This paper presents comprehensive testing results  for OPC (Ordinary Portland Cement) and PLC (Portland Limestone Cement) concretes with 1% nano CaCO3 and compares them to those for concretes with fly ash (both Class F and C). Compared to concretes with fly ash, OPC and PLC with nano CaCO3 presented improved testing results in most cases, including later age strength, permeability, and scaling resistance. As nanotechnology in concrete is a relatively new topic, more research on the efficient use of nanotechnology, such as for proper dispersion of nano CaCO3 in the concrete, has potential to offer increased benefits. Further, nano CaCO3 is environmentally and economically viable, as it has the potential to be produced within the cement plant while utilizing waste CO2 and generating economic revenue to the industry. Thus, nano CaCO3 has the potential to serve as an alternative to fly ash in all beneficial aspects—economic, environmental, and technical.Fly ash is widely used in the cement industry to improve the performance and durability of concrete. The future availability of fly ash, however, is a concern, as most countries are inclining towards renewable energy sources as opposed to fossil fuels. Additional concerns have been raised regarding the impact of strict environmental regulations on fly ash quality and variability. This paper, therefore, evaluates if nano calcium carbonate (nano CaCO This ch2, nano TiO2, nano CaCO3, nano Fe2O3, nano Zr2O3, nano Al2O3, and nano graphene (CNTs and CNFs) in cementitious composites can significantly improve their performance and durability levels [Lately, nanotechnology has gained popularity where nanomaterials are being used as a partial replacement to cement clinker ,28,29,30y levels ,31,32. M3 is relatively cheaper [3 has the potential to be produced within the cement plant while utilizing the waste CO2 from cement production [3 helps reduce the CO2 emission from cement plants by 69%. The CO2 emission from cement plant was reduced from 0.96 kg CO2 eq./kg cement to 0.3 kg CO2 eq./kg. Thus, the use of nano CaCO3 (despite lower replacement rates as compared to fly ash) helps meet two key benefits—economic and environmental—of using fly ash in concrete. This paper now evaluates the technical viability of using nano CaCO3 as compared to benefits offered by using fly ash in concrete.As compared to several others, nano CaCO cheaper . Furtheroduction ,34. A re3 improved the early and later age strengths of Portland cement concretes. Additionally, a previous study by the authors presents comprehensive testing results on OPC and PLC with different replacement rates of nano CaCO3; 1% replacement provided the optimal performance, with increased later age strength and durability properties in both cement types. This paper compares the performance of OPC and PLC concretes with 1% nano CaCO3 to that of concretes with fly ash (both F and C) and evaluates if nano CaCO3 can be used as an alternative to fly ash. To the authors’ knowledge, no prior efforts have been done to evaluate the applicability of nano CaCO3 as an alternative to fly ash.Recent studies ,35,36,372/kg and type IL—Portland Limestone Cement (PLC) with Blaine fineness of 450 m2/kg were used as binders. Type IL PLC was produced by inter-grinding type I cement clinker with 15% of limestone in the cement plant. 3) with an average diameter of 40 nm and surface area greater than 40 m2/g.Type I/II—Ordinary Portland Cement (OPC) with Blaine fineness of 390 m3), (2) PLC (and with 1% nano CaCO3), (3) OPC (replaced with 20% Class C fly ash), and (4) OPC (replaced with 20% Class F fly ash). The properties evaluated were: (a) slump and setting of fresh concrete, (b) strength and modulus of elasticity of hardened concrete, and (c) concrete durability properties—permeability, alkali silica reaction (ASR), and scaling resistance. In addition, SEM (Scanning Electron Microscope) images for different samples were obtained. The mixture proportions for 0.76 m3 (1 cy) of concrete are given in 3 (650 lbs per 1cy) of concrete. No chemical admixtures were used in this experiment to limit the interference of other chemicals on the effects of nano CaCO3. During the mix preparation, nano CaCO3 and cement were placed in an electrically driven mechanical mixer and blended under high speed for three to four minutes prior to introducing them into the mixture. Previous studies [This paper presents comprehensive testing results for four different concrete types—concretes with (1) OPC  were tested at 3, 7, 28, and 56 days. The specimens were fabricated and moist cured in accordance with ASTM C192. A Rapid Chloride Penetration Test (RCPT) was conducted in accordance with ASTM C1202 using the Giatec Scientific test setup, where the charges passed through the specimen were automatically calculated at the end of six hours. For this testing, cylindrical specimens, 100 × 200 mm (4 × 8 in), were cured for 56 days as per ASTM C192. The cured specimens were then cut to the proper size (100 × 50 mm (4 × 2-in)) for testing, as prescribed by ASTM C1202. An Alkali–Silica Reaction (ASR) test was performed on prismatic specimens 25 × 25 × 254 mm (1 × 1 × 10-in), as per ASTM C1260, where sand with a high reactivity from a local source was used. The changes in length of the specimens were measured as per ASTM C157 at 5, 10, and 14 days. Scaling resistance was evaluated in accordance with ASTM C672. The testing was performed on beam specimens 150 × 150 × 610 mm (6 × 6 × 24-in) with plastic dikes of 19 mm (0.75 in) of height for the chloride solution. The specimens for SEM images were prepared as per ASTM C305, and the images were obtained using a Zeiss Crossbeam 540 FIB-SEM.3 were compared with those of concretes containing fly ash in order to assess whether nano CaCO3 could fill in fly ash as an effective mineral admixture. All the testing results presented in this paper are the averages of those of three specimens, except for scaling resistance (single specimen). Most of the measured values were within one standard deviation (1-SD), with few data extending over 2-SD. For better understanding of the test results, all the figures (as appropriate) are provided with error bars representing 1-SD.The properties of OPC and PLC concretes with 1% cement replacement by nano CaCO3 were compared with the corresponding test results for concretes with fly ash. The Tukey test was used as it has a low false positive rate, i.e., it provides a higher level of confidence for the differences to be real.Tukey multiple comparison test  was adopted as a statistical tool in evaluating significant differences. Here, the test results for concretes with 1% nano CaCO3 had minimal effects on the slump for OPC and PLC concretes. Although the water demand is expected to increase with the use of finer particles, lower replacement levels did not seem to affect the workability [kability .As we replaced the cementitious materials with pozzolans such as fly ash, the pozzolans reacted with calcium hydroxide, a product of cement hydration, thus inhibiting early hydration. This had a pronounced effect on the set time of the concrete, as illustrated in 3 further reduced the initial and final set times for both OPC and PLC concretes, with a larger reduction in PLC concrete. In PLC concrete, the combined dilution and filler effects increased the rate of hydration at early ages, thus lowering the set time. Additionally, the increased nucleation effect resulting in an increased C3S hydration rate also helped lower the set time for PLC [The addition of nano CaCO for PLC .The strength of concrete mainly depends on the amount of hydration products, the porosity of concrete, and the packing of the microstructure. 3 improved the strength of both OPC and PLC concretes at all ages, while exceeding the corresponding strengths when compared to concretes with fly ash. The improved strength was the result of an enhanced nucleation effect, which increased the rate of hydration. In addition, the formation of extra hydration products such as carboaluminates improved the porosity and packing of the microstructure, thus increasing the later age strength [3 serves as a better alternative to fly ash.Despite improved later age strength, one of the major limitations of using fly ash is the reduced early-age strength; this reduction limits its applicability, especially in cold weather regions. However, the use of nano CaCOstrength . Thus, a3 improved the modulus values for both OPC and PLC. Nano CaCO3 did not compromise the development of concrete stiffness, in contrast to as fly ash, and could serve as a better alternative to fly ash.The elastic modulus of concrete mainly depends upon the aggregate properties and porosity or densification of the paste. Since the same aggregate was used in all concrete types, no significant difference was observed. However, there seemed to be loose correlation between compressive strength and elastic modulus due to the denseness of the hydrated cement paste. The RCPT measures concrete resistivity, not permeability; however, it has been shown that a correlation exists between concrete resistivity and permeability . Figure On the contrary, PLC had the highest charges passed, followed by OPC concrete. The higher charge numbers passed in PLC concrete indicated dominant dilution effects in PLC. Further, as cited in Bonavetti et al. , chlorid3, however, improved the resistivity of both OPC and PLC concretes. OP-1 concrete exhibited the highest resistivity among all concrete types; the charges passed in OP-1 were approximately 30% and 35% less than those in concretes with Class F and Class C fly ash. The significant improvement in OPC was due to the improved packing and enhanced microstructure with a greater amount of hydration products. Likewise, similar improvements, but at a lower scale, were observed for PL-1 concrete. PL-1 concrete showed comparable resistivity values to those of fly ash concretes. This shows the potential of improving the microstructure of concrete at later stages using nano CaCO3 instead of fly ash, thus improving the durability of concrete.The addition of nano CaCO3 improved the scaling resistance of both OPC and PLC concretes. The OP-1 concrete showed a lower mass loss than both classes of fly ash, while PL-1 exhibited the least mass loss among all concretes. One of the reasons for the lowest mass loss in PL-1 could be the consumption of C3A at early ages to form carboaluminates, as explained by the inverse relationship between the amount of C3A and the scaling resistance of concrete [The addition of nano CaCOconcrete .3 improved the scaling resistance of both OPC and PLC concretes. As shown in 3. Thus, nano CaCO3 can help in mitigating another major limitation of fly ash concrete, thereby presenting a better alternative to fly ash in concrete applications in cold regions.Concretes with fly ash, thus, have lower resistance to scaling, which has been a concern in freeze-thaw environments. On the contrary, the use of nano CaCOThe alkali–silica reaction (ASR) in concrete occurs when reactive silica present in the aggregates react with hydroxide ions in pore solution to form expansive silica gel, which could cause micro cracks in