The hysteretic behavior of square concrete-filled steel tube (CFST) stub columns subjected to sulfate corrosion and freeze-thaw cycle is examined by numerical investigation. The constitutive model of steel considered the Bauschinger effect, and compression (tension) damage coefficient was also adopted for the constitutive model of core concrete. The experimental results are used to verify the finite element (FE) model, which could accurately predict the hysteretic behaviors of the CFST piers. Then, the effects of the yield strength of steel, compressive strength of concrete, steel ratio, axial compression ratio, and alternation time on ultimate horizontal load are evaluated by a parametric study. The results showed that the yield strength of steel and the steel ratio have a positive effect of hysteretic behavior. The compressive strength of concrete and alternation time significantly decreased the unloading stiffness which causes the pinching phenomenon. The yield strength of steel, compressive strength of concrete, and alternation time of environmental factors (corrosion-freeze-thaw cycles) has no obvious effect on the initial stiffness, while the steel ratio has a remarkable effect. The ultimate horizontal load increases with the increasing steel ratio, yield strength of steel and compressive strength of concrete. Meanwhile, the decrement of alternation time led to the increase of ultimate horizontal load. This suggests that the confinement coefficient and alternation time are the two main factors that impact the ultimate horizontal load. A formula which considers the reduction coefficient for the ultimate horizontal load of the CFST columns subjected to sulfate corrosion and freeze-thaw cycles is proposed. The formulae can accurately predict the ultimate horizontal load with mean value of 1.022 and standard deviation of 0.003. Concrete-filled steel tubes (CFST) are composite structural members with an outer steel tube and an inner core of concrete ,2. The uM = 0.58I + 1.5, where M is Richter scale, I denotes seismic fortification intensity, I = 7 here) protected earthquake intensity. It illustrated that the vertex displacement of pier columns was below the ultimate displacement for all 18 earthquake excitations, which verified that the CFST pier column has good seismic resistant. Wang fcu, fcu is the cube compressive strength of concrete, η = 1.6 + 1.5/x, η is defined as shape coefficient to reflect the properties of shape cross section, β = (ξe)0.5], ξe =αe × fye/fck, ξe is the effective confinement factor, fye and fck are the effective yield strength of steel tube and characteristic compressive strength of concrete, respectively; fck = 0.88 × 0.76 × fcu, αe = Ase/Ac; αe is the steel ratio, and Ase and Ac are the effective cross-sectional areas of the steel tube and core concrete, respectively.The core concrete is modelled through the concrete damage plasticity (CDP) model. A stress–strain model considering the confinement effect in improving the behavior of core concrete by Han et al.  was applEc is the elastic modulus of core concrete and The elastic modulus of core concrete was calculated by Equation (4), which was proposed by ACI 318  as folloψ), Kc, fb0/fc0 was determined by Equations (5)–(7). The eccentricity value was selected as 0.1 and the viscosity parameter was chosen as 0.0001 to improve the convergency of the model.e is the effective confinement factor, fb0 is the initial biaxial strength of concrete, and fc0 is the initial axial strength of concrete.The parameters of the CDP model were defined in the numerical model using the formula provided by Tao et al. . The valD is the damage variable of core concrete, W0 presents the strain energy in nondestructive state, Wε presents the strain energy under damage state, and a denotes the number of calculation steps.σc(t) is the compression (tensile) stress under a damaged state and Ec denotes the elastic modulus of concrete. In order to ensure the convergence and rationality, coefficient bc(t) is selected as 0.5 and 0.25 corresponding to compression and tension condition, respectively.Since the stress–strain relationship of concrete under hysteretic load could be replaced by that under uniaxial load , the strwc and tension stiffness recovery parameter wt. According to a former study, micro cracks in concrete could convey compression under compressive load, while concrete with micro cracks could not convey tensile strength [wc = 1.0 and wt = 0 were employed.The tension recovery of core concrete should be considered in the CDP model under low cyclic load. This characteristic was determined by compression stiffness recovery parameter strength . In thisB/10 for both the core concrete and the steel tube. The 3D model consisted of a mesh which was deemed fine enough to accurately calculate the hysteretic behaviors of CFSTs with a reasonable computational time.According to a former study , core coP presents the lateral load, Δm denotes lateral displacement, and L0 defined as calculation length.The centers of the top and bottom surfaces were set as reference point 1 (RP1) and reference point 2 (RP2), respectively. The top and bottom surfaces of the specimen were constrained with RP1 and RP2 through a rigid body constraint. The top surface of the CFST column is free in all directions except in the loading direction. The axial load was exerted on the RP1 in the Z direction and the horizontal load was also exerted on RP1 in the X direction in the displacement control mode as shown in The model includes three steps: (1) an initial analysis step, where boundary conditions were set up; (2) step 2, where axial load is applied in the load-control mode; (3) step 3, where horizontal load exerted to RP1 with desired displacement in the displacement-control mode. The time of each analysis step was separated according to the displacement loading amplitude curve. The calculated result was obtained by Gauss integral iteration and output at the end of each analysis step.The concrete core and steel tube employed surface-to-surface contact to ensure the concrete core and the steel tube maintained an adequate bond, which created the CFST column as a whole. Since the stiffness of the concrete core was higher than that of the steel tube, the concrete core was selected as the master surface, while the steel tube was set as the slave surface. Moreover, the formula of small sliding was adopted in this section since the relative slip of the concrete core and the steel tube was small. Mechanical properties of tangential behavior were simulated by a penalty and friction coefficient, which is 0.6 . The valThe typical failure mode of specimens under cyclic loading at ambient temperature (20 ± 2 °C) was depicted in The experimental results were compared with those obtained via FE modelling in terms of skeleton curve, as depicted in However, in the elastic plastic stage, the slope of FE results was higher than test results. For the twelve verified specimens, the skeleton curves match the FE curves with a subtle difference in slope, which is likely to be associated with a geometric and loading defect generated through the experiment. These results were then employed in investigating hysteretic behavior.The horizontal ultimate compressive strength was obtained from the FE model and compared with the test specimens. The experimental results were compared with the results of the FE model in terms of hysteretic behavior, as depicted in B) of 400 mm, shear span ratio (λ) equal to 1.5, and other parameters as tabulated in In this paper, the typical specimen had a side length  and alternation time (i). In this study, according to practical engineering, the range of parameters was selected as ξ = 0.6–2.1 and i = 0–5.According to the parameter analysis in Mu represents the flexure capacity; Pu0 denotes the horizontal ultimate axial load; L is the length of the CFST column; N stands for the axial compressive load; and Δ corresponds to lateral deformation.According to n ≤ 0.3. Meanwhile, lateral deformation was far less than the calculated length of CFST pier column, so the bending moment caused by the axial compressive load could be ignored. Thus, the ultimate horizontal load was expressed in Equation (11) as follows:Based on CJJ166-2011 , the axiγm represents the plastic adaption coefficient of cross section; Wsc denotes the modulus of section of CFST pier columns (mm3); r0 corresponding to the equivalent circle radius (mm); and Mu is the flexure capacity (N·mm).The design formula to calculate the flexure capacity in GB50936-2014 was described in Equations (12)–(14) as follows:ksq was defined in Equation (15) as follows:Pue is the ultimate horizontal load under sulfate corrosion and freeze-thaw cycles; Pu0 is the ultimate horizontal load under ambient condition. The major effect was presented in To evaluate reduction of loading bearing capacity of the square CFST pier columns after alternate sulfate corrosion and freeze-thaw cycles, the reduction coefficient i) linearly. With the increase of alternation time, the reduction coefficient decreased rapidly and decreased up to 75.0% compared to the specimens under ambient conditions, which illustrated that i was the major factor that affects the ultimate horizontal load. In The reduction coefficient varied with alternation time  was determined by the steel ratio and the relative ratio of yield strength of the steel tube to compressive strength of the core concrete, the reduction coefficient considering ξ could reflect three above parameters. As shown in n) when it ranged from 0.05 to 0.30. This illustrated that the effect of axial compression ratio was negligible. Therefore, alternation time and confinement coefficient were adopted to be the major factors for evaluating the reduction coefficient of square CFST pier columns after alternate sulfate corrosion and freeze-thaw cycles. The reduction coefficient was described in Equation (16) as follows:ξ is the confinement coefficient; i presents the alternate time.Then, the reduction coefficient decreased obviously with the increasing confinement coefficient, as shown in The reduction coefficient of the horizontal ultimate compressive load of square CFST pier columns after sulfate corrosion and freeze-thaw cycles was calculated based on Equations (15) and (16). All the reduction coefficients corresponding to FE models were compared with the calculated results, as shown in ksq is the reduction coefficient; Pu0 presents the ultimate horizontal load under ambient conditions; the relationship between Nft and γ was defined as i in Ref. [For the square CFST pier column after alternate of sulfate corrosion and freeze-thaw cycles, ultimate horizontal load can be calculated by modifying the formula under ambient condition, which is expressed as follows:  in Ref. .The comparison between the calculated values and numberical values of the ultimate horizontal load of square CFST pier columns after alternate sulfate corrosion and freeze-thaw cycles was presented in It should be mentioned that the modified simplified formula could be adopted to calculate the ultimate horizontal load of square CFST pier columns after alternate sulfate corrosion and freeze-thaw cycles with the limited parameters: (1) the section side length ranges from 200–1200 mm; (2) compressive strength ranges from 30–60 MPa; (3) yield strength of steel tubes ranges from 235–420 MPa, (4) alternation time ranges from 0–500; and (5) corrosion ratio ranges from 0%–50%.