Cement is one of the main constituents of concrete material and it is one of the main sources of carbon dioxide emissions in the environment. Fillers within a range of 5–7% from different sources can be used as a replacement of cement without compromising the properties of concrete or even tailoring for required property. This paper investigates the influence of inactive silica filler and silica fume on the mechanical- and durability-related properties of concrete with different strengths. The investigated mechanical properties focused on compressive strength at different ages up to 400 days, while the durability-related properties focused on porosity and rapid chloride ion penetrability (RCPT). Two types of ultrafines, namely quartz ultrafine and silica fume, were used. Concrete mixtures with four different water/binder ratios  were prepared for various dosages of quartz ultrafine  and different dosages of silica fume . The results revealed that the compressive strength and durability related properties of concrete with different dosages of ultrafines and silica fume were significantly affected; however, there was a negative impact of ultrafine filler on the compressive strength after replacement of more than 8% of ultrafines. The strength relationships for the concrete with different water-to-cement ratio were assessed and certain modifications were proposed for ultrafines and silica fume. Predictive models were proposed for predicting the compressive strength of concrete in terms of RCPT and porosity for different levels of replacements of ultrafines and silica fume. Concrete with higher mechanical and durability properties are prepared through dense structure of matrix. The densification of matrix is achieved by addition of ultrafine minerals and chemical actions. Physical densifying through properly grading material in the matrix will also prepare more compacted structures [Concrete is a heterogeneous material composed itself of different materials such as coarse aggregate, fine aggregate, cement, etc. The physical and chemical properties of these materials significantly affect the properties of concrete. One of the most important parts of such materials are fine fillers which compensate for the irregularities of aggregates available in concrete . Fine fiructures . The cheructures ,5,6. Conructures ,9,10,11.In the last few years, the use of mineral admixtures which are either inert or having very low reactivity in cement-based material, along with very fine sizes, has captured the attention of researchers due to the increase in demand of new mineral additives. In addition, researchers have focused on utilizing fine by-products such as blast furnace slag and fly ash for use as fine fillers for concrete, especially when they are already available in some regions. Utilizing such fine fillers in concrete has reported positive effects. As one example, grinding of sugarcane bagasse ash with high levels of quartz with reduction in its particle size has caused increase in pozzolanic activity ,13. In aIt was reported that ultrafine filler improves the strength properties of concrete by using quartz filler and higher water-to-cement ratios . The resIn this research work, the use of ultrafine quartz and silica as a partial replacement of cement in concrete mixtures with different water-to-cementitious ratios were examined extensively to investigate its effect on the compressive strength at different ages and durability related properties. The durability-related properties focused on were chloride ion penetrability, porosity, and rapid chloride ion penetrability (RCPT). Wider ranges of ultrafine ratios were used to find out the optimal content of ultrafine quartz and silica fume as partial replacements of cement with respect to the strength and durability related properties of concrete. Two types of ultrafines, namely quartz ultrafine and silica fume, were used. Concrete mixtures with four different water/binder ratios  were prepared for various dosages of quartz ultrafine  and different dosages of silica fume . Ordinary Portland cement (OPC) according to ASTM C150  requiremTwo types of sands with different particle sizes were used for preparation of mixes named as crushed sand and fine sand. The Fineness moduli were 1.47 and 4.66 for fine and crushed sand, respectively. Fine and crushed siliceous sand were combined as 65% and 35%, respectively, to achieve a fineness modulus of 2.54. Coarse aggregate with maximum size of 10 mm was used for mix preparation. The physical properties of fine and coarse aggregate are summarized in A modified polycarboxylic ether (PE) polymer (Glenium 51) was used in the production of required mixture. It had a specific gravity of 1.1 and dry extract of 36%. The dosage of PE is expressed as a dry extract (DE) per cement weight. The PE dosage was optimized for workable mixture of concrete. 3 for 0.25 w/c ratio, 500 kg/m3 for 0.30 w/c ratio, 450 kg/m3 for 0.35 w/c ratio, and 400 kg/m3 for 0.40 w/c ratio were chosen. The amount of coarse aggregate used for the mixtures was 1056 kg/m3. The slump of all mixtures was attempted to be maintained between 175 ± 25 mm as shown in The experimental work includes the preparation of eight different concrete mixes with four different water/binder ratios  with various dosages of quartz ultrafine  and different dosages of silica fume . All aggregates were added to the mixer and mixed for a few revolutions with absorption water and then the fines were added and mixed in dry state for few minutes. Premixed super plasticizer in water was added to aggregates and mixed for three minutes followed by a rest for three minutes, then mixed again for two minutes. The mixer was stopped followed by casting of the specimen in molds. Concrete cylinders of 100 × 200 mm were casted for standard compressive strength tests in rigid plastic molds, while concrete discs 100 mm in diameter and 50-mm thick were casted in molds for durability according to ASTM 1202  and poroThe compressive strength and modulus of elasticity of high-strength concrete was measured with a 100 × 200 cylinder at a loading rate of 0.25 MPa/s. A water saturated, 50-mm thick and 100-mm diameter concrete sample was subjected to 60 V applied DC voltage for 6 h. Concrete saturated samples were placed in two reservoirs. One reservoir of 3% NaCl and another reservoir of 0.3 M NaOH solution covered the saturated concrete sample for the entire duration of the test. The charge passed was noted and the concrete was characterized according to the table given in ASTM 1202 . P is the porosity of concrete in percentage. The porosity test was done by drying the concrete disc samples (100 mm in diameter and 50-mm thick) at 100 ± 5 °C until constant weight was achieved. After drying the samples to constant weight, they were placed in desiccator under vacuum for three hours followed by immersion in the de-aired distilled water for one hour to attain saturated sample of concrete. Porosity of concrete was measured by Equation (1):The effect of ultrafines and silica fume on the compressive strength for different water to cementitious ratios ranging from 0.25, 0.3, 0.35, 0.4 are shown in There are different parameters that affect the rate of gain of strength with time. Among those parameters, the type and strength class of cement, amount and type of mineral admixture and additions, water-to-binder ratio and curing conditions. The relationship presented for the time–strength has assumptions of moist curing and normal temperature. For a constant water-to-cement ratio, the higher strength was predicted for longer exposure of moist curing condition, considering that the anhydrous cement particles were going on under hydration. There was no increase in strength with time observed, as the water was lost through the capillaries due to air-curing conditions . There it days; s = coefficient depending on the cement type, such as s = 0.20 for high early strength cements, s = 0.25 for normal hardening cements; s = 0.38 for slow hardening cements and The CEB-FIP Models Code  suggestsThe effect of adding ultrafine and silica fume on the chloride ion penetrability of concrete according to ASTM 1202 are presented by rapid chloride permeability test (RCPT) values for different water-to-cement ratios as shown in The addition of silica fume on the chloride ion penetrability of concrete according to ASTM 1202 with different water-to-cement ratios is shown in The effect of adding ultrafine and silica fume in the concrete on the porosity according to RIlEM CPC 11.3 with different water-to-cement ratios are shown in 2 of more than 0.8. 2 of more than 0.9. It shows a strong relationship between porosity and RCPT values for silica fume concrete. The data was plotted and a best-fit relationship between porosity and RCPT values was a power function. It clearly shows that an increase in porosity shows an increase in RCPT values for all replacement levels of silica fume. There is a link between RCPT and porosity of concrete. The porosity is the total pores available in the concrete whereas RCPT is the total charge pass through the concrete mixture. A and B are empirical constants catering effects of aggregate, type of cementitious matrix, admixture, curing, testing condition, and age of concrete. Parameters A and B were given as 96.55 and 8.2 for Abram’s model [w is introduced in Equation (5) as follow:Predictive model for the compressive strength of concrete with different water-to-cement ratios was given by Abram , which i’s model ,30. To uw, is computed by the best-fit of experimental data of compressive strength versus the water-to-cementitious ratio for all the mixtures at the age of 28 days. A modification factor, It is also very important to know the relationship between permeation-related properties and compressive strength of concrete because usually, quality of concrete and its fitness for construction is judged based on the compressive strength. So, it is important to have a relationship between compressive strength and permeation-related properties. R stands for RCPT and P for porosity value, whereas w is constant which varies for different dosages of ultrafines for RCPT and porosity of concrete. α is the percentage replacement of ultrafines in the concrete. The predictive proposed model is drawn in w for RCPT and compressive strength with different replacement dosages of ultrafines with R2 ranging from 0.80 to 0.95. The value of w for RCPT varies from 250 × 103 to 1150 × 103 from low replacement levels of 5% to 35% of ultrafines in concrete, respectively. The relationship porosity and compressive strength for ultrafine dosages is shown in 2 ranging from 0.80 to 0.95. The value of w for porosity varies from 1.1 × 103 to 28 × 103 from low replacement levels of 5% to 35% of ultrafines in concrete, respectively. A predictive model has been proposed to find the compressive strength by using RCPT and porosity of concrete for different levels of replacements of silica fume as shown in Equation (7).R and P stands for RCPT and porosity value, respectively, whereas w and B are constants which vary for different dosages of silica fume for RCPT and porosity of concrete. α is the percentage replacement of silica fume in the concrete. The proposed predictive model for compressive strength and RCPT value for different dosages of silica fume is drawn in w for RCPT and compressive strength with different replacement dosages of ultrafines with R2 ranging from 0.96 to 0.98. The value of w for RCPT varies from 2.23 × 108 to 1.47 × 1011 with replacement levels of 8% to 12% of silica fume in concrete, respectively. Comparison of the results with other researchers shows good agreement with developed predictive models [B for RCPT varies from 2.27 to 3.04 from replacement level of 8% to 12% of silica fume in concrete, respectively. The relationship porosity and compressive strength for ultrafine dosages is shown in 2 ranging from 0.93 to 0.95. The value of w for porosity varies from 3.7 × 103 to 30 × 103 with replacement levels of 8% to 12% of silica fume in concrete, respectively. The value of B for RCPT varies from 1.13 to 1.42 with replacement levels of 8% to 12% of silica fume in concrete, respectively.➢Maximum increase of 12% in compressive strength with 12% partial replacement of silica fume was observed, whereas partial replacement of cement with 35% dosage of ultrafines showed about a 28% decrease in compressive strength. This decrease in the compressive strength was attributed to a non-pozzolanic activity of inactive ultrafine filler. However, partial replacement of cement with ultrafine up to 8% showed around a 5% increase in compressive strength.➢All the mixtures with silica fume and ultrafines have produced higher compressive strength than given by Abram’s predictive model, and the increase in compressive strength with partial replacement of silica fume and ultrafine was 63% and 38%, respectively, as compared to Abram’s predictive equation.➢The partial replacement of 8% of silica fume has yielded the RCPT value to a very low limit and low porosity for all water-to-cement ratios. However, the partial replacement with 8% of ultrafines has yielded RCPT to a very low limit at a water-to-cement ratio of 0.3, but at a replacement level of 15% ultrafines. Concrete mixture with all water-to-cement ratios yielded a very low limit of RCPT value.➢The relationships for RCPT and porosity of all mixtures was attained which suggested that there is strong correlation between porosity and RCPT for both ultrafines and silica fume, as expected.➢Predictive models have been proposed for RCPT and porosity by compressive strength with consideration of dosage of replacements of ultrafines and silica fume using experimental data.The conclusions of the work can be summarized as follow:


If supplementary cementitious materials (SCMs) are used as binders, the environmental impact produced by cement-based composites can be reduced. Following the substitution strategy to increase sustainability, several studies have been carried out with the aim of measuring the mechanical properties of different concrete systems, in which a portion of Portland cement was substituted with SCMs, such as fly ashes. On the other hand, studies on the structural behavior of reinforced concrete (RC) elements made with SCMs are very scarce. For this reason, in this paper, a new procedure is introduced with the aim of fulfil a new limit state of sustainability, in accordance with the serviceability and ultimate limit states required by building codes. Although the environmental impact of concrete decreases with the reduction of cement content, the proposed approach shows that the carbon dioxide emission of an RC beam is not a monotonic function of the substitution rate of cement with SCMs. On the contrary, there are favorable values of such substitution rates, which fall within a well-defined range. Material performance strategy, aimed at the reduction of clinker and thus of the volume of structures, by increasing the mechanical performance of concrete.Material substitution strategy, which consists of substituting clinker with cementitious and/or pozzolanic mineral admixtures .Reinforced concrete (RC) structures are currently designed to satisfy ultimate and serviceability limit states . NeverthIn several cases, these two strategies are contemporarily used, such as in the substitution of cement with supplementary cementitious materials (SCMs), which can be byproducts of the industrial process. For instance, coal fly ashes, deriving from the combustion of coal in power plants and which can be used to partially substitute Portland cement, can also enhance the strength and the durability of traditional concrete .From a practical point of view, the abovementioned strategies are not well integrated into the current limit state design approach. In other words, there is not a single procedure capable of assuring structural safety while also minimizing the environmental impact of concrete elements. In almost all cases, after designing the mechanical performance of RC structures, the environmental impact is assessed through broad-based green building rating schemes . As the In the opinion of the authors, to design more sustainable reinforced concrete structures, a new limit state has to be introduced and used in combination with the traditional limit states. In this way, a code-specific language addressing sustainability practices, which is one of the key objectives of the American Concrete Institute ACI Concrete Sustainability Forum , can be 2 emitted per cubic meter of concrete increases with the concrete strength. According to Habert’s and Roussel’s [β = mass of CO2 emitted by the production of a cubic meter of concrete (whose binder is only cement); cf = average compressive strength of concrete (whose binder is only cement); and δ = coefficient of proportionality.In the material performance strategy, the COoussel’s  model  and on the rate of substitution S. Thus, for given values of Aβ, cAf, and S, by means of the following functions, both cf and β can be evaluated:S = is the substitution rate of cement with fly ash that modifies cAf and Aβ into cf and β, respectively; α = strength coefficient; and γ = sustainability coefficient. Obviously, for a specific concrete system, the three coefficients α, δ, and γ have to be evaluated through the regression analyses of the available experimental data.The new values of 2 released into the atmosphere, the data reported in Lam et al.  investigδ = 48.088 kg CO2/(m3 MPa0.5);α = −0.006732;γ = −0.009731.Accordingly, the following values can be obtained through least squares approximation of the experimental data reported in cf-S and β-S of a specific concrete system. For instance, the diagram depicted in Such parameters, to be used in Equations (1)–(3), seem to be independent of the water/cement ratio and are included in the procedure illustrated in sε > ydε = ydf/sE, where sE = 200 GPa = elastic modulus of steel), the stress is constant and equal to the yielding strength, regardless of the strain.According to Eurocode 2 (EC2)  the ultickf = characteristic compressive cylinder strength of concrete at 28 days; ykf = characteristic yield strength of reinforcement; cγ = 1.5 = partial safety factor of concrete; and sγ = 1.15 = partial safety factor of steel.The design strengths of both materials are computed in accordance with the partial safety factors given by Eurocode 2 :(4)σcd=EdM = design bending moment applied to the cross-section and produced by the external actions and RdM = design bending moment capacity of the cross-section.With the constitutive laws illustrated in RdM can be analytically computed assuming the limit strain conditions illustrated in sε ≥ ydε).The value of Under these assumptions, the equilibrium and compatibility equations provide :(7a)ω=0ξ is fixed, the optimal values of ω and Rdμ can be calculated through Equation (7).If the value of k1 = 1.4 and k2 = 3.5 are the values used in Italy.Generally, code rules fix the minimum and the maximum value of the reinforcement area ,2 as folsA close to the upper bound of Equation (11), thus:To reduce the volume of the cross-section, it is better to design the area ξ can be obtained:If Equation (12) is substituted into Equation (7a), the optimal value of ξ = 0.25 is obtained when k2 = 3.5 and sγ = 1.15. As stated by EC2 [ξ ≤0.25 for concrete strength classes lower than C50.It must be noted that in the case of concrete C25 , the value of Finally, by substituting Equation (9) into Equation (12) and Equation (10) and Equation (13) into Equation (7b), the following formulae can be obtained:L= span length of the beam , and it can be assumed as a fraction of the height H:ρ = coefficient.The depth of the concrete cover δ, α and γ are known), it is possible to select a specific value of strength cf  and the corresponding coefficient β. For the beam depicted in L, the density of concrete De, and the applied load dq are the input data. The values of the depth H and concrete cover c can be obtained from the coefficients ψ and ρ, regarding the serviceability (control of deflection) and the durability requirements, respectively.When a concrete system is introduced  is substituted into Equation (14b), and assuming BI, in terms of CO2 released into the atmosphere, is:ϕ is the environmental impact of steel as obtained from The area of reinforcement in tension is then computed with Equation (14a), and the global impact of the beam cf-S and β-S functions can now be extended to calculate the relationships b–S, sA–S, and BI–S of the RC beam illustrated in fckA = 25 MPa ;α = −0.006732;δ = −0.009731;ψ = 0.1;ρ = 0.07;L = 5000 mm;De = 25 kN/m3;dq = 46.5 kN/m;k2 = 3.5;ϕ = 1174.525 kg CO2 /m3.The procedure illustrated in  − 8 MPa ,2) and:β (and thus cf) linearly decreases with S , the values of BI have a minimum, BImin, in correspondence to the substitution rate SF (where 0 < SF < 100%).The above observations are also valid for the area of the steel used to reinforce the tensile zone of the RC beam. Namely,  S ≅ 75% c. As a r S > 75% d. In oth% , the impact is higher due to the high content of cement. On the contrary, when S > SF, the impact increases despite the low amount of cement (and low concrete strength), because large amounts of concrete and steel are needed. Finally, the proposed model reveals that for high values of fckA, the best substitution rate of cement with fly ash can be 100% .It must be noted that the shape of the functions S [2, a new limit state of sustainability, corresponding to the maximum environmental impact of a structure, is herein introduced. For instance, code rules or tenders can require a concrete in which the substitution of cement with fly ashes leads to a reduction of the carbon dioxide emission of larger than 20%  can be selected. The best S does not necessarily coincide with SF, because, for large substitutions, the RC beams and the area of rebar are too large to be used in practice. Moreover, higher rates of substitution would provide a decrease in the early strength of concrete. Thus, some building codes impose lower limits on the usage rates of fly ash than the feasibility rates measured by laboratory tests.From a practical point of view, the substitution rate cannot be too high, because some problems occur in the concrete system, whose early strength decreases with S . Thus, tested in ), with rFinally, it must be noted that though the proposed approach herein applies to fly ashes only, it can be easily generalized to other SCMs. Indeed, the procedure illustrated in cf-S and β-S , BI increases with the initial strength cAf. Nevertheless, the relative minimum of the curve BI-S moves towards higher S. As BImin decreases when cAf increases, it seems more convenient to use high strength concrete systems  but with the maximum substitution rate of cement with fly ash.In absence of cement substitution  is introduced, the reduction of the carbon dioxide emission can be achieved also in the case of low values of S.If a new limit state of sustainability .Finally, future works will be devoted to calculating


