Bis-phenylethynyl polyhedral oligomeric silsesquioxane (bis-PE-POSS) compounds were synthesized and thermally cured yielding crosslinked materials. After curing at 370 °C, thermal decomposition occurs near 600 °C under nitrogen. These materials were synthesized by condensation of a new phenylethynyl-functional dichlorosilane onto tetrasilanol phenyl POSS, yielding two geometric isomers. After thermal crosslinking, bis-phenylethynyl POSS exhibits 5% mass loss temperatures approaching 600 °C, the highest of reported POSS compounds. Tgs) and good thermo-oxidative stability, able to withstand exposure to temperatures in excess of 300 °C while maintaining their mechanical robustness.1 A continuous service temperature of 370 °C is widely recognized as a very important technical challenge for organic matrix composites.2 Some thermosetting systems, such as polycyanurates,3,4 poly(benzoxazines),5 and phenylethynyl-endcapped poly(oligoimides)6 have approached that benchmark, but few resins possess the requisite combination of processability, mechanical properties, and thermo-oxidative stability. Those that can be utilized in service over 300 °C have finite lifetimes, especially in the presence of oxidizing species, and exhibit poor processability, requiring solvents for fiber impregnation and high pressures to promote flow. A matrix material that shows a significant improvement in thermochemical stability at high temperatures with an expanded processing window without the utilization of solvents would be a major step forward in the pursuit of next-generation resins.Various composite applications, especially in aerospace, call for polymeric matrix materials with high glass transition temperatures  crosslinking chemistry, yielding a material with a broad processing window and good thermo-oxidative stability.One of the first examples of advancement towards this goal is NASA's PETI (phenylethynyl-terminated imide) series of phenylethynyl endcapped poly(oligoimide) resins.6,10 The properties of the final material are highly modular, with the crosslink density and molecular weight between crosslinks readily tunable through the size of the oligomer or polymer between the phenylethynyl groups.9Common in high temperature thermosets, phenylethynyl crosslinking chemistry is a versatile route for the production of a variety of thermosetting materials. The robustness of this chemistry comes from the apparent cyclization of three phenylethynyl groups to form hexasubstituted benzene rings as the crosslink junctions in the final product, as well as higher order rings and other ill-defined but still olefinic structures.11 Phenyl POSS compounds have found utility as additives for viscosity modification in high-temperature polymers, imparting improved processability and thermal properties when blended into the neat polymer, with little to no sacrifice in mechanical properties.12,13Also of note for their thermo-oxidative stability, polyhedral oligomeric silsesquioxane (POSS) compounds are hybrid organic–inorganic molecules composed of an inorganic silicon oxide core with an organic corona, well studied and available with a variety of functional groups. Phenyl-substituted POSS compounds are the most thermally stable in their class, due to their high aromatic content as well as the inorganic silsesquioxane core.14 including into polyimides as pendent moieties15,16 or even as monomers in the backbone of the polymer.17,18 This sort of incorporation increases the service lifetime of the fabricated part by reducing the amount of wear experienced. When exposed to low-Earth-orbit, Kapton-like polyimides with POSS moieties incorporated into the main chain of the polymer experienced erosion much more slowly than that of the neat polyimide due to the formation of a passivating silica layer.19 Additionally, phenylethynyl-functional POSS polyimide oligomers were found to be readily crosslinkable through the standard phenylethynyl cure schedule.20 These POSS-containing thermosets showed reduced moisture uptake when compared to the control polyimide, accomplished by the inclusion of the hydrophobic silsesquioxane cage of the POSS moieties, although with a reduction in the Tg of the finished material compared to the control. A strategy was developed to design a new matrix material that combined the high temperature properties of the POSS and phenylethynyl groups without any adverse effects of moisture uptake by removing the intermediate imide linkages. Here we present a new material, bis-PE-POSS, which utilizes the hybrid POSS architecture along with phenylethynyl curing chemistry. We report the synthetic route to this compound and demonstrate its exceptional thermal stability, with 5% mass loss temperatures approaching 600 °C.There have been many efforts to covalently attach POSS to polymeric materials as well,21,22 by the preparation of the phenylethynyl dichlorosilane  of the isomers, though, are around 12–16 for the cis compound compared to only 6–10 for the trans compound  and trans isomer in (d) are zoomed in to the regions of interest. Sharp peaks demonstrate that the POSS cages retain their discrete molecular structure through the functionalization step. The chemical shift from the silicon atoms that tether the phenylethynyl groups to the POSS cage is evident at −31.1 ppm (highlighted in blue), and the shifts from the two silicon atoms that are attached to the tethering silicon (through oxygens) are evident at −78.2 ppm (red). The central silicon atoms, then, show different shift patterns depending on the isomer. Because of the high symmetry of the trans isomer, the central silicon atoms exhibit only one peak (purple). The cis isomer's central silicon atoms are in differing chemical environments, with the shifts from the two atoms opposite the phenylethynyl groups at −79.6 ppm (green), and the shifts from the atoms between the phenylethynyl groups appearing at −79.1 ppm (orange).24The cis or trans bis-PE-POSS. The crystal structures, presented in P1̄), the cis isomer is found on a crystallographic general position, while the trans isomer resides on a center of inversion. Interestingly, the structures suggest that the cis isomer belongs to the C2v point group while the trans is C2h.Single crystals suitable for X-ray diffraction were grown from concentrated solutions of benzene containing either cis-isomer showing a melting transition at 261 °C and the trans-isomer at 304 °C. The cis-isomer's lower crystallinity led to its lower melting point. The blend of the isomers exhibits two endotherms as expected. The cis-isomer showed no change in melting point in the mixture, but the trans-isomer saw a depression in melting point to 280 °C, presumably from solubilization into the cis-isomer. The compounds are free-flowing thin liquids in the melt state before cure. Both isomers and mixtures of isomers showed a cure exotherm with a maximum temperature around 379 °C. A representative exotherm is shown in Thermal studies were performed in order to ascertain the processability and thermal properties of the bis-PE-POSS compounds. Differential scanning calorimetry (DSC) showed distinct melting temperatures for the two isomers . Meltingcis isomer, trans isomer, or a 50/50 mixture of the two were cured in situ in a TGA pan with an isothermal hold at 370 °C for 1 h. The resulting cured bis-PE-POSS resin was then subjected to a ramp to 1000 °C at a rate of 10 °C min−1. In a nitrogen atmosphere, 5% mass loss occurred around 595 °C for each isomer, as well as the mixture of isomers. The char yields are also quite high, all around 77%. For comparison, a known phenylethynyl-endcapped polyimide, 6-FDA-ODA-PEPA,20 was subjected to the same thermal treatment, and shows a 5% mass loss temperature of 574 °C and a char yield of 57%. Analysis in air shows quite high degradation temperatures as well. The polyimide left no char yield after ramping to 1000 °C, but the char yields of the bis-PE POSS compounds in air were 43% for the trans isomer, 36% for the cis isomer, and 39% for the mixture, all close to the theoretical value for the mass fraction of the central inorganic cage. The carbonaceous content of the cured resin was oxidized and lost, leaving behind the nonvolatile silicon oxide portions of the resin.Thermogravimetric analysis shows the exceptional thermal stability of these compounds. TGA curves are shown in 11,25 well below that of the bis-PE-POSS. The crosslinking and increase in aromatic content in the bis-PE POSS compounds improves thermal stability compared to other POSS systems, leading to a more robust material.These compounds show an increase in degradation temperature as compared to other phenyl substituted POSS compounds as well. Octaphenyl POSS has a degradation and volatilization temperature around 450 °C and char yield of 70% in nitrogen,In conclusion, we have synthesized a phenylethynyl-functional POSS compound through a modular synthesis that shows exceptional thermal stability to temperatures approaching 600 °C. This compound is able to be utilized as a thermoset resin, and is crosslinked through cyclization of its phenylethynyl groups. This crosslinking process greatly enhances its thermal stability in comparison to high temperature polymers, and even improves on properties seen in POSS compounds with similar functionality through inclusion of the curable phenylethynyl group. This compound opens up the possibility of thermoset resins with ever greater thermal stabilities and operational temperatures.There are no conflicts to declare.RA-008-C8RA05954C-s001RA-008-C8RA05954C-s002


Veterans’ Affairs (VA) healthcare providers perceive that Veterans expect and base visit satisfaction on receiving antibiotics for upper respiratory tract infections (URIs). No studies have tested this hypothesis. We sought to determine whether receiving and/or expecting antibiotics were associated with Veteran satisfaction with URI visits.This cross-sectional study included Veterans evaluated for URI January 2018–December 2019 in an 18-clinic ambulatory VA primary-care system. We evaluated Veteran satisfaction via the Patient Satisfaction Questionnaire Short Form (RAND Corporation), an 18-item 5-point Likert scale survey. Additional items assessed Veteran antibiotic expectations. Antibiotic receipt was determined via medical record review. We used multivariable regression to evaluate whether antibiotic receipt and/or Veteran antibiotic expectations were associated with satisfaction. Subgroup analyses focused on Veterans who accurately remembered antibiotic prescribing during their URI visit.Of 1,329 eligible Veterans, 432 (33%) participated. Antibiotic receipt was not associated with differences in mean total satisfaction . However, mean total satisfaction was lower for Veterans expecting an antibiotic . Among Veterans who accurately remembered the visit and did not receive an antibiotic, those who expected an antibiotic had lower mean satisfaction scores than those who did not .Veteran expectations for antibiotics, not antibiotic receipt, are associated with changes in satisfaction with outpatient URI visits. Future research should further explore patient expectations and development of patient-centered and provider-focused interventions to change patient antibiotic expectations. Upper respiratory tract infections (URIs), frequently evaluated in outpatient visits, are mostly caused by viruses, rendering antibiotics unnecessary. Yet, a recent evaluation of US ambulatory-care visits demonstrated that 41% of all antibiotics were prescribed for respiratory illness and 51% of acute URI visits resulted in antibiotic prescriptions.The majority of antibiotic prescribing occurs in the outpatient setting. which strongly influences provider prescribing. Although patient expectations for antibiotics may be decreasing over time, a reported 50%–72% of patients expect antibiotics for URI-like symptoms. Many studies have shown increased patient satisfaction associated with antibiotic receipt; others showed no association. Studies that directly looked at patient-reported expectation for antibiotics and patient satisfaction with care found that for patients who reported expecting an antibiotic, antibiotic receipt was associated with increased satisfaction and not receiving an antibiotic was associated with decreased satisfaction.Many providers perceive that patients desire or expect antibiotics, suggesting that there are differences in what drives Veteran visit satisfaction compared to non Veterans. To our knowledge, no studies have evaluated the association of satisfaction with clinical care and antibiotic receipt for URIs in outpatient Veteran clinics. Here, we present findings from a cross-sectional study using survey data and data extracted from electronic medical record (EMR) review assessing whether receiving an antibiotic prescription during URI clinic visits was associated with Veteran satisfaction and whether Veteran self-reported expectation for antibiotics for URI was associated with Veteran satisfaction.Only 1 study specifically included Veterans and Veterans’ Affairs (VA) facilities and demonstrated that receiving an antibiotic at an emergency department visit for URI was not associated with a difference in reported satisfaction for Veterans but was associated with increased satisfaction for non Veterans, From March to May 2020, eligible Veterans were screened. Veterans who had died since their URI visit, had documented dementia, or had not been evaluated in-person were excluded. Veterans who asked to be removed from the study after receiving a survey were also excluded.This cross-sectional study included adult Veterans (aged ≥18 years) evaluated for URI or acute bronchitis at 18 VA Tennessee Valley Healthcare System (TVHS) outpatient clinics from January 1, 2018, through December 31, 2019. These Veterans were previously identified as part of a quality improvement project at VA TVHS. The PSQ-18 is a validated 18-item survey that assesses patient satisfaction with clinical care using a 5-point Likert scale  and yields a total score of 18–90 points, with higher scores indicating higher overall satisfaction. Secondary outcomes included satisfaction by PSQ-18 subscales. The survey addressed 7 subscales of satisfaction: general satisfaction, technical quality, interpersonal manner (of the provider), communication, financial aspects, time spent with the doctor, and accessibility and convenience. The PSQ-18 has been used in >50 published studies, often to evaluate different aspects of outpatient clinical care.The study’s primary outcome was total satisfaction with URI visit measured by the Patient Satisfaction Questionnaire Short-Form (PSQ-18) .We also evaluated the association of Veteran expectation for antibiotics for URIs with URI clinic visit satisfaction in all participants and separately in the subgroup of Veterans who accurately remembered the URI clinical visit.1).The study survey included the PSQ-18 and additional items assessing patient expectations for antibiotics for URIs, perception of how antibiotics affected their URI clinical visit satisfaction, whether the Veteran remembered the specific URI clinical visit, and whether the Veteran remembered whether an antibiotic was prescribed. The survey also included a prompt informing the Veteran that he or she had been evaluated in a VA primary care clinic and diagnosed with URI or acute bronchitis between January 2018 and December 2019 and listed examples of URI-related symptoms for which they may have been evaluated. The Veteran was then asked to think about that visit while answering the survey . This study was approved by the VA TVHS Institutional Review Board. and all scores were adjusted to the scale of 90. We included all surveys with at least 1 item answered. Satisfaction subscales consisted of either 2 or 4 items per scale. All skipped or missed items for each subscale were excluded, and an average score was calculated, ranging from 1 to 5. We excluded Veterans who skipped all items in a particular subscale from that subscale analysis.According to PSQ-18 scoring instructions, skipped items were excludedEMR reviews were conducted separately to ascertain patient and visit-specific data, including whether the patient was prescribed an antibiotic. The review team comprised 4 independent EMR reviewers: 1 who reviewed EMRs throughout the project, 1 who performed EMR reviews only initially, and 2 who performed EMR reviews later in the project. All reviewers were aware of the study hypothesis at the time of EMR extraction. Percentage agreement was calculated among concurrent reviewers at 2 separate times due to the change in reviewers. We collected the following patient clinical data: status for smoking, congestive heart failure (CHF), pulmonary disease, and immunosuppression, estimated glomerular filtration rate (eGFR), and documented insurance status. We also collected the following visit and provider covariate data: season of clinic visit, clinic site, provider, provider type, whether medications for URI symptoms were prescribed, and whether the patient revisited or communicated with the clinic for the same complaint within 1 week (Supplementary Table 2).Covariates that could affect prescribing of an antibiotic for URI and/or the Veteran’s satisfaction with clinical care were assessed and included in adjusted models. We collected data on Veteran sex, age, and home-county 2013 National Center for Health Statistics (NCHS) urban–rural classification, based on the Office of Management and Budget’s metropolitan statistical areas.t test for continuous and binominal variables and a 2-sample proportion test for categorical variables to assess whether the difference in means between those that did and those that did not receive an antibiotic was different from zero, and we computed 95% confidence intervals (95% CI) around the estimated difference.We performed a  to derive values for missing eGFR. We generated 10 data sets using sex, age, NCHS urban–rural county classification, smoking status, chronic pulmonary disease status, CHF status, immunosuppressed status, documented insurance status, days from visit to survey response, receipt of a nonantibiotic prescription for URI symptoms, and return visit or call within 1 week for imputation.For the primary analysis of satisfaction associated with antibiotic receipt and for the secondary analysis of satisfaction associated with Veteran expectation for an antibiotic, we used multivariate multiple imputationWe applied multivariable linear regression to assess difference in total satisfaction associated with receiving compared to not receiving an antibiotic, adjusted for confounding patient and clinic characteristics listed above in addition to eGFR, provider type, and Veteran self-reported expectation, clustered by clinic site.To evaluate differences in mean satisfaction subscales among those who received an antibiotic compared to those who did not, we used the Wilcoxon rank-sum test. We used multivariable linear regression to assess the association of Veteran expectations for antibiotics for URI on total visit satisfaction. Therefore, to assess for potential effect modification, we evaluated satisfaction using age groups, stratified by quartiles, substituted for age in the multivariable linear regression.Prior studies evaluating patient satisfaction with clinical visits found that older age groups had increased satisfaction.We mailed surveys from July to September 2020, but visits occurred as early as January 1, 2018. To address potential recall bias, we calculated time from clinic visit to survey response for each Veteran. We chose single dates in July, August, and September 2020 (coinciding with mailing dates) as standard response dates, and we calculated the days from each Veteran’s clinic visit appointment to survey response. We evaluated difference in days from initial visit to survey response among those who received an antibiotic compared to those who did not. We also assessed difference in satisfaction based on time from visit to survey response.1). For Veterans who remembered the visit or were unsure of remembering the visit but definitely remembered receiving or not receiving an antibiotic, we compared reported antibiotic receipt to actual antibiotic receipt determined by EMR review. We calculated the positive predictive value for remembering receiving an antibiotic and the negative predictive value for remembering not receiving an antibiotic. We evaluated difference in satisfaction associated with Veterans accurately remembering the visit compared to other responders.To further address potential recall bias, we included 2 items to assess the Veteran’s memory of the visit . The final analysis included 432 Veteran responses, for a 33% response rate ; however, the percentage of physician visits was significantly lower . For Veterans who received an antibiotic compared with those who did not, the percentage who received supportive medications to address URI symptoms was higher , the percentage who called or revisited within 1 week was higher , and the mean days from clinic visit to survey response was higher  (Table Among 228 Veterans (52.8%) who received an antibiotic compared to 204 (47.2%) who did not, there was no significant difference in sex, age, urban–rural classification based on home address, percentage who smoked, had underlying pulmonary disease, CHF, or immunosuppression, mean eGFR, or percentage with documented insurance. For Veterans who received an antibiotic compared with those who did not, the percentage of nurse practitioner visits was significantly higher   compared to those who did not (66.9 points) . Additionally, there was no significant difference in any satisfaction subscale scores between those who received and those who did not receive antibiotics (Table P = .014). For Veterans aged 67–72 years and Veterans aged >72 years, compared to Veterans aged <57 years, there was no significant difference in mean total satisfaction score.After stratifying by age quartiles and adjusting for confounders, the mean total satisfaction score for Veterans aged 57–66 years was higher than for Veterans aged <57 years  reported that they remembered or possibly remembered the visit and reported that they remembered receiving or not receiving an antibiotic. The positive predictive value of the Veteran reporting that they remembered receiving an antibiotic was 95 (64.2%) of 148. The negative predictive value of the Veteran reporting that they did not receive an antibiotic was 32 (47.8%) of 67. The 127 Veterans who accurately remembered the visit (95 received an antibiotic and 32 did not) were included in subgroup analyses.P = .239) or mean satisfaction .For 127 Veterans (29.4%) who accurately remembered compared with all other 305 responders (70.6%), there was no difference in days from clinic visit to survey response . However, in Veterans who received an antibiotic, there was a significant increase in days from time of visit to survey response after adjusting for sex and age .Among those who accurately remembered, for those 95 (74.8%) who received an antibiotic compared with those 32 (25.2%) who did not, there was no difference in total satisfaction score  . The nonresponder group was younger, more often female, had fewer calls or return visits within 1 week, smoked more, had less CHF, significantly higher eGFR and fewer with documented insurance (Supplementary Table 3).Overall, 844 Veterans who did not respond to the survey were included in the nonresponder analysis, after excluding 11 Veterans due to data-processing errors. Compared to responders, there was no difference in percentage who received an antibiotic (difference, −1.4%; 95% CI, −7.2% to 4.4%;  VA clinical providers prescribe antibiotics for URIs in part because they perceive that Veterans expect antibiotics for URIs and that antibiotic prescribing affects patient satisfaction. Here, we have demonstrated that in a large, VA ambulatory clinic system, receiving an antibiotic prescription for URI was not associated with patient satisfaction unless the Veteran expected an antibiotic. For Veterans who expected an antibiotic but did not receive one, mean total satisfaction with the visit was 22% lower.Unnecessary antibiotic prescribing for URIs is high in the Veteran population. Although prior studies have assessed the effect of patient expectations for antibiotics on reported patient satisfaction for URI visits and showed similar findings, none evaluated the Veteran population. The decision to prescribe antibiotics is complex and influenced by many clinical and nonclinical factors. Nevertheless, our findings suggest that working with patients to understand what drives expectations could inform patient-focused interventions to reduce URI prescribing. Previous research has shown that it is feasible to change patients’ expectations for antibiotics for URIs.Data exploring the association between antibiotic receipt and patient satisfaction for Veterans evaluated for URI are scarce. Patient satisfaction with URI visits has been shown to be associated with receiving information or reassurance from their provider, especially for patients who did not receive antibiotics, underscoring the importance of providing resources and tools to help providers improve patient engagement, to address patients’ expectations, and to reduce unnecessary antibiotic prescribing.Additionally, communicating these findings to providers may empower them to assess and address patients’ expectations by implementing successful interventions like communications training. and nonresponder and responder antibiotic prescription rates were similar. Additionally, although there were differences in responder and nonresponder characteristics, none of the characteristics in the responders, aside from documented expectation, were significantly associated with a difference in mean total satisfaction. There was substantial time between visits and survey response for most responders, but in analyses evaluating recall bias, time from visit to survey response did not affect visit satisfaction scores or accuracy of the Veteran’s memory. Planned subgroup analyses with Veterans who accurately remembered the visit were similar to the larger responder population. This study was conducted in a single VA system; however, the system includes 18 clinics across Tennessee and Kentucky in rural and urban settings and includes both VA clinics and contract clinics, which provide care for Veterans but are run similarly to private practice clinics. Finally, these findings may not be directly generalizable to other populations outside the VA system; however, our findings corroborate previous findings in non Veterans, indicating that these findings are likely relevant to a wider outpatient population.This study had several limitations. Low response is a potential limitation; however, 33% is consistent with previously reported response ratesIn conclusion, antibiotic receipt alone does not determine Veteran satisfaction with URI visits. Patient expectations of receiving or not receiving an antibiotic were an important factor that significantly affected satisfaction scores. Further studies evaluating how best to assess, understand, and address Veteran expectations for antibiotics for URIs are needed.


This study extends the development of concretes with metallurgical sludge waste (MSW) by determining the effect of superplasticizers and air entrainment admixture (AEA). The MSW is a very fine powdery material, and in this case, it was used as a partial replacement of fine aggregate in the mixture. The reference ordinary concrete mixtures without MSW were created for evaluation. The results of concrete density, compressive strength, electrical resistivity, and rapid chloride permeability were obtained and some of them were measured continuously to determine the influence of the chemical admixtures on these characteristics over time. It was found that in general, the MSW substitution slightly lowers the mechanical and durability parameters, but MSW in combination with the chemical admixtures improves the compressive strength in comparison to the reference concrete with the addition of AEA. Sustainable development of the construction industry, and specifically the concrete industry, requires innovative and unconventional approaches . One of The aim of the whole research is to evaluate the usability and effect of MSW on the mechanical and durability properties of the final concrete mixes to create more sustainable concrete and used the waste product, which would otherwise just clutter the landfill. The MSW was considered a replacement for a fine aggregate since by its nature it resembles it. In this study, the concretes were also enriched by chemical admixtures (superplasticizer and air-entraining admixture) to determine their influence on the mentioned properties, which were measured at specific time points to properly capture their effect.The metallurgical sludge used in the research was obtained from a Polish steel producer. It consists of agglomeration sludge, blast furnace sludge, and converter sludge in different proportions. The processed MSW is a very fine powdery material consisting of grains of 0–0.25 mm in size. The chemical composition of MSW see  depends Compositions of concrete mixes are given in A “reference” mixture containing neither MSW nor other chemical additives was prepared as a base one. The “MSW” mix was prepared with the 30% fine aggregate substitution by MSW. This mix had to be enriched with a superplasticizer because MSW mixes generally have a higher water consumption. Another reference mix (“Ref + AEA”) was prepared and enriched with AEA. As the last mixture (“MSW + AEA”), a combination of the fine aggregate replacement by MSW and addition of superplasticizer and AEA was prepared.All concrete mixes and specimens were prepared and cured in the same way. The mixes were poured into molds immediately after mixing and demolded after 24 h. The storage of all samples was carried out under the same standard laboratory conditions in water storage tanks with regular water. Concreting and testing of mechanical properties were carried out at the Silesian Technical University in Gliwice; testing of degradation parameters was completed at the VSB-Technical University of Ostrava.Three specimens of every shape were cast from each mix: in the form of a cylinder (Ø100 mm × 200 mm) and a prism , R is the universal gas constant (J/K·mol), T is the absolute temperature (K), Z is the ionic valence (-), F is the Faraday constant (C/mol), ti is the transfer number of chloride ion (-), γi is the activity coefficient of chloride ion (-), Ci is the concentration of ions i in the pore water, and ρBR is the bulk electrical resistivity (Ωm).Due to the nature of the non-destructive testing of the method , it was m-factor, which describes the reduction of diffusion coefficient over time, was calculated by approximation of Equation (2) by the least squares method [cDt, is the apparent diffusion coefficient for a selected age (m2·s−1), m is the aging factor (-), cDref, is the reference diffusion coefficient (m2·s−1) in the reference time reft (years) and t is the specific time (years).The s method .(2)Dc,tThe rapid chloride permeability test (RCPT) according to ASTM C1202  was usedThe sample was prepared by cutting one of the cylinders. Throughout the test, a voltage of 60 V DC is maintained at the ends of the sample and the charge that passes through the sample is recorded. Based on the charge, the permeability of the concrete can be qualitatively evaluated. According to the standard, the following chloride ion penetration limits are defined: >4000 C = high, 2000–4000 C = moderate, 1000–2000 = low, 100–1000 = very low, <100 = negligible.Some of the experiments were performed in various time points so that the maturation of the concrete could be evaluated and some of the tests were carried out in certain time sections only. For the destructive experiment of measuring the compressive strength, three time points of testing were prepared . The other destructive RCPT test was carried out 56 days after concreting in order to assess the relationship with other tests. The measurements for the non-destructive tests (surface and bulk resistivity) were made continuously. The density of the specimens was determined only once, 28 days after concreting, with the assumption that it does not change over time. The chapter presents partial results first and then places them in the context of the time of the test.The compressive strength results are shown in The increase in strength is gradual, irrespective of the composition of the mix. Thus, MSW does not significantly improve or deteriorate the progress of the strength properties.However, the lowest value of strength was achieved by the reference concrete with AEA. In contrast, the combination of MSW and AEA can slightly increase the strength. This phenomenon is caused by the different reaction of AEA with the replacement of fine aggregate. Further evaluation of compressive strengths is presented in the following chapters together with other results. It is a material with no significant chemical activity when in contact with water. Undoubtedly, the presence of MSW makes it necessary to use more superplasticizers and/or AEA to achieve a certain effect. This is mainly physical, due to the high water demands of MS, which is much higher than sand . MSW is very fine and contains wastes absorbing water. Some chemical interactions between MSW and admixtures cannot be ruled out, but this requires further research.The diffusion coefficient at different times is a result calculated from the electrical resistivity, and it is an ideal parameter for the purpose of evaluating concrete degradation. The lower the diffusion coefficient is the higher the durability of concrete in an aggressive environment. The fundamental observation is that all concrete mixes show a decrease in the diffusion coefficient, i.e., an improvement of this characteristic, which indicates the resistance to penetration by aggressive substances. It is also possible to determine how the individual chemical admixtures or the MSW itself influence the resistance. A minimal difference can be seen in the case of the reference concretes. However, a much larger difference can already be observed in the case of MSW concretes; the resistance of the MSW concrete without AEA is higher than with AEA. However, the fundamental observation is that the initial diffusion coefficient values of MSW concretes are higher than the diffusion coefficients of the reference concretes but decrease more rapidly over time than the reference ones. Further evaluation of the electrical resistance is presented in the following chapters together with other results.The main intention of the study was to evaluate the effect of superplasticizer and AEA on the mechanical and degradation behavior of concretes admixed with partial replacement of fine aggregate by MSW. Therefore, the results were grouped according to the time of testing after concreting. Three groups were created that contain different types of results, but always include all types of concrete mixes. The first group summarizes the results 28 days after concrete preparation, which includes density, compressive strength, and bulk electrical resistivity on cylinders see .To analyze the relative influence of the fine aggregate substitution and the chemical additives alone, the relative differences to the reference mixture were calculated. Thus, the absolute values of the results for the MSW, Ref + AEA, and MSW + AEA mixes were divided by the absolute values of the reference mix. For density, the differences are minimal not exceeding −3%, which also shows the similar pore composition in the concretes. On the other hand, the compressive strength is 30% lower when AEA is added to the reference concrete. The concrete with MSW alone without the aeration admixture has a 7% lower compressive strength than the reference one and the addition of AEA further reduced the overall strength by 16%; however, this loss is not as significant as the reference mix. Electrical resistivity, which is one of the indicators of resistance to aggressive substances, shows zero difference for the reference mixtures. On the other hand, MSW mixtures show lower electrical resistivity by 13% and 21%, respectively, and thus worse resistance.The second group of results is related to the time of 56 days after concreting. It contains a larger number of experiments: compressive strength, electrical surface resistivity on a cylinder and prismatic specimen, bulk resistivity on a prismatic specimen, and RCPT see . All RCPFor the compressive strength, the differences are almost identical after 28 days from concreting. However, the relative results of electrical resistivity, which was measured by two different instruments on two different shapes of the specimen, are not the showing the same trend. Even after taking into account the possible measurement error, the same trend is observed only in the case of the MSW + AEA mix, i.e., lower electrical resistivity from 7 to 28% than the reference values.The Ref + AEA concrete also shows fluctuations on the positive axis, which may be caused by the non-uniform pore distribution over the surface of the samples. In general, the bulk measurement is more suitable for laboratory experiments and should be inclined to. Small differences in surface resistivity are often caused by the smooth surface of the sample, even if the internal structure is porous. Interestingly, the RCPT results have the same trend as the surface electrical resistivity for the Ref + AEA mixture, but also have a similar trend to the bulk electrical resistivity for the MSW + AEA mixture. From these data, one could infer the influence of the additives, which is consistent with the findings in the literature, for example .The last group of results is evaluated at 91 days after concreting, which is the time when the concrete properties are expected to stabilize. Two experiments were carried out, namely the measurement of compressive strength and bulk electrical resistivity on the cylinder see . For compressive strength, the differences are again almost the same as at the previous times. Similarly, the electrical resistivity shows almost identical results as at 28 days but differs slightly from the results at 56 days—this may be caused by the allowable error in the measurements. In general, the same conclusions can be drawn as in All concrete mixes show an improvement of parameters over time and to a very similar extent. The MSW does not have a negative effect on the progress of the degradation or strength parameters.The compressive strength of the reference concrete with AEA is the lowest, by about 30%. The strength of MSW and MSW + AEA concrete is lower by about 8% and 15%, respectively, compared to the reference concrete. Thus, AEA in combination with MSW has a lower negative impact than the addition of AEA to the concrete alone.The resistance of the MSW concrete against the aggressive substances after 91 days is about 16% lower and after 224 days is about 10% lower than the resistance of reference concrete. AEA has a slight but positive effect on the diffusion coefficient of the reference concrete. On the other hand, AEA has a negative effect on MSW concrete in terms of the diffusion coefficient, which decreases over time.The study presents the mechanical and degradation parameters of standard (reference) concrete and concrete in which fine aggregate is replaced by metallurgical sludge waste. The benefit of such concrete may be the consumption of waste material and, therefore, the creation of a more sustainable concrete mixture. Hence, it is desirable to improve, or at least maintain to some extent, similar properties as standard concrete. Some of the studied concrete mixes were enriched by air entrainment admixture to analyze its effect on the results and a superplasticizer was added to both MSW concretes. The following conclusions can be drawn from the measured data:In general, it can be concluded that the combination of 30% fine aggregate replacement for MSW together with AEA shows sufficient properties for further use in construction. In the long-term research, the parameters related to the health of humans while using this material in construction as well as other degradation properties , need to be evaluated. Studies of the effects of metallurgical sludge are at an early stage, and the issues of potential interaction of MSW with admixtures have not yet been studied in depth. The objectives of the research presented in this article were not aimed at identifying the physicochemical interactions of MS with admixtures. Concretes with MSW can make a significant contribution to sustainability by showing the possibilities of applying waste material. Future research needs to focus on the evaluation of other parameters, the financial viability of MSW in concrete, and, last but not least, health safety.


Three-dimensional printed concrete (3DPC) is a relatively recent technology that may be very important in changing the traditional construction industry. The principal advantages of its use are more rapid construction, lower production costs, and less residues, among others. The choice of raw materials to obtain adequate behavior is more critical than for traditional concrete. In the present paper a mixture of cement, silica fume, superplasticizer, setting accelerator, filler materials, and aggregates was studied to obtain a 3DPC with high resistance at short curing times. When the optimal mixture was found, metallic fibers were introduced to enhance the mechanical properties. The fresh and hard properties of the concrete were analyzed, measuring the setting time, workability, and flexural and compressive strength. The results obtained demonstrated that the incorporation of fibers (2% in volume) enhanced the flexural and compressive strength by around 163 and 142%, respectively, compared with the mixture without fibers, at 9 h of curing. At 28 days of curing, the improvement was 79.2 and 34.7% for flexural and compressive strength, respectively. The expanded selection of additives in concrete technology has led to the development of new materials and the possibility of achieving ultra-high-performance fiber-reinforced concrete (UHPFRC). This material is the product of three technologies, self-compacting concrete, fiber-reinforced concrete, and high-strength concrete , and wasUHPFRC was first developed in France in the 1990s, and, according to the Association Française de Génie Civil (AFGC) , this ceIn the present work, UHPRC mixtures were developed that could be used in shotcrete as a first step until their dosages could be used to develop additive manufacturing techniques. One of these techniques was three-dimensional concrete printing (3DPC). The challenge presented by the dosages used was that ultra-high-strength concrete is manufactured with large amounts of superplasticizer additive, whose action increases the setting time. However, to use this well-projected material for 3D printing, it was necessary to reduce the setting time, which forced the need to introduce accelerating setting additives into the mixture. This could compromise the mechanical resistance achieved with the mixture , which w3DCP is a material with numerous advantages, but it requires careful dosing. The principal advantages of its use are more rapid construction, lower production costs, and less production of residues, among others ,5.Additive manufacturing can be defined as a process that uses technology for automation. With this process, three-dimensional objects can be produced from digital models in a precise way and within a predetermined space. The first research on 3D printing in the construction and architecture industry dates back to 1995, when Pegna suggested incorporating cement-based materials when using these new technologies .Concrete printing can be used to build complex geometric shapes. The components are designed using 3D modelling software . The mixLyu et al.  noted thExtrudability measures the difficulty in the extrusion process. Fresh concrete should be delivered continuously through the nozzle. According to Ma et al. , this prBuildability measures the degree of deformation and the stability of the printed layers. The material needs to be strong enough to retain its shape and prevent layers from collapsing under its own weight and the gravitational load . IncreasThe setting time for 3DCP requires a compromise between allowing sufficient time to obtain good fluidity and extrudability and sufficient time to obtain early strength.Zhang et al.  noted thSupplementary cementing materials (SCMs) are used to enhance mechanical strength and durability performance, and they also have an influence in the fresh state ,14,15. AThe present investigation was a preliminary study that explored the use of a mixture of cement, silica fume, superplasticizer, setting accelerator, filler quartz material, and aggregates to obtain 3DPC with high resistance at short curing times. In the first part, different setting accelerators were studied to obtain an adequate setting time, in the second part we worked with the selected accelerator and studied the influence of the setting accelerator percentage on the workability of the fresh mixture and the evolution of flexural and compressive strength. Finally, in the last part of the study, metallic fibers were added to study their influence on resistance. The incorporation of fibers can also improve the bonding and connection between the different layers of placed concrete.3. Portland cement type CEM I 52.5R , which met the specification of the European standards , was use2 content higher than 98% and density between 200 and 300 kg/m3.To reduce the cement content and complement the granulometric curve for small sizes, quartz flour  was also added; the main characteristics are an SiOX-ray fluorescence analysis was conducted to determine the chemical composition of silica fume and cement, and the results are shown in Two types of siliceous sand were employed, 0.8 fraction with sizes between 0.6 and 1.2 mm and 0.4 fraction with sizes between 0.2 and 0.6 mm. The distribution company was Silicam.Sika ViscoCrete 225 P  was used as the superplasticizing additive. It is a superplasticizer powder water reducer and has a shorter absorption time. The typical dosage varies between 0.05 and 0.5% by weight of binder.Four types of liquid setting accelerators were used in the first phase of testing to study the behavior of the mixture, in order to finally determine the one that would be used in the second and third phases of the study. Centrament Rapid 500  is a chloride-free additive that provides rapid hardening without affecting workability. Sikaset-3 additive , according to the manufacturer, is capable of doubling mechanical resistance between 5 and 10 h of curing. Master X-Seed 130  is a cement hydration activator agent composed of a suspension of C-S-H nanoparticles. Finally, AKF-63  is an aqueous solution of aluminum salts.The dosage was selected following guidelines from previous studies carried out by our research group . The morAll materials were poured into the mixer machine, except for additives . The sequence and mixing time of the mixtures are shown in To determine the setting time, specifically the start of setting of the different mixtures, which occurred in the first phase of the experimental program, two European regulations were taken as reference, UNE-EN 196-3  and UNE-Various investigations have reported that the workability varied depending on the time when the test was carried out ,23. In tThe mechanical strength of 40 mm × 40 mm × 160 mm prismatic mortar specimens was determined according to the normalized standard . SamplesThis section is divided into three subsections; the first part describes the selection of setting accelerator, and the other two parts focus on the chosen additive. The selected percentages of setting accelerator were 1 and 2%, with respect to the weight of cement. The setting accelerator with the shortest initial setting time was AKF-63; this type of additive with aluminum salts was very effective, so it was selected as the setting accelerator for use in successive sections. Kim et al. suggested that aluminate-based activators reacting with cement minerals exhibit fast setting times; they obtained an initial setting time of around 10 min . Other aBefore measuring the workability values, we evaluated the initial setting time of the mixture using smaller quantities of setting accelerator; the values obtained were 16 and 13 min for 0.5% and 1.0% and 1.5%, respectively. The values of the diameter obtained in the flow table were measured at different times. This time value was a previously defined variable representing the period from the end of the mixing process to the exact moment of raising the cone. After this time, the diameter of the stabilized biscuit was measured in millimeters, as shown in The evolution of the diameter values with time for the three percentages of setting accelerator and the mixture without setting accelerator is represented in As can be seen in The values obtained in this study were lower than those obtained by other authors as ideal values to obtain good buildability. Tay et al.  reportedFor future research, the use of other supplementary materials such as fly ash (FA) should be explored, which has demonstrated its ability to increase workability. Liu et al.  reportedThe study of the mixture in the fresh state, through studies in rheometers, could also be performed to find better dosages for use in 3DCP mixtures. Panda et al.  conducteThe influence of the setting accelerator in the first hours of curing is fundamental to obtaining stability in 3D concrete. In this subsection, the resistance of mortar was measured using 1.5 and 3% setting accelerator. The values of flexural and compressive strength at curing ages of 6, 9, 12, and 24 h and 28 days are listed in The mechanical strength of 40 mm × 40 mm × 160 mm prismatic mortar specimens was determined according to the normalized standard. The loading speed for the flexural test was 50 ± 10 N/s and the compression rate was 2400 ± 10 N/s.As can be seen in the resistance results, the setting accelerator had positive effects during the first 24 h of curing. At 28 curing days, both types of resistance were very close to the results of mortar without setting accelerator.fi or Rci) and the mixture containing no additive (Rf0% or Rc0%) for each curing age tested.The beneficial effects of adding setting accelerator were higher for compressive strength than flexural strength. For both types of resistance, the 3% setting accelerator demonstrated better results. The flexural strength values of mortar with 3% additive at 6 h and 28 days of curing were 3.20 and 1.03, respectively. At 28 curing days, the effect of the additive disappeared.For compressive strength, the values for mortar with 3% additive at 9 h and 28 days of curing were 6.45 and 1.02, respectively. As with flexural strength, the contribution by the additive to improvements at long curing ages was nil.The actuation of the setting accelerator in the enhancement of resistance at short curing ages was in agreement with the references consulted ,32. In some cases, the use of setting accelerator could reduce the strength at long curing times , somethi3A and C3S at an early age. This process was quicker as the amount of setting accelerator increased. They considered that the reaction effect was effective at an early age, until 12 h.Authors such as Min et al.  suggesteThe bibliography consulted said that the application of 1–3% vol% fibers into 3DCP is applied to obtain sufficient robustness and ductility for structural applications. This reinforcement has been studied with carbon, basalt, glass, or propylene fibers, among others ,36,37.i/R0).In the last part of the present investigation, 2% of metallic fibers by volume was incorporated into the mixture containing 3% setting accelerator. The flexural and compressive strengths of the mixtures with fibers were measured at the same curing ages. The incorporation of metallic fibers enhanced both flexural and compressive strength, and flexural strength improved by a greater extent. The incorporation of fibers in 3D concrete printing is a good solution, because in this system the use of classical steel reinforcement is difficult.Hambach and Volkmer studied the use of three types of fiber in 3D fiber-reinforced Portland cement paste . They deThe results obtained in this study were promising, but this was a preliminary study in which tests were carried out in molds and not in samples obtained by 3D printing. The next step would be to test this dosage using 3D printing equipment and measure the properties of a structure made in this way. Some authors, such as Rehman and Kim , pointedWe also believe that rheology studies are essential in future investigations to know how the mixture will behave when used in 3D printing equipment. The behaviour of the fibers in the use of the equipment could also be a critical point; their use could lead to obstruction, segregation, and lack of uniformity in the distribution of them. We consider it essential to expand the study of how to improve the workability of the use of FA without excessively compromising the mechanical resistances. Since FA has a slower pozzolanic reaction than SF and this could mean a decrease in resistances in the early ages of curing.The main conclusions of the presented investigation are as follows:-Mortars with fast setting start were achieved, specifically in a time of 10 min.-The loss of workability over time was pronounced due to the high reactivity of the setting accelerator used.-The percentage of setting accelerator had an influence on the flexural and compressive strength, mainly at short curing ages, but no negative effects at longer curing ages.-With the inclusion of metal fibers, flexural strength of more than 23 MPa and compressive strength of around 76 MPa at 24 h of curing were obtained.


Danio rerio) disease model for Bloom syndrome, a recessive autosomal disorder. In humans, this syndrome is characterized by short stature, skin rashes, reduced fertility, increased risk of carcinogenesis, and shortened life expectancy brought on by genomic instability. We show that zebrafish blm mutants recapitulate major hallmarks of the human disease, such as shortened lifespan and reduced fertility. Moreover, similarly to other factors involved in DNA repair, some functions of zebrafish Blm bear additional importance in germ line development, and consequently in sex differentiation. Unlike fanc genes and rad51, however, blm appears to affect its function independent of tp53. Therefore, our model will be a valuable tool for further understanding the developmental and molecular attributes of this rare disease, along with providing novel insights into the role of genome maintenance proteins in somatic DNA repair and fertility.RecQ helicases—also known as the “guardians of the genome”—play crucial roles in genome integrity maintenance through their involvement in various DNA metabolic pathways. Aside from being conserved from bacteria to vertebrates, their importance is also reflected in the fact that in humans impaired function of multiple RecQ helicase orthologs are known to cause severe sets of problems, including Bloom, Werner, or Rothmund-Thomson syndromes. Our aim was to create and characterize a zebrafish ( BLM; [E. coli RecQ protein [Bloom Syndrome  is a rare monogenic autosomal recessive disorder . The defBLM; ) respons protein , 6.RecQ homologs are evolutionarily conserved proteins involved in a variety of genome integrity maintenance mechanisms . BLM itsRECQL1, WRN, BLM, RECQL4, and RECQL5) have a single zebrafish ortholog each  and differentiation (SDiff) in zebrafish, two processes that are still not fully understood (for reviews see: –13). UnlIrrespective of their eventual sex, zebrafish larvae initially develop a “juvenile ovary” giving rise to early oocytes , 17. TheAn additional feature of zebrafish sex is its reliance on primordial germ cells (PGCs) and, subsequently, gonadal germ cells (GCs). These stem cells are specified in the embryo and migrate into the gonadal ridge during the early development (for review see: ), where The initially unimodal distribution of PGC numbers among individuals shifts to a bimodal one during early development in fish due to their differential amplification between the two sexes: larvae with high and low GC counts being prospective zebrafish females and males, respectively . Experimrad51 [tp53, a central gene in apoptotic regulation [Interestingly, zebrafish genes primarily involved in genome maintenance have also been linked to SDiff. Knockout of genes associated with the Fanconi anemia (FA) pathway leads to complete or partial male bias, while masculinization can be observed in homozygous mutants for rad51 –32. Thisgulation , 31, 33.blm loss-of-function affects both somatic and germ line cells, and Blm is necessary both during exponential proliferation of GCs in females and during meiosis in males. We also find that the blm phenotype is not rescued by the impairment of tp53.Here we show that in zebrafish blm ortholog is located on chromosome 18  using CRISPR/Cas9 by targeting the fourth exon. We were able to isolate a small indel that results in a premature stop codon (p.Thr101Leufs*4) and a severely truncated protein . Immunostaining for the phosphorylated H2A.X histone variant γ-H2AX, a marker of double-stranded DNA breaks (DSBs) did not reveal differences between blm−/− embryos and their siblings at 3 days post-fertilization (dpf)  Fig. . This re mutants .Fig. 2Lo-H2AX punctae in the treated embryos  background, where the increased expression of GFP in germ cells (GCs) of the two sexes [blm−/−;Tg(ddx4:egfp) individual displayed little or no gonadal expression of the transgene at the age of one month, suggestive of testis development  fish. At this stage, lower GC numbers can be typically observed in those wild-type individuals that will eventually develop into males and higher ones in future females [blm+/− carriers, homozygous mutants had significantly reduced GC numbers compared to their wild-type and heterozygous siblings (blm+/+ (n = 14): 32.4 ± 18.3; blm+/− (n = 47): 25.4 ± 16.3; blm−/− (n = 14): 14.4 ± 9.02)  Fig. .blm and fanc mutants, we found that all blm−/− males were almost completely sterile  imaging of germ cells. In single spermatogenic cysts of wild-type and heterozygote testes we observed spermatocytes at different phases of the meiotic cell cycle Fig. ′, often led Fig. ′, a phenosophila .Here we describe and validate a novel zebrafish model for BSyn. Our new model recapitulates several features of the human disease , 3, inclBLM could affect human lifespan. Accumulation of mutations due to an inability to repair double-stranded DNA breaks that arise as a result of environmental genotoxic effects is one plausible explanation. Indeed, mutations of multiple fanc genes and rad51, all involved in DSB repair, result in an increase of cell death in zebrafish upon exposure to genotoxic agents [blm−/− mutant zebrafish . Comparpan Fig. .blm−/− mutants and blm+/− carriers during our lifespan analysis (not shown), although occasional testicular tumors have been observed.In bacteria, RecQ is required to reduce the number of illegitimate recombination events –51. In mblm−/− individuals invariably develop into males with severely compromised fertility  proliferation , or the blm/−− zebrafish compared to that of fancd1/brca2, fancj, and rad51 mutants [blm−/−;tp53/−− double mutants developed as males  is required to convert licensed crossover (CO) designated sites into bona fide COs and in him-6 mutants abnormal chromosomal segregation can be observed [DmBlm results in an excessive number of COs, nondisjunction, and aneuploidy during Drosophila meiosis as well [Blm expression is upregulated during the leptotene stage [blm−/− mutant zebrafish  are affected when these genes are mutated. Also, while the expression of blm is clearly elevated in zebrafish oocytes, recql4 has a similar expression pattern  [Wild-type (AB), and p53M214K  mutant zx4:egfp)  backgroux4:egfp) , 66. AllA detailed description of CRISPR-based mutagenesis, fertility assays, and genotoxic treatments can be found in Supplementary Methods.For histological examination, fish were dissected and their testes were fixed by a fixative containing 4% paraformaldehyde. The samples were embedded using JB-4 resin  as described in the manufacturer’s protocol. About 2–5-μm-thin sections were made by rotation microtome and stained with Toluidine Blue. Sections were photographed using a Zeiss Axio Imager microscope system.For immunostaining we used the anti-Sycp3-rabbit , anti-Caspase-3-rabbit  and anti-γ-H2AX-rabbit  primary antibodies in combination with anti-rabbit-Alexa488  secondary antibody. Nuclei were stained with TO-PRO-3 . Larvae stained with anti-γ-H2AX were imaged under a Zeiss Axio Imager M2 using an EC Plan-NeoFluar 10 × 0.3 objective, and a Colibri 7 LED light source.2 in 0.1 M cacodylate buffer. Post-fixation was performed with 1% ferrocyanide-reduced osmium [For electron micrography we fixed the samples using 3.2% PFA, 0.2% glutaraldehyde, 1% sucrose, 40 mM CaCld osmium  and sampA detailed description of in situ hybridization, PGC quantification, and image processing can be found in Supplementary Methods.Supplemental InformationCDD Checklist fileEmail confirmations for the change in the author list compared to the original submission.