(1)The nonlinear finite element (FE) model considering the dual environmental impact of sulfate corrosion and freeze-thaw cycles was accurate in simulating the degradation of loading stiffness and unloading stiffness, bearing load, and ductility on the basis of reasonable damage factors.(2)The steel ratio, yield strength of steel tube, compressive strength of core concrete and alternation time have a significant effect on hysteretic behaviors of square concrete-filled steel tube (CFST) pier columns after alternate sulfate corrosion and freeze-thaw cycles. The cyclic curves of hysteresis loops increased with increasing steel ratio and yield strength of steel tube caused the increasing initial stiffness of the specimens. The skeleton curves corresponding to the hysteresis loops presented ductile behavior with increasing steel ratio and yield strength of steel tube. The effect of yield strength of the steel tube, compressive strength of core concrete, and alternation time on initial stiffness was negligible. The ultimate horizontal load increased by 21.4–126.4%, 26.3–39.2%, and 16.0–33.7% as the steel ratio increased from 0.06 to 0.20, the yield strength of steel tube increased from 235 MPa to 420 MPa, and compressive strength of core concrete increased from 30 MPa to 60 MPa, respectively while the ultimate horizontal load decreased by 16.2–50.2% as alternation time increased from 1 time to 5 times.(3)The steel ratio, compressive strength of core concrete, axial compression ratio, and alternation time have a significant effect on ductility behavior. The ductility of the specimens increased with the increasing steel ratio since the post stage of the skeleton curve varied from the descending stage to the ascending stage, while the ductility of the specimens decreased with the increasing compressive strength, axial compression ratio, and alternation time for the increasing brittleness caused by the damage of raw materials.(4)The confinement coefficient and alternation time were the two major factors that affect the reduction coefficient of the ultimate horizontal load of square CFST pier columns after alternate sulfate corrosion and freeze-thaw cycles. The horizontal bearing capacity decreased by 16.2–50.2% with the alternation time increasing from 1 time to 5 times. The horizontal bearing capacity decreased up to 17.7% as the confinement coefficient increased from 0.63 to 2.06.(5)A simplified formula for predicting the reduction coefficient of the horizontal bearing load with high accuracy with a mean value of 1.028 and standard deviation of 0.001 was developed.(6)A modified equation for predicting the ultimate horizontal load of square CFST pier columns after alternate sulfate corrosion and freeze-thaw cycles was proposed within the error of 15%.The study presented a nonlinear finite element (FE) model to analyze the hysteretic behavior of concrete-filled steel tube (CFST) pier columns subjected to alternate of sulfate corrosion and freeze-thaw cyclic. Quantitative and qualitative verifications performed in this paper indicate that the FE model can accurately predict the hysteretic behavior of CFST pier columns. According to the numerical analysis, the following conclusions can be drawn:


A promising method of obtaining mineral fiber fillers for dry building mixtures is the processing of waste that comes from the production of technogenic fibrous materials (TFM). The novelty of the work lies in the fact that, for the first time, basalt production wastes were studied not only as reinforcing components, but also as binder ones involved in concrete structure formation. The purpose of the article is to study the physical and mechanical properties of waste technogenic fibrous materials as additives for optimizing the composition of raw concrete mixes. To assess the possibility of using wastes from the complex processing of TFM that were ground for 5 and 10 min as an active mineral additive to concrete, their chemical, mineralogical, and granulometric compositions, as well as the microstructure and physical and mechanical characteristics of the created concretes, were studied. It is established that the grinding of TFM for 10 min leads to the grinding of not only fibers, but also pellets, the fragments of which are noticeable in the total mass of the substance. The presence of quartz in the amorphous phase of TFM makes it possible to synthesize low-basic calcium silicate hydrates in a targeted manner. At 90 days age, at 10–20% of the content of TFM, the strength indicators increase (above 40 MPa), and at 30% of the additive content, they approach the values of the control composition without additives (above 35 MPa). For all ages, the ratio of flexural and compressive strengths is at the level of 0.2, which characterizes a high reinforcing effect. Analysis of the results suggests the possibility of using waste milled for 10 min as an active mineral additive, as well as to give better formability to the mixture and its micro-reinforcement to obtain fiber-reinforced concrete. An important direction in the development of concrete science is to minimize the use of cement as a result of its partial replacement with various fillers, including those obtained from production waste ,2,3. ManA promising direction for obtaining mineral fiber fillers for dry building mixtures is the processing of waste from the production of technogenic fibrous materials (TFM) ,5,6.The most studied type of TFM is pulp and paper waste, consisting mainly of fibers with a length of 0.1 to 5 mm, of plant origin, isolated from coniferous and hardwood , the stems and bast of annual plants, and seed pods and leaves of some plants or mineral (asbestos) origin  7,8,9].,8,9.7,8,In the world, about 15 million tons of pulp and paper waste are generated annually, of which 12 million tons are suitable for processing ,11,12,13Cellulose fiber has an amorphous structure, is insoluble in water, is resistant to acids and alkalis, and has a pH value in the range of 4 to 12 ,15. Cell3), storage areas occupy a large share of the area in factory warehouses and landfills  ;−providing various sizes of fibers for their use in composite mixtures for various technological purposes, incl. for 3D technologies in construction ,32.It is advisable to use a step-by-step process for the complex processing of basalt fibrous waste:Obtaining agglomerated, highly concentrated microfiber fillers has a number of technological advantages: increased flowability and better transport ability, which ensures a more uniform distribution of fibers in macro and micro volumes of a composite mixture with heterogeneous components, and expands the scope of the use of basalt waste (fibers) in an agglomerated form for various technological purposes  .−increase in the crack resistance of the product ;−imparting thixotropic properties of the mortars;−improving the fixing ability on a vertical surface, preventing tiles from slipping (if in tile adhesive);−reduction in shrinkage that occurs during the maturation of mortar or concrete;−increase in frost-resistant properties of products;−improving the rheological properties of the mortar and increasing the time of work with them.The effects of using technogenic fiber in mortar or concrete ,34,35:−iThe use of various industrial fibers for reinforcing concrete is sufficiently studied, for example, basalt and polypropylene , steel, The novelty of the work lies in the fact that, for the first time, basalt production wastes are studied not only as reinforcing components, but also as binder components, involved in concrete structure formation.The purpose of the article is to study the physical and mechanical properties of waste technogenic fibrous materials for use as additives for optimizing the composition of raw concrete mixes.Portland cement CEM I 42.5 N  according to EN-197 was used as a binder. As an active mineral additive to concrete, wastes from the complex processing of TFM  were used. Microsilica, which is a technogenic waste from metallurgy, was used to provide the pozzolanic reaction.2, CaO, MgO, Al2O3, Fe2O3, Na2O, TiO2, and K2O impurities represent mineral wool. The amount of SiO2 is 44.11%, the specific surface area is 200 m2/kg, the bulk density is 1366 kg/m3; and true density is 2884 kg/m3.The superplasticizer “PFM-NLK”  was used in the mixes. For the developed mortars, sand with a particle size of 1.5–2.5 mm was used.In the work, samples of 70 × 70 × 70 mm in size (according to Russian standard GOST 310) were molded with different waste content (10–40% by weight of cement) and the corresponding replacement of part of the cement. The water to cement ratio (W/C) was 0.4 and the sand/binder ratio was kept constant at 2.75. The compositions of concrete mixes are given in All mixes were designed based on the conditions of equal workability, providing a slump of 19 cm and a slump flow of 43 cm.To assess the possibility of using wastes ground for 5 and 10 min for the complex processing of TFM as an active mineral additive to concrete, their chemical and mineralogical compositions were studied using an X-ray fluorescence spectrometer. Using a scanning electron microscope, the shape and size of the particles were visually assessed before and after grinding.The specific surface area was determined by two complementary methods using the PSH-2 device  and the Sorbi-M device (4-point BET method), . The volume of pores with a radius <19.4 nm was also calculated.The microstructure of the materials was studied using a Mira 3 scanning electron microscope .Compressive and flexural strength tests were carried out after 7, 28 and 90 days according to the Russian standard GOST 310.Silica in this type of technogenic raw material is in an amorphous highly dispersed state, as evidenced by the maximum peak in the region of 31–33° .2O6 and anorthite CaAl2Si2O8, which is characteristic of crystalline basalt. These phases begin to crystallize at temperatures above 900 °C during the melting of basalt in the production of mineral fiber.The main crystalline phases of TFM that belong to plagioclases are augite CaSi2 released as a result of the hydration of clinker minerals. These processes allow the targeted synthesis of low-basic calcium silicate hydrates during hydration, which are responsible for the strength properties of the finished building product.The presence of crystalline phases of quartz in the β-modification is evidenced by characteristic diffraction reflections. There is a high-temperature polymorphic modification of quartz β-crystobalite. The presence of quartz in the amorphous phase causes high solubility in saturated alkaline solutions of the hydrated binder and active interaction with the Ca(OH)The results obtained are confirmed by the energy dispersive microanalysis (EDM) of waste performed with the construction of a map of the distribution of chemical elements over the surface. Results also indicate the absence of additional inclusions in the material due to preliminary screening .SEM images obtained using a scanning electron microscope a show thWhen grinding using a ball mill for 5 min, the size of the fibers is significantly reduced. First, there is the most intensive grinding of thin and long fibers; as a result, the ratio of length to diameter decreases. The beadlets themselves remain largely