Chronic Endometritis (CE) is a subtle pathology, likely infectious in most cases, with a negative impact on the female fertility, but often overlooked even among fertility specialists. The purpose of the study is to demonstrate the predominant infectious nature of CE and to find the best therapeutic option by comparing the results of oral antibiotic therapy versus intrauterine antibiotic infusion in patients with CE undergoing IVF procedures. The objective was to compare the cure rate of CE—defined as the percentage of patients without CE at the test of cure, between the two groups and, the hysteroscopic aspect with the positive CD 138 staining.This was a prospective, case—control study that took place in a single university fertility clinic, in Oradea, Romania and included 57 patients with CE divided into 2 groups: orally administered antibiotics group who received a combination of antibiotics compared to intrauterine infusion group who received intrauterine infusion of antibiotic. Chronic Endometritis was diagnosed through hysteroscopy and immunohistochemistry for CD 138. Patients in both groups were tested for CE twice to evaluate the cure rate after oral combination antibiotic therapy versus intrauterine infusion of antibiotic.Out of 115 patients with endometrial biopsies 57 tested positive for CE, with a 49.6% chronic endometritis prevalence. Among the group that was administered oral antibiotics, 11 patients (45.83%) experienced CE resolution after triple antibiotic therapy. Of the intrauterine infusion group, 25 patients (89.29%) presented negative results (p 0.0020). The normal hysteroscopic aspect had a similar prevalence in the patients with immunohistochemical positive and negative CD 138.Our study demonstrated the effectiveness and superiority of intrauterine antibiotic infusion over the use of oral combination antibiotic therapy for CE cure.Trial Registration: ISRCTN17542620/14.09.2022. Chronic endometritis (CE) is a subtle pathology, probably infectious in most cases, characterized by an inflammatory state of the endometrium caused by various pathogens: common gram-positive , gram-negative , intracellular  or anaerobic  . ChronicChronic endometritis is also a diagnostics challenge . HysteroThe markers used in the diagnosis of endometritis are MUM1 and Syndecan-1 or CD 138) . In our  . In ourMost likely due to these differences in definition and positive diagnosis, the prevalence of this chronic illness in women that struggle with infertility is variable: from 0.2 to 46% –17. In sAt present, there is also a lot of controversies regarding the management of CE: whether to treat or not to treat and how to treat. Being an infectious disease, the treatment for chronic endometritis is based on the administration of antibiotics that are effective against the bacteria that is causing this chronic problem. After the administration of antibiotics we expect an improvement of the inflammatory changes and endometrial receptivity –24. The Moreover, a new theory about an impaired inflammatory state of the endometrium relying on multiple pathogenic mechanisms, not only infectious but also hormonal and autoimmune could be involved. This would make things even more complicated about this already controversial pathology .In this prospective case control study we aimed find the prevalence of CE in infertile patients and to demonstrate the infectious nature of CE and to evaluate the effectiveness of oral antibiotic therapy compared with local antibiotic therapy for CE cure.This was a prospective, case–control study, conducted at a single university level fertility center in Oradea, Bihor country, Romania during the period of time between 01.01.2021–31.12.2021. This study was conducted under the principles of the Helsinki declaration and has been approved by the ethics committee of Calla Clinic, Oradea, Romania (463/05.02.2020). All patients included have signed an informed consent for their participation in the study. Information given to patients was about side effects of the procedures.We included patients that underwent an IVF procedure in our clinic and compared women diagnosed with CE who received oral antibiotic with women diagnosed with CE who received local antibiotic therapy (infusions) referred to our clinic from 01 January 2021 to 31 December 2021. The patients had the opportunity to choose whether they follow oral or local antibiotic therapy. All patients underwent a second biopsy to control the efficiency of the treatment. We included only women with hysteroscopy diagnosed CE by immunohistochemistry for CD 138. The diagnosis was based on the demonstration > 1 plasma cells per 10 high power fields according to many published studies , 26, 27.Inclusion criteria were: patients that underwent an IVF procedure in our clinic, having various IVF indications that obtained at least two day 5–6 blastocysts and agreed with a hysteroscopic examination.Exclusion criteria were: acute endometritis or other acute pelvic inflammatory disease, placental remanence, steroid and antibiotic treatment within 3 months prior to diagnosis, endometrial cancer or atypical hyperplasia and refusal of procedure (hysteroscopy) or treatment for chronic endometritis.The diagnosis of chronic endometritis is based on a hysteroscopy that is done in the beginning of the menstrual cycle (days 9–11). The guided biopsy during hysteroscopy was then sent for pathological and immunohistochemical examination. In this study the positive diagnosis of chronic endometritis is based on the presence of at least one CD 138 positive plasmacyte per 10 high power fields , 16.The data of the patients was gathered in our clinic by two authors. The register included: age of the patient, cause of infertility, previous pregnancies, hysteroscopic findings, immunohistochemical diagnostic, the type of treatment that had been administered the negative immunohistochemical test after which treatment.Hysteroscopy was done under intravenous general anesthesia, after the disinfection of the perineum with a solution of chlorhexidine and the external cervical ostium with iodine solution after a vaginoscopy to minimize contamination risk. Visualization of the uterine mucosa was done by crossing the cervical canal with a compact hysteroscope CAMPO TROPHYSCOPE® , with a HOPKINS® 30° telescope, size 2.9 mm, length 24 cm, with an irrigation connector and an operation sheath with continuous flux 26.152 DA and 26.152 DB. Entering the uterine cavity we look for two tubal ostium and a panoramic image of the uterus. With biopsy forceps we draw a mucosal probe from the macroscopical modified region . If there are no visible endometrial alterations we extract a biopsy with a catheter  that is crossing under visual control of the cervical canal without any contact with the vaginal wall. The endometrial probes were put in a saline solution (2 mL) and sent to the pathology laboratory for examination.Evaluation of endometrial biopsies was performed from formalin-fixed paraffin-embedded tissue. Samples were sectioned using a Leica RM 2125 RT microtome and processed using the standard hematoxylin and eosin stain (HE). Tissue analysis was performed using a standardized Leica system for image acquisition and analysis—a DM 3000 LED microscope equipped with K3 camera.Tissue specimens were fixed in 10% buffered formalin (pH 7.4) for up to 72 h and paraffin-embedded according to the standard procedures. A 4 μm representative section from each paraffin-embedded tissue was performed according to a standard automated immunohistochemical procedure  . For eacAcute endometritis typically represents ascending infection from lower genital tract. The most common causes are Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis and Mycoplasma species.The differential diagnosis can be done by tissue examination. The acute endometritis reveals the presence of neutrophils infiltrating and destroying endometrial epithelium not plasma cells like in chronic endometritis. Sometimes the neutrophils are organized in microabscess. The different inflammatory cells do the diagnostic easily.The treatment was decided by the patient after a thorough presentation of the method of administration, duration of treatment and side-effects to each patient.a. Oral antibiotic treatment—to have a high range of microorganisms that can cause chronic endometritis covered by the antibiotic we use a combination of 3 antibiotics over a 14 days period of time: ciprofloxacin 500 mg 2 times a day, doxycycline 100 mg 2 times a day and metronidazole 500 mg de 2 times a day [es a day , 29.b. Intrauterine antibiotic infusions—our protocol for intrauterine infusions includes the administration of 3 ml ciprofloxacin 200 mg/100 ml concentration every 3 days with 10 infusions in total across a 30 day period of time for each patient. Infusions were done using Labotect Embryo Transfer Catheter 23 cm .In the follicular phase of the menstrual cycle following antibiotic therapy all women underwent a repeat endometrial biopsy with CD 138 immunohistochemical examination.For the storage of information from the study and for the statistical analysis we used a medical statistics program MedCalc® 12.5.0.0 . Statistical results will be represented by the probability of null (p), a p value under 0.05 underlines a significant difference between the studied groups. Every continuous variable will be checked for the value distribution using the Kolmogorov–Smirnov test. Continuous variables with normal distribution will be represented by average and standard deviation in brackets, and the asymmetrical distribution by median and interquartile range in brackets. Also depending on the variable character parametric tests will be used (Student test for independent lots) or non-parametric (Mann–Whitney test). Comparison between categorical variables were tested using contingency tables and the chi-square test or Fisher`s test when necessary.The primary endpoint consisted in obtaining the prevalence of CE in a population that undergoes an IVF procedure. The secondary endpoint was to compare the rate of CE resolution between the two groups. The tertiary endpoint was to compare the hysteroscopic normal appearance with the presence of chronic endometritis.From the total of 232 patients that presented in the given period of time, 220 remained eligible for treatment, from which only 115 accepted to do the hysteroscopy and the control biopsy. Using the diagnosis criteria 57 cases of chronic endometritis were identified. After they have chosen the treatment 27 patients were included in the oral antibiotic therapy group (OAB) and 30 patients were included in the intrauterine antibiotic infusion group (IAI). Because some patients needed both treatment options to become negative and made part of both groups (the inefficiency of one treatment and changing to the other treatment) 5 more patients were excluded (3 from the OAB group and 2 from the IAI group). The algorithm of the patient selection is shown in Fig. The demographic characteristics of the study population that underwent an IVF procedure are displayed in Table Chronic endometritis prevalence according to the diagnosis criteria is 49.6%. After the diagnosis patients were divided in the oral antibiotic therapy group (OAB) and the intrauterine antibiotic infusion group (IAI). The division of patients according to the treatment option gave us the following results in clinical and demographic characteristics Table :Table 2DAmong oral antibiotic group, 11 patients (45.83%) experienced CE resolution after the triple antibiotic therapy. Among intrauterine infusion group, 25 patients (89.29%) presented negative controls (p 0.0020). The efficiency of the treatment in producing negative CD 138 testing was significantly higher for the patients treated by the intrauterine antibiotic infusion: RR = 1.9481 (IC95%: 1.2–3.06), p = 0.0039 with NNT = 2.301 (IC95%: 1.52–4.71).The hysteroscopic aspects of chronic endometritis are considered to be the classical strawberry pattern but also hemorrhagic spots, focal and generalized hyperemia, pale and edematous mucosa and the presence of micro-polyps as shown in the figure bellow Fig. .Fig. 2HyThe histological evaluation was done by identification of one or more plasma cells in the endometrial stroma. Presence of CD138 positive plasma cells were confirmed by brown colored membranes and cytoplasm , 30. (FiThe normal hysteroscopic aspect had a similar prevalence in patients with the immunohistochemical positive CD 138 as in the group that tested negative at the immunohistochemical CD 138 biopsy for chronic endometritis.The antibiotic treatment had no significant adverse effect either orally or in uterine infusion and the hysteroscopic procedure had no complication including no bleeding or infections.Our study provides new and clinical relevant information for physicians about the management of chronic endometritis that remains an emerging topic regarding its diagnosis, treatment and its impact on the result of fertility treatments, as much as, frequently the microbiological results of vaginal and uterine environment are negative .The hysteroscopic examination as a diagnostic tool is used by many practitioners , 33, butAlthough there is no unanimously accepted definition of CE, pathologists agree that using IHC to determine plasma cells by labeling CD138 is currently the most specific and reliable method. Improvement of the diagnosis rate in CE is achieved by implementation of IHC techniques . BesidesHowever, the use of HPF-related assessment is restrictive and arbitrary in some ways. In the case of small biopsies, the HPF report may lead to false-negative results. Inclusion of only 10 HPFs may not be sufficient to produce a consistently reproducible result, because in most cases the number of plasma cells present in the endometrial stroma is low. From the histological point of view, the most accepted definition of CE is the presence of a single cell labelled CD138 in the entire surface of the sample , 35 and Prevalence in our study was 49.6% but we took into consideration an infertile population requiring an IVF procedure and we used strict diagnostic criteria. Other authors have also published high prevalence values regarding specific groups: from 9 to 56% in recurrent miscarriage , 20, 37 The main of observation criteria is the negative immunohistochemical field after different treatment options: oral antibiotic administration and intrauterine infusion. To our knowledge there are two publications that describe the method of intrauterine antibiotic infusion: a case report  that obsBeing a unicentric prospective study with strict inclusion criteria and the necessity of a positive diagnosis of chronic endometritis, the number of cases will be limited, which will lower the statistical power of conclusions. The treatment with antibiotic in uterine infusions is recent in practice and we have considered that the acceptance of patients is mandatory, which excludes the possibility of randomization leading to inequal groups and error sources.Based on our findings there is a high prevalence of chronic endometritis in infertile patients and screening for it is useful and should be implemented. In the vast majority of the cases we obtained negative results after antibiotic treatment. This is an argument for the infectious nature of chronic endometritis. Antibiotic treatment administered through intrauterine infusions is much better than oral antibiotic treatment for curing chronic endometritis. Accordingly future studies on chronic endometritis therapy involving untreated control are probably discouraged for ethical reasons.


