The laminar flame speed of the surrogate fuels increased with the increase in the proportion of cyclohexane. This is due to the fact that the laminar flame speed of cyclohexane is higher than that of chain and aromatic hydrocarbons, and the addition of cyclohexane dilutes the ratio of chain and aromatic hydrocarbons in the mixture. In addition, engine simulation studies have shown that at higher engine speeds, the five-component surrogate fuel containing cyclohexane requires lower intake-gas temperatures to achieve positive ignition and are closer to the in-cylinder ignition of real gasoline.It has been discovered that there is a dynamic coupling between cycloalkanes and aromatics, which affects the number and types of radicals, thereby controlling the ignition and combustion of fuels. Therefore, it is necessary to analyze the effects of cyclohexane production in multicomponent gasoline surrogate fuels containing cyclohexane. In this study, a five-component gasoline surrogate fuel kinetic model containing cyclohexane was first verified. Then, the effect of cyclohexane addition on the ignition and combustion performance of the surrogate fuel was analyzed. This study shows that the five-component model exhibits good predictive performance for some real gasoline. Meanwhile, the addition of cyclohexane decreases the ignition-delay time of the fuel in the low and high temperature bands, which is caused by the early oxidation and decomposition of cyclohexane molecules, generating more OH radicals; in the medium temperature band, the isomerization and decomposition reactions of cyclohexane oxide cC With the growing world population and economy, the demand for energy is also increasing. The transportation sector is one of the major final consumers of total energy and a contributor to global atmospheric emissions. This sector accounts for 29% of the total world energy consumption and 65% of the world’s consumption of petroleum products, while gasoline is one of the most consumed fuels in the transportation sector ,2. In adGasoline, which is mainly composed of alkanes, naphthenes, olefins, and aromatic hydrocarbons, is a mixture of hydrocarbons with very complex components . GasolinGasoline surrogate fuels are composed of a limited number of components. A binary mixture of isooctane and n-heptane  is commonly used to match a given research octane number or motor octane number (RON or MON) ,7,8. TheMixtures with more than three typical components (TRF) are called multicomponent gasoline surrogate fuels. Such a mixture usually includes other components required to reproduce the real gasoline characteristics in addition to the three typical components. More components need to be added to the surrogate fuel to match important characteristics such as gasoline functional group or hydrocarbon distribution, average molecular weight, and octane number sensitivity, which are not met by PRF and TRF. Therefore, surrogate fuel should include components that can cover a wider range of typical gasoline. Real gasoline usually contains cycloalkanes, olefins, and oxygenates. The typical chemical kinetic mechanisms of four-component and five-component gasoline surrogate fuels are mainly linear alkanes, branched alkanes, aromatic hydrocarbons, olefins, and oxygen-containing components. Liang  added diCycloalkanes are an important component of transportation fuels, with different percentages of about 10% and 40% in gasoline and diesel . And amoIn order to make the physical and chemical properties of gasoline surrogate fuels closer to those of actual gasoline or to better analyze the mechanism of carbon soot formation, some researchers have started to focus on the development of simplified mechanisms for multicomponent gasoline surrogate fuels containing CHX. Li et al.  developeAlthough the addition of cyclohexane to gasoline surrogate fuels has been well studied, few studies have analyzed the effect of cyclohexane on the combustion characteristics of gasoline surrogate fuels. However, cyclohexane content affects the ignition quality of gasoline engines as well as the formation of polycyclic aromatic hydrocarbons (PAHs) and carbon soot. In addition, Andrae , in his The above studies have shown that cyclohexane components have a notable influence on the ignition and combustion processes of gasoline. However, in the development of gasoline fuel models, fewer studies have analyzed the effect of the addition of the new species (cyclohexane) on the original components and their predicted performance. In this study, the effect of adding cyclohexane to a four-component mixture consisting of n-heptane, isooctane, toluene, and diisobutene on the combustion of the surrogate fuel was investigated by kinetic-model simulation studies using a preconstructed simplified mechanism  for a fiThe model used in this study is a five-component gasoline surrogate fuel kinetic model  containing n-heptane, isooctane, toluene, diisobutylene, and cyclohexane, which we constructed in our previous work . In our In this section, the predictions of ignition-delay times, laminar flame speed, and HCCI cylinder pressure curves for three-, four-, and five-component gasoline surrogate fuels are explored, and the ignition and combustion behaviors of the surrogate fuels when the components are varied are verified against real gasoline, respectively.Based on the literature data ,32,33, tReal gasoline with different physicochemical properties can be described to some extent by adjusting the composition ratio between the five components. Over the years, the development of gasoline surrogate fuels has prompted many researchers to develop methods for formulating gasoline surrogate fuels ,34,35,36i and n denote the i-th component and the total group fraction in the compound, respectively; i. It should be noted that the sum of the molar fractions of the components is one in the calculation of each physical property, i.e.,Here, The basic physical and chemical properties  of the surrogate fuels can be basically determined by the above formulae to match the appropriate surrogate to the actual gasoline fuel. Therefore, the proportion of surrogate components is different for different actual gasoline, and even if two actual fuels have similar ignition and flame-combustion characteristics, their surrogate components are not the same.Sarathy et al.  measuredDuring previous validation of chemical kinetic models, the dependence of laminar flame speed on fuel combustion temperature and pressure was observed. The laminar flame speed increased with the increase in temperature and decreased with the increase in pressure . HoweverThe prediction of laminar flame speed by three surrogate fuels is shown in To further evaluate the effectiveness of the chemical kinetic model in simulating the combustion characteristics of gasoline fuels when different surrogate-fuel mixture compositions are selected, a homogeneous reactor HCCI model is used to simulate the variation of pressure curves of surrogate fuels operating in an HCCI engine. Christensen  measuredThe fuel used is a high-octane gasoline (Grön 98 MK1) with a RON of 98.5 and a MON of 88. Equations (1) and (2) are used to calculate the RON and MON for the three Grön 98 MK1 gasoline surrogate mixtures. The composition of the fuel is shown in The in-cylinder pressures of HCCI engines are predicted for the three surrogate fuels using the selected CDTRF kinetic model . Considering the uncertainty of the energy conversion of the fuel–air mixture from the engine intake to the time of entering the intake valve, the starting moment of the calculation is chosen to be −30 °CA (the upper dead point is 0 °CA). According to the experimental data, the initial conditions for the calculation at the moment of −30 °CA are condition 1: temperature 730 K, pressure 1.4 MPa; condition 2: temperature 750 K, pressure 1.35 MPa; condition 3: temperature 770 K, pressure 1.3 MPa.In addition, the accuracy of the model is not only to predict the cylinder pressure but also to be able to accurately predict the combustion exothermic rate. The calculation results of the exothermic rate of three surrogate fuels are shown in In the previous section, the ignition and combustion characteristics of three-, four-, and five-component gasoline surrogate fuels were analyzed with reference to experimental data on the ignition, flame propagation, and HCCI in-cylinder combustion of common gasoline on the market. However, the development of the model needs to consider the effect of the addition of new species on the original components and their predicted performance. In this section, the effect of adding cyclohexane to a four-component mixture consisting of n-heptane, isooctane, toluene, and diisobutene on the combustion of the surrogate fuels is explored through kinetic-model simulation studies. This four-component surrogate fuel was formulated by Fikri et al. , and theFor the fuels formulated in The ignition characteristics of the fuel are controlled by the chemical-reaction kinetic process of the fuel itself and the input of external boundary conditions. Therefore, in this paper, the effect of cyclohexane addition on the ignition-delay time of gasoline–surrogate fuel mixtures are first investigated under lean combustion conditions.The ignition-delay times are calculated for five gasoline–surrogate fuel mixtures (Fuel 1–5) under the lean combustion condition , temperature range of 600–1250 K, and pressure range of 0.5–4 MPa. The ignition-delay times of the five surrogate-fuel models calculated using the selected mechanism are given in As can be seen in In order to further study the effect of initial pressure on the ignition laws of surrogate fuels, the ignition laws are investigated at different temperatures with different cyclohexane concentrations. The results shown in The root causes of the different surrogate fuels showing different ignition patterns are further analyzed at the microscopic level by chemical kinetics. For the two fuels (fuel 1 and fuel 5) with the largest difference in cyclohexane content, sensitivity analyses are performed at low (690 K), medium (800 K), and high (1200 K) temperatures at an initial pressure of 2 MPa and an equivalence ratio of 0.5, and the top ten most-sensitive reactions are selected.The sensitivity reactions of the fuel ignition process for fuel 1 and fuel 5 at an initial temperature of 690 K are shown in 6H12O2, which in fuel 5, the surrogate-fuel ignition process showed higher sensitivity; in addition, the small molecule reaction R358. CH2O + OH = HCO + H2O exhibits a greater sensitivity during fuel 1 ignition, which indicates that the depletion of OH radicals in the R358 reaction reduces the reactivity of fuel 1 fuel. The above analysis illustrates that the fuel ignition process in the low-temperature region is controlled to a great extent by the initial oxidation and dehydrogenation reactions of fuel macromolecules, and the cyclohexane molecules of fuel 5 are the first to react, and the accumulation of OH radicals drives the early ignition of fuel 5.Among them, for fuel 1, R7 and R36 are the reactions of straight and heterochain alkanes with OH radicals to remove a hydrogen atom to form the corresponding alkyl radical, and R37 is the further decomposition of hydroperoxyalkyl radicals (QOOH); for fuel 5, R36 is the same as the dehydrogenation of chain alkanes, and R127 is the isomerization of cyclohexane oxide cCAmong the above reactions with large, normalized sensitivity coefficients, OH radicals are found to appear more often, which indicates that OH radicals have a greater influence on the ignition and combustion of the system. The OH radical molar fraction curves for the fuels in Next, the sensitivity of the ignition characteristics of fuel 1 and fuel 5 at a medium temperature of 800 K is analyzed. Unlike the low-temperature region, the temperature sensitivities calculated for the two surrogate-fuel ratios in the medium-temperature region appear significantly different. This is shown in 2O2 is decomposed into two OH radicals under the action of the third body, which increases the system temperature and reduces the ignition-delay time, leading to the formation of the NTC region of the fuel. However, the reactivity of fuel 1 in the middle-temperature region is still lower than that in the high-temperature region, because some macromolecular reactions  have large, normalized sensitivity coefficients. From 6H12O2, respectively. In contrast, the small molecular reaction R409 only occupies a small proportion. This explains the phenomenon that fuel 2~5 inhibit the NTC effect in For fuel 1, the reactions with larger normalized sensitivity coefficients shift from macromolecular reactions to small molecular reactions , and the small molecular reaction R409 has the largest normalized sensitivity coefficient. HThe OH radical generation curves for the five surrogate fuels in Finally, the sensitivities of the ignition characteristics of fuel 1 and fuel 5 at high temperatures of 1200 K are analyzed. Comparing the high-temperature normalized sensitivity coefficients in 2, generates water and oxygen molecules with OH radicals. Although the depletion of the active molecule OH radical has an inhibitory effect on the system ignition, the oxygen molecules generated by the reaction provide the oxidant for the subsequent fuel reaction. The radical reaction R391 shows the greatest positive sensitivity, which is a branching reaction of the chain, consisting of H radicals colliding with O2 molecules to generate active OH radicals and O radicals, while O radicals continue to collide with H2 molecules parametrically OH radicals, increasing the concentration of OH radicals in the system, raising the system temperature and prompting the fuel to reach ignition in a short time.Among them, the isobutylene radical hydrogenation reaction represented by the radical reaction R100 has a large, negative temperature-sensitivity coefficient, and the consumption of H radicals suppresses the elevation of the system temperature. In addition to exhibiting a large negative temperature sensitivity coefficient is the radical reaction R406, and the absolute value of the sensitivity coefficient is the largest for this radical reaction, which is a depletion reaction of OH radicals, and the unstable intermediate product, peroxyhydroxyl radical HOThe small difference in ignition-delay time between the two fuels at high temperatures is mainly attributed to the same reactivity of the small molecule reactions controlling the reaction progression. It can also be seen from The OH radical generation curves at high temperatures in The effect of cyclohexane on the ignition-delay time of surrogate fuels was analyzed in the temperature range of 600–1250 K, pressure of 0.1–4 MPa, and lean conditions with an equivalence ratio of 0.5. The addition of cyclohexane inhibits the occurrence of fuel NTC, especially at higher pressures. At low and high temperatures, the addition of cyclohexane shortens the ignition time of the fuel, and this effect is most obvious in the low-temperature region. Based on this influence pattern, the ignition pattern of gasoline containing naphthenic hydrocarbons can be analyzed for the subsequent gasoline containing naphthenic hydrocarbons.As mentioned in the previous validation of the mechanism, applying the chemical kinetic model to the numerical simulation of in-cylinder combustion, besides focusing on the ignition characteristics of the fuel, flame propagation is also an extremely important combustion characteristic, which is related to the normal propagation of the fuel flame during in-cylinder combustion and the study of in-cylinder detonation problems. Therefore, this paper investigates the effect of adding cyclohexane to gasoline surrogate fuels on the laminar flame speed of the overall mixture.2 and 21% O2.Atmospheric pressure and lower initial-temperature conditions are commonly used to study the laminar flame speed of fuels, and an initial temperature of 298 K and an initial pressure of 0.1 MPa are the general conditions under which the laminar flame speed of fuels is studied into the burner, and the experimental data obtained from different laboratories using different experimental methods can be easily compared at this condition. They can also be used as reference values for analyzing the pressure and temperature dependence of laminar and turbulent flames . In addiFrom the calculated results of the four working conditions, the trend and magnitude of the laminar flame speed changes are similar for the five surrogate fuels, but by the local enlargement in The results of the initial temperature and pressure effects on the laminar flame speed can be observed in the calculated results of the four working conditions. From In order to better understand the above phenomenon, the laws of laminar flame speed with temperature and pressure are analyzed in The variability of the surrogate-fuel laminar flame speeds was further analyzed in chemical kinetics. The sensitivity of fuel 1 and fuel 5 was calculated in 2 and one H radical, which releases heat and raises the system temperature, and the generated H radicals promote the reaction R391. Therefore, the same sensitivity reaction and sensitivity coefficients of Fuel 1 and Fuel 5 under two working conditions can explain the reason why the laminar flame speed shows the same trend.Among them, R62 exhibits the largest negative sensitivity because the reaction drives the consumption of H radicals. The reaction with the largest positive sensitivity, R391, which was introduced in the previous kinetic analysis of ignition characteristics, generates a large number of active OH radicals and O radicals that initiate the next chain reaction, which greatly increases the chemical reaction rate. R389, which first appeared in the sensitivity analysis, is an oxidation reaction of CO The reaction of CO and OH radicals produces COFurthermore, all the radical reactions with large sensitivity coefficients in In addition to ignition and flame propagation characteristics, fuel combustion in the cylinder is also a major characteristic. In HCCI engines, the mixture reaches the autoignition temperature almost simultaneously in the cylinder while exothermic reactions occur, which can be carried out in a thinner mixture, significantly reducing the generation of NOX and carbon smoke. To investigate the effect of cyclohexane addition on the in-cylinder combustion of surrogate fuels, the phase combustion of four- and five-component surrogate fuels in HCCI engines under lean conditions was investigated. The effect of cyclohexane on fuel autoignition was studied and explained from the perspective of fuel chemistry kinetics. In addition, the effects of engine speed, fuel/air ratio, and intake air temperature are analyzed.Sjöberg  investig2 molecules to produce a large number of OH radicals, making fuel 5 the first to ignite at the same intake temperature. In other words, fuel 5 requires a lower intake temperature than fuel 1 for ignition timing. In addition, the easier ignition of fuel 1 at low rpm (600 rpm) is attributed to the accelerated conversion of fuel molecules during the low-temperature stall phase (cold-flame phase) of the four-component fuel, which releases heat and leads to system temperature rise, as will be further discussed in the later analysis.As can be seen from 8H17 + O2 = JC8H16 + HO2 generated by the isooctane submechanism and the diisobutene submechanism. The conversion of isooctane in the cold-flame stage results in a net production of DIB. The negative conversion of DIB is more pronounced for fuel 5 because the conversion of isooctane in fuel 5 increases rapidly after −15 °CA. When the volume ratio increases to 0.5, a shift in the ignition sequence of fuel 1 and fuel 5 can be observed, and the inlet air temperature of fuel 5 burning at the right time of ignition causes fuel 5 fuel to ignite earlier. The n-heptane and isooctane conversion rates of fuel 1 in In In In addition to the effect of cyclohexane, the effects of engine speed, equivalence ratio, and intake temperature were analyzed by comparing 2H2), ethylene (C2H4), propylene (C3H6), 1, 3-butadiene (C4H6), and benzene (C6H6) were included.Finally, to investigate the emissions of both fuel 1 and fuel 5 surrogate fuels in the HCCI engine, the molar fraction production of some important carbon-soot precursors was analyzed at an inlet temperature of 373 K, an inlet pressure of 0.1 MPa, an equivalent ratio of 0.5, and an engine speed of 1200 rpm, as shown in 2H4 and C3H6 curves calculated for the two fuels differ, with the molar fraction curves for ethylene and propylene calculated by fuel 5 being more concentrated in front of the compression upper stop, while the curves calculated by fuel 1 are more dispersed, due to the cold-flame behavior of fuel 1. The molar fraction curves for C4H6 and C6H6 calculated by fuel 5 are clearly different from those of fuel 1  was further analyzed for C4H6 calculated for the surrogate fuels fuel 1 and fuel 5, where a positive reaction rate indicates fuel production and vice versa for consumption. It can be seen that among the first ten radical reactions calculated for the latter, R136; cC6H10 = C4H6 + C2H4 is the added reaction, which produces a 1, 3 butadiene molecule and an ethylene molecule from the decomposition reaction of cyclohexene C-C bond breakage. In addition, the reaction rate of the radical reaction R196. C4H7 + O2 = C4H6 + HO2 was increased in the fuel 5 calculations, and the R136 and R196 reactions together contributed to the higher molar fraction of C4H6 calculated for fuel 5. 6H6. It is observed that the addition of cyclohexane greatly increases the chemical reaction rate for the radical reaction R150. SAXcC6H7 = C6H6 + H. The removal of an H atom from SAXcC6H7 to form C6H6 is what leads to the increase in the molar fraction of C6H6 in fuel 5.From the above analysis, it is evident that the addition of cyclohexane has different effects on the surrogate-fuel ignition, flame propagation, and combustion characteristics in the HCCI cylinder. In the low-temperature reaction stage, the ignition-delay time of the fuel decreased gradually as the proportion of cyclohexane in the surrogate fuel increased, which was caused by the early oxidation and decomposition of cyclohexane molecules to produce more OH-active molecules. In the medium-temperature reaction stage, the addition of cyclohexane suppressed the negative temperature behavior of the surrogate fuels and became more pronounced with increasing pressure because the fuels containing cyclohexane were still dominated by macromolecular reactions in the medium-temperature stage and their ignition delay was less dependent on pressure, which affected the NTC behavior of the surrogate fuels in this region. The role of cyclohexane becomes less pronounced as the combustion characteristics in the high-temperature reaction phase are controlled by the small molecule reactions.2/CO/C1 as the core mechanism, which responds to the laminar flame speed of the fuel so that the laminar flame speeds of surrogate fuels with different cyclohexane ratios are similar. The small difference is attributed to the fact that the proportion of n-heptane, which has a larger flame speed, is reduced with the addition of cyclohexane.The coupling mechanism considers HHCCI engine tests showed that the five-component surrogate fuel containing cyclohexane required lower intake-gas temperature to achieve ignition timing at higher engine speed, and was closer to the in-cylinder ignition of real gasoline. In addition, the addition of cyclohexane results in higher concentrations of 1, 3-butadiene and benzene at ignition timing than in the four-component fuel.We have described all the materials and methods we used in our previous work. If you want to know more, you can read this literature .(1)Based on extensive experimental data of real gasoline, our previously constructed simplified kinetic model of CDTRF five-component gasoline surrogate fuel shows good predictive performance in three aspects of fuel ignition delay, laminar flame speed, and in-cylinder combustion characteristics of HCCI engines.(2)6H12O2 dominate the temperature sensitivity of the ignition delay due to the addition of cyclohexane, which affects the small molecule reactions that promote the formation of reactive radicals such as OH molecular reactions, thus inhibiting the NTC behavior of surrogate fuels. This trend becomes more and more obvious with the increase in pressure.As the proportion of cyclohexane in the surrogate fuel increases, the ignition-delay time of the fuel gradually decreases at low and high temperatures. While at the medium-temperature reaction stage, the isomerization and decomposition reactions of cyclohexane oxide cC(3)The laminar flame speed of the surrogate fuels increases with the increase of the cyclohexane ratio. This is due to the fact that the laminar flame speed of cyclohexane is higher than that of chain and aromatic hydrocarbons, and the addition of cyclohexane dilutes the proportion of chain and aromatic hydrocarbons in the mixture. From a microscopic point of view, the concentration of reactive radicals such as H and OH generated by each component varies. The C-C and C-H in toluene are more stable than other hydrocarbons, so cyclohexane addition increases the laminar flame speed of the fuel mixture.(4)Engine simulation studies show that at relatively high engine speeds, the five-component surrogate fuels containing cyclohexane require lower intake-gas temperatures to achieve ignition timing and are closer to the in-cylinder ignition of real gasoline; the addition of cyclohexane results in higher concentrations of 1,3-butadiene and benzene at ignition timing than the four-component fuels.In this study, the effect of cyclohexane addition on the ignition and combustion performance of surrogate fuels are analyzed based on three aspects: ignition delay, laminar flame speed, and in-cylinder combustion characteristics of HCCI engines. The main findings are as follows.In this paper, some discussions on the effects produced by cyclohexane in gasoline components are made at the kinetic mechanism level. In future research, the five-component gasoline kinetic model constructed by our group will be considered for the three-dimensional numerical simulation of engines. The effect of the cyclohexane component in the five-component gasoline surrogate fuel on engine combustion and emissions will be studied in a wider range and compared with existing studies.


To promote the development of green and low-carbon expressway construction, an evaluation index system and associated evaluation method for the construction of green and low-carbon expressways suitable for multiple bridges and tunnels is proposed. The evaluation index system was created from three layers: the goal layer, the criterion layer, and the indicator layer. The criterion layer includes 4 first-level indices and the indicator layer includes 18 second-level indices. The weight of each index in the criterion layer and indicator layer is determined using the improved analytic hierarchy process (AHP) method, and green and low-carbon expressway construction is then graded using the gray fuzzy comprehensive evaluation method combined quantitative indices with qualitative indices. The method with the selected indices is then verified in a case study on the Huangling-Yan’an Expressway, with the evaluation grade being “Excellent” and the evaluation value being 9.1255. The proposed evaluation method can provide theoretical and practical guidance for effective evaluation for green and low-carbon expressway construction. By the end of 2021, the total length of the highway in China reached 5.28 million kilometers, of which the length of the expressway reached 0.169 million kilometers. The huge consumption of energy and the emission of pollutants in the process of expressway construction have caused great damage to the ecological environment , where Bij > Aij > 0, as shown in uij is xij ∈ , a dimensionless numeric value.The green and low-carbon expressway construction evaluation indices in the indicator layer are divided into quantitative indices and qualitative indices according to the index properties. A linear dimensionless method was used to preprocess quantitative indices n1 represents the number of quantitative indices in the indicator layer. The comment set is set as {V1, V2, ⋯, Vk, ⋯, Vm} , with the quantitative criteria for each evaluation grade V = {v1, v2, ⋯, vk, ⋯, vm}. The semi-trapezoidal and triangular membership functions are used to determine the fuzzy membership of the index, that is, by dividing the demarcation point on the continuous interval, the membership is obtained by linear interpolation according to the size of index value. The membership function is shown as follows:The calculated values of all quantitative indices in the indicator layer were grouped into a factor set xi for evaluation grade vk is obtained, and all the fuzzy membership vectors constitute the fuzzy membership matrix R1.According to Eqs –9), the, the9), For qualitative indices in the indicator layer, the gray evaluation weight matrix is determined by combining expert scoring with the whitening weight function in gray theory, and the steps are as follows:Step 1: Establish the evaluation sample matrix using expert scoring methodp experts evaluated and scored (based on 10-point scoring) the n2 qualitative secondary indices in green and low-carbon expressway evaluation index system. The score given by the ith expert on the jth evaluation index was recorded as hij, and the evaluation sample matrix H composed of hij can be expressed as:An expert group composed of Step 2: Determine the evaluation gray classes and whitening weight functionsG = V = {v1, v2, ⋯, vk, ⋯, vm}.Considering that the gray evaluation weight matrix obtained in this section needs to be combined with the fuzzy membership matrix obtained in Section 3.3.1, the evaluation gray classes and whitening weight functions should be consistent with the comment set and fuzzy membership function in Section 3.3.1 respectively. The quantified vector for each evaluation gray class is Step 3: Calculate the gray evaluation coefficientfk(hij) for hij belonging to the kth evaluation grade, and calculate the gray evaluation coefficient njk of the jth qualitative index for the kth evaluation grade and the total gray evaluation coefficient nj of the jth qualitative index using Eqs fk(hij) fStep 4: Determine the gray evaluation weight vector and matrixrjk of the jth qualitative index for the kth evaluation grade is calculated using The gray evaluation weight R2.All the gray evaluation weight vectors constitute the gray evaluation weight matrix R1 is merged with the gray evaluation weight matrix R2 to obtain the fuzzy comprehensive evaluation matrix C. This matrix C is divided into several matrices according to indices in the criterion layer for multi-level fuzzy comprehensive evaluation. The multi-level fuzzy comprehensive evaluation starts from the bottom layer and multiple synthesis operations are then successively carried out upwards until the final results are obtained. Generally, it is divided into a first and second-level fuzzy comprehensive evaluation. The first-level fuzzy comprehensive evaluation comprehensively evaluates each index in the indicator layer, and the second-level fuzzy comprehensive evaluation considers the comprehensive influences between this and the criterion layer.The fuzzy membership matrix of the quantitative indices Step 1: First-level fuzzy comprehensive evaluationsth criterion layer is recorded as Ws, and the fuzzy comprehensive evaluation matrix of the corresponding indices in the indicator layer is recorded as Cs. The first-level fuzzy comprehensive evaluation result Bs is calculated using The weight vector of all indices in the indicator layer belonging to the Step 2: Second-level fuzzy comprehensive evaluationD, is composed of the first-level fuzzy comprehensive evaluation result, Bs, in order of rows.The second-level fuzzy comprehensive evaluation matrix, W, of the indices in the criterion layer and the second-level fuzzy comprehensive evaluation matrix, D, the second-level fuzzy comprehensive evaluation result, B, is obtained using According to the weight vector, The final evaluation grade can be obtained based on the maximum membership principle.Step 3: Comprehensive evaluation calculationY, is calculated by the quantified vector for each evaluation gray class, G, and the second-level fuzzy comprehensive evaluation result, B, using The final evaluation value, Take the capacity expansion project of the Huangling-Yan’an Expressway as an example. The Huangling-Yan’an Expressway is 143.2 km long, with 12 bridges and 22 tunnels. The expressway was designed according to the technical standards for four-lane expressways in hilly terrain.Special evaluation report of green highway theme project in Huangling-Yan’an Expressway construction , the completion performance of quantitative indices of Huangling-Yan’an Expressway were obtained, as shown in Referring to the According to the weight calculation method in Section 3.2, the judgment matrix is obtained, and the weight of each index is calculated after passing the consistency test.(1) The weights of indices in criterion layerThe judgment matrix, consistency test results and weight calculation results of indices in criterion layer in the green and low-carbon expressway evaluation system are shown in W = .The weight vector U2 > intensity index U1 = guarantee index U3 > characteristic index U4.According to the weight vector, the weights of each index in the criterion layer are sorted by size as: systematic index (2) The weights of indices in the indicator layerThe indices in the indicator layer corresponding to the intensity indices, systematic indices, guarantee indices and characteristic indices in criterion layer are calculated similarly. The weights of all indices are shown in V = {v1, v2, v3, v4, v5} = {3, 6.5, 7.5, 8.5, 9.5}. According to the method in Section 3.3.1, the fuzzy membership of the quantitative indices in the indicator layer is obtained and composes the membership matrix R1.The comment set is set as {Poor, Eligible, Intermediate, Good, Excellent}, and the value range for each evaluation grade is shown in Step 1: Establish the evaluation sample matrixH, was obtained.An expert group composed of five experts from the Haungling-Yan’an Expressway project evaluated and scored (with 0.5 points as the minimum unit of score) the qualitative indices in the indicator layer of the green and low-carbon expressway and the evaluation sample matrix, U27 as an example:Step 2: Calculate the gray evaluation coefficient Take the evaluation index U27 can be calculated similarly:Other gray evaluation coefficients for evaluation index The total gray evaluation coefficient:Step 3: Calculate the gray evaluation weight vector and matrixU27 can be expressed as:The gray evaluation weight vector for evaluation index R2, was obtained by summarizing the vectors.Other gray evaluation weight vectors for qualitative evaluation indices in the indicator layer can be calculated similarly, and the gray evaluation weight matrix, R1 and R2 were merged to obtain the fuzzy comprehensive evaluation matrix, C, and divided it into C1, C2, C3 and C4 according to the indices in criteria layer for multi-level fuzzy comprehensive evaluation.Step 1: First-level fuzzy comprehensive evaluationD, is composed of B1, B2, B3 and B4, and the second-level fuzzy comprehensive evaluation result, B, is obtained using Step 2: Second-level fuzzy comprehensive evaluation The second-level fuzzy comprehensive evaluation matrix, The maximum membership of the evaluation result B is 0.6646 at grade “Excellent”, which is higher than other grades, so the evaluation grade of Huangling-Yan’an Expressway green and low-carbon construction is “Excellent” according to the maximum membership principle.Step 3: Comprehensive evaluation calculationY, is calculated using The final evaluation value, This value is a quantitative embodiment of the evaluation grade “Excellent” and can be used to compare the green and low-carbon construction levels of different expressways.Project Evaluation Report is 97.37 according to the Standard, which is consistent with the evaluation results where the evaluation grade is “Excellent”, and the evaluation value is 9.1255. This demonstrates the accuracy and feasibility of the proposed evaluation index system and evaluation method. Furthermore, the quantitative processing and score calculation method of evaluation indices are more scientific and specific than those in Standard, and the merging of fuzzy membership and gray evaluation weight can effectively combine the quantitative and qualitative indices for a comprehensive evaluation.The evaluation score in the B1, B2, B3, and B4) and maximum membership principle, the Huangling-Yan’an Expressway has reached the “Excellent” grade in terms of intensity index, systematic index, and characteristic index, and “Good” grade in guarantee index, indicating that the publicity and training on energy conservation and emission reduction is the weakness of the project, and it is recommended to strengthen the management of this aspect.The proposed evaluation index system and evaluation method can evaluate and analyze the four indices in the criterion layer to find out the weak parts of the project and strengthen the precise management of the project. According to the first-level fuzzy comprehensive evaluation results (Compared with the traditional expert scoring method , 15, theThe proposed evaluation index system is divided into the goal layer, the criterion layer, and the indicator layer, with clear levels. The accuracy and feasibility of the evaluation system is demonstrated through the empirical analysis of the Huangling-Yan’an Expressway.The proposed evaluation method in this paper can improve the defects that the AHP method is susceptible to the misjudgment of some experts, and quantitative and qualitative indices cannot be comprehensively evaluated in traditional evaluation methods. The evaluation process and results are intuitive and clear.The concept of green roads has gradually been developed and refined from the initial sustainability of the whole life cycle of highway. The proposed evaluation index system focuses on the construction period of the expressway and introduces bridge and tunnel indices as characteristic indices to adapt to the multi-bridge and tunnel characteristics of expressways, especially expressways in mountain regions, which will contribute to the expansion of the concept of green expressway to some purpose.When calculating the weight, an improved AHP method is proposed, which combines the opinions of multiple experts to determine the weight and effectively avoid the situation of inaccurate weight calculation caused by misjudgments of some experts.The fusion of quantitative and qualitative indices can be realized by setting the fuzzy membership function and the whitening weight function as the same function, so that the comprehensive evaluation of all indices can be carried out.The proposed evaluation index system has strong versatility and scalability. It is suitable for green and low-carbon evaluation of expressways and highways with different geomorphic features when increasing or decreasing the characteristic indices.The weight of each index can provide management recommendations to the project management department. Among the four indices in criterion layer in this paper, the systematic index mainly including the use of recyclable and environmentally friendly new materials has the highest weight. It is recommended that the project management department pay special attention to the rational utilization of environmentally friendly materials while paying attention to energy conservation and emission reduction, and actively introduce new materials, which is of positive significance for the green and low-carbon construction of expressways.Referring to the idea of the establishment of the proposed evaluation index system, the green and low-carbon evaluation indices of expressway design, operation and management period can be established, and the evaluation of the whole life cycle of expressways with different geomorphic features can be realized by introducing characteristic indices.


The serum samples from the patients were collected before and 6 h after the end of the surgery. The most significant results were obtained for the sum of three sepsis-associated AMMs. This level was higher before the surgery in comparison with that of healthy volunteers (n = 48), p < 0.001, and it was also higher in the early postoperative period in patients with all types of complications compared to those without complications, p = 0.001; the area under the ROC curve, the cut-off value, and the odds ratio were 0.7; 2.9 µmol/L, and 5.5, respectively. Impaired microbiota metabolism is important in the development of complications after complex reconstructive aortic surgery, which is the basis for the search for a new prevention strategy.Postoperative complications in cardiovascular surgery remain an important unresolved problem, in particular in patients with aortic aneurysm. The role of the altered microbiota in such patients is of great interest. The aim of this pilot study was to determine whether the development of postoperative complications in patients with aortic aneurysm is related with initial or acquired disorders of microbiota metabolism by monitoring the level of some aromatic microbial metabolites (AMMs) circulating in the blood before the surgery and in the early postoperative period. The study comprised patients with aortic aneurysm ( With major reconstructive operations in cardiovascular surgery, the problem of the development of postoperative complications remains extremely relevant, since complications affect the short- and long-term results of surgical intervention, and also significantly increase financial costs. Aortic aneurysm is a severe life-threatening disease, which occurs with the involvement of almost all systems and organs in the pathological process, is characterized by hypoperfusion of organs, impaired tissue metabolism and progression of the inflammatory process, and is often accompanied by aortic dissection with the threat of fatal bleeding, etc. ,2. In moThe working hypothesis of this study is that microbiota disorders initially accompany aortic aneurysm and may subsequently cause the development of postoperative complications in conditions when preoperative preparation, surgery and early intensive therapy do not contribute to improvement, but, on the contrary, aggravate previous disorders.In choosing research methods, the authors relied on a number of previous works. The fact of deep disturbances in the composition of the gut microbiota was revealed during the examination of patients in intensive care units using the 16S rRNA gene sequencing method. The authors point to the loss of biodiversity, a sharp reduction in the number of species of beneficial anaerobic bacteria inherent in the body of a healthy person, and excessive growth of potentially pathogenic microorganisms ,8,9. TheChanges in the profile of microbiota metabolites in the gut and then in the blood are secondary to species dysbiosis. At the same time, the assessment of the degree of microbiota metabolism disorder may be clinically more significant than information about taxonomic disorders ,12. The It is always difficult to compare groups of patients and the results of surgical treatment, especially in regard to such pathology as aortic aneurysm where different types of operations are used and much depends on the experience of surgeons and anesthesiologists. In order to avoid doubts about the results that could be related to the qualifications and experience of medical personnel, the ethics committee made a decision to include in this study patients operated on by one specific team of surgeons and treated by a specific team of specialists in anesthesia and intensive care.The aim of this study was to determine whether the development of postoperative complications in patients with aortic aneurysm is related with initial or acquired disorders of microbiota metabolism by monitoring the level of aromatic microbial metabolites (AMMs) circulating in the blood before the surgery and in the early postoperative period (6 h).The present study was a single-center clinical study performed at the Petrovsky Russian Research Center of Surgery . Patients with a diagnosis of aneurysm/aortic dissection were included in the study. In order to exclude the influence of individual qualities and skill of surgeons and anesthesiologists, all patients involved in the study were operated on by the same team of surgeons and anesthesiologists.Inclusion criteria: patients aged from 18 to 75 years; reconstructive aortic surgery in 2021 performed by a team of surgeons under the guidance of Corresponding Member of the Russian Academy of Sciences, Professor, MD E.R. Charchyan; and a team of anesthesiologists under the guidance of Professor of the Russian Academy of Sciences, MD B.A. Axelrod; the presence of informed consent statement.Exclusion criteria: age under 18 or over 75 years; aortic surgery performed by another surgical team; refusal of the patient to participate in the study at any stage; mental disorders that prevent obtaining informed consent statement; and patient’s transfer to another hospital early after surgery.n = 79) before the surgery and 6 h after the end of the surgery were collected and frozen at −30 °C in Petrovsky Russian Research Center of Surgery . The Local Ethic Committee approved the study (N7 from 15 February 2021) which was conducted in accordance with the ethical standards of the Declaration of Helsinki and formal consent for participation in this study was obtained from each patient or their legal representative. The samples of the blood serum from the healthy volunteers (n = 48) were collected in Federal State Budgetary Institution N.N. Burdenko Main Military Clinical Hospital . The concentrations of aromatic acids  were measured using gas chromatography-mass spectrometry  in Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology  as it was previously described [The total number of the serum samples was 206, including 158 samples from the patients and 48 samples from the healthy volunteers. The samples of blood serum from the patients  analysis with the assessment of area under the curve parameter and its 95% confidence intervals (CI) in order to achieve the optimal sensitivity/specificity ratio (Youden’s J statistic). Additionally, odds ratio, sensitivity, specificity, positive and negative predictive values and accuracy were calculated. CI for sensitivity and specificity are “exact” Clopper–Pearson CI. Scatter plots with linear regression were used for visualization and modeling the relationship between metabolic status of the patients and anthropometric parameters. All analyses were conducted using IBM SPSS Statistics for Windows, Version 27.0. Armonk, NY, USA: IBM Corp. The differences were considered significant at From 166 patients with thoraco-abdominal aorta surgeries performed in 2021, 81 patients met the protocol conditions because they were operated on by one specific team. Two patients were excluded from the analysis due to the positive test for COVID-19 infection and were transferred to another clinic. Finally, 79 patients were included in the study. The median age of patients was 57 (46–64) years, 57 (72%) men and 22 (28%) women. There were 15 (19%) patients with acute/subacute aortic dissection . All patSeveral concomitant diseases were diagnosed in all patients participating in the study, including hypertension in 57 (72%) and heart defects in 55 (70%) patients, as well as various diseases of the gastrointestinal tract in 48 (61%) patients, multifocal atherosclerosis in 24 (30%) patients, ischemic heart disease in 20 (25%) patients, rhythm disturbances and cardiac conduction in 18 (22%) patients, and chronic kidney disease in 16 (20%) patients . PrognosThe patients underwent different types of reconstructive operations on the aorta, includingn = 21 (27%);Prosthetics of one or more parts of the thoracic aorta, n = 25 (32%);Hybrid surgery: stenting of the descending thoracic aorta with or without plastic surgery/prosthetics of the root and ascending aorta using Bentall–DeBono techniques or T. David, n = 14 (18%);Prosthetics of the aortic valve and ascending aorta using the Bentall–DeBono technique, n = 9 (11%);Prosthetics of the root and ascending aorta by the method of David, n = 5 (6%).Prosthetics of the thoracoabdominal aorta, n = 19 (24%);Prosthetics/plastics of the aortic, mitral or tricuspid valve, n = 12 (15%);Myocardial revascularization , n = 3 (4%).Radiofrequency ablation, Some patients underwent additional surgical interventions at the same time:For perioperative antibiotic prophylaxis in 57 (72%) patients, cefazolin was standardly used (2 g once immediately before surgery), and then it was prescribed at a dosage of 2 g three times a day for two or three days. Other cephalosporins  or antimicrobials of other groups or their combinations with vancomycin, fluconazole, etc., were rarely used according to individual indications, taking into account the anamnesis. When comparing indicators in groups of patients with and without complications who received different antimicrobials for antibiotic prophylaxis, no differences were detected.n = 79) were characterized by higher values of benzoic and 4-hydroxyphenyllactic acids compared to the healthy volunteers (n = 48). The parameter which describes the content of the diagnostically significant sepsis-associated microbial metabolites [A number of tyrosine and phenylalanine metabolites was measured in the serum samples of the patients and healthy volunteers, and the limit of quantitation for all metabolites was 0.5 µmol/L . The serabolites  includesn = 79) were divided into groups according to the course of the postoperative period. There were patients without complications (n = 36) and patients with different types of complications (n = 43). More than half of patients with a complicated course of the postoperative period had infectious complications (n = 26) such as pneumonia or local infection of the skin and soft tissues in the area of surgery. Among other types of complications, there were the development of organ dysfunctions or surgical complications , etc. Most often, patients with complications needed longer treatment in the ICU or were re-transferred from the specialized department to the intensive care at different times of the postoperative period, for example, due to the development of respiratory or cardiovascular insufficiency.All patients (The serum samples from the patients were collected before the surgery (0 points) and 6 h after the end of the surgery (1 point). The characteristics of the patients, the intraoperative parameters, the length of stay, and the concentrations of aromatic metabolites are demonstrated in n = 43) and without complications (n = 36). The concentration of one of the sepsis-associated metabolites 4-hydroxyphenyllactic acid in serum sample collected 6 h after the end of surgery (1 point) and the difference (∆ 1–0) was higher in patients with complications (n = 43). The same results were obtained for the sum of sepsis-associated microbial metabolites Σ3AMM.The intraoperative parameters  and length of hospital stay were statistically different in the patients with all types of complications (n = 36) and the patients with infectious complications (n = 26) were similar to those for patients with all types of complications (n = 43).The results for the comparison of the patients without complications (p = 0.065), and there was no significant relationship between BMI and Σ3AMM (p = 0.892) , concomitant diseases and other initial factors of patients, as well as the general index of concomitant pathology of Charlson had no significant differences between the two groups of patients. We detected a trend towards an increase in Σ3AMM with increasing age that did not reach statistical significance (= 0.892) .n = 43) and without complications (n = 36). The areas under the ROC curve for 4-hydroxyphenyllactic acid and Σ3AMM were 0.686 and 0.717, respectively. The optimal cut-off values for 4-hydroxyphenyl lactic acid (2.0 µmol/L) and Σ3AMM (2.9 µmol/L) were calculated. The risk of postoperative complications was 3.4 times greater (95% CI 1.3–9.0) and 5.5 times greater (95% CI 1.9–15.0) for 4-hydroxyphenyl lactic acid and Σ3AMM, respectively, when the cut-off value was exceeded.The ROC-analysis , Table 3Despite the great progress in cardiovascular surgery, the percentage of postoperative complications, such as infections at the site of surgery, pneumonia, and others, does not decrease and, according to the literature, on average is registered to range from 12.6 to 21%. The studies on this topic provide analyses of the risk factors for complications, which most often include age, gender, chronic lung diseases, heart failure, duration of cardiopulmonary bypass ,23. In rIn this study, the authors took as a basis the postulate that “function is more important than systematics”  and assep < 0.05). In the group of patients with complications, the median value of the difference of the sum of three AMMs (∆ 1–0) was more than two times higher than this level in the group without complications (p = 0.001), which can be used for monitoring and prognosis of complications in the future. It is noteworthy that 6 h after the surgery, the sum of three AMMs in patients with infectious complications (n = 26) was within 4.3 (3.0–5.7) µmol/L and did not reach high values (up to 10 µmol/L or more), as, for example, it was reported in patients with sepsis [p < 0.001).Age, gender, BMI, concomitant diseases and other initial factors of patients, as well as the general index of concomitant pathology of Charlson displayed no significant differences between the two groups of patients. At the same time, aromatic metabolites, such as 4-hydroxyphenylacetic and 4-hydroxyphenyllactic, and especially the sum of three AMMs, were significantly higher  were in the group with complications after surgery. As can be seen from It is also interesting to note that not all patients at the highest risk with acute/subacute aortic dissection (n = 79) which were operated on by one surgical team in 2021 were analyzed in our study. We purposefully selected operations on the aorta due to the greatest risk of postoperative complications, taking into account the severity of this pathology and a complex of concomitant diseases in every patient included in the study  surgeries for aortic aneurysm/dissection. In accordance with the protocol of the study, patients (he study . All patIt is important to consider that operations on the aorta in such patients with multiple risk factors are not performed in all cardiac surgery clinics, which makes it difficult to organize multicenter studies, and it is almost impossible to select a group of similar patients.The authors believe that the results of this pilot study are extremely important for understanding the mechanisms of complications. Impaired microbiota metabolism is important in the development of complications after complex reconstructive aortic surgery, which is the basis for the search for a new prevention strategy. At the time of writing of this paper, a randomized clinical trial has already begun in the same cardiac surgery center to study the effectiveness of antimicrobial prevention based on the regulation of the metabolic activity of the microbiota.The microbiota metabolism disruption is an important risk factor for postoperative complications in cardiovascular surgery, in particular, after aortic prosthetics. The degree of microbiota metabolism disruption can be assessed by monitoring the level of some AMMs circulating in the blood. It is necessary to look for the ways to adjust the metabolism of the microbiota to improve the results of surgical treatment in future by searching for replacement the compensation of its functions.


In the present work, the effect of divinylbenzene (DVB) on the kinetics of post-radiation chemical graft polymerization styrene (St) on polyethylene (PE) film and its structural and morphological features were investigated. It has been found that the dependence of the degree of polystyrene (PS) grafting on the DVB concentration in the solution is extreme. An increase in the rate of graft polymerization at low concentrations of DVB in the solution is associated with a decrease in the mobility of the growing chains of PS. A decrease in the rate of graft polymerization at high concentrations of DVB is associated with a decrease in the rate of diffusion of St and iron(II) ions in the cross-linked network structure of macromolecules of graft PS. A comparative analysis of the IR transmission and multiple attenuated total internal reflection spectra of the films with graft PS shows that graft polymerization of St in the presence of DVB leads to the enrichment of the film surface layers in PS. These results have been confirmed by the data on the distribution of sulfur in these films after sulfonation. The micrographs of the surface of the grafted films show the formation of cross-linked local microphases of PS with fixed interfaces. Synthetic membranes are heterogeneous solid phase barriers between two phases. The transport of molecular/ionic species of liquids or gases is carried out by contact with their surfaces under the influence of a driving force. Synthetic membranes can selectively transport one species of liquid or gas over another (selectivity or degree of separation) or regulate the transport of different species at different controlled rates (permeability or flux). The transport of molecular/ionic species across membranes is driven by differences in the size, shape, chemical properties, or electrical charge of the components of the mixture being separated. The separation properties of a membrane are determined by both the chemical and physical nature of the membrane materials, as well as the method of preparation .Among the various methods of ionite membrane production, grafting polymerization occupies a special place, which makes it possible to regulate their physicochemical and operational properties within a wide range ,3,4. TheIn most cases, during the synthesis of such membranes, graft polymerization of St is carried out on films of polyolefins or polyfluoroolefins, followed by the chemical modification of graft polystyrene (PS) and the production of cation-exchange membranes. Such sulfocationite membranes obtained by the sulfonation of PE films with grafted PS have high selectivity when separating mixtures of ethylene with ethane ,8 and buIn the earlier works of Chalykh et al. , we stud1H NMR (PFG NMR) demonstrate two types of water molecules in the films with low DVB contents.Of particular interest is the diffusion of water molecules, which determines the ionic conductivity . The difThe purpose of this work is to study the effect of DVB on the post-radiation chemical graft polymerization of St on the PE film, the distribution of grafted PS over the thickness of this film, the morphology of these films, and the properties of related sulfocationite membranes.3 and a thickness of 20 µm, St ; DVB ; potassium hydroxide ; iron(II) sulfate heptahydrate ; methanol .The following materials and reagents were used: high-pressure PE film with a density of 0.92 g/cmSt was purified from the inhibitor by successive treatment with an aqueous solution of potassium hydroxide and deionized water, drying, and distillation under vacuum to withdraw the boiling fraction at 40 °C at a residual pressure of 20 mmHg.60Co γ-radiation source with a radiation dose of 50 KGy and power of 5.2 Gy/s. The grafting copolymerization of St and DVB was carried out in a mixture of a methanol solution of 50 vol. % St and DVB and 50 vol. % methanol at the boiling point. The grafting solution contained 2 g/L iron (II) sulfate as a homopolymerization inhibitor and a co-initiator.The PE film was irradiated in air at room temperature under a p, %) of the copolymer of St and DVB was determined using Equation (1):m0 and m1 are the film weights (in g) before and after the grafting copolymerization stage, respectively.The degree of grafting (ΔSulfonation of the films was carried out in concentrated (96 wt. %) sulfuric acid at a temperature of 98 °C. At the end of the process, the membranes were washed with decreasing concentrations of sulfuric acid solutions and distilled water.IR transmission and multiple attenuated total internal reflection spectra were recorded using a Perkin Elmer-580 spectrophotometer . Multiple attenuated total internal reflection spectra were recorded using a KRS-5 crystal with an incidence angle of 45° and a film scanning depth of ~5 µm.gT was defined as an inflection point of the Δp(T)C curve, and the melting point value mT was defined as a maximum (peak) point. The surface area of the peak bounded by the DSC curve and zero baseline was assumed to be equal to a change in the melting enthalpy (ΔmH). To determine the glass transition temperature, we also used the tangent method [p(T).CDifferential scanning calorimetry (DSC) was used to record thermal effects accompanying the melting  and glass transition of the graft copolymer under the conditions of programmed temperature changes. The heating rate varied from 4 to 50 deg/min. Measurements were performed on a DSC 204 F1 Phoenix  in the temperature range from 25 to 150 °C in an Ar atmosphere with a flow rate of 60 mL/min. All experiments were performed using samples weighing at least 2 mg. For automatic processing of measurement results, we used the Proteus Analysis software (Version 6.1.0) in which the glass-transition temperature value t method , which wH is the melting enthalpy of the studied sample; ΔH100% is the melting enthalpy for the completely crystalline polymer; and ΔH100% = 293 J/g [The degree of crystallinity of the studied sample was determined using the following equation: 293 J/g .The structural and morphological characteristics of the graft copolymers were studied using transmission electron microscopy, scanning electron microscopy, and X-ray microanalysis. In the first case, the outer surface of the graft films was used as the object of the study, which was subjected to etching in high-frequency oxygen plasma in order to reveal the supramolecular structure. The oxygen pressure in the etching zone was 0.03 mm Hg, the electron energy was 2–3 eV, the etching time was 15–20 min, the generator power was 100 W, and the frequency was 10 MHz. The morphology of the etched surfaces was examined via the method of one-step carbon-platinum replicas using a TEM-301 transmission electron microscope  at an accelerating voltage of 80 keV.In the cases of scanning microscopy and X-ray microanalysis, studies were carried out on cross-sections of the sulfated graft PE film obtained on an LKB cryo ultramicrotome. Surface analysis was performed using a JSM-U3 scanning electron microscope  at an accelerating voltage of 5–7 keV equipped with an EDAX energy dispersive spectrometer .o-xylene absorption  was determined according to Equation (3):sm and dm are the film weights (in g) of the swollen and dry films, respectively.The S, %) in o-xylene was calculated from the surface area values of the film in the swollen state (sA) and in the dried state (dA) using Equation (4):The degree of swelling on the surface area . The magnetic field gradient pulses of amplitude g and duration δ were applied after the first and third 90° pulses. The gradient strength varied linearly in 32 steps within a range from 0.1 to 27 T/m. The integrated intensities of the spectral lines were used to obtain the dependence of the echo signal attenuation on g2 (diffusion decay) [γ is the gyromagnetic ratio, Δ is the interval between the gradient pulses, dt = Δ − δ/3 is the diffusion time, and sD is the self-diffusion coefficient. A can be expressed using the equationA(0) is the signal intensity after the first radio frequency (RF) pulse; and T1 and T2 are the spin–lattice and spin–spin relaxation times, respectively. During the measurement of the echo signal evolution, τ and τ1 were fixed and only the dependence of A on g (diffusion decay) was analyzed.The self-diffusion coefficients of water in the membranes with different DVB contents were measured for n decay) ,17. The The experimental diffusion decays were well approximated using Equation (5) by 2–3 orders of magnitude, and the self-diffusion coefficient measurement error was lower than 10%.2O5 at room temperature after they were placed in a desiccator over water vapor until a constant weight was reached. Membrane plates 3 mm × 40 mm in size were inserted in a hermetically sealed NMR tube with an outer diameter of 5 mm.For NMR measurements, the membrane samples were dried by equilibration with P2+ ions in the cross-linked network structure of the macromolecules of the grafted PS. The dependence of the degree of grafting on the concentration of DVB acquires a pronounced extreme character  (D1492/D1475) [1492/D1475 ratio, which was measured using the multiple attenuated total internal reflection method; over this ratio, which was measured using the transmission method, the enrichment of the film surface in PS occurs. Interestingly, when the degree of grafting reaches ~100%, the concentrations of the grafted polymer on the surface and in the volume of the film are leveled, which indicates the course of the grafting process throughout the entire volume of the film in spite of the formation of network structures.Since the formation of the network limits monomer diffusion in the presence of DVB, the distribution of the grafted PS over the thickness of the PE film should depend on the concentration of DVB. This distribution was investigated by comparing the ratio of the optical densities of the bands at 1492 (stretching vibrations of the C-C bond in the phenyl ring of PS) and 1475 cm2/D1475)  measured2/D1475) ,19. Indep = 34%) and high (Δp = 93%) degrees of grafting. Their concentration does not increase with an increasing degree of grafting. This suggests that DVB is consumed in the early stages of grafting polymerization. This is consistent with the fact that DVB is a more active monomer during its copolymerization with styrene [The micrographs of the surface of grafted samples  demonstr styrene .The distribution of the grafted polymer over the thickness of the PE film can be determined based on the distribution of sulfur in the film after sulfonation.The graft polymerization of St on the PE film was carried out in ,19 underThe figure shows that the surface layers of the films are enriched with sulfur. The difference between the supramolecular organization of the sulfurized PE-PS-DVB film and the binary PE-PS system is the increased nonuniformity of the sulfur distribution, the presence in the volume and on the surface of microphase particles of cross-linked DVB having clearly fixed interfaces, and the formation of the contact zone of the grafted layer with the volume of the film of extended defects and cracks, arising as a result of the formation of internal stresses of thermochemical origin. .In our opinion, the nonuniformities of the sulfur distribution are the result of structural and morphological heterogeneities in the organization of the membrane films that occur during the graft polymerization of the monomer, and the participation of polymerization products in the formation of spatially cross-linked structures of macromolecules of the grafted polymer when their fragments lose translational mobility. This induces the microgel particles to spread and coalesce in their contact zone . NeverthThus, the graft polymerization of St in the presence of DVB leads to the formation of hybrid membranes with a complex heterogeneous structure. This is also confirmed by a thermochemical analysis . Five peThus, the dispersion medium is registered: the phases of PE  on the kinetics of the post-radiation chemical graft polymerization of styrene (St) on the polyethylene (PE) film and its structural and morphological features was investigated. IR transmission, multiply attenuated total internal reflection spectroscopy, X-ray microanalysis, transmission and scanning electron microscopy, DSC, and pulsed field gradient NMR technique were applied. The graft polymerization of St in the presence of DVB leads to the formation of hybrid membranes with a complex heterogeneous structure. In the graft PS phase, microphase particles of cross-linked DVB with fixed interfaces are formed. Extended defects and cracks are formed in the contact zone of the phases. The effect of DVB on the morphology of PE films with graft PS and sulfocationite membranes obtained via the sulfonation of these films is shown. The self-diffusion coefficient of water decreases with increasing DVB content. The membrane humidity is one order of magnitude lower in the films cross-linked with DVB.


To determine the blood flow pattern of eyes before the development of type 3 macular neovascularization (MNV) by optical coherence tomography angiography (OCTA).Retrospective study.Ten eyes of 10 patients  diagnosed with unilateral Type 3 MNV who developed type 3 MNV in the fellow normal eye during the follow-up period were studied.The time of onset of type 3 MNV was defined as the time when retinal exudation was detected by OCT. The blood flow of a 3 x 3 mm or 6 x 6 mm area in the deep capillary plexus (DCP) and the outer retina (OR) including the central fovea were assessed at the onset and at 6 months prior to the onset of the type 3 MNV.All MNVs that developed in the fellow eye were type 3 MNVs. Abnormal blood flow signals in the MNVs were detected in the DCP and/or the OR by OCTA at the onset in all cases. Eight of the 10 eyes had OCTA recordings prior to the development of the MNV: 3 eyes had non-exudative MNVs only in the DCP and 5 eyes had non-exudative MNVs in the DCP and OR. The exudation appeared on the average 3.5 months after the non-exudative MNV was observed in the fellow eyes.A non-exudative MNV in the fellow eyes can already be observed by OCTA in eyes before the onset of the exudation. Knowing this will help clinicians not only how to treat these eyes appropriately but will also help in determining the origin of the MNV. A type 3 macular neovascularization (MNV), also known as retinal angiomatous proliferation (RAP), is one of the subtypes of age-related macular degeneration (AMD) with an MNV –3. It isThus, the purpose of this study was to determine the early angiogenic pattern of eyes with type 3 MNV before the development of the exudations. To accomplish this, we followed the fellow normal eyes of patients with unilateral type 3 MNV with OCTA. Our findings showed that abnormal blood vessel patterns were present even before the exudation was detected.The procedures used in this retrospective study conformed to the tenets of the Declaration of Helsinki and were approved by the Institutional Review Board of Tokyo Women’s Medical University. All patients signed a written informed consent before beginning the treatments.There were 47 patients who were diagnosed with unilateral type 3 MNV since January 2006 in the Department of Ophthalmology, Tokyo Women’s Medical University Hospital. OCTA examinations were performed on both the affected and normal fellow eyes in this group since 2016 when OCTA examinations were begun. Ten of the normal fellow eyes developed type 3 MNV during the follow-up period. Because both eyes of all of these eyes had been examined by OCTA, we were able to examine the blood flow pattern at the site of the newly developed MNV before it developed.All patients underwent fundus examination by slit-lamp biomicroscopy, color fundus photography, optical coherence tomography (OCT), and OCTA. All eyes were examined by swept-source OCT  and OCTA . The eyes were diagnosed with unilateral type 3 MNV when subretinal, intraretinal, or preretinal hemorrhages, retinal edema, and retina–retina or retina–choroid blood vessel anastomosis were present. Nine of the ten originally affected eyes was diagnosed to have a type 3 MNV by fluorescein angiography (FA) and indocyanine green angiography (IA). The remaining 1 patient did not undergo angiography due to allergy to the contrast dye, and the diagnosis was made based on other clinical results.We determined the vasogenic stage of the type 3 MNV or RAP according to the classification of Yannuzzi and associates : stage 1SS-OCT was performed with horizontal and vertical scans through the central fovea, and OCTA was performed with a 3 x 3 mm or 6 x 6 mm area including the foveal area. The onset of the type 3 MNV in the fellow eye was defined as the time of appearance of the retinal exudation in the OCT or OCTA image. The pattern of the blood flow in the DCP and OR was analyzed at the time of onset of the disease. The prior OCTA images were available for 6 months before the appearance of the exudation. These images were evaluated for the presence of abnormal blood flow signs at the site at the onset. We also determined the time from the identification of the abnormal blood flow signs to the appearance of the exudation.Ten eyes of 10 patients (4 men and 6 women) were studied. All were Japanese with a mean age of 80.4 years, a median of 82 years, and a range of 76 to 90 years. At the time of the initial examination, all patients had soft drusen in both eyes. Three eyes were at stage 1, one was at stage 2A, three were stage 2B, and three were at stage 3 RAP (type 3 MNV) in the affected eyes by the Yannuzzi classification. All patients began treatment with intravitreal injection of aflibercept into the affected eye after the diagnosis.None of the patients had retinal exudation or treatment in the fellow eyes at the time of the initial examination. At the onset of the exudation and diagnosis of AMD in the fellow eyes, the mean decimal best-corrected visual acuity (BCVA) was 1.02 (0.01 logMAR units) with a range 0.7 to 1.2.Abnormal blood flow pattern indicating a type 3 MNV was confirmed to be present in both the DCP and the OR in all cases at the onset of exudation in the fellow eye. Prior OCTA images were available in 8 of the 10 eyes, and they were recorded within 6 months before the onset of the exudation. Examination of the site of the subsequent MNV showed abnormal blood flow pattern suggestive of non-exudative type 3 MNV in both the DCP and the OR in 2 eyes (Cases 1 and 5) and only in the DCP in 3 eyes . No abnormal blood flow patterns were observed in the remaining three eyes. The average time from the detection of the nonexudative MNV to the onset of exudation was 3.5 months with a range of 2 to 6 months.We present more detailed findings in 2 of the cases, and more detailed data for both eyes of all cases in Case 3 Figs –3A 78-year-old woman was treated for type 3 MNV with a pigment epithelial detachment (PED) and cystoid macular edema (CME) in the left eye . Five moCase 5 Figs –6A 79-year-old woman began treatment for type 3 MNV with PED and CME in the left eye . One yeaDuring the follow-up of 10 unilateral type 3 MNV cases, OCTA of the fellow normal eyes that developed an MNV showed the blood flow pattern in the DCP and OR. In the 8 eyes with an OCTA recording before the development of exudation of the MNV in the fellow eye, five eyes already had a blood flow pattern suggestive of non-exudative Type 3 MNV. Interestingly, this type of blood flow pattern was detected only at the DCP in three eyes. These findings are important for determining the origin of Type 3 MNVs. In the five eyes in which nonexudative MNVs were observed, the exudation appeared at an average of 3.5 months after the detection of the MNVs in the OCTA images.Deep retinal vascular complexes were first detected in 1992 by Hartnett et al  proposedThe capabilities of OCTA have advanced by the development of new examination methods. Thus, Sacconi et al.  analyzedOn the other hand, Borrelli et al  analyzedOur results indicated that abnormal blood flow information was present in the prior OCTA images only after the appearance of exudation. Even clinically, it is difficult to determine whether the blood flow pattern can really be considered an indicator that exudation will occur. Sacconi et al  reportedAlthough the number of cases was limited, we were able to confirm that the abnormal blood flow information of non-exudative type 3 MNV in OCTA was observed in five eyes before the appearance of exudation even though three of which were identified only in the DCP. This might indicate that the type 3 MNV originates from intraretinal neovascularization in some cases. On the other hand, the detection of non-exudative type 3 MNV is difficult to determine reliably before the exudation appears, and manual in-depth evaluations of the OCT and OCTA images are necessary for the early diagnosis of type 3 MNV. In unilateral Type 3 MNV, it is important to follow the development in the fellow eye, and OCTA is a necessary examination in such cases.


Thermodynamical parameters, NBO analysis data, and HOMO/LUMO images for this compound are also presented. A good agreement between the calculated data obtained using the above three quantum-chemical methods was noticed, too.Using various versions of quantum-chemical calculation, namely four versions of density functional theory (DFT),  and two versions of the MP method (MP2/TZVP and MP3/TZVP), the existence possibility of the carbon-nitrogen-containing compound having an unusual M: nitrogen ratio of 1:20, unknown for these elements at present, was shown. Structural parameters data are presented; it was noted that, as may be expected, CN This substance is characterized by an unusual  ratio between the number of N atoms and the number of C atoms (20:1) and has a quasi-tetrahedral molecular structure. At the same time, the use of DFT methods with B3PW91 and M06 potentials both with the TZVP basis and with the more advanced Def2TZVP basis leads to practically the same results . A similar situation occurs when comparing the results of the calculations of C(N20) by the above variants of the DFT method with the results of the calculations by the MP2 and MP3 methods, the use of which is even more expensive. Thus, there is every reason to state that the DFT methods generally correctly describe the molecular structure of the compound under study, at least in a qualitative sense.As follows from the above, the presented results of quantum chemical calculations performed using six different methods, namely four DFT methods  and two MP methods , unambiguously testify in favor of the possibility of the existence of a new  chemical compound of carbon and nitrogen with the composition C(NfG0 (>2500 kJ/mol), the C(N20) [C(N5)4] compound under consideration is indeed a high-energy substance; if it is obtained experimentally, it will undoubtedly find some practical application, at least in the above capacity. Predicting the possibility of the existence of such an exotic chemical and modeling its molecular and electronic structures using modern quantum chemical calculations can serve as a very useful tool in solving the problems associated with this synthesis. On the other hand, its synthesis may be of great importance for the further development of physical chemistry and chemical technology of both its constituent chemical elements, which, as is known, play an extremely important role in nature.Judging by the very high value of ∆


Using steel plates attached with epoxy resin adhesive to strengthen prestressed reinforced concrete bridges has become a common method to increase bearing capacity in engineering because of the simple technology, low cost and good strengthening effects. The strengthening method of steel plates has been gradually applied to repair damaged bridges in practical engineering. After a cross-line box girder bridge was struck by a vehicle, the steel bars and concrete of a damaged girder were repaired and strengthened by steel plates, and then the ultimate bending bearing capacity was studied through a destructive test. The results of the destructive test were compared with those of an undamaged girder to verify the effect of the repair and strengthening of the damaged girder. The results showed that the actual flexural bearing capacity of the repaired girder strengthened by steel plates was 1.63 times the theoretical bearing capacity, 36.7% more than that of the damaged girder and 95.3% of that of an undamaged girder. The flexural cracking moment of the repaired girder strengthened by steel plates reached 66.3% of that of the undamaged girder. The maximum crack width decreased by 24.6%, and the maximum deflection increased by 2.7%, compared with the undamaged girder when the repaired girder strengthened by steel plates finally failed. Moreover, this method of attaching steel plates can increase the ductility of bridges and reduce the degree of cracking. Additionally, the actual safety factor of the repaired girder was greater than three, and it had a large safety reserve. With the accelerated pace of urban construction and the continuous rise in the number of cars, the cross-line bridge has become an essential structure to improve city traffic, relieve the pressure of urban traffic and improve the efficiency of road transport . HoweverAt present, reinforcement by steel plates is widely used because of its advantages, such as fast construction, low cost and remarkable strengthening effect, for prestressed bridges . The steWe take a prestressed concrete box girder bridge as the research object, specifically the third and fourth spans of the cross-line that were severely damaged when struck by a truck. The mechanical properties of the damaged and undamaged fourth span box girders were compared previously . The tecThe basic information of the bridge is detailed in a reference , and Fig2 of concrete fell off, and a cavity appeared in the bottom plate of the #4-2 girder. Additionally, 2 m2 of concrete were damaged 2~4.5 m from the middle span of the #3-2 girder, but a cavity of only 0.4 m2 formed. In the bottom plate of the #4-2 girder, eight longitudinal steel bars and two pretensioned strands broke. In addition to the fracture of these steel bars and pretensioned strands, three more longitudinal steel bars broke in the #3-2 girder than in the #4-2 girder. Moreover, the unbroken steel bars and pretensioned strands in the damaged areas of the two girders were exposed to air due to the loss of concrete.Due to the collision with the overhigh vehicle, the prestressed concrete box #4-2 and #3-2 girders were severely damaged. The significant modes of damage of the #4-2 girder are shown in To facilitate the transportation of the prestressed concrete box girders and the destructive tests, and considering that the overstretched flange plates of box girders had little influence on bearing capacity, the flange plates on both sides of the box girders were partially removed. The cut girders were supported simply at the girder end, as indicated in The bearing capacity of the #3-2 girder in undamaged, damaged and repaired states was calculated to determine whether it needed to be strengthened. First, the calculated section was determined before the ultimate bending capacity was calculated. Due to the adoption of a simply supported system at the girder end, the computed section of the undamaged #3-2 girder was selected as the midspan section. The calculated section was determined to be the section with the most severe damage for the damaged #3-2 girder and the repaired #3-2 girder since the damaged area was close to the midspan. In the repaired girder, the same strengths of steel bars and concrete were used to repair the broken longitudinal steel bars, stirrups and concrete of the bottom plate, and the cracks were closed. The box section was equivalent to an I-shape when the flexural bearing capacity was computed, according to the specification . Figure fsd and f′sd are design tensile strength and compressive strength of longitudinal steel bars. fpd is design tensile strength of strands. fcd is design compressive strength of concrete. As and A′s are areas of longitudinal reinforcement. Ap is section area stands. h′f and b′f are thickness and width of flanges for the equaled I-shape. h0 is the effective height. x is the height of the compressive zone. a′s is the distance between the area centroid of compression reinforcement and concrete edge.According to the design drawings, specifications and results of the appearance inspection, the calculated parameters of the #3-2 girder in undamaged, damaged and repaired states were obtained, as shown in The value of the design load effect of the prestressed concrete box girder was calculated in order to figure out if the flexural bearing capacity of the damaged #3-2 girder and repaired #3-2 girder satisfied the requirements of the current bridge design specification . Accordifsp is the design tensile strength of the steel plates. Asp is the area of the steel plates. Ap is the section area of the strands. Ψsp is the influence coefficient of the bearing capacity of the bonded steel plate when second-stage stress and cracks in the strengthened girder are considered; the value ranged from 0.85 to 0.95, according to the maximum width of the surface cracks before strengthening. Finally, ξb is the balanced relative depth of the compressive area.Considering the strengthened analysis results and field test conditions, an 8 mm thick steel plate was finally selected to reinforce the repaired #3-2 girder. The main construction steps of attaching the steel plates were as follows: First, the bottom concrete of the girder was grinded and cleaned to make the surface smooth and flat. Then, the positions of two steel plates were determined at the bottom of the girder, and they were anchored with Q345 high-strength anchor. Glue was spread between the steel plates as well as the concrete using the pressure glue injection method to firmly bond the two surfaces. Finally, the steel plates were brushed with protective paint to prevent corrosion.To predict the change in the ultimate bearing capacity and mechanical properties of the repaired #3-2 girder strengthened by steel plates during the destructive process, and to compare the difference between the undamaged #3-2 girder and the damaged #3-2 girder, a model of the #3-2 girder in undamaged, damaged and repaired states was established by ABAQUS for a detailed analysis . The modThe process of modeling the repaired #3-2 girder strengthened by steel plates was basically the same as that of modeling the undamaged girder. The difference was in the simulation of broken pretensioned strands and strengthened steel plates. The broken pretensioned strands in the strengthened box girder were divided into two parts. Some of the strands were well bonded to the concrete, and they were regarded as the longitudinal steel bars. The temperature field was not applied, and the embedding function was used to constrain the strands with the concrete. The other strands separated from the concrete, and they were modeled using the life and death unit method. That is, the Model Change function in the software was used to passivate the prestress as it was applied. A four-node curved shell element was used to establish the strengthened steel plate model, and the stress–strain curves of the steel plates are shown in The modeling of the damaged #3-2 girder was based on the model of the repaired #3-2 girder strengthened by steel plates. The main difference between them was that the simulation of the damaged #3-2 girder did not include reinforced steel plates, but the simulation included the spalling of damaged concrete and broken longitudinal steel bars. According to the actual condition of the damaged 3-2# girder, the damaged concrete spalled and the broken ordinary steel bars were cut, and the Model Change function of ABAQUS was used to model them. The model of the damaged #3-2 girder is shown in The deformation of the undamaged #3-2 girder was approximately 2.6 mm in each stage loaded with 50 kN, the deformation of the repaired #3-2 girder strengthened by steel plates was approximately 2.2 mm in each stage loaded with 40 kN and the deformation of the damaged #3-2 girder was approximately 3.3 mm in each stage loaded with 40 kN in the elastic stage. This indicated that the stiffness of the undamaged #3-2 girder in the elastic stage after being struck by a vehicle decreased by as much as 36%, but after being strengthened by steel plates, the girder that was injured had a 50% improvement in stiffness. The undamaged #3-2 girder’s cracking load was 361 kN, while the damaged #3-2 girder’s cracking load was 200 kN, or 44.6% less than the undamaged #3-2 girder’s cracking load. The cracking load of this repaired #3-2 girder strengthened by steel plates was 265 kN, which was 32.5% more than that of the damaged #3-2 girder, but there was still a large gap between the undamaged #3-2 girder, indicating that strengthened steel improved the cracking performance of the structure, but the improvement range was limited. When the load was increased to 875 kN, the concrete at the top of the undamaged #3-2 girder was crushed. The damaged #3-2 girder’s failure load was 552 kN, which was 36.9% less than that of the undamaged #3-2 girder. The failure load of the repaired #3-2 girder strengthened by steel plates was 840 kN, which was 52.2% more than that of the damaged #3-2 girder but 4% less than that of the undamaged #3-2 girder.According to the refined analysis, To explore the recovery degree of the flexural capacity and the failure process of the repaired girder strengthened by steel plates, the repaired #3-2 girder strengthened by steel plates and the undamaged #4-1 girder were selected for a destructive test. Limited by the test site and conditions, three loading points were set for the destructive test of the repaired #3-2 girder strengthened by steel plates and the undamaged #4-1 girder, which were loaded by three jacks with a peak output force of 2000 kN. The distance between adjacent loading points was 4.0 m, and The loading procedure used the hierarchical loading method and was divided into three loading stages. First, the girder was loaded to 70% of the predicted value of the cracking load of the undamaged #4-1 girder and then unloaded. The second load was applied to 85% of the predicted value of the ultimate load and then unloaded, and the third load was loaded until the girder was damaged. During the loading of the undamaged #4-1 girder, 50 kN was applied at each stage. Considering that the repaired #3-2 girder strengthened by steel plates was repaired and strengthened based on the damaged girder, the load step was adjusted from 50 kN to 40 kN to ensure the safe and smooth progress of the test. When the load of each jack exceeded 450 kN, displacement control was employed to deliver the load until the box girder was damaged.The strain and deformation measurement points were arranged at the key section of the repaired #3-2 girder strengthened by steel plates and the undamaged #4-1 girder. To facilitate comparison and analysis with the load test results of the undamaged #4-1 girder, the web strain measurement points, bottom displacement measurement points and bottom steel bar strain measurement points of the repaired #3-2 girder strengthened by steel plates were consistent with those of the undamaged #4-1 girder. The concrete strain measurement points on the bottom plate were slightly adjusted. The cracking moment and the actual ultimate flexural capacity of the box girders was calculated from the sum of bending moments by the combination of cracking load, actual failure load and dead load, and then compared with the theoretical value of the material’s design strength and the predicted value derived from the finite element analysis, as shown in To further research the effect of the strengthening measures by steel plates for the improvement of the bearing capacity of the damaged girder and the degree of the recovery of the bearing capacity to the level of the undamaged #4-1 girder, the girders were compared and analyzed in terms of their flexural stiffness, flexural deformation and stress and crack width in accordance with the load combination given in the specification. Because the destructive test was performed after the girder had been strengthened with steel plates, the destructive test of the damaged #3-2 girder was lacking. However, according to research on the damaged #4-2 girder , which fThe flexural stiffness of bridges is an essential index used to assess the ability of bridges to resist deformation. Bridge damage is often accompanied by stiffness degradation, which can indirectly reflect the damage in the process of the bridge destructive test. According to the destructive test of the repaired #3-2 girder strengthened by steel plates, the undamaged #4-1 girder and the refined analysis of the damaged #3-2 girder, Basis on the refined analysis of the damaged #3-2 girder and the destructive test of the undamaged #4-1 girder and the repaired #3-2 girder strengthened by steel plates, Basis on the refined analysis of the damaged #3-2 girder and the destructive test of the undamaged #4-1 girder and the repaired #3-2 girder, Basis on the refined analysis of the damaged #3-2 girder and the destructive test of the undamaged #4-1 girder and the repaired #3-2 girder, To verify the recovery degree of the bearing capacity of the repaired #3-2 girder strengthened by steel plates, three standard vehicle loads were considered, i.e., three-axle, five-axle and six-axle vehicles. Then, the maximum bending moment effect under the combined action of the vehicle load, secondary load and dead load was obtained and compared with the flexural capacity of the repaired #3-2 girder strengthened by steel plates, the damaged #3-2 girder and the undamaged #4-1 girder to calculate the safety factor of the vehicles, as shown in The damaged #3-2 girder of an in-service prestressed concrete bridge with continuous girders was obtained by demolishing, repairing and strengthening. A destructive test of the strengthened #3-2 girder and the undamaged #4-1 girder was performed. Refined f analysis was conducted on the repaired #3-2 girder strengthened by steel plates, the undamaged #4-1 girder and the damaged #3-2 girder. The ultimate bending capacities of the three girders were compared and analyzed, and the following conclusions were drawn.(1)The ultimate flexural bending capacities of the repaired #3-2 girder strengthened by steel plates and the undamaged #4-1 girder were obtained from a destructive test, and that of the damaged #3-2 girder was obtained by a refined analysis. The actual flexural bearing capacity of the repaired #3-2 girder strengthened by steel plates was 1.63 times the theoretical bearing capacity, which was calculated according to the specification , and 36.(2)The analysis showed that compared with the damaged #3-2 girder, the cracking moment of the repaired #3-2 girder strengthened by steel plates was 12.5% less, the stiffness in the elastic stage was 6.6% more and the maximum deformation was 9.2% less. Compared with the undamaged #4-1 girder, the cracking moment of the repaired #3-2 girder strengthened by steel plates reached 66.3%, the maximum crack width decreased by 24.6% and the stiffness in the elastic stage reached 94.3%. When the repaired #3-2 girder strengthened by steel plates finally failed, the maximum deflection was 2.7% more than the undamaged #4-1 girder. This showed that repaired and strengthening the damaged #3-2 girder improved the ductility, reduced the degree of cracking and increased the durability. Additionally, these results showed that first repairing the damaged #3-2 girder and then strengthening it with steel plates was an effective maintenance and strengthening measure.(3)The finite element numerical analysis method based on the material testing results of the bridge reflected the mechanical properties and destruction process of the repaired #3-2 girder strengthened by steel plates and the undamaged #4-1 girder. The load vs. deformation curves obtained by this method were basically consistent with those of the failure test. The bearing capacities of the repaired #3-2 girder strengthened by steel plates and the undamaged #4-1 girder were accurately determined, and the errors with respect to the actual bearing capacities were 2.5% and 3.9%, respectively.(4)Through destructive tests and a refined analysis, some conclusions about the repaired #3-2 girder strengthened by steel plates, damaged #4-2 girder and undamaged #4-1 girder were drawn. However, the improvement of the bearing capacity of an undamaged girder after strengthening has not been explored. Therefore, the destructive test and comparative analysis of the undamaged girder strengthened by CFRP will be carried out in the future.