unchanged b, but soFurther grinding for 10 min leads to grinding not only the fibers, but also the beadlets, the fragments of which are noticeable in the total mass of the substance. There is a large number of the smallest nanosized crushed fractions, however, there is also a significant amount of larger particles of a fibrous form c.This is consistent with the obtained granulometric composition of the powders .3/g  made it possible to maintain the slump within 20 cm for almost all compositions .Only at a dosage of TFM in the amount of 40 wt. % value of the slump decreased to 16 cm. At the same time, the parameter of the slump flow was kept at the level of 48–51 cm, allowing its decrease in the amount of TFM 30–40 wt. % up to 46 cm.The density of the fresh mixture modified with FMT reduced when the dosage increasing. The decrease in the density of the hardened concrete samples is justified by the fact that the average density of cement hydration products is lower than the average density of the initial mixture.Compositions with 40% TFM in all periods of hardening have the lowest strengths, with a 50% drop compared to the control composition. For all the mixtures only at the age of 7 and 28 days, the compressive strength decreased (by about 20–40% compared to the control samples) as the content of mineral wool waste increased . CorrelaHowever, at the age of 90 days, at 10–20% of the content of TFM, the strength indicators increase, and at 30% of the content of the additive they approach the values of the control composition without additives. The decrease in compressive strength of samples with the replacement of cement by 30 and 40% of TFM is explained by supersaturation and weakening of the hardening system, confirming the optimal content of this component at the level of 20%.Good early compressive strength results (7 days) are noted; even at 40% replacement of cement by TFM, the early compressive strength reaches 15 MPa. This allows you to speed up the production of concreting. The increase in strength may be associated with the pozzolanic reaction, the completeness of which increases most at a later age ,52,53,54The decrease in strength at 28 days of age may be due to the high water demand of the finely ground filler, which intensively absorbs water, slowing down the rate of hydration. However, in the future, the filler can release stored water, providing long-term hydration. Based on the test results mentioned above, the inclusion of 10–20% mineral wool waste is optimal.Good results were obtained in the study of flexural strength . The opt2 released as a result of the hydration of clinker minerals.Thus, the analysis of the results suggests the possibility of using waste milled for 10 min as an active mineral additive, as well as to give better formability to the mixture and its micro-reinforcement to obtain fiber-reinforced concrete ,63,64,65−The processing of TFM for 10 min leads to the grinding of not only fibers, but also granules, fragments of which are noticeable in the total mass of the substance. There is a large amount of the smallest nanosized crushed fractions, however, there is also a significant amount of larger particles of a fibrous form. This is the reason for the effective use of the material to control the structure formation of the cement composite, both at the macro level (fiber) and at the micro level (cement substitute).−2 released as a result of the hydration of clinker minerals. These processes make it possible to purposefully synthesize low-basic calcium silicate hydrates during hydration, which are responsible for the strength properties of the finished building product.The reactive activity of TFM is confirmed by the high solubility in saturated alkaline solutions of the hydrated binder and active interaction with the Ca(OH)−At 90 days of age, at 10–20% of the content of TFM, the strength indicators increase (above 40 MPa), and at 30% of the additive content, they approach the values of the control composition without additives (above 35 MPa). For all ages, the ratio of flexural and compressive strengths is at the level of 0.2, which characterizes a high reinforcing effect. The increase in strength may be associated with the pozzolanic reaction, the completeness of which increases most at a later age. In addition, the microsize of the grains of TFM waste used in this study increases the compressive strength of the mortar by acting as a compactor.−Analysis of the results suggests the possibility of using waste milled for 10 min as an active mineral additive, as well as to give better moldability to the mixture and its micro-reinforcement to obtain fiber-reinforced concrete.The physico-mechanical properties of waste technogenic fibrous materials (TFM) used as additives for optimizing the composition of raw concrete mixtures were studied. The following results were obtained:


To report a rare case of IgG4-related ophthalmic disease (IgG4-ROD) manifesting as intraocular masses and scleritis in both eyes in a 61-year-old male and to investigate the changes in multimodal imaging features of the lesion sites and helper T-cell type 1 (Th 1)/Th 2/Th 17 cytokine levels in the aqueous humor.A patient with IgG4-ROD seemingly manifested with an intraocular tumor in the left eye and sequentially, with an inflammatory mass in the ciliary body and scleritis in the right eye. The patient complained of vision loss of 6 months duration in the left eye at his first visit. With a preliminary diagnosis of an intraocular tumor, enucleation of the left eyeball and histopathological examination were performed. Approximately 3 months later, the patient started to experience headache, eye pain, and declining vision in the right eye. Ophthalmic imaging revealed a ciliary mass and scleritis. Th 1/Th 2/Th 17 cytokine levels and multimodal imaging findings were analyzed before and after corticosteroid treatment. Histopathological examination and immunohistochemistry (IHC) of the enucleated left eye demonstrated lymphoplasmacytic infiltration with an IgG4+/IgG+ cell ratio of approximately 40%, pointing to the diagnosis of probable IgG4-ROD. Long-term treatment with corticosteroids led to significant improvement in the signs and symptoms of the left eye. Th 1/Th 2/Th 17 cytokine profile monitoring of the aqueous humor and multimodal imaging of the right eye showed gradual regression of the mass and attenuation of ocular inflammation during treatment.Patients with an atypical presentation of IgG4-ROD, such as intraocular masses and scleritis, are likely to experience a significant delay in diagnosis. This case demonstrates the significance of IgG4-ROD in the differential diagnosis of intraocular tumors and ocular inflammation. IgG4-RD is a newly diagnosed disease with multi-organ involvement and little is known about its pathogenesis, particularly in the eye. The present case will open new challenges in the clinico-pathological diagnosis and research of this disease. Combined investigations of multimodal imaging and cytokine level detection of intraocular fluid provide a new and effective way to monitor disease progression. Immunoglobulin G4-related disease (IgG4-RD) is characterized by the infiltration of IgG4-immunopositive plasmacytes, fibrosis, or mass formation in the involved organs and is usually combined with elevated serum IgG4 levels . ComprehA 61-year-old man was referred to the Department of Ophthalmology at the Second Xiangya Hospital, Central South University, in August 2018, and reported a 6-month history of vision loss in the left eye. He denied any history of surgery or trauma in the left eye. His best corrected visual acuity (BCVA) was 20/20 in the right eye and suspicious light perception (LP) with faulty light projection in the left eye. His intraocular pressures were 15 mmHg OD and 16 mmHg OS. Slit-lamp examination revealed edema and severe vascular congestion of the supratemporal conjunctiva and sclera, together with slight corneal edema, prominent keratic precipitates (KP), anterior chamber (AC) flare, a few inflammatory cells (++) in the AC, severe posterior synechia, and posterior capsule opacification in the left eye  was observed in the ciliary body area. Adjoining the ciliary body mass, ERD was noted. Microscopic examination revealed infiltration of plasmacytes, lymphocytes, neutrophils, and histocytes with proliferation of myofibroblasts. Immunohistochemical staining showed that the plasmacytes were positive for IgG and approximately 40% of these cells were positive for IgG4 Fig. . Stainin0 mm was Four months later, the patient was referred to our clinic, complaining of eye pain and vision decline in the right eye and headache for 1 month, his BCVA was 12/20 in the right eye, and his intraocular pressure was 11 mmHg OD. Slit-lamp examination of the right eye revealed similar changes to the left eye 4 months ago. Prominent KP, slight AC flares, and moderate vitreous opacity were also observed in the right eye. Fundus examination revealed a gray-white mass located on the supratemporal peripheral fundus. The details of the mass could not be evaluated fully because of the moderate vitreous opacity. No other significant retinal abnormalities were observed on indirect binocular ophthalmoscopy. B-ultrasonography suggested a mass with high acoustic reflectivity in the supratemporal peripheral fundus. UBM showed a mass in the superior-temporal part of the ciliary body measuring 7.7 mm × 2.4 mm, with a subconjuntival lesion Fig. . No otheThe patient was treated with 500 mg intravenous methylprednisolone for the first 7 days, followed by oral methylprednisolone (50 mg/day). Peribulbar injections of 5 mg dexamethasone once and prednisolone acetate  every 2 hours while awake were also administered to the right eye. The mass and intraocular inflammation gradually attenuated in the follow-ups by serial monitoring using slit lamp photography, UBM, B-ultrasonography, wide-angle fundus photography Fig. , and aquThe frequency of IgG4-ROD ranges from 4 to 34% in IgG4-RD patients according to the largest case series published to date . AccordiIn cases of orbital or intraocular masses, it is important to differentiate IgG4-ROD from malignant tumors  and similar diseases , 5. In oA long delay in the diagnosis of IgG4-RD remains common and may be responsible for irreversible sequelae due to extensive fibrosis . Most reWith advances in technology, several novel imaging modalities are available. Each modality has its pros and cons as well as its limitations. A combination of multiple imaging techniques can overcome these individual weaknesses and provide a comprehensive picture. Multimodal imaging is the concept of “bundling” images obtained from various imaging modalities that enable accurate localization and in vivo near-histologic assessment of ocular tissue, greatly aiding the clinician in establishing a diagnosis and monitoring the therapeutic response of ocular lesions. In the present case, we combined techniques including MRI, slit lamp photography, UBM, B-ultrasonography, and wide-angle fundus photography to evaluate ocular lesions. Notably, the bulbar conjunctival swelling observed by slip lamp in the lesion location 40 days after treatment might be easily considered as a sign of aggravation. However, as a powerful ophthalmic imaging tool for detecting anterior segment lesions of the eye , UBM cleCytokines play essential