Patient records were divided into four diagnoses groups: surgical, non-surgical, chronic suppurative otitis media (CSOM), and others. Of 2909 inpatients, 51% had surgical diagnoses. An average of 83% of patients in the clean surgery group and more than 75% in the viral and non-infectious groups were prescribed antibiotics. CSOM was the most common diagnosis (31%), where 90% of inpatients were prescribed antibiotics. Overall, third-generation cephalosporins and fluoroquinolones were most commonly prescribed. This study highlights the inappropriate prescribing of antibiotics to patients of clean surgeries, viral infections, and non-infectious groups. The single-prophylactic dose of antibiotic for clean-contaminated surgeries was replaced by the prolonged empirical prescribing. The use of microbiology investigations was insignificant.Antibiotics are over-prescribed in low-and-middle-income countries, where the infection rate is high. The global paucity of standard treatment guidelines and reliable diagnose-specific prescription data from high-infection risk departments such as the otorhinolaryngology  is a barrier to rationalize antibiotic use and combat antibiotic resistance. The study was conducted to present diagnose-specific antibiotic prescribing patterns of five years at ENT inpatient departments of two private-sector Indian hospitals. Data of all consecutive inpatients ( Antibiotics are overprescribed worldwide, but the practice of overprescribing is more common in low-and middle-income countries (LMICs), where standard treatment guidelines are not available or implemented, and infection rates are high ,2. AntibAntibiotics are prescribed profusely at healthcare facilities. These places also provide suitable conditions for rapid emergence and spread of antibiotic-resistant bacteria ,5,6. TheThe aim of this study is to present and compare antibiotic prescribing patterns corresponding to ENT diagnoses (indications), and further probing of surgical and non-surgical indications, at the ENT departments of two private sector, tertiary healthcare hospitals: a teaching hospital (TH) and a non-teaching hospital (NTH), in the Ujjain district of Central India.A prospective study was conducted for five years (2008–2013), including all patients admitted in the ENT inpatient departments at the TH and the NTH. The data were analyzed and presented at the department level, diagnosis groups, and specific diagnosis level for the two hospitals.The two study hospitals are located in the Ujjain district of Madhya Pradesh state in Central India. The study settings have been described in previous publications in detail . In brieThe data collection has been explained in detail in previous publications ,8. In shPrescribed antibiotics were classified according to the WHO recommended methodologies  and the defined daily dose (DDD)) to facilitate international comparison of the results . The DDDThe indications assigned by the treating consultants in the patients’ files were recorded at the time of discharge and were not verified externally. The indications were classified according to the International Classification of Diseases version 10 (ICD-10) . p < 0.05.The study was focused on the anatomical and therapeutic main groups of the antibacterials for systemic use, with the WHO suggested ATC code-J01 . The ratn = 550, Data of (i) the inpatients aged less than 15 years old, (ii) those that did not have an ENT-related diagnosis, or (iii) had incomplete patient records were excluded before analysis n = 550, . PatientThe prevalence of chronic suppurative otitis media (CSOM) is high in the West Pacific, South East Asia, and particularly in India . AntibioThe present study was observational, and all measures were in place to maintain patients’ confidentiality during data collection as well as analysis in accordance with the standard guidelines. None of the patients was contacted at any stage of the study, and no patient was identified or analyzed individually. The data were analyzed collectively forming various groups. The ethics committee of R. D. Gardi Medical College, Surasa, Ujjain, India approved the study with approval number: 41/2007 and 114/2010. Following the norms of an observational study design, the need for the approval of trial registration was waived by the ethics committee. The datasets generated during the current study are not publicly available due to breaching individual privacy, but de-identified datasets are available from the corresponding author on reasonable request. A summary of data analyzed during this study is included in this published article and its Of the 3527 patients admitted to the ENT departments, 2909 were included in the analysis . Out of p < 0.05). Overall, the prescriptions made using generic names were significantly higher (p < 0.05) and adherence to the WHOLEM and NLEM were also higher at the TH than at the NTH  and clean-contaminated surgery (A2) subgroups at the NTH than at the TH (96% each compared to 94% and 93%), while it was higher in the clean surgery (A3) at the TH than at the NTH . At the TH out of the 109 patients who underwent tonsillectomy or adenoidectomy, 106 patients were prescribed antibiotics with a median treatment period of six days (range: 1–21 days). Overall, at the NTH, the proportion of prescriptions made using brand names 94%,  was highCSOM (group C) was the most common diagnosis with 20% of total inpatients at the NTH and 33% at the TH . At bothIn the non-surgery group (group B), antibiotics were prescribed to a higher proportion in all subgroups at the TH (83–94%) than at the NTH 75–92%, . In the The duration of antibiotic prescription was highest in groups A and C. p < 0.05). The patients in the surgical diagnosis groups (A and C) were more often prescribed antibiotics than the patients in non-surgical group B. Overall, the FDCs of amoxicillin with clavulanic acid J01CR50 (45%), cefuroxime J01DC02 (19%), and ciprofloxacin J01MA02 (8%) were the most commonly prescribed antibiotics at discharge. At discharge, a significantly higher number of patients were prescribed antibiotics at the TH (43%) than at the NTH . Antibiotics were prescribed most frequently and for the most prolonged period to CSOM inpatients. Antibiotics were commonly prescribed for clean surgeries, clinically viral infections, and non-infectious diagnoses. Overall, empiric treatment was extended during the entire hospital stay for most inpatients. One of the reasons for this extension might be a lack of sending samples for bacterial culture and antibiotic susceptibility tests. None of the inpatients was prescribed a single prophylactic dose of antibiotics for clean-contaminated surgeries, as per recommendations ,23. CeftAmong the patients who had clean-contaminated surgery, subgroup A2, a single dose regime of a first- or second-generation cephalosporin, preferably cefazolin, is recommended as prophylactic antibiotic treatment ,23. In oAmong the patients who underwent clean surgery (subgroup A3), 81% at the NTH and 86% at the TH were prescribed antibiotics, even though prophylactic antibiotic treatment is not recommended for this subgroup ,23. KhanThe results of antibiotic prescribing practices for tonsillectomy and adenoidectomy in the subgroup A3 highlights several underlying issues. The first issue was in accordance with a globally ongoing discussion. The discussion raises the question of whether antibiotics should be prescribed as a prophylactic antibiotic treatment to patients undergoing tonsillectomy or adenoidectomy or not ,23,29. OAnother issue raised was regarding universal applicability of a guideline. In the present study, the American and Scottish guidelines were used to facilitate the classification of the surgical indications concerned with prescribing of antibiotics . On the Among the inpatients with non-surgical diagnoses, group B, antibiotic treatment was indicated only to patients having a microbiologically confirmed or clinically estimated high risk of a bacterial infection (subgroup B1) ,23. A maFurthermore, a longer duration of hospital stay has been reported to correspond to a higher risk of acquiring healthcare-associated infections (HAI) and increases the risk of being prescribed antibiotics . Thus, iCSOM was the most common diagnosis in our study settings. The procedures related to CSOM are categorized in classes comparable to subgroup A1 , to which antibiotics should be prescribed as treatment and A3 , to which antibiotics should not be prescribed ,23,33. IThe inpatients in group C at the TH received antibiotics for the most prolonged period with a median of 11 days. The lack of comparable antibiotic surveillance studies and local antibiotics prescribing guidelines for CSOM surgeries at the ENT inpatient departments of the South-Asian region are the major factors affecting such a prescribing pattern. We recommend conducting qualitative studies to further analyze the factors driving the prolonged prescribing of antibiotics and infrequent prescribing of topical antibiotics.The new FDCs of antibiotics were prescribed at a lower extent J01RA,  as compaThe samples for bacterial culture and antibiotic susceptibility tests were not sent frequently in both study settings. Similar results were found in a short-term study conducted previously at the study hospitals . EmpiricActive CSOM infections are often polymicrobial, thus, most of the patients might have received several antibiotic prescriptions at the lower levels of healthcare facilities before visiting and being admitted at the tertiary level healthcare settings  ,33. The Results of our study highlight the need to conduct similar surveillance studies at other settings followed by contextualized qualitative studies to understand the underlying factors affecting practitioners for the observed patterns of antibiotic prescribing.The strengths of this study were its long-term, continuous data collection, and detailed data at a diagnosis level recorded for all admitted patients. Furthermore, the data were from the private sector that provides healthcare to most of the Indian population. A limitation of this study was that perioperative notes were not included, which could have facilitated the interpretation of the results. However, this was not the objective of the present study. Although the data collection process was supervised robustly, the possibility of human error during data collection and entry cannot be denied. However, the possible effect of such human errors was expected to be minor due to the large study population, long study duration, robust monitoring, trained data recorders, and data entry staff. The establishment of the manual process of data collection, coding of antibiotics, indications, and data entry explains why the data was analyzed and published at the current time. The recommended denominator for DDD is per 100 bed days for the inpatients . HoweverThe present study offers a unique insight into the otorhinolaryngology inpatient departments of private healthcare facilities in India and identifies several under-focused issues to be addressed in the future. In the present study, a high proportion of inpatients with non-indicated diagnoses, such as clean surgeries, viral infections, and non-infectious indications were prescribed antibiotics. A significant deviation was observed between the antibiotic prescribing patterns at the study settings and the international recommendations and guidelines. This deviation indicates poor applicability of these recommendations in LMICs that are not based on the data from LMICs but form high-income countries. This once again highlights the need for the development of contextualized standard treatment guidelines based on local infectious diseases and prescribing data. The scarcity of local antibiotic prescribing surveillance studies and resistance patterns limits the development of local prescribing guidelines. Surveillance studies at the private healthcare settings of LMICs are crucial. Our sustainable, low-cost solution of manual data collection could be adapted at resource-constrained settings where there is a lack of computerization to conduct surveillance studies. Furthermore, the use of ATC/DDD methodology and the ICD-10 codes made our results comparable and exchangeable to other global studies. The findings of this study formulate a standard policy and indicate the practice patterns of antibiotic prescribing in high-risk infection inpatient departments. Prescribing broad-spectrum antibiotics empirically and inadequate use of the microbiology laboratory was also observed in both study hospitals.Further probing using a qualitative approach is suggested for better understanding the influencing factors for current prescribing patterns, under-utilization of microbiology facilities, and possible areas of improvement. We also recommend developing a customized educational workshop and group discussions as a part of antibiotic stewardship programs for prescribers focused on developing and implement ingdiagnose-specific local antibiotic prescribing guidelines.