concrete when moisture is absorbed. The expansion of concrete due to ASR depends on several factors such as alkali content of the cement, amount and reactivity of silica present in aggregates, availability of moisture, and porosity of the concrete. The maximum expansion was seen for the OPC concrete, and the least expansion was seen for the concrete with Class F fly ash. Several reasons for lower ASR in Class F fly ash concrete include the reduced porosity due to the pozzolanic reaction, binding of alkali in the CSH gel, and consumption of portlandite, which reduced the alkalinity of the pore solution. The expansion of Class C fly ash concrete was, however, much higher than that of Class F concrete, with an expansion nearly equal to that of OPC concrete. Research studies have shown that Class C fly ash does not reduce the expansion as effectively as Class F fly ash . This di3 significantly reduced the expansion of OPC by approximately 45%. The reduced microstructure porosity due to the filling of the micropores of concrete could be one of the major reasons for this reduction in expansion, as explained by Lochana et al. [3 was effective in reducing the expansion of both OPC and PLC, with values lower than that of Class C fly ash. However, its ability to reduce concrete expansions was not as effective as for Class F fly ash. Where reducing the ASR potential is a major issue, other alternatives such as either a lower cement content or a cement with a low alkali content could be considered.The addition of nano CaCOa et al. . Likewisp < 0.05) was observed in the performance of concretes with 1% nano CaCO3 as compared to concretes with fly ash. The compressive strength, at all ages, and the scaling resistance of both OP-1 and PL-1 were significantly higher compared to those of concretes with fly ash. The permeability of OP-1 was significantly reduced, while PL-1 had higher permeability when compared to concrete with fly ash (class C), but the difference was not significant. Likewise, the ASR expansion of both OP-1 and PL-1 was higher when compared to that of concrete with fly ash (class F), but the difference was not significant. Thus, the statistical analysis confirmed that nano CaCO3 outperformed fly ash in most of the tests, with few tests where fly ash showed relatively better results, which, however, were not significant. Further, confirming the previous study by the authors [3 exhibited a significantly higher performance in all tests (except the ASR) when compared to traditional concretes without nano CaCO3. authors , concretSEM images of cement pastes were analyzed for further research. In For fly ash cement paste at 3 days a,c, the 3  at all ages compared to fly ash concretes.The concrete with nano CaCO3 reduced the permeability of both OPC and PLC concretes. The permeability of OP-1 was lower than that of concretes with fly ash, while PL-1 had a permeability comparable to that of concretes with fly ash.The use of nano CaCO3 improved the scaling resistance of both OPC and PLC concretes, with the highest resistance for PLC concrete, thus mitigating the major limitation of concretes with fly ash for use in freeze–thaw environments.The use of nano CaCO3 reduced the expansion of both OPC and PLC concretes by approximately 50% and 20%, respectively. The expansion of OPC and PLC concretes was lower than that of concrete with Class C fly ash but was not as effective as for Class F fly ash.The addition of nano CaCO3 and fly ash in concretes.SEM images showed that the microstructure of concrete improved with the addition of both nano CaCOFly ash has been widely used in the concrete industry to enhance concrete performance, while lowering concrete cost and mitigating adverse environmental impacts. The supply and quality of fly ash, however, have already been a concern in several regions of the world, and thus fly ash may not be a viable option for the years ahead. This paper evaluated if nano CaCO3) showed comparable performance, which in most cases, exceeded the performance of fly ash concretes. In addition to a higher performance, the use of nano CaCO3 can also be economical and more sustainable, as this concrete has the potential to be produced within the cement plant with the utilization of waste CO2. Thus, nano CaCO3 has the potential to serve as a reliable, economical, and environment-friendly alternative to fly ash. Further, moving towards a more environment-friendly alternative, more studies on the durability of PLC with nano CaCO3 should be initiated. As PLC with nano CaCO3 showed comparable or better results than OPC, there might be the possibility to produce PLC with higher percentage of limestone powder, thus reducing the cement clinkers.The testing results showed that both OP-1 and PL-1 (OPC and PLC concretes with 1% nano CaCO


The Microbiologically Induced Corrosion (MIC) of concrete sewer pipes is a commonly known problem that can lead to the destruction of the system, creating multiple public health issues and the need for costly repair investments. The present study focuses on the development of a magnesium hydroxide coating, with optimized properties to protect concrete against MIC. The anti-corrosion properties of the respective coating were evaluated by using short and long duration accelerated sulfuric acid spraying tests. The coating presented satisfying adhesion ability, based on pull-off and Scanning Electron Microscopy (SEM) analysis measurements. The surface pH of the coated concrete was maintained at the alkaline region  throughout the duration of all acid spraying tests. The consumption of the coating, due to the reaction  with sulfuric acid, was confirmed by the respective mass and thickness measurements. The protection ability of this coating was also evaluated by recording the formation of gypsum  during the performed tests, by X-ray Diffraction (XRD) analysis and by the Attenuated Total Reflectance (ATR) measurements. Finally, a long duration acid spraying test was additionally used to evaluate the behavior of the coating, simulating better the conditions existing in a real sewer pipe, and the obtained results showed that this coating is capable of offering prolonged protection to the concrete substrate. The good operation and efficient protection of sewerage pipeline systems, especially against MIC, is majorly important for urbanized societies. MIC is a specific type of corrosion mechanism that can take place usually in the larger diameter sewer pipes, constructed mainly from concrete, expected to highly affect the concrete and reduce the lifetime of the structure. This phenomenon has been widely studied during the last 100 years ,3,4,5 anMIC is a complex corrosion mechanism, depending on the multiple chemical and biochemical processes which can take place in the sewer pipeline. Sulfates, along with other substances carried within wastewater, initiate the growth of microbial communities, which in turn cause the reduction of sulfates to hydrogen sulfide. The formed hydrogen sulfide (gas) is released to the liquid phase (wastewater) and finally, it is emitted in the upper (air) part of the  pipe. Then, the gas hydrogen sulfide can be dissolved in the humidity film located on the upper region of the pipe wall  ,8. As a The prevention methods developed so far may include the application of linings and coatings ,15,16, lCertain coatings and linings have been already widely used for the protection of concrete ,16,23 orThis study is mainly focused on a specific magnesium hydroxide (MH) slurry, which after preliminary experiments was found to present the optimal expected properties, e.g., regarding the specific surface area (SSA) and the particle size distribution (PSD) . The mag3 CEM I 42.5 R, 895 kg/m3 crushed limestone sand (0–4 mm), 895 kg/m3 crushed limestone aggregates (4–8 mm), 184.5 kg/m3 tap water and 0.5% wt. of cement poly-carboxylate based super-plasticizer. Wooden molds with different dimensions , depending on each test specific requirements, were used for the preparation of specimens. After 24 h the concrete specimens were de-molded and cured into water for 27 days at 20 ± 2 °C.As far as concrete specimens are concerned, concrete type MC (0.45) was produced, according to the ΕΝ 1766:2017 Standard , conformThe use of concrete specimens, as substrates for the examined protective coating, may obstruct the observation of the coating’s consumption, occurred due to the potential  reaction of sulfuric acid with the cement  paste of concrete. Therefore, in this study, poly (methyl methacrylate) (PMMA) plates were alternatively used as substrates, apart from the concrete substrates, in order to promote a clear observation of the coating reaction with the sulfuric acid. PMMA plates with dimensions of 50 mm × 50 mm × 5 mm were cut and used for the detailed examination of coating behavior under similar  conditions.3, a viscosity of 2500 cP (R5 spindle @100 rpm), and contains 0.4% on solids of a modified methyl cellulose as convenient adhesive material.The magnesium hydroxide slurry was provided by Grecian Magnesite S.A. It was produced in the laboratory by the controlled hydration of micro-crystalline Caustic-Calcined Magnesia (CCM), of medium purity. The MH slurry has a solids content of 57.5%, specific gravity of 1.46 g/cm2 content of the respective powder.The main physicochemical characteristics of magnesium hydroxide solids of the slurry are provided in 2/g) to maintain favorable slurry characteristics, such as viscosity and workability and to allow the inclusion of cellulose. The results of the previous study [This magnesium hydroxide differs mainly in the MgO content, but also in the specific surface area and in the particle size from other examined magnesium hydroxides, previously investigated . The maius study  indicateus study . Additious study , this fa2. After the application of coating onto the substrates, the specimens were dried for 3 days under normal laboratory conditions  before further testing.The thickness of relevant protective coatings, according to the literature and preliminary testing, can range from few micrometers to few millimeters, depending on the coating’s nature ,31,32. IThe examined coating was also evaluated for its adhesion ability onto the concrete, by applying the pull-off bond testing method, according to the standards ΕΝ 1542:1999  and ΕΝ 1The adhesion of coating onto the concrete surfaces was also examined by Scanning Electron Microscopy (SEM) analysis, providing a closer examination of the respective concrete-coating interface and of the coating’s morphology. Moreover, specific information regarding the magnesium content, which might penetrate the concrete structure, can be obtained by using the EDS analysis. The specimens were cut vertically in order to reveal the interface between the concrete and the coating and were polished appropriately, creating a flat surface for clear observation. Micrographs were obtained by using a JSM-7610F Plus, JEOL, scanning electron microscope and the EDS analysis was performed by using the AZtec Energy Advanced X-act System .According to a relevant study  two diffFor the application of the coating onto the concrete substrate, concrete specimens with dimensions of 50 mm × 50 mm × 20 mm were used for the acid spraying tests. Moreover, PMMA plates with the same dimensions were also comparatively used for the respective tests.The surface pH values, the mass change and the existing mineralogical phases were recorded for all performed tests. However, the thickness change of the coating was examined only after the HHD test. The spraying tests and the measurements applied for each case are summarized in In all acid spraying tests a flat surface pH electrode  was used to record the surface pH values of specimens. The initial surface pH values were recorded for each specimen before the beginning of acid spraying tests. The surfaces to be measured were wetted with 1 mL of deionized water prior to the measurement.An electronic balance Kern PCB 350–3 (350 ± 0.001 g) was used to record the mass change of specimens daily, in order to evaluate the consumption of the coating. Firstly, the initial weight of all uncoated concrete specimens was recorded, as well as their weight after the application of the slurry, in order to calculate the mass of dry coatings.A Dino Lite Digital Microscope was used to photograph the cross-section of coated concrete specimens before and after the application of acid spraying, in order to record the thickness change of the coating. After that, the photographs were digitized and processed by using the microscope’s software and finally, the thickness was calculated according to the magnification used in each picture.The mineralogical phases were evaluated by using the X-ray diffraction analysis (XRD), which is described in Sulfuric acid solutions were used in all performed tests, aiming to simulate the biogenic sulfuric acid produced in a sewer pipe internal wall. The sulfuric acid spraying tests were performed to examine the total consumption of magnesium hydroxide coating at the end of respective tests, due to the neutralization reaction between them:In that way, the amount of daily sprayed sulfuric acid (according to the reaction’s stoichiometry) was calculated, based on the amount of applied coating, on the duration of each test and on the used acidic solution concentration.The duration of accelerated acid spraying tests was selected to be 4 days, apart from the long duration test, which lasted 128 days. The used sulfuric acid solutions had concentrations of 4 M, 0.2 M and 0.1 M for the HHD spraying test, the 4-day chamber test and the 4-month chamber test, respectively. In all these experiments the same conditions were applied for the calculation of corresponding necessary sulfuric acid amount to be sprayed, as explained in more detail in the relevant literature .The calculated stoichiometry  was divided by the number of spraying days and the daily spraying application stoichiometry corresponded to 25% of the overall stoichiometry, regarding the respective neutralization reaction between the coating and the sulfuric acid for the 4-day tests . The daily spraying applications were different between these two tests, due to the different initial acid solutions concentrations used. Accordingly, the daily spraying application stoichiometry for the longer duration test (128 days) corresponded to the 0.78% of the overall stoichiometry of the respective reaction.Two tests were used in the case of 4-days accelerated acid spraying tests, i.e., the test where the hand-held device was used and the test where the custom-made poly (methyl methacrylate) chamber was used. The concentration of sulfuric acid solution in the HHD test was 4 M, in order to magnify the consumption of coating, due to the reaction with sulfuric acid, whereas the concentration of the solution in the chamber tests was 0.2 M, in order to approach the milder conditions commonly existing in a sewer pipe.Coated concrete specimens were used in both tests, whereas the coated PMMA plates were only tested in the spraying chamber test. The coating was dried after its application for 3 days under normal laboratory conditions before the sulfuric acid spraying applications. Four coated specimens were removed daily from each acid spraying procedure and studied in detail.The long-term durability of the examined coating was evaluated by a 4-month accelerated acid spraying test that was held in a custom-made poly (methyl methacrylate) spraying chamber. Τhe rinsing liquids were collected separately for each specimen (chamber facility) in order to be further examined. The concentration of sprayed sulfuric acid (0.1 M) was selected in this case to be lower in respect to the 4-day tests (0.2 M), in order to simulate better the conditions existing in a sewer pipe. The longer duration test allowed the spraying of significantly lower amount of sulfuric acid daily (according to the number of daily spraying applications). In that way, the behavior and consumption of coating in time can be examined.At 8-days intervals, four specimens were removed from the chamber and tested, regarding the surface pH values, the mass change and the mineralogical phases existing on the surface. Moreover, the rinsing liquids were selected during the same time periods, in order to determine the magnesium content that was rinsed/removed  during the experiment. The magnesium content was determined by Flame Atomic Absorption Spectrophotometry, using the Perkin-Elmer AAnalyst 400 instrument. The experimental conditions, applied in the chamber, simulated the usual sewer pipe conditions, i.e., maintaining the temperature at 20 ± 2 °C and 99% relative humidity.The recognition and quantitative determination of mineralogical phases existing on the specimens’ surface were performed with the XRD analysis. After the spraying process, the specimens were dried at 40 °C for 24 h, and then the coating and the potentially formed by-products were scratched from the top of specimens, ground and measured. The structural phases  of the obtained samples were analyzed by XRD measurements, using a PW 1840 Phillips diffractometer with CuKa radiation, step size of 0.02° and step time of 0.4 s, operating at 30 kV and 10 mA. The obtained diffractograms were further quantified by following the Rietveld methodology, using the FullProf Suite Software.ATR was additionally used for the characterization of selected surface samples from the longer duration test. For the ATR measurements a Cary 630 FTIR, Agilent Technologies and the respective software MicroLab were used. The samples were measured directly after the XRD measurements without any prior treatment.The results of pull-off measurements can offer important information about the adhesion ability of protective coatings onto an appropriate substrate. In particular, the coating’s tensile bond strength can be calculated by using the failure load, resulting from the respective measurements. Additionally, the type of failure can be determined optically, according to the aforementioned standards ,34 and eAccording to the standards, and regarding the pull-off measurements, several types of coating failures can be optically observed and defined, depending on the applied coatings. However, in this study, two specific types of failure were present, i.e., the adhesion failure between the substrate/concrete and the coating (denoted hereafter as A/B), and the cohesion failure within the layer of coating itself (denoted hereafter as B). The results, regarding these failure types, are usually presented as a combination between the two aforementioned types (and as percentage).The tensile bond strength between the applied coating and the concrete substrate, as well as the type of failure, is presented in As far as the tensile bond is concerned, the coating was found to present medium-to-high values when compared to other relevant coatings, consisting of different magnesium hydroxide powders . The speAs far as the coating’s microstructure is concerned , the parThe EDS analysis of the coating and of the concrete surface can provide information regarding the potential penetration of coating constituents into the concrete structure, which can also explain the coating’s good adhesion and create an additional protection zone in the concrete structure. The EDS analysis of the spectrum areas  is preseThe study of coating surface pH values during its interaction with sulfuric acid is very important, because this is the main acquired and inherent property of magnesium hydroxide coating, against the biogenic corrosion of concrete. The maintenance of alkaline surface pH values can block the development of sulfur oxidizing bacteria, hence the production of biogenic sulfuric acid and the subsequent corrosion of concrete.The daily recordings of surface pH values, regarding the coated concrete specimens, when sprayed during the HHD test, as well as the coated concrete specimens sprayed in the spraying chamber are presented in In all these cases, the starting pH values of the coating, measured on the substrates’ surface, were very similar. The coating presented initial surface pH values around value 10 (day 0). Despite the differences between the tests, the application of acid spraying led to slightly decreased surface pH values , comparing with the initial pH values. However, the pH values remained in the alkaline region throughout the spraying processes, which means that the coating can block effectively the development of bacteria. The differences of pH values between the tests found to be relatively small. More precisely, after four days of spraying, the values measured for the specimens, sprayed under the HHD test, were the highest, i.e., 9.25. This fact may be due to the smaller number of spraying applications in the case of HHD test, even though a highly concentrated sulfuric acid solution was used, as compared with the number of spraying applications in the case of the chamber test.The respective pH values of coated PMMA plates were found to be slightly higher, at days 1, 2, and 3 of chamber spraying test, with respect to the values of coated concrete specimens. The comparison of surface pH values for the coating, during the chamber test, as applied either on concrete substrates (dry coating), or on PMMA plates, indicates that the presence of concrete substrate might also influence the measured pH values.These values can be compared with the corresponding ones of other magnesium hydroxide coatings, as well as of uncoated concrete specimens, which were sprayed accordingly . The exaMoving on, mass measurements were also conducted for the coated concrete specimens subjected to both tests (HHD and chamber), as well as for the coated PMMA plates (chamber test). The results are presented as percentage, in respect to the initial coating mass and are given in According to the stoichiometry calculations, a larger consumption of the coating, at all these cases, can be expected, because the amount of sulfuric acid that was sprayed onto the specimens, during the 4-days tests, corresponded to the coating’s total magnesium hydroxide amount. However, it can be assumed that the sprayed sulfuric acid can only react with the exposed coating surface, instead of the full coating’s mass , somehowThe mass change results indicated that the substrate affects the behavior of the coating concerning mass change. The mass change