roles in inflamed eyes. Elevated aqueous humor concentrations of cytokines have been reported for different types of uveitis, and diverse cytokine profiles have been shown to be characteristic of specific diseases . ConsequDuring treatment, ocular inflammation was effectively suppressed, and the levels of these cytokines were gradually restored. During the dynamic accumulation of the subconjunctival fluid after treatment with UBM, IL-6 showed a simultaneous gradual increase, indicating fluctuation of the intraocular inflammatory state. With resolution of the subconjunctival fluid and disappearance of the ciliary mass, the IL-6 level was readjusted to nearly normal according to the aqueous humor cytokine analysis. Our observations suggested that cytokine level detection is another effective tool for estimating intraocular inflammatory activity, monitoring disease progression, and evaluating therapeutic effect in IgG4-ROD.A high rate of systemic IgG4-RD involvement exists in patients with IgG4-ROD, particularly in bilateral cases. In a retrospective observational case series study, 14% of patients with unilateral IgG4-ROD and 79% of patients with bilateral IgG4-ROD had extra-ophthalmic involvement . The mosSystemic prednisone is recommended as first-line therapy because a high rate of response to prednisone is a common feature of IgG4-ROD. Immunosuppressive therapy may be required in steroid-sparing or steroid-resistant cases . OphthalIgG4-ROD can be challenging to diagnose as a new and rare entity, especially in cases of atypical features, such as ocular mass, conjunctival infiltration, uveitis, or scleritis. It should be suspected in any chronic inflammatory ophthalmological manifestation after excluding the more frequent alternative diagnoses. Combined with ocular cytokinome profiles, multimodal imaging can help detect lesions, monitor disease progression, and guide therapeutic strategy.


Evaluation of the appropriateness of the duration of antimicrobial treatment is a cornerstone of antibiotic stewardship programs, but it is time-consuming. Furthermore, it is often restricted to antibiotics prescribed during hospital admission. This study aimed to determine whether mandatory prescription-indication registration at the moment of prescribing antibiotics enables reliable automated assessment of the duration of antibiotic therapy, including post-discharge duration, limiting the need for manual chart review to data validation.Antibiotic prescription and admission data, from 1-6-2020 to 31-12-2021, were electronically extracted from the Electronic Medical Record of two hospitals using mandatory indication registration. All consecutively prescribed antibiotics of adult patients who received empiric therapy in the first 24 h of admission were merged to calculate the total length of therapy (LOT) per patient, broken down per registered indication. Endpoints were the accuracy of the data, evaluated by comparing the extracted LOT and registered indication with the clinical notes in 400 randomly selected records, and guideline adherence of treatment duration. Data were analysed using a reproducible syntax, allowing semi-automated surveillance.A total of 3,466 antibiotic courses were analysed. LOT was accurately retrieved in 96% of the 400 evaluated antibiotic courses. The registered indication did not match chart review in 17% of antibiotic courses, of which only half affected the assessment of guideline adherence. On average, in 44% of patients treatment was continued post-discharge, accounting for 60% (± 19%) of their total LOT. Guideline adherence ranged from 26 to 75% across indications.Mandatory prescription-indication registration data can be used to reliably assess total treatment course duration, including post-discharge antibiotic duration, allowing semi-automated surveillance.The online version contains supplementary material available at 10.1186/s13756-022-01147-2. Antimicrobial Stewardship Programs (ASP) aim to reduce antimicrobial resistance and its associated morbidity, mortality and healthcare costs . One of . Utilizing indication selected at time of order entry also enable stewardship programs perform targeted real-time interventions, as many other methods (like using ICD-10 s) can only occur post-discharge. Dyer and colleagues showed that it is feasible to extract from the EMR the total duration of antibiotic use prescribed to inpatients per registered ICD-10 diagnosis, including post-discharge prescriptions [An in-depth audit assessing the appropriateness of choice and duration of antibiotic therapy for each individual antibiotic course until recently required manual data collection from the (electronic) medical record (EMR), which is time-consuming , 8. As ariptions . It is iriptions . UnfortuIn a previous study we showed that it is feasible to link antibiotic indications to antibiotic prescriptions by mandatory indication registration, which enables systematic evaluation and benchmarking of the appropriateness of the empiric antimicrobial choice for respiratory tract infections (RTI) and urinary tract infections (UTI) , 11. TheA retrospective observational study was performed on data obtained from the Amsterdam University Medical Centres (Amsterdam UMC), a university-affiliated tertiary care hospital with two locations: AMC and VUmc. Both locations use EPIC software as their electronic medical record and prescribing software. In 2019, a standardized prescription-format  class J01, the prescription-linked registered indication on tract level  and a further specification in case of respiratory tract infections (RTI) and urinary tract infections (UTI), the duration of hospital admission (time and date of admission and discharge), the duration of therapy , and the specialty of the prescribing physician.For the purpose of this study, we identified all antibiotic prescription in patients admitted to any general ward who were prescribed empirical antibiotic treatment. Hospitalized patients were defined as patients that were admitted for at least 12 h. Empirical antibiotic treatment was defined as the prescription of systemic antibiotics at time point 24 h of hospitalization, or at the time of discharge in patients who were hospitalized for 12–24 h. These empirical inpatient prescription orders with a registered indication were merged with consecutively prescribed antibiotics during hospital admission and post-discharge, to define the total antibiotic treatment course per patient. The last registered indication during the admission was considered as the definitive indication for the full treatment course  and patients admitted to the Intensive Care Unit, because guideline-recommended treatment is usually not applicable in this setting, as well as patients who received antibiotics for two different indications that were registered simultaneously.We first extracted all aforementioned antibiotic prescribing and hospital admission data from the EMR and selected the records meeting our inclusion criteria Fig. . We inspwww.amsterdamumc.swab-id.nl). When the LOT fell within the guideline-recommended treatment duration range we considered it guideline-adherent. We added a margin of one day, as days of therapy are registered irrespective of the number of doses .The primary endpoint was the accuracy of the electronically obtained length of therapy (LOT). LOT was defined as the number of calendar days during which antimicrobials were consecutively prescribed for the definitive indication, including post-discharge duration, irrespective of the number of agents or doses on each calendar day. Accuracy was defined as percentage agreement between 1) the electronically obtained LOT and the manually retrieved LOT from the EMR; 2) the registered indication and the manually retrieved indication from the EMR, as for determination of guideline adherence the registered indication has to be correct. Secondary endpoint was the percentage of antibiotic treatment courses of which the LOT was according to local guidelines. The local guidelines are based on the national guidelines of the Dutch Working party on Antibiotic Policy (The median LOT and interquartile range (IQR) are presented for each registered indication. We provide total LOT. We calculated per indication the percentage of treatment courses in which part of the treatment was given post-discharge. For these courses we provided the proportion (± SD) of the total treatment duration that was given post-discharge. The proportion of guideline (non)-adherent prescriptions is expressed as percentage of the total number of antimicrobial prescriptions for that indication. All data handling and visualisation was performed using TIBCO® Spotfire®.The extracted data from the EMR yielded a total of 142,470 systemic antibiotic prescriptions (J01) (including post-discharge and outpatient clinic prescriptions that were not linked to an indication). Of these, 81,867 systemic antibiotic prescriptions (J01) were prescribed during hospital admission and were therefore linked to a registered indication. After general inspection of the data, including manual chart review, we excluded erroneous prescriptions, defined as prescriptions of which the start date of the antibiotic fell before the date of admission. Also, prescriptions that were labelled as cancelled were excluded, as these were not administered to patients. The remaining 71,515 prescribed systemic antibiotics (J01) represented 27,399 antibiotic courses. Applying our pre-defined in- and exclusion criteria resulted in 3,466 antibiotic courses for further analysis. A schematic overview of the selection steps and yield is presented in Fig. Of the final dataset, a random sample of 400 records was evaluated on accuracy Table . OverallWe also compared the selected indication with the diagnosis that was recorded in the patient record and found an error-rate of 17.3% (68/400). Although the tract of infection was mostly accurate, its specification was not always. Gastro-intestinal and intra-abdominal infections were commonly selected interchangeably. Furthermore, sometimes cystitis was selected instead of complicated UTI; severe community-acquired pneumonia (CAP) instead of mild-to-moderate CAP; fever of unknown cause instead of febrile neutropenia, or therapy instead of prophylaxis. Of these incorrectly registered indications, 51.5% affected the assessment of guideline-adherent LOT. This was mainly the case for the inaccurate selection of cystitis instead of complicated UTI or therapy when it actually concerned prophylaxis.The median LOT per indication is presented in Table The guideline recommended total duration of therapy per indication and the adherence rate per indication are also presented in Table This study shows that it is feasible to reliably extract from the EMR the total duration of antibiotic therapy, broken down per indication and including post-discharge treatment, enabling an automated assessment of the appropriateness of antibiotic treatment duration. General inspection, and if indicated, optimization of the dataset  is necessary to enable the use of data for further analysis. The total duration of therapy was accurately extracted from the EMR in 96% of infections, but the registered indication did not match the indication documented in the patient records in 17% of cases, which was mainly due to inaccurate selection of the mandatory indication in