The combination of functional polymers with inorganic nanostructured compounds has become a major area of research and technological development owing to the remarkable properties and multifunctionalities deriving from their nano and hybrid structures. In this context, polyhedral oligomeric silsesquioxanes (POSSs) have increasing importance and a dominant position with respect to the reinforcement of polymeric materials. Although POSSs were first described in 1946 by Scott, these materials, however, were not immediately successful if we consider that, starting from 1946 and up to 1995, we only find 85 manuscripts in the literature regarding POSSs. This means that less than two papers per year were published over 50 years. Since 1995, we observe an exponential growth of scientific manuscripts concerning POSSs. It has changed from an annual average of 20 manuscripts for the period 1995–2000 to an annual average of about 400 manuscripts, with an increase of 2800%. The introduction of POSSs inorganic nanostructures into polymers gives rise to polymer nanostructured materials (PNMs) with interesting mechanical and physical properties, thus representing a radical alternative to the traditional filled polymers or polymer compositions.Polyhedral oligomeric silsesquioxanes, with Si vertices interconnected by –O– linkages, form three-dimensional nanometer size cage structures with substituents attached to silicon atoms. These substituents may contain reactive groups, such as hydroxyl or isocyanate. A combination of a rigid inorganic nanocore with organic vertex groups makes POSS molecules useful hybrid building blocks that can be chemically incorporated in the polymer matrix by copolymerization, grafting or reactive blending, or physically mixed by solvent casting or polymer processing by using, for example, the extrusion technique. Depending on the number and kind of functional groups attached to the POSS cage, silsesquioxane moieties can be chemically built into a polymer structure as a side group of the main chain or terminating end-group, as a main chain fragment, or as a macromolecular network knot.Various routes of chemical decoration of POSS molecules with organic substituents offer new perspectives for synthesis of novel organic–inorganic hybrid materials with desirable—and often still unknown—properties. Interest in POSS-containing polymer composites and hybrid materials has been growing in the recent years as they show improved mechanical performance, thermo(oxidative) stability, and surface durability. Well-defined structure, non-toxicity, and enhanced biocompatibility, as well as biostability against oxidation, hydrolysis, and enzymatic attack under in vitro and in vivo conditions make functionalized silsesquioxanes desirable nanofillers in the biomedical field as implants and scaffolds. Other application areas include membranes, high-performance adhesives, flame retardants, aerogels, optical sensors, and shape-memory materials, to name a few. On the other hand, challenges with polyhedral oligomeric silsesquioxanes’ tendency to agglomerate are still to be addressed during synthesis and engineering of nanostructured polymer-based composites made thereof.This special issue, which consists of 18 articles, including two review articles, written by research groups of experts in the field, considers recent research on novel POSS-based polymeric materials.Firstly, it was highlighted that, compared with the other most commonly used fillers, POSSs possess the advantage of being molecules, thus allowing the combination of their nano-sized cage structures, which have dimensions that are similar to those of most polymer segments, and production of a particular and exclusive chemical composition. These characteristics linked with their hybrid (inorganic–organic) nature allow researchers to modify POSS according to particular needs or original ideas, before incorporating them into polymers .Liu et al. synthesized a novel organic–inorganic hybrid containing allyl benzoxazine and polyhedral oligomeric silsesquioxane (POSS) to be used for preparing epoxy resin composites in order to verify the effect of POSS on the thermal stability and flame retardancy of a prepared material. Improvement in thermal stability and flame retardancy was observed when the amount of POSS reached 10% or more, thus demonstrating that POSS nanoparticles can effectively protect the combustion of internal polymers .7-POSS) modified by polyols to be used for obtaining polyurethane nanocomposites at different POSS contents. The results showed that the polyol-terminated POSS particles overcame the nano-agglomeration effect and evenly dispersed in the polymeric matrix. The damping factor of resultant nanocomposites increased from 0.90 to 1.16, while the glass transition temperature decreased from 15.8 to 9.4 °C when POSS contents increased from 0 to 9.75 wt%. They attributed the improvement of the damping properties of the composites to the friction-related losses occurring in the interface region between the nanoparticles and the matrix [Wei and co-workers, by using the graft-from method, prepared a series of heptaphenyl siloxane trisilanol/polyhedral oligomeric silsesquioxane  (PNIPA) network directly. Furthermore, they observed that the gels with a hydrophilic PNIPA network exhibited better swelling ability and remarkable temperature responsiveness, and their volume phase transition temperature can be adjusted by altering the content of Oa-POSS. The deswelling rate of gels increases gradually with the increase of POSS content due to the hydrophobic Si–O skeleton of POSS [Chen and collaborator used cationic octa-ammonium polyhedral oligomeric silsesquioxane (Oa-POSS) particles to improve the performance of traditional sodium alginate (SA) hydrogels that meet a greater application demand in the biomedical field. The characterization of the gels demonstrated that their properties depend on the content of both the uniformly dispersed Oa-POSS and poly and photorheology, Marcinkowska et al. investigated the effect of monomethacryloxy-heptaisobutyl POSS (1M-POSS) on the process. They determined that at low concentrations the modifiers with a bulky substituent increase the molecular mobility by increasing the free volume fraction, which leads to an acceleration of the termination and slows the polymerization. At higher concentrations, they retard molecular motions due to the “anchor effect” that suppresses the termination, leading to acceleration of the polymerization. Thus, they considered the possibility of anchoring a monomer with a long substituent around the POSS cage, which further enhances propagation .Song et al. synthesized a series of hybrid thermoplastic polyurethanes from bi-functional polyhedral oligomeric silsesquioxane and polycaprolactone using 1,6-hexamethylene diisocyanate as a coupling agent for testing their thermo-mechanical properties. They observed an increase in decomposition temperature and glass transition temperature when compared with pristine polyurethane, and an improvement of both storage modulus (G′) and loss modulus (G″), showing the possibility to further adjust these parameters by varying POSS content in the copolymer. In addition, the synthesized POSS polyurethanes demonstrated a remarkable effect in toughening commercial polyesters, indicating a simple yet useful strategy in developing high-performance polyester for advanced biomedical applications .The modification of polyurethane foams with aminopropyl isobutyl-POSS (APIB-POSS) and aminoethylaminopropylisobutyl-POSS (AEAPIB-POSS) to enhance their mechanical and thermal properties was the object of the study of Członka and her collaborators. The results showed that the morphology of modified foams is significantly affected by the filler typology and content, which resulted in inhomogeneous, irregular, large-cell shapes, and further affected the physical and mechanical properties of resulting materials. The best results were obtained for the polyurethane modified with 0.5 wt% of APIB-POSS, showing greater compression strength, better flexural strength, and lower water absorption .Aiming to bridge the gap between small-molecule surfactants and amphiphilic block copolymers Qian and coworkers designed and synthesized single-tailed giant surfactants carrying hydrophobic poly(ε-caprolactone) (PCL) as the tail and a hydrophilic cage-like polyhedral oligomeric silsesquioxane (POSS) nanoparticle as the head. To endow the POSS head with adjustable polarity and functionality, three kinds of hydrophilic groups, including hydroxyl groups, carboxylic acids, and amine groups, were installed to the periphery of the POSS molecule by a high-efficiency thiol-ene “click” reaction. The full characterization demonstrated that these giant surfactants can form nanospheres with different sizes in aqueous solution .Li et al. synthesized, by a one-step grafting reaction, a hybrid flame retardant copolymer starting from methacryloisobutyl polyhedral oligomeric silsesquioxane (POSSMA), reactive glycidyl methacrylate (GMA), bis-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide methacrylate (bisDOPOMA), and derivative functionalized graphene oxide (GO). They showed a remarkable enhancement of the composites’ thermal properties by adding the graphene oxide hybrid flame retardant (GO-MD-MP). Furthermore, they observed an increase in the limiting oxygen index as well as the mechanical strength of the epoxy resin [Wang et al. prepared blends of cyanate ester and phthalonitrile–polyhedral oligomeric silsesquioxane and studied their cure behavior by means of thermal and rheology experiments. The obtained copolymers showed high chemical reactivity, low viscosity, and good thermal stability. In addition, an increase in glass-transition temperature of the blends, compared to cyanate ester resin, was recorded, making them suitable for preparing carbon-fiber-reinforced composite materials via a winding process and a prepreg lay-up process with a molding technique .The effect of preparation method, POSS content, and type, on the morphology, thermal, mechanical, and surface properties of poly(ε-caprolactone)/POSS derivatives nanocomposites (PCL/POSS) were studied by Cobos et al. Morphological analysis evidenced that amino-POSS with a longer alkyl chain exhibited a better degree of dispersion independent of preparation method, reducing the formation of POSS crystalline aggregates. They also showed how the incorporation of POSS derivatives into the PCL matrix improved thermal stability and enhanced the surface hydrophobicity of PCL .Ueda and collaborators designed and prepared, by the casting method, dual-functionalized polyhedral oligomeric silsesquioxane (POSS) derivatives, which have seven fluorinated alkanes and a single acrylate ester on the silica cube, to be used as a filler for lowering the refractive index and improving the thermomechanical properties of poly(methyl methacrylate) (PMMA). They observed a large lowering of the refractive index. Moreover, the degradation temperatures and the storage moduli of the obtained films were greatly elevated by loading the POSS fillers .Niemczyk and coworkers were engaged in the evaluation of a novel series of siloxane-silsesquioxane resins as possible flame retardants in polypropylene (PP) materials. Their results revealed that the functionalized resins formed a continuous ceramic layer on the material surface during its combustion, which improved both thermal stability and flame retardancy of the PP materials. This beneficial effect was observed especially when small amounts of siloxane-silsesquioxane resin were applied .Li et al. prepared two different models of hybrid ionic liquids (ILs) based on polyhedral oligomeric silsesquioxanes (POSSs), showing excellent thermal stability and low glass transition temperatures. They then focused their attention on the high sensitivity of these products for detecting nitroaromatic compounds, highlighting their great potential for the detection of explosives . Lin and collaborators prepared and characterized mesoporous molecular sieves by using rice husk as a silicon source, thus also solving environmental pollution problems to avoid its burning as garbage, in addition to the desired field of application. Structural characterization showed evenly distributed and hexangular mesoporous structures. An increase in pore size was obtained, thus leading to an increase in ammoni–-nitrogen adsorption capacity .Finally, this special issue hosts two reviews. The first one, by Dudziec et al., highlights the significant number of papers on the design and development of POSS-based organic optoelectronic as well as photoluminescent (PL) materials. In view of the scientific literature abounding with numerous examples of their application ), the aim of the review was to present efficient synthetic pathways leading to the formation of nanocomposite materials based on silsesquioxane systems that contain organic chromophores of a complex nature. A summary of stoichiometric and predominantly catalytic methods for these silsesquioxane-based systems to be applied in the construction of photoactive materials or their precursors was given .The preparation of hybrid nanocomposite materials derived from polyhedral oligomeric silsesquioxane (POSS) nanoparticles and polyimide (PI) was the subject of the second review presented by Mohamed and Kuo. The two researchers discuss the various methods used to insert POSS nanoparticles into PI matrices, through covalent chemical bonding and physical blending, as well as the influence of the POSS units on the physical properties of PIs .


Malignancy was ruled out and the patient was treated with corticosteroids, though there was no change in CT appearance over 16 months. The CT imaging pattern in our case is atypical from previous literature characterisation.Immunoglobulin G4 (IgG4)-related disease is a relatively rare and only recently recognized immune-mediated fibro-inflammatory condition that is commonly associated with autoimmune pancreatitis. Reports have further been characterized in almost all other organ systems, with several lung-related IgG4 disease reports emerging over the past decade. IgG4-related disease affects more than one organ in 60–90% of patients. To this date, there have been few published cases of pathologically proven isolated IgG4-related lung disease (IgG4-RLD), where no other organ is affected. We report an isolated pulmonary case of IgG4-RLD in a 65-year-old female with clinical and radiological manifestations suggestive of primary lung malignancy. CT revealed multiple sub-solid ground glass opacities, several of which were part-solid, others were pure ground glass. Histological analysis revealed IgG4 disease with no evidence of neoplasia. Serum IgG4 levels were elevated (206 mg dl A 65-year-old female non-smoker of Indian origin living in the UK for 42 years was referred to rheumatology outpatients with a 5-year history of mild arthralgia affecting the shoulders, hands and elbows. A 6-month history of productive cough without haemoptysis and concurrent weight loss was also reported. No fever, night sweats, chest pain or shortness of breath on exertion was present. Examination of the chest, cardiovascular system and abdomen was unremarkable. The only finding was nodal osteoarthritis in the hands with evidence of Heberden’s and Bouchard’s nodes, but no evidence of active synovitis.–1, CRP 18 mg l–1, rheumatoid factor was positive (108 IU ml–1), as was ANA at 1/160. ENA, DNA and ANCA were negative.Laboratory tests revealed raised ESR 118 mm hrCT demonstrated multiple pulmonary sub-solid opacities, many of which were part-solid with a central solid component and a ground-glass halo, others were small pure ground glass nodules . They inBronchial washings contained squamous cells, respiratory epithelial cells, mixed leucocytes and blood. No malignant cells were seen. The washings did not grow bacteria or acid-fast bacilli.Percutaneous CT-guided lung biopsy of the largest opacity was undertaken. Histological examination revealed lung tissue containing inflammatory cell-rich areas with a fibrous and collagenous background and occasional residual alveoli. Immunohistochemistry confirmed the lymphoplasmacytic nature of the infiltrate with many of the plasma cells expressing IgG4 (more than 50 per high power field) . No evid–1), a diagnosis of IgG4-related lung disease was made.On the basis of histopathological evidence and raised serum IgG4 level , gastrointestinal tract, exocrine and endocrine organs, skin, orbits and lymph nodes. Within the thorax, it can involve lung, mediastinum, pleura and pericardium. Multiorgan involvement is common (>90%), either synchronously or metachronously. It is rare, with an estimated incidence of 0.2 to 1/100,000 in Japan, with no incidence data in other countries.5 Since then, there have been reports of isolated IgG4-related disease in the lung, but precise incidence data has not been established as yet. From the limited cases within the literature, 70–80% appear to affect men of middle to elderly age and most of these cases have been described in the Far East. Approximately half the patients found to have IgG4-RLD presented with no pulmonary symptoms while the rest had non-specific symptoms such as dyspnoea, chest pain or cough.7The first pulmonary cases were reported in 2004 in association with autoimmune pancreatitis.–1) has been found to be a common occurrence in IgG4-related disease, it is not alone sufficiently sensitive or specific for diagnostic purposes. The level can be normal in 3–30% of affected individuals and can be present in 5% of the normal population, as well as in patients with unrelated conditions including auto-immune disorders.8Although elevated serum IgG4  or usual interstitial pneumonia (UIP). The less common solid nodular and round-shaped GGO can mimic primary lung cancer.11Radiologically, Inoue and colleagues collected 13 cases of IgG4-RLD over 9 years and categorized four major subtypes: (a) solid nodular, with a solitary nodular mass lesion (four cases); (b) round shaped ground glass opacity (GGO), with multiple round GGOs (two cases); (c) alveolar interstitial, with honeycombing, bronchiectasis and diffuse GGO (two cases) and (d) bronchovascular, with thickening of bronchovascular bundles and interlobular septa (five cases).8 Glucocorticoids are the first-line agent for active disease unless there are contraindications and some patients may benefit from additional steroid-sparing immunosuppressive agents, including B-cell depletion agents such as Rituximab. Though most cases respond to treatment, relapse is common and progression to multi-organ involvement is also recognised. Nonetheless, a more recent case series reported three pulmonary cases having benign outcomes, with stable disease as well as regression, following conservative management only thus raising the question whether all patients require treatment with immunosuppressive therapy.12IgG4-RLD is still an emerging entity and evidence for ideal management strategy remains scarce. However, there has been recent international consensus statement on the management of IgG4-related disease in general, stating that all symptomatic patients and a subset of asymptomatic patients require treatment.13 Indeed the prior case by Zhou et al. showed lesions with much more predominant mass like foci with smaller surrounding halo, with clinical presentation more reflective of infection than malignancy. Their biopsy was obtained using fibre-optic bronchoscopy, thus not specifically of lesions with the halo sign, which were commented on to be peripheral. In contrast, our sample was obtained using CT-guided core needle biopsy through the largest lesion with the halo sign itself . Given the patient’s medical history of autoimmune disorders, other important differential diagnoses considered were lymphoproliferative disorders, organizing pneumonia or fungal infection. This case highlights the need to maintain an index of suspicion for this albeit rare but increasingly reported condition, which would not be diagnosed without specific histological consideration supported by serum immunoglobulin subtype testing.IgG4-related disease is a recently recognised fibroinflammatory disorder that can affect virtually any organ.Pulmonary manifestations can mimic fibrosis, infection, as well as primary lung malignancy.Diagnosis relies on a radiological imaging, elevated serum IgG4 levels and histopathological confirmation, particularly immunohistochemical staining for IgG4-specific antibody.Little is known about the significance of IgG4-related disease, but it is frequently steroid-responsive so increasing awareness facilitates appropriate testing to establish diagnosis.Written informed consent for the case to be published  was obtained from the patient(s) for publication of this case report, including accompanying images.