of the coating on the concrete specimens (chamber test) presented rather stable behavior during the spraying procedure. On the other hand, the mass change of coating on the PMMA specimens was more intensified during the test. In this case the mass decrease reached almost 25%, when compared to the initial mass of the system. It seems possible that the adhesion between the coating and the concrete can play an important role on the system’s behavior. In this respect the porosity of concrete and of concrete surface are important parameters. On the contrary, the absence of adhesion between the used coating and the polymer substrate (PMMA) did not contribute to that direction.The concentration of sprayed sulfuric acid can also play an important role, as during the HHD test (using the higher concentration of 4 M), the mass loss was greater than in the chamber test (using the lower sulfuric acid concentration of 0.1 M). This reasonable result is connected to the greater consumption of coating in the case of greater acid concentration sprayed.It is also a fact that mass increase was not observed, as it was recorded for some other magnesium hydroxide coatings, presenting similar characteristics . This isThe measurement of coating thickness during the HHD acid spraying test was performed as another way to evaluate the coating consumption under the application of extreme acidic conditions (high concentration of sprayed sulfuric acid). The coating thickness was expected to decrease during the spraying procedure, due to its reaction with sulfuric acid. The results presented in The 4-months accelerated acid spraying test was performed to better simulate the existing conditions in a sewer, as described in The variation of pH values during the 128 days experiment were quite similar to those obtained from the 4-day testing, considering the respective acid concentrations. This shows that the short time tests are also reliable and both tests (long- or short-term) can be performed to evaluate the pH behavior of this magnesium-based coating.Moving on, the mass change results of the long duration acid spraying test are presented in According to the results, the mass of specimens increased  during the first 80 days, with the exceptions of specimens at day 32 and day 64. Regarding the results of day 32 specimens, there was an unregular mass decrease, with respect to the trend of the previous and the following specimen results. However, the results are given for different specimens each time, and this can lead to different results in some cases. Regarding the results of day 64, there was a technical problem during the test and mass loss was observed, due to coating detachment. After 88 days of acid spraying, mass decrease was recorded until the end of the procedure.These results, and especially the mass increase, differed from the respective tests of the accelerated acid spraying tests , where nThe long-term acid spraying test was also conducted in a poly (methyl methacrylate) chamber, which was modified in a way that the washouts could be collected and analyzed. After that, the magnesium content was determined in them, and the results are presented in According to the above-mentioned results, the long duration test showed that the examined coating was consumed during the experimental procedure. The by-products can be evaluated by the following XRD results.The respective samples were examined by using XRD and the respective results are presented as XRD diffractograms overlay. 2) are indicated, whereas the peaks of other phases (OH)4) and dolomite 2)) are not easily indicated (presenting low intensity), but they are also included in the semi-quantitative results presented in 4·2H2O) and hexahydrite (MgSO4(H2O)6), are indicated in According to these results, the main peaks of brucite (Mg(OH)It is important to note that the formed magnesium sulfate (hexahydrite) is water soluble and can be easily washed out, due to spraying applications; hence, it cannot always be traced. The differences between the tested specimens, when compared to the raw  material used, indicate the formation of by-products, specifically in the case of HHD test sample. Additionally, the substrate did not seem to interfere with the found crystallographic phases results, as no peaks of concrete phases were detected, such as calcite or quartz.The semi-quantified results of XRD diffractograms  confirm Due to the two different sources of calcium, i.e., from the concrete or from the coating, it is not clear whether gypsum was a corrosion by-product of the substrate (concrete), or of the coating content only. In that way, the tests using PMMA plates were also performed to verify the origin of potential gypsum formation. Regarding the respective results of PMMA plates, gypsum formation was not observed, concluding that the formed gypsum during the HHD tests corresponded to the corrosion of concrete. In comparison, the results of the chamber tests indicate that the coating can provide anti-corrosion protection to the concrete substrate, because gypsum formation was better prevented in this case.The coating was examined under sulfuric acid spraying in a spraying chamber test for 4 months, using 0.1 M sulfuric acid solution. The selected XRD diffractograms at days 0, 32, 64, 96, and 128 are presented in The semi-quantitative XRD results of all eight-day intervals are presented in The gypsum crystalline phase was identified at the sample of day 64, but at low content , although the periodic increase of gypsum was recorded even after the 88th day. The gypsum at day 64 might be formed due to sample weaknesses and structure deformation, creating defects and leading to the detachment of coating.According to these results, the coating can practically offer long-term anti-corrosion protection to the concrete surface. The coating protected the concrete surface for at least the 87.5% of the calculated theoretical time without allowing the formation of significant gypsum by-product. After day 112, the degradation of concrete is recorded, due to gypsum formation, despite the maintained alkaline pH values.−1 [−1 and 879 cm−1, which implies that carbonated species are also present in the samples, although the relevant IR response is rather weak.The ATR measurements record the vibrations of bonds of the compounds and the respective spectra are displayed in −1 . The pea−1 is attributed to sulphates (SO4−2) [−1 and 1618 cm−1 is attributed to the O-H bending vibrations of water molecules [−1 and 596.4 cm−1 are owed to the stretching and bending modes of sulfate group of the gypsum [At the 128th day spectrum gypsum peaks were identified. The strong peak at 1109 cm (SO4−2) . Additioolecules ,37. The According to the previous experimental study , the chaThe particle size of magnesium hydroxide was selected to be relatively small in order to enforce the interacting ability of resulting coating, based on the results of the previous relevant research . AlthougAnother crucial property that was selected according to previous evaluation  was the The slurry was applied on concrete specimens for long- and short-time evaluation of its resistance during acid spraying, as well as on PMMA specimens for the study of coating reaction , but without the interference of concrete substrate.The resulting surface pH of studied coating was maintained in the alkaline region , regardless the duration of testing and the concentration of sprayed acid. Furthermore, the coating maintained the pH to the alkaline region, when tested on both PMMA and concrete substrates and for long period of time (128 days), by applying lower acid concentration, as well as for shorter period of time (4 days), by applying higher acid concentration. The latter indicates the resistance of coating to neutralization for the aforementioned different experimental conditions.The adhesion between the coating and the concrete surface seems to result in a system, where the two materials can “co-operate” well and the coating protects efficiently and effectively the concrete substrate. The respective mass change results pictured a gradual removing of coated material and confirmed that most probably hexahydrite was washed out, as the mass of coatings was decreased in both cases, i.e., for the concrete and PMMA substrates.The long-term testing revealed the behavior of coating under approximately real conditions, existing in sewer pipes. The simulation of lower acid concentration (0.1 M) showed that efficient protection can be achieved. The gypsum formation was prevented, according to the XRD and ATR results. More specifically, gypsum was identified by XRD at the 112th day of spraying and ATR verified its late formation. Therefore, the coating can protect completely the concrete for this time period, under the applied experimental conditions. After 112 days the gypsum formation started, accompanied with extended brucite consumption, which indicates that the coating’s degradation leads to gypsum formation, i.e., strong evidence that the concrete is no longer protected. The magnesium removal from the surface and its leaching in washouts seemed to follow a nonlinear behavior, as it was found quite intensive during the initial experimental procedure  and later , according to the quantification of Mg content.The comparison of different substrates coated with the examined material revealed the gypsum source. The XRD results of PMMA coated plates did not show any gypsum formation. As a result, the gypsum formation does not originate from the calcium content of coating material, but it is attributed to the corrosion of concrete surface, due to the presence (spraying) of sulfuric acid. Additionally, it was proven that the coating’s adhesion onto the concrete’s surface also plays an important role on the consumption of coating.The magnesium hydroxide slurry was found to protect the concrete from MIC by effectively maintaining alkaline surface pH values and reacting with  the sprayed sulfuric acid. The results of the present study indicated that the medium particle size of the raw magnesium hydroxide material used is optimal for the studied experimental conditions, in order to achieve adequate interacting ability with the sprayed sulfuric acid. Improved purity can also enhance the alkaline and anti-corrosion properties of produced coating. Moreover, the SSA property seemed to be rather independent of the anti-corrosion behavior of coating.Corrosion by-product  was only formed after spraying with higher concentration of sulfuric acid, during the hand-held device accelerated acid spraying test . However, during the accelerated tests using lower sulfuric acid concentration , no production of gypsum was observed. The long duration (accelerated) acid spraying test indicated that the respective coating can protect the concrete substrate, by reacting (consuming) with sulfuric acid, under conditions that can simulate the sewer pipe environment.To sum up, the improved properties of magnesium hydroxide raw material can enhance the anti-corrosion behavior of produced coating and preserve effectively the properties of concrete substrate, even during long-term test procedures, and as a result also when used in actual sewer pipes.