the EMR. Only 50% of these indication errors affected the evaluation of appropriateness of LOT, but local validation of the datasets is therefore necessary and the error-rate should be considered when data is used for quality measurement purposes. With regard to our secondary study aim, guideline non-adherence due to excessive treatment duration varied from 10 to 50% per indication, showing possibilities for quality optimization.Including therapy after hospital discharge in the treatment duration is necessary, as a considerable amount of excess antibiotic use occurs after discharge, which was previously shown for CAP . In our In previous studies the total duration of therapy linked to indication was either assessed by manual chart review , 8, 13 oOur inclusion criteria ensured a reliable dataset for the most common infections. We were able to confirm that by applying our inclusion criteria, the total duration of therapy was accurately extracted for almost all indications, with prescriptions in the OPAT setting being the most important exception. The error-rate of 4.5% of the electronically extracted LOT was far lower than the 11.5% discrepancy Dyer et al. found . As elecBased on the Capability-Opportunity-Motivation Behaviour model, designed by Michie and colleagues, behaviour can only occur when an individual has the capability, opportunity and motivation  to perform the behaviour . The phyFinally, we showed the opportunities of using mandatory indication registration and assessment of the appropriateness of treatment duration to identify clear targets for ASP. The treatment duration for mild-to-moderate severe CAP, for example, was shown to be too long in 40% of patients, considering the guideline recommendation of five days. Each day of antibiotic therapy is associated with 4% increased odds of experiencing an adverse event , while sDue to our inclusion criteria we did not evaluate all antibiotic courses prescribed during hospital admission. We focused on patients that were initially empirically treated to enable reliable data extraction, as this method was already used and validated in our previous study . In addiWith this study we demonstrated that implementing mandatory indication registration in the EMR enables a reliable and efficient method for systemic registration of two core-elements of ASP: the guideline adherence of the total duration of antibiotic therapy and the guideline adherence of empiric antibiotic choice, the latter we showed in our previous study . It has Additional file 1. Electronic medication registration prescription format.


Electro-hydraulic shaking table is an essential experimental apparatus to evaluate structural performance under actual vibration condition. The control-structure interaction (CSI) between shaking table and eccentric load has lately received considerable attention for causing the accuracy degradation of shaking table test. At present, the research gap of the influence of the eccentricity of load on the CSI makes it challenging to find the CSI effects. And an effect assessment is yet to be proposed to evaluate the CSI effects, which has impeded the development of test technology. To overcome those theoretical bottlenecks, in this research, an analytical transfer function matrix of shaking table and eccentric load is established to analyze the CSI effects. The analysis is conducted under such conditions as different mass ratio (MR), moment of inertia ratio (IR), and eccentric distance ratio (ER) conditions. Through the analysis, the role of the ER is identified, the sensitivities of the MR, IR, and ER to the transfer function matrix are revealed, and the CSI effects are found. Furthermore, a novelty effect assessment is proposed to appraise whether the CSI effects can be ignored in shaking table test. And the visualization expression of the effect assessment is obtained for convenient application. In the context of shaking table test, the control-structure interaction (CSI)13 is the dynamic coupling between shaking table and load (that is the test structure model)  and the other models  and servo valve delay to the MST. The study revealed that the control gain and the delay of servo valve have significant impact on the MST. Li et al.25 analyzed the stability of the MST under different TVC parameters. The analysis showed that better system stability can be obtained with the no-load TVC control parameters. The influences of mechanical installation error, displacement measurement error, and bias of servo valve on the MST were considered in a study by Zhang26. The study shows the MST is only related to the bias of servo valve. And the CSI effects increases with the bias of servo valve. Yan studied the influence of the mass of exciter on the MST and found that the CSI effects increase with the mass of exciter27. The influence of the stiffness of hinge on the MST is investigated by Xie28. The investigation suggests that the stiffness hinge should be increased as much as possible. Maoult et al.29 adopted finite element modeling to investigate the phenomenon of structural frequency reduction in large-scale shaking table experiments. The investigation demonstrated that the deformation of shaking table is the main reason for the CSI effects. In other words, the deformation of shaking table is one of the factors that affect the MST. Wang30 and Li31 studied the CSI effect between dual shaking tables and structure. The study revealed that the coupling effect between the two shaking tables have significant impact on the MST at the frequency of structure and its surrounding frequency band.From the aspects of shaking table characteristics, many scholars have analyzed the effects of control parameters, the time delay and the bias of servo valve, the stiffness of hinge, the mass of hydraulic cylinder, the deformation of platform, and the coupling between two shaking tables on the MST Fig. e. Trombe32 analyzed the CSI effects on the flow requirement model of servo valve, the force requirement model of exciter, and the resonance response model of load. The analysis was conducted under different load mass, the damping ratio of load, and the frequency of load conditions. The analysis shows the CSI must be considered in designing of the actuator force of actuator, and the flow requirement of servo valve can be achieved without considering the CSI when the flow requirement in the low-frequency band is satisfied.Additionally, Wang et al.33. Guo et al.34 investigated the influence of different test structures on the control performance of shaking table, and the investigation showed that the control performance is greatly affected by the eccentricity of test structure. Therefore, it is necessary to study the CSI effects between shaking table and eccentric load. Moreover, the eccentric degree of load and the moment of inertia of load are important characteristics that have not been analyzed in previous studies. Furthermore, no effect assessment has been proposed to evaluate the CSI effects, and thus, the existing research needs to be further expanded.To date, researchers have conducted studies that are limited to analyzing the CSI effects between shaking table and centrosymmetric load. However, most of loads in shaking table test are non-centrosymmetric. The CSI increases greatly when an eccentric load is loaded on shaking table in the studies of Zhao et alIn this study, an analytical transfer function matrix is established to analyze the CSI effects between twin-axes shaking table and eccentric load. Based on the transfer function matrix, an in-depth investigation is conducted under different MR, IR, and ER conditions. The sensitivities of the MR, the IR, and the ER to the transfer function matrix, as well as the influence frequency range and the influence trend of the CSI effects, are found in the investigation. Furthermore, a novelty effect assessment is proposed to appraise the CSI effects.The schematic diagram of the twin-axes shaking table and eccentric load is presented in Fig. The transfer function matrix is established according to the modular method presented in Fig. The dynamic model is the motion mechanism part of the shaking table and eccentric load. Without regard to the stiffness and the damping between the platform and the connecting rod, the dynamic model of the shaking table and eccentric load is shown in Fig. Figure Based on Eq. , the NewThe hydraulic-driven system is the driven part of the shaking table and eccentric load. The servo valve and the hydraulic cylinder are the two core components of hydraulic-driven system, the schematic diagram of which is demonstrated in Fig. 35, and the transfer function of servo valve isGenerally, servo valve can be regarded as a second-order oscillation link36. The Laplace transform is applied to the continuity equations, and the converted form can be described as followsCombined with servo valve and hydraulic cylinder, the hydraulic-driven system can be expressed by a series of continuity equationsThe TVC model is the control part of the shaking table and eccentric load. The TVC model consists of feedback loop, feedforward loop, and generator of the TVC, the schematic diagram of which is presented in Fig. 32, the control error signal isAccording to the TVC system modeling process presented in Ref.The analytical transfer function matrix is established based on the three sub-models. Assuming the parameters of exciter 1 and 2 are the same, the transfer function matrix can be described asSubstituting Eqs. , 6) and and6) anConverting Eq.  into a tBased on the transfer function matrix, an in-depth analysis is conducted to find the sensitivity of the MR, IR, and ER to the transfer function matrix, and the influence trend and degree of the CSI effects on the transfer function matrix. The analysis is carried out under different MR, IR, and ER conditions. According to the Tables For comparing and analyzing the CSI effects on the transfer function matrix, the condition that the shaking table with no load is defined as a reference condition. In the analysis, the absolute value of the amplitude frequency characteristics of Figure Figure Figure According to Fig. The above “Analysis of the CSI effects” proves that the CSI exerts different degrees of effects on the transfer function matrix. However, the above analysis needs to be further expanded to appraise the CSI effect in practical experiments. To appraise whether the CSI effects can be ignored in shaking table test, a novelty effect assessment is proposed. Two steps are involved in proposing the assessment. The first step is the deduction of the assessment, and the second step is the visualization expression of the assessment.The “Analysis of the CSI effects” proves that the MR, IR, and ER have influence on the mentclass2pt{minimIt is assumed that the assessment can be expressed as follows:Referring to the expressions of als, Eq.  can be wEmploying /MT, Eq.  can be eAccording to a/l, Eq.  can be cFinally, Eq.  can be oWith the combination of Eq. , the assFor the convenient application of the assessment, Eq.  is simplReferring to the basic characteristics of the shaking table in Table It can be analyzed from Eq.  that theAccording to the concept, the characteristics of the Based on the conclusion that the MR ≤ 0.75, the specific values of MR, − 0.75, 0.60, 0.45, and 0.30, are adopted to obtain the values of the ER. Then the coordinate points (The ER exerts effects on the transfer function matrix at the resonance peak of oil column frequency and its surrounding frequency band.The transfer function matrix is the most sensitive to the changes of the MR, followed by the ER and then the IR. The IR has slight influence on the transfer function matrix. Additionally, the CSI exerts different influence trend and the influence degree on the transfer function matrix under different MR, ER, and IR conditions.The CSI leads to a significant increase in the exciter coupling. The coupling between two exciters is amplified at least 37.15 times.The novelty effect assessment has a wide application prospect and practical value in appraising whether the CSI effects can be ignored in shaking table test.It is worth expanding the assessment to appraise the CSI effect between shaking table and flexible structure in the future.In this study, an analytical transfer function matrix is established to analyze the CSI effects between the twin-axes shaking table and eccentric load. Based on the transfer function matrix, a comprehensive investigation is conducted under different Supplementary Information.


