Urinary tract infections (UTIs) are associated with negative pregnancy outcomes and are treated with antibiotics. Although beneficial, antibiotic use causes antimicrobial resistance (AMR), and therefore their use needs to be carefully balanced. Antimicrobial guidelines are developed to facilitate appropriate prescribing of antibiotics. This study assessed antibiotic prescribing for UTIs in pregnancy against the National Institute for Health and Care Excellence (NICE) guideline NG109. Fifty antibiotic prescribing records dated from 1st October 2018 to 1st July 2019 were identified from three London-based GP practices. The results show that a mid-stream sample of urine, which is important for the review and tailoring of antibiotic treatment, was collected in 77.6% of cases. Prescribing the first-line antibiotic is important for adequate treatment and good antimicrobial stewardship and results show that 44% of prescriptions were for the first-choice antibiotic. Most prescriptions (56%) were for a second-line or non-recommended antibiotic. Providing self-care advice is key to empowering pregnant women in managing their own health but only 16% of records documented provision of self-care advice. This study highlights important areas of concern in the management of UTIs in pregnancy. However, due to the retrospective design, future work is needed to evaluate the role of AMR in the prescriber’s treatment decision-making process. Urinary tract infections (UTIs) are caused by bacteria that colonise and infect the urinary tract. The infection commonly causes symptoms such as increased frequency of urination and burning pain when passing urine . More seUTIs are caused by bacteria and therefore antibiotic treatment is usually required to eradicate the infection. Asymptomatic infections in non-pregnant adults should not be medically treated, unless they are undergoing genitourinary surgery, whereas treatment of symptomatic UTIs consists of taking a short course of an antibiotic  such as While antibiotics are highly effective at treating UTIs, they are also associated with antimicrobial resistance (AMR), which is a global health threat. AMR is the term used to describe the evolution of microorganisms to develop characteristics that make them resistant to antimicrobial treatment . AntibioPrimary care antibiotic prescribing during pregnancy has been studied in the UK and shows that UTIs accounted for the highest proportion of antibiotics in pregnant women . The NatA midstream urine sample (MSSU) is obtained and sent for culture before antibiotics are taken.First choice antibiotic: nitrofurantoin 100 mg modified release twice a day (or 50 mg four times a day) for 7 days.If no improvement within 48 h or if first line is unsuitable:Second choice: Amoxicillin 500 mg three times a day for 7 days or cefalexin 500 mg twice a day for 7 days. The choice of antibiotic prescribed is reviewed based on culture results and changed as appropriate to a narrow spectrum antibiotic.Provision of self-care advice on managing pain and maintaining adequate hydration.The GP practices that were included in this study are part of a group in London that provide primary care services in the community. Three practices from this group were sufficient to achieve the required sample size. Collectively, the three practices have a total of 16 GPs, a team of pharmacy professionals and approximately 35,000 registered patients  from a rA data collection tool was designed to collect demographic, clinical and treatment data from the medical notes. © GP prescribing software and trained on accessing patient medical notes prior to data collection. A search was conducted to retrieve medical notes of pregnant women using the read code for ‘pregnancy’, which was then combined with a search for antibiotics that are normally used for UTIs in the UK, regardless of pregnancy status. These antibiotics include nitrofurantoin, amoxicillin, cefalexin, which are recommended for UTIs in pregnancy, and trimethoprim, co-amoxiclav, fosfomycin and pivmecillinam, which are not recommended but can be used to treat UTIs in non-pregnant cases. Data were collected in July 2019 and the search criteria were limited between the dates of 1st October 2018 to 1st July 2019 to correspond with the publication of the NICE guidelines. The medical notes were examined to confirm that the antibiotics were for the treatment of a UTI during pregnancy. The medical notes were also used to establish the appropriateness of deviating from the guidelines’ recommendation, e.g., the medical notes were consulted when a second line antibiotic was prescribed to determine whether it was because of contraindications to the first-line choice. Information from the medical notes was then documented on the data collection tool. Each of the 50 individual records were assigned a number to prevent identification and protect the anonymity of patients. The results were collated on Microsoft Excel® and are presented using descriptive statistics which summarises the proportion of prescriptions that met each standard as a percentage. FG was given an induction of the SystmOneThe target sample size for the study was to assess fifty patients’ records, which was achieved through consecutive sampling of data from the three GP practices. The records were reviewed, and information was recorded using the data collection form. The mean age of the women was 31.1 years (±4.3) and there was a range of ethnicities attending the practices, as seen in A mid-stream urine sample (MSSU) was collected before antibiotics were prescribed in 38/49 (77.6%) of cases. An MSSU was not collected in 11/49 (22.4%) of instances and documentation was unclear in 1/50 (0.02%) prescriptions. First choice antibiotic: nitrofurantoin 100 mg modified release twice a day (or 50 mg four times a day) for 7 days.Second choice: Amoxicillin 500 mg three times a day for 7 days or cefalexin 500 mg twice a day for 7 days.If no improvement within 48 h or if first line was unsuitable:Nitrofurantoin is the first choice of antibiotic according to the NICE guidelines unless there is a known contraindication to it—for example, the woman is in the third trimester of pregnancy or is allergic to nitrofurantoin. Nitrofurantoin was prescribed in 19/50 (38.0%) cases. Amoxicillin and cefalexin are the second-choice antibiotics which should be used if nitrofurantoin is contraindicated. These two antibiotics were prescribed in 27/50 (54.0%) of cases. Assessment of the medical notes and culture results revealed that 3/27 (11.1%) were prescribed amoxicillin or cefalexin because nitrofurantoin was contraindicated, therefore these were deemed as appropriate and meeting the guidelines. Trimethoprim and co-amoxiclav were two antibiotics which are not recommended for UTIs in pregnancy but were prescribed in 4/50 (8.0%) of cases. Therefore, the overall proportion of prescriptions that met the guidelines in terms of the first choice for empirical antibiotic therapy was 22/50 (44.0%). The proportion of prescriptions which are included in the guidelines for UTI treatment but are not the recommended as first choice was 24/50 (48.0%). The proportion of prescriptions which did not meet the guidelines completely was 4/50 (8.0%). The antibiotics prescribed according to the trimester of pregnancy can be seen in The dose and frequency of the antibiotic were according to the guidelines in 38/46 (82.6%) of prescriptions whereas 8/46 (17.4%) were prescribed a dose that did not meet the guidelines, as shown in The NICE guidelines recommend a seven-day course of antibiotics in pregnancy and 32/50 (64.0%) complied with this recommendation whereas 18/50 (36.0%) had a shorter duration (3 or 5 days) prescribed. Overall, 25/50 (50%) of antibiotic prescriptions did not meet the NICE guidelines either in terms of the choice of antibiotic and/or the dose or treatment duration that was prescribed. This standard was considered to have been met if the medical notes mentioned provision of any advice on analgesics and/or emphasized maintaining adequate hydration. Self-care advice was provided in 8/50 (16.0%) occasions, but there was no documentation for the provision of self-care advice in the medical notes for 42/50 (84.0%) records.Clinical data on the allergy status, whether the UTI was symptomatic or asymptomatic and the trimester of pregnancy were also collected. There were 5/50 (10.0%) instances where women were allergic to antibiotics, which included beta lactams and trimethoprim. Symptomatic infections accounted for 38/50 (76.0%) of UTIs treated, whereas asymptomatic infections occurred in 7/50 (14.0%) cases. The type of infection was not documented in 4/50 (8.0%) of cases. Due to screening for asymptomatic bacteriuria in the first trimester , it was The study assessed 50 antibiotic prescriptions for UTIs in women who were pregnant. The women were from a range of ethnic backgrounds and at various stages of pregnancy in terms of trimesters. The following discussion highlights important criteria where the prescribing of antibiotics for UTIs in pregnancy did not meet the NICE antimicrobial guidelines for lower UTIs and the potential implications of deviating from recommended practice. These criteria correspond to the audit standards and include the collection of a MSSU, the choice of empirical antibiotic, the duration of the course and the provision of self-care advice.The NICE guideline recommends the collection of a MSSU sample to test the susceptibility of the causative bacteria prior to the use of antibiotics. Culturing a MSSU sample is important as it can not only confirm the diagnosis of a UTI but also allows for the review and tailoring of the treatment by ensuring that the prescribed antibiotic is effective based on the antibiotic sensitivity of the causative organism . EmpiricE. coli resistance globally [Nitrofurantoin is the first-choice antibiotic recommended by NICE as well as the European Association of Urology . It is tglobally . Due to The most concerning antibiotic prescriptions identified in this study were trimethoprim and co-amoxiclav. These are problematic because trimethoprim is a folate antagonist and unsafe in pregnancy, and short courses of co-amoxiclav have low effectiveness for treating UTIs . The higThe duration of antibiotic treatment in pregnancy is recommended to be seven days compared with three days in non-pregnant women. The results show that the course length was not long enough for 36% of prescribed antibiotics. There is no concrete evidence to suggest that a seven day course of antibiotics is essential ,30 and tProvision of self-care advice is a criterion where there was very low compliance with NICE guidelines. Comprehensive self-care advice includes several hygiene behaviours such as drinking adequate water, avoiding delay to use the toilet and wiping the genital area from front to back. However, in this study, self-care measures incorporated advice on suitable painkillers and emphasis on maintaining adequate hydration. Previous research shows that women require and value advice given by their GP for pain management in cystitis . The resStudies exploring the perceptions of women who experienced UTIs in pregnancy have shown that they were concerned but uncertain on how to tackle antimicrobial resistance ,37. One The data were collected retrospectively by searching through patient records and using consecutive sampling to identify women who had been prescribed antibiotics in pregnancy. Although the search was conducted in consultation with an experienced user of the GP prescribing software, it is possible that some records were missed due to the way patients’ details are recorded and read codes assigned in the system. Inconsistency between the provision and documentation of self-care advice has been noted in previous research , and wasThe purpose of the study was to assess the appropriateness of primary care antimicrobial prescribing for UTIs in pregnancy. The results of the study highlight two important areas of concern. Firstly, the results show that the choice of first-line antibiotic is not optimal and second-line or non-recommended antibiotics are frequently prescribed to women. Secondly, self-care advice may need to be emphasised to women who are experiencing UTI symptoms during pregnancy. In conclusion, further work is required to review antibiotic use for UTIs in pregnancy and the provision of self-care advice, to facilitate a consolidated effort to optimise antibiotic use in response to the global threat of AMR.


The transmission of sulfate ions in concrete results in formation of calcium sulfoaluminate crystals due to chemical reactions. The expansion of calcium sulfoaluminate crystals is the main cause of concrete corrosion damage. In this study, ultrasonic analysis was used to detect the modulus change of concrete due to sulfate corrosion to obtain the basic law of corrosion damage evolution. An exponential growth model was developed for the internal expansion force based on the chemical reaction rate of calcium sulfoaluminate crystallization. Then, the evolution equation of the number density of microcracks was derived based on their initiation and balance conditions. Finally, a statistical model was developed for the concrete damage evolution by integrating the volume of microcracks. It is shown that the statistical evolution model can well characterize the evolution of concrete corrosion damage. It is well-known that seawater contains a large number of ions that are harmful to concrete, among which sulfate corrosion is one of the most important mechanisms for degradation of concrete’s durability in marine environments ,2,3. ExpThe majority of the previous research on the durability of concrete structures in marine environments has focused on corrosion due to chloride ions ,7,8. SulEttringite and gypsum are the major products of sulfate attack that cause expansion of concrete, although the exact mechanism is not fully understood ,12,13. CTo accurately evaluate the service life of concrete structures under sulfate attack, researchers have proposed several damage models based on variation of the macroscopic mechanical properties of concrete structures. To develop the STADIUM (stands for Software for Transport and Degradation In (Un)saturated Materials) model for sulfate corrosion, Marchand et al.  evaluateIn contrast, few reports have been published on the damage evolution of microcracks due to sulfate attack. Microcracks generated by corrosion can be expanded and converged until concrete failure. In addition, macro-damage in materials generated by accumulation of micro-damages may have a catastrophic consequence. In this study, the evolution of corrosion damage of concrete due to sulfate attack was investigated by statistical method, in which the effect of chemical reaction rate was taken into account. Then, a statistical evolution model of corrosion damage of concrete was developed. Results showed the proposed model can well describe the characteristics of corrosion damage evolution.4AH13 and q is the stoichiometric weighted coefficient of the sulfate phase; γi (i = 1–3) denotes the proportion of each aluminate phase to the total aluminate content.The chemical reaction takes place during diffusion of sulfate ions in concrete. The main chemical process includes :(1)CH+SOThe chemical reaction rate equation can be analytically obtained from Equations (1) and (2), that is:From Equations (3) and (4) we can obtain:Usually, As shown in the first formula of Equation (2), the increase in ettringite concentration, Generally speaking, the expansive stress appears due to growth of ettringite in pores of concrete. This stress leads to nucleation and growth of microcracks in concrete materials, as observed in t of service is  perunit volume is nda.The definition given by Equation (1) means the number of cracks with length , a partial differential equation is obtained [Based on the number balance principle of microcracks between [obtained , that isSubstituting Equation (17) into Equation (18) yields:Such a first-order partial differential equation can be transformed into a first-order ordinary differential equation on the characteristic line. Then, the evolution equation of the number density of microcracks can be written as:Multiplying both sides of Equation (20) by From Equation (9), it is seen that Equation (21) can be rewritten as:Solving Equation (22) and noting If the effect of remote loads is not taken into account, the parameter To detect the evolution of corrosion damage expressed by Equation (24), concrete can be approximately regarded as a composite composed of a concrete matrix and corrosion cracks. As illustrated in E, is determined by means of the volume average, that is:V and CV are the volume of concrete and the total volume of corrosion cracks, and E0 is the modulus of concrete matrix (or concrete before corrosion).The concrete modulus after corrosion, CV/V is the volume occupied by cracks per unit volume, which is equal to the corrosion damage, D. Hence, Equation (25) can be written as:Note that Po42.5 cement, produced by Yangzhou Lvyang Cement Co. Ltd., Yangzhou, China, was applied for the preparation of test specimens. The sodium sulfate solution for corrosion was prepared manually. Analytical grade pure sodium sulfate ) was used with a molecular weight of 142.04.3 were used to determine the dynamic elastic modulus, and specimens with dimensions 10 × 10 × 70 mm3 were used for SEM tests to observe microstructures of concrete specimens.The water-to-cement ratio has a significant influence on the mechanical properties of cement mortar. Therefore, mortar specimens with different water-to-cement ratios were prepared to determine their relationships with the mechanical properties of mortar. As listed in Cement mortar specimens were kept under the environmental conditions of 20 °C and 90% humidity for 24 h and, then, were transferred to a standard curing room for 28 d after removing formworks. These specimens were evenly divided into three groups and soaked sodium sulfate [v” denotes the ultrasonic wave speed. Finally, the average value of five points was reported.The test method of the dynamic elastic modulus consists of several steps. First, a relatively complete surface of a sample was taken as a benchmark. Then, ultrasonic wave velocities at five points were measured at four points near the vertex and one point in the middle, as illustrated in The dynamic elastic modulus was measured at several intervals. The obtained results are shown in As you can see from By neglecting the effect of continuous hydration, the evolution of the concrete dynamic modulus can be determined, as shown in Based on these experimental results, the concrete damage evolution under sulfate attack can be obtained by Equation (26), as plotted in From Equation (10) and Equation (23), we have:Substituting Equation (11) into Equation (17) gives:Therefore, we can obtain:By substitution of Equations (29) and (27) into Equation (24), the expression of damage evolution can be derived under the simultaneous action of external load and corrosion factors. Considering the damage evolution of concrete only under sulfate, i.e., Here, the threshold stress It is seen that experimental results are consistent with those obtained from the damage model. When concrete specimens are exposed to sulfate attack, the internal damage evolution law of concrete is also in agreement with the model given by Equation (30). Therefore, such a modified model can be applied to characterize the internal damage evolution law of concrete.It was theoretically proven that the increase in the space occupied by corrosion cracks per unit volume is equivalent to the reduction of the concrete modulus due to corrosion. Therefore, it is reasonable to use ultrasonic technology to detect changes in concrete modulus to analyze damage evolution.(1)By combining the equilibrium equation of microcrack number density evolution and the chemical reaction rate equation, the first-order partial differential equations were derived. The corrosion damage evolution model of concrete under sulfate attack was developed by integrating the volume of microcrack number density.(2)The new corrosion damage model established in this paper is able to accurately describe the internal damage evolution process of concrete under sulfate corrosion. The analysis method proposed in this paper provides a reference for the corrosion damage analysis of other materials.


In the context of sustainable development and circular economy, the recycling of materials and the use of alternative binders which have less environmental impacts than cement are challenges for the construction sector. This paper presents a study on non-conventional concrete using recycled aggregates and alkali-activated binder. The specimens were prepared from low calcium fly ash , sodium silicate solution, sodium hydroxide solution, fine aggregate from river sand, and recycled coarse aggregate. First, influences of different factors were investigated: the ratio between alkaline activated solution (AAS) and FA, and the curing temperature and the lignosulfonate superplasticizer. The interfacial transition zone of geopolymer recycled aggregate concrete (GRAC) was evaluated by microscopic analyses. Then, two empirical models, which are the modified versions of Feret’s and De Larrard’s models, respectively, for cement concretes, were investigated for the prediction of GRAC compressive strength; the parameters of these models were identified. The results showed the positive behaviour of GRAC investigated and the relevancy of the models proposed.Ordinary cement concrete is a popular material with numerous advantages when compared to other construction materials; however, ordinary concrete is also criticized from the public point of view due to the CO To reduce the natural resource exploitation, recycling is a strategy which has been mentioned and is encouraged; on the other hand, the reduction in carbon footprint for concrete material is still a challenge. Indeed, the cement industry is one of the major sectors which generates CO2 . Th. Th29]. It is worth mentioning that due to the liquid-form of the binder , in the fresh state the alkali-activated solution “slumps” more easily than the aggregates, which causes a certain separation between the aggregate and the binder . The effThe compressive strength of GRAC and control mixture  were determined at the ages of 3, 7, 14, and 28 days in accordance with the current standard . The resFrom The effect of lignosulfonate superplasticizer on the compressive strength obtained is not significant. Similar results were observed in previous studies with other types of aggregate using geopolymer . Thus, iThe results from SEM show that the geopolymer gels have developed in the concrete specimens tested . The micThe large-size FA particles have participated in the reaction with AAS to create the geopolymer gels; however, there were still several small-size FA particles (less than 5 µm) which have not yet completely reacted  for bothFor cement concretes , the ITZ between the cement paste and the aggregate is well-known as the zone of weakness. However, for specimens tested in the present study, the ITZ is not clear, but it appears that the aggregate is densely surrounded by the paste a. It is The zooms on the geopolymer gels  show thaIn order to provide data for predicting the compressive strength of GRAC, experiments were conducted to determine the strength of geopolymer paste with an AAS/FA ratio = 0.4. The compressive strengths at 3, 7, 14, and 28 days are shown in At 28 days, the highest compressive strength was the “Mortar–standard” which had the mix proportion following the standardized cement mortar and containing the highest sand amount. These results suggest that the presence of sand improves the “skeleton” of the specimens, and therefore increased the compressive strength.t, called cf(t), is the function of the quality of the aggregates, represented by the empirical coefficient gK; the cement compressive strength at age t, called cmf(t); the water content W, the cement amount C (in mass), and the air volume aV existing in the final concrete obtained.Numerous classical models exist in the literature which propose the empirical formulas to predict the compressive strength of ordinary cement concrete. Among these models, Feret’s model is one of the most well-known thanks to its robustness . Indeed,gK is the Feret’s aggregate constant, 4.5 < Kg < 5.5 for natural aggregate.cmf(t) is the compressive strength of cement at time t.W and C is the mass of water and cement in 1 m3 of concrete.aV is the volume of air for 1 m3 of concrete.c(t)f is the compressive strength of concrete at age t.cm(t)f is the compressive strength of cement at age t (MPa).p and q are the empirical coefficients which depend to the aggregate quality.From the classical Feret’s model for ordinary cement concrete, De Larrard (1999)  has propp and q which are appropriate for the case of GRAC.The objective of this study is to seek the values of cmf(t) must be determined. The results of geopolymer pastes/mortars with AAS/FA = 0.4 (at 28 days) are presented in cmf(t) is the compressive strength of the binder matrix (cement for ordinary cement concrete), therefore, for geopolymer concrete, it is logical that cmf(t) is the compressive strength of geopolymer paste (without sand). The results of geopolymer paste specimens are presented in To apply the above Equations (2) and (3), the compressive strength of geopolymer paste 2SiO3 + FA), the classical Feret’s model is proposed to be modified by replacing C (cement) in Equation (2) by B (binder). The modified Feret’s model is described as following:For geopolymer concrete where cement is not present and replaced by geopolymer binder ; this value is comparable to the results presented in a previous study [The specific density of water us study .W was determined from the waters existing in NaOH and Na2SiO3 solution, corresponding to 107.5 kg of water in 1 m3 of concrete;The mass of water B: this parameter replaces the cement amount C in the classical Feret’s model for ordinary cement concrete. Therefore, the mass of binder B should be the sum of mass of the solid parts  in geopolymer binder in 1 m3 of concrete; this amount G corresponds to 50.8 kg Na2SiO3, 13.72 kg NaOH, and 428 kg FA, for a total of 492.5 kg. However, for geopolymer concrete, there may be differences with the ordinary cement concrete, so a coefficient bk was introduced to take into account the potential differences, so B is replaced by bGk. Indeed, as shown in the previous sections, there were still numerous FA particles which did not participate in the geopolymerization reactions, so the value of bk can vary from 0 to 1, which will be investigated in the present study.The mass of geopolymer binder gK: the classical Feret’s model for natural aggregates indicated that gK could vary from 4.5 to 5.5 . Some recent studies proposed some empirical relationships to calculate Kg from MDE  [gK obtained would be 7.7 and 6.4 for natural and recycled aggregates in the present study, respectively. These values are not logical when compared to the usual values mentioned above. For recycled aggregates with a lower quality than natural parent aggregates, the value of gK should be less than 4.5. The value of gK in the case of GRAC will be investigated in this study.The Feret’s aggregate constant on test) , which con test) . For thecmf(t) is the compressive strength of cement at time t, so for GRAC the compressive strength of geopolymer paste (without sand) is used , the values of gK identified  seem to be logical.The results obtained from the modified Feret’s model for compressive strength of GRAC at 28 days are illustrated in at 60 °C b, the exgK and bk, the model was applied for the compressive strength of GRAC at other days . g =K 3.0, b =k 0.6. Then the SRSS (square root of the sum of the squares) of the differences between the numerical and experimental results was calculated for each case of gK and bk; the values of gK and bk which provide the lowest values of SRSS were chosen. gK and bk for the case of b =k 0.6. From this figure, the best values should be g =K 3.0, because they provide the lowest values of SRSS for both cases of curing in ambient conditions and with heating treatment. Thus, the values identified are g =K 3.0, b =k 0.6. The value identified of the binder coefficient bk (= 0.6) can be explained by two reasons: first, the components in FA which participated to the polymerization reactions are 2O3Al and 2SiO [To verify the relevancy of the modified Feret’s model and to identify best values of coefficients and SiO2  which arbk was taken as the same as the value identified previously (= 0.6); only the aggregate coefficient gK varied. The best value of gK was also identified by the SRSS approach, from which a value of gK = 4.4 was identified. The comparison between the experimental and numerical results are presented in gK = 4.4) is also logical when compared to the current values of gK for ordinary concretes with natural aggregates. Indeed, as mentioned in the classical Feret’s model, the current values of gK for natural aggregates are from 4.5 to 5.5.To verify again the robustness of the modified Feret’s model and the parameters identified, the specimens of geopolymer concrete with natural coarse aggregates were manufactured and tested. These specimens had the same proportions and properties as GRAC; only the natural coarse aggregate was used in place of recycled concrete aggregates. These specimens were cured at ambient conditions. In application of the modified Feret’s model for this geopolymer concrete, the binder coefficient p and q must be determined. In a previous study, the aggregate parameters p and q were identified for natural and recycled aggregates [p could vary about from 0.65 to 1.2, and p/q could vary about from 120 to 200, respectively. In the present study, to identify the values of p and p/q corresponding to the recycled aggregate used, a parametric study was performed: p varied from 0.65 to 1.1, and at the same time p/q varied from 135 to 175. The compressive strength at 28 days of geopolymer recycled aggregate concretes was determined by applying Equation (3) and by using the corresponding compressive strength of geopolymer pastes . The results are illustrated in To apply De Larrard’s model, the parameters gregates . It was p should be about 0.75; the change in p/q does not influence significantly the compressive strength obtained. We proposed to take p/q = 175; this value will be checked for other cases.For the case of ambient curing, the experimental compressive strength of geopolymer concrete was of 29–31 MPa. From p should be around 0.75; the change of p/q does not vary significantly from the compressive strength obtained. Thus, the previous proposition of p = 0.75 and p/q = 175 is also acceptable for this case. This result is interesting because the values of p = 0.75 and p/q = 175 can reproduce the compressive strength for different cases: with or without thermal treatment during the curing, with or without using the plasticizer. It is logical that p and p/q depend only on the aggregate properties. Thus, the difference in the compressive strength obtained for GRAC is the compressive strength of the geopolymer paste. These values are also checked for other cases which means the compressive strength of GRAC at other ages. The results are presented in For the case of curing at 60 °C, the experimental compressive strength of geopolymer concrete was of 30–35 MPa. From p and q identified in the present study can be reproduced with acceptable accuracy for the compressive strength of GRAC at 3, 14, and 28 days . For the case of 7 days, the differences are more remarkable. Indeed, the model predicts a higher increase in compressive strength from 3 to 7 days (similar to the case of geopolymer paste and mortar) but the experimental results show that the strength evolution from 3 to 7 days is slower. For practice application, when compared to the modified Feret’s model, De Larrard’s model is easier because it demands fewer parameters.This figure shows that De Larrard’s model with the parameters The recycling in general and the recycled aggregate concrete are important topics which attract attention in the context of sustainable development and circular economy. The use of an alternative binder for recycled aggregate concrete is also a subject which needs to be investigated. In the present study, the geopolymer recycled aggregate concrete was studied; the effect of different AAS/FA ratios, curing temperature, LignoSulfonate superplasticizer on the workability, and the compressive strengths of GRAC were evaluated. Two empirical models were also proposed and assessed.3). This result shows the possible application in short term of GRAC.The results showed encouraging results on the use of recycled coarse aggregate (at 100% replacement) and the fly ash-based alkali-activated binder for the manufacture of concrete. The increase in AAS/FA ratio from 0.4 to 0.5 increased the slump and decreased the compressive strength of the concrete obtained; the mean change observed was about a 10% increase in slump and 10% decrease in compressive strength. It is worth noting that an economic calculation shows that the price of GRAC (with the mix design used in the present study) is really equivalent to that of an ordinary cement concrete in Vietnam  did not completely react. The results also showed that there was correct bonding between the geopolymer gels and the aggregates, which is a positive point when compared to the ITZ in Portland cement concretes.p and q have been identified for the recycled aggregates used. The results showed that both models used could be reproduced with satisfying accuracy for most of experimental results. Therefore, these models can provide useful information for the mix design and compressive strength prediction of GRAC. Further studies on the application of these models for GRAC will be interesting.Finally, the models for the prediction of compressive strength were investigated which were based on Feret’s and De Larrard’s models. For Feret’s model, several adaptations were necessary to adopt a model which was developed for ordinary cement concrete and now applied for a geopolymer concrete. For De Larrard’s model, the parameters


This study aimed to determine if sequential deployment of a nurse-led Rapid Response Team (RRT) and an intensivist-led Medical Emergency Team (MET) for critically ill patients in the Emergency Department (ED) and acute care wards improved hospital-wide cardiac arrest rates.In this single-center, retrospective observational cohort study, we compared the cardiac arrest rates per 1000 patient-days during two time periods. Our hospital instituted a nurse-led RRT in 2012 and added an intensivist-led MET in 2014. We compared the cardiac arrest rates during the nurse-led RRT period and the combined RRT-MET period. With the sequential approach, nurse-led RRT evaluated and managed rapid response calls in acute care wards and if required escalated care and co-managed with an intensivist-led MET. We specifically compared the rates of pulseless electrical activity (PEA) in the two periods. We also looked at the cardiac arrest rates in the ED as RRT-MET co-managed patients with the ED team.Hospital-wide cardiac arrests decreased from 2.2 events per 1000 patient-days in the nurse-led RRT period to 0.8 events per 1000 patient-days in the combined RRT and MET period . Hospital-wide PEA arrests and shockable rhythms both decreased significantly. PEA rhythms significantly decreased in acute care wards and the ED.Implementing an intensivist-led MET-RRT significantly decreased the overall cardiac arrest rate relative to the rate under a nurse-led RRT model. Additional MET capabilities and early initiation of advanced, time-sensitive therapies likely had the most impact. The need for rapid response systems (RRS) evolved from reports in the 1990s showing that unexpected and possibly avoidable cardiac arrests were occurring too often in hospitalized patients . An estiIn 2004, the Institute for Healthcare Improvement (IHI) began its “100,000 Lives Campaign,” which called for all United States hospitals to deploy rapid response teams . Historicardiac arrest, and unplanned ICU admission [Prior studies looking at the impacts of rapid response teams have shown mixed results. Some demonstrated a decrease in in-hospital mortality , 17 and dmission , 19.Our Institution adopted a nurse-led RRT in 2012 and after few years deployed an intensivist-led MET team in a sequentially deployed model. We sought to analyze the impact of this intervention on the cardiac arrest rates in the hospital. Our RRT and MET also co-managed complex patients who were admitted to the ICU but boarding in the emergency department (ED). There is limited data describing rapid response intervention systems in emergency departments [We specifically looked at the impact of rapid response on pulseless electrical activity (PEA) arrest. From prior review of our hospital cardiac arrest data, PEA accounts for up to 70% of hospital cardiac arrests at our institution compared to published reports of 37% in the literature . Older pBaylor St. Luke’s Medical Center (BSLMC) is an 850-bed quaternary care teaching hospital in Houston, Texas, USA with a total of 120 ICU beds. In response to the IHI “100,000 Lives Campaign,”  BSLMC inThis study was submitted to the Baylor College of Medicine Institutional Review Board (H-38687) and determined not to constitute human subjects research.During the RRT period, the RRT carried a dedicated pager and phone, and nursing staff on the hospital wards could make calls to the RRT for patient evaluation at any time based on their clinical assessments. The RRT trigger criteria were internally developed based on established criteria of patient decompensation . After rRRT deployment to the ED only occurred in the second period. The MET was activated to respond to the ED specifically for patients in respiratory failure and shock. The ED physician could also call the MET for ad hoc conditions, such as severe acidosis or unstable airway, that might require advanced critical care expertise, or very frequent bedside assessments and interventions by an intensivist. The MET would typically call the RRT to provide nursing-level ICU support. The RRT nurses would, for example, set up pressure lines and titrate vasoactive medications. The MET goal was to assess all consults within 10–20 minutes of the initial activation. Patients in the ED who were determined to meet ICU admission criteria continued with MET management until transferred to the ICU.Prospective data was collected for administrative operations of the rapid response service and entered into a database by the rapid response data manager. Cardiac arrest data were extracted and analyzed from the code sheets by a data abstractor on a weekly basis. To triangulate accuracy, the number of cardiac arrest alerts were correlated with the number of overhead code pages. Specific cardiac arrest rhythms were determined based on information from cardiac arrest sheets and notes. Cardiac arrest episodes were defined as complete cessation of circulation requiring cardio-pulmonary resuscitation (CPR). Demographic and hospital mortality data were extracted from the hospital electronic database system.Data were analyzed using SPSS . The Fisher exact test was used to test the difference between categorical variables, and the t-test was used for the continuous variables for the pre-intervention and post intervention intervals, using a significance level of 0.05. To evaluate the effect of the implementation methods, we used logistic regression analysis  on the outcomes of interest. The significance level, the odds ratio, and the 95% confidence interval estimated for the risk of parameters of interest were all reported when appropriate. To identify the possible moderation effect of demographics or clinical variables, we used the filter method. In the filter method, variables that met criteria  were chosen to be included as confounding factors to the regression model.Table 1). In the RRT period, there were 673 hospital-wide cardiac arrests, or 2.20 cardiac arrests per 1000 patient-days. In the RRT-MET period, there were 484 hospital-wide codes, or 0.88 cardiac arrests per 1000 patient-days. This event reduction translated to an odds ratio (OR) of 0.40 (0.35–0.45 95% CI) (p<0.001) (Table 2). More specifically, the cardiac arrest rates in the ICU reduced from 1.45 to 0.60 events per 1000 patient-days (p<0.001). In the acute care wards, the cardiac arrest rates reduced from 0.43 to 0.17 events per 1000 patient-days (p<0.001). In the ED, the cardiac arrest rate reduced from 0.20 to 0.07 events per 1000 patient-days (p<0.001).In the RRT period, we analyzed 305,999 patient days between January 2013 and September 2014. In the RRT-MET group, we analyzed 550,617 patient days between October 2014 and December 2017. There was no statistical difference between the groups in terms of mean age or sex. There was a statistically significant increase in hospital length of stay (LOS), and Case Mix Index (CMI), and a non-statistically significant increase in mortality . More specifically, there was a significant reduction in PEA arrests in all three sections of the hospital. ICU PEA arrest rates decreased from 1.05 to 0.34 per 1000 patient days (p<0.003), acute care ward PEA arrest rates decreased from 0.25 to 0.09 per 1000 patient days (p< 0.001), and ED PEA arrest rates decreased from 0.17 to 0.05 per 1000 patient days (p<0.003). The highest proportional drop in PEA arrest of 32% was noted in the ED  arrests decreased from 0.48 to 0.20 events per 1000 patient days (p<0.001) (Table 2).There was a statistically significant reduction in the number of overall in-hospital PEA arrests from 1.55 to 0.50 events per 1000 patient-days (p<0.001). PEA arrest contributed to 70% of ACLS rhythms in the RRT period compared to 56% in the RRT-MET period . The major reasons for ICU transfers following RRT and MET activation were respiratory instability (38%), cardiovascular instability (30%), and overall concern of the floor nursing staff.During the RRT-MET period, there was an incremental increase in utilization of RRT and MET over time. The median number of calls to the RRT was 658 calls per quarter, averaging to seven calls per day; the median number of calls to the MET was 212 calls per quarter, averaging to 2 calls per day. This correlated with a drop in overall code rates Click here for additional data file.


Concrete is the most common building material; therefore, when designing structures, it is obligatory to consider all structural parameters and design characteristics such as acoustic properties. In particular, this is to ensure comfortable living conditions for people in residential premises, including acoustic comfort. Different types of concrete behave differently as a sound conductor; especially dense mixtures are superior sound reflectors, and light ones are sound absorbers. It is found that the level of sound reflection in modified concrete is highly dependent on the type of aggregates, size and distribution of pores, and changes in concrete mix design constituents. The sound absorption of acoustic insulation concrete (AIC) can be improved by forming open pores in concrete matrices by either using a porous aggregate or foam agent. To this end, this article reviews the noise and sound transmission in buildings, types of acoustic insulating materials, and the AIC properties. This literature study also provides a critical review on the type of concretes, the acoustic insulation of buildings and their components, the assessment of sound insulation of structures, as well as synopsizes the research development trends to generate comprehensive insights into the potential applications of AIC as applicable material to mitigate noise pollution for increase productivity, health, and well-being. Building regulations and planning authorities have not properly focused on resolving the ongoing issue of noise pollution faced by the residents of urban areas . TypicalConcrete is a widespread and cheap structural material for the construction of residential buildings of any volume and number of storeys . During To reduce build time, labor savings, and thermal efficiency, most architects and designers prefer the use of insulated concrete forms. However, the acoustic properties of these insulated concrete forms are often overlooked or under looked. To provide better acoustic properties, the use of acoustic insulation concrete (AIC) is a recent advancement in the field of concrete technology. The acoustic component installed in an AIC reduces the sound in the building structure and keeps the pollution created by noise at bay while improving the acoustical effects of the sound generated within. To achieve a desired acoustic protection, the installation of an AIC wall can provide excellent exterior insulation as well as a soundproofing envelope. Due to a better soundproofing envelope, AIC becomes a suitable choice for hotels, airports, and schools where the requirement of thick traditional walls can be eliminated. Meanwhile, the use of lightweight concretes such as foam or fabric are usually porous and do not allow sound to be reflected. As a result, the sound passes through the porous medium, and the energy gets converted to heat while reducing its magnitude . Hence, Reflects back from the building wall,Absorbs within the wall, andTransmits through the building wall.To produce a noise and sound-proof AIC, the walls and roofs of a building could be engineered with modifications on the level at which the sound energy a 21]:Re:Re21]:ReStructural elements such as glazing and roof lights, which can reduce the performance, should also be considered. The transmission of noise between different zones of a building structure is shown in It should be noted that at various conditions, the separation wall could be of high standard AIC, while the side wall could be of low standard, which is continuous between the rooms. In such cases, flanking transmission can propagate more noise than direct transmission . Hence, The ability to reduce sound transmission through a structural element is what defines the properties of AIC. Usually, concrete is a good insulator of sound, which can reflect up to 99% of its total energy. However, it is also a relatively poor absorber of sound and can propagate within enclosed spaces, causing echoes ,30,31,32iE—energy of sound falling on the building envelope; rE—reflected sound energy; and eE—comprises the absorption and transmission of sound energy.The common aspects concerning the conservation of acoustic energy according to the classic ratio (1) are shown in For the design of enclosing structures, it is important to use extremely sound-absorbing or extremely sound-reflecting materials.The acoustic absorption coefficient α is computed using Equation (1) is expressed as (2).The absorption coefficient varies between 0 and 1, where 0 denotes the materials that reflect sound, and 1 is an ideal sound absorption material ,39,40. TThis is attributable to the fact that the coefficient of acoustic absorption, α, is varied for each frequency of sound. As a simplification, the division of the audible frequency spectrum into octaves (with a further 1/3 octave division) is used, as well as, for example, such characteristics as noise reduction coefficient (NRC) and sound absorption average (SAA) ,16,41. NSummary of the noise reduction coefficients for different concrete composites are presented in Sound reflectors are materials that reflect noise, preventing the further propagation of a sound wave. Concrete, glass, wood, plastic, and metal are used as sound-reflecting materials.-w—sound insulation excluding flanking structures such as longitudinal walls, ceilings, floors, i.e., it is a value obtained during research in a laboratory;R-w—sound insulation of the structure, taking into account the flanking elements, i.e., sound transmission along longitudinal side walls, floor slabs.R’In the concept of “Sound reduction index”, two quantities should be distinguished :-Rw—sounThe last parameter is more adequate; therefore, it is the one that is important for assessing sound insulation. It varies widely for different types of concrete. For example, rubber concrete with a smooth surface has this value at the level of 30–35 dB , and forw or R’w). The latter values are accepted for frequencies around 500 Hz; therefore, they are considered the most presentable, and the fact is that a significant part of the sound (noise) spectrum is concentrated in the region of 500 Hz. Accordingly, ISO 717-1 requires the weighted Rw (or R’w) value precisely in the frequency range of about 500 Hz. Thus, this is a somewhat simplified, but sufficient for practical application, interpretation for sound reduction index R (or R’). For the sake of clarity, soundproof building materials are commonly designed in such a way as to have a maximum sound absorption coefficient, specifically for noise with frequencies in the region of 500 Hz.The same indicator is “Transmission Loss (TL)”, which differs depending on the type of material. However, the sound reduction index R is defined by ISO standards, so, in general, it is usually preferred in the American literature. In addition, ISO 717-1 distinguishes between frequency-dependent R (or R’) and weighted values  show no significant effect on the absorption coefficient at lower frequency but increases at higher frequency, 800–1600 Hz in particular ,80. ThisCrumb rubber concrete (CRC), which is produced using different sizes of crumb rubber typically ranging 6 to 19 mm for coarse and 1 to 6 mm for fine, has been a subject of recent research ,32,62,84Materials with good sound absorption prepared by a concrete matrix incorporated with crumb rubber were investigated in . The souMaterials containing crumb rubber have been known to be a good absorber of sound, with absorption coefficients ranging between 0.3 and 0.7 . In factIn reference , the imp3, non-absorbent, hydrophobic, and closed cell nature . T. T186]. Under the conditions of the current world development, noise pollution associated with population growth and industrial development is the main problem faced by people living mainly in municipal areas. This condition highlights the importance for long-term research of new energy materials that can reduce the acoustic power of a sound wave as a result of absorption and reflection. From the literature reviewed, it is found that each construction material has a different NRC and fundamentally relies on its density. However, to avoid sound waves, in any building materials, as far as possible, mass is required—that is, high-density materials, such as bricks, are best suited for partitions, while cellular concrete is lightweight and inferior to bricks in sound insulation of wave noise. However, it is imperative to note that regarding the structural noise of lower frequency, a cellular concrete isolates better than brick. The construction industries worldwide have started to mainly use the sound-absorbing concrete to reduce the level of sounds in opened and closed areas and increase the amount of sound insulation.To increase sound insulation, wall structures should be designed as multilayer, including with the use of air gaps. Slab floorings that work as absorbers of structural noise should be designed using damping components, such as chopped rubber, and it is also necessary to prevent rigid “sound bridges”. It is proposed to expand the range of measured acoustic characteristics by expanding the lower boundary of the frequency range from 100 to 20 Hz.New applications of AIC are worth exploring and can be found; for example, EPS-based concrete can be produced as a class of innovative lightweight soundproof concrete.To further study the potential use of modified concrete to develop high-sound insulation performance concrete.To increase the acoustic insulation performance of AIC in a hardened state using ecofriendly materials.To further extend the possible utilization of AIC in the building construction with a sound-insulated system and future sustainable cities with reduced noise and sound transmission.However, it is obligatory to consider all structural parameters and design characteristics, when designing concrete structures, such as acoustic insulation property. This is, in particular, to ensure comfortable living conditions for people in residential premises, including acoustic comfort. Different types of concrete behave differently as sound conductors; especially dense mixtures are superior sound reflectors, and light ones are sound absorbers. It is found that the level of sound reflection in modified concrete highly relies on the type of aggregates, distribution and size of pores, and changes in concrete mix design constituents. The sound absorption of AIC can be improved by forming open pores in concrete matrices by either using a porous aggregate or foam agent. To this end, this article reviews the noise and sound transmission in buildings, types of acoustic insulating materials, and the acoustic properties. This literature study also provides a critical review on the type of concretes, the acoustic insulation of buildings and their components, and the assessment of sound insulation of structures, as well as synopsizes the research development trends to generate comprehensive insights into the potential applications of AIC as an applicable material to mitigate noise pollution for increase productivity, health, and well-being. Nevertheless, AIC is deemed as one of the superior materials that should be used in the building constructions, in particular, concert halls, cinemas, theatres, music venues, etc. Several further research investigations are recommended for the production of renewable and green concrete composite;


Time of edge switch was computed from the force signal as the period with the lowest force application on the outside ski. From positional data, turn cycles were separated into turning and straight-line phases . Time length, path length in the straight line, speed amplitude, and change in specific mechanical energy were computed for each turn and averaged for each skier. The path length during straight line was used to continuously characterize the line strategy within the spectrum between the Z (long straight line) and S (short straight line) strategy. Path length in the straight line was correlated with the amplitude of speed over a straight line  and relative and absolute time spent in the straight line . However, path length in straight line was not correlated with decrease of speed in the following turn  or time without force application on the outside ski . While higher-performing athletes on the course performed turns during which they dissipated less energy when normalized to entry speed , it appears they did so with variable turn strategies approaches.In alpine ski racing, different line choices can drastically affect turn or sectional performance. The straight-line transition between two turns is the main phase where skiers can gain speed in a race, open their trajectory, or reduce their path length. Between two turns, a skier can foster speed increase by spending more time in a straight line, inducing sharper turning phases (Z strategy). Inversely, speed can be conserved during the entire turn cycle by performing long curved turns separated by a short straight line (S strategy). This research aimed to evaluate the kinetic and kinematic specificities associated with the line strategy and to explore interactions of selected strategy with skier performance and energy dissipation. A mixed-level population of male alpine skiers ( To achieve the lowest possible race time, alpine skiers must continuously adapt their strategy and technique. Skiers perform turns according to their position, speed, and balance (influenced by the previous turn), individual capacity evolving with fatigue , and environmental factors   provides a means of characterizing sectional performance (Δemech/vin)  followed by a turning phase (TP). The trajectory and overarching turn characteristics the skiers choose  can generate substantial differences in turn-time in giant slalom (GS) , increased velocity or preserved energy is more challenging than for other skiers, and the normalization per entry velocity  effectively quantifies skiing efficiency. Consequently, subsequent investigations presented a very strong correlation between Δemech/vin and race time in slalom  and the trajectory of the skier (as the cumulated distance per turn) . The radial force can be considered as the component of the ground reaction force acting in the direction of the center of the turn. Therefore, to increase this force, a skier can theoretically increase the lateral angulation with the snow and increase the resultant normal reaction force . The positive correlation between mean nSkiRF value and performance is shown by some studies on direct and indirect measurement  is applied and depends on the speed, the mass of the skier, and the turn radius  is the event used to separate two turns. Despite appearing to be a key event of strategic decisions for skiers, behavior during this period has attracted less attention in the research. At present, there are several ways to separate a course into individual turns via detection of the TS from kinematic and kinetic markers  identify the kinetic and kinematic characteristics associated with the line strategy. We hypothesize that line Z strategy (characterize by longer path length in the straight line) is associated with (i.a) shorter path length in entire turn, (i.b) greater speed amplitude during the straight line and the turning phase, (i.c) more energy dissipated during the turning phase and entire turn, (i.d) longer time in the straight line normalized to the entire turn time, and (i.e) a longer time without force application between turns. The second aim of the study was to (ii) evaluate the interaction between selected strategy and performance level. We hypothesized (ii.a) that high-level skiers would be more inclined to use Z line strategy and (ii.b) line strategy would be associated with final race time.Seventeen male alpine skiers participated in this study . Skiers had mixed performance levels, consisting of recreational club level  to top-ranked current and previous elite world cup competitors (FIS points < 2). Each skier was informed of the content of the study and gave their written consent to participate. The experiment was conducted under the Declaration of Helsinki and was approved by the local ethics committee of the Université Savoie Mont-Blanc.Following 2–3 familiarization trials of the course while being equipped with the various experimental technology, skiers performed one or two timed runs on a 16-gate giant slalom course. Skiers were instructed to ski as fast as possible while avoiding the risk of falling. The athletes were provided with instructions to prioritize finishing the race and within these constraints reduce the race time as much as possible. The course setting was initially performed by a national ski coach, per a 16-gate GS setup with an average distance of 23 m and an offset of 8 m on a 25° inclined groom slope. Setup was close to competition setup featuring irregularities while avoiding side-slope, jumps, and slope-break during turns. Landmark poles were placed close to the course outside of the grooming area, and gate positions were measured relative to them and to these poles in order to triangulate them at every course setting. Skiers used the same pair of race skis  and were equipped with the same model of ski boots (SALOMON XLAB 140+ WC—Annecy—France). Skiers used their own race suits and other FIS-approved race clothing and protective gear .Throughout the duration of experimentation (30 days), snow quality  and environmental conditions  were observed. Testing took place during the first 3 h after the resort opening, the slope was groomed every night, and snow cleaning was performed between every run to limit the formation of micro-reliefs. Testing was performed only if the temperature during the preceding night was cold enough to freeze the snow. If these factors were not acceptable, experimentation was delayed until the conditions stabilized. Skiers were equipped with onboard validated force plates  was used for analysis, with the first turns of the race containing skating steps excluded. All the data analyses were performed using Matlab version R2019a (MathWorks—Natick—USA). To synchronize GNSS/IMU with a force plate, skiers hit the snow with their skis before and after the race to create acceleration and nSkiRF peak. Using these acceleration and force peaks, all data from force plate and GNSS/IMU were interpolated to resample data at 200 Hz. The “makima” method was used to perform a smoothing interpolation (with less undulation than “spline”).end) and beginning of force application on the outside foot (Fbeg) were detected on a 12-Hz low pass-filtered nSkiRF signal. The typical nSkiRF pattern on the outside ski during a turn is composed by a clear increase, a plateau, and a decrease  and under 30 m (Traj<30), corresponding to the end of the previous and start of the next turning phase, respectively . Percentage of the turn in SL (T%SL in %) was defined as T SL relative to the sum of T SL and time of the following TP. The path length is computed for the SL and the sum of the SL and the following TP (Path SL+TP in m). Path length during edge switch was computed using the same approach (Path edge switch in m).Four TS events were computed : two evedecrease ; two condecrease . PIP is decrease . PIP6 anSpeed was computed by the GNSS/IMU unit by Doppler measurement related to satellite motion. This computation method is more accurate than derivation of position. To compliment SL and edge switch detection, the amplitude of speed during the SL was computed as the difference between the minimum and maximum speed in the SL (ΔSpeed SL) and for the entire turn (ΔSpeed SL+TP).emech/vin): SL (Δemech/vin SL), TP (Δemech/vin TP), and SL + TP (Δemech/vin SL+TP). Finally, race time is considered as the macroscopic indicator of skier performance level and Δemech/vin SL+TPΔemech/vin SL+TP is considered as the instantaneous performance level indicator.Based on positional data, mechanical energy was computed at each point of the race as the sum of potential and kinetic energy, relative to the body mass of the skier  was tested using Pearson coefficient (r), the mean of skier turn cycles (n = 17). The second aim of the study regarding the interaction between line strategy and performance was also tested via correlation of straight-line length and race time (n = 17).Normality of each parameter was tested using the Shapiro–Wilk test except course time which approaches an expected flat distribution. To evaluate the first aim of the study , the correlation between path length in SL and kinematic turn parameters  and change in r2 (Δr2) between models were calculated. All descriptive data were expressed as means ± standard deviation (SD), and all statistical analyses were performed on JASP (Version 0.13.1—Amsterdam—Netherlands) with an alpha level set at p = 0.05.A hierarchical linear regression analysis was performed to determine whether the line strategy (assessed via the path length in SL) parameter improved the performance prediction provided by Δr = 0.967, p < 0.001).Mean course time was 29.47 s , the difference between the minimum and maximum time . Once skating steps were removed, 185 turn cycles remained for the final analyses. Correlations between path length in the straight line and kinetics or kinematic parameters of the turn are reported in n = 17) are presented in n = 17) are presented in emech/vin during turning phase  and entire turn  with race time.Secondly, mean path length SL is computed for each skier during the race. The mean path length in SL of the population was 8.96 m . Correlations between race time and path length in SL  of the predictive model  was calculated to evaluate the accuracy of predicted race time in comparison with Δemech/vin SL+TP alone; the p-value indicates the significance of the model prediction. Δemech/vin SL+TP was forced in Model 0, path length in SL was added in Model 1, and path length in SL was finally not included in the model as a significant improvement of race time prediction .The results of the hierarchical linear regression are summarized in r = 0.966, p < 0.001), and ΔSpeed SL . There was a trend for a negative correlation between the total path length during the entire turn and path length in SL . These results follow previous works . Skiers using the Z line strategy do not necessarily lose their additional speed gained in the SL in the following TP. Absence of significant results could be explained by the capacity of some skiers to conserve their speed even when using a Z line strategy. This capacity could come from a better technical level and better manipulation of the ski angle to decrease friction . Another explanation could be that some skiers using the S line strategy possibly drift at the beginning of the TP  was independent of the path length in SL. The time of edge switch was not influenced by temporal pressure variation induced by shorter or longer SL. Consequently, the time of edge switch should not be used to quantify the duration of the straight-line trajectory. Rather than turn line strategy, this parameter might be indicative of balance or technical abilities.emech/vin SL+TP during entire turn . Moreover, a lack of relationship between path length in SL and race time  induces a higher speed variation during SL, longer turn absolute and relative time spent in SL, and a tendency of shorter length path. However, the strategy used is not linked to time without force application on outside ski between two turns. Overall, the strategy adopted does not appear to be strictly associated with course-level performance of the skiers. The significant dispersion of strategies for the same performance level highlights that radically different approaches can result in similar energy dissipation characteristics. Consequently, it would seem that better skiers possess a profile that enables them to decrease energy dissipation across a variety of preferred and adopted turn strategies.The top-level performance variable in this study was course time, which represents a macroscopic index and lacks the descriptive information potentially provided by more detailed analyses. Indeed, this parameter is not representative of each turn performance; a high-level skier who made a mistake is considered as the same level as a lower-level skier who did not. Moreover, race time is influenced by snow condition, and even under “acceptable snow conditions,” the snow quality variation between subjects could create differences between them. At last, race time is influenced here by the capacity of the skiers to be accustomed to ski gear and experiment devices. Finally, only male skiers were tested, and while we assume our findings apply to female skiers, more research is needed on female skiers.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.Each skier was informed of the content of the study and gave their written consent to participate. The experiment was conducted under the Declaration of Helsinki and was approved by the local ethics committee of the Université Savoie Mont-Blanc.CD, FH, and MC conducted the data collection. CD, FH, MC, and PS conceptualized the study design and interpretation of the data. CD, MB, and MC contributed to the data analysis. CD drafted the manuscript. All authors revised it critically, approved the final version, and agreed to be accountable for all aspects of this work.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.


Dimethylamine borane (DMAB) is a promising fuel alternative for fuel cell applications. In this work cyclic voltammetric behavior of DMAB was investigated on the polymerized aminophenol film decorated with Ag nanoparticles in alkaline media. The polymer film was formed on the glassy carbon electrode by electrochemical technique and then, the surface was modified with Ag nanoparticles. The surface of the modified electrode was identified by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy techniques. The developed electrode has displayed high electrocatalytic activity for DMAB oxidation in alkaline media depending on the supporting electrolyte concentration. Experimental parameters such as cycle number used in electropolymerization of p-aminophenol, deposition of Ag nanoparticles and supporting electrolyte were optimized. Fossil-based energy resources give rise to environmental problems that led researchers to find alternative renewable energy sources. In recent years, fuel cell developments have received great attention due to their low emissions to environment and high efficiencies. Fuel cells convert chemical energy stored in fuels to electrical energy and therefore require a constant source of fuel to sustain the chemical reaction [1–3].Dimethylamine borane (DMAB) has amine odor and a chemical formula of (CH3)2 NH:BH3 [4]. DMAB is used in wide range of applications as a reductant [5–7] and is also used as a fuel in fuel cell applications . In recent years, studies on the use and research of boron-derived fuels have become widespread all over the world [10–12]. DMAB is a boron derivative fuel and it is important to examine its possible behavior as an alternative energy source. For this purpose, some researchers have studied the oxidation reaction of DMAB . Generally, from the reaction of DMAB in the alkaline solution, the hydroxytrihydroborate intermediate anion occurs . Two mechanisms have been proposed for DMAB oxidation on the different gold electrode. Plana and Dryfe [9] and Plana et al. [14] reported that the hydroxytrihydroborate anion is either converted to water with 6 electron yields, or a lower-efficiency oxidation process may produce molecular hydrogen with 3 electron yields. The general mechanism of DMAB has been proposed as an integer between 3 and 6 . The anode reaction of the direct DMAB fuel cell is the direct oxidation of DMAB in alkaline medium as follows:(1)(CH3)2NHBH3(aq)+OH(aq)-→BH3OH(aq)-+(CH3)2NH(aq)The hydroxytrihydroborate anion generally follows the possible two ways: First one is six-electron pathway (high efficiency) :(2)BH3OH(aq)-+6OH(aq)-→B(OH)4(aq)-+3H2O(l)+6e-The second pathway yields three electrons and molecular hydrogen (lower efficiency):(3)BH3OH(aq)-+3OH(aq)-→B(OH)4(aq)-+(3/2)H2(g)+3e-The hydrolysis of DMAB resulted in the formation of hydrogen gas as the anode fuel (Eq. (3)). On the other hand, direct DMAB oxidation provides an improved cell voltage compared with oxidizing molecular hydrogen. Competing chemical hydrolysis of DMAB with evolution of hydrogen, given by Eq. 3, is expected to be minimal at pH values in excess of 12.To date, there have been only a few studies which attempt to explain the mechanism of DMAB direct electrooxidation. In one of these studies, the oxidation of DMAB on polycrystalline gold electrodes was investigated by Plana and Dryfe [9]. Two sequential oxidation processes took place on gold surface. Three e− are removed from DMAB, so H2 is not oxidized at low potentials. A six-electron was extracted from molecule at high potential. Another study about direct electrooxidation of DMAB was conducted by Nagle and Rohan [13]. It explained that an overall coulomb number of six has been determined from the data acquired using the diffusion coefficient determined and the number of electrons in the oxidation reaction depends on the OH–DMAB ratio and the hydrogen content becomes increasingly important as this ratio decreases. The direct electrooxidation of DMAB was also investigated with Au and Pt bulk surface by Finkelstein et al. [18]. This study assumed that DMAB completely dissociates as in Eq. (1). Another finding is that DMAB oxidation has two distinct oxidation processes taking place at low potential region and high potential region.Metal nanoparticles have attracted great attention for their unique physical and chemical properties owing to their high surface area to volume ratio that differs from their bulk forms . Wide range of techniques such as microemulsion [21], sol-gel [22], thermal reduction [23], metal vapor [24], and chemical reduction  have been used for their synthesis. Electrochemical synthesis, on the other hand, has drawn particular attention as an inexpensive and rapid technique with an advantage of controlling over the particle size by changing the conditions. Metal nanoparticles are usually deposited on a support for stability such as conducting polymers [27]. Pt, Au, Pd, etc. are widely studied metal nanoparticles in various kinds of applications [28–31]. Although the efficiency obtained in the presence of these metals is high, the cost considerably increases. Therefore, there is a need for cheaper and highly effective alternative catalytic surfaces. Ag has an important place among other alternative metals due to its good catalytic activity, biocompatibility, ability for accelerating the electron transfer and electro-conductibility [32]. Different silver forms offered good catalytic activity for such analytes [33–35]. In addition, the price is quite low compared to precious metals, which is an important parameter for applications [36]. In this regard, Ag nanoparticle modified surface is designed as a candidate for an active surface to energy application.Polymers are promising materials for the preparation of nanocomposites. Conducting polymers have attracted significant attention because of their chemical, mechanical, optical, and electrical properties [37–39]. Due to their unique properties, a variety of conducting polymers are used in analytical applications [40] as well as catalytic surfaces in fuel cells [41–44]. Recently, some reports have been published by our research group about application of polymer modified electrodes on neurotransmitter detection [45], oxygen reduction [46], ammonia borane investigation [47], and antimony detection [48]. In each substrate polymeric structure has provided long-term stability for metal nanoparticles. Compared to all other polymers, electroactive aminophenol polymer (PAP) is remarkable in its various properties. In different environments, it has the ability to form highly conductive film on different surfaces [49–51]. Active functional groups in its structure both facilitate the polymerization on the electrode surface and form a selective surface for many analytes . PAPmodified surfaces maintain their conducting properties for a long time as compared to many conductive polymers [55]. Chemically stable homogeneous PAP films with controlled thickness can be achieved with electrochemical modification [56]. When all these mentioned features are evaluated, PAP stands out as a preferred modifier.Present work describes the fabrication of oxidized Poly (p-aminophenol) film modified electrode decorated with Ag nanoparticles (AgNPs) for the investigation of DMAB oxidation in alkaline solutions. The electrode surface was characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) energy-dispersive X-ray spectroscopy (EDX), X-Ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Experimental parameters both in electropolymerization and DMAB oxidation were optimized and the results of electrocatalytic oxidation of DMAB at the AgNPs-modified oxidized polymer film electrode were compared with those obtained with bare GCE and polymer film electrode.4reagents were of analytical-reagent grade and supplied from Sigma. AgNO3was purchased from Carlo Erba. All the solutions were prepared using ultrapure water. All electrochemical experiments were carried out under nitrogen gas.The monomer, p-aminophenol, was obtained from Fluka and the fuel, DMAB, was purchased from Alfa Aesar. NaOH reagent was obtained from Raidel De Haen. Sodium dodecylsulfate (SDS) and HClO2) was obtained from BASi. The surface characterization was examined by using Thermo K-Alpha-Monochromated high-performance XPS spectrometer (XPS), JEOL JEM-ARM200F transmission electron microscopy (TEM), and Philips XL30 SFEG scanning electron microscopy (SEM).Autolab 302N was used as voltammetric analyzer for measurements. Three electrode systems consisting of a working electrode, a platinum wire counter electrode, and an Ag/AgCl (sat. KCl) reference electrode were employed in measurements. Glassy carbon electrode  and chronoamperometry were used for electrochemical measurements. CVs were carried out between –1300 mV and 0 mV with 50 mV s4solution and electrochemical deposition of poly(p-aminophenol) on GCE was performed by cyclic voltammetry technique as given elsewhere [57]. Polymerized film was obtained by consecutive 35 potential cycles with 100 mV s-1scan rate from –0.5 V to 2 V. The resulting electrode was abbreviated as PAP/GCE.Before modification, the GCE was polished with alumina slurry (0.05–3 μm) and rinsed with pure water. For removing any residues, the electrode was subjected to ultrasonication in ethanol  and ultrapure water. The GCE was then immersed in a 5 mM SDS and p-aminophenol containing 0.5 M HClO3on the PAP/GCE in 0.1 M HNO3 solution. It was performed by ten repetitive cyclic voltammograms in the potential range of 0.3 V and –0.9 V.AgNPs were deposited on the PAP/GCE surface using electrochemical reduction of silver ions from 2 mM AgNOThe surface morphologies of the electrodes were characterized by XPS, SEM, TEM, and EIS. Figures 1A–1C show the SEM images of AgNPs/PAP/GCE with different magnifications which exhibit the good surface coverage with polymer film and AgNPs. Spherical AgNPs are distributed homogeneously on the polymerized electrode surface. The presence of Ag element on the PAP/GCE surface was analyzed by Energy Dispersive X-ray (EDX) spectroscopy . The weight gain of the PAP/GCE because of the Ag loading was found nearly 8.7%. The overall data has confirmed that uniform coverage of Ag on the PAP/GCE can be achieved with cyclic voltammetry. The size distribution of the Ag nanoparticles obtained from SEM analysis was shown in Figure 1E. The particle size ranges from 2 to 160 nm and the average particle size was found approximately 100 nm. Moreover, TEM image of AgNP-modified PAP surface  exhibited small spherical and flower-like structures related to the AgNPs. Comparison of SEM and TEM images point out that the Ag metal particles’ diameters were not identical because of the application of different preparation procedures for SEM and TEM samples. For the SEM measurements, the electrochemically prepared composite surface was scanned by the SEM system; thus, the AgNPs/PAP/GCE surface was maintained. In addition, in TEM measurements, the electrochemically prepared polymer and Ag metal particles’ content were transferred to ethanol solvent by scraped from the electrode surface with a sharp knife and then TEM grids. The Ag metal particles should be liberated to smaller particles. Accordingly, number of the Ag metal particles in the SEM image was higher than that in the TEM image.5/2and Ag3d3/2were observed at binding energies of 368.39 and 374.08 eV, respectively. The results verified that Ag species inside the aminophenol polymer film were chiefly dispersed as metallic Ag . Moreover, the amount of Ag was found as 34.4 μg cm-2according to the experimental results.XPS technique provides important information about bonding characteristics of the film and oxidation states of Ag nanoparticles. Figure 2A shows the wide spectrum of poly(p-aminophenol) film. It is evident that Ag3d, C1s, O1s, and N1s signals are present in polymer structure. For each curve-fitted region, the component peaks are numbered and chemical state assignment was identified based on literature data [58–60]. The curve fitting of the C1s peaks for PAP/GCE has been done by assuming two components at 284.7 and 286.2 respectively . These values could correspond to C-N and C-O groups, on the basis of the PAP chemical formula. The fitted O1s spectra of the PAP modified GC electrodes were shown in Figure 2C. Two oxygen species were observed with the PAP/GCE  at BE 531.7 and 533.3 eV. The lower BE signal (531.7 eV) could be assigned to –C-O bond. The BE at 533.3 eV could be due to typical of phenolic/ether oxygen. Figure 2D shows the fitted N1s spectra indicating one component centered at 400.2 eV, a binding energy typical of C-N groups in the polymeric chain. Figure 2E shows the XPS spectra of AgNPs/PAP/GCE in Ag3d region. Ag doublets of Ag3dEIS was performed in 5 mM DMAB containing 2 M NaOH solution in the frequency range of 50,000 to 0.05 Hz. The normalized Nyquist plots were represented in Figure 3A and results were fitted with (R(RC)) equivalent circuit. The highest electron transfer resistance was obtained at bare GCE. This value was decreased with polymer coating on the surface and reached its smallest value with subsequent Ag modification. As seen from the results, lower solution resistance and DMAB oxidation impedance indicate that DMAB is more easily oxidized on the AgNPs/PAP/GCE surface as compared to the GCE and PAP/GCE. In addition, Bode plots were shown in Figure 3B. They reveal the signs of redox activity both in the modulus of the impedance and the phase angle. The double sigmoid is visible at low frequency in modulus impedance. According to the phase angle, capacitive behavior is observed over a narrow frequency range and where a second capacitive contribution is seen between 1 and 10 Hz. This behavior is indicative of residual, albeit hindered, redox activity at the electrode surface. The impedance value was increased with the modification of PAP and AgNPs on the GCE surface. This behavior was found related with the faster electron transfer rate. At the intermediate frequencies the phase angle value remains almost the same for all electrodes. The same phase angle indicates that all electrodes have the same capacitive properties.3Fe(CN)6/K4Fe(CN)6couple. K3Fe(CN)6/K4Fe(CN)6involves one electron per molecule redox reaction [63]. Based on the obtained results, square root of scan rate versus peak current plot was drawn. ESA of the bare and modified electrodes were calculated with the help of Randles–Sevcik equation (4):In this study, the electroactive surface area (ESA) was via CV by employing the increasing scan rates on Ag- NPs/PAP/GCE in 0.1 M KCl containing 0.5 mM K(4)ip=6/K4Fe(CN)6concentration (C) was added to the equation, n is the transferred electron number in the redox system was taken as 1, active area (A) is the only unknown component in the equation that calculated from the result of the equation [64]. ESA of the electrodes were found as 0.056 cm2, 0.290 cm2, and 0.574 cm2for GCE, PAP/GCE and AgNPs/PAP/GCE, respectively. Presence of PAP and AgNPs lead to an increase on the electroactive area of GCE. The larger electroactive surface area confirms the higher activity toward DMAB oxidation.(diffusion coefficient) was taken as 6.70 ×10-2current value at the AgNPs/PAP/GCE, while there is no response obtained at bare and PAP/GCE for DMAB oxidation.The performance of the electrodes towards DMAB oxidation was tested by cyclic voltammetry in alkaline media. Figure 4 demonstrates the cyclic voltammograms obtained with the bare, PAP/GCE, and AgNPs/PAP/GCE electrodes in the presence  and absence  of 1 mM DMAB solution in 2 M NaOH. The AgNPs/PAP/GCE has displayed an excellent catalytic activity towards DMAB oxidation in comparison to the bare electrode and PAP/GCE. A well-defined irreversible oxidation peak was observed at –916 mV with 0.36 mA cm-1in further modification studies.In fuel cell studies, alkaline media is preferred for operational purposes. The effect of NaOH concentrations on the DMAB oxidation was investigated in the concentration range of 0.05 to 4.00 M . The peak currents related with the DMAB oxidation have shown an increase up to 2 M and then decreased for more concentrated solutions of NaOH. The change in the peak current was accompanied by the shift in the peak potential by increasing NaOH concentration. It has been known that DMAB is relatively stable at high pH values [9]. Therefore, 2 M NaOH medium was selected as the optimum supporting electrolyte since it provides high peak current and a satisfactory shift in the peak potential. Electrochemical polymerization offers an advantage of tuning the polymeric film thickness and nanoparticle size/distribution which are important in terms of catalytic activity. The surface coverages of PAP/GC electrodes were adjusted by changing the cycle numbers used in polymerization from 30 to 60 in the studied potential range. Figure 5B demonstrates the effect of polymerization cycle number on the oxidation peak of 1 mM DMAB in 2 M NaOH. As can be seen clearly in Figure 5B, the peak current obtained for DMAB has given a plateau between 35 to 50 cycles while the desirable shift in peak potential was observed at 35 cycles. Therefore, the potential was cycled from –0.5 to 2 V for 35 consecutive scans with a rate of 100 mV sAnother parameter to be optimized is the cycle number of Ag deposition which is used for nanoparticle formation. The cycle number varied from 5 to 20 and resulting peak characteristics were plotted in Figure 5C. DMAB oxidation peak current reached its maximum value with the satisfying potential value with 10 cycles of Ag deposition on PAP/GCE.-1. These data show that the electrode reaction was controlled by diffusion of DMAB to electrode surface . The plot of peak potential vs. logarithm of scan rate was also shown in Figure 6C. The logarithm of the scan rate has a linear dependence with peak potential; therefore, the results showed that an irreversible electrode reaction occured on the AgNPs/PAP/GCE.Cyclic voltammetric response of AgNPs/PAP/GCE in 1 mM DMAB containing 2 M NaOH with various scan rates were shown in Figure 6A. The peak current of DMAB was directly proportional to the square root of scan rate in the range of 3–1000 mV s-2with a correlation of 0.9975 by changing DMAB concentration in a range of 1–8 mM. The overall data indicates the efficiency of AgNPs/PAP/GCE electrode for DMAB oxidation in alkaline media.The voltammetric response and corresponding calibration plot of peak currents vs. concentrations are shown in Figure 7. The curves b–e corresponds to the DMAB concentration of 1.0, 3.0, 5.0, and 8.0 mM, respectively where curve a displays the background response of electrode. The oxidation peak currents increase linearly from 0.36 to 2.33 mA cmThe rotating disk electrode (RDE) technique is a convenient technique to determine the kinetics and the mechanism of electrochemical electrode reactions. Linear sweep voltammetric (LSV) studies were performed on AgNPs/PAP/GCE in the presence of DMAB to determine the kinetic parameters more quantitatively . Based on the RDE results at a chosen potential, the number of electrons transferred in the redox reaction can be calculated using the Koutecky–Levich (K–L) equation (5) [65] as follows.(5)1j=1jk+10.62nFACDMABDDMAB23ω12γ-16-1) , CDMAB is the concentration of DMAB in 2.0 M NaOH (5 ×10-6mol cm-3) , DDMAB is the diffusion coefficient of DMAB [13], γ is the kinematic viscosity of the solution (0.0117 cm2s-1) which is determined with Oswald viscosimeter at 25 °C. According to the equations, the n was calculated from the slope of the Koutecky–Levich plotj-1vs. ω−1/2. The calculated total electron number for DMAB oxidation is 5.6, which is close to the theoretical value of 6.where j is the measured current density, jk is the kinetic current density, ω is the electrode rotation rate (rad/s), n is the number of electrons transferred for DMAB, F is Faraday constant (96485) C molThere are a limited number of studies on DMAB oxidation in fuel cell applications. These studies are as follows; the electrochemical behavior of DMAB on Au bulk electrode was investigated by Finkelstein et al. [18]. The results of this study showed that the total number of electrons transferred during the oxidation of DMAB was found as 5.4. This value depends on potential and formation of H2 bubble. The oxidation behavior of DMAB was studied by Rohan and Nagle using a gold microdisk in alkaline medium [13]. They exhibited that the electron number transferred in the electrooxidation reaction of DMAB varies from 3 to 6. It depends on the ratio of OH− to DMAB, with H2 evolution. An overall electron number of 6 have been determined with chronoamperometry results. Plana and Dryfe described the DMAB electrooxidation on polycrystalline gold electrodes at high pH [9]. They suggested two sequential three-electron processes on gold. At low potentials, three electrons are extracted from the molecule, denoting that hydrogen is not oxidized, whereas at high potential a six-electron oxidation occurs. In another study investigating the oxidation behavior of DMAB, Pt was used as the electrode [8]. Martins and Nunes evaluated the effect of DMAB concentration on the number of electrons transferred in the electrooxidation reaction. In the electrooxidation of DMAB on the Pt surface, the transferred electron numbers were calculated as 3.86, 4.68, and 3.76 from the discharge curves for three different DMAB concentrations. The reason for the low number of electrons is that the platinum surface catalyzes the formation of hydrogen, causing hydrolysis of DMAB. Sadik et al. explained electron transfer mechanism for the DMAB on gold surface in KOH solution [15]. This study has highlighted the pH-dependence of DMAB oxidation on gold in alkaline solution. The total number of electrons transferred in oxidation of DMAB on gold surface was calculated using the rotating disk electrode (RDE) as 5.74. All these studies examining the oxidation mechanism of DMAB show that the number of electrons transferred in electrode reaction on all gold-based surfaces is close to the theoretical number of 6. According to the results, it can be said that DMAB has direct oxidation reaction on gold surfaces. Conversely, when the platinum surface is used as the electrode, it is found that the number of electrons is reduced due to the formation of hydrogen. In our study, the number of electrons transferred in the DMAB oxidation on AgNPs/PAP/GCE surface was found to be 5.6. Although this value is consistent with the literature, it shows that direct oxidation reaction takes place. Furthermore, compared to gold and platinum electrodes, the proposed AgNPs-PAP composite electrode is advantageous in that it is relatively inexpensive, stable, and easy to prepare.Stability is a challenging issue for fuel cell applications. For this purpose, chronoamperometry was applied at AgNPs/PAP/GCE and Ag wire to test the signal change during this measurement towards the response of 8 mM DMAB . In both chronoamperometric curves, the currents were dropped rapidly at first and then became relatively stable. The higher steady-state peak current was achieved at AgNPs/PAP/GCE as compared to the Ag wire. Moreover, a long-term storage of the AgNPs/PAP/GCE was investigated by keeping the electrode in vapor of the 2.0 M NaOH solution when no measurement was taken. The response showed no significant change in the peak current and peak potential of DMAB after 1 month. These results prove that AgNPs/PAP/GCE is a stable and efficient surface for the oxidation of DMAB.In the present work, AgNPs/PAP/GCE catalyst has been prepared by electrochemical synthesis of AgNPs after electrochemical formation of poly aminophenol film on glassy carbon electrode surface. Morphological and chemical characterization of the AgNPs/PAP/GCE was carried out by SEM, TEM, EDX, XPS, and EIS techniques. The SEM images revealed that spherical AgNPs were distributed homogeneously on the PAP/GCE with the average size of approximately 100 nm. From the XPS results, it clarified that Ag species inside the PAP were chiefly dispersed as metallic Ag. Cyclic voltammograms of DMAB were indicated that higher electrocatalytic activity is obtained on the AgNPs/PAP/GCE as compared to the GCE and PAP/GCE in alkaline media. Experimental procedures such as cycle number of aminophenol polymerization, cycle number of Ag deposition, and NaOH concentration have also been optimized. The electrocatalytic oxidation of DMAB at AgNPs/PAP/GCE was found to proceed via 5.6 electron transfer, which was calculated from RDE results. It shows that direct oxidation reaction of DMAB takes place on AgNPs/PAP/GCE. The stability studies were performed by chronoamperometric technique and the results indicated that the AgNPs/PAP/GCE was introduced as a stable and efficient surface for the oxidation of DMAB. The overall results demonstrated that the AgNPs/PAP/GCE is a promising alternative as cheap, stable, and easy prepared anode material for direct DMAB fuel cells.


Serum cholinesterase could be new biomarker and predict the extent of organ involvement in IgG4-related disease.Dear Editor, IgG4-related disease (IgG4-RD) is a fibroinflammatory condition generally characterized by tumefactive lesions and elevated serum IgG4 concentration  were assessed retrospectively and also compared with healthy controls  and 16 IgG4-RD patients had normal levels . Notably, serum ChE levels in most patients were elevated 1 month after CS therapy (Rheumatology Advances in Practice online) and decreased again during flare-up in some cases (data not shown).The mean serum IgG and IgG4 levels were 3105 (1716) and 722.8 (592.4) mg/dl, respectively. Fourteen IgG4-RD patients had significantly lower levels of serum ChE [mean 131.9 (42.7) U/l] than those of healthy controls (s.d.), 4.3 (1.3)] was significantly greater than that in IgG4-RD cases with normal levels of serum ChE [1.9 (1.3); P < 0.05; P = 0.01; Rheumatology Advances in Practice online) and significantly lower in the multiple organ involvement group (n = 12) than in the limited organ involvement group (n = 18) . Stepwise analysis of serum ChE activity, the number of organs involved and several serological markers demonstrated that serum ChE activity was well correlated with the number of organs involved .Moreover, the number of organs involved in IgG4-RD cases with lower levels of serum ChE [mean (n = 10) and SS; n = 10) were examined comparatively because of exclusion of effects by hepatic protein synthetic ability and inflammation. Serum IgG and albumin levels were significantly lower in AAV cases than in IgG4-RD cases with multiple organ involvement and SS (Rheumatology Advances in Practice online). CRP concentrations were significantly higher in AAV cases than in IgG4-RD cases with multiple organ involvement and SS (Rheumatology Advances in Practice online). Despite these results, serum ChE levels were significantly lower in IgG4-RD cases with multiple organ involvement than in AAV and SS cases (Rheumatology Advances in Practice online). The markers indicating hepatic function, such as alanine aminotransferase, γ-glutamyl transpeptidase and platelets, revealed no significant differences between IgG4-RD cases with multiple organ involvement, AAV cases and SS cases (data not shown). Although we could not elucidate the mechanism of the change in serum ChE, serum ChE is a potential novel predictor of the extension of the IgG4-RD lesions.Finally, some laboratory data of IgG4-RD cases with multiple organ involvement, ANCA-associated vasculitis . In Japan, the measurement of serum ChE generally means that of BChE. The tissues with the highest BChE activity were found to be the liver, lungs, spleen, kidney, pancreas, stomach, small intestine, cerebellum, heart and plasma . The tisIn conclusion, the serum ChE level might be a new biomarker and clinically useful predictor indicating the extension of organ involvement in IgG4-RD. Further studies are necessary to gain a clear understanding of the relationship between the serum ChE level and IgG4-RD.rkaa031_Supplementary_DataClick here for additional data file.