On the ward where AS measures were no longer provided, overall antibiotic usage remained stable (71.3 DOT/100PD (P1), 74.4 DOT/100PD (P2)), showing the sustainability of AS measures. However, the application of last-resort compounds increased from 6.4 DOT/100PD to 12.1 DOT/100PD (oxazolidinones) and from 10.8 DOT/100PD to 13.2 DOT/100PD (carbapenems). Conclusions: Antibiotic consumption can be reduced without negatively affecting patient outcomes. However, achieving lasting positive changes in antibiotic prescribing habits remains a challenge.Background: Antibiotic stewardship (AS) ward rounds are a core element in clinical care for surgical patients. Therefore, we aimed to analyze the impact of surgical AS ward rounds on antibiotic prescribing, and the sustainability of the effect after the AS interventions are no longer provided. Methods: On four wards of the department of visceral surgery, we conducted two independent retrospective prescribing analyses  over three months each. During the study periods, the level of AS intervention differed for two of the four wards (ward rounds/no ward rounds). Results: AS ward rounds were associated with a decrease in overall antibiotic consumption (91.1 days of therapy (DOT)/100 patient days (PD) (P1), 70.4 DOT/100PD (P2)), and improved de-escalation rates of antibiotic therapy (W1/2: 25.7% (P1), 40.0% (P2),  Antibiotic resistance is a major global threat, making effective antibiotic treatment increasingly difficult, while the process of developing new antibiotics still has room for improvement . Broad uIn visceral surgery, intra-abdominal infections (IAI) are associated with high morbidity and mortality. Antibiotics, in addition to surgical source control, are indispensable in their treatment . HoweverASPs can effectively reduce inappropriate antibiotic consumption without compromising patient outcomes, but the sustainability of AS interventions has not been studied in detail to date . AS actip = 0.14) received at least one course of systemic antibiotic treatment during their hospital stay. During P1, four patients were excluded from the study, due to incomplete sets of data (two patients) and lengths of stay longer than 100 days (two patients), whereas nine patients were excluded in P2, due to incomplete sets of data (four patients) and lengths of stay of over 100 days (five patients). The statistical analysis included 299 (P1) and 275 (P2) patients (p = 0.028). The Charlson comorbidity index [p = 0.074) patients in P1 and P2, respectively. Rates of multidrug-resistant bacteria isolated  were similar in the two study periods. Results of nasopharyngeal, inguinal, or rectal swabs for screening of colonization were excepted. There were no differences in median length of stay, readmission for infection after 30 days, or in-hospital mortality between the two study cohorts , a total of 649 (P1) and 666 (P2) patients were admitted to the four surgical wards. Of those, 46.7%  and 42.6%  and ward 2 (W2), where AS ward rounds were conducted in both phases, and on ward 3 (W3), where AS ward rounds took place only in P2 (W1/2/3 combined: 91.1 days of therapy (DOT)/100 patient days (PD) vs. 70.4 DOT/100PD). On ward 4 (W4), the AS ward rounds were no longer provided during P2. The overall antibiotic consumption remained unchanged on this ward. On all four wards, reduced usage of cefuroxime, ciprofloxacin, and metronidazole prescriptions was seen during study period P2  in phase 1, and 312 COAs in phase 2. Initial doses were given intravenously in 88.9% (P1) and 90.7% (P2), respectively. No effect of the AS ward rounds on the intravenous-to-oral  switch rate nor on the duration until iv-to-oral-switch could be detected.p = 0.030). On W3, a trend of increased de-escalation rate during a COA was observed in P2 (p = 0.081). On W4, there was a tendency towards a decrease of iv-to-oral switch and de-escalation rates; however, it was not statistically significant. Duration to de-escalation did not change significantly on the four wards , did not change over time. In addition, there was no change of personnel in crucial positions. The decrease in overall antibiotic consumption on W1 might be explained by reductions in inappropriate COAs, as there was no reduction in length of antibiotic therapy in P2. In particular, reduced use of the last-resort compounds linezolid and meropenem on W2 and W3 is noteworthy, as it was not compensated by the use of other broad-spectrum antibiotics, such as piperacillin/tazobactam.Previous studies observed a positive impact of AS in surgical patients with IAI ,15,16. TThe positive effects of performed AS ward rounds regarding antibiotic consumption in general were sustained, but not for last-resort compounds like carbapenems or oxazolidinones. On W4, where AS ward rounds were stopped after P1, the overall antibiotic consumption remained on a stable level, but the use of meropenem and linezolid distinctly increased in P2. Barbieri et al. investigated the sustainability of clinical pathways for decreasing use of broad-spectrum antibiotics in pediatric patients suffering from acute otitis media or pharyngitis . A lack Charani et al. investigated antibiotic decision making in surgery and pointed out the importance, but also the difficulties, of ward rounds for patient care in surgery ,26. Our In addition to the AS ward rounds, the strong decrease of ciprofloxacin consumption on all four wards might have been influenced by the publication of an official drug-safety warning regarding the restricted application of fluoroquinolones after P1 (10/2018). This topic has been widely discussed in the media and has been a focus of the public’s attention. Due to the low bioavailability of cefuroxime, it was excluded from the institution’s formulary. This could have additionally reduced cefuroxime consumption, as well as causing a reduction in prolonged perioperative antibiotic prophylaxis with cefuroxime. The department’s internal guidelines for perioperative antibiotic prophylaxis were reviewed and reissued between the two study periods, and explicitly suggested single-shot application, but no prolonged postoperative therapy regime. Consequently, the consumption of metronidazole, co-administered with cefuroxime and ciprofloxacin, decreased on the wards to the same extent as cefuroxime and ciprofloxacin.Fewer female patients were included in P1 than in P2, which does not completely exclude possible changes in antibiotic prescribing due to gender differences. Aghdassi et al. described an increased risk for surgical site infections (SSI) in men for colon surgery, no differences for endoscopic cholecystectomy/appendectomy, and an increased risk in women for hernia repair . Other sThere are some limitations to our study. The patient collectives might not be comparable to those of smaller hospitals, in terms of the extent of the surgical procedures. In addition, there was no control group. However, the “cross-over” design between W3 and W4 generated an internal control to demonstrate the effects of the AS ward rounds. We were able to show a sustained effect of AS interventions, in terms of overall antibiotic consumption for three months after their completion. How long the effect of interventions persists warrants further research.Since local treatment guidelines for IAI were not available during the study periods, a combination of AS ward rounds and internal guidelines on antibiotic therapy in IAI could further improve prescribing in the future. In particular, it could help junior faculty to make their decisions based on these local treatment guidelines when AS consultation is not available. Furthermore, AS ward rounds with senior faculty members present could promote rapid and safe decisions on antibiotic therapy.This monocentric, retrospective observational study was conducted at the visceral surgery department of the university hospital, LMU Munich. Two independent prescribing analyses of three months each (18 May–18 July (P1); 19 September–19 November (P2)) were carried out on three general and one intermediate-care (IMC) wards of the department.To investigate the impact  and short-term sustainability (ward 4) of AS interventions, the two periods were chosen according to the provision of AS ward rounds. On ward 1 , ward 2 (W2), and ward 4 (W4), AS interventions were introduced before P1. On W1 and W2, they were continued in P2, whereas the AS intervention was stopped after P1 on W4, and started only after P1 on ward 3 (W3) . All patA multidisciplinary ASP was introduced at the university hospital, LMU Munich in 2017. The AS team was composed of an infectious disease (ID) physician, an ID pharmacist, and a clinical microbiologist. Weekly ward rounds based on an audit and feedback strategy, in collaboration with the current surgeon on duty, started on W2 with the observation period (P1), and on W1 and W4 a few months earlier .All demographic and clinical data, choice of antibiotic agent, days of antibiotic therapy, and microbiological results were extracted manually from electronic patient records and irreversibly anonymized during data collection.Diagnoses requiring hospitalization and the resulting surgeries were recorded and allocated to the organ concerned .In the study, antibiotic consumption was measured in days of therapy per 100 patient days. Length of antibiotic therapy (LOT) was defined as in-hospital days of antibiotic therapy. Continuous days of antibiotic treatment were defined as one course of antibiotics (COA). After discontinuation of antibiotic treatment for more than one day, a new COA was determined, and several COAs could, therefore, be assigned to one patient.To evaluate changes in antibiotic therapy, antibiotic agents were ranked according to their spectrum of activity against drug-resistant bacteria ,31 Tabl. ChangesTo assess the impact of weekly AS ward rounds, overall antibiotic consumption, as well as antibiotic consumption of single substance classes and change in antibiotic therapy, were analyzed in this study. In-hospital mortality and readmission caused by an infection after 30 days were compared to ensure patient outcome was not negatively affected by the AS intervention. Short-term sustainability was defined as maintained positive effects of AS ward rounds on antibiotic prescribing in the following three months after stopping them.A sample size calculation was performed for the outcome of changes in length of antibiotic therapy (LOT). With a targeted power of 0.8 and a low expected effect, it was calculated that 325 patients were required in each study arm. By including 299 patients within three months for P1, we were close to the intended study sample size. For P2, including 279 patients resulted in the according study period of 3 months.p < 0.05. The statistical analysis was performed with IBM SPSS Statistics 26.All categorical variables are shown as numbers with frequencies. Continuous variables are presented according to the distribution as a mean with a standard deviation or a median with a range. Variation between the two study periods for categorial variables was tested using the χ2-test or Fisher´s exact test, and for continuous variables, the t-test or Mann-Whitney U test was used. Statistical significance was set at Regular AS ward rounds most likely improved antibiotic use in the setting of visceral surgery by reducing antibiotic consumption and increasing de-escalation rates of antibiotic courses. However, AS ward rounds need to be performed continuously, as sustained effects were only observed regarding the overall antibiotic use.


IgG4-related disease is a newly recognized fibroinflammatory disease presenting with multiple features including mass forming lesion; a dense lymphoplasmacytic infiltrate; a characteristic histopathological appearance and often elevated serum of IgG4. This disease can potentially affect any organ and interestingly, the affected organs share common histopathological features including a dense lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells, storiform fibrosis, and mild to moderate eosinophiliaA 45-year-old man presented complaining of proptosis and gradual decrease in visual acuity of right eye. He had undergone many work-ups but without any definitive diagnosis. Through a combination of clinical and para-clinical investigations, the diagnosis of IgG4-RD was established. 693 mg/dL). Aggressive treatment (pulse of cyclophosphamide and pulse of corticosteroid) was started hoping to save the patient’s vision. Two weeks following the treatment, there was improvement with his visual acuity and proptosis.In any patient with chronic tumor like lesions and pseudotumors without the evidence of malignancy, we should think of IgG4-related disease. In this circumstance, biopsy may lead us to the definitive diagnosis. Early diagnosis and treatment of IgG4-RD may inhibit further irreversible organ damages. IgG4-related disease (IgG4-RD) is relatively a new fibroinflammatory disease that can involve a variety of organs and tissues such as the hepatobiliary ducts, salivary glands, periorbital tissues, and lacrimal glands . This diA 45-year-old man referred to our Rheumatology clinic for further evaluation of proptosis, which started about 8 years ago. He had a gradual bilateral decrease of vision that worsened during the last 18 months. Physical examination revealed a proptosis of 33 mm and 26 mm in the right and left eyes, respectively . There was a mild conjunctivitis in both eyes and the visual acuity  of the right eye was recorded as hand motion recognition at 50 cm and that of the left eye was normal (9/10). He had a mild cataract in both eyes. On further eye examination, the anterior segments of both eyes and the posterior segment of left eye were normal, but the posterior segment of right eye had grade 2+ disc paleness. Marcus gun examination was positive. Fundoscopy of the right eye showed blurred disc margin and mild engorgement of veins around the disc. The rest of physical examinations were unremarkable. There were no skin or mucosal involvement, sinusitis, otitis, neurological or respiratory manifestations. Laboratory investigations yielded the following results: erythrocyte sedimentation rate (ESR) was 11 mm/h, white blood cells (WBC): 13000 /ul, hemoglobin: 13.7 gr/dl, platelet count: 404000 /ul, urea: 31 mg/dl, serum creatinine (Cr): 1 mg/dl, aspartate aminotransferase (AST): 10 U/L, alanine transaminase (ALT):12 U/L, alkaline phosphatase (ALP): 187 U/L, INR:1 and total bilirubin: 0.2mg/dl. Urinalysis was normal without any cellular cast, dysmorphic RBCs or proteinuria. Echocardiography indicated normal left ventricle size with ejection fraction (EF) of 55%, normal left ventricular systolic function, moderate aortic regurgitation, and a bicuspid aortic valve. In computed tomography of paranasal sinuses and orbits, there was an evidence of bilateral retro-orbital enhancing masses notably in the right orbit with intraconal and extraconal extension encasement of optic nerve, and extension into the orbital apex and superior and inferior orbital fissures . There wThe patient underwent four different ocular biopsies. In June 2014, the patient had microscopic anaplastic lymphoma kinase (ALK) positive inflammatory myofibroblastic tumor, and underwent 17 sessions of radiotherapy, but the clinical symptoms did not resolve. The last pathology study revealed chronic inflammatory pseudotumor with marked fibrosis and IgG4 positive plasma cells about 50/ high power field. The results of immunohistochemistry staining (IHC) study was as follows: IgG4 positive lymphoid cells 50/ high power field, CD138 positive plasma cells, CD3 positive T cells (80%), CD20 positive B cells (20%), smooth muscle antibody (SMA) positive spindle cells, negative ALK and his serum IgG4 level was 693 mg/dl. As this disease can affect any organ and due to a complaint of mild abdominal pain by the patient, an abdominal CT scan was performed. The computed tomography scan results revealed multiple bilateral hepatic mass lesions with the largest size being (41*32 mm) at segment 7, and 28*2 (3)7 mm at segment 3 . The masWhen the patient referred to us, the diagnosis of IgG4-related disease was established based on the clinical and histopathological findings including the result of IHC revealed the presence of IgG4 positive plasma cells, the ratio of IgG4>40% and serum IgG4 level>130 mg/dL (693 mg/dL). Aggressive treatment (pulse of cyclophosphamide and pulse of corticosteroid) started with methylprednisolone 1gram/ day for 3 consecutive days. We observed a significant reduction of symptoms as the proptosis decreased to 26mm and 17.5 mm in the right and the left eyes, respectively . The visual acuity of right eye improved from hand motion to finger count at 1 meter. After 4 pulses of 1-gram cyclophosphamide/ month, his visual acuity improved to 3/10. The patient required a prolonged treatment with glucocorticoid, however, even though it was expensive, azathioprine was prescribed as a glucocorticoid-sparing therapy. The author previously reported a similar case of IgG4-RD with ocular manifestation of proptosis and decrease in visual acuity that showed a dramatic response to early aggressive treatment with corticosteroid and cyclophosphamide (Involvement of head and neck is one of the most common presentations of IgG4-RD (5). Patients presented with dacro-cystitis and other head and neck disorders involving the extraocular muscles, sclera, cavernous sinuses, choroid and orbital soft tissue of the orbit . DiffereThere are also some diseases that exhibit positive and elevated IgG4 cells in biopsy, for example inflammatory conditions such as primary sclerosing cholangitis (PSC), rheumatic arthritis (RA), inflammatory bowel disease (IBD), anti-neutrophil cytoplasmic antibody (ANCA)- associated vasculitis etc., but none of them shows the clinical and compatible histopathological features of IgG4-RD.Lymphomas especially low- grade B-cell lymphoma must be ruled out when IgG4-RD is thought to be the diagnosis. IgG4 positive plasma cells can be seen in cancerous tissues as well, especially pancreatobilliary cancers, however, lack of other typical histopathological aspects of IgG4-RD, like storiform fibrosis or obliterative phlebitis make the diagnosis simple . IdiopatVarious rheumatologic diseases can affect the orbital cavity including Wegener’s granulomatosis, giant cell arthritis, systemic lupus erythematosus (SLE), dermatomyositis and rheumatoid arthritis (RA) . Other cThe diagnosis of IgG4-RD was established based on the following findings; the presence of IgG4 positive plasma cells, the ratio of IgG4-RD >40%, and serum IgG4 level > 130 mg/dl. Early aggressive treatment with pulse cyclophosphamide and pulse corticosteroids) was started hoping to save the vision of the patient. Two weeks following the aggressive treatment, there was an improvement in the visual acuity of the patient to finger count at 1 meter, and after 4 pulses of cyclophosphamide, the visual acuity improved to 3/10. In this case, due to the dramatic response to pulse cyclophosphamide, we recommend cyclophosphamide pulse therapy to be used in the management of life threatening, organ involvement of the disease.During hospitalization, due to the fact that IgG4-RD is a lymphoproliferative, multi-organ disease, we evaluated the patient for other organ involvement. In the abdominal CT scan, several hepatic masses were noticed, and biopsies were taken from most of the mass. Pathological evaluation of the biopsy specimens revealed hemangioma. MRI hepatic protocol was also performed for some of the masses in which the pathologic evaluation was not clear, and hemangiomas were reported too. In articles that were reviewed, the importance of the pathologic evidence of liver mass was emphasized, however there was no relationship reported between the incidence of hepatic hemangioma and IgG4-RD.IgG4-related hepatobiliary disease (IgG4-HDs) is a part of fibroinflammatory multi-organ involvement of IgG4-RD, including IgG4-hapatopathy and IgG4-related sclerosing cholangitis. They can present as bile duct stenosis, to distinguish them from PSC and other hepatic malignancies . IgG4- HAll procedures performed in the study involving human participant were in accordance with the ethical standards of the institutional research committee and with the ethical standards.Informed consent was obtained from the patient in the study. Written permission from the patient was taken for publication of this work with his photo.None of the authors have any conflict of interest.