Prophylactic antibiotic use during delivery is common in routine obstetric practice to prevent infection globally, especially in low- and middle-income countries. In China, however, little is currently known about the national estimates for prophylactic antibiotic use during delivery. Therefore, we aimed to describe the prevalence of prophylactic antibiotic use and guideline adherence using national data in China.This cross-sectional study analyzed a national dataset from the China Labor and Delivery Survey in 2015–2016. The primary outcomes were prophylactic antibiotic use and clinician adherence to WHO recommendations for the prevention and treatment of maternal peripartum infections. We estimated the weighted prevalence of the outcomes with Taylor series linearization and investigated the associated factors of the outcomes with logistic regression.Of the 72,519 deliveries, the prevalence of antibiotic prophylaxis was 52.0%, varying from 92.8% in Shanxi to 17.3% in Hainan. The prevalence of clinician adherence to the WHO guideline was 79.9%, ranging from 93.4% in Shandong to 50.0% in Shanxi. Prophylactic antibiotic use was associated with cesarean delivery , operative vaginal delivery , preterm , premature rupture of membranes (PROM) , and meconium-stained amniotic fluid  in all deliveries and also episiotomy  in vaginal deliveries. Clinician adherence was positively associated with cesarean delivery  while negatively associated with operative vaginal delivery , PROM , and meconium-stained amniotic fluid  in all deliveries. In vaginal deliveries, clinician adherence was negatively associated with episiotomy  and severe perineal trauma . Besides, clinicians in general hospitals prescribed prophylactic antibiotics more likely  and had a lower adherence  than their peers in maternity hospitals.We observed that about half of all deliveries in China received antibiotics for prophylaxis, and most deliveries were prescribed according to the WHO guideline. Furthermore, the two prevalence rates for prophylactic antibiotic use and clinician adherence varied widely across provinces of China.The online version contains supplementary material available at 10.1186/s12916-022-02577-w. Streptococcus, and premature rupture of membranes (PROM) could reduce maternal infections [Antibiotic prophylaxis is prescribed to prevent infections, not to cure or treat diseases . Prophylfections , 4 and ifections .These benefits of antibiotic prophylaxis have led to both a high and varied prevalence of prophylactic antibiotic use during labor and delivery worldwide. For example, more than 40% of pregnant women in the USA are given antibiotics immediately before delivery , and theThere are a lot of concerns over the inappropriate use of antibiotics during labor and delivery. Antibiotic overprescribing may contribute to antibiotic resistance and increased morbidity and lead to adverse outcomes for both the mother and newborn , 10. AntTo address these research gaps, we analyzed national data from 94 Chinese hospitals to describe the prevalence of prophylactic antibiotic use and clinician adherence to the WHO guideline in 2015 , as wellIn this cross-sectional study, we used data from the China Labor and Delivery Survey (CLDS) between March 1, 2015, and December 31, 2016. The CLDS is a national, multicenter, hospital-based, cross-sectional survey to collect the labor and delivery data of new births in China. Using a stratified multistage sampling design to permit a representative sample, the CLDS selected 112 hospitals with at least 1000 annual births from 25 (out of 34) provinces throughout China. The sampling strategy has been described elsewhere [The CLDS data coordination center (DCC) was established to coordinate hospitals, train investigators, and manage the database. For data collection, the CLDS DCC randomly selected 6 weeks within 12 months for hospitals with at least 6000 annual births or 10 weeks within 12 months for hospitals with less than 6000 annual births –17. The Maternal delivery records for all births within each selected week were eligible and extracted. However, the births at < 24 weeks of gestation or with birthweights of < 500 g were excluded –17.The CLDS has been reviewed and approved by the WHO Research Ethics Review Committee and the ethics committees in all participating hospitals. Our data request was approved by the CLDS DCC, and ethics exemption was approved by the Ethics Review Board of the Xinhua Hospital, Shanghai Jiao Tong University School of Medicine (XHEC-C-2015-006), because the data from maternal delivery records in selected hospitals were anonymized and de-identified.This study’s primary outcome was prophylactic antibiotic use during labor and delivery. According to antibiotic prescribing for prophylaxis in each maternal delivery record by the physician in charge, prophylactic antibiotic use was classified as yes (coded as 1), no (coded as 0), or unknown (coded as missing).The secondary outcome was clinician adherence to the WHO guideline on antibiotic prophylaxis in labor and delivery . We recoWe also documented other characteristics of the hospitals, including hospital level , hospital type , and hospital site .svy prefix commands based on the final person weights and primary sampling units  to account for the complex survey design of the CLDS. The statistical significance level was P < 0.05, and all tests were 2-tailed. Complete case analyses were used.This study did not have a prospective analysis plan before the survey. To obtain a national estimation of the labor and delivery information, the CLDS DCC calculated a survey weight for each delivery, and the weighting procedure has been described in detail elsewhere –17. We aIn the descriptive analysis, we calculated weighted prevalence estimates and corresponding 95% confidence intervals (CIs) of prophylactic antibiotic use and clinician adherence to the WHO guideline using Taylor series linearization. We also calculated the weighted prevalence of the two outcome indicators by province and mode of delivery. Besides, we estimated the weighted prevalence of the two outcome indicators for each characteristic studied herein.In the association analysis, we used logistic regression models to assess the association of potential factors of prophylactic antibiotic use and clinician adherence. Initially, we investigated each factor individually for the two outcome indicators using univariate regression models and calculated odds ratios (ORs) with 95%CIs. Subsequently, we included risk factors studied herein in the final model and estimated the adjusted ORs (AORs) with 95%CIs for each outcome indicator using multivariate regression models.This study is reported as per the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guideline , uterine rupture or dehiscence, hysterectomy, postpartum hemorrhage, blood transfusion, puerperal infection, amniotic fluid embolism, pulmonary embolism, deep vein thrombosis, and maternal ICU admission. Furthermore, we also estimated the prevalence of antibiotic over-prescription and under-prescription in this subpopulation.n = 1732) were excluded because the information on antibiotic use was invalid. Of the 73,396 participants from 94 hospitals in 23 provinces, the participants without data on antibiotic use (n = 877) were excluded from the analysis, and the missing rate was 1.2%  were secondary, and 66 (76.78%) were tertiary; 34 (47.82%) were maternity, and 60 (52.18%) were general. Of these deliveries, 44,220 (60.6%) were delivered by spontaneous vagina delivery, 1285 (1.6%) by operative vaginal delivery, and 26,726 (37.8%) by cesarean delivery.In total, 52.0%  of deliveries were given antibiotics for prophylaxis. The prevalence of prophylactic antibiotic use varied substantially across provinces, from 92.8% in Shanxi to 17.3% in Hainan  of all deliveries followed the WHO guideline. Similar to the prevalence of prophylactic antibiotic use, clinician adherence varied substantially across provinces, from 93.4% in Shandong to 50.0% in Shanxi Fig. A. For vaAs can be seen from Table After adjusting for additional obstetric conditions, we observed the same consistent associations when examining the prevalence of prophylactic antibiotic use and clinician adherence within vaginal deliveries only Tables  and 4. Pn = 41,376), the overall prevalence of prophylactic antibiotic use among vaginal deliveries was 26.1%, ranging from 87.9% in Shanxi to 2.6% in Hainan  for obstetric conditions has implications on global efforts to contain the emergence of resistant bacteria strains and, consequently, on global health . To reduImproving the clinician’s adherence to the antibiotic prescribing guidelines could reduce inappropriate prophylaxis antibiotic use during delivery because the guidelines were developed to limit the emergence of antibiotic resistance without compromising mother and infant health outcomes . InterveBesides clinician adherence, reducing cesarean delivery prevalence could also reduce the associated use of antibiotic prophylaxis. In China, about near 39% (37.8% in this study and 38.9% in a previous study ) of birtThe overall prevalence was 52.0% for prophylactic antibiotic use and 79.9% for clinician adherence, both with marked provincial variations. Compared with peers in general hospitals, clinicians in maternity hospitals are less likely to prescribe prophylactic antibiotics but more likely to prescribe following the WHO guideline.Additional file 1: Table S1. STROBE checklist for cross-sectional studies. Table S2. Missing data rate of prophylactic antibiotics use, stratified by province. Table S3. The rate of vaginal and cesarean delivery, stratified by province. Table S4. The prevalence of prophylactic antibiotic use, stratified by province and mode of delivery. Table S5. The prevalence of adherence to guidelines on antibiotic prophylaxis, stratified by province and mode of delivery. Figure S1. The rate of cesarean delivery, stratified by province. Figure S2. The prevalence of prophylactic antibiotic use among vaginal deliveries without therapeutic indications. Figure S3. The prevalence of adherence to guidelines on antibiotic prophylaxis among vaginal deliveries without therapeutic indications.