In this paper, we propose an accurate and practical model for the estimation of surface-breaking discontinuity  depth in concrete through quantitative characterization of surface-wave transmission across the discontinuity. The effects of three different mixture types  and four different simulated crack depths on surface-wave transmission were examined through experiments carried out on lab-scale concrete specimens. The crack depth estimation model is based on a surface-wave spectral energy approach that is capable of taking into account a wide range of wave frequencies. The accuracy of the proposed crack depth estimation model is validated by root mean square error analysis of data from repeated spectral energy transmission ratio measurements for each specimen. The presence of cracks in concrete structures can cause serious safety and/or durability problems, which may result in fatal disasters requiring tremendous social (life and monetary) costs ,2. HenceFrom a broad viewpoint, nondestructive methods developed for the evaluation of the damage condition of concrete to date include visual and optical inspections and stress-wave based methods, as well as nuclear, magnetic, and electronic methods . Of thesThe depth of a crack is generally related to the width of the crack, which can be relatively easily measured by means of optical microscopy or image scanning ,34. HoweOver the last two decades, surface-wave based techniques have been developed to estimate the depth of cracks in concrete structures. The transmission and reflection of Rayleigh surface waves across a crack are sensitive to the crack depth as well as the wave frequency . Angel aPopovics et al.  applied Most previous surface-wave studies focused on the improvement of the test configuration and/or the qualitative assessment of the effects of crack depth on surface-wave transmission. However, practical models to use those data for the estimation of crack depth in concrete have been lacking. In addition, the influence of concrete properties on surface-wave transmission has not been clearly understood, and the verification of self-calibrating measurements carried out on varying concrete mixtures has not been established.Given the aforementioned concerns, this study proposes a practical approach for the accurate estimation of surface-breaking discontinuity  depth in concrete using surface-wave transmission data. The surface-wave tests of this paper are conducted with three different concrete mixtures (differing the maximum aggregate size and the concrete strength) and four different simulated crack depths. The crack depth estimation model is developed based on a spectral energy approach that is capable of taking into account a wide frequency range of waves. The proposed crack depth model illustrates a good accuracy regardless of the concrete mixture type.j due to an impact at point i, i, j, and i and j.The geometric formation  of a surface crack in concrete may be characterized by the transmission behavior of surface waves across the crack. Contact conditions between the sensors and concrete surfaces, as well as between the impact sources and concrete surfaces, may cause considerable variations in the surface-wave signals ,16,17,18Here, The self-calibrating method based on the same travel path assumption is valid for cracks perpendicular to the surface, but its applicability to inclined cracks should be examined through future study.SC(f), is defined as the ratio between geometric and arithmetic averages of five independent transmission ratios [To determine a reliable frequency domain of surface-wave measurements, the signal consistency index at each frequency, n ratios : (6)SC. In addition, the spectral energy transmission ratio was defined as the spectral energy for a considered crack depth normalized by the spectral energy for no crack [id, and Here, no crack ,17;(8)SThe purpose of this experimental study was to quantify the transmission characteristics of surface waves in concrete with various crack depths and mix proportions, so as to propose a practical model for the estimation of crack depth. Each specimen represented a concrete slab with a flexural crack, and was fabricated to have an artificial crack using a notch . The useThe test variables of this study included the crack depth, presence of coarse aggregate, and concrete compressive strength, as shown in The compression test results of the three mixtures in To minimize the effects of reflected wave signals from the bottom and side faces of the specimen, the specimen was designed to be sufficiently wide and deep: 250 mm in width, 250 mm in length, and 100 mm in depth . The dimFor the test setup, two impact locations were defined at points A and D, and two signal receivers were attached at points B and C, as shown in A set of two separate impacts were applied at points A and D in a row, as shown in The sampling rate of the data acquisition (DAQ) used to measure surface wave signals was 500 kHz. The data processing procedures are described in In the data processing for the signals of three times the wavelength, there was an unexpected decrease of the signal amplitude near the frequency of 10~15 kHz in the frequency domain, as shown in Finally, the surface-wave transmission ratio, A reliable frequency range for the surface-wave measurements was determined based on the signal consistency (SC) index computed using Equation (6). The frequency domain data had a spectral line spacing (frequency resolution) of 588 Hz. The calculated SC index values are shown in The effects of the crack depth on the obtained time domain signals for the mortar specimens are shown in From the results of The experimental results of the normalized transmission ratio versus the normalized crack depth presented similar trends to the theoretical solutions, but the differences between the experimental and theoretical results were generally considerable . When thFrom the above discussions, the relationship between the normalized transmission ratio and the normalized crack depth seems inadequate for the purpose of the estimation of concrete crack depth. Kee and Zhu  have notAlthough the surface-wave transmission ratio is sensitive to crack depth, it is also dependent on the frequency of waves  and, morThe repeatability of the measurement of the surface-wave spectral energy transmission ratio for the purpose of crack depth estimation is examined by typical statistical analysis. The spectral energy (SE) for each specimen (having a given mixture type and crack depth) was measured twenty-five times, and the spectral energy transmission ratio (SETR) for each cracked specimen was determined by dividing the SE value for the cracked specimen by the average of twenty-five SE values for the uncracked specimen of the same mixture type. R2) of the logarithmic regression curves for all the three mixture types are higher than 0.97  versus the crack depth in han 0.97 . Furtherd (mm) isFinally, a surface-wave based model for the estimation of crack depth in concrete is proposed based on the experimental SETR data, ignoring the effects of concrete mix proportions. When all the SETR data for the three mixture types are plotted together, the best fit correlation between the surface-wave SETR and crack depth R2) of this regression model is approximately 0.95. It should be noted that this simple single-variable model is capable of taking into account a wide frequency range of waves, and is independent of the mix proportions of concrete.The coefficient of determination  is validated using the root mean square error (RMSE) analysis for the twenty-five sets of surface-wave data collected from each specimen. The RMSE divided by the real crack depth in each specimen  is less than about 2.4 mm. Therefore, it is concluded that when this testing configuration is used, the proposed spectral-energy based model and associated techniques have a promising potential toward practical applications for the assessment of crack depth in concrete structures. Additionally, further studies are needed to examine the applicability of the proposed model on real cracks developed under various loading conditions. Finally, when all the mixture cases are considered together (shown in the last column of (1)The surface-wave transmission ratio constantly decreased as the crack depth increased, for all the different mixture types throughout the measured frequency domain. However, the decreasing rate of the surface-wave transmission ratio was dependent on the wave frequency.(2)Both the presence of coarse aggregate and the strength of concrete had negligible influences on the propagation and transmission of surface waves across simulated cracks of various depths in concrete. This confirms the surface-wave technique combined with the self-calibrating test scheme for applications to concrete structures made of a variety of mix proportions.(3)The relationship between the normalized transmission ratio and normalized crack depth obtained from the measured surface-wave data showed similar trends to the theoretical solutions proposed by Angel and Achenbach . However(4)The measured surface-wave spectral energy had a strong inverse correlation with the crack depth for all the different mixtures. The variation of the spectral energy transmission ratio (SETR) was reasonably small in all the specimens with different mixture types and crack depths, so that the SETR measurement of surface waves is deemed to be reliable with high statistical confidence.(5)A model for the estimation of crack depth in concrete is proposed based on the measured surface-wave SETR data, which assumes a semi-log correlation between the SETR and crack depth. The coefficient of determination of the proposed model was approximately 0.95, and the RMSE values were relatively small, compared with the test data. This simple single-variable model is capable of taking into account a wide frequency range of waves, and is independent of the mix proportions of concrete, but has a likely upper limit of crack depth of 55 to 60mm.In this study, nondestructive surface wave tests were conducted on lab-scale concrete specimens with varying mix proportions and discontinuity  depths to better understand the effects of concrete properties and crack depth on surface-wave transmission, and, finally, to develop an accurate and practical model for the estimation of crack depth in concrete. The conclusions presented here are based on the test results obtained from simulated cracks  with well-defined tips and clear opening faces along the depth. Future research efforts will explore more practical conditions involving real cracks of various configurations  and varying test configurations . The findings and conclusions of this study are summarized as follows:


This paper aims to study the effectiveness of adding waste polypropylene fibers into recycled aggregate concrete (RAC) on shrinkage cracking. The influences of fiber properties (length and content) on the shrinkage performance of RAC are investigated. Firstly, through the plat-ring-type shrinkage test and free shrinkage test, both of the early age and long-term shrinkage performance of waste fiber recycled concrete (WFRC) were measured. Then, X-ray industrial computed tomography (ICT) was carried out to reflect the internal porosity changes of RAC with different lengths and contents of fibers. Furthermore, the compressive strength and flexural strength tests are conducted to evaluate the mechanical performance. The test results indicated that the addition of waste fibers played an important role in improving the crack resistance performance of the investigated RAC specimens as well as controlling their shrinkage behaviour. The initial cracking time, amount and width of cracks and shrinkage rate of fiber-reinforced specimens were better than those of the non-fiber-reinforced specimen. The addition of waste fibers at a small volume fraction in recycled concrete had not obviously changed the porosity, but it changed the law of pore size distribution. Meanwhile, the addition of waste fibers had no significant effect on the compressive strength of RAC, but it enhanced the flexural strength by 43%. The specimens reinforced by 19-mm and 0.12% (volume fraction) waste fibers had the optimal performance of cracking resistance. The quantity of construction and demolition waste (C&DW) is being produced annually around the world , which aAmple researches reported that the old mortar particles with relatively high porosity and low strength ,14,15,16There are varieties of fibers can be mixed in the RAC, such as polymeric fibers, steel fibers, natural fibers, etc. . Akça etFrom the environmental viewpoint, adding the waste fibers into RAC is promising to improve its performance and to reduce potential pollution sources. As a combination type of green concrete, it can be reused for waste fibers and construction waste. Waste fiber recycled concrete (WFRC) not only promotes the application of recycled concrete but also is beneficial for environmental protection. Furthermore, to take economic efficiency into consideration, the utilization of waste fibers in structural concrete manufactures is meaningful to minimize the costs of fibers. Thus, it is necessary to investigate the usability of the waste fibers with RAC, especially its influence on shrinkage performance.The objective of this study is to investigate the effectiveness of adding waste polypropylene fibers into RAC. Firstly, the plat-ring-type shrinkage test is conducted to study the shrinkage cracking performance under the restrained conditions. Meanwhile, the free shrinkage test is used to measure the rate of shrinkage in the unconstrained state. Then, the X-ray industrial computed tomography (ICT) is carried out to reflect the internal porosity of RAC. Additionally, the compressive strength and flexural strength were tested to evaluate the mechanical performance.In this experiment, the coarse aggregates were recycled from waste C40 concrete, which was crushed and cleaned manually. In order to remove oversize aggregates, the recycled coarse aggregates needed to be sieved before mixing. The maximum size of recycled coarse aggregates was 25 mm. Finally, the recycled coarse aggregates with a particle size of 5 to 25 mm were formed, which can be seen in 3. The gradation curves for coarse and fine aggregates are showed in In this experiment, all the fine aggregates were natural river sand produced in the Hun River. The fineness modulus of the fine aggregates is 2.7; the moisture content is 4.15%; the density is 2610 Kg/mEnd-of-life carpets (ELCs) were made into fiber segments with lengths of 12 mm and 19 mm by removing impurities, splitting and shearing. The chemical composition is polypropylene. The cement used in this experiment was ordinary Portland cement labelled P.O.42.5. The properties of compositions of ordinary Portland cement are given in 3. The waste polypropylene fibers do not absorb water. Thus, the influence of the waste fiber on the moisture content in the mixture ratio can be ignored.There are some differences in mixture design between the RAC and natural aggregates concrete. Due to the existence of old cement mortar attaching on the surface of recycled coarse aggregates, the recycled aggregates contain more voids than nature aggregates. Meanwhile, the RAC needs relatively more water to obtain the same workability as the natural aggregates concrete. According to DG/TJ 08-2018-2007 , water c3 of water was added to the RAC. After that, the slump of RAC was tested to be the same as that of NAC. The mixture proportions of concrete specimens are listed in The RAC specimens were divided into seven groups named FRC01 to FRC07, which contains different length and volume fraction of waste fibers . MoreoveThe testing devices of the plat-ring-type test consisted of the baseboard, inner and outer steel ring, and the concrete specimen which was concreting between the inner and outer steel ring. After curing for 24 h, the outer steel ring was removed to form the concrete ring specimen restrained by the steel ring. The size of the experimental facility includes that the inner diameter of the inner steel ring is 281 mm, the outer diameter is 305 mm, and the height is 100 mm. The size of concrete ring is that the inner diameter is 305 mm, the outer diameter is 425 mm, and the height is 100 mm, as detailed in For the measurement of the concrete free shrinkage, different methods have been used in different studies. Suitable devices for testing the free shrinkage of RAC were assembled referring to other studies. The specimens were 500 mm × 100 mm × 100 mm prisms. The testing equipment and specimens are shown in In order to study the shrinkage cracking behaviour of concrete specimens, plat-ring-type and free shrinkage test were employed. The testing instruments are shown in The plat-ring-type test was conducted by the ASTM C1581 . BecauseIn this experiment, in the middle of the inner steel ring of the specimen was bound to a group of strain gauges, and one group of strain gauges includes four strain gauges which are at an angle of 90 degree while the outer concrete ring was bounded to two strain gauges . FirstlyTo observe the cracking phenomenon, the specimens were placed into the constant temperature and humidity chamber at a temperature of 20 ± 2 °C and a relative humidity of 60 ± 5%. Researchers observed the outer surface of specimens to find whether cracks were appearing, and recorded the time of initial cracking. After the concrete cracks appeared, researchers used the crack test instrument b to measAs can be seen in The free shrinkage test was devised according to the ASTM C157  and GB/TThe X-ray ICT scanning system was conducted to scan the RAC specimens at different curing periods. The internal structure of each test specimen was imaged using the TomoScope HV ICT system produced by Werth Inc. . It equipped with a microfocus X-ray tube capable of attaining a resolution of 4.5 μm. The applied voltage and power were 225 KV and 280 W, respectively. The working turntable for reconstructed specimens placing and schematic diagram of the ICT scanning system can be seen from According to the scanning theory of X-ray ICT, the air void in the concrete specimen was defined as a defect. The defect could be recognized and imaged utilizing collecting and processing the density difference between air voids and aggregates or cement mortars. Thus, two-dimensional and three-dimensional images, as well as the three-dimensional parameters of reconstructed specimens, can be obtained by VG Studio Max 3.0.2. The images can be seen in Compressive strength and flexural strength were conducted in order to determine mechanical properties of WFRC. The flexural strength test was carried out with the same prismatic specimens (100 × 100 × 500 mm) after the free shrinkage tests in accordance with GB/T 50081 . Then thThe concrete produced stress when the concrete shrunk restrained by the inner steel ring, and the stress increased gradually with the development of the time. However, the outer concrete would have cracks when the stress of the inner concrete over the compressive strength at the corresponding age. The plat-ring-type test based on the cracking caused by shrinkage of concrete under constraint conditions analyzes the influence of waste fibers on the cracking performance of WFRC qualitatively and quantitatively. The shrinkage cracking performance of each ring concrete specimen is displayed in As presented in The strain at the initial cracking of the concrete and stress of the steel ring before cracking can be seen in In this paper, the maximum crack width in the circular specimen of concrete at each age was determined as one important index to evaluate the crack resistance performance of WFRC. As shown in Compared with the non-fiber-reinforced group, the widths of cracking of specimens with 12 mm waste fibers and 0.08%, 0.12% and 0.16% volume fraction in 90 days were decreased by 6.8%, 22.3% and 10.1%, respectively. The specimens with 19-mm waste fibers and 0.08%, 0.12% and 0.16% volume fraction at 90 d decreased by 15.5%, 15.5% and 2.7%, respectively; and at 150 d by 14.7%, 20.9% and 3.4%, respectively. Therefore, the RAC reinforced by 0.12% volume fraction waste fibers has the optimal cracking resistance performance.The free shrinkage test was carried out to analyse the shrinkage of WFRC under unrestrained conditions, including early shrinkage (first 72 h) and long-term shrinkage (150 d). The early shrinkage includes the autogenous shrinkage (hydration reaction) and temperature shrinkage while the long-term shrinkage includes drying shrinkage and autogenous shrinkage.The early shrinkage and long-term shrinkage of different kinds of WFRC were studied, making two specimens of each kind of WFRC and calculating the average amount of the two values. −6 and 326 × 10−6 at 24 h, which accounted for 86.1% and 89.1% of the total of 72 h, respectively. The shrinkage rate of FRC01 was 508.7 × 10−6 at 72 h, while the shrinkage rate of FRC04 was 427 × 10−6, which was 16.07% lower than that of FRC01. Also, the FRC06 had the lowest shrinkage rate at 72 h, 30.41% lower than that of FRC01.It can be seen in The X-ray ICT images were visually evaluated regarding the internal structures and porosity characters of the concrete specimens. The results of three-dimensional reconstruction and the images before and after porosity analysis were illustrated in 3, which was 36,693 mm3 less than that of the RAC specimen (FRC01). The addition of waste fibers had no significant effect on the porosity of recycled concrete. The differences of porosity among FRC01, FRC05, FRC06 and FRC07 were within ±0.6%. The specimens without fiber (NC and FRC01) contained all sizes of pores evenly from 0.01 mm3 to 200 mm3. In specimens reinforced by waste fibers , the proportions of small pores (volume < 1 mm3) were significantly increased. The volume of micropores (volume < 0.1 mm3) in FRC07 and FRC06 were 34,463 mm3 and 23,922 mm3, accounting for 38.33% and 27.89% of all, respectively. Moreover, the volumes of small pores (volume < 1) in FRC07 and FRC06 were 62,397.16 and 55,498.88, which were greater than that of FRC01, 43,688.80 mm3. Nevertheless, the volume of micropores (volume < 0.1 mm3) in FRC01 was 10,523 mm3, only 10.58% of all, while the volume of big pores (volume > 10 mm3) was 26,404 mm3, which was larger than other specimens. From the above, compared to non-fiber-reinforced RAC, the proportions of small and medium pores of fiber-reinforced RAC were larger, on the contrary, the proportions of the big pores were much smaller. Thus, the uniformity of the pores was improved by adding waste fibers. Thus, it can be concluded that the addition of the fibers can improve the pore structures in concrete and the uniformity of the distribution of materials. These also can be regarded as an explanation of the phenomenon of the addition of waste fibers can reduce shrinkage and cracking of RAC.As illustrated in Four replicate samples were tested to investigate the compressive strength of concrete. The results of compressive strength tests are shown in (1)In the early age of RAC, the growth speed of shrinkage and cracking is fast, and the growth speed slows down with the increase of curing time. The number of cracks and shrinkage rate gradually stabilize after 90 days. The early shrinkage of all specimens is consistent with the long-term shrinkage.(2)The results of the plat-ring-type test indicate that the addition of the waste fibers cannot only delay the initial cracking time of the recycled concrete but also reduce the number of cracks in recycled concrete ring specimens and the width of cracks. As to the results of the free shrinkage test, the addition of the waste fibers can decrease the early and long-term shrinkage rate of the recycled concrete effectively.(3)The results of both the plat-ring-type shrinkage test and free shrinkage test show that the cracking resistance performance of specimens reinforced by 19-mm fibers is better than that of 12 mm. The RAC reinforced by 19 mm and 0.12% (volume fraction) waste fibers has the optimal performance of cracking resistance, especially.(4)The addition of a small volume of waste fibers will not change the porosity of recycled concrete, significantly, but it can change the law of pore size distribution. Still, the addition of fibers can make the pore size of recycled concrete more uniform.(5)This paper mainly focuses on the reinforcement of RAC by adding waste fibers. Although there is slightly higher variability in mechanical properties of fibers, the addition of waste fibers has a certain effectiveness on improving the performance of concrete. After adding the waste fibers, the flexural strength of RAC was improved. When the addition of the volume fraction of the 19-mm fiber was 0.12%, the flexural strength of recycled concrete was 43% higher than that of recycled concrete without fiber. The compressive strength of the concrete whose recycled fine aggregate replacement ratio was 100% was lower than that of NAC, and the addition of fiber has no significant effect on the compressive strength of recycled concrete specimens. The air void in concrete has a negative effect on compressive strength.(6)In this paper, only one concrete mix design is considered. More mix designs can be considered in further studies.This study investigated the effectiveness of adding waste polypropylene fibers into RAC. The shrinkage performance of WFRC was measured by Plat-ring-type shrinkage test and free shrinkage test. Then, X-ray ICT was carried out to reflect the internal porosity of RAC. Furthermore, the compressive strength and flexural strength were tested to evaluate mechanical performance. Based on the above analysis, the following conclusions could be drawn:


In this study, we investigated the influence of methacryl-functionalized polyhedral oligomeric silsesquioxane (MA-POSS) nanoparticles as a plasticizer and thermal stabilizer for a poly(vinyl chloride) (PVC) homopolymer and for a poly(vinyl chloride)/dissononyl cyclohexane-1,2-dicarboxylate (PVC/DINCH) binary blend system. The PVC and the PVC/DINCH blend both became flexible, with decreases in their glass transition temperatures and increases in their thermal decomposition temperatures, upon an increase in MA-POSS content, the result of hydrogen bonding between the C=O groups of MA-POSS and the H–CCl units of the PVC, as determined using infrared spectroscopy. Furthermore, the first thermal decomposition temperature of the pure PVC, due to the emission of HCl, increased from 290 to 306 °C, that is, the MA-POSS nanoparticles had a retarding effect on the decomposition of the PVC matrix. In tensile tests, all the PVC/DINCH/MA-POSS ternary blends were transparent and displayed flexibility, but their modulus and tensile strength both decreased, while their elongation properties increased, upon an increase in MA-POSS concentration, both before and after thermal annealing. In contrast, the elongation decreased, but the modulus and tensile strength increased, after thermal annealing at 100 °C for 7 days. Tg, ca. 89 °C). Therefore, PVC is often blended commercially with various plasticizers, e.g., di-(2-ethylhexyl)phthalate (DEHP)  suggested by the simplified relationship of pure MA-POSS (44.5 wt%) + pure PVC (2.7 wt%)—again, probably because of ash formation from the reaction of MA-POSS with PVC. This result suggests that the rate of HCl emission during the first thermal decomposition procedure had decreased as a result of the presence of MA-POSS nanoparticles. The main thermal decomposition of MA-POSS overlapped with the second thermal decomposition process of PVC, making it difficult to identify, as displayed in Tg of PVC, and increase both its thermal decomposition temperature and the char yield, while providing full miscibility with PVC, because of weak hydrogen bonding in the PVC/MA-POSS blends. As a result, MA-POSS has the potential to be a suitable replacement for traditional plasticizers, e.g., DEHP, and could be used as a blood bag, to avoid the DEHP coming into contact with tissues or body fluids.Tg of the binary PVC/DINCH blend was 13.4 °C. Increasing the MA-POSS content to 5, 10, and 15 phr caused the value of Tg to decrease to 6.6, 4.7, and 2.6 °C, respectively, based on DMA analysis, suggesting that MA-POSS remains a promising plasticizer for PVC/DINCH blends. In addition, we observed transparent behavior for all the PVC/DINCH/MA-POSS ternary blends, with flexibility, even after thermal treatment through DMA analysis (see inset to To solve the problem of the lower thermal stability of PVC/DINCH blend systems compared to pure PVC, we tested the effect of adding MA-POSS nanoparticles. Td was close to 271 °C, approximately 6 °C higher than that of the PVC/DINCH binary blend. Furthermore, the char yield also increased to 17.3 wt%, 11.3 wt% higher than that of the PVC/DINCH binary blend.Tg, the modulus, and tensile strength, but increased the thermal decomposition temperature, char yield, and elongation properties, because weak hydrogen bonding existed between the C=O groups of the MA-POSS and the H–CCl units of the PVC, as determined through FTIR spectral analyses. As a result, MA-POSS appears to be a suitable candidate for replacing traditional plasticizers, e.g., DEHP, in PVC matrices.We have examined the thermal properties, miscibility, hydrogen bonding interactions, and mechanical properties of PVC/MA-POSS binary blends and PVC/DINCH/MA-POSS ternary blends. Employing DSC, DMA, TGA, and tensile tests, we confirmed that the incorporation of MA-POSS nanoparticles into the blends occurred with full miscibility; they decreased the value of


Introduction: While fever is the main complaint among pediatric emergency services and high antibiotic prescription are observed, only a few studies have been published addressing this subject. Therefore this systematic review aims to summarize antibiotic prescriptions in febrile children at the ED and assess its determinants.Methods: We extracted studies published from 2000 to 2017 on antibiotic use in febrile children at the ED from different databases. Author, year, and country of publishing, study design, inclusion criteria, primary outcome, age, and number of children included in the study was extracted. To compare the risk-of-bias all articles were assessed using the MINORS criteria. For the final quality assessment we additionally used the sample size and the primary outcome.Results: We included 26 studies reporting on antibiotic prescription and 28 intervention studies on the effect on antibiotic prescription. In all 54 studies antibiotic prescriptions in the ED varied from 15 to 90.5%, pending on study populations and diagnosis. Respiratory tract infections were mostly studied. Pediatric emergency physicians prescribed significantly less antibiotics then general emergency physicians. Most frequent reported interventions to reduce antibiotics are delayed antibiotic prescription in acute otitis media, viral testing and guidelines.Conclusion: Evidence on antibiotic prescriptions in children with fever presenting to the ED remains inconclusive. Delayed antibiotic prescription in acute otitis media and guidelines for fever and respiratory infections can effectively reduce antibiotic prescription in the ED. The large heterogeneity of type of studies and included populations limits strict conclusions, such a gap in knowledge on the determining factors that influence antibiotic prescription in febrile children presenting to the ED remains. Fever is the main complaint among pediatric emergency services . In onlyIn contrast to the above, high antibiotic prescriptions are observed in febrile children , 5. GuidAll descriptive and interventional studies published in 2000–2017 reporting on antibiotic use in children (age under 18) with fever in the emergency department were eligible for this review.We searched Embase, Medline (OvidSP), Web-of-science, Scopus, Cinahl, Cochrane, PubMed publisher, and Google scholar for the  keywords: fever, antibiotics, emergency department, children and antibiotic prescription. Initially search was performed in 2015 and updated in October 2017  of the population needed to be admitted to the ED.– Design: observational studies and randomized controlled trials with a minimum of 50 participants.– Outcome: the studies had to report the number or percentage of antibiotics prescribed.– Population: participants under the age of 18; if mixed ages, at least 20% of the population needed to be <18 years (with a minimum of 50) or age specific antibiotic prescriptions had to be presented. Studies on children with specific comorbidities only were excluded.– Fever: at least 30% of all included children needed to have fever or the reason of visit was (reported) fever.A screening by title/abstract resulted in potential eligible articles that underwent full text review. Two authors reviewed all articles; any discrepancies were solved by oral agreement between authors.To compare the risk-of-bias of all these different study designs all articles were assessed using the MINORS criteria . Zero poExtracted data included: Author, year, and country of publishing, study design, inclusion criteria, primary outcome, median (or mean when median not available) age, number of included children. Aiming to invest determinants of antibiotic prescription, we additionally extracted (if available): diagnosis, type of antibiotics, type of physicians, and type of intervention.Due to heterogeneity in participants, outcome measures, interventions and study designs, no statistical pooling but a qualitative analysis was performed . ResultsWe obtained 837 articles by literature search. Screening the full text articles excluded 97 out of 151, which leaves 52 articles for data extraction. Two additional studies were included by reference check of included studies , 16 others came from Europe, and 6 others from Canada (n = 3) (n = 2) (n = 1)  or all ages < 18 year . Antibiotic prescription was the primary outcome in 33 studies (59%). Quality and feasibility assessment of the included studies  , 36, 49, , 36, 49 (n = 1) . The sizSixteen studies (29%) were considered as high quality and 17 30%) were considered low quality. In general, observational studies did not describe sufficiently how sample size was approximated. Almost all high quality studies, except one , compared to older ones , independent of study quality Figure  3, 28, , 50, 71.None of the studies on febrile children in general compared antibiotic prescriptions between countries. In the eleven studies , 61, 71 Four studies provided data for antibiotic prescription in AOM, ranging from 88–93%. We could not determine influences of age on prescriptions. Five studies reported on antibiotic prescription in pneumonia, ranging from 69 to 93%. The study with the lowest prescription (n = 7) included both second or third generations.Nine out of 26 (35%) studies  repFive , 63, 72 Nine out of 27 studies on interventions for antibiotic prescription (32%) reported about rapid viral testing , 62, 64,Interventions with a significant effect on antibiotic reduction were guidelines and the wait-and-see prescription in acute otitis media (AOM). For this latter a significant reduction was found in four articles  , 52, 66.n = 9). Fewer antibiotics were prescribed when the RVT is positive  to reduce antibiotic prescription, but its effect is controversial.It is important to note that the high variability in antibiotic prescription observed in our systematic review differ from reported antibiotic prescriptions from literature, or websites , 73. HowLimited evidence was found for age effects on antibiotic prescriptions, potentially due to age distribution among study populations. Infants below 2 months are underrepresented in our review. From community studies, we know that pre-school children are more frequently exposed to antibiotic therapy .After exclusion of two outlier studies given their patient selection and outcome definition , 50, we Similar to studies in primary care, watchful waiting intervention seems highly effective for reducing antibiotic use in AOM at the ED . ResultsThe quality of the studies that reported about fever in general was low to moderate, with only one high quality study . SpecifiThis systematic review focuses on prescription of antibiotics in the ED setting. In many European countries, antibiotics are available as over the counter drugs as well . This isUnfortunately, we observed a large heterogeneity of the studies or had only 1 study per diagnosis group, hampering meta-analysis. Most heterogeneity is caused by specific patient selection , by study design . This also applies to the population of febrile children <36 months that constitute the majority of ED attendances.To validly estimate baseline antibiotic prescriptions in children with fever presenting to the emergency department we need observational studies including the general spectrum of febrile children. Being able to determine influences of antibiotic prescription, we should address geographical and cultural influences, differences in setting, adherence area, general patient characteristics, and descriptors of illness severity. Insight in these determinants may help to define targets for intervention to reduce antibiotic prescriptions. Next, this information will contribute to valid power calculations for intervention studies and to generalize effects to other settings.A summary of studies on antibiotic prescription in the 5 main diagnostic groups at the ED did not yield uniform outcomes. There seems to be a trend toward higher antibiotic prescriptions in younger children and for diagnoses that are more often related to bacterial infections. Delayed antibiotic prescription in children with acute otitis media and guidelines for fever/LRTI seem useful to reduce antibiotic prescriptions at the ED. However no strict conclusions can be drawn on the basis of this review because of the large heterogeneity of type of studies and included populations. This means that there is still a gap in knowledge on the determining factors that influence antibiotic prescription in febrile children presenting to the ED. A multicentre study including a wide range of countries on a general population of febrile children would be recommended to provide a valid baseline of antibiotic prescriptions in general, and influencing factors that identify targets for future interventions.EvdV was responsible for search, dataextraction and writing of the manuscript. HM, SM, and AG contributed to datainterpretation and writing of the manuscript. RO concepted the idea of the paper, supervised search, dataextraction, and writing of the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.