Antibiotic resistance is increasing worldwide, largely driven by excessive antibiotic use. Antibiotic stewardship (AS) interventions have traditionally focused on acute care, long-term care, and ambulatory settings. However, as patients transition from one care setting to another, AS interventions should address antibiotic orders  between the hospital and the home. The purpose of this study is to determine the appropriateness of a total course of antibiotics, including inpatient and outpatient prescriptions, to aid in prioritizing AS interventions.A single-center, retrospective study was performed to evaluate antibiotic duration for adult patients discharged from a large quaternary-care academic hospital. All antibiotic prescribing data, including pre-admission, during admission, and after hospital discharge, as well as information on indication, was collected from the electronic medical record. Descriptive statistics were used to summarize the data collected.196 patients were included in the study. There were 100 instances of disagreement on antibiotic indication between the discharge summary and reviewer. However, 70% of patients were discharged on an appropriate antibiotic. The majority of patients (75%) were prescribed excess antibiotic days beyond guideline recommended total duration, and 68% of patients did not have appropriate duration of antibiotics post-discharge. Of those with excess duration, 31% were prescribed penicillins, 23% were prescribed cephalosporins, and 20% were prescribed trimethoprim/sulfamethoxazole. Excess antibiotic duration was associated most commonly with an unknown diagnosis (23%), a skin and soft tissue infection diagnosis (16%), and antibiotic prophylaxis (12%).The results of this study showed that patients were often prescribed excess antibiotics at discharge, and the total duration of antibiotics from pre-admission to post-discharge were prolonged beyond guideline-recommended duration. Understanding the total duration of antibiotic prescription, including post-discharge and pre-admission durations, is key in assessing risk from antibiotics and targeting AS interventions. Kate Dzintars, PharmD, Nothing to disclose


VBF), PVA fiber volume ratio (VPF) and rubber volume ratio (VR) on the compressive strength, splitting tensile strength and flexural strength of HFRC were analyzed. The results show that the strength of HFRC is the best when the volume ratio of basalt fiber is 0.3%, the volume ratio of PVA fiber is 0.2% and the volume ratio of rubber is 5%. Basalt fiber has the greatest influence on the strength of HFRC. The strength of HFRC mixed with hybrid fiber is greatly improved, which reflects the good fiber “positive hybrid effect”. With the increase of rubber volume ratio, the strength of HFRC decreases gradually. With the help of SEM and EDS, the toughening and cracking resistance mechanism of the fiber to HFRC was analyzed. Finally, the strength of HFRC was predicted by model.Orthogonal experiments were designed for hybrid fiber rubber concrete (HFRC). The mechanical properties of HFRC were tested and compared with ordinary concrete. The effects of basalt fiber volume ratio ( Concrete has the characteristics of high compressive strength and a wide range of strength grades. It has become the most widely used artificial building material in the world. At the same time, with the rapid development of global infrastructure, the application of concrete materials has become more and more extensive, which promotes the development of concrete in the directions of high strength, sustainable development, intelligence, etc. However, with the increasing requirements of construction engineering on all aspects of concrete, and the defects of ordinary concrete such as easy cracking, low tensile strength, poor toughness and heavy self-weight, it not only limits the exertion of the advantages of concrete to a great extent, but also reduces the service life of concrete structure. For a long time, from the perspective of improving the performance of concrete, many researchers have carried out a lot of research on improving the easy cracking, low tensile strength and poor toughness of concrete. Among them, mixing different admixtures into concrete has become one of the most effective ways ,2,3,4.With the rapid development of economic society, the global automobile production has increased rapidly, and automobile update frequency is also increasingly accelerated, leading to a sharp increase in the amount of discarded tires every year. Because discarded tires (solid polymers) are not easily degraded, they have caused a lot of “black pollution” to the environment. Therefore, the recycling and reuse of waste tires has become an urgent problem to be solved ,6,7. CruStudies have shown that fiber in concrete can better enhance the strength of concrete and make up for its brittle failure defects ,17. BasaIn this paper, a new type of hybrid fiber rubber concrete (HFRC) was prepared by mixing basalt-PVA hybrid fiber into rubber concrete to study the effects of the basalt-PVA hybrid fiber on the compressive strength, splitting tensile strength, flexural strength and impact resistance of HFRC, in order to provide reference and theoretical support for large-scale application of HFRC.3. The coarse aggregate used in the test is 5–25 mm continuously graded granite gravel, with a bulk density of 1460 kg/m3, an apparent density of 2660 kg/m3, a crushing index of 10.5% and a mud content of 0.5%. The fine aggregate used in the test is natural river sand with an apparent density of 2525 kg/m3 and a fineness modulus of 2.75. The water-reducing agent adopts HPWR liquid type high-performance water-reducing agent, and the water-reduction rate is 37%. The water is ordinary tap water.The cementitious material used in the test is Chinese standard Portland cement, and the 28d compressive strength is 42.5 MPa. The physical and mechanical properties of basalt fiber and PVA fiber are shown in BFV (factor A), PVA fiber volume rate-PFV (factor B) and rubber volume rate-RV (factor C) on the compressive strength, splitting tensile strength and flexural strength of HFRC, the L9 (33) orthogonal experiment scheme was selected, with each factor taking three levels. The factors and levels are shown in Specification for mix proportion design of ordinary concrete’, the concrete mix proportion design is shown in Japanese statistician Genichi Taguchi proposed an orthogonal table based on an orthogonal optimization scheme. When there are many test groups in the whole experiment, selecting representative points from the whole test according to the orthogonality can effectively reduce the number of tests, and the orthogonal experiment is dispersibility and neat comparability. The range and variance was applied to analyze the experimental data; by analyzing the degree of influence of variables on the research object, the best conditions or the best combination can be used to achieve the experimental goals ,25,26. IBecause the fibers agglomerate easily in the process of specimen making, the main function of sodium carboxymethyl cellulose is to fully disperse the fiber in the concrete and make the fibers into a monofilament state. At the same time, this will not cause any impact on concrete. Therefore, 0.7% of the total mass of the cement is mixed with sodium carboxymethyl cellulose to improve the reinforcing effect of the fiber on the concrete in the sample preparation . The tesStandard for test methods for concrete physical and mechanical properties, the compressive strength, splitting tensile strength and flexural strength are tested with a WAW-2000D electro-hydraulic servo universal testing machine. The calculation formula of the compressive strength value is shown in Equation (1), the splitting tensile strength value is shown in Equation (2), and the flexural strength is shown in Equation (3). The loading device diagram of the flexural strength test specimen is shown in According to the relevant provisions of the National Standard of the People’s Republic of China GB/T 50081-2019 ccf is the cubic compressive strength of the test piece (MPa); F is the failure load of the test piece (N); A is the pressure-bearing area of the test piece (mm2).In Equation (1): tsf is the splitting tensile strength of the test piece (MPa); F is the failure load of the test piece (N); A is the pressure-bearing area of the test piece (mm2).In Equation (2): ff is the flexural strength of the test piece (MPa); F is the failure load of the test piece (N); l is the span between supports (mm); b is the section width of the test piece (mm); h is the section height of the test piece (mm).In Equation (3): Standard for test methods for concrete physical and mechanical properties, the compressive strength, splitting tensile strength and flexural strength are converted into standard specimen results by multiplying the size conversion coefficient. The size conversion coefficient of the cube compressive strength is 0.95, and the size conversion coefficient of the splitting tensile strength and flexural strength is 0.85.Since the size of the test piece used to determine the compressive strength and splitting tensile strength is non-standard size specimens of 100 mm × 100 mm × 100 mm and the flexural strength test piece is non-standard size specimens of 100 mm × 100 mm × 400 mm. According to the relevant provisions of the National Standard of the People’s Republic of China GB/T 50081-2019 VBF and VPF on the compressive strength, splitting tensile strength and flexural strength of rubber concrete and find out the significant factors, the range and variance of the test results of compressive strength, splitting tensile strength and flexural strength of HFRC are calculated. The calculation method is shown in Equation (4):In order to study the effects of Range calculation method:imK is the sum of the test results corresponding to the level of factor m in column i, imK, and iR is the range of factors in column i. The primary and secondary relationships of the factors are judged according to iR.In Equation (4): The variance is calculated as follows:Sum of squares of total deviations:Degree of freedom:n is the number of rows (test times) of the orthogonal experiment table, and n test indexes.In Equations (5) and (6): Sum of square of deviations of factor A:Degree of freedom:Mean square of factor A:A is the level number of factor A, in is the number of tests at level i, SSB, SSC, Bf, Cf, MSB and MSC can be obtained.In Equations (7)–(9): Sum of the squares of deviation of error:Mean square of error:Significant level of factor A:BF and CF can be obtained.Similar to the significance level of factor A, VBF is 0.3%, VPF is 0.2%, and VR is 5%, the compressive strength, splitting tensile strength and flexural strength of HFRC reached the peak value of 47.9 MPa, 6.63 MPa and 8.98 MPa, respectively. Compared with ordinary concrete, the three kinds of strength increase of H-8 group are 40.06%, 42.58% and 37.3%, respectively. This shows that VBF,VPF and VR have the greatest impact on the splitting tensile strength of HFRC.The test results of the compressive strength, splitting tensile strength and flexural strength of each group of specimens are shown in VBF,VPF and VR on the compressive strength of HFRC is shown in VBF,VPF and VR on the splitting tensile strength of HFRC is shown in VBF,VPF and VR on the flexural strength of HFRC is shown in The range of the compressive strength, splitting tensile strength and flexural strength of HFRC in VBF,VPF and VR on the compressive strength, splitting tensile strength and flexural strength of HFRC are all VBF > VR > VPF.It can be seen from VBF. When VBF increased from 0.1% to 0.3%, the compressive strength, splitting tensile strength and flexural strength of HFRC increased by 25.66%, 24.05% and 16.53%, respectively. With the increase of VPF, the compressive strength, splitting tensile strength and flexural strength of HFRC increased first and then decreased; when VPF increased from 0.1% to 0.2%, the compressive strength, splitting tensile strength and flexural strength of HFRC increased by 2.88%, 0.52% and 0.37%, respectively; when VPF increased from 0.1% to 0.3%, the three strengths of HFRC decreased by 0.41%, 4.95% and 3.6%, respectively. With the increase of VR, the compressive strength of HFRC gradually decreased, the splitting tensile strength and flexural strength showed a trend of first increasing and then decreasing; when VR increased from 5% to 10%, the splitting tensile strength and flexural strength of HFRC increased by 1.03% and 0.61%, respectively; when VR increased from 5% to 15%, the compressive strength, splitting tensile strength and flexural strength of HFRC decreased by 5.98%, 6.48% and 4.69%, respectively.It can be seen from The variances of compressive strength, splitting tensile strength and flexural strength of HFRC in VBF is an extremely significant factor affecting the three strengths of HFRC; VPF has a certain impact on the compressive strength of HFRC and VPF represents non-significant factors affecting the splitting tensile strength and flexural strength of HFRC; VR is a significant factor affecting the compressive strength of HFRC, and the impact on the splitting tensile strength and flexural strength of HFRC is relatively close. All showed a certain impact, but the impact on the flexural strength is greater than the splitting tensile strength.Based on the variance analysis of the compressive strength, splitting tensile strength and flexural strength of HFRC in The above is the range and variance analysis of the compressive strength, splitting tensile strength and flexural strength of HFRC, but it is not a comprehensive evaluation of the mechanical properties of HFRC. The compressive strength, splitting tensile strength and flexural strength of HFRC in The efficacy coefficient values of each index of 9 groups of HFRC were calculated according to the satisfactory and unsatisfactory values of each index, and the calculation formula is shown in Formula (13).d1 represents the efficiency coefficient value of each group of the compressive strength of HFRC, d2 represents the efficiency coefficient value of each group of the splitting tensile strength of HFRC, and d3 represents the efficiency coefficient value of each group of the flexural strength of HFRC.In Formula (13): Total efficacy coefficient value of each group of HFRC:3B2C1, that is, VBF is 0.3%, VPF is 0.2% and VR is 5%.The stress of the concrete in the initial stage of bearing the external load is mainly borne by the HFRC matrix. At this time, the stress is small, but with the continuous increase of load, tiny cracks begin to appear in the concrete and slowly develop into cracks that penetrate the whole specimen. At this time, basaltic fiber with high elastic modulus bears the main load through mechanical bite force and bonding force with concrete matrix and plays the reinforcement role of basalt fiber. With the continuous increase of load, when small cracks develop into larger cracks, the adhesive force formed by the bridging action between the basalt fiber and the concrete matrix will become much smaller. At this time, the PVA fiber begins to interact with the basalt fiber after compression deformation, which enhances the strength of the concrete matrix synergistically, and reflects the “positive hybrid effect” of the fiber. However, due to the low elastic modulus of PVA fiber, the reinforcement effect on concrete is limited, so the reinforcement effect of PVA fiber is much smaller than that of basalt fiber. Mixing rubber into concrete can improve the workability of HFRC. From the previous range analysis and variance analysis of the three strengths of HFRC, it can be seen that: (1) Rubber is not a significant factor affecting the strength of HFRC. (2) Mixing a certain amount of rubber into concrete can improve the strength of concrete to a certain extent, but the effect is not obvious and the strength of concrete even shows a negative increase after exceeding the amount.As can be seen from In order to intensively study the mechanism of action of basalt-PVA fiber reinforced HPBC, group C and group H-8 were selected for EDS test and quantitative analysis. According to the theory of material mechanics, it is assumed that the strength of HFRC is composed of concrete matrix strength, basalt fiber reinforcement, PVA fiber reinforcement and rubber reinforcement. The strength regression model is assumed to be:f is the compressive strength, splitting tensile strength or flexural strength of concrete (MPa); β0 is the compressive strength, splitting tensile strength or flexural strength of concrete matrix (MPa); β1, β2, β3 is the regression coefficient; α is the test parameter; x1 = VBF (%); x2 = VPF (%); x3 = VR (%).In Equation (15): β.The data in ccf is the compressive strength of HFRC (MPa); tsf is the splitting tensile strength of HFRC (MPa); ff is the flexural strength of HFRC (MPa); 2R is the determining coefficient.In Equations (16)–(18): The compressive strength, splitting tensile strength and flexural strength of HFRC are greater than those of ordinary concrete; the compressive strength is between 34.5–47.9 MP, the splitting tensile strength is between 4.72–6.63 MPa, and the flexural strength is between 7.05–8.98 MPa, indicating that basalt fiber and PVA fiber improve the strength of rubber concrete.VBF > VR > VPF. When VBF increased from 0.1% to 0.3%, the compressive strength, splitting tensile strength and flexural strength of HFRC increased by 25.85%, 23.59% and 16.31%, respectively.The influence degree of the three factors on the compressive strength, splitting tensile strength and flexural strength of HFRC is VBF is an extremely significant factor affecting the strength of HFRC; VPF has a certain impact on the compressive strength of HFRC and is an non-significant factor of the splitting tensile strength and flexural strength of HFRC; VR is a significant factor affecting the compressive strength of HFRC and it also has a certain impact on the splitting tensile strength and flexural strength of HFRC, but the impact on the flexural strength is greater than that on the splitting tensile strength.The hybrid of basalt fiber and PVA fiber showed a good synergy effect of fiber to enhance the strength of HFRC and reflected a good “positive hybrid effect” of fiber. In the studied HFRC in this paper, when the volume ratio of rubber is 5%, the increase in its strength has a certain effect, but when the volume ratio of rubber exceeds 5%, the strength of HFRC will show a negative growth effect.3B2C1, that is, VBF is 0.3%, VPF is 0.2%, and VR is 5%. The bridging and reinforcement effect of fiber in HFRC was analyzed with the help of SEM microscopic and quantitative analysis of EDS. Finally, the strength of HFRC was predicted.The best mix proportion combination is A