Bacillus subtilis, E. coli, and Pseudomonas sps.), and the loading  on concrete beams. Two beams were chosen from previous experimental research and simulated on the ANSYS before carrying out our parametric study to verify the validity of our simulation. Following this, our parametric study was carried out on eight beams; each beam was loaded gradually up to failure. The results show that the optimum type of bacteria was the Bacillus subtilis, and that the bacteria concentration of 3% for Bacillus subtilis can increase the beam’s capacity by 20.2%. Also, we found that distributing the load to four points led to the increase of the beam’s capacity by 74.5% more than the beam with a one-point load.Deterioration or crack formation in concrete elements is a phenomenon that cannot be easily avoided, and it has a high cost of repair. A modern technology that needs wider study is the use of the bio-precipitation of calcium carbonate using bacteria to increase a structures’ capacity. The current research presents an analytical study on self-healing concrete beams using bacteria to enhance the beam’s capacity. A Finite Element Analysis on (ANSYS 15.0) was carried out to study the effect of the bacteria concentration , the type of bacteria ( The use of self-healing bacterial concrete in real applications became a topic of interest due to its ability to extend the service life of structures. Considerable research has been undertaken on the mechanical properties of bacterial concrete cubes and cylinders, but few studies have applied this technique to the reinforced concrete elements on a large scale such as beams, columns, and slabs, etc. Therefore, we still need to study the matter more extensively with different parameters.The use of self-healing concrete can prove its efficiency as smart material, designed and inspired by nature such as in skin tissue or bone structure ,2. Natha3 by the induced bacteria to heal microcracks has also been investigated through many other studies [Bacillus subtilis bacteria [Bacillus sp. bacteria on the durability properties and remediation of cracks in cementitious structures [3-reducing bacteria to enhance crack closure performance of microbial mortar [Microcracks can create a direct pathway for undesired substances to penetrate concrete elements, causing reinforcement corrosion and requiring costly manual maintenance and repair. These cracks affect the structure’s functionality, and they also affect the durability and strength of the structure ,6. An in studies ,14. H. M studies . H. M. J studies . Mian Lu studies . Wasim Kbacteria . C. Lorsbacteria . N. H. Bbacteria . Varenyaructures . A. Faisructures . M. O’Coructures . Yusuf el mortar  and to dl mortar . Wiktor l mortar . Mohammal mortar . Shashanl mortar .Bacillus subtilis to reinforced concrete beams to examine the flexural behavior of bacterial demolition waste concrete; their experimental results were validated with the use of the Finite Element Software Abaqus [Only a small number of numerical studies have been carried out to explain the self-healing process of cementitious elements, such as I. Rohini et al. who added the e Abaqus . Aliko-Be Abaqus . Also, Se Abaqus .Bacteria concentration ;Bacillus subtilis, E. coli and Pseudomonas sps.);Type of bacteria .With reference to previous research it can be concluded that adding bacteria to the concrete mix for cubes, cylinders, and prismatic specimens has a significant effect on enhancing their mechanical properties;however, we still need to apply this technology to the reinforced concrete elements on a large scale such as to beams, columns, and slabs, etc. Therefore, the current research is an investigation into adding bacteria to reinforced concrete beams by changing three different parameters on software package (ANSYS 15.0):The Finite Element Models on ANSYS APDL are verified initially by two experimental beams previously tested by Milan Joy et al. , followeThe reinforced concrete beams were simulated on ANSYS APDL using three dimensional elements: SOLID65, LINK180, and SOLID185 for concrete, reinforcement, and steel plates, respectively. The mechanical properties for the concrete elements were assumed to be changed during the solution for each model (except the control specimen which did not contain bacteria) to simulate the activation of bacteria, which happened in the laboratory for the actual beams when the bacteria received nutrition due to the opened cracks. The mechanical properties of bacterial concrete could be graduated through the modelling from those of concrete without bacteria to those of concrete with bacteria using the command (MPCHG), after reaching the load step in which the cracks begin to appear.SOLID65 was used to model concrete. The element was defined by eight nodes having three degrees of freedom at each node: translations were in the nodal x, y, and z directions. The solid was capable of cracking in tension and crushing in compression. A 3-D element (LINK180) was used to model the reinforcement. The element was a uniaxial tension–compression element with three degrees of freedom at each node: translations were in the nodal x, y, and z directions. Tension-only (cable) and compression-only (gap) options were supported. A 3-D solid element (SOLID185) was used to model the steel plates for loading and support. The aim of this section is to verify the validity of our simulation on ANSYS, and not to repeat the previous work. Therefore, after the verification, we could build an analytical study based on our own parameters. Two reinforced concrete beams from previous experimental work by Milan Joy et al.  were choControl Specimen (CS);Bacterial concrete beam with fly ash (BCFA).Two beams from Milan’s experimental work  were choBacillus subtilis was selected in Milan’s research. The mechanical properties of concrete with and without bacteria and fly ash were obtained. The compressive strength was obtained from cubes of 150 mm on each side and the split tensile strength was obtained from cylinders of 150 mm in diameter and 300 mm in height. The bacteria species A parametric study was carried out on eight beams with the same concrete dimensions and reinforcement details as the previous verification models. The eight beams were divided into three groups.Bacillus subtilis)—the most popular of all types. It was the same case for loading (two-point load). A comparison was then made with the conventional beam (the control beam without bacteria).Group (1) addressed the first parameter (bacteria concentration), with all other parameters kept constant except the bacteria concentration for the purposes of comparison. The bacteria concentration was the weight of the bacteria to the weight of cement, and it differed between 1%, 2%, and 3% for the same type of bacteria (Bacillus subtilis with the effect of adding other bacteria types (E. coli and Pseudomonas sps.) with the bacteria concentration remaining constant at 3% and the loading at a two-point load. Comparisons were made with the control specimen.Group (2) addressed the second parameter (the type of bacteria). In this group, we began to compare the effect of adding Bacillus subtilis. Three cases of loading were used: a one-point load, a two-point load, and distributed loads on four points.Group (3) addressed the third parameter (case of loading) and its effect on the capacity of beams with a constant bacteria concentration; the type of bacteria was 3% of All beams were simulated on ANSYS using the same elements: SOLID65, LINK180, and SOLID185 for concrete, reinforcement, and steel plates. The failure loads were obtained, and the displacements were measured at the mid-span of beams for each load step, then the load-displacement curves were drawn. The crack patterns and modes of failure were also illustrated.ans) to experimental failure load (Pexp) as follows:ans)/(Pexp)% for the control specimen (CS) = 91.4%;(Pans)/(Pexp)% for the bacterial concrete beam with fly ash (BCFA) = 94.5%.. Three concentrations of bacteria were studied  for the same type of bacteria  at the same concentration of 3%. The following bar chart in As shown in the previous parameter, a percentage of 3% is more effective for enhancing the beam’s behavior. Therefore, in the current section, three types of bacteria were investigated  with a constant bacteria concentration and type of bacteria. The results show that distributing the load to many points enhanced the beam’s capacity. The beam with the distributed load on four points had a higher capacity by 74.5% than the beam with a one-point load and a higher capacity by 13% than the beam with a two-point load. The following bar chart in The crack patterns are illustrated in The bottom reinforcement in all beams in each parameter reached the yield stress before the concrete failed due to a ductile failure, which is desireable in the beam design process. ans) represented 91.4% to 94.5% of the experimental failure loads (Pexp) which is good agreement with the verification models:a.ans)/(Pexp)% for the control specimen (CS) = 91.4%(Pb.ans)/(Pexp)% for the bacterial concrete beam with fly ash (BCFA) = 94.5%;(PThe ANSYS failure loads (PAdding bacteria to the reinforced concrete beams increased their capacity and