The compressive strength of concrete is an important parameter in construction practice. At present, there are few reports on the prediction model of the compressive strength of concrete at a super early age. For some engineering vibration analyses, it is very necessary to study the growth law of compressive strength of concrete at a super early age. To this end, a new prediction model is proposed in this work to analyze the variation of compressive strength for the concrete at a super early age. The innovations of this work mainly lie in two aspects. The first innovation is to propose a new compressive strength-age mathematical model to predict the variation of compressive strength more accurately. The second innovation is to develop a new robust regression analysis method to obtain the fitting parameters in the mathematical model more effectively. Using the experimental data of the super early age concrete, the proposed prediction model is compared with the existing power function model and the hyperbolic function model. The results of the comparative study show that the prediction model proposed in this work is more reasonable and reliable. Taking C40 under natural curing as an example, it has been shown from the comparative study that: (1) The total fitting error of the proposed model is approximately 60% of that of the power function model, and approximately 17% of that of the hyperbolic model; (2) The fitting standard deviation of the proposed model is approximately 49% of that of the power function model, and approximately 15% of that of the hyperbolic model; (3) The 28 day strength of concrete predicted by the proposed model is more in line with the actual strength growth law of concrete. The mechanical properties of concrete at an early age are a key topic in the field of civil engineering ,2,3. On Although many achievements have been made in the research of mechanical properties of early-age concrete, it is still necessary to study a more accurate predictive model for concrete strength-age at the super early age. Generally, the measured strength data of concrete are often very discrete because concrete is a brittle material. It is also necessary to study more robust regression analysis methods to deal with these discrete data. In view of this, the innovations of this work mainly lies in two aspects. The first innovation is to propose an improved mathematical model to predict the variation of compressive strength with concrete age more accurately. The second innovation is to develop a new robust regression analysis method to obtain the fitting parameters more effectively. The proposed robust regression analysis method is especially suitable for analyzing the mechanical characteristics of materials with great discreteness such as concrete. Using the experimental data, it was found that the proposed new compressive strength-age model has a better prediction accuracy than the existing models. The proposed robust regression analysis method can effectively overcome the great discreteness in the measured data. The framework of this study is organized as follows. As stated before, it is very necessary to propose an effective compressive strength-age model to predict the compressive strength of concrete at all times for engineering application. In this section, two existing compressive strength-age models are briefly reviewed firstly and then a new compressive strength-age model is proposed. One of the commonly used strength-age models is the power function model ,30 as The power function model can be used to analyze the change of compressive strength of concrete at a super early age, but it can not be used to analyze the variation of the concrete compressive strength at a late age; (2) In general, the fitting accuracy of the hyperbolic model for the super early age concrete (within 3 days) is not ideal. Relatively, the hyperbolic model is more suitable for predicting the strength of concrete in the later stage; (3) The prediction model proposed in this work can be used not only to analyze the compressive strength of super early-age concrete, but also to predict the compressive strength of concrete after 28 days; (4) The proposed robust regression analysis method can effectively resist the great discreteness of the measured data and obtain the reliable fitting parameters in the mathematical model. It has been shown that the proposed prediction model may be an effective tool for predicting the early-age strength of concrete. The future research can be carried out around the following aspects: (1) The first aspect is to carry out more compressive strength experiments for the super early-age concrete to further verify and improve the proposed prediction model; (2) The second aspect is to study the applicability of the proposed model to the tensile strength and elastic modulus of the super early-age concrete; (3) The third aspect is to investigate the performance of the proposed model for analyzing the strength development law of other types of concrete, such as recycled concrete and high-strength concrete; (4) The fourth aspect is to apply the proposed model to the concrete strength prediction in real projects for better serving the construction practice.


The repair of underwater concrete structures is usually difficult work, requiring specialized materials and installation systems. This paper presents a carbon-textile-reinforced concrete (TRC) grouting system for underwater repair of concrete structures. One multi-purpose grout and two types of underwater grouts were considered in this study, and the bond performance between the substrate and grout was evaluated by a bi-surface shear test with cubic specimens. The bond strength of the repair material is greatly affected by the casting and curing conditions. When the multi-purpose grout is used, the average bond strength of the specimens cast and cured in dry conditions is only 22% of the specimens cast and cured in underwater conditions. On the other hand, the maximum difference in bond strength is, at most, 15.8% when non-dispersive, anti-washout grouts are used. Two types of installation methods were proposed and four full-scale RC slab specimens were repaired with the TRC grouting method, two for each installation method. Regardless of the installation method, the load levels that causes concrete cracking, steel yield, and the failure of specimens repaired with the TRC grouting system are at least 37.5%, 16.6%, and 21.7% greater than those of the unrepaired specimen, respectively. The test results further indicate that the influence of the grouting materials on the ultimate load-carrying capacity of the specimens repaired with the TRC grouting system is insignificant, and the maximum difference is, at most, 4%. Civil infrastructures including bridges, hydraulic structures, and waterfront structures are often constructed in tidal zones or underwater environments. These structures are generally constructed with reinforced concrete (RC) and, if they are located in an underwater environment, are referred to as underwater concrete structures . UnderwaThe repair of underwater concrete structures is usually difficult work, requiring specialized materials and installation systems . Tremie Removable forms and jackets, such as plywood forms and steel jackets, are commonly used for grouting repair of underwater concrete structures. In recent years, fiber-reinforced polymer (FRP) composites were used as stay-in-place (SIP) jackets for the underwater repair of concrete elements ,6. If SIIn recent years, textile-reinforced concrete (TRC), consisting of a textile grid and cement-based matrix, was widely used for the repair and strengthening of deteriorated or structurally deficient concrete elements under various environmental conditions ,9,10,11.A research group in KICT developed a carbon-textile-reinforced concrete (TRC) panel, as not only an SIP formwork for the RC slab-type element of an open-type wharf structure during construction, but also as a protective layer during service . More reA thorough search of the relevant literature on TRC indicated that neither the development nor the application of TRC in an underwater environment has been reported. This paper proposes a TRC grouting system and installation method for the underwater repair of concrete structures. The proposed TRC grouting system consists of a carbon textile grid and cementitious grout. The objectives of this paper are to evaluate proposed underwater installation methods for a TRC grouting system, and to experimentally validate the structural performance of the RC elements repaired with the proposed installation methods. A carbon textile grid and three different grouts (one multi-purpose grout and two underwater grouts) were considered for underwater installation of the TRC grouting system.A total of 18 cubic specimens with a bi-surface (interface) between the substrate and repair materials were cast underwater and tested in shear to examine the bond performance of the material interface. To validate the proposed installation method of the TRC grouting system, five 2000.0 mm long RC slabs were fabricated, and two of the RC slabs were repaired with each installation method in an underwater environment. The RC slabs repaired with the TRC grouting system were tested in flexure, and the structural performance of the specimens was compared with that of an unrepaired RC slab and the analytical solutions.Two types of substrate materials (concrete and mortar) and three types of cementitious grouts were considered in the bonding test for the substrate with the repair material. For the fabrication of the substrate, a ready-mixed concrete and a commercially available mortar were used, and the mix composition of concrete and mortar are provided in A Portland cement-based non-shrink grout and two types of cementitious grouts for underwater application were selected for repair materials for the bonding test . G1 is aA bi-surface direct shear test  with a cThe compressive strengths of the substrate and repair materials were evaluated by the compressive strength testing method. The compressive strengths of concrete and mortar are identified as 32.9 MPa and 36.5 MPa, respectively. On the other hand, the compressive strength of G1, G2, and G3 are identified as 53.6 MPa, 46.7 MPa, and 27.4 MPa, respectively.σ) of the specimens is calculated by [2). The bond strength (lated by (1)σ=PAThe average bond strength of concrete without repair material (STC series) is found to be 10.4 MPa. On the other hand, the average bond strength of the concrete substrate with multi-purpose grout (G1) cast and cured under dry and underwater conditions is 1.5 MPa and 5.0 MPa, respectively. The bond failure occurs at the concrete–grout interface for the ST-1 and ST-2 series specimens. The bond strength varies greatly depending on the casting and curing conditions. Although the same grout (G1) is used as a repair material, the average bond strength of the ST-1 series specimen (dry casting) is only 30% of that of the ST-2 series specimen (underwater casting and curing). Note that the grout was cast without pre-wetting of the concrete substrate for ST-1 series specimens. Therefore, mixing water from the grout might be absorbed into the concrete substrate, and this results in an adverse effect on the bond strength of the concrete–grout interface. A research group  also conThe average bond strength of the STU-1 and STU-2 series specimens  is evaluated as 9.4 MPa and 6.4 MPa, respectively, and bond failure also occurs at the concrete–grout interface for these specimens. Although the higher compressive strength grout results in higher bond strength, the maximum difference is 31.9%. Therefore, the bond strength of specimens with the concrete–grout is greater than 5.0 MPa, regardless of the grout type used when they are cast and cured in the underwater environment.The average bond strength of the STP specimen (the mortar with multi-purpose grout) is identified as 6.5 MPa. As shown in The average bond strength of the STUP-1 and STUP-2 specimens  is evaluated as 4.8 MPa and 10.2 MPa, respectively. Bond failure occurs at the mortar–grout interface for the STPU-1 specimens. On the other hand, two of the STPU-2 series specimens fail at the mortar–grout interface, while one specimen  are provided in In the proposed method for underwater repair of RC elements, two types of installation methods for the TRC grouting system are used: a CIP TRC grouting system (CUW method) with removable formwork, and a TRC grouting system with a prefabricated TRC panel (PUW method). As shown in The RC slabs repaired with the TRC grouting system show a linear load-displacement behavior until concrete cracking occurs. After the concrete cracking, the stiffness of the repaired specimens is somewhat reduced, but the load could be further increased until the steel reinforcement yielded. The load-carrying capacity of the repaired specimen after the yield of steel reinforcement is due to the TRC grouting system. Overall, the ultimate load-carrying capacity of the PUW series specimens is at least 15.7% greater than that of CUW series specimens. Note that the thickness of the PUW series specimens is 20.0 mm greater than that of CUW series specimens. Therefore, a higher depth relative to the neutral axis increases the flexural capacity of the PUW series specimens. The load reaches its ultimate value of the repaired specimens, and an abrupt failure occurs. On the other hand, the load levels corresponding to the concrete cracking, steel yield, and failure of the RC specimens are at least 37.5%, 16.6%, and 21.7% smaller than those of the repaired specimens, respectively.In As shown in The load-displacement curves for the CUW series specimens and SG-1 series specimens  are plot(1) The bond strength of the repair material (grout) is greatly affected by the casting and curing conditions. When the multi-purpose grout is used as a repair material, the average bond strength of the specimens cast and cured in dry conditions is only 30% of the specimens cast and cured in underwater conditions. This result may be attributed to the fact that mixing water from the grout might be absorbed into the concrete substrate, and this adversely affects the bond strength of the concrete–grout interface. Non-dispersive, anti-washout grouts with normal and high compressive strengths  were used for the bond test specimens, and cast in an underwater condition. The higher compressive strength of grout results in higher bond strength, but the maximum difference is 31.9%. Therefore, the non-dispersive, anti-washout grouts should be used for the underwater repair of concrete structures with the TRC grouting method.(2) Four full-scale RC slab specimens were repaired with the TRC grouting method, two for each installation method. Regardless of the installation method, the load levels that cause concrete cracking, steel yield, and the failure of slab specimens repaired with the TRC grouting system are at least 37.5%, 16.6%, and 21.7% greater than those of the unrepaired specimen, respectively. The ultimate load-carrying capacity of specimens repaired with the TRC panel grouting system is at least 15.7% greater than that of specimens repaired with the CIP TRC grouting method. The test results further indicate that the influence of the grouting materials on the ultimate load-carrying capacity of the specimens repaired with the TRC grouting system is insignificant, and the maximum difference is, at most, 4%.(3) In this study, the proposed method was evaluated by a trial fabrication and structural test for RC slab specimens. However, the number of specimens tested per each case was limited in terms of obtaining reliable results. Therefore, an additional test program with at least two specimens per case should be conducted in future study.(4) Furthermore, several technical verifications should still be made for practical application. The total resources and time required for the proposed method should be compared with those of the conventional methods. A demonstration project should be conducted to evaluate the constructability of the proposed method for the repair and rehabilitation of deteriorated RC structures in an underwater environment. Successful development and validation of the proposed method will allow concrete structures in an underwater environment to be easily repaired.


Correction: Cellular and Molecular Life Sciences (2022) 80:6 10.1007/s00018-022-04634-2In the published article reference 41 was missed in the third paragraph, under discussion section in the page 15, and the below mentioned reference has been incorrectly processed, and the error in the below references has been now updated.Previously, we have reported that aberrant activation of the MET receptor modulates the cellular response to IR by rewiring key DNA damage response (DDR)-related phosphorylations in some tumor cell lines featuring MET activation [41]. Assuming that a MET–DDR interface underlies MET dependency, here we monitored 116 DDR- and RTK signalling-associated phosphosites in a panel of MET-positive, MET-responsive as well as non-responsive tumor models following targeted MET inhibition. This analysis revealed 14 METi-modulated phosphorylation events that were present solely in MET-addicted models, thus representing ‘MET-asa-driver’ footprints.The original article has been updated.


The aim of the presented examination is condition-monitoring of GFRP-reinforced concrete structural members using elastic wave propagation. As an example, a deck slab is selected. The deck slab is made of concrete of the targeted C30/37 class under three-point bending. During loading cycles, the specimen is observed with a digital image correlation (DIC) system, which enables calculation of the strain field. The measuring setup consists of two Baumer 12.3 Mpx cameras with VS-1220HV lenses, combined in a Q400 system by Dantec Dynamics GmbH. Elastic waves are also measured based on signals recorded with PZT (lead–zirconate–titanate) sensors. Additionally, the typical crack-opening measurements are made. The appearance of a crack and its growth causes changes in both the shape and amplitude of the registered signals. However, the changes are not obvious and depend on the location of the sensors. Due to the impossibility of determining simple parameters with respect to disturbingly wide cracks, for damage detection, an artificial neural network (ANN) is applied. Perfect determination of the specimen’s condition (100% properly classified patterns) is possible based on whether the element is under loading or not. Concrete, as a very popular construction material, is widely applied in many structural members and works in varying loading conditions. Due to its properties, this material transfers compression much better than tension, so in elements with tensile zones (but not exclusively), the application of reinforcement is necessary. Additionally, the inhomogeneous internal structure of this material makes the exact prediction of crack appearance and its propagation path impossible. Despite the use of reinforcement in concrete structures, cracks appear; however, they do not always mean that the operation of the facility becomes unsafe. A certain acceptable level of cracks is assumed, which allows continued safe use of the structure.Control of cracking in reinforced concrete is important due to aesthetic reasons and to prevent water leakage. Other aspects considered in crack limitation are creep cracking and shear effects. The load-bearing elements of a structure in which cracks have appeared should be regularly observed and examined in detail. The presence of cracks with large width and height may be a signal of deterioration of the structure’s condition, leading to its uselessness.Crack-opening measurements are most often performed manually using a feeler or fracture-width measuring instrument during periodic or ad hoc inspections. Like any manual control, it requires involvement of an experienced and skilled operator and gives a view of the structure only during the inspection. Until the next inspection, the situation may change as a result of exploitation. Not surprisingly, more and more scientists are looking for alternative ways to detect and assess cracks in concrete elements, especially in regards to construction that would have high consequences if damaged .Among many non-destructive testing (NDT) techniques in crack detection, the following are applied: elastic wave propagation measurements ,3, ultraElastic wave propagation through a material is very similar to how a wave propagates in water. Waves can propagate inside the material  or alongElastic waves are applied not only for crack detection in concrete structural members but also in different types of materials, such as metal  or compoIn concrete specimens, where the exact location of failure and the way of its propagation are difficult to predict, simultaneous measurements at many points is highly desirable. This opportunity is given by DIC . The maiExamples of DIC application can be found:  for cracThe purpose of this study is to determine the usefulness of the propagation of an elastic wave to determine the alarm level of crack opening. It is the continuation of research presented in  involvinIn the literature, a few tasks similar to those presented in this paper can be found. Kee and Nam  examinedLocalization of the cracks in concrete based on signals collected with PZT sensors is also the aim of the study by Narayanan et al. . LikewisThe same-sized small (500 mm × 150 mm × 150 mm) concrete specimen but under a three-point bending test was an object of examination by Kocherla et al. . The autIn the above-mentioned papers, damage indexes or factors that are sensitive to cracks are used. In this publication, artificial intelligence is used to determine whether the slab can be still exploited or not. Shallow artificial neural networks, which have been previously trained, classify the specimen’s condition. ANNs have often been applied in this type of task, enabling automation of the damage-detection process ,27,28,29Another interesting application of elastic waves to damage-imaging in concrete slabs was presented in . The autIt can be mentioned that not only elastic waves are used for NDT of concrete slabs. In the literature, examples of the application of vibration-based methods are also presented, such as in . HoweverThe prepared experiment relied on the observation of part of a deck-slab side surface under the three-point bending test. The deck slab width was 100 cm, the other dimensions of the slab as well as the location of the observed area are shown in The slab specimen was made using concrete with the targeted C30/37 class according to Eurocode 2 . The ageThe concrete slab was reinforced with 10 mm diameter solid GFRP (glass fiber reinforced polymer) bars with spiral ribbing. The mechanical properties of the GFRP bars were determined on five specimens using the ISO 10406-1 standard . The aveAs top and bottom reinforcement, bidirectional grids made of 10 mm diameter GFRP bars were used. The spacing of bars in both longitudinal and transverse directions was the same and equaled 80 mm. There were total of 11 longitudinal bars in the slab’s cross-section, and the concrete covers were 30 mm.The slab specimen was constructed in a local precast concrete plant and transported to the laboratory. The slab was inspected before testing, and there were two initial cracks with widths less than 0.1 mm (due to handling and transportation or shrinkage), which were considered irrelevant.The examination plan assumed loading and unloading the sample. Eight cycles were defined with different load rates. Loading was controlled by displacement. In the first three cycles, the increase was equal to 0.5 mm/min, and in the next five cycles, it was 2 mm/min. The following load values were achieved in subsequent cycles: 10 kN, 20 kN, 30 kN, 50 kN, 80 kN, 100 kN, 135 kN, and 150 kN. After the planned cycles, the slab was destroyed, but the examination presented here does not consider this stage.During the loading increase, the changes to the shape of the observed area were registered by the DIC system Q-400 by Dantec Dynamics GmbH . For this purpose, the area was painted with irregular black speckles, as shown in For elastic wave propagation measurement, a set of four of the same PZT transducers  were glued onto the boundary of the observed area. The location of these sensors was selected to enable measurement of the wave in zones with different stress states. The wave was generated by an exciter on the left side in the middle of the height of the slab. The other three PZT transducers received the wave. The set for elastic wave measurement see  consisteThe elastic wave measurements were made in states both without loading and under loading with the final value in each loading cycle. The generated signal was 3.5 sine waves, modified by a Hanning window, with an amplitude of 9 Vpp, and amplified 20 times. The operational frequency was 70 kHz. The normalized excitation signal is shown in During the experiment, the signals registered by the receivers changed their amplitude and shape. Observed changes were related to the force applied to the slab and the appearance of cracks. To enable signal comparison, all signals were normalized using the biggest value of amplitude registered in all measurements . The normalized signals for the alarm state are shown in When GFRP reinforcement bars are used, crack limitations related to corrosion are not required due to the bars; corrosion-resistant properties, so larger crack widths can be tolerated compared to those for steel-reinforced concrete elements . StandarThe first crack in the tested slab, as measured with the traditional way, appeared between the 30 kN and 50 kN load step at about 35 kN. At each load step, formation of cracks was evaluated, and crack widths were recorded and measured. The evolution of the crack pattern observed in the tests is shown in The exemplary views registered by two cameras are shown in The changes in the structure of the slab and the signals that appeared in selected loading cycles are summarized in The P = 50 kN loading resulted in development of the first crack propagation as well as the appearance of new cracks. The changes in the structure were so big that all sensors registered a significant decrease in signal amplitude. This time, even after removal of the loading, the amplitudes did not reach the State 0 level. However, according to the previously mentioned rules for this type of structure, the slab could still be treated as undamaged.The damage caused by the P = 80 kN load were determined, based on standard measurement of crack openings, as needing an alarm. It should be mentioned that the amplitude of signals C2 and C3 when the structure was under the influence of force were bigger than prior to loading (P = 0 kN). This relationship was also observed in the next loading cycles, which hindered assessment of the condition of the structure. Examples of registered signals after the alarm state and with and without loading are shown in To summarize, we must determine the influence that the amount and range of cracks and strain/stress state in the examined object or its parts has on elastic wave propagation. The changes in registered signals (considering amplitude and shape) have to be analyzed in connection with the location of the sensor.X, H—the number of hidden neurons, and O—the number of ANN outputs collected in vector O).Due to the inability of simple determination of parameters to enable structural health monitoring of the slab, an ANN was used. A shallow ANN with one hidden layer was selected. The architecture of this type of ANN can be symbolically described as X-H-O —the coordinates of the center of gravity of the absolute value of the cross-correlation vector of signal C2, —the same as above but for the C4 signal, and load—the information about loading: Load = 0 means that there is no load on the structure; Load = 1 means that some load is applied.Two cases of ANN were considered. The difference lay in the number of input parameters, as shown below:O = {In both analyzed cases, the output vector All 23 patterns collected during the measurement were divided into two sets: learning and testing. The learning set included the patterns corresponding to P ∈ {10, 20, 30, 80, 100, 135, and 150} kN and eight patterns for P = 0 kN but with different levels of crack growth. The testing set consisted of seven patterns connecting to P = 0 kN (different crack levels) and one specimen under loading with P = 50 kN. During learning procedures, the ANN did not use the testing patterns. The testing procedure was extended to two steps. In the first, testing using the above-mentioned testing patterns was made. In the second step, based on patterns registered during measurement, a new set of signals was created by the addition of random noise to the original patterns. Using this set enabled testing of the specimen loaded by force with a different magnitude .The ANNs were trained and testing according to the Levenberg–Marquardt algorithm using the approach described in . The detThe elastic wave propagation phenomenon can be useful in the determination of the state of concrete elements under bending. Considering the discontinuities in materials caused by cracks and the influence of strain fields on wave propagation, the information collected in both tensile and compressive zones has to be included simultaneously. The proposed method allows determining the state of a slab when the initial state of the structure is “healthy”, which means a lack of significant cracks at the beginning of monitoring.It has to be emphasized that the signals generated and registered by PZT transducers are sensitive to the way they are glued; concrete is an inhomogeneous material, and during manufacturing of reinforced elements, inaccuracies may appear. The above-mentioned factors, as well as the type of applied reinforcement or concrete, influence wave propagation. In our opinion, the development of a universal tool for monitoring the structural health of concrete elements will be a difficult or perhaps even impossible task. However, after narrowing down the set of variables and widening the collection of patterns , application of artificial intelligence automation of damage detection in concrete elements seems to be real.


Group Name: NorthShore University HealthSystemBackground: Prolonged antibiotic use has been attributed to an increased incidence of adverse drug events (ADEs). Cessation of unnecessary antibiotics would decrease length of treatment and may help prevent these adverse events. We evaluated whether an antibiotic stewardship intervention aimed at stopping unnecessary antibiotic usage would both shorten the duration of treatment and reduce ADEs. Methods: At NorthShore University HealthSystem, a 4-hospital, 832-bed system, we identified patients who were started on empiric antibiotics during a hospital admission between May 2, 2016, and June 30, 2018. Within 24 hours of antibiotic initiation, an infectious disease (ID) physician reviewed each patient chart. If the patient was unlikely to have a symptomatic bacterial infection, the ID physician left a note in the electronic medical record (EMR) recommending antibiotic cessation. Two physician reviewers retrospectively reviewed whether the treatment team accepted these recommendations and assessed potential ADEs for 30 days after the recommendation through inpatient and outpatient notes in the EMR. These ADEs were defined using previously published criteria. If the 2 reviewers disagreed on the presence of an ADE, an ID physician acted as the tie breaker. We compared the number of antibiotic days and the number of ADEs between cases in which the recommendations were followed and cases in which they were not. Results: We reviewed 168 cases: 78 (46.43%) followed recommendations and 90 (53.57%) did not. There were no significant differences in baseline patient characteristics between the 2 groups. There was a significant difference in total ADEs between the 2 groups: in 6 cases (7.69%) the recommendations were followed, and 21 (23.33%) they were not followed (P = .011). There was also a significant difference in antibiotic days between cases in which recommendations were followed (1.40 days) versus those in which they were not followed (1.99 days) (p < 0.001). Conclusions: Antibiotic-associated adverse events can cause harm to patients and increase healthcare costs, particularly when used for patients who are unlikely to have a bacterial infection. An antibiotic stewardship program to identify patients in an EMR who are unlikely to benefit from antibiotic use can decrease the length of total antibiotic usage and help prevent adverse events.Funding: NoDisclosures: None


Based on the underground reinforced concrete wall of subway stations , this paper studied the influence of a MgO expansive agent (MEA) on deformation and mechanical properties of a reinforced concrete wall. The results show that the effect of the MEA with different activities to compensate for the shrinkage of reinforced concrete walls is different. For MEA-R (60 s), because the activity is too high, its hydration rate is too fast, and many expansions occur at the plastic state of the concrete, which cannot effectively compensate for the shrinkage of concrete. For MEA-S (220 s), due to its low activity, the early hydration rate is so slow that it cannot compensate for the shrinkage, but it compensates well at the later stage due to the continuous hydration expansion of MEA. For MEA-M (140 s), the shrinkage of concrete is well compensated for the shrinkage at the early, middle and late stages due to its moderate activity. After using MEA to partially replace fly ash and mineral powder, the compressive strength of concrete was lower at the early stage (0–28 days). However, in the later stage, the porosity of concrete decreased rapidly, and the compressive strength of concrete would also be significantly improved. Therefore, choosing a suitably active MEA can compensate for the shrinkage of mass concrete without reducing its strength. Cracks caused by non-load deformation in concrete affect the durability of buildings and seriously endanger the safety of buildings . In rece2, which is more stable. In addition, MEAs with different expansion properties can be produced through artificial control calcination temperature to meet the needs of different projects [In recent years, many engineers and researchers have studied the structural cracking caused by the shrinkage of cement-based materials. There are five traditional ways to reduce shrinkage or cracking of cement-based materials. The first method is to replace part of cement to reduce the hydration heat of cement-based materials by mixing with mineral addition (milled fine fly ash or slag powder) . The secprojects ,19. For 2, the solid phase volume increases by 118%, so the expansion force generated by MgO in cement-based materials can compensate concrete shrinkage [Based on the results of previous researchers, after MgO hydrates to form Mg(OH)hrinkage . The lowhrinkage . This seIn fact, the reaction rate and expansion performance of MEAs are closely related to its activity. By changing its calcination temperature and holding time, MEAs with different expansion properties can be produced. According to the preliminary study of our group, MEAs with high activity produced at a low temperature have a higher expansion rate at the early stage but a lower expansion rate at the later stage . On the In this study, the reinforced concrete wall of the Hangzhou subway station is used as the research object. The volume deformation properties and the mechanical properties of MEA concrete under the conditions of conservation of natural conditions and rebar constraints were studied, and the hydration and deformation laws of MEAs with different activities were revealed under the condition of rebar constraints. The temperature change process and volume deformation of the reinforced concrete wall in outdoor environments were recorded by the vibration strain gauges, the humidity meter was used to measure the internal humidity of the concrete, and the degree of hydration of the MEA in the internal concrete wall was measured by thermal analysis.Portland cement, fly ash, coarse aggregates, fine aggregates, MEA and polycarboxylate-based high-range water reducer were used as the experimental objects. Details about each material are enumerated below.2/kg. 2, Fe2O3, Al2O3 and so on. The ARL XTRA-type Cu-target X-ray diffraction instrument produced by the United States was used to analyze the material composition of the cement, with a tube voltage of 45 kV, a tube current of 35 mA, a scanning range of 5 to 85 °C, a scanning rate of 10 degrees/min and a step length of 0.02 degrees. The test results are shown in Cement was P.O. 42.5 cement produced by Conch Group Co., Ltd. . Its specific surface area is 353 m2/kg.Fly ash was produced by Huaneng Renewable Resources Utilization Co., Ltd. . 2/kg, and its chemical composition is shown in Mineral powder was produced by Jiangsu Huailong Building Materials Co., Ltd. . Its specific surface area is 406 m2 in the MEA. The mineral phase was mainly periclase. The results of particle size distribution are shown in In this study, three kinds of MEAs with different activities produced by Wuhan Sanyuan Special Building Materials Co., Ltd.  were used. By using a citric acid testing method, the activity values were 60 s, 140 s and 220 s, respectively, which were denoted as MEA-R, MEA-M and MEA-S. Their chemical composition is shown in The mix proportions of concrete are listed in totalε is the total strain of concrete; svε is the self-volumetric deformation of concrete; k is the measurement sensitivity of strain gauge; ΔF is the change in the measured value in real time relative to the base value of the vibrating modulus; b is the temperature correction factor of strain gauge; a is the thermal expansion coefficient of concrete, which was tested via increasing the temperature of concrete from 25 °C to 55 °C and the average value 7.9 × 10−6/°C was taken; ΔT is the change in the temperature.Type-10 vibrating wire strain gauges made by Nanjing Gelan Industrial Co., Ltd.  were used. The gauge distance of strain gauge was 100 mm, and the vibrating modulus of the strain gauge, F, was closely related to its length, varying with the length change of the transducer brought about by the deformation of concrete . The totThe wall was constructed in the spring, and the atmospheric temperature at that time was 25 °C. The size of the reinforced concrete wall was 3 m × 0.8 m × 1.85 m. The thickness of the protection layer of reinforcement was 50 mm, and the spacing between horizontal reinforcement and vertical reinforcement was 150 mm. The layout of reinforcement is shown in In order to test the hydration degree of the MEA in reinforced concrete wall, cement paste samples with the same mixing ratio were poured. When pouring concrete, a cuboid hole of 50 mm × 50 mm × 750 mm is reserved for placing the cement paste specimen. The hole for the embedded paste specimen was set at position 4. A 20 mm × 20 mm × 750 mm hole was set at position 5 for placing a humidity sensor to measure the internal humidity of the concrete wall. The HX94CNPT humidity sensors was manufactured by Omega Engineering .2 in this experiment was 310~400 °C, and Equation (3) was used to calculate the content of Mg(OH)2 in the cement paste [2; lossMass (310 °C–400 °C) is the mass loss at the temperature range of 320 °C–400 °C caused by the decomposition of Mg(OH)2.The mass of the tested sample was reduced owing to the dehydration and decomposition of the cement-based material. According to the mass loss within the temperature range where the dehydration peak of a substance is located, the content of decomposed hydration products can be calculated. The dehydration peak of Mg(OH)nt paste . ThermogIn the beginning, three different strength test methods were compared. The first is to directly test the strength of concrete walls with a rebound meter, which is often used on buildings in China, but its accuracy is not high. The second is to drill the specimen from the concrete wall by drilling holes, but this will destroy the integrity of the wall, which will affect the subsequent test of the deformation of the concrete wall. Finally, the method of maintaining the cube test block in the outdoor environment was adopted, which was highly accurate and did not destroy the integrity of the wall.At the same time as pouring the concrete wall, the pumping of concrete was used to form 150 mm × 150 mm × 150 mm cube concrete blocks. The blocks were placed in the standard treatment room for one day, and then the blocks were placed near the concrete wall, so that they were in the outdoor environment. At the age of the corresponding age, the blocks were taken out to test the compressive strength. By analyzing the compressive strength of concrete with different mix proportions, the influences of the MEA activity and hydration on concrete were studied.3. For each concrete wall, two blocks were made for testing. Subsequently, the test blocks were soaked in absolute ethanol for 24 h to stop the hydration of the cement and MEA. Next, the test blocks were placed in a vacuum drying oven at 50 °C for 12 h. Finally, Mercury Intrusion Porosimetry (MIP) was used to test the pore distribution to study the effect of different active MEAs on the pore structure.At the specified age, the cement paste buried in the wall was removed, the surface part of cement paste was knocked out, and the internal part was taken to make a small test block of 2 mmThe temperature change process of the reinforced concrete wall could be divided into three stages, namely, the rapid temperature rise stage, rapid temperature drop stage and change stage with ambient temperature. The concrete temperature (in the depth of 5 cm) measured by three strain gauges was basically the same. In this paper, the temperature measured by No. 2 strain gauge was taken as an example to introduce the temperature variation. The detailed temperature variation is shown in The first stage was the stage of intense heating. During this period of time, the hydration reaction of active components such as cement, mineral powder and MEA was intense, and the temperature of reinforced concrete wall increased sharply. This stage lasted about one day, with the highest temperature reaching 56 °C. During this period, the concrete is in the state of thermal expansion, and the stress in the concrete is the compressive stress generated by the restraint of the reinforcement and the foundation, which will not cause the concrete to crack. Comparing the data of the reinforced concrete wall in this paper with the temperature of the dam in other publications, it is found that its temperature change is very different from that of the dam . For damThe second stage was the rapid cooling stage. During this period of time, the rate of hydration and heat release of cement slowed down significantly. Owing to the large temperature difference between the inside and the outside, the heat from the inner core slowly diffused into the air, thus gradually cooling down. This stage lasted about 7 days, and the internal temperature of the concrete wall was significantly higher than the outside air temperature, resulting in continuous heat dissipation from the wall. In this process, the CR-Ref concrete was in a state of shrinkage due to the temperature drop, and the stress in the concrete was tensile stress owing to the constraint of the steel bar and foundation. In the process, the concrete wall would crack if the tensile stress exceeded the limit of the tensile strength.The third stage was accompanied by the change of atmospheric temperature. During this period, the temperature of the reinforced concrete wall was basically the same as the atmospheric temperature, which changed with the atmospheric temperature.In the first stage, intense contraction appeared in CR, producing microstrains of −138 με, −106 με, and −50 με, respectively, at three locations. This was owing to the early high temperature accelerated the hydration rate of cement, leading to greater self-shrinkage of the concrete. After the first stage, the contraction rate of CR slowed down, and the cause of CR contraction changed from self-shrinkage to dry shrinkage, finally reaching a maximum of −235 με in 150 days. On the other hand, the concrete shrinkage at three different positions was not exactly the same, and the shrinkage at position 3 was significantly less than that of the other two. This was mainly owing to the fact that position 3 was closer to the foundation, which constrained the shrinkage and deformation of the concrete, resulting in a relatively smaller shrinkage.For concrete mixed with the MEA, it showed a completely different deformation. The CMM expanded significantly during the first phase. For example, at position 1 and position 2, the deformation was 39 με and 36 με, respectively. At position 3, owing to the foundation constrained the expansion of MEA, its expansion was reduced relative to the other two positions, and the 10 days expansion was 19 με. On the other hand, the expansion produced by CMR and CMS at this stage cannot completely compensate for the shrinkage of concrete, and the shrinkage was −7 με~−25 με.In the second stage, the expansion of the MEA was greater than the shrinkage of concrete, resulting in micro-expansion of the reinforced concrete walls. During this period, for CMM, the expansion gradually increased, reaching a maximum value of 75 με at 90 days. At the same time, the expansion of position 3 was also smaller than that of the other two positions owing to the constraint of the foundation.Comparing the two stages, the following conclusions can be drawn. For CMR, because the activity is too high, its hydration rate is too fast, and many expansions occur at the plastic state of the concrete, which cannot effectively compensate for the shrinkage of concrete. For CMS, due to its low activity, the early hydration rate is so slow that it cannot compensate for the shrinkage, but it compensates well at the later stage due to the continuous hydration expansion of the MEA. For CMM, the shrinkage of concrete is well compensated for the shrinkage at all the stages due to its moderate activity.In the third stage, due to the large consumption of the MEA in the early stage, there are few remaining MEAs that can continue to produce expansion. At this stage, contraction and expansion were basically equal, and concrete expansion gradually decreased. The deformation of CMR tended to be flat and even shrink. The later deformation of CMM and CMS was still expansion deformation, which indicated that the hydration expansion of MEA-M and MEA-S could compensate for the self-shrinkage caused by hydration and the shrinkage caused by drying.According to classical computational mechanics, when a wall is constrained by a foundation, cracks appear at the bottom of the wall, and cracks are perpendicular to the foundation. However, in many large-volume concrete structures, cracks are often randomly distributed and do not always appear near the foundation ,26. In oThe hydration of MEA depends on its own activity, maintenance temperature and humidity. As shown in 2 in the cement paste, and the calculated results were shown in 2 content of the MEA at different curing ages are showed in 2 in cement paste with different activities of the MEA under the same content, Mg(OH)2 produced by MEA-S (PMS) with low activity was the least. However, at the later stage (160 days), PMS produced more Mg(OH)2 than the other two samples. As the expansion of the MEA was generated by MgO hydration to generate Mg(OH)2, it indicated that the expansion of the MEA with low activity was smaller in the early stage, but it produced greater expansion in the later stage, which was consistent with the laboratory test results of many other researchers [On the other hand, the activity of MEA also affected the hydration rate of MEA. At 28 days, compared with the content of Mg(OH)earchers .As some fly ash and mineral powder were replaced by the MEA, the amount of cementitious materials in concrete was reduced. As a result, in the early days (0–28 days), compressive strength of three MEA concretes  were lower than CR. However, with the continuous hydration expansion of MEA in the later stage, the hardened concrete restricted the outward expansion of MEA and made the MEA turn into an inward compression, which reduced the cavity of concrete and made the concrete more compact, thus improving the compressive strength of concrete.(1)After 24 h of wall pouring, the temperature of the mass-reinforced concrete wall dropped sharply, which made the concrete produce a large shrinkage period and was prone to cracks. Therefore, effective measures must be taken to avoid wall cracking, ensure the safety of the wall and improve the durability of the wall.(2)The shrinkage of reinforced concrete wall under the constraints of the foundation created tensile stress in the structure, resulting in cracks in the walls. Adding an MEA could effectively reduce the shrinkage of concrete, improve the volume stability of concrete, and reduce the generation of cracks.(3)The effect of an MEA with different activities to compensate for the shrinkage of reinforced concrete walls is different. For MEA-R, because the activity is too high, its hydration rate is too fast, and many expansions occur at the plastic state of the concrete, which cannot effectively compensate for the shrinkage of concrete. For MEA-S, due to its low activity, the early hydration rate is so slow that it cannot compensate for the shrinkage, but it compensates well at the later stage due to the continuous hydration expansion of MEA. For MEA-M, the shrinkage of concrete is well compensated for the shrinkage at the early, middle and late stages due to its moderate activity.(4)The early strength of the MEA concrete was lower than that of concrete without an MEA, and the early porosity is also higher. With the later expansion of the MEA, the porosity of the MEA decreased rapidly, and the strength also increased significantly, which indicates that the MEA will not reduce the strength while supplementing the shrinkage.(5)Unlike plain concrete, an MEA can only compensate for shrinkage and cannot improve the strength of concrete. For reinforced concrete structures, due to the constraints of steel bars, self-stress is generated, which can also improve the compactness and strength of concrete. Therefore, MEA140 is safe and reliable for reinforced concrete walls of subway stations.


Navigation is a complex skill that is used in everyday living, whether it be to travel across a country or to travel to a local store. How one successfully navigates through their environment involves many different processes, including spatial navigation, route generation, and orientation. An issue with investigating those separate constructs within navigation is the number of questions required to assess them reliably. As a part of a larger project, a large sample of community-dwelling older adults (ages 60–90) completed an online survey answering questions related to navigation. Among those were three subscales: a general wayfinding subscale, a subscale asking how often they felt lost when moving around near and far spaces, and a subscale asking how often they needed help navigating around near and far spaces. Each of these subscales contained fewer than eight items. The goal of the analysis was to determine the reliability and validity of these subscales, and this was accomplished through calculating Cronbach’s α and an exploratory factor analysis (EFA). Cronbach’s α for each of the individual subscales were above 0.8, indicating high reliability. EFA results output five unique factors. Noticeably, the wayfinding subscale was broken into two factors, one for route generation ability and one for mental mapping ability. while the “Feeling Lost” and “Needing Help” subscales produced a dichotomy between nearer distances (ex. Your immediate neighborhood) and farther distances (ex. Your state). This contrast, along with its implications, are discussed further.