overnight at 37°C, 5% CO2. BMDMs were treated with 10 μM sulforaphane . Statistical significance was calculated using the Student’s t test  or one-way ANOVA with Sidak’s multiple comparison test as described in the figure legends.Bone marrow from wildtype (WT) C57BL/6J mice (Jackson Laboratory) was isolated as described in . Bone maoraphane , 400 nM oraphane , 100 nM 4 cells per well in white tissue-culture-treated 96-well plates. Macrophages were treated as described above. The cells were washed three times with PBS. L-012 was diluted to 150 μM in Hanks’ balanced salt solution (Gibco). Luminescence was read immediately using a Biotek Synergy H1 microplate reader. Data shown are representative of three independent assays of three biological replicates. Statistical significance was calculated using a one-way ANOVA with Sidak’s multiple comparison test or Student’s unpaired t test as indicated in figure legends.The luminescent probe L-012  was used to measure ROS. BMDMs were seeded at 4 × 105 LAC cells in Mueller-Hinton broth were incubated with various concentrations of rifampicin in a 96-wellmicrotiter plate. Where indicated, wells were supplemented with 100mM rosiglitazone, 10mMsulforaphane, 400 nM CDDO-Me-NPs, 100 nM dexamethasone. The plate was covered with a breath easy strip and incubated for 24h at 37°C. The MIC of rifampicin was 0.004mg/mL, and was unchanged by supplementation with rosiglitazone, sulforaphane, CDDO-Me-NPs or dexamethasone. The experiment was performed in biological triplicates.MIC assays for rifampicin were conducted using a microdilution method. Approximately 5 × 10n) are indicated in the methods for each experiment. Statistical analysis was performed using Excel (Microsoft) or Prism 8 (GraphPad) software.Statistical method and sample size (Additional data that support the findings of this study are available from the corresponding  T1 Crossref missing


Promoting improvement in Infection Prevention and Control (IPC) is an important part of improving the quality of care. The influence of leadership attention and incentives on the self-perceived continuous improvement in IPC has drawn a lot of attention, but relevant academic research is still lacking. The objective of this study is to explore the effect of leadership attention on self-perceived continuous improvement in IPC among medical staff and its underlying mechanisms.The 3,512 medical staff from 239 health facilities in Hubei, China, were surveyed online during September 2020. Data on leadership attention, incentives, and improvement in Infection Prevention and Control were collected using self-administered questionnaires. Correlation analysis was used to analyze the relationship between leadership attention, incentives, and improvement in Infection Prevention and Control. Amos 24.0 was used to analyze the mediating role.The scores of leadership attention, incentives and self-perceived continuous improvement in Infection Prevention and Control were all high. The score of leadership attention was the highest (4.67 ± 0.59), followed by self-perceived continuous improvement (4.62 ± 0.59) and incentives in Infection Prevention and Control (4.12 ± 0.83). Leadership attention positively affected self-perceived continuous improvement in Infection Prevention and Control . Moreover, incentives partially mediated the effect of leadership attention on self-perceived continuous improvement in Infection Prevention and Control among medical staff .Leadership attention positively affects self-perceived continuous improvement in Infection Prevention and Control among medical staff, and incentives mediates this relationship. The present study has valuable implications for self-perceived continuous improvement in Infection Prevention and Control from the perspective of leadership attention and incentives. Healthcare-associated infections (HAIs) have become a major global threat to health systems. 1.7 million people acquire HAIs in the United States annually, resulting in more than 98,000 deaths –8. The 2Continuous improvement in IPC involves improving operations, system processes, working environment, or regulatory compliance, focusing on the process improvement of the organization, which reflects the improvement culture and climate of the organization . The posThe continuous improvement in IPC can be influenced by both patient and medical factors. From the perspective of the medical, individual and organizational factors affect continuous improvement in IPC . It is cThis study intends to explore the relationship between leadership attention and self-perceived continuous improvement in IPC, and its internal mechanism, focusing on the mediating role of incentives. This study has significant enlightenment for leadership construction and incentive system construction in the IPC field, thus providing an evidence-based suggestions for the comprehensive management and continuous improvement in IPC at the organizational level. So far, this study is the first to quantitatively describe the level and distribution of leadership attention, incentives, and self-perceived continuous improvement in IPC and to elaborate the mechanism of leadership attention on self-perceived continuous improvement in IPC with a large sample size.Leadership attention in IPC means the commitment that leaders give to HAIs , which wH1: Leadership attention positively affects the continuous improvement in IPC.The incentive is a process in which personal demands are created under the action of external or internal stimuli, motives and behaviors are generated under the guidance of demands, and finally, some goals are achieved . IncentiH2: Leadership attention positively affects incentives in IPC.Incentives are important factors affecting continuous improvement. The incentive model by Porter and Lawler  proposedH3: Incentives positively affect the continuous improvement in IPC.Incentives may play a mediating role in the relationship between leadership attention and continuous improvement. The path-goal theory illustrates that leaders could help their subordinates to achieve their goals through incentive mechanisms, with incentives as an intermediary role . A studyH4: Leadership attention positively affects the continuous improvement in IPC mediated by incentives.The four research hypotheses are summarized in the model .An online survey was conducted among medical staff from all 237 comprehensive medical institutions who participated in the Training course on hospital infection management , in September 2020, Hubei Province, China, through a stratified random sampling method.Based on institutional stratification, we encouraged each comprehensive medical institution to randomly select medical staff from different departments to attend the conference. In order to ensure the number of questionnaires, participants were encouraged to send the questionnaire link to their colleagues who were engaged in nosocomial infection but could not attend. Each comprehensive medical institution was required to provide at least 17 questionnaires. Hubei, China was chosen as the research site because coronavirus disease 19 (COVID-19) originated in Hubei, and developed into a major public health issue in China. It has a dense population, a large number of medical institutions, and rich medical and health resources. Inclusion criteria: (1) doctors or nurses working in clinical departments; (2) engaged in nosocomial infection prevention and control; and (3) informed and voluntary participation in the study. Exclusion criteria: management personnel.The survey was conducted from September 17 to September 19, 2020. We invited all comprehensive medical institutions in Hubei province to participate in the Training course on hospital infection management in the form of online learning. The survey was conducted before the start of the training course. Before the investigation, the link to the questionnaire was posted on the home page of the live broadcast platform. Then, the purpose and content of the survey were explained to respondents through an online medium. It was emphasized that the study was to improve the status quo of IPC management in hospitals. Each respondent was required to fill in the questionnaire according to their actual condition. Whether to fill in the questionnaire is voluntary and will not affect the subsequent study. The online meeting lasted for 3 days, and the data was exported and analyzed before 24:00 every day.To ensure the quality of data, we adopted the double-check method according to the following requirements: All items were set as “required questions” to guarantee the completeness of the questionnaire. Users from each IP address only had one chance to participate in the investigation. The answer time was longer than 1 min.The questionnaire was developed based on the tools of leadership attention, incentives and improvement in the field of hospitals safety, and the characteristics of the IPC field. The self-report questionnaire consisted of four parts: demographic characteristics, leadership attention, incentives, and self-perceived continuous improvement in IPC. Demographic characteristics were collected, including clinical department, gender, age, professional title, working years, title, education level, etc. The measurement variables included Leadership attention, Incentives in IPC, and self-perceived continuous improvement in IPC. Items were scored on a five-point Likert Scale from 1 “strongly disagree” to 5 “strongly agree.” The higher the score, the more leadership attention and the better incentives and self-perceived continuous improvement in IPC.Leadership attention was measured with three items adapted from Patient Safety Climate in Healthcare Organizations (PSCHO)  and the Incentives in IPC was measured with four items adapted from PSCHO  and the After a HAI incident occurs, whether the organization can learn from it and optimize and improve it in an orderly manner is crucial to avoid the recurrence of similar hospital infection incidents . FeedbacSelf-perceived continuous improvement in IPC was measured with four items adapted from Hospital Survey on Patient Safety Culture (HSOPSC)  and conc2 = 38,655.00, df = 55, P < 0.000), suitable for factor analysis. The KMO value of leadership attention, incentives, and self-perceived continuous improvement in IPC was >0.6 and P < 0.05, indicating that the data met the requirement of factor analysis. The factor loading coefficient of each item was >0.6, which showed that the extracted common factors are highly correlated. When using real-world data to verify and evaluate the theoretical model, χ2 is susceptible to sample size. The larger the sample size, the more significant the results, and the easier to reject the theoretical model (2/df , which indicated the structure validity is good.The overall Kaiser–Meyer–Olkin (KMO) value of the questionnaire was 0.932. The Bartlett sphericity test was significant  (S-X2 were up to standard (P <0.05). Therefore, the questionnaire adopted in our study has good differentiation, appropriate difficulty and reasonable options.We adopted the graded response model (GRM) of Item Response Theory (IRT) to assess the differentiation, difficulty, information function and t Index)  of the qp < 0.05 was considered to be statistically significant.Descriptive statistics and Pearson's correlations were calculated using SPSS 26.0 for leadership attention, incentives, and self-perceived continuous improvement in IPC. Amos 24.0 was used to establish a structural equation model between leadership attention, incentives, and self-perceived continuous improvement in IPC to test the mediating effect of incentives in the relationship between leadership attention and self-perceived continuous improvement in IPC. Path coefficients were used to examine the action paths of leadership attention on improvement (including direct and indirect effects). The Bootstrap method was adopted to test the mediation effect. The sample size was selected as 5,000. Under the 95% confidence interval, if the result of the mediation test contained 0, it indicated that the mediation effect of IPC incentives was not significant; if the result of the mediation test did not contain 0, it suggested that the mediation effect of IPC incentives was significant. In this study, This study was approved by the Ethics Committee of Tongji Medical College, Huazhong University of Science and Technology (No: 2020S252). All participants were enrolled in the investigation using the principles of informed consent and confidentiality.2/df = 134.04, RMSEA = 0.20, RMR = 0.11, NFI = 0.85, RFI = 0.81, CFI = 0.85, IFI = 0.85, TLI = 0.81), which indicated there was no significant bias.Common method variance (CMV) is the systematic error variance shared among variables measured with the same source or method. This systematic error variance could also bias the estimated relationships among variables or measures . To testA total of 4,000 medical staff in clinical departments participated in the survey, 3,512 of which were remained, whereas 488 were removed because the answers to all 11 items in a questionnaire were the same or because the questionnaire was not filled out by doctors or nurses, or the answer time was <1 min. The effective response rate was 87.80%. 16.00% were male, and 84.00% were female. The average age was 30.52 ± 1.26 (mean ± SD). 25.60% were doctors, and 74.40% were nurses. 77.73% had a bachelor's degree or above. 53.22% worked for more than 5 years. 45.02% have intermediate or higher professional titles. 76.82% of them had contact with hospital-infected patients. There were no significant differences in scores of demographic variables among different groups on self-perceived continuous improvement in IPC, which indicated that demographic variables did not affect the level of IPC improvement. The specific demographic characteristics are shown in r = 0.54, p < 0.01), and correlated with self-perceived continuous improvement in IPC . Incentive in IPC was positively correlated with self-perceived continuous improvement in IPC .The correlations for each factor are presented in p < 0.01), leadership attention and incentives in IPC , incentives in IPC and self-perceived continuous improvement in IPC  were all statistically significant.p < 0.01), the direct effect was 0.72 , and the indirect effect was 0.13 . Hence, incentives in IPC had a mediating effect between leadership attention and self-perceived continuous improvement in IPC, the mediating effect was 13%, and the mediating effect accounted for 15% of the total effect.Five thousand bootstrap tests were performed on the mediation effect, and the results showed that the path differences in the model were statistically significant . The totThis study examined the direct (0.72), indirect (0.13), and total effects (0.85) of leadership attention on self-perceived continuous improvement in IPC mediated by incentives among medical staff. Our findings expand the existing literature by demonstrating the mediating role of incentives on the association between leadership attention and self-perceived continuous improvement in IPC.This study constructed a tool with good reliability and validity for measuring leadership attention, incentives, and self-perceived continuous improvement in IPC. This study was the first to quantitatively describe the level and distribution of these three variables after COVID-19. The results showed that the scores of leadership attention, incentives, and self-perceived continuous improvement in IPC were high after COVID-19, and the score of leadership attention was the highest. The possible reason may be that medical institutions pay more attention to IPC work, and the management mode of full participation of medical staff in IPC in hospitals has been widely used after COVID-19 . The curFurthermore, compared with the score of leadership attention and self-perceived continuous improvement in IPC, the overall score of Incentives in IPC was relatively low, indicating that the effect of the incentive system was limited and needed continuous improvement although hospital and department managers attached great importance to IPC work. Studies showed that some hospitals still used punishment as the primary management method for IPC work in hospitals, which was repellent to medical staff and even hindered IPC work in hospitals . Good asThis study showed that leadership attention positively affected self-perceived continuous improvement in IPC (H1), which was consistent with previous studies. Nguyen et al.  pointed One of the most important findings of this study was to confirm that incentives in IPC mediated the effect of leadership attention on self-perceived continuous improvement in IPC (H4). That indicated that leadership attention not only positively affected self-perceived continuous improvement in IPC directly, but also positively affected self-perceived continuous improvement in IPC indirectly mediated by incentives in IPC. The mediating effect of incentives in IPC can be understood from the following two aspects. On the one hand, leadership attention can positively affect incentives in IPC (H2) (Direct effect: 0.76), which was similar to previous studies. Basahel  proved tBased on the above, incentives in IPC mediated the relationship between leadership attention and self-perceived continuous improvement in IPC (the mediation effect: 0.13). Some studies have proved the mediating role of intrinsic motivation in leadership attention and continuous improvement. Hersona et al.  confirmeThe strength of our study is that we are the first to quantitatively describe the level and distribution of leadership attention, incentives, and self-perceived continuous improvement in IPC and to elaborate on the mechanism of leadership attention on self-perceived continuous improvement in IPC from the perspective of organization management. Moreover, the sample size of our study is large, which is rarely seen in previous studies. However, there are several limitations. First, the measurement tool in this study adopts self-reported, and there may be situations where subjects overestimate or underestimate measured variables. But in the absence of objective measurement tools, subjective measurement is an alternative. Future research could try to construct more objective measurement tools. Second, the participants of this study are from one province, and this is a cross-sectional study, which may affect the generalization of this research. Future studies can further expand the scope of the survey and design a prospective cohort study to confirm our study. Third, we didn't do re-test reliability because online surveys couldn't guarantee that participants of the two surveys was the same person. In the future, a field survey can be conducted to verify test-retest reliability. Fourth, our study only investigates the effect of leadership attention on self-perceived continuous improvement in IPC from the perspective of organization incentives. Future research also needs to explore the relationship between self-perceived continuous improvement in IPC and the actual improvement. Fifth, our study was conducted during the pandemic. The level of leadership attention, incentives, and self-perceived continuous improvement in IPC may be overestimated, but the mechanism of leadership attention affecting self-perceived continuous improvement in IPC will not change because of these backgrounds.Leadership attention positively affects self-perceived continuous improvement in IPC, and incentives mediate the relationship between leadership attention and self-perceived continuous improvement in IPC. This finding offers recommendations that strengthening leadership construction and improving incentives systems in IPC are effective ways to enhance the effect of self-perceived continuous improvement in IPC.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by the Ethics Committee of Tongji Medical College, Huazhong University of Science and Technology (No: 2020S252). The patients/participants provided their written informed consent to participate in this study.LW conducted the literature review, took part in the investigation, contributed to the data cleaning, performed formal analysis, and wrote the original draft. DZ, JC, XL, and XZ designed the study, obtained funding, contributed to the interpretation of the results, and performed revisions of the manuscript. JL, YT, QZ, FZ, and QW contributed to the data cleaning and performed revisions of the manuscript. All authors contributed to the article and approved the submitted version.


Background: Inappropriate antibiotic use for SARS-CoV-2 infection has the potential to increase the burden of antibiotic resistance. Brazil experienced spread of a new SARS-CoV-2 variant in the fourth quarter (Q4) of 2020, resulting in the highest case counts in Latin America, raising concerns of antibiotic overuse. To better understand antibiotic use during the COVID-19 pandemic, we evaluated prescribing changes in antibiotics commonly used for outpatient respiratory infections  among adults aged ≥20 years in Brazil in 2020 versus 2019. Methods: We analyzed the IQVIA MIDAS medical data set for AALM prescribing by age group , comparing Q4 2020 rates to those in Q4 2019. We estimated crude rate ratios and 95% CIs using prescription number as the numerator (assuming Poisson counts) and age-adjusted population as the denominator. We also determined the most common prescribing specialties for each antibiotic across both time points. Results: Compared to Q4 2019, Q4 2020 azithromycin prescribing increased among all ages, ranging from 90.7%  in those aged 20–39 years to 927.2%  in those aged 65–74 years (Fig. Conclusions: Despite decreases in prescribing of amoxicillin-clavulanate and respiratory fluoroquinolones for most adults, azithromycin prescribing increased dramatically across all adults during the COVID-19 pandemic. Targeting inappropriate outpatient antibiotic use in Brazil, particularly azithromycin prescribing among general practitioners, gynecologists, and surgeons, may be high-yield targets for antibiotic stewardship.Funding: NoneDisclosures: None


Treating pneumonia in old patients remains challenging for clinicians. Moreover, bacterial antimicrobial resistance is a major public health threat.The PROPAGE study evaluated the interest of a strategy using serial measurements of procalcitonin (PCT) to reduce the duration of antibiotic therapy in old patients with pneumonia.PROPAGE took place from Dec.-2013 to Jun.-2016 in eight French geriatric units. It was a prospective, comparative, randomised, open-label study involving old patients (≥ 80 years) who had initiated antibiotic treatment for pneumonia in the previous 48 h. PCT was monitored in all patients and two decision-making PCT-based algorithms guided antibiotic therapy in patients from the PCT group.n = 50; Control, n = 57). Antibiotic therapy exposure was reduced in the PCT group as compared to the Control group  and no significant difference was found in recovery rate .107 patients were randomised (PCT, Although, the superiority of the strategy was not tested using a composite criterion combining antibiotic therapy duration and recovery rate was not tested due to the small sample size, the present study showed that monitoring associated with PCT-guided algorithm could help shorten antibiotic treatment duration in the very old patients without detrimental effects. Measuring PCT levels between Day 4 and Day 6 could be helpful when making the decision regarding antibiotic discontinuation.NCT02173613. This study was first registered on 25/06/2014.The online version contains supplementary material available at 10.1186/s12877-022-03658-4. The rate of hospitalisations due to infectious diseases rises with age, reaching its highest incidence in those above 85 years of age. According to a recent systematic review, in industrialised countries, hospitalisations due to pneumonia have more than doubled in each consecutive age range going from 6.8, to 16.4, and to 34.6 episodes/1000 persons/year in patients aged 65–74, 75–84, and > 85 years, respectively . Addition = 6481) in the United States, two-thirds of patients hospitalised with pneumonia received excess antibiotic therapy. Notably, each additional day of antibiotic therapy was associated with a 5% increase in the risk of antibiotic-associated adverse events [Infectious diseases such as pneumonia are not only more frequent and severe in old people, but also have different characteristics . Diagnose events .Clostridium difficile, and microbiome alterations [In France, excess antibiotic use both in hospitals and in the community is also a remarkable problem. Mean antibiotic consumption rates are consistently above the European average despite national healthcare system campaigns to decrease antibiotic overuse. However, these campaigns were not as successful as expected in old people possibly because comorbidities which are frequent in this population trigger empiric antibiotic treatments . Despiteerations , 6.The limitation of antibiotic use in old people is, therefore, a major issue. One way to prevent problems related to extended antibiotic use without altering patient prognosis is discontinuing antibiotic treatment early . Immune PROcalcitonine chez les Patients AGEs) was an interventional, randomised, comparative, open-label study involving old patients admitted for pneumonia to eight geriatric units .PROPAGE  they had an associated endovascular or chronic infection, or a lung abscess upon admission; (3) they had severe immunosuppression; (4) they were under palliative care; (5) they were deceased 24 h post-admission; or (6) they were receiving antibiotics for a chronic infection.Geriatricians and/or infectious disease specialists agreeing to participate in the study included all volunteer patients admitted in their unit provided (1) they were ≥ 80 years of age, (2) they had initiated antibiotic treatment for pneumonia in the previous 48 h, and (3) their PCT levels were evaluated prior to treatment initiation on Day 0. Pneumonia was previously defined by the presence of at least 2 clinical signs of pneumonia and based on the results of X-Ray or scanner. Patients were not included if (1) they had an infection due to a virus, parasite, At inclusion, patients were randomised into two groups (1:1): i.e., PCT and Control groups. Randomisation was centralised via electronic case report forms (eCRFs) once eligibility was verified. Stratification was by centre and balanced by random size blocks.PCT was assessed on patients from both the PCT and Control groups on Days 2, 4, 6, and 8 post-admission, and then after discharge or on Day 15 with the miniVidas® B.R.A.H.M.S PCT device  and PCT kits. PCT results were immediately transmitted to the physicians. They guided antibiotic treatment for patients in the PCT group, only. Patients assigned to the PCT group received an antibiotic regimen that was terminated early according to clinical evaluation algorithms guided by PCT levels. Patients assigned to the Control group received a conventional antibiotic regimen that was terminated according to treating physician’s discretion. Once discharged, patients were followed via telephonic interviews at 6 weeks (Week 6). Interviews were performed by the investigators.Société de pathologie infectieuse de langue française) [In the PCT group, single decision-making PCT-based approach with 2 consecutive algorithms to guide antibiotic therapy were used to assess patients Fig. . Physiciançaise) ; PCT meaThe PCT-based algorithms were considered useful if they significantly shortened antibiotic treatment duration. Treatment failure and recovery rates on Day 45 were determined in each group and compared. Infection relapse or death from any cause were considered therapeutic failures. Recovery rate was defined as complete if, according to the physician judgement, no clinical sign of pneumonia persisted; otherwise, recovery was partial.Demographic data, nutritional  and funp = 0.05). The main analysis was performed on the intention-to-treat (ITT) population. A secondary analysis was performed on the per protocol (PP) population. ITT population included all randomised patients complying with all inclusion criteria and none of the non-inclusion criteria with available PCT evaluation on Day 2; patients from the ITT population whose antibiotic treatment did not respect the PCT-based algorithms were excluded from the PP population.All statistical analyses were performed with Stata . A descriptive statistical analysis at baseline was performed for all collected variables and results were reported as mean  or median  if appropriate for continuous variables, and count  for qualitative variables. Usual parametric and non-parametric tests were used for group comparisons. All tests were two-sided at the 5% level of significance  of the teaching hospital of Grenoble on 05 October 2011 . All patients  gave their informed consent for participation before being included in the study . This trial is registered in ClinicalTrials.gov .PROPAGE was conducted in compliance with the International Conference on Harmonisation-Good Clinical Practice Guidelines and the applicable regulatory requirements. The protocol was authorised by the PROPAGE took place from December 2013 to June 2016. As shown in the participant flow diagram , while the patients in the PCT group had higher leukocyte counts and slightly worse pain. Lastly, almost 80% and 84% of the patients in the Control and PCT groups had PSI scores indicating hospitalisation (IV and V), the rest had a score that indicated they could benefit from a brief hospitalisation (III). None of these differences was statistically significant. Finally, mean (SD) PCT levels measured before initiation of antibiotic therapy were 2.6 (6.70) ng/ml in the PCT and 4.8 (12.73) ng/ml in the Control group .As the study was randomized, no statistically significant difference was observed between groups in baseline characteristics (Table p = 0.001). The recovery rate on Day 45 in the PCT group (84%) was lower than that of the Control group (89.5%), but no statistically significant difference was observed in recovery rate between the two groups . As no relapse was reported, mortality rates were 16% and 10.5% in the PCT and Control groups, respectively. Serum PCT levels decreased rapidly between inclusion and Day 4 in both groups and then reached a plateau. PCT levels and their evolution over time were not significantly different between the two groups  , the median duration of antibiotic treatment in the PCT group was 8 days (IQR: 6–11 days), which was significantly shorter than in the Control group . The recovery rate in the PCT group was slightly higher in the PP than in the ITT population (86.2% vs. 84%) but remained lower than in the Control group (86.2% vs. 89.5%). PCT changes over time were similar than that in the ITT population and no statistically significant difference was observed between the PCT and Control groups .Overall, 35 patients (20 in the PCT group and 15 in the Control group) reported at least one adverse event leading to death  and/or requiring hospitalisation or prolongation of existing hospitalisation or leading to permanent or significant disability/incapacity . Of the 47 reported adverse events, 9, 9, 8, and 7 were respiratory, thoracic, or mediastinal disorders , cardiac disorders (4 and 5), psychiatric disorders (6 and 2), and infections or infestations (3 and 4).2, and eosinophil counts). The completion rates of disease severity questionnaires were between 66% (APACHE II) and 100%. Lastly, the completion rates of functional autonomy questionnaires were between 37% and 68%.Regarding missing information, data completion rates at baseline were between 87% and 100% for most clinical parameters and 37% and 68% for three parameters  . The algIn terms of magnitude of the reduction in treatment duration, these results are consistent with previously reported data despite the particularity of this trial as it only recruited very old people with high Fine and CURB-65 scores. The effectiveness of PCT-based algorithms to guide antibiotic pneumonia treatment has been demonstrated in several randomised trials performed in different patient populations and clinical settings, ranging from primary care to emergency departments .Analysing 26 trials including 6708 patients with respiratory infections across different clinical settings, a recent Cochrane review  found thRandomised clinical trials differ with respect to cut-off PCT levels for discontinuation, populations enrolled, and antibiotic treatment duration in the control groups. The randomised-controlled study by Schuetz et al. (ProHOSP)  is the lThe particularity of the present study lies in the population enrolled because it represents a typical population of short-stay patients hospitalised in France in Geriatric Units. They were very old (≥ 80 years), disabled, vulnerable, with poor nutritional status or at risk of malnutrition. As expected, most of the population exhibited impaired cognitive function, declined functional status, high severity scores, and respiratory decompensation upon their presentation. Notably, the atypical presentation of pneumonia and the difficulties in re-assessing the evolution of these patients often lead to inappropriate antibiotic initiation and longer antibiotic duration. Because of the presence of several comorbidities that blur infection status and hamper clinicians’ ability to make an accurate clinical assessment and correct diagnosis, prolongation of antibiotic treatment is frequent as was the case in the present study. Moreover, prolonged antibiotic treatment underlies adverse reactions and antibiotic resistance . AntibioThere are some limitations to this study that clinicians should be aware of before using PCT in their own practice. The small population size and the short follow-up period (45 days) may have impacted the generalisation of the results due to possible uncontrolled bias resulting from the very particular study population. Although this patient population is representative of day-to-day care, larger and longer-term studies are needed to examine the way PCT is being used and its impact in real-world settings in this highly specific population. The small population size was responsible for the abandonment of the initial primary objective of the study. Indeed, the primary objective was initially to demonstrate that, as compared with the usual antibiotic treatment strategy, the strategy based on PCT monitoring shortened antibiotic treatment duration with at least equivalent recovery rates. The primary evaluation criterion was thus composite combining a superiority test for antibiotic therapy duration and a non-inferiority test for recovery rate. However, with an attrition rate of 10%, 340 patients were to be included in the present study to demonstrate a recovery rate of 84% in each group and a non-inferiority threshold of 10% for a 3-day difference in antibiotic therapy durations between the two groups with a power of 80% and an alpha-risk of 5%. Even after a 12-month extension of the recruitment period, only 117 patients could have been included in the present study. No hypothesis was therefore tested, and data were analysed as presented in “Material and Methods”. In addition, non-compliance rate was high (48%). At the time of the study, PCT assays were rarely performed, which probably partly explains the small sample size, and encourages us to emphasise on the need of assessing PCT levels to follow antibiotic treatment. Moreover, physicians were not used to guide antibiotic treatment on PCT levels and could be afraid to use the method including despite having agreed to participate in the study. This could be particularly true as the in-force recommendation stated to continue antibiotic therapy until recovery and as included patients were frail. This possibly explained both the small sample size and the high non-compliance rate. However, it was in accordance with that reported in previous trials  but equiThe present algorithm could be used in viral pneumonia  with suspicion of bacterial coinfections to promote early discontinuation of antibiotics. Recent studies have showed that in COVID-19 patients, antibiotic inappropriateness was very high, suggesting that PCT or PCT-changes could be used during the first 3 days from admission to help physician to decide (or not) antibiotic therapy initiation , 39.Finally, the present study showed that a PCT-guided algorithm could help reduce antibiotic treatment duration (from 10 to 8 days) in very old patients without detrimental effects. Identifying and diagnosing pneumonia in very old patients remain major challenges for clinicians as this patient population often presents atypically clinical signs. Facing these difficulties and considering the obvious risk of delaying antibiotic therapy in this high-risk population of patients, physicians usually prescribe antibiotic treatment. This PCT-guided algorithm could help physicians in their decision to stop antibiotic treatment, avoiding needlessly prolonged antibiotic treatment and therefore participating in the prevention of AMR. Further researches to determine the optimal PCT algorithm used in different situations and infectious syndromes are sorely needed in this very old patient population. Moreover, it seems necessary to disseminate information on the use of PCT-guided algorithm to effectively raise people’s awareness of this practice and improve their adherence.Additional file 1.Additional file 2.


This study is applied to the Yangtze River shield crossing project of the Sino-Russian Eastern Gas Pipeline, and ANSYS was used to simulate the stress and deformation of the foam concrete. This work provides an efficient foam concrete optimization mix scheme, and supports the application of foam concrete in the filling of the long-distance cross-river natural gas tunnels.The shield tunnel is a common solution for natural gas pipelines crossing rivers. Consequently, the development of natural gas tunnel filling materials with excellent performance is crucial to the safe operation and maintenance of pipelines. The foam concrete offers a reasonable solution. Nevertheless, since its inherent compressive strength decreases almost proportionally with the decrease in density, obstacles remain concerning obtaining the high density and relatively low strength required for natural gas tunnel filling. Here, a synergistic optimization strategy was proposed involving the orthogonal test, univariate control, and comprehensive balance method. It involves modifying the type and proportion of cementitious matrix, in particular by incorporating fly ash and PVA fibers in the mix design, and synergetic determining the best mix ratio from the aspects of compressive strength, stability, and dry density. The obtained foam concrete has a compressive strength of 4.29 MPa (FC4) and a dry density of 1060.59 kg/m Natural gas resources are unevenly distributed worldwide, and therefore natural gas transmission pipelines are essential for the reallocation of these valuable resources. The construction of natural gas transmission pipelines often passes through a variety of complex terrains. A shield tunnel is the main solution for river crossing, the annular space between the tunnel wall and the natural gas pipeline is usually filled to protect the pipeline while facilitating operation and maintenance. Water, air, and controllable low-strength materials are the main tunnel-filling materials at present . ThereinFoam concrete is a lightweight porous material made by introducing air bubbles into the slurry mixed with cementitious materials, admixtures, and water . Due to With the development and application of foam concrete in many fields, its shrinkage cracking and poor mechanical strength have become obstacles. Therefore, extensive exploration has been carried out around performance optimization ,11,12,13As discussed above, foam concrete shows good performance improvability. After filling the tunnel with foam concrete, the resistance to deformation of the natural gas pipeline is improved, and the compressive strength shall not be lower than the transmission pressure of the pipeline. Nevertheless, based on the design concept of the whole life cycle, the tunnels filled with foam concrete are exempt from routine maintenance, but emergency excavation for repair should be considered, so the strength of the foam concrete should be as low as possible when complying with the pressure in the natural gas pipeline. Additionally, considering the anti-floating demand of the pipeline, the density of foam concrete needs to be dense enough. Nevertheless, its inherent compressive strength decreases almost proportionally with the decrease in density . Althoug3 (A11). It is important to verify the safety and reliability of the filling structure. The stress and deformation of foam concrete under the operating pressure of natural gas pipeline were simulated by ANSYS. The synergistic optimization of this investigation is conducive to obtaining the optimal mix ratio of foam concrete suitable for different filling projects, and foam concrete with optimized performance is a promising filling material for natural gas tunnels.Herein, in order to achieve the excellent filling effect, a synergistic optimization strategy of foam concrete mix ratio suitable for the filling of long-distance natural gas tunnels was proposed. Given the application of the Yangtze River shield crossing project of the Sino-Russian Eastern Gas Pipeline, by incorporating fly ash and PVA fibers in the mix design, the cementitious matrix was properly modified to achieve reasonable mechanical strength and density. The method of orthogonal test and controlling a single variable was used to synergetic determine the best ratio of water-cement ratio, fly ash substitution level, foaming agent dilution ratio, and superplasticizer from the aspects of compressive strength, dry density, and stability. Next, the PVA fibers were incorporated to prevent shrinkage and cracking of the bulk filler. The tested compressive strength of the optimized foam concrete was 4.29 MPa (FC4) and the dry density was 1060.59 kg/mCement and fly ash were obtained from Qingdao Weidong Hongyuan Building Materials Co., Ltd.  Three types of silicate cement were studied in this study, and their basic properties are shown in 3 were then added to the slurry to obtain the target density. The slurry was continued mixed at low speed for 2 min until the foam was well mixed with the slurry. The wet capacity of the foam concrete slurry in the fresh state was measured before casting, and finally, the specimens were poured into 40 mm × 40 mm × 160 mm and 100 mm × 100 mm × 100 mm molds brushed with lubricant and scraped calmly, and the specimens were demolded after 48 h and cured naturally until the specified age for performance testing.Foam concrete was prepared by the pre-foaming method  as folloIn the orthogonal test, water-cement ratio (A), fly ash admixture (B), foamer dilution ratio (C) and water-reducing agent admixture (D) were selected as four factors, and four levels were set for each factor. Details of the orthogonal test are shown in The 28 d compressive strength of foam concrete specimens was tested according to JC/T 266-2011 (Chinese industry standard). The specimen size was 100 mm × 100 mm × 100 mm. The test was performed on an electro-hydraulic universal testing machine  with a loading rate of 2 kN/s, and the average value of three specimens was taken as the compressive strength.The ratio of compressive-flexural strength is the ratio of compressive strength to flexural strength of the test block, which is used to reflect the anti-cracking performance of foam concrete. According to GB/T17671-2021 , the test block size was 40 mm × 40 mm × 160 mm. The test blocks were placed into the flexural jig and loaded on the upper surface of the flexural jig until the prismatic body fractured in the middle, with a loading rate of 50 N/s. The test blocks after fracture were taken for compressive strength testing with a loading rate of 2400 N/s ± 200 N/s, and the load was applied uniformly until the prismatic test blocks broke. The average values of three specimens were taken to calculate the compressive-fractural strength ratio.0, and the measuring cup was gently tapped to allow close packing of the slurry. The excessive slurry was scraped flat along the mouth of the measuring cup with a straightedge. The weight of the slurry (W0) was calculated after deducting the weight of the empty cup. The wet capacity was calculated as W0/V0. After being cured under natural conditions for 28 d, the hardened concretes were put into the drying oven and dried to constant weight, then taken out and placed in the room for cooling, and subsequently weighed to calculate their dry density.The wet and dry densities of the foam concrete were measured in the fresh and hardened states, respectively. The fresh foam concrete slurry was poured into a measuring cup with volume VCompressive strength is an important index that affects the application performance of foam concrete. Its low compressive strength is not conducive to providing sufficient support and protection for the pipeline. On the contrary, its high strength will make emergency repair difficult. The range analysis is carried out on the 28 d strength test results of the orthogonal test, and the compressive strength range analysis trend chart is made according to the range values of each factor, as shown in In order to directly reflect the impact of each factor level change on the 28 d compressive strength, the trend chart of factors and indicators is drawn as shown in Due to the small inner diameter of the natural gas tunnel and the arrangement of gas pipelines inside it, the slurry should be self-leveling, and therefore self-compacting foam concrete should be used. The self-compacting foam concrete is required to have high stability, which can be characterized by the foaming volume ratio (slurry wet density/dry density). The stability of the foam concrete is better if the foaming volume ratio is close to 1 and there is no segregation and water secretion during the mixing and setting of the slurry . The ranThe influences of the change of factors on the stability of foam concrete are further analyzed, as shown in According to the target compressive strength and stability of foam concrete, the optimal level combinations of factors are different. Based on the results of compressive strength and stability extreme difference analysis, the comprehensive balance method was used to compare the four factors respectively, the analysis process is shown in Compressive strength is one of the crucial properties when foam concrete is applied to fill natural gas tunnels. Foam concrete with high compressive strength provide greater restraint on a natural gas pipeline, and the filled tunnel can provide better bearing capacity to protect the pipeline. However, too high a strength can cause difficulties in emergency tunnel excavation and repair. From the test results of the standard mixing proportion, it can be seen that the compressive strength of the foam concrete is large than the target compressive strength FC4, and further optimization is thus needed to make it meet the target requirements. At the same time, the dry density is an important performance index in the optimization process. The density of optimized foam concrete should reach the grade requirement of A11 to prevent a pipe from floating.From the results of the multi-factor test, it is clear that the water-cement ratio is the most important factor affecting the compressive strength of foam concrete. In order to optimize the compressive strength to meet the target requirements, further single-factor optimization of the water-cement ratio was carried out. It can be seen that the compressive strength of foam concrete changes sensitively when the water-cement ratio is varied in the range of 0.35 to 0.45 a, and th3, both of which are slightly lower than the target values. The type and usage of cementitious materials are the key factors affecting the performance of foam concrete. Fly ash, as supplementary cementitious material with a smaller particle size than cement, can regulate the particle gradation of cementitious materials and optimize carbon emission at the same time. As seen from 3, respectively, which are close to the target values. The prepared foam concrete has a low cost.The compressive strength of the foam concrete obtained after water-cement ratio optimization is 2.67 MPa and the dry density is 1028.59 kg/mThe foam concrete produced after optimization shows fine cracks on the surface a, indica3 (A11), which meets the requirements of the target performance. Meanwhile, the strength of foam concrete develops very fast and has good anti-cracking performance, which can be applied to long-distance tunnel-filling applications.Therefore, based on the comprehensive analysis above, the optimized mixing proportion of foam concrete is shown in The Yangtze River crossing project of the China–Russia East Line is characterized by long crossing distances and a large diameter natural gas pipeline arranged in the tunnel, which makes the foam concrete have a larger filling volume and complex structure. In order to ensure the safety and stability of the tunnel as a whole during the operation phase and avoid the damage of foam concrete due to excessive stress or deformation, the ANSYS software is used to simulate the actual working conditions of foam concrete during the operation phase of the tunnel, so as to ensure that the foam concrete with optimized mixing proportion meets the requirements of engineering applications. The constitutive relationship of foam concrete under uniaxial compression is the main basis for the selection of each parameter index for finite element simulation, which can fully reflect the basic characteristics of foam concrete such as strength and elastic-plastic deformation ,41. FoamThe stress-strain curve to a certain extent reflects the changes in the internal structure during the uniaxial compression damage of foam concrete. Combined with Taking the peak compressive strength as the dividing point, the typical stress-strain curve is divided into ascending and descending segments. According to the shapes of the rising and falling sections, the curves are fitted by segments, with the rising section being fitted in two parts and the falling section being fitted by a polynomial cubic. The uniaxial compressive stress-strain constitutive equation of optimized ratio foam concrete is shown in Equation (1).The ANSYS software was used to simulate the working conditions of the foam concrete filler during operation, and foam concrete in a horizontal section of the tunnel was selected for analysis. The shield tunnel lining concrete, natural gas pipe, and foam concrete are all isotropic linear elastic materials, and the material properties are assigned according to the material properties as shown in The overall plastic strain and stress in the foam concrete filled in the natural gas transmission tunnel during operation are shown in (1)The significance of the effects of various factors on the compressive strength and stability of foam concrete is consistent. The factors, in the decreasing sequence in terms of their significance, are water-cement ratio, water-reducing agent addition, foam dilution ratio, and fly ash addition. The increase in water-cement ratio and water-reducing agent can significantly improve the compressive strength and stability of foam concrete within a certain range. This is mainly because the two factors influence the hydration of cementitious materials and the stability of foams in slurry. There is an optimal dilution ratio of a foaming agent to obtain the best foam stability, which is conducive to improving the compressive strength and stability. The appropriate amount of fly ash can improve the pore structure and thus increases the compressive strength and stability of foam concrete.(2)3 (A11). The ANSYS simulation results show that the maximum deformation of foam concrete during the operation of the natural gas pipeline is 1.61 mm, and the maximum stress does not exceed 3.5 MPa. Plastic damage of foam concrete will not take place during operation. The designed foam concrete meets the safe operation demand for natural gas pipeline tunnel filling projects.The dry density increases almost proportionally with compressive strength, and the addition of PVA fiber can improve compressive strength and flexural strength, and significantly improve the anti-cracking performance of foam concrete. Based on the performance requirements on long-distance river-crossing tunnel, an optimal mixing proportion of foam concrete is proposed as: water-cement ratio of 0.35, fly ash admixture of 25%, 40 times dilution of foaming agent, 0.1% of high-efficiency superplasticizer, and 0.15% of PVA fiber. The compressive strength of the optimized foam concrete is 4.29 MPa (FC4) and the dry density is 1060.59 kg/m(3)The present research work has been only focused on compressive strength, dry density, and stability. Additional properties important in long-distance gas tunnel filling applications such as fluidity, corrosivity, and pipeline adhesion will be explored in a forthcoming study. Moreover, further research will be aimed at high-performance foaming agents and recycled admixtures to make this research environmentally friendly.In this work, the optimum mix ratio of foam concrete suitable for filling long-distance cross-river natural gas tunnels was studied. The orthogonal test and single factor test were carried out to discuss the effects of water-cement ratio, water-reducing agent addition, foam dilution ratio, and fly ash addition on stability and 28d compressive strength. The requirements of dry density and crack resistance have been considered, including three types of cement and PVA fiber. The following conclusions can be drawn as major outcomes of the present study:


It has been established that steel fiber more significantly increases the concrete compressive strength, and both types of dispersed reinforcement increase the flexural strength equally by 27–34%. Also, dispersed reinforcement reduces the concrete abrasion resistance by 15–35% and increases its frost resistance by 50 cycles, which helps to improve the durability of industrial floors and road pavements. The use of steel fiber in an amount of 20 kg/m3 and polypropylene fiber in an amount of 2.5 kg/m3 also increases the concrete corrosion resistance in an acidic environment. In general, dispersed reinforcement with both fiber types has approximately the same technological effect concerning the mentioned applications. However, the use of polypropylene fibers is economically more profitable since an increase in the cost of 1 m3 of concrete with steel fiber reinforcement is from $22.5 to $37.5, and an increase in cost with polypropylene fiber is from $10 to $15.A comparison of the effect of steel and polypropylene fibers on the strength, frost resistance, abrasion, and corrosion resistance in an acidic environment of fiber-reinforced concrete for industrial floors and road pavements was carried out. Steel fibers with a length of 50 mm and a diameter of 1 mm and polypropylene fibers with a length of 36 mm and a diameter of 0.68 mm were used. The amount of steel fiber varied from 15 to 25 kg/m Concrete industrial floors must provide a quality surface for production processes and comfortable, safe human activities. At the same time, they are operated under conditions of multidirectional loads and dynamic influences ,2. RigidAccording to the current standard in Ukraine , concretThe use of fiber reinforcement is a well-known and well-established method for improving important mechanical properties for industrial floor and road pavement concretes. For dispersed reinforcement, different types of fibers are used, most often steel, polypropylene, and basalt ,9,10,11.3 of steel fiber, the compressive strength of concrete pavement was increased by 10–12 MPa, and the flexural strength increased from 7–9 MPa to 15–17 MPa. However, the economic efficiency of the use of steel fiber in pavements, as well as the impact of the fiber on the environment, depends on its amount in the concrete composition [According to many studies, reinforcement with steel fiber makes it possible to most significantly increase the concrete flexural strength and, at the same time, compressive strength. It was shown in  that steposition .The use of polypropylene fibers is also an effective method for improving the concrete properties of industrial floors and rigid pavements. For example, it was shown in  that disIn addition to the above important parameters of the concrete industrial floor’s durability, such as shrinkage, frost resistance, and abrasion, another important characteristic is the acid resistance of concrete. The authors  point ouThus, comparing the effectiveness of steel and polypropylene fibers in concrete industrial floors and road pavements is a crucial task. It is important to consider the corrosion resistance of concrete reinforced with different fiber types since different substances, including acid solutions, can act on pavements. At the same time, it is important to compare the effect of different fiber types on the strength, durability, and cost of concrete ,9,26.-Portland cement CEM II/A-S 42.5 R, manufactured by CRH Ukraine in accordance with ,33;-Granite breakstone with a maximum aggregate size of 20 mm, in accordance with ,35,36,37-Quartz sand with a fineness modulus of 2.75 in accordance with ,36,37;-Polycarboxylate superplasticizer MC-PowerFlow 3200 produced by MC-Bauchemie, Bottrop, Germany, in accordance with ;-Steel anchor fiber with 50 mm long and 1 mm in diameter, and ultimate tensile strength 1150 MPa, produced by Stalkanat-Silur, Odessa, Ukraine, in accordance , Figure -Polypropylene fiber "Baumesh" with 36 mm long and 0.68 mm in diameter and ultimate tensile strength 530 MPa, produced by Bautech-Ukraine (Odessa) in accordance  Figure 1For the fiber-reinforced concrete mixing, the following materials were used:3, and the amount of polypropylene fiber varied from 2 to 3 kg/m3. Such a quantity of each type of dispersed reinforcement was adopted based on the recommendations of manufacturers and production practices.Concrete without dispersed reinforcement was studied as a control composition. Three fiber-reinforced concrete compositions with steel and polypropylene fibers were produced. The amount of steel fiber varied from 15 to 25 kg/mThe compositions of the investigated fiber-reinforced concrete with different fiber types and control concrete are shown in 3 (0.94% of the cement content) to 4.08 kg/m3 (1.13% of the cement content). At the same time, the amount of water in the mixture remained constant for the correct comparison of the fiber-reinforced concrete properties, and the W/C ratio was 0.5.The workability of all the studied concretes and fiber-reinforced concrete mixtures was the same S4 with cone slump of 17–18 cm and determined according to ,42,43. TFor the preparation of fiber-reinforced concrete, a rotary mixer was used. The production and curing of the samples were carried out in accordance with the standards ,45,46. FFor all the studied fiber-reinforced concrete, compressive strength at the age of 7 and 28 days ,47, flex3. Fiber concretes with steel fibers (no. 5–7) were expected to have a slightly higher average density of 2430 to 2440 kg/m3.It was experimentally established that the average concrete density of the base composition (no. 1) and fiber-reinforced concrete with polypropylene fiber (no. 2–4) was approximately the same and was in the range of 2415–2425 kg/mAn important indicator of the difference in the concrete structure of the control and fiber-reinforced concrete composition is that the water adsorption of concrete without fiber (no. 1) was 4.2%. For all fiber-reinforced concrete, the water absorption was lower and was in the range of 3.6–3.8%. Since water absorption is an indicator of the open porosity of concrete, it can be concluded that fiber-reinforced concretes (no. 2–7) have a lower open porosity than concrete without fibers. This can be explained by an increase in the amount of superplasticizer MC-PowerFlow 3200 when using fiber , which a3 and polypropylene fiber up to 3.0 kg/m3.The effect of the steel and polypropylene fibers amount on the compressive strength is shown in As can be seen from the diagram in For concrete industrial floors and pavements, the more important mechanical property is flexural strength since this property determines the bearing capacity of the pavement structure ,5,18,27.3, and with using polypropylene from 2 to 3 kg/m3. The cost of steel fiber is about $1.5 per 1 kg, and the cost of polypropylene fiber is about $5 per 1 kg. Accordingly, the increase in the cost of 1 m3 of concrete due to reinforcement with steel fibers is from $22.5 to $37.5, and the increase in price due to reinforcement with polypropylene fibers is from $10 to $15.The use of polypropylene fibers increases strength by the same amount as the use of steel fibers. However, an important economic effect is that when using steel fiber its amount in fiber-reinforced concrete is from 15 to 25 kg/mIndustrial floors and road pavements are subjected to abrasive action during operation. Therefore, the concrete durability of such structures is largely determined by the abrasion resistance of concrete. 2. This level of concrete abrasion resistance does not meet the requirements of the Ukrainian national standard [2. Due to the introduction of steel fiber, the abrasion of concrete is reduced by 15–31%, and with the introduction of polypropylene fiber by 19–35%.Analysis of the diagram in standard , accordi3 steel fibers or 2 kg/m3 polypropylene fibers makes it possible to achieve the G3 abrasion grade (0.41–0.5 g/cm2), which already allows the use of concrete for rigid road pavements [3, as well as by using 2.5–3 kg/m3 polypropylene fibers, the concrete abrasion grade improves to G2 (0.31–0.4 g/cm2), which increases the durability of road pavements and industrial floors. It is also possible to note the best wear resistance of concretes with polypropylene fibers, despite the significantly lower amount of dispersed reinforcement in concrete by weight. This can be explained by the better adhesion of polypropylene fibers to the concrete matrix compared to steel fibers. Under abrasive action, steel fibers lose their adhesion to the concrete matrix more easily, and polypropylene fibers, due to better cooperation with the matrix and retention of individual blocks of the composite, give the concrete greater wear resistance [Using 15–20 kg/mavements . By incrsistance ,58.The durability of rigid road pavements in the climatic conditions of European and many other countries is significantly affected by the frost resistance of concrete ,21,25,59The value of frost resistance of the studied concretes was determined in accordance with ,53 usinga): specimen with dispersed reinforcement with polypropylene fiber; (b): specimen with dispersed reinforcement with steel fiber.It has been experimentally established that the frost resistance of control concrete composition (No. 1) is grade F150. For all other studied fiber-reinforced concretes (No. 2–9), the frost resistance grade was F200. The experimental data are presented in 3 of material is more economically beneficial.That is, dispersed reinforcement with both steel and polypropylene fibers made it possible to increase the frost resistance of concrete to approximately the same extent. The positive effect of using fibers is explained by the ability of fibers as a stabilizing factor to prevent the separation of concrete as a composite material into separate structural blocks under the influence of freezing and thawing ,59. As sFor industrial floors in a number of chemical industries and other enterprises using acids in the production process, as well as warehouses where substances with acidic properties are stored, an important indicator of the quality of concrete is its resistance to an acidic environment. For road pavements, acid resistance can provide concrete durability when de-icers are used.As noted above, for all the studied fiber-reinforced concrete, the resistance to the acid attack in an acidic environment was determined. For each concrete composition, one part of the samples was kept in water for 6 months, and the second in an acidic environment with pH = 3, Analysis of the diagram in 3 for steel and 2 kg/m3 for polypropylene fibers), dispersed reinforcement has little effect on the strength and does not increase the resistance to the acid attack on concrete. The decrease in the concrete strength of the control composition was 24%, concrete with a small amount of fiber was 26% and 25%, respectively. With a higher amount of fiber, dispersion-reinforced concretes have a strength degree reduction of 23% with using steel fibers and 20–21% with using polypropylene fibers.Under the influence of an acidic environment, the nature of the fiber effect on the concrete strength changes b. DisperSuch an effect of fiber on resistance to acid attack in an acidic environment is explained by the fact that as a result of the reaction of concrete components with acids, calcium carbonate is formed. It is insoluble in water and accumulates in pores and micro-cracks, which leads to concrete cracking ,61. In tIn general, dispersed reinforcement with both steel and polypropylene fibers improves the concrete resistance to acid attack for industrial floors and road pavements.The conducted research allowed us to carry out a comprehensive comparison of the effectiveness of concrete dispersed reinforcement for industrial floors and road pavements with steel and polypropylene fibers.3, and the amount of polypropylene should not be lower than 2.5 kg/m3.It has been established that both types of dispersed reinforcement increase the strength, frost resistance, abrasion resistance, and resistance to acid attack on fiber-reinforced concrete. Steel fibers increase the concrete compressive strength slightly more effectively. In other analyzed indicators of the concrete quality , the use of polypropylene fibers can improve at the same level as the use of steel fibers. To ensure increased resistance to an acid attack on concrete in an acidic environment, the amount of steel fiber should not be lower than 20 kg/m3 of concrete mix using dispersed reinforcement of polypropylene fibers is $12.5–$22.5 less than the increase in cost with dispersed reinforcement with steel fibers. Other advantages of polypropylene fibers compared to steel fibers are less wear and tear of technological equipment during the preparation and placing of the fiber-reinforced concrete mixture, as well as lower energy costs in manufacturing fibers.Dispersed reinforcement with both types of fibers increases the strength characteristics and durability of pavements under operating conditions typical of most European countries. However, due to a significant difference in the effective dosage of different fiber types, the increase in the cost of 1 mOur data complement  notes thIt is important to emphasize that in our experiment, a more aggressive acid attack environment was used, which can be useful for expanding the range of data on the effect of dispersed reinforcement on the concrete acid attack resistance.


The addition of supplementary cementitious materials (SCM), particularly at nano level, leads to several benefits, such as the reduced permeability of concrete matrix, which consequently leads to having more durable and sustainable concrete. The dataset presented in the current paper was collected from two series of experiments. The natural pozzolana used in making concrete mixtures is of volcanic origin; i.e. volcanic scoria. The first series was conducted to test nano natural pozzolana-based concrete specimens on water penetration, while the second one was carried out to investigate the chloride ion penetrability of the latter specimens. Concrete specimens were prepared using nano natural pozzolana of two sizes and six replacement levels. Concrete mixes of four water/binder ratios were prepared. All experiments were conducted after five curing times; namely 2, 7, 28, 90 and 180 days. The collected dataset would be beneficial for concrete mix designers, concrete properties analyzers, construction project managers and scientific researchers. An attempt to correlate water permeability with chloride ion penetrability was made. The first two sheets nominated “WPD-all results” and “CIP-all results” contain the entire results of WPD and CIP tests, respectively, along with the computed average and standard deviation values. The other two sheets nominated “Results of 100 nm-based concrete” & “Results of 500 nm-based concrete” contain the average values of WPD and CIP tests along with some representative figures for concrete specimens prepared with nano natural pozzolana of 100 & 500 nm size, respectively. The fifth sheet nominated “Correlation between WPD & CIP” was constructed to establish a correlation between WPD and CIP. Some further data can be also obtained from Refs. 2The data presented in the current paper are results of experimental tests conducted by the author. Concrete mixtures were prepared with six replacement levels of NNP; namely 0%, 1%, 2%, 3%, 4% and 5%, four water/binder ratios, namely 0.4, 0.5, 0.6 and 0.7. NP was ground to 2 different sizes; i.e. 100 & 500 nm.2 spreading over Syrian, Jordanian and Saudi territories. The chemical composition of NP is presented in Natural pozzolana (NP) was quarried from a region situated at the northeast of Harrat al-Shaam, which is a basaltic volcanic field of about fifty thousand km2/kg with a median particle size of about 15 µm. Its chemical composition is illustated in 3S (61%), C2S (10%), C3A (7%) and C4AF (11%). Its setting times: 162 min  and 224 min .The cement used in concrete mixtures was obtained from Adra Plant “a local cement plant located in Damascus’ northeastern countryside”. It was ground to a Blaine fineness value of 360 mCrushed dolomitic aggregates with three sizes were used in making concrete mixtures. The first size was crushed fine aggregate of a nominal max size of 4.75 mm  (%)=1.57) while the second and third sizes are crushed medium-size aggregate =1.30; Los Angeles (LA) Number=20.5) and crushed coarse aggregate =1.30; LA Number=20.5) of nominal max sizes of 12.5 and 25 mm, respectively. Natural silicious river sand of a nominal max size of 1.18 mm =1.60) was incorporated in order to bring the aggregate blend’ grading as close as possible to the Fuller's grading. Water used in the preparation of all concrete mixtures is a drinkable water.3 of superplasticizer “type F” (ASTM C494) were added to the fresh concrete mixtures of w/b ratios of 0.7, 0.6, 0.5 and 0.4, respectively. The binder content was fixed in all mixtures; i.e. 350 kg binder per one cubic meter. The detailed mixing process can be found in ref. nr. ACI 211 guidelines were adopted in designing the investigated concrete mixtures. Slump values of 150 ± 25 mm were kept in all concrete mixtures. In addition, the percentage of coarse aggregate in the aggregates blend was also kept constant. 0, 5, 2 and 4 l/mC1202 were adopted to test the water permeability of concrete cubic specimens of 150 mm and the chloride ion penetrability of concrete cylindrical slices of (100 mm × 50 mm), respectively.After five curing ages, i.e. 2, 7, 28, 90 and 180 days, all hardened concrete specimens were tested for either water permeability or chloride ion penetrability. The international standards, i.e. EN 12390-8 & ASTM C1202).In the concrete water permeability test, water from the bottom surface was forced to penetrate under a 5 bar-constant presser applied for 72 hours. The concrete specimen was then broken in order to determine the water penetration depth (WPD), Not applicable.The author is the sole responsible for the paper.The author declares that he has no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.