decreased the deflection, depending on the bacteria type and concentration;Bacillus subtilis was the optimum type of bacteria and had a higher significant effect than the E. coli and Pseudomonas sps. especially with a concentration of 3%, as it increased the capacity of the beam by 20.2% and decreased the deflection by 15.7%, compared to the control specimen without bacteria;The Bacillus subtilis to the reinforced concrete beams had approximately the same effect on the beam’s capacity, which increased by 16.2% and 17%, respectively, compared to the control specimen without bacteria;Adding 1% and 2% of Bacillus subtilis to the reinforced concrete beam had no effect on deflection, as it decreased the deflection by 2% only;Adding 1% Pseudomonas sps., even with a concentration of 3%, was unable to decrease the deflection at all;The use of Distributing the load on many points enhanced the beam’s capacity to support more than a concentrated load on one or two points, as the beam with the distributed load on four points had a higher capacity by 74.5% than the one-point loaded beam, and by 13% than the two-point loaded beam. Also, the deflection decreased for the beam with a distributed load on four points by 77.8% when it was compared to the one-point loaded beam, and 67.6% when it was compared to the two-point loaded beam.According to the current analytical study on the ANSYS software package, the following conclusions are obtained:Low and high temperature;The structures’ scale;Carrying out an experimental study;Changing the nutrition type for bacteria;Using capsules to preserve bacteria inside the concrete until cracks occur;Adding bacteria to the marine concrete.A greater number of parameters could be studied to understand more widely the self-healing nature of concrete using bacteria and to discover their benefits. Also, the study could be repeated for other types of elements such as columns, slabs, and frames, etc., instead of beams, to understand the behavior of these elements under the use of self-healing concrete. The following parameters can be taken into consideration:Some limitations may be facing this analytical study such as simulating the nutrition of bacteria or simulating capsules to preserve bacteria inside the concrete until cracks occur. Therefore, these two parameters need further experimental study to assess their potential implementation.


We use a compatibility equation based on the planar crack hypothesis, i.e., the assumption that the crack surfaces remain plane throughout the fracture process, which was recently proven true using digital image correlation. Non-cracked concrete bulk follows a stress–strain law (σ − ε) combined with the Bernoulli–Navier assumption. We define a brittleness number derived from non-dimensional analyses, which includes the beam size and the softening characteristics. We show that this parameter is key to determining the FRC flexural strength, characterizing fiber-reinforced concrete, and reproducing the size-effect of sections in flexure. Moreover, we propose an expression to calculate the flexural strength of FRC as a function of the cited brittleness number. The model also gives the ratio between the residual strength in service conditions and the flexural strength. Model results show a good agreement with tests in the scientific literature. Finally, we also analyze the brittle–ductile transition in FRC sections.This article describes a model based on concepts of Fracture Mechanics to evaluate the flexural strength of fiber-reinforced concrete (FRC) sections. The model covers the need by structural engineers to have tools that allow, in a simple way, the designing of FRC sections and avoiding complex calculations through finite elements. It consists of an analytical method that models FRC post-cracking behavior with a cohesive linear softening law ( Fiber-reinforced concrete (FRC) is a composite material characterized by a cementitious matrix and discrete fibers. The matrix is either concrete or mortar. Fibers can be of steel, polymers, carbon, glass, or natural materials and they provide post-cracking residual strength ,2. Thus,The flexural strength in quasibrittle materials, such as FRC, does not coincide with the tensile strength and it is widely accepted that it is size-dependent . Indeed,σ − w) law to represent the softening, or (ii) the smeared crack band model firstly advanced by  of b*w.In 3, which is a usual range in fiber reinforced concrete elements. x-axis represents the brittleness number, H,FRCβ, and the y-axis the maximum non-dimensional bending moment during crack growth, max*M. The model follows the experimental trends of experimental results with good agreement. Dotted horizontal lines represent the theoretical limits to the non-dimensional moment max*M as will be explained in the next section.To validate the response of the model, we compared the results obtained with experimental results from the bibliography ,42,43,44max*M depending on the brittleness number, H,FRCβ, is easy to obtain.This could be useful to take into account for FRC sections in the structural design, thus the prediction of the non-dimensional moment The flexural strength or modulus of rupture of a FRC section is defined as:x-axis represents the brittleness number, H,FRCβ, and the y-axis represents the non-dimensional flexural strength, R*f, which is defined as the ratio between the flexural strength, Rf, and Ftfs. The results obtained with the model are plotted with the expressions for the flexural strength evaluated by Uchida et al. , as was explained in Ftuf/Ftsf between 0 and 0.8 for conventional FRC, which correspond with ratios Rf3/Rf1 in the range a–d according to Mode Code 2010 [R*f to 2.5.Equations (20)–(23) cover ratios of ode 2010 . So, we A minimum quantity of fiber in FRC elements can be determined to avoid brittle failure by imposing that the maximum cracking load, due to the matrix behavior, is lower than the ultimate load. This critical fiber quantity value is a limit that provides a ductile post-peak response of FRC members . Figure crM is the cracking moment of the concrete matrix and maxM is described in tf is the tensile strength of the concrete matrix and Rf is the flexural strength or modulus of rupture. So, the behavior of the FRC section can be described in a non-dimensional form as:t*f, is equal to tf/Ftsf. So, if t*f is bigger than R*f, fiber concrete section presents a brittle behavior, and, if t*f is lower than R*f, fiber concrete section presents a ductile behavior. Rearranging Equation (20) as a function of H,FRCβ, and considering the limit condition in Equation (25), Equation (28) gives the value of the maximum brittleness number that has a ductile behavior for a given base concrete tensile strength. In other words, if a section has a brittleness number, H,FRCβ, less than H,FRC,maxβ, for a given value of t*f, this section will be ductile.The limit condition is:tf, and the brittleness number, H,FRCβ. In x-axis represents the brittleness number, H,FRCβ, and the y-axis the non-dimensional tensile strength of the base concrete, t*f. Two areas are drawn defining the FRC section behavior (ductile or brittle). The boundary curve between brittle–ductile behavior is given by Equation (28).Thus, the ductile or brittle response of a FRC section is determined by only two parameters, namely the tensile strength of the base concrete, csl to evaluate strains from crack openings, as is commonly carried out in models based on stress–strain laws.The planar crack assumption can be considered as an alternative to Navier’s hypothesis to model the FRC cracked zone. Using this approach, we avoid using length parameters as H,FRCβ, analogous to the one of Hillerborg, as a characterization parameter of FRC structural sections. It is derived from a nondimensional analysis, which includes the beam size and FRC softening characteristics.We propose a brittleness number, The model fits experimental results very well. Moreover, the model reproduces the asymptotic behavior expected from plastic limit solution for cohesive cracks—very short depths—to the linear elastic solution—overly large depths.H,FRCβ and on the serviceability residual stress, Ftsf. Its range of validity covers most of practical cases and thus, it can be profitably used for the structural design of FRC sections.We offer an expression to calculate the flexural strength of a fiber-reinforced concrete section based on the model results. It depends on the brittleness number, tf, and the brittleness number, H,FRCβ.The model, also, allows studying the ductile–brittle transition in FRC sections. It depends only on two parameters, namely the related tensile strength of the base concrete, The planar crack model contributes to a better understanding of the nature of flexural behavior of FRC sections and gives a more physical approach to their failure behavior. In addition, the expressions derived from the model results can be used for structural engineering purposes, constituting a design toolset that avoids complex calculations through finite elements.An analytical model based on concrete Fracture Mechanics is presented to evaluate the flexural strength of FRC sections. The following conclusions can be drawn from the study: